JP2012067884A - Solid-lubrication rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend a bearing service life by excellently maintaining the lubricating state inside a solid-lubrication rolling bearing for a long period of time.SOLUTION: A pillar-shaped separator 4 is arranged at every other ball 3 between inner and outer rings 1, 2. Lubrication rings 7 is arranged between shields 6 attached to both ends of the outer ring 2, and the array of the balls 3. The pillar-shaped separators and the lubricating rings are formed of graphite. The blending ratio of the graphite is set to 90-100 vol.%, thereby achieving sufficient lubrication. The bending strength of the separators 4 is set to 10-90 MPa, thereby preventing breakage of the separators 4 in operation. As a result, it is possible to excellently maintain the lubricating state between an inner-ring raceway surface 1a/an outer-ring raceway surface 2a and the balls 3 over a long period of time, thereby achieving the extension of the bearing service life.

Description

  The present invention relates to a solid lubricated rolling bearing used under high temperature conditions.

  In rolling bearings used under high temperature conditions, fluorine grease having excellent heat resistance is generally enclosed as a lubricant. However, for example, a rolling bearing used as a guide roller for a tenter clip in a resin film stretching apparatus, such as a rolling bearing that is exposed to a high temperature that is insufficient in heat resistance even with fluorine grease, is usually more than with fluorine grease. Lubrication with a solid lubricant having high heat resistance is performed.

  For example, in Patent Document 1, a ring formed of a solid lubricant (hereinafter referred to as a “lubricating ring”) on both sides of an array of rolling elements between inner and outer rings, and an elastic member that presses the lubricating ring against the rolling elements, There has been proposed a rolling bearing in which a solid lubricant is transferred from a lubrication ring to a rolling element to perform lubrication.

  Further, in the rolling bearing proposed in Patent Document 2, by incorporating a column-shaped separator having a sectoral cross section formed of a solid lubricant into every other or a plurality of rolling elements arranged between the inner and outer rings, Lubricating is performed by transferring a solid lubricant from the separator to the rolling surfaces of the rolling elements and inner and outer rings.

JP 2008-14411 A JP 2000-320548 A

  In the rolling bearing described in Patent Document 1, since the solid lubricant is supplied to the rolling elements by the lubrication ring only from the axial direction, the solid lubricant is provided between the rolling elements and the rolling surfaces of the inner and outer rings. May not be able to penetrate, and there is a possibility that sufficient lubrication cannot be performed.

  On the other hand, in the rolling bearing described in Patent Document 2, since the strength of the separator formed with the solid lubricant is small, the separator may be damaged during operation. On the other hand, if the blending ratio of the solid lubricant is lowered to increase the strength of the separator, sufficient lubrication cannot be performed.

  Therefore, an object of the present invention is to maintain the lubrication state inside the solid lubricated rolling bearing well over a long period of time and extend the bearing life.

  In order to solve the above-described problems, a solid lubricated rolling bearing of the present invention is attached to a plurality of rolling elements arranged between an inner ring and an outer ring, and both axial ends of either the inner ring or the outer ring. A sealing member that closes the annular space between the inner ring and the outer ring, a lubricating ring that is formed of graphite and is arranged between the array of rolling elements and the sealing member, and that is formed of graphite and between the rolling elements. And a columnar separator disposed on the lubricating ring, the blending ratio of graphite of the lubricating ring and the separator is 90 to 100 vol%, and the bending strength of the separator is 10 to 90 MPa.

  That is, sufficient lubrication is achieved by forming the lubrication ring and separator incorporated in the bearing with graphite, which is particularly excellent in lubricity among solid lubricants, and setting the blending ratio of the graphite to 90 to 100 vol%. And the bending strength of the separator is 10 to 90 MPa, so that the separator can be prevented from being damaged during operation.

  Said structure WHEREIN: The said lubrication ring and a separator can each be formed with the sintered compact of only graphite or a graphite, and a binder. The binder contains at least one of one metal selected from the group consisting of Fe, Cu, Ni, W, Sn, Co, and Cr, or an oxide, nitride, and boride of each of the above metals. Should be used. Further, at least one of the two members can be molded by any one of a cold isostatic press molding method (CIP), an extrusion molding method, and a compression molding method.

  As the separator, one having a flat surface facing the rolling element or one formed in a columnar shape can be used.

  The inner ring, outer ring and rolling element are preferably formed of martensitic stainless steel, and JIS standard SUS440C is preferably used as the martensitic stainless steel. Further, the rolling element may be formed of ceramics. In this case, it is preferable to use silicon nitride as the ceramics.

  On the other hand, when the rolling element is not formed of ceramics, it is desirable to form a graphite film on the surface thereof.

