Sealed rolling bearings

Abstract

The rolling bearing is equipped with an annular seal that allows for efficient and highly accurate assembly, minimizing partial insertion failures of the annular seal's outer edge into the circumferential groove on the inner surface of the outer ring. [Solution] The sealing rolling bearing 1 is provided with an annular seal 5 which is reinforced with an annular core metal 5a and has a thickened portion 5b on its outer peripheral edge which is made of a rubber-like elastic material and can be fitted into and held in a circumferential groove 3b. The outer diameter φDs of the annular core metal 5a and the shoulder top surface 3c on the outer ring end face side of the side walls of the circumferential groove 3b are defined as the inner diameter φDe of the outer ring end, and the axial thickness Bs of the thickened portion 5b of the annular seal 5 satisfies the relationship shown by the formula (φDe-φDs) / 2≦0.3Bs.

Description

Technical Field

[0001] The present invention relates to a sealed rolling bearing provided with a seal that seals a bearing space.

Background Art

[0002] Generally, in a bearing space inside a rolling bearing such as a deep groove ball bearing, an annular seal for sealing the axial end of the bearing space is used to prevent foreign matters (such as moisture, metal powder, dust, etc.) from entering from the outside, or prevent lubricant and the like from leaking out of the bearing to the outside.

[0003] As shown in Fig. 5, the conventional sealed rolling bearing 10 is a well-known form as a counterbore ball bearing having circumferential grooves 3b at both ends of the inner peripheral surface of an outer ring 3, with one shoulder of the groove wall cut away.

[0004] The annular seal 11 assembled in such a sealed rolling bearing 10 is reinforced by embedding an annular cored bar 11a having a slightly smaller outer diameter than the main body inside an annular main body made of a rubber-like elastic material, a thick portion 11b is provided on an outer peripheral edge having rubber-like elasticity, and the annular seal 11 is fitted and held in a seal groove (circumferential groove 3b) formed on the inner peripheral surface of the outer ring 3.

[0005] Further, an inner peripheral edge portion of the annular seal 11 is provided with a seal lip (not shown), which is brought into contact with the rotating inner ring, or provided with a sealing function in a non-contact state with the inner ring via a labyrinth-shaped gap.

[0006] The assembly work of the annular seal 11 to the rolling bearing 10 of the outer ring 3 is performed as follows: the thick portion 11b is inserted toward the circumferential groove 3b so that the outer peripheral edge of the annular seal 11 exceeds the shoulder top surface 3c of the counterbore portion 3A, while positioning the thick portion 11b against the inner wall surface of the circumferential groove 3b in the insertion direction, the thick portion 11b is elastically deformed, compressed, and press-fitted into the circumferential groove 3b.

[0007] In such assembly work, in order to position the annular seal 11 in a predetermined position and to adequately hold the thickened portion 11b in the circumferential groove 3b, it is preferable to make the inner diameter of the top surface 3c of the shoulder portion that opens to the end face of the outer ring 3 of the rolling bearing 10 as large as possible.

[0008] However, in order for the outer ring 3 of the rolling bearing 10 to withstand axial pressure sufficiently when mounted, it is preferable that the inner diameter of the end of the outer ring 3 be small.

[0009] To satisfy such conflicting requirements, the difference in shoulder height on both sides of the seal groove in conventional sealed rolling bearings is designed to be as small as possible. Patent Document 1 discloses that "the difference in shoulder height A on both sides of the seal groove is set to be greater than half the thickness of the core metal and within (0.1 × ball diameter) (Patent Document 1)."

[0010] Furthermore, Patent Document 1 describes how, with respect to annular seals, the elastic deformability of the thickened portion of the outer edge is increased so that the outer edge of the core metal is bent from the flat portion toward the inside of the bearing, in order to perform the assembly work as efficiently as possible (paragraph

[0015] of the same document). [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2004-116687 [Overview of the project] [Problems that the invention aims to solve]

[0012] However, in the conventional rolling bearings with annular seals described above, the rigidity of the outer edge of the annular seal is determined solely by the elasticity of the rubber-like elastic material. Therefore, it is difficult to satisfy efficient assembly, sealing performance, and stable retention all at once. In particular, it has been difficult to sufficiently improve the workability of assembling the annular seal. For example, it has been difficult to efficiently perform assembly work with sufficient precision so that no improperly inserted parts, sometimes called "remaining ears," are left when assembling the outer ring of the annular seal into the seal groove.

