阅读说明：本技术 一种激光改性超精密切削的激光辅助加工硬脆材料方法 (Laser-modified ultra-precision cutting laser-assisted hard and brittle material processing method ) 是由 石卓奇 赵清亮 郭兵 计天宇 靳田野 于 2019-12-04 设计创作，主要内容包括：一种激光改性超精密切削的激光辅助加工硬脆材料方法,它涉及一种激光辅助加工硬脆材料方法,具体涉及一种激光改性超精密切削的激光辅助加工硬脆材料方法。本发明为了解决目前的激光辅助车削只能应用于圆柱面车削,激光焦点与切削区域置于同一个圆周面内,这使刀具与激光焦点的几何位置关系无法保持恒定的问题。本发明的步骤为步骤一、搭建激光辅助切削平台；步骤二、将激光输出头产生的连续激光束聚焦于工件表面；步骤三、使用刀具对改性后的工件表面进行切削加工。本发明属于机械加工领域。(A laser-assisted hard and brittle material processing method of laser-modified ultra-precision cutting relates to a laser-assisted hard and brittle material processing method, in particular to a laser-assisted hard and brittle material processing method of laser-modified ultra-precision cutting. The invention aims to solve the problem that the current laser-assisted turning can only be applied to cylindrical surface turning, and the laser focus and the cutting area are arranged in the same circumferential surface, so that the geometric position relationship between a cutter and the laser focus cannot be kept constant. The method comprises the steps of firstly, building a laser auxiliary cutting platform; focusing the continuous laser beam generated by the laser output head on the surface of the workpiece; and step three, cutting the modified workpiece surface by using a cutter. The invention belongs to the field of machining.)

1. A laser-modified ultra-precision cutting method for processing hard and brittle materials by aid of laser is characterized by comprising the following steps: the method for processing the hard and brittle material by the aid of the laser modified ultra-precision cutting comprises the following specific steps:

step one, building a laser auxiliary cutting platform;

focusing the continuous laser beam generated by the laser output head on the surface of the workpiece;

and step three, cutting the modified workpiece surface by using a cutter (2).

2. The method for laser-assisted machining of the hard and brittle material through laser-modified ultra-precision cutting according to claim 1, characterized by comprising the following steps: the laser auxiliary cutting platform in the first step comprises a five-axis manual displacement platform (3) and a laser processing module (4), wherein the laser processing module (4) is installed on the five-axis manual displacement platform (3);

the steps of building the laser auxiliary cutting platform are as follows:

a, mounting a laser processing module (4) on a five-axis displacement platform (3);

b, mounting the five-axis displacement platform (3) on the ultra-precision machine tool (1);

and step C, mounting the cutter (2) on the ultra-precision machine tool (1).

3. The method for laser-assisted machining of the hard and brittle material through laser-modified ultra-precision cutting according to claim 2, characterized by comprising the following steps: the five-axis manual displacement platform (3) comprises a vertical Y-direction manual displacement platform (16), a connecting rib plate (17), a rotary R-direction manual displacement platform (18), a linear Z-direction manual displacement platform (19), a linear X-direction manual displacement platform (20) and a linear W-direction manual displacement platform (21); the laser processing module (4) is installed on the manual displacement platform (21) in the direction of straight line W, the manual displacement platform (21) in the direction of straight line W is installed on the manual displacement platform (16) in the direction of vertical Y, the manual displacement platform (16) in the direction of vertical Y is connected with the manual displacement platform (18) in the direction of rotation R through a connecting rib plate (17), the manual displacement platform (18) in the direction of rotation R is installed on the manual displacement platform (19) in the direction of straight line Z, and the manual displacement platform (19) in the direction of straight line Z is installed on the manual displacement platform (20) in the direction of straight line X.

