Retainer and ball bearing

Abstract

In a holder in which a corner portion and a ring portion are integrated by synthetic resin molding, both suppression of deformation of the corner portion due to centrifugal force and suppression of strength reduction of a weld are taken into account. The ring portion (7) has a pocket bottom (9) on the other side in the axial direction in a pocket (12). The corner portion (8) has a base portion (10) connecting the pair of claws (11a, 11b) to each other and to the ring portion (7) in the axial direction throughout the pocket (12), and a pair of claws (11a, 11b) separated from each other. The claws (11a, 11b) have a pocket inner surface (13) on the pocket (12) side and an opposite surface (14) on the side opposite thereto. The base portion (10) has linking portions (10a, 10b) linking the claws (11a, 11b) to the ring portion (7) in the axial direction, respectively, and an intermediate portion (10c) connecting the linking portions (10a, 10b) to each other in the circumferential direction. A weld (W) is disposed in a resin region constituted by a circumferential direction region of the claws (11a) connected in the axial direction, the linking portions (10a), and the ring portion (7).

Description

Technical Field

[0001] This invention relates to a retainer integrally molded by injecting synthetic resin into a mold. Background Technology

[0002] As such a retainer, it is integrally injection molded with a ring portion extending in a circular shape and a plurality of corner portions protruding axially from the ring portion at equal intervals in the circumferential direction. A pocket formed by the adjacent corner portions and the ring portion in the circumferential direction on three sides is used as a space for accommodating the rolling elements. The aforementioned rolling elements and retainer are bearing components constituting a rolling bearing. The rolling elements housed in the pocket are located between the inner and outer raceways of the rolling bearing.

[0003] In the retainers of ball bearings, as ball bearings operate at higher speeds, countermeasures are taken to suppress the deformation of the corners due to centrifugal force. As a countermeasure, the paired claws protrude axially to one side in a manner that forms a concave space in the corner, thereby reducing the volume of the corner. Therefore, in the circumferential region where the concave bottom surfaces connecting the roots of these claws are located, the cross-sectional area of ​​the resin portion forming the corner and the ring is reduced (e.g., Patent Documents 1 and 2).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-46069

[0005] Patent Document 2: Japanese Patent Application Publication No. 2015-197210

[0006] In the retainer manufactured by injection molding, there is a confluence of molten resin injected into the mold, i.e., a weld. In the weld, the confluenced molten resins do not completely mix and solidify, resulting in relatively weak strength. In the retainers of Patent Documents 1 and 2, the weld is located near the bottom of the pocket in the ring or on the concave bottom surface of the corner.

[0007] However, the cross-sectional area of ​​the resin portion on one side of the retainer becomes the smallest at the section including the bottom of the pocket, so it is not preferable to place the weld near the bottom of the pocket.

[0008] Furthermore, if the weld is positioned on the concave bottom surface of the corner, the resin orientation at the weld becomes perpendicular to the resin flow direction, reducing the weld strength. That is, the boundary of the confluence (weld line) becomes a clearly defined weld, making it prone to breakage. Considering the reduced strength at the weld, the strength of the cross-section, including the concave bottom surface of the weld, relative to the smallest cross-section on the bottom of the pocket, may be insufficient during high-speed rotation. In particular, the higher the strength of the synthetic resin, the greater the tendency for the weld strength to decrease, resulting in a significant reduction in weld strength and increasing the likelihood of insufficient strength. Summary of the Invention

[0009] Therefore, the problem to be solved by the present invention is to achieve both suppressing the deformation of the corner caused by centrifugal force and suppressing the reduction of the weld strength in a retainer obtained by integrally molding the corner and the ring with synthetic resin.

[0010] To achieve the aforementioned problem, the present invention employs the following structure: a retainer integrally formed by injection molding of synthetic resin, comprising an annular portion extending in a circular shape and a plurality of corner portions protruding axially from the annular portion at equal intervals in the circumferential direction; a rolling element is received in a pocket surrounded on three sides by adjacent corner portions and the annular portion in the circumferential direction; wherein the annular portion has a pocket bottom at a position defining the other side in the axial direction within the pocket; and the corner portions have: a base, extending circumferentially to the point where adjacent pockets are connected to each other and axially to the annular portion; and a retainer. The claws, which are separated from each other in the circumferential direction, protrude from the base to one side in the axial direction. The claws have: an inner surface of a pocket facing the pocket; and an opposing surface located on the opposite side in the circumferential direction relative to the inner surface of the pocket. The base has: a pair of connecting portions that connect the pair of claws to the ring portion in the axial direction; and a middle portion that connects the pair of connecting portions to each other in the circumferential direction. The weld formed in the injection molding is disposed in the resin region formed by the claws, the connecting portions connected to the claws in the axial direction, and the circumferential region of the ring portion connected to the connecting portions in the axial direction.

