JP4120406B2 - Roller bearing cage and method for manufacturing roller bearing cage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a roller bearing retainer and a method for manufacturing a roller bearing retainer .
[0002]
[Prior art]
Among the cages used in roller bearings (so-called cage-and-rollers) composed only of cages, there are welding type cages.
[0003]
This welding type cage is generally formed by performing necessary processing such as forming a pocket using a band-shaped metal plate as a base, and then rounding it into a cylindrical shape to weld both ends.
[0004]
In this welding type cage, for example, low carbon steel such as JIS standard SPC is used for easy forming and welding, and carburizing hardening treatment is applied to the surface portion in order to improve wear resistance. By doing so, the surface metallographic structure is made martensite and the surface is made to have high hardness. (See Patent Document 1).
[0005]
[Patent Document 1]
JP-A-10-237620 [0006]
[Problems to be solved by the invention]
It is pointed out that the cage of the conventional example has insufficient fatigue strength, and the durability is deteriorated particularly when used in a severe environment. In the conventional cage, the surface hardness is 750 to 800 in terms of Vickers hardness (HV), and the internal hardness is 150 to 170 in terms of Vickers hardness (HV). Based on this, the inventor inferred that the metal structure inside the cage of the conventional example is ferrite / pearlite, and as a result of such metal structure, the fatigue strength is insufficient as described above. I thought.
[0007]
[Means for Solving the Problems]
A roller bearing retainer according to the present invention is a roller bearing retainer which is manufactured by rolling a belt-shaped metal plate into a cylindrical shape and welding both ends, and is provided with pockets penetrating radially at several circumferential positions. As the band-shaped metal plate, a cold-rolled steel plate in which the content of the C component is set to 0.10% or more and 0.20% or less is used, and heat treatment is performed on this in the manufacturing process. The surface metal structure is martensite, the surface hardness is set to 400 to 700 in terms of Vickers hardness (HV), and the internal metal structure is mainly composed of low carbon martensite. In addition, the internal hardness is set to 250 or more in terms of Vickers hardness (HV), and the welding is performed on the strip metal plate after the heat treatment.
The method for manufacturing a roller bearing retainer according to the present invention includes a step-shaped intermediate portion in the width direction of a strip-shaped cold-rolled steel sheet in which the C component content is set to 0.10 or more and 0.20% or less. A step of forming a pocket, a step of performing a heat treatment, a step of rounding into a cylindrical shape and welding both ends after the heat treatment, and the heat treatment is performed at 800 ° C. or higher and 900 ° C. or lower. Carburizing and quenching performed at a temperature of 0.5 h to 1.0 h and tempering performed at a temperature of 300 ° C. to 400 ° C. for 0.5 h to 1.5 h. Therefore, the surface metal structure is martensite, the surface hardness is set to 400 to 700 in terms of Vickers hardness (HV), and the internal metal structure is mainly composed of low carbon martensite. Has been Both internal hardness is set to 250 or more Vickers hardness (HV).
[0008]
In this case, since the internal hardness is increased sufficiently and sufficiently after the internal metallographic structure is made dense and stable in the cage, the fatigue strength is improved.
[0009]
Note that a cold-rolled steel sheet in which the content of the C component is set to 0.10% or more and 0.20% or less is used as the band-shaped metal sheet, and heat treatment is performed on this in the manufacturing process. Thus, the metal structure and hardness from the surface to the inside can be ensured. In this case, the metal structure and hardness as described above can be easily ensured.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 to 6 show an embodiment of the present invention. In the figure, 1 is a cage and 2 is a roller. This cage 1 is a combination of only the rollers 2 and constitutes a roller bearing called a cage and roller. This roller bearing is used for each part of a manual transmission, for example, and the outer peripheral surface of an inner diameter side member such as a shaft inside the transmission is used as an inner ring raceway of the roller 2 and an outer gear such as a transmission gear inside the transmission. The inner peripheral surface of the diameter side member is the outer ring raceway of the roller 2.
[0011]
The cage 1 is manufactured by rolling a belt-shaped metal plate into a cylindrical shape and welding both ends, and pockets 3 penetrating in the radial direction are provided at several places on the circumference thereof. The retainer 1 here has an outer diameter surface guided to the outer diameter side member.
