Single-mode and multi-mode laser coupling processing device for SLM (selective laser melting)

Abstract

The utility model discloses a single-mode and multi-mode laser coupling processing device for SLM. The device comprises a single-mode fiber laser, a multi-mode fiber laser, a beam coupler and a focusing lens. Wherein the single-mode fiber laser emits a single-mode light beam, the multi-mode fiber laser emits a multi-mode light beam, the light beam coupler is used for coupling the single-mode light beam and the multi-mode light beam, the single-mode light beam and the multi-mode light beam are coaxial, and the single-mode light beam is located at the center of the multi-mode light beam. The focusing lens is used for focusing the light beam on the to-be-formed part. According to the invention, the single-mode fiber laser and the multi-mode fiber laser are integrated into a whole, a region with a high precision requirement is irradiated by a single-mode light beam, a region with a high efficiency requirement is irradiated by a multi-mode light beam, and a combined light beam of the single-mode light beam and the multi-mode light beam can be adopted to further improve the forming quality of parts. Various requirements in the SLM part forming process can be met, two sets of independent laser irradiation systems do not need to be arranged, and the equipment cost is saved.

Description

Technical Field

[0001] The present application relates to the technical field of metal 3D printing, and in particular to a single-mode and multi-mode laser coupling processing device for SLM. Background Art

[0002] Metal additive manufacturing technology does not require the addition of various fixtures or tools, the equipment is small in size, and has a high degree of design freedom. It can form complex structures, has a short production cycle, and has a high material utilization rate. It has been widely used in many fields such as jewelry, aerospace, and biomedicine. Among them, the selective laser melting (SLM) technology is a metal additive manufacturing technology that has developed rapidly in recent years due to its high processing accuracy, excellent forming quality and mechanical properties.

[0003] At present, most SLM equipment uses lasers with a spot diameter in the range of 60 to 100 μm after being focused by a lens. A smaller spot diameter is conducive to improving processing accuracy and facilitating the forming of complex parts, such as grids and porous structures. However, a small beam will consume more time when filling entities, especially entities with larger areas, and the temperature gradient will be larger when scanning with a smaller diameter spot, which is prone to defects such as pores and cracks, thus affecting the forming quality. Laser processing using a larger diameter spot can reduce the temperature gradient in the forming area and avoid defects such as cracks and warping caused by stress concentration. However, the power of the current commercial single-mode laser is less than 1000 W. When the laser beam is adjusted to a larger spot, the body energy density will be greatly reduced, making it difficult to process high-melting-point alloy materials.

[0004] Single-mode laser and multi-mode laser each have their own advantages and disadvantages. Using different laser modes for different parts can effectively improve the molding quality of parts. However, for some parts with complex structures and large sizes, it is necessary to frequently change the two laser modes during the processing, which is more time-consuming; or use two sets of independent laser heads, which undoubtedly increases the manufacturing cost. Summary of the invention

[0005] The purpose of the present application is to solve at least one of the technical problems existing in the prior art and to provide a single-mode and multi-mode laser coupling processing device for SLM, which can ensure the quality of part molding while improving the processing efficiency of the parts and reducing production costs.

[0006] According to an embodiment of the present application, there is provided a single-mode and multi-mode laser coupling processing device for SLM, comprising a single-mode fiber laser, a multi-mode fiber laser, a beam coupler and a focusing lens;

[0007] The beam coupler transitions from a first surface to a second surface along a thickness direction thereof, the first surface of the beam coupler is covered with a total reflection film, the second surface of the beam coupler is covered with a total transmission film, the light beam emitted by the single-mode fiber laser is reflected by the total reflection film to obtain a single-mode light beam, the light beam emitted by the multi-mode fiber laser passes through the total transmission film to obtain a multi-mode light beam, the single-mode light beam is coaxial with the multi-mode light beam and the single-mode light beam is located at the center of the multi-mode light beam;

[0008] The single-mode light beam, the multi-mode light beam, or a combined light beam of the single-mode light beam and the multi-mode light beam passes through the focusing lens, and the focusing lens focuses the light beam on the part to be molded.

[0009] According to an embodiment of the present application, further, the single-mode and multi-mode laser coupling processing device for SLM also includes a scanning galvanometer, which is arranged between the beam coupler and the focusing lens, and the scanning galvanometer is used to reflect the light beam emitted from the beam coupler to the focusing lens.

[0010] According to an embodiment of the present application, further, the scanning galvanometer has a rotation axis and can rotate around its rotation axis to adjust the reflection angle of the light beam.