[0011] According to the above structure, the opposing surfaces of the paired claws at the corner are concave spaces, which reduces the volume of the corner and suppresses corner deformation caused by centrifugal force. Furthermore, during injection molding, the molten resin flowing from one side to the other in the circumferential direction passes through the filling area at the bottom of the forming pocket, and the molten resin flowing from the other side to one side in the circumferential direction passes through the filling space in the middle part of the base of the forming corner. They then converge in a wide filling space that forms a weld seam by sequentially molding the claws, the connecting portion of the base, and the ring portion. This wide filling space is designed to significantly expand the cross-sectional area axially due to the inner surface of the forming claw pocket and the opposing surfaces. Therefore, the resin flow is easily disordered, and a clear weld seam is not easily formed in the cured resin area, effectively suppressing weld seam strength reduction. Furthermore, the weld seam is inclined relative to the resin flow rather than perpendicular, and the weld seam cross-section is also larger, thus effectively increasing weld seam strength. Therefore, weld seam strength reduction can also be suppressed.

[0012] Preferably, the opposing surface of the aforementioned claw has a corner portion that curves away from the inner surface of the pocket from a position on one side of the axial direction near the connecting portion axially connected to the claw, toward the other side of the axial direction. When considering the positional relationship between the weld and the corner portion on the outer periphery of the resin region having the weld, based on an imaginary plane including the central axis of the ring portion, it is preferable that the weld is configured not to protrude from the imaginary plane including the point on the corner portion that is closest to the pocket in the circumferential direction toward the corner portion. Thus, stress concentration at the root of the claw can be mitigated by the corner portion, and the weld can be formed by avoiding the corner portion where stress is relatively high.

[0013] Furthermore, when considering the positional relationship between the weld and the inner surface of the pocket on the outer periphery of the resin region having the weld, based on an imaginary plane including the central axis of the aforementioned ring portion, it is preferable that the weld is configured not to protrude from the imaginary plane including the boundary point of the inner surface of the pocket with the aforementioned base towards the inner surface of the pocket. The weld becomes longer on the outer periphery of the resin region due to the difference in circumference between the inner and outer peripheries of the retainer. The boundary point between the inner surface of the pocket and the base of the claw on its outer periphery is the base end of the claw on its outer periphery; therefore, if it exceeds this point, the aforementioned cross-sectional area increases significantly in the axial direction. Therefore, it is possible to suppress strength reduction by blurring the weld on the outer periphery of the resin region where the weld is relatively long.

[0014] Furthermore, when considering a one-sided resin cross-section obtained by cutting with an imaginary plane including the central axis of the aforementioned ring portion, if the cross-sectional area of ​​the one-sided resin cross-section including the bottom of the aforementioned pocket is set as A1, and the smallest cross-sectional area formed by the aforementioned ring portion and the aforementioned middle portion among the one-sided resin cross-sections at any circumferential position including the aforementioned middle portion is set as A2, then it is preferable that the cross-sectional area A2 is less than 3 times the cross-sectional area A1. This allows for a reduction in the volume of the corner portion by reducing the cross-sectional area A2.

[0015] Preferably, the cross-sectional area A2 is less than twice the cross-sectional area A1. This allows for further reduction in the volume of the corner portion.

[0016] Alternatively, the aforementioned corner portion may also have an ejector shaft protruding between the paired claws. When the area near the concave bottom between the paired claws is narrow, the ejector pin pushing the retainer out of the mold interferes with the opposing surfaces of the claws, making it impossible to properly push the middle portion of the base. If an ejector shaft protruding between the paired claws is formed, the ejector pin can abut against the ejector shaft to eject the retainer. Therefore, the present invention can be applied even when the outer diameter of the retainer is small.

[0017] The type of synthetic resin is not particularly limited. For example, thermoplastic resins or thermosetting resins can be used as the synthetic resins described above.

[0018] The location of the gate during injection molding, i.e. the gate mark formed on the retainer, can be configured, for example, on the surface forming the inner or outer diameter of the aforementioned ring portion and the aforementioned multiple corner portions.

[0019] A ball bearing comprising a retainer, an inner ring, an outer ring, and a plurality of rolling elements disposed between the raceways of the inner ring and the raceways of the outer ring, as described in this invention, is suitable for high-speed rotation by suppressing deformation at the corners and suppressing the reduction in weld strength.

[0020] As described above, by adopting the above structure, the present invention can simultaneously suppress the deformation of the corner caused by centrifugal force and suppress the reduction of weld strength in a retainer obtained by integrally molding the corner and the ring with synthetic resin. Attached Figure Description

[0021] Figure 1 This is an enlarged front view of the vicinity of the retainer according to the first embodiment of the present invention, shown from the radially outer side.

