JPH0313585A - Method for surface-hardening metal and method for surface-hardening nonmagnetic bearing parts - Google Patents

Abstract

PURPOSE:To efficiently form a sufficiently thick alloy carbide layer on the surface of a metal to harden the surface at a low cost by arranging a mixture of metal powder and carbon powder on the surface of a metallic substrate and irradiating the mixture with a high-density energy beam. CONSTITUTION:A mixture of the powder 2 of a metal such as chromium and carbon powder 3 is arranged on the surface of a metallic substrate 1 of mild steel, etc. The mixture is irradiated with a laser beam, an electron beam, etc., as the high-density energy beam. Consequently, the metal powder 2 and carbon powder 3 are melted, and the surface of the substrate 1 is also melted. An alloy carbide layer 4 is formed on the surface of the substrate 1 in this way, and the carbon atom of the powder 3 is diffused and infiltrated into the substrate 1. The surface of the substrate 1 is hardened with the sufficiently thick alloy carbide layer 4. Nonmagnetic metal powder and carbon powder are arranged on the surface of a nonmagnetic bearing part, and irradiated with a high density energy beam by this method to improve the surface hardness and rolling characteristic or the part.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for hardening a metal surface and a method for hardening the surface of a non-magnetic bearing component.

<Prior art> Various conventional methods of curing metal surfaces have been considered, and three examples are listed below. Thereafter, this metal base material is carburized.

(2) Similar to (2), a method in which appropriate metal powder is placed on a metal surface and irradiated with an electron beam or laser beam, and then carbon powder is placed on this metal surface and the electron beam or laser beam is irradiated again.

■ A method in which a carbide such as titanium carbide is placed on a metal surface and irradiated with an electron beam or laser beam.

In methods (■) and (■) above, first, the metal base material and the metal powder are alloyed on the metal surface, and as a result of the diffusion of carbon atoms into this alloyed part, an alloy carbide layer is formed on the metal surface. Become. Furthermore, in the method (2), the metal surface is coated with a ceramic film.

<Problems to be Solved by the Invention> However, the conventional curing method described above has the following disadvantages.

First, methods (1) and (2) both require two independent steps and are inefficient. Moreover, since carbon atoms are diffused into the alloy layer after alloying the metal surface, it is difficult for carbon atoms to diffuse into the alloy layer, and although a thick alloy layer can be formed, it is difficult to make the alloy carbide layer too thick. There is a limit to the improvement of surface hardness.

Furthermore, in the method (2), since carbide is melted, a considerable amount of thermal energy is required compared to the case where metal powder, carbon powder, etc. are melted. Moreover, since the result is a ceramic film adhered to the surface of the metal base material rather than an alloy with the metal base material, it has been pointed out that the peel strength of the ceramic film is insufficient.

By the way, in rolling bearings, for example, the raceway rings are sometimes made of non-magnetic materials, such as titanium alloys or austenitic stainless steel, but these materials lack the hardness for bearings, so carburizing or forming a ceramic film is required. Surface hardening of the rolling element rolling surface of the raceway and the mating surface to the mating member is performed using a film method, etc. However, the carburizing method described above does not provide a sufficiently thick hardened layer, and the ceramic film does not peel off. There are problems such as insufficient strength, and it is impossible to improve bearing life or rolling characteristics. Note that even if the above methods (■) and (■) are used for this non-magnetic bearing component, there will be the same disadvantages as mentioned above.
The best method has not yet been developed.

The first invention aims at making it possible to form a sufficiently thick carbonized layer of a hard alloy while reducing the number of processing steps and the thermal energy required for the processing. Furthermore, the second invention aims to improve the surface hardness and rolling characteristics of non-magnetic bearing components that lack hardness.

Means for Solving the Problems The present invention has the following configuration in order to achieve the above objects.

The method of hardening a metal surface according to the first invention is characterized in that metal powder and carbon powder are mixed and arranged on the metal surface and irradiated with a high-density energy beam.

Further, the surface hardening method for non-magnetic bearing components according to the second invention is as follows:
It is characterized in that non-magnetic metal powder and carbon powder are placed on the surface of a bearing component made of non-magnetic material, and a high-density energy beam is irradiated onto them.

<Effect> First, 1st. In the second invention, metal powder, carbon powder, and metal surface potassium are melted by irradiation with a high-density energy beam of -degrees to form an alloy carbonized layer on the metal surface and to melt the metal powder on the metal surface. The carbon atoms of the carbon powder will also be diffused into the metal. If sufficient amounts of metal powder and carbon powder are placed on the metal surface, a sufficiently thick alloy carbonized layer can be obtained.