4. The laser-modified ultra-precision-machined laser-assisted hard and brittle material processing method as claimed in claim 2 or 3, characterized in that: the laser processing module (4) comprises a protective window glass (5), a converging mirror system (6), a collimating mirror system (7), a laser fiber (8), a water-cooling joint (9), a rear protective plate (10), a laser QBH output head (11), a base plate (12), a protective cover (13) and a front protective plate (14); protection window glass (5), convergent mirror system (6), collimating mirror system (7) are connected gradually by preceding to back end to end, protection window glass (5), convergent mirror system (6), collimating mirror system (7) is installed in protection casing (13) by preceding to back in proper order, collimating mirror system (7) are connected with laser fiber (8) through laser instrument QBH delivery head (11), the front end in protection casing (13) is installed in preceding protection shield (14), the rear end in protection casing (13) is installed in rear protection shield (10), water-cooling connects (9) and installs on rear protection shield (10).

5. The method for laser-assisted machining of the hard and brittle material through laser-modified ultra-precision cutting according to claim 1, characterized by comprising the following steps: in the second step, the specific steps of focusing the continuous laser beam generated by the laser output head on the surface of the workpiece are as follows:

a, adjusting the position of a laser spot of a laser processing module (4) on the surface of a workpiece through a five-axis displacement platform (3);

b, adjusting and determining the radius of the laser spot;

adjusting laser to focus on the surface of the workpiece, wherein the defocusing amount Z of the laser is 0; when Z is equal to Z⁺>When the concentration is 0 or less than 0,the laser is in a defocusing state; when the laser generates defocusing amount, the laser spot becomes large;

c, performing a laser scanning ablation experiment to obtain three parameters of power, blackbody coating solution solubility and defocusing amount;

step d, carrying out grouping ablation research on different laser scanning speeds;

e, performing finite element simulation on the scanning process in the step d by using COMSOL software;

step f, respectively solving the temperature peak value of the model and the stress distribution of the section of the laser spot in COMSOL software processing;

and g, determining laser parameters.

6. The method for laser-assisted machining of the hard and brittle material through laser-modified ultra-precision cutting according to claim 5, characterized by comprising the following steps: in the step b, according to the laser principle, the laser spot radius expression is as follows:

z in formula ①_RThe length of the rayleigh band is represented,

7. The method for laser-assisted machining of the hard and brittle material through laser-modified ultra-precision cutting according to claim 5, characterized by comprising the following steps: and b, pitting corrosion time of the laser on the surface of the workpiece in the step b is 1 second.

8. The method for laser-assisted machining of the hard and brittle material through laser-modified ultra-precision cutting according to claim 5, characterized by comprising the following steps: and c, performing a laser scanning ablation experiment to obtain three parameters of power, blackbody coating solution solubility and defocusing amount:

firstly, regulating laser power and blackbody coating solution concentration in groups; the adjusting range of the laser power is 20W-100W, and the concentration of the blackbody coating solution is 10% -20%;

carrying out microscopic observation on each ablation point and measuring the area of an ablation area, and selecting power and coating concentration which have ablation traces and no obvious black body coating residual as reasonable parameters in the ablation area;

and thirdly, adjusting the displacement of a laser system through a five-axis displacement platform (3) to generate laser defocusing amount, wherein the numerical range of the defocusing amount is 0-45 mm, performing a grouped ablation experiment on the defocusing amount by using the laser power and the concentration parameter of the black body coating solution obtained in the previous step, observing and measuring an obtained ablation point, and selecting the defocusing amount parameter which has the largest ablation area, has the most obvious surface layer material ablation effect and does not have black body coating residue.

9. The method for laser-assisted machining of the hard and brittle material through laser-modified ultra-precision cutting according to claim 5, characterized by comprising the following steps: in the step d, the three parameters of the laser power, the blackbody coating solution concentration and the defocusing amount obtained in the step c are used for carrying out a dynamic scanning ablation process experiment on the surface of the workpiece by laser, and the laser scanning speed is obtained, wherein the formula of the laser scanning speed is as follows:

v_c＝2δ·N③，

in the formula ③, N represents the spindle rotation speed of the ultra-precision machine tool (1), delta represents the laser ablation radius, and v_cIndicating the laser scanning speed.

Technical Field

The invention relates to a method for processing a hard and brittle material by laser assistance, in particular to a method for processing a hard and brittle material by laser assistance of laser modification and ultra-precision cutting, belonging to the field of machining.

