Bearing device

Abstract

The present invention provides a bearing device that improves the ease of installation of fastening members and suppresses the occurrence of bearing malfunctions caused by improper posture of fastening members. [Solution] The bearing device comprises an inner ring, an outer ring, and a plurality of rolling elements arranged between the inner ring and the outer ring, wherein the inner ring has an annular portion and an extension portion that protrudes axially from the inner diameter end face of the annular portion and has an axial slit formed therein, and a clamping member that is fitted onto the extension portion and clamps and fixes the extension portion to the shaft. A stepped portion is provided at the inner diameter end of the clamping member on the bearing side, into which the outer diameter end of the annular portion can be fitted.

Description

Technical Field

[0001] The present invention relates to a bearing device applied to a bearing unit used in, for example, general industrial machines and the like.

Background Art

[0002] Various bearing units with self-aligning properties have been proposed. In conventional bearing units, in order to simplify assembly with a shaft and the like, the inner diameter of the bearing and the shaft have a clearance fit, and as a fixing device for the bearing and the shaft, a set screw, an eccentric collar, or a taper adapter is generally used (Patent Documents 1 to 5). Among these, the set screw method is most often adopted. However, since it is inevitable that the clearance between the inner ring inner diameter and the shaft becomes the shaft misalignment with respect to the rotation center of the bearing when the set screw is tightened, there is a problem that the vibration increases as the rotational speed increases. The same problem exists when using an eccentric collar.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0004] For this reason, tapered adapter bearings are commonly used under high-speed rotation. This tapered adapter type eliminates the gap between the inner ring diameter and the shaft by tightening the tapered sleeve, thus eliminating misalignment and resulting in excellent rotational accuracy and low vibration. However, it has more parts than the bearings mentioned above, and furthermore, in order to use it with the same shaft diameter as other types, the internal structure changes and the overall bearing becomes larger, making it disadvantageous in terms of workability and dimensional constraints.

[0005] As a countermeasure, some methods, such as those described in Patent Document 1, use a clamping member (concentric collar 106) that allows the shaft and the bearing inner ring to be mounted concentrically. That is, as shown in Figure 6(a), the inner ring 101 comprises an annular portion 102 and an extension portion 103 that continuously protrudes axially from one end face on the inner diameter side of the annular portion 102 and has the same inner diameter as the annular portion 102. The extension portion 103 has multiple slits (cuts) 104 that extend axially formed in the circumferential direction, thereby having multiple claw portions 105 in the circumferential direction.

[0006] On the other hand, the concentric collar 106 is a retaining ring with a discontinuous gap (not shown) formed by cutting out one point in the circumferential direction. A fastening bolt 107 is screwed into this gap in the circumferential direction, bringing the two opposing ends across the gap closer together and reducing the gap by tightening. As a result, each claw portion 105 is pressed against the concentric collar 106 and reduced in diameter, allowing the shaft 108 to be fixed.

[0007] When tightening the concentric collar 106, the fastening bolts 107, which are provided in the circumferential direction as described above, are screwed in. However, since there is a clearance fit between the concentric collar 106 and the outer diameter of the extension 103, the position of the concentric collar 106 is unstable. In addition, a circumferential force is generated around the fastening bolts 107 in response to the screwing motion of the fastening bolts 107. As shown in Figure 6(b), this force causes the concentric collar 106 to tilt relative to the bearing. When the concentric collar 106 is tilted relative to the bearing, the amount of radial deformation (reduction in diameter) of the claw portion 105 due to the tightening of the concentric collar 106 decreases, and the bearing's shaft holding force cannot be obtained. If the bearing does not fully hold the shaft 108, the shaft 108 may slip, causing vibration, abnormal noise, etc.

[0008] Therefore, the present invention provides a bearing device that improves the ease of installation of the fastening member and suppresses the occurrence of bearing malfunctions caused by improper posture of the fastening member. [Means for solving the problem]

[0009] The present invention provides a bearing device comprising an inner ring, an outer ring, and a plurality of rolling elements disposed between the inner ring and the outer ring, wherein the inner ring has an annular portion and an extension portion that protrudes axially from the inner diameter side end face of the annular portion and has an axial slit formed thereon, and a clamping member fitted onto the extension portion and clamping and fixing the extension portion to the shaft, wherein the clamping member has a stepped portion at the inner diameter side end on the bearing side into which the outer diameter side end of the annular portion can be fitted.

