BEARING AND BEARING MANUFACTURING PROCESS

Abstract

The invention relates to a bearing from which it is easy to confirm whether a first annular body and a second annular body, which together form a resin cage, are completely coupled together. The bearing is provided with crimped head portions 29 arranged at the distal ends of respective resin projections 26 of the resin cage 5 so as to prevent the resin projections 26 from protruding from the projection insertion holes 30. Figure to be published with the abbreviation: Fig. 1

Description

Title of the invention: BEARING AND BEARING MANUFACTURING METHOD Scope of the invention

[0001] The present invention relates to a bearing, and a method of manufacturing the bearing. Technological background

[0002] As a bearing supporting a rotating shaft, a bearing is widely used in electric motors, speed reducers, transmissions, etc. The bearing comprises an inner ring, an outer ring arranged radially outward from the inner ring, a plurality of rolling elements arranged between the inner and outer rings, and a cage retaining the rolling elements. A resin cage (made of a resin) is used in some cases due to certain advantages, such as its light weight and degree of freedom in molding. A crown-shaped cage, a combination cage, or a similar design is generally used for the resin cage.

[0003] The crown-shaped cage comprises a circular annular portion, and a plurality of pairs of claws extending axially from the circular annular portion, and retaining rolling elements.

[0004] In recent years, electric motors in electric vehicles and similar applications have tended to increase in speed, and consequently, bearings used for speed reducers, transmissions, and similar applications also tend to be used within a high-speed rotational range. If, when a bearing is used within a high-speed rotational range (in particular, a rotational range close to the bearing's speed limit), a ring-shaped cage is used as the bearing cage, the pairs of claws in the ring-shaped cage could deform radially outward under the effect of a centrifugal force, thus causing the claws to interfere with the rolling elements. As a method for reducing claw deformation due to centrifugal force, the use of a highly rigid resin material is considered, but such a resin material is generally expensive.

[0005] The crown-shaped cage has claws only on one axial side of the circular annular portion, and is therefore axially asymmetrical. For this reason, a bearing in which the crown-shaped cage is used may require management of the mounting direction.

[0006] In view of this, a combined cage is used in certain cases as a cage that exhibits high structural rigidity and does not require management of the direction of installation. The applicant of the present application has already proposed combined cages in patent documents 1 to 4 identified below.

[0007] The combined cages of patent documents 1 to 4 comprise a first annular body and a second annular body axially opposed to the first annular body, and the combined cages are formed by coupling the first annular body and the second annular body to each other. A method of coupling involves engaging engagement claws in respective engagement holes.

[0008] More specifically, the first annular body comprises a plurality of first pocket-forming parts circumferentially spaced from one another; and a plurality of first interpocket parts, each formed between a corresponding circumferentially adjacent pair of first pocket-forming parts. Similarly, the second annular body comprises a plurality of second pocket-forming parts circumferentially spaced from one another; and a plurality of second interpocket parts, each formed between a corresponding circumferentially adjacent pair of second pocket-forming parts.

[0009] First stop surfaces formed on the first inter-pocket sections are superimposed on respective second stop surfaces formed on the second inter-pocket sections. Pockets are defined between the respective first and second pocket-forming sections, and balls are received in the respective pockets. Axially extending engagement claws are formed on the respective first stop surfaces, and the engagement claws are inserted into respective engagement holes formed in the second stop surfaces so as to extend axially into the second inter-pocket sections. Hook portions formed on the engagement claws are engaged with stages formed on the inner surfaces of the engagement holes, thus preventing the engagement claws from exiting the engagement holes.As described above, the first annular body and the second annular body are coupled together by engaging the engagement claws in the engagement holes.

[0010] PRIOR ART DOCUMENTS: Patent document 1: Japanese publication of unexamined patent application no. 2004-076778; Patent document 2: Japanese publication of unexamined patent application no. 2010-112461; Patent document 3: Japanese publication of unexamined patent application no. 2013-245762; Patent document 4: Japanese publication of unexamined patent application no. 2020-133663.

[0011] With regard to the combined cages of patent documents 1 to 4, it is difficult to reliably couple the first and second ring bodies to each other. Furthermore, it is difficult to confirm whether the first and second ring bodies are completely coupled together.

[0012] That is to say, since the combined cages of patent documents 1 to 4 have engagement claws larger than the engagement holes, when the engagement claws are inserted into the engagement holes, they must be forced in while deformed. The size relationship between the engagement claws and the engagement holes is important. That is, if all the engagement claws are not engaged in all the engagement holes simultaneously, some of the engagement claws may not be fully inserted into some of the engagement holes, and partial separation could occur between the first and second ring bodies. Thus, it is difficult to reliably couple the first and second ring bodies to each other.

[0013] Furthermore, the hook portions of the engagement claws and the stages that engage with the hook portions are located inside the engagement holes, so the engagement state cannot be visually verified from the outside. Thus, it is difficult to confirm the engagement state between the hook portions and the stages, and therefore difficult to confirm whether the first annular body and the second annular body are fully coupled together.

[0014] Furthermore, if the bearing of patent document 1 is used in a high-speed rotation range, seizure could occur inside the bearing due to insufficient (depletion) lubricating oil.

[0015] That is to say, in the combined cage of patent document 1, the axially outer end surface of each of the first and second annular bodies is an irregular, corrugated surface having hemispherical portions along the circumferentially spaced ball shapes. Thus, when the bearing is used in a high-speed rotational range, the lubricating oil supplied from outside the bearing is dispersed by the axially irregular end surfaces of the cage and is therefore less likely to penetrate the bearing. Consequently, lubricating oil is lacking inside the bearing, and seizure can occur within the bearing. These latter In particular, over the years, the viscosity and quantity of lubricating oil tend to decrease, and seizing is likely to occur. Summary

[0016] The present invention aims to provide a bearing in which a first annular body and a second annular body constituting a resin cage can be reliably coupled together, and from which it is possible to easily confirm whether the first annular body and the second annular body are completely coupled together.

