Heterogeneous material powder bed laser additive manufacturing device and method

Abstract

The invention discloses a heterogeneous material powder bed laser additive manufacturing device and method.The heterogeneous material powder bed laser additive manufacturing device comprises a fixed-point powder suction ultrasonic powder feeding system, an electrostatic powder laying system and a powder bed additive manufacturing forming system, and the fixed-point powder suction ultrasonic powder feeding system and the electrostatic powder laying system are both arranged in the powder bed additive manufacturing forming system. The automatic powder spreading device has a heterogeneous material powder spreading mode of ultrasonic powder feeding and electrostatic powder spreading, the utilization rate of materials is effectively improved, the manufacturing efficiency is improved, the scraper, the electrostatic powder spreading device and the powder spreading trolley are combined into a whole, the flexibility and applicability of equipment are enhanced, the conversion and waiting time between the equipment can be shortened, the production efficiency is improved, and the production cost is reduced. The powder feeding device has the advantages that automatic replacement of the powder feeding needle tubes is achieved, manual intervention is not needed, the working efficiency is greatly improved, the powder feeding needle tubes with different calibers are adopted, the powder laying quality of the connecting positions of the heterogeneous materials is further improved while the powder laying efficiency is not lost, and the final interface connecting effect of the heterogeneous materials is indirectly enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a heterogeneous material powder bed laser additive manufacturing device and method. Background Art

[0002] Nowadays, additive manufacturing technology is listed as one of the twelve disruptive technologies that will determine the future economy. It is one of the fastest-growing, most active and most concerned disciplines in the world's advanced manufacturing field, with broad application prospects and huge development potential. Metal heterogeneous material additive manufacturing technology refers to the preparation of a single complex functional component with a variety of material structures by combining multiple materials to meet the specific requirements of material performance, function and structural integration in different application scenarios. New processes, new principles, new materials and new applications related to additive manufacturing are constantly emerging around the world. With the development of contemporary science and technology and the innovation of the technology industry, metal heterogeneous material additive manufacturing technology has shown broad application prospects in aerospace, military, medical and other fields. This technology breaks through the limitations of traditional manufacturing methods and can achieve precise control and optimization of material composition and structure from micro to macro scales, providing strong support for the development of high-performance, multi-functional and lightweight advanced manufacturing products.

[0003] The forming principle of powder bed laser melting is: first, a layer of metal powder to be printed is spread on the substrate, and then the laser heats and melts the metal powder in the specified area through the scanning galvanometer, field mirror, etc. to form a cladding layer, and then the substrate is lowered by one layer, and the system re-spreads the powder, and the above steps are repeated until the printing is completed. In the field of additive manufacturing processing of powder bed melting, heterogeneous material additive manufacturing usually requires the heterogeneous material to be freely and accurately pre-placed on the powder bed as needed before the next step of laser heating and melting can be carried out. The mainstream heterogeneous material pre-positioning methods include scraper powder feeding, ultrasonic powder feeding, electronic photography powder feeding, and scraper + ultrasonic assisted powder feeding. Different from the traditional single scraper heterogeneous material layer-by-layer printing method, ultrasonic powder feeding can realize the one-time accurate pre-positioning of heterogeneous material powder, greatly improving the powder utilization rate, while reducing the powder mixing phenomenon and the difficulty of recycling heterogeneous material powder. In the process of ultrasonic powder feeding, the distribution of powder may be affected by many factors, including powder feeding speed, vibration frequency, substrate flatness, powder type, etc. The powder clumps on the substrate during ultrasonic powder dropping often accumulate into hills and then collapse. In order to ensure that the interface joints of heterogeneous materials of the final formed part are tightly fitted, more powder is usually required to reduce the defects such as holes and cracks at the formed joints. This also leads to uneven powder spreading at the joints of heterogeneous materials. At the same time, the repeated path powder spreading of the ultrasonic vibrator at the connection interface also aggravates this phenomenon. At present, the research on ultrasonic powder feeding by researchers is not perfect enough. The ultrasonic powder feeding technology still has a series of problems such as uneven surface after powder dropping, excessive powder spreading thickness at the joints of heterogeneous materials, and aggravated powder mixing caused by scraper powder spreading, which have a certain impact on the final printing quality. Therefore, we propose a laser additive manufacturing device and method for heterogeneous material powder bed. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a device and method for laser additive manufacturing of a powder bed of heterogeneous materials. In the powder spreading stage of powder bed additive manufacturing, the main material powder (powder placed in a powder cylinder) is first spread from the powder cylinder to the upper surface of the substrate by a flexible scraper, and then the powder suction system is turned on. The controller sends a control signal to the motor to drive the three-axis slide to move according to a predetermined path program, driving the powder suction tube to absorb powder along a specified path. After the end, the powder suction system is closed, and the ultrasonic powder dropping system is started. The coarse-caliber powder delivery needle first fills the non-edge area where the powder has been sucked out, and then it is automatically replaced with the fine-caliber powder delivery needle after the end, and then the powder is delivered to the edge area where the powder has been sucked out. Finally, the electrostatic powder spreading system is operated, and the electric field strength between the electrodes can be adjusted instantly according to the material properties while the powder spreading vehicle moves forward to complete a layer of heterogeneous material powder spreading. The above steps are repeated for each layer of powder spreading, and finally the powder spreading quality of each layer is effectively improved to complete the additive manufacturing of heterogeneous materials.

[0005] The present invention is implemented as follows: a heterogeneous material powder bed laser additive manufacturing device, comprising:

[0006] A fixed-point powder suction and ultrasonic powder feeding system, an electrostatic powder spreading system and a powder bed additive manufacturing molding system, wherein the fixed-point powder suction and ultrasonic powder feeding system and the electrostatic powder spreading system are both arranged in the powder bed additive manufacturing molding system;

[0007] The powder bed additive manufacturing molding system includes an optical path system, a molding cavity, a molding cylinder, a powder cylinder and a flexible scraper. The powder cylinder is arranged at the bottom of the molding cavity, and the powder cylinder is communicated with the inside of the molding cavity. The molding cylinder is arranged at the bottom of the molding cavity, and the molding cylinder is communicated with the inside of the molding cavity. The flexible scraper is arranged at one end of the bottom of the molding cavity.

