A pulsed discharge cutting method based on a hard and brittle conductive material

Abstract

The present invention discloses a pulse discharge cutting method based on a hard and brittle conductive material. When cutting a hard and brittle conductive material, a high-frequency pulse current is applied to the hard and brittle conductive material, so that an electromagnetic thermal effect is generated at the tip of the machining crack that is starting to expand. The material in the crack tip region rapidly melts, and the crack tip becomes blunt, so that the crack cannot continue to expand or the propagation path of the crack is changed. As a result, during machining, the removal changes from large-piece fragmentation at the beginning to small-piece fragmentation, greatly improving the surface quality. The specific steps are to install a pulse power supply on the machine tool and connect it to both ends of the workpiece to form a current loop. Then, the pulse power supply parameters are adjusted, and the hard and brittle conductive workpiece installed on the machine tool table is cut. The present invention is an effective processing method for hard and brittle conductive difficult-to-machine materials, improving the machining surface quality of the materials, greatly improving the service performance and life of the workpiece, and having broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of cutting hard and brittle materials, and particularly relates to a pulsed discharge cutting method for hard and brittle conductive materials. Background Art

[0002] In modern manufacturing, especially in the fields of national defense, military industry, aerospace, etc., a large number of high-quality and precision products made of hard and brittle conductive materials (such as alloy die steel, conductive ceramics, quenched steel, etc.) are required, such as integrated circuits, precision radars, precision machine tools, etc. These hard and brittle materials have characteristics such as high hardness, high brittleness, and high melting point, which are very different from the physical properties of general ductile metals. Their machining process is different from the plastic shearing process of general ductile metal materials and also different from the pure fracture machining process of highly brittle materials (such as diamond); that is, when using a tool to cut hard and brittle conductive materials, under the extrusion of the cutting edge, cracks are generated near the cutting edge. The cracks first expand forward and downward, and the depth exceeds the cutting depth; then they expand upward while advancing; finally, they pass through the upper free surface, forming large flake-shaped chips, and large and deep pits are formed on the cutting surface, which is called large-scale extrusion cracking, resulting in an increase in the surface roughness of the machining surface, deterioration of the machining surface quality, and it is very difficult to ensure and improve the machining accuracy.

[0003] In order to obtain better machining surface quality, the current machining methods for hard and brittle conductive materials mainly used all have deficiencies such as low machining surface quality, expensive machining equipment, and inconvenient operation and use. Therefore, the cutting of hard and brittle conductive difficult-to-machine materials has always been a key point and a difficult point in research. Summary of the Invention

[0004] The purpose of the present invention is to provide a conductive cutting method for hard and brittle conductive materials, which improves the machining surface quality of hard and brittle conductive materials without reducing the machining efficiency, increasing the processes and energy consumption, that is, a pulsed discharge cutting method for hard and brittle conductive materials is proposed: when machining (such as grinding, turning, milling) hard and brittle conductive materials with a machine tool, a high-frequency pulsed current is passed through the workpiece of the hard and brittle conductive material, so that the current concentrates and flows around the crack tip region, that is, a strong electromagnetic thermal effect is generated, a large amount of heat and compressive stress are generated in the crack tip region, the material in the crack tip region is instantaneously melted, so that the crack cannot continue to extend and grow, realizing the stop of the dynamic crack propagation, or under the action of the cutting force, the crack propagation direction is changed, so that the large-scale fragmentation removal occurring during cutting is transformed into small-piece fragmentation removal, and the machining surface changes from forming large and deep pits to small and shallow pits, thereby improving the machining quality and machining accuracy of the workpiece surface, greatly improving the service performance and life of the workpiece, and having broad application prospects.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A pulsed discharge cutting method for hard and brittle conductive materials, comprising the following steps:

[0006] (1) Install the pulsed power supply device:

[0007] Install the high-frequency pulsed power supply device at a suitable position on the processing machine tool;

[0008] (2) Install the workpiece:

[0009] Use a fixture to install the hard and brittle conductive material workpiece on the machine tool workbench;

[0010] (3) Install the special connector for the anode of the pulsed power supply:

[0011] Connect the anode special connector with the power anode cable, then install the anode special connector on the machine tool, and finally make the anode connector contact one end of the workpiece;

[0012] (4) Install the special connector for the cathode of the pulsed power supply:

[0013] Connect the cathode special connector with the power cathode cable, then install the cathode special connector on the machine tool, and finally make the cathode connector contact the other end of the workpiece;

[0014] (5) Turn on the pulsed power supply:

[0015] First, set the processing parameters of the pulsed power supply, and then turn on the power supply to perform pulsed discharge on the workpiece. The output voltage of the pulsed power supply can be set to 10 KV and 30 KV, and the output current is adjusted between 0 - 500 A according to the processing conditions;

[0016] (6) Start the cutting machine tool:

[0017] Start the processing machine tool and perform mechanical cutting using a metal cutting tool;

[0018] Furthermore, when the fixture positions and clamps both ends of the workpiece in step (2), insulation treatment should be performed at the contact points between the fixture and both ends of the workpiece.

[0019] Furthermore, insulation treatment should be performed at the installation positions of the pulsed power supply anode, the anode special connector and the processing machine tool in steps (3) and (4). One end of the connector is connected to the pulsed power supply anode and cathode cables through quick connectors, and the other end of the connector is connected to a brush, and the brush contacts both ends of the workpiece.

[0020] Furthermore, the cutting tool described in step (6) can be a milling cutter, a turning tool, or a grinding wheel. Insulation treatment should be performed on the tool and the workpiece (using a non-metal tool, an insulating coating tool, or a tool with an insulating layer between the tool and the machine tool spindle), and an insulating cutting fluid is used during processing.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention is a pulsed discharge cutting method for hard and brittle conductive materials, which can greatly improve the surface quality and machining accuracy of workpieces, greatly improve the service performance and life of workpieces, reduce subsequent machining processes and thus lower production costs; moreover, the equipment and devices used in the machining are simple, with low cost and convenient operation, and it is an effective method for precision machining of hard and brittle conductive difficult-to-machine materials (quenched steel, alloy die steel, conductive ceramics, etc.). Description of the Drawings

[0023] The drawings are used to further understand the present invention, form a part of the invention specification, and are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation to the present invention.

[0024] Figure 1 is the cutting process of the hard and brittle conductive difficult-to-machine material of the present invention;

[0025] Figure 2 is the machining removal process (large-piece crushing removal) on the surface of the hard and brittle conductive difficult-to-machine material of the present invention;

[0026] Figure 3 is the pulsed discharge cutting process (small-piece crushing removal) of the hard and brittle conductive difficult-to-machine material of the present invention;

[0027] Figure 4 is the schematic diagram of the electromagnetic thermal effect (crack tip crack arrest) of the pulsed discharge cutting method for the hard and brittle conductive difficult-to-machine material of the present invention;

[0028] Figure 5 is the working state diagram of the pulsed discharge cutting method for the hard and brittle conductive difficult-to-machine material of the present invention.

[0029] Description of the reference numerals in the drawings: 1. Power supply device; 2. Metal workpiece; 3. Planer; 4. Anode cable; 5. Anode special joint; 6. Cathode cable; 7. Cathode special joint; 8. Planer tool; 9. Fixture; a. Crack tip; b. Crack path Specific Embodiments

[0030] The following will combine the attached Figures 1-5 The present invention will be described in detail. The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] The processing flow includes the following steps:

[0032] (1) Install the high-frequency pulse power supply device:

[0033] First, install the pulse power supply device 1 used in this processing method at a suitable position;

[0034] (2) Install the metal workpiece:

[0035] Use the fixture 9 to position and clamp both ends of the metal workpiece 2 on the workbench of the planer 3;

[0036] (3) Install the special connector for the anode of the pulse power supply for processing:

[0037] Connect the special anode connector 5 with the power anode cable 4, then install the special anode connector 5 on the fixture 3, and finally make the anode connector 5 contact one end of the workpiece 2;

[0038] (4) Install the special connector for the cathode of the pulse power supply:

[0039] Connect the special cathode connector 7 with the power cathode cable 6, then install the special cathode connector 7 on the fixture 3, and finally make the cathode connector 7 contact the other end of the workpiece 2;

[0040] (5) Turn on the pulse power supply:

[0041] Set the processing parameters of the pulse power supply, and turn on the power supply device 1 to perform pulse discharge on the workpiece 2. The output voltage of the pulse power supply can be set to 10 KV and 30 KV, and the output current fluctuates between 0 - 500 A according to the processing conditions;

[0042] (6) Start the cutting machine tool:

[0043] Adjust the planer tool 8, start the planer 3, make the planer tool 8 perform a linear motion, and start the planing process on the metal workpiece 2;

[0044] Among them, when positioning and clamping both ends of the workpiece 2 with the fixture 9 in step (2), insulation treatment should be carried out;

[0045] Among them, in steps (3) and (4), the connection positions of the special anode head 5 and the special cathode head 7 for the pulse power supply processing with the fixture 9 should be insulated, and connected to the pulse power supply anode cable 4 and the cathode cable 6 through quick-connect plugs.