[0017] To achieve the above objective, the present invention proposes a bearing comprising: an inner ring; an outer ring arranged radially outwards from the inner ring; a plurality of rolling elements arranged between the inner ring and the outer ring; and a resin cage made of a thermoplastic resin, retaining the rolling elements, the resin cage comprising: a first annular body; and a second annular body axially opposed to the first annular body, the first annular body comprising: a plurality of first pocket-forming parts; and a plurality of first inter-pocket parts, each formed with a first thrust surface, and each formed between a corresponding circumferentially adjacent pair of first pocket-forming parts.the second annular body comprising: a plurality of second pocket-forming parts; and a plurality of second inter-pocket parts, each formed with a second abutment surface, and each formed between a corresponding circumferentially adjacent pair of second pocket-forming parts, the first abutment surfaces of the first inter-pocket parts being superimposed on the respective second abutment surfaces of the second inter-pocket parts, and pockets being defined between the first pocket-forming parts and the respective second pocket-forming parts, and the rolling elements being received in the respective pockets, characterized in that axially extending resin protrusions are formed on all or part of the first abutment surfaces, respectively, protrusion insertion holes being formed, respectively,in all or part of the second buttress surfaces so as to extend axially through all or part of the second inter-pocket parts, and the resin projections being inserted through the respective projection insertion holes, and the resin projections having, at their respective distal ends, crimped head parts to prevent the resin projections from exiting the projection insertion holes [arrangement 1]. ,

[0018] With this arrangement, after the first annular body and the second annular body are superimposed on one another so that the resin protrusions are inserted through the respective protrusion insertion holes, the distal ends of the Resin protrusions are melted to form the crimped head sections, preventing the resin protrusions from protruding from the protrusion insertion holes and coupling the first and second ring bodies together. This ensures that the first and second ring bodies are reliably coupled without spontaneous separation.

[0019] Furthermore, when the first and second annular bodies are coupled together, the crimped head portions are located in positions where they are visible. Therefore, it is easy to confirm whether the first and second annular bodies are completely coupled together by visually checking whether the crimped head portions have a shape that prevents them from protruding from the insertion holes.

[0020] Furthermore, since the crimped head portions are formed after the resin protrusions are inserted through the respective protrusion insertion holes, it is possible to form the crimped head portions so that each is sufficiently larger than the protrusion insertion hole, thus ensuring an overlap tolerance of the crimped head portions. Consequently, the first annular body and the second annular body can be reliably coupled together.

[0021] - Arrangement 2 - Bearing according to arrangement 1, in which the surfaces axially external end surfaces of the second pocket-forming parts and the axially external end surfaces of the second inter-pocket parts form a planar surface that is perpendicular to an axial direction, and that extends circumferentially continuously around a whole circumference of the second annular body, and in which the protruding insertion holes have counterbore parts in which the respective crimped head parts are received so that the crimped head parts do not protrude beyond the axially external end surfaces of all or part of the second inter-pocket parts.

[0022] With this arrangement, the axially outer end surface of the second annular body is a flat surface that is perpendicular to the axial direction and extends circumferentially and continuously around the entire circumference. Furthermore, the crimped head portions are received in the counterbore portions of the respective protruding insertion holes so as not to protrude beyond the axially outer end surfaces of the second inter-pocket portions, which form part of the second annular body. In other words, the axially outer end surface of the second annular body does not have an irregular shape. Therefore, when the bearing is used within a range At high rotational speeds, and because the lubricating oil is supplied from outside the bearing to the axially external end surface of the second annular body, the lubricating oil is less likely to be dispersed and penetrates the bearing more easily. Consequently, a lack of lubricating oil is less likely to occur, thus preventing bearing seizure. Furthermore, the resistance to agitation of the lubricating oil can also be reduced, thereby lowering the bearing torque.

[0023] - Arrangement 3 - Bearing according to arrangement 2, in which the head parts The crimped parts are melted and bonded to the inner surfaces of the respective counterbore parts.

[0024] With this arrangement, since the crimped head parts are melted and bonded to the inner surfaces of the counterbore parts of the respective protrusion insertion holes, the first annular body and the second annular body are coupled together more reliably.

[0025] - Arrangement 4 - Rolling according to any one of arrangements 1 to 3, in wherein each of the resin projections comprises: a stem portion; and a root portion having a cross-sectional area larger than a cross-sectional area of ​​the stem portion, and connected to a corresponding of the first buttress surfaces, and wherein each of the projection insertion holes comprises: a stem insertion portion through which one of the stem portions of the resin projections is inserted; and a root mounting portion mounted on one of the root portions of the resin projections.

[0026] With this arrangement, when a displacement of the rolling elements occurs, a force (shear force) is applied which causes the first annular body and the second annular body to slide in the circumferential direction. The force is received by the root sections of the resin protrusions. Thus, the moments of force acting on the root positions of the resin protrusions are low, and breakage of the resin protrusions can be reliably prevented.

[0027] - Arrangement 5 - Rolling according to any one of arrangements 1 to 4, in wherein the rolling elements are balls, wherein the axially inward end surfaces of the first lap-forming parts and the axially inward end surfaces of the second lap-forming parts comprise inner lap surfaces having an axially concave hemispherical shape, and wherein each of the inner lap surface is formed with an oil reservoir throat extending to both circumferential sides through a bottom of the inner lap surface.

[0028] With this arrangement, the lubricating oil is kept in the oil reservoir grooves, so that a lack of lubricating oil can be prevented even when the amount of lubricating oil supplied from the outside is low.

[0029] - Arrangement 6 - Bearing according to arrangement 5, in which a groove width a of each of the oil reservoir grooves in the inner pocket surfaces is fixed to a < (b / 3), where b is a radial width of one of the pockets, and in which a depth c (mm) of each of the oil reservoir grooves is fixed to c < 1.0.

[0030] With this arrangement, since the throat width of each oil reservoir throat is less than the radial width of the pocket and the oil reservoir throat is also shallow, the lubricating oil can be effectively retained in the oil reservoir throat due to the surface tension action of the lubricating oil.

[0031] -Arrangement 7 - Bearing according to arrangement 5 or 6, in which a length d of each of the oil reservoir grooves seen in the axial direction is fixed at (e / 2) < d, where e is a diameter of one of the rolling elements.

[0032] With this arrangement, lubricating oil can be supplied to sufficient areas of the surfaces of the rolling elements.

[0033] - Arrangement 8 - Rolling according to any one of arrangements 5 to 7, in wherein each of the first parts of the pocket formation is formed with a first oil hole, one end of which is open towards an inner surface of a corresponding oil reservoir groove, and the other end of which is open towards an axially outer end surface of the first part of the pocket formation, and wherein each of the second parts of the pocket formation is formed with a second oil hole, one end of which is open towards an inner surface of a corresponding oil reservoir groove, and the other end of which is open towards the axially outer end surface of the second part of the pocket formation.

[0034] With this arrangement, the lubricating oil can be introduced from the outside into the oil reservoir grooves through the first oil holes or the second oil holes.

