CN115229215B

CN115229215B - Apparatus and method for additive manufacturing of gradient materials

Info

Publication number: CN115229215B
Application number: CN202210893498.3A
Authority: CN
Inventors: 谭乐; 唱丽丽; 李午红; 申赛刚; 闫成鑫
Original assignee: Nanjing Zhongke Raycham Laser Technology Co Ltd
Current assignee: Nanjing Zhongke Raycham Laser Technology Co Ltd
Priority date: 2022-07-27
Filing date: 2022-07-27
Publication date: 2023-08-29
Anticipated expiration: 2042-07-27
Also published as: CN115229215A

Abstract

The invention relates to the technical field of additive manufacturing, and provides a device and a method for additive manufacturing of gradient materials. The device for additive manufacturing gradient materials comprises a printing control system, a laser optical scanning system, a forming bin, a powder feeder, a powder spreading system and a substrate. Wherein in the middle part of the shaping surface of each layer, a lap joint area formed by a first material and a second material is formed, a laser optical scanning system in the lap joint area adopts a corresponding laser scanning process to shape according to the powder spreading range of different materials, and in the powder spreading process of each deposition layer, a baffle plate is arranged to move in the lap joint area range of the gradient material, thereby realizing the dynamic adjustment of the lap joint line of the gradient material in the lap joint area between different deposition layers, inhibiting lap joint marks and improving the printing shaping quality of the lap joint area.

Description

Apparatus and method for additive manufacturing of gradient materials

Technical Field

The invention relates to the technical field of additive manufacturing, in particular to a powder-laying type laser cladding additive manufacturing technology, and particularly relates to a device and a method for manufacturing gradient materials by additive.

Background

Gradient materials refer to a novel composite material in which two or more materials are compounded to form a composition and structure which change continuously in gradient, the chemical composition or structure of which changes gradually in space according to the intended design to achieve a specific performance, and thus are also called functional gradient materials (Functionally Graded Materials, FGM), and internal stress is reduced by adding a gradually changing gradient layer between the two materials.

The laser selective melting forming technology (Selective Laser Melting, SLM) which is an important branch of the additive manufacturing printing technology is hopeful to realize high-precision printing forming of gradient materials by changing the feed ratio to realize gradient transition from the component A to the component B, but is difficult to control overlap joint of the gradient layers.

Disclosure of Invention

According to a first aspect of the object of the invention, an apparatus for additive manufacturing of gradient materials is proposed, comprising a printing control system, a laser optical scanning system, a molding bin, a powder feeder, a powder spreading system and a substrate;

the powder spreading system and the substrate are both arranged in the forming bin, and the powder spreading system is configured to receive at least two kinds of powder from the powder feeder and send the at least two kinds of powder to the surface of the substrate according to a preset gradient control strategy so as to finish powder spreading;

the laser optical scanning system is arranged above the forming bin and is used for cladding forming according to the at least two kinds of powder and according to the powder laying range of different materials by adopting a corresponding laser scanning process;

the printing control system is used for controlling the operation of the powder feeder, the powder spreading system and the laser optical scanning system;

the powder spreading system comprises a powder box, a powder conveying pipe, a scraper, a powder outlet, a powder spreading motion control mechanism and a gradient adjustment control mechanism;

the scraper and the powder outlet are arranged at the lower bottom surface of the powder box;

a cavity is formed in the powder box, a partition plate is inserted into the cavity to divide the cavity into a first powder bin and a second powder bin which are independent, the first powder bin is used for containing first-class powder, and the second powder bin is used for containing second-class powder; the first powder bin and the second powder bin are respectively provided with a corresponding powder conveying pipe so as to respectively receive the first type of powder and the second type of powder conveyed by the powder conveying device;

the lower ends of the first powder bin and the second powder bin are in shrinkage trend and are communicated with the powder outlet at the lower bottom surface of the powder box, so that the first type of powder and the second type of powder can be discharged from the space at one side of each powder bin through the powder outlet;

the powder spreading motion control mechanism is used for driving the powder box to move along a preset path on the surface of the substrate, and scraping the powder falling through the powder outlet by a scraper to finish powder spreading;

the gradient adjusting control mechanism is used for driving the partition plate to move in the cavity so as to dynamically adjust the position of the bonding wire within the range of bonding areas of different materials between different deposition layers.

