U.S. patent application number 15/317933 was filed with the patent office on 2017-05-11 for material processing methods and related apparatus.
The applicant listed for this patent is Hybrid Manufacturing Technologies Limited. Invention is credited to Peter Coates, Jason B. Jones.
Application Number | 20170129180 15/317933 |
Document ID | / |
Family ID | 54834505 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170129180 |
Kind Code |
A1 |
Coates; Peter ; et
al. |
May 11, 2017 |
MATERIAL PROCESSING METHODS AND RELATED APPARATUS
Abstract
The application describes a machine tool adapted and arranged to
carry out removal and addition of material on a work piece located
in a work station, the machine having a first head arranged to
remove material from the work piece and at least a second head
arranged to process the work piece, each of the first and second
heads being arranged to be moveable in at least two axes and
preferably in 3, 4 or 5 axes and wherein the machine is arranged to
control an environment of the work station. The work station is at
least partially sealable. The machine has a clean side and a dirty
side. Novel processing heads particularly adapted for use in the
new machine tool are disclosed. These may also be retrofitted to
CNC machines. The novel heads include heads adapted to carry out
two processes simultaneously. Heads adapted to carry out heat and
pressure treatment are also disclosed. Use of the processing beads
to carry out analysis in manufacturing steps is disclosed as is the
provision and use of heads that can carry out analysis as well as
processing.
Inventors: |
Coates; Peter; (Sutton
Coldfield, GB) ; Jones; Jason B.; (Fairview,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hybrid Manufacturing Technologies Limited |
Leicestershire |
|
GB |
|
|
Family ID: |
54834505 |
Appl. No.: |
15/317933 |
Filed: |
June 9, 2015 |
PCT Filed: |
June 9, 2015 |
PCT NO: |
PCT/GB2015/051689 |
371 Date: |
December 9, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 64/25 20170801;
B23P 23/04 20130101; B23Q 3/15539 20161101; Y10T 409/30392
20150115; B23C 1/08 20130101; B22F 2999/00 20130101; B23Q 3/15506
20130101; B23Q 1/012 20130101; B23C 1/002 20130101; Y02P 10/25
20151101; Y10T 483/1736 20150115; B29C 64/371 20170801; B23K
26/0093 20130101; B23Q 11/0825 20130101; B22F 3/1055 20130101; Y10T
483/1795 20150115; B23Q 2220/008 20130101; Y10T 409/307168
20150115; B22F 2003/1056 20130101; B33Y 30/00 20141201; Y10T 483/17
20150115; Y02P 10/295 20151101; B23Q 11/0891 20130101; B23K 26/342
20151001; B23Q 11/0046 20130101; Y10T 409/308288 20150115; B23Q
1/0009 20130101; Y02P 80/40 20151101; Y10T 483/1845 20150115; B23Q
17/00 20130101; Y10T 483/115 20150115; B22F 2999/00 20130101; B22F
3/1055 20130101; B22F 2202/03 20130101 |
International
Class: |
B29C 67/00 20060101
B29C067/00; B23Q 11/00 20060101 B23Q011/00; B23K 26/342 20060101
B23K026/342; B33Y 30/00 20060101 B33Y030/00; B23K 26/00 20060101
B23K026/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 2014 |
GB |
1410229.7 |
Jul 18, 2014 |
GB |
1412843.3 |
Dec 31, 2014 |
GB |
1423407.4 |
Apr 10, 2015 |
GB |
1506154.2 |
Claims
1. A machine tool adapted and arranged to carry out removal and
addition of material on a work piece located in a work station, the
machine having a first head arranged to remove material from the
work piece and at least a second head arranged to process the work
piece, each of the first and second heads being arranged to be
moveable in at least two axes and preferably in 3, 4 or 5 axes and
wherein the machine is arranged to control an environment of the
work station.
2. The machine tool of claim 1, wherein the machine comprises a
clean side and a dirty side.
3. The machine tool of claim 1, wherein the first head is
selectable from a plurality of first interchangeable processing
heads and the second head is selectable from a plurality of second
interchangeable processing heads and wherein the first
interchangeable processing heads are storable in a first tool
changer and the second interchangeable processing heads are
storable in a second tool changer.
4. The machine tool of claim 3, wherein the first and the second
tool changers are remote from the work station.
5. The machine of claim 1, wherein the work station comprises a
chamber that is, at least in part, sealable.
6. The machine tool of claim 5, wherein the chamber is partially
open and is provided with a local shielding locatable around the
work-piece during processing.
7. The machine tool of claim 5, wherein an environment in the
chamber is controllable and may be provided with at least one of:
at least a partial inert gas atmosphere a low oxygen atmosphere; a
coolant; a pressure above ambient pressure; a pressure below
ambient pressure; a vacuum.
8. The machine tool of claim 1, further comprising a waste
extractor.
9. The machine tool of claim 1, wherein the machine further
comprises an integral docking system, preferably having a supply
manifold located on one or each carriage and arranged to connect
with a receiving manifold on the processing head.
10. The machine tool of claim 9, wherein the docking system is
arranged to provide a clean connection between a supply docking
manifold on the machine and a receiving manifold on the processing
head.
11. The machine tool of claim 9, wherein the docking system is
arranged to be able to supply material and energy to the or each
processing head in use.
12. The machine tool of claim 11, wherein the media is supplied to
a reservoir in the processing head or is continuously supplied to
the processing head.
13. The machine tool of claim 9, wherein energy is supplied to the
processing head by a laser beam or by a fibre optic cable and
wherein the energy source is preferably integral to the
machine.
14. The machine tool of claim 1, wherein the machine comprises one
or more heads arranged to monitor and/or analyse at least one of
the work-piece and a processing head.
15. A method of creating an article using a machine tool having a
work station and at least one tool changer remote from the work
station, the method comprising using a first processing head,
having a first deposition characteristic, to lay down material
having a first set of properties on a work piece in the work
station; changing the first processing head for a second processing
head selected from the tool changer, the second processing head
having a second deposition characteristic different from the first;
laying further material down having a second set of properties. in
which the machine tool holding the processing head automatically
changes the processing head from the first head to the second head
and the second deposition characteristic is arranged to improve the
fidelity of the article being created to the desired article
16. The method of claim 15, wherein the second deposition
characteristic varies one or more of the following parameters when
compared to the first deposition characteristic: angle of
deposition (relative to the build surface); type of material;
mixture of materials being deposited; deposition rate; bead size;
cross-sectional shape of deposition; energy input; nano/micro
characteristic of material; colour and transparency of material;
texture of the surface finish
17. The method of claim 15, wherein the article is created in
stages such that at least one of the first and second processing
heads are used a plurality of times.
18. The method of claim 15, wherein a third processing head is used
and arranged to remove material from the article.
19. The method of claim 15, wherein the machine tool further
comprises a controller and the controller is arranged to control
the first processing head to deposit material and is then arranged
to select a second processing head dependent on the material
deposited and the work piece to be created.
20. The method of claim 19, wherein the controller uses data from
the first or the second processing head to select a further
processing head to be utilised.
21-72. (canceled)
Description
[0001] This invention relates to a method of processing materials
and to an apparatus for carrying out the method. In particular the
method and apparatus relate to additive manufacturing and CNC
machining.
[0002] Additive manufacturing (AM) is a technology in which
articles, or at least portions thereof, are manufactured, repaired,
or the like, by adding material this may be via stand alone 3D
printer, dedicated AM system or deposition using a robot, machine
tool, or the like. Suitable apparatus for the provision of such
additive manufacturing is shown in WO2014/013247 in the name of Ex
Scintilla Ltd.
[0003] Material removal techniques, such as milling, and the like
are also well known. Typically such material removal can be
facilitated through the use of Computer Numerically Controlled
(CNC) machines which automate the material removal process.
[0004] AM and CNC can be combined such that an article can be
fabricated or repaired using AM and finished by having the surface
processed using material removal, such as CNC material removal and
this process is illustrated with reference to FIG. 1.
[0005] It is known to use a machine having a number of heads
permanently connected to the tool and selectable to work on a work
piece. Such arrangements increase the bulk and volume occupied by a
machining head which restricts operation of the machining head. It
is also known to It is also known to move a work piece from one
work station to another which each work station carrying out a
specific operation including additive steps and post deposition
treatment and cutting.
[0006] It is known to provide arrangements that provide processing
heads that can be fitted to existing machine-tools, such as
multi-axis CNC milling machines. However the capabilities of such
prior art processing-heads can be expanded as may be desired and
improved heads are described in published application number
WO/2014/013247, and also in unpublished application numbers: GB
1412843.3 and GB1423407.4 from which this application claims
priority.
[0007] In the previous machines a suitable head has been designed
and used in existing CNC machines as described in the previous
applications. However it has been appreciated that disadvantages
exist where an existing machine tool designed for milling is used
for additive manufacturing. These disadvantages can be
characterized in that milling machines are intended for shaping the
outward surface of a part only. This is not surprising since the
internal characteristics of the part are determined by the
preparation of the starting billet from which a part is cut. The
addition of material during additive manufacturing or 3D printing
not only shapes the outward surface, but also forms key
characteristics of the inward volume of the part (including
microstructure) as it is made. As such it is desirable to be able
to maintain the cleanest environment possible to avoid defect
introduction during the build. Furthermore, to be able to provide
quality assurance it is desirable to assess the internal volume of
a part (including microstructure) as well as the surface topology
and chemistry at nano, micro, meso and macro scale as the part or
product is made in real-time or at least in sitiu.
[0008] According to a first aspect of the invention there is
provided a machine adapted and arranged to carry out removal and
addition of material on a work piece located in a work station, the
machine having a first device arranged to remove material from the
work piece and a second device arranged to process the work piece,
each of the first and second devices being arranged to be moveable
in at least two axes.
[0009] In some embodiments the first and second devices may each be
moveable in 3, 4 or 5 axes.
[0010] Preferably the first device is a mechanism which comprises a
first carriage on which a plurality of interchangeable delivery
heads are processing heads which can be removably mounted in use
and the interchangeable processing heads being storable in a first
tool changer. Desirably the second device is a mechanism which
comprises a second carriage on which a plurality of interchangeable
delivery heads which are processing heads and machining heads which
can be removably mounted, the removable processing heads for the
second device being storable in a second tool changer.
[0011] The applicant has developed new and improved processing
heads and methods of using those heads in existing machines. The
applicant has also realized that the processing heads may be
particularly useful in a machine specifically designed to take
advantage of the features of the heads and the methods of using the
heads that have been developed.
[0012] It will be appreciated that the processing head either be
arranged to remove material from the work piece or may be otherwise
arranged to process the work piece by addition or deposition of
material or may be arranged to inspect or monitor the work piece.
Such heads may be loosely referred to as processing heads. In some
cases it will be appreciated that the processing head may be
arranged to process the work pieces by heat treatment and may
remove some of the material of the work piece in the processing.
Other processing heads are arranged to remove material from the
work piece.
[0013] Desirably each tool changer has a number of processing heads
stored therein. The first tool changer preferably stores processing
heads designed to remove material from a work piece.
[0014] Such heads may be arranged to carry out milling, grinding,
planning, boring, ablation, machining and other material removal
processes as are well known in the art. The machining may be laser
assisted and the processing head may utilise coaxial laser delivery
or off-axis laser delivery.
[0015] The second tool changer preferably stores processing heads
designed and arranged to process material on a work piece. Such
heads are described in the earlier applications referred to above
and include heads arranged to process the material of the work
piece such as by depositing or modifying material or inspecting,
detecting or marking the work piece being created such as with a
galvo laser, cladding such as with a laser cladding head or a
90.degree. laser cladding head, deposition such as by extrusion of
a material including a 90.degree. extrusion head, heat treatment,
hammering, scarifying, shot blasting, peening or micro-peening,
needle peening, laser peening or rolling. The heads may be arranged
to carry out induction heating, metal inert gas welding (MIG
welding), plasma arc transferred welding (PTA welding), apply a
vacuum; to blow air onto the work piece; carry out laser assisted
machining; apply a coating to the work piece such as with HVOF
coating or use electrical discharge machining (EDM). The heads may
also be arranged to lay down material using 3D manufacturing
processes. Additionally the second tool changer may contain heads
may be any one or more of the following: an image recording
apparatus; lighting, either fixed or moving; touch probes; 3D
surface (including laser and structured light varieties) and
volumetric scanners, including confocal, focus variation,
interferometry and structured light scanners; photogrammetry
systems, sensors (such as oxygen sensors; thermal sensors; thermal
cameras) eddy current generators, ultrasound transducers (for air,
gel, and liquid coupled), electromagnetic wave generators,
induction heating coils, electromagnet(s), a magnification device
such as confocal microscope, incremental sheet forming tools, heat
gun, vacuum, induction heater, galvanometer, oscilloscopes, digital
mirror devices, structured light scanners, grinders, abrasives,
right angle variations of heads, microscopes, confocal or variable
microscopes, electromagnetic detectors including gamma and X-ray,
spectrographs, etc.
[0016] Preferably each tool changer is adapted to store from 5 to
50 heads, or more preferably from 10 to 40 heads or most preferably
from 25 to 35 heads. It will be appreciated however that as in
common practice a tool changer can be expanded to store more heads
if required.
[0017] Preferably the respective tool changers store the processing
heads remote from the work piece. Such storage of the heads in a
remote location from the work piece allows a larger number of heads
to be stored and to be available for selection as well as prevents
them from becoming contaminated from the work piece. Additionally
as only the "in use" head is attached there is a greater range of
movement available to the head relative to the work piece.
[0018] In a preferred embodiment the first carriage is parked while
the second carriage is in use and vice versa.
[0019] Preferably the machine comprises a body having a clean side
and a dirty side. Each side may comprise a chamber that may be
sealable. Preferably at least the clean side comprises a sealable
chamber. The clean side may comprise a chamber, such as a tool
changer, in which clean heads are stored. The dirty side may
comprise a chamber such as a tool changer, in which "dirty" heads
are stored. Such "dirty" heads may be used for removal of material
from a work piece. The first and second tool changers are
preferably remote from the work station.
[0020] Desirably the machine is arranged to control an environment
of the work station
[0021] Desirably the work station is located between the clean side
and the dirty side. In a preferred embodiment the work station is
at least semi protected. The work station may be provided in a
chamber. The chamber may be sealed or may be sealable or partially
sealable.
