CN107649755B - High-speed arc discharge grinding composite processing method - Google Patents

Abstract

A high-speed electric arc discharge grinding combined machining method adopts a tool electrode with an electrode side surface capable of forming electric arc discharge and a grinding layer at the bottom of the electrode to combine the high-speed electric arc discharge machining and the grinding machining. The invention realizes the high-efficiency, low-cost and high-precision processing of various conductive materials in one device.

Description

High-speed arc discharge grinding compound machining method

technical field

The invention relates to a conductive material, in particular to a high-speed arc discharge grinding compound processing method for the conductive material.

Background technique

High-speed arc discharge machining is a new machining method specially proposed for the urgent need of high-efficiency and low-cost machining of difficult-to-cut materials. The principle is to use the high temperature of the arc plasma generated by the discharge to quickly melt or even gasify the workpiece material, and cooperate with the high-speed flow field between the tool electrode and the workpiece to quickly rush the eroded material out of the gap. Machining of difficult-to-cut materials with a certain conductivity. However, due to the extremely high energy density of the arc, in order to achieve high efficiency, the energy of each discharge pulse is also very large, which results in large etch pits on the surface of the workpiece after arc discharge machining, forming a rough surface. The surface after EDM is cooled by the working fluid, and it is easy to form a recast layer on the surface to increase the hardness. In addition, the surface is relatively rough, which may have a negative impact on the subsequent finishing and shorten the service life of the tool. If the combination of arc discharge machining and grinding can be used in the machining process, not only can high-efficiency and low-cost machining be achieved, but also problems such as surface roughness after arc discharge machining can be effectively solved. Specifically, a specially designed tool electrode (which can form discharge on the side and has a grinding layer at the bottom) is used to realize simultaneous arc discharge machining and grinding; the side of the electrode and the workpiece form a high-energy arc discharge thermal erosion to remove the workpiece. material, remove most of the material and form a relatively rough machined surface. At the same time, the surface of the workpiece after arc machining is ground by applying the grinding layer at the bottom of the electrode, and finally a high-quality surface is obtained. Therefore, through the high-speed arc discharge grinding compound machining method, the high-speed arc discharge grinding compound machining can be realized, and the functions of high-efficiency, low-cost and precision machining can be realized on one arc-discharge machining machine tool.

In recent years, thanks to the rapid development of arc discharge machining, many scholars have proposed various new methods for removing workpiece materials based on arc discharge, and these methods can effectively solve some problems faced in machining, but these same The method also has some shortcomings. In the last century, Weifang Fangzi Woodworking Machinery Factory disclosed their respective anode mechanical cutting devices and partial structures in patent CN87212711 and Suzhou Electric Machining Machine Tool Research Institute Co., Ltd. in patent CN201644967. There are generally two types of anode mechanical cutting machines: disc type and belt type. Connect the workpiece to the anode of the DC power supply, connect the cutting electrode to the negative pole of the power supply, and spray conductive electrolyte at the cutting port. During the cutting process, when the tool is in contact with the front of the workpiece, the high-speed and direct-moving tool (iron belt) scratches and removes the anode purification film on the workpiece, forming a loop, generating electric sparks and short electric solitary discharges, and the instantaneous local high temperature reaches 5000 ℃ above. However, the machining accuracy and surface roughness of the anode mechanical cutting technology are poor, and the tool electrode is easy to wear, and it is usually only used for cutting blanks or blanking.

Ye Liangcai disclosed a new technology of electric discharge mechanical grinding combined processing method and equipment in patent CN87106421A. This technology is named as electric melting and blasting machining, which is a method of realizing arc discharge machining with low voltage and high current. When working, the cutter head tool is connected to the negative pole of the power supply, and the workpiece is connected to the positive pole of the power supply, and a discharge arc with high energy density will be generated between the poles, which will rapidly melt and vaporize the surface of the workpiece and quickly explode and throw away. At the same time, the tool and the workpiece perform relative rotational motion to realize the forced mechanical motion of the discharge arc to break the arc, so as to achieve efficient and stable arc discharge machining. At the same time, after searching the prior art, it is found that patent CN 1061175A discloses a non-contact strong electric machining technology similar to electric melting explosion, which is called short arc machining.

