JP3185044B2 - Manufacturing method of bearing parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a bearing component, and more particularly to a method of manufacturing a bearing component suitable for use in a bearing used in dirty oil mixed with foreign matter.

[0002]

2. Description of the Related Art Generally, when a bearing is used in dirty oil mixed with foreign matters such as metal powder and molding sand, its life is reduced to 1/2 to 1/10 or less of the calculated life.

In view of the above, as a bearing component having an improved life in contaminated oil contaminated with foreign matter, the present applicant has a carburized layer on which fine spherical carbides are precipitated, and has a carbon concentration of 1.5 to 1.5 at the surface. 3.0% by weight, the particle size of the fine spherical carbide is 10 μm or less, and the amount is 50% by area ratio.
A bearing component in which the carbon concentration in the matrix of the carburized layer is 0.6 to 0.7% by weight (see Japanese Patent Application Laid-Open No. 2-107755).

[0004] As described in the above-mentioned publication, this method of manufacturing a bearing component includes a first step of performing a primary carburizing treatment,
2. Carbide treatment is performed to reduce the carbon concentration on the surface from 1.5 to 3.
It comprises a second step of depositing carbides at 0% by weight and a third step of performing quenching treatment to obtain fine spherical carbides.

In this method, it is extremely difficult to control the carburizing atmosphere in order to uniformly precipitate fine spherical carbides in the second step. Therefore, in the second step, coarse reticulated carbides are precipitated by carburizing treatment, and then the second step is performed. The coarse reticulated carbide is finely crushed by three steps of quenching to obtain a fine spherical carbide.

[0006]

However, in order to obtain a fine spherical carbide having a particle size of 10 μm or less in the third step, the quenching process must be repeated many times, which is troublesome. There's a problem. Moreover, as a result of repeatedly performing the quenching treatment, there is a problem that fine carbides are precipitated, the amount of carbon in the matrix is reduced, and the strength is reduced.

An object of the present invention is to provide a method for manufacturing a bearing component which has solved the above-mentioned problems.

[0008]

According to a method of manufacturing a bearing part according to the present invention, a processed bearing part material formed into a predetermined shape from steel is subjected to a carburizing treatment or a carburizing and quenching treatment to reduce the carbon concentration of a surface portion. A first step of 0.8 to 1.8% by weight, a second step of performing quenching treatment to uniformly precipitate fine spherical carbides on the carburized layer, and And a third step of performing a high-concentration carburizing and quenching treatment so that the carbon concentration becomes higher than the carbon concentration of the surface portion obtained in one step to grow fine spherical carbides.

[0009] In the above, as steel, carbon 0.1 ~
It is preferable to use one containing 0.3% by weight and 0.7 to 3.0% by weight of chromium.

The reason why the carbon concentration of the surface portion is set to 0.8 to 1.8% by weight by the carburizing treatment or the carburizing and quenching treatment in the first step is as follows. That is, if the carbon concentration of the surface after carburizing or carburizing and quenching is within the above range, the generation of carbides in the carburized layer can be prevented. This is because it is possible. On the other hand, if the carbon concentration at the surface is less than 0.8% by weight, fine spherical carbides cannot be uniformly deposited in the second step, so that 1.8% by weight cannot be obtained.
If the temperature exceeds the above range, coarse reticulated carbides are precipitated in the second step, and it is necessary to increase the carburizing temperature, so that the crystal grains are coarsened and the strength is reduced. Further, the carburization in the first step may be performed by any method such as fluidized bed carburization, gas carburization, and ion carburization.

When quenching is performed in the second step, fine spherical carbides are generated in the carburized layer. When the high-concentration carburizing and quenching treatment is performed in the third step, the fine spherical carbides precipitated in the second step grow, the particle diameter increases, and the carbon in the matrix decreased by the carbide precipitation in the second step. The concentration becomes a high carbon concentration while supplementing the amount.

After completion of the third step, the carbon concentration on the surface is 1.
5 to 3.0% by weight, the particle size of the precipitated carbide is 10 μm
m or less, the amount is preferably 15 to 80% in area ratio, and the carbon concentration of the carburized layer matrix is preferably 0.6 to 0.7% by weight. The surface hardness is preferably 63 to 68 in Rockwell C hardness, and the amount of retained austenite is preferably 13 to 35%.

The quenching process in the second step may be performed a plurality of times.

