JP2016027273A - Rolling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling device which has a coating of zinc phosphate chemical treatment film applied onto the surface of each rolling element having rolling contact with inner and outer members, and of which a cage contains a solid lubricant, capable of suppressing seizure and wear because the solid lubricant the cage contains transfers and adheres onto the phosphoric acid chemical treatment film on the surface of the rolling element and acts as a lubricant under the conditions that a fluid lubricant is not used (in the atmosphere or vacuum).SOLUTION: The rolling device includes the inner member, the outer member, the rolling elements, and the cage for holding the rolling elements. The phosphoric acid chemical treatment film is formed on the surface of the rolling elements, and the cage contains the solid lubricant.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rolling device such as a rolling bearing, a ball screw, and a linear guide, and is suitable for use in machinery, equipment, and the like that are operated and operated in the atmosphere or vacuum without using a fluid lubricant.

  In rolling devices such as general rolling bearings, ball screws, and linear guides, a lubricant such as grease is supplied between the inner member, the outer member, and the rolling elements and the cage. The rolling friction and sliding friction generated during this period are reduced, and the durability of the rolling device is improved.

  By the way, when the rolling device is used in a vacuum of a space device or the like, a lubricant having a high vapor pressure such as grease evaporates in the atmosphere and cannot be used. Further, when the rolling device is used in an environment where the vapor of the lubricant becomes a problem, a fluid lubricant such as grease cannot be used. Therefore, a rolling lubricant used in such an environment requires a solid lubricant having a low vapor pressure.

  As a rolling device that does not use a fluid lubricant as described above, for example, Patent Document 1 proposes a rolling bearing in which a lubricating film made of PTFE telomer having a specific molecular weight range is formed at least on the surface of a rolling element.

Japanese Patent Laid-Open No. 5-1718

  However, in the rolling bearing of Patent Document 1, PTFE telomer is a soft substance, and when the rolling element film is used, the durability of the rolling bearing has room for improvement because the durability of the film itself is low.

  The present invention has been made in view of the above circumstances, and its purpose is to coat the rolling element surface that is in rolling contact with the inner and outer members with a phosphoric acid-based chemical conversion treatment film, and the cage is a solid lubricant. Is contained. For this reason, the solid lubricant contained in the cage is transferred to the phosphoric acid-based chemical conversion film on the surface of the rolling element and acts as a lubricant under conditions where no fluid lubricant is used (in the atmosphere, in a vacuum, etc.). An object of the present invention is to provide a rolling device that can suppress seizure and wear.

The above object of the present invention can be achieved by the following constitution.
In a rolling device having an inner member, an outer member, a rolling element, and a cage for holding the rolling element, a phosphoric acid-based chemical conversion coating is formed on the surface of the rolling element, and the cage is solid lubricated. It contains an agent. The phosphoric acid-based chemical conversion treatment film is preferably a zinc phosphate film. The solid lubricant preferably contains molybdenum disulfide and PTFE.

  In the rolling device of the present invention, the solid lubricant contained in the cage is lubricated with respect to the phosphoric acid-based chemical coating on the surface of the rolling element under conditions where no fluid lubricant is used (in the atmosphere, in a vacuum, etc.) Since it acts as an agent, seizure and wear can be suppressed.

It is sectional drawing which shows the structure of the thrust ball bearing of the rolling bearing which is one Embodiment of the rolling device of this invention. It is a graph of the rotation test result of an Example and a comparative example.

  Hereinafter, embodiments of a rolling device according to the present invention will be described with reference to the drawings.

<Embodiment>
FIG. 1 is a partial longitudinal sectional view showing a structure of a thrust ball bearing of a rolling bearing, which is an embodiment of the rolling device of the present invention. This ball bearing 1 includes an inner ring as an inner member 2, an outer ring as an outer member 3, and a plurality of rolling elements disposed between the inner member 2 and the outer member 3 so as to be freely rollable. A ball as the moving body 4 and a cage 5 that holds a plurality of rolling elements so as to roll freely are provided. In addition, a phosphoric acid-based chemical conversion coating (not shown) is formed on the surface of the rolling element 4, and the cage is a cage containing a solid lubricant. The phosphoric acid-based chemical conversion treatment film is preferably a zinc phosphate film. The solid lubricant is preferably composed of at least one of molybdenum disulfide, graphite, and PTFE. Further, it is more preferable that the solid lubricant contains PTFE and molybdenum disulfide. When both PTFE and molybdenum disulfide are used, it is preferable to contain more PTFE than molybdenum disulfide in order to achieve both lubricity and wear resistance. In order to improve the strength of the cage, the cage preferably contains glass fiber.