[0013] In particular, when the elastic force of the rubber-like elastic material of the annular seal is low, there is a problem in that the work efficiency required to perform the assembly work on the outer ring with precision tends to decrease.

[0014] Therefore, the object of this invention is to solve the above-mentioned problems and to provide a rolling bearing equipped with an annular seal that enables stable and efficient high-precision assembly work so as not to cause partial insertion failure of the outer edge of the annular seal into the circumferential groove on the inner surface of the outer ring during the assembly work of the annular seal of the sealed rolling bearing to the outer ring, and moreover, to provide a sealed rolling bearing in which the assembly work of the annular seal can be performed without causing partial insertion failure, such as "ear retention," even if the rubber-like elastic material has low elasticity. [Means for solving the problem]

[0015] To solve the above problems, this invention provides a sealed rolling bearing comprising an inner ring, an outer ring having a circumferential groove on its inner surface, rolling elements incorporated between the inner and outer rings, and an annular seal that seals one axial end of the bearing space formed between the opposing inner and outer rings via the rolling elements, wherein the annular seal is reinforced with an annular core and has a thick-walled portion fitted into the circumferential groove on its outer peripheral edge made of an elastic material, the outer diameter φDs of the annular core and the inner diameter φDe of the outer ring end of the shoulder portion on the outer ring end face side of the side walls of the circumferential groove satisfy the relationship shown by the formula (φDe-φDs) / 2≦0.3Bs.

[0016] As described above, the sealed rolling bearing of this invention satisfies the above formula by ensuring that the difference in radius between the inner diameter φDe of the outer ring end and the outer diameter φDs of the mandrel is less than or equal to 0.3 times the wall thickness Bs of the thickened portion of the annular seal (less than or equal to 30%), thereby allowing the entire thickened portion of the annular seal to fully benefit from the reinforcing effect of the mandrel.

[0017] Therefore, the rigidity provided by the metal core is added to the thicker portion of the annular seal, and the elastic deformation of the rubber-like elastic material at the outer edge of the annular seal, which has increased rigidity, is suppressed to the minimum necessary extent, making it easier to push into the circumferential groove with a jig or by hand.

[0018] Therefore, when assembling the outer edge of the annular seal of a sealed rolling bearing into the circumferential groove on the inner surface of the outer ring, partial insertion failures on the outer edge are prevented, allowing for efficient assembly.

[0019] This excellent workability can be further enhanced by ensuring that the outer diameter φDs of the annular core and the outer diameter φD of the annular seal satisfy the relationship expressed by the formula φDs≧0.97φD.

[0020] In other words, because the outer diameter φDs of the core metal is 97% or more of the outer diameter φD of the annular seal, the rigidity of the core metal affects the outermost part of the annular seal, which is made of a rubber-like elastic material.

[0021] Therefore, even if the rubber-like elastic material has low elasticity, the rigidity can be increased while maintaining the required elasticity of the outermost diameter portion of the outer edge of the annular seal, suppressing greater deformation. This makes it less likely for partial insertion failures to occur in the circumferential groove of the outer edge, allowing for more efficient assembly of the annular seal.

[0022] In order to further prevent such partial insertion failure of the outer peripheral edge of the annular seal into the circumferential groove, it is preferable that the extended portion of the outer peripheral edge of the annular core bar is provided inclined at less than 90° with respect to the radial direction. With this configuration, the extended portion of the outer peripheral edge of the inclined core bar is sufficiently extended to approach the central portion inside the thick portion of the annular seal, so that the rigidity of the thick portion can be more sufficiently enhanced.

[0023] Further, for the same reason as described above, it is preferable that the extended portion is formed into a shape having one or more cranks so as to extend and spread inside the thick portion of the annular seal.