[0010] In the bearing device of the present invention, a stepped portion is provided at the inner diameter end of the clamping member on the bearing side. This ensures that when the clamping member is tightened, the inner diameter surface of the clamping member at the stepped portion comes into contact with the outer diameter of the inner ring (i.e., the outer diameter end of the annular portion). In other words, the movement of the clamping member to tilt relative to the bearing during the tightening operation can be suppressed, and the posture of the clamping member during the tightening operation can be stabilized in the correct state (while maintaining concentricity with the extension portion). This suppresses tightening defects without reducing the amount of radial deformation (diameter reduction) of the extension portion, and prevents the bearing's shaft holding force from being impaired due to tightening defects.

[0011] Furthermore, the correct orientation of the clamping member (maintaining concentricity with the extension) includes cases where the centers of the clamping member and the extension perfectly coincide, as well as cases where there is a deviation that is within an acceptable margin of error. In other words, "mounting in the correct orientation" refers to a mounting state in which the bearing's axial holding force can be maintained, and if the bearing's axial holding force is not impaired, the clamping member can be said to be mounted in the correct orientation even if there is a tilt.

[0012] In the above configuration, it is preferable that the radial thickness of the extension portion is thinner than the maximum radial thickness of the annular portion. This increases the flexibility of the extension portion and enhances the fixing force between the extension portion and the shaft. In addition, the outer diameter end of the annular portion takes on a shoulder shape, making it easier to fit with the stepped portion.

[0013] In the above configuration, it is preferable that the axial depth of the stepped portion is greater than or equal to the axial dimension of the chamfer formed on the outer diameter side end of the annular portion. This ensures sufficient space for the outer diameter side end of the annular portion to enter the stepped portion, and further stabilizes the position of the fastening member during installation.

[0014] In the above configuration, it is preferable that the radial gap between the inner diameter surface of the clamping member at the stepped portion and the outer diameter end of the annular portion is larger than the gap between the inner diameter surface of the clamping member and the outer diameter surface of the extension portion. This prevents interference between the inner diameter surface of the clamping member at the stepped portion and the annular portion of the inner ring when the clamping member is tightened, thereby preventing the deformation of the extension portion from being hindered by such interference.

[0015] An opening may be provided in the extension. With this configuration, the rigidity of the extension can be reduced compared to the rigidity of the annular portion. This increases the fixing force between the inner diameter of the extension and the shaft when fixing the bearing to the shaft, compared to structures without an opening in the extension. Furthermore, since the machining range of the opening can be changed according to the area of ​​the extension, it can be applied to conventional extension shapes as well, providing even greater flexibility.

[0016] The outer circumferential surface of the outer ring may be alignably mounted on the bearing housing. In other words, this is applicable to bearings having such a self-aligning function. [Effects of the Invention]

[0017] This invention improves the ease of installation of a fastening member by stabilizing its position during fastening operations through the formation of a stepped portion. Furthermore, after fastening, it prevents the loss of bearing axial holding force due to improper fastening, thereby suppressing problems such as abnormal noise and vibration of the bearing caused by the poor position of the fastening member. Moreover, by forming a stepped portion only on one axial end of the fastening member, the fastening member has an asymmetrical shape, eliminating the need to visually check markings such as engravings to distinguish the front and back of the fastening member. This also has the advantage of eliminating the need for markings or laser markings displayed on the front of the fastening member. [Brief explanation of the drawing]

[0018] [Figure 1] This is a cross-sectional view of a bearing device according to the first embodiment of the present invention. [Figure 2] This is a perspective view of the inner ring that constitutes the bearing device. [Figure 3] It is an enlarged cross-sectional view of the main part of FIG. 1 above. [Figure 4] It is a cross-sectional view of a bearing device according to a second embodiment of the present invention. [Figure 5] It is a cross-sectional view of a bearing unit showing an example in which a bearing device according to any embodiment of the present invention is applied to the bearing unit. [Figure 6] A conventional bearing device is shown. (a) is a cross-sectional view of a state where a concentric collar, which is a fastening member, is not tilted with respect to the bearing, and (b) is a cross-sectional view of a state where the concentric collar is tilted with respect to the bearing.

Embodiments for Carrying out the Invention

[0019] Hereinafter, embodiments of the bearing device of the present invention will be described based on FIGS. 1 to 5. This bearing is applied to, for example, a bearing unit described later used in general industrial machines and the like as follows.

