JPH07116587B2 - Forging die and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a forging die and its manufacturing method.

[Conventional technology]

In general, forging is a process in which an object to be processed is repeatedly subjected to impact to form it into a desired shape, and a severe pressure state is imposed on a die used. In particular,
Cold forging is performed at room temperature or a temperature close to room temperature without actively heating the work piece, so the deformation resistance of the work piece is high and extremely severe conditions are imposed on the cold forging die. It will be. In other words, the mold used is required to be made of a material having a high dynamic strength and a high load per unit area, which is accompanied by an impact.

Therefore, as forging dies, especially cold forging dies, the heat treatment technology is mixed with the improvement, and various alloy steels have been developed so far, or the application of cemented carbide, which is a product of powder metallurgy technology, etc. Improvements have been made in terms of materials.

On the other hand, in order to develop excellent tool materials with higher productivity, techniques for coating the surface of materials with various intermetallic compounds have been developed. For example, by coating the tool surface with an intermetallic compound such as TiN by a so-called PVD method such as a vacuum deposition method, an ion sputtering method, an ion plating method, or a CVD method which should be called a vapor phase plating method, the tool life can be improved. It is an attempt to extend it.

[Problems to be Solved by the Invention]

However, the PVD coating layer has poor adhesion on the surface of the material, and cannot be endured even when applied to the surface of a forging die under severe dynamic load.

When the latter CVD method is used, the adhesion of the coating layer on the material surface is somewhat improved as compared with the PVD method, but in this case as well, a coating layer that is clearly identified is formed on the material surface. There was a problem that the coating layer was peeled off under severe dynamic pressure conditions.

Furthermore, in the CVD method, it is necessary to heat the mold to a high temperature (for example, when coating TiN or TiC, it is heated to about 1000 ° C.), so the quenching process of the mold is tempered and the mold substrate itself This causes inferior strength, and the dimensional accuracy is distorted due to thermal strain, which is inconvenient as a mold. In order to eliminate this inconvenience, it was necessary to impose severe restrictions on the material, which was not practical.

In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a forging die excellent in productivity, which has a high strength capable of withstanding severe forging, and has a long tool life, and a manufacturing method thereof. .

[Means for Solving the Problems]

In order to achieve the above object, a characteristic configuration of a forging die according to the present invention is that at least a surface in contact with a workpiece is implanted with an ion of one element selected from the following element group (A): By vacuum deposition of titanium and these ions,
Boride-based, or carbide-based, nitride-based, or oxide-based intermetallic compound amorphous in which the vapor deposition element and the base metal of the workpiece made of tool steel or cemented carbide are mixed Element group (A): boron, carbon, nitrogen, oxygen, which is provided with a modified surface treatment layer made of a porous material.

Furthermore, the characteristic configuration of the method for producing a forging die according to the present invention is that at least the surface in contact with the workpiece is implanted with ions of one element selected from the following element group and vacuum deposition of titanium. By doing at the same time, with these ions,
A vapor-deposition element and a base metal of a workpiece made of tool steel or cemented carbide are mixed to form a boride-based, carbide-based, nitride-based, or oxide-based intermetallic compound amorphous To form a modified surface treatment layer composed of a substance.

Element group (A): Boron, carbon, nitrogen, oxygen.

[Work]

The operation of the forging die and the manufacturing method thereof according to the present invention configured as described above is as follows.

Using an ion implantation device, ions of one element selected from the group of elements of boron, carbon, nitrogen, and oxygen are implanted into the surface of the forging die, and at the same time vacuum deposition of titanium is simultaneously performed. As a result, these ions and titanium, which is the vapor deposition element, are mixed with the substrate of the surface layer portion of the base metal of the workpiece made of tool steel or cemented carbide to form a boride-based or carbide-based, or nitride-based material. A modified surface treatment layer having a high strength and excellent wear resistance is formed in which a material-based or oxide-based amorphous intermetallic compound material is integrated with a material substrate.

The surface layer of such a die for forging is not separated into two distinct layers such as a thin film formed by PVD method or CVD method, but the die substrate and the modified layer are mixed and integrated. And
The surface layer does not peel off even under severe dynamic pressure conditions, and the surface layer has extremely high strength.

