Rolling bearings

Abstract

To ensure fixing force acting on a protective member even when a stop ring for fixing an annular protection member to a fitting part of a bearing ring is attached to a stop ring groove of the bearing ring at an angle with respect to a radial direction.SOLUTION: In a stop ring groove 9 of a bearing ring 2, a cross-sectional shape of a groove bottom part 9c connecting a tapered surface 9a that receives a stop ring 6 from the outside in an axial direction and a flat surface 9b that is a portion facing the tapered surface 9a in the axial direction, is formed into a curved shape in a direction away from the stop ring 6 in a radial direction, so that even when the stop ring 6 is attached to the stop ring groove 9 at an angle with respect to a radial direction, a gap 13 in the radial direction is secured between the groove bottom part 9c and the stop ring 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006]

[0001] This invention relates to a rolling bearing capable of fixing an annular protective member such as a seal or a shield to a raceway ring.

Background Art

[0002] Conventionally, in order to prevent water and foreign matter from entering the inside of a rolling bearing, a protective member such as a seal or a shield is fixed to the raceway ring of the rolling bearing, and the bearing inner space between the inner and outer rings is sealed or generally covered with the protective member.

[0003] As this type of rolling bearing, there is one provided with a raceway ring having a stepped fitting portion that receives the peripheral edge portion of the protective member from the radial direction and the raceway surface side, and a retaining ring groove into which a retaining ring can be fitted. Among the retaining ring grooves, the portion that receives the retaining ring from the axially outer side has a tapered surface that is inclined so that the groove width becomes narrower as it approaches the groove bottom. Further, the portion facing the tapered surface in the axial direction and the groove bottom portion connecting the tapered surface are substantially cylindrical surfaces and are located at positions facing the retaining ring in the radial direction. A radial gap is set between the groove bottom portion and the retaining ring (Patent Document 1).

[0004] In the rolling bearing disclosed in Patent Document 1, by fitting the retaining ring to the tapered surface of the retaining ring groove, an axial component force that presses the retaining ring against the fitting portion is generated at the contact portion between the retaining ring that tends to elastically restore in the radial direction and the tapered surface, and the protective member can be fixed to the fitting portion. (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a fixing structure for a protective member, such as that described in Patent Document 1, it is preferable to set the contact position between the tapered surface of the retaining ring groove and the retaining ring near the bottom of the groove in order to obtain the aforementioned axial force component within the limited width and depth of the retaining ring groove.

[0007] However, if the retaining ring contacts the bottom of the retaining ring groove, the axial force required to secure the protective member to the fitting portion decreases. In particular, if the retaining ring is mounted at an angle to the radial direction, there is a concern that the corners of the retaining ring will contact the bottom of the groove, and insufficient fixing force will be obtained to act on the protective member.

[0008] In light of the above-mentioned background, the problem that this invention aims to solve is to ensure a fixing force acting on the protective member even when the retaining ring for fixing the annular protective member to the fitting portion of the raceway is attached to the retaining ring groove of the raceway at an angle with respect to the radial direction. [Means for solving the problem]

[0009] To achieve the above objectives, this invention provides a rolling bearing comprising a raceway, a protective member having a peripheral edge that can be fitted into the raceway from the axial direction, and a retaining ring for fixing the protective member fitted into the raceway, wherein the raceway has a stepped fitting portion that receives the peripheral edge of the protective member from the radial direction and the raceway surface side, and a retaining ring groove into which the retaining ring can be fitted, and the portion of the retaining ring groove that receives the retaining ring from the axially outer side has a tapered surface that is inclined so as to narrow the groove width as it approaches the bottom of the groove, the bottom of the groove connecting the portion facing the tapered surface in the axial direction and the tapered surface is located radially opposite to the retaining ring, and a radial gap is set between the bottom of the groove and the retaining ring, and the cross-sectional shape of the bottom of the groove is a curved shape that is bent radially away from the retaining ring.

[0010] As described above, the cross-sectional shape of the groove bottom in the retaining ring groove is curved away from the retaining ring in the radial direction. This causes the groove bottom to become deeper than the continuous portion with the tapered surface, increasing the radial gap between the groove bottom and the retaining ring. Therefore, even if the retaining ring is mounted at an angle with respect to the radial direction, contact between the corners of the retaining ring and the groove bottom can be avoided, thereby ensuring a fixing force acting from the retaining ring to the protective member.

