Resin holder

Abstract

The present application provides a resin holder which does not protrude from the axial side of a deep groove ball bearing and has a strength of the fatigue limit (U) or more in the range of the maximum load applied to the resin holder. The thickness (t) in the axial direction of the portion of the crown-shaped resin holder (5) having the smallest axial direction cross-sectional area of the pocket (5a) for holding the rolling ball (4) is set so that the stress generated at the portion having the smallest axial direction cross-sectional area when a prescribed maximum load (F) is applied to the crown-shaped resin holder (5) is lower than the fatigue limit (U) of the crown-shaped resin holder (5) and so that the crown-shaped resin holder (5) is located within the width (B) in the axial direction of the deep groove ball bearing (1).

Description

Technical Field

[0001] This invention relates to resin retainers. Background Technology

[0002] Resin retainers for deep groove ball bearings, manufactured by injection molding, have long been known. These resin retainers are formed, for example, by injection molding using a mold with corresponding annular cavities. The molten resin injected into the cavities separates and merges due to its movement within the cavities. The molten resin within the cavities, in a merged state, bonds together and solidifies, thereby forming a weld joint.

[0003] On the other hand, deep groove ball bearings that use resin retainers to hold rolling elements experience relative motion (rolling element advance / lag) relative to the retainer due to the difference between the revolution speed of the rolling elements and the revolution speed of the resin retainer. Because of this relative motion, the pocket-shaped portion of the resin retainer repeatedly collides with the rolling elements during the rotation of the deep groove ball bearing. The resin retainer undergoes repeated elastic deformation due to these collisions with the rolling elements. That is, repetitive stress is generated in the resin retainer due to the collisions with the rolling elements. This repetitive stress concentrates at the weld joint in the resin retainer, which is detrimental to fatigue life. Therefore, resin retainers that increase the joint strength to suppress the impact on the fatigue life of the resin retainer are known. For example, as described in Patent Document 1.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-026856 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] The mold used to form the resin holder described in Patent Document 1 is configured such that the opening area of ​​the resin storage section connected to the cavity is larger than the opening area of ​​the resin injection port connected to the cavity. As a result, the molten resin filling the cavity flows smoothly without stagnating in the resin storage section. Consequently, after the weld joint is formed, convection of the molten resin occurs within the cavity, and the contact area between the molten resins increases due to the deformation of the weld joint. Therefore, even when using a resin material with a relatively high melt viscosity, the strength of the weld joint of the resin holder can be improved. However, in the technology described in Patent Document 1, the deformation state of the weld joint within the cavity cannot be controlled. That is, it is unclear whether the strength of the weld joint in the resin holder exceeds the fatigue limit. Therefore, the resin holder needs to be designed with an excessively high safety margin to achieve a strength exceeding the fatigue limit within the range of the maximum load applied to the resin holder, which is disadvantageous in this respect.

[0009] The present invention was made in view of the above circumstances, and its object is to provide a resin retainer that does not protrude from the axial side of a deep groove ball bearing and has a strength exceeding the fatigue limit within the range of the maximum load applied to the resin retainer.

[0010] Technical solutions for solving the problem

[0011] That is, the first invention is a resin retainer that holds a plurality of rolling elements of a deep groove ball bearing at equal intervals. In the resin retainer, the width of the portion with the smallest axial cross-sectional area of ​​the pocket-shaped portion holding the rolling elements is within the range calculated by equation (1), such that when a specified maximum load is applied to the resin retainer, the stress generated in the portion with the smallest axial cross-sectional area is lower than the fatigue limit of the resin retainer, and such that the resin retainer is located within the range of the axial width of the deep groove ball bearing.

[0012] [Formula 1]

[0013]

[0014] F: Maximum load applied to the resin retainer; U: Fatigue limit of the resin constituting the resin retainer; α: Rate of reduction of fatigue limit caused by the welded portion of the resin retainer; Da: Diameter of the rolling element; t: Axial thickness of the minimum cross-sectional area; B: Axial width of the deep groove ball bearing.

[0015] The second invention is that the resin forming the resin retainer is a polyamide synthetic resin.

[0016] The third invention is that the resin forming the resin retainer comprises a fiber-reinforced resin.

