Laser optical system and 3D printing device having the same

Abstract

The present application provides a laser optical system and a 3D printing device having the laser optical system. The laser optical system includes a laser light source, a collimating and beam expanding lens, a galvanometer scanner, and a field lens. The laser light source uses a single-mode green laser with a wavelength of 500 nm to 550 nm. The collimating and beam expanding lens expands the light spot of the laser light source to 8 - 14 mm. The focal length of the field lens is set to 100 - 200 mm, and the beam quality M<supgt;2< / supgt; of the green laser output after passing through the field lens is 1.0 - 1.4. In this way, the light spot diameter of the generated green laser at the focal point will be 5 - 20 μm, breaking through the industry technical bottleneck that the laser light spot diameter in current high-power laser processing applications is greater than 30 μm.

Description

Technical Field

[0001] The present invention relates to the field of laser processing equipment, and more particularly to a laser optical system and a 3D printing device having the laser optical system, and more particularly to a high-resolution laser optical system and a 3D printing device having the same. Background Art

[0002] The mainstream optical system used in 3D printing equipment (such as selective laser sintering (SLS), selective laser melting (SLM) and other laser printing equipment) on the market is a 1064nm infrared fiber laser. Based on the limitations of the performance of infrared light itself, the diameter of the laser spot generated under the current collimator and field lens conditions is limited. For example, when using a 10-14mm beam expansion collimator and a 400mm focal length field lens, the spot diameter is about 50μm for a diffraction-limited infrared laser beam. The smaller the laser spot diameter of the 3D printing equipment, the smaller the focal area, the more products that can be processed by laser, and the higher the processing accuracy. The current use of infrared fiber laser as the laser light source for 3D printing equipment has greatly restricted the application scope of 3D printing technology.

[0003] In order to reduce the spot diameter, some researchers have improved the beam expansion capability of the collimator. For example, the collimator is used to expand the spot of the laser light source to more than 14mm. However, due to the aperture of the beam expander and the galvanometer, the final spot diameter is still relatively limited. Under extreme conditions, for example, the focal length of the field lens is adjusted to the limit, and the focal length of the field lens is reduced to less than 200mm. The spot diameter can be about 30μm, but most materials usually have a certain reflectivity to infrared lasers. Especially in the production and processing of high-reflective metal materials, high-reflective metal materials have strong reflectivity to infrared lasers and poor absorption rate to infrared lasers. The splashes generated by the metal reflecting the laser can easily damage the field lens, causing the equipment to be scrapped, which is not conducive to safe production.

[0004] In addition, some researchers have reduced the spot diameter by changing the infrared laser light source to a semiconductor blue laser light source or a solid ultraviolet laser light source. 2 Very poor, the beam quality of the best semiconductor blue laser currently is M 2 Also greater than 10, usually the beam quality of semiconductor blue laser M 2The beam quality is relatively poor, which makes it difficult for semiconductor blue laser sources to reduce the spot diameter. Solid-state UV laser sources can reduce the spot diameter to less than 30μm, but solid-state UV lasers have low power, usually below 100W, which makes it difficult to melt metal powders. Most of them are pulsed lasers, with poor printing quality and difficult to control spatter, making it difficult to meet the processing requirements of laser 3D printing. At the same time, high-power solid-state UV lasers are extremely expensive, making them difficult to be popularized in high-power industrial processing fields.

[0005] Based on this, it is necessary to invent a high-power laser optical system that can produce an ultra-small focused spot and a high-precision 3D printing device with the laser optical system. The high-resolution laser optical system breaks through the current industry technical bottleneck of laser spot diameter greater than 30um, and the generated laser spot diameter can be less than 20um. Summary of the invention

[0006] The technical problem to be solved by this application is to provide a laser optical system and a 3D printing device having the laser optical system in view of the deficiencies of the prior art. The laser output by the optical system breaks through the industry technical bottleneck of the laser spot diameter being greater than 30um in the current high-power laser processing application, has high resolution, and can promote the wider application of laser processing technology in the field of high-precision laser 3D printing.

