A metal 3D printing system and method for mitigating metal spatter

Abstract

The application relates to a metal 3D printing system and printing method for reducing metal splashing, and belongs to the technical field of 3D printing. The system comprises a laser, an imaging module arranged on the light path of the laser beam emitted by the laser, a vibrating mirror module and a printing work surface. An optical path shaping module is arranged between the laser and the vibrating mirror unit. The optical path shaping module comprises an angle adjusting ring, a first collimating lens, a first Powell prism and a second collimating lens which are sequentially arranged in the light path direction and are installed in the angle adjusting ring. The first Powell prism is eccentric, the laser beam is diffused in one direction, and the energy of the diffused laser beam is gradually weakened from one end to the other end of the diffusion direction. During printing, the direction of the diffused laser beam of the first Powell prism is adjusted by the angle adjusting ring, so that the end with the same scanning direction and higher energy is located at the front end of the scanning direction, the absorption power of the liquid metal to the laser is reduced, and the splashing of the metal liquid drops is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of 3D printers, and particularly relates to a metal 3D printing system and a printing method for reducing metal splashing. BACKGROUND

[0002] The SLA, SLS and SLM in 3D printing adopt a single-beam laser reflected by a galvanometer to perform image scanning printing on a two-dimensional working plane. Compared with traditional subtractive manufacturing technology, 3D printing technology is an advanced rapid manufacturing additive manufacturing technology, and metal 3D printing (SLM) is a manufacturing method for manufacturing parts by using metal powder to melt under the action of a laser beam, and then cooling and condensing and layering and accumulating.

[0003] When metal powder is used for 3D printing, the molten liquid metal splashes in the rapid heating and melting process of the metal powder, solidifies in the splashing process, and falls on the surface of the printed part, making the surface of the printed part rough and defects appearing in the interior, as shown in FIG. 1. Figure 1 The generation of splashing particles is mainly caused by the process of melting metal powder into liquid. In SLM metal 3D printing, a laser is used as an energy source and is absorbed by metal materials to generate a molten pool. Therefore, the melting efficiency of the metal is not only related to the laser power, but also related to the absorption rate of the metal material to the laser. The SLM metal 3D printing equipment usually uses an infrared laser with a wavelength of 1080 nm. The resonant frequency of the free electrons in the metal material is close to the frequency of the laser with this wavelength. At this time, the laser absorption rate is very low, and the reflectivity is very high. The reflectivity of the commonly seen pure copper, pure gold, pure silver, pure aluminum and the like tends to be 100%. Therefore, the reflectivity of the laser with this wavelength used for metal sintering of such materials is not high. The absorption rate of the metal to the laser is affected by the external environment, among which the most obvious is the temperature. The reflection of the metal material to the laser is due to the internal electronic resonance, and when the temperature rises, the electronic resonance changes, the resistivity of the metal increases, and the conductivity decreases. At this time, the absorption rate of the laser with a wavelength of 1080 nm will increase significantly. For general materials, theoretically, the higher the temperature, the stronger the laser absorption rate. Taking metal copper as an example, according to the public data, the absorption rate curve of copper to infrared 1064 nm laser is shown in FIG. 2. It can be seen that, with the melting temperature increasing from 0 to 1400K, the absorption of copper to infrared light slowly rises from 5% to about 10%. When copper reaches the melting point (1400K), the absorption rate of copper to the infrared waveband laser will jump from 10% to about 17%. Then, with the temperature continuing to rise, the absorption rate will slowly increase. The sudden change of the absorption rate will cause the laser power absorbed by the metal material to increase sharply in a short time, and the melting process of the metal powder will be more violent, so that some melted materials are discharged in the form of splashing. Figure 2