[0022] Figure 2 This is a cross-sectional view showing the ball bearing according to the first embodiment of the present invention.

[0023] Figure 3 Shown from one axial side Figure 1 A three-dimensional view of the retainer.

[0024] Figure 4 yes Figure 1 A side view of the axial side of the retainer.

[0025] Figure 5 yes Figure 4 The cross-sectional view of the VV line shown.

[0026] Figure 6 This is a partial side view of the retainer on one axial side according to the second embodiment of the present invention.

[0027] Figure 7 It means Figure 6 The equivalent of the retainer Figure 5 A partially enlarged sectional view of the cutting surface. Detailed Implementation

[0028] The following is based on the attached figures. Figures 1-5 The first embodiment, which is an example of the present invention, will be described.

[0029] Figures 1-5The retainer 1 shown is a bearing component for uniformly arranging a plurality of rolling elements 4 between the inner ring 2 and the outer ring 3 in the circumferential direction. The plurality of rolling elements 4 are arranged in a row in the circumferential direction between the raceway 5 formed on the inner side of the inner ring 2 and the raceway 6 formed on the outer side of the outer ring 3. The rolling elements 4 are composed of balls.

[0030] exist Figure 2 In this design, the central axes (not shown) of the retainer 1, inner ring 2, and outer ring 3 are coaxial, which is equivalent to the rotation center of the ball bearing in the design, i.e., the bearing central axis. Hereinafter, the central axis of the retainer 1 will be referred to as the "central axis".

[0031] Here, axial direction refers to the direction along the central axis. Additionally, "one side of the axial direction" refers to one direction of the axial direction. Figure 2 The middle is on the left. Additionally, the other side of the axis refers to the direction opposite to the one mentioned above. Figure 2 The center is on the right. Additionally, radial direction refers to the direction orthogonal to the central axis. Furthermore, radially outer refers to the direction radially away from the central axis. Figure 2 The middle refers to the upper side. Additionally, the radially inner side refers to the direction radially closer to the central axis. Figure 2 The middle refers to the lower side. Additionally, the circumferential direction refers to the direction along the circumference of a circle around the central axis. Furthermore, the imaginary plane orthogonal to the central axis is called the "radial plane." Additionally, the imaginary plane including the central axis is called the "axial plane."

[0032] like Figures 3-5 As shown, the retainer 1 is a molded part integrally formed by injection molding of synthetic resin, consisting of a ring portion 7 extending in a circular shape and a plurality of corner portions 8 protruding axially from the ring portion 7 at equal intervals in the circumferential direction. The entire retainer 1 is formed by injection molding.

[0033] The synthetic resin can be any resin that can be injection molded, and can be any of thermoplastic resins, thermosetting resins, crystalline resins, or non-crystalline resins. Alternatively, the synthetic resin can be a resin obtained by using thermosetting or thermoplastic resins as the main component and appropriately adding other thermosetting resins, thermoplastic resins, rubber, glass fiber, carbon fiber, carbon black, graphite, etc.

[0034] The ring portion 7 is composed of a continuous resin portion along the entire circumference. The corner portion 8 is composed of a cantilevered resin portion that protrudes hollowly from one side of the axial direction of the ring portion 7.

[0035] The outer and inner diameter surfaces of the ring portion 7 are cylindrical surfaces extending in the circumferential direction. The outer and inner diameter surfaces of the corner portions 8 are the same as the outer or inner diameter surfaces of the ring portion 7. The outer and inner diameters of the retainer 1 are respectively equivalent to the diameters of the imaginary cylindrical surfaces that are externally or internally connected to the ring portion 7 and the plurality of corner portions 8.

[0036] The ring portion 7 has a plurality of pocket bottoms 9 exposed on one side of the retainer 1 along its axial direction. The pocket bottoms 9 are evenly spaced on the same circumference. These pocket bottoms 9 form the portion of the ring portion 7 located on the outermost side along its axial direction. The ring portion 7 has another end face located at the other outermost end of the retainer 1 along its axial direction. The other end face of the ring portion 7 forms a flat surface along its radial direction throughout its circumference. The other side of the retainer 1 along its axial direction is formed by the ring portion 7.

[0037] exist Figure 1 , Figure 5 In the diagram, dashed lines L1 to L4 represent radial planes, and dashed lines L5 to L7 represent axial planes. Figure 1 , Figure 5 The radial plane L1 shown is located at the position where it contacts the bottom 9 of the pocket of the ring 7 in the axial direction. Figure 1 The radial plane L2 shown is located at a position that contacts the other end face of the ring 7 in the axial direction. Figure 1 The radial plane L3 shown is located at the position where it contacts the axially outermost part of the corner 8 in the axial direction.