[0020] As shown in FIG. 1, the bearing device according to the first embodiment includes a bearing 1 and a fastening member 8. The bearing 1 is a ball bearing having an inner ring 2, an outer ring 3, rolling elements 4 such as a plurality of balls, a cage 5, seals 6, and a slinger 7. The inner and outer rings 2 and 3 are made of bearing steel, and the balls 4 are made of steel balls or the like. The inner ring 2 is formed wider than the outer ring 3 and includes an annular portion 10 and an extension portion 11 as will be described later. The inner ring inner diameter and the shaft 9 are, for example, clearance fits, and the extension portion 11 is attached to the shaft 9 by a fastening member 8 (concentric collar).

[0021] The outer peripheral surface 3b of the outer ring 3 is formed in a convex spherical shape, and the outer peripheral surface 3b of the outer ring 3 is slidably fitted to the spherical inner diameter portion of a bearing housing described later. Therefore, the outer peripheral surface 3b of the outer ring 3 is provided in the bearing housing so as to be self-aligning.

[0022] A plurality of rolling elements 4 are interposed between the raceways 2a and 3a of the inner and outer rings 2 and 3, and the cage 5 holds these rolling elements 4. Both ends of the bearing space of the inner and outer rings 2 and 3 are sealed by, for example, contact-type seals 6 and 6. Grease, which is a lubricating oil, is enclosed in the bearing space. [[ID=三十一]] [[ID=三十二]]

[0023] [[ID=三十三]] A slinger 7 is provided immediately outside each seal 6 in the axial direction to further enhance the sealing performance of the bearing space. Each slinger 7 is formed in an L-shape in cross-section, consisting of a cylindrical portion 7a that is fitted and fixed to the outer circumference of the inner ring, and a vertical plate portion 7b that extends radially outward from the axially inner end of the cylindrical portion 7a. The outer diameter end of the vertical plate portion 7b faces the inner circumference of the outer ring with a predetermined radial gap in between.

[0024] As shown in Figure 1, the inner ring 2 comprises an annular portion 10 positioned on the inner diameter side of the outer ring 3, and an extension portion 11 that continuously protrudes axially from one end face on the inner diameter side of the annular portion 10 and has the same inner diameter as the inner diameter 10a (see Figure 1) of the annular portion 10. As shown in Figures 1 and 2, the extension portion 11 has multiple slits (cuts) 18 extending axially formed in the circumferential direction (eight in the example shown in Figure 2), thereby forming eight claw portions 19 in the circumferential direction. The number of slits 18 between adjacent claw portions 19 in the circumferential direction is appropriately set according to the flexibility to be given to each claw portion 19, the bearing size, and other design specifications, and can be set to seven or fewer, or it can be increased to nine or more.

[0025] As shown in Figure 1, the radial thickness of the extension 11 is thinner than the maximum radial thickness of the annular portion 10, for example, about 50% of the maximum radial thickness of the annular portion 10. This increases the flexibility of the extension 11 and enhances the fixing force between the extension 11 and the shaft 9. In addition, the outer diameter end 13 of the annular portion 10 has a shoulder shape, making it easier to fit with the stepped portion 12, which will be described later.

[0026] The fastening member 8 has a circumferential gap (not shown) formed by a notch at one point in the circumferential direction, and is configured to be able to be reduced in diameter by this gap. By screwing the fastening bolt 23 into the gap portion of the fastening member 8 near the gap, both ends of the fastening member 8 are brought closer together and the gap is reduced. As a result the fastening member 8 is reduced in diameter, and the inner diameter 11a of the extension portion (see Figure 1) presses against the outer surface of the shaft 9, thereby easily and concentrically fixing the inner ring 2 and the shaft 9.

[0027] As shown in Figure 1, a stepped portion 12 is provided at the inner diameter end of the clamping member 8 on the bearing side. That is, as shown in Figure 3, the inner diameter side of the clamping member 8 has an axial surface 14 facing the tip side of the extension portion 11, a first tapered surface 15 that expands in diameter from the axial surface 14 toward the bearing side, and a second tapered surface 16 that further expands in diameter from the first tapered surface 15 toward the bearing side. The stepped portion 12 is formed on the bearing side of the inner diameter end of the clamping member 8, which is cut out from the second tapered surface 16. This stepped portion 12 allows the outer diameter end 13 of the annular portion 10 of the inner ring 2 to enter and is also capable of fitting with the shoulder-shaped outer diameter end 13.