[0012]
The pocket 3 has a substantially rectangular shape when seen in a plan view, and the roller 2 is accommodated in the pocket 3 so as not to come out radially inward and outward. For example, in the cage 1, a column part 4 exists between the pockets 3 adjacent in the circumferential direction, and an annular part exists on both axial sides of the column part 4. Moreover, the cross-sectional shape of the pocket 3 becomes a fan shape as shown in FIG. 4 based on the manufacturing method as described above.
[0013]
The intermediate portion in the axial direction of the column portion 4 is bent so as to sink inward in the radial direction. In the sunk axially intermediate portion, the circumferentially opposed distance between the axial end portions 5 and 5, that is, the opening width on the inner diameter side of the pocket 3 is set smaller than the diameter of the roller 2. As shown, the rollers 2 are prevented from coming out radially inward. Moreover, the convex part 6 is provided in the circumferential direction both sides | surfaces of the axial direction both ends in the pillar part 4. As shown in FIG. The circumferentially facing interval between the convex portions 6 and 6 of the two pillar portions 4 facing the pocket 3 is set smaller than the diameter of the roller 2, whereby the roller 2 has a diameter as shown in FIG. 5. It is designed to prevent getting out of the direction. 4 and 5, PCD indicates a circle diameter connecting the centers of all the rollers 2 in a state in which the rollers 2 and the cage 1 are incorporated into the object of use.
[0014]
In the above configuration, in this embodiment, in the cage 1, the surface metal structure is martensite, and the surface hardness is 400 to 700, preferably 400 to 600, in terms of Vickers hardness (HV). Preferably, it is set to 470 or more and 570 or less, and the internal metal structure is a structure mainly composed of low carbon martensite, and the internal hardness is 250 to 400, preferably 300 or more in terms of Vickers hardness (HV). 400 or less is set.
[0015]
In short, the above numerical range takes into consideration increasing the fatigue strength while ensuring ease of forming and welding by making the internal hardness close to the surface hardness without excessively hardening the surface hardness of the cage 1. The inventor determined based on experiments. In particular, if the surface hardness is 400 HV or more and 600 HV or less, the fatigue strength is improved, but 470 HV or more and 570 HV or less is preferable. On the other hand, when the surface hardness is 700 HV, which is the upper limit, the fatigue strength is slightly reduced, but the wear resistance is excellent. For these reasons, it is preferable to set the hardness in consideration of the required conditions.
[0016]
Moreover, the meaning that the metal structure inside the cage 1 is mainly composed of low carbon martensite is meant to include the case where ferrite is present in the inside of the cage 1 in an amount of 10% or less, for example. Further, the surface of the cage 1 is not particularly limited, but as an application example of the present invention, for example, when the plate thickness of the cage 1 is 1.2 to 2.0 mm, the outer surface To a depth of 0.15 mm. According to this range, a deeper part becomes the inside of the cage 1.
[0017]
A method for manufacturing such a cage 1 will be described.
[0018]
First, a cold-rolled steel sheet in which the content of the C component is set to 0.10% or more and 0.20% or less is used as the band-shaped metal plate serving as the base of the cage 1. As this cold-rolled steel sheet, for example, BAS standard SPB2 (content of component C 0.13% to 0.20%) can be mentioned.
[0019]
In order to obtain the cross-sectional shape shown in FIG. 2 with respect to the strip-shaped metal plate, a step of bending the intermediate portion in the width direction to have a stepped shape, a step of forming pockets 3, a step of performing heat treatment, and a cylindrical shape And at least a step of welding both ends. Note that, for example, a polishing finish is performed after the welding process.
[0020]
The heat treatment includes carburizing and quenching and tempering. In carburizing and quenching, a predetermined amount of C component is permeated and diffused on the surface to form high carbon, which is quenched. The quenching at the time of carburization is performed at a temperature of 800 ° C. or higher and 900 ° C. or lower and taking a time of 0.5 h or longer and 1.0 h or shorter. In tempering, the austenite remaining on the surface and inside of the cage 1 is martensified by the carburizing and quenching. This tempering is performed, for example, at a temperature of 300 ° C. or higher and 400 ° C. or lower and taking a time of 0.5 h or longer and 1.5 h or shorter.