[0004] ​In order to prevent the splashed particles from affecting the quality of the printed parts, a horizontal wind field is usually added in metal 3D printing to blow away the splashed particles using wind, but the wind field blowing away the particles is subject to many conditions: if the wind speed of the wind field is too small, the splashed particles cannot be blown away by the wind; if the wind speed of the wind field is too large, the metal powder laid on the printing work surface is easily blown away; if the printing work cavity is too large, the wind field is easily turbulent, and in addition to the distance side length that the splashed particles need to be blown, no matter what parameters are set, the splashed particles cannot be completely blown away from the work cavity. In order to improve the splashing of particles in metal 3D part printing, another way is to heat the printing work base plate to make its working temperature reach 200~500℃, so as to reduce the energy required to heat the metal powder to the melting point, thereby reducing the time ratio of the laser beam heating the metal powder to the melting point, increasing the time ratio of the light spot melting the metal powder to the liquid state, and thereby reducing the splashing of particles. This method will affect the equipment, the temperature of the work base plate will be transferred to the rest of the equipment work cavity, causing the work cavity to expand and contract due to heat, causing the printing size to change and drift. And because the composition of the work cavity is irregular, the change of the printing size is also irregular, which seriously affects the printing quality. In summary, the above two schemes for preventing and improving the splashing of particles in metal 3D part printing have limitations. SUMMARY

[0005] The present application provides a metal 3D printing system and printing method for reducing metal splashing to reduce or solve the problem of quality defects of printed parts caused by liquid metal splashing in the metal 3D printing process.

[0006] To solve the above technical problems, the technical scheme provided by the present application is:

[0007] The present application relates to a metal 3D printing system for reducing metal splashing, which comprises a laser and an imaging module, a galvanometer module and a printing work surface arranged on the light path of the laser beam emitted by the laser, wherein an optical path shaping module is arranged between the laser and the galvanometer module, the optical path shaping module comprises an angle adjusting ring, a first collimating lens, a first Powell prism and a second collimating lens which are arranged in sequence along the light path and are installed in the angle adjusting ring; the first collimating lens is used to adjust the laser beam into a parallel light beam; the first Powell prism is used to diffuse the laser beam in one direction, so that the cross section of the laser beam is stretched along the diffusion direction, and the first Powell prism is arranged eccentrically with the laser beam, so that the energy of the diffused laser beam gradually decreases from one end to the other end of the diffusion direction; the second collimating lens is used to adjust the diffused laser beam into a parallel light beam; the angle adjusting ring is provided with a driving motor, and the driving motor is used to rotate the angle adjusting ring to adjust the diffusion direction of the laser beam to be the same as the scanning direction, and the end with higher energy is located at the front end of the scanning direction.

[0008] Preferably, the light path shaping module further comprises a second Powell prism, a multi-channel grating light head, a dynamic focusing module and a zoom module, the second Powell prism is fixed in the angle adjusting ring between the first collimating lens and the second collimating lens, the second Powell prism is coaxial with the laser beam, the second Powell prism is perpendicular to the first Powell prism, used to diffuse the laser beam to another direction, so that the cross section of the laser beam is stretched along another direction, and the directions of the laser beam diffused by the first Powell prism and the second Powell prism are perpendicular to each other, so that the cross section of the laser beam after combined diffusion of the first Powell prism and the second Powell prism is a rectangular cross section, and the energy of the rectangular cross section of the laser beam gradually weakens from one end to the other end of the diffusion direction of the first Powell prism; the multi-channel grating light head, the dynamic focusing module and the zoom module are arranged between the second collimating lens and the galvanometer module, the multi-channel grating light head is arranged in the angle adjusting ring, used to divide the rectangular cross section of the laser beam into several strip-shaped beams along the direction in which the first Powell prism stretches the laser beam, and the dynamic focusing module and the zoom module are provided with a controller for real-time dynamic compensation adjustment of each strip-shaped beam.

[0009] Preferably, the imaging module is an imaging lens arranged in front of the light path of the galvanometer module.

[0010] Preferably, the imaging module is a field lens arranged behind the light path of the galvanometer module.

