Optical system for additive manufacturing

Abstract

The utility model belongs to the field of additive manufacturing relates to a kind of optical system for additive manufacturing, including laser generating device, first spectroscope, laser forming device, powder bed preheating device and beam combiner;Powder bed preheating device includes power regulating device;Laser generating device generates incident laser;First spectroscope is set on the light path of incident laser and is divided into forming beam and preheating beam by incident laser;Forming beam is incident to beam combiner after laser forming device;Preheating beam is incident to beam combiner after power regulating device and is emitted after beam combining with forming beam.The utility model provides a kind of optical system for additive manufacturing, preheating temperature is adjustable controllable, preheating temperature is more accurate and can effectively reduce the time consumption of preheating.

Description

Technical Field

[0001] This utility model belongs to the field of additive manufacturing and relates to an optical system, and more particularly to an optical system for additive manufacturing. Background Technology

[0002] In PBF (Powder Bed Fusion) additive manufacturing equipment, a laser beam is focused by a focusing lens group onto the working surface to form an energy spot capable of melting metal powder. This laser spot moves along a pre-defined layered scanning trajectory on the powder bed. Under the irradiation of the laser spot, the metal powder melts from a solid state to a liquid state and then solidifies into the desired part shape. During this process, because the melting point of metal powder is generally high, the temperature gradient is large during rapid cooling. If the part is not preheated, excessive internal stress will occur after forming, ultimately leading to defects such as warping and cracks after cooling. Currently, PBF additive manufacturing equipment typically uses substrate preheating. This preheating method suffers from problems such as a long preheating process and increased heat conduction as the part's forming layer thickness increases.

[0003] Utility model patent CN220196601U discloses a laser processing system that splits a linearly polarized laser emitted from a laser into two beams using a polarizing beam splitter: one for preheating and the other for processing. The two beams are then combined using a beam combiner and focused onto the processing surface, synchronizing preheating and processing. Its drawback is that the power of the processing and preheating beams is uncontrollable. The power of the preheating beam is determined by the laser and the beam splitter, and the preheating temperature cannot be controlled according to the specific material and forming process when processing different materials. Utility Model Content

[0004] In order to solve the above-mentioned technical problems in the background art, the present invention provides an optical system for additive manufacturing with adjustable and controllable preheating temperature, more precise preheating temperature, and effective reduction of preheating time.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An optical system for additive manufacturing is characterized in that: the optical system for additive manufacturing includes a laser generator, a first beam splitter, a laser forming device, a powder bed preheating device, and a beam combiner; the powder bed preheating device includes a power adjustment device; the laser generator generates an incident laser; the first beam splitter is disposed on the optical path of the incident laser and splits the incident laser into a forming beam and a preheating beam; the forming beam is incident on the beam combiner after passing through the laser forming device; the preheating beam is incident on the beam combiner after passing through the power adjustment device and is combined with the forming beam before exiting.

[0007] The aforementioned power adjustment device is either an electric shutter-type adjustment device or a variable aperture-type adjustment device.

[0008] When the power adjustment device described above is an electric optical shutter type adjustment device, the power adjustment device includes a second electric optical shutter; the preheated beam is incident on the beam combiner after passing through the second electric optical shutter;

[0009] When the power adjustment device is a variable aperture type adjustment device, the power adjustment device includes a variable magnification beam expander and a variable aperture; the preheated beam passes through the variable magnification beam expander and the variable aperture in sequence and then enters the beam combiner.

[0010] The aforementioned powder bed preheating device further includes a second beam splitter, an optical power detector, and a PID controller; the power adjustment device and the second beam splitter are arranged sequentially from front to back on the optical path where the preheating beam is located; the second beam splitter splits the preheating beam incident on it into a preheating beam reflected light and a preheating beam transmitted light; the beam combiner is placed on the optical path where the preheating beam reflected light is located; the optical power detector is placed on the optical path where the preheating beam transmitted light is located; the optical power detector is connected to the power adjustment device through the PID controller.

