U.S. patent application number 16/076008 was filed with the patent office on 2021-06-24 for reconfigurable machining center.
The applicant listed for this patent is Universita degli Studi di Genova. Invention is credited to Alessandro Arturo Bruzzone, Andrea Godani, Margherita Monti.
Application Number | 20210187679 16/076008 |
Document ID | / |
Family ID | 1000005477511 |
Filed Date | 2021-06-24 |
United States Patent
Application |
20210187679 |
Kind Code |
A1 |
Bruzzone; Alessandro Arturo ;
et al. |
June 24, 2021 |
Reconfigurable machining center
Abstract
A reconfigurable machining center includes a base structure
extending in a first direction, a movable crossmember movable in
the first direction and provided with a machining head, supporting
elements on the base structure to enable movement of the movable
crossmember along the first direction, a first leadscrew rack,
integral with the base structure and having a first helical
circular toothed sector, and extending along the entire base
structure parallel to the first direction, and a first screw
rotatably coupled to the movable crossmember and engaging a
corresponding first leadscrew rack, and having a rotation axis
parallel to the first direction. The longitudinal extension of the
base structure in the first direction is an integer multiple of the
pitch of tooth of the leadscrew racks, and the base structure
includes coupling elements adapted to couple the base structure to
a following and/or preceding adjacent base structure along the
first direction.
Inventors: |
Bruzzone; Alessandro Arturo;
(Genova, IT) ; Monti; Margherita; (Genova, IT)
; Godani; Andrea; (La Spezia, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Universita degli Studi di Genova |
Genova |
|
IT |
|
|
Family ID: |
1000005477511 |
Appl. No.: |
16/076008 |
Filed: |
February 10, 2017 |
PCT Filed: |
February 10, 2017 |
PCT NO: |
PCT/IB2017/050737 |
371 Date: |
August 7, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y10T 29/50 20150115;
B23Q 1/017 20130101; B23C 1/06 20130101; B23Q 1/012 20130101; B23Q
1/015 20130101; B23Q 5/40 20130101; F16H 25/2409 20130101; B23C
1/002 20130101; B23Q 37/005 20130101; B23Q 37/007 20130101; B23Q
1/46 20130101; Y10T 409/308288 20150115; Y10T 409/307952 20150115;
Y10T 409/309576 20150115; B23Q 1/44 20130101; B23C 1/08
20130101 |
International
Class: |
B23Q 1/44 20060101
B23Q001/44 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 10, 2016 |
IT |
102016000013699 |
Claims
1. A reconfigurable machining center (1, 100), comprising: a base
structure (2), which extends longitudinally in a first direction
(X); a first movable crossmember (3), which is supported to be
movable with respect to the base structure (2) in the first
direction (X) and is provided with an equipped machining head (4);
supporting elements that support the first movable crossmember (3)
on the base structure (2) and enable the first movable crossmember
to move along the first direction (X); a first leadscrew rack (5),
integral with the base structure (2) and comprising a first helical
circular toothed sector (51), the first leadscrew rack (5)
extending along the base structure (2) in a longitudinal direction
parallel to the first direction (X) for an entire extension of the
base structure in the first direction (X); and a first screw (6)
rotatably coupled to the first movable crossmember (3) by way of a
moving assembly (7), said first screw (6) engaging the first
leadscrew rack (5), the screw having a rotation axis parallel to
the first direction (X), wherein a longitudinal extension of the
base structure (2) in the first direction is an integer multiple of
a pitch of teeth of the first leadscrew rack (5), and wherein the
base structure (2) further comprises coupling elements (8) that are
adapted to couple the base structure (2) to one or both of a
following or preceding adjacent base structure (2'), along the
first direction (X).
2. The reconfigurable machining center (1, 100) according to claim
1, wherein: the base structure (2) comprises a second leadscrew
rack (5) parallel to the first leadscrew rack (5), the second
leadscrew rack comprising a second helical circular toothed sector
(51) with the same pitch of teeth as the first leadscrew rack or an
integer multiple thereof, the second leadscrew rack (5) extending
along the base structure (2) in a longitudinal direction parallel
to the first direction (X) for the entire extension of the base
structure in the first direction (X), and the machining center
comprises a second screw (6) rotationally coupled to the first
movable crossmember (3) by way of the moving assembly (7), said
second screw (6) engaging the second leadscrew rack (5), the second
screw having a rotation axis parallel to the first direction (X),
wherein the first and the second screw (6) define a same pair of
screws.
3. The reconfigurable machining center (1, 100) according to claim
1, wherein the supporting elements comprise bearings cooperating
with rails.
4. The reconfigurable machining center (1, 100) according to claim
2, wherein the supporting elements comprise one or both of said
first or said second leadscrew rack (5).
5. The reconfigurable machining center (1, 100) according to claim
2, wherein the moving assembly (7) is single for the first and the
second screw (6) of a same pair of screws and comprises a motor
(71) and a transmission shaft (72) that is common to the first and
to the second screw (6) of the same pair, each of the first and the
second screws (6) being coupled to said shaft (72), so that the
first and the second screws (6) of the same pair rotate
synchronously.
6. The reconfigurable machining center (1, 100) according to claim
1, wherein the equipped machining head (4) is adapted to move with
respect to the first movable crossmember (3) in a second direction
(Y), perpendicular to the first direction (X), a first plane on
which the first direction (X) and the second direction (Y) lie
being a horizontal plane when the machining center (1) is
operating.
7. The reconfigurable machining center (1, 100) according to claim
6, wherein the equipped machining head (4) comprises a tool-holder
(44) that is adapted to move with respect to the equipped head (4)
in a third direction (Z), perpendicular to said first plane.
8. The reconfigurable machining center (1, 100) according to claim
2, wherein the helical circular toothed sector (51) of one or both
of said first or said second leadscrew rack (5) is defined by a
center angle of amplitude comprised between 30.degree. and
90.degree., so that the first or the second leadscrew rack (5) has
a function of moving the first movable crossmember (3) with respect
to the base structure (2).
9. The reconfigurable machining center (1, 100) according to claim
2, wherein the helical circular toothed sector (51) of one or both
of said first or said second leadscrew rack (5) is defined by a
center angle of amplitude comprised between 90.degree. and
300.degree., so that the first or the second leadscrew rack (5) has
a function of moving and supporting the first movable crossmember
(3) with respect to the base structure (2), thus constituting at
least part of said supporting elements.
10. The reconfigurable machining center (1, 100) according to claim
1, further comprising a workpiece-holding table (10) arranged
parallel to the first movable crossmember (3) and supported to move
on said base structure (2) along a direction parallel to the first
direction (X).