[0021]
As described above, in this embodiment, a high-carbon steel having a C component content higher than that of the conventional product is used as the band-shaped metal plate serving as the base of the cage 1, and the heat treatment is performed to hold the finished product. The metal structure and hardness from the surface to the inside of the vessel 1 are set as described above. In particular, the metal structure inside the cage 1 is made denser and more stable than the ferrite / pearlite as in the conventional example, and the hardness inside the cage 1 is sufficiently increased. As a result, the fatigue strength of the cage 1 can be improved, and the durability and reliability can be improved.
[0022]
For reference, the fatigue strength test was performed with the surface hardness changed, which will be described. Three samples, Examples 1 and 2 and a comparative example, were prepared as samples. The samples according to Examples 1 and 2 and the comparative example are cages having the shapes described above, and the hardness is changed. In Example 1, the material is JIS standard SPB2, the surface hardness is set to 530 HV, and the internal hardness is set to 350 HV. In Example 2, the material is JIS standard SPB2, the surface hardness is set to 700 HV, and the internal hardness is set to 380 HV. In the comparative example, the material is JIS standard SPC, the surface hardness is set to 650 HV, and the internal hardness is set to 150 HV.
[0023]
As a result, as shown in FIG. 6, Examples 1 and 2 confirmed that the fatigue strength was improved over the comparative example under all conditions. In FIG. 6, the vertical axis represents the radial load applied to the sample, and the horizontal axis represents the logarithm of the number of repetitions of the load applied to the sample. The repetition period is 20HZ.
[0024]
In addition, this invention is not limited only to the holder | retainer 1 illustrated by the said embodiment, This invention is applicable also to the thing from which the hole shape of the pocket 3 and the cross-sectional shape of the pillar part 4 differ.
[0025]
【The invention's effect】
The cage for roller bearings of the present invention has improved fatigue strength as compared with the conventional example, so that durability and reliability are improved even in use in severe environments.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a part of a roller bearing retainer according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an upper half of the roller bearing retainer shown in FIG. FIG. 4 is a developed plan view showing a pocket of a roller bearing cage. FIG. 4 is a sectional view taken along line (4)-(4) in FIG. 1. FIG. 5 is an arrow taken along line (5)-(5) in FIG. FIG. 6 is a chart showing the results of examining the fatigue strength of the roller bearing cage of the present invention and comparative examples.
1 Cage 2 Roller 3 Cage Pocket 4 Cage Column

Claims (2)

A roller bearing retainer that is manufactured by rounding a belt-shaped metal plate into a cylindrical shape and welding both ends, and provided with pockets that penetrate in a radial direction at several places on the circumference,
As the strip-shaped metal plate, a cold-rolled steel plate in which the content of C component is set to 0.10% or more and 0.20% or less is used, and heat treatment is performed on this in the manufacturing process. The surface metal structure is martensite, the surface hardness is set to 400 to 700 in terms of Vickers hardness (HV), and the internal metal structure is mainly composed of low carbon martensite. A roller bearing cage in which the internal hardness is set to 250 or more in terms of Vickers hardness (HV), and the welding is performed on the band-shaped metal plate after the heat treatment . For the strip-shaped cold rolled steel sheet in which the content of the C component is set to 0.10 or more and 0.20% or less,
Bending the widthwise intermediate portion to have a stepped shape;
Forming a pocket;
A step of performing a heat treatment;
A step of rounding into a cylindrical shape after heat treatment and welding both ends,
The above heat treatment is carburizing and quenching performed at a temperature of 800 ° C. or more and 900 ° C. or less over a period of 0.5 h or more and 1.0 h or less,
Including tempering performed at a temperature of 300 ° C. or more and 400 ° C. or less at a temperature of 0.5 h or more and 1.5 or less,
The surface metal structure is martensite, the surface hardness is set to 400 to 700 in terms of Vickers hardness (HV), and the internal metal structure is mainly composed of low carbon martensite. And a method for manufacturing a roller bearing retainer in which the internal hardness is set to 250 or more in terms of Vickers hardness (HV).

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