U.S. patent application number 16/816373 was filed with the patent office on 2020-07-02 for device and method for additive casting of metallic parts.
This patent application is currently assigned to MAGNUS METAL LTD.. The applicant listed for this patent is MAGNUS METAL LTD.. Invention is credited to Gil LAVI, Boaz VINOGRADOV.
Application Number | 20200206810 16/816373 |
Document ID | / |
Family ID | 65722598 |
Filed Date | 2020-07-02 |
![](/patent/app/20200206810/US20200206810A1-20200702-D00000.png)
![](/patent/app/20200206810/US20200206810A1-20200702-D00001.png)
![](/patent/app/20200206810/US20200206810A1-20200702-D00002.png)
![](/patent/app/20200206810/US20200206810A1-20200702-D00003.png)
![](/patent/app/20200206810/US20200206810A1-20200702-D00004.png)
![](/patent/app/20200206810/US20200206810A1-20200702-D00005.png)
United States Patent
Application |
20200206810 |
Kind Code |
A1 |
LAVI; Gil ; et al. |
July 2, 2020 |
DEVICE AND METHOD FOR ADDITIVE CASTING OF METALLIC PARTS
Abstract
A method and an apparatus for additive casting of parts is
disclosed. The method may include: depositing, on a build table, a
first portion of a mold, such that, the depositing may be performed
layer by layer; pouring liquid substance into the first portion of
the mold to form a first casted layer; solidifying at least a
portion of the first casted layer; depositing a second portion of
the mold, on top of the first portion of the mold; pouring the
liquid substance into the second portion of the mold to form a
second casted layer, on top of at least a portion of the first
casted layer; and solidifying at least a portion of the second
casted layer. The method may further include joining the first and
second casted layers prior to the pouring of a third casted
layer.
Inventors: |
LAVI; Gil; (Ness Ziona,
IL) ; VINOGRADOV; Boaz; (Rehovot, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAGNUS METAL LTD. |
Ness Ziona |
|
IL |
|
|
Assignee: |
MAGNUS METAL LTD.
Ness Ziona
IL
|
Family ID: |
65722598 |
Appl. No.: |
16/816373 |
Filed: |
March 12, 2020 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/IL2018/051006 |
Sep 6, 2018 |
|
|
|
16816373 |
|
|
|
|
62557167 |
Sep 12, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 80/00 20141201;
B22F 3/008 20130101; B29C 64/124 20170801; B29C 64/268 20170801;
B33Y 70/10 20200101; B29C 64/40 20170801; B29C 64/106 20170801;
B22D 23/00 20130101; B33Y 40/20 20200101; B33Y 50/02 20141201; B29C
64/30 20170801; B33Y 30/00 20141201; B33Y 10/00 20141201 |
International
Class: |
B22D 23/00 20060101
B22D023/00; B29C 64/124 20060101 B29C064/124; B29C 64/268 20060101
B29C064/268 |
Claims
1. A method of additive casting of parts, comprising: depositing,
on a build table, a first portion of a mold, wherein the depositing
is performed layer by layer; pouring a molten metal into the first
portion of the mold to form a first casted layer; solidifying at
least a portion of the first casted layer; depositing a second
portion of the mold, on top of the first portion of the mold;
pouring the molten metal into the second portion of the mold to
form a second casted layer, on top of at least a portion of the
first casted layer; and solidifying at least a portion of the
second casted layer.
2. The method of claim 1, further comprising: receiving a
three-dimensional (3D) part model comprising one or more parts, the
part model is divided into a plurality of casted layers.
3. The method of claim 1, further comprising: joining the first and
second casted layers prior to the pouring of a third casted
layer.
4. The method of claim 3, wherein joining comprises melting at
least a portion of the interface between the first and second
casted layers.
5. The method of claim 3, wherein joining comprises treating at
least a portion of an upper surface of the second casted layer with
at least one of: an induction heater, a resistance welder, an
ultrasonic welder, plasma deposition unit, E-beam, a laser, a
welding arc, a torch, cold fusion and magnetic field flow.
6. The method of claim 1, further comprising: pre-heating each
casted layer prior to the pouring of an additional casted
layer.
7. The method of claim 1, further comprising: providing surface
treatment to each casted layer after solidification and prior to
the pouring of an additional casted layer.
8. The method of claim 1, further comprising: providing surface
treatment to internal walls of each mold portion prior to the
pouring of the corresponding casted layer.
9. The method of claim 1, further comprising leveling the first
casted layer and the first mold portion to be in the same level
prior to the deposition of the second mold portion.
10. The method of claim, wherein the depositing and pouring steps
are performed under a protective atmosphere.
11. The method of claim 1, wherein each mold layer comprises a
mixture of granular material and a binder, wherein the granular
material may include at least one of: ceramic powders, sand, clay,
and any combination thereof.
12. The method of claim 1, wherein: the first casted layer is
casted by pouring a first molten metal having a first chemical
composition; and the second casted layer is casted by pouring a
second molten metal having a second chemical composition.
13. The method of claim 1, wherein pouring the molten metal into
the second mold portion is in an amount sufficient to form the
second casted layer and to compensate for at least one of:
shrinkage of the first casted layer and thickness deviation in the
first casted layer.
14. An additive casting apparatus comprising: a movable dispensing
unit in fluid connection with a first container containing mold
material, the dispensing unit comprising one or more liquid
introduction ports for depositing the mold material; a movable
pouring unit in fluid connection with at least one second container
for holding a molten metal, the pouring unit comprising one or more
liquid introduction ports for pouring at least one molten metal; a
build table for holding the deposited mold material and the poured
molten metal; and a controller configured to: control the movable
dispensing unit to deposit a first portion of a mold, layer by
layer; control the movable pouring unit to pour at least one liquid
substance into the first portion of the mold to form a first casted
layer; control the movable dispensing unit to deposit a first
portion of a mold, layer by layer, on top of the first portion; and
control the movable pouring unit to pour the at least one molten
metal into the second portion of the mold to form a second casted
layer on top of at least a portion of the first casted layer.
15. The additive casting apparatus of claim 14, further comprising:
a joining unit configured to join the first and second casted
layers prior to a deposition of a third mold portion and the
pouring of a third casted layer.
16. The additive casting apparatus of claim 15, wherein the joining
unit is at least one of: an induction heater, E-beam, a resistance
welder, an arc welder, a laser welder, a torch, a gluing device, a
cold fusion unit, a magnet for magnetic field flow, an ultrasonic
bonding unit and a heater for diffusion bonding.
17. The additive casting apparatus of claim 14, wherein the at
least one second container is a crucible and the liquid substance
is one of: a molten metal and molten glass.
18. The additive casting apparatus of claim 14, further comprising
a pre-heating unit for heating each casted layer prior to pouring
an additional casted layer.
19. The additive casting apparatus of claim 14, further comprising:
one or more surface treatment units for treating the surface of
each casted layer after the solidification and prior to pouring an
additional casted layer.
