JP2009115187A - Rolling member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an abrasion resistance and a friction characteristic by avoiding generation of regions thin in oil film thickness at both ends with which a rolling member rollingly contacts, and by obtaining a sufficient oil film thickness in a contact part as a whole with which the rolling member rollingly contacts. <P>SOLUTION: The oil film thickness after elastic deformation is increased by a depth of a groove 5 in a rolling direction by forming the groove 5 in the rolling direction at the end of at least one contact region with which the rolling member rollingly contacts, so that the contact parts are separated from each other by lubricating oil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mechanical element such as a rolling bearing that realizes friction reduction by a relative motion mainly composed of rolling, and is particularly suitable for operating conditions such as frequent start and stop, swinging motion, or operating conditions such as low speed and high load. The present invention relates to a rolling member.

  In the rolling / sliding contact part of a rolling member such as a rolling bearing, a direct fluid contact is prevented by generating a dynamic pressure effect on the fluid interposed between the objects by the relative movement of the objects to achieve a fluid lubrication state. Friction and wear can be reduced.

  However, when the amount of lubricating oil is small or the speed is low, the dynamic pressure effect is small and it is difficult to form a lubricating oil film, so there is a risk of causing solid contact. Particularly in recent years, low-viscosity lubricating oil has been used to reduce torque, and the amount of lubricating oil supplied from the outside has also decreased. For this reason, the possibility of becoming a solid contact state is further increased.

  Conventionally, even if the amount of lubricating oil in the vicinity of the contact portion is insufficient, lubrication is possible as long as the surface of the contact portion retains the lubricating oil. A technique for retaining oil is disclosed in Patent Document 1. This technique can improve boundary lubrication performance at low speeds.

  Another technique for improving boundary lubrication performance is disclosed in Patent Document 2. In this technique, a fine concavo-convex shape is created on the surface by a short pulse laser, the lubricating oil is adsorbed on the new surface when the convex portion is slightly worn, and the lubricating oil is supplied to the contact surface.

  On the other hand, in a plain bearing, a technique is generally used in which lubricating performance is improved by forming a number of grooves having a depth of about the oil film thickness on a sliding surface. This utilizes the fact that a hydrodynamic dynamic pressure action occurs because the depth of the sliding surface changes due to the presence of the groove. An example in which this effect is applied to a rolling bearing is disclosed in Patent Document 3. The technique disclosed in Patent Document 3 tries to prevent slipping by pressing a rolling element in which slipping occurs against a race ring with a pressure due to a hydrodynamic action because of a light load.

  Further, Non-Patent Document 1 discloses an example in which a deep concave portion is provided in a thrust flat plain bearing that supports high surface pressure. This is intended to improve the boundary lubrication performance by discharging the lubricating oil from the recess accompanying thermal expansion. However, this technique is not intended to generate hydrodynamic dynamic pressure effects.

Japanese Patent Laid-Open No. 02-168021 Japanese Patent Laying-Open No. 2005-32148 JP 2006-105361 A H.Kotera, A.Mori, N.Tagawa, PROPOSAL OF A SEIZURE PREVENTING METHOD IN HEAVILY LOADED SLIDING PAIRS, Synopses of the International Tribology Conference Kobe, 2005, D-04

  In the conventional technique, the amount of lubricating oil supplied to the contact surface is increased by minute unevenness, or the oil film thickness is improved by the dynamic pressure action of minute recesses.

  By the way, as shown in FIG. 7, the oil film thickness of the contact surface under the elastohydrodynamic lubrication (EHL) condition has a horseshoe-shaped thin region with respect to the oil film thickness of the central portion at both ends of the contact portion that is in rolling contact. . In the vicinity of the region where the oil film thickness is thin, the pressure of the oil film becomes low, so that sufficient elastic deformation cannot be obtained at the contact portion that makes rolling contact. Therefore, when the oil film thickness in this thin region is less than the maximum value of the surface roughness, metal contact is partially generated.

  In view of this, the present invention provides a technique for obtaining a sufficient oil film thickness in the entire contact portion that is in rolling contact by preventing a region having a thin oil film thickness from occurring at both ends of the contact portion that is in contact with rolling. It is a subject.

  In the present invention, a rolling direction groove is provided at the end of the contact region of at least one member of the rolling contact.