[0035] - Arrangement 9 - Rolling according to any one of arrangements 1 to 8, in wherein the number of pockets is even, wherein the number of first stop surfaces is even, and the first stop surfaces are circumferentially spaced from each other, wherein the number of second stop surfaces is even, and the second stop surfaces are circumferentially spaced from each other, wherein the first stop surfaces comprise: a first group of first stop surfaces formed with the resin protrusions, respectively; and a second group of first surfaces of stop surfaces each formed with a second protrusion insertion hole extending axially through a corresponding of the first interpocket parts, and the first group of first stop surfaces alternates circumferentially with the second group of first stop surfaces, in which the second stop surfaces comprise: a first group of second stop surfaces formed with the protrusion insertion holes, respectively; and a second group of second stop surfaces each formed with a second resin protrusion inserted through one of the second protrusion insertion holes of the second group of first stop surfaces;and the first group of second stop surfaces alternates circumferentially with the second group of second stop surfaces, and wherein each of the second resin protrusions of the second group of second stop surfaces has a second crimped head portion formed by fusing a distal end of the second resin protrusion, and disposed to prevent the second resin protrusion from protruding from one of the second protrusion insertion holes.

[0036] With this arrangement, it is possible to make the first annular body and the second annular body have the same shape, and thus to use common components such as the first and second annular bodies. It is therefore possible to reduce costs.

[0037] In order to achieve the above object, the present invention further proposes a manufacturing method for a bearing, the bearing comprising: an inner ring; an outer ring arranged radially outwards from the inner ring; a plurality of rolling elements arranged between the inner ring and the outer ring; and a resin cage made of a thermoplastic resin, retaining the rolling elements, the resin cage comprising: a first annular body; and a second annular body axially opposed to the first annular body, the first annular body comprising: a plurality of first pocket-forming parts;and a plurality of first interpocket parts, each formed with a first stop surface, and each formed between a corresponding circumferentially adjacent pair of first pocket-forming parts, the second annular body comprising: a plurality of second pocket-forming parts; and a plurality of second interpocket parts, each formed with a second stop surface, and each formed between a corresponding circumferentially adjacent pair of second pocket-forming parts, the first stop surfaces of the first interpocket parts being superimposed on the respective second stop surfaces of the second interpocket parts, pockets being defined between the respective first and second pocket-forming parts, and the rolling elements being received in the pockets; respective, axially extending resin projections being formed on all or part of the first buttress surfaces, respectively, projection insertion holes being formed, respectively, in all or part of the second buttress surfaces so as to extend axially through all or part of the second inter-pocket parts, and the resin projections being inserted through the respective projection insertion holes, the resin projections having, at the respective distal ends of the resin projections, crimped head parts to prevent the resin projections from exiting the projection insertion holes, and the manufacturing process comprising: a superposition step consisting of superimposing the first buttress surfaces on the respective second buttress surfaces so that the resin projections are inserted through the projection insertion holes;and a step of forming crimped head parts consisting, after the layering step, of forming the crimped head parts by pressing a heated template against the distal ends of the resin protrusions so that they are pushed and enlarged outwards while heating and melting the distal ends of the resin protrusions - arrangement 10;

[0038] EFFECTS OF THE INVENTION In the bearing of the present invention, since the first and second annular bodies of the resin cage are coupled together by providing crimped head portions to prevent the resin protrusions from protruding from the protrusion insertion holes, it is possible to combine them reliably. Furthermore, the crimped head portions are located in positions where they are visible when the first and second annular bodies are coupled together, making it easy to confirm whether the first and second annular bodies are fully coupled. Brief description of the figures

[0039] [Fig. 1] is a view of a bearing of a first embodiment seen axially. [Fig. 2] is a cross-sectional view taken along line II-II of [Fig. 1]. [Fig.3] is a cross-sectional view taken along line III-III of [Fig.2] so that a rolling element is located in the centre. [Fig.4] is an enlarged view illustrating a resin cage on [Fig.2] and its proximity. [Fig.5] is a view illustrating a state before a head part set in the resin cage on [Fig.4] is formed. [Fig.6] is a perspective view illustrating a state before coupling of the resin cage onto [Fig.3]. [Fig.7] is a flowchart illustrating a manufacturing process for the bearing on [Fig.1]. [Fig.8A] is a view illustrating a state just before a heated template is pressed against the distal end of a resin protrusion. [Fig.8B] is a view illustrating a state in which the distal end of the resin protrusion on [Fig.8A] is melted and begins to deform. [Fig.8C] is a view illustrating a state in which the distal end of the resin protrusion on [Fig.8B] is further deformed and just before the deformed part comes into contact with the lower surface of a counterbore part. [Fig.8D] is a view illustrating a state in which the heated jig is continuously pressed against the distal end of the resin protrusion from the state of [Fig.8C], thus fusing and gluing the crimped head portion to the inner surface of the counterbore portion. [Fig.9] is a view illustrating an inner pocket surface of the resin cage on [Fig.6]. [Fig. 10] is a cross-sectional view taken along line XX of [Fig. 9]. [Fig. 11] is a view of a bearing of a second embodiment viewed axially. [Fig. 12] is a cross-sectional view taken along line XII-XII of [Fig. 11]. [Fig. 13] is a cross-sectional view taken along line XIII-XIII of [Fig. 12] so that a rolling element is located in the centre. [Fig. 14] is a perspective view illustrating a state before coupling of a resin cage onto [Fig. 13]. [Fig. 15] is an axial view of a bearing of a third embodiment. [Fig. 16] is a cross-sectional view taken along line XVI-XVI of [Fig. 15]. [Fig. 17] is a cross-sectional view taken along line XVII-XVII of [Fig. 16] so that a rolling element is located in the centre. [Fig. 18] is a perspective view illustrating a state before coupling of a resin cage onto [Fig. 17]. Description of the implementation methods

[0040] - First embodiment - Figures 1 and 2 illustrate a bearing in which A resin cage according to a first embodiment of the present invention is used. This bearing comprises an inner ring 1; an outer ring 2 arranged radially outwards from the inner ring 1; a plurality of circumferentially spaced rolling elements 4 arranged in an annular inner bearing space 3 defined between the inner ring 1 and the outer ring 2; and a resin cage 5 (cage made of resin) retaining the rolling elements 4.

[0041] As used herein, the terms "axial" and "axially" refer to the direction along the central axis of the bearing; the terms "radial" and "radially" refer to a direction orthogonal to the central axis of the bearing; and the terms " "Circumferential" and "circumferentially" refer to the direction around the central axis of the bearing.

[0042] As illustrated in [Fig.2], the inner ring 1 has, on its outer periphery, an inner ring raceway groove 6 on which the rolling elements 4 roll; and cylindrical surfaces 7 having a uniform outer diameter and adjacent to the inner ring raceway groove 6. The inner ring raceway groove 6 is a circular arc groove which has a cross-section in the form of a concave circular arc symmetric in the axial direction, and which extends along the surfaces of the rolling elements 4. The inner ring raceway groove 6 is formed at the axial center of the outer peripheral surface of the inner ring 1 so as to extend in the circumferential direction.