As an alternative embodiment, the gradient adjusting control mechanism is a motor motion control mechanism, and the separator is driven by the motion of the motor to move linearly in the cavity, so that the separator moves in a preset gradient material overlap area, and the dynamic adjustment of the overlap line of the gradient material in the overlap area is realized between different deposition layers.

As an alternative embodiment, the separator is arranged to move once for each layer, the distance of each movement being d sin θ, d representing the width of the overlap region along the powder laying direction, 10 θ+.ltoreq.90 °, θ representing the step angle, being an integer multiple of 10.

As an alternative embodiment, the overlap region defines a zero position and a final position thereof, and the diaphragm is driven to move from the zero position towards the final position or from the final position towards the zero position during printing;

and for one movement, if the distance s from the last position or zero position of the lapping area is smaller than d.sin theta for the scraper position obtained from the last movement, controlling the partition plate to correspondingly return to the zero position or the last position and continuously moving d.sin theta-s, thereby determining the position of the partition plate and the position of the lapping line.

According to a second aspect of the object of the present invention there is also presented a method of gradient material additive manufacturing comprising the steps of:

planning a printing path and a laser scanning process of additive manufacturing according to the molded part and the powder material;

different powder materials are respectively fed into a first powder bin and a second powder bin of the powder paving system through a powder feeder;

controlling the powder spreading system to move along the powder spreading direction, spreading the powder falling onto the surface of the substrate through the powder outlet by using a scraper, and finishing the powder spreading corresponding to each deposition layer;

the laser optical scanning system scans according to a planned laser scanning process, forms the molding surface of the powder spreading and forms a deposition layer, and spreads the powder layer by layer and forms a growing mode until the printing process of the whole molding part is completed;

wherein, in the middle part of the shaping surface of each layer, a lap joint area formed by a first material and a second material is formed, a laser optical scanning system adopts a corresponding laser scanning technology to shape according to the powder spreading range of different materials in the lap joint area, and in the powder spreading process of each layer of deposition layer, the baffle plate is arranged to move in the lap joint area range of the gradient material, thereby realizing the dynamic adjustment of the lap joint line of the gradient material in the lap joint area between different deposition layers so as to inhibit lap joint marks.

As an alternative embodiment, the separator is arranged to move once for each layer, the distance of each movement being d sin θ, d representing the width of the overlap region along the powder laying direction, θ being 10+.θ+.90°, θ representing the step angle.

The device for additively manufacturing the gradient material and the method for additively manufacturing the gradient material, provided by the invention, have the advantages that the linear motion of the partition board is adopted, the motion quantity is controlled each time, the motion quantity is converted according to a sine function, so that the dynamic motion quantity is determined, the lap joint line in the lap joint area in the printing process of each layer is realized to be a dynamic adjustment process, and the motion is realized in a mode similar to random fluctuation. So as to inhibit and eliminate the trace of the bonding wire, avoid the bonding defect caused by the position fixing of the bonding wire, and improve the printing quality of the splicing area.

It should be understood that all combinations of the foregoing concepts, as well as additional concepts described in more detail below, may be considered a part of the inventive subject matter of the present disclosure as long as such concepts are not mutually inconsistent. In addition, all combinations of claimed subject matter are considered part of the disclosed inventive subject matter.

The foregoing and other aspects, embodiments, and features of the present teachings will be more fully understood from the following description, taken together with the accompanying drawings. Other additional aspects of the invention, such as features and/or advantages of the exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of the embodiments according to the teachings of the invention.

Drawings

The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

fig. 1 is a schematic structural view of an apparatus for additive manufacturing of gradient materials according to an exemplary embodiment of the present invention.

Fig. 2 is a schematic structural view of a powder spreading system according to an exemplary embodiment of the present invention.

Fig. 3 is a side cross-sectional view of a compact according to an exemplary embodiment of the present invention.

Fig. 4 is a bottom view of a compact according to an exemplary embodiment of the present invention.

Fig. 5 is a schematic illustration of a landing zone of an exemplary embodiment of the present invention.