[0017] The fourth invention is that the reduction rate of the proportion of the fatigue limit of the resin constituting the resin retainer that is reduced due to the welded portion is 0.6 or more and 0.8 or less.

[0018] Invention Effects

[0019] As a result of the present invention, the following effects can be achieved.

[0020] That is, the first invention is designed such that the shape of the portion with the smallest axial cross-sectional area in the pocket-shaped part, which is considered to generate the maximum stress in the resin retainer, satisfies Equation (1). The resin retainer assembled into the deep groove ball bearing has a radial width that does not contact the inner and outer rings of the deep groove ball bearing, and has an axial thickness such that the stress generated in the portion with the smallest axial cross-sectional area when the maximum load of the resin retainer is applied to the resin retainer is lower than the fatigue limit of the resin constituting the resin retainer. Furthermore, Equation (1) includes the rate of reduction of the fatigue limit due to the welded portion. Thus, the stress generated in the portion with the smallest axial cross-sectional area of ​​the resin retainer is lower than the fatigue limit of the resin constituting the resin retainer, even when there is a welded portion in the portion with the smallest axial cross-sectional area. Furthermore, the resin retainer assembled into the deep groove ball bearing has a thickness that does not protrude from the axial sides of the inner and outer rings. Thus, it is possible to not protrude from the axial sides of the deep groove ball bearing and to have a strength above the fatigue limit within the range of the maximum load applied to the resin retainer.

[0021] The second and third inventions improve the fatigue limit of the crown resin retainer by using a polyamide synthetic resin with excellent toughness, impact resistance, and flexibility, or by employing a fiber-reinforced resin containing glass fiber (GF), carbon fiber (CF), etc. As a result, the crown resin retainer does not protrude from the axial side of the deep groove ball bearing, and the range of axial thickness required to achieve strength exceeding the fatigue limit within the maximum load applied to the resin retainer is expanded.

[0022] The fourth invention, by taking into account the rate of reduction in fatigue limit caused by the welded portion of the resin retainer, ensures that even if the portion with the smallest cross-sectional area in the axial direction has a welded portion, the stress generated at the welded portion when the maximum load of the resin retainer is applied to the resin retainer is lower than the fatigue limit of the resin forming the resin retainer. Therefore, the crown-shaped resin retainer can avoid protruding from the axial side of the deep groove ball bearing and possess strength exceeding the fatigue limit within the range of the maximum load applied to the resin retainer. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of a deep groove ball bearing.

[0024] Figure 2 This is a side view of the crown-shaped resin retainer according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the load state caused by the advance and lag of the rolling element relative to the crown resin retainer in an embodiment of the present invention.

[0026] Figure 4 This is a graph showing the relationship between the load and the diameter of the rolling element under specified conditions in the crown-shaped resin retainer according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the fatigue test of the crown-shaped resin retainer according to an embodiment of the present invention.

[0028] Figure 6 This is a graph showing the relationship between the radial thickness of the crown-shaped resin retainer and the diameter of the rolling element according to an embodiment of the present invention. Detailed Implementation

[0029] use Figure 1 and Figure 2 This describes a deep groove ball bearing 1 as one embodiment of the deep groove ball bearing of the present invention. Figure 1 This is a cross-sectional view of a deep groove ball bearing. Figure 2 This is a side view of the crown-shaped resin retainer according to an embodiment of the present invention.

[0030] like Figure 1 and Figure 2 As shown, the deep groove ball bearing 1 includes an inner ring 2, an outer ring 3, a plurality of balls 4 rotatably positioned between the inner ring 2 and the outer ring 3, and a crown-shaped resin retainer 5 for housing the balls 4. Furthermore, in the following description, the axial direction refers to the direction along the axis P of the deep groove ball bearing 1. Additionally, radial direction refers to the direction perpendicular to the axis P of the deep groove ball bearing 1.

[0031] The inner ring 2 is a radially inner guide ring that guides the ball 4. The inner ring 2 has an annular inner guide surface 2a on its outer circumferential surface for the rotation of the ball 4. The inner guide surface 2a is a groove with an arc-shaped cross-section when viewed from the axial direction.