[0022] It may be possible to change an environment in the chamber
of the work station to be a clean environment depending on the
process being carried out. In some embodiments the work station may
be provided in a chamber that can be flooded with an inert gas such
as argon or nitrogen. In some embodiments the atmosphere in the
chamber may be controlled to have a low oxygen content and/or to
have a low level of particle contamination. An inert gas may flow
through the chamber. In other embodiments the chamber may be
sealable, and the work piece may be submerged in an inert gas. The
inert gas may also be provided as a coolant.
[0023] In some embodiments the carriage may provide a means of
supplying fluid to the chamber or to the work piece. The fluid may
be a gas. The gas may be inert and/or may be acting as a coolant.
In some cases the gas may assist in extraction of waste material.
In other cases an inert atmosphere may be provided and a coolant
gas may be supplied to the work piece in addition. Where the work
piece is submerged in an inert gas, any waste material or coolant
extraction preferably rises above the level of the inert gas so
that upon extracting coolant and waste material, the inert gas is
not expelled from the chamber. A waste extraction means may be
provided. In a preferred embodiment an extraction point is provided
which is connected to a duct in the machine. Preferably waste is
removed by means of an Archimedes screw operating in the duct. This
arrangement preferably extracts the coolant straight up the centre
of the screw and out of the chamber, yet always leave a column of
inert gas and fluid in the duct, which would provide a natural
airtight barrier between the chamber and the atmosphere.
[0024] It is desirable to manage heat in the work piece. As
material, particularly metal, is deposited the work piece gains in
heat and this can cause problems such as distortion of the final
part.
[0025] It is possible to manage heat in the work piece by
alternating between deposition of metal and machining of the metal
with a coolant. At least a part of the heat in the work piece
transfers to the coolant which may be a gaseous or liquid cutting
fluid. It will be appreciated that this method of operation is
effective and can maintain the work piece at a temperature below
approximately 1/3.sup.rd of the melting point of the material,
which maintains a level of stability in most materials. Such an
alternation in steps may not be the optimal sequence for maximum
productivity but does manage the temperature of the work piece and
may be used in existing machine tools that are retro fitted with
processing heads.
[0026] In some embodiments the chamber may be at least partially
sealable. It is desirable in managing heat in the work piece that
the work station is liquid cooled. Typically the work piece will be
held in a work holding device on a platform in the work station.
The platform or at least the work holding device may be cooled with
a cooling liquid or gas such that heat generated by material
deposition on the work piece is removed through conduction to the
work holding device and into the cooling system. Advantages have
been found in that the cooling enable higher work cycles to be
maintained for deposition. Additionally the machine is insulated
from the heat of the work piece which helps axes of the machine to
maintain the accuracy that they are designed to hold and prevent
damage due to thermal expansion of moving parts.
[0027] In other embodiments the chamber may be sealable and a
vacuum may be applied to the sealed chamber such that material
processing is carried out in a vacuum or under a pressure reduced
from atmospheric. Alternatively it may be desirable to increase the
pressure in the chamber above atmospheric pressure.
[0028] In some embodiments the chamber may be unitary on at least
two, three, four or five sides. A lid or other sealing mechanism
may be provided to seal the chamber. In other embodiments a sealing
door may be provided. Preferably means for introducing a gas or
applying a vacuum is provided in at least one face of the chamber
or door.
[0029] In other embodiments the chamber may be partially open and
may be provided with a local shielding. Such local shielding may be
expelled openly, or preferably may be confined by using a bag, such
as a plastic bag, or a skirt that can be located around the work
piece during processing. The skirt could be supported on a plunger
and the locating of the skirt around the work piece may be
automated.
[0030] In a preferred embodiment the first and second devices are
moveable in at least x, y and z axes. In a preferred embodiment the
devices are slideable in at least one of the x, y and z axes.
[0031] Preferably one of the slideable axes is in the x directions
and a rail is provided which is common to the first and second
devices. In some embodiments the first and second carriages are
each mounted on respective first and second supports. The first and
second supports are preferably each slideable in the rail so
providing movement to the first and second carriages in the x
direction. In a preferred embodiment each carriage is moveable in
the z direction relative to the support. Desirably the movement of
the first and second carriages on the first and second supports in
the y direction is parallel.
[0032] In some embodiments the machine may be provided with further
variation by control of orientation of a platform supporting the
work piece. The platform may be fixed providing flat table or may
be rotary or may in some cases be arranged to tilt as well as
rotate.
[0033] The platform and the chamber are advantageously arranged to
accommodate a work piece having a size as known in the art of
machine tools.
[0034] Typically the machine is cuboid and overall size the
footprint of the machine is from 1 m to 5 m or more preferably from
2 m to 4 m or most preferably about 3 m.
[0035] The machine is preferably optimized for high speed machining
of light passes since the amount of heavy cutting, traditionally
known as "roughing" would be reduced due to the addition of
material which is near-net of the target shape and therefore a work
piece will require mostly "finish machining".
[0036] Historically many of the processing and removal heads used
to date have utilised a side docking system.
[0037] Preferably the machine provides an integrated docking
system. The integrated docking system may deliver material and
energy to a processing head on the first or second carriage which
may be arranged to remove material from the work piece or may be
arranged to process the work piece.
[0038] In a preferred embodiment the docking system is arranged to
provide a clean connection between a processing head and the
docking manifold on the machine. An operable seal may be provided
on both halves of the mating manifold. Furthermore portions of the
head which are sensitive to contamination, such as the optical
windows for laser energy may be covered by a sliding or rotating
door which is only opened after the head manifold and dock manifold
mate, thereby eliminating the opportunity for contaminants to
accumulate on said sensitive areas when the head or dock are in a
storage position. Also, positioning of an air knife may be used to
blow off any contaminants after the doors are closed to ensure the
powder ports and other docking manifold connections may be kept
clean.
[0039] Material delivered to the processing head may be in the form
of powder, fluid, or filaments. In some embodiments the material
may comprise a polymer material. In other embodiments the material
may be selected from a group comprising metals, non-metals,
polymers, ceramics, clay, salts, conductive, capacitive or
dielectric materials, in powder form, filaments, rods, fibers
(short, chopped, long, or continuous) sheets, or wires, in solid or
semi- to fully liquid form. Alternatively materials can be provided
in suspension in a liquid, emulsion, gas, aerosol or paste. In
combination with a matrix material continuous or discontinuous
fibres may also be deposited to form a composite material. In a
preferred embodiment the media may comprise a polymer pellets or
filament. Typically such a feedstock may be heated by an energy
source to a temperature such that the material can be fed,
directed, extruded, jetted or otherwise deposited in a controllable
manner. Alternatively a fluid material may be supplied to the
processing head from a media reservoir which may be provided in the
machine. The material may be heated by an energy source till all
the material in the reservoir is fluid and can be extruded in a
controllable manner. In some embodiments the material may also
comprise conductive, semi-conductive, capacitive, piezoelectric and
dielectric material such that electric circuits can be laid down
during formation of the work piece.
[0040] In another preferred embodiment the media may comprise
metals which may be provided in the form of powders or wires. Such
metals may be used in forming the body of the work piece or may be
applied to a part of the work piece in order to lay down electronic
circuits.
[0041] A particular advantage of the machine is that a wide variety
of heads may be provided and these are able to deposit material so
as to produce work pieces complete with embedded electronic,
biological and other functional subsystems.
[0042] It is envisaged that the machine may be used for making
prototypes, end use products and entire products.
[0043] In a preferred embodiment the integrated docking system is
arranged to be able to supply material and energy to the processing
head when required. Preferably the laser energy required for
processing is delivered parallel to the z axis, but from a point
removed from the close proximity to the working area. It will be
appreciated that advantages arise as the laser beam path can be
direct and so the laser power that can be delivered is reduced less
because of the few reflectors and optics than with side docking
delivery of laser power which necessitates the use of mirrors in
the beam path.
[0044] In one preferred embodiment the docking may be provided on a
top face of the processing head and the integral docking in the
carriage is arranged to align and to mate with a manifold on the
carriage with the processing head.
[0045] In other embodiments a manifold and docking means may be
provided in a collar of the carriage. The carriage may comprise a
spindle arranged to be moveable in the z direction and the docking
manifold may be provided on a collar of the spindle.
[0046] Provision of an integral energy source in the machine has a
number of advantages. In some embodiments the energy source may be
by means of a beam targeted on the work piece.
[0047] Control means can be provided to control the applied beam of
energy and the source may be selected from lasers, such as
infra-red lasers, visible light lasers and UV lasers. Pulse
durations may be controlled to vary from an attosecond (as) up to
femtosecond (fm) and so on up to continuous wave (CW) durations.
The energy source selected may be chosen depending on the process
being carried out--whether removal, addition or alteration of the
material. The energy source and pulse duration may also be selected
to optimise absorbance of the energy by the material to be
processed. A beam switch may also be used for changing between
different laser beams sources.
[0048] In some embodiments the energy source may be supplied to the
work piece or to the processing head, particularly a processing
head, using a fibre optic cable arranged to be carried by the
carriage to the processing head. It will be appreciated that in
some cases a hollow core may be required due to the energy
density.
[0049] As has already been discussed the machine has a clean side
and a dirty side and the work piece can be located in a chamber.
Preferably the processing heads or deposition heads are maintained
in a clean condition. It will be understood that contamination of
the work piece in the course of deposition or processing of the
work piece can lead to poor quality finishes or imperfections in
the material. Accordingly it is important to maintain the
processing heads used on the clean side without contamination or to
minimise contamination that can occur.
[0050] Preferably the machine and particularly the processing heads
are cooled using a cryogenic cooling system. In a particularly
preferred embodiment an organic coolant is used which evaporates,
vaporizes, flatulises or otherwise combusts to form products with a
very low ash content and which leave no residue behind. It will be
appreciated that other coolants may be used such as liquid
nitrogen.
[0051] In some embodiments the coolant may be supplied to the
chamber or the coolant may be supplied to the work piece or to the
processing head.
[0052] The clean side can be maintained by providing seals between
the chamber and the clean tool changer. Any processing heads used
for deposition or processing may be stored in the second tool
changer and the second tool chamber may be suitably sealed.
Processing heads used for milling do not need to be kept in a clean
environment and are stored in the first tool changer when not in
use. As the first tool changer is on the "dirty" side the first
tool changer does not need to be sealed from the chamber or the
work piece.
[0053] In a particularly preferred embodiment the machine is
provided with duplicated supports and carriages arranged to move in
the z direction. In some cases the supports and carriages are the
same. In other cases it may be preferable to provide specialised
docking and manifolds on each of the supports and respective
carriages. As discussed above one of the supports and carriages is
used exclusively for clean processing and the other support and
carriage is used exclusively for "dirty" processes.
[0054] Preferably docking of the heads on the carriage and support
is arranged to maintain a clean environment. Preferably the optics
of laser processing heads are not exposed to the air and are
maintained in a clean environment at all times. In some embodiments
an automated cover system is provided whereby actuation of a cover
on the dock opens a corresponding door on a selected processing
head. Once docking of the head on the carriage has been completed
the system is sealed. Automation of the docking process allows the
process to occur with out visual inspection being required. It will
be appreciated therefore that a machine equipped with an automated
docking and not requiring visual inspection may use higher power
lasers since it is no longer necessary to provide laser safe
windows for inspection.
[0055] In some embodiments the environment may be maintained as a
clean environment by the use of air knives and air purging. This
may be particularly desirable around the areas used for head
changing and for docking of the head with the carriage.
[0056] It is desirable that the second processing heads are
maintained in a clean environment during storage in the second tool
changer. Preferably a separate storage area is provided for
processing heads. In some preferred embodiments the processing
heads may be reversed into the tool changer such that a face of the
processing head is sealed against a surface of the tool changer
pocket.
[0057] Another important area is control of powder used in additive
manufacturing of the work piece. Typically powder is applied to the
surface of the work piece. Commonly it is a problem that some of
the powder will not be retained on the work pieces. In some cases
there will be overspray.
[0058] Desirably the machine comprises a waste extractor. This may
be used to remove swarf from the bottom of the working area where
it accumulates with the cutting fluid. Additionally, fumes and
humidity may be removed from the working area using appropriate
filtration, extraction and dehumidification. Such an air
filtration/de-humidifying system prevents airborne contaminants and
humidity from affecting the cleanliness of the working area.
[0059] In a preferred embodiment there is integrated capture of the
overspray powder. In some cases a tray may be provided in the
machine that can be slid into the chamber to capture overspray
powder. Preferably material captured by the tray can be collected
and may be re-used directly or may be reconditioned and re-used.
Some material may escape the powder collection tray.
[0060] Such material is typically removed from the chamber with the
coolant and may be filtered from the coolant and re-used.
[0061] An important aspect of the machine is the provision of
integral monitoring of the work piece and the processing head or
heads.
[0062] In known systems in which a work piece is milled or cut or
processed by removal of material the work piece is typically
considered to be of good quality. However in additive manufacturing
it has been realised that it is important for quality of the work
piece to ensure that the processing has been carried out to a high
standard to ensure that any additive manufacturing good quality. It
is important therefore to monitor the processes and the work piece
to ensure that any imperfections are detected.
[0063] Preferably at least one of the following monitoring methods
may be provided on the machine. The melt pool in processing or
additive manufacture may be monitored. A thermal history of the
work piece may be monitored and recorded using thermal cameras.
Oxygen sensors may be provided in the chamber. Spectrocscopy may be
used to analyse parts of the work piece in the processing. Such
monitoring may be provided on the carriage or may be separately
provided in the chamber of the machine.
[0064] Additionally or alternatively the processing may be
monitored by the use of accelerometers in the processing head.
Calibration routines may be carried out using detectors located in
the chamber. Such routines may be arranged to monitor the or each
processing head and/or the work-piece. Desirably wireless
communication is enabled between the processing heads and a
controller in the machine. Communication with a remote controller
or output may also be provided. Such communication may use IR or
radio data transfer. Additionally communication of processing data
using MT Connect may be utilized or other established wireless
protocols.
[0065] In some embodiments a focal length of any optical elements
may be monitored and data output.
[0066] In one embodiment sensors and circuitry may be embedded into
a work piece as it is being made to form a monitoring device that
can monitor the condition and health of a part in use.
[0067] Preferably such sensors and monitoring devices to be printed
into and onto work pieces may be arranged to function and give
feedback to users prior to completion of said part. It is envisaged
that the monitoring devices could continue to function throughout
the service life of the part. An example of such a monitoring
device would be a strain monitoring circuit, which could detect
when a device had been loaded beyond a safe condition.