[0007] In order to solve the above technical problems, this application adopts the following technical solutions.

[0008] The present application provides a laser optical system, including: a laser light source, a collimating beam expander, a galvanometer, and a field mirror. The laser light source adopts a single-mode green laser of 500nm to 550nm, and the collimating beam expander can adjust the divergence angle and spot size of the green laser emitted by the laser light source. The collimating beam expander can collimate and expand the laser passing through it, and the green laser after collimation and expansion enters the galvanometer again, and the scanning direction of the green laser is controlled by the swing of the deflection lens in the galvanometer, and then the green laser is focused by the field mirror and output from the light outlet of the field mirror.

[0009] In order to generate a high-precision green laser with a spot diameter less than 30um, the collimating beam expander of the laser optical system of the present application expands the spot of the laser light source to 8-20mm, the focal length of the field lens is set to 100-200mm, and the beam quality M of the green laser output after passing through the field lens is 2 In this way, the spot diameter of the generated green laser at the focal position will be 5 to 20 um.

[0010] The present application also provides a 3D printing device, which includes the above-mentioned laser optical system, and also includes a 3D printing work surface and a powder spreading unit. The powder spreading unit is set on one side of the 3D printing work surface, and can spread the powder to be processed on the 3D printing work surface. The green laser output by the laser optical system is focused by a field lens and irradiated to the 3D printing work surface to realize 3D printing processing within the range of the 3D printing work surface using green laser.

[0011] The present application provides a high-precision laser optical system and a 3D printing device having the laser optical system. The laser optical system uses a single-mode green laser of 500nm to 550nm, and is then configured with a suitable beam expander, galvanometer and field lens, and can ultimately generate a green laser with a spot diameter of 5 to 20um at the focal position, so as to break through the current industry technical bottleneck of laser 3D printing with a laser spot diameter greater than 30um, thereby promoting the application of laser 3D printing technology to higher precision fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 A schematic diagram of the structure of the laser optical system provided for this application;

[0014] Figure 2 A first structural schematic diagram of the 3D printing device provided in this application;

[0015] Figure 3 This is a second structural schematic diagram of the 3D printing device provided in this application.

[0016] Reference numerals:

[0017] 11. Laser light source, 12. Beam expander module, 13. Galvanometer module, 14. Field lens module, 21. 3D printing work surface, 22. Powder spreading unit, 221. Powder bin, 222. Powder to be processed, 223. Smoothing tool, 224. Lifting mechanism. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present application, and are not limitations on the scope of the rights of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0019] The technical problem to be solved by the present application is that, in view of the deficiencies in the prior art, a laser optical system and a 3D printing device having the same are provided. The laser optical system adopts a single-mode green laser of 500nm to 550nm as a laser light source, and then matches a suitable beam expander, galvanometer and field lens, thereby promoting the application of laser 3D printing technology to higher precision fields.

[0020] In order to solve the above technical problems, this application adopts the following technical solutions.

[0021] See also Figure 1 , Figure 1 A schematic diagram of the structure of the laser optical system provided in the present application. The laser optical system provided in the present application includes: a laser light source 11, a collimating beam expander 12, a galvanometer 13, and a field lens 14. The laser light source 11 adopts a single-mode green laser of 500nm to 550nm, and the collimating beam expander 12 is used to adjust the divergence angle and spot size of the green laser emitted by the laser light source 11. The green laser after collimation and expansion by the collimating beam expander 12 enters the galvanometer 13 again, and the scanning direction of the green laser is controlled by the swing of the deflection lens in the galvanometer 13, and finally the green laser is focused by the field lens 14 and output from the light outlet of the field lens 14.

