WO2020211164A1

WO2020211164A1 - Jet-constrained femtosecond laser ultra-precision machining system and method

Info

Publication number: WO2020211164A1
Application number: PCT/CN2019/088543
Authority: WO
Inventors: 姚鹏; 王庆伟; 黄传真; 朱洪涛; 刘含莲; 邹斌; 何婉盈
Original assignee: 山东大学
Priority date: 2019-04-19
Filing date: 2019-05-27
Publication date: 2020-10-22
Also published as: CN109866028B; CN109866028A

Abstract

Provided is a jet-constrained femtosecond laser ultra-precision machining system, which comprises a B-axis workbench (1), a liquid tank (2), a laser jet coupling device (9), a plane mirror (11), a plane-convex lens (10), an adjusting block (8), a first reflecting mirror (5), a second reflecting mirror (7), a bracket (4) and a C-axis chuck (3), in operation, under the control of an ultra-precision CNC machine tool, the B-axis workbench (1) and C-axis chuck (3) can rotate around the axis and move along the axis, after being focused, a femtosecond laser (6) has a coupling effect with the jet and reaches the surface of a workpiece, at the same time, a chemical solution has a micro-corrosion effect with the machined surface of the workpiece and removes defects such as a surface deterioration layer, then impurities such as debris generated in the machining and chemical reaction processes are removed under the action of the water jet, to improve the quality of the machined surface, in combination with five-axis linkage of the C-axis chuck and the B-axis workbench, three-dimensional structured micro-machining of workpieces with arbitrary shapes such as a flat or free-form surface can be completed, the types of the workpiece surface machined by femtosecond laser are expanded, and the purpose of a wide range of high-efficiency and high-quality machining is achieved.

Description

Jet-constrained femtosecond laser ultra-precision processing system and method

Technical field

The invention relates to a jet confinement femtosecond laser ultra-precision processing system and method.

Background technique

The statements here only provide background art related to the present invention, and do not necessarily constitute prior art.

In recent years, femtosecond lasers have been widely used in many fields such as biomedicine, optoelectronic information, mechanical manufacturing, and 3D printing due to their short pulse width, high resolution, and low heat input. Femtosecond laser processing has small size, small thermal effect, wide range of processing objects, simple process and environmental protection. It can be used to process some difficult-to-process semiconductor materials and hard and brittle optical crystals. Compared with some traditional processing methods, it has high resolution and thermal effects. The area is small and can be processed without a mask, which can realize three-dimensional high-efficiency and high-quality micro-processing of materials. However, the interaction between the femtosecond laser and the solid material in the air environment will produce ablation debris and irregular micro-nano periodic stripe structure on the surface of the material, making it difficult to obtain high surface quality and surface accuracy in the ablated area and part of the unablated area.

At present, the method of improving the surface quality by chemically etching the surface of the workpiece processed by the femtosecond laser has been applied, but the etching time is longer and the etching efficiency is low. Moreover, the current femtosecond laser micromachining is mainly based on the surface of the workpiece, and the surface processed structures are mostly simple three-dimensional structures such as holes and wire grooves. It is difficult to realize complex curved three-dimensional structures such as cylindrical, aspherical or free-form surfaces on the material surface. Processing.

Summary of the invention

The purpose of the present invention is to solve the problem that the femtosecond laser processing accuracy is relatively low and it is difficult to complete the ultra-precision processing of workpieces with complex surface morphology, and to propose a jet-constrained femtosecond laser processing system with simple structure and low design and manufacturing cost, and a A method capable of processing a variety of workpiece surface shapes and structures such as planes, free-form surfaces, microstructures, and curved arrays.