[0024] A sealed rolling bearing with the annular seal assembled in this manner has increased rigidity at key portions of the thick portion even when the local elastic force of the rubber-like elastic material is low, resulting in a sealed rolling bearing in which insertion failure during assembly work is less likely to occur.

Effects of the Invention

[0025] According to the present invention, the outer diameter φDs of the annular core bar of the sealed rolling bearing, the inner diameter φDe of the outer ring end opening at the outer ring end, and the axial thickness Bs of the thick portion of the annular seal are configured to satisfy the predetermined relationship described above. Therefore, partial insertion failure is extremely unlikely to occur during the work of fitting the outer peripheral edge of the annular seal of the sealed rolling bearing into the circumferential groove on the inner peripheral surface of the outer ring. Furthermore, even if the elastic material is a material with low elastic force, there is an advantage that the rolling bearing with an annular seal can be obtained which allows efficient assembly work with sufficiently high accuracy.

Brief Description of the Drawings

[0026] [Figure 1] Cross-sectional view of essential parts of the sealed rolling bearing according to the first embodiment [Figure 2] Enlarged cross-sectional view showing essential parts of Fig. 1 [Figure 3] Enlarged cross-sectional view showing essential parts of the second embodiment [Figure 4] Enlarged cross-sectional view showing essential parts of the third embodiment [Figure 5]A cross-sectional view showing a magnified view of the key parts of a conventional sealed rolling bearing. [Modes for carrying out the invention]

[0027] Embodiments of this invention will be described below with reference to the attached drawings. As shown in Figures 1 and 2, the sealed rolling bearing 1 of the first embodiment comprises an inner ring 2, an outer ring 3 having a circumferential groove 3b in the counterbore portion 3A of the inner circumferential surface 3a, rolling elements 4 incorporated between the inner ring 2 and the outer ring 3, and an annular seal 5 that seals one axial end of the bearing space formed between the opposing inner ring 2 and outer ring 3 via the rolling elements 4. The annular seal 5 is reinforced with an annular core metal 5a and has a thickened portion 5b on its outer peripheral edge, which is made of an elastic material and can be fitted into and held in the circumferential groove 3b. The axial direction is the direction parallel to the central axis of the outer ring 3 (the central axis of the bearing 1), and the radial direction is the direction perpendicular to the central axis of the outer ring 3.

[0028] In this type of sealed rolling bearing 1, the outer diameter φDs of the annular core metal 5a and the inner diameter φDe of the outer ring end of the shoulder top surface 3c on the outer ring end face side of the side walls of the circumferential groove 3b satisfy the relationship shown by the formula (φDe-φDs) / 2≦0.3Bs.

[0029] Furthermore, the annular seal 5 is reinforced by integrating it with a ring-shaped core metal 5a, which is slightly narrower than the ring, by means of composite molding, such as embedding at least the inner and outer edges of the core metal 5a along one side of the ring-shaped elastic material made of rubber.

[0030] Typically, rubber-like elastic materials use elastomers such as well-known elastic rubbers, and materials with various properties such as oil resistance, heat resistance, and cold resistance can be adopted depending on the purpose. For example, acrylonitrile butadiene rubber (NBR), acrylic acid ester / chloroethyl vinyl ether copolymer (ACM), vinylidene fluoride rubber (FKM), high-wear acrylic rubber (high-wear ACM), etc. can be used.

[0031] For the rubber-like elastic material exemplified above, it is preferable to use one with a Type A durometer hardness of 55 to 75 as specified in JIS K6253-3. Incidentally, the material constants (parameters C10, C01, C11, C20, C30) of the strain energy density function of the Mooney-Rivlin model are used as material properties corresponding to the shear modulus used in the analysis of the hardness.

[0032] Furthermore, the core metal 5a is formed by punching a ring shape out of a highly rigid metal sheet such as steel plate, and then processing it so that the inner and outer edges are bent to one side by bending or drawing, thereby obtaining the required reinforcing effect.

[0033] In the first embodiment, the core metal 5a is provided integrally with the annular seal 5, and is bent at a 90° angle to the radial direction of the annular seal 5 so that its outer diameter preferably reaches the central part of the thickened portion 5b, which is formed of a rubber-like elastic material at its outer peripheral edge. This bending direction is toward the inside of the rolling bearing 1, where the annular seal 5 seals the bearing space of the rolling bearing.

