Selective laser melting forming device

Abstract

The invention discloses a selective laser melting forming device, relates to a melting forming technology, and can prevent reflected light from being reflected into an optical device, improve the utilization rate of laser and further improve protection on an optical system. The selective laser melting forming device is characterized by comprising a laser source; the optical system comprises a scanning galvanometer and a first optical lens, the laser source is arranged on the side, away from the first optical lens, of the scanning galvanometer, and laser emitted by the laser source is transmitted to the first optical lens through the scanning galvanometer; the forming cabin is connected with the optical system, and the laser emitted by the first optical lens is transmitted to a machining area of the forming cabin, so that a target machining material in the machining area is melted and formed; the forming cabin comprises a protective cover, a reflecting layer is arranged on the side, facing the machining area, of the protective cover, a window is formed in the area, corresponding to emergent light of the first optical lens, of the protective cover, and a second optical lens is arranged in the window and used for transmitting laser emitted by the first optical lens and irradiating the laser to the machining area. And the second optical lens is used for blocking light rays in the forming cabin from penetrating.

Description

Technical Field

[0001] The present application relates to the technical field of additive manufacturing, and in particular to a laser selective melting forming device. Background Art

[0002] At present, the selective laser melting (SLM) forming technology has great advantages in the field of laser additive manufacturing due to its unique technical characteristics. However, due to the large differences in the absorption rates of different metals to different laser wavelengths, there are many metal materials with high reflectivity. These types of metals reflect a large amount of laser during the SLM forming process, resulting in low laser energy utilization and even damage to the components of the optical system. Summary of the invention

[0003] The embodiment of the present application provides a laser selective melting forming device, which can prevent reflected light from being reflected into optical devices, improve the utilization rate of lasers, and improve the protection of optical systems.

[0004] In a first aspect of an embodiment of the present application, a laser selective melting forming device is provided, comprising:

[0005] Laser source;

[0006] An optical system, wherein the optical system comprises a scanning galvanometer and a first optical lens, wherein the laser source is disposed on a side of the scanning galvanometer away from the first optical lens, and the laser emitted by the laser source is transmitted to the first optical lens via the scanning galvanometer;

[0007] A forming chamber, wherein the forming chamber is connected to the optical system, and the laser emitted by the first optical lens is transmitted to a processing area of ​​the forming chamber, so that a target processing material in the processing area is melted and formed;

[0008] The forming chamber includes a protective cover, a reflective layer is arranged on the side of the protective cover facing the processing area, the protective cover is provided with a window corresponding to the area where the first optical lens emits light, a second optical lens is arranged in the window, the second optical lens is used to transmit the laser emitted by the first optical lens to the processing area, and the second optical lens is used to block the transmission of light in the forming chamber.

[0009] In some embodiments, the surface of the protective cover facing the processing area includes a curved surface, and a focus of the curved surface is located on a side close to the processing area.

[0010] In some embodiments, the curved surface includes a parabola and / or a spherical surface;

[0011] The radius of curvature of the parabola is greater than or equal to the radius of curvature of the spherical surface.

[0012] In some embodiments, the second optical lens comprises a planar one-way lens, the second optical lens is sealed to the window, and a centerline of the window coincides with a centerline of the protective cover.

[0013] In some embodiments, the protective cover is embedded in the top of the forming chamber, a water cooling channel is embedded in the protective cover, the top of the forming chamber is arranged on a side of the protective cover close to the optical system, and the optical system is embedded in the top of the forming chamber.

[0014] In some embodiments, the optical system further includes a beam expander collimator, which is disposed between the laser source and the scanning galvanometer.

[0015] In some embodiments, the forming chamber further includes a powder feeding mechanism, a powder spreading mechanism, a powder spreading guide rail, a lifting mechanism and a lifting platform, one end of the powder feeding mechanism is connected to the side wall of the protective cover, the other end of the powder feeding mechanism is embedded in the top of the forming chamber, the outlet of the powder feeding mechanism is connected to the powder spreading mechanism, the powder spreading mechanism is used to move along the powder spreading guide rail to spread powder in the processing area, the lifting mechanism is connected to the lifting platform, and the lifting mechanism is used to adjust the rise or fall of the lifting platform to adjust the thickness of the powder.

