JP2000301278A - Die for cold forging excellent in wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the sufficient wear resistance to keep up with a forging of a difficult-to-working material without forming a film on the surface of the forming part of a die, consequently, without generating the detachment of the film. SOLUTION: This die applies the coating with an electric discharging machining by using a titanium as an electrode on the surface of the forming part 3 of the die D for cold-forging composed of a cemented carbide to form the hard film on the surface of the forming part 3, and also, forms a ceramic hardened layer 4 with a titanium permeation having about 3-5 micron in the inner part of the cemented carbide material in the forming part 3. Thereafter, the coating hard film 5 on the surface of the forming part is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold forging die excellent in wear resistance and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a die for cold forging generally has a high hardness coating film of about 3 to 5 microns formed by a PVD or CDV coating process on a die surface to enhance abrasion resistance. When the treatment is performed on the inner diameter side molded portion, it is difficult to form a coating film, and even if a film is formed, it is difficult to secure a sufficient film thickness. In particular, since the coating film is formed on the surface of the molded part, peeling is likely to occur under conditions of high pressure and high temperature, and it is not possible to exhibit sufficient wear resistance commensurate with the film hardness. Was.

[0003] When a horizontal split die is used,
It is necessary to bake and fix the dice on the die body,
And 300-500 ° C by PVD process, 1 by CVD process
Since processing at a high temperature of 100 ° C. causes a thermal change in the die body and not only adversely affects the life of the die, the coating equipment becomes large-scale due to the use of a vacuum furnace and the like. The coating cost was high, the mold was expensive, and there were practical difficulties.

[0004]

[Problems to be solved by the invention]

However, in recent years, in the field of cold forging, forging of difficult-to-machine materials such as high-carbon materials is rapidly increasing, and the demand for dies capable of handling such difficult-to-machine materials is increasing.

[0006] The present invention addresses the above-mentioned situation and finds a new coating method for a die, thereby forming no coating on the surface of a die forming part, and thus, forging a difficult-to-process material without peeling off the coating. It is an object of the present invention to provide a cold forging die having sufficient abrasion resistance capable of coping with the following.

[0007]

One of the features of the present invention that meets the above-mentioned object is that, on the surface of a forming part of a cold forging die made of a cemented carbide, an electric discharge machining process using titanium as an electrode is performed. It is a configuration in which a ceramic hardened layer is formed by infiltration of titanium having a depth of about 3 to 5 microns inside the cemented carbide material of the forming part, and the other one is a method for manufacturing the cold forging die, The electric discharge machining process is performed on the forming part of the cold forging die made of cemented carbide using titanium as an electrode.
At the same time as forming a ceramic hard coating on the surface of the molded part by using the high voltage at the time of electric discharge machining, titanium is infiltrated into the inside of the molded member to form a ceramic hardened layer with a depth of about 3 to 5 microns in the part. Then, the surface of the molded portion is mirror-finished to remove a hard coating on the surface and smoothen the surface.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the dice and the manufacturing method of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view of a die for cold forging according to the present invention before a film is removed, and FIG. 2 shows an embodiment of an electric discharge machining process. In FIG. 1, reference numeral 1 denotes an upper die, 2 denotes a lower die, and 3 denotes a formed part. A die D according to the illustrated embodiment of the present invention has a horizontal two-part structure made of cemented carbide,
A configuration is such that a molding material is charged into the molding section 3 and pressed by a punch (not shown) to form a product.

Conventionally, such a die has been subjected to a coating on the surface of the formed part of the die by PVD or CDV processing and a mirror finish by lapping. In the present invention, however, an ED cord power supply is mounted. Using an electric discharge machine as shown in FIG. 2, using titanium for the electrode, utilizing the high voltage at the time of electric discharge machining, infiltrating titanium into the material inner surface portion made of cemented carbide in the die forming portion, The high hardness layer 4 is formed at a depth of about 3 to 5 microns on the inner surface layer of the material.

Here, the coating using the above-mentioned electric discharge machine utilizes the electric discharge phenomenon in the working fluid, and as shown in FIG. 2, the forming part 3 is formed in a working fluid, for example, a dielectric hydrocarbon oil. A Ti-based electrode 7 is arranged to face the coating surface of the upper die 1 or the like to be
To form a discharge circuit to generate sparks due to intermittent discharge and process the Ti-based electrodes 7 by discharge.
Is consumed and released between the poles, and this reacts with carbon, which is a hydrocarbon oil constituent element decomposed by the heat of discharge, to form Ti.
C and a hard ceramic coating 5 on the inner diameter surface of the molded part
To form

When the hard ceramic film 5 is formed on the surface of the molded part 3, titanium is taken into the material surface layer of the molded part 3 to a depth of about 5 to 7 microns inside the material by the heat of discharge. A hardened layer 4 having a hardness of 2000 to 3000 HV or more is formed.

The ceramic hard coating 5 formed on the surface of the molded part 3 by the above-mentioned electric discharge machining has discharge traces 6 as shown in FIG. 2 and causes a large friction when used as a cold forging die. And the hard coating 5 on the surface is brittle and easily peeled off, so that it is removed at the same time as the mirror finish by lapping and finally has a hardened layer 4 inside the material of the molded part 3. The die according to the present invention is completed.

That is, the die thus obtained is obtained by removing the hard coating 5 of the molded part 3 in FIG. 1 and the hard coating 5 is removed, so that no peeling occurs and the capability of the internal hardened layer 4 is sufficiently high. It is possible to significantly improve the wear resistance of the mold.

[0015]

As described above, according to the present invention, the surface of the forming part of the cold forging die made of a cemented carbide is subjected to electric discharge machining as a titanium electrode, and the inside of the cemented carbide material of the forming part is about 3 to 5 microns. This is a cold forging die with a ceramic hardened layer formed by penetration of titanium at a depth of .The coating does not form on the surface of the formed part as in the past, so that the coating does not peel off and the inside of the molded member has high hardness. A sufficiently high hardness layer is secured by forming a hardened layer of, which significantly increases wear resistance, and has a life that is 1.3 times or more longer than the currently used coated mold. Can be secured.

In addition, the manufacturing method of the present invention uses only an electric discharge machine such as an electric discharge machine equipped with an ED coat power source and a general-purpose NC machining machine as equipment, and performs coating using an electrode which can be coated with a small equipment. Because of the processing, the coating can be applied to any place, which has a remarkable effect that an economical die can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of a die according to the present invention before a hard coating is removed.

FIG. 2 is an explanatory view of a machining state of an electric discharge machine used for manufacturing the present invention.

[Explanation of symbols]

 D Dice 1 Upper die 2 Lower die 3 Molding part 4 Hardened layer 5 Hard coating 7 Ti-based electrode

Claims (2)

[Claims] 1. A surface of a forming part of a cold forging die made of a cemented carbide is subjected to electric discharge machining using titanium as an electrode, and a depth of about 3 to 5 microns is formed inside the cemented carbide material of the forming part. Die for cold forging with excellent wear resistance characterized by forming a ceramic hardened layer by titanium penetration. 2. A forming part of a cold forging die made of a cemented carbide is subjected to electric discharge machining using titanium as an electrode, and a ceramic hard coating is formed on the surface of the forming part using a high voltage at the time of electric discharge machining. At the same time, titanium is penetrated into the inside of the molded member to form a ceramic hardened layer with a depth of about 3 to 5 microns in the part, and then the surface of the molded part is mirror-finished to remove the hard coating on the surface and smoothen it. A method for producing a cold forging die excellent in wear resistance, characterized in that: