CN109158718B

CN109158718B - Method for producing electrode tip, tool electrode, and method for producing tool electrode

Info

Publication number: CN109158718B
Application number: CN201811326528.2A
Authority: CN
Inventors: 顾晓辉; 何星; 赵轩均
Original assignee: Shanghai Jiangnan Roller Co ltd; University of Shanghai for Science and Technology
Current assignee: Shanghai Jiangnan Roller Co ltd; University of Shanghai for Science and Technology
Priority date: 2018-11-08
Filing date: 2018-11-08
Publication date: 2020-07-17
Anticipated expiration: 2038-11-08
Also published as: CN109158718A

Abstract

The invention relates to the technical field of electric spark machining, in particular to a preparation method of an electrode tip, a tool electrode and a preparation method of the tool electrode. The preparation method comprises the following steps: mixing graphene, tungsten carbide, cobalt and absolute ethyl alcohol, and grinding to obtain a mixed ground substance; drying the mixed ground material to obtain a dried ground material; pressing the dried ground material to obtain a molded green body; and sintering the green body to form the electrode tip. The preparation method of the electrode tip provided by the invention is simple and rapid in preparation process, does not need complex equipment, and can greatly reduce the manufacturing cost of the electrode tip. The electrode head obtained is also capable of retaining the properties of the material from which it is made to the greatest extent possible.

Description

Method for producing electrode tip, tool electrode, and method for producing tool electrode

Technical Field

The invention relates to the technical field of electric spark machining, in particular to a preparation method of an electrode tip, a tool electrode and a preparation method of the tool electrode.

Background

The tungsten carbide material has the characteristics of high wear resistance, high hardness, high melting point, corrosion resistance and the like, and is commonly used for strengthening the surface of a workpiece. Cobalt is often used as a binder in the cemented carbide, which ensures the toughness of the cemented carbide to a certain extent. The tungsten carbide-cobalt hard alloy is composed of tungsten carbide and metal cobalt, is one of common hard alloys at present, and is a tool motor material commonly used in the field of electric spark surface strengthening at present.

Graphene, a novel carbonaceous material, has characteristics such as high electrical conductivity, high thermal conductivity, high specific surface area, and increased strength in the case of dealloying and metal compounding. Due to these characteristics of graphene, graphene can be added to a conventional tool electrode to change the strength of the tool electrode. The graphene compounded tool electrode can increase the thermal conductivity, the electric conductivity and the strength of the electrode to a certain extent; the consumption of the electrode can be reduced, the working efficiency is improved, and the processing cost is reduced.

At present, the tool electrode made of tungsten carbide, cobalt and graphene is widely used. However, the existing methods for preparing such tool electrodes are cumbersome, and the resulting electrodes have poor overall performance and low yield.

In addition, most of the conventional tool electrodes are integrated. The integrated tool electrode is usually directly processed from a whole material, and has a simple structure, so that the production efficiency is high, and the quality can be better ensured. However, since the consumption of the tool electrode is large, once a part of the tool electrode is damaged, the whole tool electrode is scrapped, and thus the use cost of the tool electrode is high.

Disclosure of Invention

The invention aims to provide a preparation method of an electrode tip, a tool electrode and a preparation method of the tool electrode, which aim to solve the technical problems of poor performance and high yield of the conventional tool electrode.

Meanwhile, the tool electrode can solve the problem that the use cost of the existing tool electrode is high.

In order to solve the technical problems, the invention provides a preparation method of an electrode tip, which comprises the following steps:

mixing graphene, tungsten carbide, cobalt and absolute ethyl alcohol, and grinding to obtain a mixed ground substance;

drying the mixed ground material to obtain a dried ground material;

pressing the dried ground material to obtain a molded green body;

and sintering the green body to form the electrode tip.

