CN112548339B

CN112548339B - Ultrasonic laser mechanical composite machining method, ultrasonic vibration clamp, machine tool and laser

Info

Publication number: CN112548339B
Application number: CN202011232396.4A
Authority: CN
Inventors: 王成勇; 李伟秋; 颜炳姜; 陈守峰; 郑李娟; 杜策之; 胡小月
Original assignee: Guangdong University of Technology; Conprofe Technology Group Co Ltd; Smartguy Intelligent Equipment Co Ltd Guangzhou Branch
Current assignee: Guangdong University of Technology; Conprofe Technology Group Co Ltd; Smartguy Intelligent Equipment Co Ltd Guangzhou Branch
Priority date: 2020-11-06
Filing date: 2020-11-06
Publication date: 2022-08-23
Anticipated expiration: 2040-11-06
Also published as: WO2022095652A1; CN112548339A; WO2022095804A1

Abstract

The invention relates to an ultrasonic laser mechanical composite processing method, an ultrasonic vibration clamp, a machine tool and a laser. The ultrasonic vibration is beneficial to the falling off of molten drops after the laser ablates the workpiece to be processed, and the contact between the workpiece to be processed and the laser is increased; the laser ablation effect can lead to waiting to process the damage layer that the work piece surface produced the crazing line, under ultrasonic vibration's effect, because high-frequency vibration's existence makes the release of material internal stress more complete after the crazing line forms, steadily increases crazing line's expansion, and then has steadily enlarged the expansion of damage layer, is favorable to the getting rid of the material when the cutter is to processing work piece finish machining, reduces cutting force and cutter wearing and tearing, promotes machining efficiency.

Description

Ultrasonic laser mechanical composite machining method, ultrasonic vibration clamp, machine tool and laser

Technical Field

The invention relates to the technical field of methods for processing hard and brittle materials, in particular to an ultrasonic laser mechanical composite processing method, an ultrasonic vibration clamp, a machine tool and a laser.

Background

Hard and brittle materials which are represented by ceramics, glass, sapphire and the like and are difficult to process have the characteristics of corrosion resistance, high temperature resistance, abrasion resistance, high hardness, high brittleness and the like, and are widely applied to various industries such as consumer electronics, semiconductors, molds, solar energy, aerospace and the like.

The hard and brittle material belongs to a typical difficult-to-machine material, the common machining modes of the hard and brittle material comprise grinding machining and milling machining, the grinding machining efficiency is low, the milling machining quality is poor, and in the two machining methods, the residual stress of the surface of a workpiece under the action of a cutter is high, micro cracks are easily generated, and the surface and subsurface damage is serious.

The hard and brittle material workpiece is processed by laser, and the workpiece is thermally damaged by laser ablation, so that the mechanical property of the material is reduced, and further removal by mechanical processing is facilitated. However, the large laser power processing damage causes the whole workpiece to crack, so that the stable crack propagation on the workpiece is difficult to realize, and the stable expansion of the damaged layer cannot be ensured.

Disclosure of Invention

In view of the above, it is necessary to provide an ultrasonic laser mechanical composite machining method, an ultrasonic vibration jig, a machine tool, and a laser, which can stably expand a crack in a workpiece and ensure stable expansion of a damaged layer, in order to solve the above-described problems.

An ultrasonic laser mechanical composite processing method comprises the following steps:

placing a workpiece to be processed on an ultrasonic vibration clamp, and transmitting ultrasonic vibration generated by the ultrasonic vibration clamp to the workpiece to be processed to enable the workpiece to be processed to generate ultrasonic vibration;

under the condition that the workpiece to be processed generates ultrasonic vibration, laser generated by a laser device carries out rough machining on the workpiece to be processed, the laser machining enables a damage layer to be generated on the workpiece to be processed, and the ultrasonic vibration is used for increasing the expansion of the damage layer;

and carrying out finish machining on the workpiece to be machined through the cutter.

In one embodiment, before the laser performs rough machining on the workpiece to be machined, the method further comprises the following steps:

the laser wavelength, pulse width and power are selected according to the material characteristics and processing requirements of the workpiece to be processed.

In one embodiment, after the laser wavelength, pulse width and power are determined, the method further includes:

the ultrasonic frequency and the ultrasonic amplitude adjusting range are determined according to the subsurface damage characteristic of the material to be processed in the laser processing, and the matching expansion loss of the ultrasonic and the laser is realized by matching with the laser power and the scanning speed.