[0008] The fixed-point powder suction ultrasonic powder feeding system comprises an ultrasonic vibrator, multiple groups of powder feeding needle tubes, a powder suction tube and a needle tube rack, wherein the powder feeding needle tubes are hung on the needle tube rack, and the needle tube rack is arranged inside the molding cavity, wherein one group of powder feeding needle tubes is detachably arranged inside the ultrasonic vibrator;

[0009] The electrostatic powder spreading system includes an electrostatic powder spreading mechanism and a powder spreading vehicle. The powder spreading vehicle is horizontally movably arranged inside the molding cavity, and the electrostatic powder spreading mechanism is arranged at the bottom of the powder spreading vehicle. The electrostatic powder spreading mechanism is located above the powder cylinder and the powder recovery cylinder.

[0010] Optionally, a screw slide is provided on one side of the molding cavity, and a double-rod cylinder is connected to the molding cavity on one side through the screw slide for lifting, and an internal support clamp is provided on the movable end of the double-rod cylinder. The needle tube rack is located at the bottom of the screw slide, and a placement hole for placing the powder feeding needle is opened on the needle tube rack, and the internal support clamp is arranged vertically corresponding to the placement hole.

[0011] Optionally, the powder feeding needle tube is composed of a large-caliber powder feeding needle tube A, a small-caliber powder feeding needle tube A, a large-caliber powder feeding needle tube B and a small-caliber powder feeding needle tube B, and the large-caliber powder feeding needle tube A, the small-caliber powder feeding needle tube A, the large-caliber powder feeding needle tube B and the small-caliber powder feeding needle tube B are all hung on the needle tube rack.

[0012] Optionally, the ultrasonic vibrator is composed of a front cover plate, a rear cover plate, a piezoelectric ceramic sheet, an electrode sheet and a hollow bolt, and the powder feeding needle tube is detachably arranged in the ultrasonic vibrator.

[0013] Optionally, a three-axis slide system is provided at the upper end of one side inside the molding cavity, and the ultrasonic vibrator is transmission-connected to the three-axis slide system, so that the ultrasonic vibrator is movably arranged inside the molding cavity through the three-axis slide system, and the powder suction tube is arranged between the ultrasonic vibrator and the three-axis slide system, and a push-pull electromagnet is provided at the transmission end of the three-axis slide system, the push-pull electromagnet is arranged close to the ultrasonic vibrator, and the push-pull electromagnet is used to fix the powder feeding needle tube.

[0014] Optionally, the electrostatic powder spreading mechanism consists of an upper electrode plate and an insulating layer, the insulating layer is arranged at the bottom of the upper electrode plate, the flexible scraper is arranged on the outside of the powder spreading vehicle, a powder bed is arranged at the lower end of the molding cavity, and the insulating layer is located above the powder bed, and a high-voltage AC power supply is electrically connected between the upper electrode plate and the powder bed.

[0015] Optionally, a powder laying guide rail is provided at the lower end of one side inside the molding cavity, and the powder laying cart is connected to the powder laying guide rail in transmission, so that the powder laying cart is arranged inside the molding cavity through horizontal movement of the powder laying guide rail, and a screw guide rail is provided at the end of the powder laying cart, and the upper electrode plate and the insulating layer are both connected to the screw guide rail in transmission, so that the upper electrode plate and the insulating layer are both arranged to move up and down in the powder laying cart through the screw guide rail.

[0016] Optionally, the optical path system is arranged at the upper end of the molding cavity, and the optical path system consists of a collimator, a scanning galvanometer, and a field lens.

[0017] A method for laser additive manufacturing of a powder bed of heterogeneous materials, using a laser additive manufacturing device of a powder bed of heterogeneous materials as claimed in the claims, characterized in that it comprises the following steps:

[0018] S1: Preparation stage:

[0019] S11. Preparation of powder bed additive manufacturing system: Use 3D design software to build a model of heterogeneous material parts; add support and slice the model data, and at the same time, the computer software generates the corresponding powder suction and powder drop paths according to the slice information and imports them into the powder bed additive manufacturing system; add the main material powder and the forming substrate into the powder cylinder and the forming cylinder respectively, level the forming substrate, and complete the preparation of the powder bed additive manufacturing system;

[0020] S12, preparation of fixed-point powder suction ultrasonic powder feeding system: calculate the amount of heterogeneous materials to be loaded into each powder feeding needle tube, and vertically place each powder feeding needle tube on the needle tube rack and inside the ultrasonic vibrator. First, the powder feeding needle tube inside the ultrasonic vibrator is a large-caliber needle tube, and then the push-pull electromagnet is energized to clamp the powder feeding needle tube; the screw slide position returns to zero; the coordinates of the three-axis slide system return to zero, and check whether the ultrasonic generator and the vacuum powder suction machine can operate normally;

[0021] S13, Preparation of electrostatic powder spreading system: Return the powder spreading vehicle and the lead screw guide rail to zero position, and connect the lines between the electrodes;

[0022] S2: Powdering stage:

[0023] S21, the powder bed additive manufacturing system works and executes the slicing program. When printing of heterogeneous materials is required, after the flexible scraper spreads a layer of main material powder in the powder tank, the motor shaft on the side of the powder spreading vehicle drives the flexible scraper to rotate to an idle position vertically upward;