[0016] In some embodiments, a center line of the lifting platform, a center line of the processing area, and a center line of the protective cover coincide with each other.

[0017] In some embodiments, the forming chamber is a sealed chamber, and the oxygen content in the forming chamber is less than 500 ppm.

[0018] In some embodiments, the laser source emits a laser with a wavelength ranging from 200 nm to 1250 nm; and / or,

[0019] The wavelength range of the reflected light of the reflective layer is 200nm to 1250nm; and / or,

[0020] The curvature radius of the protective cover ranges from 400 mm to 3000 mm.

[0021] In the embodiment of the present application, a protective cover is provided in the forming chamber, and a reflective layer is provided on the side of the protective cover facing the processing area. The reflective layer has a high reflective performance and can reflect the reflected light from the processing area back to the processing area, and the energy of the reflected laser is used to preheat the processing area, thereby reducing the melting energy threshold of the target processing material and reducing the temperature gradient of the processing area, thereby improving the energy utilization rate. At the same time, a second optical lens is provided on the side of the protective cover corresponding to the light emitted by the first optical lens, and the second optical lens is used as an isolation device of the optical system to prevent the reflected light from being transmitted back along the optical path to the surface of the optical device in the optical path system, thereby protecting the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a laser selective melting forming device for a high-reflective metal provided in an embodiment of the present application;

[0023] Figure 2 A schematic structural diagram of a protective cover provided in an embodiment of the present application;

[0024] Figure 3 A schematic optical path diagram of a protective cover provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to better understand the technical solutions provided by the embodiments of this specification, the technical solutions of the embodiments of this specification are described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of this specification and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this specification, rather than limitations on the technical solutions of this specification. In the absence of conflict, the embodiments of this specification and the technical features in the embodiments can be combined with each other.

[0026] 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 that there is 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 the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the statement "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. The term "more than two" includes two or more than two situations.

[0027] At present, laser selective melting forming technology has great advantages in the field of additive manufacturing due to its unique technical characteristics, but due to the large differences in the absorption rates of different metals to different laser wavelengths, there are many metal materials with high reflectivity. These types of metals reflect a large amount of processing laser during the SLM forming process, resulting in low laser energy utilization and even damage to the components of the optical system.

[0028] In view of this, an embodiment of the present application provides a laser selective melting forming device for highly reflective metals, which can prevent reflected light from being reflected into optical devices, improve the utilization rate of laser energy, and further improve the protection of the optical system.

[0029] According to a first aspect of an embodiment of the present application, a laser selective melting forming device for high-reflective metal is provided. Figure 1 This is a schematic structural diagram of a laser selective melting forming device for a high reflective metal provided in an embodiment of the present application. Figure 1 As shown, the laser selective melting forming device of high reflective metal includes a laser source 1, an optical system 100, a control system and a forming chamber 5. The optical system 100 may include a beam expander collimator 2, a scanning galvanometer and a first optical lens 3. The beam expander collimator 2 is arranged between the laser source 1 and the scanning galvanometer, the scanning galvanometer is arranged between the beam expander collimator 2 and the first optical lens 3, and the laser source 1 is arranged on the side of the scanning galvanometer away from the first optical lens 3. The first optical lens 3 may be a field lens, which is used to focus the laser, and the laser focus after passing through the field lens is on the same focal plane. The laser source 1 may be a light source that emits continuous laser light, such as a fiber laser, a solid laser, a semiconductor laser, etc., and the wavelength range of the laser emitted by the laser source 1 is 200nm to 1250nm. Schematically, the laser source 1 may be a single-mode quasi-continuous laser, and the continuous laser emitted by the laser source 1 first passes through the beam expander collimator 2 for beam expansion and collimation and focusing, and the continuous laser after collimation and focusing passes through the scanning galvanometer, and the continuous laser output by the scanning galvanometer is transmitted to the forming chamber through the first optical lens. The forming chamber 5 is connected to the optical system 100, and the optical system 100 is embedded in the top of the forming chamber 5. The continuous laser output by the laser source 1 enters the processing area of ​​the forming chamber after being transmitted by the optical system 100, so that the target processing material in the processing area is melted and formed.