[0038] like Figure 1 , Figure 5 As shown, the resin portion constituting the ring portion 7 exists in the axial region B1 between the radial plane L1 and the radial plane L2, and is continuous in the circumferential direction in the axial region B1.

[0039] The resin portion constituting the corner portion 8 exists in the axial region B2 between the radial plane L1 and the radial plane L3, and is discontinuous in the circumferential direction within the axial region B2.

[0040] The corner portion 8 has: a base portion 10, which is axially connected to the ring portion 7; and a pair of claws 11a and 11b, which protrude from the base portion 10 to one side in the axial direction.

[0041] The retainer 1 houses the rolling element 4 within a pocket 12 enclosed on three sides by adjacent corner portions 8, 8 and annular portion 7 in the circumferential direction. The pocket 12 is a space opening radially outward, radially inward, and axially to one side. The pockets 12 are formed in the same number N as the number of corner portions 8. Each pocket 12 houses one rolling element 4. The retainer 1 has a shape with N rotational symmetries about its central axis.

[0042] The pocket 12 extends radially between the outer and inner diameter surfaces of the retainer 1, but its radially outer opening and radially inner opening are not wide enough to allow the rolling element 4 to pass radially. The retainer 1 is a crown-shaped retainer that can accommodate multiple rolling elements 4 disposed between the inner and outer raceways 5 and 6 by causing elastic deformation of multiple corners 8 to open the opening on one side of the axial direction of the pocket 12 in the circumferential direction.

[0043] The resin surface forming the pocket 12 is shaped approximately along an imaginary sphere, including a contact area defining the pocket gap between the retainer 1 and the rolling element 4. The retainer 1 and the rolling element 4 are able to move relatively freely within the pocket gap. The center of this imaginary sphere coincides with the center of the rolling elements 4 arranged on the pitch circle diameter of the plurality of rolling elements 4. The resin surface forming the pocket 12 is symmetrical about an imaginary plane including its center and central axis.

[0044] The rolling element 4, which is in a state between the inner and outer raceways 5 and 6, presses the paired claws 11a and 11b axially from the claw tip, thereby causing each claw 11a and 11b to undergo elastic deformation, resulting in the opening of the axial side of the pocket 12 opening, and the rolling element 4 enters between the adjacent corners 8 and 8.

[0045] The bottom 9 of the pocket in the ring 7 defines the position of the other side in the axial direction within the pocket 12. That is, the bottom 9 of the pocket is the other side in the axial direction of the resin surface forming the pocket 12. Figure 1 The diagram shows the diameter D of the aforementioned imaginary sphere. The pocket bottom 9 is located at one end of the diameter D.

[0046] The base 10 of the corner portion 8 is composed of resin portions that are circumferentially connected to each other through adjacent pockets 12, 12. The paired claws 11a, 11b are composed of a first claw 11a and a second claw 11b that are circumferentially separated from each other. Each claw 11a, 11b is composed of a cantilevered resin portion that protrudes hollowly from one axial side of the base 10.

[0047] In the corner portion 8, a concave space with depth extending from the claw tip to the other side of the axial direction is formed between the paired claws 11a and 11b. As a result, the volume of the corner portion 8 is reduced compared to the case where the concave space is filled with resin. By reducing the volume of the corner portion 8, the centrifugal force acting on the corner portion 8 when the holder 1 rotates is reduced, and deformation of the corner portion 8 caused by centrifugal force can be suppressed.

[0048] The base 10 is composed of a pair of connecting portions 10a and 10b that connect the pair of claws 11a and 11b to the ring portion 7 in the axial direction, and an intermediate portion 10c that connects the pair of connecting portions 10a and 10b to each other in the circumferential direction.

[0049] Each claw 11a, 11b has: an inner surface 13 of the pocket facing the pocket 12; and an opposing surface 14 located on the opposite side in the circumferential direction relative to the inner surface 13 of the pocket.

[0050] The resin surface forming the pocket 12 is composed of the inner surface 13 of the pocket of the first claw 11a of the first corner portion 8, the inner surface 13 of the pocket of the second claw 11b of the second corner portion 8, and the bottom 9 of the pocket of the ring portion 7. The bottom 9 of the pocket is dotted, and the inner surfaces 13 of the pockets of the first claw 11a and the second claw 11b constitute the entire resin surface forming the pocket 12 except for the bottom 9 of the pocket.

[0051] Each claw 11a, 11b has an opposing surface 14 having: a angular surface 15, which curves away from the inner surface 13 of the pocket from one axial side of the connecting portion 10a, 10b that is axially connected to the claw 11a, 11b, towards the other axial side; and a curved surface 16, which curves from the angular surface 15 towards one axial side, approaching the inner surface 13 of the pocket. The boundary between the angular surface 15 and the curved surface 16 forms an inflection point. The circumferential width of each claw 11a, 11b is greatest at the root of each claw 11a, 11b, and decreases towards its tip.

