U.S. patent application number 17/648705 was filed with the patent office on 2022-05-12 for additive manufacturing method and device for ceramic and composite thereof.
This patent application is currently assigned to Huazhong University of Science & Technology. The applicant listed for this patent is Huazhong University of Science & Technology. Invention is credited to Xiaoqi HU, Guilan WANG, Cheng YANG, Hai'ou ZHANG.
Application Number | 20220143868 17/648705 |
Document ID | / |
Family ID | 1000006093485 |
Filed Date | 2022-05-12 |
United States Patent
Application |
20220143868 |
Kind Code |
A1 |
ZHANG; Hai'ou ; et
al. |
May 12, 2022 |
ADDITIVE MANUFACTURING METHOD AND DEVICE FOR CERAMIC AND COMPOSITE
THEREOF
Abstract
Additive manufacturing (AM) methods and devices for
high-melting-point materials are disclosed. In an embodiment, an
additive manufacturing method includes the following steps. (S1)
Slicing a three-dimensional computer-aided design model of a
workpiece into multiple layers according to shape, thickness, and
size accuracy requirements, and obtaining data of the multiple
layers. (S2) Planning a forming path according to the data of the
multiple layers and generating computer numerical control (CNC)
codes for forming the multiple layers. (S3) Obtaining a formed part
by preheating a substrate, performing a layer-by-layer spraying
deposition by a cold spraying method, and heating a spray area to a
temperature until the spraying deposition of all sliced layers is
completed. (S4) Subjecting the formed part to a surface
modification treatment by a laser shock peening method.
Inventors: |
ZHANG; Hai'ou; (Wuhan,
CN) ; HU; Xiaoqi; (Wuhan, CN) ; WANG;
Guilan; (Wuhan, CN) ; YANG; Cheng; (Wuhan,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huazhong University of Science & Technology |
Wuhan |
|
CN |
|
|
Assignee: |
Huazhong University of Science
& Technology
Wuhan
CN
|
Family ID: |
1000006093485 |
Appl. No.: |
17/648705 |
Filed: |
January 24, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16909847 |
Jun 23, 2020 |
|
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17648705 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B28B 11/089 20130101;
B33Y 10/00 20141201; B28B 1/001 20130101; B33Y 30/00 20141201; B28B
11/0872 20130101; B22F 10/10 20210101; C22F 1/04 20130101 |
International
Class: |
B28B 11/08 20060101
B28B011/08; B33Y 10/00 20060101 B33Y010/00; B33Y 30/00 20060101
B33Y030/00; B22F 10/10 20060101 B22F010/10; B28B 1/00 20060101
B28B001/00; C22F 1/04 20060101 C22F001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2019 |
CN |
201910546152.4 |
Claims
1. A device, comprising: a data processing module, a spraying
deposition module, a heating module, and a laser shock peening
module, wherein: the data processing module is configured to: slice
the three-dimensional computer-aided design model of the workpiece
into multiple layers according to the shape, thickness, and size
accuracy requirements; obtain data of multiple sliced layers; plan
the forming path according to the data of the multiple slice
layers; and generate computer numerical control codes for forming
the slice layers; the spraying deposition module is configured to
perform a layer-by-layer spraying deposition according to the
computer numerical control codes of the slice layers obtained by
the data processing module; the heating module is configured to
preheat the substrate and heat the spray area to a temperature
until the spraying deposition of all slice layers is completed,
wherein the temperature is in a range of the melting point of the
sprayed powder minus 200.degree. C. to the melting point of the
sprayed powder; and the laser shock peening module is configured to
modify a surface of a formed part to generate the predetermined
residual compressive stress thereon.
2. The device according to claim 1, further comprising a computer
numerical control machine tool, wherein: the computer numerical
control machine tool comprises a workbench (10), a gantry machine
tool (1), and a first spindle (5) provided on the gantry machine
tool (1); the workbench (10) is provided below the gantry machine
tool (1); the gantry machine tool (1) is configured to integrate
the data processing module, the spraying deposition module, the
heating module, and the laser shock peening module; the spraying
deposition module comprises a high-speed cold spraying gun (7) and
a substrate (9); the high-speed cold spraying gun (7) is provided
at the bottom of the first spindle (5); the substrate (9) is
provided on the workbench (10); the heating module comprises a
first heating unit and a second heating unit; the first heating
unit is provided above the substrate (9); and the second heating
unit is provided at the bottom of the first spindle (5).
3. The device according to claim 2, further comprising a second
spindle (3), a temperature sensor (6), a milling/grinding device
(2), and a micro-rolling device (4), wherein: the second spindle
(3) is provided on the gantry machine tool (1); the
milling/grinding device (2) is provided at the bottom of the second
spindle (3); and the temperature sensor (6) and the micro-rolling
device (4) are provided at the bottom of the first spindle (5).
4. The device according to claim 2, wherein: the high-speed cold
spraying gun (7) utilizes a laser/cold spraying composite nozzle;
the composite nozzle comprises a composite nozzle outer wall (11)
and a composite nozzle inner wall provided inside the composite
nozzle outer wall (11); a beam splitter (14) is provided between
the composite nozzle outer wall (11) and the composite nozzle inner
wall; a powder inlet (15) is provided on the top of the composite
nozzle inner wall; a high-pressure gas inlet (16) is provided on a
side wall of the composite nozzle inner wall; and a nozzle (13) is
provided at the bottom of the composite nozzle inner wall.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of the pending
U.S. application Ser. No. 16/909,847, filed on Jun. 23, 2020, which
claims priority to Chinese application number 201910546152.4 filed
on Jun. 24, 2019, the disclosure of which are incorporated by
reference herein in their entireties.