[0011] According to an embodiment of the present application, further, the scanning galvanometer has a first rotation axis and a second rotation axis that are perpendicular to each other, and the single-mode and multi-mode laser coupling processing device for SLM also includes a first servo motor and a second servo motor, wherein the first servo motor drives the scanning galvanometer to rotate around the first rotation axis, and the second servo motor drives the scanning galvanometer to rotate around the second rotation axis.

[0012] According to an embodiment of the present application, further, the single-mode and multi-mode laser coupling processing device for SLM includes a height adjustment mechanism, the focusing lens is installed on the height adjustment mechanism, and the height adjustment mechanism is used to drive the focusing lens to move along the optical path direction of the light beam to change the focal position.

[0013] According to an embodiment of the present application, further, the single-mode and multi-mode laser coupling processing device for SLM also includes a first collimating beam expander, which is arranged between the single-mode fiber laser and the beam coupler, and the first collimating beam expander is used to adjust the morphology of the light beam emitted by the single-mode fiber laser.

[0014] According to an embodiment of the present application, further, the single-mode and multi-mode laser coupling processing device for SLM also includes a second collimating beam expander, which is arranged between the multi-mode fiber laser and the beam coupler, and the second collimating beam expander is used to adjust the morphology of the light beam emitted by the multi-mode fiber laser.

[0015] The beneficial effects of the embodiments of the present application include at least: the present application integrates a single-mode fiber laser and a multi-mode fiber laser into one, adopts a single-mode beam to irradiate areas with high precision requirements, and adopts a multi-mode beam to irradiate areas with high efficiency requirements. In addition, a combination of a single-mode beam and a multi-mode beam can be used to further improve the quality of part molding, which can meet various requirements in the SLM part molding process, and there is no need to set up two independent laser irradiation systems, thereby saving equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief description of the drawings required for use in the description of the embodiments. Obviously, the drawings described are only part of the embodiments of the present application, not all of the embodiments, and those skilled in the art can also obtain other design solutions and drawings based on these drawings without creative work.

[0017] Figure 1 It is a schematic diagram of the structure of a single-mode and multi-mode laser coupling processing device for SLM according to an embodiment of the present application;

[0018] Figure 2 It is a schematic diagram of the irradiation range of the single-mode light beam 110 and the multi-mode light beam 210 in the single-mode and multi-mode laser coupling processing device for SLM in an embodiment of the present application;

[0019] Figure 3 It is a workflow diagram of a single-mode and multi-mode laser coupling processing device for SLM according to an embodiment of the present application.

[0020] Reference numerals: 100 - single-mode fiber laser, 110 - single-mode light beam, 200 - multi-mode fiber laser, 210 - multi-mode light beam, 300 - beam coupler, 400 - focusing lens, 500 - scanning galvanometer, 600 - first collimating beam expander, 700 - second collimating beam expander. DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the present application. The preferred embodiments of the present application are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present application, but it cannot be understood as a limitation on the scope of protection of the present application.

[0022] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0024] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0025] At present, most SLM equipment uses lasers with a spot diameter in the range of 60 to 100 μm after being focused by a lens. A smaller spot diameter is conducive to improving processing accuracy and facilitating the forming of complex parts, such as grids and porous structures. However, a small beam will consume more time when filling entities, especially entities with larger areas, and the temperature gradient will be larger when scanning with a smaller diameter spot, which is prone to defects such as pores and cracks, thus affecting the forming quality. Laser processing using a larger diameter spot can reduce the temperature gradient in the forming area and avoid defects such as cracks and warping caused by stress concentration. However, the power of the current commercial single-mode laser is less than 1000 W. When the laser beam is adjusted to a larger spot, the body energy density will be greatly reduced, making it difficult to process high-melting-point alloy materials.

[0026] Single-mode laser and multi-mode laser each have their own advantages and disadvantages. Using different laser modes for different parts can effectively improve the molding quality of parts. However, for some parts with complex structures and large sizes, it is necessary to frequently change the two laser modes during the processing, which is more time-consuming; or use two sets of independent laser heads, which undoubtedly increases the manufacturing cost.

[0027] In this regard, the present application proposes a single-mode and multi-mode laser coupling processing device for SLM, which integrates a single-mode fiber laser 100 and a multi-mode fiber laser 200 into one, and uses a single-mode beam 110 to irradiate areas with high precision requirements, and a multi-mode beam 210 to irradiate areas with high efficiency requirements. In addition, a combined beam of the single-mode beam 110 and the multi-mode beam 210 can be used to further improve the molding quality of parts, which can meet various requirements in the SLM part molding process, and there is no need to set up two independent laser irradiation systems, thereby saving equipment costs.