[0068] In some preferred embodiments data from the machine and from
processing heads may be output to remote monitoring means.
Preferably a performance of the machine and the delivery heads and
data from the chamber and the work piece is monitored and reported
in real time. In some embodiments an analysis may be carried out in
real time. Preferably a statistical analysis may be carried out to
predict failure of work pieces. In some embodiments the analysis
may be applied to the processing heads to identify potential
failure of the processing heads. In all cases it is preferable for
the detections to form a closed loop feedback system to ensure
quality production of parts and if needed enable remedial re-work
of areas of the parts that do not meet acceptable quality standards
in situ to avoid scrapping the part.
[0069] According to an aspect of the invention there is provided a
machine in accordance with an aspect of the invention in which at
least one carriage is provided with an integrated docking
system.
[0070] Preferably the docking system is arranged such that docking
between the carriage and the head is at a top face of the
processing head.
[0071] Desirably integral docking with the carriage aligns and
mates a manifold on the carriage with a cooperating manifold in the
processing head. In some preferred embodiments the manifold is
orientated perpendicular to the delivery head loading axis. This
may eliminate or reduce the need for the supply docking manifold to
be moved since the processing head docking action also accomplished
docking of the manifolds. It has been found that this action is
particularly suitable for energy sources that do not require a line
of sight but it can also be used with lasers and with other energy
sources.
[0072] In a preferred embodiment the connection between the
carriage and the processing head is arranged to be sealable so as
to preferably exclude contaminants.
[0073] In some embodiments the processing head manifold is arranged
to be fixed. However in some preferred embodiments the manifold is
arranged to move outwardly from the processing head to a docking
position. This has been found to be particularly advantageous as
the processing head occupies less space in the tool changer. In
addition in the storage position a seal can be provided over the
manifold. This is particularly advantageous for processing heads
that are used on the clean side and for which it is desirable to
maintain all of the elements in as clean a state as possible. Such
a seal may be provided by a sliding door.
[0074] A deposition head comprising an electrode providing energy
to a work piece and a media feed wherein the head comprises means
for generating integral electromagnetic field arranged to bend an
arc between the electrode and the work piece.
[0075] The integration of additive manufacturing technology into a
CNC machine has prompted new approaches to beam delivery, to
maximize the utility of the combination. This also introduces a new
approach to laser beam delivery for CNC machines, including the
ability to switch between different sets of optics and even
deposition technologies automatically.
[0076] According to another aspect of the invention there is
provided a machine arranged to carry out removal and addition of
material on a work piece located in a work station having at least
one device arranged to process the work piece, the device being
arranged to be moveable in at least two axes and wherein the work
piece is processed in a sealable chamber.
[0077] According to another aspect of the invention there is
provided a machine arranged to carry out removal and deposition of
material on work piece located in a work station, the machine
having at least one device arranged to process the work piece, the
device being arranged to be moveable in at least two axes and
having a clean side and a dirty side and wherein deposition of
material on the work piece or processing of the work piece is
carried out in a clean environment.
[0078] According to yet another aspect of the invention there is
provided a method of working on a work piece comprising placing the
work piece in a chamber of a machine according to an aspect of the
invention and processing the work piece by removal of material,
cleaning the chamber by removing waste from the chamber and the
work piece, processing the work piece in a clean environment in the
chamber and removing the work piece from the chamber.
[0079] In some embodiments automated means may be provided to place
a work piece on the work station. Preferably the automated means
may comprise pick and place grippers. Such grippers may move the
work piece from a first position to a second position on the work
platform or may move the work piece into and out of the working
area. In a preferred embodiment the grippers select and place
objects including electrical objects for embedding into parts as
they are being made. The working area may be the chamber or may be
the work platform.
[0080] AM and CNC can be combined such that an article can be
fabricated or repaired using AM and finished by having the surface
processed using material removal, such as CNC material removal and
this process is illustrated with reference to FIG. 1. It is known
to use a machine having a number of heads permanently connected to
the tool and selectable to work on a work piece. Such arrangements
increase the bulk and volume occupied by a machining head which
restricts operation of the machining head. It is also known to It
is also known to move a work piece from one work station to another
which each work station carrying out a specific operation including
additive steps and post deposition treatment and cutting.
[0081] As briefly referred to above, the machine is particularly
adapted to the maximize the advantage of the heads and methods of
using the heads but it will be appreciated that the heads may be
retrofitted to existing CNC machines to enable the use of existing
CNC machines for additive manufacturing and post deposition
treatment and cutting. Accordingly there are further aspects of the
invention disclosed herein which relate to the features of the
heads and the methods of using the heads and carrying out methods
of manufacture.
[0082] According to an aspect of the invention there is provided a
method of creating an article comprising at least one of the
following steps:
i) using a first processing head, which may have a first deposition
characteristic, to lay down material having a first set of
properties: ii) changing the first processing head for a second
machine head, which may have a second deposition characteristic
different from the first; iii) laying further material down having
a second set of properties.
[0083] According to another aspect of the invention there is
provided a method of creating an article comprising at least one of
the following steps: [0084] i) using a machine tool having a work
station, a first processing head connectable to the machine tool; a
tool changer and a storage location arranged to store a number of
further processing heads; [0085] ii) using the first processing
head, which may have a first deposition characteristic, to lay down
material having a first set of properties; [0086] ii) changing the
first processing head for a second processing head, which may have
a second deposition characteristic different from the first; and
[0087] iii) laying down further material having a second set of
properties.
[0088] Preferably the storage location is a part of the machine but
is remote from the work station. Preferably any processing heads
not being used are stored in the remote storage location and are
not connected to the machine tool when not in use.
[0089] Embodiments providing the features of the above aspect are
advantageous in that they allow the type of process that is being
performed on the article that is being fabricated (ie a work-piece)
to be performed at a single station without the need to move that
work-piece between stations. Thus, this aspect may be thought of as
providing a single piece or pseudo single piece flow for the
fabrication process. It will be appreciated that a suitable
processing head is selected and is moved to the work-piece.
[0090] A machine tool holding the processing head may, in at least
some embodiments, automatically change the processing head from the
first head to the second head thereby providing a method which can
run with little or no operator interaction.
[0091] Preferably the method comprises use of a machine tool having
a having a work station at which the article is created, a first
processing head connectable to the machine tool; a tool changer and
a storage location arranged to store a number of further processing
heads. The tool changer may be arranged to remove the first
processing head from the machine tool, place the first processing
head in a storage location; remove a second processing head from
the storage location and connect the second processing head to the
machine tool.
[0092] Conveniently, the second deposition characteristic varies
one or more of the following parameters when compared to the first
deposition characteristic:
[0093] Angle of deposition (relative to the build surface); type of
material; mixture of materials being deposited; deposition rate;
bead size; cross-sectional shape of deposition; energy input;
nano/micro characteristic of material (which includes hardness,
ductility, chemical resistance, strength, wear resistance,
electrical and thermal conductivity, dielectric strength, or any
other material property); colour and transparency of material;
texture of the surface finish.
[0094] In some embodiments, the second deposition characteristic is
arranged to improve the fidelity of the article being created to
the desired article thereby removing, or at least reducing, the
need for surface finishing of the article. Embodiments may improve
the fidelity of at least one of an internal and an external surface
of the article.
[0095] Some embodiments may be arranged to deposit a sacrificial
material with at least one of the first and second processing
heads.
[0096] At least some embodiments are arranged to create the article
in stages such that at least one of the first and second processing
heads are used a plurality of times.
[0097] At least some of the embodiments use a third processing head
which may be used to remove material from the article. The third
processing head may be a milling head, or other machine tool.
[0098] In at least some of the embodiments the method may include
the use of a processing head arranged to treat the surface of the
work piece after at least a first layer of material has been
deposited. The surface of a second or further layer may also be
treated.
[0099] Typically a processing head may be connected to a spindle on
the machine tool. It will be understood that the spindle is
considered to be part of the machine tool.
[0100] In some embodiments the machine tool may comprise a supply
unit arranged to supply or to be able to supply a power source to
the or each processing head. The processing head may comprise a
docking manifold arranged connect to the supply unit to supply
power to the processing head. The docking manifold may be arranged
to be alongside or adjacent to the spindle. In some embodiments the
docking manifold may be arranged to connect along an axis
transverse to the spindle. In other embodiments the docking
manifold may be arranged to connect along an axis parallel to the
spindle. In other arrangements the manifold may be rotated into
position. In other arrangements the manifold may be incorporated
into the spindle column, spindle housing or one of the axes
convenient to offer access to the spindle such as the Z-axis for
many machine configurations. For example ports in the manifold may
be arranged in a pattern around the collar of the spindle.
[0101] The power source may be laser energy. Each processing head
may be configured to achieve a unique spatial mode and power
distribution from the head. The mode may be achieved by the use of
optical train components such as apertures, fixed or variable
diffractive or reflective optic and ancillary guide mechanisms as
are known in the art.
[0102] Preferably the docking manifold is arranged to supply
processing media to the processing head in addition to or instead
of supplying power to the processing head. The processing media may
be one or more of a metal, a plastic, polymer or ceramic material
in a powder or a filament form, cooling or processing fluids, gases
and the like including mixtures thereof.
[0103] According to another aspect of the invention there is
provided a method of creating an article comprising at least one of
the following steps: [0104] i) using a first processing head,
having a first deposition characteristic, to lay down material
having a first set of properties; [0105] ii) changing the first
processing head for a second processing head wherein the second
processing head is arranged to analyse at least one of the article
being created and a function of a processing head.
[0106] Preferably the method further comprises using the
information from the analysis to select a further treatment or
processing step to be carried out.
[0107] Preferably the method comprises use of a machine tool having
a work station at which the article is created, a first processing
head connectable to the machine tool; a tool changer and a storage
location (or simply a storage location for the tools which is
reachable with the spindle as is known in the art for changing
conventional rotary cutting tools) arranged to store a number of
further processing heads. The tool changer may be arranged to
remove the first processing head from the machine tool, place the
first processing head in a storage location; remove a second
processing head from the storage location and connect the second
processing head to the machine tool.
[0108] Conveniently, the second processing head is any one or more
of the following: an image recording apparatus; lighting; touch
probes; 3D surface and volumetric scanners; photogrammetry systems,
sensors (such as oxygen sensors; thermal sensors; thermal cameras)
eddy current generators, ultrasound transducers (for air, gel, and
liquid coupled), electromagnetic wave generators, induction heating
coils, electromagnet(s), a magnification device, incremental sheet
forming tools, heat gun, vacuum, induction heater, galvanometer,
oscilloscopes, digital mirror devices, structured light scanners,
grinders, abrasives, right angle variations of heads, microscopes,
confocal or variable microscopes, electromagnetic detectors
including gamma and X-ray, spectrographs, etc.
[0109] Preferably the docking manifold is arranged to supply power
from the supply unit to the second processing head and to transfer
data to and from the second processing head.
[0110] Advantageously there is provided a controller arranged to
control the machine tool and the tool changer. Preferably the
controller has a data storage component and parameters of the
processing heads are stored in the data storage component.
Preferably the controller is arranged to control the first
processing head to deposit material and is then arranged to select
a second processing head dependent on the material deposited and
the work piece to be created.
[0111] The controller may use data from the analysis to select a
further processing head to be utilised.
[0112] The data from the second processing head may be used for
quality control of the treatment of the work-piece. The data may
also or alternatively be used to ensure that the work-piece meets a
desired quality standard. Data from the second processing head may
additionally provide information on the function of a processing
head. Such data may allow the calibration of the processing head to
be evaluated or to establish that the processing head may need to
be replaced or repaired.
[0113] According to another aspect of the invention there is
provided a machine-tool arranged to provide the method of at least
one of the first aspect of the invention.
[0114] The machine tool may be adapted to provide a method of the
invention. The machine tool may be retrofitted with processing
heads and a controller and arranged to carry out one or more of the
disclosed methods.
[0115] According to another aspect of the invention there is
provided a machine readable medium containing instructions which
when read by a computer cause that computer to perform the method
of the at least one of the aspects of the invention.
[0116] According to another aspect of the invention there is
provided a method of inspecting an article being fabricated, the
method comprising at least one of the following steps: [0117] i)
ejecting a fluid from a first processing head onto the article
being inspected; [0118] ii) coupling a second processing head via
the fluid to the article being inspected; and [0119] iii)
transmitting a signal via the fluid in order to inspect the
article.
[0120] In one embodiment, the first and second processing heads are
the same head and the method therefore provides an efficient means
for inspecting an article.
[0121] The fluid may be a cooling fluid which may be a through
spindle cooling fluid thereby providing a method which allows a
processing head to be fitted to an existing machine tool. In such
embodiments, the fluid may be a machine tool cooling fluid arranged
to be used during a material removal process.
[0122] In alternative, or additional, embodiments, the fluid may be
a gel or the like. Such a fluid may be thought of as being a
sacrificial fluid as it will latterly be removed from the article
being inspected.
[0123] In other embodiments, the first and second processing heads
are different and in which the first processing head is arranged to
deposit a sacrificial material.
[0124] According to another aspect of the invention there is
provided a machine tool and/or a processing head arranged to
perform the method of the another aspect of the invention.
[0125] According to another aspect of the invention there is
provided a machine readable medium containing instructions which
when read by a computer cause that computer to perform the method
of the another aspect of the invention.
[0126] The machine readable medium referred to in any of the above
aspects of the invention may be any of the following: a CDROM; a
DVD ROM/RAM (including -R/-RW or +R/+RW); a hard drive; a memory
(including a USB drive; an SD card; a compact flash card or the
like); a transmitted signal (including an Internet download, ftp
file transfer of the like); a wire; etc.
[0127] According to another aspect of the invention there is
provided a method of processing a work piece comprising: [0128] i)
using a first processing head, which may have a first deposition
characteristic to lay down material having a first set of
properties; [0129] ii) processing the article being created by at
least one of laser ablation, drilling, marking, cladding,
inspection, 3D scanning, heat treatment, hammering, scarifying,
shot blasting, peening or micro-peening, needle peening, or
rolling, the method including a plurality of processing steps
carried out on the work piece.
[0130] In a preferred method a series of processes are carried out
by a further processing head or heads. Preferably each processing
head is arranged to be optimised for a particular process.