[0011] A 3D printing method based on the above metal 3D printing system for reducing metal spatter, comprising the following steps:

[0012] Step 1. Start the laser, and the laser emits a divergent laser beam to the light path shaping module;

[0013] Step 2. The laser beam passes through the first collimating lens, the eccentrically arranged first Powell prism and the second collimating lens in the light path shaping module in sequence; the first collimating lens adjusts the laser beam into a parallel beam, the first Powell prism diffuses the laser beam to one direction, so that the cross section of the laser beam is stretched along the diffusion direction, and the energy of the diffused laser beam gradually weakens from one end to the other end of the diffusion direction; the second collimating lens adjusts the diffused laser beam into a parallel beam again;

[0014] Step 3. The laser beam passing through the light path shaping module is focused by the imaging module and reflected by the galvanometer module, and then irradiates the metal powder layer on the printing work surface;

[0015] Step 4. A scanning path is planned according to the printing file, the galvanometer module changes the position of the laser beam irradiating to the metal powder layer according to the scanning path, and meanwhile, the driving motor rotates the angle adjustment ring to adjust the diffusion direction of the laser beam to the same direction as the scanning direction, and to make the end with higher energy be located at the front end of the scanning direction.

[0016] Preferably, in the step 4, the angle of the driving motor rotating the angle adjustment ring is:

[0017] (1),

[0018] In the formula, x1 and y1 represent the horizontal coordinate and the vertical coordinate of the starting point of any scanning vector, respectively, a 1 and b 1 represent the horizontal coordinate and the vertical coordinate of the end point of any scanning vector, respectively, a 2 and b 2 represent the horizontal coordinate and the vertical coordinate of the end point of any scanning vector, respectively, β is the adjustment angle of the angle adjustment module relative to the initial state of the angle adjustment module.

[0019] Preferably, the optical path shaping module further comprises a second Powell prism, a multi-channel grating light head, a dynamic focusing module and a zoom module, the second Powell prism is fixed in the angle adjustment ring at a position between the first collimating lens and the second collimating lens, the second Powell prism is coaxial with the laser beam, and the second Powell prism is perpendicular to the first Powell prism; the multi-channel grating light head, the dynamic focusing module and the zoom module are arranged between the second collimating lens and the galvanometer module, and the dynamic focusing module and the zoom module are provided with a controller.

[0020] In the step 2, the first collimating lens adjusts the laser beam into a parallel beam; the first Powell prism diffuses the laser beam in one direction to stretch the cross section of the laser beam along the diffusion direction; the second Powell prism diffuses the laser beam in another direction to stretch the cross section of the laser beam along the other diffusion direction, the directions of the first Powell prism and the second Powell prism diffusing the laser beam are perpendicular to each other, so that the cross section of the laser beam after the combined diffusion of the first Powell prism and the second Powell prism is a rectangular cross section, and the energy of the laser beam with the rectangular cross section gradually weakens from one end to the other end of the diffusion direction of the first Powell prism; the second collimating lens adjusts the diffused laser beam into a parallel beam again; the multi-channel grating light head divides the laser beam with the rectangular cross section into several strip-shaped beams along the direction of the first Powell prism diffusing the laser beam; and the dynamic focusing module and the zoom module perform real-time dynamic compensation adjustment on each strip-shaped beam.

[0021] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects:

[0022] 1.The metal 3D printing system for reducing metal splashing comprises a light path shaping module, the light path shaping module comprises an angle adjusting ring, a first collimating lens, a first Powell prism and a second collimating lens which are sequentially arranged along the light path direction and are installed in the angle adjusting ring, wherein the first Powell prism is arranged eccentrically with the laser beam, is used for diffusing the laser beam in one direction, and makes the energy of the diffused laser beam gradually weaken from one end to the other end of the diffusion direction, the first collimating lens and the second collimating lens respectively adjust the laser beams before and after the diffusion of the first Powell prism into parallel light beams, during the metal 3D printing, the direction of the diffused laser beam of the first Powell prism is adjusted through the angle adjusting ring, so that the direction of the diffused laser beam is the same as the scanning direction and the end with higher energy is located at the front end of the scanning direction, when the metal powder at a certain printing position is melted, with the action of the laser beam on the metal powder to be sintered, the temperature of the metal powder gradually rises, and at the same time, the laser energy gradually decreases, until the metal powder is melted, the laser energy is at the lowest, the energy distribution curve of the laser beam and the curve of the metal powder absorption rate to the laser when the temperature rises are compensated, when the metal powder is melted, the absorption power of the liquid metal to the laser is reduced, so that the reaction of the liquid metal after melting is not violent, and the splashing of the metal droplets is reduced.