Moreover, in addition to the base metal itself being made of a hard metal such as tool steel or cemented carbide, titanium that is supplied at the same time as the implantation of ions has a function of increasing the bonding degree of intermetallic compounds. Therefore, the adhesion of the metal compound is further increased, and a modified layer having higher strength can be obtained.

〔The invention's effect〕

 The effects of the above configuration are as follows.

That is, by implanting ions of one element selected from the group of elements consisting of boron, carbon, nitrogen, and oxygen, and vacuum-depositing titanium, these ions, titanium that is a vapor deposition element, tool steel, or super steel A mixed material such as a base metal of a work piece made of a hard alloy that is mixed and integrated, and is a boride-based, carbide-based, nitride-based, or oxide-based intermetallic compound-based amorphous substance It was possible to obtain a high-strength modified surface-treated layer having excellent peel resistance and having a higher binding force due to the increasing action of titanium, which is suitable as a die for forging.

Moreover, the ion-implanted and mixed surface layer is provided with an intermetallic compound-based amorphous material layer having excellent mechanical properties, and this intermetallic compound-based amorphous material layer is manufactured by rapidly cooling from a molten state. Unlike amorphous metal, which has a high thermal stability, the surface layer does not deteriorate and deteriorate even when heated by continuous forging, so that a durable and long-life mold is also used in this respect. Can be obtained.

In addition, by forming a modified surface treatment layer integrated with the base metal in this way, it is not necessary to separately form a coating layer on the surface of the base metal. It is possible to obtain a high-quality mold as a mold, which is effective in improving the manufacturing accuracy of products, that is, the dimensional accuracy is stable and the dimensional accuracy is stable.

Further, according to the method of the present invention, since heating as in the CVD method is not necessary, even if the surface modification treatment is performed after the necessary heat treatment, the heat-treated portion of the surface layer is not adversely affected.

As a result, a forging die with high accuracy, high strength and long life, which does not impair the strength of the die and does not disturb the dimensional accuracy, has excellent productivity of forged products. Was obtained.

〔Example〕

An embodiment of a forging die and its manufacturing method according to the present invention will be described in detail below with reference to the drawings.

As the forging die, a cold forging die which is used for manufacturing a taper roller for a taper roller bearing and which requires particularly severe conditions is taken as an example.

FIG. 1 shows a vertical cross section of the mold. The die (1) is composed of a combination die including a male die (punch side) (1a) and a female die (1b), and a header machine (not shown).
The steel wire piece cut by is arranged between the two dies as a material (2) for a taper roller which is a workpiece. The dimension of the steel wire piece at this time is, for example, 22 mm in length,
The diameter was 10 mm.

Of the mold shapes shown in FIG. 1, a severe dynamic load is applied particularly to the corners, and damage such as cracks and chips is likely to occur. Therefore, ion implantation was performed on the corner portion and other portions where the material (2) and the die were in contact with each other. (3) in the figure
Is an ion-implanted and mixed mixing layer.

Next, a method for forming the mixing layer will be described below.

The method used in this example is also called a dynamic mixing method or IVD (Ion and Vapor Deposition) method (M. Satou, K. Fukui and F. Fujimoto, Proc.
5th Symp. ISIAT, p.349, 1982), which uses lower ion acceleration energy than the ordinary ion implantation method and performs vacuum deposition and ion implantation at the same time.

FIG. 2 shows a schematic configuration of the ion implanter used.

This apparatus uses a cold cathode type ion source as an ion source (5), and from the ions emitted from this ion source (5), only the ions to be injected are taken out by a mass spectrometric system (6) and placed on a sample table (17). It is designed to be injected into the placed sample (7). Therefore, the impurity element which is not planned is sieved by the mass spectrometry system (6), and the impurity element is not mixed in the sample (7). Further, by controlling the current density of selected ions, the composition ratio of the compound thin layer formed on the sample surface layer can be controlled.

In the figure, (14) is a valve, (8) is a repelling electrode for accurately knowing the ion current applied to the sample (7),
This is provided with a lens function for obtaining a current density and a uniform irradiation area in the sample (7). In the figure, (9) is a current integrator for measuring the ion current applied to the sample (7).