[0043] The outer ring 2 has, on its inner periphery, an outer ring raceway groove 8 on which the rolling elements 4 roll; and cylindrical surfaces 9 having a uniform inner diameter and adjacent to the outer ring raceway groove 8. The outer ring raceway groove 8 is a circular arc groove which has a cross-section in the form of a concave circular arc symmetric in the axial direction, and which extends along the surfaces of the rolling elements 4. The outer ring raceway groove 8 is formed at the axial center of the inner peripheral surface of the outer ring 2 so as to extend in the circumferential direction.

[0044] The rolling elements 4 are radially interposed between the inner ring raceway groove 6 and the outer ring raceway groove 8. The inner bearing space 3 is open on both axial sides, between which the rolling elements 4 are interposed. This bearing is used by introducing lubricating oil supplied from outside the bearing into the inner bearing space 3 through an axial opening in the inner bearing space 3. The rolling elements 4 are balls in this embodiment. This bearing is a deep groove ball bearing.

[0045] The resin cage 5 comprises a first annular body 10 and a second annular body 11 axially opposed to the first annular body 10. The resin cage 5 is a combined cage formed by coupling the first annular body 10 and the second annular body 11 to each other such that the axially inner end surface of the first annular body 10 (i.e., the surface of the first annular body 10 axially opposed to the second annular body 11) and the axially inner end surface of the second annular body 11 (i.e., the surface of the second annular body 11 axially opposed to the first body 10) are aligned with the first annular body 10. annular body 10) are superimposed on each other. Both the first annular body 10 and the second annular body 11 are formed of a thermoplastic resin.

[0046] As a thermoplastic resin, a polyamide (PA) resin, a polyphthalamide (PPA) resin, a polyphenylene sulfide (PPS) resin, or a similar material may be used. It is preferable, from the point of view of stiffness, to mix a fiber-reinforced material into the thermoplastic resin material. Glass fiber, carbon fiber, or a similar material may be used as the fiber-reinforced material.

[0047] As illustrated in [Fig. 6], the first annular body 10 has a plurality of first pocket-forming parts 12 and a plurality of first inter-pocket parts 13. The first pocket-forming parts 12 are circumferentially spaced from one another. The first inter-pocket parts 13 are each formed between the corresponding circumferentially adjacent pair of first pocket-forming parts 12. The first annular body 10 is formed in an annular shape such that the first pocket-forming parts 12 alternate circumferentially with the first inter-pocket parts 13.

[0048] Similarly, the second annular body 11 has a plurality of pocket-forming second parts 14; and a plurality of inter-pocket second parts 15. The pocket-forming second parts 14 are circumferentially spaced from one another. The inter-pocket second parts 15 are each formed between the corresponding circumferentially adjacent pair of pocket-forming second parts 14. The second annular body 11 is formed in an annular shape such that the pocket-forming second parts 14 alternate circumferentially with the inter-pocket second parts 15.

[0049] As illustrated in [Fig. 3], the first inter-pocket portions 13 are opposed to the respective second inter-pocket portions 15. Furthermore, the first pocket-forming portions 12 are opposed to the respective second pocket-forming portions 14. Pockets 16 are defined between the respective first pocket-forming portions 12 and second pocket-forming portions 14, and the rolling elements 4 are received in the respective pockets 16. The pockets 16 are hole-shaped portions extending through the resin cage 5 in the radial direction (direction orthogonal to the surface of the sheet in [Fig. 3]), and the rolling elements 4 are received in the respective pockets 16 so as to protrude partially beyond the resin cage 5 towards the radially inner and outer sides.

[0050] The axially interior end surfaces of the first pocket formation parts 12 (end surfaces thereof opposite the respective second pocket formation parts 14), and the axially interior end surfaces of the second pocket formation parts 14 (end surfaces thereof opposite the respective first pocket formation parts 12) include interior pocket surfaces 17 having an axially concave hemispherical shape.

[0051] The axially external end surface 18 of the first annular body 10 (end surface on the left in [Fig. 3]) comprises a flat surface extending circumferentially and continuously around the entire circumference. That is to say, the axially external end surfaces 19 of the first pocket-forming parts 12 (end surfaces of these opposite the side facing the second pocket-forming parts 14), and the axially external end surfaces 20 of the first inter-pocket parts 13 (end surfaces of these opposite the side facing the second inter-pocket parts 15) form a flat surface that is perpendicular to the axial direction, and that extends circumferentially and continuously around the entire circumference of the first annular body 10.

[0052] Similarly, the axially external end surface 21 of the second annular body 11 (end surface on the right in [Fig. 3]) comprises a flat surface extending circumferentially and continuously around the entire circumference. That is to say, the axially external end surfaces 22 of the second pocket-forming parts 14 (the end surfaces of these opposite the side facing the first pocket-forming parts 12), and the axially external end surfaces 23 of the second inter-pocket parts 15 (the end surfaces of these opposite the side facing the first inter-pocket parts 13) form a flat surface that is perpendicular to the axial direction, and that extends circumferentially and continuously around the entire circumference of the second annular body 11.

[0053] As illustrated in [Fig. 4], first buttress surfaces 24, which are planar and perpendicular to the axial direction, are formed on the axially internal end surfaces of the respective first inter-pocket sections 13. Second buttress surfaces 25, which are planar and perpendicular to the axial direction, are formed on the axially internal end surfaces of the respective second inter-pocket sections 15. The first buttress surfaces 24 are superimposed on the respective second buttress surfaces 25.

[0054] Axially extending resin projections 26 are formed on the respective first buttress surfaces 24. Each resin projection 26 comprises a root portion 27 connected to the first buttress surface 24; a stem portion 28 connected to the root portion 27; and a crimped head portion 29 connected to the stem portion 28. The cross-sectional area of ​​the root portion 27 is larger than the cross-sectional area of ​​the stem portion 28. The cross-sectional area of ​​the root portion 27 can be fixed at 3.0 times or more and at 6.0 times or less the cross-sectional area The transverse portion of the stem 28 is formed. The root portion 27 is column-shaped (see [Fig. 6]; a quadrangular prism shape in [Fig. 6]) extending in the axial direction. The root portion 27 is formed such that one pair of lateral surfaces of the quadrangular prism of the root portion 27 is oriented in the circumferential direction, and the other pair of lateral surfaces is oriented in the radial direction. The axial length of the root portion 27 is less than the axial width dimension of the second interpocket portion 15 (i.e., the width dimension of the second interpocket portion 15 from its axially inner end surface to its axially outer end surface 23). The axial length of the root part 27 is fixed at 10 to 20% of the axial width dimension of the second inter-pocket part 15. The stem part 28 is formed in the shape of a column (see the [Fig.6] ; a cylindrical shape on the [Fig.6]) extending in the axial direction. The crimped head portion 29 is formed in a flange shape (a dome shape on the relevant drawing) projecting from the outer periphery of the stem portion 28 in the direction perpendicular to the longitudinal direction of the stem portion 28. .