[0052] The middle portion 10c of the base 10 has a concave bottom surface 17 that connects the roots of the paired claws 11a and 11b to each other in the circumferential direction. The concave bottom surface 17 is exposed on the side of the axial side of the retainer 1. The concave bottom surface 17 is a flat surface along the circumferential direction and radial direction.

[0053] The radial plane L4 is located at the root of each claw 11a, 11b on the outer diameter surface of the retainer 1. That is, the radial plane L4 is located at the boundary between the inner surface 13 of the pocket and the base 10 on the outer diameter surface of the retainer 1. In addition, the radial plane L4 is located at a position that contacts the concave bottom surface 17 in the axial direction.

[0054] The resin portion constituting the base 10 exists in the axial region B3 between the radial plane L1 and the radial plane L4, and is continuous in the circumferential direction between adjacent pockets 12. The resin portions constituting each claw 11a, 11b exist in the axial region B4 between the radial plane L3 and the radial plane L4, and adjacent claws 11a, 11b are discontinuous in the circumferential direction.

[0055] The axial plane L5 is located at the boundary point P1 on the outer diameter surface of the retainer 1, which includes the concave bottom surface 17 and the corner surface 15. Figure 1 The axial plane L6 shown is located at the boundary point P2 on the outer diameter surface of the retainer 1, including the inner surface 13 of the pocket and the base 10.

[0056] Each connecting portion 10a, 10b forms a resin surface on the outer diameter surface of the retainer 1 that corresponds to the area between the axial plane L5 and the axial plane L6 (i.e., the circumferential width of the claw 11a or claw 11b of the connected object) and is equivalent to the division of the axial region B3. Each intermediate portion 10c forms a resin surface on the outer diameter surface of the retainer 1 that corresponds to the area between adjacent axial planes L5, L5 in the circumferential direction (i.e., the circumferential distance between the paired connecting portions 10a, 10b) and is equivalent to the division of the axial region B3.

[0057] If we consider the single-sided resin section of the retainer 1 at any circumferential position when it is cut with an axial plane, then the ring portion 7, which is a continuous portion of the whole circumference, occupies the same position on the single-sided resin section at any circumferential position.

[0058] Here, the single-sided resin section refers to the resin section when the radial range between the outer diameter and the central axis of the retainer 1 is cut by an axial plane.

[0059] Let A1 be the cross-sectional area of ​​the single-sided resin section obtained by cutting with an axial plane including the bottom of the pocket 9. The single-sided resin section with cross-sectional area A1 is equivalent to... Figure 2 The resin cross-section of the retainer 1 shown, Figure 5 The resin cross-section in the lower part of the retainer 1 is shown. The cross-sectional area A1 is the smallest among any single resin cross-sections of the retainer 1.

[0060] Let A2 be the smallest cross-sectional area formed by the ring portion 7 and the middle portion 10c in a single-sided resin cross-section at any circumferential position including the middle portion 10c. The single-sided resin cross-section that becomes the smallest cross-sectional area A2 is equivalent to Figure 5 The resin cross-section on one side of the upper part of the retainer 1 shown.

[0061] In order to reduce the volume of the corner portion 8 by thinning the middle portion 10c in the axial direction, the cross-sectional area A2 is less than three times the cross-sectional area A1. In particular, in the example shown in the figure, the cross-sectional area A2 is less than twice the cross-sectional area A1.

[0062] exist Figure 4 In the diagram, radial arrows indicate the circumferential position of the gate G for injecting synthetic resin, and radial arrows also indicate the circumferential position of the weld W formed in the retainer 1 through injection molding. When the retainer 1 is ejected from the mold, it is sheared by the resin within the gate G, thereby forming a gate mark in the retainer 1 at the location of the gate G. The gate mark corresponding to the gate G can be located on either the outer or inner diameter surface of the retainer 1.

[0063] Weld W is configured from Figure 5The single-sided resin cross-section of cross-sectional area A2 shown on the upper side of the figure and the single-sided resin cross-section of cross-sectional area A1 shown on the lower side of the figure are offset from each other.

[0064] like Figure 1 As shown, consider a resin region consisting of a claw 11a (or 11b), a connecting portion 10a (or 10b) axially connected to the claw 11a (or 11b), and a ring portion 7 axially connected to the connecting portion 10a (or 10b) in a circumferential direction. Such resin regions exist in the same number as the claws 11a and 11b in the retainer 1, and are uniformly distributed in the circumferential direction within the retainer 1. If... Figure 1 Considering the example, on the outer diameter surface of the retainer 1, the area occupied by the outer periphery of a resin region is the range between adjacent axial planes L5 and L6 in the circumferential direction, and the range between radial planes L2 and L3 in the axial direction (axial regions B1 and B2).

