A new alloy tool electrode for electric discharge machining and its preparation method

Abstract

The present invention discloses a novel alloy tool electrode for electric discharge machining and a preparation method thereof. The novel alloy tool electrode is composed of the following components, in parts by weight: 20-150 parts of novel alloy powder, 1-100 parts of copper or copper alloy powder, and 5-30 parts of abrasive. The novel alloy powder is composed of four or more elements selected from the group consisting of W, Nb, Mo, Ta, Cr, V, Ti, and Hf. The abrasive is one of uncoated diamond, W-coated diamond, and Ti-coated diamond, and has a particle size of 5-600 μm. The electrode of the present invention has extremely high electro-corrosion resistance, solving the problem of severe electro-corrosion loss of electrodes and tool electrodes in electric discharge machining. The tool electrode also has excellent high-temperature mechanical properties, wear resistance, and high-temperature stability, preventing rapid wear of the tool electrode binder and shedding of the abrasive under high-temperature discharge conditions. The service life of the electrode and tool electrode, machining efficiency, machining surface quality, and machining accuracy are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical machining, and in particular relates to a novel alloy tool electrode for electrical discharge machining and a preparation method thereof. Background Art

[0002] Currently, both electrodes and tool electrodes suffer from the unavoidable problem of electrolytic erosion caused by the discharge effect. The metal raw materials currently used to manufacture these electrodes and tool electrodes lack sufficient electrolytic erosion resistance, resulting in significant electrode and tool electrode wear and short lifespan during machining, impacting both machining efficiency and quality. Discharge machining (EDM) is an important method in materials processing. High discharge temperatures are unavoidable during EDM. Based on the machining principles, EDM can be categorized into EDM (Electrodischarge Machining), EDM (Electrochemical Discharge Machining), and hybrid methods based on both, such as EDM (Electrodischarge-Assisted Grinding) and EDM (Electrochemical Discharge-Assisted Grinding). These methods all involve vaporizing and eroding the workpiece material through the discharge effect of either the electrode (composed solely of metal) or the tool electrode (composed of abrasive and a metal binder). However, due to the discharge effect, existing research indicates that these machining methods all suffer from the problem of electrolytic erosion caused by the discharge effect, a problem that is unavoidable from a fundamental processing perspective. Furthermore, for EDM and ECD grinding, the tool electrode (composed of abrasive and metal binder) faces the challenge of not only electrolytic wear of the binder due to erosion, but also a reduction in the mechanical properties and wear resistance of the binder due to high discharge temperatures (i.e., softening of the binder at high temperatures). This causes the binder to be rapidly worn away by the hard phase during machining, and the binder's grip on the abrasive is also reduced, leading to premature and excessive abrasive shedding, significantly shortening the tool electrode's service life. Furthermore, issues such as low machining efficiency, poor surface quality, and low machining precision caused by electrode and tool electrode wear are also not to be ignored. Summary of the Invention

[0003] In response to the above-mentioned problems, the present invention proposes a new alloy tool electrode for electric discharge machining and a preparation method thereof, which is used to prepare electrodes and tool electrodes. By selecting metal raw material powders with high melting points and high mechanical properties, a new alloy with higher electro-corrosion resistance, high-temperature mechanical properties and wear resistance, high-temperature stability and high-temperature creep resistance is designed. On the one hand, the high electro-corrosion resistance of the new alloy can reduce the electro-corrosion loss of electrodes and tool electrodes. On the other hand, the high-temperature mechanical properties, wear resistance, and high-temperature stability of the new alloy can avoid rapid wear of tool electrode binders and abrasive shedding. Therefore, the new alloy can improve the service life and processing performance of electrodes and tool electrodes. In addition, a certain proportion of copper or copper alloy can be added to the new alloy powder to form a new alloy-reinforced copper-based composite material, which can simultaneously ensure the conductivity, electro-corrosion resistance, high-temperature mechanical properties and wear resistance of electrodes and tool electrodes.

