Composite laser efficient and high-quality polishing method and equipment

Abstract

The invention relates to the field of laser micro-nano machining, in particular to a composite laser efficient and high-quality polishing method and device, effectively solves the problems that during ceramic surface polishing, the surface quality is low, and the machining efficiency is poor, continuous / ultrafast laser composite shaping machining, preheating, rough machining and finish machining are synchronously carried out, and the machining efficiency is high. And efficient and high-quality polishing of the ceramic surface is achieved. The method specifically comprises the steps that continuous laser and femtosecond laser spots are shaped into oval light spots through a beam shaper, the oval light spots are compounded into light spots shown in the figure 2 through a light path, and then polishing machining is conducted according to a certain scanning path; a single continuous part in the composite light spot firstly scans the surface of the sample, and the sample is preheated; after preheating, rough machining is conducted on the sample through the composite part with the highest polishing efficiency in the composite light spots; and finally, finish machining is carried out on the roughly polished area through the single femtosecond part, and the surface roughness of the sample is further reduced. And finally, efficient and high-quality polishing of the ceramic surface is achieved.

Description

Technical Field

[0001] The invention relates to the field of laser micro-nano processing, and specifically designs a composite laser high-efficiency and high-quality polishing method and equipment. Background Art

[0002] Alumina ceramics have excellent properties such as high hardness, high thermal conductivity, high resistivity, and high thermal stability. In addition to its excellent cost-effectiveness, it is widely used in aerospace, 5G communications, high-power power semiconductors, and high-power LED lighting. However, the high hardness, high brittleness, and low fracture toughness of alumina ceramics also make it difficult to process them into parts with high surface finish and dimensional accuracy. Studies have found that surface polishing can effectively improve the surface quality of alumina ceramic parts.

[0003] At present, most of the surface polishing of ceramic parts is done by diamond grinding. Although traditional diamond grinding and polishing can meet the requirements of dimensional accuracy and surface roughness of ceramic parts, it has disadvantages such as low processing efficiency, high processing cost and environmental pollution. Therefore, there is an urgent need for a green and efficient polishing method to improve the surface polishing of ceramic materials.

[0004] The authorized patent (CN108890138B) provides an ultrafast laser polishing method for ceramic-based composite materials, which uses the laser and the processing platform to work together to achieve collaborative processing of ceramic surface polishing in the horizontal and vertical directions. Compared with traditional mechanical processing, this method can effectively improve processing quality and processing efficiency and achieve green processing. However, single laser processing often finds it difficult to balance processing quality and processing efficiency. This method uses femtosecond laser processing, and the total laser energy is limited, so the processing efficiency needs to be further improved.

[0005] The authorized patent (CN114473214A) provides a dual laser coupled polishing method. This method uses an infrared laser to preheat the workpiece surface, and after the preheating is completed, an ultraviolet picosecond laser is used to cold polish the workpiece to be polished according to the laser processing trajectory. Since the action time between the laser and the workpiece to be polished is very short, the heat-affected zone is very small, and the obtained processing section is also relatively flat, so that lower surface roughness and higher surface quality can be obtained. However, this method uses composite asynchronous processing. Although an infrared laser is used for preheating, due to the low total energy of the ultraviolet picosecond laser, it does not fundamentally solve the problem of insufficient single laser processing efficiency.

[0006] The authorized patents (CN109158762B) and (CN221269987U) both designed an ultrafast nanosecond composite laser polishing system. Patent (CN109158762B) first uses an infrared femtosecond laser to remove the oxide layer on the metal surface, while patent (CN221269987U) first uses a continuous laser with a camera to detect the surface roughness of the workpiece to be processed. Then both use ultrafast lasers to perform preliminary polishing on the sample, and finally use nanosecond lasers for final polishing. Using nanosecond lasers for final processing can, to a certain extent, solve the problem of insufficient efficiency of femtosecond polishing, and the final metal surface roughness can reach below 500nm, but these two methods still use a step-by-step processing mode, requiring multiple scans, and it is difficult to further improve efficiency.