[0030] It should be noted that the scanning galvanometer is electrically connected to the computer in the control system. When the collimated and focused continuous laser is transmitted to the scanning galvanometer, the control system can control the movement of the scanning galvanometer to melt and form the target processing material by controlling the running trajectory of the scanning galvanometer. At the same time, the control system can also control the output power of the laser to accurately control the laser power required for processing and improve the work efficiency of laser selective melting.

[0031] Figure 2A schematic structural diagram of a protective cover provided in an embodiment of the present application. For example, refer to Figure 1 and Figure 2 As shown, the forming chamber 5 also includes a protective cover 6, and a reflective layer is provided on the side of the protective cover 6 facing the processing area. The reflective layer can be a metal layer with high reflectivity or a non-metal layer, and the reflective layer can reflect the reflected light from the processing area back to the processing area. The protective cover 6 is provided with a window on the side corresponding to the light emitted by the first optical lens 3, and a second optical lens 13 is embedded in the window. The second optical lens 13 can include a bidirectional anisotropic optical lens. The second optical lens 13 can pass the laser emitted by the first optical lens 3 and irradiate the processing area. The second optical lens 13 can block the transmission of the light reflected from the processing area of ​​the forming chamber 5, and prevent the reflected light from the processing area from being reflected into the optical system 100. By providing a reflective layer on the side of the protective cover 6 facing the processing area, the reflected light from the processing area is reflected back to the processing area again, and the processing area is preheated by using the energy of the reflected laser, which can reduce the melting energy threshold of the target processing material, reduce the temperature gradient of the processing area, and improve the energy utilization rate. At the same time, by arranging a second optical lens on the side of the protective cover corresponding to the outgoing light of the first optical lens, the second optical lens is used as an isolation device of the optical system to prevent reflected light from being transmitted back along the optical path to the surface of the optical device in the optical path system, thereby protecting the optical system.

[0032] Usually, in the SLM forming process, high-reflectivity metals generally refer to metal materials with high reflectivity to commonly used infrared band lasers, such as copper alloys, aluminum alloys, gold and silver, etc. The processing of high-reflectivity metals usually adopts the method of increasing laser power and adjusting the laser incident angle to make the metal well formed and avoid damage to the optical path system caused by reflected light.

[0033] In the embodiment of the present application, a protective cover is provided in the forming chamber, and a reflective layer is provided on the side of the protective cover facing the processing area. The reflective layer has a high reflective performance and can reflect the reflected light from the processing area back to the processing area, and the energy of the reflected laser is used to preheat the processing area, thereby reducing the melting energy threshold of the target processing material and reducing the temperature gradient of the processing area, thereby improving the energy utilization rate. At the same time, a second optical lens is provided on the side of the protective cover corresponding to the light emitted by the first optical lens, and the second optical lens is used as an isolation device of the optical system to prevent the reflected light from being transmitted back along the optical path to the surface of the optical device in the optical path system, thereby protecting the optical system.

[0034] For example, Figure 1As shown, the forming chamber 5 may also include a powder feeding mechanism, a powder spreading mechanism 10, a powder spreading guide rail 11, a lifting mechanism and a lifting platform 9. The powder feeding mechanism 4 and the powder spreading mechanism 10 may be bidirectional powder spreading mechanisms, which can realize powder spreading in both left and right directions. The lifting platform 9 may be used as a powder bed of the forming chamber 5 for spreading powder. The area where the laser acts on the metal powder may be regarded as a processing area 400, that is, the processing area 400 is located above the lifting platform 9. One end of the powder feeding mechanism 4 is connected to the side wall of the protective cover 6, and the other end of the powder feeding mechanism 4 is embedded in the top of the forming chamber 5. The outlet of the powder feeding mechanism 4 is connected to the powder spreading mechanism 10, and the powder spreading mechanism 10 is used to move linearly along the powder spreading guide rail 11 to spread powder on the lifting platform 9. The powder dropping cylinder 7 is arranged on both sides of the powder spreading guide rail 11 to cooperate with the bidirectional powder spreading mechanism, so that excess powder enters the powder dropping cylinder 7, improves the powder spreading efficiency and reduces the excess powder in the forming chamber. The lifting mechanism is connected to the lifting platform 9, and the lifting mechanism is used to drive the lifting platform 9 to rise or fall in the forming cylinder 8 to adjust the thickness of the powder layer and the number of forming layers.