Detailed Description

For a better understanding of the technical content of the present invention, specific examples are set forth below, along with the accompanying drawings.

Aspects of the invention are described in this disclosure with reference to the drawings, in which are shown a number of illustrative embodiments. The embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, may be implemented in any of a number of ways, as the disclosed concepts and embodiments are not limited to any implementation. Additionally, some aspects of the disclosure may be used alone or in any suitable combination with other aspects of the disclosure.

An apparatus for additive manufacturing of gradient materials in connection with the exemplary embodiment shown in fig. 1-4 comprises a print control system 1, a laser optical scanning system 2, a forming bin 3, a powder feeder 4, a powder spreading system 5, and a substrate 6.

The powder spreading system 5 and the substrate 6 are both arranged inside the molding bin 3, and the powder spreading system 5 is configured to receive at least two kinds of powder from the powder feeder 4 and send the at least two kinds of powder to the surface of the substrate 6 according to a preset gradient control strategy to finish powder spreading.

The base plate 6 is mounted in a bottom-centered position inside the forming chamber 3 and is arranged to be movable in a vertical direction by a forming cylinder located at its bottom, each movement being at a height of the thickness of each deposited layer.

The laser optical scanning system 2 is arranged above the forming bin 3 and is used for carrying out cladding forming by adopting corresponding laser scanning technology according to at least two kinds of powder and according to the powder laying range of different materials.

The print control system 1 is provided for controlling the operation of the powder feeder 4, the powder spreading system 5, and the laser optical scanning system 2.

The powder spreading system 5 comprises a powder box 7, powder conveying pipes (8A and 8B), a scraper 9, a powder outlet 10, a powder spreading motion control mechanism 11 and a gradient adjusting control mechanism 13.

The scraper 9 and the powder outlet 10 are arranged at the lower bottom surface of the powder box 7.

A cavity is formed in the powder box 7, a partition plate 12 is inserted into the cavity to divide the cavity into a first powder bin 7A and a second powder bin 7B which are independent, the first powder bin 7A is used for containing first type powder, and the second powder bin 7B is used for containing second type powder; the first and second powder bins 7A, 7B are provided with corresponding powder conveying pipes 8A, 8B, respectively, to receive the first and second kinds of powder conveyed from the powder feeder 4, respectively.

The lower ends of the first powder bin 7A and the second powder bin 7B are in shrinkage trend and are communicated with the powder outlet 10 at the lower bottom surface of the powder box 7, so that the first type powder and the second type powder can be discharged from the space at one side of each powder outlet 10.

The powder spreading motion control mechanism 11 is provided to drive the powder box 7 to move along a predetermined path on the surface of the substrate 6, and the powder falling through the powder outlet 10 is scraped off by the scraper 9 to complete the powder spreading.

A gradient adjustment control mechanism 13 is provided for driving the diaphragm 12 to move within the cavity to dynamically adjust the crossover line position within the overlap region of the different materials between the different deposited layers.

As shown in fig. 1, 2 and 4, the powder outlet 10 is located on the front side of the doctor blade 9 along the first direction with the direction of the powder laying movement as the first direction.

The side of the molding bin 3 is provided with a guide rail groove, and the powder spreading motion control mechanism 11 is a motor motion control mechanism, such as a direct current or alternating current motor, and drives the powder box 7 and the scraper 9 to move along the guide direction of the guide rail groove through a transmission mechanism so as to spread powder on the surface of the substrate 6 in a preset powder spreading direction and path. The foregoing transmission means particularly refers to a transmission mechanism that converts rotational motion into linear motion, including but not limited to rack and pinion transmission, screw transmission, and the like.

As an alternative embodiment, the powder box 7 is arranged in a rectangular flat box-like structure, and a first powder conveying pipe 8A and a second powder conveying pipe 8B are respectively arranged at two sides of the upper end face of the powder box, the first powder conveying pipe 8A and the second powder conveying pipe 8B are respectively connected to the external powder feeder 4, and the powder feeder 4 respectively feeds powder into the corresponding first powder bin 7A and the corresponding second powder bin 7B through the corresponding powder conveying pipes.

As an alternative example, two or more powder feeders 4 may be provided, each holding a different powder.

