Laser optical path adjustment device and forming method for laser powder bed fusion additive manufacturing

Abstract

A laser optical path adjustment device and forming method for laser powder bed fusion additive manufacturing, including a selection valve box, a laser beam outlet at the front end of the selection valve box is provided with a plane mirror, and two optical fiber head connection ports at the rear end of the selection valve box are respectively connected to a low-power laser optical fiber head and a high-power laser optical fiber head. The high-power laser beam input by the high-power laser optical fiber head is emitted from the laser beam outlet through a beam expander, a second reflector, a third reflector, and a plane mirror. The low-power laser beam input by the low-power laser optical fiber head is emitted from the laser beam outlet through a first reflector, a third reflector, and a plane mirror. The third reflector can be rotated to change its angle. The forming method includes a large spot filling printing mode and a large spot preheating mode. The present invention can not only improve the printing efficiency of additive manufacturing, but also ensure the performance of printed parts.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a laser optical path adjustment device and a forming method for laser powder bed melting additive manufacturing. Background Art

[0002] Laser powder bed fusion (LPBF), an advanced additive manufacturing technology, uses lasers as the energy source and metal powder as the printing material. Under the heat of the laser beam, the metal powder is completely melted, rapidly solidified, and then additively molded layer by layer. LPBF has attracted widespread attention due to its advantages, including high precision, excellent surface quality, and superior performance. The general process of LPBF printing is as follows: first, the 3D model of the part is converted into a slice file to obtain the forming information for each cross-section. Then, a powder laying system deposits a layer of powder on a substrate according to the set layer thickness. A high-energy laser beam then selectively melts the metal powder based on the slice forming information, completing the current layer. The substrate then moves down a layer, and a new round of powder laying and scanning begins, producing the entire part layer by layer. During the LPBF process, the build chamber is filled with inert gas to prevent high-temperature oxidation of the metal. Improving printing efficiency while ensuring the performance of the printed part is a key concern for laser powder bed fusion technology.

[0003] To improve printing efficiency, the existing solutions mainly adopt variable spot printing. The printing area of ​​each cross section of the part can be divided into two parts: one is the shape line area, and the other is the internal filling area, such as Figure 1 As shown, the two printing areas correspond to the outline and fill lines, respectively. It can be seen intuitively that the area of ​​the internal fill area is much larger than that of the shape line area, and the number of fill lines is also much larger than the number of outline lines. Therefore, in order to improve printing efficiency while ensuring part performance, different printing strategies are required for the shape line area and the internal fill area. The purpose of variable spot printing is to use a small spot of a low-power laser to print the shape line area, and to use a large spot of a high-power laser to fill the internal fill area as much as possible. This increases the spacing between adjacent fill lines, thereby reducing the number of fill lines and improving printing efficiency. For example, the patent application entitled "A Dual Laser Single Galvanometer Printing System and Method" (Publication No. CN218799127U) adds two collimating lenses and a new galvanometer unit. The two collimating lenses change the spot size of the incident laser emitted by a low-power, high-beam-quality laser and a high-power laser, respectively, and make the two laser beams intersect. The newly added x-axis and y-axis galvanometer units are driven by motors to change their angles, so that the optical paths of the low-power laser beam and the high-power laser beam coincide, thereby achieving variable spot printing to improve printing efficiency.