[0007] If the above two asynchronous composite laser polishing methods are combined, the sample can also be processed through three steps of preheating, rough polishing and fine polishing. In comparison, the advantage of this method is that the composite light spot can be produced through optical path conditioning, which can realize preheating, rough processing and fine processing simultaneously, thereby improving processing efficiency. Furthermore, in asynchronous polishing, preheating and rough processing are carried out in steps, with a long interval time, which has the problem of energy dissipation. In this method, preheating and rough processing are carried out simultaneously, with a short interval time, which greatly improves the energy coupling efficiency.

[0008] In order to solve the problems of low processing efficiency, high processing cost and environmental pollution in the existing ceramic polishing methods, the present invention provides a composite laser high-efficiency and high-quality polishing method and equipment. The present invention specifically includes turning on the first and second lasers, adjusting the composite light spot through the beam shaper respectively, and then using the reflector to combine the two lasers into the same optical path, and then vertically injecting them into the incident hole of the scanning galvanometer through the collimated optical path and emitting them from the exit hole of the scanning galvanometer, focusing them through the field lens, and polishing the sample surface placed on the three-dimensional platform according to the set scanning path; the single continuous part in the composite light spot first scans the sample surface to preheat the sample and improve the subsequent processing efficiency; after preheating, the composite part with the highest polishing efficiency in the composite light spot is used to rough-process the sample; finally, the single femtosecond part in the composite light spot is used to fine-process the area after the composite part is polished, so as to further reduce the surface roughness of the sample. Finally, efficient and high-quality polishing of the ceramic surface is achieved. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a composite laser high-efficiency and high-quality polishing method and equipment. Through continuous / ultrafast laser shaping composite processing, high-quality, high-efficiency and green ceramic surface polishing processing is achieved.

[0010] In order to achieve the above object, the present invention provides a composite laser high-efficiency, high-quality polishing method and equipment, comprising the following steps:

[0011] (1) Turn on the first and second lasers. First, the two laser beams are respectively adjusted for the composite spot through a beam shaper. Subsequently, the two laser beams are combined onto the same optical path using a mirror, and then vertically enter the incident hole of the scanning galvanometer through a collimating optical path and exit from the exit hole of the scanning galvanometer, and are focused by a field lens to polish the surface of the sample according to the set scanning path;

[0012] (2) The single continuous part in the composite spot first sweeps across the surface of the sample to preheat the sample and improve the subsequent processing efficiency;

[0013] (3) After preheating, the composite part with the highest polishing efficiency in the composite spot is used to rough-process the sample.

[0014] (4) Finally, the single femtosecond part in the composite spot performs fine processing on the area polished by the composite part to further reduce the surface roughness of the sample.

[0015] Furthermore, the beam shaper is responsible for conditioning the composite spot, modulating the femtosecond spot and the continuous spot into ellipses respectively, and as shown in the appendix, Figure 2 the composite spot in the shape of "丄" is formed, which can be divided into a single femtosecond part, a single continuous part, and a composite part.

[0016] The single continuous part has a relatively high total energy and is difficult to remove the ceramic surface material when acting alone, so it is used to preheat the area to be polished;

[0017] The composite part is jointly composed of a continuous spot and a femtosecond spot, has a relatively high material removal efficiency, and can effectively reduce the surface roughness of the material, so it is used to rough-process the material;

[0018] The single femtosecond part has high processing accuracy, short action time, small heat affected zone, and the processed surface is relatively flat. Using it to perform fine processing on the roughly polished surface can further reduce the surface roughness of the material and improve the surface processing quality.

[0019] Furthermore, the scanning path needs to ensure the correct processing sequence, the single continuous part first touches the polishing area, followed by the composite part, and finally the single femtosecond part.

[0020] Furthermore, the first laser is a continuous laser, and the second laser is an ultrafast laser, specifically, it can be a femtosecond laser or a high-repetition-rate picosecond laser.

[0021] Furthermore, among the polishing processing parameters used, the continuous laser power is 300W - 800W, the femtosecond laser power is 5W - 15W, the repetition frequency is 1MHz, and the scanning speed is 20mm / s - 50mm / s.

[0022] Furthermore, the three-dimensional motion platform is a motion platform with three degrees of freedom, which can move independently or in conjunction on the three axes of X, Y, and Z, and its main function is to adjust the focal plane.

[0023] Furthermore, the galvanometer is a high-speed two-dimensional galvanometer, which can realize two-dimensional movement of the laser beam through the deflection of two reflection mirrors, and the scanning speed setting range of the scanning galvanometer is 20mm / s-50mm / s.