The powder volume contained in the powder box 7 is 1.5-2.5 times of the substrate molding area multiplied by the layer thickness. Wherein, every time powder is fed from the powder feeder 4 into the powder box 7 through the corresponding powder conveying pipe, the powder feeding amount can be controlled through the gear arranged on the powder conveying pipe, for example, the control of the powder feeding amount is realized by controlling the number of teeth passing through.

As an alternative example, the first hopper 7A and the second hopper 7B are each provided in a flat box shape and in a structure of wide upper and narrow lower and continuously contracting and changing, so as to facilitate natural falling of the powder.

As shown in fig. 2, a rectangular powder box is taken as an example, and the long side is X-direction, the short side is Y-direction, and the height is Z-direction in the cross-sectional plane of the rectangular side. In the preferred embodiment, in the Y-Z plane direction, the side cross-sectional shapes of the first powder bin 7A and the second powder bin 7B are funnel-shaped, and gradually shrink from top to bottom. As shown in fig. 2 and 4, the leakage openings at the bottoms of the first powder bin 7A and the second powder bin 7B are long and are opposite to and communicated with the long powder outlet 9.

In an alternative embodiment, as shown in connection with fig. 2, 3 and 5, the gradient adjustment control mechanism 13 is used to drive the separator 12 to move linearly within the cavity so as to move the separator 12 within a predetermined overlap region of the gradient material, thereby achieving dynamic adjustment of the overlap line of the gradient material within the overlap region between different deposited layers.

As an alternative example, the gradient adjustment control mechanism 13 is a motor motion control mechanism, for example, a shaft end gear is driven by an output shaft of a motor, a rack connected with the motor is driven by the shaft end gear to move, and the partition board is connected with the rack, so that the partition board 12 is driven by the movement of the motor to move linearly in the cavity, so that the partition board 12 moves in a preset gradient material lapping zone, and thus, dynamic adjustment of the lapping line of the gradient material in the lapping zone is realized between different deposition layers.

As shown schematically in fig. 5, which illustrates an illustration of the overlap region and the crossover line during printing of graded material additive manufacturing, in an embodiment of the present invention, the separator 12 is configured to move within the overlap region to change the position of the crossover line, and in particular, to dynamically adjust the position of the crossover line within the overlap region during printing of each deposited layer, thereby inhibiting and eliminating traces of the crossover line during multi-layer printing to improve the print quality of the overlap region.

In the embodiment of the present invention, as shown in fig. 5, the gradient material may be selected from powder special for additive manufacturing such as iron-based, nickel-based, titanium-based, aluminum-based, stainless steel, etc., and in particular, different powder components are similar, or a certain component is changed in proportion, so as to ensure the stability of the performance of the lap joint area in the forming process.

Different metal powders, such as TC4 and TiAl titanium alloy, are respectively filled in different powder feeders, and different powders are respectively conveyed into a powder box for storage by controlling the number of teeth rotated by gears in a powder conveying pipe; in the powder spreading process, the powder is uniformly spread on a molding surface of the substrate by a rubber scraper, and the molding surface is molded by a laser optical scanning system. Wherein, in the middle part of the molding surface, the overlap joint area of the gradient material is formed, and a laser optical scanning system in the overlap joint area adopts different processes to mold according to the powder spreading range of different materials. When the next layer is printed, the separator is moved within a preset overlap area for a certain distance, then the separator is subjected to blanking and powder spreading for printing, and the process is circulated until the molding is finished.

Wherein the separator 12 is arranged to move once for each layer, the distance of each movement being d x sin θ, d representing the width of the overlap region along the powder laying direction, 10+.ltoreq.θ.ltoreq.90°, θ representing the step angle, being an integer multiple of 10.

As shown in connection with fig. 5, the overlap region defines its zero and end positions, from which the diaphragm 12 is driven to move toward the end position or from the end position toward the zero position during printing.

Wherein for one movement, if the doctor position obtained from the last movement is less than d x sin θ from the last position or zero position of the overlap region, the separator 12 is controlled to correspondingly return to the zero position or last position and continue to move d x sin θ -s, thereby determining the position of the separator 12 and the position of the overlap line.