[0131] The method includes a plurality of processing steps carried
out on the work piece. The method may include two, three, four,
five or more processing steps.
[0132] Preferably at least one of the process steps comprises
inspection and or analysis of the work-piece. Desirably at least
one of the further processing steps is selected using data from the
analysis of the work piece.
[0133] According to another aspect of the invention there is
provided a processing head arranged to carry out two processing
steps simultaneously.
[0134] In one embodiment heating and pressure treatment are carried
out by the same head. In other embodiments alternative processes or
treatments may be combined. An exemplary list of processes which
may be combined is set out below. It is emphasized that the list is
exemplary and not exhaustive. [0135] Induction heating and laser
metal deposition such as cladding or welding, etc; [0136] induction
heating and peening; [0137] induction heating and laser processing
such as heat treatment, etc; [0138] laser heating and peening;
[0139] laser heating and rolling; [0140] laser heating and
chiseling (to remove material); [0141] laser heating and pressure
pins; [0142] laser material deposition and inductive stand-off
measurement [0143] laser polishing (or other processing) and a
camera to assess the effectiveness of the process [0144] shot or
grit blasting to clean/roughen the surface just ahead of laser
processing [0145] shot peening to impart compressive stresses into
the former layer just after laser deposition [0146] deposition of a
degreasing agent, followed by an air blow off to prepare the
surface deposition nozzle for a mineral based flux just ahead of an
arc based metal deposition head (where the flux creates a slag to
protect the cooling weld pool from oxidation) [0147] air blow off
plus a laser metal deposition head use of a camera such as for
registration on fiducial marks with inkjet nozzles; [0148] use of
one or more cameras (visible, HDR, IR, etc.) and a process to
inspect the process; [0149] laser metal deposition and a detection
means to identify surface and/or sub-surface defects, such as by
eddy current inspection; [0150] eddy current inspection and 3D
scanning (for surface form); [0151] laser metal deposition and 3D
scanning; [0152] laser metal deposition and multiple cameras
(photogrammetry); [0153] inkjet head and a camera; [0154]
deposition of reinforcing fiber with a cutting device to cut fiber
when needed milling and camera (for measurement) [0155]
microscope(s) (confocal, stereo, etc.) and a lighting means.
[0156] It will be further appreciated that the processing head may
be arranged to carry out other combinations of processes than those
set out above. In some embodiments the processing head may be
arranged to carry out a plurality of processes.
[0157] In some embodiments the work piece may be inspected or
analysed. In some embodiments the processing head may also be
arranged to be analysed. Such analysis may provide date relating to
the condition of the processing head.
[0158] In a preferred embodiment heating and pressure treatment are
carried out simultaneously. Preferably the pressure treatment is
intermittent. In a preferred embodiment the pressure treatment is
peening.
[0159] In some embodiments the processing head may be arranged to
be optimised to carry out two processes simultaneously such as
laser cladding and hot rolling. In other embodiments the processing
head is arranged to carry out laser deposition (or other forms of
welding, cold spray, directed energy deposition, etc.) and peening
simultaneously. Preferably a portion of the head having peening
pins is arranged to follow the deposition of material on the work
pieces such that the deposited material is processed while it is
hot. In other embodiments a laser deposition head may incorporate a
portion having rollers.
[0160] Preferably the docking manifold is arranged to connect the
processing head to the supply unit and to supply power and media to
the processing head.
[0161] In the embodiment in which laser cladding and hot rolling is
carried out simultaneously the docking manifold is preferably
arranged to connect the processing head to the supply unit to
supply power for the laser cladding and cooling fluid to cool the
rollers in the hot rolling operation. The docking manifold may also
be arranged to supply media to the processing head.
[0162] In a particularly preferred embodiment the method comprises
surface treatment of the work piece by peening. It is desirable to
apply pressure to a localised area on a layer or part of a layer of
a work piece to reduce stress in the layer. In some cases when a
layer of a material is thermally deposited rapid cooling can cause
it to be under a tensile stress. It is desirable to reduce or
eliminate the tensile stress by the application of pressure to some
or all of the layer.
[0163] This can be referred to as peening or micro peening. It can
be undertaken incrementally so as to achieve part, total or
repeated coverage of the areas with residual stress.
[0164] In some embodiments the peening may be achieved by indexing
the processing head to follow a line of deposition. In a preferred
embodiment the head may be arranged to activate one or more peening
pins to add pressure in the wake of an area treated by the
processing head. The processing may be by means such as a laser.
Desirably a plurality of pins can be activated. In a preferred
embodiment activation of the pins is arranged to be countercyclical
to a laser pulsing frequency. In other embodiments the energy
source may be an arc, an electron beam, microwaves, induction
heaters or other similar energy sources. These stress reduction
techniques can be enhanced by choosing build strategies which
distribute the stresses in a balanced way, such as using build
patterns (where the desired end geometry is amenable to it) which
are thin walled and symmetrical. Parts may also be built imitating
a seed where the layers are not planar, but are substantially
spherical--essentially beginning around a small core and layers
grow outward (in a similar way to how a pearl grows layer by
spherical layer).
[0165] In some embodiments a processing head may be provided in
which a media is supplied to a work piece and an energy source
applies energy to the work piece. In a preferred embodiment the
processing head may be arranged to control a direction in which the
energy is directed to the work piece.
[0166] In a preferred embodiment the energy source and the media
feed may be connected to the processing head by means of a
receiving manifold on the processing head. The receiving manifold
may be arranged to connect to a supply manifold on a carriage
carrying the processing head. The media feed is preferably
substantially parallel to the electrode. Such an arrangement
facilitates automation.
[0167] Desirably the energy source is arranged to create a weld
pool. Preferably the energy source is an arc between the processing
head and the work pieces. Alternatively, an electron beam passing
through a plasma "window" may also be useable. Preferably the media
feeds directly into the weld pool. It is desirable that the
processing head comprises means arranged to control the direction
of the energy towards the work piece and in a preferred embodiment
the processing head comprises means of generating an
electromagnetic field. Desirably the electromagnetic field may be
controlled so that a position of the weld pool relative to the
media feed may be controlled. To minimize the variability in the
deposited material characteristics during omnidirectional material
deposition it is desirable to allow coaxial feed of the material on
spindle centerline and position the weld pool to effectively be on
the same coaxial line.
[0168] In some embodiments automated means may be provided to place
a work piece on the work station. Preferably the automated means
may comprise pick and place grippers. Such grippers may move the
work piece from a first position to a second position on the work
platform or may move the work piece into and out of the working
area. In a preferred embodiment the grippers select and place
objects including electrical objects for embedding into parts as
they are being made. In some case a magazine of components may be
integrated into the pick and place heads as illustrated in FIGS. 40
and 41. The working area may be the chamber or may be the work
platform.
[0169] According to another aspect of the invention there is
provided a machine tool arranged to carry out the steps of
processing a work piece comprising: [0170] i) using a first
processing head, which may have a first deposition characteristic
to lay down material having a first set of properties; [0171] ii)
processing the article being created by pressure treatment.
[0172] According to a further aspect of the invention there is
provided a processing head arranged to apply pressure to at least a
portion of a work piece created by additive manufacturing.
[0173] According to another aspect of the invention there is
provided a method of creating an article comprising at least one of
the following steps of processing a work piece comprising: [0174]
i) using a first processing head, which may have a first deposition
characteristic to lay down material having a first set of
properties; [0175] ii) processing the article being created by
pressure treatment.
[0176] In some preferred embodiments the pressure treatment is
intermittent. Preferably the pressure treatment is by means of one
or more impacts on the surface of the deposited material. The
movement may be mechanical or may be ultrasonic. Mechanical
movement may be generated by the machine tool or by the processing
head. The movement may be generated by actuation of pins in the
head. The actuation of the pins may be simultaneous or may be
sequential. Preferably coolant fluid is supplied to the processing
head to keep the pins cool.
[0177] Preferably the head may comprise one or more rollers, at
least one array of rollers, one or more notched rollers. In other
embodiments the head may comprise a pin, chisel or hammer or a
plurality of pins, chisels, or hammers. A power supply is
preferably connected to the processing head. In some embodiments
micro peening is carried out by the use of mechanical movement. The
movement may be generated in the machine tool. Preferably the
mechanical movement is generated in the processing head.
Alternatively the movement may be ultrasonically generated. In a
particularly preferred embodiment the processing head comprises an
array of pins. The configuration of the array may be selected in
view of the geometry of the work piece being stress relieved. A
sequence of processing heads may be selected to fit a particular
geometry. This may be done by the operator based on their
experience or preferably by an algorithm in CAM software.
[0178] The controller may select a processing head to analyse the
work piece and use data from the analysis to select a further
processing head.
[0179] According to another aspect of the invention there is
provided a processing head having a receiving manifold, the
receiving manifold having an openable closure sealing an opening
and an actuator arranged to move the closure between an open and a
closed position.
[0180] Preferably the receiving manifold is arranged to open the
closure when the receiving manifold is connected to a supply
manifold. Desirably the arrangement is such that an interior of the
processing head is not exposed to the general environment.
[0181] In a preferred embodiment an interior of the processing head
may contain a laser path and the laser path is not exposed to
environmental contamination in the docking/undocking process.
[0182] Once the processing head has docked and the head is securely
connected to the supply manifold the power supply to the laser path
can be connected. The power supply may be a laser beam.
[0183] Preferably the supply manifold is also provided with a
second openable closure and a second actuator is arranged to move
the second closure between an open and a closed position. The first
and second closures may be arranged to be openable together to
allow connection from the supply manifold to the processing
head.
[0184] As described above the processing head may be stored and
used in a clean environment and the protection of the interior and
the exterior of the head provided significant advantages over
existing heads and environments of use of the heads. it will be
appreciated that the provision of a clean connection between the
processing head and the supply manifold provides significant
advantages when the heads are used with existing CNC machines.
[0185] In some embodiments the receiving manifold may be provided
in the processing head and may be arranged to dock with a supply
manifold in a machine according to an aspect of the invention.
Preferably the receiving manifold is arranged to connect to a
carriage on which the processing head is engaged in the machine
described. In a conventional machine the receiving manifold maybe
arranged to connect to a supply manifold provided on the machine.
The receiving manifold may have an open position in which a
connection with the supply manifold can be made and a closed
position in which connections in the receiving manifold are
protected from contamination.
[0186] The opening may be provided on a side of the processing head
and arranged to connect with a corresponding side mounted opening
on the supply manifold. Alternatively as described above,
particularly but not exclusively in connection with the machine the
receiving manifold may be provided on an upper face of the
processing head. In some embodiments the manifold may be moveable
from a retracted position to a connection position. A retractable
manifold may in some preferred cases be provided on a side of the
processing head.
[0187] The skilled person will appreciate that a feature described
in relation to any one aspect and/or embodiment of the invention
may be used, mutatis mutandis, to any other aspect/embodiment of
the invention.
[0188] The invention will now be further described by way of
example only with reference to the accompanying drawings in
which
[0189] FIG. 1 is a partial cross section and perspective view of a
machine in accordance with the invention;
[0190] FIG. 2 is a section through the machine of FIG. 1;
[0191] FIG. 3 is a cross section of the machine at right angles to
the section of FIG. 2;
[0192] FIG. 4 is a different view of the section of FIG. 3;
[0193] FIG. 5 is a section through the dirty side of the
machine
[0194] FIG. 6 is a Prior Art processing head;
[0195] FIG. 7 is a processing head for use in the machine;
[0196] FIGS. 8a and 8b show detail of the processing head of FIG. 7
showing the head in a closed position for storage and an open
position;
[0197] FIG. 9 shows examples of grip and place processing
heads.
[0198] FIGS. 10a and b (Prior art) shows how material removal is
used to finish an article fabricated from an additive process;
[0199] FIGS. 11a and b (Prior art) shows the effect of varying
layer thickness in fabricating an article;
[0200] FIG. 12 shows an example machine tool;
[0201] FIG. 13 (Prior art) schematically shows a section through a
machine tool head; and
[0202] FIG. 14 shows a variety of different machine-tool heads;
[0203] FIG. 15 shows a variety of different machine tool heads with
associated spatial and power outputs;
[0204] FIG. 16 shows a flow chart outlining an embodiment;
[0205] FIGS. 17a to 17c show results of the method described in
FIG. 16;
[0206] FIG. 18 shows the results of a further example using the
flow chart of FIG. 16 with a different desired finish;
[0207] FIGS. 19a to 19d show embodiments which are used to process
an internal feature of a work-piece;
[0208] FIGS. 20a and 20b shows an embodiment which uses a support
material;
[0209] FIG. 21 shows a further embodiment using a support
material;
[0210] FIG. 22 shows a further example of a processing-head;
[0211] FIG. 23 shows a further embodiment in which a material is
used to couple the work-piece to a processing-head;
[0212] FIG. 24 shows a cross section through a processing head for
using in the method outlined in relation to FIG. 23;
[0213] FIG. 25a to 25e show examples of power distributions that
can be selected;
[0214] FIG. 26a to 26e show spatial power outputs that can be
achieved;
[0215] FIG. 27 shows a processing head with a chisel tip;
[0216] FIG. 28 shows a processing head with a single pin tip for
peening;
[0217] FIG. 29a to 29d show alternative pin tips for peening;
[0218] FIG. 30a to 30e show a selection of roller tips suitable for
peening;
[0219] FIG. 31 shows a processing head having a tip with vertical
and horizontal rollers;
[0220] FIG. 32 is a side view of the head of FIG. 31;
[0221] FIG. 33 shows a variation of a processing head having a
combination of laser processing and rolling;
[0222] FIG. 34 shows a variation of a processing head having a
combination of laser deposition and a peening tip;
[0223] FIG. 35 is a variation of the processing heads of FIG.
34;
[0224] FIG. 36 is an alternative peening head;
[0225] FIG. 37 is a Prior Art deposition head;
[0226] FIG. 38 is a modified deposition head;
[0227] FIG. 39 shows the movement of the melt pool achieved;
[0228] FIG. 40 is a processing head arranged to supply a number of
components and in which the components are replenished through a
dock; and
[0229] FIG. 41 is a processing head similar to that of FIG. 40 in
which the components are stored in a reservoir in the processing
head;
[0230] FIG. 42 shows a perspective view of a processing head having
a side opening with a closure moveable between an open and a closed
position;
[0231] FIG. 43 is a side view of the processing head of FIG.
