JP2009108963A - Rolling member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve lubricating performance of a contact part rollingly contacting. <P>SOLUTION: Grooves 2 having a finite length equivalent to a width in a direction perpendicular to a rolling direction in contact areas are juxtaposed along the rolling direction in one of the contact areas of a member rollingly contacting, thereby, lubricating oil on the contact part is retained in the grooves 2 and is less likely to flow out. Accordingly, the dynamic pressure action of the lubricating oil is generated in the contact part, and the contact part is reliably separated by the 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 when the speed is low, the dynamic pressure effect is small and the lubricating oil film is not formed, and 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 prior art, by providing a large number of grooves on the contact surface, a dynamic pressure action and a lubricating oil retaining effect are generated to improve the lubricating performance.
However, if the length of the groove is increased, the lubricating oil flows out of the contact area along the groove, so that sufficient dynamic pressure action and lubricating oil retention effect cannot be obtained, and the expected lubrication performance. Improvement may not be seen.

  Accordingly, an object of the present invention is to improve the lubrication performance of a contact portion that makes rolling contact.

  According to the present invention, grooves having a length corresponding to the width in a direction perpendicular to the rolling direction of the contact area are arranged in one of the contact areas of the members that are in rolling contact along the rolling direction.

  In FIG.1 and FIG.2, the groove | channel 2 (y direction) is provided in the contact part of the member 1 which rolls. The groove 2 is provided in a member that relatively rolls, and the direction thereof is provided to be orthogonal to the rolling direction (x direction). As shown in FIG. 1, the length of the groove 2 is formed to a finite length corresponding to the width of the contact area of the member that makes rolling contact. As shown in FIG. 2, the grooves 2 may be provided in two rows at the center of the contact area. As shown in FIG. 2, when the grooves 2 are divided into two rows at the center, the lubricating oil is more effectively replenished at the end of the contact area where the oil film thickness is thin and solid contact is likely to occur. 1 and 2, the z direction indicates the direction of dynamic pressure generated at the contact portion.

  If a lubricating oil storage pocket deeper than the groove 2 is provided between the grooves 2 arranged along the rolling direction, the lubricating oil is more easily replenished from the deep lubricating oil storage pocket.

  Examples of rolling members to which the present invention can be applied include radial ball bearings having balls and raceways, thrust ball bearings having balls and raceways, and thrust roller bearings having rollers and raceways.

  As a method of processing the grooves arranged along the rolling direction, for example, there is etching. Etching requires a mask to protect portions that do not require processing, but a large number of grooves having submicron-order depths can be formed on the metal surface in a single process. Further, if NC control is used in laser processing, a groove having a depth of 0.1 μm or less can be processed without producing a mask or the like.

  As described above, in the rolling member according to the present invention, even when the lubricating oil in the contact portion is insufficient, the dynamic pressure action by the lubricating oil is generated by the groove having a finite length corresponding to the width of the contact area of the contact portion. It is easy and the contact part can be separated with lubricating oil, improving wear resistance and friction characteristics.

FIG. 3 shows an example in which the present invention is applied to a deep groove ball bearing in which a ball 5 is inserted between an inner ring 3 and an outer ring 4.
In the example of FIG. 3, a groove 2 having a length corresponding to the length of the major axis of the contact ellipse indicated by reference numeral 6 in FIG. 3 is provided on both the outer ring 4 and the outer ring 4, but it may be provided only on the inner ring 3 that is more rigorously lubricated.

Next, FIG. 4 shows an example in which the present invention is applied to an angular ball bearing in which the contact angle between the ball 5 and the inner ring 3 / outer ring 4 is not zero.
In the angular ball bearing, since the contact angle is determined, the position of the contact ellipse 6 is roughly determined inside the track, so that the present invention can be more easily applied. And since the magnitude | size of the contact ellipse 6 is calculated | required from the largest load assumed at the time of use, what is necessary is just to provide the groove | channel 2 equivalent to the length of the major axis of the contact ellipse 6. FIG. Although this groove 2 is provided in both the inner ring 3 and the outer ring 4, it may be provided only in the inner ring 3 that is more severely lubricated.

5 and 6 show an example in which the present invention is applied to a thrust ball bearing in which a ball 5 with a cage 8 is arranged between a set of washer disks 7.
In the example of FIGS. 5 and 6, the region where the ball 5 is in contact with the washer 7, that is, the groove 2 having a length corresponding to the length of the major axis of the contact ellipse indicated by reference numeral 6 in FIG. It is provided on the washer 7. The direction of the grooves 2 aligned along the rolling direction is provided so as to coincide with the rotation axis direction of the balls 5.

