CN117139646A - Device and method for assisting pulse laser sintering to inhibit splashing by pulse current - Google Patents
Device and method for assisting pulse laser sintering to inhibit splashing by pulse current Download PDFInfo
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- CN117139646A CN117139646A CN202311122947.5A CN202311122947A CN117139646A CN 117139646 A CN117139646 A CN 117139646A CN 202311122947 A CN202311122947 A CN 202311122947A CN 117139646 A CN117139646 A CN 117139646A
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/20—Direct sintering or melting
- B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/30—Process control
- B22F10/36—Process control of energy beam parameters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
- B22F12/40—Radiation means
- B22F12/41—Radiation means characterised by the type, e.g. laser or electron beam
- B22F12/43—Radiation means characterised by the type, e.g. laser or electron beam pulsed; frequency modulated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y80/00—Products made by additive manufacturing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The invention discloses a device and a method for suppressing splashing by pulse current auxiliary pulse laser sintering, which belong to the technical field of additive manufacturing and comprise a forming cavity; a forming cylinder and a powder cylinder are fixedly arranged at the bottom of the forming cavity; the powder cylinder stores metal powder; a scraping plate is arranged in the forming cavity and is used for conveying metal powder into the forming cylinder; a base plate is arranged in the forming cylinder; the substrate is electrically connected with the pulse current generator; forming parts are placed on the base plate; an optical system is also arranged in the forming cavity; the optical system and the pulse current generator are electrically connected with the control center. The Joule heating effect and the flow stress effect generated by the high-frequency pulse current can be well coupled with the pulse laser to form heat-force action, so that the processability of parts and materials is improved, the process window of pulse laser sintering is widened, and the forming quality of the parts is improved.
Description
Technical Field
The invention belongs to the technical field of additive manufacturing, and particularly relates to a device and a method for suppressing splashing by pulse current auxiliary pulse laser sintering.
Background
Additive manufacturing (Additive Manufacturing, AM) is a rapid processing and manufacturing technology for a device and a method for suppressing splashing by pulse current auxiliary pulse laser sintering, and has the advantages of short production period, high material utilization rate, direct processing and forming without a die and the like, and has been attracting attention in recent years. Direct fabrication of metal parts using additive manufacturing techniques has been extended to the fields of aerospace, medical treatment, automotive manufacturing, and the like. Additive manufacturing can be divided into a number of techniques, depending on the differences in processing materials and forming principles, including mainly light-cured forming (SLA), fused deposition Forming (FDM), electron Beam Melting (EBM), laser selective sintering (SLS), and laser selective melting (SLM) techniques. The device and the method implementation mode of the pulse current auxiliary pulse laser sintering splash suppression device are characterized in that after a modeling software is used for establishing a model, the model is sliced through special software, specific technological parameters are set, slice data and specific technology are input into operation equipment, and metal powder which is uniformly paved on a metal substrate is melted point by point, line by line and layer by adopting a high-energy density laser beam to directly manufacture functional parts, so that the device is superior to a metal workpiece with the performance of forging workpieces, and the device becomes a hot spot for domestic and foreign research in recent years.
However, in the existing laser powder bed additive manufacturing technology in the market, no matter the laser selective sintering process or the laser selective melting process, the forming is a rapid melting and solidifying process, a plurality of uncontrollable influencing factors can be generated in the processing process, such as the phenomena of spheroidization, cracking, overburning, low forming dimensional precision and the like can be generated when laser rapidly acts on the powder, and certain process defects exist. On the other hand, the splash generated under the continuous laser action can obstruct the adhesion between the melting layers, and influence the mechanical properties of the formed part. The quality stability of the molded parts of additive manufacturing is poor due to the existence of such defects, thereby limiting the development and practical application of additive manufacturing.
To address the above drawbacks, many researchers began to shape parts using pulsed lasers instead of continuous lasers. Compared with continuous laser, the pulse laser energy is convenient to control, under the condition that the laser spot diameter is unchanged, the continuous laser can only change the input energy by changing the scanning rate and the laser power, and the pulse laser can control the input of energy by parameters such as pulse peak power, pulse action time, point distance, pulse repetition frequency and the like. The time of the pulse laser action is relatively short, the heat diffusion depth of the pulse laser sintering is small, so that the heat affected zone is small, the sticky powder on the periphery of a molten pool is reduced in the laser sintering process, and finally, higher machining precision, particularly side machining precision, is achieved, and further, finer and uniform microstructures are obtained. However, because the peak power of the pulse laser is higher, plasmas are generated in the sintering process, and the recoil pressure of the plasmas can cause severe splashing, so that the phenomena of powder accumulation, uneven powder spreading and the like are caused, and the forming quality of parts is affected. How to improve such forming defects is a problem that needs to be addressed by laser powder bed additive manufacturing techniques.
Along with the discovery of the electric effect of metal and the proposal of the electric plastic effect, more and more domestic researchers start to introduce pulse current in the metal processing process to strengthen the machinability and comprehensive performance of the metal material. According to the related studies, an electric heating effect caused by a pulse current causes a current flowing through the inside of a material to interact with a resistance to generate heat, and such heat generation causes thermal softening of a metal. Meanwhile, the high-speed moving electrons can generate intermittent impact on atoms originally stationary in the material by the aid of the pulse current to assist the pulse laser sintering to inhibit splashing, so that thrust is generated by misplacement, flow stress of the material is reduced, formability of parts is improved, and therefore the pulse current has good application prospect in improving defect of the parts and enhancing strength of the parts. For example, patent CN 105855549B discloses a device and a method for suppressing splashing by pulse current assisted pulse laser sintering, which are based on a pulse laser filler wire welding system and obtain the final structure by layer-by-layer deposition with inert gas as a shielding gas. However, the method omits the defects of spheroidization and the like at the edge of a molten pool caused by insufficient wetting and spreading of the liquid phase on a substrate due to short stay time of the liquid phase and insufficient energy density of pulse laser when laser scans at a high speed, and influences the forming precision of parts. As another example, patent CN 104755197B discloses an additive manufacturing method and apparatus that uses a fiber laser to apply pulsed laser energy to a powder material on a substrate to selectively and rapidly fuse a quantity of aluminum alloy powder material disposed in a powder bed, optimizing pulsed laser sintering by selective sintering. However, the method ignores the problem that the pulse laser can generate plasma recoil force under high power to cause splashing, and the splashing problem is still not solved.
Disclosure of Invention
The invention aims to provide a device and a method for suppressing splashing by pulse current auxiliary pulse laser sintering, which are used for solving the problems, and achieving the purposes of taking pulse laser as a heat source, coupling pulse current in the sintering process, and enabling the energy absorbed by metal powder from the pulse laser to be lower than a threshold value generated by plasma under the combined action of the cooperative adjustment of the pulse laser and the pulse current, thereby reducing the vapor backflushing pressure and the plasma backflushing pressure, reducing the splashing, improving the forming precision and the forming quality of additive manufactured parts and increasing the practicability of the additive manufactured parts.
In order to achieve the above object, the present invention provides the following solutions:
a pulsed current assisted pulsed laser sintering splash suppression device comprising: forming a cavity; the bottom of the forming cavity is fixedly provided with a forming cylinder and a powder cylinder; the powder cylinder stores metal powder; a scraper is arranged in the forming cavity and is used for conveying the metal powder into the forming cylinder; a base plate is arranged in the forming cylinder; the substrate is electrically connected with the pulse current generator; the base plate is provided with a forming part;
an optical system is also arranged in the forming cavity; the optical system and the pulse current generator are electrically connected with the control center.
The optical system comprises a pulse laser, a laser galvanometer and an optical lens; the laser galvanometer and the optical lens are arranged right above the forming part; the pulse laser and the pulse current generator are electrically connected with the control center.
Lifting devices are arranged at the bottoms of the forming cylinder and the powder cylinder, and the lifting devices are electrically connected with a control center.
The oxygen content in the forming cavity is lower than 800ppm.
The metal powder is pulse laser sintered spherical powder, and is aluminum alloy powder, titanium alloy powder or nickel-based alloy powder.
The pulse laser formed by the pulse laser has the advantages of 50 mu m of spot diameter, 0-100W of power, 10-1500mm/s of scanning speed, 5-50 mu m of layer thickness, 40-100 mu m of scanning interval, adjustable frequency of 20-200KHz and 100-200ns of pulse width.