The first objective of the present invention is to provide a jet-confined femtosecond laser ultra-precision machining system. In order to achieve this objective, the present invention adopts the following technical solutions:

A jet-constrained femtosecond laser ultra-precision processing system, including a B-axis worktable, a liquid tank, a laser jet coupling device, a plane mirror, a plano-convex lens, a first mirror, a second mirror, a bracket, and a C-axis chuck;

The B-axis worktable can rotate around the Y-axis and move along the Z-axis. The liquid tank is used to place workpieces and is fixed on the B-axis worktable. The laser jet coupling device is located above the liquid tank and is fixed. On the support, the plane mirror and the plano-convex lens are located inside the laser jet coupling device, wherein the plano-convex lens can focus the laser light, and the plane mirror can transmit the light and separate the jet from the plano-convex lens; on the side wall of the laser jet coupling device A first hole for liquid to flow in is provided, and the position of the first hole in the height direction is lower than the plano-convex lens;

The second reflector is connected and fixed with the external clamping device, the first reflector can reflect the laser light and is fixed on the bracket, the bracket is fixed on the C-axis chuck, and the C-axis chuck The disc is connected with the machine tool and can rotate around the Z axis and move along the X and Y axes, thereby realizing the five-axis linkage of the entire processing system.

The second objective of the present invention is to provide a jet-confined femtosecond laser ultra-precision machining method using the above system, which is specifically as follows:

The laser jet coupling device is fixed on the bracket, the liquid tank is fixed on the B-axis table, and the bracket is fixed on the C-axis chuck. The C-axis chuck and the B-axis table are connected to the ultra-precision CNC machine tool and realize axis rotation and Moving along the axis, after the femtosecond laser is focused by the plano-convex lens, it couples with the chemical reaction liquid coming in from the external jet and reaches the surface of the workpiece to be processed. At the same time, the solution and the surface of the workpiece processed by the femtosecond laser further chemically react to achieve micro The purpose of corroding and removing defects such as surface deterioration layer, and removing impurities generated by femtosecond laser processing and chemical reaction of the solution under the action of water jet, and taking away some of the heat generated during the processing, and then combining with the C-axis chuck and B The five-axis linkage of the axis table realizes jet-constrained femtosecond laser ultra-precision machining of a variety of workpiece surface shapes and structures such as plane, free-form surface, and curved array structure.

Further, in the jet-constrained femtosecond laser processing method, by programming a CNC machine tool, the rotation and movement of the C-axis chuck and the B-axis table can be controlled, and the size of the processing area can be adjusted.

Further, in the jet-confined femtosecond laser processing method, the laser is coupled with the jet to reach the surface of the workpiece and is processed perpendicular to the tangent plane at any point on the surface, that is, normal processing.

Further, by adjusting the valve connected with the laser jet coupling device and the opening of the liquid tank, the flow and depth of the solution inside the liquid tank can be controlled.

Further, the liquid that flows into the system during the processing is a chemical reagent solution, which only reacts with the workpiece under the action of the femtosecond laser, that is, through this method, the jet confinement of the plane or free-form surface workpiece in a variety of liquid phase environments can be realized. Laser ultra-precision processing.

The working principle and use method of the present invention:

In order to solve the problem that the surface accuracy of the material surface is affected by defects such as the deterioration layer caused by the thermal effect after the femtosecond laser processing, some researchers have adopted the method of chemical solution etching after the femtosecond laser processing the workpiece to improve the surface accuracy, but the corrosion time is long and It is difficult to control the corrosion depth, and the generated debris and other impurities will affect the further corrosion of the solution and the material.

The processing method mainly uses the femtosecond laser to process the workpiece while the chemical solvent performs micro-corrosion on the material. After the solvent is pressurized (the critical removal pressure of the material is not reached), the plasma bubbles generated during the processing are pressured to re-act on the workpiece The surface promotes the removal of defects such as the surface deterioration layer of the workpiece, and at the same time cleans up the debris and other impurities generated in the processing and reaction process and takes away some of the heat, which improves the surface quality of the workpiece, combined with the ultra-precision machining device C-axis chuck And the five-axis linkage of the B-axis worktable, so as to realize the jet-constrained femtosecond laser ultra-precision processing of a variety of workpiece surface shapes and shapes such as plane, free-form surface, and curved array structure.

The beneficial effects of the present invention are as follows:

1 When the femtosecond laser enters the processing system as incident light, it is focused on the surface of the workpiece through a plano-convex lens and is perpendicular to the tangent plane at any point on the surface, and the C-axis chuck is programmed to control the rotation of the C-axis chuck around the Z axis and move along the X and Y axes. The B-axis worktable rotates around the Y-axis and moves along the Z-axis, which can realize the five-axis linkage of the processing system, and perform three-dimensional structured micro-normal processing of various workpiece surface shapes such as planes and free-form surfaces, which expands the femtosecond laser processing workpiece surface The types of products achieve the purpose of wide range, high efficiency and high quality processing.