[0023] 2.The light path shaping module of the metal 3D printing system for reducing metal splashing can further comprise a second Powell prism and a multi-channel grating light head, wherein the second Powell prism is coaxial with the laser beam, the second Powell prism is perpendicular to the first Powell prism, is used for diffusing the laser beam in another direction, so that the cross section of the laser beam is stretched along the other direction, and the directions of the laser beams diffused by the second Powell prism and the first Powell prism are perpendicular to each other, so that the cross section of the laser beam after the joint diffusion of the first Powell prism and the second Powell prism is a rectangular cross section, and then the multi-channel grating light head is used to divide the laser beam with the rectangular cross section into a plurality of strip-shaped light beams along the direction of the laser beam diffused by the first Powell prism, so as to form a plurality of strip-shaped laser beams with gradually reduced energy, thereby reducing the splashing of the metal droplets and improving the printing efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a principle diagram of the existing metal 3D printing to generate splashing;

[0025] Figure 2 is an absorption rate curve diagram of the metal copper to the infrared 1064nm laser;

[0026] Figure 3 is a structure diagram of the metal 3D printing system for reducing metal splashing in the embodiment 1;

[0027] Figure 4 is a structure diagram of the light path shaping module of the metal 3D printing system in the embodiment 1;

[0028] Figure 5 is the light intensity distribution after the first Powell lens with eccentricity setting of the laser beam;

[0029] Figure 6 is the detailed energy distribution diagram of the laser beam before and after the first Powell lens with eccentricity setting;

[0030] Figure 7 is the structure diagram of the metal 3D printing system related to the rear focusing for reducing metal spatter in Example 1;

[0031] Figure 8 is the Gaussian energy distribution diagram of the laser beam inputted by the laser;

[0032] Figure 9 is the Gaussian energy distribution diagram of the light beam after the first Powell lens with eccentricity setting;

[0033] Figure 10 is the Gaussian energy distribution diagram of the light beam after the first Powell lens with different eccentricity settings;

[0034] Figure 11 is the schematic diagram of the diffusion direction of the laser beam changing with the rotation of the angle adjusting ring;

[0035] Figure 12 is the diagram of the relationship between the light spot of the printing work surface and the laser scanning direction;

[0036] Figure 13 is the structure diagram of the metal 3D printing system related to the rear focusing for reducing metal spatter in Example 2;

[0037] Figure 14 is the front view of the optical path shaping module omitting the angle adjusting ring in Example 2;

[0038] Figure 15 is the top view of the optical path shaping module omitting the angle adjusting ring in Example 2.

[0039] Reference signs: 1-laser, 2-optical path shaping module, 21-first collimating lens, 22-first Powell lens, 23-second Powell lens, 24-second collimating lens, 25-multichannel grating light head, 26-dynamic focusing module, 27-zoom module, 28-angle adjusting ring, 3-imaging module, 4-galvanometer module, 5-printing work surface. DETAILED DESCRIPTION

[0040] For further understanding of the present application, the application will be described in detail with examples, which are used to illustrate the application but not to limit the scope of the application. EXAMPLE

[0041] Reference is made to the accompanying drawings Figure 3As shown, this embodiment relates to a metal 3D printing system for reducing metal spatter, comprising a laser 1 and an optical path shaping module 2, an imaging module 3, a galvanometer module 4, and a printing working surface 5 disposed on the optical path of the laser beam emitted by the laser 1. (See attached diagram.) Figure 4 As shown, the optical path shaping module 2 includes an angle adjustment ring 28, a first collimating lens 21, a first Powell prism 22, and a second collimating lens 24, which are installed within the angle adjustment ring 28 and arranged sequentially along the optical path direction. The first collimating lens 21 is used to adjust the laser beam into a parallel beam. The first Powell prism 22 is used to diffuse the laser beam in one direction, causing the cross-section of the laser beam to be stretched along the diffusion direction. The first Powell prism 22 is offset from the laser beam, so that the energy of the diffused laser beam gradually weakens from one end of the diffusion direction to the other end. The light intensity distribution of the laser beam after passing through the offset first Powell prism 22 is as follows: Figure 5 and Figure 6 As shown; the second collimating lens 24 is used to adjust the diffused laser beam into a parallel beam; the angle adjustment ring 28 is equipped with a drive motor (not shown in the figure), which is used to rotate the angle adjustment ring 28 to adjust the diffusion direction of the laser beam to be the same as the scanning direction, and the end with higher energy is located at the front end of the scanning direction.