A method for pulse current assisted pulse laser sintering to suppress splatter, comprising the steps of:
layering the part model according to the characteristics of the metal powder and the properties of the part, and setting data;
adding the metal powder into the powder cylinder, and introducing inert gas into the forming chamber;
turning on the pulse current generator to preheat the substrate;
and opening the pulse laser, so that the pulse laser is coupled with the pulse current in real time, and the metal powder is combined with the formed part for forming.
And placing the metal powder in the step of layering the part model and setting data, wherein the step specifically comprises the following steps: and layering the part model by layering slicing software, and setting layered pulse laser power, powder feeding amount, scanning speed and scanning interval.
The pulse laser couples the pulse laser with the pulse current in real time, and the step of combining and forming the metal powder and the formed part specifically comprises the following steps: the frequency, pulse width and incidence time of the laser are regulated, so that the pulse laser is coupled with the pulse current in real time, and the peak pulse current is regulated in real time according to the characteristics of a molten pool to reduce the recoil pressure of the plasma.
The peak output current of the pulse laser is 380A, the maximum current frequency is 100KHz, and the maximum pulse width is 100 mu s.
Compared with the prior art, the invention has the following advantages and technical effects: 1. the pulse laser is used as a heat source, the average forming power is small, the heat affected zone is relatively small due to the small heat diffusion depth, and finally, higher processing precision and forming quality are brought, so that the pulse laser sintering has unique advantages when forming tiny complex parts.
2. The Joule heating effect and the flow stress effect generated by the high-frequency pulse current can be well coupled with the pulse laser to form heat-force action, so that the processability of parts and materials is improved, the process window of pulse laser sintering is widened, and the forming quality of the parts is improved.
3. By adjusting the peak current and the frequency of the pulse, the energy absorbed by the metal powder from the pulse laser is lower than the threshold value generated by the plasma, so that the recoil pressure of the plasma is reduced, the suppression of splashing and the sintering formation under the low-power effect are realized, and the influence of the splashing on the forming quality in the sintering process is reduced.
4. The method has the advantages that green pollution-free energy is used, the whole process is fully automatically operated, the waste of manpower is reduced, the forming efficiency is high, the self safety of a user is guaranteed, the precision of additive manufacturing and processing is improved, and the whole economy, safety, working efficiency, forming quality and practicability are high.
Drawings
For a clearer description of an embodiment of the invention or of the solutions of the prior art, the drawings that are needed in the embodiment will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art:
FIG. 1 is a schematic diagram of an apparatus for pulse current assisted pulse laser sintering to suppress splatter;
FIG. 2 is a graph of the macroscopic topography of the surface of the pulsed laser sintered part of example 1;
FIG. 3 is a graph of the surface macromorphology of a pulsed laser sintered part after introduction of a pulsed current in example 2;
wherein, 1-a control center; a 2-pulse laser; 3-laser galvanometer; 4-forming cavity; 5-an optical lens; 6-forming the part; 7-a substrate; 8-forming cylinders; 9-a pulse current generator; 10-a powder cylinder; 11-metal powder; 12-scraper.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
As shown in fig. 1, a device for suppressing splashing by pulse current auxiliary pulse laser sintering comprises: a molding cavity 4; a forming cylinder 8 and a powder cylinder 10 are fixedly arranged at the bottom of the forming cavity 4; the powder cylinder 10 stores metal powder 11; a scraping plate 12 is arranged in the forming cavity 4, and the scraping plate 12 is used for conveying metal powder 11 into the forming cylinder 8; a base plate 7 is installed in the forming cylinder 8; the substrate 7 is electrically connected with the pulse current generator 9; a forming part 6 is placed on the base plate 7;
an optical system is also arranged in the molding cavity 4; the optical system and the pulse current generator 9 are electrically connected with the control center 1.
The optical system comprises a pulse laser 2, a laser galvanometer 3 and an optical lens 5; the laser galvanometer 3 and the optical lens 5 are arranged right above the forming part 6; the pulse laser 2 and the pulse current generator 9 are electrically connected with the control center 1.