[0011] The aforementioned powder bed preheating device also includes a beam homogenizer; the power adjustment device, the beam homogenizer, and the second beam splitter are arranged sequentially from front to back on the optical path where the preheating beam is located.

[0012] The aforementioned powder bed preheating device also includes a beam expander; the power adjustment device, beam homogenizer, beam expander, and second beam splitter are arranged sequentially from front to back on the optical path where the preheating beam is located.

[0013] The aforementioned laser forming device includes a first motorized optical shutter and a dynamic focusing lens group; the first motorized optical shutter, the dynamic focusing lens group, and the beam combiner are arranged sequentially from front to back on the optical path where the forming beam is located.

[0014] The aforementioned optical system for additive manufacturing also includes a first reflector, a first half-wave plate, and a second half-wave plate; the first reflector, the power adjustment device, the second half-wave plate, and the beam homogenizer are arranged sequentially from front to back on the optical path where the preheated beam is located; the first motorized shutter, the first half-wave plate, and the dynamic focusing lens group are arranged sequentially from front to back on the optical path where the forming beam is located.

[0015] The aforementioned laser generating device includes a laser; the laser generates incident laser light; the incident laser light is a linearly polarized laser light.

[0016] The aforementioned laser generating device also includes a collimating and beam expanding element placed between the laser and the first beam splitter.

[0017] The advantages of this utility model are:

[0018] This invention provides an optical system for additive manufacturing, including a laser generator, a first beam splitter, a laser forming device, a powder bed preheating device, and a beam combiner. The powder bed preheating device includes a power adjustment device. The laser generator produces an incident laser beam. The first beam splitter is positioned on the optical path of the incident laser and splits the incident laser beam into a forming beam and a preheating beam. The forming beam passes through the laser forming device and is then incident on the beam combiner. The preheating beam passes through the power adjustment device and is then incident on the beam combiner, where it is combined with the forming beam before exiting. Addressing the shortcomings of existing PBF (Powder-Based Fabrication) equipment, such as slow substrate preheating and heat conduction issues, as well as the drawbacks of other patented follow-up preheating devices, including complex optical paths, uncontrollable preheating beams, and high preheating costs, this invention employs beam splitting to preheat and process the powder bed separately. Simultaneously, the power of the preheating beam is adjusted. This not only improves the accuracy of the preheating area and better matches the working conditions, reducing the preheating time of the powder bed, but also allows for power control of the preheating and processing beams, enabling adjustment of the preheating temperature under different working conditions. This invention features a simple structure, reducing material costs. The preheating beam is shaped into a ring to avoid interference with the processing beam. Furthermore, the power of both the preheating and processing beams is individually controllable, improving the operability and stability of both the preheating and processing areas. It follows the processing beam during preheating, resulting in fast preheating speed and low energy consumption. The preheating can be automatically controlled to stop, making the preheating process more flexible. Using the processing laser beam for beam splitting reduces the cost of additional parts, and a single scanning system can complete the control. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the optical path structure of the optical system for additive manufacturing (based on an electric optical shutter type adjustment device) provided by this utility model;

[0020] Figure 2 This is a schematic diagram of a follow-up preheating spot formed based on the optical system for additive manufacturing provided by this utility model;

[0021] Figure 3 This is a schematic diagram of the optical path structure of the additive manufacturing optical system (based on a variable aperture adjustment device) provided by this utility model.

[0022] in:

[0023] 1-Laser; 2-Collimating and expanding element; 3-First beam splitter; 4-Laser forming device; 41-First motorized optical shutter; 42-First half-wave plate; 43-Dynamic focusing lens group; 44-Beam combiner; 5-Powder bed preheating device; 51-First reflecting mirror; 52-Second motorized optical shutter; 53-Second half-wave plate; 54-Beam homogenizer; 55-Beam expander; 56-Second beam splitter; 57-Optical power detector; 58-Variable magnification beam expander; 59-Variable aperture; 6-Preheated spot area; 7-Processed spot area; 8-Processed plane; 9-Scanning galvanometer. Detailed Implementation