FIELD OF THE DISCLOSURE
[0002] The disclosure relates generally to additive manufacturing
(AM) of materials with high melting points. More specifically, the
disclosure relates to AM methods and devices for ceramics and
ceramic composites.
BACKGROUND
[0003] Additive manufacturing (AM) processes of high-melting-point
materials mainly include laser deposition technology (LDT),
electron-beam freeform fabrication (EBF.sup.3) and plasma arc
deposition (PAD).
[0004] The LDT uses a high-power laser to melt the metal powder
sent to the substrate layer by layer and quickly solidify the
deposit to form a near-net-shape part. The method has high forming
precision and higher workpiece density than that of the selective
laser sintering (SLS) process. However, its forming efficiency and
energy/material utilization are low, the equipment investment and
operating cost are high, and it is not easy to achieve full
density. The EBF.sup.3 process uses a high-power electron beam to
melt the powder material. It applies an electromagnetic field
according to the computer model and controls the movement of the
electron beam to scan layer by layer until the entire part is
formed. This method has high forming precision and good forming
quality. However, the process conditions are strict, and the entire
forming process needs to be performed in a vacuum, which results in
limited forming dimensions and high equipment investment and
operating costs. In addition, because it uses the same
layer-by-layer powder spreading method as SLS, it is difficult to
form with functionally graded materials (FGM). The PAD uses a
highly compressed and well concentrated plasma beam to melt the
metal powder or filament that is synchronously supplied so that the
material is deposited on the substrate layer by layer to form a
metal part or mold. Compared with the previous two methods, this
method has high forming efficiency and material utilization, low
equipment, and operating costs, and is easy to achieve full
density. However, due to the larger diameter of the plasma plume,
the size and surface accuracies of this method are not as high as
these two methods. Therefore, like LDT, this method requires finish
machining after forming (Haiou Zhang, Jipeng Xu, Guilan Wang:
Fundamental Study on Plasma Deposition Manufacturing, Surface and
Coating Technology, v.171 (1-3) 2003, pp. 112-118; Haiou Zhang,
Hongjun Wu, Guilan Wang, Jing Chen: Study on Microstructure of
Superalloy Parts Directly Formed by Plasma Deposition, Journal of
Huazhong University of Science and Technology (Natural Sciences),
v33, n11, 2005, p54-56). However, the direct forming process will
increase the surface hardness of the difficult-to-machine parts due
to rapid solidification, resulting in difficult machining. Since
the complex-shaped parts need to be clamped multiple times, the
processing time is prolonged, sometimes even accounting for more
than 60% of the entire manufacturing cycle. This has become a
bottleneck for the low-cost, short-flow manufacturing of
high-performance difficult-to-machine parts. To solve this problem,
a moldless rapid manufacturing method of hybrid plasma deposition
and milling (HPDM) is proposed. This method uses a plasma beam as
the forming heat source to sequentially perform the alternative
deposition and computer numerical control (CNC) milling in the
layered or segmented deposition process to implement short-flow,
low-cost direct precision manufacturing (DPM) (Patent No.
ZL00131288.X: Method and Device for Directly and Rapidly
Manufacturing Molds and Parts; Haiou Zhang, Xinhong Xiong, Guilan
Wang: Direct Manufacturing of Double Helix Integral Impeller Made
of Superalloy by Hybrid Plasma Deposition & Milling, China
Mechanical Engineering, 2007, Vol18, No. 14: P1723-1725).
[0005] Among the three methods, LDT and PAD are supportless,
moldless deposition methods of forming homogeneous or functionally
graded composite material (FGCM) parts. Compared with supported
moldless deposition methods such as EBF.sup.3, SLS/SLM, and
laminated object manufacturing (LOM), stereolithography apparatus
(SLA) and fused deposition modeling (FDM) which use
low-melting-point materials like paper, resin, and plastic, the
supportless moldless deposition methods avoid disadvantages caused
on the materials and processes due to the need to add or remove
supporting materials. They reduce the manufacturing time and costs
and may be used to form FGM parts. However, due to the lack of
support, during the forming process of complex-shaped parts with
overhangs, the molten material may fall and flow under the action
of gravity, making it difficult to deposit. The HPDM process
reduces machining complexity through layered forming and milling.
However, for complex-shaped parts with large inclination angles on
the sides, especially those with lateral overhanging angles, the
flow and fall caused by gravity during the deposition process
cannot be avoided, making lateral growth difficult.
[0006] Some research institutions such as the University of
Michigan (UM), Southern Methodist University (SMU), and National
University of Singapore (NUS) use multi-direction slicing
technology and select the direction with the best support
conditions as the main direction of part forming, split
complex-shaped parts into several simple-shaped parts to form in
sequence or develop five-axis moldless forming equipment and
software to support the molten material as much as possible (P.
Singh, D. Dutta: Multi-Direction Slicing for Layered Manufacturing,
Journal of Computing and Information Science and Engineering, 2001,
2, pp: 129-142; Jianzhong Ruan, Todd E. Sparks, Ajay Panackal et
al.: Automated Slicing for a Multiaxis Metal Deposition System,
Journal of Manufacturing Science and Engineering, April 2007, Vol.
129. pp: 303-310; R. Dwivedi, R. Kovacevic: An Expert System for
Generation of Machine Inputs for Laser-Based Multi-Directional
Metal Deposition, International Journal of Machine Tools &
Manufacture, 46 (2006) pp.1811-1822).