[0035] For example, Figure 1 As shown, the laser selective melting forming device of high-reflective metal in the present invention includes a laser source 1 and an optical system 100, a forming chamber 5, a powder feeding mechanism 4, a powder spreading mechanism 10, a powder spreading guide rail 11, a powder dropping cylinder 7, a forming cylinder 8, a lifting platform 9, and a protective cover 6 above the forming cylinder 8. Before laser processing, in the forming chamber 5, the metal powder falls into the powder spreading mechanism 10 through the powder feeding mechanism 4, and the powder spreading mechanism 10 moves linearly along the powder spreading guide rail 11 to spread the powder on the processing plane. After the powder is spread, the laser source 1 generates laser light, which enters the beam expander collimator 2 through optical fiber transmission, and passes through the scanning galvanometer and the first optical lens 3. At the same time, the control system controls the power of the laser and the running trajectory of the scanning galvanometer to achieve laser scanning of different paths and shapes. After a layer of metal powder is processed, the position of the lifting platform 9 in the forming cylinder 8 is controlled by the lifting mechanism to adjust the thickness of the powder layer and the number of forming layers. During the processing, the excess powder falls into the powder dropping cylinder 7 under the push of the two-way powder spreading mechanism 10. The reflected laser generated during the processing of high-reflective metals is reflected back to the processing area by the protective cover 6, realizing the laser selective melting of high-reflective metals. By adjusting the process parameters and processing paths on the control system, laser selective melting of different metals can be achieved.

[0036] Exemplarily, the powder feeding mechanism 4 is sealed with the forming chamber 5 through a silicone gasket to ensure the overall airtightness of the forming process, and powder is added through the rotating powder dropping shaft below the powder feeding mechanism 4. Under the control of the control system, the rotating powder dropping shaft of the powder feeding mechanism 4, the powder spreading mechanism 10 and the lifting platform 9 cooperate with each other to achieve the matching of the powder feeding amount and the processing layer thickness, and the optimization of the powder spreading speed and the powder spreading quality.

[0037] For example, the laser source 1 can emit a continuous power range of 50 to 2000 W and a power density of 1.6×10 9 W / cm 2 Up to 4.0×10 13 W / cm 2 The continuous laser is transmitted to the beam expander collimator 2, the scanning galvanometer and the first optical lens 3 through the optical fiber. The scanning galvanometer can perform laser scanning according to the scanning path pre-designed by the control system. After the laser passes through the first optical lens, it passes through the bidirectional anisotropic optical lens in the center of the protective cover 6 to melt and form the metal powder on the powder bed.

[0038] Exemplarily, the lifting platform 9 in the forming cylinder 8 can be driven by the lifting mechanism to process on different planes, and descend according to the preset value in the control system to achieve layer-by-layer processing. The adjustable range of the powder layer thickness is 20μm to 100μm, and the powder feeding amount is controlled in combination with the preset value of the rotation angle of the powder spreading mechanism to achieve a match between the powder layer thickness and the powder amount.

[0039] In some embodiments, the number of reflective layers of the protective cover 6 can be set according to the laser wavelength actually required for the forming process, and the reflective layer can include a single layer or multiple layers.

[0040] Exemplarily, the wavelength of lasers commonly used for forming processing ranges from ultraviolet to infrared, wherein the wavelength range from ultraviolet to infrared is 200nm to 1250nm. When the wavelength of the processing laser is 1064nm, the reflective layer is a single layer. When there is a half-wave loss, the actual thickness of the reflective layer is 1064×(2k+1) / 4n nm, wherein n is the refractive index of the film layer, and k is a constant, k=0, 1, 2, .... When there is no half-wave loss, its actual thickness is 1064×k / 2n nm, wherein n is the refractive index of the film layer, and k=0, 1, 2, ....