[0024] Furthermore, the field lens is a lens or a group of lenses, which is used to control and adjust the propagation direction, beam diameter and focusing position of the laser beam. The focal length of the field lens is 80 mm, and the laser defocus can be set between plus or minus 100 μm.

[0025] Furthermore, the ceramic samples described above represent materials that are difficult to polish with high quality and high efficiency using traditional mechanical methods, and the present method is also applicable to other materials that require surface polishing.

[0026] In general, the above technical solution of the present invention has the following advantages compared with the prior art solution:

[0027] Compared with traditional machining and polishing methods, this method uses laser processing methods, which can effectively overcome the difficult processing problems caused by high hardness, high brittleness and low fracture toughness of ceramics. Ultrashort pulse laser processing has the characteristics of low processing damage, high processing accuracy, wide processing application range and cold processing, and can achieve green and environmentally friendly, high-precision micro-nano processing.

[0028] Compared with single laser processing and composite asynchronous laser processing, this method can output continuous laser and ultrashort pulse laser at the same time. The composite spot is used to realize the simultaneous preheating, rough processing and fine processing, which improves the processing efficiency. At the same time, preheating and rough processing are carried out simultaneously, which reduces energy dissipation and ensures the laser energy coupling efficiency.

[0029] The light spot produced by this method is divided into single continuous, single femtosecond and composite parts, which are responsible for preheating, high-precision finishing and high-efficiency roughing respectively. It can not only maximize the polishing efficiency of the ceramic surface through the preheating of continuous laser and the high polishing efficiency of composite laser, but also ensure the polishing quality of the sample by using the high processing accuracy of ultrashort pulse laser.

[0030] The present invention effectively solves the problems of low surface quality, poor processing efficiency and low processing precision when polishing ceramic surfaces. Through continuous / ultrafast laser composite shaping processing, preheating, rough processing and fine processing are carried out simultaneously, thereby achieving efficient and high-quality polishing of the ceramic surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attached Figure 1 Optical path diagram of the invented composite laser high-efficiency and high-quality polishing method

[0032] Attached Figure 2 Schematic diagram of polishing scanning path and composite shaping spot

[0033] Explanation of the reference numerals: 1 - first laser; 2 - second laser; 3 - computer; 4 - beam shaper; 5 - reflector; 6 - collimation optical path; 7 - scanning galvanometer; 8 - field mirror; 9 - sample; 10 - three-dimensional motion platform. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and points to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Aiming at the problems of poor processing efficiency, low processing precision and low surface quality of the current traditional ceramic surface polishing method, the present invention provides a composite laser high-efficiency and high-quality polishing method and equipment.

[0036] The structure of an example provided by the present invention is shown in the figure, and is composed of a first laser 1; a second laser 2; a computer 3; a beam shaper 4; a reflector 5; a collimating optical path 6; a scanning galvanometer 7; a field lens 8; a sample 9; and a three-dimensional motion platform 10.

[0037] In this example, after the first laser 1 and the second laser 2 emit laser light, they enter the beam shaper for shaping, so that the light spot on the surface of the sample 9 is as shown in the attached figure. Figure 2 As shown. The two laser beams are combined into the same optical path through the reflector, and after being collimated by the collimated optical path 6, they enter the scanning galvanometer 7 together. The scanning galvanometer 7 controls the two-dimensional movement of the optical path through the internal reflector so that it enters the field lens 8 vertically. After being focused by the field lens 8, the laser is focused on the upper surface of the sample 9. During the processing, the workpiece remains stationary, and the scanning galvanometer and the field lens realize the movement of the light spot, thereby completing the polishing of the sample surface.