[0046] Working principle: When processing hard and brittle materials, many cracks of a certain depth are generated on the processed surface. Then, under the continuous discharge of the pulsed power supply, a large amount of heat is generated in the a area at the crack tip by the current, that is, the pulsed current concentrates and flows around the crack tip, generating a strong electromagnetic heat effect (the electromagnetic heat effect is an effect of the interaction between the mechanical field, the electromagnetic field, and the temperature field inside and outside the elastic solid), thereby melting the material in the crack tip area, making the crack unable to continue to extend, achieving the stop of the dynamic growth of the crack, making the depth of the surface crack shallower, or making the crack propagation develop along path b, thus realizing the removal of small pieces by fragmentation, and improving the quality of the processed surface.

[0047] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A pulse discharge cutting method based on a hard and brittle conductive material, characterized in that It includes the following steps: (1) Install the pulse power supply device: Install the pulse power supply device at a suitable position near the processing machine tool; (2) Install the workpiece: Use a fixture to install the hard and brittle conductive material workpiece on the machine tool workbench; (3) Install the special joint for the anode of the pulse power supply machining: Connect the special joint for the anode of the pulse power supply machining with the cable for the anode of the pulse power supply machining, then install the special joint for the anode of the pulse power supply machining on the machine tool, and finally connect the joint for the anode of the pulse power supply machining with one end of the workpiece; (4) Install the special joint for the cathode of the pulse power supply machining: Connect the special joint for the cathode of the pulse power supply machining with the cable for the cathode of the pulse power supply machining, then install the special joint for the cathode of the pulse power supply machining on the machine tool, and finally connect the joint for the cathode of the pulse power supply machining with the other end of the workpiece; (5) Mechanical cutting machining: Start the processing machine tool and perform cutting machining with a mechanical machining tool; (6) Turn on the pulse power supply: First set the processing parameters of the pulse power supply, and then turn on the pulse power supply to perform pulse discharge on the workpiece; the output voltage of the pulse power supply is set to 10 KV or 30 KV, and the output current is adjusted between 0 - 500 A according to the processing conditions; Its working principle is: When machining hard and brittle materials, many cracks with a certain depth are generated on the machining surface. Then, under the continuous discharge of the pulse power supply, a large amount of heat is generated by the current at the crack tip region, that is, the pulse current concentrates and flows around the crack tip, generating a strong electromagnetic heat effect, thereby melting the material in the crack tip region, making the crack unable to continue to extend, realizing the stop of the dynamic growth of the crack, the reduction of the surface crack depth, and thus achieving the removal of small pieces by fragmentation, improving the quality of the machining surface.

2. The pulsed discharge cutting method based on a brittle conductive material according to claim 1, characterized in that, When the fixture positions and clamps both ends of the workpiece in step (2), insulation treatment should be carried out at the contact areas between the fixture and both ends of the workpiece.

3. The pulsed discharge cutting method based on a hard and brittle conductive material according to claim 1, characterized in that, For the special joint for the anode of the pulse power supply machining and the special joint for the cathode of the pulse power supply machining in steps (3) and (4), insulation treatment should be carried out at the installation positions on the processing machine tool. And one end of the special joint for the anode of the pulse power supply machining and the special joint for the cathode of the pulse power supply machining are respectively connected to the anode cable and the cathode cable of the pulse power supply through quick connectors, and the other ends of the special joint for the anode of the pulse power supply machining and the special joint for the cathode of the pulse power supply machining are respectively in contact with both ends of the workpiece.

4. A pulsed discharge cutting method based on a hard and brittle conductive material according to claim 1, characterized in that The mechanical cutting tool mentioned in step (5) is a milling cutter, a turning tool or a grinding wheel, and the mechanical cutting tool is insulated from the workpiece, and an insulating cutting fluid is used during machining.

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