JP2006083965A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute a cage used for a rolling bearing by materials generating low friction by sliding contact with respect to a rolling element and having excellent heat transfer properties. <P>SOLUTION: This rolling bearing is provided with an inner ring 14 rotatably supporting a rotational shaft 12, an outer ring 16 arranged outside the inner ring 14, the cage 18 made of synthetic resin for connecting the inner ring 14 with the outer ring 16, and a ball 20 rotatably fitted between the inner ring 14 and the outer ring 16. The cage 18 comprises a composite material in which either a carbon nano tube, carbon nano hone or carbon nano fiber is uniformly dispersed in resin such as phenolic resin and PEEK resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling bearing, and more particularly, to a rolling bearing that rotatably supports a rotating shaft and rotates under a load in an axial direction or a radial direction.

  Examples of rolling bearings include an inner ring that rotatably supports a rotating shaft, an outer ring that is disposed on the outer peripheral side of the inner ring, a cage that connects the inner ring and the outer ring, and a rotatable structure between the inner ring and the outer ring. There are known rolling elements that are mounted and that rotate in response to axial or radial loads. This type of rolling bearing is adapted to be guided to an inner ring or an outer ring while sliding and contacting a pocket surface of a cage during operation while storing balls or rollers as rolling elements. At this time, since it rotates in response to a load in the axial direction or radial direction, it is desirable that the cage of the rolling bearing that rotates at a high speed is light and has a low friction of sliding contact. In pump bearings that are immersed in a low-viscosity fluid, high-speed internal gearbox bearings such as high-speed main bearings and tower shaft bearings in jet engines and gas turbine engines, Since it is necessary to efficiently propagate the lubricant to the oil and discharge it to the outside of the bearing, it is desirable that the cage used for these bearings has a good heat transfer characteristic.

  For this reason, in consideration of the need for mechanical strength that can withstand centrifugal force at high speeds as well as conventional cages used in high-speed rotating bearings, it is necessary to improve heat transfer characteristics. For example, nickel chrome molybdenum steel (JIS: SNCM439, AMS6414) is used as the material of the cage. The nickel chrome molybdenum steel is tempered and heat-treated and then machined. A configuration in which plating or phosphoric acid coating treatment is performed is employed.

  However, the structure in which the surface of the cage is subjected to silver plating or phosphoric acid coating treatment increases the processing cost of the cage, which increases the cost of the entire bearing. For this reason, there is a demand for materials that can keep the friction and wear of the sliding contact surface between the rolling element and the cage low, and the most suitable surface treatment method for that material, and in order to suppress centrifugal force at high speed, There has been a need for a lightweight and high strength cage material.

In JP 2004-132507 A, in order to provide a rolling bearing suitable for automobile electrical parts, engine accessories, etc., having excellent seizure resistance even at a high temperature close to 200 ° C. A plurality of rolling elements are movably held by a cage between the rings, and contain at least one of carbon black and carbon nanotubes in a ratio of 1 to 40% by volume, and are specified as a thickener. Although a rolling bearing in which grease containing a diurea compound is enclosed is disclosed, there is no disclosure that the cage is composed of a material in which carbon nanotubes are dispersed in a base resin.
JP 2004-132507 A

  Therefore, conventionally, lightweight alloys such as magnesium alloy and aluminum alloy have been used as the cage material, but the former has insufficient wear resistance on the sliding contact surface between the ball and the pocket surface of the cage. However, the latter has insufficient tensile strength and wear resistance when rotated at high speed. In addition, engineering plastics such as PEEK materials and VESPEL materials have been used, but these materials are not sufficient in strength. When carbon fiber reinforced plastic was used, the strength was improved, but it was not satisfactory in terms of cost effectiveness.

  An object of the present invention is to configure a cage used for a rolling bearing having a low heat friction due to sliding contact with a rolling element and a good heat transfer characteristic.

