Variable-diameter laser additive manufacturing device of coaxial powder feeding process and scanning method

Abstract

The invention relates to the technical field of coaxial powder feeding additive manufacturing, in particular to a variable-diameter laser additive manufacturing device of a coaxial powder feeding process and a scanning method.The variable-diameter laser additive manufacturing device of the coaxial powder feeding process comprises an optical lens set, a machining head main mounting plate, a guide rail and a main light barrel, and the machining head main mounting plate is arranged on one side of the optical lens set; the optical lens set is connected with one side of the machining head main mounting plate through a connecting piece, a mounting frame is connected to the bottom end of the machining head main mounting plate, the machining head main mounting plate and the mounting frame are arranged in a right-angle structure, and a servo motor is fixedly connected to the top end of the end, close to the machining head main mounting plate, of the mounting frame. The servo motor is located between the machining head main mounting plate and the optical lens set, and the end, away from the machining head main mounting plate, of the mounting frame is arranged on the outer side of the optical lens set in a sleeving mode. In the additive printing process, the size of the light spot can be selected according to the process requirement, the adaptability of additive manufacturing can be improved under the condition that the additive manufacturing efficiency is not reduced, and the practicability of the additive manufacturing is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coaxial powder feeding additive manufacturing, and in particular to a variable diameter laser additive manufacturing device and a scanning method for a coaxial powder feeding process. Background Art

[0002] At present, the application of metal additive manufacturing technology in product processing and reshaping of damaged parts is becoming more and more extensive. Among them, coaxial laser powder feeding additive manufacturing process, as an important branch of metal additive process, has excellent process stability and high product mechanical properties. With the development of finite element analysis, topology optimization and other technologies, in order to pursue higher structural lightweight design, the integration of single products is getting higher and higher, and the structural form is becoming more and more complex.

[0003] Traditional laser coaxial powder feeding laser additive manufacturing uses a fixed-size spot to fill and form according to a certain scanning trajectory based on the discrete slice data of the product model. Since the spot size is fixed during the entire printing process (currently the market does not), the theoretical minimum structural size of the printed product is the spot size, and the spot size also determines the additive manufacturing efficiency. Therefore, traditional coaxial powder feeding laser additive manufacturing is difficult to balance the contradiction between additive manufacturing accuracy and additive manufacturing efficiency.

[0004] To this end, we propose a variable diameter laser additive manufacturing device and scanning method for a coaxial powder feeding process. Summary of the invention

[0005] The main purpose of the present invention is to provide a variable diameter laser additive manufacturing device and scanning method for a coaxial powder feeding process. Through the design of a servo adjustment mechanism, the main light cylinder is changed from the original fixed type to a retractable light cylinder. During the additive manufacturing process, the main light cylinder drives the end powder path actuator to move up and down along the optical axis. The laser beam divergence angle is used to timely adjust the spot size on the injection path, which can effectively solve the problems in the background technology.

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

[0007] A variable diameter laser additive manufacturing device of a coaxial powder feeding process comprises an optical lens group, a main mounting plate of a processing head, a guide rail and a main light cylinder, wherein one side of the optical lens group is provided with the main mounting plate of the processing head, the optical lens group is connected to one side of the main mounting plate of the processing head through a connecting piece, a mounting frame is connected to the bottom end of the main mounting plate of the processing head, the main mounting plate of the processing head and the mounting frame are arranged in a right angle structure, a servo motor is fixedly connected to the top end of the mounting frame close to one end of the main mounting plate of the processing head, the servo motor is located between the main mounting plate of the processing head and the optical lens group, and the mounting frame is sleeved on the outside of the optical lens group at one end away from the main mounting plate of the processing head;

[0008] A main light cylinder is provided at the lower part of the optical lens group, a guide rail is provided on the outer side of the main light cylinder, an outer cone is provided at the bottom end of the main light cylinder, an optical axis is connected to the bottom end of the outer cone, the lower part of the outer side of the main light cylinder is connected to the end powder path actuator through a rotating member, a plurality of groups of the end powder path actuators are provided relatively, and the plurality of groups of the end powder path actuators are connected to an assembly plate, the assembly plate is located directly below the main light cylinder, and a printing surface is provided below the end powder path actuator;

[0009] The bottom end of the mounting frame close to one end of the main mounting plate of the processing head is fixedly connected with a vertical plate, the bottom end of the vertical plate is fixedly connected with a horizontally arranged baffle, a threaded rod is provided on the side of the vertical plate close to the main light tube, the top end of the threaded rod passes through the mounting frame and is connected with the output shaft at the bottom end of the servo motor, the bottom end of the threaded rod is rotatably connected with the baffle, a sliding piece is sleeved on the threaded rod, and the sliding piece is slidably connected with the guide rail away from one end of the threaded rod.