[0028] By providing the stepped portion 12 described above, when the fastening member 8 is tightened, the inner diameter surface 17 of the fastening member 8 at the stepped portion 12 comes into contact with the outer diameter of the inner ring (i.e., the outer diameter end 13 of the annular portion 10). In other words, during the fastening operation, the movement of the fastening member 8 to tilt relative to the bearing 1 (for example, circumferential movement around the fastening bolt 23) can be suppressed, and the posture of the fastening member 8 during the fastening operation can be stabilized in the correct state (while maintaining concentricity with the extension portion 11). As a result, fastening defects can be suppressed without reducing the amount of radial deformation (reduction in diameter) of the extension portion 11, and the shaft holding force of the bearing 1 caused by fastening defects can be prevented.

[0029] Furthermore, the correct orientation of the clamping member 8 (maintaining concentricity with the extension 11) includes cases where the centers of the clamping member 8 and the extension 11 perfectly coincide, as well as cases where there is a deviation that is within an acceptable margin of error. In other words, "mounting in the correct orientation" refers to a mounting state in which the axial holding force of the bearing 1 can be maintained, and if the axial holding force of the bearing 1 is not impaired, the clamping member 8 can be said to be mounted in the correct orientation even if there is a tilt.

[0030] As shown in Figure 3, it is preferable that the axial depth D of the stepped portion 12 is greater than or equal to the axial dimension d of the chamfer 13a formed on the outer diameter side end 13 of the annular portion 10. This ensures sufficient space for the outer diameter side end 13 of the annular portion 10 to enter the stepped portion 12, and further stabilizes the position of the fastening member 8 during installation.

[0031] Furthermore, it is preferable that the radial gap δ1 between the inner diameter surface 17 of the clamping member 8 at the stepped portion 12 and the outer diameter surface 10b of the annular portion 10 of the inner ring 2 is larger than the gap δ2 between the inner diameter surface of the clamping member 8 (the axial surface 14, which is the innermost of the axial surface 14, the first tapered surface 15, and the second tapered surface 16) and the outer diameter surface 11b of the extension portion 11. This prevents interference between the inner diameter surface 17 of the clamping member 8 at the stepped portion 12 and the annular portion 10 of the inner ring 2 when the clamping member 8 is tightened, thereby preventing the deformation of the extension portion 11 from being hindered by such interference.

[0032] In the bearing device according to the present invention, the orientation of the clamping member 8 during the clamping operation is stabilized by the formation of the stepped portion 12, thereby improving the ease of mounting the clamping member 8. Furthermore, after clamping, it is possible to prevent the loss of the axial holding force of the bearing 1 due to improper clamping, and thus suppress problems such as abnormal noise and vibration of the bearing 1 caused by the improper orientation of the clamping member 8. In addition, by forming the stepped portion 12 only on one axial end of the clamping member 8, the clamping member 8 has an asymmetrical shape, and the front and back sides of the clamping member 8 can be identified without relying on visual confirmation of markings such as engravings. This also has the advantage of eliminating the need for engravings or laser markings displayed on the front of the clamping member 8.

[0033] Next, Figure 4 shows a bearing device of the second embodiment. In the bearing device of the second embodiment, each claw portion 19 of the extension portion 11 is provided with an opening 20. The opening 20 is a round through-hole that penetrates the claw portion 19 in the radial direction. However, the opening 20 is not limited to a round shape, and may be a square hole, for example. The axial position of the opening 20 is preferably located on the side of the raceway groove 2a of the inner ring 2 rather than the axial middle portion of the claw portion 19, and in Figure 4, it is provided at the base of the claw portion 19.

[0034] The axial length L1 of the opening 20 is preferably up to 50% of the axial length l1 of the claw portion 19. Furthermore, the circumferential length L2 of the opening 20 is preferably up to 60% of the circumferential length l2 of the claw portion 19. This helps to suppress a reduction in the contact area between the inner diameter of the claw portion 19 and the shaft 9. If the axial length L1 of the opening 20 exceeds 50% of the axial length l1 of the claw portion 19, or if the circumferential length L2 of the opening 20 exceeds 60% of the circumferential length l2 of the claw portion 19, the contact area between the inner diameter of the claw portion 19 and the shaft 9 decreases, making it difficult to maintain the fixing force between the inner diameter of the claw portion 19 and the shaft 9.