Next, FIG. 7 and FIG. 8 show an example in which the present invention is applied to a thrust roller bearing having a structure in which a cylindrical roller 9 with a cage 8 is disposed between a pair of raceways 7.
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 grooves 2 arranged along the rolling direction can be provided on the outer peripheral surface of the roller 9, it is desirable to provide them on the track of the washer 7 from the viewpoint of manufacturing efficiency. The direction of the grooves 2 aligned along the rolling direction is provided so as to coincide with the axial direction of the rollers 9.

Next, FIGS. 9 and 10 show an example in which the present invention is applied to a radial roller bearing. FIG. 9 shows a type in which the roller 10 is guided by the hook of the inner ring 11, and FIG. 10 shows a type in which the roller 10 is guided by the hook of the outer ring 12.
FIG. 9 is an example in which the axial grooves 2 are provided on the surface of the roller 10 so as to be aligned along the rolling direction. FIG. 10 illustrates the rolling of the grooves 2 along the axial direction on the inner ring 11 having no wrinkles. The example provided so that it may rank along a direction is shown.

  9 and 10 show an example in which the present invention is applied to a radial roller bearing, but it can also be applied to a tapered roller bearing and a self-aligning roller bearing in the same manner.

  The above embodiment is an example in which the groove 2 for generating the dynamic pressure action is arranged on the rolling contact surface in the rolling direction to improve the lubrication action. However, the embodiment of FIG. This is an example in which lubricating oil storage pockets 13 deeper than the depth of the groove 2 are scattered on the dynamic pressure generating surface having the groove 2 for generating the above. In FIG. 11, the lubricating oil storage pocket 13 is represented by a black circle.

In the example of FIG. 11, the lubricating oil storage pocket 13 is disposed between the groove 2 and the groove 2, but the positional relationship between the groove 2 and the lubricating oil storage pocket 13 is arbitrary.
For example, the deep lubricating oil storage pockets 13 may be interspersed so as to be arranged in parallel at a predetermined interval in the rolling direction, or may be interspersed in a staggered manner at a predetermined interval in the rolling direction. The lubricating oil discharged from the deep lubricating oil storage pocket 13 moves to the rear in the traveling direction along with the rolling motion. Therefore, when the lubricating oil storage pockets 13 are arranged in parallel at predetermined intervals, the surface of the lubricating oil However, when the lubricating oil storage pockets 13 are arranged in a staggered pattern, the distribution of streaks on the surface of the lubricating oil almost doubles, so that the lubricating oil storage pockets 13 are staggered. It is preferable to arrange them.

  In the example of FIG. 11, the shape of the opening surface of the lubricating oil storage pocket 13 is all circular, but may be an ellipse or a polygon.

  Next, the cross-sectional shape of the groove 2, that is, the bottom surface of the groove does not need to be parallel to the surface and may be inclined. However, since the dynamic pressure action decreases when it is inclined deeper in the direction of fluid flow, as shown in FIGS. 12 and 13, at least the direction of fluid flow (indicated by the arrows in FIGS. 12 and 13). It is desirable to incline so as to be shallow in the direction). In particular, as shown in FIG. 13, if the shape has no shoulder on one side of the groove, it is possible to reduce wear at the time of starting and stopping.

  Next, since the lubricating oil storage pocket 13 deeper than the groove 2 is intended to store lubricating oil, the larger the volume, the better. However, since the dynamic pressure that contributes to the load support is not generated in the lubricating oil at the opening, it is desirable that the opening area is small. Therefore, the lubricating oil storage pocket 13 has a small diameter and a deep hole. Considering the current level of processing technology that can be mass-produced, the size is 20-30 μm in diameter and about 100 μm in depth.

  On the other hand, since the groove 2 is intended to generate dynamic pressure in a minute contact region, it is relatively small with respect to the area of the contact portion, and it is desirable that there are many in the contact surface. Accordingly, assuming a normal rolling contact machine element represented by a rolling bearing, the groove width is set to 20 to 30 μm or less. In the case of a normal dynamic pressure bearing that is used in a state where there is sufficient lubricating oil, the depth of the groove that effectively generates the dynamic pressure action is about the oil film thickness. Expects a dynamic pressure effect under operating conditions where the oil film thickness is not sufficient. In the case of a general rolling bearing, the oil film thickness is at most several μm even when a sufficient oil film is generated. Therefore, the depth of the groove 2 is about 0.1 to 1 μm. The bottom surface of the groove 2 does not necessarily have to be flat, but it is better that the shoulder portion is not bent as much as possible.