[0010] By adopting the above technical solution and designing the servo adjustment mechanism, the main light cylinder is changed from the original fixed type to a retractable light cylinder. During the additive manufacturing process, the main light cylinder drives the end powder path actuator to move up and down along the optical axis, and uses the laser beam divergence angle to adjust the spot size in time on the injection path.

[0011] Specifically, the slide is threadably matched with the threaded rod, the slide is arranged at a right angle to the guide rail, and one end of the slide away from the guide rail is slidably connected to one side of the vertical plate.

[0012] Specifically, the baffle plate and the mounting plate are arranged relatively parallel, and the bottom end of the baffle plate contacts one end of the upper surface of the mounting plate.

[0013] Specifically, the vertical plate and the threaded rod are parallel to the guide rail, and the sliding member is located between the mounting frame and the baffle.

[0014] By adopting the above technical solution, the spot size can be selected according to the process requirements. Without reducing the efficiency of additive manufacturing, the adaptability of additive manufacturing can be improved, thereby further improving its practicability.

[0015] A scanning method for a variable diameter laser additive manufacturing device with a coaxial powder feeding process comprises the following steps:

[0016] S1. The main light tube drives the end powder path actuator to move up and down along the optical axis, and uses the laser beam divergence angle to adjust the spot size in time on the light injection path;

[0017] S2, the expansion and contraction of the main light tube (H2-H3) is compensated in the opposite direction by the main axis of the additive equipment (H1), offsetting the distance between the powder path convergence point and the forming surface, ensuring that the forming surface remains level;

[0018] S3, the spot size change is caused by the system automatically adjusting the scanning step length according to the expansion and contraction amount (H2-H3) to scan and fill:

[0019] Negative overlap step value Pace = 2 × beam spot diameter d × (1-overlap rate OverlapRate);

[0020] Positive overlap step value Pace = beam spot diameter d × (1-overlap rate OverlapRate);

[0021] Spot diameter change: Spot diameter δd = tan (laser beam divergence angle θ) × H (distance from the forming surface to the laser focus) - tan (laser beam divergence angle θ) × H' (distance from the forming surface to the laser focus after movement);

[0022] (The distance between the moving forming surface and the laser focus) H' = the expansion and contraction amount of the main light tube (H2-H3);

[0023] S4. During the part forming process, according to the model wall thickness requirements, the main light tube expansion and contraction amount δH (H2-H3) is adjusted within a predetermined range to meet the requirements of different wall thicknesses for light spots during the same printing process;

[0024] At the same time, during the forming process, δH(H2-H3) is adjusted in time according to the forming state detection situation, and the local margin of the product is quickly adjusted by changing the spot diameter.

[0025] Beneficial effects of the present invention:

[0026] (1) The variable diameter laser additive manufacturing device and scanning method of the coaxial powder feeding process described in the present invention, a servo adjustment mechanism is installed on the main light cylinder, and the main light cylinder is changed from the original fixed type to a retractable light cylinder through the design of the servo adjustment mechanism. During the additive manufacturing process, the main light cylinder drives the end powder path actuator to move up and down along the optical axis, and the laser beam divergence angle is used to timely adjust the spot size on the injection path;

[0027] (2) The variable diameter laser additive manufacturing device and scanning method of the coaxial powder feeding process described in the present invention can select the spot size according to the process requirements during the additive printing process. Without reducing the efficiency of additive manufacturing, it can also improve the adaptability of additive manufacturing and further improve its practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] Figure 1 It is a structural schematic diagram of the present invention;

[0030] Figure 2 It is the overlap rate formula diagram of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of the terminal powder circuit actuator of the present invention;

[0032] Figure 4 A comparison diagram of large-size spot printing and small-size spot printing of the present invention;