[0042] In this embodiment, a front focusing system can be used, that is, the imaging module 3 is an imaging lens located in front of the optical path of the galvanometer module 4, and the imaging lens is a convex lens, such as... Figure 1 As shown; alternatively, a post-focusing system can be used, where the imaging module 3 is a field lens positioned behind the optical path of the galvanometer module 4, such as... Figure 7 As shown.

[0043] A 3D printing method based on a metal 3D printing system that reduces metal spatter includes the following steps:

[0044] Step 1. Activate laser 1. Laser 1 emits a divergent laser beam towards optical path shaping module 2. The Gaussian energy distribution of the laser beam is as follows: Figure 8 As shown;

[0045] Step 2. As Figure 4 As shown, the laser beam passes sequentially through the first collimating lens 21, the eccentrically positioned first Powell prism 22, and the second collimating lens 24 in the optical path shaping module 2. The first collimating lens 21 adjusts the laser beam into a parallel beam, and the first Powell prism 22 diffuses the laser beam in one direction, causing the cross-section of the laser beam to be stretched along the diffusion direction. Furthermore, the energy of the diffused laser beam gradually decreases from one end of the diffusion direction to the other, and its energy distribution is as follows: Figure 9 As shown, of course, the energy distribution is different depending on the eccentricity of the first Powell prism 22. The energy distribution of the laser beam after passing through the first Powell prism 22 with a different eccentricity is as follows:Figure 10 As shown, the specific eccentricity can be adjusted according to actual printing requirements; the second collimating lens 24 adjusts the diffused laser beam into a parallel light beam again; by Figure 9 and Figure 10 It can be seen that the end of the diffused laser beam with strong light intensity has a part with gradually increasing light intensity, but the length of this part is extremely short compared to the length of the cross section of the diffused laser beam and can be ignored; in the process of gradually decreasing light intensity, the light intensity is not always decreasing but fluctuating; here, the gradual decrease of the energy of the diffused laser beam from one end to the other end in the diffusion direction means that the overall trend is gradually decreasing.

[0046] Step 3. The laser beam passing through the light path shaping module 2 is focused by the imaging module 3 and reflected by the galvanometer module 4, and then irradiates the metal powder layer on the printing work surface 5;

[0047] Step 4. The scanning path is planned according to the printing file, and the galvanometer module 4 changes the position of the laser beam irradiating the metal powder layer according to the scanning path, while the driving motor rotates the angle adjustment ring 28, and the diffusion direction of the laser beam changes accordingly, as shown in Figure 11 The diffusion direction of the laser beam is adjusted to be the same as the scanning direction, and the end with higher energy is located at the front end of the scanning direction, as shown in Figure 12 The angle of the driving motor rotating the angle adjustment ring 28 is:

[0048] (1),

[0049] In the formula, a 1 and b 1 represent the horizontal coordinate and vertical coordinate of the starting point of any scanning vector, a 2 and b 2 represent the horizontal coordinate and vertical coordinate of the end point of any scanning vector, β is the adjustment angle of the angle adjustment module relative to the initial state. By adjusting the energy distribution direction of the light spot in real time, the energy high end of the light spot can be made the same as the scanning direction when the laser scans in any direction on the printing work surface.

[0050] In this way, when the metal powder at a certain printing position is melted, the temperature of the metal powder gradually rises as the laser beam acts on the metal powder to be sintered, and at the same time, the laser energy gradually decreases until the metal powder melts, and the laser energy is at a minimum. By compensating the laser energy distribution curve and the curve of the metal powder's absorption rate of laser when the temperature rises, the absorption power of the liquid metal to the laser is reduced when the metal powder is melted, so that the reaction of the liquid metal after melting is no longer intense, and the splashing of the metal droplets is reduced. Embodiment