42;
[0232] FIG. 44 is a schematic sectional view of a processing head
for adding material and applying pressure;
[0233] FIG. 45 is a schematic sectional view of an alternative
head;
[0234] FIG. 46 is a schematic view of a docked laser processing
head;
[0235] FIG. 47 is a side view of a processing head with a laser
beam delivery and a sensor for feedback and monitoring; and
[0236] FIG. 48 is a schematic view of a modification of the head of
FIG. 47 to include multiple cameras.
[0237] FIG. 1 shows partial cross section and perspective view of a
machine 1 in accordance with an aspect of the invention in which
the machine arranged to carry out removal and addition of material
on a work piece 2. The work piece 2 is located in a work station
which is in a chamber 4. The machine has a first device 6 arranged
to remove material from the work piece.
[0238] The first device comprises a first carriage 8 arranged to
move on a first support 10. The support 10 is able to slide on a
first 12 and a second rail (not shown) in an x direction. The
carriage 8 is moveable on the support 10 in a y direction. The
carriage is movable in a z direction between the support 10 and the
work piece 2.
[0239] In this embodiment the work station comprises a work
platform 14 that is a fixed table.
[0240] The machine comprises a second device 16 arranged to process
the work piece. The second device 16 or mechanism comprises a
carriage 18 mounted on a second support 20. The second support 20
is also arranged to slide on the first rail 12 and a second rail in
an x direction. The second carriage 18 is adapted to move in a y
direction on the second support 20. A first and a second tool
changer 22, 24 are provided. A number of first processing heads are
stored in the first tool changer 22. The first processing heads are
heads arranged to mill, cut, drill, plane the material of the work
piece 2. These processes are considered to be "dirty" and typically
produce waste material. It is not as important to keep the work
piece 2 clean during these processes.
[0241] The machine 1 is arranged such that in use the first
carriage 8 moves adjacent the first tool changer 22 and a suitable
processing head is selected. The processing head is moved to a
docking position and docks with the carriage 8. The carriage 8 is
moved to the chamber 4 and moves in the z direction to bring the
first processing head into position to process the work piece.
[0242] As can also be seen in FIG. 3 a powder catching tray 26 is
placed in the chamber 4 below the work platform 14 to catch any
waste falling from the work piece 2. A coolant and waste removal
fluid is supplied to the work piece by means of a channel in the
first carriage 8. The coolant fluid is removed from the chamber 4
though ducting in the machine 1. The chamber has a floor 28 sloping
to a channel 30 connected to the ducting. Swarf or other waste
material falling from the work piece can be removed from the
chamber 4 along the channel 30 and ducting along with coolant
material.
[0243] Once the first processing head has finished processing the
work piece 2 the first carriage 8 moves in the z direction to
remove the processing head from the work piece. The first carriage
then moves in the y direction and the x direction to bring the
first carriage 8 to the first tool changer 22. The first processing
head is detached from the first carriage and moved into the first
tool changer. While the first carriage is in use the second
carriage is in an inoperative position.
[0244] Preferably the first device 6 comprises the first carriage 8
on which a plurality of interchangeable processing heads can be
removably mounted in use and the interchangeable processing heads
are storable in a first tool changer 22. The second device
comprises a second carriage 18 on which a plurality of
interchangeable processing heads can be removably mounted, the
removable processing heads for the second device being storable in
a second tool changer 20.
[0245] Desirably each tool changer has a number of processing heads
stored therein. The first tool changer preferably stores processing
heads designed to remove material from a work piece. Such heads may
be arranged to carry out milling, grinding, planning, boring,
ablation, machining and other material removal processes as are
well known in the art. The machining may be laser assisted and the
processing head may utilise coaxial laser delivery or off-axis
laser delivery. The second tool changer 24 stores second processing
heads 32. The second processing heads 32 are used for processing
and for additive processes and are kept and used in an
environmentally clean conditions.
[0246] Turning now to FIG. 2 which shows a section through the
machine 1 it can be seen that the work piece 2 is placed on a
platform 14 within the chamber 4. The powder capture tray 26 is in
a retracted position under a powder recycling extraction hood 34
from which powder can be extracted and recovered for re-use. In the
retracted or recovery position the powder capture tray is located
on the clean side and a duct 36 from the extraction hood is located
below the clean tool changer 24.
[0247] FIG. 3 is a cross section of the machine and the section is
at right angles to the section of FIG. 2. The powder capture tray
26 is shown in position in the chamber 4 below the work piece. The
chamber 4 is provided with a sloping floor 28 leading to an
extraction channel 30 in the base of the floor. When the powder
capture tray 26 is not in position in the chamber, swarf or other
waste material from the work piece 2 falls to the floor 28 and
descends the slope to the channel 30 at the bottom. From the
channel swarf and other waste can be removed via an extraction duct
38 as will be described below.
[0248] In this embodiment the chamber 4 is provided with an access
door 40 which can be sealed to be air tight.
[0249] The platform 14 for the work piece in the chamber is movable
in 2 axes A and B. It will be appreciated that the platform 14 may
be arranged to move in more axes if desired.
[0250] As can be readily seen the machine has an electrical cabinet
42 adjacent the chamber. The electrical cabinet 42 houses the
necessary connections and controls for the machine.
[0251] It will be appreciated that the work station, or at least
the work holding device will be electrically isolated from the rest
of the machine with a separate path to ground. Isolation of the
work station enables the use of an arc as a heat source without
causing electrical risk to the machine.
[0252] In one embodiment the electrical isolation is achieved using
a flexible grounding strap for 3 axis machines with a table which
is mounted with a polymer concrete or ceramic spacer between it and
the underlying machine carriages (axes) to isolate it. In many
circumstances on 3-axis machines, it is sufficient to have only the
work holding device isolated and grounded. However 5-axes machines
can be more difficult and tilt-rotary tables can be very difficult
to isolate and ground. In a preferred embodiment the work platform
is isolated by a ceramic or polymer concrete insulator between it
and the underlying carriages. Grounding is achieved by using a set
of carbon brushes that encircle the entire platform which is
generally circular or substantially circular, such that it is free
to rotate continuously but there is always a path to ground through
the carbon brushes all the way around.
[0253] The first rail 12 on an upper portion of the machine can be
seen along with the second rail 44 positioned opposite the first
rail and parallel thereto. Each support is moveable on the first
and second rails. As can be readily seen the first carriage 8 is
arranged to be moveable in the y direction along the first support
10. The first carriage 8 is on the "dirty" side and is arranged to
select a first processing head from the first tool changer 22 which
is visible at the rear of the machine. The first and second
supports 10, 20 may slide on ball screws received in the first and
second rails 12, 44.
[0254] FIG. 4 is a different view of the section of FIG. 3 and
shows the first carriage 8 in position over the work piece 2. In
this case the first carriage 8 is in use and material is being
removed from the work piece. As such it is to be expected that
swarf or other waste material will be removed from the work piece 2
and will be present in the chamber 4. To facilitate removal the
powder capture tray 26 is removed and the waste material which
comes off the work piece and falls to the floor 28 is removed from
the chamber 4 by the channel 30 and ducting 38. FIG. 5 is a section
through the dirty side of the machine and shows the first tool
changer 22 and a passage 46 connected to the channel 30 in the
chamber 4. The passage 46 leads to an inclined duct 38 having a
waste material lift screw 48 which can be an Archimedes screw or
other known lifting screws or transporters can be used. A motor 50
for operation of the waste material lift screw 48 is provided at an
upper end of the inclined duct 38. Once waste material has been
lifted to the upper end of the duct 38 it is transferred to a waste
material collection 52.
[0255] Transfer to the waste material collection is automated.
[0256] Although not shown, coolant is extracted from the chamber
through the duct 38 and by means of a channel provided in the swarf
lift screw 48.
[0257] A roof is provided over the machine, but not shown for
clarity, and the roof as arranged to be able to slide back to allow
access to the machine 1 by a crane and also to allow access for
robotic handling.
[0258] Also not shown are liners which are used in the chamber and
typically comprise a cover or double sealed bellows.
[0259] The machine may be constructed on a polymer concrete base to
provide stability and robustness without undue weight.
[0260] As has been described generally the machine can be used with
processing heads that are already known and such processing heads
may have been used in connection with additive manufacture or in
connection with CNC machining. Such processing heads have been
described in the applicant's earlier applications such as
WO/2014/013247 and unpublished application numbers: GB 1412843.3
and GB1423407.4.
[0261] FIG. 6 is schematic drawing is a processing head which is a
prior art processing head. It comprises a head 60 with media feed
62 and energy source 63 delivering energy to an electrode 64 which
is connected to a suitable machine by a manifold 66. The manifold
66 is separate from the processing head 60 and it is necessary to
arrange for the manifold to be docked and supported through
movement of the processing head.
[0262] FIG. 7 is a schematic drawing of a modified and
substantially improved processing head.
[0263] The processing head comprises a head 70 which is arranged to
deliver energy 71 to an electrode 72. The electrode creates a melt
pool on the work pieces 73. The processing head also supplies media
in the form of a filament 74 to the work piece adjacent the melt
pool. The energy and the media are supplied from a supply manifold
75 which is connected to the machine by a connection secured to a
carriage 76 on which the processing head 70 is engaged.
[0264] The processing head 70 has a receiving manifold 77 which is
adapted to cooperate with a supply manifold 75. The receiving
manifold 77 and the supply manifold 75 cooperate and are docked
together when the carriage 76 picks up the processing head 70.
[0265] The manifold on a processing head will now be described in
more detail in relation to FIG. 8. FIG. 8 schematically shows the
receiving manifold 77 in a closed position in FIG. 8a. In this
embodiment the door 80 rotates to a closed position as can be seen
in FIG. 8a. In this position the connections are protected from
contamination. In FIG. 8b the door 80 is shown in an open position
and connections on the upper surface 81 of the receiving manifold
are accessible for connection the supply manifold 75.
[0266] FIG. 46 illustrates a manifold on a laser processing head
460. A collimated laser beam 462 is supplied to the laser
processing head 460 through the docking manifold interface,
generally indicated at 464. The docking interface 464 is arranged
to allow a docking motion to be accomplished with the tool mounting
motion and the receiving docking manifold 466 has an upper surface
468 which is generally directed upwardly so that the upper surface
of the receiving docking manifold 466 comes into contact with a
lower surface 470 of the supply docking manifold 472 as the
processing head is moved into contact with a spindle on the machine
onto which the processing head is mounted. The collimated laser
beam is directed downwardly by the laser processing head and is
applied to the work pieces, generally indicated at 474.
[0267] An alternative manifold is described below with reference to
FIGS. 42 and 43.
[0268] FIG. 9 illustrates a number of pick and place grabbers.
These end tools can be fixed to a processing head and can be
utilised between processing steps to place material on the work
piece, to remove a portion from the work piece, to add or move
components. They may be particularly useful for adding components
to the work piece part way through a build process. These are
particularly useful in increasing the automation of the build
process and reducing the number of personnel interventions that
have to be made. Improved automation also enable the clean
environment to be maintained and improved.
[0269] The pick and place grabbers are particularly suited for
combination with a head having a magazine of components that can be
applied to a work piece. It is sensors or chips can be dispensed by
the magazine and then placed in position on or in the work piece by
a suitable pick and place grabber as illustrated in FIGS. 40 and
41.
[0270] FIGS. 10a and b show a portion of an article 100 which is
being fabricated using Additive Manufacturing (AM) combined with a
material removal technique. In particular, FIG. 10a shows a stepped
surface 102 which results from building up the article 100 as a
series of layers as is the case in AM where the process uses a
series of layers to fabricate. The final intended surface of the
article is seen in FIG. 10a as a stepped line 104 connecting the
inner corners of the steps 102. Thus, in order to create that
intended surface 104 it is then necessary to remove material from
the article 100 extending beyond that intended surface 104.
[0271] FIG. 10b shows the process of using, in this embodiment a
Computer Numerically Controlled (CNC) machine head 106, to remove
material 108 to provide the finished, intended, surface.
[0272] It is also possible to generate articles, or at least
portions thereof, in which material does not follow the deposition
steps used in AM and a brief discussion of this follows with
reference to FIG. 11. Reference to article herein should be
interpreted to mean not only the entire article, but also a portion
of an article.
[0273] FIG. 11 illustrates that as the depth that is laid down in a
single pass of the AM process then the roughness of the finished
surface increases but the speed at which the article can be
fabricated is normally increased as more material is laid down in a
single pass. Thus, in FIG. 11a it can be seen that the intended
surface 200 of the article 202 has larger steps within it when
compared to the intended surface 204 of article 206 as shown in
FIG. 11b in which less material has been laid down in each pass of
the AM process. Accordingly, in the prior art a choice is made,
unless post processing material removal is to be used, as to
whether to fabricate the article quickly by laying down more
material in each pass, or whether an improved surface finish is
required thereby reducing the speed at which the article can be
fabricated.
[0274] The skilled person will appreciate that regardless of the
step size used (ie the amount of material laid down in each pass of
the AM process) it would be possible to remove material to provide
the finished surface as described in relation to FIG. 10. However,
the amount of material and therefore waste and time needed to do
the material removal will be determined by the step size (ie the
amount of material laid down in each pass of the AM process) used
to fabricate the article, or part thereof.
[0275] FIG. 12 shows, schematically, a machine-tool 300, which
typically comprises a processing head 302 held in a clamping
mechanism of the machine-tool 300 and arranged to process a
work-piece 304 (such as the article 100 of FIG. 10) held in a work
volume. Typically the work-piece 304 is held within the work-volume
by an additional clamping mechanism such as a vice, or the like.
Further, the machine-tool 300 is usually controlled by a controller
306 (which may be thought of as a computer) which controls the
position of the processing-head 302 as it processes the work-piece
304.
[0276] Most machine-tools 300 are arranged such that the
processing-head 302 can be interchanged with other processing-heads
302 in order that the correct processing-head 302 is provided for
the task at hand. Providing the example of milling machine, then a
first processing-head may be provided for coarse material removal,
whereas a second processing-head may be provided for fine material
removal. In the case of material removal, such as milling, then the
processing head may often be referred to as a machining-head or
milling cutter.
[0277] As such, machine-tools 300 have tool-changers 308 which can,
typically under the control of the controller 306, automatically
change the processing head 302 being used by the machine-tool 100
to process the work-piece 304. Typically, the tool changer will
also be under the control of the controller 306. In the Figure
shown, four further processing heads (which may be machining heads)
310, 312, 314, 316 are shown in a storage location 308 in addition
to the processing head 302 already in the machine tool 300.