[0033] In the figure: 1. Optical lens assembly; 2. Main mounting plate of processing head; 3. Guide rail; 4. Main optical tube; 5. End powder path actuator; 6. Optical axis; 7. Printing surface; 8. Servo motor; 9. Mounting frame; 10. Vertical plate; 11. Connector; 12. Threaded rod; 13. Sliding part; 14. Baffle; 15. Assembly plate; 16. Outer cone. DETAILED DESCRIPTION

[0034] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0035] As an embodiment of the present invention, Figure 1-Figure 4 As shown, a variable diameter laser additive manufacturing device of a coaxial powder feeding process described in the present invention comprises an optical lens group 1, a processing head main mounting plate 2, a guide rail 3 and a main light cylinder 4, one side of the optical lens group 1 is provided with a processing head main mounting plate 2, the optical lens group 1 is connected to one side of the processing head main mounting plate 2 through a connecting member 11, a mounting frame 9 is connected to the bottom end of the processing head main mounting plate 2, the processing head main mounting plate 2 and the mounting frame 9 are arranged in a right angle structure, a servo motor 8 is fixedly connected to the top end of the mounting frame 9 close to one end of the processing head main mounting plate 2, the servo motor 8 is located between the processing head main mounting plate 2 and the optical lens group 1, and the mounting frame 9 is sleeved on the outside of the optical lens group 1 at one end away from the processing head main mounting plate 2;

[0036] A main light cylinder 4 is provided at the lower part of the optical lens group 1, a guide rail 3 is provided on the outer side of the main light cylinder 4, an outer cone 16 is provided at the bottom end of the main light cylinder 4, an optical axis 6 is connected to the bottom end of the outer cone 16, the lower outer part of the main light cylinder 4 is connected to a terminal powder path actuator 5 through a rotating member, a plurality of groups of terminal powder path actuators 5 are provided relatively, and the plurality of groups of terminal powder path actuators 5 are all connected to an assembly plate 15, the assembly plate 15 is located directly below the main light cylinder 4, and a printing surface 7 is provided below the terminal powder path actuator 5;

[0037] The bottom end of the mounting frame 9 close to one end of the main mounting plate 2 of the processing head is fixedly connected with a vertical plate 10, and the bottom end of the vertical plate 10 is fixedly connected with a horizontally arranged baffle 14. The vertical plate 10 is provided with a threaded rod 12 on one side close to the main light tube 4. The top end of the threaded rod 12 passes through the mounting frame 9 and is connected with the output shaft at the bottom end of the servo motor 8. The bottom end of the threaded rod 12 is rotatably connected with the baffle 14. A slide 13 is sleeved on the threaded rod 12, and the slide 13 is slidably connected with the guide rail 3 away from the end of the threaded rod 12; the servo motor 8, the threaded rod 12, the slide 13 and the guide rail 3 together constitute a servo adjustment mechanism.

[0038] Optics: In a narrow sense, it is the science of light and vision; optics, as it is often referred to today, is in a broad sense, and is the science of studying the generation, propagation, reception and display of electromagnetic radiation in a wide band ranging from microwaves, infrared, visible light, ultraviolet rays to X-rays and gamma rays, as well as the interaction with matter, with a focus on the range from infrared to ultraviolet. Light is an electromagnetic wave, and in physics, electromagnetic waves are described by Maxwell's equations in electrodynamics. At the same time, light has the dual nature of wave and particle, and the particle nature of light needs to be described by quantum mechanics.

[0039] When in use, the main light tube 4 drives the end powder path actuator 5 to move up and down along the optical axis 6, and uses the divergence angle of the laser beam to adjust the spot size in time on the light injection path;

[0040] The expansion and contraction amount (H2-H3) of the main light tube 4 is compensated in the opposite direction (H1) by the main axis of the additive equipment to offset the distance between the powder path convergence point and the forming surface, ensuring that the forming surface remains horizontal.

[0041] like Figure 1 and Figure 3 As shown, the present invention also includes that the slide 13 is threadedly matched with the threaded rod 12, the slide 13 and the guide rail 3 are arranged in a right-angle structure, and the end of the slide 13 away from the guide rail 3 is slidably connected to one side of the vertical plate 10; the baffle 14 and the assembly plate 15 are arranged relatively parallel, and the bottom end of the baffle 14 is in contact with one end of the upper end surface of the assembly plate 15; the vertical plate 10 and the threaded rod 12 are parallel to the guide rail 3, and the slide 13 is located between the mounting frame 9 and the baffle 14.