However, due to the large amount of heat generated by the application of a discharge current of thousands of amperes in the process of electric melting explosion and short arc, it is difficult to discharge in time, which is likely to cause the electrode, workpiece surface and machine tool components to rise in temperature too high, resulting in damage to the surface tissue of the workpiece. . Therefore, the surface quality of the workpiece processed by this technology is low, and it is not suitable for occasions with high requirements on the workpiece surface. At the same time, the disc tool electrode and its rotating motion are used, so that the method is mainly suitable for the processing of cylindrical parts such as rollers and grinding rollers, as well as simple grooving processing.

The distributed arc electric erosion processing method disclosed in the patent CN 1693024A by General Electric Company is a kind of relative motion between the end face of the hollow tubular electrode and the workpiece surface to generate a distributed discharge arc and use the distributed arc for processing. Using this method to perform layer-by-layer milling to profile a curved surface can achieve an efficient material removal rate. In the patent CN1397399A, Suzhou Zhongte Electromechanical Technology Co., Ltd. disclosed a method for high-efficiency milling and electrical discharge machining using the rotation of a simple hollow long electrode, and an experimental comparison of hollow long electrodes with different aspect ratios was carried out. Suzhou Zhongte Electromechanical Technology Co., Ltd. also mentioned in the patent CN 1597216A that the use of hollow long electrodes as the main and supplemented by other devices can perform efficient cooling and chip removal during high-speed discharge. However, the above patents are all typical arc discharge machining methods, and processing effects similar to high-speed arc discharge machining can be achieved by applying arc plasma with high energy density. However, all of them only describe the arc discharge machining process and method, and fail to carry out deeper synchronous grinding processing on the machined surface after arc machining, so as to further improve the quality of the machined surface.

At the same time, after searching the prior art, it is found that the electrolytic grinding compound machining is a kind of electric discharge compound machining method that has been widely used in recent years. This technology is to increase the power supply of electrolytic machining on the basis of the traditional grinding machine. By loading the machining voltage between the grinding wheel and the workpiece, and at the same time with the electrolyte sprayed by the grinding layer, not only can the material be removed by grinding the grinding wheel, but also the grinding wheel and the workpiece can be removed. Electrolytic machining removes material between workpieces. However, this technology is mainly based on grinding wheel grinding to remove workpiece materials, supplemented by electrolytic machining to remove materials. However, the processing efficiency is low, and its processing efficiency is not significantly improved compared with traditional grinding, which is far lower than the efficiency of arc discharge machining, so it is not suitable for high-efficiency, low-cost and large allowance removal processing of difficult-to-cut materials. The technology uses both grinding and electrolytic machining, and its processing efficiency is limited; however, the method proposed by the present invention is to first use arc discharge to efficiently remove materials, and then use grinding in the same process to further improve the quality of the machined surface. precision.

The high-speed arc discharge machining method is mentioned in the present invention, and the method is the high-speed electric discharge machining method of cluster electrode published in patent CN102091839A by Zhao Wansheng, Gu Lin, etc., members of the research group. This technology is a typical arc discharge machining method based on a cluster electrode disclosed in the patent CN1657208A, which realizes the hydrodynamic arc breaking mechanism of strengthening the porous inner flushing liquid. After recent years of research, this method has achieved good results in the removal of high ^- efficiency, low-cost and large allowances for difficult-to-cut materials. Current), the highest efficiency in processing titanium alloys can reach 21000mm ³ /min (using 600A current), and the maximum material removal rate when processing aluminum-based silicon carbide materials can also reach 8000mm ³ /min (using 600A current), these processing The efficiency is several times or even ten times that of traditional mechanical cutting methods. However, despite the high efficiency of high-speed arc discharge machining, the surface of the workpiece after machining is relatively rough, which affects the surface quality and machining accuracy, and restricts its further application and promotion. Therefore, at present, this method is mainly used in rough machining of parts with high efficiency and large allowance removal.

However, in order to realize high-efficiency, low-cost, and high-precision machining of various conductive materials in one device, and to further expand the application field and scope of high-speed arc discharge machining, it is necessary to optimize and further expand the existing arc discharge machining methods. Research to solve the problem of poor surface quality after processing.