[0032] The outer ring 3 is a radially outer guide ring for guiding the ball 4. The outer ring 3 has an inner diameter larger than the outer diameter of the inner ring 2. The outer ring 3 has an annular outer ring guide surface 3a on its inner circumferential surface for the rotation of the ball 4. The outer ring guide surface 3a is a groove with an arc-shaped cross-section when viewed in the axial direction. The outer ring 3 is located on the same axis P as the inner ring 2. Furthermore, the outer ring 3 is positioned where the outer ring guide surface 3a overlaps with the inner ring guide surface 2a when viewed radially.

[0033] The multiple balls 4, which are rolling elements, are spherical. The curvature of the surfaces of the multiple balls 4 is approximately the same as the curvature of the inner ring track surface 2a and the outer ring track surface 3a. The balls 4 are located between the inner ring 2 and the outer ring 3 and are arranged circumferentially on both the inner ring 2 and the outer ring 3. The multiple balls 4 are in contact with the inner ring track surface 2a. In addition, the multiple balls 4 are in contact with the outer ring track surface 3a. That is, the multiple balls 4 are sandwiched between the inner ring track surface 2a and the outer ring track surface 3a. The multiple balls 4 rotate on the inner ring track surface 2a and the outer ring track surface 3a. Thus, the multiple balls 4 are supported in a manner that allows the outer ring 3 to rotate relative to the inner ring 2.

[0034] The crown-shaped resin retainer 5, serving as a resin retainer, is a component that holds multiple balls 4. The crown-shaped resin retainer 5 is constructed from polyamide synthetic resins such as polyamide 46 (PA46), polyamide 66 (PA66), and polyamide 9T (PA9T). Additionally, glass fiber (GF) and carbon fiber (CF) may be included in the synthetic resin as reinforcing materials. The crown-shaped resin retainer 5 is formed in a cylindrical shape. The crown-shaped resin retainer 5 has multiple pocket-shaped portions 5a that independently hold the balls 4. The multiple pocket-shaped portions 5a are arranged at equal intervals in the circumferential direction of the crown-shaped resin retainer 5. Each pocket-shaped portion 5a is a spherical recess that is concave from one end to the other in the axial direction. The curvature of the pocket-shaped portion 5a is less than the curvature of the balls 4. That is, the pocket-shaped portion 5a is constructed from a spherical surface with a radius larger than that of the balls 4. Therefore, when the balls 4 are located within the pocket-shaped portion 5a, a gap is created between the surface of the balls 4 and the surface of the pocket-shaped portion 5a in the crown-shaped resin retainer 5.

[0035] like Figure 2 As shown, the crown-shaped resin retainer 5 has a pair of claw portions 5b extending to one side in the axial direction in each of the plurality of pocket-shaped portions 5a. The side of the claw portion 5b on the pocket-shaped portion 5a side has a spherical surface that is continuous with the spherical surface of the pocket-shaped portion 5a. Furthermore, the spherical portion of the pocket-shaped portion 5a and the spherical portion of the claw portion 5b have the same curvature. Thus, the claw portion 5b constitutes part of the spherical portion of the pocket-shaped portion 5a. The minimum distance between the front ends of the pair of claw portions 5b is less than the maximum circumferential width of the crown-shaped resin retainer 5 of the pocket-shaped portion 5a. That is, the pair of claw portions 5b restricts the amount of movement of the ball 4 located in the pocket-shaped portion 5a in the axial direction. Thus, the crown-shaped resin retainer 5 can retain the ball 4 in the pocket-shaped portion 5a by means of the pair of claw portions 5b and allow the ball 4 to rotate in the pocket-shaped portion 5a. Furthermore, the crown-shaped resin retainer 5 retains the ball 4 in such a way that the ball 4 can move in the pocket-shaped portion 5a within the range of the gap between the ball 4 and the pocket-shaped portion 5a.