[0038] After the polishing processing platform is built according to the designed optical path, the cleaned ceramic sample 9 to be polished is fixed on the three-dimensional motion platform 10 by a clamp, and the three-dimensional platform 10 is adjusted so that the focal plane of the laser is located at the height of the upper surface of the ceramic sample 9. The beam shaper is used to adjust the spot of the continuous laser and the femtosecond laser so that the composite spot is as shown in the figure. Figure 2As shown. The processing parameters, galvanometer scanning path and scanning speed of continuous laser and femtosecond laser are controlled by computer 3. After all preparations are completed, the first laser 1 and the second laser 2 are controlled by computer 3 to emit light at the same time. The two laser beams are first adjusted by beam shaper 4 respectively, and then the two laser beams are combined into the same optical path by reflector 5, and then vertically injected into the incident hole of scanning galvanometer 7 through collimated optical path 6 and emitted from the exit hole of scanning galvanometer 7, and focused by field lens 8, and the surface of sample 9 is polished according to the set scanning path. The composite spot is divided into single femtosecond part, single continuous part and composite part. The single continuous part is responsible for preheating the sample surface, and the composite part with high polishing efficiency performs rough processing on the sample surface. The single femtosecond part performs fine processing on the polished area of ​​the composite part, further reducing the surface roughness of the sample. Through continuous / ultrafast laser composite shaping processing, preheating, rough processing and fine processing are carried out simultaneously, and the surface roughness of ceramics can be reduced to below 500nm, and finally efficient and high-quality polishing of ceramic surfaces can be achieved.

Claims

1. A composite laser high-efficiency, high-quality polishing method and equipment, used to achieve high-efficiency, high-quality polishing of ceramic surfaces, characterized in that: It includes the following steps: Step 1: Turn on the first and second lasers. First, the two laser beams are respectively adjusted for the composite spot through a beam shaper. Then, the two laser beams are combined onto the same optical path by using a reflector, and then vertically enter the incident hole of the scanning galvanometer through a collimation optical path and exit from the exit hole of the scanning galvanometer, and are focused by a field lens to polish the surface of the sample placed on the three-dimensional platform according to the set scanning path. Step 2: The single continuous part in the composite spot first sweeps across the sample surface to preheat the sample and improve the subsequent processing efficiency. Step 3: After preheating, use the composite part with the highest polishing efficiency in the composite spot to rough-process the sample. Step 4: The single femtosecond part in the composite spot finely processes the area polished by the composite part to further reduce the surface roughness of the sample.

2. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: In Step 1, the beam shaper is responsible for conditioning the composite spot, modulating the femtosecond spot and the continuous spot into ellipses respectively, and combining them into a "丄”-shaped composite spot as shown in Figure 2, which can be divided into a single femtosecond part, a single continuous part, and a composite part. The single continuous part has a relatively high total energy and is difficult to remove the ceramic surface material when acting alone, so it is used to preheat the area to be polished. The composite part is jointly composed of a continuous spot and a femtosecond spot, has a relatively high material removal efficiency, and can effectively reduce the surface roughness of the material, so it is used to rough-process the material. The single femtosecond part has high processing accuracy, short action time, small heat-affected zone, and relatively flat processed surface. Using it to finely process the surface after rough polishing can further reduce the surface roughness of the material and improve the surface processing quality.

3. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: In Step 1, the scanning path needs to ensure the correct processing sequence. The single continuous part first touches the polishing area, followed by the composite part, and finally the single femtosecond part.

4. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: In Step 1, the first laser is a continuous laser, and the second laser is an ultrafast laser, specifically, it can be a femtosecond laser or a high-repetition-rate picosecond laser.

5. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: Among the polishing processing parameters used, the continuous laser power is 300W - 800W, the femtosecond laser power is 5W - 15W, the repetition frequency is 1MHz, and the scanning speed is 20mm / s - 50mm / s.

6. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: In Step 1, the three-dimensional motion platform is a motion platform with three degrees of freedom, which can move independently or联动ly on the X, Y, and Z axes, and its main function is to adjust the focal plane.

7. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: In Step 1, the galvanometer is a high-speed two-dimensional galvanometer. The two-dimensional movement of the laser beam can be realized by the deflection of two reflectors. The scanning speed setting range of the scanning galvanometer is 20mm / s - 50mm / s.

8. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: In Step 1, the field lens is a single lens or a group of lenses, which is used to control and adjust the propagation direction, beam diameter, and focusing position of the laser beam. The focal length of the field lens is 80mm, and the laser defocus amount can be set between plus and minus 100μm.

9. A composite laser high-efficiency, high-quality polishing method and equipment according to claim 1, characterized in that: In Step 1, the ceramic sample represents a material that is difficult to polish with high quality and high efficiency by traditional mechanical methods. This method is also applicable to other materials that need surface polishing.

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