[0024] The starting point for the development of this utility model is: the laser outputs linearly polarized light, and the laser beam is divided into a preheating beam and a processing beam by polarization beam splitting and beam combining technology. The two beams pass through their respective optical paths, and the power of the two beams is adjusted by adjusting the control power adjustment device. Finally, the beams are combined by a beam combiner, and the scanning galvanometer scans the entire working surface. The preheating spot surrounds the processing spot but does not intersect, which avoids interference between the two beams and also enables the follow-up preheating of the powder bed. Therefore, based on this research and development concept, an optical system for additive manufacturing is provided, including a laser generator, a first beam splitter 3, a laser forming device 4, a powder bed preheating device 5, and a beam combiner 44; the powder bed preheating device 5 includes a power adjustment device; the laser generator generates an incident laser; the first beam splitter 3 is set in the optical path of the incident laser and splits the incident laser into a forming beam and a preheating beam; the forming beam is incident on the beam combiner 44 after passing through the laser forming device 4; the preheating beam is incident on the beam combiner 44 after passing through the power adjustment device and is combined with the forming beam before exiting, focusing on the scanning galvanometer 9 and finally incident on the processing plane 8, forming an energy spot on the processing plane 8 that can melt metal powder.

[0025] The power adjustment device used in this invention is an electric shutter type adjustment device or a variable aperture type adjustment device.

[0026] See Figure 1This is a schematic diagram of the optical path of an additive manufacturing optical system based on an electric optical shutter adjustment device. The electric optical shutter adjustment device includes a second electric optical shutter 52. The preheated beam passes through the second electric optical shutter 52 and is incident on a beam combiner 44. To precisely control or adjust the power of the preheated beam, the electric optical shutter adjustment device used in this invention can also be automated. For example, the powder bed preheating device 5 further includes a second beam splitter 56, an optical power detector 57, and a PID controller, in addition to the aforementioned features. The second electric optical shutter 52 and the second beam splitter 56 are sequentially arranged in the optical path of the preheated beam. The second beam splitter 56 divides the preheated beam incident on it into a reflected preheated beam and a transmitted preheated beam. The beam combiner 44 is placed in the optical path of the reflected preheated beam. The optical power detector 57 is placed in the optical path of the transmitted preheated beam. The optical power detector 57 is connected to the second electric optical shutter 52 via the PID controller.

[0027] See Figure 1 as well as Figure 3 The powder bed preheating device 5 used in this utility model also includes a beam homogenizer 54 and a beam expander 55; the preheating beam is arranged in the optical path of the preheating beam from front to back through the power adjustment device, the beam homogenizer 54, the beam expander 55 and the second beam splitter 56.

[0028] Beam expander 55 expands the homogenized annular spot to a size that can encompass the processing spot. The preheated annular spot includes the processing spot, but there is no overlap between the two. This avoids coupling interference between the preheated spot and the processing spot, as shown in the figure. Figure 2 As shown. After the preheating beam passes through the second beam splitter 56, part of the light is combined with the processing beam by the beam combiner 44, and the rest is received by the optical power detector 57. The optical power detector 57 detects the energy of the light spot at this location, thereby calibrating the energy of the preheating light spot on the processing surface. The calibration information of the detected preheating light spot is fed back to the control card. The control card uses PID control to control the second motorized optical shutter 52, thereby adjusting the energy of the preheating light spot and achieving closed-loop control of the temperature in the preheating area. The preheating beam is combined with the processing beam by the reflector and beam combiner, ultimately forming a beam on the processing surface as shown. Figure 2 The light spot (processing light spot area 7 is located in the center, and preheating light spot area 6 is arranged around the circumference of processing light spot area 7) achieves precise and rapid preheating and forming by controlling the scanning trajectory through scanning galvanometer 9.