[0055] Projection insertion holes 30 extending axially through the respective second inter-pocket parts 15 are formed in the second abutment surfaces 25. Each projection insertion hole 30 comprises a root mounting part 31 connected to the second abutment surface 25; a rod insertion part 32 connected to the root mounting part 31; and a counterbore portion 33 connected to the stem insertion portion 32. The root mounting portion 31 is a column hole (see [Fig. 6]; a quadrangular prism shape in [Fig. 6]) mounted on the root portion 27. The root portion 27 is mounted on the root mounting portion 31 such that a circumferential gap is not defined between the root mounting portion 31 and the root portion 27. The root mounting portion 31 is preferably formed such that a radial gap is also not defined between the root mounting portion 31 and the root portion 27.The stem insertion portion 32 is a column hole (a cylindrical shape in the corresponding drawing) through which the stem portion 28 is inserted. The stem insertion portion 32 is formed so that the stem portion 28 is installed in the stem insertion portion 32 with a loose fit, thus allowing smooth insertion of the resin protrusion 26 into the stem insertion portion 32 in a state in which the crimped head portion 29 has not yet been formed at the distal end of the resin protrusion 26.

[0056] The counterbore portion 33 has a lower surface 34; and lateral surfaces 35 extending from the lower surface 34. The lateral surfaces 35 of the counterbore portion 33 form a cylindrical shape. The entire crimped head portion 29 is received in the counterbore portion 33 so that the portion of The crimped head 29 does not protrude from the axially external end surface 23 of the second inter-pocket portion 15. A seating surface of the crimped head portion 29 is in contact with the lower surface 34 of the counterbore portion 33. The cross-sectional area of ​​the crimped head portion 29 is larger than the cross-sectional area of ​​the rod insertion portion 32 of the protruding insertion hole 30. The cross-sectional area of ​​the crimped head portion 29 is fixed at 1.5 to 6.0 times the cross-sectional area of ​​the rod insertion portion 32. The depth of the counterbore portion 33 is equal to or greater than the axial length of the crimped head portion 29. The depth of the counterbore portion 33 is fixed at 10 to 20% of the axial width dimension of the second inter-pocket portion 15.

[0057] As illustrated in [Fig. 9], the inner pocket surface 17 of each first pocket forming portion 12 has an oil reservoir groove 36 having a circular, arc-shaped cross-section extending at a constant depth (see [Fig. 10]) relative to the inner pocket surface 17. The oil reservoir groove 36 extends to both circumferential sides through the bottom 37 of the inner pocket surface 17 of the first pocket forming portion 12. More precisely, the oil reservoir groove 36 extends linearly in the direction perpendicular to an imaginary radial line L passing through the center of the pocket 16 when viewed in the axial direction. The oil reservoir groove 36 extends to portions at which the inner pocket surface 17 is connected to the corresponding adjacent first buttress surfaces 24.The two ends of the oil reservoir throat 36 are respectively open onto the corresponding first adjacent stop surfaces 24.

[0058] As illustrated in [Fig.3], an oil reservoir groove 36 is also formed in the inner surface of pocket 17 of each second pocket forming part 14. This oil reservoir groove 36 has the same structure as the oil reservoir groove 36 of the inner surface of pocket 17 of the first pocket forming part 12.

[0059] The oil reservoir groove 36 of the first pocket forming part 12 and the oil reservoir groove 36 of the second pocket forming part 14 are connected to each other at the two circumferential ends of the inner pocket surface 17 of the first pocket forming part 12 and at the two circumferential ends of the inner pocket surface 17 of the second pocket forming part 14 so as to form a single annular groove (i.e. an annular groove extending around the entire circumference of the inner pocket surfaces 17).

[0060] As illustrated in [Fig. 10], the throat width a of the oil reservoir throat 36 is fixed at a < (b / 3), where b is the radial width of the pocket 16. The depth c (mm) of the oil reservoir throat 36 is fixed at c < 1.0. The depth c of the oil reservoir throat 36 refers to the depth to the bottom 38 of the oil reservoir throat 36 from the part of the oil reservoir throat 36 connected to the inner surface of pocket 17.

[0061] As illustrated in [Fig.9], the length d (chord length) of the oil reservoir throat 36 viewed in the axial direction is fixed at (e / 2) < d, where e is the diameter of the rolling element 4 (see [Fig.3]).

[0062] A manufacturing process for the bearing described above is exemplified and described below with reference to the flowchart in [Fig.7].

[0063] - Preparation step - First, as illustrated in [Fig. 5], the elements The four rolling elements (plural) are placed between the inner ring 1 and the outer ring 2, and are positioned at equal intervals in the circumferential direction. Then, the first annular body 10 and the second annular body 11 are placed axially opposite each other so as to interpose the four rolling elements between them.

[0064] - Overlay step - After the preparation step, the first surfaces of The stops 24 of the first annular body 10 are superimposed on the respective second stop surfaces 25 of the second annular body 11 so that the resin projections 26 of the first annular body 10 are inserted through the projection insertion holes 30 of the second annular body 11. Prior to this, the lengths of the resin projections 26 are each fixed to a length enabling the resin projection 26 to protrude beyond the axially external end surface 23 of the second inter-pocket part 15. Furthermore, the peripheral edge of the distal end of each resin projection 26 has a beveled shape to smoothly insert the resin projection 26 through the projection insertion hole 30.

[0065] - Step of forming the crimped head portion - After the layering step, As illustrated in Figures 8A to 8D, the crimped head portions 29 are formed to prevent the resin protrusions 26 from protruding from the protrusion insertion holes 30, and the first annular body 10 and the second annular body 11 are coupled together. The crimped head portions can be formed by (i) pressing and melting the distal ends of the resin protrusions 26 with a heated jig 39 to push and expand them outward, and then (ii) solidifying the melted portions.

[0066] More specifically, the heated template 39, which is now at a high temperature, is pressed against the distal end of each resin protrusion 26 (see [Fig. 8A]), and the distal end of the resin protrusion 26 is melted by heat transferred from the heated template 39. The resin protrusion 26 is further pressed by the heated template 39 so as to enlarge a melted portion of the distal end of the resin protrusion 26, and so as to push and widen the melted portion of the resin protrusion 26 towards the outer side (see [Fig. 8B]). When the heating jig 39 is moved near the axially outer end surface 23 of the second inter-pocket portion 15 (see [Fig. 8C]), and the heating jig 39 is separated from the resin protrusion 26, the molten portion is naturally cooled and hardened, thus forming the crimped head portion 29. That is, the crimped head portion 29 refers to the head of the resin protrusion 26 comprising a portion formed by melting the distal end of the resin protrusion 26, followed by cooling and solidification of this distal end. Forced cooling can also be used to cool the molten resin.