  The solid-lubricated rolling bearing of the present invention is attached to a rolling bearing used in an atmosphere of 250 ° C. or higher in the atmosphere, for example, a tenter clip that holds a resin film in a resin film stretching apparatus, and is used for guiding a tenter clip. The present invention can be particularly effectively applied to a rolling bearing used as a guide roller that rolls on a guide rail.

  As described above, in the solid lubricated rolling bearing of the present invention, the lubricating ring and separator incorporated in the bearing are formed of graphite, the blending ratio of the graphite is 90 to 100 vol%, and the bending strength of the separator is 10 to 90 MPa. Therefore, the inside of the bearing is sufficiently lubricated, and there is no possibility that the separator is damaged during operation. Therefore, the lubrication state between the rolling surfaces of the inner and outer rings and the rolling elements can be maintained well over a long period of time, and the bearing life can be extended.

Partially cutaway front view of the solid lubricated rolling bearing of the embodiment except for the shield Sectional view along the line II-II in FIG. 1 is a perspective view of the separator of FIG. 1, and b and c are perspective views of modified examples of the separator shape, respectively.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This solid-lubricated rolling bearing is attached to a tenter clip that holds the resin film in the resin film stretching device, and is used as a guide roller that rolls on the guide rail for guiding the tenter clip in an atmosphere of 250 ° C. or higher. As shown in FIG. 1, the basic configuration thereof has rolling surfaces 1 a and 2 a having a concave arc shape in cross section on the outer periphery of the inner ring 1 and the inner periphery of the outer ring 2, respectively. A ball bearing in which balls 3 as a plurality of rolling elements are arranged between a surface 1a and an outer ring rolling surface 2a.

  As shown in FIGS. 1 and 2, between the inner ring 1 and the outer ring 2, columnar separators 4 are incorporated every other ball 3. In addition, you may make it incorporate a separator every several balls.

  As shown in FIG. 2, shields (seal members) 6 that close the annular space 5 between the inner ring 1 and the outer ring 2 are attached to both ends in the axial direction of the outer ring 2. A lubrication ring 7 is arranged between the arrays. Note that a heat-resistant seal can be used instead of the shield.

  The inner ring 1, outer ring 2 and ball 3 are made of SUS440C, but other martensitic stainless steels may be used. The ball 3 can be formed of ceramics such as silicon nitride, but if not formed of ceramics, a film of a solid lubricant such as graphite may be formed on the surface thereof. On the other hand, the shield 6 is formed of SUS304.

  The separator 4 and the lubricating ring 7 are molded by any one of a cold isostatic press molding method (CIP), an extrusion molding method, and a compression molding method using only graphite or a sintered body of graphite and a binder. Or a plate material, pipe material, bar material or the like molded by the same molding method is formed into a desired shape. The blending ratio of each graphite is 90 to 100 vol%, preferably 95 to 100 vol%. When these members are formed of a sintered body of graphite and a binder, the binder includes one metal selected from the group consisting of Fe, Cu, Ni, W, Sn, Co, and Cr, or each of these metals. A material containing at least one of oxides, nitrides and borides is used. And in any case, the separator 4 is formed so that bending strength may be 10-90 MPa.

  The shape of the separator 4 is a prism having a substantially square cross section, as shown in FIG. 3A, and both circumferential edges of the surface facing the outer ring 2 are chamfered. As a modification of the shape, as shown in FIG. 3B, the surface facing the inner and outer rings 1 and 2 is a cylindrical surface, and the surface facing the ball 3 is a flat surface, or as shown in FIG. Thus, the whole may be formed in a columnar shape, and dimples, grooves or the like may be formed on the surface as necessary.

  This solid-lubricated rolling bearing has the above-described configuration, and the separator 4 and the lubricating ring 7 having a graphite blending ratio of 90 to 100 vol% are in contact with the ball 3 during operation, and the ball 3 is in contact with the graphite. Therefore, a sufficient graphite transfer film can be formed on the balls 3. Moreover, since the bending strength of the separator 4 is set to 10 to 90 MPa, there is no possibility that the separator 4 is damaged during operation. Therefore, the lubrication state between the inner ring rolling surface 1a and the outer ring rolling surface 2a and the ball 3 is maintained well over a long period of time, and the service life is longer than before.