11. The reconfigurable machining center (1, 100) according to claim
10, wherein the base structure (2) comprises a first leadscrew rack
of the workpiece-holding table (5''') integral with the base
structure (2), further comprising a first helical circular toothed
sector, the first leadscrew rack of the workpiece-holding table
(5''') extending along the base structure (2) in a longitudinal
direction parallel to the first direction (X) for the entire
extension of the base structure in the first direction (X), and
wherein the workpiece-holding table (10) comprises a first screw of
the workpiece-holding table (6''') rotatably coupled to the
workpiece-holding table (10) by way of a moving assembly, said
first screw of the workpiece-holding table (6''') engaging the
corresponding first leadscrew rack of the workpiece-holding table
(5'''), the first screw of the workpiece-holding table (6''')
having a rotation axis parallel to the first direction (X).
12. The reconfigurable machining center (1, 100) according to claim
11, wherein the base structure (2) comprises a second leadscrew
rack of the workpiece-holding table (5''') integral with the base
structure (2), further comprising a second helical circular toothed
sector, the second leadscrew rack of the workpiece-holding table
(5''') extending along the base structure (2) in a longitudinal
direction parallel to the first direction (X) for the entire
extension of the base structure in the first direction (X), and
wherein the workpiece-holding table (10) comprises a second screw
of the workpiece-holding table (6''') rotatably coupled to the
workpiece-holding table (10) by way of a moving assembly, said
second screw of the workpiece-holding table (6''') engaging with
the second leadscrew rack of the workpiece-holding table (5'''),
the second screw of the workpiece-holding table (6''') having a
rotation axis parallel to the first direction (X).
13. The reconfigurable machining center (1, 100) according to claim
1, further comprising an additional base structure (2') that
extends longitudinally in the first direction (X), further
comprising one or both of a first or a second leadscrew rack (5) of
the additional base structure, which are integral with the
additional base structure (2') and identical to the first or second
leadscrew rack (5) of the base structure (2), wherein the first or
the second leadscrew rack (5) of the additional base structure
extend along the additional base structure (2') in a longitudinal
extension parallel to the first direction (X) for the entire
extension of the additional base structure in the first direction
(X), wherein the longitudinal extension of the additional base
structure (2') in the first direction is a multiple of the pitch of
teeth of the leadscrew racks (5), and wherein, when the base
structure (2) and the additional base structure (2') are coupled,
one or both of the first or second leadscrew rack (5) of the
additional base structure are aligned and contiguous with the first
or second leadscrew rack (5) of the base structure (2), so as to
enable a modular coupling of a plurality of base structures (2, 2')
all extending in the first direction (X).
14. The reconfigurable machining center (1, 100) according to claim
1, wherein the base structure further contains at least two
electric conductors, and the moving assembly (7) comprises sliding
contacts.
15. The reconfigurable machining center (1, 100) according to claim
1, further comprising an electromagnetic source for an electric
power supply of motors present on the first movable crossmember by
way of an electromagnetic field.
16. The reconfigurable machining center (100) according to claim 1,
further comprising: a second base structure (200) that extends
longitudinally in a direction (X') parallel to the first direction
(X) of the first base structure (2); and a second leadscrew rack
(500), integral with the second base structure (200), which
comprises a second helical circular toothed sector, the second
leadscrew rack (500) extending along the second base structure
(200) in a longitudinal direction parallel to the first direction
(X) for the entire extension of the second base structure (200) in
the direction (X') parallel to the first direction (X), wherein: a
pitch of a tooth of the second leadscrew rack (500) of the second
base structure (200) is identical to the pitch of the tooth of the
leadscrew rack (5) of the base structure (2), and the longitudinal
extension of the second base structure (200) in the direction (X')
parallel to the first direction (X) is an integer multiple of the
pitch of tooth of the leadscrew racks (5, 500), further comprising
at least one distribution base structure (201) that is adapted to
move with respect to the base structure (2) in a distribution
direction (Ydist), perpendicular to the first direction (X),
wherein said distribution base structure (201) extends
longitudinally in a direction parallel to the first direction (X)
of the base structure (2), said distribution base structure (201)
comprising a distribution leadscrew rack (501) integral with the
distribution base structure (201), further comprising a respective
helical circular toothed sector, the distribution leadscrew rack
(501) extending along the distribution base structure (201) in a
longitudinal direction parallel to the first direction (X), so as
to be coupled without discontinuities in a helical thread
alternatively to the base structure (2) or to the additional base
structure (200) in order to enable a travel at least of said first
movable crossmember (3) between the base structure (2) and the
additional base structure (200).
Description
TECHNICAL FIELD
[0001] The present invention relates to the sector of machining
technologies and systems.
[0002] In particular, the invention relates to a machining center
according to the preamble of claim 1.
STATE OF THE ART
[0003] In the present invention the term "machining center" is used
to mean a system capable of transforming the characteristics of the
workpiece by way of operations that can employ subtractive,
additive, joining, and plastic deformation processes.
[0004] In general a machining center contains the following
elements: [0005] a device that supplies energy, by virtue of which
a relative coupled motion is obtained between the tool used to
provide the process and the workpiece; [0006] a device for fixing
the workpiece; [0007] a device for conveniently fixing and
orientating a tool; [0008] a device for controlling the three above
mentioned elements; [0009] a device for operating the tool
according to the used transformation process.
[0010] Below conventional solutions are described for machining
centers constituted by machine tools.
[0011] The latter use processes that modify the chemical/physical
characteristics of the material being machined such as its geometry
or its mechanical characteristics.
[0012] Other machining centers, apart from machine tools, are for
example centers (or stations) for welding, extrusion, shearing,
assembly, measuring and the like.
[0013] The characteristics of the machine tool, such as the number
and type of axes used for the relative motion between the tool and
the workpiece, the dimensions/travel of the axes, and power,
determine the production capacities of the machine tool,
conditioning the shape (geometry) of the workpieces that can be
made (prismatic, rotational), their dimensions, and the geometrical
accuracy of the products.
[0014] Based on flexibility, machine tools are classified as:
[0015] universal machines (multipurpose), conventional or
numerically controlled; these have the greatest flexibility and are
adapted to various different kinds of machining. [0016] automatic
machines for manufacturing high production volumes; these require
long setup times when the type of production changes. [0017]
special, single-purpose machines; these have no flexibility as they
are designed for a certain kind of machining.
[0018] Traditionally industry selects the type of machine tools on
the basis of the required production volume.
[0019] Production capacity increases by transitioning from the
universal machines to special machines, at the expense of the
variability of the products that can be made.
[0020] In order to overcome the limitations connected to
flexibility and production capacity, over the last 50 years
numerous solutions have been presented, such as flexible
manufacturing systems (FMS) which, although they have a greater
level of flexibility with respect to dedicated systems (lines with
automatic or special machines), have high costs that are not
justifiable when the production throughput requires lower
production capacities than the rated capacities of the system.
[0021] Starting in 1996 at the Engineering Research Center for
Reconfigurable Manufacturing Systems (ERC/RMS) of the University of
Michigan College of Engineering, the concept of a Reconfigurable
Manufacturing System was developed, which is defined as a system
"designed at the outset for rapid change in its structure, both for
its hardware and software components, in order to quickly adjust
its production capacity and functionality within a family of parts
in response to sudden changes in the market or in the requirements
imposed by regulations".