[0022] In order to make the spot diameter of the green laser generated for 3D printing less than 30um, the collimating beam expander 12 of the laser optical system of the present application expands the spot of the laser light source 11 to 8-20mm, the focal length of the field lens 14 is 100-200mm, and the beam quality M of the laser output by the field lens 14 is 2 Since the absorption rate of metal materials, especially highly reflective metal materials, to green laser is much higher than that to infrared laser, when the focal length of the field lens 14 of the laser optical system of the present application is set to 100-200 mm, the splash generated will be controllable.

[0023] According to the calculation formula of the spot diameter at the focal position D f =4M 2 λf / πD, where M 2 is the beam quality, λ is the wavelength of the light source, f is the focal length of the field lens, and D is the spot diameter of the light beam after collimation and expansion. According to this formula, when a laser light source 11 with a wavelength λ of 500-550nm is used and the beam quality M is designed at the same time2 When φ is 1.1-1.4, D is 8-20mm, and f is 100-200mm, the spot diameter of the green laser at the focal position is 5-20um. Usually, the processing accuracy of metal processing using the above laser optical system can be below 30um. A single spot of such a small size or a trace formed by the small spot along a straight line has reached a resolution range that cannot be recognized by the naked eye, and there will be a large number of applicable laser processing application scenarios.

[0024] In a preferred embodiment, the laser light source 11 of the laser optical system is a single-mode fiber green laser light source and adopts a continuous working mode. The single-mode fiber green laser has better beam quality than the solid green laser. The laser in the continuous working mode has higher stability and less spatter during 3D printing.

[0025] In a preferred embodiment, the spot diameter output by the laser light source 11 of the laser optical system is 2 to 8 mm. After the spot of this size is expanded to 8 to 14 mm by the collimating beam expander 12, the beam quality M can be maintained. 2 It is 1.0~1.4.

[0026] In a preferred embodiment, the operating power of the laser light source 11 of the laser optical system is greater than 100W.

[0027] Furthermore, when the working power of the laser light source 11 is 100-1000W, the scanning speed of the green laser is 500-5000mm / s.

[0028] See also Figure 2 , Figure 2 The first structural schematic diagram of the 3D printing device provided in this application. The 3D printing device includes the above-mentioned laser optical system, and also includes a 3D printing work surface 21 and a powder spreading unit 22. The powder spreading unit 22 is set on one side of the 3D printing work surface 21, and can spread the powder 222 to be processed on the 3D printing work surface 21. The green laser output by the laser optical system is focused by the field lens 14 and irradiated to the 3D printing work surface 21, so as to realize the 3D printing processing within the range of the 3D printing work surface 21 using the green laser.

[0029] Furthermore, the galvanometer 13 of the laser optical system controls the scanning range of the green laser on the focal plane of the flat-field focusing lens on the 3D printing work surface 21 to be 100mm*100mm~200mm*200mm.

[0030] Furthermore, the powder spreading unit 22 includes a powder bin 221, a smoothing tool 223 and a lifting mechanism 224. The powder bin 221 contains powder 222 to be processed. The powder 222 to be processed is pushed to the plane where the 3D printing work surface 21 is located through the lifting mechanism 224, and then the smoothing tool 223 is used to spread the powder 222 to be processed onto the 3D printing work surface 21.

[0031] Furthermore, the powder to be processed 222 is metal powder such as gold, silver, copper, aluminum, nickel, titanium, tantalum, tungsten, etc., and metal alloy powder containing one or more of the above metals.

[0032] Furthermore, the diameter length of a single powder particle of the powder to be processed 222 is less than 20 um.

[0033] In a preferred embodiment, the smoothing tool 223 is provided with a vibration mechanism (not shown in the figure). When the smoothing tool 223 spreads the powder 222 to be processed onto the 3D printing work surface 21, the vibration mechanism can break up the clusters and / or adhesions between the powders 222 to be processed, so that the powder layer of the powder 222 to be processed becomes smooth.