20. The additive casting apparatus of claim 14, further comprising:
an enclosure filled with protective atmosphere for providing the
protective atmosphere to the casted layers during casting.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation in Part application of
PCT International Application No. PCT/IL2018/051006, International
Filing Date Sep. 6, 2018, claiming the benefit of U.S. Patent
Application No. 62/557,167, filed Sep. 12, 2017, which are hereby
incorporated by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] The application generally relates to the field of casting
parts. More specifically the application relates to the field of
additive casting of parts.
BACKGROUND OF THE INVENTION
[0003] Casting is one of the oldest material-forming methods still
used today. The idea of pouring liquid material into a mold which
contains a hollow cavity of the desired shape and then allowed it
to solidify is 6000-year-old. The principal process has not changed
since 3200 BC when bronze was melted and poured into a stone mold.
When glass was invented around 3000 years ago, glass was also
casted in molds (in addition to the glass blowing process) in order
to form articles made from glass. In modern days, polymer resins
are also casted into molds in order to form shaped polymeric
parts.
[0004] Modern casting methods involve the use of molds made from
various materials, such as sand casting, die casting (e.g., a
metallic mold), semi-die casting (e.g., metallic mold+sand
inserts), investment casting (e.g., a ceramic shell mold), lost
foam casting (e.g., relapsing polymeric foam with molten metal
placed in a sand container) and the like. However, the idea of
pouring all the required amount of metal in order to form a desired
object/part at a single pouring act has not changed.
[0005] Casting, although being a very reliable method is also very
expensive, time consuming, and is adapted for large production
quantities. The time required in order to form the molds of die
casting or make a mold for sand casting molds is typically several
months. Furthermore, even the most modern casting methods are not
flexible to changes. Every little change to the mold makes the
process more expensive and delays the production time.
[0006] Printing three-dimensional (3D) objects is one of the newest
material-forming methods. Inks made from polymer resins, metallic
powders mixed with binders or ceramic powders mixed with binders
are printed on a build table, sometimes with the addition of a
printed shell/support structure to support the printed object. A 3D
computerized model is used to create the printed object.
Accordingly, any change in the 3D model is easily implemented
without the need to change any of the printing parameters. However,
the quality of the printed part, (for example, mechanical
properties, material defects, voids and dislocations) in particular
metal printed parts that further require heat treatment processes
are often inferior to the quality of casted parts.
[0007] Currently used processes for three-dimensional printing of
metal objects includes deposition of metal powder/particles, layer
by layer, followed by a selective laser sintering (SLS) to
melt/solidify the fine deposited layer. Another process includes
printing a wax pattern of the mold by a three-dimensional printer,
for subsequent use in an investment casting to fabricate a metal
object. However, because the three-dimensional printing results are
the fabrication of the mold rather than the finished metal object
itself, additional stages of gravitational casting are required in
order to finish the metal object.
[0008] Therefore, there is a need for a system and a method that
obviate the disadvantages of the above production methods.
SUMMARY OF THE INVENTION
[0009] Some aspects of the invention may be directed to a method of
additive casting of parts. In some embodiments, the method may
include: depositing, on a build table, a first portion of a mold,
such that, the depositing is performed layer by layer; pouring
liquid substance into the first portion of the mold to form a first
casted layer; solidifying at least a portion of the first casted
layer; depositing a second portion of the mold, on top of the first
portion of the mold; pouring the liquid substance into the second
portion of the mold to form a second casted layer, on top of at
least a portion of the first casted layer; and solidifying at least
a portion of the second casted layer.
[0010] In some embodiments, the method may further include
receiving a three-dimensional (3D) part model including one or more
parts, the part model is divided into a plurality of casted layers.
In some embodiments, the method may further include receiving a 3D
mold model, the mold model is divided into a plurality of mold
portions, wherein the mold model is design to provide a desired
shape to the liquid substance. In some embodiments, the method may
further include generating a 3D mold model based on the received
part model, the mold model is divided into a plurality of mold
portions, wherein the mold model is design to provide a designed
shape to a liquid substance.
[0011] In some embodiments, the liquid substance is one of: a
molten metal, a molten glass and a polymer resin. In some
embodiments, the method may further include joining the first and
second casted layers prior to the pouring of a third casted layer.
In some embodiments, joining may include melting at least a portion
of the interface between the first and second casted layers. In
some embodiments, joining may include treating at least a portion
of an upper surface of the second casted layer with at least one
of: an induction heater, a resistance welder, an ultrasonic welder,
plasma deposition unit, E-beam, a laser, a welding arc, a torch,
cold fusion and magnetic field flow. In some embodiments, joining
may include at least one of: gluing, ultrasonic bonding, diffusion
bonding, heat curing and ultraviolet (UV) curing.
[0012] In some embodiments, the method may further include
pre-heating each casted layer prior to the pouring of an additional
casted layer. In some embodiments, the method may further include
providing surface treatment to each casted layer after
solidification and prior to the pouring of an additional casted
layer. In some embodiments, the surface treatment may include at
least one of: machining, grinding, polishing and laser ablation. In
some embodiments, the method may further include: providing surface
treatment to internal walls of each mold portion prior to the
pouring of the corresponding casted layer. In some embodiments, the
surface treatment to internal walls of each mold portion may
include machining the internal walls and removing the excess
material.
[0013] In some embodiments, the method may further include leveling
the first casted layer and the first mold portion to be in the same
level prior to the deposition of the second mold portion. In some
embodiments, the depositing and pouring steps are performed under a
protective atmosphere. In some embodiments, the first and second
casting layers have different thicknesses. In some embodiments, the
first and second casted layers have thickness of between 0.1-12 mm.
In some embodiments, each mold layer may include a mixture of
granular material and a binder, wherein the granular material may
include at least one of: ceramic powders, sand, clay, and any
combination thereof. In some embodiments, the mixture may further
include metallic powder.
[0014] In some embodiments, depositing the one or more mold layers
may include printing each mold layer using a 3D printer. In some
embodiments, pouring the liquid substance is from a movable pouring
unit including at least one liquid introduction port for pouring
liquid substance. In some embodiments, the movable pouring unit may
be configured to pour a predetermined amount of liquid substance at
predetermined locations in each mold portion. In some embodiments,
the method may further include annealing the solidified first
casted layer by pouring molten metal to form a third and a fourth
casted layers. In some embodiments, the first casted layer is
casted by pouring a first liquid substance having a first chemical
composition; and the second casted layer is casted by pouring a
second liquid substance having a second chemical composition. In
some embodiments, the first liquid substance and the second liquid
substance may be selected from: two alloys of the same metallic
element, two types of glass and two types of polymers.
[0015] In some embodiments, the first liquid substance and the
second liquid substance differ in at least one of: the amount and
the type of additives, wherein the additives are configured to at
least: evaporate and decompose during casting. In some embodiments,
the method may further include: measuring a chemical composition of
the liquid substance in the first container prior to pouring the
liquid substance into at least one of: the first mold portion and
the second mold portion; measuring the chemical composition of the
corresponding casted layer; and comparing the measurements. In some
embodiments, the method may further include: removing the
corresponding casted layer, if the measurements yield a difference
in chemical composition larger than a threshold value; and pouring
new liquid substance into the at least one of: the first mold
portion and the second mold portion.