On the other hand, an electron beam vapor deposition device (11) is installed in the chamber (10) in order to mix another ion on the surface of the sample (7) together with the ion from the ion source (5). It is convenient to use the electron beam vapor deposition apparatus (11) because the vapor deposition rate can be easily controlled by adjusting the electron beam current. A quartz vibrating type film thickness meter (12) equipped with a quartz plate is also installed in the chamber (10) in order to measure the deposition amount of the sample surface layer by the electron beam deposition apparatus (11). This allows the vapor deposition film thickness to be accurately measured by changing the frequency of the crystal oscillator. In the figure (13) is the chamber (10)
It is an exhaust port connected to an axial flow molecular pump (not shown) for exhausting the inside. However, the vapor deposition device (11) for mixing different ions is not limited to the electron beam vapor deposition device as described above, and may be a normal vapor deposition device.

When inserting the sample die (7) into the ion implanter and performing ion implantation, first, the surface part of the die that comes into contact with the workpiece is oriented toward the ion implantation direction on the sample stage (17). To install. Then, the mixing process is performed under predetermined conditions.

The implantation conditions at this time are as follows.

Ion species ………… N (N ₂ ) Vapor deposition element ………… High-purity metallic titanium was used as Ti.

Acceleration voltage (Kev) …… 40 N ₂ ion implantation dose (pieces / cm ² ) …… 5 to 7 × 10 ¹⁶ ultimate vacuum (Pa) ………… 3 × 10 ^-5 (when thin layer is formed ( Pa) ………… Approx. 10 ^-3 ) Deposition rate (Å / sec) ………… Approx. 10 Current value during deposition (mA) ………… 3 According to the above conditions, the intermetallic compound-based non-metallic compound is not formed on the metal surface. A layer of crystalline material will be formed.

A taper roller for a taper roller bearing was manufactured on the basis of the material shown in FIG. 1 by using the above-mentioned mixing-treated mold. Then, the life of this mold was compared with that of a mold not subjected to mixing treatment. The life at this time was defined as the number of products manufactured until they became unusable as a mold, such as damage to the product. The result is the first
Shown in the table.

As the base material of the die, JIS SKD-11, SKH- for tool steel, which is currently generally used as a cold forging die.
9 and cemented carbide (NK-15) were used.

As shown in Table 1, in the SKD-11 and SKH-9 molds, the mixing treatment resulted in a life of three times or more, and in the cemented carbide mold, the life was more than twice.

As the ion species to be mixed, in addition to the above TiN, TaC, T
iC, VC, BN, TiN ₂ , Fe ₂ N, etc., which are the elements belonging to Group III to Group VI and Group VIII in the Periodic Table of Elements alone or 2
You may make it use in combination of 2 or more types.

Various conditions can be considered as the mixing treatment, and the treatment can be performed according to the purpose by changing the ion implantation amount, the implantation depth and the like.

Needless to say, the present invention may be applied to a hot forging die.

Furthermore, the surface layer of the forging die may be modified by a method other than the dynamic mixing method or the IVD method.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a forging die according to the present invention, and FIG. 2 is a schematic configuration diagram of an ion implantation apparatus used for implementing the present invention. (2) ... Workpiece, (3) ... Mixing layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinobu Shimotani, 3-13-41 Shindo, Matsubara-shi, Osaka (72) Nobuo Terao 1-15-14, Satsukinonishi, Mihara-cho, Minamikawachi-gun, Osaka Mika Kagawa (56) References JP-A-58-181863 (JP, A) JP-A-61-272364 (JP, A)

Claims (2)

[Claims] 1. At least a surface (4) in contact with a workpiece (2) is subjected to ion implantation of one element selected from the following element group (A) and vacuum deposition of titanium to form one of these elements. Borides, carbides, nitrides, or oxides obtained by mixing ions, vapor deposition elements, and the base metal of the workpiece (2) made of tool steel or cemented carbide, Forging die having a modified surface treatment layer made of an intermetallic compound-based amorphous substance, element group (A) ... boron, carbon, nitrogen, oxygen. 2. At least a surface (4) in contact with the workpiece (2) is simultaneously subjected to ion implantation of one element selected from the following element group (A) and vacuum deposition of titanium. Due to
These ions, vapor deposition elements, and the base metal of the workpiece (2) made of tool steel or cemented carbide are mixed to form a boride-based, carbide-based, nitride-based, or oxide-based material. A method for manufacturing a forging die for forming a modified surface treatment layer made of an intermetallic compound-based amorphous substance, element group (A) ... Boron, carbon, nitrogen, oxygen.