Lifting devices are arranged at the bottoms of the forming cylinder 8 and the powder cylinder 10, and are electrically connected with the control center 1.
In a preferred embodiment of the present invention, the elevating means is used to extend or retract the metal powder 11 into the cylinder.
The oxygen content in the molding cavity 4 was less than 800ppm.
The metal powder 11 is a pulsed laser sintered spherical powder, which is an aluminum alloy powder, a titanium alloy powder, or a nickel-based alloy powder.
In a preferred embodiment of the invention, the powder has a particle size of 2-10 μm, and has good flowability and high bulk density.
The pulse laser 2 has a pulse laser spot diameter of 50 μm, a power of 0-100W, a scanning speed of 10-1500mm/s, a layer thickness of 5-50 μm, a scanning interval of 40-100 μm, a frequency of 20-200KHz, and a pulse width of 100-200ns.
A method for pulse current assisted pulse laser sintering to suppress splatter, comprising the steps of:
layering the part model according to the characteristics of the metal powder and the properties of the part, and setting data;
adding metal powder into a powder cylinder, and introducing inert gas into a forming cavity;
turning on a pulse current generator to preheat a substrate;
the pulse laser is turned on to couple the pulse laser and the pulse current in real time, so that the metal powder and the formed part are combined and formed.
In a preferred scheme of the invention, the pulse current generator is turned on, and the preheating of the substrate specifically comprises the control of pulse current waveform, frequency and pulse width by an oscilloscope, so that alloy powder on the substrate has effects of electric heating, flow stress and the like in the process of laser sintering.
The metal powder is placed in the steps of layering the part model and setting data, and the method specifically comprises the following steps: and layering the part model by layering slicing software, and setting layered pulse laser power, powder feeding amount, scanning speed and scanning interval.
In a preferred embodiment of the present invention, the part model is a stl model; the inert gas is argon.
The pulse laser, make pulse laser and pulse current couple in real time, make metal powder and shaping part combine the shaping step specifically including: the frequency, pulse width and incidence time of the laser are regulated, so that the pulse laser is coupled with the pulse current in real time, and the peak pulse current is regulated in real time according to the characteristics of a molten pool to reduce the recoil pressure of the plasma.
Further, the peak pulse current is regulated in real time according to the characteristics of the molten pool to reduce the plasma recoil pressure so as to realize the suppression of powder splashing.
Further, the last splash is mainlyIs generated by the plasma recoil pressure, and the plasma recoil pressure is known by deductionIn which I m Is pulse peak current, T is pulse current frequency, T i The pulse current is the pulse width of the current, and the introduction of the pulse current can effectively reduce the recoil pressure of the plasma so as to inhibit splashing; in addition, the pulse current and the pulse laser are coupled to increase the width of a molten pool, increase the contact area of liquid metal and a substrate, reduce the occurrence of splashing while increasing the adhesion, and improve the mechanical property and the forming precision of parts.
The peak output current of the pulse laser is 380A, the maximum current frequency is 100KHz, and the maximum pulse width is 100 mu s.
In a preferred embodiment of the invention, the real-time coupling of the electric pulse and the laser melting is achieved by adjusting the frequency, the pulse width and the incident time of the pulse current and the pulse laser, thereby improving the shaping performance of the pulse laser sintering.
In a preferred embodiment of the present invention, as shown in fig. 1, the pulse current auxiliary pulse laser sintering splash suppression device specifically operates in such a manner that a powder cylinder 10 is located at the left side of a forming cylinder 8 for temporarily storing metal powder 11, and a base plate 7 is fixed above the forming cylinder 8 by screws; the doctor blade 12 is always located on the leftmost side of the forming cavity 4 before each laying. The control center 1 controls the powder cylinder 10 to rise by 20 μm and simultaneously controls the molding cylinder 8 to descend by 20 μm. Then the scraper 12 moves from right to left to the rightmost side at a constant speed, and the metal powder higher than the plane of the powder cylinder 10 is uniformly spread on the surface of the substrate 7. Finally, the scraper 12 returns to the leftmost end to finish one powder spreading cycle, and waits for the pulse laser sintering of the layer to finish the next powder spreading.