[0022] Reconfigurable Machine Tools (RMTs) are essential to
implementing such a system, as they extend the reconfigurability
concept from the system (RMS) to the machine tool.
[0023] In particular, reconfigurable machine tools have lower costs
than numerically controlled machines (CNC, for Computer Numeric
Control), since with respect to these they employ a customizable
flexibility that is the minimum necessary in order to manufacture
products that belong to a given family.
[0024] In addition to the customizable flexibility, RMTs should be
easily convertible, scalable, and use the same basic structure used
in other reconfigurable machines in order to ensure the necessary
modularity.
[0025] The first example of reconfigurable systems dates back to
1977: in Japan, MITI began the FMC program (Flexible Manufacturing
system Complex), which culminated in the construction of an
experimental factory in 1983 in Tsukuba.
[0026] This study is considered an important reference point
because it was the first system that was designed to be modular and
variously assemblable according to requirements.
[0027] The complex was made up of modular units consisting of
machine tools and by assembly robots, with the goal of making a
variety of prismatic parts with corresponding packaging.
[0028] The modules were stored in a warehouse and assembled
according to the product to be made.
[0029] Once manufacturing was complete, the modules were
disassembled and returned to the warehouse.
[0030] Another large-scale project was set up by the European Union
in the early 1990s.
[0031] On the basis of a report commissioned by the European
Community, a survival strategy was formulated for the European
machine tool industry.
[0032] The report stated that if machine tools are designed and
built to be modular, the makers can specialize in providing
specific modules instead of complete systems.
[0033] Starting from integration modules, it is possible to build
the complete system according to the specific user
requirements.
[0034] Such strategy requires breaking a machine tool down into a
set of autonomous functional units provided with plug-and-play
interfaces, in order to build up systems according to specific
requirements.
[0035] In order to achieve this objective, several projects have
been carried out or are under development at European level.
[0036] The MOSYN (Modular Synthesis of Advanced Machine Tools)
project run by the University of Hanover analyzed the specific
configurations for customization.
[0037] The KERNEL program seeks to develop two different machine
tools using modules with identical axes.
[0038] The University of Stuttgart's "Special Research Program 467"
concentrates on transformable business structures for highly
variable mass production and on developing the capacities and
functionalities of machine tools so that they can be adapted to
sudden changes in the market.
[0039] Another project, called MOTION (Modular Technologies for
Intelligent Motion Unit with Linear Motor and Axis Control),
analyzed the possibility of using identical modules on different
machines and addressed the consequent design of the interfaces.
[0040] Since 1996, at the Engineering Research Center of
Reconfigurable Machining Systems (ERC/RMS), RMS technology has been
developed in three main fields: [0041] reduction of design times of
reconfigurable systems; [0042] design of reconfigurable machines
and of the related control systems; [0043] reduction of ramp-up
times.
[0044] The ERC/RMS studies the combination of modular machines and
controllers, the methods for the analysis and design of the
configuration of the systems, for the modeling, for the calibration
and the ramp-up of RMS systems.
[0045] Another research project developed by Carnegie Mellon
University in Pittsburgh, Pa., called Reconfigurable Modular
Manipulator System, studies the development of plug-and-play
modules that can be assembled in a large number of different
configurations in order to adapt the kinematic and dynamic
properties of the manipulator to a specific purpose.
[0046] In Japan modules have been made with which it is possible to
assemble a complete industrial robot.
[0047] The problem of modularity and of reconfigurability has also
been addressed in the international Intelligent Manufacturing
Systems (IMS) project.
[0048] Another solution is disclosed in U.S. Pat. No. 6,920,973 in
which a multistage manufacturing system is proposed that uses
manufacturing cells, each of which is associated with at least one
step of the production process. Each cell has a hexagonal shape,
giving the system made up by joining multiple units a honeycomb
structure.
[0049] The cells must be such that the first has to comprise at
least one flexible manufacturing station, a second includes at
least one reconfigurable production station and a third is provided
with at least one reconfigurable inspection machine. The system has
to include a series of conveyor apparatuses that enable the
transfer of the parts being machined from one station to the others
available in the single production cell, and then from one cell to
the subsequent cells.
[0050] At the global scale, the three major projects dealing with
control systems with open architecture are the OSACA project,
commissioned by the European Union, with its German successor
HUMNOS; the OSEC project in Japan, and the North American OMAC-TEAM
project.
[0051] The main result of the OSACA project, started in 1992, is
the design oriented on the basis of the object to be made and the
use of an open architecture for the systems for controlling the
machines.
[0052] The OMAC project seeks to establish a series of programming
interfaces (Application Programming Interfaces, API) that can be
used by developer companies to sell products and services for
controlling machines for the aerospace and automobile
industries.
[0053] Finally, the HEDRA (Heterogeneous and Distributed Real-time
Architecture) project, sponsored by the EU, and the
previously-mentioned MOTION project have sought to develop control
systems capable of managing heterogeneous and distributed
processes, although this field of research has not yet been fully
explored.
[0054] Several examples of reconfigurable machine tools have been
proposed in the literature and/or claimed in patent
applications.
[0055] A purely manually-actuated version was proposed by P. O.
Aldrin.
[0056] This is a universal machine tool provided with a first
horizontal worktop on which, by way of an intermediate plate that
rotates about a vertical axis, it is possible to mount a second
worktable which can be oriented variously with respect to the first
one.
[0057] The two tables can be moved by way of a leadscrew
system.
[0058] A vertical column, perpendicular to the base structure, is
provided with a second plate that rotates around a horizontal axis
and is capable of translating vertically by way of a leadscrew
system. A rectangular worktop is mounted on it, on which it is
possible to install the rotating base for a motor. The latter
enables the actuation of a tool or of a self-centering head used to
support the workpiece being machined.
[0059] G. N. Bullen, working for the aerospace company Northrop
Grumman Corporation, has studied the problem with respect to the
production of male and female mold parts in plastic or metal for
making parts in composite material, such as material based on
fiberglass, graphite or carbon fiber. Such components are used for
building aircraft or to obtain life-size models for aerodynamic
testing in wind tunnels. It has been observed that using
traditional manufacturing techniques to make these dies, which have
extremely complex shapes and often also have holes, is very
laborious and therefore expensive. The solution proposed by Bullen
provides for a reconfigurable machine tool composed of a platform
on which a worktable is moved that is translatable and able to
rotate between 0.degree. and 90.degree.. A gantry structure allows
movement along the X and Y axes of a robotized multiaxis head that
carries the tool, constituting the end effector of the Z axis of
the machine. The operation is managed by numerical control, with a
control panel set on the unit itself. On the workpiece-holding
table, the object being machined is kept in position by clamps or
by pneumatic devices, both high-precision and re-adaptable
according to the dimensions of the workpieces. Single machines then
form the modules of an RMS. In fact the ability to rotate the
worktop between 0.degree. and 90.degree. makes it possible, at the
end of the machining carried out simultaneously by different
stations, to join the parts by interlocking and transport them by
way of rails to other production cells of the same type, arranged
to form an assembly line.
