JP2012237386A - Solid-lubrication rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-lubrication rolling bearing which is capable of achieving a well-maintained lubrication state in the solid-lubrication rolling bearing for a long period of time and thereby providing an extended service life for the bearing.SOLUTION: In each pocket 4a of a cage 4 for retaining a ball 3 between an inner and outer rings 1, 2, one of each the ball 3 and the columnar lubrication member 5 composed of a material containing 60-98 vol.% of graphite are stored. By sliding contacting one end face of the lubrication member 5 to the ball 3, on a surface of the ball 3, a transported film of graphite which is hardly releasable is formed evenly. As the result, under high temperature atmosphere, the lubrication state between the ball 3 with an inner ring rolling face 1a and an outer ring rolling face 2a is well-maintained for a long period of time and thereby an extended service life for the bearing can be achieved.

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 solid lubricant is supplied from a lubricating ball over a long period of time by incorporating at least one ball (hereinafter referred to as “lubricating ball”) formed of a solid lubricating composite material between an inner ring and an outer ring. Solid lubricated rolling bearings have been proposed.

  The solid lubricated rolling bearing proposed in Patent Document 2 incorporates the same lubricating balls as in Patent Document 1 between the inner and outer rings, and is solid on the surface of at least one of the inner ring, outer ring, and rolling element. A lubricating film is provided so that a good lubricating state can be obtained even in the initial stage of rotation when the supply of the solid lubricant from the lubricating ball is small.

JP 2005-48852 A JP 2005-133881 A

  In the solid lubricated rolling bearing described in Patent Documents 1 and 2, the lubricant balls roll on the rolling surfaces of the inner ring and the outer ring, so that a transfer film of a solid lubricant is formed on each rolling surface, The space between the rolling surface and the rolling element is lubricated.

  However, since the contact of the lubrication ball with the rolling surface of the inner and outer rings is rolling contact, the transfer film of the solid lubricant formed on the rolling surface is uneven, and the adhesion force is weak, so that it is easy to peel off. For this reason, the lubrication state between each rolling surface and a rolling element is not necessarily maintained well, and the bearing may have a short life.

  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 problems, the present invention provides a plurality of rolling elements between an inner ring and an outer ring, a cage that holds each of the rolling elements in a pocket and holds the rolling elements, and a solid lubricant. In a solid lubricated rolling bearing incorporating a lubrication member formed of a material containing, a lubrication member formed of a material containing 60 to 98 vol% of the rolling element and graphite as the solid lubricant in each pocket of the cage The structure which accommodated one or more each in the state which slip | slidly contacts each other was employ | adopted.

  That is, a sliding member made of a material containing 60 to 98 vol% of graphite is brought into sliding contact with the rolling element, so that a graphite transfer film that does not easily peel off is formed on the surface of the rolling element. Thus, the lubrication state between the rolling surfaces of the inner and outer rings and the rolling elements can be satisfactorily maintained over a long period of time.

  Here, the reason why graphite was selected as the solid lubricant contained in the lubricating member is that graphite is superior to other solid lubricants in terms of heat resistance, availability, and lubricity at high temperatures in the atmosphere. It is. However, if the blending ratio is less than 60 vol%, a sufficient lubricating effect cannot be obtained at high temperatures in the atmosphere, so 60 vol% or more is necessary, and preferably 80 vol% or more. On the other hand, if it exceeds 98 vol%, the amount of the binder is insufficient, the strength of the lubricating member is reduced, and chipping or cracking occurs during use.

  In the above-described configuration, as a specific arrangement of the rolling elements and the lubricating member in each pocket of the cage, one rolling element and one lubricating member are accommodated in each pocket of the cage, or one It is preferable to accommodate the rolling element and two lubricating members arranged at positions sandwiching the rolling element. This is because the solid lubricant is supplied from one or two lubricating members to one rolling element, and a sufficient lubricating effect is surely obtained. Moreover, when it arrange | positions so that one rolling element may be pinched | interposed by two lubrication members, the sliding location of a rolling element and a holder | retainer is reduced compared with the case where one rolling element and one lubrication member are accommodated. And rotational torque can be reduced.

