JP2007333187A - Resin made crown cage for ball bearing, and ball bearing with the cage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin made crown cage for a ball bearing, and a ball bearing with the cage integrated wherein whitening or breakage of a claw part is not caused in a molding process and bearing-assembly, occurrence of deformations during use of the bearing is suppressed, and the durability is ensured. <P>SOLUTION: The resin made crown cage comprises: ring parts 2; and claws 3 formed at a plurality of positions extendedly in the circumferential direction from the respective ring parts 2. Claws 3 are faced in pairs to each other, and a recess 4 is formed in the ring part 2 between the pair of claws 3 opposed to each other. A pocket 5 for holding a ball 6 is formed of the each pair of claws 3 and the recess 4. The distance Hw between the tip ends of the opposed claws 3 is made narrower than the diameter Dw of the ball 6. The whole of the cage 1 is formed of a resin. The claws 3, and the root parts 3a of the claws 3 are formed of a material of an elastic-modulus smaller than that of the main-body part 1A of the other part of the cage 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ball bearing, for example, a crown-shaped resin cage in an angular ball bearing used as a bearing for a general industrial machine, a wheel for an automobile, or the like, and a ball bearing incorporating the cage.

  As a crown-shaped resin cage incorporated in a ball bearing, one formed of a nylon resin (polyamide resin) reinforced with glass fiber or the like is widely known. In such a crown-shaped resin retainer, a pocket for holding balls at equal intervals is formed by a pair of claws, and an opening between the tips of the claws is open in the axial direction. The distance between the tips of the opposing claws is narrower than the diameter of the ball so as to securely hold the ball and not fall off. Patent Document 1 discloses a crown-shaped resin cage for a ball bearing having such a structure (see FIGS. 7 and 8 of the same document).

  FIG. 6 is a cross-sectional view showing a pocket portion of the crown-shaped resin cage for ball bearings. The cage 50 shown in FIG. 6 has a ring portion 51 and a plurality of circumferentially extending claws 52 extending in the axial direction from the ring portion 51, and the ring portion 51 is provided between a pair of opposed claws 52. A recess 53 is formed. Each of the pair of claws 52 and the recess 53 forms a pocket 54 for holding the ball 55, and the opening of the pocket 54 is open in the axial direction. The pocket entrance dimension Hw of the opening is set smaller than the ball diameter Dw and has a predetermined allowance so that the ball 55 is securely held and the ball 55 does not fall off. The tightening allowance is set so that the ball 55 does not fall off and the insertion force of the ball during assembly is not excessive.

Further, in Patent Document 2, in order to prevent so-called “unreasonable punching” at the time of demolding when forming the tightening allowance of the ball, the column portion inner diameter side portion and the outer diameter side portion forming the claw portion are separately provided. It is proposed to remove the molds in the opposite directions.
JP 2002-195269 A JP 10-103359 A

When the crown-shaped resin cage 50 as shown in FIG. 6 is produced by molding, the mold is forcibly removed in the direction of the white arrow in FIG. At this time, the opening of the pocket 54 instantaneously expands from the pocket entrance dimension Hw to the pocket diameter HP, and the claw 52 is deformed to generate stress. In particular, since stress concentrates on the root portion 52a of the nail 52, a whitening phenomenon occurs in this portion (a phenomenon that turns whitish), and in the worst case, breakage may occur starting from the nail root portion. Further, since the relationship between the pocket entrance dimension Hw and the ball diameter Dw is set so as to have a predetermined allowance as described above, when the ball 55 is inserted into the pocket 54 when the bearing is assembled, Whitening and damage due to stress concentration on the root 52a can occur. The reason why such whitening phenomenon or breakage occurs is because a high-strength resin material having a large elastic modulus and not easily elastically deformed is used.
However, it is not preferable to use a material having a low elastic modulus (low strength) because it causes problems in deformation and durability when the bearing is used.

  In addition, in the case of the resin cage for angular ball bearings proposed in Patent Document 2, there is no concern that whitening phenomenon or damage will occur because the above-mentioned force is not removed. A troublesome work and apparatus configuration for demolding in opposite directions are required.

  An object of the present invention is to provide a crown-shaped resin cage for a ball bearing that does not cause a whitening phenomenon or breakage of a claw part at the time of molding or assembly of a bearing, and that can prevent deformation during use of the bearing and ensure durability. It is to provide a ball bearing incorporating this.

  The crown-shaped resin cage for a ball bearing according to the present invention has a ring portion and a plurality of circumferentially extending claws extending in the axial direction from the ring portion, and the claws are opposed to each other one by one. A concave portion is formed in the ring portion between the claws, and a pocket for holding the ball is formed by each of the pair of claws and the concave portion, and the distance between the tips of the opposing claws is determined by the diameter of the ball. In a crown-shaped resin cage for ball bearings in which the entire cage is made of resin, each claw and the base portion of the claw have a smaller elastic modulus than the main body portion which is another part of the cage. It is characterized by comprising a material.