[0004] Taking all factors into consideration, the above scheme has the following disadvantages: 1) The installation and layout of two or more collimating lenses has not been considered. The newly added unit is difficult to integrate with the original galvanometer system of the equipment, and it is difficult to be applied in printing equipment with space layout requirements; 2) The optical path stability of the laser powder bed melting equipment is a prerequisite for ensuring the stable quality of the formed parts. The newly added x-axis and y-axis galvanometer units are driven by ordinary motors to achieve angle changes. There are many problems such as difficulty in coordinated control of dual motors, slow motor response speed, low position resolution, and magnetic disturbance. As a result, the optical paths of low-power laser beams and high-power laser beams do not overlap, which directly affects the quality of the parts. The quality stability of the shaped parts; 3) Although a single galvanometer system is adopted, the new x-axis and y-axis galvanometer units are added, which further increases the overall complexity of the galvanometer system. For additive manufacturing technology with extremely high equipment reliability requirements, the failure rate and maintenance difficulty are greatly increased; 4) The splicing problem of variable spot printing is an important reason affecting the performance of printed parts. Due to the obvious uneven distribution of large spot energy, the joints of the internal filling area and the shape line area inevitably have problems of low splicing accuracy and poor stability, and the performance of the parts cannot be guaranteed; 5) The difficult-to-form materials are not preheated during the printing process, and cracks are prone to appear on the surface of the forming layer. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a laser optical path adjustment device and forming method for laser powder bed fusion additive manufacturing. Under the premise of ensuring the performance of printed parts, the difficulty and failure rate of device maintenance are reduced, the printing efficiency of the internal filling area during the additive manufacturing process is improved, and it can be applied to printing equipment with spatial layout requirements.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A laser optical path adjustment device for laser powder bed fusion additive manufacturing includes a selection valve box 1, a laser beam outlet at the front end of the selection valve box 1 is provided with a plane mirror 2, and two optical fiber head connection ports at the rear end of the selection valve box 1 are respectively connected to a low-power laser optical fiber head 14 and a high-power laser optical fiber head 15. A high-power laser beam 23 input by the high-power laser optical fiber head 15 is emitted from the laser beam outlet through a beam expander 12, a second reflector 8, a third reflector 10, and a plane mirror 2. A low-power laser beam 24 input by the low-power laser optical fiber head 14 is emitted from the laser beam outlet through a first reflector 6, a third reflector 10, and a plane mirror 2. The third reflector 10 can be rotated to change its angle.

[0008] The low-power laser fiber head 14 and the high-power laser fiber head 15 are connected to the selector valve housing 1 via the fiber support plate 3 by laser welding.

[0009] The third reflector 10 is connected to the piezoelectric ceramic ultrasonic motor 4 , the piezoelectric ceramic ultrasonic motor 4 is connected to the motor fixing plate 5 , and the motor fixing plate 5 is connected to the selection valve housing 1 by laser welding.

[0010] The first reflector 6 is connected to the first rectangular rod 7, and both ends of the first rectangular rod 7 are connected to the selection valve box 1; the second reflector 8 is connected to the second rectangular rod 9, and both ends of the second rectangular rod 9 are connected to the selection valve box 1; the third reflector 10 is connected to the rotating rod 11, and the rotating rod 11 is connected to the piezoelectric ceramic ultrasonic motor 4.

[0011] The rotating rod 11 is designed with an internal structure by using a lattice optimization method and is manufactured by using an additive manufacturing method.

[0012] The beam expander 12 is fixed on a beam expander bracket 13 , and the beam expander bracket 13 is connected to the selection valve box 1 .

[0013] The first reflector 6 , the second reflector 8 and the third reflector 10 are all square in shape, with their centroids located on the same vertical line, and the area of ​​their reflective surfaces is more than 100 times the area of ​​the laser spot.

[0014] The first reflector 6, the second reflector 8 and the third reflector 10 are all made of high-purity UV fused quartz substrate and coated with ultra-high laser-induced damage threshold dielectric film, which can withstand high-energy pulses, an incident angle of 0-45°, and a reflectivity of more than 99%.

[0015] The low power laser adopts a beam quality M 2 The single-mode fiber laser has a power of 400-800W and a wavelength of less than 1.2. The high-power laser uses a fiber laser with a power of more than 4000W.

[0016] A forming method using the laser optical path adjustment device for laser powder bed fusion additive manufacturing includes a large spot filling printing mode forming method and a large spot preheating mode forming method;

[0017] The method for forming a large light spot filling printing pattern comprises the following steps:

[0018] S1. Connect the low-power laser fiber head 14 and the high-power laser fiber head 15 to the selector valve housing 1. Arrange the two laser fiber heads in parallel so that the low-power laser beam 24 and the high-power laser beam 23 remain parallel. The spot diameter formed by the high-power laser beam 23 after passing through the beam expander 12 and the galvanometer system is larger than the spot diameter formed by the low-power laser beam 24 after passing through the galvanometer system.