[0278] FIG. 13 illustrates a processing-head 400 which connects to
the machine-tool 100 using the clamping mechanism 402 of the
machine-tool 100 and which can be stored in a store of
processing-heads 308 (ie a tool changer) and automatically
connected to the machine-tool 100 with a tool-changer thereof. Here
the tool-changer 308 may provide a storage-location for
processing-heads, machining-heads, etc. which are not currently
being used by the machine-tool 100. Discussion herein refers to a
clamping-mechanism 402 and it is assumed that a spindle into which
the clamping mechanism 402 connects is part of the machine-tool
100.
[0279] In the embodiment being described, the processing head 400
is arranged to focus a laser beam 406 onto the work-piece 304. In
other embodiments, other energy sources may be utilised instead of
the laser. Thus, the processing head is arranged, under the control
of the controller 306, to process the work-piece 304 with the
focused laser beam 406 (or other energy source).
[0280] In FIG. 13, a section is shown through the processing-head
400 and it can be seen that a reflector, such as a mirror 408,
arranged to move an incoming laser beam 410 through ninety degrees
to be incident upon a focusing-lens 412 for creation of the
focused-laser beam 406.
[0281] In addition to the laser beam and optical components, the
processing-head 400 also contains one or more ducts to deliver a
media. For the example, the media may comprise a polymer, ceramic
and/or metallic powder within a transport fluid which is arranged
to be melted by the energy source. The processing is arranged such
that media is delivered through the processing-head and is passed
into the energy source such that it is molten or at least
semi-molten before the media reaches the work-piece 304. As such,
the processing-head can be used to deposit material onto the
work-piece and provide a deposition system, which may for example
be used to repair parts. Thus, the processing head may be utilised
in an Additive Manufacturing process.
[0282] The machine tool (including a spindle) and the
clamping-mechanism 402 have a longitudinal axis, represented by the
dashed line XX in FIG. 13. Should a machining-head (such as a
milling cutter) be present within the clamping-mechanism 402 then
it would rotate about the axis XX. Conveniently, the energy source,
which in the embodiment being described is the laser-beam 406, is
focused onto a point, area, etc. 413 that lies substantially upon
the axis XX on the surface of the work-piece 304.
[0283] In other embodiments, the focusing-lens 412 may in fact be
arranged to cause a divergent beam, such as would be the case for
pre-heating the substrate (and as illustrated by the processing
head 316 in D FIG. 14), heat treating the work piece or in some
types of thermal spraying and the like.
[0284] Although not shown in the drawings, some embodiments of the
invention may be arranged to transmit an energy source through a
spindle of the machine tool along the axis XX; ie from the region
of point 407 shown in FIG. 11. In such embodiments the supply-unit
would supply media to the processing head 400.
[0285] In other embodiments, regardless of whether the energy
source is provided from region 407 or from elsewhere, it may be
preferable to deposit from a position offset from axis XX.
[0286] Adjacent to the processing head 400 and clamping-mechanism
402 there is provided a supply-unit 414 which provides a housing in
which various components are housed. The processing-head 400
comprises a processing-head docking-manifold 401 and the
supply-unit 414 comprises a supply docking-manifold which are
arranged to mate with one another to connect the supply-unit 414 to
the processing-head 400 in the condition as shown in FIG. 13.
[0287] On top of the supply-unit 414 there is provided an energy
source 416, which in the embodiment being described is a laser. The
laser 416 generates a beam which is transmitted into the
supply-unit 414 and passes through a beam expander 417 comprising a
first and a second lens 418, 420 respectively. The beam expander
417 is utilised to increase the diameter of the laser beam in order
to achieve a better final focus onto the work-piece 304 and reduce
the thermal load on the optics.
[0288] The supply-unit 414 also comprises a further reflector 422
arranged to reflect the beam of light from the laser through 900
toward the processing head 400 and the reflector 408
therewithin.
[0289] As referred to the beam may be controlled by the use of
variable optics or fixed optics or combinations or arrays of these
optics. Examples of the spatial distribution of the laser beam are
illustrated in FIG. 26 a to e. A power distribution of the laser
beam may also be varied and examples are shown in FIG. 25a to
e.
[0290] The supply-unit 414 also comprises a supply of various media
424 which connects through the manifold to the processing-head 400
when the supply-unit 414 is connected thereto. It will be
appreciated that the media may be supplied by docking with the
supply manifold of the supply unit. Alternatively media can be
supplied from an internal reservoir or cartridge in the processing
head.
[0291] In some embodiments the media may be a suitable powder and
may be supplied from a side of the processing head through a port
or annular supply line. Supply of the powder to the work piece may
be through a side feed or preferably through coaxially directed
ports or a coaxial annular outlet.
[0292] Alternatively the media may be provided in the form of a
metallic wire or polymer filament and may be supplied from the
supply unit. The wire may be fed along guides coaxially to the work
piece or may be provided in multiple feeds from the processing head
to the work piece.
[0293] In some cases the media may be a fluid and may be a gas used
for inert shielding or shaping of the work piece. A gas may be
supplied to the processing head from the supply unit. Liquid fluids
may be used for cooling of the processing head as will be described
in more detail below. Liquids may also be used for coupling of the
processing head with the work piece for ultrasonic cleaning,
abrasion or inspection. In some other embodiments a liquid may be
used as a media for confinement of energy pulses as used in laser
shock peening of the work piece.
[0294] The skilled person will appreciate that the area 426 around
the work-piece 304 is typically referred to as the working area (or
volume) of the machine-tool.
[0295] FIG. 25 shows a variety of processing heads 310-316 that
are, in the embodiment being described, held within the tool
changer 308. The skilled person will appreciate that the particular
heads that have been chosen to illustrate this embodiment are
examples only and other embodiments will likely utilise other
processing and/or machining heads.
[0296] The embodiment of FIG. 12 may thus be used in a hybrid
methodology which uses the tool changer as an automation system to
allow both AM to be provided as well as material removal,
inspection, and the like. Such a hybrid methodology reduces the
cost and complication normally associated with work-piece 304
transfer between technologies done up until now by human operators,
robots, or other automation solutions. There is no inherent
limitation to the types of technologies which can now be mixed and
deployed including multiple additive, subtractive and inspection
technologies.
[0297] The use of a tool changer 308 allows convenient changeover
of a variety of laser processing heads--each with optimized optics,
powder focus, and shielding gas for a specific task (as illustrated
in relation to the head shown FIG. 13). Using a selection of
different heads opens up a wider range of effective operations than
is typically achieved using a single processing head. Other
embodiments may use processing heads which use an energy source
other than a laser, or which use laser based processing heads
providing functions other than as described herein.
[0298] FIG. 14 shows, in more detail, the processing heads 310-316
of the embodiment being described. Other embodiments, may of course
use other heads. The first head 310 is a conventional co-axial
laser cladding head. The second head 312 is a laser cladding head
with optics for optimizing the power distribution within the laser
focus for a high power multi-mode laser. The third head is a laser
cutting head with optimized profile and high pressure/velocity
inert assist gas 314. The fourth head 316 has a parallel or
divergent focus head used for cleaning (including for removal of
coolant residue), preheating, annealing, heat treatment, etc.
[0299] Using this set of heads 310-316 the embodiment being
described can process the work-piece 304 in a variety of ways. For
example, in the repair/restoration of a turbine blade any holes
covered over during cladding can be re-opened by laser drilling in
the same setup by changing the processing head 310-316 used by the
machine tool 100.
[0300] FIG. 15 shows in more detail the processing heads and some
alternative spatial distributions and the associated power outputs
that can be selected. The spatial output may be controlled by
selecting the optic in the laser processing head. The optics may be
variable or fixed. Variable optics can be selected from free form
mirrors, galvanometer(s) and digital mirror devices.
[0301] This is an example of how hybridizing increases the
flexibility of current tools. Combining laser processing with
in-machine inspection then builds another layer of in-process
quality assurance in a system which can actually correct problems
arising (by detection, removal and re-addition of material) before
parts simply become expensive scrap.
[0302] A processing head combining laser processing and inspection
is illustrated in FIGS. 47 and 48. FIG. 47 illustrates a laser
processing head corresponding to that described with reference to
FIG. 13. In this embodiment the processing head 4700 is provided
with a second processing function in the form of a camera or sensor
4702. Although the use of cameras positioned to view the melt pool
is known in the art, the ability to introduce a camera into the
work area to augment one or more deposition heads through the
dockable manifold provides the ability to monitor through heads
which are amenable to such and to have it safely removed from the
working area when it is not in use. The camera 4702 is provided
adjacent a feed for the laser beam 4704. The laser beam 4704 is
directed to a partial reflector 4706 which directs the laser beam
energy toward the axis of the spindle. The partial reflector 4706
allows coaxial viewing through the reflector.
[0303] A second reflector 4708 is provided and this allows the
camera a coaxial line of sight in the laser beam delivery. The
camera is designed to provide in process feedback and monitoring of
the work piece and can be adapted to provide in process feedback on
the function of the laser processing head.
[0304] It will be appreciated that the camera could be mounted
without the use of the second reflector by mounting the camera with
a direct line of sight to the partial reflector. Optionally
multiple cameras may be used to monitor different spectra. It will
be appreciated that it is straightforward to mount alternative
sensors on the head to monitor other data from the work piece or
from the head as is schematically illustrated in FIG. 48. A first
camera 4702 is mounted adjacent the laser beam feed and has a
coaxial line of sight to the laser beam by reflector 4708 and
partial reflector 4706. A second camera 4710 is mounted adjacent
the first camera 4702. A second reflector 4712 provides a coaxial
line of sight from the second camera to the laser beam feed.
[0305] Some embodiments of the invention may be arranged to deposit
dissimilar materials onto the work-piece 304, perhaps by providing
a different processing head for each material.
[0306] Thus, in an example of how the embodiment being described
may be used is described in relation to the flow chart of FIG.
16.
[0307] As a first step 600, the machine-tool 300 is arranged to
select a first processing head 312 (a laser cladding head) from the
tool-changer 308. This head is similar to that described in FIG. 13
and arranged to deposit material (in this case metal) onto a
work-piece 304.
[0308] The controller 306 is programmed, as is known in the art, to
control the machine tool 300 and the processing head 312 to deposit
material (step 602) to fabricate the desired article. The skilled
person will appreciate that the techniques described herein will be
suitable for creating entire articles or modifying existing
articles. The modification of an existing article will include the
repair of that article.
[0309] As described in relation to FIGS. 10 and 11 above, the
material deposited by the processing head 312 is built up in layers
which leads to steps evident on the outside surface of the
work-piece 306. Such steps will also occur on any inside
surfaces.
[0310] Accordingly, once a predetermined point of the program
executed by the controller 306, the machine tool is arranged to
dock the processing head 312 back into the tool changer 308 (step
604). The skilled person will appreciate that the predetermined
point will be determined by the program. In some embodiments, the
predetermined point may when the majority of the material for the
article being fabricated has been deposited. In other embodiments,
the deposition of the material for the article may occur in an
iterative manner: ie some material is deposited, processing heads
changed; other processing performed; deposition head returned and
further material deposited and such a process flow is described in
relation to FIG. 19.
[0311] The controller 306 then causes the machine tool to select a
second processing head (step 606), which in this example is
processing head 310. Looking at FIG. 14, it can be seen that the
area onto which the laser beam is focused from the processing head
310 is smaller than the area for the processing head 312. As such,
the processing head 310 will deposit material in smaller amounts
when compared to the processing head 312. Thus, the processing head
310 may then be controlled to deposit material in finer amounts
(step 608).
[0312] The controller has a data storage component that is arranged
to store information on the parameters of the processing heads in
the storage location and is arranged to select a suitable
processing head based on the desired article.
[0313] In addition the controller can select a processing head
adapted to inspect or analyse the work piece. The controller is
arranged to select a suitable processing head for further
processing depending on the data from the analysing head.
[0314] FIG. 17 shows how layers 700a-d deposited by head 312 are of
a larger thickness than layers 702a-c deposited by head 310. For
example, process step 602 may have been used to deposit layers 700
and process step 604 may have been used to deposit layers 702. The
skilled person will appreciate that whilst FIG. 16 shows only a
single change of processing heads, other embodiments may provide
multiple processing head changes in order to work on the
work-piece. Each sequential processing head selected can be
controlled by the controller using information from an inspection
or analysing head and depending on the work piece to be
created.
[0315] However, it will also be seen that the head 310 has been
used to fill in the stepped nature of the surface part 704 (ie the
work-piece) being fabricated. Thus, the surface of the part becomes
a closer approximation to the desired surface 706 and the second
processing head used in step 606 has been used to improve the
fidelity of the article being created to the desired article
thereby removing, or at least reducing, the need for surface
finishing of the article. Depending on the characteristics of the
further heads a higher fidelity to the intended surface may be
achieved as shown in FIGS. 17b and 17c.
[0316] FIG. 17b illustrates an embodiment where the second
processing head allows material 710a-e to be deposited with
sufficient resolution that the final, desired surface 706 can be
substantially achieved without the need for further processing.
[0317] FIG. 17c shows an embodiment in which a liquid has been
deposited by the second processing head, and due to the surface
tension within that liquid (prior to solidification), the deposited
and solidified material 712a-e forms convex surfaces extending
slightly beyond the desired 706 final surface.
[0318] Once the processing head 310 has been used to deposit the
smaller amounts of material in layers 702a-c; 710a-e; 712a-e then
the surface may have an acceptable surface finish. If this is not
the case then further processing and/or machining heads may be used
to further work the work-piece. For example smaller amounts of
material could be deposited within the remaining steps (eg 708)
between the layers 700 and 702 to make the surface a closer
approximation to the desired surface 706.
[0319] In alternative, or additional, embodiments a milling head,
or the like, may be selected to remove material to provide the
desired surface. It will be appreciated that in such embodiments
less material will need to be removed when compared to embodiments
in which the material layers 702a-c was not deposited by processing
head 310. Thus, it will be appreciated that embodiments providing
the method as outlined in relation to FIG. 17 provide a surface
finish that is either i) acceptable without any material removal;
or 2) requires much less material removal to provide the finished
surface when compared to an embodiment in which layers 702a-c had
not been deposited. In the example, of FIG. 17 the material being
deposited in layers 700 and 702 is largely the same but with the
rate/amount of material deposition being varied between layers 700
and 702.