In one embodiment, before finishing the workpiece to be machined by the tool, the method further comprises the following steps:

and selecting proper cutting depth, cutting width, feeding amount and cutting speed according to the subsurface damage characteristic of the workpiece material to be processed in the laser and ultrasonic vibration combined processing process.

In one embodiment, before finishing the workpiece to be machined by the tool, the method further comprises:

the cutter is arranged on the ultrasonic cutter handle, and the ultrasonic vibration generated by the ultrasonic cutter handle is transmitted to the cutter, so that the cutter generates ultrasonic vibration.

In one embodiment, the laser wavelength is in the range of 335 nm-1064 nm, the power is in the range of 10W-500W, and the pulse width is less than 30 ns.

In one embodiment, the frequency range of the ultrasonic wave is 16000 Hz-18000 Hz, and the amplitude regulation range of the ultrasonic wave is 2 μm-3 μm.

In one embodiment, the tool is a solid PCD micro-blade milling tool.

In one embodiment, the cutting depth range is within 0.2mm, the cutting width range is within 2mm, the feeding amount range is within 5000mm/min, and the cutting speed is 15000 r/min-24000 r/min.

In one embodiment, the workpiece to be processed is made of any one of glass, ceramic, sapphire, silicon carbide and single crystal silicon.

An ultrasonic vibration jig for realizing the ultrasonic laser mechanical composite machining method as defined in any one of the above.

A machine tool for implementing the ultrasonic laser mechanical composite machining method as defined in any one of the above.

A laser for implementing the ultrasonic laser mechanical composite machining method as claimed in any one of the preceding claims.

The ultrasonic laser mechanical composite processing method at least has the following advantages:

under the condition that the workpiece to be machined generates ultrasonic vibration, laser generated by the laser carries out rough machining on the workpiece to be machined, the laser machining enables a damaged layer with cracks to be generated on the workpiece to be machined, the ultrasonic vibration is used for increasing the expansion of the damaged layer, and then the workpiece to be machined is subjected to finish machining through the cutter. The ultrasonic vibration is beneficial to the falling off of the molten drop after the laser ablates the workpiece to be processed, so that the contact between the workpiece to be processed and the laser is increased; the laser ablation effect can lead to waiting to process the damage layer that the work piece surface produced the crazing line, under ultrasonic vibration's effect, because the existence of high frequency vibration makes the release of material internal stress more complete after the crazing line forms, the expansion of stable increase crazing line, and then the stable expansion that enlarges the damage layer is favorable to the removal of cutter to the material when processing work piece finish machining, reduce cutting force and cutter wearing and tearing, promote machining efficiency, improve the finish machining after-machining surface quality, realize that the high-efficient precision of hard brittle material is reduced and is got rid of.

Drawings

FIG. 1 is a schematic flow chart of a combined ultrasonic laser machining method according to an embodiment;

FIG. 2 is a simplified schematic diagram of an ultrasonic vibration jig, a laser, and a workpiece to be machined in one embodiment;

FIG. 3 is a schematic flow diagram of a method of ultrasonic laser mechanical composite machining in a preferred embodiment;

FIG. 4 is a graph of surface roughness after processing a glass workpiece using the processing method of the preferred embodiment;

FIG. 5 is a graph showing the surface roughness of a glass workpiece machined by a machining tool in a manner of rough machining using a No. 350 grinding wheel in a comparative example;

FIG. 6 is a depth SEM illustration of a damage layer after rough machining of a glass workpiece using the machining method of the preferred embodiment;

FIG. 7 is a depth SEM illustration of a sub-surface damage region after finishing a glass workpiece using a machining method according to a preferred embodiment;

FIG. 8 is a SEM illustration of the depth of a damage layer of a comparative example where a 350# grinding wheel was used to roughen a glass workpiece;

FIG. 9 is a depth SEM illustration of a sub-surface damage region after machining a workpiece with a tool in a comparative example.