[0004] One of the objects of the present invention is to provide a novel alloy tool electrode for electric discharge machining, wherein the novel alloy tool electrode is composed of the following components in parts by weight: 20-150 parts of novel alloy powder, 1-100 parts of copper or copper alloy powder, and 5-30 parts of abrasive;

[0005] The novel alloy powder is composed of four or more elements selected from the group consisting of W, Nb, Mo, Ta, Cr, V, Ti, and Hf, wherein the elements constituting the novel alloy powder are weighed in a molar ratio of 1:1, and the particle size of the novel alloy powder is 5-150 μm;

[0006] The abrasive is one of uncoated diamond, W-coated diamond, and Ti-coated diamond, and has a particle size of 5-600 μm;

[0007] Furthermore, the novel alloy tool electrode is composed of the following components in parts by weight: 30-120 parts of novel alloy powder, 5-80 parts of copper or copper alloy powder, and 10-25 parts of abrasive;

[0008] The novel alloy powder is composed of four or more elements selected from W, Nb, Mo, Ta, Cr, V, Ti, and Hf, wherein the elements constituting the novel alloy powder are weighed in a molar ratio of 1:1, and the particle size is 5-120 μm;

[0009] The abrasive is one of uncoated diamond, W-coated diamond and Ti-coated diamond, and has a particle size of 5-500 μm.

[0010] Furthermore, the novel alloy tool electrode is composed of the following components in parts by weight: 30-100 parts of novel alloy powder, 5-70 parts of copper or copper alloy powder, and 10-20 parts of abrasive;

[0011] The novel alloy powder is composed of four or more elements selected from the group consisting of W, Nb, Mo, Ta, Cr, V, Ti, and Hf, wherein the elements constituting the novel alloy powder are weighed in a molar ratio of 1:1, and the particle size is 5-100 μm;

[0012] The abrasive is one of uncoated diamond, W-coated diamond and Ti-coated diamond, and has a particle size of 5-400 μm.

[0013] A second object of the present invention is to provide a method for preparing the novel alloy tool electrode for electric discharge machining, the method comprising the following steps:

[0014] (1) Weigh the new alloy powder according to the required weight, place the new alloy powder in an argon / nitrogen atmosphere and ball mill for 5-50 hours, with a ball-to-material ratio of (10-30):1 and a rotation speed of 200-500 rpm;

[0015] (2) Weighing copper or copper alloy powder and abrasive according to the required weight proportions, mixing them with the new alloy powder obtained in step (1) and ball milling, wherein the ball mill speed is 100-250 r / min, the ball milling time is 1-10 h, the protective atmosphere is argon or nitrogen, and the total volume of the raw materials does not exceed 2 / 3 of the volume of the ball mill;

[0016] (3) placing the mixed material obtained in step (3) into a cold pressing mold for cold pressing to obtain a green body, wherein the green body has a green body density of 40 to 60% and a cold pressing pressure of 100 to 250 MPa;

[0017] (4) The green body obtained above is hot-pressed and sintered, heated to 750-1450°C at a heating rate of 40-100°C / min, and kept warm for 5-40 min. The sintering pressure during the heating stage is 20-100 MPa, and the protective atmosphere is argon or nitrogen. The green body is cooled to room temperature in the furnace to obtain the new alloy tool electrode.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention proposes a novel alloy designed to be used as an electrode material and tool electrode binder material for electrical discharge machining. Through a special composition design, the alloy has extremely high resistance to electro-corrosion, thereby solving the serious problem of electro-corrosion loss of electrodes and tool electrodes in electrical discharge machining. At the same time, the tool electrode also has excellent high-temperature mechanical properties, wear resistance, and high-temperature stability, which can avoid rapid wear of the tool electrode binder and abrasive shedding under high-temperature discharge conditions. The alloy can also improve the service life of electrodes and tool electrodes, machining efficiency, machining surface quality, and machining accuracy.

[0020] (2) Compared with the currently commonly used electrode materials, the new alloy designed in the present invention has higher electro-corrosion resistance, can better cope with the environment and conditions during discharge machining, avoids serious electro-corrosion loss, thereby extending the service life of the electrode and tool electrode and improving the machining performance.

[0021] (3) Compared with the commonly used tool electrode binder materials, the new alloy designed in the present invention has more excellent high-temperature mechanical properties, wear resistance, and high-temperature stability. It can avoid rapid wear of the tool electrode binder and abrasive shedding, extend the service life of the tool electrode, and improve the processing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a diagram showing the results of the electro-corrosion experiment of the electrode material of Example 1 of the present invention.

[0023] Figure 2This is a diagram of tool electrode wear and average material removal rate in Example 1 of the present invention.

[0024] Figure 3 This is a diagram showing the results of the electro-corrosion experiment of the electrode material of Example 2 of the present invention.

[0025] Figure 4 This is a diagram of tool electrode wear and average material removal rate in Example 2 of the present invention. DETAILED DESCRIPTION

[0026] Below with reference to the embodiment Figure 1-4 The present invention is described in further detail.