[0028] Reference Figure 1 The single-mode and multi-mode laser coupling processing device for SLM in the embodiment of the present application includes a single-mode fiber laser 100, a multi-mode fiber laser 200, a beam coupler 300 and a focusing lens 400.

[0029] The beam coupler 300 transitions from the first surface to the second surface along the thickness direction thereof. The first surface of the beam coupler 300 is covered with a total reflection film, and the second surface of the beam coupler 300 is covered with a total transmission film. The light beam emitted by the single-mode fiber laser 100 is reflected by the total reflection film to obtain a single-mode light beam 110, and the light beam emitted by the multi-mode fiber laser 200 passes through the total transmission film to obtain a multi-mode light beam 210. It is worth noting that, referring to Figure 2 , the single-mode light beam 110 is coaxial with the multi-mode light beam 210 and the single-mode light beam 110 is located at the center of the multi-mode light beam 210. When in use, only the single-mode fiber laser 100 can be turned on to irradiate the surface of the part to be processed with the single-mode light beam 110, or only the multi-mode fiber laser 200 can be turned on to irradiate the surface of the part to be processed with the multi-mode light beam 210, or the single-mode fiber laser 100 and the multi-mode fiber laser 200 can be turned on at the same time to irradiate the surface of the part to be processed with a combined light beam of the single-mode light beam 110 and the multi-mode light beam 210.

[0030] Specifically, the spot of the single-mode beam 110 is a Gaussian laser with a smaller diameter, less than 100 μm, and a laser power less than 500 W. The spot of the multi-mode beam 210 is a flat-top laser with a larger diameter, greater than 200 μm, and a laser power greater than 2000 W.

[0031] The single-mode light beam 110 , the multi-mode light beam 210 , or a combined light beam of the single-mode light beam 110 and the multi-mode light beam 210 passes through the focusing lens 400 , and the focusing lens 400 focuses the light beam on the part to be formed to complete laser additive manufacturing.

[0032] Furthermore, the single-mode and multi-mode laser coupling processing device for SLM also includes a scanning galvanometer 500, which is disposed between the beam coupler 300 and the focusing lens 400 and is used to reflect the light beam emitted from the beam coupler 300 into the focusing lens 400. Moreover, the scanning galvanometer 500 has a rotation axis and can rotate around its rotation axis, so that the reflection angle of the light beam can be adjusted to allow it to be more accurately emitted into the focusing lens 400.

[0033] Furthermore, the scanning galvanometer 500 has a first rotation axis and a second rotation axis that are perpendicular to each other. The single-mode and multi-mode laser coupling processing device for SLM also includes a first servo motor and a second servo motor, wherein the first servo motor drives the scanning galvanometer 500 to rotate around the first rotation axis, and the second servo motor drives the scanning galvanometer 500 to rotate around the second rotation axis, thereby being able to meet more angle adjustment requirements.

[0034] Furthermore, the single-mode and multi-mode laser coupling processing device for SLM includes a height adjustment mechanism, and the focusing lens 400 is installed on the height adjustment mechanism. The height adjustment mechanism is used to drive the focusing lens 400 to move along the optical path direction of the light beam to change the focal position, thereby ensuring that the focal point of the light beam is located on the surface of the part to be processed.

[0035] Furthermore, the single-mode and multi-mode laser coupling processing device for SLM also includes a first collimating beam expander 600, which is arranged between the single-mode fiber laser 100 and the beam coupler 300, and is used to adjust the morphology of the light beam emitted by the single-mode fiber laser 100.

[0036] Furthermore, the single-mode and multi-mode laser coupling processing device for SLM also includes a second collimating beam expander 700, which is arranged between the multi-mode fiber laser 200 and the beam coupler 300, and is used to adjust the morphology of the light beam emitted by the multi-mode fiber laser 200.

[0037] Below, refer to Figure 3 , the workflow of the single-mode and multi-mode laser coupling processing device for SLM is introduced, which includes the following steps:

[0038] S100. Establish a three-dimensional model of the part, slice the three-dimensional model to be processed to obtain multiple slice layers and corresponding contour information and save them as slice files;

[0039] S200. Import the slice file into the control software in the SLM device, the control software reads and saves the contour of each layer in the slice file, and divides the contour into a fine processing area, a high-efficiency processing area and a contour scanning area according to the slice contour information of each layer;

[0040] S300. Turn on the multimode fiber laser 200 and use the multimode beam 210 to perform additive manufacturing on the efficient processing area;

[0041] S400. Turn on the single-mode fiber laser 100 and use the single-mode beam 110 to perform additive manufacturing on the fine processing area;

[0042] S500. Turn on the single-mode fiber laser 100 and perform additive manufacturing on the contour scanning area using the single-mode beam 110;

[0043] S600. Lift the single-mode and multi-mode laser coupling processing device for SLM, and perform the operations from S300 to S500 on the next layer of contour until all layers of contour are processed.