In the figure, 10, a workpiece to be machined; 20. an ultrasonic vibration jig; 30. an ultrasonic generator 11, 11', a damage layer; 12, 12', subsurface damage region.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

Referring to fig. 1, an ultrasonic laser mechanical composite processing method according to an embodiment includes the following steps:

step S110, a workpiece to be processed is placed on the ultrasonic vibration clamp, and ultrasonic vibration generated by the ultrasonic vibration clamp is transmitted to the workpiece to be processed, so that the workpiece to be processed generates ultrasonic vibration. Specifically, as shown in fig. 2, the workpiece 10 to be processed is placed on the ultrasonic vibration jig 20, and the ultrasonic vibration jig 20 is electrically connected to the ultrasonic generator 30.

And step S120, under the condition that the workpiece to be processed generates ultrasonic vibration, roughly processing the workpiece to be processed by laser generated by the laser, generating a damage layer on the workpiece to be processed by laser processing, and increasing the expansion of the damage layer by the ultrasonic vibration. Therefore, when the laser is used for processing the workpiece to be processed, the ultrasonic vibration generated by the ultrasonic vibration clamp is transmitted to the workpiece to be processed.

And step S130, finishing the workpiece to be machined through the cutter. In particular, the tool may be a milling tool. For example, a solid PCD micro-blade milling tool.

Hereinafter, a preferred embodiment of the ultrasonic laser mechanical composite machining method will be described in detail as an example.

An ultrasonic laser mechanical composite processing method in a preferred embodiment includes the steps of:

step S201, selecting laser wavelength, pulse width and power according to the material characteristics and the processing requirements of the workpiece to be processed. The material of the workpiece to be processed can be glass, ceramics, sapphire, silicon carbide or monocrystalline silicon and other hard and brittle materials. For example, the laser has a wavelength range of 335nm to 1064nm, a power range of 10W to 500W, and a pulse width of less than 30 ns. If the power range of the laser is too large, the workpiece is likely to crack, and if the power of the laser is too small, the machining efficiency is too low, and therefore, a suitable range of 10W to 500W is selected. Preferably, the laser power is in the range of 10W to 100W. For example, in the present embodiment, a material of the workpiece to be processed is glass as an example.

The specific selection process is roughly as follows: and (3) placing the test workpiece on an ultrasonic vibration clamp, wherein the ultrasonic generator is not started temporarily. That is, the test workpiece does not generate ultrasonic vibration. And then adjusting laser parameters (including laser wavelength, pulse width, power and the like) to ensure that the test workpiece has better processing effect and does not crack, and the surface of the test workpiece has a certain damaged layer. Thereby determining parameters such as laser wavelength, pulse width and power of the laser.

Step S202, determining the ultrasonic frequency and the ultrasonic amplitude adjusting range according to the sub-surface damage characteristic of the material to be processed in the laser processing, and matching the ultrasonic and the laser to expand the damage by matching with the laser power and the scanning speed. For example, the frequency range of the ultrasonic wave is 16000Hz to 18000Hz, and the amplitude adjustment range of the ultrasonic wave is 2 μm to 3 μm.

The specific determination process is roughly as follows: after the parameters (laser wavelength, pulse width, power and the like) of the laser are adjusted, the parameters (including the frequency and amplitude of the ultrasonic wave) of the ultrasonic wave are adjusted, so that the further expansion of the damage layer on the test workpiece can be ensured. After the laser parameters and the ultrasonic parameters are determined, the workpiece to be processed can be processed. The workpiece to be machined at this time is the same material as the test workpiece described above, e.g., is not glass. If workpieces of different materials need to be processed, the laser parameters and the ultrasonic parameters need to be selected again.

Step S203, a workpiece to be processed is placed on the ultrasonic vibration clamp, and the ultrasonic vibration generated by the ultrasonic vibration clamp is transmitted to the workpiece to be processed, so that the workpiece to be processed generates ultrasonic vibration. In the present embodiment, the workpiece to be processed is directly placed on the ultrasonic vibration jig. In other embodiments, the workpiece to be processed may be indirectly placed on the ultrasonic vibration jig as long as it is ensured that the workpiece to be processed can generate ultrasonic vibration meeting the conditions.

Step S204, under the condition that the workpiece to be processed generates ultrasonic vibration, laser generated by the laser device carries out rough machining on the workpiece to be processed, the laser machining enables a damage layer to be generated on the workpiece to be processed, and the ultrasonic vibration is used for increasing the expansion of the damage layer. That is, in the present embodiment, a laser beam is used to process a workpiece, and ultrasonic vibration is generated in the workpiece, so that the laser beam and the ultrasonic vibration are combined to process the processed workpiece.

