JP2010043690A - Rolling bearing and bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deformation of the raceway surface of a wide-width inner ring even if a fastening screw is strongly fastened. <P>SOLUTION: This rolling bearing comprises an outer ring 3 and the wide-width inner ring 5, and also comprises, at an inner ring wide-width part 5a, a fixing device 7 which whirl-stops the wide-width inner ring 5 with respect to a rotating shaft 4 in a state that the wide-width inner ring 5 is loosely fitted into the rotating shaft 4. The fixing device 7 is composed of the fastening screw 8, the inner ring wide-width part 5a which is formed so that the fastening screw 9 penetrates the part in the radial direction, and an annular member 11 fitted into the external periphery of the inner ring wide-width part 5a. A screw-fastening hole 12 is formed at the annular member 11 so as to penetrate the member in the radial direction, the fastening screw 8 is screwed into the internal face of the screw-fastening hole 12 in a state that the screw-fastening hole 12 and a screw penetration hole 9 are made to communicate with each other in the radial direction, and screw-fitted into the screw penetration hole 9, the fastening screw 8 is press-pushed to the rotating shaft 4 by a fastening force, and the annular member 11 is whirl-stopped with respect to the rotating shaft 4. The wide-width inner ring 5 is whirl-stopped with respect to the rotating shaft 4 by the annular member 11 and the fastening screw 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rolling bearing in which a wide inner ring is prevented from rotating with respect to a rotating shaft, and a bearing unit in which the rolling bearing is incorporated in a bearing box.

  As shown in FIG. 3, as a rolling bearing for preventing the rotation of the wide inner ring on the rotating shaft, an outer ring 20 fitted on the inner periphery of the bearing housing 19 is provided, and the wide inner ring 21 is loosely fitted on the rotating shaft 22. There is known a fixing device 23 provided in the inner ring wide portion 21 a for preventing the rotation of the shaft 21 from rotating about the rotating shaft 22.

The fixing device 23 includes two set screws 24 and an inner ring wide portion 21a in which screw holes 25 are formed, and the screw holes 25 are spaced by 120 ° in the circumferential direction around the bearing center axis. It is formed in two places. In addition, the fixing device 23 screws the set screw 24 into the inner surface of the screw fixing hole 25 and presses the set screw 24 against the rotating shaft 22 with a screw tightening force, thereby causing the wide inner ring 21 to move against the rotating shaft 22. It is preventing rotation. The fixing device 23 can adjust the tightening force of the set screw 24 by turning the set screw 24 with a hexagon wrench or the like (Patent Document 1).
Japanese Patent Application Laid-Open No. 08-232950

  In the rolling bearing, the set screw 24 is screwed into the screw-fastening hole 25 and pressed against the rotary shaft 22, and therefore, a force is applied to the wide inner ring 21 from the set screw 24 radially outward. Therefore, when the set screw 24 is tightened strongly, the portion where the two set screws 24 and the screwing holes 25 are screwed together expands radially outward, and FIG. 4 shows the deformation of the raceway surface of the wide inner ring 21 in a graph. Thus, the raceway surface of the wide inner ring 21 is deformed into a heart shape. In this way, if there is a portion where the contact surface pressure with the raceway surface locally increases during the revolution of the rolling element, there is a risk of early breakage. Therefore, the set screw 24 could not be tightened strongly.

  The problem to be solved by the present invention is to prevent deformation of the raceway surface of the wide inner ring even if the set screw is tightened strongly.

  In order to solve the above-described problems, a rolling bearing according to the present invention includes an outer ring and a wide inner ring, and prevents the wide inner ring from rotating with respect to the rotary shaft in a state where the wide inner ring is loosely fitted to the rotary shaft. Assuming that the fixing device is attached to the inner ring wide portion, the fixing device includes a set screw, the inner ring wide portion formed so as to penetrate the screw through hole in the radial direction, and an annular shape that fits on the outer periphery of the inner ring wide portion. A screw hole that penetrates in the radial direction is formed in the annular member, and the set screw is screwed in the state where the screw hole and the screw through hole are communicated in the radial direction. The annular member is screwed into the inner surface of the working hole and is inserted into the threaded hole, and the set screw is pressed against the rotating shaft with a screw tightening force, so that the annular member is prevented from rotating with respect to the rotating shaft. Members and said The female thread is to that to be detent with respect to the rotation axis of the wide inner ring.

  By doing so, in the rolling bearing of the present invention, the set screw and the screw through hole of the wide inner ring are not screwed together, so that a force that pushes radially outward from the set screw to the wide inner ring is unlikely to act. Therefore, even if the set screw is tightened strongly, deformation of the raceway surface of the wide inner ring can be prevented.

  The two set screws can be arranged at two positions spaced 120 ° in the circumferential direction around the bearing central axis. In this way, since a force is applied radially outward from the two set screws to the female screw of the screw hole, the circumferential position at 120 ° intervals from each of the two set screws. Thus, the annular member can be pressed against the rotating shaft via the wide inner ring, and the annular member and the wide inner ring can be simultaneously prevented from rotating with respect to the rotating shaft. For this reason, it is only necessary to tighten the set screw with the same two as in the conventional case.

