JP2007232177A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve lubricating condition in a guide clearance when grease lubrication is adopted in an outer ring guide system rolling bearing. <P>SOLUTION: A resin cage 3 assembled between an outer ring 1 and an inner ring 2 is guided by the cage guide surface of the outer ring 1 and the guide surface of the resin cage 3, and at least one of the cage guide surface of the outer ring 1 and the guide surface of the resin cage 3 is provided with a recessed part 33 formed to retain grease. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rolling bearing suitable for supporting a high-speed rotating shaft such as a main shaft of a machine tool, and more particularly to a lubrication technique when a cage is an outer ring guide system.

  In recent machine tools, in order to shorten the machining time, the spindle is rotated at a high speed. In a rolling bearing that supports a high-speed rotating shaft such as this main shaft, the lubricant inside is blown to the outer ring side by centrifugal force. For this reason, countermeasures are required so that poor lubrication does not occur on the inner ring outer diameter surface and the cage inner diameter surface.

  Conventionally, as a countermeasure against the above-mentioned poor lubrication, in a rolling bearing in which a cage is incorporated between an outer ring and an inner ring, the cage is made of resin, and the cage is divided into a cage guide surface of the outer ring and a guide surface of the cage. By adopting an outer ring guide system configured to guide, the gap formed between the outer diameter surface of the inner ring and the inner diameter surface of the cage is enlarged, and lubricating oil is directly supplied to the gap. (See Patent Document 1).

  In the above rolling bearing, oil is directly supplied between the outer diameter surface of the inner ring and the inner diameter surface of the cage, so that an oil film is easily formed between both surfaces. Further, the supplied lubricating oil is blown off by a centrifugal force to form an oil film between the outer ring and the cage. Furthermore, the self-lubricating property of the resin material forming the cage also contributes to lubrication between the cage and both wheels. Therefore, the rolling bearing is suitable for supporting a shaft that rotates at high speed.

Japanese Patent Laying-Open No. 2004-3577 (FIGS. 1 and 2 [0004] to [0009])

  However, the outer ring guide type rolling bearing as described above is effective when oil lubrication can be employed, but there is a difference (guide clearance) between the diameter of the cage guide surface of the outer ring and the diameter of the guide surface of the cage. Compared to the inner ring guide method and the rolling element guide method, it becomes smaller. For this reason, when grease lubrication is adopted for a rolling bearing of the outer ring guide system, it is difficult to supply grease to the guide clearance, and the cage is guided in a poorly lubricated state where there is almost no grease in the guide clearance. There has been a problem that the higher the speed of rotation, the easier it is to generate cage noise due to poor lubrication.

  Therefore, an object of the present invention is to improve the lubrication state in the guide clearance when grease lubrication is adopted for the outer ring guide type rolling bearing.

  In order to achieve the above object, the present invention provides a rolling bearing in which a resin cage incorporated between an outer ring and an inner ring is guided by a cage guide surface of the outer ring and a guide surface of the resin cage. A recess for holding grease is formed on at least one of the cage guide surface of the outer ring and the guide surface of the resin cage.

  According to the present invention, when the grease lubrication is employed in at least one of the cage guide surface of the outer ring and the guide surface of the resin cage, the grease is retained in the recess. An oil film is formed in the guide gap by the applied grease, and as a result, the lubrication state in the guide gap can be improved.

  Moreover, in the said structure, the said resin holder has an annular part and the some pillar part formed in the axial direction side surface of this annular part, The said recessed part is the said pillar among the said annular part. It is preferable to adopt a configuration formed in a part on the axial extension of the part. Since the strength of the part of the annular part on the axial extension of the cage pillar part is higher than that of the other parts, the resin cage is deformed during high-speed rotation by forming a recess in this part. Can be suppressed as much as possible.