Taking the example of moving from the zero position to the last position, after the scraper moves a certain distance (for example, a plurality of times), when the distance s between the position of the scraper and the last position on the other side is smaller than d×sin θ, the control partition board returns to the zero position again, and moves d×sin θ -s from the zero position, so that the position of the partition board 12 and the position of the bonding wire are determined, the position of the partition board of each layer and the determined position of the bonding wire are ensured to be different, and the trace of the bonding wire is restrained and eliminated.

In connection with the example additive manufacturing apparatus of fig. 1-5, embodiments of the present invention summarize a gradient material additive manufacturing method comprising the steps of:

different powder materials are respectively fed into a first powder bin 7A and a second powder bin 7B of the powder paving system 5 through the powder feeder 4;

controlling the powder spreading system 5 to move along the powder spreading direction, spreading the powder falling onto the surface of the substrate 6 through the powder outlet 10 by a scraper 9, and finishing the corresponding powder spreading of each deposition layer;

the laser optical scanning system 2 scans according to a planned laser scanning process, forms the molding surface of the powder spreading and forms a deposition layer, and spreads the powder layer by layer and forms a growing mode until the printing process of the whole molding part is completed;

wherein, in the middle of the molding surface of each layer, a lap zone formed by the first material and the second material is formed, the laser optical scanning system 2 is molded by adopting a corresponding laser scanning process according to the powder spreading range of different materials in the lap zone, and in the powder spreading process of each deposition layer, the partition 12 is arranged to move in the lap zone range of the gradient material, thereby realizing the dynamic adjustment of the lap line of the gradient material in the lap zone between different deposition layers so as to inhibit lap marks.

Wherein the overlap region defines its zero and end positions, from which the diaphragm 12 is driven to move towards the end position, or from the end position towards the zero position, during printing;

While the invention has been described with reference to preferred embodiments, it is not intended to be limiting. Those skilled in the art will appreciate that various modifications and adaptations can be made without departing from the spirit and scope of the present invention. Accordingly, the scope of the invention is defined by the appended claims.

Claims

1. The device for additive manufacturing of the gradient material is characterized by comprising a printing control system (1), a laser optical scanning system (2), a forming bin (3), a powder feeder (4), a powder spreading system (5) and a substrate (6);

the powder spreading system (5) and the substrate (6) are both arranged in the forming bin (3), the powder spreading system (5) is configured to receive at least two kinds of powder from the powder feeder (4) and send the at least two kinds of powder to the surface of the substrate (6) according to a preset gradient control strategy to finish powder spreading;

the laser optical scanning system (2) is arranged above the forming bin (3) and is used for cladding forming according to the at least two kinds of powder and according to the powder spreading range of different materials by adopting a corresponding laser scanning process;

the printing control system (1) is used for controlling the operation of the powder feeder (4), the powder spreading system (5) and the laser optical scanning system (2);

the powder spreading system (5) comprises a powder box (7), powder conveying pipes (8A and 8B), a scraper (9), a powder outlet (10), a powder spreading motion control mechanism (11) and a gradient adjustment control mechanism (13);

the scraper (9) and the powder outlet (10) are arranged at the lower bottom surface of the powder box (7);

a cavity is formed in the powder box (7), a partition plate (12) is inserted into the cavity to divide the cavity into a first powder bin (7A) and a second powder bin (7B), the first powder bin (7A) is used for containing first-class powder, and the second powder bin (7B) is used for containing second-class powder; the first powder bin (7A) and the second powder bin (7B) are respectively provided with corresponding powder conveying pipes (8A, 8B) for respectively receiving the first type of powder and the second type of powder conveyed by the powder feeder (4);

the lower ends of the first powder bin (7A) and the second powder bin (7B) are in shrinkage trend and are communicated with a powder outlet (10) at the lower bottom surface of the powder box (7), so that the first type of powder and the second type of powder can be discharged from the space at one side of each powder outlet (10);

the powder spreading motion control mechanism (11) is used for driving the powder box (7) to move along a preset path on the surface of the substrate (6), and scraping the powder falling through the powder outlet (10) through the scraper (9) to finish powder spreading;

the gradient adjustment control mechanism (13) is used for driving the partition plate (12) to move in the cavity inside the powder box (7) so as to dynamically adjust the position of the lapping line in the range of the lapping area of different materials between different deposition layers;