[0029] See Figure 3This is a schematic diagram of the optical path of an additive manufacturing optical system based on a variable aperture adjustment device, which includes a variable magnification beam expander 58 and a variable aperture 59. The preheated beam is incident on the beam combiner 44 after passing through the variable magnification beam expander 58 and the variable aperture 59. The variable magnification beam expander 58 amplifies and "dilutes" the beam, while the variable aperture 59 changes the size of the aperture to filter out excess power, thus achieving adjustable preheated beam power. To precisely control or adjust the power of the preheating beam, the electric optical shutter-type adjustment device used in this invention can also be automated. For example, the powder bed preheating device 5 further includes a second beam splitter 56, an optical power detector 57, and a PID controller; the variable magnification beam expander 58, the variable aperture 59, and the second beam splitter 56 are arranged sequentially from front to back on the optical path where the preheating beam is located; the second beam splitter 56 divides the preheating beam incident on it into a preheating beam reflected light and a preheating beam transmitted light; the beam combiner 44 is placed on the optical path where the preheating beam reflected light is located; the optical power detector 57 is placed on the optical path where the preheating beam transmitted light is located; the optical power detector 57 is connected to the variable magnification beam expander 58 and / or the variable aperture 59 through the PID controller.

[0030] See Figure 1 as well as Figure 3 The laser forming device 4 used in this invention includes a first motorized optical shutter 41 and a dynamic focusing lens group 43; the first motorized optical shutter 41, the dynamic focusing lens group 43, and the beam combiner 44 are arranged sequentially from front to back on the optical path where the forming beam is located. Among them, the first motorized optical shutter 41 can realize the opening and closing of the processing beam, and the dynamic focusing lens group 43 realizes the focusing of the collimated and expanded processing beam.

[0031] See Figure 1 as well as Figure 3The optical system for additive manufacturing provided by this utility model further includes a first reflecting mirror 51, a first half-wave plate 42, and a second half-wave plate 53; the first reflecting mirror 51, the preheated beam via a power adjustment device, the second half-wave plate 53, and the beam homogenizer 54 are arranged sequentially from front to back on the optical path of the preheated beam; the first motorized shutter 41, the first half-wave plate 42, and the dynamic focusing lens group 43 are arranged sequentially from front to back on the optical path of the shaped beam. Both the first half-wave plate 42 and the second half-wave plate 53 are used to change the polarization state. For example, in the operation of an additive manufacturing optical system containing half-wave plates, the linearly polarized laser beam emitted by laser 1 is collimated and expanded before reaching the first beam splitter 3. The polarization perpendicular to the incident plane (S-polarized light) is reflected on the surface of the beam splitter, while the polarization parallel to the incident plane (P-polarized light) is transmitted. By inserting half-wave plates (first half-wave plate 42 and second half-wave plate 53) into the two optical paths, the polarization states of the two polarized beams are changed. When the two polarized beams reach the beam combiner, the polarization perpendicular to the incident plane (S-polarized light) is reflected, while the polarization parallel to the incident plane (P-polarized light) is transmitted, thus combining the two laser beams.

[0032] See Figure 1 as well as Figure 3 The laser generating device includes a laser 1, which generates incident laser light. For example, the incident laser light can be a linearly polarized laser. In order to collimate and expand the incident laser light, the laser generating device used in this invention also includes a collimating and expanding element 2 placed between the laser 1 and the first beam splitter 3.

[0033] In the additive manufacturing optical system provided by this invention, laser 1 emits a linearly polarized laser beam. After being collimated and expanded by collimating and expanding element 2, the laser beam passes through first beam splitter 3. Light polarized along the horizontal axis is transmitted, while light polarized along the vertical axis is reflected, thus splitting the collimated and expanded laser beam into a processing beam (transmitted light) and a preheating beam (reflected light). The processing beam passes through laser forming device 4 and then enters beam combiner 44. The preheating beam passes through powder bed preheating device 5 and then enters beam combiner 44. The two laser beams are combined by beam combiner 44 to form a processing spot on processing plane 8. The preheating beam is reflected by first beam splitter 3 and enters powder bed preheating device 5. Power adjustment device can realize switching control and power control of preheating beam. Second half-wave plate 53 changes the polarization state. By changing the switching time of power adjustment device within one cycle, the power of preheating beam can be controlled (similar to PWM dimming). Beam homogenizer 54 homogenizes the preheating beam into a ring-shaped spot with uniform energy distribution.