Background

Hard and brittle materials such as hard alloy, ceramics, glass and the like have important application value and wide application prospect in the fields of aviation, photoelectron, medical treatment and the like, and compared with the traditional parts, the key parts made of the materials have the advantages of greatly prolonging the service life and improving the capability of resisting extreme conditions by virtue of the excellent mechanical and optical properties. However, these materials generally have greater processing difficulties, such as higher hardness, lower fracture toughness, etc., and may cause greater wear to the tool during the processing, which brings greater difficulty to the conventional machining means. Laser-assisted machining is considered to be an effective means of machining hard and brittle materials: the laser high-energy field is utilized to irradiate a processing area, so that local materials are softened or changed in phase at high temperature, and then mechanical processing is carried out. The addition of the laser field can be effective, so that the hardness of the surface of the material is reduced, and the processing difficulty is reduced. However, most laser-assisted machining methods are directed to cylindrical surface turning, the relative position of a laser and a cutter is kept unchanged, and the cutter is used for removing materials from materials which are heated by the laser and cooled. In the processing process, the position relation between the laser focus and the cutter needs to be accurately calculated and adjusted in advance, and only the surface of a certain simple shape of a workpiece can be repeatedly processed, so that the surface with a complex shape cannot be adapted; in addition, the current laser-assisted turning can only be applied to cylindrical surface turning, and the laser focus and the cutting area are arranged in the same circumferential surface, so that the geometric position relationship between the cutter and the laser focus cannot be kept constant.

Disclosure of Invention

The invention aims to solve the problem that the geometric position relationship between a cutter and a laser focus cannot be kept constant because the conventional laser-assisted turning can only be applied to cylindrical surface turning and the laser focus and a cutting area are arranged in the same circumferential surface, and further provides a laser-assisted hard and brittle material processing method based on laser modification and ultra-precision cutting.

The technical scheme adopted by the invention for solving the problems is as follows: the method comprises the following specific steps:

step one, building a laser auxiliary cutting platform;

focusing the continuous laser beam generated by the laser output head on the surface of the workpiece;

and step three, cutting the modified workpiece surface by using a cutter.

Further, the laser auxiliary cutting platform in the first step comprises a five-axis manual displacement platform and a laser processing module, and the laser processing module is installed on the five-axis manual displacement platform;

the steps of building the laser auxiliary cutting platform are as follows:

a, mounting a laser processing module on a five-axis displacement platform;

b, mounting the five-axis displacement platform on the ultra-precision machine tool;

and step C, mounting the cutter on the ultra-precision machine tool.

Furthermore, the five-axis manual displacement platform comprises a vertical Y-direction manual displacement platform, a connecting rib plate, a rotary R-direction manual displacement platform, a linear Z-direction manual displacement platform, a linear X-direction manual displacement platform and a linear W-direction manual displacement platform; the laser processing module is installed on the manual displacement platform in straight line W direction, and the manual displacement platform in straight line W direction is installed on the manual displacement platform in vertical Y direction, and the manual displacement platform in vertical Y direction is connected with the manual displacement platform in rotatory R direction through the connecting rib plate, and the manual displacement platform in rotatory R direction is installed on the manual displacement platform in straight line Z direction, and the manual displacement platform in straight line Z direction is installed on the manual displacement platform in straight line X direction.

Further, the laser processing module comprises a protective window glass, a converging mirror system, a collimating mirror system, a laser fiber, a water-cooling joint, a rear protective plate, a laser QBH output head, a base plate, a protective cover and a front protective plate; the protection window glass, the convergent mirror system and the collimating mirror system are sequentially connected from front to back, the protection window glass, the convergent mirror system and the collimating mirror system are sequentially installed in the protective cover from front to back, the collimating mirror system is connected with the laser fiber through a laser QBH output head, the front protective plate is installed at the front end of the protective cover, the rear protective plate is installed at the rear end of the protective cover, and the water-cooling connector is installed on the rear protective plate.