  At the end of the contact area of the rolling contact member, an area with a thin oil film thickness is likely to occur, but if a groove in the rolling direction is provided in this area, the oil film thickness after elastic deformation increases by the depth of this groove. In addition, the contact portion can be separated with the lubricating oil.

Examples of rolling members to which the present invention can be applied include ball bearings having balls and race rings, thrust roller bearings having rollers and raceways.
In the case of a ball bearing, a rolling direction groove is provided at the end of at least one member of a contact ellipse indicating the contact area between the ball and the race. Moreover, you may make it provide a rolling direction groove | channel only in an inner raceway among an inner and outer raceway.

  In the case of a thrust roller bearing, a rolling direction groove is provided at the end of the contact area of the roller with respect to the washer, or a rolling direction groove is provided at the end of the contact area of the washer with respect to the roller.

  According to the elastohydrodynamic lubrication (EHL) analysis, the depth of the rolling direction groove is preferably 15 to 30% of the oil film thickness at the center of the contact area in rolling contact. For example, as shown in FIG. 8, when rolling direction grooves are formed at both ends of the contact portion of the ball, according to elastohydrodynamic lubrication (EHL) analysis, as shown in FIGS. Oil film can be obtained. In FIG. 8, x represents the rolling direction, y represents the direction orthogonal to the rolling direction, and z represents the direction of the oil film thickness. 9 shows a case where no rolling direction groove is provided, FIG. 10 shows a case where the groove depth is 15% with respect to the central oil film thickness, and FIG. 11 shows a groove depth relative to the central oil film thickness. When the thickness is 30%, FIG. 12 is a case where the groove depth is 60% with respect to the central oil film thickness, and the groove depth is 15% to 30% with respect to the central oil film thickness. %, The minimum oil film thickness increases, and when the groove depth is 60% of the central oil film thickness, the minimum oil film thickness decreases. Therefore, the depth of the groove is preferably 15% to 30% with respect to the central oil film thickness.

  This is because when the groove is shallow, pressure is also generated in the groove, and the elastic deformation is about the same as when there is no groove. On the other hand, when a deep groove is provided, no oil film pressure is generated in the groove, so that the contact area that substantially supports the load decreases, and the minimum oil film thickness decreases. It is thought to do.

  As a method of processing the rolling direction groove, laser processing, etching, electric discharge processing, microblasting, or the like can be considered. Among these, etching, electric discharge machining, and microblasting are difficult to accurately machine a metal surface with a depth of 0.1 μm or less. Etching and microblasting also require the creation of a mask. On the other hand, laser processing can be performed with high accuracy even with a shape with a depth of 0.1 μm or less without creating a mask or the like by using NC control. Processing is preferred.

  As described above, the rolling member according to the present invention can increase the lubricating oil film thickness at the minimum film thickness portion even in the case of a high load or a low speed at which the oil film becomes thin, and direct contact between solids is possible. Since it can prevent, abrasion resistance and a friction characteristic improve.

FIG. 1 shows an example in which the present invention is applied to a ball bearing in which a ball 3 is inserted between an inner ring 1 and an outer ring 2.
In the example of FIG. 1, the rolling direction grooves 5 are provided in the region where the ball 3 is in contact with the inner ring 1 and the outer ring 2, at both ends of the contact ellipse indicated by reference numeral 4 in FIG. 1. Although the rolling direction groove 5 is provided in both the inner ring 1 and the outer ring 2, it may be provided only in the inner ring 1 that is more severely lubricated.

Next, FIG. 2 shows an example in which the present invention is applied to an angular ball bearing in which the ball 3 is in contact with the inner ring 1 and the outer ring 2 at a non-zero contact angle.
In the angular ball bearing, since the contact angle is determined, the position of the contact ellipse 4 is roughly determined inside the raceway, so that the present invention can be more easily applied. And since the magnitude | size of the contact ellipse 4 is calculated | required from the largest load assumed at the time of use, what is necessary is just to provide the rolling direction groove | channel 5 in the both ends of the major axis of the contact ellipse 4. FIG. Although the rolling direction groove 5 is provided in both the inner ring 1 and the outer ring 2, it may be provided only in the inner ring 1 that is more severely lubricated.