SUMMARY OF THE INVENTION

In view of the deficiencies of the above-mentioned existing processing methods, the present invention provides a high-speed arc discharge grinding composite processing method. The method uses a tool electrode that can form discharge on the side of the electrode and has a grinding layer at the bottom of the electrode. The composite grinding process can not only realize efficient and low-cost machining of difficult-to-cut materials, but also effectively solve the problem of poor surface quality after machining in arc discharge machining.

The technical scheme adopted by the present invention to solve the technical problem is as follows:

A high-speed arc discharge grinding compound machining method is characterized in that the method comprises the following steps:

1) Install the workpiece on the machine tool table, the tool electrode is installed on the machine tool spindle, and the installation axis of the tool electrode is coincident with the axis of the machine tool spindle; the working medium in the working medium container enters the tool electrode through the flushing inlet on the tool electrode, Through the inner channel of the tool electrode, it reaches the processing area through the side wall and bottom outlet of the tool electrode to realize the internal flushing of the electrode during processing, and finally returns to the working medium container through the machine tool table to form a working medium circuit;

2) The workpiece and the tool electrode are respectively connected to the two poles of the machining power supply, and the side surface of the tool electrode and the workpiece form a discharge during processing under the action of the power supply. Feed to the specified depth, and move along the tangential direction of the workpiece surface. The side surface of the tool electrode always maintains a certain gap with the surface of the workpiece to implement electrical discharge and form an electrical discharge machining area, and the bottom surface of the tool electrode cuts into the workpiece after arc discharge machining. The surface has a certain depth for further grinding;

3) According to the shape and contour of the workpiece to be processed, the tool electrode is driven by the machine tool spindle to move along the X, Y or Z axis of the machine tool, and the workpiece is installed on the machine tool table, and the table can be along the machine tool A axis or B. Rotation of the shaft can realize the movement of the workpiece, and the linkage between the tool electrode and the workpiece realizes the tangential movement of the tool electrode along the surface of the workpiece; after finishing one layer of processing, the tool electrode feeds a depth in the axial direction to start the new layer processing, and the process is repeated until Finish processing.

The processing power supply is a DC power supply with a peak current of 1A-1000A, a pulse width of 1μs-10ms, and a pulse interval of 0-10ms.

The working medium is a working medium flowing between the tool electrode and the workpiece at a pressure of more than 0.1 MPa, including water-based working fluid, mist or gas.

The rotation speed of the tool electrode is 100RPM～400,000RPM.

The feed layer depth of the tool electrode along the axis direction is 0.1 μm˜3000 μm.

The bottom end face of the tool electrode is provided with an electrode grinding layer, which is fixedly connected with the electrode and can realize the grinding process of the area to be ground.

Compared with the prior art, the beneficial effects of the present invention are:

The high-speed arc discharge grinding composite machining method of the present invention solves the following problems:

1) Effectively combine high-speed electrical discharge machining and grinding to achieve high-efficiency, low-cost, and high-precision machining of various conductive materials in one device;

2) The method of the present invention can realize the grinding process on the surface formed by the discharge in a short period of time after the end of the arc discharge; at this time, because the process of removing the workpiece by the arc discharge has just ended, the surface temperature of the workpiece still remains at the time of the discharge. Part of the high temperature, so that the surface of the workpiece has a softening effect, which is easy to carry out grinding.

3) The present invention effectively improves the surface quality of arc discharge machining, and further expands the application field and scope of high-speed arc discharge machining.

Description of drawings

Fig. 1 is the schematic diagram of the high-speed arc discharge grinding compound processing device of the present invention;

Fig. 2 is the principle diagram of the high-speed arc discharge grinding compound machining method of the present invention and an enlarged view of its machining area;

In the figure: 1: Discharge power supply, 2: Machine tool body, 3: Work piece, 4: Tool electrode, 5: Workbench, 6: Working medium storage box, 7: Processing area, 8: Electrode grinding layer, 9: Plasma , 10: discharge pit, 11: area to be ground, 12: working medium.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention should not be limited by this.