[0036] like Figure 1 and Figure 2As shown, the deep groove ball bearing 1 configured in this way allows the outer ring 3 and inner ring 2 to rotate relative to each other by means of a plurality of balls 4. The plurality of balls 4 are held at certain intervals between the inner ring 2 and the outer ring 3 by a crown-shaped resin retainer 5. When the outer ring 3 and inner ring 2 rotate relative to each other, the deep groove ball bearing 1 rotates on the inner ring raceway 2a and the outer ring raceway 3a with the plurality of balls 4 held by the pocket-shaped portion 5a of the crown-shaped resin retainer 5. The plurality of balls 4 rotate within the pocket-shaped portion 5a and revolve together with the crown-shaped resin retainer 5 in the circumferential direction of the deep groove ball bearing 1. The crown-shaped resin retainer 5 moves radially by an amount corresponding to the gap between the balls 4 and the pocket-shaped portion 5a and revolves together with the plurality of balls 4.

[0037] Next, use Figure 3 and Figure 4 This indicates that the ball 4 is advanced and delayed relative to the pocket-shaped portion 5a of the crown-shaped resin retainer 5. Figure 3 This is a schematic diagram of the load state caused by the advance and lag of the rolling element relative to the crown resin retainer in an embodiment of the present invention. Figure 4 This is a graph showing the relationship between the load and the diameter of the rolling element under specified conditions in the crown-shaped resin retainer according to an embodiment of the present invention.

[0038] like Figure 3 As shown, when radial and axial loads are applied to the deep groove ball bearing 1, the rotational speed of the balls 4 varies depending on the contact angle between the load direction applied to the inner ring raceway 2a or outer ring raceway 3a and the direction perpendicular to the axis P of the deep groove ball bearing 1. On the other hand, the rotational speed of the crown resin retainer 5 is constant. Therefore, the deep groove ball bearing 1 exhibits two states: one where the balls 4 move faster than the crown resin retainer 5 in the rotational direction (advanced), and the other where the balls 4 move slower than the crown resin retainer 5 in the rotational direction (lagging). When the rotational speed of the balls 4 is slower than that of the crown resin retainer 5, the crown resin retainer 5 pushes the balls 4 in the rotational direction. When the rotational speed of the balls 4 is faster than that of the crown resin retainer 5, the balls 4 push the crown resin retainer 5 in the rotational direction. As a result, compressive and tensile loads are generated variably in the crown-shaped resin retainer 5 during its revolution (see the blackened arrows). Furthermore, the crown-shaped resin retainer 5 generates the maximum compressive and tensile stresses at the bottom portion of the pocket-shaped part 5a, which has the smallest cross-sectional area in the axial direction.

[0039] like Figure 4As shown, when the deep groove ball bearing 1 is used in a transmission device under the following operating conditions, the load applied to the crown resin retainer 5 can be calculated based on the measurement results and according to equation (2). As shown in equation (2), the maximum load F applied to the crown resin retainer 5 can be approximated by a linear function with the diameter Da of the ball 4 as the variable. As shown in equation (2), the specified maximum load F applied to the crown resin retainer 5 can be calculated based on the diameter Da of the ball under the application and operating conditions of the deep groove ball bearing 1.

[0040] [Equation 2]

[0041] F = 23.7Da - 78.4…(2)

[0042] F: Maximum load applied to crown-shaped resin retainer 5; Da: Diameter of ball 4.

[0043] Misalignment: 2 / 1000mm / mm, Radial load: 0.165Cr, Axial load: 0.07Ca, Rotational speed: Maximum permissible rotational speed under oil lubrication, Lubricating oil: Transmission fluid.

[0044] Next, use Figure 5 The reduction rate α of the fatigue limit U caused by the welded portion W of the crown resin retainer 5 will be explained. Figure 5 This is a schematic diagram of fatigue testing of the crown-shaped resin retainer according to an embodiment of the present invention. The welded portion W refers to the strip-shaped joint formed by the merging of molten resin that has increased in viscosity due to cooling at the front end within the mold.

[0045] like Figure 5 As shown, the fatigue test of the crown-shaped resin retainer 5 utilizes a pair of semi-circular clamps J to apply a predetermined force (refer to the blackened arrows) to the inner circumferential surface of the crown-shaped resin retainer 5 in a radially outward direction at predetermined cycles. A tensile load in the radially outward direction is repeatedly applied to the crown-shaped resin retainer 5. During this process, the crown-shaped resin retainer 5 is tested with the welded portion W located in the gap between one clamp J and the other clamp J. Thus, the maximum tensile load is applied to the welded portion W in the crown-shaped resin retainer 5. Therefore, the fatigue limit Uw of the welded portion W is estimated through the fatigue test of the crown-shaped resin retainer 5. Furthermore, the fatigue limit U of the resin material of the crown-shaped resin retainer 5 is estimated using a non-reinforced dumbbell-shaped test piece without the welded portion W.