[0034] The annular seal 5, reinforced with such a core metal 5a, has at least its outer and inner edges covered with the rubber-like elastic material. The outer edge has a thickened portion 5b that can be fitted into and held in the circumferential groove 3b, and a seal lip 5c (Figure 1) is formed on the inner edge.

[0035] A bifurcated seal lip 5c is formed on the inner periphery of the annular seal 5 shown in the illustration, and a seal groove 2a is formed on the outer circumferential surface of the inner ring 2 that contacts this seal lip 5c, so as to effectively provide a double sealing action.

[0036] Although not shown in the diagram, instead of the seal lip 5c, a labyrinth-shaped gap can be used to provide a sealing function that does not come into contact with the rotating inner ring.

[0037] To assemble such an annular seal 5 to seal one axial end in the bearing space between the inner ring 2 and the outer ring 3, the annular seal 5 is inserted into the inner circumferential surface of the outer ring 3 such that its outer peripheral edge exceeds the top surface 3c of the shoulder portion on the outer ring end face side of the circumferential groove 3b of the counterbore portion 3A that opens to the end face of the outer ring 3 of the rolling bearing 1. It is then positioned by pressing it against the groove wall on the far side in the insertion direction, and the outer peripheral edge of the annular seal 5 is compressed against elasticity to fit it into the circumferential groove 3b. The axial end mentioned above refers to one of the two axial ends of the bearing, and the end opposite to the axial end is defined as the other axial end.

[0038] As shown in Figures 1 and 2, in this state, the annular seal 5 is provided such that the outer diameter φDs of the core metal, the inner diameter φDe of the outer ring end, and the axial thickness Bs of the thickened portion of the annular seal satisfy the relationship shown by the formula (φDe-φDs) / 2≦0.3Bs.

[0039] In other words, the outer diameter of the annular seal 5, the thickness of the outer peripheral edge, the outer diameter of the core metal 5a, and the opening diameter on the end face side of the outer ring 3 at the shoulder top surface 3c on the end face side of the outer ring 3 are set to dimensions that satisfy the above formula.

[0040] If the above formula is satisfied, the difference in radius between the inner diameter φDe of the outer ring end and the outer diameter φDs of the core metal will be less than or equal to 0.3 times the wall thickness Bs of the thick-walled portion of the annular seal (less than 30%), and the entire thick-walled portion 5b of the annular seal will be able to fully benefit from the reinforcing effect of the core metal.

[0041] In the first embodiment, the outer diameter φDs of the annular core and the outer diameter φD of the annular seal satisfy the relationship shown by the formula φDs≧0.97φD.

[0042] In this way, the entire thick-walled portion 5b of the annular seal 5 can fully benefit from the reinforcing effect of the core metal. As a result, the rigidity of the core metal 5a affects even the outermost diameter portion of the outer edge of the annular seal 5, which is made of a rubber-like elastic material. This makes it less likely for partial insertion failures into the circumferential groove 3b of the outer edge to occur, even if the rubber-like elastic material has low elasticity, and allows for more efficient assembly of the annular seal.

[0043] The second embodiment shown in Figure 3 is an annular seal 6 with the same external shape as the annular seal 5 of the first embodiment (Figure 2), but the outer edge of the core metal 6a is inclined at less than 90° (approximately 45°) with respect to the radial direction of the annular shape so that it extends into the interior of the thick-walled portion 6b of the annular seal 6, especially to the central part of the interior, and the other configurations are the same as the first embodiment.

[0044] By embedding such a core metal 6a inside the annular seal 6, the radially extended portion of the outer peripheral edge of the core metal 6a, which is inclined at a predetermined angle, extends sufficiently into the interior of the thickened portion 6b of the annular seal 6, and preferably to the central portion, thereby further increasing the rigidity of the thickened portion 6b.