[0016] In some embodiments, pouring the liquid substance into the
second mold portion may be in an amount sufficient to form the
second casted layer and to compensate for at least one of:
shrinkage of the first casted layer and thickness deviation in the
first casted layer.
[0017] Some aspects of the invention may be related to an additive
casting apparatus. An additive to casting apparatus according to
embodiments of the invention may include: a movable dispensing unit
in fluid connection with a first container containing mold
material, the dispensing unit including one or more liquid
introduction ports for depositing the mold material; a movable
pouring unit in fluid connection with at least one second container
for holding liquid substance, the pouring unit including one or
more liquid introduction ports for pouring at least one liquid
substance; a build table for holding the deposited mold material
and the poured liquid substance; and a controller configured to:
control the movable dispensing unit to deposit a first portion of a
mold, layer by layer; control the movable pouring unit to pour at
least one liquid substance into the first portion of the mold to
form a first casted layer; control the movable dispensing unit to
deposit a first portion of a mold, layer by layer, on top of the
first portion; and control the movable pouring unit to pour the at
least one liquid substance into the second portion of the mold to
form a second casted layer on top of at least a portion of the
first casted layer.
[0018] In some embodiments, the additive casting apparatus may
further include a joining unit configured to join the first and
second casted layers prior to a deposition of a third mold portion
and the pouring of a third casted layer. In some embodiments, the
joining unit may be at least one of: an induction heater, E-beam, a
resistance welder, an arc welder, a laser welder, a torch, a gluing
device, a cold fusion unit, a magnet for magnetic field flow, an
ultrasonic bonding unit and a heater for diffusion bonding. In some
embodiments, the at least one second container may be a crucible
and the liquid substance is one of: a molten metal and molten
glass. In some embodiments, the at least one second container may
be a tank and the liquid substance is at least one of: a polymer
resin or a molten polymer.
[0019] In some embodiments, the additive casting apparatus may
further include a pre-heating unit for heating each casted layer
prior to pouring an additional casted layer. In some embodiments,
the additive casting apparatus may further include one or more
surface treatment units for treating the surface of each casted
layer after the solidification and prior to pouring an additional
casted layer. In some embodiments, the one or more surface
treatment units includes at least one of: a machining device, a
grinding device and a polishing device.
[0020] In some embodiments, the additive casting apparatus may
further include an enclosure filled with protective atmosphere for
providing the protective atmosphere to the casted layers during
casting. In some embodiments, the enclosure may include a closed
housing accommodating: the movable dispensing unit, the movable
casting unit, the build table and a device configured to provide
the protective atmosphere. In some embodiments, the controller may
further be configured to: receive a three-dimensional (3D) part
model of one or more solid parts, the 3D part model is divided into
a plurality of casted layers; receive a 3D mold model of a mold,
the mold model is divided into a plurality of mold portions,
wherein the mold is designed to provide a desired shape to a liquid
substance; control the deposition of the mold portions based on the
mold model; and control the pouring of the casted layers based on
the part model.
[0021] In some embodiments, the movable despising unit is
configured to move in at least one axe. In some embodiments, the
movable pouring unit is configured to move in at least one axes. In
some embodiments, the additive casting apparatus may further
include the build table may be coupled to a movable platform. In
some embodiments, the movable pouring unit may be in fluid
connection with two containers for holding a first liquid
substances and a second liquid substances, and the controller may
be configured to: control the movable pouring unit to pour the
first liquid substance into the first portion of the mold to form a
first casted layer; and control the movable pouring unit to pour
the second liquid substance into the second portion of the mold to
form a second casted layer.
[0022] In some embodiments, the additive casting apparatus may
further include at least one chemical composition sensor configured
the measure at least of: the chemical composition of the liquid
substance in the container and the chemical composition of the
casted layers. In some embodiments, the at least one substance
composition sensor based on X-ray or laser.
[0023] Some additional aspects of the invention may be directed to
a casted metallic part that may include: at least a first casted
layer including a first type of alloy; at least a second casted
layer including a second type of alloy, joined to the at least
first casted layer. In some embodiments, the first and second
alloys are different alloys of the same metallic element. In some
embodiments, the thickness of each casted layer may be at least two
orders of magnitude smaller than the perimeter of each casted
layer. In some embodiments, the casted metallic may further include
a third casted layer joined to at least one second casted layer. In
some embodiments, the third casted layer may include a third type
of alloy of the same metallic element. In some embodiments, the at
least a first casted layer may differ from the at least a second
casted layer also in microstructure.
[0024] Some additional aspects of the invention may be directed to
a casted metallic part that may include: at least a first casted
layer having a first predetermined microstructure; and at least a
second casted layer having a second predetermined microstructure,
joined to the at least first casted layer. In some embodiments, the
first and second predetermined microstructures may differ at least
in the average grain size. In some embodiments, the thickness of
each casted layer may be at least two orders of magnitude smaller
than the perimeter of each casted layer. In some embodiments, the
casted metallic may further include a third casted layer joined to
at least one second casted layer. In some embodiments, the third
casted layer having a third predetermined microstructure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The subject matter regarded as the invention is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. The invention, however, both as to organization and
method of operation, together with objects, features, and
advantages thereof, may best be understood by reference to the
following detailed description when read with the accompanying
drawings in which:
[0026] FIG. 1 is an illustration of an additive casting apparatus
according to some embodiments of the invention;
[0027] FIG. 2 is a flowchart of a method of additive casting of
parts according to some embodiments of the invention;
[0028] FIGS. 3A and 3B are illustration of an in processes casted
part and mold according to some embodiments of the invention;
[0029] FIG. 4 is an illustration of an in processes casted part and
mold according to some embodiments of the invention; and
[0030] FIG. 5 is a detailed flowchart of a method of additive
casting of parts according to some embodiments of the
invention.
[0031] It will be appreciated that for simplicity and clarity of
illustration, elements shown in the figures have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements may be exaggerated relative to other elements for clarity.
Further, where considered appropriate, reference numerals may be
repeated among the figures to indicate corresponding or analogous
elements.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0032] In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of the invention. However, it will be understood by those skilled
in the art that the present invention may be practiced without
these specific details. In other instances, well-known methods,
procedures, and components have not been described in detail so as
not to obscure the present invention.
[0033] A casting apparatus and method according to embodiments of
the invention may include producing casted parts layer by layer, by
pouring liquid medium (e.g., a molten metal/alloy, molten glass, a
polymer resin, etc.) into mold portions being deposited themselves
layer by layer. The liquid medium may be any liquid material that
can solidify when poured into a mold, either spontaneously (e.g.,
solidification of molten martials due to cool down) or assisted by
an additional process (e.g., polymerization/crosslinking of
monomers or a polymer precursor using heat or ultraviolet (UV)
curing).
[0034] As used herein, a mold (also known in the art as shell) may
include any hollow cavity configured to provide a shape to the
liquid material being poured into the mold and allowed to solidify.