  The lubricating member preferably has two parallel planes, one of which is in sliding contact with the rolling element and the other plane is in sliding contact with the cage. In this way, the lubricating member can be easily processed and hardly damaged. As the shape of the lubricating member, for example, a cylindrical shape or a prismatic shape can be adopted. Also, it is desirable to provide a groove on the surface of the lubricating member that makes sliding contact so that the wear powder can be easily discharged.

  The lubricating member can be formed of a sintered body of graphite and a binder. The binder includes at least one of one metal selected from the group consisting of Fe, Cu, Ni, W, Sn, Co, and Cr, or an oxide, nitride, or boride of each metal. Should be used.

  On the other hand, the inner ring, the outer ring, and the rolling element are preferably formed of martensitic stainless steel in order to provide heat resistance, and JIS SUS440C is preferably used as the martensitic stainless steel. In order to improve the initial lubrication, the surface of the rolling element may be subjected to a solid lubricating film treatment. The rolling elements may be formed of ceramics that can be expected to reduce adhesion with the rolling surfaces of the inner and outer rings. In this case, silicon nitride is preferably used.

  Also, seal members that close the annular space between the inner ring and the outer ring are attached to both axial ends of either the inner ring or the outer ring to prevent the abrasive powder of solid lubricant from scattering outside the bearing. Is desirable. The sealing member is preferably formed of austenitic stainless steel in order to provide heat resistance, and JIS standard SUS304 is preferably used as the austenitic stainless steel.

  The cage is also preferably made of austenitic stainless steel in order to provide heat resistance, and JIS standard SUS304 is preferably used as the austenitic stainless steel.

And the solid-lubricated rolling bearing of this invention can be applied especially effectively with respect to the rolling bearing used in the high temperature environment in air | atmosphere. The high temperature here means a temperature at which continuous operation for 24 hours or more cannot be performed when fluorine grease is used as a lubricant for a rolling bearing, for example, a maximum contact pressure between a rolling element and an inner and outer ring rolling surface is 1.7 GPa. When the rotation speed is 1000 min ^−1, the temperature reaches a lifetime in 5 to 10 hours, and is generally 350 ° C. or higher. As a rolling bearing used in such a high temperature environment, for example, it is attached to a tenter clip that holds a resin film in a resin film stretching apparatus, and is used as a guide roller that rolls on a guide rail for guiding the tenter clip. There are rolling bearings and conveying bearings for glass substrate manufacturing equipment.

  In the present invention, as described above, the lubricating member of the rolling bearing is formed of a material containing 60 to 98 vol% of graphite, and the lubricating member is housed in the pocket of the cage together with the rolling element so as to be in sliding contact with the rolling element. As a result, it is possible to uniformly form a graphite transfer film that does not easily peel off on the surface of the rolling element. Therefore, even under a high temperature environment in the atmosphere, the lubrication state between the rolling surfaces of the inner and outer rings and the rolling elements can be satisfactorily maintained 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 first embodiment except for the shield 1 is an external perspective view of the lubricating member of FIG. Sectional view along line III-III in FIG. Explanatory drawing of the assembled state of the ball and lubricating member of FIG. Partially cutaway front view of the solid lubricated rolling bearing of the second embodiment except for the shield Explanatory drawing of the assembled state of the ball and lubricating member of FIG. a and b are graphs showing results of durability confirmation experiments for the bearings of the embodiments and comparative examples, respectively.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment. This solid-lubricated rolling bearing is attached to a tenter clip that holds the resin film in the resin film stretching apparatus, and serves as a guide roller that rolls on the guide rail for guiding the tenter clip. As shown in FIGS. 1 and 3, the basic structure has rolling surfaces 1a, 2a having concave arcs 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 the inner ring rolling surface 1a and the outer ring rolling surface 2a.

  A cage 4 is incorporated between the inner ring 1 and the outer ring 2 so as to accommodate each ball 3 in a pocket 4a and hold it freely. And in each pocket 4a of this holder | retainer 4, the ball | bowl 3 and the lubricating member 5 of the shape shown in FIG. 2 are accommodated in the state which mutually slide-contacts (refer FIG. 4).

