JPH11132241A - Shell type needle roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the bearing service life, and to improve an acoustic characteristic by forming an orbital plane after press molding by using low carbon steel having a specified crystal grain size. SOLUTION: A shell type needle roller bearing is used under a condition where roughness of a contact surface of a bearing ring with a needle roller is generally largely different. That is, from a material of the bearing ring, almost same roughness (Ra=0.06 to 0.07 μm) is obtained regardless of the crystal grain size as illustrated, but in a pressed bearing ring, roughness is large in the one having the large crystal grain size, and is remarkably large when the crystal grain size is not more than about No. 7. Thus, in a work surface having bad roughness, a projection becomes a stress concentration source, and becomes a cause of reducing the service life and an acoustic characteristic. Therefore, when low carbon steel having the crystal grain size not less than JIS No. 8 is used as a material of the bearing ring, a bearing ring having an excellent roughness orbital plane can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle-type needle roller bearing, and more particularly to a long-life and excellent sound used for a T / M of an automobile, a compressor of a car cooler, a machine tool, and an office machine. The present invention relates to a shell-type needle roller bearing having characteristics.

[0002]

2. Description of the Related Art In general, low-carbon steel hoop material is used as a material for a bearing ring of a shell type needle roller bearing, and the hoop material is formed by pressing, drawing, intermediate drawing, and final drawing.
A deep drawing process is performed, and then a predetermined shape is formed by several stages of pressing, followed by carburizing or carbonitriding, and finally barrel finishing.

[0003] Since the raceway surface of the raceway ring thus obtained is not polished, the surface roughness is substantially determined by press working. Therefore, when a predetermined roughness is required, press working conditions and accuracy of the mold surface,
It is considered to control barrel processing conditions and the like. As for a high-precision product, a solid-type needle roller bearing which has been machined and then polished and tumbled is used.

[0004]

In such a raceway of a shell type needle roller bearing, the life and acoustic characteristics are greatly affected by the roughness of the raceway surface. There is a limit in improving the press working conditions and molds of the technology, and in controlling the barrel working conditions, and thus a track surface with sufficient roughness has not been obtained until now.

In the case of a solid type needle roller bearing, the bearing ring is formed by turning, then carbonitriding and quenching, and then finished by grinding. However, there are difficulties in terms of productivity and cost.

As described above, it is difficult to improve the roughness of the raceway surface of the raceway of the conventional needle roller bearing from the viewpoint of the working surface. An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a shell-type needle roller bearing capable of improving the bearing life and having excellent acoustic characteristics.

[0007]

In order to solve the above-mentioned problems, the present invention provides a shell type needle roller bearing having a bearing ring formed by pressing a material of low carbon steel. The grain size is JIS
A shell type needle roller bearing characterized by being No. 8 or more is provided.

That is, the shell-type needle roller bearing of the present invention is characterized in that the raceway surface formed by press working is made of low carbon steel having a crystal grain size of JIS No. 8 or more. If the grain size of the raceway surface of the raceway ring is JIS No. 8 or more, the larger the JIS No., the better the grain size is, that is, the finer the grain size. However, in practice, JIS Nos. 8 to 9 are preferable. If the crystal grain size is less than JIS No. 8, that is, 7 or less, a shell-type needle roller bearing having excellent raceway surface roughness and excellent life and acoustic characteristics cannot be obtained.

[0009] The press working of the bearing ring is performed by performing deep drawing including three steps of punching, intermediate drawing, and final drawing, and then working into a predetermined shape by several stages of pressing. After being formed by press working, the bearing ring is heat treated and hardened by carburizing or carbonitriding.
Then, finally, the manufacture of the bearing ring is completed by barrel finishing.

The shell-type needle roller bearing of the present invention can be constructed by incorporating a needle roller and a retainer into the raceway thus obtained. The shell-type needle roller bearing is generally used under the condition that roughness of two contact surfaces of the bearing ring and the needle roller is largely different. That is, since the needle roller is polished and tumbled, the roughness is very good (eg, about 0.04 Ra μm).
Since the raceway surface of the outer ring is a pressed surface, the roughness is very poor (for example, about 0.6 Raμm). On a work surface having such a poor roughness, the projections are a source of stress concentration, and cause a reduction in life and acoustic characteristics.

The present inventors have studied that when the size of the crystal grain size is changed by pressing of a low carbon steel material,
It was found that the press formability, that is, the surface roughness changed. That is, the raw material before the press working has almost the same roughness regardless of the crystal grain size, but after the press working, if the size of the crystal grain changes, the roughness greatly changes.

From these facts, the present inventors obtain a raceway having a raceway surface with good roughness by using a low carbon steel having a crystal grain size of JIS No. 8 or more as a material of the raceway. It has been found that this results in a shell-shaped needle roller bearing with significantly improved life and acoustic properties. The present invention is based on such findings.

[0013] When low-carbon steel of JIS No. 7 or less is used as the material of the bearing ring, the projections of the surface roughness become large due to the press working, the sound becomes poor, and the projections become a stress concentration source, and the life is shortened. Will drop.