  In order to solve the above problems, the present invention provides an inner ring that rotatably supports a rotating shaft, an outer ring that is disposed on the outer peripheral side of the inner ring with a space between the inner ring, and an annular ring that is formed in an annular shape. In a rolling bearing including a synthetic resin cage that connects an inner ring and the outer ring, and a rolling element that is rotatably mounted between the inner ring and the outer ring, the synthetic resin cage includes a carbon nanotube. A rolling bearing comprising any one of carbon nanohorn and carbon nanofiber is configured.

  When the synthetic resin cage is composed of one of carbon nanotubes, carbon nanohorns, or carbon nanofibers, it is configured as a composite material uniformly dispersed in a resin such as phenol resin or PEEK resin. It is desirable to do.

  As the resin, in addition to phenol and PEEK, PPS and PTFE can be used.

  As the carbon nanotube, carbon nanohorn, or carbon nanofiber, it is desirable to use a carbon nanotube having a diameter of 0.5 to 10 nm, a length of 0.5 to 60 μm, and a content of 5 to 45% by weight.

  As the fluororesin (PTFE), a fluorinated type is desirable.

  Further, it is not only good at high temperature and high speed with little wear, but also suitable for rolling bearings such as LNG pumps and liquid nitrogen pumps as low temperature side bearings.

When forming a composite material in which any one of carbon nanotubes, carbon nanohorns, or carbon nanofibers is uniformly dispersed in a resin, a solid lubricant such as M _{2 O 2} may be contained (kneaded). .

  When carbon nanotubes, carbon nanohorns or carbon nanofibers are used as the material of the synthetic resin cage, the heat conduction characteristics are improved, and the temperature of the entire cage becomes uniform immediately during use and molding, No extra distortion will occur. In particular, at the time of molding, the temperature of each part of the cage is uniform, so that the characteristic sink marks at the time of injection molding and the like are reduced, and the dimensional stability after molding becomes very good. In addition, the strength is increased and the friction reduction effect can be enhanced.

  According to the present invention, it is possible to improve frictional wear characteristics and thermal conductivity.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an essential part of a rolling bearing showing an embodiment of the present invention. In FIG. 1, a rolling bearing (ball bearing) 10 includes an inner ring 14 that rotatably supports a rotating shaft 12, an outer ring 16 that is disposed on the outer peripheral side of the inner ring leaving a gap between the inner ring 14, and an annular shape. As a rolling element that is formed and is rotatably mounted between a synthetic resin cage 18 that connects the inner ring 14 and the outer ring 16, and a spherical recess 14 a of the inner ring 14 and a spherical recess 16 a of the outer ring 16. When the rotary shaft 12 rotates, it receives a load in an axial direction or a radial direction and rotates.

  When the rolling bearing 10 was constructed, a composite material in which multi-walled carbon nanotubes were uniformly dispersed in a phenol resin or a PEEK resin was used as a material for the cage 18.

  As a composite material of the cage 18, in Example 1, the content of multi-walled carbon nanotubes is 10% by weight and the remainder is phenol resin, and in Example 2, the content of multi-walled carbon nanofibers is 5% by weight and the remaining is In Example 3, the content of single-walled carbon nanotubes was 10% by weight, and the remainder was a resin formed by laminating PEEK resin sheets distributed in one direction.

  On the other hand, as Comparative Example 1, a PEEK resin containing a fluororesin and reinforced with carbon fiber was used.

  Further, in the same manner as the cages 18 of Examples 1 to 3 and Comparative Example 1, an outer diameter of 45 mm, an inner diameter of 8 mm, a thickness of 5 mm, and a surface roughness of 0. Each of 6 μm Ra was prepared.

  When performing a high-temperature / high-speed wear test using ring-shaped test pieces constructed in exactly the same manner as the cages 18 of Examples 1 to 3 and Comparative Example 1, a friction tester 22 shown in FIG. 2 was used. The friction tester 22 includes a base 24, a load cell 26, and a rotating test piece 28. The rotating test piece 28 is rotatably fixed to a rotating shaft 30 arranged in a horizontal direction. ing.

  The friction tester 22 rotates the rotating test piece 28 at a rotational speed of 19000 rpm when the ring-shaped test pieces of Examples 1, 2, 3 and Comparative Example 1 are sequentially attached to the base 24 as the fixed side test piece 32. The base 24 is pressed against the fixed-side test piece 32 with the test load F, and the load (friction force) is measured by the load cell 26. At this time, the lubricating oil at 120 ° C. is jetted from the oil jet 34 to the contact portion between the fixed-side test piece 32 and the rotating test piece 28 at a rate of 0.2 l / min.