[0007] The five-axis machining technology significantly improves
the growth support conditions and avoids the material falling. The
gas-shielded plasma arc/electric arc welding, vacuum electron beam
welding, electroslag welding and submerged arc welding improve the
efficiency and reduce costs. However, it is difficult for these
heat sources to form complex, fine, thin-walled parts, and their
forming precision and thin-walledness are not as good as the LDT
(Almeida PMS, Williams S: Innovative Process Model of Ti-6AI-4V
Additive Layer Manufacturing Using Cold Metal Transfer (CMT) [C],
Proceedings of the 21.sup.st Annual International Solid Freeform
Fabrication Symposium, Austin, Tex., USA, 2010: 25-26).
[0008] There are two main methods for attaching materials to the
surface to improve the surface performance of parts and molds,
namely cold spraying (CS) and thermal spraying (TS). TS is a
process of using the heat provided by the fuel gas, electric arc,
or plasma arc to melt the powder, wire, or filament, atomizing the
coating material into fine particles with a high-speed gas jet, and
spraying them onto the surface of the workpiece to form a coating.
Different coating materials are chosen as needed to implement one
or more properties of wear resistance, corrosion resistance,
oxidation resistance and heat resistance. TS may be used to spray
almost all solid engineering materials, such as cemented carbide,
ceramics, metals, and graphite. However, TS also has many defects.
First, the spraying process needs to melt the metal particles,
resulting in a high spraying temperature, causing thermal stress
inside the substrate and thermal deformation on the surface of the
substrate. Second, because manual operation is impossible except
for flame spraying (FS), the operation is dangerous. In addition,
the traditional TS process has poor spraying effect since the
spraying area and thickness are difficult to control, and the
device is not portable. CS is a metal and ceramic spraying process.
Unlike traditional TS, CS does not need to melt the metal particles
before spraying. Instead, it uses compressed air to accelerate the
metal particles to a critical speed (supersonic speed). After the
metal particles directly impact the surface of the substrate, they
undergo physical deformation, and thus physically combine with the
substrate. The metal particles collide with the surface of the
substrate and thus are firmly attached. The metal particles are not
melted in the whole process, so the surface of the coating
substrate avoids excessively high temperature to cause the metal to
oxidize and the phase to change. The above two surface-enhanced
spraying processes improve the surface performance of parts and
molds from different perspectives. However, they are difficult to
obtain coatings with large thicknesses and densities and are thus
difficult to meet the requirements of high-end aerospace equipment
such as aero-engines for the surface modification of parts.
[0009] In addition, the aerospace, energy, and power industries
have high requirements on the microstructure, performance, and
stability of parts. Featuring rapid heating, rapid solidification,
and free growth, the existing moldless AM methods are difficult to
avoid cracks and porosity during the AM process, resulting in that
the microstructure, performance, and stability of parts is not
satisfactory. The above problems have become the key technical
problems that restrict the further development of the direct energy
deposition (DED) technology and the implementation of industrial
application. Therefore, it is necessary to develop a new method to
effectively improve the manufacturing accuracy, formability, and
the microstructure and performance of parts.
SUMMARY
[0010] The following presents a simplified summary of the invention
to provide a basic understanding of some aspects of the invention.
This summary is not an extensive overview of the invention. It is
not intended to identify critical elements or to delineate the
scope of the invention. Its sole purpose is to present some
concepts of the invention in a simplified form as a prelude to the
more detailed description that is presented elsewhere.
[0011] In some embodiments, the disclosure provides an additive
manufacturing method including the following steps.
[0012] (S1) Slicing a three-dimensional computer-aided design model
of a workpiece into multiple layers according to shape, thickness,
and size accuracy requirements, and obtaining data of the multiple
layers. The obtained data includes thickness, shape, and size
accuracies of each sliced layer and a melting point of a
material.
[0013] (S2) Planning a forming path according to the data of the
multiple layers and generating computer numerical control codes for
forming the multiple layers.
[0014] (S3) Obtaining a formed part by preheating a substrate,
performing a layer-by-layer spraying deposition by a cold spraying
method according to the computer numerical control codes in step
(S2), and heating a spray area to a temperature until the spraying
deposition of all sliced layers is completed. The temperature is in
a range of a melting point of a sprayed powder minus 200.degree. C.
to the melting point of the sprayed powder.
[0015] (S4) Subjecting the formed part to a surface modification
treatment by a laser shock peening method so that the formed part
has a predetermined residual compressive stress.
[0016] Optionally, heating the spray area of step (S3) further
includes heating the substrate to perform spraying deposition in
forming a first slice layer until the spraying deposition of the
first slice layer is completed and heating a surface of an
uppermost formed slice layer to perform spraying deposition on the
surface of a formed slice layer until the spraying deposition of
all slice layers is completed.
[0017] Optionally, the substrate is heated by at least one item
selected from the group consisting of a heating furnace provided
outside a spray chamber, a plasma device provided inside the spray
chamber, and an electromagnetic heating coil.
[0018] Optionally, surfaces of formed slice layers are heated by
laser heating or plasma heating.
[0019] Optionally, in step (S3), the substrate is preheated to
600.degree. C. to 1,100.degree. C., and the spray area is heated to
800.degree. C. to 1,400.degree. C.
[0020] Optionally, in the spraying deposition of step (S3), if the
formed thickness, shape, and size accuracies are not satisfactory,
a formed slice layer is subjected to a finishing step. The
finishing step may be performing a plastic forming on the formed
slice layer by roller compaction until the thickness, shape, and
size accuracy requirements are met, or performing a subtractive
processing on the formed slice layer by milling, grinding, and
polishing until the thickness, shape, and size accuracy
requirements are met.
[0021] In other embodiments, the disclosure provides a device for
implementing an additive manufacturing method. The device includes
a data processing module, a spraying deposition module, a heating
module, and a laser shock peening module.