Claims

1. An optical system for additive manufacturing, characterized in that: The optical system for additive manufacturing includes a laser generator, a first beam splitter (3), a laser forming device (4), a powder bed preheating device (5), and a beam combiner (44); the powder bed preheating device (5) includes a power adjustment device; the laser generator generates an incident laser; the first beam splitter (3) is disposed on the optical path of the incident laser and splits the incident laser into a forming beam and a preheating beam; the forming beam is incident on the beam combiner (44) after passing through the laser forming device (4); the preheating beam is incident on the beam combiner (44) after passing through the power adjustment device and is combined with the forming beam before exiting.

2. The optical system for additive manufacturing according to claim 1, characterized in that: The power adjustment device is an electric shutter-type adjustment device or a variable aperture adjustment device.

3. The optical system for additive manufacturing according to claim 2, characterized in that: When the power adjustment device is an electric optical shutter type adjustment device, the power adjustment device includes a second electric optical shutter (52); the preheated beam is incident on the beam combiner (44) after passing through the second electric optical shutter (52); When the power adjustment device is a variable aperture type adjustment device, the power adjustment device includes a variable magnification beam expander (58) and a variable aperture (59); the preheated beam passes through the variable magnification beam expander (58) and the variable aperture (59) in sequence and then enters the beam combiner (44).

4. The optical system for additive manufacturing according to claim 3, characterized in that: The powder bed preheating device (5) also includes a second beam splitter (56), an optical power detector (57), and a PID controller; the power adjustment device and the second beam splitter (56) are arranged sequentially from front to back on the optical path where the preheated beam is located; the second beam splitter (56) divides the preheated beam incident on the second beam splitter (56) into a preheated beam reflected light and a preheated beam transmitted light; the beam combiner (44) is placed on the optical path where the preheated beam reflected light is located; the optical power detector (57) is placed on the optical path where the preheated beam transmitted light is located; the optical power detector (57) is connected to the power adjustment device through the PID controller.

5. The optical system for additive manufacturing according to claim 4, characterized in that: The powder bed preheating device (5) also includes a beam homogenizer (54); the power adjustment device, the beam homogenizer (54) and the second beam splitter (56) are arranged sequentially from front to back on the optical path where the preheating beam is located.

6. The optical system for additive manufacturing according to claim 5, characterized in that: The powder bed preheating device (5) also includes a beam expander (55); the power adjustment device, beam homogenizer (54), beam expander (55) and second beam splitter (56) are arranged sequentially from front to back on the optical path where the preheated beam is located.

7. The optical system for additive manufacturing according to claim 6, characterized in that: The laser forming device (4) includes a first motorized optical shutter (41) and a dynamic focusing lens group (43); the first motorized optical shutter (41), the dynamic focusing lens group (43) and the beam combiner (44) are arranged sequentially from front to back on the optical path where the forming beam is located.

8. The optical system for additive manufacturing according to claim 7, characterized in that: The optical system for additive manufacturing also includes a first reflector (51), a first half-wave plate (42), and a second half-wave plate (53); the first reflector (51), the power adjustment device, the second half-wave plate (53), and the beam homogenizer (54) are arranged sequentially from front to back on the optical path where the preheated beam is located; the first motorized shutter (41), the first half-wave plate (42), and the dynamic focusing lens group (43) are arranged sequentially from front to back on the optical path where the forming beam is located.

9. The optical system for additive manufacturing according to any one of claims 1-8, characterized in that: The laser generating device includes a laser (1); the laser (1) generates an incident laser; the incident laser is a linearly polarized laser.

10. The optical system for additive manufacturing according to claim 9, characterized in that: The laser generating device also includes a collimating beam expander (2) placed between the laser (1) and the first beam splitter (3).

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