[0060] One case that is often cited in the literature relating to
reconfigurable machine tools is the Arch-Type RMT, developed at the
University of Michigan.
[0061] The project started from the need to make cylinder heads for
engines with six and eight cylinders, with different
inclinations.
[0062] The RMT obtained, which was therefore designed to make a
specific family of parts, has the spindle installed on an arched
movement support that makes it possible to vary the angle of
machining and to carry out milling and drilling operations on the
parts.
[0063] This machine was developed after a first prototype proposed
by Y. Koren and S. Kota, which had a base structure, a supporting
structure for the castings to be machined, and modules that can be
installed on a rail so as to be able to pass from a configuration
with two axes to one with three axes.
[0064] The model that served as the starting point for the
development of the Arch-Type RMT is the one disclosed in the patent
filed by the two researchers.
[0065] The workpiece to be machined is fixed to the suitable
worktop while two arched supporting units allow the movement of at
least one single-axis spindle.
[0066] In this manner, the spindles, with the tools mounted, can be
easily moved by way of numeric control so as to execute the
machining operations according to different positions and
orientations with respect to the workpiece.
[0067] Given the modularity of the machine, the arched supports can
be variously arranged, taking advantage of the couplings present on
the base structure.
[0068] Despite what is recited by the patent just described, the
Arch-Type differs from the RMT approach due to the rigidity of its
architecture, the lack of modularity and the need for intervention
by the operator in order to manually reorient the non-perpendicular
axis in the machine in various discrete positions.
[0069] There are two other examples of RMTs that do not entail the
use of the usual Cartesian reference system.
[0070] The first is the Parallel Kinematic Machine (PKM) developed
by Z. M. Bi at the University of Indiana. This is a machine with a
gantry structure that supports a tripod actuator equipped with
three degrees of freedom and with a passive arm. The
workpiece-holding table allows the object to be machined to be
moved on the X and Y axes of the plane, giving the machine two
other degrees of freedom. Finally, the bridge to which the tripod
actuator is anchored can be made to rotate about its own axis.
[0071] As previously mentioned, although it is more sophisticated
in terms of kinematic modeling and of control, by virtue of the
modularity of its components a PKM can be easily re-adapted to
carry out varieties of machining, even if these are mutually very
different.
[0072] The second example is represented by the reconfigurable
machine tool proposed and patented by J. K. Park and
colleagues.
[0073] It has a tripod supporting structure raised off the ground,
which supports two intersecting circular frames, each one capable
of rotating about its own axis. A sliding component is fixed to the
two circular frames, in a circumferential position, and a spindle
is fixed vertically to it which can therefore be moved and rotated
around the workpiece, being thus able to execute three-dimensional
machining operations.
[0074] For simpler geometries the modularity of this RMT is
exploited by using a single circular frame with the sliding
carriage block and the spindle mounted on it.
[0075] This structure therefore makes it possible to considerably
simplify the machine tool which frequently requires up to five
axes, becoming very large and complicated, and avoids the problems
associated with the vibrations that can arise, traditionally due to
the tool which behaves like a cantilevered beam.
[0076] X. Chao and colleagues have patented a reconfigurable
cutting machine tool. This structure is provided with a base, a
module provided with a self-centering head for holding the
workpieces, a support for such workpieces and a movable turret
capable of carrying a thermal cutting torch which is numerically
controlled.
[0077] Each module is provided with standardized interfaces that
make it possible to reconfigure the machine each time the
production strategy or the type of cutting operations to be carried
out changes.
[0078] The machine tool proposed by S. Ongaro enables the
combination of a series of modular units that can work on a same
workpiece in a mutually coordinated manner without the necessity of
having to reposition it after each operation, as usually
happens.
[0079] The raw workpiece to be machined is supported by two
mutually opposite supporting structures that make it rotate about
an axis parallel to the main axis.
[0080] The modules provided with spindles and/or tools are moved on
their guides which are conveniently brought to and away from the
workpiece, making it possible to execute multiple operations
simultaneously and independently of each other, such as turning,
milling, or gears cutting.
[0081] D. P Weidman, H. K. Patel, J. W. Dillman and G. L. Headrick
have invented modules that serve as elements that make up the
longitudinal axis of a machine tool.
[0082] By adding various units in series, it is possible to obtain
different configurations according to the particular object that is
to be machined.
[0083] The extendable axis thus obtained can become the base for a
gantry structure or for a transverse axis on which the spindle is
mounted in a cantilever fashion.
[0084] The movement of the transverse body of the machine is
ensured by way of recirculating ball or leadscrew systems.
[0085] To conclude, it is mentioned the bench-mounted numerically
controlled reconfigurable machine tool patented by L. Kui and
colleagues.
[0086] It is constituted by a series of modules that comprise a
base structure, lathe headstock and tailstock, a column support,
the spindle box and a storage area for spindles and tools.
[0087] By having the possibility to variously organize the basic
units that make up the machine so that they can execute very
diversified turning and milling operations, the costs of machining
operations carried out on objects of small dimensions can be kept
down.
[0088] Various different systems of moving an axis to produce
linear motion, by way of devices constituted by recirculating-ball
or rack-and-leadscrew systems, have been claimed by several
inventors.
[0089] For example, although constituting a valid example of an
RMT, the patent proposed by D. P. Weidman and colleagues adopts a
conventional recirculating-ball leadscrew coupling, with the
leadscrew fixed to the supports of the crossbeam while the screw,
actuated by a motor, is arranged in the recess present in the
modules.
[0090] This solution, although valid, is affected by the constraint
represented by the necessity of having maneuvering screws of
different length in function of the useful travel that it is
desired to give the machine.
[0091] Examples of machine tools that use the mating of an endless
screw with a rack can be found in some planer machines produced
between the end of the nineteenth century and the start of the
twentieth century by the American company William Sellers &
Co.
[0092] In the various different versions of such machine tools,
there was a screw with multiple starts that engaged on the rack
installed under the workpiece-holding table of the planer; the
whole was designed so that six teeth of the rack were always
engaged with the screw. The system for transmission of power from
the motor to the shaft of the screw was designed to ensure the
correct engagement of the screw on the teeth.
[0093] However, in these cases the screw is inclined with respect
to the female thread with consequent reactions directed along the
axis of the screw.
[0094] An arrangement with the two elements, screw and rack,
mutually aligned can be found for example in large parallel lathes
for longitudinally moving the first saddle of the tool-holder
block. In such configuration the length of the rack is preset, and
it reacts to only the forces directed along the longitudinal axis,
the other components of the forces generated during the cutting
being supported by the two parallel guides.
[0095] The reconfigurable machine tools offered today have
predefined work volumes, and modifying these requires complex
interventions such as the substitution of some components: for
example if the travel of a linear axis is increased, the leadscrew
system requires at least the substitution of the screw with another
of greater length.
[0096] From all the foregoing it evidently follows that, although
they are to a certain degree effective, the machining centers
currently available have a number of drawbacks.