[0024] S22, the fixed-point powder suction and ultrasonic powder feeding system works: first, the vacuum powder suction machine is started, and the three-axis slide system drives the powder suction tube to move along the predetermined path program to suck powder, and a layer of powder is sucked from the area where the material needs to be replaced; then the ultrasonic vibrator moves to the starting point of the inner area where the powder has been sucked away under the driving action of the three-axis slide, and the ultrasonic generator is started. Subsequently, the ultrasonic vibrator moves along the specified path, and a coarse-caliber powder feeding needle tube is used to accurately drop powder to fill the non-edge area where the powder has been sucked away. After the powder dropping is completed, the ultrasonic generator is turned off, and the ultrasonic vibrator moves to the empty needle tube slot on the side of the needle tube rack;

[0025] S23, needle tube removal; first, the double-rod cylinder pushes out the inner-supporting clamping claw, and then the screw slider moves down, so that the claw head of the inner-supporting clamping claw extends into the interior of the powder delivery needle tube in the ultrasonic vibrator, then the inner-supporting clamping claw is started, the push-pull electromagnet is powered off, the screw slider moves up, the double-rod cylinder contracts, the screw slider moves down, and finally the inner-supporting clamping claw is closed, and the screw slide returns to zero, completing the automatic replacement of the coarse-caliber powder delivery needle tube;

[0026] S24, replace the fine-caliber powder delivery needle tube, and assemble the fine-caliber powder delivery needle tube according to the reverse process of S23; after the needle tube is automatically replaced, the ultrasonic vibrator moves to the starting point of the edge area where the powder has been sucked away, the ultrasonic generator is started, and the fine-caliber powder delivery needle tube accurately drops powder to fill the edge area where the powder has been sucked away. After the powder dropping is completed, the ultrasonic generator is turned off; the three-dimensional coordinates of the three-axis slide are reset to zero;

[0027] S25. Working of the electrostatic powder spreading system: first, turn on the high-voltage AC power supply, and an AC electric field with rapidly alternating polarity will be formed between the upper electrode plate and the powder bed; start the powder spreading vehicle and move it along the direction of the powder spreading guide rail. At the same time, the lead screw guide rail drives the insulating layer and the upper electrode plate to move vertically, and adjusts the electric field strength between the upper electrode plate and the powder bed. When the upper electrode plate passes through the forming cylinder and is located above the powder material, the powder oscillates up and down due to the AC electric field force, thereby spreading the powder.

[0028] Optionally, in S25, the electric field strength E is set to a range of 200-2000 V / mm, the electric field strength E is adjusted by driving the upper electrode plate through the screw guide rail, and the electric field strength E satisfies E=U / d;

[0029] Among them, U is the AC voltage applied by the high-voltage AC power supply, E is the electric field strength between the upper electrode plate and the upper surface of the powder in the forming cylinder, and d is the distance between the upper electrode plate and the upper surface of the powder in the forming cylinder.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention adopts a heterogeneous material powder spreading method of ultrasonic powder feeding + electrostatic powder spreading in the metal additive manufacturing process to achieve precise pre-setting of heterogeneous powder materials on the substrate. This powder spreading method can achieve one-time powder spreading of each layer in heterogeneous material additive manufacturing, without the need for segmented powder spreading and laser irradiation printing of each layer of traditional heterogeneous materials, avoiding the problems of material waste and uneven distribution that may occur in traditional methods, thereby improving material utilization and manufacturing efficiency.

[0032] 2. The present invention combines a scraper, an electrostatic powder spreading device, and a powder spreading vehicle into one, which reduces the possibility of hardware interference between various systems, provides a large amount of free space for the molding cavity, and further enhances the flexibility and applicability of the equipment, which is conducive to reducing the conversion and waiting time between equipment and improving production efficiency.

[0033] 3. In the process of ultrasonic powder feeding, the present invention can realize automatic replacement of powder feeding needles without manual intervention, which greatly improves work efficiency. At the same time, a coarse-caliber powder feeding needle is used to feed powder inside the contour of heterogeneous materials, and a fine-caliber powder feeding needle is used to feed powder at the edge of the contour of heterogeneous materials. The powder spreading quality at the connection of heterogeneous materials is further improved without losing the powder spreading efficiency, and the final heterogeneous material interface connection effect is indirectly enhanced.

[0034] 4. Compared with the prior art based on scraper and ultrasonic powder feeding, the present invention adopts the powder leveling method of electrostatic powder spreading after ultrasonic powder feeding, which greatly improves the problem of uneven thickness of heterogeneous material interface layer caused by ultrasonic powder feeding. The electrostatic powder spreading system can adjust the electric field strength according to the different material properties, further enhancing the powder spreading effect. At the same time, since electrostatic powder spreading effectively reduces the powder mixing phenomenon caused by traditional scraper powder spreading, the consistency and reliability of the quality of heterogeneous material additive manufacturing is guaranteed, which provides a new composite powder spreading method for heterogeneous material additive manufacturing.

[0035] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of a heterogeneous material powder bed laser additive manufacturing device provided by the present invention;

[0037] Figure 2 It is a schematic diagram of the powder suction tube provided by the present invention for regional fixed-point powder suction;

[0038] Figure 3 It is a schematic diagram of the ultrasonic powder feeding process provided by the present invention;

[0039] Figure 4 It is a schematic diagram of the electrostatic powder spreading process provided by the present invention;

[0040] Figure 5 It is a schematic diagram of the bulge at the interface of heterogeneous materials and the uneven surface of powder after ultrasonic powder removal provided by the present invention;

[0041] Figure 6 This is a schematic diagram of the effect of electrostatic powder leveling provided by the present invention;

[0042] Figure 7 It is a schematic diagram of the thick-bore powder delivery needle tube provided by the present invention filling the non-edge area where the powder has been sucked out, and the thin-bore powder delivery needle tube filling the edge area where the powder has been sucked out;

[0043] Figure 8 It is a schematic diagram of the internal structure of the flexible scraper and the electrostatic powder spreading system provided by the present invention;

[0044] Fig. 9 It is a schematic diagram of the structure of the ultrasonic vibrator and the powder suction tube provided by the present invention;

[0045] Fig.10 It is a structural schematic diagram of the automatic tube changing device provided by the present invention;

[0046] Fig.11 It is a schematic flow chart of the heterogeneous material powder bed laser additive manufacturing method provided by the present invention.