  Moreover, it is preferable that the inner member 2 and the outer member 3 consist of steel materials, and it is preferable that the rolling element has the phosphoric acid type | system | group chemical conversion treatment film formed in the steel materials.

Moreover, the following test bearings were used, and the rotation test was performed on the following test conditions, and the lifetime of the rolling bearing as a rolling device was evaluated. Table 1 shows the rolling element materials and coatings of the single-row thrust ball bearings of the examples and comparative examples, the cage material and the type of solid lubricant, and the test results. In Example 1 and Comparative Examples 1 to 3, a solid lubricant PTFE was used as a main material of the cage, and a solid lubricant MoS ₂ was also contained. At that time, the MoS ₂ content was 5% by mass of the entire cage, the PTFE content was 80% by mass of the entire cage, and the glass fiber content was 15% by mass of the entire cage. Moreover, in Example 1 and Comparative Example 4, the thickness of the zinc phosphate coating was 1 to 2 μm. In the rotation test, the total number of rotations until the bearing vibration acceleration reached a constant value was regarded as the life, and the wear depth of the raceway surfaces of the bearing inner and outer rings was measured after the test.

Test bearing: Thrust ball bearing Bearing dimensions: Inner diameter φ25 x Outer diameter φ52 (Single row thrust ball bearing)
Bearing ring material: SUS440C
Diameter: 3/8 inch
Rotational speed: 1000 min ^-1
Load: 1176N
Test atmosphere: Air temperature: Room temperature

While the bearing using the rolling element coated with the MoS ₂ coating or DLC coating formed by shot peening treatment of the solid lubricant shown in the comparative example has a short life, the rolling element shown in Example 1 It was confirmed that bearings coated with the steel material by zinc phosphate conversion treatment and containing more PTFE as a solid lubricant than MoS ₂ in the cage significantly increased the life (test is 4500 x 10 ⁴ rotations) Censored). This is because the solid lubricant of the cage is transferred to the zinc phosphate coating on the surface of the rolling element to improve lubrication and suppress wear of the bearing. Further, it can be said that the bearing of Comparative Example 4 had a short life because the cage did not contain a solid lubricant.

  Further, test bearings of Comparative Examples 5 and 6 in which only the material of the cage was changed from Example 1 in Table 1 were prepared, and a rotation test was performed under the same test conditions as in Table 1. The material and life of the cage are shown in Table 2. In addition, Example 1 and Comparative Example 4 are the same as Table 1, and are described again for comparison with Comparative Examples 5 and 6.

Bearings using MC nylon or POM resin for the cages shown in Comparative Examples 5 and 6 in Table 2 are non-lubricated, the temperature of the contact portion between the rolling element and the cage is increased, and a resin having a low melting point is used. It melted from the surface and transferred to the raceway, and the vibration of the bearing increased. The bearing of Example 1, which contains MoS ₂ in PTFE, has a low coefficient of friction and thus generates less heat. Further, the melting point of PTFE was 326 ° C., and it was confirmed that the life of the bearing of Example 1 using the PTFE cage having a melting point of 100 ° C. or higher was significantly extended as compared with the resin having a low melting point.

  As described above, in the rolling device of the present invention, the solid lubricant contained in the cage is added to the phosphoric acid-based chemical film on the surface of the rolling element under conditions where no fluid lubricant is used (in the atmosphere, in a vacuum, etc.). Since it transfers and acts as a lubricant, seizure and wear can be suppressed.

  The above-described embodiments show examples of the present invention, and the present invention is not limited to these embodiments.

DESCRIPTION OF SYMBOLS 1 Rolling device 2 Inner member 3 Outer member 4 Rolling body 5 Cage

Claims (3)

  In a rolling device having an inner member, an outer member, a rolling element, and a cage for holding the rolling element, a phosphoric acid-based chemical conversion coating is formed on the surface of the rolling element, and the cage is solid lubricated. A rolling device comprising an agent.   The rolling device according to claim 1, wherein the phosphoric acid-based chemical conversion coating is a zinc phosphate coating.   The rolling device according to claim 1 or 2, wherein the solid lubricant contains two kinds of molybdenum disulfide and PTFE.

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