As described above, it is possible to obtain an orbital ring having a good pressed surface roughness, thereby alleviating the concentration of the intermediate portion acting on the roughness projection, and having a long life and excellent acoustic characteristics. It is possible to obtain shaped needle roller bearings.

As described above, the shell-type needle roller bearing of the present invention, which has a long life and excellent acoustic characteristics, can be used for a T / M of an automobile, a compressor of a car cooler, a machine tool,
For applications requiring long life and low noise, such as office machines,
It can be suitably used.

[0016]

Embodiments of the present invention will be described below. SAE1010, which is a commonly used low carbon steel material, was used as the material of the raceway of the shell-type needle roller bearing according to one embodiment of the present invention. The bearing name number is DB503504C, and as shown in Table 1 below, five types of hoop materials having different crystal grain sizes are used, and press working is performed by a normal press working line for manufacturing a raceway. The wheel was manufactured. In addition,
Table 2 below shows the specifications of the needle roller used in combination with the bearing ring.

[0017]

[Table 1]

[0018]

[Table 2]

Thereafter, the carbonized, quenched, and tempered treatments are simultaneously performed on the compact obtained by press working,
The race was completed by barrel processing. here,
The crystal grain size and the average roughness of the raw material before press working and the crystal grain size and the average roughness of the raceway after the press working were examined, respectively. The result is shown in FIG. As is apparent from FIG. 1, the material has almost the same roughness (Ra = 0.06 to 0.07) regardless of the crystal grain size.
(about μm) is obtained, but in the pressed bearing ring, the roughness becomes large as a whole, and particularly, the larger the crystal grain size is, the larger the roughness is, and it is remarkably large when the crystal grain size is about 7 or less.

From these results, it can be seen that the orbital grain size No.
It can be understood that the surface roughness of the press-processed bearing ring can be significantly reduced by setting the ratio to 8 or more. Next, the SU obtained in the above Table 2 was added to the bearing ring thus obtained.
A needle roller and a cage of the same lot manufactured by J2 were incorporated, and five kinds of test bearings were manufactured.

For these test bearings, a life test was performed using the test machine shown in FIG. 2 under the following test conditions.
That is, test bearings 2 a and 2 b were mounted on the rotating shaft 1, a load was applied by the load bearing 3, and the rotating shaft 1 was rotated by the pulley 4. The life was defined as the time when scaly damage called flaking occurred on the raceway surfaces of the test bearings 2a and 2b. Oil lubrication is oil bath lubrication up to the center height of the rotating shaft. As a quantitative evaluation of life, weibull distribution L ₁₀
The service life was determined and compared. The test was performed on ten test bearings for each crystal grain size.

Load: 606 kgf (P / C = 0.3) Revolution: 10,000 rpm Temperature: Oil temperature 100 ° C. Lubricating oil: Daphne Hermetic Oil PS The test results are shown in FIG. From the results shown in FIG. 3, it can be seen that the larger the crystal grain size No (the finer the crystal grain size), the better the roughness and the longer the life.

Next, the test bearing was subjected to an acoustic test. FIG. 4 shows a test apparatus for an acoustic test. The acoustic test
A test bearing 12 is loaded on the rotating shaft 11 with a load of 2 kgf, the rotating shaft 11 is rotated at 1800 rpm, and a sound pressure level is measured by a microphone 13 arranged at a position of 100 mm at an inclination angle of 45 ° from the axial direction. It was done by doing. FIG. 5 shows the test results. In addition, the test was performed about three test bearings about each crystal grain size, and the dispersion of all data was shown. The test was performed in a silent room.

From the test results shown in FIG. 4, in the acoustic test as well, as with the life test results, the larger the crystal grain size No., the better the result is obtained. You can see that it is at the level.

[0025]

As described above, according to the present invention,
By setting the crystal grain size to JIS No. 8 or more, it is possible to obtain a raceway with good roughness on the pressed surface. It is possible to provide a shell-type needle roller bearing having excellent characteristics.

[Brief description of the drawings]

FIG. 1 shows the relationship between the crystal grain size and the average roughness before and after pressing.

FIG. 2 is a configuration diagram of a life tester.

[3] The life test results of the test machine of FIG. 2 have the meanings indicated in L ₁₀ life, the relationship of the grain size of the magnitude and L ₁₀ life.

FIG. 4 is a configuration diagram of an acoustic test apparatus.

FIG. 5 shows the results of an acoustic test performed by the test apparatus shown in FIG. 4, showing the relationship between the crystal grain size and the sound pressure level.

[Explanation of symbols]

 Reference numerals 1, 11: rotating shafts 2a, 2b, 12: test bearings 3: load bearings 4: pulleys 13: microphones

Claims (1)

[Claims] 1. A shell-type needle roller bearing having a bearing ring formed by pressing a low-carbon steel material, wherein the raceway surface of the bearing ring has a grain size of JIS.
A shell type needle roller bearing characterized by being No. 8 or more.