  If the fitting between the annular member and the inner ring wide portion is a clearance fit, the fitting between the annular member and the inner ring wide portion and the alignment of the screw-through hole and the screwing hole can be easily performed. The clearance between the annular member and the inner ring wide portion is not the clearance in the range defined in the JIS definition, and may have any size. Since there is a gap in the fitting state of the annular member and the inner ring wide part, when the annular member presses the wide inner ring against the rotating shaft by tightening two set screws, the contact range between the annular member and the wide inner ring is reduced in the circumferential direction. The pressing pressure can be increased. Even if the pressing pressure is increased, the shape of the wide inner ring is maintained by the rotating shaft in this portion, so there is no fear of the raceway surface being deformed.

  In these configurations, grease can be applied to the fitting surface of the inner ring wide portion and the annular member, or grease can be applied to the fitting surface of the inner ring wide portion and the rotating shaft. If it does in this way, fretting which arises on a fitting surface will be controlled.

  If a mineral oil-based grease is used as the grease, the oil film strength of the grease is increased, so that the fretting suppression effect is enhanced. Examples of mineral oil grease include Albania manufactured by Showa Shell.

  In these configurations, a pipe member made of a material having a lower friction than the material of the inner ring can be interposed between the screw hole and the set screw. If it does in this way, it will become difficult to generate stick slip between a set screw and a pipe member, and generation of sound by stick slip will be prevented.

  If the pipe member is made of polyacetal or polyamide, the strength and wear resistance of the pipe member can be increased.

  Further, the rolling bearing of the present invention is suitable for a bearing unit because it assumes that a wide inner ring is fitted with a clearance. The bearing unit is obtained by attaching a rolling bearing to a bearing box in advance. The bearing unit is generally developed as a general-purpose product having various inner ring inner diameters. The user selects a bearing unit according to the specifications of the rotating shaft. For this reason, high-precision fitting between the rotating shaft and the inner ring cannot be expected, and the inner ring of the bearing unit is premised on clearance fitting. The user performs torque management so as not to overtighten the set screw when fixing the inner ring, but the torque management is not always performed with high accuracy. Since the rolling bearing of this invention can make tightening of a set screw strong, torque management is easy.

  In the rolling bearing according to the present invention, since the set screw is screwed onto the annular member as described above, the raceway surface of the wide inner ring can be prevented from being deformed even if the set screw is strongly tightened.

  A bearing unit 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view cut along an axial plane of a bearing unit 1 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view cut along a radial plane passing through the inner ring wide portion 5a of FIG. As shown in FIGS. 1 and 2, the bearing unit 1 is obtained by attaching a rolling bearing to a bearing box 2. The rolling bearing includes an outer ring 3 fitted on the inner periphery of the bearing housing 2, a wide inner ring 5 fitted in the rotary shaft 4 with a clearance, and a plurality of rolling elements 6 interposed between the wide inner ring 5 and the outer ring 3. And a fixing device 7 for preventing the wide inner ring 5 from rotating with respect to the rotating shaft 4. The fixing device 7 is provided in a cylindrical inner ring wide portion 5 a constituting a portion protruding in the axial direction from the outer ring 3 of the wide inner ring 5.

  The fixing device 7 includes two set screws 8, an inner ring wide portion 5a formed so as to penetrate the cylindrical screw-through hole 9 in the radial direction, and an annular member 11 that is loosely fitted to the outer periphery of the inner ring wide portion 5a. Consists of. The inner surface of the screw hole 9 is formed of a cylindrical pipe member 10. In the annular member 11, a screwing hole 12 for screwing the set screw 8 into the inner surface penetrates in the radial direction. The screw-fastening holes 12 and the screw-through holes 9 are formed at two locations with a 120 ° interval in the circumferential direction around the bearing center axis.

  The two set screws 8 are screwed into the screw holes 9 by screwing the two screw holes 12 and the two screw holes 9 with the female threads of the screw holes 12 in a state where the two screw holes 8 are communicated in the radial direction. Inserted. When the screwing is further advanced, the tip 8a of the set screw 8 is pressed against the rotating shaft 4 with a screw tightening force. Therefore, the annular member 11 is pressed against the rotating shaft 4 via the wide inner ring 5 at a position on the circumferential direction at a distance of 120 ° from each of the two set screws 8, 8. The inner ring 5 is simultaneously prevented from rotating with respect to the rotating shaft 4. For this reason, the set screws 8, 8 need only be tightened with the same two screws.