[0019] S2. When printing the inner fill area, the high-power laser is turned on, the low-power laser is turned off, the piezoelectric ceramic ultrasonic motor 4 is activated, and the angle of the third reflector 10 is adjusted so that the expanded high-power laser beam 23 reflects out of the dual laser selection valve and enters the galvanometer system, then scans the fill line;

[0020] S3. When printing the shape line area, the low-power laser is turned on, the high-power laser is turned off, the piezoelectric ceramic ultrasonic motor 4 is started and the angle of the third reflector 10 is adjusted so that the low-power laser beam 24 is reflected from the dual laser selection valve and enters the galvanometer system, and then scans the contour line;

[0021] S4. After the shape line area is printed, continue to use the low-power laser beam 24 to scan the joint between the internal filling area and the shape line area.

[0022] The large spot preheating mode forming method comprises the following steps:

[0023] S1. Connect the low-power laser fiber head 14 and the high-power laser fiber head 15 to the selector valve housing 1. Arrange the two laser fiber heads in parallel so that the low-power laser beam 24 and the high-power laser beam 23 remain parallel. The spot diameter formed by the high-power laser beam 23 after passing through the beam expander 12 and the galvanometer system is larger than the spot diameter formed by the low-power laser beam 24 after passing through the galvanometer system.

[0024] S2. When printing refractory materials, the high-power laser is turned on, the low-power laser is turned off, the piezoelectric ceramic ultrasonic motor 4 is activated, and the angle of the third reflector 10 is adjusted so that the expanded high-power laser beam 23 reflects out of the dual laser selection valve and enters the galvanometer system, thereby preheating the printing surface.

[0025] S3. After the printing surface is preheated, the low-power laser is turned on, the high-power laser is turned off, the piezoelectric ceramic ultrasonic motor 4 is started and the angle of the third reflector 10 is adjusted so that the low-power laser beam 24 is reflected from the dual laser selection valve and enters the galvanometer system, and then the part is printed;

[0026] S4. Repeat steps S2 and S3 for each cross section of the printed part until the part is printed.

[0027] In the steps S2 and S3 , the piezoelectric ceramic ultrasonic motor 4 rotates the third reflector 10 by an angle of 90°.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The laser optical path adjustment device for laser powder bed fusion additive manufacturing of the present invention can be installed outside the galvanometer system, so that the overall printing equipment adopts a single galvanometer system without changing the structure and composition of the original galvanometer system. On the one hand, it saves the cost of a set of galvanometer systems, and on the other hand, it improves the overall reliability of the equipment and the difficulty of daily maintenance.

[0030] 2. The laser optical path adjustment device for laser powder bed fusion additive manufacturing of the present invention adjusts the angle of the third reflector through a single piezoelectric ceramic ultrasonic motor to ensure that the high-power laser beam and the low-power laser beam have the same optical path when entering the galvanometer system. On the basis of ensuring the simplicity of the optical path, it further realizes the characteristics of fast response speed, simple control, high optical path accuracy, compact overall structure and high practicality.

[0031] 3. The present invention provides a forming method for a laser optical path adjustment device for laser powder bed melting additive manufacturing, which uses a high-power laser beam to print the internal filling area, and uses a low-power laser beam to print the shape line area. The low-power laser beam is then used to further scan the joints of the internal filling area and the shape line area. This not only improves the printing efficiency but also ensures the performance of the printed parts, overcomes the problem of low printing quality in existing variable spot printing, and improves the practicality of variable spot printing.

[0032] 4. The forming method of a laser optical path adjustment device for laser powder bed melting additive manufacturing of the present invention has two working modes: a large spot filling printing mode and a large spot preheating mode; large spot preheating is performed on refractory materials, which improves the printing accuracy and performance of refractory material parts, expands the types of printable materials of the printing equipment, and effectively reduces the equipment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the cross-section printing area of ​​a variable spot printing part.

[0034] Figure 2 It is a structural diagram of a dual laser selection valve device according to an embodiment of the present invention.

[0035] Figure 3 1 is a structural diagram of a valve box body 1 according to an embodiment of the present invention.

[0036] Figure 4 It is a structural diagram of the first rectangular parallelepiped rod 7 and the second rectangular parallelepiped rod 9 in an embodiment of the present invention.