[0011] The cross-sectional shape of the groove bottom is preferably an arc shape that is continuous in the tangential direction with both the portion facing the tapered surface in the axial direction and the tapered surface itself. This makes turning of the groove bottom easier.

[0012] The raceway has an end face that defines one end of the raceway's width and a groove shoulder that connects the retaining ring groove and the end face, and the fitting portion has a circumferential surface that receives the peripheral edge of the protective member in the radial direction and a side surface that receives the peripheral edge of the protective member in the axial direction, and when the width between the end face of the raceway and the side surface of the fitting portion is W and the radius of curvature of the cross-sectional shape of the groove bottom is R, it is preferable that the radius of curvature R is set to a dimension of 10% or more and 20% or less of the width W. In this way, it is possible to avoid contact between the retaining ring and the groove bottom while minimizing the reduction in wall thickness at the groove bottom due to the arc-shaped cross-section of the groove bottom of the retaining ring groove. [Effects of the Invention]

[0013] By adopting the above configuration, this invention ensures that a fixing force acts on the protective member even when the retaining ring for fixing the annular protective member to the fitting portion of the raceway is attached to the retaining ring groove of the raceway at an angle with respect to the radial direction. [Brief explanation of the drawing]

[0014] [Figure 1] A cross-sectional view showing the vicinity of the retaining ring groove of a rolling bearing according to an embodiment of this invention. [Figure 2] Cross-sectional view showing a rolling bearing according to an embodiment of this invention. [Modes for carrying out the invention]

[0015] A rolling bearing according to an embodiment of this invention will be described based on the attached drawings.

[0016] The rolling bearing shown in Figures 1 and 2 comprises an inner raceway 1, an outer raceway 2, rolling elements 3 interposed between the inner and outer raceway 1 and 2, a cage 4 that holds the rolling elements 3, an annular protective member 5 that seals the inside of the bearing from the outside, and a retaining ring 6 that fixes the protective member 5 to the raceway 2.

[0017] Hereinafter, the direction along the bearing's central axis CL will be simply referred to as the "axial direction," the direction perpendicular to the bearing's central axis CL will be simply referred to as the "radial direction," and the direction around the bearing's central axis CL will be simply referred to as the "circumferential direction." Furthermore, the virtual plane containing the bearing's central axis CL will be simply referred to as the "axial plane," and the virtual plane perpendicular to the bearing's central axis CL will be simply referred to as the "radial plane." Each figure shows a cross-section on the axial plane. In each figure, the axial direction corresponds to the left-right direction, and the radial direction corresponds to the up-down direction.

[0018] The protective member 5 is a seal having a peripheral portion 7 that can be fitted onto the raceway ring 2 from the axial direction. The peripheral portion 7 consists of the peripheral portion of a core metal to which rubber forming a seal lip is attached. The axial sides of the peripheral portion 7 are flat surfaces aligned with the radial direction. The protective member 5 does not have a slit for inserting a feeler gauge. Although the protective member 5 is exemplified as having a contact-type seal lip, it can also be a non-contact seal or shield.

[0019] The rolling bearing in the illustrated example is a sealed, self-aligning roller bearing, but it can be replaced with a radial bearing of any appropriate type, such as a cylindrical roller bearing, tapered roller bearing, or ball bearing.

[0020] The track wheel 2 is an annular bearing component integrally having a stepped fitting portion 8 that receives the peripheral edge portion 7 of the protection member 5 from the radial direction and the axial direction, a retaining ring groove 9 into which the retaining ring 6 can be fitted, a raceway surface 10, an end surface 11 that defines one end of the width of the track wheel 2, and a groove shoulder portion 12 that connects between the tapered surface 9a of the retaining ring groove 9 and the end surface 11.

[0021] The fitting portion 8 is formed by a peripheral surface 8a of the fitting portion 8 that receives the peripheral edge portion 7 in the radial direction and a side surface 8b of the fitting portion 8 that receives the peripheral edge portion 7 in the axial direction from the side of the raceway surface 10 of the track wheel 2. The peripheral surface 8a is a cylindrical surface extending over the entire circumference in the circumferential direction. The side surface 8b is a flat surface along the radial direction.

[0022] The fitting portion 8 and the retaining ring groove 9 are located only between the raceway surface 10 and the end surface 11. This is to ensure the bearing rigidity when receiving a heavy load on the raceway surface 10.