[0046] The reduction rate α of the fatigue limit U caused by the welded portion W in the crown resin retainer 5 is calculated based on the ratio of the fatigue limit U of the unreinforced dumbbell-shaped test piece to the fatigue limit Uw of the welded portion W of the crown resin retainer 5. The reduction rate α of the fatigue limit U caused by the welded portion W can be expressed as Uw / U, for example, when using the fatigue limit U of the unreinforced dumbbell-shaped test piece and the fatigue limit Uw of the welded portion W of the crown resin retainer 5. For example, when the reduction rate α of the fatigue limit U caused by the welded portion W is 0.63, the fatigue limit Uw of the welded portion W of the crown resin retainer 5 is reduced to 63% of the fatigue limit U of the resin material of the crown resin retainer 5 due to the welded portion W. The reduction rate α of the fatigue limit U caused by the welded portion W varies depending on the material used in the crown resin retainer 5, and as an example, it varies between 0.6 and 0.8.

[0047] Next, use Figure 6 The relationship between the fatigue limit U of the resin material of the crown-shaped resin retainer 5 and its shape is explained. Figure 6 This is a graph showing the relationship between the radial thickness of the crown-shaped resin retainer and the diameter of the rolling element according to an embodiment of the present invention.

[0048] like Figure 6 As shown, the crown-shaped resin retainer 5 will not experience fatigue failure even if it has a welded portion W, as long as the maximum stress generated by the crown-shaped resin retainer 5 is 60% to less than 80% of the fatigue limit U of the resin material of the crown-shaped resin retainer 5. Therefore, in the crown-shaped resin retainer 5, by making the bottom portion of the pocket-shaped portion 5a, which has the welded portion W and the smallest cross-sectional area in the axial direction, satisfy equation (3), fatigue failure will not occur even if a specified maximum load F is applied.

[0049] [Formula 3]

[0050]

[0051]

[0052] F: Maximum load applied to crown resin retainer 5; U: Fatigue limit of the resin forming crown resin retainer 5; α: Rate of reduction of fatigue limit U caused by welded portion W of crown resin retainer 5; S: Cross-sectional area of ​​the portion with the smallest axial cross-sectional area of ​​crown resin retainer 5.

[0053] Furthermore, the cross-sectional area S (hereinafter referred to as "bottom cross-sectional area S") of the bottom part of the pocket-shaped portion 5a with the smallest cross-sectional area in the axial direction of the crown-shaped resin retainer 5 can be calculated according to equation (4).

[0054] [Formula 4]

[0055] S=h·t…(4)

[0056] S: The cross-sectional area of ​​the smallest portion of the crown-shaped resin retainer 5 in the axial direction; h: The radial thickness of the crown-shaped resin retainer 5; t: The axial thickness of the bottom portion of the pocket-shaped part 5a.

[0057] The crown-shaped resin retainer 5 is located between the inner ring 2 and the outer ring 3 such that the axis P of the inner ring 2 and the outer ring 3 is aligned with the axis P of the crown-shaped resin retainer 5. Furthermore, the crown-shaped resin retainer 5 holds a plurality of balls 4 in a state where they can rotate relative to the inner ring 2 and the outer ring 3. That is, in the deep groove ball bearing 1, the inner ring 2 and the outer ring 3 are always spaced apart from the crown-shaped resin retainer 5 (see reference). Figure 1 Therefore, the radial thickness h of the crown-shaped resin retainer 5 is included in the range that will not contact the inner ring 2 and the outer ring 3 even if the gap between the ball 4 and the pocket-shaped portion 5a is moved radially.