[0041] For example, when the wavelength of the processing laser is 1064 nm, the reflective film layer is a multi-layer high-reflective film, and its structure is GHLHLH…LHA=G(HL) p HA, p = 1, 2, 3, ..., where G represents the matrix, A represents air, H and L represent the high refractive index layer and the low refractive index layer respectively. When the wavelength is 1064nm, the optical thickness of the H layer and the L layer are both set to 266nm. The total actual thickness of the multilayer film system is 266×[(1+p) / n H +p / n L ]nm, where n H and n L represent the refractive indices of the H layer and the L layer respectively.

[0042] By arranging a single or multiple reflective layers on the protective cover, a better reflective effect can be obtained to achieve control of the reflection direction of the reflected light and utilization of the reflected light energy during the laser selective melting forming process.

[0043] In some embodiments, the surface of the protective cover facing the processing area includes a curved surface, and the focus of the curved surface is located on the side close to the processing area. Through the setting of the curved surface, on the one hand, the reflected light from the processing area can be evenly reflected to the processing area, and the reflected light can also be converged to the focus to achieve better processing effects.

[0044] Exemplarily, the surface of the protective cover 6 facing the processing area includes a parabola or a sphere. The curvature radius of the parabola is larger than the curvature radius of the sphere. The parabola protective cover has a more uniform reflection effect, and can reflect the processing reflected light of the focal plane back to the processing plane in the form of parallel light. The spherical protective cover has a lower cost, but the uniformity of the reflected light is slightly worse. The height size range of the forming cabin 5 is about 200mm to 1500mm, and different reflection focal lengths and surface shapes can be set according to the size and structure of the different forming cabins 5. When the size of the forming cabin is small, the maximum distance from the processing plane to the protective cover is short, and the required curvature radius of the protective cover 6 is small. Among them, the processing plane is the plane where the processing area 400 is located. In the case of a small curvature, the difference in the uniformity of the reflected light between the spherical protective cover and the parabolic protective cover is large, and it is more appropriate to choose a parabolic protective cover. When the size of the forming chamber is larger, the maximum distance between the protective cover 6 and the processing plane is farther, the required curvature radius of the protective cover 6 is larger, and the difference in the uniformity of reflected light between the spherical protective cover and the parabolic protective cover is smaller. Choosing a spherical protective cover can better reduce costs.

[0045] When the focal length of the parabola is the same as that of the sphere, the vertex of the parabola coincides with the vertex of the sphere, and the radius of curvature of the vertex of the parabola is equal to the radius of curvature of the sphere. The parabola protective cover has a more uniform reflection effect, and can reflect the processing reflected light of the focal plane back to the processing plane in the form of parallel light. The spherical protective cover has a lower cost, but the uniformity of the reflected light is slightly worse, so it is more appropriate to choose a parabola protective cover.

[0046] Exemplarily, the bidirectional anisotropic optical lens uses a plane lens to avoid changing the focal plane of the laser processing. The curvature of the protective cover 6 is determined according to the distance from the processing plane to the center of the protective cover. The distance range from the processing plane of the forming chamber 5 to the vertex of the protective cover is 200mm to 1500mm, and the maximum distance range from the processing plane to the protective cover is 200mm to 1500mm. The curvature radius of the protective cover is approximately 400mm to 3000mm.