[0023] The diameter of the groove shoulder portion 12 is set to the same diameter as the diameter of the peripheral surface 8a of the fitting portion 8 or a dimension with a diameter difference away from the peripheral edge portion 7 of the protection member 5 with respect to the peripheral surface 8a. This is to prevent the peripheral edge portion 7 of the protection member 5 from being axially caught by the track wheel 2 when the protection member 5 is axially attached and detached to and from the fitting portion 8, making it easy to attach and detach the protection member 5 and keeping the protection member 5 in a reusable state during its attachment and detachment.

[0024] In the retaining ring groove 9, the portion that receives the retaining ring 6 from the axial outside has a tapered surface 9a that is inclined so that the groove width becomes narrower as it approaches the groove bottom.

[0025] In the retaining ring groove 9, the portion facing the tapered surface 9a in the axial direction has a flat surface 9b along the radial direction. The outer side surface in the axial direction of the peripheral edge portion 7 fitted to the fitting portion 8 protrudes axially outward from the flat surface 9b. This is to prevent the contact between the retaining ring 6 and the peripheral edge portion 7 from being inhibited by the flat surface 9b.

[0026] In the retaining ring groove 9, the groove bottom portion 9c that connects the tapered surface 9a and the flat surface 9b is located at a position facing the retaining ring 6 in the radial direction.

[0027] The retaining ring 6 consists of an annular metal spring that is interrupted at one point in the circumferential direction. In the illustrated example, the retaining ring 6 is a C-shaped concentric retaining ring with a rectangular cross-sectional shape. Each figure shows the retaining ring 6 tilted with respect to the radial direction and mounted in the retaining ring groove 9. The retaining ring 6 is fitted into the retaining ring groove 9 so as to be interposed between the peripheral edge 7 of the protective member 5 and the tapered surface 9a, in a state where its diameter has been reduced from its natural state. The retaining ring 6 fitted into the retaining ring groove 9 fixes the peripheral edge 7, which is fitted into the fitting portion 8 of the raceway ring 2, to the raceway ring 2. The retaining ring 6 may also be pre-formed with a shape that curves toward the peripheral edge 7 of the protective member 5 around the contact portion with the tapered surface 9a in order to provide an axial spring action between the axially outer side surface of the peripheral edge 7 and the tapered surface 9a.

[0028] A radial gap 13 is provided between the groove bottom 9c of the retaining ring groove 9 and the retaining ring 6. The gap 13 is a space that allows the elastic rebound of the retaining ring 6 when the retaining ring 6 is in contact with the tapered surface 9a and the axially outer side surface of the peripheral edge 7 of the protective member 5, and generates an axial component force that is applied from the retaining ring 6 to the peripheral edge 7 of the protective member 5 at the contact point between the tapered surface 9a and the retaining ring 6. When the retaining ring 6 is fitted into the retaining ring groove 9, it contacts the retaining ring groove 9 only with its tapered surface 9a. Since a radial gap 13 is provided between the groove bottom 9c of the retaining ring groove 9 and the retaining ring 6, the elastic rebound force of the retaining ring 6 is received at the tapered surface 9a, and the resulting axial component force is applied from the retaining ring 6 to the peripheral edge 7 of the protective member 5, thereby pressing the peripheral edge 7 axially toward the side surface 8b of the fitting portion 8, making it possible to firmly fix the protective member 5 to the raceway ring 2.

[0029] Here, if we consider the width between the end face 11 of the raceway ring 2 and the side surface 8b of the fitting portion 8 to be W, then the width W corresponds to the axial distance between the radial plane tangent to the side surface 8b and the radial plane tangent to the end face 11. The thickness of the retaining ring 6 is set to a dimension of 25% to 50% of the width W. Furthermore, the thickness of the retaining ring 6 is set to be greater than the thickness of the peripheral edge 7. These settings are intended to increase the elastic repulsive force by making the thickness of the retaining ring 6 large within the limited width W, while also ensuring the strength of the groove shoulder 12 by avoiding a narrowing of the width of the groove shoulder 12 (minimum width from the end face 11). The thickness of the retaining ring 6 corresponds to the plate thickness of the material of the retaining ring 6. The thickness of the peripheral edge 7 of the protective member 5 corresponds to the plate thickness of the material of the peripheral edge 7.

[0030] In order to ensure a groove width for the retaining ring groove 9 that makes it easy to fit the retaining ring 6 into the groove 9 within a limited width W, and to effectively generate an axial component force by receiving the elastic repulsive force of the retaining ring 6 on the tapered surface 9a, the acute taper angle that the tapered surface 9a makes with respect to the radial direction is set to an angle of 5° or more, more preferably 10° or more. Furthermore, in order to prevent the retaining ring 6 from sliding on the tapered surface 9a and moving outward in the axial direction, and to ensure the strength of the groove shoulder 12 by avoiding a narrowing of the width of the groove shoulder 12, the acute taper angle that the tapered surface 9a makes with respect to the radial direction is set to an angle of 25° or less, more preferably 20° or less.