Please refer to FIG. 1 first. FIG. 1 is a schematic diagram of a high-speed arc discharge grinding compound machining device of the present invention. The high-speed arc discharge grinding compound machining method of the present invention includes the following steps:

1) The workpiece 3 is installed on the machine tool table 5, the tool electrode 4 is installed on the machine tool spindle, and the installation axis of the tool electrode coincides with the axis of the machine tool spindle; the working medium in the working medium container 6 passes through the flushing liquid on the tool electrode 4. The inlet enters the tool electrode, passes through the inner channel of the tool electrode, and reaches the processing area 7 through the side wall and bottom outlet of the tool electrode to realize the internal flushing of the electrode during processing, and finally returns to the working medium container 6 through the machine tool table 5 to form a working medium circuit;

2) The workpiece 3 and the tool electrode 4 are respectively connected to the two poles of the processing power supply 1, and the side surface of the tool electrode 4 forms a discharge with the workpiece 3 during the power-on machining. The vertical direction of the tool electrode 4 is fed to the specified depth, and the feed movement is in the tangential direction of the workpiece surface. The side surface of the tool electrode 4 always maintains a certain gap with the surface of the workpiece 3 to implement electrical discharge and form an electrical discharge machining area. At the same time, the bottom surface of the tool electrode 4 Cut into the surface of the workpiece after arc discharge machining to a certain depth for further grinding;

3) According to the shape and contour of the workpiece 3 to be processed, the tool electrode 4 is driven by the main shaft of the machine tool to move along the X, Y or Z axis of the machine tool, and the table 5 can rotate along the A axis or the B axis of the machine tool to realize the workpiece. 3 movement, the linkage between the tool electrode 4 and the workpiece 3 realizes the tangential movement of the tool electrode along the surface of the workpiece; after the completion of one layer processing, the tool electrode 4 feeds a depth in the axial direction to start the new layer processing, and the process is repeated until the completion processing.

Further, the processing power supply refers to a DC power supply with a peak current of 1A-1000A, the pulse width is 1μs-10ms, and the pulse interval is 0-10ms; the working medium refers to the power supply between the tool electrode and the workpiece. The working medium flowing at a pressure of more than 0.1 MPa can be water-based working fluid, mist or gas; further, the rotational speed of the tool electrode is 100RPM-400,000RPM; further, the tool electrode is fed along the axis direction The layer depth is 0.1 μm-3000 μm, and the bottom end face of the tool electrode 4 has an electrode grinding layer 8 , which is fixedly connected with the tool electrode 4 and can realize the grinding process of the area to be ground 11 .

Further in conjunction with accompanying drawing 2, the high-speed arc discharge grinding composite machining method of the present invention is to use special tool electrodes 4 (the side of the electrode can form discharge, and the bottom of the electrode has a grinding layer), and the high-speed arc discharge machining and grinding are used. Compounding by machining. This technique requires the tool electrode to rotate and assist the high-speed flushing of the machining area. When this technology is implemented, firstly, arc discharge is formed between the side of the tool electrode and the workpiece, and the high-temperature plasma 9 formed by the arc discharge in the discharge point area 7 thermally removes the material of the workpiece 3, and at the same time, a large discharge pit is formed after the arc discharge machining. 10. Its surface is very rough and needs to be further ground and smoothed, so it is called the area to be ground 11; then, the grinding layer 8 at the bottom of the tool electrode 4 grinds the area to be ground 11 after arc machining, and smoothes the workpiece. surface to achieve high surface quality machining. During this machining process, arc discharge occurs between the outer circular surface of the tool electrode 4 and the workpiece 3, and the combined action of the tool rotation and the internal flushing causes the arc plasma 9 to slip and deflect the arc, which avoids burning the surface while removing the material. ; The electrode grinding layer 8 also has the effect of flushing, which can efficiently cool the machined surface, avoid the surface heating up and cause burns, and can help the debris removed by grinding to be discharged from the machining area through the chip flute in the grinding layer. .