[0047] Exemplarily, the range of the distance from the processing plane of the forming cabin 5 to the vertex of the protective cover is the maximum distance from the processing plane to the protective cover, and the range of the maximum distance from the processing plane to the protective cover 6 is 250mm to 1000mm. A forming cabin is considered to be small-sized if the distance from the plane where the processing area of ​​the forming cabin is located to the vertex of the protective cover is less than 500mm, and a forming cabin is considered to be large-sized if the distance from the plane where the processing area of ​​the forming cabin is located to the vertex of the protective cover is greater than or equal to 500mm. When the maximum distance from the plane where the processing area of ​​the forming cabin is located to the protective cover is 200mm, the surface of the protective cover 6 facing the processing area is spherical, the protective cover 6 is a spherical protective cover, the spherical focal length is 200mm, and the maximum spherical curvature radius is 400mm. When the maximum distance from the plane where the processing area of ​​the forming cabin is located to the protective cover is 250mm, the surface of the protective cover 6 facing the processing area is spherical, the protective cover 6 is a spherical protective cover, the spherical focal length is 250mm, and the maximum spherical curvature radius is 500mm. When the maximum distance from the plane where the processing area of ​​the forming cabin is located to the protective cover is 1000mm, the spherical focal length is 1000mm, and the maximum curvature radius of the spherical surface is 2000mm. When the maximum distance from the plane where the processing area of ​​the forming cabin is located to the protective cover is 1500mm, the surface of the protective cover 6 facing the processing area is spherical, and the protective cover 6 is a spherical protective cover, with a spherical focal length of 1500mm and a maximum curvature radius of 3000mm. By setting the surface of the protective cover facing the processing area, different forming cabin requirements can be met, so that the sizes of the melt-formed products are different, thereby achieving diversity in product processing.

[0048] For example, different reflection focal lengths and surface shapes can be set according to different forming chamber sizes and structures. When the forming chamber size is small, the focal width ratio of the shield is less than 5, and the reflected light uniformity difference between the spherical shield mirror and the parabolic shield is large, so it is more appropriate to choose a parabolic shield. When the forming chamber size is large, the focal width ratio of the shield is greater than 5, the distance between the shield vertex and the processing plane is far, and the reflected light uniformity difference between the spherical shield and the parabolic shield is small. Choosing a spherical shield can better reduce costs. Among them, the focal width ratio is the ratio of the focal length to the half width of the shield, and half of the maximum width of the shield facing the processing area is the half width of the shield.

[0049] In some embodiments, a window matching the size of the galvanometer and the first optical lens is provided at the axial position of the protective cover 6, the diameter of the window is larger than the diameter of the first optical lens 3, and the center line of the window coincides with the center line of the protective cover so that all the laser emitted by the first optical lens 3 can enter the forming chamber 5, thereby avoiding laser loss during transmission and improving laser utilization.

[0050] Exemplarily, the second optical lens 13 includes a planar one-way lens, which may be a bidirectional anisotropic optical lens. The second optical lens 13 is sealed and connected to the window, which may provide a good sealing environment for the forming chamber 5. The second optical lens 13 may serve as an optical isolator between the forming chamber and the optical system, so that the processing laser emitted from the optical system is transmitted and irradiated to the processing area, and at the same time reflects the reflected light generated during the high-reflective metal SLM forming process, thereby protecting the optical path system.

[0051] For example, Figure 1 and 2 As shown, the protective cover 6 is embedded in the top of the forming chamber 5, and a water cooling channel 14 is embedded in the protective cover 6. The water cooling channel 14 changes along the curved surface shape of the protective cover. There are multiple water cooling channels, and multiple water cooling channels extend along the curved surface toward the processing area. The surface of multiple water cooling channels 14 facing the processing area is a curved surface, and the water cooling channels are curved and run through the protective cover 6. Multiple water cooling channels are arranged on both sides of the second optical lens 13 along the width direction X of the protective cover 6. The water cooling channel 14 is arranged close to the reflective layer side of the protective cover 6. The water cooling channel 14 can be a single-layer channel or a multi-layer channel. The water cooling channel 14 can be connected to an external water source to form a circulating water flow channel to increase the reflectivity of the corresponding laser wavelength, reduce the absorption of reflected light by the laser protective cover 6, and avoid thermal effects and thermal damage to the protective cover. The top of the shaping chamber 5 is arranged on the side of the processing area close to the optical system 100, and the optical system 100 is embedded in the top of the light shaping chamber 5 to reduce the distance between the optical system 100 and the shaping chamber 5, so as to avoid long-distance transmission of the laser in the optical system and affect the beam quality.

[0052] In some embodiments, the center line of the lifting platform 9, the center line of the processing area, and the center line of the protective cover 6 coincide with each other.