  In the above configuration, since the outer ring guide method is adopted, the gap between the inner diameter surface of the cage and the outer diameter surface of the inner ring is larger than that of other guide methods. Easy to form. Therefore, the rolling bearing having the above configuration is more suitable for supporting the spindle of the machine tool because it is more adaptable to high-speed rotation than the conventional example and the generation of cage noise is suppressed. Become.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 4 shows a support structure frequently used for a spindle of a machine tool such as a lathe or a machining center. The fixed side of the main shaft 10 is supported by a double row cylindrical roller bearing 11 that receives only a radial load and a combination angular ball bearing 12 that receives only an axial load. The free side of the main shaft 10 is supported by a single row cylindrical roller bearing 13.

  The combined angular contact ball bearing 12 is loosely fitted to the housing 14 on the outer diameter surface of the outer ring so that only the axial load is received and not the radial load. On the other hand, since the double row cylindrical roller bearing 11 and the single row cylindrical roller bearing 13 receive only a radial load, the outer diameter surfaces of the outer rings are tightly fitted to the housing 14.

  As shown in FIG. 1, the angular ball bearing 12 according to the first embodiment includes an outer ring 1 divided on the counter-bore side, two inner rings 2 on which the counter-bore sides face each other, and the inner rings 2. And the outer ring 1 are constituted by a plurality of rolling elements 4 held by two right and left resin holders 3.

  The rolling element 4 is rotatably incorporated between a pair of left and right raceway surfaces 5 formed on the inner diameter surface of the outer ring 1 and a raceway surface 6 formed on the outer diameter surface of the inner ring 2.

  Oil seals 7 are fitted to both ends of the inner diameter surface of the outer ring 1, and grease is sealed inside the bearing.

  As shown in FIGS. 1 and 2, the resin retainer 3 includes two annular portions 31a and 31b and a plurality of column portions 32 formed between the axial side surfaces of the annular portions 31a and 31b. The rolling elements 4 are arranged equally. The combined angular ball bearing 12 is configured in an outer ring guide system by positioning one annular portion 31 a between the counter-bore portion 1 a of the outer ring 1 and the counter-bore portion 2 a of the inner ring 2.

  Specifically, a portion of the outer diameter surface of the resin retainer 3 located between the counter-counter bore portion 1a and the counter-bore portion 2a has a guide clearance required for guiding the resin retainer 3, and the counter-bore portion. It becomes a guide surface with respect to the inner diameter surface of 1a, and a part of inner diameter surface of the counter-bore part 1a of the outer ring 1 becomes a cage guide surface.

  A concave portion 33 for holding grease is formed on the outer diameter surface of the annular portion 31a constituting the guide surface of the resin holder 3. By storing grease in the recess 33, an oil film is continuously formed in the guide gap. As a result, the lubrication state in the guide clearance is improved, and accordingly, the generation of cage noise is also suppressed.

  On the other hand, in the combined angular contact ball bearing 12, with the adoption of the outer ring guide system, a relatively large gap is formed between the inner diameter surface of the resin cage 3 and the inner ring 2, and grease enters the gap to form an oil film. Formed continuously.

As said grease, the following products can be used, for example.
(1) Product name: Isoflex LDS18 Manufacturer: NOK Kluber Corporation (2) Product name: Isoflex NBU15 Manufacturer: NOK Kluber Corporation (3) Product name: Multemp PS2 Manufacturer: Kyodo Yushi Co., Ltd. ( 4) Product name: Multemp LRL3 Manufacturer: Kyodo Yushi Co., Ltd. (5) Product name: Multemp PS2 Manufacturer: Kyodo Yushi Co., Ltd.

  The resin cage 3 is preferably formed using a resin material having excellent self-lubricating properties such as phenol resin and polyether ether ketone (PEEK). This is to further improve the lubrication between the resin retainer 3 and the two wheels 1 and 2.

  In the combination angular contact ball bearing 12, the recess 33 is formed in a portion of the annular portion 31 a located on the axial extension of each column portion 32. This is because grease is accumulated near each column portion 32 to promote oil film formation between the outer diameter surface of each column portion 32 and the outer ring 1. As a result, a part of the outer diameter surface of each column portion 32 can be actively used as a guide surface. Such a position configuration is preferable in that the guide area of the cage can be increased and the swinging can be suppressed when the one-side guide method is used like the resin cage 3.