[0045] The third embodiment shown in Figure 4 is an annular seal 7 with the same external shape as the annular seal 5 of the first embodiment (Figure 2), but the outer edge of the core metal 7a is bent at 90° in two places to form a crank, and the other components are the same as in the first embodiment.

[0046] By forming the outer edge of the core metal 7a in this manner, even when using a rubber-like elastic material with relatively low hardness, the radial rigidity of the thick-walled portion 7b is increased to compensate for the low elastic force of the thick-walled portion 7b, resulting in a sealed rolling bearing that is less prone to insertion problems during assembly.

[0047] [Examples 1-3] A sealed rolling bearing was fabricated by removing the annular seal from a deep groove ball bearing (standard product: shape described in JIS B 1521:2012) and incorporating the annular seals 5, 6, and 7 used in the first to third embodiments. These were then evaluated as Example 1, Example 2, and Example 3, respectively, as follows. In addition, conventional deep groove ball bearings (standard products) using annular seals were evaluated in the same manner as they were.

[0048] The evaluation tests assessed the assembly ease of the annular seals 5, 6, and 7 of Examples 1-3 and the same parts in the conventional example. The test results, which were evaluated based on ease of assembly (efficiency) and assembly accuracy, were rated on a three-point scale: excellent (◎), good (〇), and poor (×). The results are shown in Table 1, and the ratio of the (φDe-φDs) / 2 value to Bs and the ratio of φDs to φD for each example are also shown in Table 1.

[0049] Furthermore, the evaluation of assembly accuracy in the evaluation test was based on whether or not partial insertion failures were likely to occur when assembling the outer edge of the annular seal into the circumferential groove on the inner surface of the outer ring.

[0050] [Table 1]

[0051] As is clear from the results shown in Table 1, the value expressed by the formula (φDe-φDs) / 2 is Conventional examples with a ratio exceeding 0.30Bs and a ratio of φDs to φD of less than 0.97φD had poor assembly performance. However, sealed rolling bearings of Examples 1 to 3, where the above values ​​were all 0.30Bs or less and the above ratio was 0.97φD or greater, all received an evaluation of excellent (◎) or good (〇) assembly performance of the annular seal. Although deep groove ball bearings were exemplified in the above embodiment, the rolling bearings to which this invention can be applied are not limited to deep groove ball bearings, but can also be applied to other types of bearings such as angular contact bearings and self-aligning bearings. [Explanation of Symbols]

[0052] 1.10 Rolling bearings 2 Inner Ring 2a Seal groove 3 Outer ring 3A Counterbore section 3a Inner surface 3b Circumferential groove 3c Shoulder top surface 4 Rolling elements 5, 6, 7, 11 Ring seal 5a, 6a, 7a, 11a Core metal 5b, 6b, 7b, 11b Thick wall part 5c Seal Lip

Claims

1. An inner ring and an outer ring having a circumferential groove on its inner surface, A rolling element incorporated between the inner ring and the outer ring, The bearing comprises an annular seal that seals one axial end of the bearing space formed between the opposing inner and outer rings via the rolling elements, The annular seal is reinforced with an annular core and has a thickened portion fitted into the circumferential groove on its outer edge, which is made of an elastic material. The outer diameter φDs of the annular core metal and the inner diameter φDe of the outer ring end, where the top surface of the shoulder on the outer ring end face side of the side walls of the circumferential groove is defined by the formula: A sealed rolling bearing that satisfies the relationship (φDe - φDs) / 2 ≤ 0.3Bs.

2. The outer diameter φDs of the annular core and the outer diameter φD of the annular seal are given by the formula A sealed rolling bearing according to claim 1 that satisfies the relationship shown by φDs ≥ 0.97φD.

3. A sealed rolling bearing according to claim 1 or 2, wherein the outer edge of the annular core is inclined at less than 90° with respect to the radial direction of the annular, so that the extension extends into the interior of the thickened portion of the annular seal.

4. A sealed rolling bearing according to claim 1 or 2, wherein the outer edge of the annular core is bent to form one or more cranks so as to extend into the thickened portion of the annular seal.

5. The sealed rolling bearing according to claim 1 or 2, wherein the rolling bearing is a deep groove ball bearing.

Images