[0047] In the figure: 1. optical system; 2. molding chamber; 3. powder recovery cylinder; 4. molding cylinder; 5. powder cylinder; 6. three-axis slide system; 7. ultrasonic vibrator; 8. powder suction tube; 9. powder spreading guide rail; 10. electromagnet; 11. screw slide; 12. double-rod cylinder; 13. internal support jaws; 14. powder delivery needle tube; 15. powder spreading car; 16. flexible scraper; 17. main powder material A; 18. powder material B; 19. substrate; 20. high-voltage AC power supply; 21. powder bed; 22. upper electrode plate; 23. insulating layer; 24. screw guide rail; 25. needle tube rack; 26. non-edge area where powder has been sucked out; 27. edge area where powder has been sucked out; 28. coarse-caliber powder delivery needle tube A; 29. ​​fine-caliber powder delivery needle tube A; 30. coarse-caliber powder delivery needle tube B; 31. fine-caliber powder delivery needle tube B. DETAILED DESCRIPTION

[0048] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings.

[0049] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0050] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0051] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0052] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0053] The structure of the present invention is described in detail below in conjunction with the accompanying drawings.

[0054] like Figures 1 to 11 As shown, an embodiment of the present invention provides a heterogeneous material powder bed laser additive manufacturing device, comprising: a fixed-point powder suction and ultrasonic powder feeding system, an electrostatic powder spreading system and a powder bed additive manufacturing molding system, wherein the fixed-point powder suction and ultrasonic powder feeding system and the electrostatic powder spreading system are both arranged in the powder bed additive manufacturing molding system;

[0055] The powder bed additive manufacturing molding system comprises an optical path system 1, a molding cavity 2, a molding cylinder 4, a powder cylinder 5 and a flexible scraper 16, wherein the powder cylinder 5 is arranged at the bottom of the molding cavity 2, and the powder cylinder 5 is communicated with the inside of the molding cavity 2, the molding cylinder 4 is arranged at the bottom of the molding cavity 2, and the molding cylinder 4 is communicated with the inside of the molding cavity 2, and the flexible scraper 16 is arranged at one end of the bottom of the molding cavity 2;

[0056] like Figures 1 to 9 As shown, the flexible scraper 16 mentioned above can spread the powder in the powder cylinder 5 onto the forming cylinder 4.

[0057] The fixed-point powder suction ultrasonic powder feeding system comprises an ultrasonic vibrator 7, multiple groups of powder feeding needle tubes 14, a powder suction tube 8 and a needle tube rack 25, wherein the powder feeding needle tubes 14 are hung on the needle tube rack 25, and the needle tube rack 25 is arranged inside the molding cavity 2, wherein one group of powder feeding needle tubes 14 is detachably arranged inside the ultrasonic vibrator 7;

[0058] The electrostatic powder spreading system includes an electrostatic powder spreading mechanism and a powder spreading vehicle 15, wherein the powder spreading vehicle 15 is horizontally movable and arranged inside the molding cavity 2, and the electrostatic powder spreading mechanism is arranged at the bottom of the powder spreading vehicle 15, and the electrostatic powder spreading mechanism is located above the powder cylinder 5 and the powder recovery cylinder 3;

[0059] Further, a screw slide 11 is provided on one side of the molding cavity 2, and a double-rod cylinder 12 is connected to the molding cavity 2 through the screw slide 11 for lifting, and an inner-supporting clamp 13 is provided on the movable end of the double-rod cylinder 12. The needle tube rack 25 is located at the bottom of the screw slide 11, and a placement hole for placing the powder feeding needle tube 14 is opened on the needle tube rack 25, and the inner-supporting clamp 13 is arranged vertically corresponding to the placement hole; the powder feeding needle tube 14 is composed of a coarse-caliber powder feeding needle tube A28, a fine-caliber powder feeding needle tube A29, a coarse-caliber powder feeding needle tube B30 and a fine-caliber powder feeding needle tube B31, and the coarse-caliber powder feeding needle tube A28, the fine-caliber powder feeding needle tube A29, the coarse-caliber powder feeding needle tube B30 and the fine-caliber powder feeding needle tube B31 are all hung on the needle tube rack 25;

[0060] like Figures 1 to 9 As shown, through the mutual cooperation design of the double-rod cylinder 12, the internal support jaws 13 and the needle tube rack 25, during the powder spreading stage, the powder feeding needle tube 14 in the ultrasonic vibrator 7 can be replaced at any time through the internal support jaws 13 and the powder feeding needle tube 14 on the needle tube rack 25. The powder feeding needle tube 14 on the needle tube rack 25 is prepared with fine-caliber powder feeding needle tubes, as well as coarse-caliber and fine-caliber powder feeding needle tubes filled with another material, so that the powder feeding needle tube can be automatically replaced without manual intervention, effectively improving work efficiency.

[0061] It should be noted that by using coarse and fine diameter powder feeding syringes made of different materials, powder can be delivered inside the contour of heterogeneous materials, and fine diameter powder feeding syringes can be used to deliver powder to the edge of the contour of heterogeneous materials. This method further improves the powder spreading quality at the joints of heterogeneous materials without losing the powder spreading efficiency, and indirectly enhances the final heterogeneous material interface connection effect.

[0062] Furthermore, the ultrasonic vibrator 7 is composed of a front cover plate, a rear cover plate, a piezoelectric ceramic sheet, an electrode sheet and a hollow bolt, and the powder feeding needle tube 14 is detachably arranged in the ultrasonic vibrator 7;

[0063] It should be noted that the ultrasonic vibrator 7 mentioned above needs to be connected to an external ultrasonic generator, and the powder suction tube 8 needs to be connected to an external vacuum powder suction machine. When printing reaches the corresponding stage, the computer sends a signal to control the on and off of the two.