  Further, since the portion where the concave portion 33 is formed is a portion having a relatively high strength in the resin retainer 3, the above position configuration is a deformation caused by the formation of the concave portion 33 when the resin retainer 3 rotates at high speed. This is also advantageous in that it can be reduced. In particular, by providing the concave portion 33 at a position where the axial center of the annular portion 31a intersects with the axial extension line of the column portion 32, a decrease in cage strength due to the formation of the concave portion 33 can be minimized. .

  Further, the recesses 33 are equally arranged in the circumferential direction and are arranged in a line. This is because it is advantageous in that the eccentricity of the resin retainer 3 can be reduced as much as possible and the swinging thereof can be suppressed.

  The concave portion 33 may be arranged in any manner as long as an oil film is formed in the guide gap. Further, when the eccentricity of the resin retainer 3 is positively avoided or an outer ring without a counterbore is used, the concave portion 33 can be formed in the other annular portion 31b.

  Moreover, although the recessed part 33 was used as the hole part, and the recessed part 33 was made into circular arc shape of the cross section, and the edge shape was made into the substantially circular hole, it is not limited to such a form, The cross-sectional shape of the recessed part 33 Each of the edge shapes can be appropriately changed to a triangle, a quadrangle, or the like. Moreover, the recessed part 33 can also be formed as a groove | channel. Note that when the edge of the recess 33 is chamfered, there is no portion that contacts the guide surface, and the oil film is prevented from being broken or the edge is missing.

  In the combination angular contact ball bearing 12, the recess 33 is formed only on the guide surface of the resin retainer 3, but at least one of the retainer guide surface of the counter-counter bore 1 a and the guide surface of the resin retainer 3. A recess for holding grease may be formed on the surface, and the recess 33 can be formed on both surfaces.

  Next, the single row cylindrical roller bearing 13 according to the second embodiment will be described. Only differences from the first embodiment will be described. As shown in FIG. 3, the single-row cylindrical roller bearing 13 is composed of an outer ring 41 and rolling elements 44 held by a resin holder 43 between an inner ring 42 with both flanges.

  The outer diameter surface of each annular portion 45 of the resin retainer 43 serves as its guide surface, and the portion of the inner diameter surface of the outer ring 41 that faces the outer diameter surface of the annular portion 45 serves as the retainer guide surface.

  A recess 46 for holding grease is formed in the cage guide surface of the outer ring 41. A recess 46 is similarly formed on the outer diameter surface of the annular portion 45. By storing grease in each recess 46, an oil film is continuously formed in the guide gap.

  In the single-row cylindrical roller bearing 13, the concave portions 46 are formed on both surfaces of the cage guide surface of the outer ring 41 and the guide surface of the resin cage 43, but may be formed only on one of the surfaces.

  Also in the double row cylindrical roller bearing 11, the cage may be made of resin, and a recess for retaining grease may be formed on at least one of the guide surface of the resin cage and the cage guide surface of the outer ring. it can.

Sectional drawing of the principal part of the combination angular contact ball bearing which concerns on 1st Embodiment. 1 is a partially cutaway enlarged perspective view of the resin cage of FIG. Sectional drawing of the principal part of the single row cylindrical roller bearing which concerns on 2nd Embodiment Sectional view of the structure in which the spindle of the machine tool is supported using the rolling bearings of FIGS.

Explanation of symbols

1, 41 Outer ring 2, 42 Inner ring 3, 43 Resin cage 10 Main shaft 12 Combined angular ball bearing 13 Single row cylindrical roller bearing 33, 46 Recess

Claims (3)

  In a rolling bearing in which a resin cage incorporated between an outer ring and an inner ring is guided by a cage guide surface of the outer ring and a guide surface of the resin cage, the cage guide surface of the outer ring and the resin holding A rolling bearing characterized in that a recess for holding grease is formed on at least one of the guide surfaces of the vessel.   The resin retainer has an annular portion and a plurality of column portions formed on the side surface in the axial direction of the annular portion, and the concave portion is on the axial extension of the column portion of the annular portion. The rolling bearing according to claim 1 formed in a portion.   The rolling bearing according to claim 1, wherein the rolling bearing supports a spindle of a machine tool.

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