best practice

The high-speed arc discharge grinding composite machining method of the present invention is described according to Fig. 1 and Fig. 2: select a CNC machine tool with 5-axis linkage, select a stainless steel square material as the workpiece material 3, select a special tool electrode 4 (the side of the electrode can form a discharge, And the bottom of the electrode has a grinding layer), the workpiece 3 is fixed on the machine tool table 5 and the tool electrode 4 is connected to the machine tool spindle, and the tool electrode rotates at a speed of 3000r/min. The workpiece 3 and the tool electrode 4 are respectively connected to the positive and negative ends of the discharge power supply 1, and the power supply parameters are set as: peak voltage 90V, peak current 500A, pulse width 5000μs and pulse interval 3000μs. The working fluid medium 12 is selected as a water-based emulsion, and the pressure of the working fluid medium flushing the outlet is 1.6 MPa. Under the above process conditions, high-speed arc discharge grinding composite processing is carried out. First, move the tool electrode 4 to the outside of the contour of the workpiece 3, close to the edge of the workpiece material, and the tool electrode 4 is lowered to a position 2 mm below the upper edge of the workpiece 3. When the tool electrode 4 is fed tangentially along the surface of the workpiece 3, the side surface of the tool electrode 4 is first discharged with the workpiece 3, and the arc discharge generates a high-temperature plasma 9 to erode the material of the workpiece 3 to form the surface of the discharge pit 10, which is relatively Roughness, the roughness Ra is preliminarily estimated that the measured value is as high as 16 μm or more. Since this rough machined surface needs to be further ground, the surface area is referred to as the area to be ground 11 in this invention. Then, with the lateral feed of the tool electrode 4, the grinding layer 8 at the bottom of the tool electrode 4 will move to the area to be ground 11 for grinding and smoothing the machined surface to improve the surface quality. When this method is used to process stainless steel materials, preliminary experimental results show that the processing efficiency can reach more than 2000mm ³ /min, and the surface roughness after processing is expected to be less than Ra3.2. Compared with the traditional arc processing, the surface has Great improvement.

Claims (5)

1. A high-speed arc discharge grinding composite processing method is characterized by comprising the following steps:

1) a workpiece (3) to be machined is arranged on a machine tool workbench (5), a tool electrode (4) is arranged on a main shaft of a machine tool, and the installation axis of the tool electrode (4) is superposed with the axis of the main shaft of the machine tool; working media in the working medium container (6) enter the tool electrode through a flushing liquid inlet on the tool electrode (4), and reach a machining area (7) through an internal channel of the tool electrode and a side wall outlet and a bottom outlet of the tool electrode, so that flushing liquid in the electrode during machining is realized, and finally, the working media flow back to the working medium container (6) through the machine tool workbench (5) to form a working medium loop;

2) respectively connecting a workpiece (3) and a tool electrode (4) with two poles of a processing power supply (1), discharging the side surface of the tool electrode (4) and the workpiece (3) after electrification, generating plasma (9) and corroding workpiece materials to form the surface of a discharge corrosion pit (10), wherein the tool electrode (4) is driven by a machine tool main shaft to rotate, simultaneously, the feed is fed to a specified depth along the vertical direction of the surface of the workpiece (3) and is fed along the tangential direction of the surface of the workpiece, the side surface of the tool electrode (4) keeps a certain gap with the surface of the workpiece (3) all the time to carry out electric discharge and form an electric discharge machining area (7), simultaneously, the bottom surface of the tool electrode (4) is cut into the surface of the workpiece after the arc discharge machining for a certain depth, further grinding the surface of the workpiece through an electrode grinding layer (8) arranged on the bottom surface of the tool electrode (4);

3) according to the shape and the contour of a workpiece (3) to be machined, the tool electrode (4) is driven by a main shaft of a machine tool to move along the X, Y or Z axis of the machine tool, meanwhile, the workbench (5) rotates along the A axis or the B axis of the machine tool to realize the movement of the workpiece (3), and the tool electrode moves tangentially along the surface of the workpiece through the linkage of the tool electrode (4) and the workpiece (3); after completing one layer of machining, the tool electrode (4) is axially advanced by a depth to start a new layer of machining, and the process is repeated until the machining is completed.

2. The high-speed arc discharge grinding hybrid machining method according to claim 1, wherein the machining power supply (1) is a dc power supply having a peak current of 1A to 1000A, a pulse width of 1 μ s to 10ms, and a pulse interval of 0 to 10 ms.

3. The high-speed arc discharge grinding composite machining method according to claim 1, wherein the working medium is a working medium flowing between the tool electrode (4) and the workpiece (3) at a pressure of 0.1MPa or more, and includes a water-based working fluid or mist.

4. The high-speed arc discharge grinding composite machining method according to claim 1, wherein the tool electrode rotation speed is 100RPM to 400,000 RPM.

5. The high-speed arc discharge grinding composite machining method according to claim 1, wherein the depth of the feed layer of the tool electrode in the axial direction is 0.1 μm to 3000 μm.

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