2 During the processing of the system, while the femtosecond laser acts on the surface of the workpiece, the chemical solvent in the laser area will cause micro-corrosion on the defects of the processed surface and other defects, reducing the later corrosion time, and the solvent is under a certain pressure (not reached Material critical removal pressure) reaches the processing surface, promotes the removal of defects such as the metamorphic layer, cleans up the debris and other impurities generated during the processing, and takes away some of the heat generated during the processing, reduces the impact of thermal effects on the processing process, and improves the workpiece The surface quality and surface accuracy of the surface can achieve jet-constrained femtosecond laser ultra-precision processing.

Description of the drawings

The drawings of the specification forming a part of the application are used to provide a further understanding of the application, and the exemplary embodiments and descriptions of the application are used to explain the application, and do not constitute an improper limitation of the application.

Figure 1 shows the overall structure of a jet-constrained femtosecond laser ultra-precision machining system;

Figure 2 is the second-axis view of the jet-constrained femtosecond laser ultra-precision machining system;

Figure 3 is a cross-sectional view of the laser jet coupling device;

Figure 4 is a cross-sectional view of the liquid tank device;

In the picture: 1. B-axis workbench, 2. Liquid tank, 3. C-axis chuck, 4. Bracket, 5. First mirror, 6. Femtosecond laser, 7. Second mirror, 8. Adjustment block , 9. Laser jet coupling device, 10. Plano-convex lens, 11. Plane mirror, 12. Workpiece.

detailed description

It should be pointed out that the following detailed descriptions are all illustrative and are intended to provide further explanations for the application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

It should be noted that the terms used here are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and/or "including" are used in this specification, they indicate There are features, steps, operations, devices, components, and/or combinations thereof;

In the present invention, the "X", "Y" and "Z" axes are linear motion axes, the "B" and "C" axes are rotary motion axes, and their rotation axes are respectively "Y" and "Z" axes. For the convenience of description, if the words "X axis", "Y axis", "Z axis", "B axis", and "C axis" appear in the present invention, they only indicate that they are consistent with the coordinates of the figure itself, and do not affect the structure. Therefore, it cannot be understood as a limitation of the present invention.

The terms "installed", "connected", "connected", "fixed" and other terms in the present invention should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or a whole; it can be a mechanical connection, It can also be an electrical connection, a direct connection, or an indirect connection through an intermediate medium, an internal connection between two components, or an interaction relationship between two components. For those of ordinary skill in the art, it can be based on specific Understand the specific meaning of the above terms in the present invention.

In order to solve the problem that the femtosecond laser processing accuracy is relatively low and it is difficult to complete the ultra-precision processing of workpieces with complex surface morphology, a simple structure, low design and manufacturing cost, and jet-constrained femtosecond processing for workpieces with arbitrary surface morphology is proposed. The laser ultra-precision processing system and method use CNC machine tool programming to control the five-axis linkage of the processing system to realize jet-constrained femtosecond laser ultra-precision processing of surface shapes and structures of various workpieces such as planes, free-form surfaces, microstructures, and curved structures.

The working principle and method of the present invention:

When the high-power femtosecond laser acts on the solid material under the liquid layer, the liquid medium near the surface of the material and the focus of the laser beam absorbs the laser energy. When the internal lattice of the material reaches the thermodynamic critical temperature, it explodes explosively, generating high-temperature and high-pressure plasma The body is separated from the surface of the material, the material is modified, and the plasma and the liquid in the front contact area undergo a phase change to generate cavitation bubbles and generate shock waves under the restriction of the liquid. Femtosecond laser ultra-precision processing of materials in a liquid environment. Higher plasma pressure and longer shock wave duration are conducive to laser pulse processing. Changes in the material structure and stress state lead to the surface hardness and fatigue strength of the material. Performance is improved.