A mold according to embodiments of the invention may be
manufactured by printing/depositing layer by layer of mold material
to form different mold portions, as disclosed herein. As used
herein, a mold material may be any material suitable for being
deposited/printed from a deposition unit and provide a shape for a
specific liquid material being poured into the mold, after the mold
deposition. For example, when the liquid material is a molten
polymer or a polymer resin the mold material may also include a
polymer. In another example, when the liquid material is molten
metal (e.g., having a melting temperature of above 500.degree. C.)
or molten glass (e.g., having a melting temperature of above
1000.degree. C.) the mold material may include granular material
mixed with a binder and configured to hold molten substance at
elevated temperatures. The granular material may include: ceramic
powders (e.g., zirconia, alumina, magnesia, etc.), sand, clay,
metallic powders and any combination thereof. In some embodiments,
the mold material may further include activation additives. For
example, UV absorbing particles, crosslinking agents, heat
absorbing particles and the like.
[0035] In order to ensure the bonding between consecutive casted
layers a joining process may be conducted, using any joining method
known in the art. The joining method may be selected according to
the casted material, for example, two metallic layers may be
welded, two glass layers may be diffusion bonded and two polymeric
layers may be glued and/or crosslinked.
[0036] Reference is now made to FIG. 1 which is an illustration of
an additive casting apparatus according to some embodiments of the
invention. Such an additive casting apparatus may allow depositing
a plurality of mold portions substantially one on top of the other
that may form a single mold for casting liquid medium. Each mold
portion, as deposited, may be filled with liquid substance in order
to form a casted layer, prior to the deposition of an additional
mold portion. Thus, forming casted part(s) made from a plurality of
casted layers, being casted one on top of the other. Depositing,
each mold portion may include depositing one or more layers of mold
material.
[0037] An additive casting apparatus 100 may include a movable
dispensing unit 130 for depositing the mold material and a movable
pouring unit 120 for pouring at least one liquid substance.
Additive casting apparatus 100 may further include a build table
116 for holding the deposited mold material and the poured liquid
substance and a controller 153 configured to control the
controllable components of apparatus 100. In some embodiments,
additive casting apparatus 100 may further include a fixed frame
170 for holding at least some of the movable elements of additive
casting apparatus 100. Fixed frame 170 may be stationary.
[0038] In some embodiments, movable dispensing unit 130 may include
one or more liquid introduction ports 134 (e.g., nozzles, spouts
and the like) for pouring at least one liquid substance. In some
embodiments, movable dispensing unit 130 may be in fluid connection
and/or may include with at least one first container 132 containing
the mold material. In some embodiments, first container 132 may be
any tank/cartridge/magazine configured to hold the mold material.
In some embodiments, first container 132 may include a stirrer for
stirring the mold material in first container 132 prior to the
deposition.
[0039] In some embodiments, movable dispensing unit 130 may further
include a controllable valve configured to control the amount of
mold material being poured to form each mold layer in each mold
portion 112 from one or more liquid introduction ports 134. In some
embodiments, movable dispensing unit 130 may be configured to move
in at least one axe (e.g., the X axe as illustrated), for example,
when build table 116 may be coupled to a movable platform
configured to move in the at least two other axes (e.g., the Y and
Z axes). In some embodiments, movable dispensing unit 130 may be
configured to move in two or three axes. In some embodiments,
movable dispensing unit 130 may be mounted on an X-Y table
configured to move movable dispensing unit 130 to any point over
build table 116. In some embodiments, build table 116 and movable
dispensing unit 130 may be mounted on fixed frame 170 and may each
be allowed to relatively move in at least one axe with respect to
fixed frame 170. In some embodiments, movable dispensing unit 130
may be controlled (e.g., by controller 153) to deposit mold
portions 112 (e.g., first, second, third, fourth, etc. portions)
layer by layer.
[0040] In some embodiments, movable pouring unit 120 may include
one or more liquid introduction ports 124 for pouring at least one
liquid substance into a respective mold portion 112. Movable
pouring unit 120 may be in fluid connection with at least one
second container 122 for holding liquid substance. In some
embodiments, when the liquid substance is one of: a molten metal,
molten alloy and molten glass at least one second container 122 may
be a crucible. The crucible may be made from any material that
withstands elevated temperatures. The crucible may include an
opening for receiving the molten metal or molten glass (melted in a
melting crucible) and at least one exit for providing the melted
metal or glass to pouring unit 120. In some embodiments, the
crucible may be included in pouring unit 120.
[0041] In some embodiments, when the liquid substance is at least
one of: a polymer resin or a molten polymer, container 124 may be a
tank (e.g., a metallic tank) for holding the polymer resin or the
molten polymer. In some embodiments, the tank may include a stirrer
(not shown) for stirring the polymer resin. In some embodiments,
the tank may be included in pouring unit 120.
[0042] In some embodiments, movable pouring unit 120 may be in
fluid connection with two or more containers for holding a first
liquid substances and a second liquid substances. In some
embodiments, the first liquid substances may have a first chemical
composition and the second liquid substances may have a second
chemical composition, for example, the first liquid substance and
the second liquid substance may be selected from: two alloys of the
same metallic element, two types of glass and two types of
polymers.
[0043] In some embodiments, movable pouring unit 120 may further
include a controllable valve configured to control the amount of
liquid substance poured to form each casted layer 104 from one or
more liquid introduction ports 124. In some embodiments, movable
pouring unit 120 may be configured to move in at least one axe
parallel to the surface of build table 116 (e.g., the X axe
illustrated), for example, when build table 116 may be coupled to a
movable platform and configured to move in the at least two other
axes (e.g., the Y and Z axes). In some embodiments, movable pouring
unit 120 may be configured to move in two or three axes. In some
embodiments, movable pouring unit 120 may be mounted on an X-Y
table configured to move movable pouring unit 120 to any point over
build table 116. In some embodiments, build table 116 and movable
pouring unit 120 may be mounted on fixed frame 170 and may each be
allow to move in at least one axe with respect to fixed frame 170.
In some embodiments, movable pouring unit 120 may be controlled
(e.g., by controller 153) to pour each casted layer 104 into a
corresponding mold portion (e.g., first, second, third, fourth,
etc. portions).
[0044] As used herein, a casted layer is a layer made from a liquid
substance poured into a mold portion and solidify into a solid
casted layer in the mold portion. The casted layer may receive its
shape from the shape of the mold portion. The casted layer may
include, a casted polymer, casted metal/alloy, casted glass and the
like. A casted layer according to some embodiments of the invention
may be casted (e.g., poured) on top of a build table, a mold layer,
or a previously casted layer, as illustrated in FIG. 1 and
discussed with respect to the method of FIG. 2. In some
embodiments, the thickness of a typical casted layer may be at
least two orders of magnitude smaller than the perimeter of each
casted layer. A plurality of solidified casted layers 104 one on
top of the other may form a casted part 102.
[0045] In some embodiments, additive casting apparatus 100 may
further include at least one sensor 126 for measuring a chemical
composition of the liquid substance in first container 122 and/or
measuring the chemical composition of casted layer 104. At least
one sensor 126 may be coupled to movable pouring unit 120. In some
embodiments, a single sensor 126 may be assembled such that the
sensor may measure both the chemical composition in first container
122 and each casted layer 104. In some embodiments, one or more
sensors 126 may include an X-Ray based sensor or a laser-based
sensor. It should be appreciated that any other sensor capable of
measuring chemical composition of casted layer 104 may be used.