[0027] Example 1

[0028] A method for preparing a novel alloy tool electrode for electric discharge machining, comprising the following steps:

[0029] (1) Weigh W, Nb, Mo, Ta, and Cr powders in a molar ratio of 1:1:1:1:1, with a particle size of 20 μm, and alloy them in a ball mill with a ball-to-material ratio of 20:1 for 50 h;

[0030] (2) 80 parts of the new alloy powder prepared in step (1), 8 parts of copper powder and 12 parts of Ti-coated diamond abrasive, all with a particle size of 200 μm, were placed in a planetary ball mill and mixed thoroughly. The ball mill speed was 150 rpm and the ball milling time was 6 h.

[0031] (3) placing the mixed powder obtained in step (2) into a mold for cold pressing to obtain a green body with a green body density of 65% at a cold pressing pressure of 240 MPa;

[0032] (4) The green body obtained in step (3) is subjected to hot pressing sintering, and the green body is heated to 1400°C at a heating rate of 75°C / min, kept at this temperature for 5 minutes, and cooled in the furnace to obtain a sintered block containing abrasive.

[0033] After sintering, no obvious pores and cracks were generated in the binder, and the density was high. At the same time, the hardness and compressive strength reached 841HV and 3500 MPa respectively. The binder has a good embedding effect on diamond. Single pulse electro-etching experiments found that under the same conditions, the maximum depth and maximum width of the electro-etching pit on the new alloy substrate were significantly reduced compared with the control group (pure copper substrate). Figure 1 The tool electrodes with a certain shape and size were used in electrochemical discharge assisted grinding and drilling of aluminum-based silicon carbide composite materials. The results showed that the loss of the new alloy diamond tool electrode was significantly reduced compared with the pure Cu bond diamond tool electrode, while the average material removal rate was greatly improved. Figure 2In summary, the obtained new alloy diamond tool electrode has high wear resistance, electrical corrosion resistance and processing efficiency.

[0034] Example 2

[0035] A method for preparing a novel alloy tool electrode for electric discharge machining, comprising the following steps:

[0036] (1) Take W, Nb, Mo, Ta, and V powders in a molar ratio of 1:1:1:1:1, with a particle size of 20 μm; put them into a ball mill for alloying with a ball-to-material ratio of 20:1 for 50 hours;

[0037] (2) 70 parts of the new alloy powder obtained in step (1), 18 parts of copper powder, and 12 parts of Ti-coated diamond abrasive, wherein the particle size of the copper powder is 20 μm, and the particle size of the Ti-coated diamond abrasive is 200 μm, are placed in a planetary ball mill and mixed thoroughly. The ball mill speed is 200 rpm and the ball milling time is 8 h.

[0038] (3) The mixed powder obtained in step (3) is placed in a mold for cold pressing to obtain a green body with a green body density of 55% at a cold pressing pressure of 200 MPa; the green body obtained above is hot pressed and sintered by heating the green body to 1150°C at a heating rate of 100°C / min, keeping the temperature for 10 minutes, and cooling in the furnace to obtain a sintered block containing abrasive.

[0039] After sintering, no obvious pores and cracks were generated in the binder, and the density was high. At the same time, the hardness and compressive strength reached 700HV and 2480MPa respectively. The binder has a good embedding effect on diamond. Single pulse electro-etching experiments found that under the same conditions, the maximum depth and maximum width of the electro-etching pit on the new alloy substrate were significantly reduced compared with the control group (pure copper substrate). Figure 3 The tool electrodes with a certain shape and size were used in electrochemical discharge assisted grinding and drilling of aluminum-based silicon carbide composite materials. The results showed that the loss of the new alloy diamond tool electrode was significantly reduced compared with the pure Cu bond diamond tool electrode, while the average material removal rate was greatly improved. Figure 4 In summary, the obtained new alloy diamond tool electrode has high wear resistance, electrical corrosion resistance and processing efficiency.

[0040] Comparative Example 1

[0041] The only difference between Comparative Example 1 and Example 1 is that the same weight fraction of Cu powder is used instead of the new alloy powder;

[0042] Comparative Example 2

[0043] The only difference between Comparative Example 1 and Example 2 is that the same weight fraction of Cu powder is used instead of the abrasive;

[0044] Comparative Example 3

[0045] The only difference between Comparative Example 3 and Example 1 is that the particle size of the new alloy powder is 180 μm;

[0046] Comparative Example 4

[0047] The only difference between Comparative Example 4 and Example 1 is that the particle size of the abrasive is 650 μm;

[0048] Comparative Example 5

[0049] The only difference between Comparative Example 5 and Example 2 is that the particle size of the new alloy powder is 180 μm;

[0050] Comparative Example 6

[0051] The only difference between Comparative Example 6 and Example 1 is that the particle size of the abrasive is 650 μm;