[0037] Figure 5 1 is a structural diagram of the rotating rod 11 according to an embodiment of the present invention.

[0038] Figure 6 It is a structural diagram of the first reflecting mirror 6, the second reflecting mirror 8 and the third transmitting mirror 10 in an embodiment of the present invention.

[0039] Figure 7 Schematic diagram of the path of a high-power laser beam in a dual-laser selection valve according to an embodiment of the present invention.

[0040] Figure 8 Schematic diagram of the path of a low-power laser beam in a dual-laser selection valve according to an embodiment of the present invention.

[0041] Figure 9 Schematic diagram of a large-diameter light spot (right) formed on a printing surface by a high-power laser beam 23 and a small-diameter light spot (left) formed on a printing surface by a low-power laser beam 24 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0043] Reference Figure 2 and Figure 3 A laser optical path adjustment device for laser powder bed fusion additive manufacturing includes a selection valve box 1, a laser beam outlet at the front end of the selection valve box 1 is provided with a plane mirror 2, and two optical fiber head connection ports at the rear end of the selection valve box 1 are respectively connected to a low-power laser optical fiber head 14 and a high-power laser optical fiber head 15. The high-power laser beam 23 input by the high-power laser optical fiber head 15 is emitted from the laser beam outlet through a beam expander 12, a second reflector 8, a third reflector 10, and a plane mirror 2. The low-power laser beam 24 input by the low-power laser optical fiber head 14 is emitted from the laser beam outlet through a first reflector 6, a third reflector 10, and a plane mirror 2. The third reflector 10 can be rotated to change its angle.

[0044] The low-power laser fiber head 14 and the high-power laser fiber head 15 are connected to the selector valve housing 1 by laser welding via the optical fiber support plate 3, in order to reduce the number of parts in the device and to reduce the deformation of the selector valve housing 1 by taking advantage of the small heat-affected zone and low welding stress of laser welding.

[0045] The third reflector 10 is connected to the piezoelectric ceramic ultrasonic motor 4, the piezoelectric ceramic ultrasonic motor 4 is connected to the motor fixing plate 5, and the motor fixing plate 5 is connected to the selection valve housing 1 by laser welding. The purpose is to reduce the number of parts in the device and take advantage of the small heat-affected zone and low welding stress of laser welding to reduce the deformation of the selection valve housing 1.

[0046] The first reflector 6 is used to change the direction of the low-power high-beam-quality laser beam. The first reflector 6 is connected to the first rectangular rod 7, and both ends of the first rectangular rod 7 are connected to the selection valve box 1; the second reflector 8 is used to change the direction of the high-power laser beam. The second reflector 8 is connected to the second rectangular rod 9, and both ends of the second rectangular rod 9 are connected to the selection valve box 1. The third reflector 10 is used to change the direction of the high-power laser beam or change the direction of the low-power high-beam-quality laser beam. The third reflector 10 is connected to the rotating rod 11, and the rotating rod 11 is connected to the piezoelectric ceramic ultrasonic motor 4.

[0047] The beam expander 12 is fixed on a beam expander bracket 13 , and the beam expander bracket 13 is connected to the selection valve box 1 .

[0048] Reference Figure 3 The selection valve box body 1 is provided with a first square fixing hole 101 on the upper left and right sides for positioning the first rectangular rod 7; the selection valve box body 1 is provided with a first circular fixing hole 102 in the middle of the left and right sides for positioning the rotating rod 11; the selection valve box body 1 is provided with a second square fixing hole 103 on the lower left and right sides for positioning the second rectangular rod 9; the selection valve box body 1 is provided with a second circular fixing hole 104 at the front end for fixing the plane mirror 2; the selection valve box body 1 is provided with a first optical fiber head connection port 105 and a second optical fiber head connection port 106 at the rear end for fixing the low-power laser optical fiber head 14 and the high-power laser optical fiber head 15 respectively; the internal bottom plate of the selection valve box body 1 is provided with a first screw hole 107, and the beam expander bracket 13 is connected to the selection valve box body 1 through the first screw 16 through the first screw hole 107.

[0049] Reference Figure 3 The motor fixing plate 5 is provided with a threaded through hole 501 , and the piezoelectric ceramic ultrasonic motor 4 is connected to the motor fixing plate 5 via a bolt 17 through the threaded through hole 501 .