[0067] In this embodiment, a portion corresponding to the crimped head portion 29 is formed at the distal end of the resin protrusion 26, and even after this portion is brought into contact with the lower surface 34 of the counterbore portion 33, the heated template 39 is continuously pressed against the distal end of the resin protrusion 26, thus fusing and bonding the crimped head portion 29 to the inner surface of the counterbore portion 33 (see [Fig.8D]).Whereas, in this embodiment, as a method for forming the crimped head part 29, hot crimping is exemplified and described in which a resin is melted by pressing the heated template 39, which is at a high temperature, against the resin, a method such as ultrasonic crimping may be used in which a resin is melted by the frictional heat generated by pressing an ultrasonically vibrating heated template 39 (sonotrode) against the resin.

[0068] In the rolling of this embodiment, as illustrated in [Fig. 4], after the first annular body 10 and the second annular body 11 are stacked one on top of the other so that the resin protrusions 26 are inserted through the respective protrusion insertion holes 30, the distal ends of the resin protrusions 26 are melted to form the crimped head portions 29, thereby preventing the resin protrusions 26 from exiting the protrusion insertion holes 30, and coupling the first annular body 10 and the second annular body 11 to each other. Thus, the first annular body 10 and the second annular body 11 can be reliably coupled together without spontaneous separation occurring between the first annular body 10 and the second annular body 11.

[0069] Furthermore, in this bearing, when the first annular body 10 and the second annular body 11 are coupled together, the crimped head portions 29 are located in positions where they are visible. Therefore, it is easy to confirm whether the first annular body 10 and the second annular body 11 are completely coupled together by visually checking whether the crimped head portions 29 have a shape that prevents them from protruding from the projection insertion holes 30.

[0070] Furthermore, in this rolling bearing, since the crimped head parts 29 are formed after the resin protrusions 26 are inserted through the respective protrusion insertion holes 30, it is possible to form the crimped head parts 29 so that each is sufficiently larger than the protrusion insertion hole 30, and thus ensure an overlap tolerance of the crimped head parts 29. Consequently, the first annular body 10 and the second annular body 11 can be reliably coupled together.

[0071] Furthermore, as illustrated in Figures 2 and 3, the axially external end surface 21 of the second annular body 11 is a flat surface that is perpendicular to the axial direction and extends circumferentially and continuously around the entire circumference. As illustrated in [Fig. 3], the crimped head portions 29 are received in the counterbore portions 33 of the respective protruding insertion holes 30 so as not to protrude the axially external end surfaces 23 of the second inter-pocket portions 15, which form part of the second annular body 11. In other words, the axially external end surface 21 of the second annular body 11 does not have an irregular shape.Therefore, when the bearing is used within a high-speed rotational range, and the lubricating oil is supplied from outside the bearing to the axially external end surface 21 of the second annular body 11, the lubricating oil is less likely to be dispersed and penetrates the bearing more readily. Consequently, a lack of lubricating oil is less likely to occur, thus preventing bearing seizure. Furthermore, the resistance to agitation of the lubricating oil can also be reduced, and thus the bearing torque can be lowered.

[0072] As illustrated in [Fig. 8D], since the crimped head portions 29 are melted and bonded to the inner surfaces of the counterbore portions 33 of the respective protrusion insertion holes 30, the first annular body 10 and the second annular body 11 are coupled together more reliably. While the outer periphery and the seating surface of each crimped head portion 29 can be melted and bonded to the counterbore portion 33, only the outer periphery of the crimped head portion 29 can be melted and bonded to the lateral surfaces 35 of the counterbore portion 33.

[0073] Furthermore, in this bearing, when, due to a misalignment of the rolling elements 4 illustrated in [Fig. 3], the rolling elements 4 press against the inner pocket surfaces 17 of the first annular body 10 or the second annular body 11, and a force (shear force) is applied which causes the first annular body 10 and the second annular body 11 to slide in the circumferential direction, the force is received by the root portions 27 of the resin projections 26. Thus, the moments the forces acting on the positions of the roots of the resin projections 26 are weak, and a breakage of the resin projections 26 can be reliably prevented.

[0074] In addition, the lubricating oil is kept in the oil reservoir grooves 36, so that a lack of lubricating oil can be prevented even when the amount of lubricating oil supplied from the outside is low.

[0075] Furthermore, as illustrated in [Fig.10], since the groove width a of each oil reservoir groove 36 is less than the radial width b of the pocket 16, and also since the oil reservoir groove 36 is shallow, the lubricating oil can be effectively retained in the oil reservoir groove 36 due to the surface tension action of the lubricating oil.

[0076] As illustrated in [Fig.9], since the lengths d of the oil reservoir grooves 36 viewed in the axial direction are long, the lubricating oil can be supplied to sufficient areas of the surfaces of the rolling elements 4 (see [Fig.3]).

[0077] - Second embodiment - Figures 11 to 14 illustrate a rolling in in which a resin cage 5 (made of resin) is used according to a second embodiment of the present invention. The second embodiment differs from the first embodiment only in that the first oil holes 40 are formed in the respective first pocket-forming portions 12, and the second oil holes 41 are formed in the respective second pocket-forming portion 14; and in that the axial width dimension of the resin cage 5 is smaller. The second embodiment is the same as the first embodiment in other respects. Thus, the elements of the second embodiment corresponding to those of the first embodiment are designated by the same reference numerals, and their description is omitted.

[0078] As illustrated in [Fig.13], the first oil holes 40 are formed in the bottoms 37 of the respective inner pocket surfaces 17 of the first annular body 10. One end of each first oil hole 40 is open in the shape of an ellipse towards the inner surface of the oil reservoir throat 36, and its other end is open in the shape of an ellipse towards the axially outer end surface 19 of the first pocket-forming part 12 (end surface thereof facing the side opposite the second pocket-forming part 14).

[0079] Similarly, the second oil holes 41 are formed at the bottoms 37 of the respective inner pocket surfaces 17 of the second annular body 11. One end of each second oil hole 41 is open in the shape of an ellipse towards the inner surface of the oil reservoir throat 36, and its other end is open in the shape of an ellipse towards the axially outer end surface 22 of the second pocket forming part 14 (end surface thereof facing the side opposite the first pocket forming part 12).