OBJECTS AND SUMMARY OF THE INVENTION
[0097] The aim of the present invention is to overcome the
drawbacks of the background art.
[0098] Within this aim, an object of the present invention is to
make it possible to modify the dimension of the travel length of at
least one linear axis of machining centers, in particular of
reconfigurable machine tools, without requiring complex
interventions such as the substitution of components that already
are part of the machine to be modified.
[0099] Another object of the present invention is to be able to
vary the number of tools/devices that machine the workpiece without
requiring a modification of the elements (spindles, extrusion heads
etc.) that already operate on the machining center, in particular a
machine tool.
[0100] Another object of the invention is to obtain a system that
is easily modifiable without the intervention of specialist labor
or complex technologies.
[0101] This aim and these and other objects which will become
better apparent hereinafter are achieved by a machining center, in
particular a machine tool, according to the appended claim 1, which
optionally incorporates the characteristics of the dependent
claims, which form an integral part of the present description.
[0102] The general idea underlying the present invention is to
provide a reconfigurable machining center that comprises: [0103] a
base structure which extends longitudinally in a first direction,
[0104] a first movable crossmember which is supported so that it
can move with respect to the base structure in the first direction
and is provided with an equipped machining head, [0105] supporting
elements for supporting the movable crossmember on the base
structure so that it can move along the first direction, [0106] a
first leadscrew rack, integral with the base structure, which
comprises a first helical circular toothed sector, the leadscrew
rack extending along the base structure in a longitudinal direction
parallel to the first direction for the entire extension of the
base structure in the first direction, [0107] a first screw
rotationally coupled to the movable crossmember by way of a moving
assembly, the screw engaging with the corresponding first leadscrew
rack, the screw having its rotation axis parallel to the first
direction,
[0108] wherein the longitudinal extension of the base structure in
the first direction is an integer multiple of the pitch of the
teeth of the leadscrew racks,
[0109] and wherein the base structure further comprises elements
for coupling that are adapted to couple the base structure to a
following and/or preceding adjacent base structure, along the first
direction.
[0110] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the base structure comprises a second leadscrew rack parallel to
the first leadscrew rack, the second leadscrew rack comprising a
second helical circular toothed sector with the same pitch of teeth
of the first leadscrew rack or a multiple thereof, the leadscrew
rack extending along the base structure in a longitudinal direction
parallel to the first direction for the entire extension of the
base structure in the first direction, and the machining center
comprises a second screw rotationally coupled to the movable
crossmember by way of a moving assembly, the second screw engaging
with the corresponding second leadscrew rack, the second screw
having its rotation axis parallel to the first direction, wherein
the first and the second screw define a same pair of screws.
[0111] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the supporting elements for supporting the movable crossmember on
the base structure so that it can move along the first direction
comprise bearings cooperating with rails.
[0112] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the supporting elements for supporting the movable crossmember on
the base structure so that it can move along the first direction
comprise the first and/or the second leadscrew rack.
[0113] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the moving assembly is single for the first and the second screw of
a same pair of screws and comprises a motor and a transmission
shaft that is common to the first and to the second screw of the
same pair, each screw being coupled to the shaft, so that the two
screws of the same pair rotate synchronously.
[0114] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the equipped machining head can move with respect to the
crossmember in a second direction, perpendicular with respect to
the first direction, a first plane on which the first and the
second directions lie preferably being a horizontal plane when the
machining center is operating.
[0115] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the equipped machining head comprises a tool-holder that can move
with respect to the equipped head in a third direction,
perpendicular to the first plane.
[0116] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the helical circular toothed sector of the first and/or the second
leadscrew rack is defined by a center angle of amplitude comprised
between 30.degree. and 90.degree., so that the first and/or the
second leadscrew rack have a function of moving the movable
crossmember with respect to the base structure.
[0117] Alternatively, according to an optional and advantageous
characteristic, taken alone or in combination with the foregoing
characteristics, the helical circular toothed sector of the first
and/or the second leadscrew rack is defined by a center angle of
amplitude comprised between 90.degree. and 300.degree., so that the
first and/or the second leadscrew rack have a function of moving
and supporting the movable crossmember with respect to the base
structure, thus constituting at least part of the supporting
elements.
[0118] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the machining center comprises a workpiece-holding table arranged
parallel to the movable crossmember and supported so that it can
move on the base structure along a direction parallel to the first
direction.
[0119] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the base structure comprises a first leadscrew rack of the
workpiece-holding table integral with the base structure,
comprising a first helical circular toothed sector, the first
leadscrew rack of the workpiece-holding table extending along the
base structure in a longitudinal direction parallel to the first
direction for the entire extension of the base structure in the
first direction and wherein the workpiece-holding table comprises a
first screw of the workpiece-holding table rotationally coupled to
the workpiece-holding table by way of a moving assembly, the first
screw of the workpiece-holding table engaging with the
corresponding first leadscrew rack of the workpiece-holding table,
the first screw of the workpiece-holding table having its rotation
axis parallel to the first direction.
[0120] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the base structure comprises a second leadscrew rack of the
workpiece-holding table integral with the base structure,
comprising a second helical circular toothed sector, the second
leadscrew rack of the workpiece-holding table extending along the
base structure in a longitudinal direction parallel to the first
direction for the entire extension of the base structure in the
first direction and wherein the workpiece-holding table comprises a
second screw of the workpiece-holding table rotationally coupled to
the workpiece-holding table by way of a moving assembly, the second
screw of the workpiece-holding table engaging with the
corresponding second leadscrew rack of the workpiece-holding table,
the second screw of the workpiece-holding table having its rotation
axis parallel to the first direction.
[0121] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the machining center comprises an additional base structure that
extends longitudinally in the first direction, comprising a first
and/or a second leadscrew rack of the additional base structure,
which are integral with the additional base structure and identical
to the first and/or second leadscrew rack of the base structure,
wherein the first and/or second leadscrew rack of the additional
base structure extend along the additional base structure in a
longitudinal direction parallel to the first direction for the
entire extension of the additional base structure in the first
direction, wherein the longitudinal extension of the additional
base structure in the first direction is a multiple of the pitch of
the teeth of the leadscrew racks, and wherein, when the base
structure and the additional base structure are coupled, the first
and/or the second leadscrew rack of the additional base structure
are aligned and contiguous with the first and/or the second
leadscrew rack of the base structure, so as to enable a modular
coupling of a plurality of base structures all extending in the
first direction in such a way as to allow the movement of the
screws between the base structures.
[0122] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the base structure furthermore contains at least two electric
conductors, and preferably the electric conductors are in the form
of electric tracks and the moving assembly comprises sliding
contacts.
[0123] According to an optional and advantageous characteristic,
taken alone or in combination with the foregoing characteristics,
the machining center comprises an electromagnetic source for the
electric power supply of the motors present on the crossmembers by
way of an electromagnetic field.