Further, the mass ratio of the tungsten carbide to the cobalt is 4-9, the mass ratio of the graphene to the tungsten carbide to the cobalt is 0.00001-0.02, and the mass ratio of the absolute ethyl alcohol to the graphene, the tungsten carbide and the cobalt is 0.4-0.6.

Further, the graphene, the tungsten carbide, the cobalt and the absolute ethyl alcohol are ground by a ball mill, the grinding speed is 130-160 revolutions per minute, and the grinding time is 8-24 hours.

Further, after drying the mixed ground material, sieving the dried mixed ground material to obtain the dried ground material.

Further, drying the mixed ground material by using a drying oven at the temperature of 50-80 ℃.

Further, drying the mixed ground material in a drying oven for 6-12 hours.

Further, a sieving treatment is performed by using a sieve of at least 325 meshes.

Further, pressing the dried ground object by using a pressing mold, and pressing under the pressure of 150-350 MPa to obtain a molded green body;

wherein the pressing time lasts for 2-5 minutes, and the pressing speed is 2-5 mm per minute.

Further, placing the green body in a tube furnace, and sintering at 1050-1150 ℃ to obtain the electrode tip;

and introducing high-purity nitrogen into the tubular furnace to exhaust air, wherein the flow rate of the high-purity nitrogen is 3-8 ml per minute, and the duration time is 13-17 minutes.

In order to solve the above problems, the present invention also provides a tool electrode including a conductive body to which the electrode tip described above is fixed, the conductive body and the electrode tip being capable of conducting electricity.

The invention also provides a method for preparing the tool, which comprises the steps of adhering the electrode tip to the electric conductor by using conductive silver adhesive, and keeping the temperature for 6-12 hours at 50-80 ℃ by using an oven to form the tool electrode.

The preparation method of the electrode tip provided by the invention is simple and rapid in preparation process, does not need complex equipment, and can greatly reduce the manufacturing cost of the electrode tip. The electrode head obtained is also capable of retaining the properties of the material from which it is made to the greatest extent possible. In addition, the combined tool electrode provided by the invention can replace the electrode tip for many times, thereby greatly reducing the use cost of the tool electrode and improving the utilization rate of resources.

Drawings

Fig. 1 is a flowchart of a method of manufacturing an electrode head according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of a modular tool electrode according to one embodiment of the present invention;

fig. 3 is a schematic view of a discoid electrode head provided in an embodiment of the present invention.

Detailed Description

According to the foregoing, in the present stage, some tool electrodes used for electric discharge machining can improve the machining performance of the tool electrode by using tungsten carbide and cobalt materials; still other tool electrodes have further improved the thermal and electrical conductivity and strength of the tool electrode itself by the addition of graphene materials. However, the existing methods for preparing such tool electrodes are cumbersome, and the resulting electrodes have poor overall performance and low yield. To this end, the invention provides a method for producing a tool electrode for electrical discharge machining.

In addition, because the existing integrated tool electrode has high use cost, especially the integrated tool electrode made of expensive materials (such as tungsten carbide, copper-tungsten alloy and the like) is adopted. Therefore, the invention provides a combined tool electrode, which is characterized in that two electric conductors with the same or different properties are combined to form one tool electrode, and one of the electric conductors is used as an electrode tip (used for discharging a machined workpiece and can be made of a material with higher price and better performance) to be applied to electric spark machining, so that the use cost of the tool electrode is reduced. Since the preparation method can be used for preparing the tool electrode for electric discharge machining, the preparation method can also be used for preparing the electrode tip in the combined tool electrode provided by the invention.

Furthermore, the invention also provides a method for preparing the tool electrode, so as to fix the electrode tip and the electric conductor to form a finished tool electrode.

The method for producing the electrode head, the tool electrode and the method for producing the tool electrode according to the invention are described in more detail below with reference to the drawings and the specific examples. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Example 1

The present embodiment provides a method for manufacturing an electrode tip, and as shown in fig. 1, fig. 1 is a flowchart of the method for manufacturing an electrode tip provided in the present embodiment.