In addition, if a sufficiently thick hard alloy carbonized layer is formed on the surface of a non-magnetic bearing component that lacks hardness through such treatment, its hardness and wear resistance will increase, and the self-contained carbon atoms will increase. The lubrication effect reduces the frictional resistance of the rolling elements and makes them less likely to be damaged.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

An embodiment of the first invention is shown in FIGS. 1 and 2. FIG. As shown in Figure 1, first, mild steel (for example, 5IOC
For example, a metal powder 2 such as chromium and a carbon powder 3 are mixed and arranged on the surface of a metal base material 1 consisting of a metal base material 1 made of chromium. Although each powder is shown extremely large in the figure, for example, 350
In this state, which is preferably less than 100 psi, an electron beam or laser beam as a high-density energy beam is scanned and irradiated. By this irradiation, the metal powder 2 and the carbon powder 3 are melted, and the surface of the metal base material 1 is also melted, and while the surface of the metal base material 1 is alloyed with the metal powder 2, this alloy The carbon atoms of the carbon powder 3 are included in the portion. As a result, an alloy carbonized layer 4 is formed on the surface of the metal base material 1, as shown in FIG. At the same time, the carbon atoms of the carbon powder 3 are diffused deep into the metal base material 1. Note that the diffused carbon components are represented by spots.

Since the alloy carbonized layer 4 is formed in this way, a thick alloy carbonized layer 4 can be obtained by increasing the amount of each powder disposed on the surface of the metal base material 1. . Moreover, since the carbon atoms are diffused deeper into the metal base material 1 through the alloy carbonized layer 4, the surface hardness of the metal base material 1 is sufficiently increased.

It goes without saying that the method for hardening metal surfaces described above can be widely applied to mechanical structures such as rolling bearings in general and rolling rolls.In addition to the above-mentioned metal powders, tungsten, vanadium, etc. , titanium, etc.

Next, FIG. 3 shows an embodiment of the second invention.

Here, we will take a deep groove ball bearing as an example. In Figure 0, 10 is the inner ring;
11 is an outer ring, 12 is a ball, and 13 is a retainer. The inner and outer rings 10.11 are made of a non-magnetic material such as titanium alloy or austenitic stainless steel. The rolling element rolling surfaces 14 and 15 of the inner and outer rings 10 and 11 are hardened using the same procedure as the above-mentioned hardening method. However, the powder for alloying is a non-magnetic material such as titanium.

In this way, each rolling element rolling surface 14°1 of the inner and outer rings 10.11
If an alloy carbide layer 4 is formed on the surface of the rolling element 5 and carbon atoms are diffused deep inside the rolling element transfer surface 12.13,
Even if the material lacks hardness, its surface hardness can be sufficiently increased, and the self-lubricating effect of the carbon atoms in the alloy carbonized layer 4 reduces the rolling friction resistance of the balls 14 as rolling elements and the slippage in minute areas. It becomes possible to reduce resistance.

<Effects of the Invention> As explained above, according to the first invention, it is possible to form a sufficiently thick hard alloy carbonized layer on the metal surface without reducing the number of processing steps and wasting thermal energy. This makes it possible to improve work efficiency, reduce manufacturing costs, and improve the hardness of the metal surface.

Further, according to the second invention, it is possible to sufficiently increase the surface hardness of the bearing component made of relatively soft non-magnetic material, and it is also possible to improve the rolling characteristics, which greatly contributes to longer life. become able to.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the first invention,
Figure 1 is a cross-sectional view schematically showing the hardening process of the metal surface, Figure 2
The figure is a cross-sectional view schematically showing the metal surface after hardening treatment. FIG. 3 is an upper half sectional view of a rolling bearing according to an embodiment of the second invention, in which both the inner and outer raceways are hardened. 1... Metal base material, 2... Metal powder, 3...
- Carbon powder, 4... Alloy carbonized layer. Fig. 1 1...Metal base material 2...Metal powder 3...Carbon powder 4...Alloy carbonized layer Fig. 2

Claims (2)

[Claims] (1) A method for hardening a metal surface, which comprises disposing a mixture of metal powder and carbon powder on a metal surface and irradiating them with a high-density energy beam. (2) A method for surface hardening non-magnetic bearing parts, which comprises placing non-magnetic metal powder and carbon powder on the surface of a bearing part made of non-magnetic material, and irradiating them with a high-density energy beam.