The laser processing ablates the material of the workpiece to be processed, and the ultrasonic vibration is beneficial to the shedding of molten drops of the ablated workpiece by the laser, so that the contact between the workpiece to be processed and the laser is increased; secondly, the laser ablation effect can cause the surface of the workpiece to be processed to generate a damaged layer of microcracks, and under the action of ultrasonic vibration, the internal stress of the material is released more completely due to the existence of high-frequency vibration after the microcracks are formed, so that the expansion of the microcracks is increased stably, and further the expansion of the damaged layer is enlarged stably. Through experimental analysis, the depth of a damaged layer generated by laser processing on the surface of the glass is controlled to be approximately 100-130 μm by adopting a mode of rough processing by matching laser and ultrasonic vibration, and the damaged layer can be stably expanded by about 15-20% (compared with a mode of processing only by laser).

And S205, mounting the cutter on the ultrasonic cutter handle, and transmitting the ultrasonic vibration generated by the ultrasonic cutter handle to the cutter to enable the cutter to generate ultrasonic vibration. Therefore, ultrasonic vibration is added to the cutter, and the surface quality of the workpiece to be processed can be further improved. In this embodiment, the tool is a solid PCD micro-blade milling tool. Of course, the tool may also be a milling tool of other materials. In another embodiment, step S205 may be omitted and the workpiece may be machined by using the solid PCD microblade cutting tool as it is.

And S206, selecting proper cutting depth, cutting width, feeding amount and cutting speed according to the subsurface damage characteristic of the workpiece material to be processed in the laser and ultrasonic vibration combined processing process. For example, the cutting depth is within 0.2mm, the cutting width is within 2mm, the feed rate is within 5000mm/min, and the cutting speed is 15000r/min to 24000 r/min. By setting the cutting depth, cutting width, feed and cutting speed to the above parameters, efficient removal of workpiece surface material (which may be a damaged layer or a damaged layer + a partially undamaged layer) can be ensured while reducing tool wear.

And step S207, finishing the workpiece to be machined through the cutter. In the processing step in the embodiment, the workpiece is subjected to the laser and ultrasonic vibration combined processing in the front, so that a damaged layer is generated on the surface of the processed workpiece, the mechanical property of the material is reduced, and compared with the traditional mode of directly processing the workpiece by using a cutter in the subsequent processing of the workpiece by using the cutter, the cutting force and the cutter abrasion can be reduced, and the processing efficiency is improved.

According to experimental analysis, after laser and ultrasonic vibration combined rough machining, the mode of finish machining of the integral PCD micro-blade milling cutter and the ultrasonic cutter handle is adopted, the quality of the machined surface of the glass can reach about 5 nm-10 nm, and compared with the mode of direct grinding machining of the cutter, the roughness of the surface of a workpiece is reduced by more than 20%. As shown in fig. 4, after the glass is processed by the ultrasonic laser machining method, the glass surface roughness Sa is 10 nm. As shown in fig. 5, the roughness Sa of the surface of the workpiece obtained by performing rough machining using a 350# grinding wheel and finish machining using a tool in the conventional process (as a comparative example) was 12 nm. The workpiece processed by the processing method of the preferred embodiment has smaller surface roughness and higher surface quality.

Referring to fig. 6, a depth SEM of the damaged layer after the glass workpiece is roughly processed by using the combined processing of laser and ultrasonic vibration, wherein the depth of the damaged layer 11 is 115 μm. Referring to fig. 7, a schematic depth SEM of the subsurface damaged region 12 is shown in the drawing, in which the depth of the subsurface damaged region 12 is 16.3 μm, in order to finish the glass workpiece by using the integrated PCD microblade milling tool and the ultrasonic tool shank after the combined processing of laser and ultrasonic vibration. FIG. 8 is a SEM diagram of the depth of a damaged layer 11 'for rough machining of a glass workpiece with a 350# grinding wheel, wherein the depth of the damaged layer 11' is 120 μm. Referring to FIG. 9, a depth SEM of a sub-surface damage region 12 'after machining a workpiece with a tool is shown, wherein the depth of the sub-surface damage region 12' is 45.4 μm. Obviously, the glass workpiece processed by the preferred embodiment has a smaller depth of the subsurface damage region 12, meaning that the surface quality of the glass workpiece is higher.