The preparation method of the electrode head provided by the embodiment comprises the following steps:

s1: mixing graphene, tungsten carbide, cobalt and absolute ethyl alcohol, and grinding to obtain a mixed ground substance;

s2: drying the mixed ground material to obtain a dried ground material;

s3: pressing the dried ground material to obtain a molded green body;

s4: and sintering the green body to form the electrode tip.

Specifically, in S1, the mass ratio of the tungsten carbide to the cobalt is 4-9, the mass ratio of the graphene to the tungsten carbide to the cobalt is 0.00001-0.02, and the mass ratio of the absolute ethyl alcohol to the graphene, the tungsten carbide and the cobalt is 0.4-0.6. For example: measuring 9g of tungsten carbide powder (the tungsten carbide powder with the particle size of 1 micron can be selected), 1g of cobalt powder (the cobalt powder with the particle size of 1-2 microns can be selected), 0.101g of graphene material and 5g of absolute ethyl alcohol by using a balance. In the case of grinding, the above-mentioned materials may be put into a ball mill for grinding in order to improve the grinding efficiency.

Further, when the mixture of tungsten carbide, cobalt, graphene and absolute ethyl alcohol is ground by a ball mill, the grinding speed of the ball mill may be set to 130 to 160 revolutions per minute and the grinding may be continued for 8 to 24 hours, for example, the rotation speed of the ball mill may be maintained at 150 revolutions per minute and the grinding may be continued for 24 hours, so that the above materials may be sufficiently ground to form the mixed ground product.

Specifically, in S2, the mixed ground product is dried and then sieved to obtain a dried ground product. The sieving can be carried out by utilizing a sieve with at least 325 meshes. For example, a 400-mesh screen can be selected according to actual requirements for sieving to remove larger particles in the mixed ground material, so as to obtain the dried ground material.

Also, the mixed grind needs to be dried before being screened to avoid the grinding mixture sticking and forming lumps. When the drying treatment is performed, a drying oven can be used as drying equipment, and the temperature of the drying oven is set to be 50-80 ℃ to perform the drying treatment on the mixed ground material. Of course, in order to dry the ground object more thoroughly, the drying time may be set to 6 to 12 hours. For example, the temperature is set to 80 ℃ and the drying time is set to 12 hours to ensure more thorough drying of the milled mixture.

Specifically, in S3, the dried ground substance may be pressed by a pressing mold, and in order to make the pressed green body more dense, the dried ground substance may be pressed at a pressure of 150MPa to 350MPa to obtain the shaped green body; and the pressing time lasts for 2-5 minutes, and the pressing speed is 2-5 mm per minute. When the electrode tip is pressed, the electrode tip can be made into a smaller volume to save raw materials and cost, for example, 3g of the dried ground material can be put into a pressing grinding tool which realizes a set or specified pressing shape, then the pressing grinding tool is put into a 100KN pressing machine and pressed for 5 minutes according to the pressure of 250MPa, and then the pressed green body is taken out of the pressing grinding tool.

Placing the green body in a tube furnace, and sintering at 1050-1150 ℃ to obtain the electrode tip; in addition, in order to avoid oxidation of the green body, high-purity nitrogen is introduced into the tube furnace to exhaust air in the tube furnace before sintering, the flow rate of the high-purity nitrogen is 3-8 milliliters per minute, and the time for introducing the high-purity nitrogen can be controlled to be 13-17 minutes. For example, according to the green compact pressed by taking 3g of the dried ground material, the temperature may be set to 1100 ℃, the temperature rise time may be set to 10 hours, the temperature holding time may be set to 1 hour, and the flow rate of the introduced high-purity nitrogen may be set to 3 ml per minute, and the duration of the introduction of the high-purity nitrogen may be set to 15 minutes. Finally the desired electrode head is obtained.