At the same time, when the workpiece is processed in a certain chemical solvent, the micro-burst induced by the femtosecond laser will cause the internal microstructure of the workpiece material to change. When the material reacts with the chemical solvent, these structural deformations are compared with non-compact workpiece materials. It has better chemical activity and therefore a higher corrosion rate. Moreover, when materials are processed in solution, the surface of the sample can be cooled by the liquid, and the ablation produced by the laser can also be removed by bubbles, so the thermal effect is not obvious, and the structure surface is smoother and cleaner.

Based on the principle of femtosecond laser processing and chemical solvent corrosion in the liquid phase environment, the jet-constrained femtosecond laser ultra-precision processing system is built, and the five-axis linkage of the processing system is controlled by CNC machine tool programming to realize planes, free-form surfaces, fine structures, and curved surfaces. Femtosecond laser ultra-precision machining is constrained by jet flow of various workpiece surface shapes and structures such as structures.

Example 1

This embodiment is a stereotyped implementation provided by the present invention. As shown in Figures 1 and 2, it includes a B-axis worktable 1, a liquid tank 2, a laser jet coupling device 9, a flat mirror 11, a plano-convex lens 10, and an adjustment block 8. , The first mirror 5, the second mirror 7, the bracket 4 and the C-axis chuck 3.

The B-axis worktable 1 is connected to the machine tool and can rotate around the Y-axis and move along the Z-axis. The liquid tank 2 is fixed on the B-axis worktable 1, and the laser jet coupling device 9 is located in the liquid tank 2. Above and fixed on the bracket 4.

The plano-convex lens 11 and the plano-convex lens 10 are located inside the laser jet coupling device 9, and are fixed in a stepped structure inside the laser jet coupling device 9 through the adjustment block 8. It is separated from the plano-convex lens 10; the plano-convex lens 10 is located above the plane mirror 11, the specific structure can be seen in Fig. 3; in Fig. 3, the plane mirror 11 is fixed on the boss of the inner side wall of the laser jet coupling device 9 and passes through the lower The adjustment block 8 is pressed tightly; the plano-convex lens 10 is directly adhered to the bottom of the upper adjustment block 8, and the adjustment block 8 is fixed on the side wall of the laser jet coupling device 9.

The second reflector 7 is connected and fixed with an external clamping device. The first reflector 5 can reflect the light of the femtosecond laser 6 and is fixed on the bracket 4, and the bracket 4 is fixed on the C-axis chuck 3. Above, the C-axis chuck 3 is connected to the machine tool and the laser jet coupling device 9. The C-axis chuck 3 can also rotate around the Z axis and move along the X and Y axes; in general, the angle of rotation around the Z axis is Within ±30°.

When the femtosecond laser enters the processing system as incident light and is focused to the normal direction of the workpiece surface through the plano-convex lens, the C-axis chuck is programmed to control the rotation of the C-axis chuck around the Z-axis and move along the X and Y axes and the B-axis worktable around Y-axis rotation and movement along the Z-axis can realize the five-axis linkage of the processing system, and perform three-dimensional structured micro-machining of various workpiece surface shapes such as planes and free-form surfaces, expanding the types of femtosecond laser processing workpiece surfaces and realizing a wide range , High-efficiency, high-quality processing purpose.

Further, under the action of the CNC machine tool, the B-axis worktable 4 can rotate around the Y axis and move along the Z axis, and the C axis chuck 3 can rotate around the Z axis and move along the X and Y axes, thereby realizing the overall processing system Five-axis linkage.

Further, the laser jet coupling device 9 has a first hole on one side for the inflow of liquid, where the liquid is a chemical reagent solution, and the first hole is connected with related pipelines and valves. By controlling the size of the valve, The flow rate of the liquid is controlled, and the position of the first hole on the side wall is lower than the position of the plane mirror.

Further, there are second holes for the liquid to flow out on both sides of the liquid tank 2, and the two second holes are both connected with related pipelines and valves; of course, it is not difficult to understand that in other embodiments, the first The number of the two holes is not limited to two, but can also be one, three, four, five or more, and the specific number is set according to actual needs.