[0058] Furthermore, the radial spacing between the inner ring 2 and the outer ring 3 of the deep groove ball bearing 1 is determined based on the diameter Da of the balls 4. Similarly, the radial thickness h of the crown-shaped resin retainer 5 is determined based on the diameter Da of the retained balls 4. The radial thickness h is proportional to the diameter Da of the balls 4. The radial thickness h is calculated according to equation (3).

[0059] [Formula 5]

[0060] h = 0.595Da - 0.4181…(5)

[0061] h: radial thickness of crown resin retainer 5; Da: diameter of ball 4.

[0062] The bottom cross-sectional area S of the crown-shaped resin retainer 5 is calculated using equation (6), which is based on equations (4) and (5), and expresses the thickness t in the axial direction of the bottom portion of the pocket-shaped part 5a and the diameter Da of the ball 4. Furthermore, the bottom of the pocket-shaped part 5a of the crown-shaped resin retainer 5 is spherical. Therefore, the thickness t in the axial direction of the bottom portion of the pocket-shaped part 5a is taken as the thinnest thickness t.

[0063] [Formula 6]

[0064] S=(0.595Da-0.4181)·…(6)

[0065] Based on the above explanation, the thickness t in the axial direction of the crown resin retainer 5 is expressed according to equations (3) and (6) by the maximum load F applied to the crown resin retainer 5, the diameter Da of the ball 4, and the fatigue limit U of the resin forming the crown resin retainer 5. The crown resin retainer 5, by ensuring that the thickness t in the axial direction satisfies equation (7), will not experience fatigue failure even if it has a welded portion W.

[0066] [Formula 7]

[0067]

[0068] On the other hand, in the deep groove ball bearing 1, the crown resin retainer 5 does not protrude from the axial sides of the inner ring 2 and the outer ring 3. That is, in the crown resin retainer 5, the thickness t in the axial direction of the bottom portion of the pocket-shaped part 5a, with the axial center of the deep groove ball bearing 1 as a reference, is less than the difference between the radius of the ball 4 and half of the axial width B of the inner ring 2 and the outer ring 3. Thus, the thickness t in the axial direction of the crown resin retainer 5 is located within the range of the axial width B of the inner ring 2 and the outer ring 3 by satisfying the relationship shown in equation (8).

[0069] [Formula 8]

[0070]

[0071] The crown-shaped resin retainer 5 has a thickness t in the axial direction set in a manner that satisfies Equation (1) derived from Equations (7) and (8), does not protrude from the axial sides of the inner ring 2 and the outer ring 3, and does not suffer fatigue failure when the maximum load F is applied.

[0072] [Formula 1]

[0073]

[0074] In the crown-shaped resin retainer 5 of this embodiment, the thickness t in the axial direction of the pocket cross-sectional area S, which is considered to generate the maximum stress, is set in a manner that satisfies equation (1). The crown-shaped resin retainer 5 assembled into the deep groove ball bearing 1 has a radial thickness h that does not contact the inner ring 2 and the outer ring 3, and has an axial thickness such that the stress generated in the pocket cross-sectional area S when the maximum load F of the crown-shaped resin retainer 5 is applied to the resin retainer is lower than the fatigue limit U of the resin constituting the crown-shaped resin retainer 5. Furthermore, the bottom portion of the pocket-shaped portion 5a of the crown-shaped resin retainer 5 assembled into the deep groove ball bearing 1 is located between the axial sides of the inner ring 2 and the outer ring 3 and the axial direction of the ball 4. That is, the crown-shaped resin retainer 5 is contained within the volume of the deep groove ball bearing 1 enclosed by the inner ring 2 and the outer ring 3. Thus, Equation (1) calculates the range of thickness t in the axial direction required for the crown resin retainer 5 to satisfy its function, based on the axial width B of the deep groove ball bearing 1, the diameter Da of the ball 4, and the allowable load (maximum load F) of the crown resin retainer 5. Consequently, the crown resin retainer 5 can avoid protruding from the axial sides of the inner ring 2 and the outer ring 3, and possesses a fatigue limit U or higher within the range of the maximum load F applied to the crown resin retainer 5.