[0080] The axial width dimension of the resin cage 5 is substantially equal to the diameter of each rolling element 4 (more precisely, 0.90 times or more and 1.05 times or less the diameter of the rolling element 4). The axial width of the first annular body 10 (width length from each first abutment surface 24 to the axially external end surface 18 of the first annular body 10) is equal to the axial width of the second annular body 11 (width length from each second abutment surface 25 to the axially external end surface 21 of the second annular body 11).

[0081] In the bearing of this embodiment, the lubricating oil supplied from outside the bearing can be introduced into the oil reservoir grooves 36 through the first oil holes 40 or the second oil holes 4L. In addition, since the resin cage 5 has a small axial width dimension, it is possible to shorten the width dimensions of the outer ring 2 and the inner ring 1 according to the width dimension of the resin cage 5 (see [Fig. 12]), which saves space.

[0082] [Third embodiment] Figures 15 to 18 illustrate a bearing in which a resin cage 5 (resin cage) is used according to a third embodiment of the present invention. The third embodiment differs from the first embodiment only in that resin projections 26 and second projection insertion holes 42 are formed on the first thrust surfaces 24; second resin projections 43 and second projection insertion holes 30 are formed on the second thrust surfaces 25; and the first annular body 10 and the second annular body 11 have the same shape. The third embodiment is identical to the first embodiment in its other structures. Thus, the elements of the third embodiment corresponding to those of the first embodiment are designated by the same reference numerals, and their description is omitted.

[0083] As illustrated in [Fig. 18], the first pocket-forming parts 12, the number of which is an even number, are circumferentially spaced from one another, the first inter-pocket parts 13, the number of which is an even number, are circumferentially spaced from one another, and the first stop surfaces 24, the number of which is an even number, are formed on the respective first inter-pocket parts 13. Second pocket-forming parts 14, the number of which is an even number, and second inter-pocket parts 15, the number of which is an even number, are formed, and second stop surfaces 25, the number of which is an even number, are formed on the respective second inter-pocket parts 15. As illustrated in [Fig. 17], pockets 16, the number of which is an even number, are formed in the resin cage 5 so that they are spaced circumferentially from each other.

[0084] The first stop surfaces 24, the number of which is an even number, comprise a first group of first stop surfaces 24 each formed with an axially extending resin protrusion 26; and a second group of first stop surfaces 24 each formed with a second protrusion insertion hole 42 extending axially through the corresponding first interpocket portion 13, and the first group of first stop surfaces 24 alternates circumferentially with the second group of first stop surfaces 24, i.e. the resin protrusions 26 alternate circumferentially with the second protrusion insertion holes 42.

[0085] The second projection insertion holes 42 each comprise a root mounting portion 31 connected to the first stop surface 24; a rod insertion portion 32 connected to the root mounting portion 31; and a counterbore portion 33 connected to the rod insertion portion 32. The second projection insertion holes 42 have the same shape and structure as the projection insertion holes 30 in the second stop surfaces 25.

[0086] The second stop surfaces 25, of which there is an even number, comprise a first group of second stop surfaces 25, each formed with a projection insertion hole 30 extending axially through the corresponding second inter-pocket part 15; and a second group of second stop surfaces 25, each formed with a second resin projection 43 extending axially inserted through the second projection insertion hole 42; and the first group of second stop surfaces 25 alternates circumferentially with the second group of second stop surfaces 25, i.e. the second resin projections 43 alternate circumferentially with the projection insertion holes 30.

[0087] Each second resin projection 43 comprises a root portion 27 connected to the second abutment surface 25; a stem portion 28 connected to the root portion 27; and a second crimped head portion 44 connected to the stem portion 28. The second crimped head portion 44 is formed by fusing the distal end of the second resin projection 43. The second crimped head portion 44 has the same shape as the crimped head portion 29 at the distal end of the resin projection 26. The crimped head portion 29 prevents the resin projection 26 from protruding from the projection insertion hole 30, and similarly, the second crimped head portion 44 also prevents the second resin projection 43 from protruding from the second projection insertion hole 42. The second resin projection 43 has the same shape and structure as the resin projection 26 on the first stop surface 24.

[0088] With this arrangement, it is possible to make the first annular body 10 and the second annular body 11 have the same shape, and thus to use common components such as the first annular body 10 and the second annular body 11. It is therefore possible to reduce costs.

[0089] Whereas, in each of the above embodiments, the ball bearing in which the rolling elements 4 are balls is described, the present invention can also be applied to a bearing in which the rolling elements 4 are elements other than balls, for example, a bearing in which the rolling elements 4 are rollers.

[0090] The embodiments described above are merely examples in all respects, and the present invention is not limited to them. The scope of the present invention is not indicated by the above description, but by the claims, and is to be understood as including all modifications in meaning and scope equivalent to the scope of the claims.

[0091] DESCRIPTION OF REFERENCE SIGNS 1: Inner ring 2: outer ring 4: rolling element 5: Resin cage (cage made of resin) 10: first ring body 11: second annular body 12: First part of pocket training 13: First part inter-pocket 14: Second part of pocket training 15: Second part, inter-pocket 16: pocket 17: inner pocket surface 19: Axially outer end surface of the first part of pocket formation 22: Axially outer end surface of the second part of the pocket formation 23: Axially outer end surface of the second interpocket part 24: first stop surface 25: second stop surface 26: resin projection 27: part of root 28: stem part 29: Head part set 30: protrusion insertion hole 31: Root assembly part 32: Rod insertion part 33: counterbore section 36: Oil reservoir throat 37: bottom of the inner pocket surface 39: heated template 40: First oil spill 41: Second oil hole 42: Second projection insertion hole 43: second resin projection 44: second part of the set head a: width of the oil reservoir throat b: radial width of the pocket c: depth of the oil reservoir throat d: length of the oil reservoir throat viewed in the axial direction; e: diameter of the rolling element

Claims

1. Demands Bearing comprising: an inner ring (1); an outer ring (2) arranged radially outwards from the inner ring (1); a plurality of rolling elements (4) arranged between the inner ring (1) and the outer ring (2); and a resin cage (5) made of thermoplastic resin, and retaining the rolling elements (4), in which the resin cage (5) comprises: a first annular body (10); and a second annular body (11) axially opposed to the first annular body (10), in which the first annular body (10) comprises: a plurality of pocket-sized training first parts (12); and a plurality of first interpocket parts (13) each formed with a first stop surface (24), and each formed between a corresponding circumferentially adjacent pair of first pocket-forming parts (12), in which the second annular body (11) comprises: a plurality of second pocket-forming parts (14); and a plurality of second inter-pocket parts (15), each formed with a second stop surface (25), and each formed between a corresponding circumferentially adjacent pair of second pocket-forming parts (14), in which the first abutment surfaces (24) of the first inter-pocket parts (13) are superimposed on the respective second abutment surfaces (25) of the second inter-pocket parts (15), and in which pockets (16) are defined between the respective first pocket-forming parts (12) and second pocket-forming parts (14), and the rolling elements (4) are received in the respective pockets (16), characterized in that axially extending resin projections (26) are formed on all or part of the first abutment surfaces (24), respectively, in which protruding insertion holes (30) are formed, respectively, in all or part of the second buttress surfaces (25) so as to extend axially through all or part of the second interpocket parts (15), and the resin projections (26) are inserted through the respective projection insertion holes (30), and wherein the resin projections (26) have, at the respective distal ends of the resin projections (26), crimped head parts (29) to prevent the resin projections (26) from coming out of the projection insertion holes (30).