Further, the first reflecting mirror 5 and the second reflecting mirror 7 are placed at an angle of 45° with the plane where the X axis is located. The first reflecting mirror 5 and the second reflecting mirror 7 are mainly used to perform the femtosecond laser After reflection, it enters the laser jet coupling device.

Example 2

This embodiment provides a jet-constrained femtosecond laser ultra-precision processing method. The laser jet coupling device 9 is fixed on the bracket 4, the liquid tank 2 is fixed on the B-axis table 1, and the bracket 4 is fixed on the C-axis chuck 3. Above, the C-axis chuck 3 and the B-axis worktable 1 are connected with the ultra-precision CNC machine tool to realize rotation around the axis and movement along the axis. After the femtosecond laser is focused by the plano-convex lens 10, it couples with the jet and reaches the surface of the workpiece 12 to be processed At the same time, a further chemical reaction occurs between the solution and the surface of the workpiece 12 processed by the femtosecond laser 6 to achieve the purpose of micro-corrosion and removal of surface deterioration layers and other defects, and the femtosecond laser processing and solution chemical reaction are generated under the action of the water jet The debris and other impurities are removed and part of the heat generated during the processing is taken away, and then combined with the C-axis chuck 3 and the B-axis worktable 1 five-axis linkage to realize a variety of workpieces such as planes, free-form surfaces, microstructures, curved array structures, etc. The jet flow of surface shape and structure constrains ultra-precision processing of femtosecond laser.

Further, in the jet-constrained femtosecond laser processing method, by programming a CNC machine tool, the rotation and movement of the C-axis chuck 3 and the B-axis table 1 can be controlled, and the size of the processing area can be adjusted.

Further, by adjusting the valve connected to the first opening of the laser jet coupling device 9 and the valve connected to the second opening of the liquid tank 2, the flow of the solution in the liquid tank 2 and its depth can be controlled.

Further, the surface of the workpiece can be a flat surface or a free-form surface. The liquid that flows into the system during the processing is a chemical reagent solution, which only reacts with the workpiece under the action of the femtosecond laser. That is, through this method, a variety of liquid-phase environments can be realized. Or the jet flow of the free-form surface is constrained by femtosecond laser ultra-precision processing.

In order to make the description of the jet-confined femtosecond laser ultra-precision processing system and method of the present invention clearer, the following further describes the specific working process:

When working, first fix the plane mirror 11 and the plano-convex lens 10 inside the laser jet coupling device 9 through the adjustment block 8 and the internal stepped structure of the laser jet coupling device 9. The second mirror 7 is connected and fixed with the external clamping device. The mirror 5 is fixed on the bracket and forms an angle of 45° with the plane where the X axis is located. The laser jet coupling device 9 is fixed on the bracket 4, and the bracket 4 and the liquid tank 2 are respectively fixed on the C axis chuck 3 and the B axis Then fix the workpiece 12 on the bottom of the liquid tank 2 on the worktable 1, and access the liquid from the right side of the laser jet coupling device 9 and maintain a certain height and flow in the liquid tank 2, after which the femtosecond laser 6 passes The plano-convex lens 10 focuses on the surface of the workpiece 12 and keeps it perpendicular to the tangent plane at any point on the surface. Under the control of the CNC machine tool, the laser jet coupling device 9 can rotate around the Z axis and move along the X and Y axes and can drive the first mirror 5. The femtosecond laser light 6 makes the same movement, the liquid tank 2 can rotate around the Y axis and move along the Z axis and can drive the workpiece 12 to make the same movement, realizing a variety of planes, free-form surfaces, microstructures, curved array structures, etc. Femtosecond laser ultra-precision processing is restricted by the jet flow of the surface shape and structure of the workpiece.

While the femtosecond laser in the present invention acts on the surface of the workpiece, the chemical solvent produces micro-corrosion and other effects on defects such as the processed surface deterioration layer in the laser action zone, reducing the later corrosion time, and the solvent is under a certain pressure (not reaching the material facing the street). Removal pressure) reaches the processing surface, promotes the removal of defects such as the metamorphic layer and cleans up the debris and other impurities generated during the processing process, and takes away some of the heat generated during the processing process, reduces the impact of thermal effects on the processing process, and improves the surface of the workpiece The quality and surface accuracy can realize ultra-precision processing of femtosecond laser with jet confinement.