[0051] Referring to the accompanying drawings Figure 13 The metal 3D printing system for reducing metal spatter according to the embodiment includes a laser 1 and an optical path shaping module 2, an imaging module 3, a galvanometer module 4 and a printing work surface 5 arranged in the light path of the laser beam emitted by the laser 1. Referring to the accompanying drawings Figure 14 and 15 The optical path shaping module 2 includes an angle adjusting ring 28, a first collimating lens 21, a first Powell prism 22, a second Powell prism 23 and a second collimating lens 24 arranged in the optical path in sequence and inside the angle adjusting ring 28, a multi-channel grating optical head 25, a dynamic focusing module 26 and a zoom module 27 arranged at the rear side of the second collimating lens 24 in the optical path; the first collimating lens 21 is used to adjust the laser beam into a parallel light beam; the first Powell prism 22 is used to diffuse the laser beam in one direction so that the cross section of the laser beam is stretched along the diffusion direction, the first Powell prism 22 is arranged eccentrically with the laser beam so that the energy of the diffused laser beam gradually weakens from one end to the other end of the diffusion direction, and the light intensity distribution of the laser beam after passing through the eccentrically arranged first Powell prism 22 is as shown in Figure 5 and Figure 6The second Powell prism 23 is coaxial with the laser beam, perpendicular to the first Powell prism 22, and used to diffuse the laser beam to another direction, so that the cross section of the laser beam is stretched along another direction, and the directions of the first Powell prism 22 and the second Powell prism 23 are perpendicular to each other, so that the cross section of the laser beam after being diffused by the first Powell prism 22 and the second Powell prism 23 is a rectangular cross section, and the energy of the laser beam with the rectangular cross section gradually decreases from one end to the other end of the diffusion direction of the first Powell prism 22; the second collimating lens 24 is used to adjust the diffused laser beam into a parallel light beam; the multi-channel grating light head 25 is arranged in the angle adjusting ring and rotates synchronously with the first Powell prism, and used to divide the laser beam with the rectangular cross section into several strip-shaped light beams along the direction in which the first Powell prism 22 stretches the laser beam, each channel grating in the multi-channel grating light head 25 can be controlled independently, the dynamic focusing module 26 is a focusing lens, and the focusing lens is a convex lens; the zoom module 27 adopts a zoom lens, and the zoom lens is a concave lens; the dynamic focusing module 26 and the zoom module 27 are provided with a controller, the control device is a voice coil motor and a control circuit (not shown in the figure), the dynamic focusing module 26 and the zoom module 27 are driven by the voice coil motor, the voice coil motor is controlled by the control circuit, and the dynamic focusing module 26 and the zoom module 27 cooperate to perform real-time dynamic compensation adjustment on each strip-shaped light beam. The angle adjusting ring 28 is provided with a driving motor, the driving motor is used to rotate the angle adjusting ring 28, so that the length direction of the strip-shaped light beam is adjusted to be the same as the scanning direction, and the end with higher energy is located at the front end of the scanning direction.

[0052] A 3D printing method based on a metal 3D printing system for reducing metal spatter, comprising the following steps:

[0053] Step 1. Start the laser 1, and the laser 1 emits a divergent laser beam to the light path shaping module 2, and the Gaussian energy distribution of the laser beam is as shown in Figure 8 ;

[0054] Step 2. As shown in Figure 13 , the laser beam sequentially passes through the first collimating lens 21, the first Powell prism 22 arranged eccentrically, the second Powell prism 23, the second collimating lens 24, the multi-channel grating light head 25, the dynamic focusing module 26 and the zoom module 27 in the light path shaping module 2; the first collimating lens 21 adjusts the laser beam into a parallel light beam, the first Powell prism 22 diffuses the laser beam to one direction, so that the cross section of the laser beam is stretched along the diffusion direction, and the energy of the diffused laser beam gradually decreases from one end to the other end of the diffusion direction, and the energy distribution is as shown in Figure 9As shown, of course, the first Powell prism 22 has different eccentric amounts, and the energy distribution is also different, the energy distribution of the laser beam after passing through the first Powell prism 22 with another eccentric amount is as shown in FIG. 2B Figure 10 As shown, the specific eccentric amount is determined according to the actual printing requirement; the second Powell prism 23 diffuses the laser beam to another direction, so that the cross section of the laser beam is stretched along another diffusion direction, the diffusion direction of the second Powell prism 23 is perpendicular to that of the first Powell prism 22, so that the cross section of the laser beam after the joint diffusion of the first Powell prism 22 and the second Powell prism 23 is a rectangular cross section, and the energy of the laser beam with the rectangular cross section gradually weakens from one end to the other end of the diffusion direction of the first Powell prism 22; the second collimating lens 24 adjusts the diffused laser beam into a parallel light beam again; the multi-channel grating light head 25 divides the laser beam with the rectangular cross section into several strip-shaped light beams along the diffusion direction of the first Powell prism 22; the dynamic focusing module 26 and the zoom module 27 perform real-time dynamic compensation adjustment on each strip-shaped light beam.