Referring to the table below, a comparison table of cutting forces when a workpiece is roughly machined and finely machined by the machining method of the preferred embodiment and roughly machined by a 350# grinding wheel and then finely machined by a tool is shown. When the glass workpiece is finish machined by the machining method in the preferred embodiment, the maximum axial cutting force Fz Max is 15.04N, and the maximum y-direction cutting force Fy Max is 1.481N. When the 350# grinding wheel is used for rough machining and then a cutter is used for finish machining, the axial maximum cutting force Fz Max is 32.41N, and the y-direction maximum cutting force Fy Max is 3.6N. By contrast, according to the machining method of the present preferred embodiment, the maximum cutting force in the axial direction (Z direction, direction in which the tool approaches the workpiece) is reduced by 113% or more, and the maximum cutting force in the Y direction is reduced by 100% or more.

The smaller the cutting force is, the smaller the breakage probability in the cutting process is, which means that the material is removed more smoothly, and the pits on the surface are less broken after the machining, so the machining quality is higher; meanwhile, the cutting force is small, the abrasion to the cutter is small, the impact is small, the abrasion to the cutter can be slowed down, and the service life of the cutter is prolonged.

The invention also provides an ultrasonic vibration clamp which is used for realizing the ultrasonic laser mechanical composite processing method.

The invention also provides a machine tool which is used for realizing the ultrasonic laser mechanical composite machining method.

The invention also provides a laser which is used for realizing the ultrasonic laser mechanical composite processing method.

All possible combinations of the technical features of the above embodiments may not be described for the sake of brevity, but should be considered as within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. The ultrasonic laser mechanical composite processing method is characterized by comprising the following steps of:

placing a workpiece to be processed made of a hard and brittle material on an ultrasonic vibration clamp, and transmitting ultrasonic vibration generated by the ultrasonic vibration clamp to the workpiece to be processed to enable the workpiece to be processed to generate ultrasonic vibration;

under the condition that the workpiece to be processed generates ultrasonic vibration, laser generated by a laser device carries out rough machining on the workpiece to be processed, the laser machining enables a damaged layer with cracks to be generated on the workpiece to be processed, and the ultrasonic vibration is used for increasing the expansion of the damaged layer;

2. The ultrasonic laser mechanical composite processing method according to claim 1, further comprising, before the laser performs rough processing on the workpiece to be processed:

3. The ultrasonic laser mechanical composite processing method of claim 2, further comprising, after determining the laser wavelength, pulse width and power:

the ultrasonic frequency and the ultrasonic amplitude adjusting range are determined according to the subsurface damage characteristic of a workpiece material to be processed in laser processing, and the matching expansion loss of the ultrasonic and the laser is realized by matching with the laser power and the scanning speed.

4. The ultrasonic laser mechanical composite machining method according to claim 3, further comprising, before finish machining the workpiece to be machined by the tool:

5. The ultrasonic laser mechanical composite machining method according to claim 3, further comprising, before finish machining the workpiece to be machined by the tool:

6. The ultrasonic-laser-mechanical composite processing method as claimed in claim 3, wherein the laser wavelength range is 335nm to 1064nm, the power range is 10W to 500W, and the pulse width is less than 30 ns.

7. The ultrasonic laser mechanical composite processing method according to claim 6, wherein the frequency range of the ultrasonic wave is 16000Hz to 18000Hz, and the amplitude adjustment range of the ultrasonic wave is 2 μm to 3 μm.

8. The ultrasonic laser mechanical composite machining method according to claim 1, wherein the tool is a solid PCD micro-blade milling tool.

9. The ultrasonic laser mechanical composite processing method according to claim 4, wherein the cutting depth range is within 0.2mm, the cutting width range is within 2mm, the feed amount range is within 5000mm/min, and the cutting speed is 15000r/min to 24000 r/min.

10. The ultrasonic laser mechanical composite processing method according to claim 1, wherein the material of the workpiece to be processed is any one of glass, ceramic, sapphire, silicon carbide, and single crystal silicon.

11. An ultrasonic vibration jig for carrying out the ultrasonic laser mechanical composite machining method according to any one of claims 1 to 10.

12. A machine tool for carrying out the ultrasonic laser mechanical composite machining method according to any one of claims 1 to 10.

13. A laser for carrying out the ultrasonic laser mechanical composite machining method according to any one of claims 1 to 10.