[0031] The cross-sectional shape of the groove bottom 9c of the retaining ring groove 9 is a curved shape that curves radially away from the retaining ring 6. The cross-sectional shape of the groove bottom 9c is the shape of the line segment formed by the entire groove bottom 9c at an arbitrary point in the circumferential direction when the groove bottom 9c is cut by an axial plane. The groove bottom 9c has the illustrated cross-sectional shape along its entire circumference.

[0032] Compared to the case where the cross-sectional shape of the groove bottom of the retaining ring groove is a straight line extending axially from the continuity with the tapered surface 9a, the cross-sectional shape of the groove bottom 9c of the retaining ring groove 9 in the illustrated example is a curved shape that curves away from the retaining ring 6 radially, thereby increasing the radial gap 13 between the retaining ring 6 and the groove bottom 9c. As a result, even when the retaining ring 6 is attached to the retaining ring groove 9 at an angle as shown in the illustration, a radial gap 13 is secured between the corner on the outer circumference side of the retaining ring 6 and the fitting portion 8 side and the groove bottom 9c, thus avoiding contact between the corner of the retaining ring 6 and the groove bottom 9c. Therefore, even when the retaining ring 6 is attached to the retaining ring groove 9 at an angle as shown in the illustration, the fixing force acting from the retaining ring 6 on the peripheral edge 7 of the protective member 5 is secured to be large enough to fix the peripheral edge 7 to the fitting portion 8.

[0033] The cross-sectional shape of the groove bottom 9c is an arc that is continuous in the tangential direction with both the tapered surface 9a and the flat surface 9b. That is, in its cross-sectional shape, the groove bottom 9c forms a circular arc with a single radius of curvature R, and the distance from the continuity between the tapered surface 9a and the groove bottom 9c to the center of curvature of the groove bottom 9c coincides with the radius of curvature R, and the distance from the continuity between the flat surface 9b and the groove bottom 9c to the center of curvature of the groove bottom 9c also coincides with the radius of curvature R.

[0034] The groove bottom 9c is turned. During this turning process, the NC lathe tool (not shown) only needs to be controlled based on circular arc interpolation of a single radius of curvature R between the continuous section between the tapered surface 9a and the groove bottom 9c, and between the continuous section between the flat surface 9b and the groove bottom 9c. This simplifies the construction of a control program for turning the groove bottom 9c, thereby facilitating the turning of the groove bottom 9c. In other words, the turning process for the groove bottom 9c can be easily determined, resulting in lower processing costs.

[0035] The radius of curvature R in the cross-sectional shape of the groove bottom 9c is set to a dimension of 10% or more of the width W. If the radius of curvature R is less than 10% of the width W, the radial wall thickness at the bottom of the retaining ring groove 9 will be thin, raising concerns about a decrease in strength at this point. The bottom of the retaining ring groove 9 is the deepest part of the radial depth of the groove bottom 9c relative to the diameter of the groove shoulder 12, and the radial wall thickness at this point corresponds to the radial distance between the outer circumference of the raceway ring 2 and the bottom of the retaining ring groove 9 in the illustrated example.

[0036] Furthermore, the radius of curvature R in the cross-sectional shape of the groove bottom 9c is set to a dimension of 20% or less of the width W. If the radius of curvature R exceeds 20% of the width W, the radial depth of the retaining ring groove 9 relative to the diameter of the groove shoulder 12 becomes shallow, raising concerns that contact between the retaining ring 6 and the groove bottom 9c may occur, resulting in a loss of the fixing force acting from the retaining ring 6 to the peripheral edge 7 of the protective member 5.

[0037] As described above, this rolling bearing comprises a raceway ring 2, a protective member 5 having a peripheral edge portion 7 that can be fitted onto the raceway ring 2 from the axial direction, and a retaining ring 6 that fixes the protective member 5 fitted onto the raceway ring 2 to the raceway ring 2. The raceway ring 2 has a stepped fitting portion 8 that receives the peripheral edge portion 7 of the protective member 5 from the radial direction and from the raceway surface 10 side, and a retaining ring groove 9 into which the retaining ring 6 can be fitted. Of the retaining ring groove 9, the portion that receives the retaining ring 6 from the axially outer side (the axially opposite side from the raceway surface 10) has a tapered surface 9a that is inclined so that the groove width narrows as it approaches the bottom of the groove. The bottom of the groove 9c, which connects the flat surface 9b, which is the portion facing the tapered surface 9a in the axial direction, and the tapered surface 9a, is located radially opposite to the retaining ring 6, and a radial gap 13 is set between the bottom of the groove 9c and the retaining ring 6.