[0046] In some embodiments, additive casting apparatus 100 may
further include a joining unit 140 configured to join first and
second casted layers 104 prior to a deposition of a third mold
portion 112 and the pouring of a third casted layer 104. In some
embodiments, in order to form a solid part, consecutive casted
layers 104 must be joint together. In some embodiments, joining
unit 140 may be one of: an induction heater, a resistance welder,
an arc welder, a E-beam unit, an ultrasonic welder, a plasma
deposition unit, a laser welder, a torch, a gluing device, a cold
fusion unit, a magnet for magnetic field flow, an ultrasonic
bonding unit, a heater for diffusion bonding and the like. In some
embodiments, the type and number of joining devices 140 may be
selected according to the type of liquid substance being poured.
Joining unit 140 may be configured to move in at least one axe
(e.g., the X axe illustrated). For example, joining unit 140 may be
carried/coupled to robotic arm 151 capable of moving joining unit
140 to any required point over the surface a casted layer 104. In
another example, joining unit 140 may be coupled to a movable X-Y
table.
[0047] In some embodiments, additive casting apparatus 100 may
further include a pre-heating unit 145 for heating each casted
layer 104 prior to pouring an additional casted layer 104. In some
embodiments, when the casted liquid substance is molten metals,
alloys or glass, in order to reduce the temperature gradient
between the already solidified casted layer and the molten material
being poured to form the additional casted layer, the solidified
casted layer may be pre-heated, for example, by an indication
heater, or any other suitable heating element (e.g., filament).
Pre-heating unit 145 may be configured to move in at least one axe
(e.g., the X axe as illustrated). For example, Pre-heating unit 145
may be carried/coupled to robotic arm 151 capable of moving
pre-heating unit 145 to any required point over the surface of a
casted layer, such as layer 104. In another example, pre-heating
unit 145 may be coupled to a movable X-Y table. In some
embodiments, a movable pre-heating unit 145 may be may be
configured to move with respect to fixed farm 170.
[0048] In some embodiments, additive casting apparatus 100 may
further include one or more surface treatment units 128. The one or
more surface treatment units may include at least one of: a
machining device, a grinding device, a polishing device, a laser
ablation unit, and the like. For example, the machining device may
be included any cutting tool configured to at least one of: mill,
drill, broach, saw and the like. In some embodiments, the machining
device may be a computer numerical control (CNC) controlling a
plurality of cutting tools. In some embodiments, surface treatment
units 128 may include a grinding machine and/or a polishing machine
for receiving fine and ultrafine surface finishing.
[0049] In some embodiments, surface treatment units 128 may be
configured to treat the surface of each casted layer 104 including
both mold and poured material after the solidification and prior to
pouring an additional casted layer 104. In some embodiments,
surface treatment units 128 may be configured to treat the inner
and/or upper surface of each mold portion 112 prior to pouring the
corresponding casted layer 104, as illustrated and discussed with
respect to FIG. 4. As used herein, the upper surface is the surface
parallel to table 116 and inner surface is the surface of the inner
walls of the mold portion that may come in contact with the poured
liquid substance. In some embodiments, one or more surface
treatment units 128 may be configured to machine the upper surface
of both the mold portion and the corresponding casted layer, prior
to depositing of another casted layer, in order to level and even
the height (e.g., thickness) of both the mold portion and the
corresponding casted layer. The leveling may ensure an accurate
deposition and pouring of the following mold portion and casted
layer. One or more surface treatment units 128 may be configured to
move in at least one axe (e.g., the X axe as indicated by the
illustrated arrows).
[0050] In some embodiments, additive casting apparatus 100 may
further include a hardening unit (not illustrated) for assisting in
the hardening of a polymeric casted layer 104 after purring, for
example, by heating or UV curing.
[0051] In some embodiments, additive casting apparatus 100 may
further include an enclosure 160 filled with protective atmosphere
for providing the protective atmosphere to the casted layers during
casting. As used herein a protective atmosphere may include any
atmosphere that can protect the surface of the as casted layer 104
from undesirable chemical reactions, such as, oxidation and
carbonization. The protective atmosphere may include, an inert gas
such as argon, nitrogen and the like. The protective atmosphere may
include vacuum. In some embodiments, enclosure 160 may include a
closed housing accommodating at least: movable dispensing unit 130,
movable casting unit 120, build table 116 and a device 165
configured to provide the protective atmosphere, for example, a
vacuum pump, an argon source and the like.
[0052] In some embodiments, build table 116 may be or may include a
surface configured to hold the deposited mold material and the
poured liquid substance. Build table 116 may include any suitable
material, for example, metals such as steels, ceramics, such as,
alumina and the like. In some embodiments, build table 116 may
include more than one type of material (for example, a metal and a
ceramic) when the first mold portion 112 is to be deposited on a
ceramic surface and the first casted layer 104 is to be poured on a
metallic surface.
[0053] In some embodiments, build table 116 may be movable and may
be configured to move in at least one axes, for example, the three
axes indicated by the illustrated arrows. In some embodiments,
build table 116 may be configured to rotate around the vertical
axes. Build table 116 may be coupled to a movable platform, such as
an x-y table and the like.
[0054] In some embodiments, controller 153 may include any
processing unit, such as, processor 155 configured to execute
methods, codes and instructions according to embodiments of the
present invention. The methods, codes and instructions may be
stored in non-transitory storage 157, for example, instructions to
control various controllable components of casting apparatus 100
(e.g., movable dispensing unit 130, movable pouring unit 120, build
table 116, joining unit 140, pre-treatment unit 145 and the like).
Storage 157 may further include any data related to the operation
of casting device 100, for example, 3D models of parts and/or
molds. In some embodiments, controller 153 may be configured to:
control movable dispensing unit 130 to deposit a first portion of a
mold, layer by layer; control movable pouring unit 120 to pour at
least one liquid substance into the first portion of the mold to
form a first casted layer; control movable dispensing unit 130 to
deposit a first portion of a mold, layer by layer, on top of the
first portion; and control movable pouring unit 120 to pour the at
least one liquid substance into the second portion of the mold to
form a second casted layer on top of at least a portion of the
first casted layer. In some embodiments, controller 153 may control
movable dispensing unit 130 and movable pouring unit 120 to
deposited and pour a plurality of mold portions and the
corresponding casted layers, as discussed with respect to the
methods of FIGS. 2 and 5.
[0055] Reference is now made to FIG. 2 which is a flowchart of a
method of additive casting of parts according to some embodiments
of the invention. The method of FIG. 2 may be performed by additive
casting apparatus 100 under the control of controller 153. In some
embodiments, instructions to perform at least some of the steps of
the method of FIG. 2 may be stored in storage 157. In some
embodiments, a 3D model of one or more parts to be casted may be
received, in step 220. The 3D part model may be received by
controller 153, via I/O unit 159, for example, from any computer
aided design (CAD) software. Controller 153 may then divide the 3D
part model into a plurality of casted layers, for example, layers
104, 104a, 104b in FIG. 1 layer 204 in FIGS. 3A and 3B and 304 in
FIG. 4.