  As shown in FIG. 3, a shield (seal member) 7 that closes the annular space 6 between the inner ring 1 and the outer ring 2 is attached to both ends of the outer ring 2 in the axial direction, and forms a lubricating member 5. The wear powder is prevented from scattering outside the bearing. 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 also be formed of ceramics such as silicon nitride. On the other hand, the cage 4 and the shield 7 are formed of SUS304.

  As shown in FIG. 4, the retainer 4 is formed in a state of being divided into two in the axial direction, and is integrated by crimping at the position of the column portion 4b that partitions the pocket 4a.

  Each of the lubricating members 5 is formed in a cylindrical shape with graphite alone or a sintered body of graphite and binder (see FIG. 2), and one of the parallel planes at both ends thereof is in sliding contact with the ball 3. The other is in sliding contact with the inner wall of the pocket 4a of the cage 4. Lattice-like grooves 5a are provided on both end faces where the sliding contact is made, so that abrasion powder is easily discharged (see FIG. 2). In addition, although the groove | channel of this surface which carries out a sliding contact can be formed in various forms, such as concentric form, it is not necessary to necessarily provide. Further, the overall shape of the lubricating member is not limited to the cylindrical shape as in the embodiment, and may be a prismatic shape, for example.

  The blending ratio of graphite forming the lubricating member 5 is 60 to 98 vol%, preferably 80 to 98 vol%. When the lubricating member 5 is formed of a sintered body of graphite and binder, the binder includes one kind of metal selected from the group of Fe, Cu, Ni, W, Sn, Co, Cr, or these A material containing at least one of oxides, nitrides and borides of each metal is used.

  In addition, petroleum coke and petroleum pitch coke are used as aggregates, coal tar pitch and coal tar are used as binders, these are kneaded, extruded, compression molded, molded by CIP, etc., then calcined, graphitized It is also possible to use a lubricating member manufactured through the above process.

  This solid-lubricated rolling bearing has the above-described configuration, and the lubricating member 5 formed of a material containing 60 to 98 vol% of graphite is housed in the pocket 4 a of the cage 4 together with the ball 3 and is in sliding contact with the ball 3. Therefore, a graphite transfer film that hardly peels off is formed uniformly on the surface of the ball 3, and the graphite is also transferred to the rolling surfaces 1 a and 2 a of the inner and outer rings 1 and 2 and the cage 4. As a result, even in a high temperature environment in the atmosphere, the lubrication state between the inner and outer ring rolling surfaces 1a, 2a and the cage 4 and the ball 3 is well maintained for a long period of time, and the life is longer than that of the conventional one.

  5 and 6 show a second embodiment. In this embodiment, one ball 3 and two lubrication members 5 are accommodated in each pocket 4 a of the cage 4, and each lubrication member 5 is disposed at a position sandwiching the balls 3 so as to slide with the balls 3. It comes to contact. Thereby, compared with 1st Embodiment mentioned above, the sliding location of the ball | bowl 3 and the holder | retainer 4 can be reduced, and rotational torque can be reduced.

Next, an experiment conducted for confirming the durability of the bearing of each embodiment described above will be described. In the experiment, 16 types of test bearings having a reference number 608 were prepared, two for each type. Each test bearing is obtained by changing the graphite blending ratio of the lubricating member based on the configuration of the embodiment or changing a part of the following reference configuration. Table 1 shows the changes from the reference configuration of each test bearing and the graphite blend ratio of the lubricating member.
(Standard configuration of test bearing)
Main component of lubricating member: Graphite Lubricating member shape: Cylindrical cylinders with both end faces (sliding contact surfaces) without grooves Arrangement in cage pocket: One ball and one lubricating member Inner ring / outer ring / ball material: SUS440C
Cage / shield material: SUS304
Ball surface coating treatment: None

  Eleven types of the test bearings have the configuration of the first or second embodiment (Examples 1 to 11). The remaining five types each use a lubricating member formed of a material mainly composed of tungsten disulfide or molybdenum disulfide (mixing ratio 95 vol%) instead of the lubricating member of the first embodiment (Comparative Example 1). 2), one using a lubricating member in which the mixing ratio of graphite is 50 vol% or 100 vol% (Comparative Examples 3 and 4), and one rolling element ball without using the lubricating member as in each embodiment Only a lubricating ball made of tungsten disulfide is used (Comparative Example 5). Note that the lubricating ball of Comparative Example 5 is formed to have a diameter of about 20 to 40 μm smaller than other balls that are rolling elements.