The laser galvanometer 3 and the optical lens 5 are integrated above the forming cylinder 8, the pulsed laser is excited by the pulsed laser 2, a desired light beam is formed through the optical mirror of the laser galvanometer 3, and finally the light beam focuses the metal powder 11 in the surface of the pulsed laser sintering substrate 7 through the optical lens 5.
In a preferred scheme of the invention, the device also comprises a gas circulation purifying system, a deoxidizing procedure is carried out before forming is started, a sensor is arranged in the forming cavity 4, the oxygen content is displayed on a panel of the control center 1 in real time, the forming cavity 4 is pumped into a low-pressure state by a vacuumizing device, and then helium is filled into the forming cavity 4 by an air supply device; the vacuum-pumping device is continuously started, and the processing process can not be performed until the oxygen content in the forming cavity 4 is lower than 800ppm. The gas circulation and purification system is continuously operated during the process in order to maintain a low oxygen environment within the forming chamber 4.
Embodiment one:
step one: before the experiment, the metal powder 11 is put into a vacuum drying oven for drying and dewatering pretreatment so as to reduce powder agglomeration and prevent the impact on the sintering quality of the pulse laser. The vacuum degree in the vacuum drying box is set to be 0.08MPa so as to prevent powder from burning and oxidizing, the drying temperature is 80-100 ℃, and the drying time is 2-3 hours.
Step two: according to the characteristics of the metal powder 11 and the properties of the parts, a three-dimensional model of the part to be machined is established, pretreatment is carried out on the CAD three-dimensional model of the part to be machined, including slicing, repairing, supporting and arranging on a forming cylinder 8, and the technological parameters of pulse laser sintering are set; specifically, the pulse laser pulse frequency is set to be 50KHz, the pulse width is set to be 100ns, the power is set to be 50W, the scanning speed is set to be 400mm/s, the layer thickness is set to be 20 mu m, the scanning interval is set to be 60 mu m, and stl files are led into the control center 1 after the completion.
Step three: the dried and cooled metal powder 11 is fed into a powder cylinder 10 and the powder is laid flat. Before forming, firstly, opening a gas circulation purification system to perform a deoxidization procedure, wherein a sensor is arranged in the forming cavity 4, the oxygen content is displayed on a computer panel in real time, the inside of the forming cavity 4 is pumped into a low-pressure state by a vacuumizing device, and then helium is filled into the forming cavity 4 by an air supply device; the cycle is repeated until the oxygen content in the forming chamber 4 is below 800ppm.
Step four: the powder cylinder 10 is controlled to rise by 20 mu m, the forming cylinder 8 is simultaneously lowered by 20 mu m, then the scraper 7 uniformly moves from left to right to the rightmost side of the forming cavity 4, the metal powder higher than the plane of the powder cylinder 10 is uniformly paved into the forming cylinder 8, finally the scraper 12 returns to the leftmost end to finish one-time powder paving, the control center 1 controls the pulse laser 2 to be turned on, the pulse laser sintering process is carried out in inert atmosphere, the powder paving is carried out once after each layer is formed, and the solid parts 6 are printed layer by layer on the substrate 7 according to set process parameters in such a cycle.
Step five: after the parts are printed, the pulse laser is turned off, the substrate 7 is taken out, and finally the parts are taken down by wire cutting. The obtained microscopic morphology of the surface of the pulse laser sintered part is shown in fig. 2.
Embodiment two:
the method and the device used are the same as those in the embodiment 1, the pulse current generator 9 is controlled to be turned on just before the pulse laser sintering, the pulse current with the average value of 60A, the frequency of 50KHz and the pulse width of 250ns is introduced, and the incident time of the pulse laser is regulated, so that the pulse current and the pulse laser are coupled in real time to form a part. The resulting surface microtopography of the shaped part is shown in fig. 3.
As can be seen by comparing fig. 2 and 3, the metal droplets and the powder are bonded to form a spherical surface morphology due to the generation of splash, so that the surface of the part is very rough, and the forming quality of the part is affected. When pulse current is introduced, the recoil pressure of the plasma is effectively reduced, and the splashing phenomenon is restrained, so that the influence of splashing on the surface quality of the part is reduced, and the forming quality of the part is improved obviously.