[0050] Reference Figure 4 The first rectangular rod 7 has second screw holes 701 at both ends, which are fixed to the selection valve box 1 by second screws 18; a fifth screw hole 702 is opened in the middle of the first rectangular rod 7 for fixing the first reflector 6.

[0051] Reference Figure 4 The second rectangular rod 9 has third screw holes 901 at both ends, which are fixed to the selection valve box 1 by third screws 19; a sixth screw hole 902 is opened in the middle of the second rectangular rod 9 for fixing the second reflector 8.

[0052] Reference Figure 5A fourth screw hole 1101 is opened at one end of the rotating rod 11, which is fixed to the selection valve box 1 by the fourth screw 20; a square hole 1102 is opened at the other end of the rotating rod 11, which is connected to the transmission shaft of the piezoelectric ceramic ultrasonic motor 4; a seventh screw hole 1103 is opened in the middle of the rotating rod 11 for fixing the third reflector 10.

[0053] The rotating rod 11 is designed with an internal structure by using a lattice optimization method and is manufactured by using an additive manufacturing method, so as to reduce weight and moment of inertia, thereby improving the response speed of the third reflector 10 .

[0054] The lengths of the first rectangular parallelepiped rod 7 , the second rectangular parallelepiped rod 9 and the rotating rod 11 are all the same as the width of the selector valve housing 1 .

[0055] Reference Figure 6 The first reflector 6 has first through holes 601 on both sides and is fixed to the middle of the first rectangular rod 7 by the fifth screw 21. The angle between its reflective surface and the bottom surface of the selection valve box 1 is 45°.

[0056] Reference Figure 6 The second reflector 8 has second through holes 801 on both sides and is fixed to the middle of the second rectangular rod 9 by the sixth screw 22. The angle between its reflective surface and the bottom surface of the selection valve box 1 is 135°.

[0057] Reference Figure 6 The third reflector 10 has third through holes 1001 on both sides and is fixed to the middle of the rotating rod 11 by a seventh screw.

[0058] The first reflector 6 , the second reflector 8 and the third reflector 10 are all square in shape, with their centroids located on the same vertical line, and the area of ​​their reflective surfaces is more than 100 times the area of ​​the laser spot.

[0059] The first reflector 6, the second reflector 8 and the third reflector 10 are all made of high-purity UV fused quartz substrate and coated with ultra-high laser-induced damage threshold dielectric film, which can withstand high-energy pulses, an incident angle of 0-45°, and a reflectivity of more than 99%.

[0060] The low power laser adopts a beam quality M 2 The single-mode fiber laser has a power of 400-800W and a wavelength of less than 1.2. The high-power laser uses a fiber laser with a power of more than 4000W.

[0061] A forming method using the laser optical path adjustment device for laser powder bed fusion additive manufacturing includes a large spot filling printing mode forming method and a large spot preheating mode forming method;

[0062] The method for forming a large light spot filling printing pattern comprises the following steps:

[0063] S1. Reference Figure 7 and Figure 8 , connect the low-power laser fiber head 14 and the high-power laser fiber head 15 to the selector valve housing 1, and arrange the two laser fiber heads in parallel so that the low-power laser beam 24 and the high-power laser beam 23 remain parallel; the spot diameter formed by the high-power laser beam 23 after passing through the beam expander 12 and the galvanometer system is 10 times the spot diameter formed by the low-power laser beam 24 after passing through the galvanometer system;

[0064] S2. Reference Figure 7 and Figure 9 When printing the internal filling area, the high-power laser is turned on and the low-power laser is turned off. The piezoelectric ceramic ultrasonic motor 4 is started and the angle of the third reflector 10 is adjusted. The high-power laser beam 23 emitted by the high-power laser passes through the second reflector 8 and the third transmitting mirror 10 in succession, so that the expanded high-power laser beam 23 is reflected out of the dual laser selection valve and enters the galvanometer system, and then scans the filling line. The spot diameter formed on the printing surface is 800μm.