[0022] The data processing module is configured to slice a
three-dimensional computer-aided design model of a workpiece into
multiple layers according to shape, thickness, and size accuracy
requirements, obtain data of multiple slice layers, plan a forming
path according to the data of the multiple slice layers, and
generate computer numerical control codes for forming the slice
layers.
[0023] The spraying deposition module is configured to perform a
layer-by-layer spraying deposition according to the computer
numerical control codes of the slice layers obtained by the data
processing module.
[0024] The heating module is configured to preheat a substrate and
heat a spray area to a temperature until the spraying deposition of
all slice layers is completed. The temperature is in a range of the
melting point of a sprayed powder minus 200.degree. C. to the
melting point of the sprayed powder.
[0025] The laser shock peening module is configured to modify a
surface of a formed part to generate a predetermined residual
compressive stress thereon.
[0026] Optionally, the device further includes a computer numerical
control machine tool. The computer numerical control machine tool
includes a workbench (10), a gantry machine tool (1), and a first
spindle (5) provided on the gantry machine tool (1). The workbench
(10) is provided below the gantry machine tool (1). The gantry
machine tool (1) is configured to integrate the data processing
module, the spraying deposition module, the heating module, and the
laser shock peening module. The spraying deposition module includes
a high-speed cold spraying gun (7) and a substrate (9). The
high-speed cold spraying gun (7) is provided at the bottom of the
first spindle (5). The substrate (9) is provided on the workbench
(10). The heating module includes a first heating unit and a second
heating unit. The first heating unit is provided above the
substrate (9). The second heating unit is provided at the bottom of
the first spindle (5).
[0027] Optionally, the device further includes a second spindle
(3), a temperature sensor (6), a milling/grinding device (2), and a
micro-rolling device (4). The second spindle (3) is provided on the
gantry machine tool (1). The milling/grinding device (2) is
provided at the bottom of the second spindle (3). The temperature
sensor (6) and the micro-rolling device (4) are provided at the
bottom of the first spindle (5).
[0028] Optionally, the high-speed cold spraying gun (7) utilizes a
laser/cold spraying composite nozzle. The composite nozzle includes
a composite nozzle outer wall (11) and a composite nozzle inner
wall provided inside the composite nozzle outer wall (11). A beam
splitter (14) is provided between the composite nozzle outer wall
(11) and the composite nozzle inner wall. A powder inlet (15) is
provided on the top of the composite nozzle inner wall. A
high-pressure gas inlet (16) is provided on a side wall of the
composite nozzle inner wall. A nozzle (13) is provided at the
bottom of the composite nozzle inner wall.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Illustrative embodiments of the present disclosure are
described in detail below with reference to the figures.
[0030] FIG. 1 is a flowchart of an additive manufacturing (AM)
method according to an embodiment of the disclosure.
[0031] FIG. 2 is a structural diagram of a device for implementing
an AM method according to an embodiment of the disclosure.
[0032] FIG. 3 is a structural diagram of a laser/cold spraying (CS)
composite nozzle of a high-speed CS gun according to an embodiment
of the disclosure.
DETAILED DESCRIPTION
[0033] The following describes some non-limiting embodiments of the
invention with reference to the accompanying drawings. The
described embodiments are merely a part rather than all of the
embodiments of the invention. All other embodiments obtained by a
person of ordinary skill in the art based on the embodiments of the
disclosure shall fall within the scope of the disclosure.
[0034] As shown in FIGS. 1-3, 1 represents gantry machine tool, 2
represents milling/grinding device, 3 represents second spindle, 4
represents micro-rolling device, 5 represents first spindle, 6
represents temperature sensor, 7 represents high-speed CS gun, 8
represents second heating unit, 9 represents substrate, 10
represents workbench, 11 represents composite nozzle outer wall, 12
represents ring-shaped laser beam, 13 represents nozzle, 14
represents beam splitter, 15 represents powder inlet, 16 represents
high-pressure gas inlet, 17 represents incident laser beam, and 18
represents partially formed part.
[0035] FIG. 1 is a flowchart of an additive manufacturing (AM)
method according to an embodiment of the disclosure. As shown in
FIG. 1, the disclosure may provide an additive manufacturing (AM)
method for a ceramic and a composite thereof including the
following steps.
[0036] Step 101. A three-dimensional (3D) computer-aided design
(CAD) model of a workpiece to be formed is sliced into layers
according to the shape, thickness, and size accuracy requirements
thereof, and data of multiple slice layers are obtained, which may
include thickness, shape, and size accuracies of each slice
layer.
[0037] Step 102. A forming path is planned according to the data of
the slice layers, and computer numerical control (CNC) codes for
forming the slice layers are generated.
[0038] Step 103. A coating substrate 9 is preheated to a specified
temperature in the range of 600.degree. C. to 1,100.degree. C.