[0035] By adopting the above configuration, the bearing device of the second embodiment also provides the same effects as the bearing device of the first embodiment. Moreover, since the bearing device of the second embodiment has an opening 20 in the claw portion 19, the rigidity of the claw portion 19 can be reduced to that of the annular portion 10. As a result, the fixing force between the inner diameter surface 11a of the extension portion and the shaft 9 when fixing the bearing 1 to the shaft 9 is increased compared to structures in which the claw portion 19 does not have an opening 20. Furthermore, since the processing range of the opening 20 can be changed according to the area of ​​the extension portion 11, it can be applied to conventional extension portion shapes as well, providing even greater flexibility. Note that in the bearing device of the second embodiment shown in Figure 4, components similar to those in the bearing device of the first embodiment are denoted by the same reference numerals as in Figure 1, and their descriptions are omitted.

[0036] Figure 5 is a longitudinal cross-sectional view of a bearing unit 21 showing an example in which a bearing device according to one of the embodiments is applied to a bearing unit. The bearing unit 21 comprises a bearing housing 22, a bearing 1 that is alignably mounted in the bearing housing 22, and a clamping member 8. The inner circumference of the pillow-shaped bearing housing 22 is provided with a concave spherical inner diameter portion 22a. The bearing unit 21 has an alignment function by the outer peripheral surface 3b, which is the convex spherical outer ring outer diameter portion of the bearing 1, being slidably fitted into the spherical inner diameter portion 22a of the bearing housing 22. In the bearing unit shown in Figure 5, components similar to those of the bearing device of the first embodiment are denoted by the same reference numerals as in Figure 1, and their descriptions are omitted.

[0037] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. In the embodiments, the bearing 1 was a ball bearing, but it may be a tapered roller bearing, a cylindrical roller bearing, or the like. The number of claws 19 can be set arbitrarily. When multiple claws 19 are provided, the circumferential lengths of each claw 19 may be the same or different, and the axial length and circumferential width of each slit 18 may be the same or different. In addition, the seal 6 may be a non-contact seal, or the slinger 7 may be omitted. The axial and radial depths of the stepped portion 12 can be set arbitrarily according to the dimensions of the chamfer 13a of the outer diameter end portion 13, etc.

[0038] In the second embodiment, it is not necessary to provide openings 20 in all of the claw portions 19, and it is also possible to have an opening 20 in at least one of the claw portions 19. In this case, the number of processing steps can be reduced and manufacturing costs can be reduced compared to providing openings 20 in all of the claw portions 19. When multiple openings 20 are provided, the diameter and shape of each opening 20 may be the same or different. The openings 20 may be so-called counterbore-type non-through holes provided on the inner or outer circumferential surface of the claw portion 19. [Explanation of Symbols]

[0039] 1 bearing 2 Inner ring 3 Outer ring 4 balls 8. Fastening member 9 axes 10 Annular section 11 Extension 12 steps 13 Outer diameter end 13a Chamfer 19 slits 20 openings 22 Bearing housing Axial depth of the D-section d Axial dimension of the chamfer δ1 Radial clearance δ² radial clearance

Claims

1. A bearing comprising an inner ring, an outer ring, and a plurality of rolling elements disposed between the inner ring and the outer ring, wherein the inner ring has an annular portion and an extension portion that protrudes axially from the inner diameter end face of the annular portion and has an axial slit formed therein, A bearing device comprising a fastening member fitted onto the extension portion and fastening and fixing the extension portion to the shaft, A bearing device characterized in that a stepped portion is provided at the inner diameter end of the clamping member on the bearing side, into which the outer diameter end of the annular portion can be fitted.

2. The bearing device according to claim 1, characterized in that the radial wall thickness of the extension is thinner than the maximum radial wall thickness of the annular portion.

3. The bearing device according to claim 1, characterized in that the axial depth of the stepped portion is greater than or equal to the axial dimension of the chamfer formed on the outer diameter side end of the annular portion.

4. The bearing device according to claim 1, characterized in that the radial gap between the inner diameter surface of the clamping member in the stepped portion and the outer diameter end of the annular portion is larger than the gap between the inner diameter surface of the clamping member and the outer diameter surface of the extension portion.

5. The bearing device according to claim 1, characterized in that an opening is provided in the extension portion.

6. The bearing device according to claim 1, characterized in that the outer circumferential surface of the outer ring is alignably mounted on the bearing housing.

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