[0065] S3. Reference Figure 8 and Figure 9 When printing the shape line area, the low-power laser is turned on and the high-power laser is turned off. The piezoelectric ceramic ultrasonic motor 4 is started and the angle of the third reflector 10 is adjusted. The low-power laser beam 24 emitted by the low-power laser passes through the first reflector 6 and the third transmitting mirror 10 in succession, so that the low-power laser beam 24 is reflected out of the dual laser selection valve and enters the galvanometer system, and then scans the contour line. The spot diameter formed on the printing surface is 80μm;

[0066] S4. Considering the uneven energy distribution of the laser spot, which leads to low splicing accuracy and poor stability at the joint of the internal filling area and the shape line area, after the shape line area is printed, continue to use a low-power laser beam 24 to scan the joint of the internal filling area and the shape line area.

[0067] The large spot preheating mode forming method comprises the following steps:

[0068] S1. Reference Figure 7 and Figure 8 , connect the low-power laser fiber head 14 and the high-power laser fiber head 15 to the selector valve housing 1, and arrange the two laser fiber heads in parallel so that the low-power laser beam 24 and the high-power laser beam 23 remain parallel; the spot diameter formed by the high-power laser beam 23 after passing through the beam expander 12 and the galvanometer system is 10 times the spot diameter formed by the low-power laser beam 24 after passing through the galvanometer system;

[0069] S2. Reference Figure 7 and Figure 9 When printing refractory materials, the high-power laser is turned on and the low-power laser is turned off. The piezoelectric ceramic ultrasonic motor 4 is started and the angle of the third reflector 10 is adjusted. The high-power laser beam 23 emitted by the high-power laser passes through the second reflector 8 and the third reflector 10 in succession, so that the expanded high-power laser beam 23 is reflected out of the dual laser selection valve and enters the galvanometer system. The spot diameter formed on the printing surface is 800μm, and then the printing surface is preheated;

[0070] S3. Reference Figure 8 and Figure 9 After the printing surface is preheated, the low-power laser is turned on, the high-power laser is turned off, the piezoelectric ceramic ultrasonic motor 4 is started and the angle of the third reflector 10 is adjusted. The low-power laser beam 24 emitted by the low-power laser passes through the first reflector 6 and the third reflector 10 in succession, so that the low-power laser beam 24 is reflected out of the dual laser selection valve and enters the galvanometer system. The spot diameter formed on the printing surface is 80μm, and then the part is printed;

[0071] S4. Repeat steps S2 and S3 for each cross section of the printed part until the part is printed.

[0072] In the steps S2 and S3, the piezoelectric ceramic ultrasonic motor 4 rotates the third reflector 10 by an angle of 90°, thereby ensuring that the high-power laser beam 23 and the low-power laser beam 24 have the same optical path when entering the galvanometer system.

[0073] The present invention has been described in detail above with reference to the embodiments. However, the contents described are only preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A laser optical path adjustment device for laser powder bed fusion additive manufacturing, comprising a selector valve housing (1), characterized in that: A plane mirror (2) is provided at the laser beam outlet at the front end of the selection valve box (1), and two optical fiber head connectors at the rear end of the selection valve box (1) are respectively connected to a low-power laser optical fiber head (14) and a high-power laser optical fiber head (15). The high-power laser beam (23) input by the high-power laser optical fiber head (15) is emitted from the laser beam outlet via the beam expander (12), the second reflector (8), the third reflector (10), and the plane mirror (2). The low-power laser beam (24) input by the low-power laser optical fiber head (14) is emitted from the laser beam outlet via the first reflector (6), the third reflector (10), and the plane mirror (2). The third reflector (10) rotates to change its angle. The first reflector (6) is connected to a first rectangular parallelepiped rod (7), and both ends of the first rectangular parallelepiped rod (7) are connected to the selection valve housing (1); the second reflector (8) is connected to a second rectangular parallelepiped rod (9), and both ends of the second rectangular parallelepiped rod (9) are connected to the selection valve housing (1); the third reflector (10) is connected to a rotating rod (11), and the rotating rod (11) is connected to a piezoelectric ceramic ultrasonic motor (4); The first reflector (6), the second reflector (8) and the third reflector (10) are all square in shape, with their centroids located on the same vertical line, and the area of ​​the reflective surface is more than 100 times the area of ​​the laser spot; the first reflector (6), the second reflector (8) and the third reflector (10) are all made of high-purity ultraviolet fused quartz substrates and coated with ultra-high laser-induced damage threshold dielectric films, and can withstand high-energy pulses, with an incident angle of 0-45° and a reflectivity of more than 99%; Low power lasers use beam quality The single-mode fiber laser has a power of 400-800W and a wavelength of less than 1.