[0056] In some embodiments, a 3D model of the mold may be received,
in step 222. The 3D mold model may be received by controller 153,
via I/O unit 159, for example, from any computer added design (CAD)
software. In some embodiments, the 3D may be generated, in step
222, based for example, on the 3D part model. Controller 153 may
use any software module to generate a 3D mold model designed to
provide a desired shape to a liquid substance, as to form the final
casted part(s). In some embodiments, the 3D mold model may be
divided into a plurality of mold portions (e.g., shells), for
example, mold portions 108 and 112 illustrated in FIG. 1, portions
212, 213 and 215 illustrated in FIGS. 3A and 3B and portions 312
and 313 illustrated in FIG. 4. In some embodiments, each mold
portion may further be divided into one or more mold layers, such
that each mold portion may include one or more (e.g., two or more)
deposited mold layers.
[0057] In some embodiments, a first portion of a mold may be
deposited on a build table, layer by layer, in step 224. For
example, first portion 212 illustrated in FIGS. 3A and 3B or first
portion 312 illustrated in FIG. 4 may be deposited by movable
dispensing unit 130. Controller 153 may control movable dispensing
unit 130 to deposit the mold material according to the division of
the mold model. In some embodiments, controller 153 may control
movable dispensing unit 130 to deposit the mold material in
specific locations on build table 116 by controlling one or more
liquid introduction ports 134 to drop mold material when movable
dispensing unit 130 reaches each of the specific locations.
Controller 153 may control at least one of movable dispensing unit
130 and build table 116 to move with respect to one another as to
position movable dispensing unit 130 at the specific location. At
the end of the deposition, the mold portion may form a shape having
closed walls (e.g., a ring, an open box, etc.) configured to
accommodate a liquid substance.
[0058] In some embodiments, the method may include depositing an
initial mold layer (e.g., portions 108 illustrated in FIG. 1, 211
illustrated in FIGS. 3A and 3B and 311 illustrated in FIG. 3) prior
to the deposition of the first mold portion as to have a complete
coverage of the build table at the bottom of the first mold
portion.
[0059] In some embodiments, liquid substance may be poured into the
first portion of the mold to form a first casted layer, in step
226. For example, molten metal, molten glass, polymer resin etc.
may be poured from movable pouring unit 120 into a volume formed by
the walls of mold portion 212 to form casted layer 204, as
illustrated in FIGS. 3A and 3B. In some embodiments, movable
pouring unit 120 may continuously pour the liquid substance while
moving along the surface of build table 116. In some embodiments,
the amount of liquid substance being poured may be calculated, by
controller 153, according to the volume formed by the walls of mold
portion 212 and the expected shrinkage of the liquid substance
during the solidification. Controller 153 may control at least one
of movable pouring unit 120 and build table 116 to move with
respect to one another. In some embodiments, at least a portion of
the first casted layer may solidify, is step 228. For example,
molten material may be at least partially solidified due to
temperature dropping starting, for example, from the mold portions'
walls and inwards. In yet another example, polymer resin (e.g., a
precursor or a mixture of monomers) may polymerized, cured or
crystallized, either spontaneously or with the aid to external
energy source, such as UV lamp.
[0060] In some embodiments, a second portion of the mold may be
deposited, layer by layer, on top of the first portion, in step
230. For example, second mold portion 213 may be deposited on top
of first portion 212, according to the divided 3D mold model, as
illustrated in FIGS. 3A and 3B. The deposition of second mold
portion 213 may be substantially the same as the deposition of
first mold portion 212 discussed in step 224. In some embodiments,
a third mold portion 215 may be deposited on top of second mold
portion 213, as illustrated in FIG. 215.
[0061] In some embodiments, the mold material may be deposited,
layer by layer, in order to form support structures in the mold.
Such a support structure may include one or more elements for
overhanging casted layers. For example, at least one mold portions
may include one or more protrusions that may form support for
casted layers poured above the protrusions.
[0062] In some embodiments, the inner walls of each mold portion
may be undergo surface treatment prior to the pouring of an
additional casted layer, in step 232. In some embodiments, the
surface treatment may include at least one of: machining, grinding,
polishing and the like, for example, by surface treatment unit 128.
For example, a 90.degree. mill 206, illustrated in FIGS. 3A and 3B
may mill the walls of second mold portion 213 (and third mold
portion 215) as to attain a more precise and smooth edge. In yet
another example, a slop may be provided to the walls of mold
portion 313, illustrated in FIG. 4, by an angled end mill 306. In
some embodiments, the excess material machined (e.g., milled) may
be removed from the corresponding mold portion, as not to be mixed
with the liquid substance to be poured into the mold portion.
[0063] In some embodiments, liquid substance may be poured into the
second portion of the mold to form a second casted layer, on top of
at least a portion of the first casted layer, in step 234. The
pouring of the second casted layer may be substantially the same as
the pouring of the first casted layer. In some embodiments, the
second casted layer may be let to at least partially solidify, in
step 236. In some embodiments, at least some of steps 224-236 may
be repeated until the entire 3D part (e.g., part 102 illustrated in
FIG. 1) is additively casted by pouring a plurality of casted
layers. In some embodiments, pouring the liquid substance into the
second mold portion may be in an amount sufficient to form the
second casted layer and to compensate for at least one of:
shrinkage of the first casted layer and thickness deviation in the
first casted layer. For example, controller 153 may control pouring
unit 120 to pour more liquid substance than the amount required to
form the second casted layer, according to the received 3D model.
The added liquid substance may be determined as to compensate for
deficiencies formed in the first casted layer.
[0064] In some embodiments, the first and second casted layers may
be joined prior to the pouring of a third casted layer, in step
238. In some embodiments, when casting different casted layers, a
thin film may be formed on the free upper surface of each casted
layer. When pouring the following layer, the thin film may form a
boundary between two adjacent casted layers and may reduce the
bonding strength between the layers. Accordingly, in order to
increase the bonding strength an additional joining/bonding
operation may be conducted. For example, if the liquid substance is
molten metals/alloys the joining may include melting at least a
portion of the interface between the first and second casted
layers. The melting may be conducted by, for example,
heating/treating at least a portion of an upper surface of the
second casted layer, such that a temperature higher than the
melting point of the casted substance may be formed in the
interface between the first and second casted layers. The
heating/treating may be with one of: an induction heater, a
resistance welder, a laser, a welding arc, a torch, cold fusion,
magnetic field flow and the like. In another example, if the liquid
substance is molten glass, molten polymer or a polymer resin the
joining may include at least one of: gluing, ultrasonic bonding,
diffusion bonding, heat curing, UV curing and the like.
[0065] In some embodiments, each casted layer may be pre-heated
prior to the pouring of an additional casted layer, in step 240. In
some embodiments, the pre-heating is conducted in order to minimize
the thermal shocks that may cause macro and micro defects, such as
cracks, in the casted layers during the pouring of the additional
casted layer. In some embodiments, the previously casted layer may
be preheated, for example, to 600-700.degree. C. prior to pouring
molten metal or molten glass at 1000-1300.degree. C., thus reducing
thermal shock.