Then, according to the CNC codes of the layers obtained in step
102, a CNC high-speed CS gun 7 may be configured to deposit a
powder material on the substrate layer by layer by cold spraying
based on a scanning track. At the same time, a spray area may be
heated by a heat source such as a laser beam or an electron beam,
and the spray area and the powder material to be sprayed maintain
an appropriate spray temperature. To print a first slice layer, the
substrate 9 may be heated synchronously by a heat source such as a
laser beam or an electron beam so that the temperature of the
substrate 9 matches the temperature of the molten material to be
printed; that is, the heating temperature may be in the range of a
melting point of the sprayed powder minus 200.degree. C. to the
melting point of the sprayed powder. The powder sprayed onto the
substrate 9 may effectively avoid the thermally induced adverse
effects caused by the TF processes such as thermal spraying (TS)
and fused deposition by a laser beam, an electron beam, and an
electric arc. To print a second slice layer after the printing of
the first slice layer may be completed, a heat source such as a
laser beam or an electron beam may be configured to heat the
printed first partition/slice layer synchronously so that the
temperature of the printed first slice layer matches the
temperature of the molten material to be printed. Similarly, a heat
source 8 such as a laser beam or an electron beam may be configured
to heat a printed uppermost slice layer so that the temperature of
the printed uppermost slice layer matches the temperature of the
molten material to be printed; that is, the heating temperature may
be in the range of the melting point of the sprayed powder minus
200.degree. C. to the melting point of the sprayed powder, until
the printing of all slices may be completed. The method maintains
the advantages of the CS process such as solid-state deposition, no
dilution, low heat input, low oxidation, and low deformation,
thereby maintaining the composition and phase of the raw powder
material. The substrate 9 may be preheated by a heating furnace
provided outside a spray chamber, a plasma device provided inside
the spray chamber, or an electromagnetic heating coil provided on a
spraying workbench. The preheating temperature may be selected
according to the deposition characteristics of the ceramic or the
composite thereof. Generally, the preheating temperature may be in
the range of 600.degree. C. to 1,100.degree. C. For zirconia
ceramics, the preheating temperature of the substrate may be
900.degree. C. to 1,100.degree. C., and for alumina ceramics, the
preheating temperature of the substrate may be 600.degree. C. to
800.degree. C. The heat source such as the laser beam or the
electron beam to heat the area to be sprayed may be emitted by a
laser emitter synchronized with the spray gun, placed on the same
frame of the spray gun, or controlled by a separate robotic arm.
The power, pulse width and frequency of the laser emitter may be
adjusted based on the characteristics of the sprayed powder
material.
[0039] When the coating substrate is preheated and the printed
uppermost slice layer is heated, a temperature sensor 6 may be
configured to monitor the temperature of the heating area in real
time. The parameters (power, pulse width and frequency) of the
laser beam or electron beam are subjected to real-time closed-loop
feedback adjustment according to an optimal deposition temperature
of different sprayed materials so that the preheated substrate and
the printed uppermost slice layer maintain the optimal deposition
temperature. Meanwhile, the heating of the laser beam and other
heat sources reduces the critical speed and critical temperature
required for the deposition of high-melting-point materials such as
ceramics and their alloys and reduces the requirements for the
working gas (that is, N2 may be used instead of He to reduce the AM
cost). The disclosure softens the surface of a deposited layer
while another layer is deposited to enhance the plasticity of the
deposited layer, stabilize the deposition process, and improve the
forming quality. The sprayed particles are selected from
high-melting-point materials such as ceramics, cermets and ceramic
composites, and argon or nitrogen may be used as the working gas
during the deposition process.
[0040] During deposition, if the formed thickness, shape, and size
accuracies are not satisfactory, the formed slice layer may be
subjected to finishing. The finishing includes performing plastic
forming on the surface of the formed slice layer by roller
compaction until the required thickness, shape, and size
accuracies, or mill, grind or/and polish the formed slice layer
until the required thickness, shape, and size accuracies.
[0041] Step 104: After reaching the required size and surface
accuracies, the formed part is subjected to LSP; that is, a
high-frequency pulse laser device configured to modify the surface
of the formed part to generate a large residual compressive stress
thereon to extend the fatigue life of the formed part.
[0042] According to another aspect of the disclosure, an AM device
for a ceramic and a composite thereof may be provided to implement
the AM method described above. FIG. 2 is a structural diagram of a
device for implementing an AM method according to an embodiment of
the disclosure. As shown in FIG. 2, the device may include a data
processing module, a spraying deposition module, a heating module
and an LSP module. The data processing module may be configured to
slice a 3D CAD model of a workpiece to be formed into layers
according to the shape, thickness, and size accuracy requirements
thereof, obtain data of multiple slice layers, plan a forming path
according to the data of the slice layers, and generate CNC codes
for forming the slice layers. The spraying deposition module may be
configured to perform spraying deposition layer by layer according
to the CNC codes of the slice layers obtained by the data
processing module. The heating module may be configured to preheat
a substrate and heat a spray area to a temperature in the range of
a melting point of a sprayed powder minus 200.degree. C. to the
melting point of the sprayed powder until the printing of all slice
layers is completed. The LSP module may be configured to modify the
surface of a formed part to generate a predetermined residual
compressive stress thereon.
[0043] The device may further include a CNC machine tool. The CNC
machine tool may include a workbench 10, a gantry machine tool 1,
and a first spindle 5 provided on the gantry machine tool 1. The
workbench 10 may be provided below the gantry machine tool 1. The
gantry machine tool 1 may be configured to integrate the data
processing module, the spraying deposition module, the heating
module and the LSP module. The spraying deposition module may
include a high-speed CS gun 7 and a substrate 9. The high-speed CS
gun 7 may be provided at the bottom of the first spindle 5. The
substrate 9 may be provided on the workbench 10. The heating module
may include a first heating unit and a second heating unit. The
first heating unit may be provided above the substrate 9, and the
second heating unit may be provided at the bottom of the first
spindle 5. The device may further include a temperature sensor 6, a
second spindle 3, a milling/grinding device 2 and a micro-rolling
device 4. The temperature sensor 6 may be provided at the bottom of
the first spindle 5. The second spindle 3 may be provided on the
gantry machine tool 1. The milling/grinding device 2 may be
provided at the bottom of the second spindle 3. The micro-rolling
device 4 may be provided at the bottom of the first spindle 5. The
device may be installed on a five-axis machine tool, and cooperates
with double gantries or robotic arms to implement a composite AM.