[0065] exist Figure 1 The weld W on the outer diameter surface of the retainer 1 is schematically represented by a double-dotted line. Around the outer periphery of the resin region containing the weld W, the weld W is circumferentially positioned between adjacent axial planes L5 and L6.

[0066] Considering the positional relationship between the weld W and the corner portion 15 on the outer periphery of the resin region having the weld W, the weld W is configured not to protrude from the axial plane L7 of the corner portion 15, which includes a point P3 in the circumferential direction closest to the pocket 12. Point P3 becomes the boundary point between the corner portion 15 and the curved portion 16 on the outer diameter surface of the retainer 1. The weld W is circumferentially and axially away from the corner portion 15.

[0067] Furthermore, considering the positional relationship between the weld W on the outer periphery of the resin region having the weld W and the inner surface 13 of the pocket, the weld W is configured not to protrude from the axial plane L6, which includes the boundary point P2 of the base 10 in the inner surface 13 of the pocket, toward the inner surface 13. The weld W is separated from the bottom 9 of the pocket by more than D / 4.

[0068] The location and number of gates G, and the location and number of welds W, should be appropriately set so that all welds W formed on the retainer 1 are arranged in a resin area at a certain location. The number of gates G and the number of welds W should be appropriately determined based on whether the number N of pockets 12 is even or odd. The fewer the number of welds W, the better.

[0069] In the example shown, the number N of pockets 12 is 9. Therefore, without configuring at least two gates G and a weld W between each gate G, weld W cannot be formed in the aforementioned resin area. When the number N of pockets 12 is odd, such as... Figure 4 As shown, two gates G are respectively disposed at two locations that are separate from each other in the circumferential direction. A first weld W is formed between gates G and G that advance clockwise from the first gate G to the second gate G, and a second weld W is formed between gates G and G that advance counterclockwise from the first gate G to the second gate G. That is, the holder 1 has two gate marks and welds W that are separate from each other in the circumferential direction.

[0070] When the number N of the pockets 12 of the retainer 1 is changed to an even number, the gate G can be arranged only at one location in the circumferential direction, and the weld W can be formed at a position 180° opposite to the gate G. That is, the retainer 1 has a gate mark and a weld W.

[0071] like Figure 1 As shown, for the retainer 1, the corner portion 8 has: a base 10, extending circumferentially to the ring portion 7 where adjacent pockets 12, 12 are connected to each other circumferentially and axially; and a pair of claws 11a, 11b, which protrude axially from the base 10 at a position separated from each other circumferentially. Each claw 11a, 11b has: an inner surface 13 facing the pocket 12; and a facing surface 14 located circumferentially opposite the inner surface 13 of the pocket. On the opposite side; the base 10 has: a pair of connecting portions 10a and 10b that connect the pair of claws 11a and 11b to the ring portion 7 in the axial direction; and a middle portion 10c that connects the pair of connecting portions 10a and 10b to each other in the circumferential direction, so that the opposing surfaces 14 and 14 of the pair of claws 11a and 11b of the corner portion 8 are concave spaces between each other, which can reduce the volume of the corner portion 8 and suppress the deformation of the corner portion 8 caused by centrifugal force.

[0072] In addition, for the retainer 1, the ring portion 7 has a pocket bottom 9 positioned at the axially furthest side of the pocket 12. The weld W formed during injection molding is disposed in the resin region formed by the claw 11a, the connecting portion 10a axially connected to the claw 11a, and the circumferential region of the ring portion 7 axially connected to the connecting portion 10a. Therefore, the strength reduction of the weld W can be suppressed. That is, during the injection molding of the retainer 1, the resin flow around the weld W becomes... Figure 1 The trend is schematically illustrated by multiple arrows. If the molten resin flowing from one side of the circumferential direction to the other side in the filling space of the molding ring 7 is defined as the first resin flow (in... Figure 1The flow from left to right in the middle is designated as the second resin flow (where the molten resin flows from one side of the circumference to the other side of the circumference in the filling space of the molding ring 7). Figure 1 (The flow is from right to left). The first resin flow is diverted to the filling space of the molding claw 11b and collides with the transfer surface near the bottom of the pocket 9. After passing through the filling space of cross-sectional area A1, it reaches the filling space of the molding claw 11a. In contrast, the second resin flow, after passing through the filling space of the molding middle portion 10c with cross-sectional area A2, is diverted to the filling space of the molding claw 11b, collides with the transfer surface near the bottom of the pocket 9, and merges with the first resin flow in the wide filling space where the claw 11a, the connecting portion 10a, and the ring portion 7 (the aforementioned resin area) are formed in a series. Therefore, the first and second resin flows slow down near the filling spaces of the molding claws 11b and 11a, and there is a tendency for the flow to become turbulent. On the other hand, there is a tendency for the first resin flow to be faster than the second resin flow near the transfer surface at the other end of the ring portion 7. The first and second resin flows merge in a filling space with a significantly expanded cross-sectional area in the axial direction to form the inner surface 13 and the opposing surface 14 of the pocket of the forming claw 11a. Consequently, the resin flows are chaotic and easily mixed, making it difficult to form a clear weld W in the cured resin region. Furthermore, the weld W tends to form at an angle relative to the resin flow, rather than perpendicular to it, thus increasing the weld cross-section. Therefore, the retainer 1 can increase the strength of the weld W to suppress any decrease in weld strength.