[0042] When in use, since the guide rail 3 is provided on the outside of the main light cylinder 4, the top end of the threaded rod 12 passes through the mounting frame 9 and is connected to the output shaft at the bottom end of the servo motor 8, the bottom end of the threaded rod 12 is rotatably connected to the baffle 14, and a slide 13 is sleeved on the threaded rod 12, and the end of the slide 13 away from the threaded rod 12 is slidably connected to the guide rail 3, so when the servo motor 8 drives the threaded rod 12 to rotate, the main light cylinder 4 is changed from the original fixed type to a retractable light cylinder through the threaded cooperation between the threaded rod 12 and the slide 13. In the additive manufacturing process, the main light cylinder 4 drives the end powder path actuator 5 to move up and down along the optical axis 6, and uses the laser beam divergence angle to timely adjust the size of the light spot (laser light spot) on the light injection path;

[0043] Laser spot refers to the distribution of laser beam in space. After the laser is output, the laser beam will focus to form a small and bright spot. The shape of the laser spot can be circular, elliptical or other shapes. It depends on the output mode of the laser and the interference and diffraction effects of the lens or other optical elements. The shape and characteristics of the spot will change with the change of propagation distance.

[0044] Spot size and intensity distribution: The size of the laser spot is usually expressed by the spot diameter or spot area, which describes the size of the spot on a certain cross section. Its size can be adjusted according to factors such as the laser parameters, the design of the optical system and the propagation distance. The light intensity distribution within the spot is an important factor in describing the brightness distribution of the spot. The intensity distribution of the spot can be uniform or non-uniform, which depends on factors such as the output characteristics of the laser and the propagation distance.

[0045] Near field and far field are two key concepts that describe the distance between the light spot and the laser. The area near the laser exit is called the near field, while the area far from the laser and far from the light spot is called the far field. In the near field, the shape and size of the light spot are related to the shape of the light spot at the laser exit and the propagation distance. Typically, the near-field light spot will have a larger size and a more irregular shape. This is because the laser beam has not yet fully diverged in the near-field distance, resulting in strong interference and diffraction effects. The light intensity distribution in the near-field light spot is usually uneven, with higher brightness near the center. As the distance increases, the light spot enters the far field. In the far field, the shape of the light spot will gradually become regular, and the diameter will become smaller and more symmetrical. This is due to the gradual emergence of the divergence effect of the laser beam. In the far field, the light intensity distribution tends to be uniform, and the size of the light spot is determined by the divergence angle and propagation distance of the light spot. The far field area is usually the area of ​​interest for the light spot in practical applications, because in this area, the light spot has a relatively stable size and shape, which is suitable for various measurement, imaging and other applications.

[0046] Defocus, that is, the positional relationship between the laser focal point and the surface of the irradiated material, is also a very important parameter in the laser surface treatment process. By selecting the defocus, the laser power density acting on the sample surface can be controlled. On the one hand, it can meet the demand for a certain laser power density in the laser surface treatment process; on the other hand, it can avoid excessive damage to the sample surface.

[0047] When the laser focal spot is above the surface of the material, it is defined as positive defocus; conversely, when the laser focal spot is below the surface of the irradiated material, it is defined as negative defocus; within the positive defocus range, the light will converge into a small spot behind the focus after refraction or reflection, and the spot size will gradually increase with increasing distance. At this time, the object image is behind the focus, and the lens or optical system focuses the light beam to form a clear image; negative defocus is the opposite, the object image is in front of the focus, the lens or optical system cannot focus normally, resulting in a blurred image; and the spot size gradually decreases with increasing distance.

[0048] A scanning method for a variable diameter laser additive manufacturing device with a coaxial powder feeding process comprises the following steps:

[0049] S1, the main light tube 4 drives the end powder path actuator 5 to move up and down along the optical axis 6, and uses the laser beam divergence angle to adjust the spot size in time on the light injection path;

[0050] S2, the expansion and contraction amount of the main light tube 4 (H2-H3) is compensated in the opposite direction by the main axis of the additive equipment (H1), offsetting the distance between the powder path convergence point and the forming surface, ensuring that the forming surface remains horizontal;

[0051] S3, the spot size change is caused by the system automatically adjusting the scanning step length according to the expansion and contraction amount (H2-H3) to scan and fill:

[0052] Negative overlap step value Pace = 2 × beam spot diameter d × (1-overlap rate OverlapRate);