[0320] FIG. 18 is used to exemplify another example of FIG. 16 in
which the material is varied between steps 602 and 606. It will be
appreciated that it would also be possible to vary the rate/amount
of material being deposited in addition to varying the composition
of said material.
[0321] As in FIG. 17, process step 602 is used to deposit layers
700a-d and step 604 is used to change the processing head.
[0322] In step 606 the second processing head is used to deposit a
material having a different property in the layers 800a-d when
compared to the layers 700a-d. The skilled person will appreciate
that whilst the layers 800a-d are shown, in this embodiment, as
being on the faces of the layers 700a-d this need not be the
case.
[0323] In the embodiment of FIG. 18, the different property is
provided by a different micro-structure of material. Specifically,
the material deposited in layers 800a-d has a different heat
treatment, whilst it could be substantially the same material as
that in layers 700a-d, and therefore has a different hardness. For
example, the layers 800a-d may constitute a hardened bearing
surface, cylinder sleeve of the like. Those trained in the art will
appreciate that by varying the processing parameters including
energy input, feedstocks, additives, shielding, that a wide variety
of nano and micro properties can be varied including grain size,
crystal structure, crystal orientation, and chemistry which have
corresponding effects on the hardness, chemical resistance,
magnetism, residual stress, dimensional stability, thermal
conductivity, electrical conductivity, etc.
[0324] In other embodiments, it is possible to change the material
between steps 602 and 606. For example, step 602 may be used to
deposit a metal and step 606 may be used to deposit a plastic.
[0325] In other embodiments similar to that shown in FIG. 18, the
layers 800a-d may not be provided by further material and may
simply be provided by a heat treatment to the surface region of
layers 700a-d. Such surface region treatment may be provided by a
heat source, such as a laser, or the like. An alternative treatment
will be described in more detail below.
[0326] Thus, FIG. 18 is used to exemplify embodiments in which step
606 is used to deposit materials of different properties (whether
bulk or nano/micro-structure) when compared to the material
deposited in step 602.
[0327] FIGS. 19a-19b are used to exemplify a further example of the
process outlined in relation to FIG. 16. Here a first processing
head is used to deposit a series of substantially annular layers
900a-d. Each of the layers are shown and thus the interface between
each of the layers is visible in the figure. The skilled person
will appreciate that this interface between layers 900a-d will be
present both on the outside of the annulus of each layer and also
on the inside of each layer.
[0328] Here the second processing head used in step 606 is a
material removal head, such as a milling machine, or the like.
However, the material removal is not only used to smooth the
outside surface of the layers, as shown at 902 but also to smooth
the inside of the annulus in a similar manner.
[0329] In other embodiments, further material may be deposited
using a second processing head in order to improve the fidelity of
the inside surface of the article being created to the desired
article in a similar manner to that described in relation to the
outer surface in FIG. 17.
[0330] As such, the skilled person will appreciate that, in such an
embodiment, the number of layers deposited using the first
processing head in step 602 is limited to the extent that the
second processing head used in step 606 can reach sufficiently far
inside the work-piece 902.
[0331] However, by using both the first and second processing heads
a plurality of times, thereby creating the article in stages, it is
possible to build up larger work-pieces which have a smoothed
inside surface.
[0332] Thus, in the example of FIG. 19 it can be seen that once the
second processing head has been finished with in step 606, the
first processing head is again used a further four layers 904a-d
are deposited on top of the work-piece 902. Then the second
processing head is again used in step 606 and both the internal and
external surfaces of the new layers 904a-d are processed to
generate work-piece 906.
[0333] Embodiments, in which the internal surfaces are smoothed in
this manner may find utility applications in which a gas, a liquid,
or other fluid or fluidized material flows through work-piece 906
since it will be appreciated that smooth internal surface can lead
to a better fluid flow. Examples where such a structure may be
useful include fuel lines, hydraulic lines, cooling channels, flow
tubes or the like.
[0334] The skilled person will also appreciate that it would be
possible to provide further processing head changes so as to
provide a change of macro or micro material around the inner
surface region of each of the layers 900a-d, 904a-d, etc.
Additionally a substantially smoother internal surface may be
achieved by the use of different size deposition heads without
machining where that is deemed more appropriate.
[0335] FIG. 20 is used to explain a further example of how the
process of FIG. 16 might be utilised.
[0336] In step 602, a first material is deposited. In the example
of FIG. 20a, the material is deposited as half a cylinder 1000 in a
first material. This cylinder 1000 will be a sacrificial material
as described hereinafter.
[0337] In the second processing step a further material 1002 is
deposited over the sacrificial material 1000. Thus, the sacrificial
material 1000 supports the arch 1004 so that the arch 1004 can be
fabricated and thereby, the sacrificial material 1000 provides
support for material deposited in latter processing steps. Once the
second processing head has finished and the further material 1002
has solidified, etc. the sacrificial material 1000 can be removed.
The skilled person will appreciate that further processing steps
may be completed before the sacrificial material 1000 is
removed.
[0338] In such embodiments, the portion of material 1002 may any
suitable material for acting as a support. However, the portion of
material 1002, which may be thought of a support material, may
typically be a soluble polymer material or a loosely
bonded/confined particulates or powder. It may be in a solid part
filling the void or may be created as hollow self-supporting
structure according to the limitations known in the art of directed
energy deposition. For example a support structure could be made in
a form that resembles cathedral like arches. It could also be made
in such a way that it is easily removable by machining.
[0339] FIG. 21 provides a further example in which a support, or
sacrificial, material is deposited to facilitate fabrication or
repair of the underlying article. Here the article being fabricated
is a turbine blade 1100. At a lower portion of the turbine blade
there is a fir tree root portion 1102 which is difficult to hold
during fabrication steps.
[0340] As such, some embodiments are arranged to encase this fir
tree root portion 1102 within a block of sacrificial material 1104
(shown here in dotted outline). This sacrificial material 1104
could then be clamped in order to hold the turbine blade 1100
during subsequent steps. Thus, the sacrificial material 1104
provides a temporary, sacrificial, material which aid physical
location of the work piece.
[0341] It will be appreciated that components may benefit from
being supported at more than one point. Thus, in the context of
FIG. 21, one embodiment provides a further portion of sacrificial
material 1106 toward the end region opposite the fir tree root
portion 1102. This further portion 1106 allows the blade 1100 to be
held at two points at the regions of sacrificial material 1104,
1106 and the blade 1100 is protected from damage by the clamping
means (such as a vice, or the like).
[0342] The skilled person will appreciate that although the example
of a turbine blade has been used any other part could be so
treated.
[0343] In some embodiments, a processing head may be used to
provide a protective material arranged to protect a surface region
of the work-piece. As with the support material, the protective
material may (or may not) be a sacrificial material which is
removed later in the fabrication of the article.
[0344] In yet further embodiments, as briefly referred to above, a
processing head may be used to inspect an article. In such
embodiments, the processing head may comprise any one or more of
the following: image recording apparatus; lighting; touch probes;
3D surface and volumetric scanners; photogrammetry systems, sensors
(such as oxygen sensors; thermal sensors; thermal cameras); eddy
current generators; ultrasound transducers (for air, gel, and
liquid coupled); electromagnetic wave generators or the like.
Inspection data can be transferred from the processing head to the
controller and from the controller to the processing head to
control the inspection.
[0345] Thus, it will be seen from the foregoing that embodiments of
the invention provide a variety of processing steps that may be
applied to a work-piece. The skilled person will appreciate that a
feature described in relation to any one embodiment may be used,
mutatis mutandis, with any of the other described embodiments.
[0346] Some embodiments may flush a processing head. Such
embodiments are advantageous because they help to ensure that the
processing head is clean for its next use and help to avoid
contamination of materials. Further, such embodiments help prevent
wear to components through particles of material left within and/or
on a processing head. In particular, in the embodiment being
described, as a processing head is returned to the tool changer 308
is flushed with compressed air. In other embodiments other gases
(eg an inert gas such as nitrogen or the like) might be used.
[0347] In one particular embodiment, there comprises four material
feeds from the supply-unit 414 to the processing head 400. Other
embodiments may have fewer or more material feeds used one at a
time or in combination to provide in-process alloying. However,
four feeds can be used to provide flexibility in how material is
delivered from the supply-unit 414 to the processing head 400 and
can be used to improve the speed with which a material change can
be made and also to reduce the chances of contamination.
[0348] In one example, material of a first kind may be fed to the
processing head 400 using two feeds. Then, it is desired to switch
materials and so flow of material is stopped, or at least diverted,
using a by-pass circuit, away from the processing-head 400. In the
embodiment being described it has been found advantageous to divert
material back to a hopper so that it is not wasted, thereby
collecting media that is flushed/diverted from the processing-head.
Here diversion rather than stopping the feed is helpful to ensure
that pressures within the material feed are not raised too
greatly.
[0349] Once the first material has been diverted (ie stopped from
entering the processing head), the processing head is flushed with
air and subsequently the two feeds not previously used are now used
to supply a second material to the processing head. Such an
embodiment is advantageous as it allows the supplied material to be
switched from the first material to the second material quickly
without the need to change processing heads 400 or change
supply-units 414 whilst ensuring that no contamination of the
materials occurs.
[0350] Various actions may be performed to assist changing from a
first processing head to a second processing head.
[0351] In addition, and in the embodiment being described,
parameters associated with the processing head to be used are
loaded for use into the controller 306. Thus, with reference to
FIG. 16, then as the first processing head is changed for the
second processing head then at some point during the change between
the two heads parameters associated with the second processing head
are loaded for use into the controller 306.
[0352] A wide variety of processing parameters are stored for each
deposition head including powers, feed speeds, gas flows, etc. and
rates of change for each of these triggered by geometry
requirements. These settings may be stored in database tables in a
separate controller and called up as needed or they may be fully
integrated into the machine tool controller and called using custom
M-codes or other suitable signals. In some cases parameters for
deposition heads may be used with functionality in the controller
already associated with conventional cutting tools such as offsets.
Embodiments may re-purpose the parameters stored in relation
machining heads (eg a milling head or the like) to allow those
parameters to be used with non-machining processing heads (such as
deposition heads, probe heads and the like). For example, at least
one of the following parameters may be stored for a processing
head: [0353] Tool length offset for each processing head length.
Typically tool length is measured along what would be termed the
Z-axis, which in the embodiment described in relation to FIG. 13 is
along the line XX. It will be appreciate that most machine tools
300 have a parameter, often called a G-code, used to adjust the
origin for the measured and stored the length of a bit, or other
material remover. This parameter may be used to store the length of
the processing head. Embodiments which store the length of the
processing head are advantageous in that they can reduce the
chances of the processing head having a collision with the
work-piece 304. Embodiments may adjust the origin for the
processing head to allow the processing head to be moved between a
plurality of work-volumes at the same machine-tool 300. This
parameter allows adjustment to be made to the origin of the
machine-tool 300 to offset the datum for fixtures on the table,
such as when there are two vices on the CNC table (eg two
work-volumes). In the embodiment being described the parameters are
used to record any deviations from centre-line (fine tuning to
arrange all processing-heads to be used by the machine-tool 300 on
the centre-line and/or in some cases for an intended offset).
[0354] The fixture offset can be used to make fine adjustments to
ensure that the head position is kept substantially on the centre
line of the spindle, or to specify intentional offsets from said
centre-line. These offsets would typically be referred to as being
in the X or Y axis, which in the embodiment of described in
relation to FIG. 13 would be perpendicular to the line XX.
[0355] In some embodiments, including the one being described, the
tool length stored may be modified or compensated such that the
processing head length is increased beyond its physical length to
include the designed stand-off distance of the processing head from
the build surface (ie the surface of the work-piece 304). Here the
stand-off distance is the required distance between the processing
head and the work-piece 304 and may be adjusted to manipulate the
deposition width.
[0356] In this embodiment, the controller 306 is arranged to vary
the stand-off distance, and therefore to vary the stored length of
the processing head, in order to vary the distribution of the laser
beam power that is imparted on to the work-piece 304. The skilled
person will appreciate that as the laser is moved toward or away
from the work-piece then it will move into or out of the nominally
engineered focus. Accordingly, using a processing head length which
includes the stand-off distance can allow the focusing of any
energy source provided by the processing head, which in the
embodiment being described is the laser.
[0357] Some embodiments, may measure the amount of back reflection
of the laser from the surface of the work-piece 304 and aim to
minimise this amount; as such, the processing head is arranged to
measure energy returned from the work-piece from energy directed
(ie the laser), from the processing head, toward the work-piece. It
will be appreciated that once a laser is focused then maximum power
will be coupled into the work-piece 304 and that therefore, the
amount of laser light reflected from the surface will be a minimum.
This process of determining the ideal focus may be a stored routine
which moves the head through a range of stand-off distances to
establish the ideal focus and then the optimised outcome of the
process can be stored in the CNC tool length tables as described
above, or otherwise.
[0358] Furthermore, any processing head where the deposition or
processing point is not on the spindle centerline can be stored as
a fixture offset and called when the head is loaded into the
spindle, thus re-purposing another standard CNC feature to
accommodate the use of multiple heads.
[0359] Further, embodiments may store further parameters for a
processing head. For example, parameters may be stored that
determine the flow rate of any media 424, flow rate of any
shielding gas, or the like; determine the power of any energy
source (such as laser 416). The parameters mentioned in this
paragraph may indicate how they should be varied according to
motion of the processing head. For instance, it will be appreciated
that as a processing head approaches a turn within its path then it
is likely to need to slow down in order to achieve that turn.
Accordingly, as the processing head slows it becomes advantageous
for embodiments to reduce the flow of media 424; reduce the flow of
shielding gas; and reduce the power of any energy source (eg laser
416).
[0360] Some embodiments may use a processing head 1200 which use
mechanical means, such as a syringe 1202 or one or more Archimedes
screws (not shown), to eject or extrude material 1204 from the head
1200. Such embodiments may work with a material feed from the
supply-unit 414 or may additional supply media from a reservoir
within the processing head 1206.
[0361] Some embodiments may use the spindle rotation (of the
machine tool) to directly control the amount of material extruded.
For example in the processing-head 1200 of the Figure being
described which uses a syringe-based deposition, the plunger or
other means for causing displacement in the syringe 1202 is coupled
to the spindle with the tool holder and thereby commands to control
the spindle motion changes the displacement which controls the
deposition rate.
