阅读说明：本技术 一种金属表面先削峰后填谷的蒸发-熔凝复合激光抛光方法 (Evaporation-fusion composite laser polishing method for metal surface with peak clipping and valley filling ) 是由 王梁 黄锦榜 姚建华 吴国龙 于 2020-12-11 设计创作，主要内容包括：本发明提供了一种金属表面先削峰后填谷的蒸发-熔凝复合激光抛光方法,引入纳秒脉冲激光对大粗糙度表面进行削峰处理,再利用连续激光熔凝填充谷底的方式来对大粗糙度表面进行复合激光抛光,以防止微裂纹的产生；由于纳秒激光的脉宽极短,故多次扫描不会造成严重的热影响,作用后表面光亮、微观表面高峰被削低,接着再用连续激光熔凝,使材料熔化流动填充谷底,最终得到平整又光亮的无微观热裂纹的抛光表面,本发明抛光效率高,环境友好。(The invention provides an evaporation-fusion composite laser polishing method for metal surfaces, which comprises the steps of firstly carrying out peak clipping treatment on a large-roughness surface by introducing nanosecond pulse laser, and then carrying out composite laser polishing on the large-roughness surface by using a mode of filling valley bottoms by continuous laser fusion so as to prevent microcracks; because the pulse width of the nanosecond laser is extremely short, serious heat influence cannot be caused by multiple times of scanning, the surface is bright after the action, the peak of the microscopic surface is reduced, and then continuous laser melting is carried out, so that the material is melted, flows and fills the valley bottom, and a smooth and bright polished surface without the microscopic heat cracks is obtained.)

1. An evaporation-fusion composite laser polishing method for metal surface with peak clipping and valley filling, which is characterized by comprising the following steps:

cleaning and drying the surface of a metal workpiece to be polished, then placing the metal workpiece in an atmosphere protection box which is continuously filled with argon and the upper part of which is provided with a coated lens, and fixing the metal workpiece;

placing the atmosphere protection box on a workbench of a laser processing system, determining the polishing position of a laser selection area, the size of a polishing area and the scanning filling mode of the polishing area, setting process parameters of nanosecond pulse laser peak clipping and polishing, and performing peak clipping, polishing and scanning processing on the surface;

the nanosecond pulse laser peak clipping and polishing process parameters are as follows: the laser wavelength is 193-1064 nm, the laser power is 80-200W, the laser scanning speed is 100-2000 mm/s, the laser repetition frequency is 66-2000 kHz, and the laser pulse width is 10-400 ns;

setting technological parameters of continuous laser valley filling and polishing, and performing fused valley filling and polishing scanning treatment on the peak-clipped and polished low-peak surface;

the continuous laser valley filling and polishing process parameters are 193-1064 nm of laser wavelength, 100-500W of laser power and 100-500 mm/s of laser scanning speed.

2. The evaporation-fusion laser polishing method of claim 1, wherein in step one, the metal workpiece to be polished is made of stainless steel, tool steel or high temperature alloy.

3. The evaporation-fusion laser polishing method of claim 1, wherein in step one, the flow rate of argon gas introduced into the atmosphere protection box is 5-30L/min.

4. The evaporation-fusion laser polishing method of claim 1, wherein in step one, a coated lens transmitting 193-1064 nm laser is installed on the top of the atmosphere protection box.

5. The evaporation-fusion laser polishing method of claim 1, wherein in the second and third steps, the polishing region is an arbitrary pattern region with a length of 3-40 mm and a width of 3-40 mm.

6. The evaporation-fusion laser polishing method of claim 1, wherein in the second and third steps, the scanning and filling manner of the polishing region is from left to right transverse scanning and from top to bottom longitudinal overlapping, and the longitudinal overlapping ratio is 50% to 90%.

7. The evaporation-fusion laser polishing method of claim 1, wherein in step two, the number of scanning times of nanosecond pulsed laser peak clipping polishing is 4-12.

8. The evaporation-fusion laser polishing method of claim 1, wherein in step three, the number of scanning times of the continuous laser valley filling polishing is 1-2.

Technical Field

The invention relates to an evaporation-fusion composite laser polishing method for metal surface with peak clipping and valley filling.