2. The high-power laser uses a fiber laser with a power of more than 4000W.

2. The device according to claim 1, characterized in that: The low-power laser optical fiber head (14) and the high-power laser optical fiber head (15) are connected to the selection valve box (1) via the optical fiber support plate (3) by laser welding.

3. The device according to claim 1, characterized in that: The third reflector (10) is connected to the piezoelectric ceramic ultrasonic motor (4), the piezoelectric ceramic ultrasonic motor (4) is connected to the motor fixing plate (5), and the motor fixing plate (5) is connected to the selection valve box (1) by laser welding.

4. The device according to claim 1, characterized in that: The beam expander (12) is fixed on a beam expander bracket (13), and the beam expander bracket (13) is connected to the selection valve box (1).

5. The device according to claim 1, characterized in that: The rotating rod (11) is designed with an internal structure by using a lattice optimization method and is manufactured by using an additive manufacturing method.

6. A forming method using a laser optical path adjustment device for laser powder bed fusion additive manufacturing according to any one of claims 1 to 5, comprising a forming method for a large spot filling printing mode and a forming method for a large spot preheating mode; The method for forming a large light spot filling printing pattern comprises the following steps: S1. Connecting a low-power laser fiber head (14) and a high-power laser fiber head (15) to the selector valve housing (1), the two laser fiber heads are arranged in parallel so that the low-power laser beam (24) and the high-power laser beam (23) remain parallel; the diameter of the spot formed by the high-power laser beam (23) after passing through the beam expander (12) and the galvanometer system is larger than the diameter of the spot formed by the low-power laser beam (24) after passing through the galvanometer system; S2. When printing the inner filling area, the high-power laser is turned on, the low-power laser is turned off, the piezoelectric ceramic ultrasonic motor (4) is started and the angle of the third reflector (10) is adjusted so that the expanded high-power laser beam (23) is reflected out of the dual laser selection valve and enters the galvanometer system, and then scans the filling line; S3. When printing the shape line area, the low-power laser is turned on, the high-power laser is turned off, the piezoelectric ceramic ultrasonic motor (4) is started and the angle of the third reflector (10) is adjusted so that the low-power laser beam (24) is reflected out of the dual laser selection valve and enters the galvanometer system, and then scans the contour line; S4. After the shape line area is printed, continue to use the low-power laser beam (24) to scan the joint between the internal filling area and the shape line area; The large spot preheating mode forming method comprises the following steps: S1. Connecting a low-power laser fiber head (14) and a high-power laser fiber head (15) to the selector valve housing (1), the two laser fiber heads are arranged in parallel so that the low-power laser beam (24) and the high-power laser beam (23) remain parallel; the diameter of the spot formed by the high-power laser beam (23) after passing through the beam expander (12) and the galvanometer system is larger than the diameter of the spot formed by the low-power laser beam (24) after passing through the galvanometer system; S2. When printing refractory materials, the high-power laser is turned on, the low-power laser is turned off, the piezoelectric ceramic ultrasonic motor (4) is started and the angle of the third reflector (10) is adjusted so that the expanded high-power laser beam (23) is reflected out of the dual laser selection valve and enters the galvanometer system, and then the printing surface is preheated; S3. After the printing surface is preheated, the low-power laser is turned on, the high-power laser is turned off, the piezoelectric ceramic ultrasonic motor (4) is started and the angle of the third reflector (10) is adjusted so that the low-power laser beam (24) is reflected out of the dual laser selection valve and enters the galvanometer system, and then the part is printed; S4. Repeat steps S2 and S3 for each cross section of the printed part until the part is printed.

7. The forming method according to claim 6, wherein: In the steps S2 and S3, the angle at which the piezoelectric ceramic ultrasonic motor (4) rotates the third reflector (10) is .

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