  Moreover, even if the annular member 11 is deformed by a force that pushes radially outward from the set screw 8 to the female screw of the screw fastening hole 12, the annular member 11 is deformed by the clearance between the annular member 11 and the inner ring wide portion 5a. The contact range between the member 11 and the inner ring wide portion 5a is reduced in the circumferential direction. For this reason, the pressing pressure of the annular member 11 and the wide inner ring 5 can be increased. Even if the pressing pressure is increased, the shape of the wide inner ring 5 is maintained by the rotating shaft 4 in this portion, so there is no concern that the raceway surface is deformed.

  The pipe member 10 is formed of a material having a lower friction than that of the wide inner ring 5. Therefore, stick slip is less likely to occur between the set screw 8 and the pipe member 10 during operation of the bearing unit 1, and generation of sound due to stick slip is prevented. For example, the wide inner ring 5 is generally formed of a ferrous metal such as bearing steel. For this reason, as a low-friction material, for example, polyacetal or polyamide is preferable. This is because if the pipe member 10 is made of polyacetal or polyamide, the strength and wear resistance of the pipe member 10 can be enhanced while having lower friction than iron-based metals. Note that the pipe member 10 may be formed of a resin material that is particularly excellent in low friction so that stick-slip does not occur.

  Grease is applied to the fitting surface between the inner ring wide portion 5 a and the annular member 11 and the fitting surface between the inner ring wide portion 5 a and the rotating shaft 4. Therefore, the occurrence of fretting on the mating surface is suppressed. As the grease, for example, mineral oil-based grease is preferably used. This is because the oil film strength of grease is high and the fretting suppression effect is high.

  In this embodiment, since the set screw 8 and the inner surface of the screw-through hole 9 are not screwed together, the force pushing from the set screw 8 outward in the radial direction is unlikely to act on the wide inner ring 5. Therefore, even if the set screw 8 is strongly tightened, the raceway surface of the wide inner ring 5 is not easily deformed. As a result, the wide inner ring 5 and the rolling element 6 are not easily damaged.

  In the above-described embodiment, the set screws 8 are provided at two locations spaced by 120 ° in the circumferential direction around the bearing central axis of the annular member 11, but 120 in the circumferential direction around the bearing central axis of the annular member 11. Set screws 8 may be provided at three positions with an interval of °.

  Further, in the above-described embodiment, the set screw 8 is screwed into the screwing hole 12 having the internal thread formed on the inner surface. You may make it do.

Sectional drawing cut | disconnected by the axial plane of the bearing unit of embodiment of this invention Sectional view cut along a radial plane passing through the inner ring wide portion of FIG. Sectional view showing a conventional bearing unit Diagram showing the amount of deformation of the track diameter of the wide inner ring

Explanation of symbols

2 Bearing housing 3 Outer ring 4 Rotating shaft 5 Wide inner ring 5a Inner ring wide part 7 Fixing device 8 Set screw 9 Screw through hole 10 Pipe member 11 Annular member 12 Screw fixing hole

Claims (9)

An outer ring (3) and a wide inner ring (5) are provided, and the wide inner ring (5) is rotated with respect to the rotary shaft (4) in a state where the wide inner ring (5) is loosely fitted to the rotary shaft (4). In the rolling bearing provided with the fixing device (7) for stopping in the inner ring wide portion (5a),
The fixing device (7) includes a set screw (8), an inner ring wide portion (5a) formed so as to penetrate the screw hole (9) in a radial direction, and an outer periphery of the inner ring wide portion (5a). An annular member (11) to be fitted is formed, and a screwing hole (12) penetrating in the radial direction is formed in the annular member (11), and the screwing hole (12) and the screw through hole (9) are formed. And the set screw (8) is screwed into the inner surface of the screw hole (12) and fitted into the screw hole (9), and the set screw (8) is inserted into the screw hole (9). The annular member (11) is prevented from rotating with respect to the rotating shaft (4) by being pressed against the rotating shaft (4) with a screw tightening force, and the annular member (11) and the set screw (8) are used. The wide inner ring (5) is prevented from rotating with respect to the rotating shaft (4). Rolling bearing, characterized in that.   The rolling bearing according to claim 1, wherein the two set screws (8) are arranged at two positions spaced 120 ° in a circumferential direction around the bearing central axis.   The rolling bearing according to claim 2, wherein the fitting of the annular member (11) and the inner ring wide portion (5a) is a clearance fit.   The rolling bearing according to any one of claims 1 to 3, wherein grease is applied to a fitting surface between the inner ring wide portion (5a) and the annular member (11).   The rolling bearing according to any one of claims 1 to 4, wherein grease is applied to a fitting surface between the inner ring wide portion (5a) and the rotating shaft (4).   The rolling bearing according to claim 4 or 5, wherein a mineral oil-based grease is used as the grease.   A pipe member (10) made of a material having a lower friction than the material of the wide inner ring (5) is interposed between the screw-through hole (9) and the set screw (8). The rolling bearing according to any one of claims 1 to 6.   The rolling bearing according to claim 7, wherein the pipe member is made of polyacetal or polyamide.   9. A bearing unit comprising the rolling bearing according to claim 1 attached to a bearing box (2).

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