[0038] In this rolling bearing, the cross-sectional shape of the groove bottom 9c is curved away radially from the retaining ring 6, so that the groove bottom 9c becomes deeper than the continuous portion with the tapered surface 9a, increasing the radial gap 13 between the groove bottom 9c and the retaining ring 6. This prevents contact between the corners of the retaining ring 6 and the groove bottom 9c even when the retaining ring 6 is mounted at an angle to the retaining ring groove 9 with respect to the radial direction, thereby ensuring a fixing force acting from the retaining ring 6 to the protective member 5.

[0039] Furthermore, because the cross-sectional shape of the groove bottom 9c of this rolling bearing is an arc shape that is tangentially continuous with both the flat surface 9b and the tapered surface 9a, which face the tapered surface 9a in the axial direction, turning of the groove bottom 9c is facilitated, and consequently, a rolling bearing with reduced processing costs can be produced.

[0040] Furthermore, in this rolling bearing, the raceway ring 2 has an end face 11 that defines one end of the width of the raceway ring 2 and a groove shoulder 12 that connects the retaining ring groove 9 and the end face 11, and the fitting portion 8 has a circumferential surface 8a that receives the peripheral edge 7 of the protective member 5 in the radial direction and a side surface 8b that receives the peripheral edge 7 of the protective member 5 in the axial direction, and when the width between the end face 11 of the raceway ring 2 and the side surface 8b of the fitting portion 8 is W, and the radius of curvature of the cross-sectional shape of the groove bottom 9c is R, the radius of curvature R is set to a dimension of 10% to 20% of the width W, thereby making it possible to avoid contact between the retaining ring 6 and the groove bottom 9c while minimizing the reduction in wall thickness at the bottom of the groove due to the arc-shaped cross-section of the groove bottom 9c of the retaining ring groove 9.

[0041] In the illustrated example, a fitting portion 8 and a retaining ring groove 9 are formed on the outer raceway 2, but it is also possible to form a fitting portion and a retaining ring groove on the inner raceway and attach a retaining ring to that groove.

[0042] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Accordingly, the scope of the invention is indicated by the claims and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of symbols]

[0043] 2 Raceway ring 5. Protective component 6. Retaining ring 7 Peripheral area 8. Fitting part 8a Peripheral surface 8b side 9 Retaining ring groove 9a Tapered surface 9b flat surface 9c groove bottom 10 Raceway surface 11 End face 12 Groove shoulder 13 gaps

Claims

1. The system comprises a raceway ring, a protective member having a peripheral edge that can be fitted onto the raceway ring from an axial direction, and a retaining ring for fixing the protective member fitted onto the raceway ring to the raceway ring. The raceway has a stepped fitting portion that receives the peripheral edge of the protective member from the radial direction and the raceway surface side, and a retaining ring groove into which the retaining ring can be fitted. Of the retaining ring groove, the portion that receives the retaining ring from the axial outside has a tapered surface that is inclined so as it approaches the bottom of the groove, and the portion facing the tapered surface in the axial direction and the bottom of the groove connecting the tapered surface are located radially opposite to the retaining ring. In a rolling bearing in which a radial gap is set between the groove bottom and the retaining ring, The cross-sectional shape of the groove bottom is curved in a direction away from the retaining ring in the radial direction. A rolling bearing characterized in that the cross-sectional shape of the groove bottom is an arc shape that is continuous in the tangential direction with both the portion facing the tapered surface in the axial direction and the tapered surface.

2. The raceway has an end face that defines one end of the width of the raceway, and a groove shoulder that connects the retaining ring groove and the end face. The fitting portion has a circumferential surface that receives the peripheral edge of the protective member in the radial direction, and a side surface that receives the peripheral edge of the protective member in the axial direction, The rolling bearing according to claim 1, wherein when the width between the end face of the raceway ring and the side surface of the fitting portion is W, and the radius of curvature of the cross-sectional shape of the groove bottom is R, the radius of curvature R is set to a dimension of 10% or more and 20% or less of the width W.

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