  The rolling bearing has a rotational speed of 0 at the start of operation or the dead center of the swinging motion, and gradually reaches a predetermined or maximum rotational speed. Immediately after starting the movement from the speed of 0, no lubricating oil is supplied from the outside, and since the speed of the contact surface is low, an oil film is not formed, and the solids are in contact with each other. When the movement is continued in the contact state, heat is generated due to high friction, and the lubricating oil held in the concave portion of the contact surface expands. The lubricating oil held in the groove 2 is also discharged to the contact surface and is considered to contribute to lubrication. However, in the deep lubricating oil storage pocket 13, a relatively large amount of lubricating oil is generated due to the difference in thermal expansion between the solid and the lubricating oil. It will be discharged onto the contact surface.

When the amount of lubricating oil in the rolling contact portion is extremely small, a dynamic pressure action cannot be generated in the groove 2, but in the present invention, the groove 2 is lubricated by the lubricating oil discharged from the deep lubricating oil storage pocket 13. Since oil is replenished, an oil film due to a dynamic pressure action is easily formed on the rolling contact portion, and the contact surface is separated by the oil film.
Therefore, according to the present invention, solid contact of the contact surface is prevented even under operating conditions at a low speed, and the fluid lubrication state can be maintained.

  In addition, in the case of extremely low speed where oil film formation is essentially difficult, severe solid contact is caused by boundary lubricity due to the lubricating oil discharged mainly from the deep lubricating oil storage pocket 13 due to thermal expansion due to frictional heat. Can be avoided.

Explanatory drawing which shows embodiment of this invention which provided the groove | channel in the member which rolls. Explanatory drawing which shows other embodiment of this invention which provided the groove | channel in the member which rolls. It is the schematic which shows the example which applied this invention to the deep groove 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 ball bearing. FIG. 6 is a partially enlarged longitudinal sectional view of FIG. 5. It is the schematic which shows the example which applied this invention to the thrust roller bearing. FIG. 8 is a partially enlarged longitudinal sectional view of FIG. 7. 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 schematic which shows other embodiment of this invention dotted with the lubricating oil storage pocket. Sectional drawing which shows the shape of a groove shape and a lubricating oil storage pocket. Sectional drawing which shows the groove shape and the other shape of a lubricating oil storage pocket.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling member 2 Groove 3 Inner ring 4 Outer ring 5 Ball 6 Contact ellipse 7 Bearing disk 8 Cage 9 Roller 10 Roller 11 Inner ring 12 Outer ring 13 Lubricant storage pocket

Claims (14)

  The rolling member is a rolling bearing comprising a rolling element and a raceway, or a rolling element and a pair of washer disks, and the rolling direction of the contact area between the rolling element and the raceway or the rolling element and a pair of washer disks A rolling member characterized in that a groove having a length corresponding to a width in a direction perpendicular to the at least one member is provided along the rolling direction.   The rolling member is a radial ball bearing having a ball and inner and outer races, and a groove having a length corresponding to the width in a direction perpendicular to the rolling direction of the contact area between the ball and the race is arranged along the rolling direction. A rolling member characterized by being arranged side by side on at least one of a ball and a raceway.   The rolling member according to claim 2, wherein the groove is provided in an inner race of the inner and outer races.   The rolling member is a thrust ball bearing having a ball and a pair of washer, and a groove having a length corresponding to the width in a direction perpendicular to the rolling direction of the contact area between the ball and the washer is formed along the rolling direction. A rolling member characterized by being arranged side by side on at least one of a ball and a washer.   The rolling member according to claim 4, wherein the groove is provided in the washer.   The rolling member is a thrust roller bearing having a roller and a pair of washer, and a groove having a length corresponding to the width in a direction perpendicular to the rolling direction of the contact area between the roller and the washer is formed along the rolling direction. A rolling member characterized by being arranged side by side on at least one of a roller and a washer.   The rolling member according to claim 6, wherein the groove is provided in the roller.   The rolling member according to claim 6, wherein the groove is provided in the washer.   The rolling member is a radial roller bearing having a roller and inner and outer races, and a groove having a length corresponding to the width in a direction perpendicular to the rolling direction of the contact area between the rollers and the race is arranged along the rolling direction. And a rolling member provided side by side on at least one of the races.   The rolling member according to claim 9, wherein the groove is provided in the roller.   The rolling member according to claim 9, wherein the groove is provided in an inner race.   The rolling member according to any one of claims 1 to 11, wherein the groove is divided at the center of a contact area of a member that is in rolling contact.   The rolling according to any one of claims 1 to 12, wherein a lubricating oil storage pocket for storing lubricating oil deeper than a depth of the groove is provided between the grooves arranged along the rolling direction. Element.   The rolling member according to claim 1, wherein the groove is formed by etching or laser processing.

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