[0055] Step 3. The laser beam passing through the light path shaping module 2 is focused by the imaging module 3 and reflected by the galvanometer module 4, and then irradiates the metal powder layer on the printing work surface 5;

[0056] Step 4. The scanning path is planned according to the printing file, the galvanometer module 4 changes the position of the laser beam irradiating the metal powder layer according to the scanning path, at the same time, the driving motor rotates the angle adjustment ring 28, and the diffusion direction of the laser beam changes accordingly, the length direction of each strip-shaped light beam is adjusted to be the same as the scanning direction, and the end with higher energy is located at the front end of the scanning direction, and the angle of the driving motor rotating the angle adjustment ring 28 is:

[0057] (1),

[0058] In the formula, a 1 and b 1 represent the horizontal coordinate and the vertical coordinate of the starting point of any scanning vector, a 2 and b 2 represent the horizontal coordinate and the vertical coordinate of the end point of any scanning vector, β is the adjustment angle of the angle adjustment module relative to the initial state of the angle adjustment module;

[0059] During the scanning process, the scanning lengths of the strip-shaped light beams may be different, for this purpose, the multi-channel grating light head 25 can be used to adjust the on-off of each channel according to the scanning path, so as to meet the requirement of different scanning lengths.

[0060] Compared with embodiment 1, this embodiment realizes the simultaneous printing of multiple laser beams, and has higher printing efficiency.

[0061] The application has been described in detail with reference to the embodiments above. However, the above description is merely the preferred embodiments of the application, and should not be considered as limiting the scope of the application. Any equivalent changes and improvements made according to the scope of the application should still fall within the patent scope of the application.

Claims

1. A metal 3D printing system for reducing metal spatter, comprising a laser and an imaging module, a galvanometer module and a printing work surface disposed in the optical path of a laser beam emitted by the laser, characterized in that: The laser and the galvanometer module are provided with an optical path shaping module, the optical path shaping module comprises an angle adjusting ring, a first collimating lens, a first Powell prism and a second collimating lens which are sequentially arranged along the optical path and are arranged in the angle adjusting ring; the first collimating lens is used for adjusting the laser beam into a parallel light beam; the first Powell prism is used for diffusing the laser beam to one direction, so that the cross section of the laser beam is stretched along the diffusion direction, the first Powell prism is arranged eccentrically with the laser beam, so that the energy of the diffused laser beam gradually decreases from one end to the other end of the diffusion direction; the second collimating lens is used for adjusting the diffused laser beam into a parallel light beam; the angle adjusting ring is provided with a driving motor, the driving motor is used for rotating the angle adjusting ring, the diffusion direction of the laser beam is adjusted to be the same as the scanning direction, and the end with higher energy is located at the front end of the scanning direction.

2. The metal 3D printing system to mitigate metal spatter of claim 1, wherein: The optical path shaping module further comprises a second Powell prism, a multi-channel grating light head, a dynamic focusing module and a zoom module, the second Powell prism is fixed in the angle adjusting ring and is located between the first collimating lens and the second collimating lens, the second Powell prism is coaxial with the laser beam, the second Powell prism is perpendicular to the first Powell prism, is used for diffusing the laser beam to the other direction, so that the cross section of the laser beam is stretched along the other direction, and the directions of the laser beams diffused by the second Powell prism and the first Powell prism are perpendicular to each other, so that the cross section of the laser beam after being diffused by the first Powell prism and the second Powell prism is a rectangular cross section, and the energy of the rectangular cross section of the laser beam gradually decreases from one end to the other end of the diffusion direction of the first Powell prism; the multi-channel grating light head, the dynamic focusing module and the zoom module are arranged between the second collimating lens and the galvanometer module, the multi-channel grating light head is arranged in the angle adjusting ring and is used for dividing the rectangular cross section of the laser beam into a plurality of strip-shaped light beams along the direction in which the first Powell prism stretches the laser beam, and the dynamic focusing module and the zoom module are provided with a controller and are used for dynamically compensating and adjusting each strip-shaped light beam in real time.