[0064] Furthermore, a three-axis slide system 6 is provided at the upper end of one side inside the molding cavity 2, and the ultrasonic vibrator 7 is transmission-connected to the three-axis slide system 6, so that the ultrasonic vibrator 7 is movably arranged inside the molding cavity 2 through the three-axis slide system 6, and the powder suction tube 8 is arranged between the ultrasonic vibrator 7 and the three-axis slide system 6, and a push-pull electromagnet 10 is provided at the transmission end of the three-axis slide system 6, and the push-pull electromagnet 10 is arranged close to the ultrasonic vibrator 7, and the push-pull electromagnet 10 is used to fix the powder feeding needle tube 14;

[0065] like Figures 1 to 9As shown, the three-dimensional coordinates of the three-axis slide system 6 mentioned above are changed by the control signal of the corresponding powder suction and powder dropping path transmitted by the controller. The powder suction and powder dropping path is generated by the software according to the three-dimensional model calculation, and the effective range must at least include the entire area of ​​the forming cylinder, so that the ultrasonic vibrator 7 can be used to drive the powder feeding needle tube 14 to move to any position, thereby realizing the powder dropping work at any position.

[0066] Furthermore, the electrostatic powder spreading mechanism is composed of an upper electrode plate 22 and an insulating layer 23, wherein the insulating layer 23 is arranged at the bottom of the upper electrode plate 22, the flexible scraper 16 is arranged outside the powder spreading vehicle 15, a powder bed 21 is arranged at the lower end of the molding cavity 2, and the insulating layer 23 is located above the powder bed 21, and a high-voltage AC power supply 20 is electrically connected between the upper electrode plate 22 and the powder bed 21;

[0067] like Figures 1 to 9 As shown, through the design of the insulating layer 23 , the function of the insulating layer 23 is to prevent an arc from being formed between the upper electrode plate 22 and the powder bed 21 .

[0068] It should be noted that a high-voltage AC power supply 20 needs to be connected between the upper electrode plate 22 and the powder bed 21 platform to provide a sufficiently large electric field strength to vibrate and flatten the powder. The lower electrode is composed of the powder bed 21 and the powder, and both need to have a certain conductivity to ensure the normal flow of current in the lower electrode.

[0069] Secondly, it is worth mentioning that the powder bed 21 needs to be grounded to prevent the powder in the molding cylinder 4 from being affected by other electric forces other than the high-voltage AC electric field force and to reduce the disturbing effect of the high-voltage AC on surrounding sensitive equipment and devices.

[0070] Furthermore, a powder laying guide rail 9 is provided at the lower end of one side inside the molding cavity 2, and the powder laying cart 15 is transmission-connected to the powder laying guide rail 9, so that the powder laying cart 15 is horizontally moved inside the molding cavity 2 through the powder laying guide rail 9, and a screw guide rail 24 is provided at the end of the powder laying cart 15, and the upper electrode plate 22 and the insulating layer 23 are both transmission-connected to the screw guide rail 24, so that the upper electrode plate 22 and the insulating layer 23 are both lifted and lowered in the powder laying cart 15 through the screw guide rail 24;

[0071] like Figures 1 to 9 As shown, through the design of transmission connection between the powder spreading vehicle 15 and the powder spreading guide rail 9, the powder spreading vehicle 15 moves horizontally, so that the movement coverage range of the powder spreading vehicle 15 at least includes the powder cylinder 5 to the powder recovery cylinder 3, thereby effectively increasing the powder spreading area.

[0072] Furthermore, the optical path system 1 is arranged at the upper end of the molding cavity 2, and the optical path system 1 is composed of a collimator, a scanning galvanometer, and a field lens;

[0073] like Figures 1 to 9As shown, the optical path system 1 is designed to consist of a collimator, a scanning galvanometer, and a field lens, so that the laser scanning range can cover the entire forming cylinder 4, so that the laser heats and melts the metal powder in the designated area through the scanning galvanometer, the field lens, etc. to form a cladding layer, and then the substrate 19 descends one layer, and the system re-spreads powder, and the above steps are repeated until the printing is completed.

[0074] The embodiment of the present invention further provides a method for laser additive manufacturing of a heterogeneous material powder bed, which uses the above-mentioned laser additive manufacturing device for a heterogeneous material powder bed, and comprises the following steps:

[0075] S1. Preparation stage:

[0076] S11, Preparation of powder bed additive manufacturing system: Use 3D design software to establish a model of heterogeneous material parts; add support and slice the model data, and at the same time, the computer software generates corresponding powder suction and powder drop paths according to the slice information and imports them into the powder bed additive manufacturing system; add the main material powder and the forming substrate 19 into the powder cylinder 5 and the forming cylinder 4 respectively, level the forming substrate 19, and complete the preparation of the powder bed additive manufacturing system;

[0077] S12, preparation of fixed-point powder suction ultrasonic powder feeding system: calculate the amount of heterogeneous materials to be loaded into each powder feeding needle tube 14, and vertically place each powder feeding needle tube 14 on the needle tube rack 25 and inside the ultrasonic vibrator 7. First, the powder feeding needle tube 14 inside the ultrasonic vibrator 7 selects a large-caliber needle tube, and then the push-pull electromagnet 10 is energized to clamp the powder feeding needle tube 14; the position of the screw slide 11 returns to zero; the coordinates of the three-axis slide system 6 return to zero, and check whether the ultrasonic generator and the vacuum powder suction machine can operate normally;

[0078] S13, preparation of electrostatic powder spreading system: return the powder spreading vehicle 15 and the lead screw guide rail 24 to zero position, and connect the lines between the electrodes;

[0079] S2: Powdering stage:

[0080] S21. Operation of the powder bed additive manufacturing system: The powder bed additive manufacturing system performs additive manufacturing printing of parts layer by layer according to the slicing program; when the printing process does not require printing of heterogeneous materials, the motor shaft on the side of the powder spreading vehicle 15 drives the flexible scraper 16 to rotate to a vertically downward working position for printing and forming; when the printing process requires printing of heterogeneous materials, after the flexible scraper 16 spreads a layer of main material powder in the powder cylinder 5, the motor shaft on the side of the powder spreading vehicle 15 drives the flexible scraper 16 to rotate to a vertically upward idle position, and the rest of the powder spreading stage work is carried out according to the following steps;

[0081] S22, the fixed-point powder suction and ultrasonic powder feeding system works: first, the vacuum powder suction machine is started, and the three-axis slide system 6 drives the powder suction tube 8 to move along the predetermined path program to suck powder, and a layer of powder is sucked off the area where the material needs to be replaced. Here, the moving speed of the powder suction tube 8 and the negative pressure of the vacuum powder suction machine should be set in advance by the experiment to ensure that the powder suction tube 8 only accurately sucks off a layer of powder in a single action; then the ultrasonic vibrator 7 is driven by the three-axis slide to move to the starting point of the internal area where the powder has been sucked off, the ultrasonic generator is started, and then the ultrasonic vibrator 7 moves along the specified path. , use the coarse-caliber powder delivery needle to accurately drop powder to fill the non-edge area 26 where the powder has been sucked out. After the powder dropping is completed, the ultrasonic generator is turned off, and the ultrasonic vibrator 7 moves to the empty needle tube slot on the side of the needle tube rack 25; after the needle tube is automatically replaced, the ultrasonic vibrator 7 moves to the starting point of the edge area 27 where the powder has been sucked out, the ultrasonic generator is started, and the fine-caliber powder delivery needle accurately drops powder to fill the edge area 27 where the powder has been sucked out. After the powder dropping is completed, the ultrasonic generator is turned off; the three-dimensional coordinates of the three-axis slide are reset to zero to avoid interference and collision between the three-axis slide and the powder spreading vehicle 15 in S;

[0082] S23, the needle tube is removed; first, the double-rod cylinder (12) pushes out the inner-supporting clamp (13), and then the screw slide moves downward, so that the claw head of the inner-supporting clamp (13) extends into the interior of the powder delivery needle tube (14) in the ultrasonic vibrator (7), then the inner-supporting clamp (13) is started, the push-pull electromagnet (10) is powered off, the screw slide moves upward, the double-rod cylinder (12) contracts, and the screw slide moves downward. Finally, the inner-supporting clamp (13) is closed, and the screw slide (11) returns to zero, completing the automatic replacement of the coarse-caliber powder delivery needle tube.

[0083] S24, replace the fine-caliber powder delivery needle tube, and assemble the fine-caliber powder delivery needle tube according to the reverse process of S23; after the needle tube is automatically replaced, the ultrasonic vibrator (7) moves to the starting point of the edge area (27) where the powder has been sucked out, the ultrasonic generator is started, and the fine-caliber powder delivery needle tube accurately drops powder to fill the edge area (27) where the powder has been sucked out. After the powder dropping is completed, the ultrasonic generator is turned off; the three-dimensional coordinates of the three-axis slide table are reset to zero;

[0084] S25, the electrostatic powder spreading system works: first, the high-voltage AC power supply 20 is turned on, and an AC electric field with rapidly alternating polarity will be formed between the upper electrode plate 22 and the powder bed 21; because in the step, the powder dropping of the ultrasonic vibrator 7 is often difficult to control the powder thickness at the junction of different material areas and the starting and ending points of the ultrasonic vibrator 7 dropping powder, resulting in uneven powder surface and inconsistent layer thickness in some areas; the powder spreading vehicle 15 is started to move along the powder spreading guide rail 9, and at the same time, the screw guide rail 24 drives the insulating layer 23 and the upper electrode plate 22 to move vertically according to different material properties, and adjusts the electric field strength between the upper electrode plate 22 and the powder bed 21. When the upper electrode plate 22 passes through the forming cylinder 4 and is located above the powder material, the conductive powder oscillates up and down due to the AC electric field force; the high-concentration particle oscillation area has a tendency to move toward the low-concentration particle oscillation area, and finally achieves the effect of uniform distribution of powder particles and smooth powder spreading surface.

[0085] Specifically, Figure 5 and Figure 6 As shown, the powder material mentioned above is composed of main powder material A17 and powder material B18.

[0086] Further, assuming that the AC voltage applied by the high-voltage AC power supply 20 is U, and the electric field strength between the upper electrode plate 22 and the upper surface of the powder in the forming cylinder 4 is E, the distance d between the upper electrode plate 22 and the upper surface of the powder in the forming cylinder 4 can be determined by the following relationship:

[0087] d=U / E

[0088] In order to achieve a good electrostatic powder spreading effect, the electric field strength E should be at least 200-2000V / mm. Due to the difference in conductivity of different materials, the electrostatic powder spreading electric field strength selected for different materials is also different. In this system, the electric field strength can be adjusted in real time by the screw guide rail 24 according to the material, thereby optimizing the electrostatic powder spreading effect.