[0075] Furthermore, by making the crown-shaped resin retainer 5 from a polyamide synthetic resin with excellent strength, toughness, impact resistance, and flexibility, or by containing glass fiber (GF), carbon fiber (CF), etc., the fatigue limit U of the crown-shaped resin retainer 5 can be improved. As a result, the range of the axial thickness t required for the crown-shaped resin retainer 5 to have strength exceeding the fatigue limit U within the range of the maximum load F applied to the crown-shaped resin retainer 5, without protruding from the axial sides of the inner ring 2 and outer ring 3, can be expanded.

[0076] Furthermore, by considering the reduction rate α of the fatigue limit U caused by the welded portion W of the crown resin retainer 5, even if the welded portion W exists at the bottom of the pocket-shaped portion 5a where the maximum stress is generated in the crown resin retainer 5, the stress generated when the crown resin retainer 5 is subjected to the envisioned maximum load F is lower than the fatigue limit U of the resin forming the crown resin retainer 5. Therefore, the crown resin retainer 5 can avoid protruding from the axial sides of the inner ring 2 and the outer ring 3, and has a strength exceeding the fatigue limit U within the range of the maximum load F applied to the crown resin retainer 5.

[0077] The embodiments of the present invention have been described above, but the present invention is not limited to such embodiments, which are merely examples. Of course, it can be implemented in various ways without departing from the spirit of the present invention. The scope of the present invention also includes all modifications in the same sense and scope as the claimed scope.

[0078] Furthermore, while the deep groove ball bearing 1 is described in this embodiment, it can be applied to all bearings having multiple rolling elements. Similarly, while the crown-shaped resin retainer 5 is described in this embodiment, it can be applied to any resin retainer used to retain rolling elements.

[0079] Furthermore, in this embodiment, the crown-shaped resin retainer 5 is made of polyamide synthetic resin, but it is not limited to this. The crown-shaped resin retainer can be made of any synthetic resin.

[0080] Explanation of reference numerals in the attached figures

[0081] 1. Deep groove ball bearing

[0082] 2 Inner ring

[0083] 2a Inner track surface

[0084] 3 Outer ring

[0085] 3a Outer track surface

[0086] 4 ball bearings

[0087] 5. Crown-shaped resin retainer

[0088] 5a Pocket-shaped part

[0089] F is the maximum load applied to the crown resin retainer.

[0090] U represents the fatigue limit of the resin constituting the crown-shaped resin retainer.

[0091] The rate of decrease in fatigue limit U caused by the welded portion W of the α-crown resin retainer

[0092] The diameter of the ball bearing.

[0093] t Thickness of the bottom portion of the pocket-shaped part in the axial direction

[0094] B. Axial width of deep groove ball bearing

[0095] The cross-sectional area of ​​the smallest part along the axial direction of the S-shaped resin retainer.

[0096] h is the radial thickness of the crown-shaped resin retainer.

Claims

1. A resin retainer that holds a plurality of rolling elements of a deep groove ball bearing at equal intervals, characterized in that: The thinnest thickness in the axial direction of the portion with the smallest cross-sectional area in the axial direction of the pocket-shaped portion of the rolling element is contained within the range calculated by equation (1). This ensures that when a specified maximum load is applied to the resin retainer, the stress generated in the portion with the smallest cross-sectional area in the axial direction is lower than the fatigue limit of the resin retainer, and that the resin retainer is located within the axial width of the deep groove ball bearing. [Formula 1] F: Maximum load applied to the resin retainer; U: Fatigue limit of the resin constituting the resin retainer; α: Reduction rate of the proportion by which the fatigue limit of the resin constituting the resin retainer is reduced due to the welded portion, which is the joint of the resin; Da: Diameter of the rolling element; t: Thinnest thickness in the axial direction of the portion with the smallest axial cross-sectional area of ​​the pocket-shaped part; B: Axial width of the deep groove ball bearing.

2. The resin retainer as described in claim 1, characterized in that: The resin forming the resin retainer is a polyamide synthetic resin.

3. The resin retainer as described in claim 1 or 2, characterized in that: The resin forming the resin retainer comprises a fiber-reinforced resin.

4. The resin retainer as described in claim 1, characterized in that: The rate of decrease in the fatigue limit of the resin constituting the resin retainer due to the welded portion is 0.6 or more and 0.8 or less.

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