The temperature sensor 6, the high-speed CS gun 7, and the second
heating unit 8 are mounted on the same gantry or robotic arm to
move synchronously and are located at the bottom of the first
spindle 5. The micro-rolling device 3 and the milling/grinding
device 2 are installed on the same gantry or robotic arm, namely,
at the bottom of the second spindle, and are each provided with a
lifting device so that they work independently to implement the
finishing process. The workbench 10 implements the translation of
one degree of freedom and the rotation of two degrees of freedom to
always keep a working surface perpendicular to the CS gun according
to the characteristics of the formed part to achieve the best
forming effect.
[0044] The working process of the device may be explained as
follows. A track may be planned, and a CNC program may be generated
for the printing process in advance. The preheating temperature and
the parameters of an auxiliary heat source (laser/plasma/arc) are
entered in a system according to different printed materials. The
CNC program and the parameters of the heat source are entered into
a redeveloped CNC system of the machine tool. The CNC system of the
machine tool automatically performs printing and micro-rolling
according to the parameters of the heat source and the CNC program.
During the printing process, the temperature sensor monitors the
temperature of the printed layer and adjusts the parameters of the
heat source in real time in a closed loop based on the temperature.
The surface topography may be measured by a line laser sensor, and
when a surface topography error reaches a certain threshold
(.gtoreq.1 mm), milling codes are automatically called to mill the
surface of the formed part to control the surface flatness.
[0045] To reduce the volume of the device, increase the flexibility
of the spray device, and effectively heat the sprayed powder and
the substrate to reduce heat loss, the disclosure combines a CS gun
with a laser heat source to form a laser/CS composite nozzle. FIG.
3 is a structural diagram of a laser/cold spraying (CS) composite
nozzle of a high-speed CS gun according to an embodiment of the
disclosure. As shown in FIG. 3, the nozzle may be configured to the
high-speed CS gun 7 and may include a composite nozzle outer wall
11 and a composite nozzle inner wall provided inside the composite
nozzle outer wall 11. A beam splitter 14 may be provided between
the composite nozzle outer wall 11 and the composite nozzle inner
wall to convert a direct laser beam generated by a laser into a
ring-shaped laser beam. A powder inlet 15 may be provided on the
top of the composite nozzle inner wall. A high-pressure gas inlet
16 may be provided on a side wall of the composite nozzle inner
wall. A nozzle 13 may be provided at the bottom of the composite
nozzle inner wall. The nozzle 13 may be a De Laval nozzle. The
nozzle outputs a laser beam and a high-pressure powder-gas mixture
coaxially. The beam splitter converts the laser beam generated by
the laser into a ring-shaped laser beam, which may intersect with
the powder-gas mixture at a certain distance from an outlet of the
De Laval nozzle to form a hot spray area to perform AM
continuously.
[0046] The working process of the nozzle may be explained as
follows. A preheated ceramic or ceramic composite powder material
fed by a servo powder feeder may be sent to the laser/CS composite
nozzle through the powder inlet 15. At the same time, a
controllable pressure gas may flow into the nozzle through the
high-pressure gas inlet 16. After being accelerated by the De Laval
nozzle, the high-pressure gas carrying the powder material may
coincide with a laser beam near the nozzle outlet. The laser beam
may enter through the laser inlet 17 and may be converted into a
ring-shaped laser beam by the beam splitter 14. The high-speed
powder-gas mixture may be further heated by the laser beam to reach
a deposition temperature to complete the forming process on the
substrate or a partially formed part.
EXAMPLE 1
[0047] According to the performance requirements of a superalloy
part, a superalloy powder may be used for high-speed CS
forming.
[0048] A forming substrate is heated to 900.degree. C. to
1,000.degree. C. by heating outside a spray chamber or heating
inside the spray chamber with a heating coil. A high-speed CS gun
is moved on the forming substrate to deposit the metal based on a
digital additive forming path derived from a 3D CAD model of the
part.
[0049] In the forming process, a heat source fixed beside the
high-speed CS gun simultaneously heated a spray area to a
temperature of 1,200.degree. C. to 1,300.degree. C., and a
micro-roller fixed behind the high-speed CS gun moved with the gun
to perform continuous cold rolling. In this way, high-speed CS
forming and pressure forming (PF) are carried out simultaneously.
If size and surface accuracies are not satisfactory, surface
finishing is performed layer by layer or by several layers by a
milling device in the synchronous forming process. Or, grinding and
polishing are performed layer by layer or by several layers
according to a grinding and polishing path planned coincidentally
with the synchronous forming path in the synchronous forming
process.
[0050] The finishing process and the synchronous forming process
are alternately performed until the forming process of a mold
cavity is completed and the size and surface accuracies are
satisfactory. After reaching the required size and surface
accuracies, the formed part is subjected to LSP; that is, a
high-frequency pulse laser device is used to modify the surface of
the formed part to generate a large residual compressive stress
thereon to extend the fatigue life of the formed part.
EXAMPLE 2
[0051] According to the performance requirements of an aluminum
alloy part, an aluminum alloy powder may be used for high-speed CS
forming.
[0052] A forming substrate is heated to 600.degree. C. to
800.degree. C. by heating outside a spray chamber or heating inside
the spray chamber with a heating coil. A high-speed CS gun is moved
on the forming substrate to deposit the metal based on a digital
additive forming path derived from a 3D CAD model of the part.