[0089] The working principle and use process of the new invention:

[0090] In the powder bed additive manufacturing process of the present invention, when it comes to the powder spreading stage, the computer determines whether each layer needs to be printed with heterogeneous materials. When the non-heterogeneous material printing layer is spread, the flexible scraper 16 is placed in the working position, and the main material powder is spread and laser irradiated to form normally; when the heterogeneous material printing layer needs to be spread, the flexible scraper 16 is rotated up and placed in the idle position after the main material powder is spread, and the motor drives the three-axis slide system 6 to move according to the established path program, driving the powder suction tube 8 to absorb powder along the specified path, and then after the coarse-caliber powder delivery needle tube fills the non-edge area 26 where the powder has been sucked out, it is automatically replaced with the fine-caliber powder delivery needle tube, and then the powder is delivered to the edge area 27 where the powder has been sucked out. Finally, the electrostatic powder spreading device is started and moves back and forth, and at the same time, the computer adjusts the electric field strength in real time according to the powder type to flatten the powder. The present invention abandons the traditional scraper powder spreading device and adopts a heterogeneous material powder spreading method of ultrasonic powder dropping + electrostatic powder spreading, so that when the powder bed 21 is printing heterogeneous material components, the interlayer thickness is more uniform, and the interface bonding between different materials is tighter. At the same time, it effectively avoids the powder mixing phenomenon caused by traditional scraper powder spreading, and improves the quality of heterogeneous material prints. In addition, the present invention realizes the automatic replacement of the powder feeding needle tube 14 and the variable adjustment of the electric field strength of the electrostatic powder spreading, which improves the processing efficiency and ensures a higher powder spreading accuracy. Therefore, the present invention realizes a new heterogeneous material powder spreading that combines ultrasonic powder dropping with electrostatic powder spreading, which is of great significance for achieving the upgrade of the printing effect and performance optimization of heterogeneous material components.

[0091] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0092] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A laser additive manufacturing device for a powder bed of heterogeneous materials, characterized in that: include: A fixed-point powder suction and ultrasonic powder feeding system, an electrostatic powder spreading system and a powder bed additive manufacturing molding system, wherein the fixed-point powder suction and ultrasonic powder feeding system and the electrostatic powder spreading system are both arranged in the powder bed additive manufacturing molding system; The powder bed additive manufacturing molding system comprises an optical path system (1), a molding cavity (2), a molding cylinder (4), a powder cylinder (5) and a flexible scraper (16), wherein the powder cylinder (5) is arranged at the bottom of the molding cavity (2), and the powder cylinder (5) is communicated with the interior of the molding cavity (2), the molding cylinder (4) is arranged at the bottom of the molding cavity (2), and the molding cylinder (4) is communicated with the interior of the molding cavity (2), and the flexible scraper (16) is arranged at one end of the bottom of the molding cavity (2); The fixed-point powder suction ultrasonic powder feeding system comprises an ultrasonic vibrator (7), a plurality of groups of powder feeding needle tubes (14), a powder suction tube (8) and a needle tube rack (25), wherein the powder feeding needle tubes (14) are hung on the needle tube rack (25), and the needle tube rack (25) is arranged inside the molding cavity (2), wherein one group of powder feeding needle tubes (14) is detachably arranged inside the ultrasonic vibrator (7); The electrostatic powder spreading system comprises an electrostatic powder spreading mechanism and a powder spreading vehicle (15), wherein the powder spreading vehicle (15) is horizontally movable and arranged inside the molding cavity (2), and the electrostatic powder spreading mechanism is arranged at the bottom of the powder spreading vehicle (15), and the electrostatic powder spreading mechanism is located above the powder cylinder (5) and the powder recovery cylinder (3).

2. A heterogeneous material powder bed laser additive manufacturing device according to claim 1, characterized in that: A screw slide (11) is provided on one side of the interior of the molding cavity (2), and a double-rod cylinder (12) is connected to the interior of the molding cavity (2) via the screw slide (11) for lifting and lowering. An internally supported clamping claw (13) is provided at the movable end of the double-rod cylinder (12). The needle tube rack (25) is located at the bottom of the screw slide (11), and a placement hole for placing a powder feeding needle tube (14) is provided on the needle tube rack (25), and the internally supported clamping claw (13) is arranged vertically corresponding to the placement hole.

3. The heterogeneous material powder bed laser additive manufacturing device according to claim 2, characterized in that: The powder feeding needle tube (14) is composed of a large-caliber powder feeding needle tube A (28), a small-caliber powder feeding needle tube A (29), a large-caliber powder feeding needle tube B (30) and a small-caliber powder feeding needle tube B (31), and the large-caliber powder feeding needle tube A (28), the small-caliber powder feeding needle tube A (29), the large-caliber powder feeding needle tube B (30) and the small-caliber powder feeding needle tube B (31) are all hung on the needle tube rack (25).

4. The heterogeneous material powder bed laser additive manufacturing device according to claim 3, characterized in that: The ultrasonic vibrator (7) is composed of a front cover plate, a rear cover plate, a piezoelectric ceramic sheet, an electrode sheet and a hollow bolt, and the powder feeding needle tube (14) is detachably arranged in the ultrasonic vibrator (7).

5. The heterogeneous material powder bed laser additive manufacturing device according to claim 4, characterized in that: A three-axis slide system (6) is arranged at the upper end of one side inside the molding cavity (2), and the ultrasonic vibrator (7) is connected to the three-axis slide system (6) by transmission, so that the ultrasonic vibrator (7) is movably arranged inside the molding cavity (2) through the three-axis slide system (6), and the powder suction pipe (8) is arranged between the ultrasonic vibrator (7) and the three-axis slide system (6). A push-pull electromagnet (10) is arranged at the transmission end of the three-axis slide system (6), and the push-pull electromagnet (10) is arranged close to the ultrasonic vibrator (7), and the push-pull electromagnet (10) is used to fix the powder feeding needle tube (14).

6. The heterogeneous material powder bed laser additive manufacturing device according to claim 5, characterized in that: The electrostatic powder spreading mechanism consists of an upper electrode plate (22) and an insulating layer (23), wherein the insulating layer (23) is arranged at the bottom of the upper electrode plate (22), the flexible scraper (16) is arranged on the outside of the powder spreading vehicle (15), a powder bed (21) is arranged at the lower end of the interior of the molding cavity (2), and the insulating layer (23) is located above the powder bed (21), and a high-voltage AC power supply (20) is electrically connected between the upper electrode plate (22) and the powder bed (21).