3. The metal spatter mitigating metal 3D printing system of claim 1, wherein: The imaging module is an imaging lens arranged in front of the optical path of the galvanometer module.

4. The metal 3D printing system to mitigate metal spatter of claim 1, wherein: The imaging module is a field lens arranged behind the optical path of the galvanometer module.

5. A 3D printing method based on the metal 3D printing system for mitigating metal spatter according to claim 1, characterized in that: It comprises the following steps: Step 1. Start the laser, the laser emits a divergent laser beam to the optical path shaping module; Step 2. The laser beam sequentially passes through the first collimating lens, the eccentrically arranged first Powell prism and the second collimating lens in the optical path shaping module; the first collimating lens adjusts the laser beam into a parallel light beam, the first Powell prism diffuses the laser beam to one direction, so that the cross section of the laser beam is stretched along the diffusion direction, and the energy of the diffused laser beam gradually decreases from one end to the other end of the diffusion direction; the second collimating lens adjusts the diffused laser beam into a parallel light beam again; Step 3. The laser beam passing through the optical path shaping module is focused by the imaging module and reflected by the galvanometer module, and then irradiates the metal powder layer on the printing work surface; Step 4. The scanning path is planned according to the printing file, the galvanometer module changes the position of the laser beam irradiating to the metal powder layer according to the scanning path, and at the same time, the driving motor rotates the angle adjustment ring to adjust the diffusion direction of the laser beam to the same direction as the scanning direction, and make the end with higher energy at the front end of the scanning direction.

6. The 3D printing method of mitigating metal spatter of a metal 3D printing system of claim 5, wherein: In step 4, the angle of the driving motor rotating the angle adjustment ring is: （1）， In the formula, a 1 and b 1 represent the horizontal coordinate and the vertical coordinate of the starting point of an arbitrary scanning vector, respectively, a 2 and b 2 represent the horizontal coordinate and the vertical coordinate of the ending point of an arbitrary scanning vector, respectively, β is the adjustment angle of the angle adjustment module relative to the initial state of the angle adjustment module.

7. The 3D printing method of mitigating metal spatter of a metal 3D printing system of claim 5, wherein: The optical path shaping module further comprises a second Powell prism, a multi-channel grating light head, a dynamic focusing module and a zoom module, the second Powell prism is fixed in the angle adjustment ring at a position between the first collimating lens and the second collimating lens, the second Powell prism is coaxial with the laser beam, and the second Powell prism is perpendicular to the first Powell prism; the multi-channel grating light head, the dynamic focusing module and the zoom module are arranged between the second collimating lens and the galvanometer module, and the dynamic focusing module and the zoom module are provided with a controller; In step 2, the first collimating lens adjusts the laser beam to a parallel beam; the first Powell prism diffuses the laser beam in one direction, so that the cross section of the laser beam is stretched along the diffusion direction; the second Powell prism diffuses the laser beam in another direction, so that the cross section of the laser beam is stretched along the other diffusion direction, the directions of the first Powell prism and the second Powell prism diffusing the laser beam are perpendicular to each other, so that the cross section of the laser beam after combined diffusion of the first Powell prism and the second Powell prism is a rectangular cross section, the energy of the rectangular cross section of the laser beam gradually decreases from one end to the other end of the diffusion direction of the first Powell prism; the second collimating lens adjusts the diffused laser beam to a parallel beam again; the multi-channel grating light head divides the rectangular cross section of the laser beam into several strip-shaped beams along the direction of the first Powell prism diffusing the laser beam; the dynamic focusing module and the zoom module perform real-time dynamic compensation adjustment on each strip-shaped beam.

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