[0053] Positive overlap step value Pace = beam spot diameter d × (1-overlap rate OverlapRate);

[0054] Spot diameter change: Spot diameter δd = tan (laser beam divergence angle θ) × H (distance from the forming surface to the laser focus) - tan (laser beam divergence angle θ) × H' (distance from the forming surface to the laser focus after movement);

[0055] (The distance between the moving forming surface and the laser focus) H' = the expansion and contraction amount of the main light tube (H2-H3);

[0056] S4. During the part forming process, according to the model wall thickness requirements, the main light tube expansion and contraction amount δH (H2-H3) is adjusted within a predetermined range to meet the requirements of different wall thicknesses for light spots during the same printing process;

[0057] At the same time, during the forming process, δH(H2-H3) is adjusted in time according to the forming state detection situation, and the local margin of the product is quickly adjusted by changing the spot diameter.

[0058] like Figure 4 As shown in , the fixed diameter spot scanning filling is often performed on the same part as a whole, and the part = forming wall thickness cannot be less than the spot diameter, resulting in excessive waste of margin;

[0059] After the spot size is adjustable, within the same printing section, different diameter spots can be selected according to different model cross-sections, which can take into account both the equipment's additive efficiency and additive accuracy.

[0060] The variable diameter laser additive manufacturing device and scanning method of the coaxial powder feeding process, when in use, a processing head main mounting plate 2 is provided on one side of the optical lens group 1, the optical lens group 1 is connected to one side of the processing head main mounting plate 2 through a connecting piece 11, a mounting frame 9 is connected to the bottom end of the processing head main mounting plate 2, a servo motor 8 is fixedly connected to the top end of the mounting frame 9 close to one end of the processing head main mounting plate 2, and the mounting frame 9 is sleeved on the outside of the optical lens group 1 at one end away from the processing head main mounting plate 2; a main optical cylinder 4 is provided at the lower part of the optical lens group 1, a guide rail 3 is provided on the outer side of the main optical cylinder 4, an outer cone 16 is provided at the bottom end of the main optical cylinder 4, an optical axis 6 is connected to the bottom end of the outer cone 16, the lower outer part of the main optical cylinder 4 is connected to the terminal powder path actuator 5 through a rotating member, multiple groups of terminal powder path actuators 5 are connected to the assembly plate 15, the assembly plate 15 is located directly below the main optical cylinder 4, and a printing surface 7 is provided below the terminal powder path actuator 5;

[0061] The main light tube 4 drives the end powder path actuator 5 to move up and down along the optical axis 6, and uses the laser beam divergence angle to adjust the spot size in time on the light injection path; the expansion and contraction amount (H2-H3) of the main light tube 4 is compensated in the opposite direction (H1) by the main axis of the additive equipment to offset the distance between the powder path convergence point and the forming surface, ensuring that the forming surface remains horizontal; the change in the spot size is caused by the system automatically adjusting the scanning step length according to the expansion and contraction amount (H2-H3) for scanning and filling:

[0062] Negative overlap step value Pace = 2 × beam spot diameter d × (1-overlap rate OverlapRate);

[0063] Positive overlap step value Pace = beam spot diameter d × (1-overlap rate OverlapRate);

[0064] Spot diameter change: Spot diameter δd = tan (laser beam divergence angle θ) × H (distance from the forming surface to the laser focus) - tan (laser beam divergence angle θ) × H' (distance from the forming surface to the laser focus after movement);

[0065] (The distance between the moving forming surface and the laser focus) H' = the expansion and contraction amount of the main light tube (H2-H3);

[0066] During the part forming process, the expansion and contraction amount of the main light tube δH (H2-H3) is adjusted within a predetermined range according to the wall thickness requirements of the model, so as to meet the requirements of different wall thicknesses for the light spot during the same printing process; at the same time, during the forming process, δH (H2-H3) is adjusted in time according to the forming state detection situation, and the local margin of the product is quickly adjusted by changing the light spot diameter.