  The rotating test piece 28 is a heat-resistant steel M50 having an outer diameter of 100 mm, an inner diameter of 30 mm, a thickness of 5 mm, and a surface roughness of 0.02 μmRa. Went.

摩擦試験機２２を用いて高温・高速磨耗試験を行い、実施例１、２、３および比較例１のリング状試験片（固定側試験片）３２について磨耗痕跡をロードセル２６で測定したところ、次の表２に示すような結果が得られた。

A high-temperature and high-speed wear test was performed using the friction tester 22, and the wear traces of the ring-shaped test pieces (fixed side test pieces) 32 of Examples 1, 2, 3 and Comparative Example 1 were measured with the load cell 26. The results as shown in Table 2 were obtained.

表２に示す試験結果から、実施例１〜３のものは、従来のＰＥＥＫ樹脂を用いた比較例１のものよりも熱伝導率が大きくなり、改善されたことが分かる。さらに、磨耗痕跡の幅も比較例１のものよりも小さくなり、改善されたことが分かる。

From the test results shown in Table 2, it can be seen that the samples of Examples 1 to 3 have improved thermal conductivity as compared with those of Comparative Example 1 using a conventional PEEK resin. Furthermore, it can be seen that the width of the wear trace was also smaller than that of Comparative Example 1 and improved.

  In this embodiment, the lubrication conditions are dilute, such as pump bearings immersed in a low-viscosity fluid, high-speed main bearings such as jet engines and gas turbine engines, and relatively high-speed internal gearbox bearings such as tower shaft bearings. When the bearing used in the invention is constructed, the bearing ring including the inner ring 14 and the outer ring 16 is made of bearing steel, the composite material of Examples 1 to 3 is used as the material of the cage 18, and the ball as a rolling element 20 is composed of a ceramic material such as silicon nitride, so that the lubrication between the ball 20 and the bearing ring is insufficient, and wear / damage under boundary lubrication where the portion where the bearing ring and the ball 20 are in direct contact increases. Even under such operating conditions, wear and damage can be prevented.

  In addition, rolling bearings that support high-speed rotation of pump main shafts that transport fluids such as fuel oil and refrigerants such as CFCs and fluids at extremely low temperatures (around -250 ° C), high-speed main bearings for jet engines and gas turbine engines, By applying the present invention to a relatively high-speed internal gearbox bearing such as a tower shaft bearing, which is used under lean lubrication conditions, it is possible to improve frictional wear characteristics. In addition, even if the present invention is applied to the one that is operated at a high speed without using a lubricant, it is possible to prevent the contact portion between the pocket surface of the cage and the raceway from being damaged, The heat generated inside the bearing can be immediately discharged to the outside, and the thermal conductivity can be improved.

  Moreover, the rigidity of the holder | retainer 18 can be improved by mixing a ceramic fine powder in the resin material of Examples 1-3.

  In the above-described embodiment, the carbon nanotube is used as the composite material of the cage 18. However, in addition to the carbon nanotube, carbon nanohorn or carbon nanofiber can also be used.

It is a principal part longitudinal cross-sectional view of the rolling bearing which shows one Example of this invention. It is a block diagram of a friction tester.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rolling bearing 12 Rotating shaft 14 Inner ring 16 Outer ring 18 Cage 20 Ball 22 Friction tester 24 Base stand 26 Load cell 28 Rotating test piece 32 Fixed side test piece

Claims (1)

An inner ring that rotatably supports the rotating shaft, an outer ring that is disposed on the outer peripheral side of the inner ring with a space between the inner ring, and a synthetic resin holding that is formed in an annular shape and connects the inner ring and the outer ring In a rolling bearing provided with a roller and a rolling element rotatably mounted between the inner ring and the outer ring,
The synthetic resin cage contains any one of carbon nanotubes, carbon nanohorns, and carbon nanofibers.

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