[0124] Further advantageous characteristics are the subject of the
appended claims, which should be understood to be an integral part
of the present description and of the detailed description
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0125] The invention will be described below with reference to
non-limiting examples, provided for explanatory and non-limiting
purposes in the accompanying drawings. These drawings show
different aspects and embodiments of the invention and, where
appropriate, reference numerals designating similar structures,
components, materials and/or elements in different figures are
designated by similar reference numerals.
[0126] In the accompanying figures:
[0127] FIG. 1 is a perspective view of an example of a machining
center according to the invention;
[0128] FIGS. 2 and 3 are two perspective views from different
angles of an equipped crossmember of the machining center according
to the invention;
[0129] FIG. 4 is an exploded perspective view of part of the
machining center of FIG. 1 and of a modular extension of the base
structure according to the present invention;
[0130] FIG. 5 is a schematic cross-sectional view of the machining
center of FIG. 1;
[0131] FIG. 6 is a perspective view of the base structure of the
machining center of FIG. 1;
[0132] FIGS. 7 and 8 are two perspective views from different
angles of a non-equipped movable crossmember of the machining
center of FIG. 1;
[0133] FIG. 9 is a simplified cross-sectional view of the assembly
for moving the screws, with the screws of the machining center of
FIG. 1 mounted;
[0134] FIG. 10 is a perspective view of a screw of the machining
center of FIG. 1;
[0135] FIG. 11 is a perspective view of the simplified
cross-section of the moving assembly of FIG. 9 with the screws
engaged in the leadscrew seats;
[0136] FIGS. 12 and 13 are respectively a perspective view and a
transverse cross-sectional view of the coupling between a screw and
an open leadscrew of the machining center of FIG. 1;
[0137] FIG. 14 is a perspective view of a variation of the base
structure of the machining center according to the invention;
[0138] FIG. 15 is a view of a variation of the assembly for moving
the screws with a variation of the screws that are applicable to a
variation of the base structure of the machining center according
to the invention;
[0139] FIGS. 16 and 17 are respectively a perspective view and a
transverse cross-sectional view of the coupling between a variation
of the screw and a variation of the open leadscrews that are
applicable to a variation of the base structure of the machining
center according to the invention;
[0140] FIG. 18 is a schematic cross-sectional view of another
variation of the machining center according to the invention;
[0141] FIG. 19 is a schematic cross-sectional view of a further
variation of the machining center according to the invention;
[0142] FIG. 20 is a perspective view of an advanced embodiment of
the machining center according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0143] Although the invention is susceptible of various changes and
alternative constructions, some preferred embodiments are shown in
the drawings and will be described below in detail.
[0144] It should be understood, however, that there is no intention
of limiting the invention to the specific embodiment shown, but, on
the contrary, it is intended to cover all the changes, alternative
and equivalents constructions, that fall within the scope of the
invention as defined in the claims.
[0145] The use of "for example", "etc.", and "or" indicates
non-exclusive alternatives without limitation, unless specified
otherwise.
[0146] The use of "includes" means "includes, but not limited to",
unless specified otherwise.
[0147] Indications such as "vertical" and "horizontal", "upper" and
"lower" (in the absence of other indications) must be read with
reference to the assembly (or operating) conditions and with
reference to the normal terminology in use in the current language,
where "vertical" indicates a direction that is substantially
parallel to that of the force of gravity vector "g" and
"horizontal" a direction perpendicular thereto.
[0148] With reference to FIGS. 1-13, a machining center according
to the invention, generally designated with the reference numeral 1
is generally and in detail shown.
[0149] The machining center 1 comprises a base structure 2 which
extends longitudinally in a first direction X.
[0150] Such base structure 2 is preferably made of metal and has a
substantially H-shaped transverse cross-section with respect to the
direction X, in this embodiment.
[0151] Other transverse cross-sections are possible, but all have
at least two parallel and mutually spaced apart vertical wings, 28,
29, which extend from the ground.
[0152] The base structure 2, generally speaking, comprises a first
leadscrew rack 5, integral with the base structure 2, which
comprises a first helical circular toothed sector 51, the leadscrew
rack 5 extending along the base structure 2 in a longitudinal
direction parallel to the first direction X for the entire
extension of the base structure in the first direction X.
[0153] The base structure in the embodiment shown for the purposes
of example in FIGS. 1-13 also comprises a second leadscrew rack 5,
parallel to the first.
[0154] Similarly, the second leadscrew rack 5 comprises a second
helical circular toothed sector 51 with a pitch of teeth preferably
equal to that of the first leadscrew rack or in an integer ratio
with the pitch of the first rack.
[0155] Also similarly, the second leadscrew rack 5 extends along
the base structure 2 in a longitudinal direction parallel to the
first direction X for the entire extension of the base structure in
the first direction X.
[0156] With reference to the base structure 2, this has a
longitudinal extension d (in the first direction X) which is an
integer multiple of the pitch of teeth of the leadscrew racks
5.
[0157] Since each rack 5 is as long as the base structure 2, it
immediately follows from this that the racks 5 also have a length
(in the direction X) that is equal to a multiple of the pitch of
teeth of the leadscrew racks.
[0158] By "pitch of teeth" what is meant, as is customary in the
technical field, is the distance between two homologous points of
two adjacent teeth of the helical thread measured along the
longitudinal axis (X axis).
[0159] By multiple, what is meant is preferably an integer
multiple.
[0160] In this manner, when two base structures 2, 2' provided as
just described (as in FIG. 4) are placed side by side (one
preceding and one following along the direction X), the leadscrew
racks 5 of the two base structures will have no interruptions in
the helical thread at the point of mutual mating, so that they
behave overall as a single thread without discontinuities in the
interface area of the two base structures.
[0161] The base structure 2 further comprises coupling elements 8
that are suitable to couple the base structure 2 to an adjacent
additional base structure 2', following and/or preceding, along the
first direction X.
[0162] Such coupling elements 8 are preferably conical seats
provided on one end side of the base structure 2 and complementary
conical protrusions provided on the opposite end side of the base
structure 2.
[0163] In this manner, two adjacent base structures 2, 2' can be
connected relatively rapidly and precisely, since the conical seats
and protrusions perform a self-centering function, which ensures
that the racks of the two base structures are aligned.
[0164] We will return to the second base structure 2' later.
[0165] The machining center 1 further comprises a first movable
crossmember 3 which is supported so that it can move with respect
to the base structure 2 in the first direction X and is provided
with an equipped machining head 4.
[0166] To this end, there are supporting elements for supporting
the movable crossmember 3 on the base structure 2 so that it can
move along the first direction X, and we will return to these
elements later.
[0167] The machining center 1 further comprises a first screw 6
rotationally coupled to the movable crossmember 3 by way of a
moving assembly 7.
[0168] The screw 6 has a helical threading adapted to cooperate
with the rack 5.
[0169] Preferably the helical thread of the screw 6 is trapezoidal,
but it could also be of a different type.
[0170] The screw 6 engages in fact with the corresponding leadscrew
rack 5 and has a rotation axis parallel to the first direction
X.
[0171] In the embodiment shown, there is also a second screw 6,
parallel to the first and rotationally coupled to the movable
crossmember 3 by way of a moving assembly 7.