[0034] Furthermore, a shock-absorbing bracket (not shown in the figure) is also provided on the smoothing tool 223, and the shock-absorbing bracket has a shock-absorbing function, which is beneficial to protecting the powder spreading unit 22 and extending its service life.

[0035] See also Figure 3 , Figure 3 This is a second structural schematic diagram of the 3D printing device provided in the present application. The number of the powder spreading units 22 may be two, which are respectively set on both sides of the 3D printing work surface 21.

[0036] It should be noted that, in this article, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or device that includes the elements. In addition, the parts of the above-mentioned technical solutions provided in the embodiments of the present application that are consistent with the implementation principles of the corresponding technical solutions in the prior art are not described in detail to avoid excessive elaboration.

[0037] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the method and its core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and the various embodiments in the present application can be combined, and these improvements, modifications and combinations also fall within the scope of protection of the claims of the present application.

Claims

1. A laser optical system, applied to 3D printing of metal materials, characterized in that , comprising: a laser light source (11), a collimating beam expander (12), a galvanometer (13), and a field lens (14); The laser light source (11) adopts a single-mode green laser of 500nm to 550nm and adopts a continuous working mode. The collimating beam expander (12) is used to adjust the divergence angle and spot size of the green laser emitted by the laser light source (11). The green laser after being collimated and expanded by the collimating beam expander (12) enters the galvanometer (13). The scanning direction of the green laser is controlled by the swing of the deflection lens in the galvanometer (13). Finally, the green laser is focused by the field lens (14) and output from the light outlet of the field lens (14). The collimating beam expander (12) expands the spot of the laser light source (11) to 8 to 20 mm, the focal length of the field lens (14) is 100 to 200 mm, and the beam quality M of the laser output through the field lens (14) is 2 is 1.0 to 1.4, and the spot diameter of the generated green laser at the focal position is 5 to 20 um.

2. The laser optical system according to claim 1, characterized in that The operating power of the laser light source (11) of the laser optical system is greater than 100W.

3. The laser optical system according to claim 2, characterized in that The diameter of the light spot output by the laser light source (11) is 2 to 8 mm.

4. The laser optical system according to claim 2, characterized in that , when the working power of the laser light source (11) is 100 to 1000 W, the scanning speed of the green laser is 500 to 5000 mm / s.

5. A 3D printing device, characterized in that , comprising the laser optical system of any one of claims 1-4, and further comprising a 3D printing work surface (21) and a powder spreading unit (22), wherein the powder spreading unit (22) is set up on the side of the 3D printing work surface (21), and the number of the powder spreading units (22) is 1-2.

6. The 3D printing device according to claim 5, characterized in that The galvanometer (13) of the laser optical system controls the scanning range of the green laser on the focal plane of the flat-field focusing lens on the 3D printing work surface (21) to be 100mm*100mm to 200mm*200mm.

7. The 3D printing device according to claim 5, characterized in that: The powder spreading unit (22) comprises a powder bin (221), a smoothing tool (223) and a lifting mechanism (224); the powder bin (221) contains powder to be processed (222); the powder to be processed (222) is pushed to the plane where the 3D printing work surface (21) is located by the lifting mechanism (224); and then the powder to be processed (222) is spread flat on the 3D printing work surface (21) using the smoothing tool (223).

8. The 3D printing device according to claim 7, characterized in that: The powder to be processed (222) is one or more of gold, silver, copper, aluminum, nickel, titanium, tantalum, tungsten metal powders and metal alloy powders containing one or more of the above metals, and the diameter length of a single powder particle of the powder to be processed (222) is less than 20um.

9. The 3D printing device according to claim 7, characterized in that: The smoothing tool (223) is provided with a vibration mechanism. When the smoothing tool (223) spreads the powder (222) to be processed onto the 3D printing work surface (21), the vibration mechanism can break up the clusters and / or adhesions between the powders (222) to be processed, so that the powder layer of the powder (222) to be processed becomes smooth.

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