Next, an experiment conducted for confirming the durability of the bearing of the above-described embodiment will be described. In the experiment, 20 types of test bearings having a reference number 608 of 10 types (Examples 1 to 13 and Comparative Examples 1 to 7) were prepared. Each test bearing is obtained by changing the graphite blending ratio of the separator and the lubrication ring based on the configuration of the embodiment or by changing a part of the following standard configuration. Table 1 shows the changes from the reference configuration of each test bearing and the graphite blending ratio of the separator / lubricating ring together with the experimental results (bearing life) described later.
(Standard configuration of test bearing)
Main component of separator / lubricating ring: graphite Material of inner ring / outer ring / ball: SUS440C
Solid lubricant coating on ball surface: None

  Here, the separator incorporated in each test bearing has a prismatic shape (height 2.5 mm × width 2.5 mm × length 4 mm) shown in FIG. 3A, and the lubricating ring has an outer diameter of 16 mm. 8 mm x inner diameter 13.2 mm x thickness 0.8 mm. When forming the separator and lubrication ring with a solid lubricant such as graphite, the separator and the lubrication ring are molded by any one of the cold isostatic press molding method (CIP), the extrusion molding method, and the compression molding method, and then baked at 1000 ° C. or higher. To obtain a sintered body. The bending strength of the separator was measured according to JIS R1601. Further, the formation of the graphite film on the ball surface in Example 12 was performed by spraying shot blast.

Two test bearings of the same type are attached to a high-temperature bearing tester in the atmosphere and operated under the following conditions until the total rotational torque of the two bearings reaches a certain value (147 mN · m). The operation time was measured, and the average of the five measurement results was defined as the bearing life.
(Test conditions)
Heating temperature: 250 ° C, 400 ° C (2 levels)
Axial load: 196N
Rotational speed: 1000 min ^-1

  As is apparent from Table 1, in each case where the heating temperature is 250 ° C. and 400 ° C., the life of each example is about several times that of each comparative example. In each of the examples and comparative examples, the separator was not damaged during operation. From this result, it was confirmed that the life of the solid lubricated rolling bearing can be greatly extended by the present invention.

  The present invention is not limited to the ball bearings as in the above-described embodiments, but can be applied to rolling bearings such as cylindrical roller bearings.

DESCRIPTION OF SYMBOLS 1 Inner ring 1a Rolling surface 2 Outer ring 2a Rolling surface 3 Ball 4 Separator 5 Annular space 6 Shield (seal member)
7 Lubrication ring

Claims (15)

  A plurality of rolling elements disposed between the inner ring and the outer ring, a seal member attached to both axial ends of the inner ring and the outer ring, and closing the annular space between the inner ring and the outer ring, and graphite. A lubrication ring formed between the rolling element array and the seal member, and a columnar separator formed of graphite and disposed between the rolling elements, the lubrication ring and the graphite of the separator. A solid lubricated rolling bearing having a blending ratio of 90 to 100 vol% and a bending strength of the separator of 10 to 90 MPa.   2. The solid lubricated rolling bearing according to claim 1, wherein the lubricating ring is made of only graphite or a sintered body of graphite and a binder.   The solid lubricated rolling bearing according to claim 1 or 2, wherein the separator is made of only graphite or a sintered body of graphite and a binder.   The binder contains at least one of one metal selected from the group consisting of Fe, Cu, Ni, W, Sn, Co, and Cr, or an oxide, nitride, and boride of each metal. The solid lubricated rolling bearing according to claim 2 or 3, wherein the solid lubricated rolling bearing is used.   5. At least one of the lubrication ring and the separator is formed by any one of a cold isostatic press molding method, an extrusion molding method, and a compression molding method. Solid lubricated rolling bearing.   6. The solid lubricated rolling bearing according to claim 1, wherein a surface of the separator facing the rolling element is a flat surface.   6. The solid lubricated rolling bearing according to claim 1, wherein the separator is formed in a columnar shape.   The solid lubricated rolling bearing according to any one of claims 1 to 7, wherein the inner ring and the outer ring are made of martensitic stainless steel.   The solid lubricated rolling bearing according to any one of claims 1 to 8, wherein the rolling element is made of martensitic stainless steel.   The solid lubricated rolling bearing according to any one of claims 1 to 9, wherein a graphite film is formed on a surface of the rolling element.   9. The solid lubricated rolling bearing according to claim 1, wherein the rolling element is made of ceramics.   The solid lubricated rolling bearing according to claim 8 or 9, wherein the martensitic stainless steel is JIS standard SUS440C.   The solid lubricated rolling bearing according to claim 11, wherein the ceramic is silicon nitride.   The solid-lubricated rolling bearing according to any one of claims 1 to 13, wherein the solid-lubricated rolling bearing is used in an atmosphere of 250 ° C or higher in the atmosphere.   The resin film stretching apparatus is attached to a tenter clip that holds the resin film and used as a guide roller that rolls on a guide rail for guiding the tenter clip. Solid lubricated rolling bearing.

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