  Examples 1 to 4 are of the first embodiment in which one ball and a lubricating member are accommodated in each pocket of the cage, and the blending ratios of graphite forming the lubricating member are different from each other. . In Examples 5 and 6, the lubricating members having the same composition as in Examples 2 and 4 were used, respectively, and one ball and two lubricating members sandwiching the balls were accommodated in each pocket of the cage. It is. Example 7 was obtained by subjecting the balls of Example 2 to a graphite coating treatment, Example 8 was obtained by forming the balls of Example 2 with silicon nitride, and Example 9 was a bearing steel comprising the balls and inner and outer rings of Example 2 (SUJ2), and the cage and shield are made of cold rolled steel plate (SPCC). In Example 10, a grid-like groove is formed on the sliding contact surface of the lubricating member of Example 2 with the ball and the cage. In Example 11, the sliding contact surface of the lubricating member of Example 2 with the ball is formed. It is a concave surface along the ball surface.

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 this was defined as the bearing life. FIG. 7A shows the bearing life of each example, and FIG. 7B shows the bearing life of each comparative example.
(Test conditions)
Heating temperature: 350 ° C
Axial load: 196N
Rotational speed: 1000 min ^-1

  As is clear from FIGS. 7A and 7B, the life of each example is more than twice as long as the comparative examples 3 and 4 having the longest life among the comparative examples. It has been confirmed that the invention can greatly extend the life of a solid lubricated rolling bearing.

  In the above-described embodiment, one ball, which is a rolling element, and one or two lubricating members are accommodated in each pocket of the cage, but the rolling element accommodated in one pocket of the cage is The number of lubricating members is not limited to this.

  Further, the present invention is not limited to the ball bearing as in the above-described embodiment, but can be applied to a rolling bearing such as a cylindrical roller bearing. And it can apply widely to not only what is used in the resin film extending | stretching apparatus like embodiment but the rolling bearing used in high temperature environments in air | atmosphere, such as a bearing for conveyance of a glass substrate manufacturing apparatus.

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

Claims (16)

  A plurality of rolling elements, a cage that holds each rolling element in a pocket and holds the rolling elements in a freely rotatable manner, and a lubricating member formed of a material containing a solid lubricant are incorporated between an inner ring and an outer ring. In the solid lubricated rolling bearing, in each pocket of the cage, one or more of the rolling elements and a lubricating member formed of a material containing 60 to 98 vol% of graphite as the solid lubricant are in sliding contact with each other. Solid lubricated rolling bearing characterized by being housed.   The solid lubricated rolling bearing according to claim 1, wherein each of the rolling elements and the lubricating member is accommodated in each pocket of the cage.   2. The solid lubricated rolling bearing according to claim 1, wherein each of the pockets of the cage contains one of the rolling elements and two of the lubricating members arranged at positions sandwiching the rolling elements. .   2. The lubrication member has two planes parallel to each other, one of which is in sliding contact with the rolling element, and the other plane is in sliding contact with the cage. The solid lubricated rolling bearing according to any one of 1 to 3.   The solid lubricated rolling bearing according to any one of claims 1 to 4, wherein a groove is provided on a surface of the lubricating member in sliding contact.   The solid lubricated rolling bearing according to any one of claims 1 to 5, wherein the lubricating member is formed of 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 6, which is used.   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.   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 lubricant rolling bearing according to claim 10, wherein the ceramic is silicon nitride.   The solid lubricated rolling according to any one of claims 1 to 12, wherein a seal member for closing an annular space between the inner ring and the outer ring is attached to both axial ends of either the inner ring or the outer ring. bearing.   The solid-lubricated rolling bearing according to any one of claims 1 to 13, which is used in an atmosphere of 350 ° 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.   The solid-lubricated rolling bearing according to any one of claims 1 to 14, wherein the solid-lubricated rolling bearing is used as a bearing for conveyance in a glass substrate manufacturing apparatus.

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