The above are only the preferred embodiments of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined in this document can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, this application will not be limited to the embodiments shown in this document, but should conform to the widest scope consistent with the principles and novel features disclosed in this document.

Claims

A jet-constrained femtosecond laser ultra-precision processing system, which is characterized by comprising a B-axis worktable, a liquid tank, a laser jet coupling device, a plane mirror, a plano-convex lens, a first mirror, a second mirror, a bracket, and a C-axis card plate;

The B-axis worktable can rotate around the Y-axis and move along the Z-axis. The liquid tank is used to place workpieces and is fixed on the B-axis worktable. The laser jet coupling device is located above the liquid tank and is fixed. On the support, the plane mirror and the plano-convex lens are located inside the laser jet coupling device, wherein the plano-convex lens can focus the laser light, and the plane mirror can transmit the light and separate the jet from the plano-convex lens; on the side wall of the laser jet coupling device A first hole for liquid to flow in is provided, and the position of the first hole in the height direction is lower than the plano-convex lens;

The second reflector is connected and fixed with the external clamping device, the first reflector can reflect the laser light and is fixed on the bracket, the bracket is fixed on the C-axis chuck, and the C-axis chuck The disc can rotate around the Z axis and move along the X axis and Y axis to realize the five-axis linkage of the entire processing system.
The jet-confined femtosecond laser ultra-precision machining system according to claim 1, wherein the first hole is connected to a first pipeline, and a valve is provided on the first pipeline.
The jet-confined femtosecond laser ultra-precision machining system according to claim 1, wherein a second hole for liquid to flow out is opened on the side wall of the liquid tank, and the second hole is connected with the second pipeline , A valve is provided on the second pipeline;

Further, there are two second holes, which are symmetrically arranged on the side wall of the liquid tank.
The jet-confined femtosecond laser ultra-precision processing system according to claim 1, wherein the first mirror and the second mirror are placed at an angle of 45° with the plane where the X axis is located.
The jet-confined femtosecond laser ultra-precision processing system according to claim 1, wherein the plano-convex lens and the plane mirror are both fixed by the adjustment block and the internal stepped structure of the laser jet coupling device.
The method for processing using the system according to claim 1, characterized in that it is as follows:

Step 1 Fix the laser jet coupling device on the bracket, the workpiece in the liquid tank, the liquid tank on the B-axis worktable, and the bracket on the C-axis chuck;

Step 2: After the femtosecond laser is focused by the plano-convex lens, it couples with the jet and reaches the surface of the workpiece to be processed, thereby achieving the purpose of removing material from the surface of the workpiece;

Step 3 A further chemical reaction occurs between the solution and the surface of the workpiece processed by the femtosecond laser to achieve the purpose of micro-corrosion and removal of surface deterioration layers and other defects, and under the action of the water jet, the femtosecond laser processing and the chemical reaction of the solution are broken. Remove impurities such as chips and take away part of the heat generated during processing;

Step 4 combines the five-axis linkage of the C-axis chuck and the B-axis worktable to realize jet-constrained femtosecond laser ultra-precision machining of a variety of workpiece surface shapes and structures such as planes, free-form surfaces, microstructures, and curved array structures.
A jet-constrained femtosecond laser ultra-precision machining method according to claim 6, characterized in that the rotation and movement of the C-axis chuck and the B-axis worktable can be controlled by programming a CNC machine tool. Adjust the size of the processing area.
A jet-confined femtosecond laser ultra-precision processing method according to claim 6, characterized in that the valve connected to the first opening of the laser jet coupling device and the second opening of the liquid tank are adjusted by adjusting The valve can control the flow and depth of the solution inside the tank.
The jet-confined femtosecond laser ultra-precision processing method according to claim 6, wherein the liquid flowing into the system during the processing is a chemical reagent solution, which only reacts with the workpiece under the action of the femtosecond laser.
A jet-confined femtosecond laser ultra-precision machining method according to claim 6, characterized in that the laser is coupled with the jet to reach the surface of the workpiece and maintain a tangent plane perpendicular to any point on the surface for processing, that is, normal processing.