[0014]

In the quenching treatment in the second step, fine spherical carbides are evenly distributed on the carburized layer where carbide is not deposited after the first step.
Since they are deposited all at once, there is no need to repeat the process as in the conventional method. In addition, the high-concentration carburizing treatment in the third step is for growing the fine spherical carbides precipitated in the second step, so that the carburizing atmosphere can be easily controlled. Moreover, in the second step, the amount of carbon in the matrix is reduced due to the precipitation of fine spherical carbides, but the third step can compensate for the amount of carbon in the matrix, so that the strength does not decrease.

[0015]

Next, an embodiment of the present invention will be described.

Example 1 First, the carbon content was 0.2% by weight and the chromium content was 0.1%.
Materials of inner and outer wheels for roller bearings and materials for rollers were prepared using SAE5120 material of 8% by weight, and these materials were subjected to a heat treatment under the following conditions. That is, each material was subjected to a carburizing and quenching treatment in which the material was carburized by holding it at 930 ° C. for 5 hours in a carburizing atmosphere containing 10% of C ₃ H ₈ by a fluidized bed furnace, followed by quenching. Then, at 830 ° C, 30
A re-quenching treatment of holding and quenching for a minute was performed. Thereafter, high-concentration carburizing treatment was carried out by holding at 930 ° C. for 5 hours in a carburizing atmosphere containing 17% of C ₃ H ₈ by a fluidized bed furnace.
Thus, inner and outer wheels and rollers for roller bearings were manufactured, and the roller bearings were assembled using these.

Example 2 Inner and outer wheels for roller bearings and rollers were manufactured in the same manner as in Example 1 except that the re-quenching treatment in the second step in Example 1 was performed twice. The roller bearing was assembled.

Example 3 After completion of the third step in Example 2 described above, an additional 830
Other than the quenching treatment of quenching by holding at 30 ° C for 30 minutes,
Inner and outer wheels and rollers for roller bearings were manufactured in the same manner as in Example 1, and a roller bearing was assembled using these. As in this embodiment, if the quenching treatment is performed after the end of the third step so that the strength does not decrease due to the decrease in the carbon concentration in the matrix, the carbides can be made finer.

Embodiment 4 The carburizing atmosphere in the first step in the above embodiment 1 was changed to C ₃ H _8.
The inner and outer wheels and rollers for the roller bearing were manufactured in the same manner as in Example 1 except that the atmosphere containing ₈ % and the atmosphere containing 12% of C ₃ H _{8 in} the high concentration carburizing atmosphere in the third step were used. Then, a roller bearing was assembled using these.

Example 5 After the completion of the third step in Example 4 described above, an additional 830
Other than the quenching treatment of quenching by holding at 30 ° C for 30 minutes,
The inner and outer wheels and rollers for roller bearings were manufactured in the same manner as in Example 4, and the roller bearings were assembled using these.

Embodiment 6 The high-concentration carburizing treatment of the third step in the above-mentioned Embodiment 5 was carried out by holding the mixture at 930 ° C. for 7 hours in a carburizing atmosphere containing 12% of C ₃ H ₈ in a fluidized bed furnace. Otherwise, the inner and outer wheels and rollers for the roller bearing were manufactured in the same manner as in Example 5, and the roller bearing was assembled using these.

Example 7 The high concentration carburizing treatment of the third step in the above Example 5 was carried out by holding the mixture at 930 ° C. for 5 hours in a carburizing atmosphere containing 14% of C ₃ H ₈ in a fluidized bed furnace. Otherwise, the inner and outer wheels and rollers for the roller bearing were manufactured in the same manner as in Example 5, and the roller bearing was assembled using these.

Example 8 Both inner and outer rollers for a roller bearing were manufactured in the same manner as in Example 4 above. In addition, a JIS SUJ2 material is used to make a roller bearing roller material, and this material is quenched at 830 ° C for 30 minutes and quenched at -60 ° C for 2 hours. And in this order to produce rollers. Then, a roller bearing was assembled using the inner and outer wheels and the rollers.

Example 9 In the same manner as in Example 7 above, inner and outer wheels for a roller bearing were manufactured. Further, a roller was manufactured in the same manner as in Example 8 above.
Then, a roller bearing was assembled using the inner and outer wheels and the rollers.

Example 10 In the same manner as in Example 3, both inner and outer wheels for a roller bearing were manufactured. Further, a roller was manufactured in the same manner as in Example 8 above.
Then, a roller bearing was assembled using the inner and outer wheels and the rollers.