[0067] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A variable diameter laser additive manufacturing device with a coaxial powder feeding process, characterized in that: The optical lens assembly (1) comprises an optical lens group (1), a main mounting plate (2) for a processing head, a guide rail (3) and a main light cylinder (4), wherein one side of the optical lens group (1) is provided with a main mounting plate (2) for a processing head, the optical lens group (1) is connected to one side of the main mounting plate (2) for a processing head via a connecting piece (11), a mounting frame (9) is connected to the bottom end of the main mounting plate (2) for a processing head, the main mounting plate (2) for a processing head and the mounting frame (9) are arranged at a right angle, a servo motor (8) is fixedly connected to the top end of the mounting frame (9) close to one end of the main mounting plate (2) for a processing head, the servo motor (8) is located between the main mounting plate (2) for a processing head and the optical lens assembly (1), and the mounting frame (9) is sleeved on the outside of the optical lens group (1) at one end away from the main mounting plate (2) for a processing head; A main light cylinder (4) is provided at the lower part of the optical lens group (1), a guide rail (3) is provided on the outer side of the main light cylinder (4), an outer cone cylinder (16) is provided at the bottom end of the main light cylinder (4), an optical axis (6) is connected to the bottom end of the outer cone cylinder (16), the lower part of the outer side of the main light cylinder (4) is connected to the end powder path actuator (5) through a rotating member, a plurality of groups of the end powder path actuator (5) are provided relatively, and the plurality of groups of the end powder path actuator (5) are connected to the assembly plate (15), the assembly plate (15) is located directly below the main light cylinder (4), and a printing surface (7) is provided below the end powder path actuator (5); The bottom end of the mounting frame (9) close to one end of the main mounting plate (2) of the processing head is fixedly connected to a vertical plate (10), and the bottom end of the vertical plate (10) is fixedly connected to a horizontally arranged baffle (14). The vertical plate (10) is provided with a threaded rod (12) on one side close to the main light tube (4). The top end of the threaded rod (12) passes through the mounting frame (9) and is connected to the output shaft at the bottom end of the servo motor (8). The bottom end of the threaded rod (12) is rotatably connected to the baffle (14). A slide (13) is sleeved on the threaded rod (12), and the slide (13) is slidably connected to the guide rail (3) at one end away from the threaded rod (12).

2. The variable diameter laser additive manufacturing device with coaxial powder feeding process according to claim 1 is characterized in that: The slide (13) is threadably matched with the threaded rod (12), the slide (13) and the guide rail (3) are arranged at a right angle, and the end of the slide (13) away from the guide rail (3) is slidably connected to one side of the vertical plate (10).

3. The variable diameter laser additive manufacturing device with coaxial powder feeding process according to claim 1 is characterized in that: The baffle plate (14) and the mounting plate (15) are arranged relatively parallel to each other, and the bottom end of the baffle plate (14) contacts one end of the upper end surface of the mounting plate (15).

4. The variable diameter laser additive manufacturing device with coaxial powder feeding process according to claim 1 is characterized in that: The vertical plate (10) and the threaded rod (12) are parallel to the guide rail (3), and the sliding member (13) is located between the mounting frame (9) and the baffle (14).

5. The scanning method of a variable diameter laser additive manufacturing device with a coaxial powder feeding process according to any one of claims 1 to 4, characterized in that: The steps include: S1, the main light cylinder (4) drives the end powder path actuator (5) to move up and down along the optical axis (6), and uses the laser beam divergence angle to adjust the light spot size in time on the light injection path; S2, the expansion and contraction amount (H2-H3) of the main light cylinder (4) is compensated in the opposite direction (H1) by the main axis of the additive equipment to offset the distance between the powder path convergence point and the forming surface, ensuring that the forming surface remains horizontal; S3, the spot size change is caused by the system automatically adjusting the scanning step length according to the expansion and contraction amount (H2-H3) to scan and fill: Negative overlap step value Pace = 2 × beam spot diameter d × (1-overlap rate OverlapRate); Positive overlap step value Pace = beam spot diameter d × (1-overlap rate OverlapRate); Spot diameter change: Spot diameter δd = tan (laser beam divergence angle θ) × H (distance from the forming surface to the laser focus) - tan (laser beam divergence angle θ) × H' (distance from the forming surface to the laser focus after movement); (The distance between the moving forming surface and the laser focus) H' = the expansion and contraction amount of the main light tube (H2-H3); S4. During the part forming process, according to the model wall thickness requirements, the main light tube expansion and contraction amount δH (H2-H3) is adjusted within a predetermined range to meet the requirements of different wall thicknesses for light spots during the same printing process; At the same time, during the forming process, δH(H2-H3) is adjusted in time according to the forming state detection situation, and the local margin of the product is quickly adjusted by changing the spot diameter.

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