[0044] Further, for the classification of fine processing area, efficient processing area and contour scanning area: the fine processing area includes narrow area and small area. The narrow area refers to the area where the contour width is less than the set threshold or less than the spot diameter of the multimode fiber laser; the small area refers to the area where the closed area is less than the set threshold. The contour scanning area refers to the outer contour area of ​​the slice layer. The efficient processing area refers to the remaining area in the slice layer after removing the fine processing area and the contour scanning area.

[0045] Furthermore, in step S600, when processing the next layer of contour, the single-mode and multi-mode laser coupling processing device used for SLM is rotated so that the angle between the light beam and the surface of the part to be processed changes, so as to reduce the accumulation of thermal stress caused by the overlap of the scanning lines of adjacent layers.

[0046] Furthermore, for the fine processing area and the contour scanning area, the single-mode fiber laser 100 and the multi-mode fiber laser 200 can be turned on at the same time, and the combined beams of the two can be used for composite processing. During the processing, the single-mode beam 110 is mainly used to melt the metal powder, and the multi-mode beam 210 can preheat the powder on the scanning path to reduce the temperature gradient between the powder and the molten pool, thereby improving the forming quality of the part.

[0047] The above is a specific description of the preferred implementation methods of the present application, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present application, and these equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A single-mode and multi-mode laser coupling processing device for SLM, characterized in that: Includes single-mode fiber lasers, multi-mode fiber lasers, beam couplers, and focusing lenses; The beam coupler transitions from a first surface to a second surface along a thickness direction thereof, the first surface of the beam coupler is covered with a total reflection film, the second surface of the beam coupler is covered with a total transmission film, the light beam emitted by the single-mode fiber laser is reflected by the total reflection film to obtain a single-mode light beam, the light beam emitted by the multi-mode fiber laser passes through the total transmission film to obtain a multi-mode light beam, the single-mode light beam is coaxial with the multi-mode light beam and the single-mode light beam is located at the center of the multi-mode light beam; The single-mode light beam, the multi-mode light beam, or a combined light beam of the single-mode light beam and the multi-mode light beam passes through the focusing lens, and the focusing lens focuses the light beam on the part to be molded.

2. The single-mode and multi-mode laser coupling processing device for SLM according to claim 1, characterized in that: The single-mode and multi-mode laser coupling processing device for SLM also includes a scanning galvanometer, which is arranged between the beam coupler and the focusing lens, and is used to reflect the light beam emitted from the beam coupler to the focusing lens.

3. The single-mode and multi-mode laser coupling processing device for SLM according to claim 2, characterized in that: The scanning galvanometer has a rotation axis and can rotate around the rotation axis to adjust the reflection angle of the light beam.

4. The single-mode and multi-mode laser coupling processing device for SLM according to claim 3, characterized in that: The scanning galvanometer has a first rotation axis and a second rotation axis that are perpendicular to each other. The single-mode and multi-mode laser coupling processing device for SLM also includes a first servo motor and a second servo motor, wherein the first servo motor drives the scanning galvanometer to rotate around the first rotation axis, and the second servo motor drives the scanning galvanometer to rotate around the second rotation axis.

5. The single-mode and multi-mode laser coupling processing device for SLM according to claim 1, characterized in that: The single-mode and multi-mode laser coupling processing device for SLM includes a height adjustment mechanism, the focusing lens is installed on the height adjustment mechanism, and the height adjustment mechanism is used to drive the focusing lens to move along the optical path direction of the light beam to change the focal position.

6. The single-mode and multi-mode laser coupling processing device for SLM according to claim 1, characterized in that: The single-mode and multi-mode laser coupling processing device for SLM also includes a first collimating beam expander, which is arranged between the single-mode fiber laser and the beam coupler, and is used to adjust the morphology of the light beam emitted by the single-mode fiber laser.

7. The single-mode and multi-mode laser coupling processing device for SLM according to claim 1, characterized in that: The single-mode and multi-mode laser coupling processing device for SLM also includes a second collimating beam expander, which is arranged between the multi-mode fiber laser and the beam coupler, and is used to adjust the morphology of the light beam emitted by the multi-mode fiber laser.

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