[0066] In some embodiments, a surface treatment may be provided to
each casted layer after the solidification and prior to the pouring
of an additional casted layer, in step 242. The surface treatment
may include removing an upper film (e.g., a thin oxidized layer)
from the casted layer and may also include leveling the mold
portion. In such case the removing of the upper film may cause
leveling or evening the first casted layer and the first mold
portion to be in the same level prior to the deposition of the
second mold portion. The leveling may allow more accurate
deposition of the second mold portion. In some embodiments, the
surface treatment may include at least one of: machining, grinding,
polishing and laser ablation.
[0067] In some embodiments, pouring the third and fourth casted
layers may cause a reheating to some extant an already fully
solidified lower casted layer. The reheating may cause an, in situ,
annealing process in the first casted layer result in at least
partial stress relief of the first casted layer.
[0068] In some embodiments, the first casted layer (e.g., layer
104a) may be casted by pouring a first liquid substance having a
first chemical composition; and the second casted layer (e.g.,
layer 104b) may be casted by pouring a second liquid substance
having a second chemical composition. In some embodiments, the
first liquid substance and the second liquid substance may be
selected from: two alloys of the same metallic element, two types
of glass (e.g., colored by two different pigments) and two types of
polymers, as to ensure the bonding/joining of the first and second
casted layers to each other. For example, the first casted layer
may include a first type of grey cast iron and the second casted
layer may include ductile iron, when cast part 102 may require
grater hardness at one part while having ductility and shock
absorbing ability in another part.
[0069] In some embodiments, in addition to controlling the chemical
composition also the microstructure of the first and second casted
layers (and any other layer in part 102) may be controlled to be
different from each other. For example, by selecting different
pre-heating temperature to be provided to the previously poured
casted layer, the microstructure may be altered. The lower the
selected pre-heating temperature is the finer the microstructure of
the poured layer will be. In some embodiments, additives added to
the first and second liquid substances may also alter the
microstructure. Therefore, the first liquid substance and the
second liquid substance may differ in at least one of: the amount
and the type of additives that are configured to at least:
evaporate and decompose during casting.
[0070] In some embodiments, the method of FIG. 2 may further
include measuring a chemical composition of the liquid substance in
the first container prior to pouring the liquid substance into at
least one of: the first mold portion and the second mold portion;
and measuring the chemical composition of the corresponding casted
layer. For example, one or more sensors 126 may measure the
chemical composition of the liquid substance in first container 122
and then measure the chemical composition in the last casted layer.
In some embodiments, the sensor may send the measurements to
controller 153 and the controller may compare the measurements. In
some embodiments, if the measurements yield a difference in
chemical composition larger than a threshold value (e.g., due to
oxidation of the casted layer) the measured casted layer may be
removed, and a new liquid substance may be poured into the at least
one of: the first mold portion and the second mold portion. For
example, controller 153 may control surface treatment unit 128 to
remove (e.g., by milling) an entire casted layer and control
movable pouring unit 120 to pour a new casted layer to replace the
removed one.
[0071] In some embodiments, the method of FIG. 2 may further
include removing all the mold portions at the ending of the
solidification of the last casted layer. The removing of the mold
portions may be conducted according to any known method, for
example, by mechanical means or chemical means.
[0072] Referring back to FIG. 1 and cast part 102. In some
embodiments, cast part 102 may be a metallic part including: at
least a first casted layer 104a and at least one second casted
layer 104b. In some embodiments, at least a first casted layer 104a
may include a first type of alloy and at least a second casted
layer 104b may include a second type of alloy. In some embodiments,
the first and second alloys may be different alloys of the same
metallic element. For example, first casted layer 104a may include
aluminum A355 and second casted layer 104a may include aluminum
A356. In yet another example, first casted layer 104a may include
grey cast iron and second casted layer 104a may include ductile
iron. In some embodiments, cast metallic part 102 may include a
third casted layer 104 having a third type of alloy of the same
metallic element.
[0073] In some embodiments, all casted layers 104 may be casted
from the same alloy however, at least a first casted layer 104a may
include a first predetermined microstructure and at least a second
casted layer 104b may include a second predetermined
microstructure. There are several methods known in the art for
altering the microstructure of various alloys, during the
solidification processes. The methods are based on controlling the
nucleation process, in which small grain nuclei are formed in the
melted metal and then grow into the final grain. There are two main
approaches: 1) controlling the over-cooling thus controlling the
energetic deriving force for creating the nuclei and 2) adding
nucleation centers (e.g., powders that includes compounds that may
use as nucleation centers) to the melt prior to pouring the melt
into the mold.
[0074] In some embodiments, the cooling rate of the casted layer
can be controlled by providing different pre-heating temperature to
the previously casted layer. For example, cast part 102 may be
casted from aluminum A356 however first casted layer 104a may have
larger grain size (e.g., crystal size) than second casted layer
104b. The different grain size may be archived by providing
different pre-heating treatment to each layer, as disclosed herein
above. In another example, cast part 102 may be casted from grey
cast iron however first casted layer 104a may have larger graphite
flasks than second casted layer 104b. The larger the temperature
difference between the molten metal being poured and the substrate
(e.g., the former casted layer) the greater is the driving force
for creating nuclei, thus the larger is the number of nuclei formed
and the finer the final microstructure may be.
[0075] In some embodiments, the microstructure may be controlled by
the amount of nucleation centers provided to the melt in each
layer. For example, ZrO.sub.2 particles may be added at two
different amounts (e.g., 0.5 wt. % to layer 104a and 1.7 wt. % to
layer 104b) to SP steel in order to refine the microstructure. The
larger the amount the of ZrO.sub.2 particles the larger the amount
of nucleation sites and the finer is the microstructure. In some
embodiments, at least one first casted layer 104a and at least one
second casted layer 104b may differ both in the type of alloy and
the microstructure.
[0076] In some embodiments, at least a first casted layer 104a and
at least a second casted layer 104b may be joined together. For
example, the at least a first casted layer 104a and at least a
second casted layer 104b may be welded to each other, diffusion
bonded to each other and the like as to form a solid metallic part.
In some embodiments, the microstructure of the joined areas may be
distinguished from the rest of the cast part, a phenomenon known in
the art as heat affected zone (HAZ). In some embodiments, if the
casted layers has a thickness smaller than the HAZ, than all casted
layers may have a HAZ microstructure and the joined areas may not
be distinguishable.
[0077] In some embodiments, the thickness of each casted layer 104,
104a, 104b may be at least two orders of magnitude smaller than the
perimeter of each casted layer.
[0078] Reference is now made to FIG. 5 which is a detailed
flowchart of a method of additive casting of parts according to
some embodiments of the invention. In some embodiments, the method
steps may be performed by controller 153 directing an additive
casting apparatus 403. In some embodiments, additive casting
apparatus (e.g., a 3-D printer) 403 may include at least some of
the components of additive casting apparatus 100, illustrated in
FIG. 1.