[0052] Comparative Example 7

[0053] The only difference between Comparative Example 7 and Example 1 is that the same weight proportions of Mo, Ta, and Cr powders are used instead of W, Nb, Mo, Ta, and Cr powders;

[0054] Comparative Example 8

[0055] The only difference between Comparative Example 8 and Example 1 is that W, Nb, and Mo powders in the same weight proportions are used instead of W, Nb, Mo, Ta, and Cr powders;

[0056] Comparative Example 9

[0057] The only difference between Comparative Example 9 and Example 2 is that W, Nb, and Mo powders in the same weight proportions are used instead of W, Nb, Mo, Ta, and V powders;

[0058] Comparative Example 10

[0059] The only difference between Comparative Example 10 and Example 2 is that the same weight proportions of Mo, Ta, and V powders are used instead of W, Nb, Mo, Ta, and V powders;

[0060] The above test data are recorded in Table 1.

[0061] Table 1

[0062]

[0063] As can be seen from Table 1, the particle size and composition of the new alloy powder and the abrasive particle size also have a certain influence on the electro-erosion results, electrode loss and material removal rate. Among them, the change of the composition of the new alloy powder has a relatively large impact on these effects. However, compared with the electrodes in Examples 1-2, the tool electrode of the present invention has very good performance.

[0064] The above content is the best specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily conceived by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A new alloy tool electrode for electric discharge machining, characterized in that: The novel alloy tool electrode is composed of the following components in parts by weight: 20-150 parts of novel alloy powder, 1-100 parts of copper or copper alloy powder, and 5-30 parts of abrasive; The novel alloy powder is composed of four or more elements selected from the group consisting of W, Nb, Mo, Ta, Cr, V, Ti, and Hf, wherein the elements constituting the novel alloy powder are weighed in a molar ratio of 1:1, and the particle size of the novel alloy powder is 5-150 μm; The abrasive is one of uncoated diamond, W-coated diamond and Ti-coated diamond, and has a particle size of 5-600 μm.

2. A new alloy tool electrode for electric discharge machining according to claim 1, characterized in that: The novel alloy tool electrode is composed of the following components in parts by weight: 30-120 parts of novel alloy powder, 5-80 parts of copper or copper alloy powder, and 10-25 parts of abrasive; The novel alloy powder is composed of four or more elements selected from the group consisting of W, Nb, Mo, Ta, Cr, V, Ti, and Hf, wherein the elements constituting the novel alloy powder are weighed in a molar ratio of 1:1, and the particle size of the novel alloy powder is 5-120 μm; The abrasive is one of uncoated diamond, W-coated diamond and Ti-coated diamond, and has a particle size of 5-500 μm.

3. A new alloy tool electrode for electric discharge machining according to claim 2, characterized in that: The novel alloy tool electrode is composed of the following components in parts by weight: 30-100 parts of novel alloy powder, 5-70 parts of copper or copper alloy powder, and 10-20 parts of abrasive; The novel alloy powder is composed of four or more elements selected from the group consisting of W, Nb, Mo, Ta, Cr, V, Ti, and Hf, wherein the elements constituting the novel alloy powder are weighed in a molar ratio of 1:1, and the particle size of the novel alloy powder is 5-100 μm; The abrasive is one of uncoated diamond, W-coated diamond and Ti-coated diamond, and has a particle size of 5-400 μm.

4. A method for preparing a new alloy tool electrode for electric discharge machining according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Weigh the new alloy powder according to the required weight, place the new alloy powder in an argon / nitrogen atmosphere and ball mill for 5-50 hours, with a ball-to-powder ratio of (10-30):1 and a rotation speed of 200-500 rpm; (2) Weighing copper or copper alloy powder and abrasive according to the required weight proportions, mixing them with the new alloy powder obtained in step (1) and ball milling, wherein the ball mill speed is 100-250 r / min, the ball milling time is 1-10 h, the protective atmosphere is argon or nitrogen, and the total volume of the raw materials does not exceed 2 / 3 of the volume of the ball mill; (3) placing the mixed material obtained in step (3) into a cold pressing mold for cold pressing to obtain a green body, wherein the green body has a green body density of 40 to 60% and a cold pressing pressure of 100 to 250 MPa; (4) The green body obtained above is hot-pressed and sintered, heated to 750-1450°C at a heating rate of 40-100°C / min, and kept warm for 5-40 min. The sintering pressure during the heating stage is 20-100 MPa, and the protective atmosphere is argon or nitrogen. The green body is cooled to room temperature in the furnace to obtain the new alloy tool electrode.

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