[0172] In other embodiments (not shown) the second screw 6 (and
therefore the second rack) is absent and/or substituted by a
sliding bearing, for example a rail/slider coupling or the
like.
[0173] If it is present, the second screw 6 engages with the
corresponding second leadscrew rack 5.
[0174] The second screw 6 has its rotation axis parallel to the
first direction X and (therefore) parallel to that of the first
screw 6, so that the first and the second screw 6 can be considered
as belonging to the same pair.
[0175] Therefore, the movable crossmember 3 moves in the direction
X (both ways) along the base structure 2 or 2' by virtue of the
action of the screws 6 on the leadscrew racks 5.
[0176] From the foregoing description, it follows that a machining
center is provided that is extremely versatile, the length of which
in the direction X can be extended at will, it being sufficient
merely to add, relatively simply and inexpensively, a number of
additional base structures to the initial base structure.
[0177] Likewise, it follows that, owing to such length that can be
modified at will, there can be a plurality of crossmembers 3 with
equipped head 4 which operate on the same base structure.
[0178] With regard to the equipped head 4, it preferably can move
with respect to the crossmember 3 in a second direction Y
perpendicular with respect to the first direction X.
[0179] To this end the equipped head 4 is coupled to the
crossmember 3 by way of sliding bearing rails 43 adapted to enable
the movement of the head 4 in the direction Y.
[0180] In this sense, it is possible for the plane on which the
first direction X and the second direction Y lie to be a horizontal
plane (when the machining center is operational or installed in an
operational position).
[0181] Preferably, also, the equipped machining head 4 comprises a
tool-holder 44 that can move with respect to the equipped head 4 in
a third direction Z, perpendicular to the first plane.
[0182] To this end, the equipped head 4 comprises a frame 42 on
which a supporting column 41 is mounted, along which the
tool-holder 44 in turn performs a translational motion in the
direction Z, which, in the example provided and illustrated, is a
vertical direction.
[0183] In some embodiments, the tool-holder 44 is designed to
support and move a milling tool, while in other embodiments it is a
measurement tool, an extrusion head, a turning tool, a cutting
and/or welding head, or the like.
[0184] Moving on now to describe the supporting elements for
supporting the movable crossmember 3 on the base structure 2 so
that it can move along the first direction X, in the embodiment
shown in FIGS. 1-13, such elements comprise bearings 91 cooperating
with rails 92.
[0185] In the example, the bearings 91 are coupled to the
crossmember 3 and the rails 92 are coupled to the base structure 2,
parallel to the leadscrew racks 5 and suitably spaced apart from
them; in other embodiments the positions of the bearings 91 and the
rails 92 are reciprocated (bearings 91 on the base structure 2 and
rails 92 on the crossmember 3).
[0186] In an alternative embodiment, shown in FIGS. 14-17, the
supporting elements for supporting the movable crossmember 3 on the
base structure comprise (or, in a variation, are constituted only
by) the first and/or the second leadscrew rack 5'.
[0187] In the first case, i.e. when there are dedicated supporting
elements (e.g. bearings and rails or the like), the helical
circular toothed sector 51 of the leadscrew racks 5 is defined by a
center angle A (see FIG. 13) which can be of amplitude comprised
between 30.degree. and 90.degree.: in this case in fact the only
function of the first and/or the second leadscrew rack 5 is to move
the movable crossmember 3 with respect to the base structure 2.
[0188] In the second case, however, i.e. when dedicated supporting
elements are absent or when, although present, it is considered
that at least some of the functionality for supporting the
crossmember 3 should be borne by the leadscrew racks 5', it is
necessary that the helical circular toothed sector 51' of the
leadscrew racks 5' is capable of exercising such additional
function, and it is therefore advantageous to define it with a
center angle B (see FIG. 17) of amplitude comprised between
90.degree. and 300.degree..
[0189] In this way the first and/or the second leadscrew rack 5'
have, in addition to the movement function, the function of
supporting the movable crossmember 3 with respect to the base
structure 2, thus constituting at least part of such supporting
elements.
[0190] In some variations, as shown in FIG. 15, the screw or screws
6' have an intermediate portion in which the helical threading is
absent, for example in order to reduce friction, and only the end
portions 62' of the screw 6' are threaded.
[0191] As regards the motion imparted to the screws 6, 6', which
enables the movement of the crossmember 3 in the direction X, it is
obtained by way of a moving assembly 7, which generally comprises
at least one motor means coupled to the screw 6, 6'.
[0192] In the preferred and illustrated embodiment, there is one
moving assembly 7 for the first and the second screw 6 or 6' of a
same pair of screws.
[0193] The moving assembly 7 is accommodated on the movable
crossmember 3 and connected to both of the screws.
[0194] In the preferred embodiment, it comprises a motor 71 and a
common transmission shaft 72 for the first and the second screw 6
of the same pair.
[0195] Each screw 6 is therefore coupled to the shaft 72, for
example by way of bevel gears 61, so that the two screws 6 or 6' of
the same pair rotate synchronously, thus ensuring a steady traction
in the movement of the crossmember 3.
[0196] The motor 71 is preferably an electric motor, and to power
it the base structure comprises at least two isolated electric
conductors (not shown).
[0197] Preferably such conductors are in the form of electric
tracks and the assembly 7 comprises sliding contacts to
electrically power the motor 71.
[0198] Alternatively, the machining center comprises an
electromagnetic source for the electric power supply of the motors
present on the crossmembers by way of an electromagnetic field.
[0199] Moving on now to other variations of the invention, in one
of these, shown in brief in FIG. 19, the machining center 1 also
comprises a workpiece-holding table 10 arranged parallel to the
movable crossmember 3 and supported so that it can move on the base
structure 2 along a direction parallel to the first direction
X.
[0200] To this end the base structure 2 comprises preferably a
first leadscrew rack of the workpiece-holding table 5''' integral
with the base structure 2.
[0201] Similarly to the foregoing, the first leadscrew rack of the
workpiece-holding table 5''' comprises a first helical circular
toothed sector, the leadscrew rack of the workpiece-holding table
5''' extending along the base structure 2 in a longitudinal
direction parallel to the first direction X preferably for the
entire extension of the base structure in the first direction
X.
[0202] Similarly, the workpiece-holding table 10 comprises a first
screw of the workpiece-holding table 6''' rotationally coupled to
the workpiece-holding table 10 by way of a moving assembly (not
shown but similar to the assembly 7 described above).
[0203] The first screw of the workpiece-holding table 6''' has its
rotation axis parallel to the first direction X and engages with
the corresponding first leadscrew rack of the workpiece-holding
table 5''', so as to move the workpiece-holding table in a manner
similar to what is described above with reference to the
crossmember.
[0204] In some solutions a single screw/rack is sufficient to move
the workpiece-holding table 10 along the direction X.
[0205] In other solutions (as in the example shown), the base
structure 2 instead can comprise a second leadscrew rack of the
workpiece-holding table 5''' integral with the base structure
2.