2. Bearing according to claim 1, wherein the axially outer end surfaces (22) of the second pocket-forming parts (14) and the axially outer end surfaces (23) of the second inter-pocket parts (15) form a planar surface that is perpendicular to an axial direction, and that extends circumferentially continuously around a whole circumference of the second annular body (11), and wherein the protruding insertion holes (30) have counterbore portions (33) in which the respective pressed head portions (29) are received so that the pressed head portions (29) do not protrude from the axially outer end surfaces (23) of all or part of the second inter-pocket parts (15).

3. Bearing according to claim 2, wherein the crimped head parts (29) are melted and bonded to the inner surfaces of the respective counterbore parts (33).

4. Bearing according to any one of claims 1 to 3, wherein each of the resin projections (26) comprises: a stem portion (28); and a root portion (27) having a cross-sectional area larger than a cross-sectional area of ​​the stem portion (28), and connected to a corresponding of the first thrust surfaces (24), and wherein each of the projection insertion holes (30) comprises: a stem insertion portion (32) through which one of the stem portions (28) of the resin projections (26) is inserted; and a root mounting portion (31) mounted on one of the root portions (27) of the resin projections (26).

5. A bearing according to any one of claims 1 to 4, wherein the rolling elements (4) are balls, wherein the axially inner end surfaces of the first pocket-forming parts (12) and the surfaces axially inner end portions of the second pocket-forming parts (14) include inner pocket surfaces (17) having an axially concave hemispherical shape, and in which each of the inner pocket surface (17) is formed with an oil reservoir throat (36) extending towards both circumferential sides through a bottom (37) of the inner pocket surface (17).

6. Bearing according to claim 5, wherein a groove width a of each of the oil reservoir grooves (36) in the inner pocket surfaces (17) is fixed to a < (b / 3), where b is a radial width of one of the pockets (16), and wherein a depth c (mm) of each of the oil reservoir grooves (36) is fixed to c < 1.

0.

7. Bearing according to claim 5 or 6, wherein a length d of each of the oil reservoir grooves (36) when viewed in the axial direction is fixed at (e / 2) < d, where e is a diameter of one of the rolling elements (4).

8. Bearing according to any one of claims 5 to 7, wherein each of the first pocket forming parts (12) is formed with a first oil hole (40) having one end open towards an inner surface of a corresponding oil reservoir groove (36), and having the other end open towards an axially outer end surface (19) of the first pocket forming part (12), and wherein each of the second pocket forming parts (14) is formed with a second oil hole (41) having one end open towards an inner surface of a corresponding oil reservoir groove (36), and having the other end open towards the axially outer end surface (22) of the second pocket forming part (14).

9. Bearing according to any one of claims 1 to 8, wherein the number of pockets (16) is an even number, wherein the number of first thrust surfaces (24) is an even number, and the first thrust surfaces (24) are circumferentially spaced from each other,

10. in which the number of second abutment surfaces (25) is an even number, and the second abutment surfaces (25) are circumferentially spaced from each other, wherein the first abutment surfaces (24) comprise: a first group of first abutment surfaces (24) formed with the resin projections (26), respectively; and a second group of first abutment surfaces (24) each formed with a second protrusion insertion hole (42) extending axially through a corresponding first interpocket portion (13), and the first group of first abutment surfaces (24) alternates circumferentially with the second group of first abutment surfaces (24), in which the second abutment surfaces (25) comprise: a first group of second abutment surfaces (25) formed with the protrusion insertion holes (30), respectively; and a second group of second stop surfaces (25) each formed with a second resin protrusion (43) inserted through one of the second protrusion insertion holes (42) of the second group of first stop surfaces (24), and the first group of second stop surfaces (25) alternates circumferentially with the second group of second stop surfaces (25), and wherein each of the second resin protrusions (43) of the second group of second stop surfaces (25) has a second crimped head portion (44) formed by melting a distal end of the second resin protrusion (43), and disposed to prevent the second resin protrusion (43) from exiting one of the second protrusion insertion holes (42). Manufacturing process for a bearing, the bearing comprising: an inner ring (1); an outer ring (2) arranged radially outwards from the inner ring (1); a plurality of rolling elements (4) arranged between the inner ring (1) and the outer ring (2); and a resin cage (5) made of a thermoplastic resin, retaining the rolling elements (4), in which the resin cage (5) comprises: a first annular body (10); and a second annular body (11) axially opposed to the first annular body (10), in which the first annular body (10) comprises: a plurality of first pocket-forming parts (12); and a plurality of first inter-pocket parts (13), each formed with a first stop surface (24), and each formed between a corresponding circumferentially adjacent pair of first pocket-forming parts (12), in which the second annular body (11) comprises: a plurality of second pocket-forming parts (14); and a plurality of second inter-pocket parts (15), each formed with a second stop surface (25), and each formed between a corresponding circumferentially adjacent pair of second pocket-forming parts (14), in which the first abutment surfaces (24) of the first inter-pocket parts (13) are superimposed on the respective second abutment surfaces (25) of the second inter-pocket parts (15), in which pockets (16) are defined between the respective first pocket-forming parts (12) and second pocket-forming parts (14), and the rolling elements (4) are received in the respective pockets (16), in which axially extending resin projections (26) are formed on all or part of the first abutment surfaces (24), respectively, in which projection insertion holes (30) are formed, respectively, in all or part of the second buttress surfaces (25) so as to extend axially through all or part of the second interpocket parts (15), and the resin projections (26) are inserted through the respective projection insertion holes (30), in which the resin projections (26) have, at their respective distal ends, crimped head portions (29) to prevent the resin projections (26) from exiting the projection insertion holes (30), and in which the manufacturing process includes: a layering step consisting of superimposing the first abutment surfaces (24) onto the respective second abutment surfaces (25) so that the resin protrusions (26) are inserted through the protrusion insertion holes (30); and a step of forming crimped head parts consisting, after the layering step, of forming the crimped head parts (29) by pressing a heated template (39) against the distal ends of the resin protrusions (26) so that they are pushed and enlarged outwards while heating and melting the distal ends of the resin protrusions (26).

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