[0053] In the forming process, a heat source fixed beside the
high-speed CS gun simultaneously heated a spray area to a
temperature of 900.degree. C. to 1,100.degree. C., and a
micro-roller fixed behind the high-speed CS gun moved with the gun
to perform continuous cold rolling. In this way, high-speed CS
forming and PF are carried out simultaneously. If size and surface
accuracies are not satisfactory, surface finishing is performed
layer by layer or by several layers by a milling device in the
synchronous forming process. Or, grinding and polishing are
performed layer by layer or by several layers according to a
grinding and polishing path planned coincidentally with the
synchronous forming path in the synchronous forming process.
[0054] The finishing process and the synchronous forming process
are alternately performed until the forming process of a mold
cavity is completed and the size and surface accuracies are
satisfactory. After reaching the required size and surface
accuracies, the formed part is subjected to LSP; that is, a
high-frequency pulse laser device is used to modify the surface of
the formed part to generate a large residual compressive stress
thereon to extend the fatigue life of the formed part.
EXAMPLE 3
[0055] According to the performance requirements of a ceramic part,
a zirconia ceramic powder may be used for high-speed CS
forming.
[0056] A forming substrate is heated to 900.degree. C. to
1,100.degree. C. by heating outside a spray chamber or heating
inside the spray chamber with a heating coil. A high-speed CS gun
is moved on the forming substrate to deposit the metal based on a
digital additive forming path derived from a 3D CAD model of the
part.
[0057] In the forming process, a first heating unit fixed beside
the high-speed CS gun simultaneously heated a spray area to a
temperature of 1,000.degree. C. to 1,200.degree. C., and a
micro-roller fixed behind the high-speed CS gun moved with the gun
to perform continuous cold rolling. In this way, high-speed CS
forming and PF are carried out simultaneously. If size and surface
accuracies are not satisfactory, surface finishing is performed
layer by layer or by several layers by a milling device in the
synchronous forming process. Or, grinding and polishing are
performed layer by layer or by several layers according to a
grinding and polishing path planned coincidentally with the
synchronous forming path in the synchronous forming process.
[0058] The finishing process and the synchronous forming process
are alternately performed until the forming process of a mold
cavity is completed and the size and surface accuracies are
satisfactory. After reaching the required size and surface
accuracies, the formed part is subjected to LSP; that is, a
high-frequency pulse laser device is used to modify the surface of
the formed part to generate a large residual compressive stress
thereon to extend the fatigue life of the formed part.
EXAMPLE 4
[0059] According to the performance requirements of a metal-ceramic
gradient composite part, a multichannel synchronous servo powder
feeder and an accelerator may be used to perform high-speed CS
forming of the gradient composite material.
[0060] A forming substrate is heated to a preset temperature by
heating outside a spray chamber or heating inside the spray chamber
with a heating coil. A high-speed CS gun is moved on the forming
substrate to deposit the metal based on a digital additive forming
path derived from a 3D CAD model of the part.
[0061] In the forming process, a first heating unit fixed beside
the high-speed CS gun simultaneously heated a spray area, and a
micro-roller fixed behind the high-speed CS gun moved with the gun
to perform continuous cold rolling. In this way, high-speed CS
forming and PF are carried out simultaneously. If size and surface
accuracies are not satisfactory, surface finishing is performed
layer by layer or by several layers by a milling device in the
synchronous forming process. Or, grinding and polishing are
performed layer by layer or by several layers according to a
grinding and polishing path planned coincidentally with the
synchronous forming path in the synchronous forming process.
[0062] The finishing process and the synchronous forming process
are alternately performed until the forming process of a mold
cavity is completed and the size and surface accuracies are
satisfactory. After reaching the required size and surface
accuracies, the formed part is subjected to LSP; that is, a
high-frequency pulse laser device is used to modify the surface of
the formed part to generate a large residual compressive stress
thereon to extend the fatigue life of the formed part.
[0063] Various embodiments of the disclosure may have one or more
of the following effects.
[0064] In some embodiments, the disclosure may provide an additive
manufacturing (AM) method and device for a ceramic and a composite
thereof. The disclosure may combine the characteristics of the AM
process on ceramics and ceramic-metal composites with those of
thermal spraying (TS) and cold spraying (CS) and may skillfully
combine the TS with the CS process. The disclosure may maintain the
advantages of the CS process such as solid-state deposition, no
dilution, low heat input, low oxidation, and low deformation, which
may help to maintain the composition and phase of the raw powder
material. The disclosure may overcome deficiencies of the CS
process such as not being able to form a part with a
high-melting-point material (e.g., ceramic) and the deficiencies of
the TS process such as oxidation, phase transformation, ablation,
and grain growth of the formed part.
[0065] In other embodiments, the disclosed method may produce a
formed part with 0stable microstructure and performance and high
manufacturing accuracy and may be suitable for the AM of
high-melting-point materials such as ceramics and ceramic-metal
composites.
[0066] In further embodiments, the disclosure may provide an AM
method for a high-melting-point material such as a ceramic and a
ceramic-metal composite. The disclosure may help to solve the
defects of the existing moldless manufacturing methods of parts or
molds made of high-melting-point materials. As a result, the
prepared parts or molds may be free from thermally induced adverse
effects such as pores, shrinkage cavities, incomplete fusion, slag
inclusions, dilution, oxidation, decomposition, phase change,
deformation, cracking, flow, and fall caused by thermoforming (TF)
such as metal melt deposition. The disclosure may also overcome the
problems of high-speed CS deposition such as: the coating having
poor microstructure and low mechanical properties (e.g., density,
plasticity, and toughness,) difficulties in implementing effective
deposition of hard materials, small range of materials that may be
suitable for spraying, tapered surface of the continuously
cold-sprayed coating (causing a linear decrease in the deposition
rate), low surface and size accuracies, and an increase in the
equipment and operating costs.