[0206] Such second leadscrew rack of the workpiece-holding table
5''' comprises a second helical circular toothed sector.
[0207] The second leadscrew rack of the workpiece-holding table
5''' also extends along the base structure 2 in a longitudinal
direction parallel to the first direction X, preferably for the
entire extension of the base structure in the first direction
X.
[0208] The workpiece-holding table 10 similarly comprises a second
screw of the workpiece-holding table 6''' rotationally coupled to
the workpiece-holding table 10 by way of a moving assembly, the
second screw of the workpiece-holding table 6''' engaging with the
corresponding second leadscrew rack of the workpiece-holding table
5''', the second screw of the workpiece-holding table 6''' having
its rotation axis parallel to the first direction X.
[0209] Returning to FIG. 4, a basic modular implementation is
shown, in which the machining center 1 comprises an additional base
structure 2' that extends longitudinally in the first direction X,
and comprises in turn a first and/or a second leadscrew rack 5 of
the additional base structure, integral with the additional base
structure 2' and identical to the first and/or second leadscrew
rack 5 of the base structure 2.
[0210] The first and/or the second leadscrew rack 5 of the
additional base structure 2' extend along the latter in a
longitudinal direction parallel to the first direction X for the
entire extension of the additional base structure in the first
direction X.
[0211] The longitudinal extension of the additional base structure
2' in the first direction is, as for the base structure 2, a
multiple of the pitch of teeth of the leadscrew racks 5, so as to
provide the coupling advantages described above.
[0212] When a base structure 2 and an additional base structure 2'
are coupled, in fact, the first and/or the second leadscrew rack 5
of the additional base structure are aligned and contiguous with
the first and/or second leadscrew rack 5 of the base structure 2,
so as to enable a modular coupling of a plurality of base
structures 2, 2' which extend in the first direction X.
[0213] In an advanced embodiment of FIG. 20, the machining center
100 further comprises an additional base structure 200 that extends
longitudinally in a respective first direction X' parallel to the
first direction X of the first base structure 2.
[0214] In the embodiment shown in FIG. 20 the machining center 100
comprises (but is not limited to) three additional base structures
200, but there may also be only one, two, or more.
[0215] The additional base structure 200 is provided in a similar
manner to the base structure 2 described earlier.
[0216] In particular the additional base structure 200 comprises a
respective leadscrew rack 500 which is integral with the additional
base structure 200, and which comprises a respective helical
circular toothed sector.
[0217] The leadscrew rack 500 of the additional base structure 200
is extended along the latter in a respective longitudinal direction
parallel to the first direction X substantially for the entire
extension of the additional base structure 200 in the respective
first direction X', thus being parallel and co-planar with the rack
5 and with any other racks 500 of other additional base structure
200 that are optionally present.
[0218] In practice the base structure 2 and the additional base
structure or base structures 200 are substantially mutually
parallel; on this point it is emphasized that the additional base
structure 200 can comprise, in some embodiments, the same
characteristics described above for the base structure 2 and about
which we will say no more for the sake of brevity.
[0219] The pitch of teeth of the leadscrew rack 500 of the
additional base structure 200 is also identical to the pitch of
teeth of the leadscrew rack 5 of the base structure 2, so that a
crossmember 3, 300 that moves on the base structure 2 can also move
on the additional base structure 200 in the same way.
[0220] Similarly, the longitudinal extension of the additional base
structure 200 in the respective first direction X' is an integer
multiple of the pitch of teeth of the leadscrew racks 5, 500, so as
to enable a modularity of additional base structures that can be
extended along the axis X' indefinitely, similarly to what happens
for the base structure 2.
[0221] In order to allow the transfer at least of the crossmember
3, 300 from one base structure 2 to an additional base structure
200 (or between additional base structures 200), in this embodiment
100 there is at least one distribution base structure 201, which is
provided with dedicated leadscrew racks 501.
[0222] The distribution base structure 201 can move with respect to
the base structure 2 (and therefore with respect to the base
structures 200) in a distribution direction (Ydist) which is
perpendicular with respect to the first direction (X) (and
therefore with respect to the directions X').
[0223] To this end the machining center 100 comprises transverse
distribution tracks 900 mounted on a transverse distribution base
structure 211, which extend perpendicular to the base structures 2,
200, and means for moving the distribution base structure 201 along
the distribution tracks 900, for example an electric motor and an
adapted kinematic chain (not shown).
[0224] In the embodiment shown, the distribution tracks 900
comprise a rack with helical thread and a cooperating screw, in a
manner similar to that described above.
[0225] The distribution tracks 900 and the corresponding movement
systems extend longitudinally along the direction Ydist so as to
enable the movement of the distribution base structure 201 for a
length at least equal to that comprised between the base structure
2 and the additional base structure 200 that is furthest from the
base structure 2.
[0226] The leadscrew racks 500 of all the additional base
structures 200 have, at the end facing the distribution base
structure 201, leadscrew racks in which the helices have an
identical geometry to that of the helices present on the base
structure 2, so as to enable the crossmembers 3, 300 to move
between one and the next.
[0227] The distribution leadscrew rack 501 comprises a respective
helical circular toothed sector and is extended along the
distribution base structure 201 in a respective longitudinal
direction parallel to the first direction X, so as to be capable of
being coupled without discontinuities in the helical thread
alternatively to the base structure 2 or to the additional base
structure 200.
[0228] Thus a movement is enabled at least of the first movable
crossmember 3 between the base structure 2 and the additional base
structure 200 or between additional base structures 200.
[0229] The distribution base structure 201 is, in a preferred
embodiment, completely similar to the base structure 2 and 200
described previously.
[0230] The distribution transverse base structure 211 extends
longitudinally in the distribution direction Ydist, parallel to the
first direction X of the base structure 2 with a length that can be
modulated at will, in a similar manner to the foregoing; to this
end in fact the leadscrew racks of the distribution tracks 900 will
preferably be made in a similar manner to the leadscrew racks 5,
500 in terms of the threading, so that multiple distribution
transverse base structures 211 can be joined together to provide a
distribution path that extends in the direction Ydist, the length
of which can be determined at will as a function of the operating
needs.
[0231] Although Ydist is shown in FIG. 20 as a direction that lies
substantially on a horizontal plane, it should be understood that
its arrangement can (in other configurations, not shown) vary; for
example Ydist is a direction that lies substantially on a vertical
plane.
[0232] Thus the above mentioned objects are achieved.
[0233] Naturally, many variations of what is described up to now
are possible, all of which should be considered equivalent to what
is claimed later.
[0234] The content of Italian patent application no.
102016000013699 (UB2016A000624), the priority of which is claimed
in the present application, is incorporated as a reference.
[0235] Where the technical features mentioned in any claim are
followed by reference numerals and/or signs, those reference
numerals and/or signs have been included for the sole purpose of
increasing the intelligibility of the claims and accordingly, such
reference numerals and/or signs do not have any limiting effect on
the interpretation of each element identified by way of example by
such reference numerals and/or signs.
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