the gradient adjusting control mechanism (13) is a motor motion control mechanism, and the separator (12) is driven to linearly move in a cavity in the powder box (7) by the motion of the motor so that the separator (12) moves in a preset gradient material overlapping area, and therefore dynamic adjustment of the overlapping line of the gradient material in the overlapping area is realized between different deposition layers;

and the separator (12) is arranged to move once for each layer, the distance of each movement is d.sin theta, d represents the width of the overlap region along the powder spreading direction, theta is more than or equal to 10 degrees and less than or equal to 90 degrees, and theta represents the stepping angle which is an integer multiple of 10.

2. An apparatus for additive manufacturing gradient material according to claim 1, characterized in that the powder outlet (10) is located on the front side of the doctor blade (9) along a first direction of the powder laying movement.

3. An apparatus for additive manufacturing of a gradient material according to claim 1, characterized in that the base plate (6) is mounted in a bottom-centered position inside the forming bin (3) and is arranged to be movable in a vertical direction driven by a forming cylinder located at its bottom, each movement being at a height of the thickness of each deposited layer.

4. The apparatus for additive manufacturing of gradient material according to claim 1, wherein the side of the forming bin (3) is provided with a guide rail groove, and the powder spreading motion control mechanism (11) is a motor motion control mechanism for driving the powder box (7), the doctor blade (9) to move along the direction guided by the guide rail groove, and spreading powder on the surface of the substrate (6) in a predetermined powder spreading direction and path.

5. The apparatus for additive manufacturing gradient material according to claim 1, wherein the first powder bin (7A) and the second powder bin (7B) are each provided in a flat box-like shape and in a structure that is wide at the top and narrow at the bottom and continuously varies in shrinkage.

6. The device for additive manufacturing of gradient materials according to claim 1, characterized in that the powder volume contained in the powder box (7) is 1.5-2.5 times the substrate molding surface area multiplied by the layer thickness, controlled by the number of teeth rotated by the gears of the powder conveying pipe.

7. The device for additive manufacturing gradient material according to claim 1, characterized in that the overlap zone defines a zero position and a final position thereof, from which the shutter (12) is driven to move towards the final position or from the final position towards the zero position during printing;

and for one movement, if the distance s from the last position or zero position of the lapping area is smaller than d.sin theta for the doctor position obtained from the last movement, controlling the partition plate (12) to correspondingly return to the zero position or the last position and continuously moving d.sin theta-s, so as to determine the position of the partition plate (12) and the lapping line position.

8. A gradient material additive manufacturing method of the apparatus for additive manufacturing of a gradient material according to claim 1, comprising the steps of:

different powder materials are respectively fed into a first powder bin (7A) and a second powder bin (7B) of the powder spreading system (5) through a powder feeder (4);

controlling the powder spreading system (5) to move along the powder spreading direction, spreading the powder falling onto the surface of the substrate (6) through the powder outlet (10) by a scraper (9), and finishing the powder spreading corresponding to each deposition layer;

the laser optical scanning system (2) scans the molding surface of the powder spreading according to a planned laser scanning process to form a deposition layer, and the powder spreading and molding growth mode is adopted layer by layer until the printing process of the whole molding part is completed;

wherein, in the middle part of the molding surface of each layer, a lap joint area formed by a first material and a second material is formed, a laser optical scanning system (2) is molded by adopting a corresponding laser scanning process according to the powder laying range of different materials in the lap joint area, and in the powder laying process of each deposition layer, a baffle (12) is arranged to move in the lap joint area range of the gradient material, thereby realizing the dynamic adjustment of the lap joint line of the gradient material in the lap joint area between different deposition layers so as to inhibit lap joint marks;

wherein the separator (12) is arranged to move once for each layer, the distance of each movement is d.sin theta, d represents the width of the overlap region along the powder spreading direction, theta is more than or equal to 10 degrees and less than or equal to 90 degrees, and theta represents the stepping angle which is an integer multiple of 10.

9. The method of additive manufacturing of gradient material according to claim 8, wherein the overlap region defines a zero position and a final position thereof, the diaphragm (12) being driven to move from the zero position towards the final position or from the final position towards the zero position during printing;