Further, the specific steps of focusing the continuous laser beam generated by the laser output head on the surface of the workpiece in the second step are as follows:

a, adjusting the position of a laser spot of a laser processing module on the surface of a workpiece through a five-axis displacement platform;

b, adjusting and determining the radius of the laser spot;

adjusting laser to focus on the surface of the workpiece, wherein the defocusing amount Z of the laser is 0; when Z is equal to Z⁺>When 0 or less than 0, the laser is in a defocusing state; when the laser generates defocusing amount, the laser spot becomes large;

c, performing a laser scanning ablation experiment to obtain three parameters of power, blackbody coating solution solubility and defocusing amount;

step d, carrying out grouping ablation research on different laser scanning speeds;

e, performing finite element simulation on the scanning process in the step d by using COMSOL software;

step f, respectively solving the temperature peak value of the model and the stress distribution of the section of the laser spot in COMSOL software processing;

and g, determining laser parameters.

Further, in the step b, according to the laser principle, the laser spot radius expression is as follows:

z in formula ①_RThe length of the rayleigh band is represented,

represents the beam waist radius of the laser beam generated by the laser, and omega₀Where ω (Z) denotes the laser spot radius, Z denotes the laser defocus amount, and λ denotes the laser center wavelength in equation ②.

Further, in the step b, the laser pitting time on the surface of the workpiece is 1 second.

Further, in the step c, a laser scanning ablation experiment is carried out, and the three parameters of power, the solubility of the black body coating solution and the defocusing amount are obtained by the following steps:

firstly, regulating laser power and blackbody coating solution concentration in groups; the adjusting range of the laser power is 20W-100W, and the concentration of the blackbody coating solution is 10% -20%;

carrying out microscopic observation on each ablation point and measuring the area of an ablation area, and selecting power and coating concentration which have ablation traces and no obvious black body coating residual as reasonable parameters in the ablation area;

and thirdly, adjusting the displacement of a laser system through a five-axis displacement platform to generate laser defocusing amount, wherein the numerical range of the defocusing amount is 0-45 mm, performing a grouped ablation experiment on the defocusing amount by using the laser power and the concentration parameter of the black body coating solution obtained in the previous step, observing and measuring an obtained ablation point, and selecting the defocusing amount parameter which has the largest ablation area, has the most obvious surface layer material ablation effect and does not have black body coating residue.

Further, in the step d, the three parameters of the laser power, the concentration of the black body coating solution and the defocusing amount obtained in the step c are used for carrying out a dynamic scanning ablation process experiment on the surface of the workpiece by the laser, and the laser scanning speed is obtained, wherein the formula of the laser scanning speed is as follows:

v_c＝2δ·N③，

in the formula ③, N represents the spindle rotation speed of the ultra-precision machine tool, delta represents the laser ablation radius, and v_cIndicating the laser scanning speed.

The invention has the beneficial effects that: aiming at the laser-assisted end face turning process, the invention provides an adjustable platform which can conveniently and rapidly focus the position of the tool nose of a turning tool by laser.

Aiming at the process parameter selection of the laser-assisted turning end face, the invention provides an adjustable platform capable of changing the process parameters such as the defocusing amount of laser, the incident angle of the laser, the distance between the focal point of the laser and the position of the tool nose of a turning tool and the like.

The laser ablation strategy of the invention improves the absorption rate of the transparent hard and brittle material to the laser energy, and realizes the basic requirement of laser-assisted turning.

The invention provides a parameter optimization method aiming at laser parameters, ultra-precision turning parameters and a matching relation between the laser parameters and the ultra-precision turning parameters in a laser-assisted end face turning processing technology.

Drawings

FIG. 1 is a schematic diagram of a laser-assisted cutting platform;

FIG. 2 is a schematic structural view of a laser processing module;

FIG. 3 is a schematic structural diagram of a five-axis manual displacement platform;

fig. 4 is a schematic illustration of a laser ablation strategy for a workpiece.

Fig. 5 is a schematic diagram of a laser scanning ablation process using COMSOL modeling.

FIG. 6 is a cross-sectional view of the ultra-precision cutting process after surface laser modification.

Fig. 4-6-blackbody coating to help absorb laser energy, 24-workpiece finite element model, 25-two-dimensional elliptical gaussian heat source laser energy density model, 26-heat affected zone cross section for laser ablation 23.

Detailed Description