In summary, the method and the device adopt pulse laser as a heat source by the pulse current compound enhanced pulse laser sintering process, and have small heat affected zone and high forming precision; residual compressive stress generated in the sintering process is coupled with pulse current, so that the defects of low strength, spheroidization and the like of the additive manufactured part are overcome to a great extent; meanwhile, the method well inhibits the generation of splash in the sintering process, reduces the influence of splash on the forming quality, and ensures that the forming precision of the part is higher.
In the description of the present invention, it should be understood that the terms "longitudinal," "transverse," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present invention, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.
Claims (10)
1. A pulse current assisted pulse laser sintering splash suppression device, comprising: a molding cavity (4); a forming cylinder (8) and a powder cylinder (10) are fixedly arranged at the bottom of the forming cavity (4); the powder cylinder (10) stores metal powder (11); a scraping plate (12) is arranged in the forming cavity (4), and the scraping plate (12) is used for conveying the metal powder (11) into the forming cylinder (8); a base plate (7) is arranged in the forming cylinder (8); the substrate (7) is electrically connected with the pulse current generator (9); a forming part (6) is placed on the base plate (7);
an optical system is also arranged in the forming cavity (4); the optical system and the pulse current generator (9) are electrically connected with the control center (1).
2. The pulse current assisted pulse laser sintering splash suppression device according to claim 1, wherein: the optical system comprises a pulse laser (2), a laser galvanometer (3) and an optical lens (5); the laser galvanometer (3) and the optical lens (5) are arranged right above the forming part (6); the pulse laser (2) and the pulse current generator (9) are electrically connected with the control center (1).
3. The pulse current assisted pulse laser sintering splash suppression device according to claim 1, wherein: lifting devices are arranged at the bottoms of the forming cylinder (8) and the powder cylinder (10), and the lifting devices are electrically connected with the control center (1).
4. The pulse current assisted pulse laser sintering splash suppression device according to claim 1, wherein: the oxygen content in the forming cavity (4) is lower than 800ppm.
5. The pulse current assisted pulse laser sintering splash suppression device according to claim 1, wherein: the metal powder (11) is pulse laser sintering spherical powder, and the metal powder (11) is aluminum alloy powder, titanium alloy powder or nickel-based alloy powder.
6. The pulse current assisted pulse laser sintering splash suppression device according to claim 1, wherein: the pulse laser (2) has the advantages that the diameter of a pulse laser spot formed by the pulse laser is 50 mu m, the power is 0-100W, the scanning speed is 10-1500mm/s, the layer thickness is 5-50 mu m, the scanning interval is 40-100 mu m, the frequency is 20-200KHz and the pulse width is 100-200ns.
7. A method of pulse current assisted pulse laser sintering splash suppression comprising the apparatus of any of claims 1-6, characterized by the steps of:
layering the part model according to the characteristics of the metal powder and the properties of the part, and setting data;
adding the metal powder into the powder cylinder, and introducing inert gas into the forming chamber;
turning on the pulse current generator to preheat the substrate;
and opening the pulse laser, so that the pulse laser is coupled with the pulse current in real time, and the metal powder is combined with the formed part for forming.
8. The method for suppressing splatter by pulse current assisted pulse laser sintering according to claim 7, wherein: and placing the metal powder in the step of layering the part model and setting data, wherein the step specifically comprises the following steps: and layering the part model by layering slicing software, and setting layered pulse laser power, powder feeding amount, scanning speed and scanning interval.
9. The method for suppressing splatter by pulse current assisted pulse laser sintering according to claim 7, wherein: the pulse laser couples the pulse laser with the pulse current in real time, and the step of combining and forming the metal powder and the formed part specifically comprises the following steps: the frequency, pulse width and incidence time of the laser are regulated, so that the pulse laser is coupled with the pulse current in real time, and the peak pulse current is regulated in real time according to the characteristics of a molten pool to reduce the recoil pressure of the plasma.
10. The method for suppressing splatter by pulse current assisted pulse laser sintering according to claim 9, wherein: the peak output current of the pulse laser is 380A, the maximum current frequency is 100KHz, and the maximum pulse width is 100 mu s.
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Cited By (1)
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