[0053] Figure 3 A schematic optical path diagram of a protective cover provided in an embodiment of the present application. For example, Figures 1 to 3 As shown in the figure, during the processing, considering the influence of the random distribution of the morphology of the processing area and the forming cylinder 8 on the laser reflection, the center of the protective cover corresponds to the center position of the forming cylinder 8 and the lifting platform 9. The center line of the lifting platform 9, the center line of the processing area and the center line of the protective cover 6 are set to coincide, so that all the reflected light in the processing process is Lambertian in overall distribution, that is, Figure 3 The middle protective cover 6 can reflect the reflected light from the processing plane back to the processing plane for a second time, and the intensity of the reflected light is evenly distributed. The energy of the reflected light is used to preheat the processing plane, reduce the melting energy threshold of the target processing material, and reduce the temperature gradient in the processing area, thereby improving energy utilization.

[0054] In some embodiments, the present application provides a method for preparing copper alloy / pure copper by laser selective melting. Exemplarily, the preparation method is as follows:

[0055] S1: adjusting the processing plane of the lifting platform 9 so that the processing plane remains horizontal, and passing high-purity argon gas into the forming chamber 5 so that the oxygen content in the chamber is less than 500ppm;

[0056] S2: The control system controls the powder spreading shaft of the powder spreading mechanism to rotate according to a preset value, so that a sufficient amount of copper alloy or pure copper powder falls from the powder feeding mechanism 4 into the powder spreading mechanism 10, and the powder spreading mechanism 10 moves from right to left and completes the powder spreading on the processing plane;

[0057] S3: The laser source 1 emits a laser with a power of 500W, which is transmitted through the optical fiber to the beam expander collimator 2, the scanning galvanometer and the optical system 100. The scanning galvanometer performs laser scanning according to the scanning path pre-designed by the control system. After the laser passes through the first optical lens 3, it passes through the second optical lens 13 in the center of the protective cover 6 to melt and form the processing area.

[0058] S4: After the current layer is processed, the lifting platform 9 descends by a layer thickness, and the powder spreading mechanism 10 moves from left to right and completes the powder spreading on the processed surface.

[0059] S5: Repeat the S3 processing step.

[0060] S6: Repeat processing steps S2 to S5.

[0061] S7: During the processing, argon gas is continuously circulated inside the forming chamber 5 to keep the oxygen content below 200ppm during the processing, remove the metal vapor and smoke generated during the processing, and prevent the vapor and smoke from adhering to the surface of the protective cover facing the processing area to avoid reducing the surface reflectivity and thus causing damage to the reflector. At the same time, ensure that the powder in the powder feeding mechanism 4 is sufficient and the airtightness of the forming chamber 5 is ensured, and according to the preset parameters of the control system and the running trajectory of the scanning galvanometer, realize layer-by-layer cumulative melting and forming until the processing and forming of the copper alloy / pure copper parts are completed.

[0062] In some embodiments, the present application provides a method for preparing an aluminum alloy formed by laser selective melting. Exemplarily, the preparation method is as follows:

[0063] S1: Adjust the processing plane of the lifting platform 9 so that the processing plane remains horizontal, and pass high-purity argon gas into the forming chamber 5 so that the oxygen content in the chamber is less than 500ppm.

[0064] S2: The control system controls the powder spreading shaft in the powder spreading mechanism 10 to rotate according to a preset value, so that a sufficient amount of aluminum alloy powder falls from the powder spreading mechanism 10 and enters the powder spreading mechanism 10. The powder spreading mechanism 10 moves from right to left and completes powder spreading on the processing plane.

[0065] S3: The laser source 1 emits a laser with a laser power of 250W, which is transmitted to the beam expander collimator 2, the scanning galvanometer and the optical system 100 through the optical fiber. The scanning galvanometer performs laser scanning according to the scanning path pre-designed by the control system. After the laser passes through the first optical lens 3, it passes through the second optical lens 13 in the center of the protective cover 6 to melt and form the processing area.

[0066] S4: After the current layer is processed, the lifting platform 9 descends by a layer thickness, and the powder spreading mechanism 10 moves from left to right and completes the powder spreading on the processed surface.

[0067] S5: Repeat the S3 processing step.

[0068] S6: Repeat processing steps S2 to S5.