Next, FIG. 3 and FIG. 4 show an example in which the present invention is applied to a thrust roller bearing having a structure in which a cylindrical roller 8 with a cage 7 is arranged between a pair of raceway discs 6.
In the case of a thrust roller bearing, the present invention is particularly effective because slippage increases at both ends of the effective length and the oil film decreases. Although the rolling direction groove 5 can be provided in the roller 8, it is desirable to provide it in the washer 6 from the viewpoint of manufacturing efficiency.

Next, FIGS. 5 and 6 show an example in which the present invention is applied to a radial roller bearing. FIG. 5 shows a type in which the roller 9 is guided by the collar of the inner ring 10, and FIG. 6 shows a type in which the roller 9 is guided by the collar of the outer ring 11.
5 shows an example in which the rolling direction grooves 5 are provided at both ends of the effective length of the roller 9, and FIG. 6 shows an example in which the rolling direction grooves 5 are provided in the inner ring 10 having no flange.
5 and 6 show an example in which the present invention is applied to a radial roller bearing. However, the present invention can be similarly applied to a tapered roller bearing and a self-aligning roller bearing.

It is the schematic which shows the example which applied this invention to the ball bearing. It is the schematic which shows the example which applied this invention to the angular ball bearing. It is the schematic which shows the example which applied this invention to the thrust roller bearing. FIG. 4 is a partially enlarged longitudinal sectional view of FIG. 3. It is the schematic which shows the example which applied this invention to the radial roller bearing of the type which guides a roller with the collar of an inner ring | wheel. It is the schematic which shows the example which applied this invention to the radial roller bearing of the type which guides a roller with the collar of an outer ring | wheel. It is the figure which represented typically the oil film thickness formed in the contact area | region of a rolling member on elastohydrodynamic lubrication (EHL) conditions. Explanatory drawing which shows the example which formed the rolling direction groove | channel in the both ends of the contact part of a ball | bowl. The figure which shows the oil film thickness formed in the contact area | region of a rolling member when not providing the rolling direction groove | channel 5 with the explanatory drawing of FIG. The figure which shows the oil film thickness formed in the contact area | region of a rolling member when the depth of the rolling direction groove | channel 5 is 15% with respect to the center oil film thickness in explanatory drawing of FIG. The figure which shows the oil film thickness formed in the contact area | region of a rolling member when the depth of the rolling direction groove | channel 5 is 30% with respect to the center oil film thickness in explanatory drawing of FIG. The figure which shows the oil film thickness formed in the contact area | region of a rolling member when the depth of the rolling direction groove | channel 5 is 60% with respect to the center oil film thickness in explanatory drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Ball 4 Contact ellipse 5 Rolling direction groove 6 Bearing disc 7 Cage 8 Roller 9 Roller 10 Inner ring 11 Outer ring

Claims (12)

  The rolling member is a rolling bearing comprising a rolling element and a raceway, or a rolling element and a pair of washer disks. A rolling member provided with a direction groove.   A rolling member, wherein the rolling member is a radial ball bearing having balls and inner and outer races, and a rolling direction groove is provided at an end of a contact region of at least one of the balls and races.   The rolling member according to claim 2, wherein a rolling direction groove is provided only in the inner raceway among the inner and outer raceways.   A rolling member, wherein the rolling member is a thrust ball bearing having a ball and a pair of washer, and a rolling direction groove is provided at an end of at least one contact area between the ball and the washer.   The rolling member according to claim 4, wherein a rolling direction groove is provided in the bearing disc.   A rolling member, wherein the rolling member is a radial roller bearing having a roller and inner and outer races, and a rolling direction groove is provided at an end of a contact region of at least one of the roller and the race.   7. The rolling member according to claim 6, wherein a rolling direction groove is provided only in the inner raceway among the inner and outer races.   A rolling member, wherein the rolling member is a thrust roller bearing having a roller and a washer, and a rolling direction groove is provided at an end of at least one contact region of the washer.   The rolling member according to claim 8, wherein a rolling direction groove is provided in the bearing disc.   9. The rolling member according to claim 8, wherein a rolling direction groove is provided in an inner washer among inner and outer washer contacting with a roller.   The rolling member according to any one of claims 1 to 10, wherein a depth of the rolling direction groove is 15 to 30% of an oil film thickness at a central portion of a contact region in rolling contact.   The rolling member according to any one of claims 1 to 11, wherein the rolling direction groove is formed by laser processing.

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