[0079] In some embodiments, the process may start at step 400, when
a 3D mold model 405 and a 3D part model 407 may be stored in
storage 157 of controller 153. In some embodiments, 3D mold model
405 and a 3D part model 407 may be divided to a plurality of mold
portions and a corresponding plurality of casted layers to be
included in a layer build map set 409. For example, for
illustrative purposes as including casted layer and the
corresponding mold portions build maps 409-1, 409-2, . . . , 409-N,
for a 3D printed part that is poured using N layers. For purposes
of illustration and discussion, a typical casted layer and mold
portion build map 409-C may include casted layer and mold portion
data 411, that may contain a layer/portion thickness parameter 413,
a number of mold layers 415 within each mold portion, and edge
profile data 417. In the discussions of layer fabrication, build
map 409-C may be taken as the "current" layer build map during the
3D additive casting process.
[0080] In some embodiments, edge profile data 417 may specify, for
example, the shape and angle of the mold walls such as illustrated
in FIG. 3A and FIG. 4. In some embodiments, edge profile data 417
may also contain information regarding the sequencing of surface
finishing operations, such as illustrated and discussed in FIG. 3B,
such that two mold portions (e.g., mold portion 213 and mold
portion 215) may be finished simultaneously by end mill 206 (as
opposed to finishing portion 213 before depositing portions
215).
[0081] In some embodiments, an additional data stored in readable
memory accessible to controller 153 may include material parameters
421, for example, the mold material parameters 423 and the liquid
substance parameters 425. Material parameters may include
specifications and characteristics of the materials, including at
least one of: physical properties, chemical compositions and other
data necessary to carry out method steps. In a non-limiting
example, for a mold material that may be heated to be harden, mold
material parameters 423 may include the temperature and time for
hardening. In some embodiments, if the temperature and time derived
from the thickness of the mold walls, then mold material parameters
423 may include a formula or lookup table from which the parameters
could be derived from the thickness.
[0082] Additive casting of a 3D part (e.g., part 102) may begin at
step 431, and may be followed by the deposition of mold layer to
form the first mold portion (e.g., portion 112), at deposition loop
433. The deposition of a new mold portion may be initialized in an
initialization step 435. Initialization steps may include, for
example, a selection of the appropriate mold portion form build map
set 409. For example, the first mold portion may be deposited
according to layer build map 409-1, the second mold portion may be
deposited according to build map 409-2, and so forth, up to the
casting of the final casted layer/mold portion, according to build
map 409-N (for N layers). In a non-limiting example, build table
116 may be initialized in position for the mold portion to be
properly deposited and/or the liquid substance be properly
poured.
[0083] In some embodiments, the mold portion may be deposited, in
step 437. For example, mold material may be laid layer by layer
(e.g., from movable dispensing unit 130) according to mold 3D model
405 data in current build map 409-C (e.g., the current layer in
build map in effect)), such that the mold material delineates a
region where liquid substance is to be subsequently poured into
(e.g., from movable pouring unit 120). In some embodiments, the
mold material may be deposited by movable dispensing unit 130,
positioned and moved by robotic arm 151 as directed by controller
153.
[0084] In some embodiments, at step 439, it may be determined
whether a further mold layers should be laid on top of the former
mold layer already laid in deposition step 437. The deposition of
an additional mold layer at this point may be determined according
to the 3D model of the mold portion included in build map 409-C. If
a further mold layer is to be deposited, then deposition step 437
may be repeated, as many times as required by build map 409-C in
order to complete the corresponding mold portion.
[0085] In some embodiments, when no further mold layer is to be
deposited after mold deposition step 437, the method may include a
mold hardening step 441, to harden all the layers of the mold
portion that have been deposited. In some embodiments, the
hardening step may be selected according to the mold material
parameters. Some mold materials may not require hardening at all.
Hardening may be accomplished by any method known in the art, such
as UV curing, heating and the like. In some embodiments, the mold
material may spontaneously harden over a period of time. Thus,
according to this embodiment mold hardening step 441 may include
waiting an appropriate amount of time after the deposition of the
mold material. Moreover, according to this embodiment, the waiting
time may be included in mold material parameters 423, such as by a
value, a table, and/or a formula.
[0086] In some embodiments, in step 443, it is determined whether a
further mold layers may be laid on top of the mold material already
deposited in deposition step 437 and optionally hardened in mold
hardening step 441. The deposition of further mold layer/portions
at this point may be determined based on build map 409-C. If a
further mold layer is to be deposited, then deposition step 437 may
be repeated to form the mold portion.
[0087] In some embodiments, if no further mold layers are to be
deposited, then a mold surface finishing step 445 may be performed.
In some embodiments, the surface of the walls of the hardened mold
may be machined, grinded and/or polished. Mold surface finishing
may include surface treatment of either the top surface of the
walls of mold portion, or the inner surface of the mold portion,
which delineates the part surface to be subsequently formed. Mold
surface finishing may be accomplished by one or more of the means
previously described herein.
[0088] In some embodiments, in pouring step 451, liquid substance
may be poured according to the 3D part model 407 data of current
layer build map 409-C. In some embodiments, the amount of liquid
substance to be poured may be determined such that, the liquid
substance fills the region delineated by the mold portion. In some
embodiments, liquid substance may be poured by movable pouring unit
120, for example, positioned and moved by robotic arm 151 as
directed by controller 153.
[0089] In some embodiments, the amount of liquid substance poured
into the corresponding mold portion may be determined based on
liquid substance parameters 425, for example, the amount of
expected shrinkage of the liquid substance during the
solidification. The amount may include an additional computation
according to volumetric factors such as temperature changes, phase
changes, and the like, to allow for expansion, shrinkage, density
changes, and so forth.
[0090] In some embodiments, in solidification step 453, the poured
liquid build table may at least partially be solidified into casted
layer.
[0091] In some embodiments, if there is a previously-consolidated
casted layer beneath the present casted layer, the solidification
process may bond the present casted layer to the previously-poured
casted layer, so that both casted layers may be part of the same
solid part. In some embodiments, an additional joining process may
be conducted in order to join the two adjacent casted layers, as
disclosed herein above.
[0092] In some embodiments, in casted layer surface finishing step
455, the top surface of the casted layer may be treated to have a
smooth and level surface of a desired thickness in preparation for
the next casted layer, if any, such as by steps previously
discussed.
[0093] In some embodiments, casted layer pouring loop end 457 may
be reached, and at a decision may be taken in step 459 by, for
example, controller 153 to checks if there is a subsequent casted
layer to be fabricated. If there is a subsequent casted layer,
casted layer pouring loop 433-457 may be repeated, using the next
casted layer build map data from build map data set 409.
[0094] In some embodiments, if no subsequent casted layer is to be
poured, the 3D additive casting may be terminated at a point 461,
and all mold portions forming the mold may be removed in removal
step 463. In various embodiments of the present invention, the mold
removal may be done according to any known method, for example,
chemically, by use of a solution that removes the mold without
affecting the 3D casted part within the mold. In other embodiments,
the mold may be mechanically removed.
[0095] In some embodiments, a number of new layers that still need
to be poured/deposited may be determined in step 401, given the
number of new casted layers 401, a decision may be made in step
459, to repeat steps 433 through 457.
[0096] While certain features of the invention have been
illustrated and described herein, many modifications,
substitutions, changes, and equivalents will now occur to those of
ordinary skill in the art. It is, therefore, to be understood that
the appended claims are intended to cover all such modifications
and changes as fall within the true spirit of the invention.
* * * * *