[0069] S7: During the processing, argon gas is continuously circulated inside the forming chamber 5 to keep the oxygen content below 200ppm during the processing, remove the metal vapor and smoke generated during the processing, and prevent the vapor and smoke from adhering to the surface of the protective cover facing the processing area to avoid reducing the surface reflectivity and thus causing damage to the reflector. At the same time, ensure that the powder in the powder feeding mechanism 4 is sufficient and the airtightness of the forming chamber 5 is ensured, and according to the preset parameters of the control system and the running trajectory of the scanning galvanometer, realize layer-by-layer cumulative melting and forming until the processing and forming of the copper alloy / pure copper parts are completed.

[0070] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0071] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

[0072] Although the preferred embodiments of this specification have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of this specification.

[0073] Obviously, those skilled in the art can make various changes and modifications to this specification without departing from the spirit and scope of this specification. Thus, if these modifications and variations of this specification fall within the scope of the claims of this specification and their equivalents, this specification is also intended to include these modifications and variations.

Claims

1. A laser selective melting forming device, characterized in that: include: Laser source; An optical system, wherein the optical system comprises a scanning galvanometer and a first optical lens, wherein the laser source is disposed on a side of the scanning galvanometer away from the first optical lens, and the laser emitted by the laser source is transmitted to the first optical lens via the scanning galvanometer; A forming chamber, wherein the forming chamber is connected to the optical system, and the laser emitted by the first optical lens is transmitted to a processing area of ​​the forming chamber, so that a target processing material in the processing area is melted and formed; The forming chamber includes a protective cover, a reflective layer is arranged on the side of the protective cover facing the processing area, the protective cover is provided with a window corresponding to the area where the first optical lens emits light, a second optical lens is arranged in the window, the second optical lens is used to transmit the laser emitted by the first optical lens to the processing area, and the second optical lens is used to block the transmission of light in the forming chamber.

2. The laser selective melting forming device according to claim 1, characterized in that: The surface of the protective cover facing the processing area includes a curved surface, and the focus of the curved surface is located on a side close to the processing area.

3. The laser selective melting forming device according to claim 2, characterized in that: The curved surface includes a parabola or a spherical surface; The radius of curvature of the parabola is greater than or equal to the radius of curvature of the spherical surface.

4. The laser selective melting forming device according to claim 3, characterized in that: The second optical lens comprises a planar one-way lens, the second optical lens is sealed to the window, and the center line of the window coincides with the center line of the protective cover.

5. The laser selective melting forming device according to claim 1, characterized in that: The protective cover is embedded in the top of the forming chamber, a water cooling channel is embedded in the protective cover, the top of the forming chamber is arranged on a side of the protective cover close to the optical system, and the optical system is embedded in the top of the forming chamber.

6. The laser selective melting forming device according to claim 1, characterized in that: The optical system further comprises a quasi-beam expanding collimating mirror, and the beam expanding collimating mirror is arranged between the laser source and the scanning galvanometer.

7. The laser selective melting forming device according to claim 1, characterized in that: The forming chamber also includes a powder feeding mechanism, a powder spreading mechanism, a powder spreading guide rail, a lifting mechanism and a lifting platform. One end of the powder feeding mechanism is connected to the side wall of the protective cover, and the other end of the powder feeding mechanism is embedded in the top of the forming chamber. The outlet of the powder feeding mechanism is connected to the powder spreading mechanism. The powder spreading mechanism is used to move along the powder spreading guide rail to spread powder in the processing area. The lifting mechanism is connected to the lifting platform. The lifting mechanism is used to adjust the rise or fall of the lifting platform to adjust the thickness of the powder.

8. The laser selective melting forming device according to claim 7, characterized in that: The center line of the lifting platform, the center line of the processing area and the center line of the protective cover coincide with each other.

9. The laser selective melting forming device according to claim 8, characterized in that: The forming chamber is a sealed chamber, and the oxygen content in the forming chamber is less than 500 ppm.

10. The selective laser melting forming device according to claim 5, characterized in that: The laser source emits a laser with a wavelength ranging from 200 nm to 1250 nm; and / or, The wavelength range of the reflected light of the reflective layer is 200nm to 1250nm; and / or, The curvature radius of the protective cover ranges from 400 mm to 3000 mm.

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