7. The heterogeneous material powder bed laser additive manufacturing device according to claim 6, characterized in that: A powder laying guide rail (9) is provided at the lower end of one side inside the molding cavity (2), and the powder laying cart (15) is connected to the powder laying guide rail (9) in a transmission manner, so that the powder laying cart (15) is arranged inside the molding cavity (2) through horizontal movement of the powder laying guide rail (9), and a screw guide rail (24) is provided at the end of the powder laying cart (15), and the upper electrode plate (22) and the insulating layer (23) are both connected to the screw guide rail (24) in a transmission manner, so that the upper electrode plate (22) and the insulating layer (23) are both arranged to move up and down inside the powder laying cart (15) through the screw guide rail (24).

8. The heterogeneous material powder bed laser additive manufacturing device according to claim 7, characterized in that: The optical path system (1) is arranged at the upper end of the molding cavity (2), and the optical path system (1) is composed of a collimator, a scanning galvanometer, and a field mirror.

9. A method for laser additive manufacturing of a powder bed of heterogeneous materials, using a laser additive manufacturing device of a powder bed of heterogeneous materials according to claim 8, characterized in that: The steps include: S1: Preparation stage: S11, preparation of powder bed additive manufacturing system: using three-dimensional design software to establish a heterogeneous material part model; adding support and slicing the model data, while the computer software generates corresponding powder suction and powder drop paths according to the slicing information and imports them into the powder bed additive manufacturing system; adding the main material powder and the forming substrate (19) into the powder cylinder (5) and the forming cylinder (4) respectively, and leveling the forming substrate (19), and completing the preparation of the powder bed additive manufacturing system; S12, preparation of fixed-point powder suction ultrasonic powder feeding system: calculate the amount of heterogeneous material to be loaded into each powder feeding needle tube (14), and vertically place each powder feeding needle tube (14) on the needle tube rack (25) and inside the ultrasonic vibrator (7). First, the powder feeding needle tube (14) inside the ultrasonic vibrator (7) is selected as a large-caliber needle tube, and then the push-pull electromagnet (10) is energized to clamp the powder feeding needle tube (14); the position of the screw slide (11) is returned to zero; the coordinates of the three-axis slide system (6) are returned to zero, and the ultrasonic generator and the vacuum powder suction machine are tested to see whether they can operate normally; S13, preparation of electrostatic powder spreading system: reset the powder spreading vehicle (15) and the screw guide rail (24) to zero position, and connect the lines between the electrodes; S2: Powdering stage: S21, the powder bed additive manufacturing system is working and executing the slicing program. When printing of heterogeneous materials is required, after the flexible scraper (16) spreads a layer of main material powder in the powder tank (5), the motor shaft on the side of the powder spreading vehicle (15) drives the flexible scraper (16) to rotate to an idle position vertically upward; S22, the fixed-point powder suction and ultrasonic powder feeding system works: first, the vacuum powder suction machine is started, and the three-axis slide system (6) drives the powder suction tube (8) to move along a predetermined path program to suck powder, and remove a layer of powder from the area where the material needs to be replaced; then the ultrasonic vibrator (7) moves to the starting point of the inner area where the powder has been sucked away under the driving action of the three-axis slide, and the ultrasonic generator is started. Subsequently, the ultrasonic vibrator (7) moves along the designated path, and a coarse-caliber powder feeding needle tube is used to accurately drop powder to fill the non-edge area (26) where the powder has been sucked away. After the powder dropping is completed, the ultrasonic generator is turned off, and the ultrasonic vibrator (7) moves to the empty needle tube slot on the side of the needle tube rack (25); S23, the needle tube is removed; first, the double-rod cylinder (12) pushes out the inner-supporting clamp (13), and then the screw slide moves downward, so that the claw head of the inner-supporting clamp (13) extends into the interior of the powder delivery needle tube (14) in the ultrasonic vibrator (7), then the inner-supporting clamp (13) is started, the push-pull electromagnet (10) is powered off, the screw slide moves upward, the double-rod cylinder (12) contracts, the screw slide moves downward, and finally the inner-supporting clamp (13) is closed, and the screw slide (11) returns to zero, completing the automatic replacement of the coarse-caliber powder delivery needle tube; S24, replace the fine-caliber powder delivery needle tube, and assemble the fine-caliber powder delivery needle tube according to the reverse process of S23; after the needle tube is automatically replaced, the ultrasonic vibrator (7) moves to the starting point of the edge area (27) where the powder has been sucked out, the ultrasonic generator is started, and the fine-caliber powder delivery needle tube accurately drops powder to fill the edge area (27) where the powder has been sucked out. After the powder dropping is completed, the ultrasonic generator is turned off; the three-dimensional coordinates of the three-axis slide table are reset to zero; S25, the electrostatic powder spreading system works: first, the high-voltage AC power supply (20) is turned on, and an AC electric field with rapidly alternating polarity is formed between the upper electrode plate (22) and the powder bed (21); the powder spreading vehicle (15) is started to move along the direction of the powder spreading guide rail (9), and at the same time, the screw guide rail (24) drives the insulating layer (23) and the upper electrode plate (22) to move vertically, and the electric field strength between the upper electrode plate (22) and the powder bed (21) is adjusted. When the upper electrode plate (22) passes through the forming cylinder (4) and is located above the powder material, the powder is oscillated up and down by the AC electric field force, thereby spreading the powder.

10. The method for laser additive manufacturing of a heterogeneous material powder bed according to claim 9, characterized in that: In S25, the electric field strength E is set in the range of 200-2000 V / mm, the electric field strength E is adjusted by the upper electrode plate (22) driven by the screw guide rail (24), and the electric field strength E satisfies E=U / d; Wherein, U is the AC voltage applied by the high voltage AC power source (20), E is the electric field strength between the upper electrode plate (22) and the upper surface of the powder in the forming cylinder (4), and d is the distance between the upper electrode plate (22) and the upper surface of the powder in the forming cylinder (4).

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