In conclusion, the preparation method of the electrode tip provided by the embodiment is simple and rapid in preparation process, complex equipment is not needed, and the manufacturing cost of the electrode tip can be greatly reduced. The electrode head obtained is also capable of retaining the properties of the material from which it is made to the greatest extent possible.

Example 2

The present embodiment provides a tool electrode, as shown in fig. 2 and fig. 3, fig. 2 is a schematic structural diagram of the tool electrode provided in the present embodiment; fig. 3 is a schematic view of the electrode head provided in the present embodiment. The tool electrode comprises a conductor 1, and is typically copper and cylindrical in shape, so the present embodiment is exemplified by a copper cylindrical conductor 1. The electrode tip 2 obtained by the production method in example 1 is fixed to the conductive body 1, and current can be passed between the conductive body 1 and the electrode tip 2.

Since the main purpose of the tool electrode provided in this embodiment is to reduce the use cost of the tool electrode, the volume of the electrode tip 2 can be made sufficiently small, and the electrode tip 2 having a cylindrical shape is also made into a cylindrical shape to fit the conductor 1, and then the cylindrical electrode tip 2 is fixed to one end of the conductor 1, thereby obtaining a combined tool electrode. If the electrode tip 2 is damaged during use, the whole tool electrode can be prevented from being scrapped by replacing the electrode tip 2.

Of course, when the electrode tip 2 is fixed on the electric conductor 1, the electrode tip 2 may be adhered to the electric conductor 1 by using conductive silver paste, and the heat is preserved for 6 to 12 hours at 50 to 80 ℃ by using an oven to form the tool electrode. For example, the electrode tip 2 and the conductor 1 bonded together by the conductive silver paste are placed in an oven at 80 ℃ and kept warm for 12 hours, and then taken out.

Based on the above, the combined tool electrode provided by the embodiment can replace the electrode tip 2 for multiple times, thereby greatly reducing the use cost of the tool electrode and improving the utilization rate of resources.

Claims

1. A method for producing an electrode head, characterized in that it comprises the following steps:

drying the mixed ground material to obtain a dried ground material;

pressing the dried ground material to obtain a molded green body;

sintering the green compact to form the electrode tip;

the tungsten carbide and the cobalt form a first group of substances, and the mass ratio of the graphene to the first group of substances is 0.00001-0.02.

2. The method according to claim 1, wherein the mass ratio of the tungsten carbide to the cobalt is 4 to 9, the graphene, the tungsten carbide and the cobalt constitute a second group of substances, and the mass ratio of the absolute ethyl alcohol to the second group of substances is 0.4 to 0.6.

3. The method according to claim 1, wherein the graphene, the tungsten carbide, the cobalt and the absolute ethyl alcohol are milled by a ball mill at a milling speed of 130 to 160 revolutions per minute for 8 to 24 hours.

4. The method of claim 1, wherein the mixed grind is dried and then screened to obtain a dried grind.

5. The method according to claim 4, wherein the mixed ground product is dried in a drying oven at a temperature of 50 to 80 ℃.

6. The method of claim 5, wherein the mixed grind is dried in a drying oven for 6 to 12 hours.

7. A method as claimed in claim 4, wherein the screening treatment is carried out using a screen of at least 325 mesh.

8. The method of claim 1, wherein the dried abrasive article is pressed using a pressing die and pressed at a pressure of 150MPa to 350MPa to obtain the shaped green body;

9. The method of claim 1, wherein the green body is placed in a tube furnace and sintered at a temperature of 1050 to 1150 ℃ to obtain the electrode head;

10. A tool electrode for electric discharge machining, comprising an electric conductor to which an electrode tip according to any one of claims 1 to 9 is fixed, the electric conductor being capable of conducting electricity with the electrode tip.

11. A method for preparing a tool electrode, characterized in that the electrode tip as claimed in claim 10 is bonded to the conductor by means of a conductive silver paste, and is kept warm for 6 to 12 hours at 50 to 80 ℃ by means of an oven to form the tool electrode.