[0067] In some embodiments, the disclosure may produce a formed
part with stable microstructure and performance and high
manufacturing accuracy and may be suitable for the AM of
high-melting-point materials such as ceramics and ceramic-metal
composites.
[0068] In other embodiments, the disclosure may combine the TS with
the CS process. A high-speed CS gun may be configured to deposit a
powder material, and a heat source may be configured to heat a
spray area in real time to a temperature in the range of the
melting point of the sprayed powder minus 200.degree. C. to the
melting point of the sprayed powder. The high-speed CS may be
maintained as a "cold working process" with low heat input, which
may help to avoid the thermally induced adverse effects caused by
the "thermoforming (TF)" processes such as TS and fused deposition
by a laser beam, an electron beam, and an electric arc. In
addition, the surface of the formed part may be modified to
generate a predetermined residual compressive stress thereon. The
method of the disclosure may produce parts or molds of metals,
intermetallic compounds (IMC), cermets, ceramics and their
functionally graded composite materials (FGCMs) with high quality,
high speed, and low cost.
[0069] In further embodiments, the disclosure discloses that a
substrate may be heated to a temperature in the range of the
melting point of the sprayed powder minus 2005.degree. C. to the
melting5 point of the sprayed powder until the spraying deposition
of the first slice layer completed in forming a first slice layer.
When the spraying deposition is performed on the surface of a
formed slice layer, the surface of the formed slice layer may be
heated to a temperature in the range of the melting point of the
sprayed powder minus 200.degree. C. to the melting point of the
sprayed powder. The high-speed CS may be maintained as a "cold
machining process" with low heat input, which may help to avoid the
thermally induced adverse effects caused by the "thermoforming"
processes such as TS, and fused deposition by a laser beam, an
electron beam, and an electric arc.
[0070] In some embodiments, the disclosure discloses that the
substrate may be preheated to 600.degree. C. to 1,100.degree. C.,
and the spray area may be heated to 800.degree. C. to 1,400.degree.
C. The preheating and heating temperatures may be adjusted
according to different materials so that the temperature of the
spray area matches the melting temperature of the material without
exceeding the melting point of the sprayed material.
[0071] In other embodiments, the disclosure discloses that during
deposition, if the formed thickness, shape, and size accuracies are
not satisfactory, the formed slice layer may be subjected to
finishing. The finishing may include performing plastic forming on
the surface of the formed slice layer by roller compaction until
the required thickness, shape, and size accuracies, or milling,
grinding and/or polishing the formed slice layer until the required
thickness, shape, and size accuracies. The disclosed method may
help to solve the actual engineering problem. The prepared part or
mold may be free from thermally induced adverse effects such as
pores, shrinkage cavities, incomplete fusion, slag inclusions,
dilution, oxidation, decomposition, phase change, deformation,
cracking, flow, and fall, which may help to improve the
microstructure and mechanical properties. This method may also be
suitable for hard materials and may spray a wide range of
materials. The method of the disclosure may also overcome the
problem of a tapered surface of the cold-sprayed coating causing a
linear decrease in the deposition rate and an increase in the
equipment and operating costs.
[0072] In further embodiments, the disclosure may be used for
surface repair or peening of parts or molds. It may effectively
increase the coating thickness and better the surface peening
performance compared with the CS or TS process alone. In addition,
the disclosure may overcome the technical bottleneck of the
existing method which is difficult to perform subsequent finishing
on the repaired or peened layer after repair and peening of
quenching hardening.
[0073] In some embodiments, the disclosure may provide a device
which integrates a data processing module, a spraying deposition
module, a heating module, and an LSP module, all of which may
cooperate with each other. The prepared part or mold may be free
from thermally induced adverse effects such as pores, shrinkage
cavities, incomplete fusion, slag inclusions, dilution, oxidation,
decomposition, phase change, deformation, cracking, flow, and fall,
which may help to improve the microstructure and mechanical
properties. The device may be also suitable for hard materials and
may spray a wide range of materials. The device of the disclosure
may also overcome the problem of a tapered surface of the
cold-sprayed coating causing a linear decrease in the deposition
rate and an increase in the equipment and operating costs.
[0074] In other embodiments, the disclosure may provide a nozzle
combining a CS gun with a laser heat source to output a laser beam
and a high-pressure powder-gas mixture coaxially. A beam splitter
may convert the laser beam generated by a laser into a ring-shaped
laser beam, which may intersect with the powder-gas mixture at a
certain distance from a nozzle outlet to form a hot spray area to
perform AM continuously. The nozzle may reduce the volume of the
device and increase the flexibility of the spray device so that the
sprayed powder and the substrate may be heated effectively to
reduce heat loss.
[0075] In further embodiments, the disclosure may provide a method
combining a high-speed cold spraying (CS) process with a
milling/pressure forming (PF) process. The disclosure may utilize
the advantages of the high-speed CS process so that the prepared
product does not have the defects of thermoforming (TF) and
high-speed CS processes, which may help to ensure the final
accuracy and performance of the product.
[0076] Many different arrangements of the various components
depicted, as well as components not shown, are possible without
departing from the spirit and scope of the present invention.
Embodiments of the present invention have been described with the
intent to be illustrative rather than restrictive. Alternative
embodiments will become apparent to those skilled in the art that
do not depart from its scope. A skilled artisan may develop
alternative means of implementing the aforementioned improvements
without departing from the scope of the present invention.
[0077] It will be understood that certain features and
subcombinations are of utility and may be employed without
reference to other features and subcombinations and are
contemplated within the scope of the claims. Unless indicated
otherwise, not all steps listed in the various figures need be
carried out in the specific order described.
* * * * *