Background

Laser polishing is a new type of material surface treatment technology that has appeared with the development of laser technology, and its basic principle is to use a laser beam with certain energy density and wavelength to irradiate a specific workpiece, so that a thin layer of material on its surface is melted or evaporated to obtain a smooth surface. Since laser polishing only works on a material layer with a thickness of micrometers, the laser polishing has higher processing precision compared with the metal processed by a common laser beam. The method can polish surfaces with very complicated appearance which are difficult or impossible to polish by the traditional polishing method without any mechanical grinding agent and polishing tool, and also provides the possibility of automatic processing, so compared with the traditional polishing, the method has the outstanding advantages of small environmental pollution, high polishing precision, wide range of polishing materials, micro-area polishing and the like.

At present, the mechanism of laser polishing is mainly melting, one is SSM, and the surface is shallow melted; the other is SOM, the surface is melted deeply. SSM is primarily directed to polishing surfaces with lower raw roughness values, while SOM is primarily directed to polishing surfaces with higher raw roughness values. When the surface with a high original roughness value is subjected to laser polishing, continuous energy input can be caused due to the increase of the number of continuous laser polishing scanning times, and micro thermal cracks can be formed on the surface of the brittle and hard material in the rapid heating and rapid cooling process under the action of laser, so that the surface performance of metal is influenced.

Disclosure of Invention

In order to prevent the influence on the material performance caused by the thermal cracks on the metal surface due to the continuous laser multiple polishing, the invention provides an evaporation-fusion composite laser polishing method for the metal surface with peak clipping and valley filling. Nanosecond pulse laser is introduced to carry out peak clipping treatment on the surface with large roughness, and then composite laser polishing is carried out on the surface with large roughness by utilizing a mode of filling valley bottoms by continuous laser melting so as to prevent microcracks from being generated. Because the pulse width of the nanosecond laser is extremely short, serious heat influence cannot be caused by multiple times of scanning, the surface is bright after the action, the peak of the microscopic surface is reduced, and then continuous laser melting is carried out, so that the material is melted, flows and fills the valley bottom, and a smooth and bright polished surface without the microscopic heat cracks is finally obtained.

The technical scheme of the invention is as follows:

an evaporation-fusion composite laser polishing method for metal surface with peak clipping and valley filling comprises the following steps:

cleaning and drying the surface of a metal workpiece to be polished, then placing the metal workpiece in an atmosphere protection box which is continuously filled with argon and the upper part of which is provided with a coated lens, and fixing the metal workpiece;

the material of the metal workpiece to be polished is stainless steel, tool steel, high-temperature alloy and the like, such as 304, 316L, SKD 11, Inconel 718 and the like;

continuously introducing argon into the atmosphere protection box to prevent the metal surface from being oxidized to influence the polishing quality, wherein the flow of the introduced argon is 5-30L/min;

the upper part of the atmosphere protection box is provided with a coated lens which can transmit 193-1064 nm laser;

placing the atmosphere protection box on a workbench of a laser processing system, determining the polishing position of a laser selection area, the size of a polishing area and the scanning filling mode of the polishing area, setting process parameters of nanosecond pulse laser peak clipping and polishing, and performing peak clipping, polishing and scanning processing on the surface;

specifically, the polishing area is an arbitrary graphic area with the length of 3-40 mm and the width of 3-40 mm;

the scanning filling mode of the polishing area is from left to right transverse scanning and from top to bottom longitudinal superposition, and the longitudinal superposition overlapping rate is 50-90%;

the nanosecond pulse laser peak clipping and polishing process parameters are as follows: the laser wavelength is 193-1064 nm, the laser power is 80-200W, the laser scanning speed is 100-2000 mm/s, the laser repetition frequency is 66-2000 kHz, and the laser pulse width is 10-400 ns;

the scanning times of the nanosecond pulse laser peak clipping polishing are 4-12 times;

setting technological parameters of continuous laser valley filling and polishing, and performing fused valley filling and polishing scanning treatment on the peak-clipped and polished low-peak surface;

the size of the polishing area and the scanning filling mode of the polishing area are the same as those in the second step;

the continuous laser valley filling and polishing process parameters are 193-1064 nm of laser wavelength, 100-500W of laser power and 100-500 mm/s of laser scanning speed;

and the scanning times of the continuous laser valley filling polishing are 1-2 times.