[0073] Furthermore, for the retainer 1, the opposing surface 14 of the claw 11a has a corner portion 15. The corner portion 15 bends away from the inner surface 13 of the pocket from the axial side of the connecting portion 10a that is axially connected to the claw 11a to the other side of the axial direction. When considering the positional relationship between the weld W and the corner portion 15 on the outer periphery of the resin area with the weld W based on the imaginary plane (axial plane) including the central axis of the ring portion 7, the weld W is configured not to protrude from the imaginary plane (axial plane L7) including the point P3 that is closest to the pocket 12 in the circumferential direction in the corner portion 15 towards the corner portion 15. This allows the stress concentration at the root of the claw 11a to be mitigated by the corner portion 15. In addition, the weld W can be formed by avoiding the corner portion 15 where the stress becomes relatively high, thereby preventing damage from the weld W.

[0074] Furthermore, for the retainer 1, when considering the positional relationship between the weld W and the inner surface 13 of the pocket on the outer periphery of the resin region having the weld W based on an imaginary plane (axial plane) including the central axis of the ring portion 7, the weld W is configured not to protrude from the imaginary plane (axial plane L6) including the boundary point P2 of the base 10 in the inner surface 13 of the pocket towards the inner surface 13 of the pocket. Thus, during injection molding, even in the outer periphery of a relatively long resin region in the circumferential direction, the weld W is formed in a filling space region with a significantly expanded cross-sectional area in the axial direction. Therefore, the weld W can be blurred on the outer periphery of the relatively long resin region to suppress strength reduction.

[0075] Furthermore, for the retainer 1, when considering the single-sided resin cross-section obtained by cutting with an imaginary plane (axial plane) including the central axis of the ring portion 7, the smallest cross-sectional area A2 formed by the ring portion 7 and the middle portion 10c in any circumferential position of the single-sided resin cross-section including the middle portion 10c is less than 3 times the cross-sectional area A1 of the single-sided resin cross-section including the bottom of the pocket 9. This allows the cross-sectional area A2 to be reduced, thereby reducing the volume of the corner portion 8.

[0076] Compared to the non-welded area, the strength of the weld W sometimes decreases by about one-third per unit cross-sectional area. Therefore, as in the existing example, when the weld is placed in the cross-sectional area A2, it is preferable that the cross-sectional area A2 is at least three times the cross-sectional area A1 in terms of strength comparison relative to the cross-sectional area A1 (bottom of the pocket). On the other hand, as mentioned above, if the strength reduction is suppressed by placing the weld W in the resin area that deviates from the cross-sectional area A1 and the cross-sectional area A2, then the problem of strength comparison can be avoided even if the cross-sectional area A2 is less than three times the cross-sectional area A1.

[0077] In addition, the cross-sectional area A2 is less than twice the cross-sectional area A1, thereby enabling the retainer 1 to achieve a further reduction in the volume of the corner 8.

[0078] Furthermore, the ball bearing equipped with the retainer 1 is suitable for high-speed rotation by suppressing deformation of the corner 8 and suppressing the reduction of strength of the weld W.

[0079] based on Figure 6 , Figure 7 The second embodiment of the present invention will now be described. Furthermore, the differences from the first embodiment will only be described below.

[0080] The corner portion 20 according to the second embodiment has an ejector shaft 21 protruding between the paired claws 11a, 11b. The ejector shaft 21 protrudes axially from the concave bottom surface 17 and the corner portion 15. The ejector shaft 21 is the part that is pushed by the ejector pin when ejecting from the mold, and has an ejection mark on its front end face.

[0081] Because the area near the concave bottom of the paired claws 11a and 11b is narrow, the ejector pin that pushes the retainer out of the mold interferes with the opposing surfaces 14, 14 of the claws 11a and 11b, preventing proper pushing of the concave bottom surface 17. If an ejector shaft 21 is formed, the ejector pin pushes against the ejector shaft 21 to eject the retainer. Therefore, the present invention can be applied even when the spacing between the pockets 12 of the retainer is narrow.