Example 11 An inner ring and a roller for a roller bearing were manufactured in the same manner as in Example 8 above. Further, a material for an outer ring for a roller bearing was manufactured using SAE5120 material having a carbon content of 0.2% by weight and a chromium content of 0.8% by weight, and this material was subjected to a heat treatment under the following conditions. That is, C ₃ H ₈ 8% by fluidized bed furnace
After carburizing by holding at 930 ° C. for 5 hours in a carburizing atmosphere containing
Carburizing and quenching to hold and quench for 30 minutes
A secondary quenching treatment of holding and quenching for a period of one minute was performed in this order to produce a roller bearing outer ring. Then, a roller bearing was assembled using the inner and outer wheels and the rollers.

Example 12 An inner ring and a roller for a roller bearing were manufactured in the same manner as in Example 9 above. An outer ring for a roller bearing was manufactured in the same manner as in Example 11 above. Then, a roller bearing was assembled using the inner and outer wheels and the rollers.

Example 13 An inner ring for a roller bearing and a roller were manufactured in the same manner as in Example 10 above. An outer ring for a roller bearing was manufactured in the same manner as in Example 11 above. Then, a roller bearing was assembled using the inner and outer wheels and the rollers.

COMPARATIVE EXAMPLE Material of inner and outer wheels for roller bearings was manufactured using SAE5120 material having a carbon content of 0.2% by weight and a chromium content of 0.8% by weight. Then, the inner ring material was carburized by holding at 930 ° C. for 5 hours in a carburizing atmosphere containing 7% of C ₃ H ₈ by a fluidized bed furnace, and then cooled to a quenching temperature of 850 ° C. and held for 30 minutes. Carburizing and quenching were performed to produce inner rings for roller bearings. The outer ring material was carburized in a carburizing atmosphere containing 7% of C ₃ H ₈ by a fluidized bed furnace at 930 ° C. for 5 hours, and then 850 ° C.
Quenching temperature, holding for 30 minutes and quenching, followed by a secondary quenching process of heating to 900 ° C. by a press quenching method and then immediately quenching, in this order. Manufactured bearing outer rings. Furthermore, using JIS SUJ2 material, a roller material for roller bearings was made.
Was subjected to a normal quenching treatment of quenching while holding for 30 minutes to produce rollers. Then, a roller bearing was assembled using the inner and outer wheels and the rollers.

The inner and outer wheels and rollers in Examples 1 to 13 and Comparative Example were subjected to a tempering treatment at 160 to 200 ° C. for 2 hours.

The surface hardness, the amount of retained austenite, the C of the surface, the average particle size and area ratio of the precipitated spherical carbide, and the C of the carburized layer matrix in the above Examples 1 to 13 and Comparative Example were measured. did. Table 1 shows the results for the inner ring, and Table 2 shows the results for the outer ring.
Table 3 shows the results for the rollers.

[0032]

[Table 1] In the columns of the average particle size and the area ratio of the spherical carbide in Table 1, the mark x indicates that no precipitated spherical carbide was present.

[0033]

[Table 2]

[Table 3] Evaluation Test Using the roller bearings assembled in Examples 1 to 13 and Comparative Example, a high-speed steel powder (hardness: H
v830) was carried out in a soil oil containing 1.1 g, and the life ratio when the life of the comparative example was set to 1 was examined. Table 4 shows the results.

[0034]

[Table 4]

[0035]

According to the method for manufacturing a bearing component of the present invention,
This eliminates the need to repeat the quenching treatment in the second step over and over, and also facilitates the control of the carburizing atmosphere in the high concentration carburizing treatment in the third step, thereby simplifying the operation. Further, since it is not necessary to repeat the quenching process many times, a reduction in strength can be prevented , and
The life of the manufactured bearing component in dirty oil is prolonged .

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C21D 9/00-9/44 C21D 9/50 C21D 1/06 C23C 8/22

Claims (1)

(57) [Claims] 1. A first step of subjecting a machined bearing part material formed of steel to a predetermined shape to a carburizing treatment or a carburizing and quenching treatment to adjust the carbon concentration of the surface portion to 0.8 to 1.8% by weight. And a second step of performing a quenching treatment to uniformly deposit fine spherical carbides on the carburized layer, and a carbon concentration of the surface portion higher than the carbon concentration of the surface portion obtained in the first step. Performing a high-concentration carburizing and quenching treatment so as to attain a high concentration to grow fine spherical carbides.