Compared with other polishing processes, the invention provides an evaporation-fusion composite laser polishing method for metal surface with peak clipping and valley filling, which has the advantages that:

(1) the invention has high polishing efficiency and no environmental pollution;

(2) the invention utilizes the characteristic that nanosecond laser has extremely short pulse width to reduce the heat input to the polishing matrix material;

(3) because nanosecond pulse laser is adopted for peak clipping, the invention obviously reduces the remelting and valley filling times of single continuous laser and improves the defect that the single continuous laser is fused for many times to cause microcracks on a large-roughness surface.

Drawings

FIG. 1 is a schematic view of the surface of a workpiece to be polished with a large roughness in example 1 or 2.

FIG. 2 is a surface topography of the initial high roughness surface of example 1 or 2.

FIG. 3 is a surface topography of a single laser reflow polish of example 1.

FIG. 4 is a surface topography of the pulsed laser peak clipping polishing in example 2.

FIG. 5 is a surface topography of the evaporation-fusion composite polish of example 2.

Detailed Description

The present invention is further illustrated by the following specific examples, but the scope of the invention is not limited thereto.

EXAMPLE 1 Single continuous laser polishing method for Metal surfaces

Selecting a 316L stainless steel block with the size of 100mm multiplied by 60mm multiplied by 10mm as shown in figure 1, wherein the surface 1 of the 316L stainless steel block is a large roughness surface cut by a model DK77-30 electric spark numerical control linear cutting machine, cleaning and drying the surface, and performing surface characterization on the surface, wherein the characterization result is shown in figure 2.

Placing the workpiece in an atmosphere protection box, carrying out single continuous laser polishing, and setting continuous laser parameters: the laser wavelength is 1064nm, the laser power is 500W, the scanning speed is 500mm/s, the scanning area is 10mm multiplied by 10mm, the scanning line spacing is 0.04mm, the scanning times are 6 times, the scanning filling mode is transverse scanning from left to right and longitudinal overlapping from top to bottom, the longitudinal overlapping rate is 67%, the surface characterization result is shown in figure 3, and a plurality of microscopic thermal cracks exist on the surface after single continuous laser polishing treatment.

Example 2 evaporation-fusion hybrid laser polishing method with peak clipping followed by valley filling on the metal surface

Selecting a 316L stainless steel block with the size of 100mm multiplied by 60mm multiplied by 10mm as shown in figure 1, wherein the surface 1 of the 316L stainless steel block is a large roughness surface cut by a model DK77-30 electric spark numerical control linear cutting machine, cleaning and drying the surface, and performing surface characterization on the surface, wherein the characterization result is shown in figure 2.

Placing the workpiece in an atmosphere protection box, performing evaporation-fusion composite laser polishing, and setting pulse laser parameters: laser wavelength is 1064nm, laser power is 100W, scanning speed is 1000mm/s, repetition frequency is 500kHz, pulse width is 10ns, scanning area is 10mm multiplied by 10mm, scanning line spacing is 0.05mm, scanning times are 8 times, scanning filling mode is from left to right transverse scanning and from top to bottom longitudinal overlapping, longitudinal overlapping rate is 50%, peak clipping and polishing treatment is carried out on a surface with large roughness, the surface characterization result of peak clipping and polishing is shown in figure 4, microscopic peaks are all cut down, and valley portions still exist.

And then setting continuous laser parameters: laser wavelength is 1064nm, laser power is 500W, scanning speed is 500mm/s, a scanning area is 10mm multiplied by 10mm, scanning line spacing is 0.04mm, scanning times are 2 times, scanning filling modes are transverse scanning from left to right and longitudinal overlapping from top to bottom, the longitudinal overlapping rate is 67%, fused valley filling polishing treatment is carried out on the surface after peak clipping and polishing, and the final surface characterization result is shown in figure 5, and the surface is flat and has no obvious micro thermal cracks.

The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but includes equivalent technical means as would be recognized by those skilled in the art based on the inventive concept.