[0082] Furthermore, the cross-sectional area is increased by ejector shaft 21, but if weld W is placed here, stress concentration will occur at the root of ejector shaft 21, resulting in unstable strength. Ejector shaft 21 does not actually extend to the adjacent pockets 12, 12 are connected to each other in the circumferential direction, therefore the cross-sectional area of ​​ejector shaft 21 is not included in the calculation of cross-sectional area A mentioned above.

[0083] The embodiments disclosed herein should be considered illustrative rather than limiting in all respects. Therefore, the scope of the invention is not limited to the foregoing description, but is indicated by the scope of protection claimed in this application, and is intended to include all modifications within the meaning and scope equivalent to the scope of protection claimed in this application.

[0084] Explanation of reference numerals in the attached figures

[0085] 1…Retainer; 2…Inner ring; 3…Outer ring; 4…Rolling element; 7…Ring portion; 8, 20…Corner portion; 9…Pocket bottom; 10…Base; 10a, 10b…Connecting portion; 10c…Intermediate portion; 11a, 11b…Claw; 12…Pocket; 13…Inner surface of pocket; 14…Opposing surface; 15…Corner portion; 17…Concave bottom surface; 21…Ejector shaft.

Claims

1. A retainer integrally formed by injection molding of synthetic resin, comprising an annular portion extending in a circular shape and a plurality of corner portions projecting axially to one side at equal intervals in the circumferential direction from the annular portion, wherein a rolling element is received in a pocket surrounded on three sides by adjacent corner portions and the annular portion in the circumferential direction. The retainer is characterized in that... The ring portion has a pocket bottom that defines the position of the other side of the axial direction in the pocket. The corner portion has: a base portion, and adjacent pockets in the circumferential direction are connected to each other in the circumferential direction and connected to the ring portion in the axial direction; A pair of claws, which are separated from each other in the circumferential direction, protrude from the base toward one side in the axial direction, and the claws have: an inner surface of a pocket facing the pocket; And the opposing surface, located on the side opposite to the inner surface of the pocket in the circumferential direction, the base has: a pair of connecting portions, which connect the pair of claws to the ring portion in the axial direction respectively; The middle section connects the paired connecting parts to each other in the circumferential direction. The weld formed in the injection molding process is disposed in the resin region formed by the claw, the connecting portion axially connected to the claw, and the circumferential region of the ring portion axially connected to the connecting portion. When considering the positional relationship between the weld and the inner surface of the pocket on the outer periphery of the resin region having the weld, based on an imaginary plane including the central axis of the ring portion, the weld is configured not to protrude from the imaginary plane including the boundary point of the base in the inner surface of the pocket toward the inner surface of the pocket.

2. The retainer according to claim 1, characterized in that, The opposing surface of the claw has a corner portion that curves away from the inner surface of the pocket, from a position on one side of the connecting portion axially connected to the claw towards the other side of the axial direction, up to the connecting portion. When considering the positional relationship between the weld and the corner portion on the outer periphery of the resin region having the weld, based on an imaginary plane including the central axis of the ring portion, the weld is configured not to protrude from the imaginary plane including the point in the corner portion that is closest to the pocket in the circumferential direction toward the corner portion side.

3. The retainer according to claim 1 or 2, characterized in that, When considering a single-sided resin cross-section obtained by cutting with an imaginary plane including the central axis of the ring portion, if the cross-sectional area of ​​the single-sided resin cross-section including the bottom of the pocket is set as A1, and the smallest cross-sectional area formed by the ring portion and the middle portion in the single-sided resin cross-section at any circumferential position including the middle portion is set as A2, then the cross-sectional area A2 is less than 3 times the cross-sectional area A1.

4. The retainer according to claim 3, characterized in that, The cross-sectional area A2 is less than twice the cross-sectional area A1.

5. The retainer according to claim 1 or 2, characterized in that, The corner portion has an ejector shaft protruding between the paired claws.

6. The retainer according to claim 1 or 2, characterized in that, Thermoplastic resin is used as the synthetic resin.

7. The retainer according to claim 1 or 2, characterized in that, Thermosetting resin is used as the synthetic resin.

8. The retainer according to claim 1 or 2, characterized in that, The injection molding gate mark is disposed on the surface forming the inner or outer diameter of the ring portion and the plurality of corner portions.

9. A ball bearing, characterized in that, have: The retainer as described in any one of claims 1 to 8; Inner circle; Outer ring; and The plurality of the rolling elements are received in the pocket when disposed between the inner ring and the outer ring.

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