[0362] In one embodiment there are one or two Archimedes screws
which are arranged to interact to plasticise a material (typically
by shearing the material after the manner known in injection
moulding), typically a polymer, within the processing head. The
energy to rotate the screws may come directly from the spindle
rotation. A heater can additionally be provided in order assist
plasticising of the material. The heater may be powered by
electricity generated from the spindle motion.
[0363] In one embodiment, the processing head is arranged to sense
the spindle speed of the machine tool to which it is attached and
to use that spindle speed to control the mechanical means within
the head. For example a transition from a first speed of rotation
to a second speed of rotation may indicate that flow should start.
A transition from a high speed to a low speed may indicate that
flow should cease.
[0364] Other embodiments may use further speeds of rotation in
order to pass further information to the processing head.
[0365] FIG. 23 illustrates a further embodiment in which a
processing head 1300 is positioned above an article that is being
inspected 1302. This article may still be in the process of being
manufactured and an inspection step may be performed as part of the
process described in relation to any of the Figures above. The
article 1302 could also be a finished article to be inspected.
[0366] FIG. 23 shows a fluid 1304 being ejected from the processing
head 1300 and impacting upon a surface of the article 1302. In the
embodiment of FIG. 23, the fluid is a cooling fluid typically used
by the machine tool in which the processing head is mounted to cool
an article being milled, drilled, or similarly processed. Thus, it
will be seen, as illustrated in the Figure, that the fluid sprays
away 1306 from the surface 1302. To facilitate the communication of
the cooling fluid to the article, a channel 1308 is provided along
a central region of the processing head 1300. The channel is
arranged to ensure that the fluid 1304, as far as possible, has a
laminar flow since turbulence within the fluid flow can reduce the
coupling to the article 1302.
[0367] In some embodiments, the fluid 1304 is through spindle
coolant.
[0368] Nonetheless the fluid 1304 provides sufficient coupling for
an ultrasound transducer 1310 provided within the channel 1308 and
in communication with the fluid 1304 flowing therein for ultrasound
transmitted by the transducer 1310 to be couple to the article
1302.
[0369] Thus, embodiments as described in relation to FIG. 23 can be
used to inspect articles 1302 using ultrasound. The skilled person
will appreciate that such inspection may be useful in determining
the presence of voids and the like within the article 1302.
[0370] In other embodiments, the fluid may be deposited onto the
surface and latterly used by a processing head to couple that
processing head to the part to make an inspection, such as an
ultrasonic inspection, using that fluid as a coupling medium. Where
a CNC machine is equipped with flood coolant capability and the
coolant is sufficiently clean it is desirable to use it as the
coupling medium, however where it is not fit for purpose another
fluid can be delivered. The processing head making the inspection
may be the same or different to the processing head that deposits
the fluid. Here the fluid may be a gel or the like. The gel may be
termed a sacrificial material as it does not end up in the final
article and used as part of the inspection process.
[0371] An alternative processing head 1700 is shown in FIG. 27
having a 1702 in the form of a chisel. A surface of the work piece
can be treated with the chisel tip to reduce stress in the work
piece or a part of the work piece. The chisel tip may be kept
stationary or may be moved by movement of the spindle.
Alternatively they can be actuated by mechanical or ultrasonic
means which can be provided within the processing head.
[0372] In FIG. 28 the processing head 1800 has a tip in the form of
a pin 1802. The pin can be used to relieve stress and strain,
particularly tensile stress, in the work piece. Alternative
configurations of the tip of a processing head are shown in FIGS.
29a to 29d. The tip may have one, two, three or more pins. Arrays
of pins can be used as can be seen in FIGS. 29c and 29d. The
controller can choose a head with a particular arrangement of pins
to apply pressure to the required part of the work piece and the
arrangement selected is suited to the geometry of the work piece.
Alternatively, the selection of heads can be pre-determined using
planning software ahead of time such as with CAM software.
[0373] In FIGS. 29a to 29d the pins have a circular cross section
but the skilled person will appreciated that the pins may
alternatively have rectangular, hexagonal, square or other cross
sections. Such cross sections may be used if an array is required
in which there are not gaps or overlaps. The processing head is
actuated to impact upon or apply pressure to the work piece. This
process is referred to as peening. The application of pressure
relieves tensile stresses and applies compressive stresses to the
work pieces so improving the characteristics of the work piece. The
force results in material compression, which in many materials
contributes to better fatigue life and is less susceptible to
propagate cracks, with improved resistance to stress corrosion,
corrosion fatigue, and cavitation erosion. It will be appreciated
that a person skilled in the art will see the peening method shown
in these illustrations as interchangeable with all peening
varieties including shot, hammer, flail (roto), vibro, tup, dot,
needle, ultrasonic, micro, nano, and laser shock peening.
[0374] Alternative heads that can be used to needle or
ultrasonically peen the surface of the work pieces are shown in
FIGS. 30a to 30e. FIG. 30a shows a head having a continuous wheel
or roller and can be caused to apply a continuous pressure. The
discontinuous roller in FIGS. 30b and 30c can be used to apply
pressure intermittently and may be preferred to reduce the rigidity
required of the machine tool. It is desirable that the machine tool
or processing head be supplied with a force feedback mechanism to
apply a desired amount of pressure to the work pieces which can be
recorded and used in a metrology loop which monitors feedback
(including force and work piece temperature gradients) and adjusts
the process ideally in real time to ensure consistent treatment of
each work piece.
[0375] FIGS. 30d and 30e show variations in which an array of
wheels or rollers are used. The skilled person will appreciate that
the rollers can be arranged to have individual travel so that the
rollers can conform to a surface as they travel over it.
[0376] FIG. 31 shows an embodiment in which the processing head
comprises sets of arrays of rollers. A pair of arrays are arranged
to rotate about an axis parallel to the spindle and an array of
rollers is arranged to rotate about an axis perpendicular to the
axis of the spindle. As can be seen the rollers are arranged to act
on an upper surface and side surfaces of a wall part created on the
work piece.
[0377] In FIG. 32 is a side view of the processing head if FIG. 31
in which the set of rollers arranged to rotate about the spindle
axis can be seen more clearly.
[0378] FIGS. 33 to 34 show variations of the embodiment of FIG. 13
and the same reference numerals have been used for the same
features. In FIG. 33 a roller is combined with a laser cladding
head. This allows for hot rolling of the material immediately after
deposition on the work piece. Hot rolling of the work piece can
have benefits for the microstructure of the deposited material and
can also reduce the amount of force required to affect the material
properties. As referred to above the manifold and the processing
head are arranged to supply a cooling fluid to internal passageways
in the head and to the wheels or rollers to prevent overheating.
The roller is indexed around the spindle to ensure that the rolling
action is substantially parallel with the direction of
deposition.
[0379] FIG. 34 shows a processing head having a laser deposition
head and peening pins integrated around the head. This arrangement
allows hot peening, hammering, scarifying, and chiselling of the
work piece. As before, coolant is supplied to the processing head
and is circulated around the head to keep the pins cool. The
peening is carried out by striking the surface, of the part which
is hot, akin to the use of a blacksmith's hammer, and the impact of
the pins on the heated metal in a softened state is maximised while
the force is reduced compared to cold peening. The action of the
pins is mechanical and is controlled by the processing head but
alternatives such as delivery of the action by the machine tool or
by the use of ultra sound can be envisaged. As with the previous
head, it may be indexed around in order to add pressure in the wake
of the heated area from the laser. The pins can be attached such
that they could be displaced with a couple of mm of travel once the
appropriate force was exerted by them. To enable some travel of the
head the pin actuation can be countercyclical to a laser pulsing
frequency so as not to defocus the laser if the motion of the pins
is dependent on the Z axis of the CNC machine. It will also be
appreciated that a laser heat source has been shown here as an
example, but an arc, electron beam, microwaves, induction heaters,
or the like could also be useable.
[0380] When forces are high and especially when the forces are not
substantially symmetrical around the spindle centre line it is
desirable to have anti-rotation/torque blocks and/or thrust assist
collars and/or cowl mounts for the spindle as is known in the art
to assist with 90 degree or other angle heads. In some cases it
will be desirable to rotate the spindle when undertaking pressure,
impact, or stress relieving operations to help prevent bearing
surfaces from being damaged (such as by dimpling) due to
non-uniform loads.
[0381] It will be appreciated that the peening heads described
above can be used independently of the laser heads. Peening is then
carried out on work piece when it is cold or at least not so hot.
FIG. 35 is a variation of the processing head of FIG. 34 and has a
processing head having a laser deposition head and peening pins.
The same reference numbers are used for the same features. The head
is shown in more detail in FIG. 36. As in the head of FIG. 34 the
peening pins are integrated around the head. However in the head of
FIG. 34 the head is indexed around to follow a line of deposition,
in this head different pins can be activated in order to add
pressure in the wake of an area heated by the laser. The activation
may be by actuation of the peening pins or by a length increase of
individual pins so that the contact the surface before the other
pins. In another arrangement the pins are attached to the
processing head such that they can be displaced by a few mm of
travel once an appropriate force has been exerted on the pins. It
has been found that it is desirable to make the pin actuation
countercyclical to a laser pulsing frequency which prevent s the
laser defocusing which motion of the pin is dependent on the z axis
of a CNC machine. It will be appreciated that the energy source may
be exchanged for an alternative energy source such as an arc, an
electron beam, microwaves, induction heaters, or other equivalent
energy sources.
[0382] FIGS. 44 and 45 show alternative processing heads adapted to
carry out two processes. The heads in FIGS. 44 and 45 apply a
polymer extrusion to a work piece. In FIG. 44 processing head
comprises a polymer extrusion head 4400 attached to the tool holder
4402. The extrusion head comprises a body 4404 and a nozzle 4406.
The nozzle 4406 is surrounded by a compacting frame 4408. Heaters
4410 are located around the body 4404 of the extrusion head.
[0383] A screw 4412 connected to the tool holder 4402 rotates
within a bore 4414 of the head to move injection moulding pellets
4416 from the media feed 4418 towards the nozzle. As the pellets
move down the bore 4414 the pellets are melted by heat from the
heaters 4410 around the body. As the pellets melt the screw 4412,
which is driven by the spindle, plasticises the pellet material
ready for extrusion from the nozzle. As the material is being
extruded from the nozzle 4406 the compacting frame 4408
reciprocates up and down applying pressure onto the soft material
4420 in order to achieve full density of the extruded material.
[0384] FIG. 45 illustrates a modification of the head of FIG. 44.
The same reference numerals are used for the same features. In FIG.
45 an additional feature is that a continuous fibre 4422 is fed
into the head in a co-axial direction. The fibre 4422 feeds through
the melted polymer and is extruded through the nozzle 4406 with the
extruded polymer 4420. A knife 4424 is provided that operates to
cut the fiber periodically once it has been extruded. The knife can
cut the fibre when it is finished with each continuous feed. In
other embodiments the fibre is chopped periodically to produce a
chopped fibre reinforcement of the extruded material.
[0385] It will be appreciated that in an alternative arrangement
the polymer and the fibre could be fed from separate nozzles on the
same head or could be applied by different heads with the
processing heads being switched between the deposition steps.
[0386] The skilled person will also appreciate that the screw does
not need to be connected to the tool holder but may be located in
the receiving dock or even in the supply dock. The polymer may be
melted in the machine tool and merely fed to the processing head by
means of a heated tube connected or connectable to the body of the
processing head.
[0387] FIG. 37 shows a prior art deposition processing head in
which an electrode 3701 supplies energy to the work piece 3702 and
a wire 3703 is fed into the melt pool 3704. Typically this is done
just ahead of the electrode since feeding the wire ahead of the
electrode prevents the wire from snagging on the substrate. The
area generally indicated at 3705 is the dilution layer and heat
affected zone.
[0388] FIG. 38 shows a novel deposition head comprising an
electrode 3801 providing energy to a work piece 3802 and a media
feed 3803. The head comprises means for generating an integral
electromagnetic field 3804 which is arranged to bend an arc 3805
extending between the electrode and the work piece.
[0389] The electromagnetic field 3804 bends the arc 3805 to be
slightly ahead of the electrode 3801. The media feed 3803 in the
form of a wire can be feed substantially parallel to the electrode
so facilitating automation. The wire always feeds straight into the
weld pool 3806 and is unaffected by changes in the feed direction.
Should it be necessary the bend of the arc can be controlled by
changing the electromagnetic field applied to the arc. The
electromagnetic field 3804 can be controlled by changing the mode
of the electricity used to induce the field or can be changed by
controlling a position of the magnet or magnets.
[0390] FIG. 39 illustrates the control that can be achieved in the
location of the melt pool using the head of FIG. 38. The position
of the electrode was not changed but the polarity of the field
powering the electromagnet was reversed. In this case the weld pool
location was moved by approximately 10 mm. The displacement of the
weld pool allows the wire to be fed co axially with the electrode.
It will be appreciated that the arc may be intentionally shifted to
an alternative position other than a co-axial location of the wire
if so desired.
[0391] FIGS. 40 and 41 illustrate processing heads 4001 that can
hold various components 4002. In FIG. 41 the components 4002 are
held inside the processing head 4001 in a reservoir or storage
facility 4004 and the head 4001 is arranged to dispense the
components 4002 as required. In the embodiment of the FIG. 41 the
processing head 4001 can be replenished through a dock 4006 as
schematically indicated at 4008.
[0392] FIG. 42 illustrates an alternative processing head having a
body 4600 and a nozzle 4602.
[0393] The processing head is connectable to the carriage and has a
receiving manifold 4604 located on a side face 4606 of the body.
The receiving manifold 4604 comprises an opening 4608 having a
closure 4610 arranged to be moveable in a track 4612 between a
closed position in which the closure is over the opening and an
open position 4614 as can be seen in FIGS. 42 and 43. An actuator,
not visible, is arranged to move the closure form the closed to the
open position in the docking operation and to move the closure from
the open to the closed position in the undocking operation. In the
closed position the interior of the processing head is sealed from
the environment. In the open position docking of power and media
supplies can be arranged through the opening. In the docked
position the path for power and media supply through the opening
and into the processing head is sealed from the environment.
[0394] It will be appreciated that a number of different concepts
have been described herein. The skilled person will appreciate that
these may be used alone or in combination with the other concepts
described herein.
* * * * *