  According to this structure, since each nail and the base part of this nail are made of a material having a smaller elastic modulus than the main body part, which is another part of this cage, the resin cage is used by using a mold. When molding, even if a force that spreads the mold in the pocket part and forcibly pulls it out to the nail part acts, the nail part is elastically deformed and the generation of stress is suppressed, and the base part of the nail is suppressed. There is no concentration of stress. Also, when a ball is pressed into the pocket from between the opposing claws during the assembly of the bearing, a force that pushes the claw part acts, but in this case, the claw part is elastically deformed to suppress the generation of stress. The stress does not concentrate at the base of the nail. Thereby, the whitening phenomenon of the base part of a nail | claw and the generation | occurrence | production of the damage starting from a base part are suppressed. Further, since the main body portion is made of a material having a large elastic modulus, deformation when the main body portion is incorporated in the bearing and used under the use of the bearing is suppressed, and durability is ensured.

  In the present invention, the main body portion may be a fiber reinforced polyamide resin, and the nail and the base of the nail may be an unreinforced polyamide resin. Fiber reinforced polyamide resin (nylon resin) is widely used as a constituent material of this type of crown bearing cage for ball bearings, and the main body part has high strength characteristics. It is effective in suppressing and ensuring durability. In addition, by using non-reinforced polyamide resin for the nails and base of the nail, the above-mentioned whitening phenomenon and breakage of the base of the nail are suppressed and the same type of resin as the main body is used as the base. Unity with the part is ensured.

In this invention, the said main-body part, a nail | claw, and a nail | claw root part are good also as what was formed with the different resin material by two-color molding. It is also possible to form the main body part and the claw part individually and then bond them together by bonding or ultrasonic welding. However, in this case, man-hours for bonding and welding are required, and bonding errors occur. easy. Two-color molding is excellent in this sense because it can be produced with high accuracy in a single molding process, and post-processing after molding is not required, and the cost can be reduced. Here, the two-color molding is a technique of simultaneously molding resins of different colors and different materials, and is a method of molding with a dedicated molding machine having two injection mechanisms and a gate for one mold.
In the case of two-color molding, considering the adhesion strength at the boundary surface (weld line) of each material, the combination of the base polymer is unified (for example, fiber reinforced polyamide resin and non-reinforcing material) rather than the combination of completely different materials. (Such as a combination of polyamide resins) is desirable.

  A ball bearing according to the present invention is characterized by incorporating any of the above-mentioned crown-shaped resin cages for ball bearings. According to this configuration, as described above, there is no concern about the whitening phenomenon or damage of the claw portion of the cage, the deformation of the cage during use of the bearing is suppressed, and durability is ensured. Durability is also ensured and the service life is extended.

  The crown-shaped resin cage for a ball bearing according to the present invention has a ring portion and a plurality of circumferentially extending claws extending in the axial direction from the ring portion, and the claws are opposed to each other one by one. A concave portion is formed in the ring portion between the claws, and a pocket for holding the ball is formed by each of the pair of claws and the concave portion, and the distance between the tips of the opposing claws is determined by the diameter of the ball. In a crown-shaped resin cage for ball bearings in which the entire cage is made of resin, each claw and the base portion of the claw have a smaller elastic modulus than the main body portion which is another part of the cage. Because it is made of material, it suppresses the concentration of stress on the base of the nail due to elastic deformation of the nail during molding or assembly of the bearing, thereby preventing whitening of the nail and preventing damage from the base of the nail. By suppressing the occurrence That. Further, the durability can be ensured by suppressing the deformation when using the built-in bearing in the bearing.

  Since the ball bearing according to the present invention incorporates one of the above-mentioned crown-shaped resin cages for ball bearings, there is no fear of whitening or damage of the claw portion of the cage, and deformation of the cage during use of the bearing Therefore, the durability of the ball bearing itself is ensured and the life is extended.

  An embodiment of a crown-shaped resin cage for ball bearings according to the present invention will be described with reference to FIGS. This ball bearing crown-shaped resin cage 1 is a cage for an angular ball bearing, and has a ring portion 2 and a plurality of claw portions 3 extending in the axial direction from the ring portion 2. Each pair of claws 3 faces each other, and a recess 4 is formed in the ring portion 2 between each pair of claws 3 facing each other, and the pair of claws 3 and the recess 4 hold the ball 6. Each pocket 5 is formed. The pockets 5 are equally arranged in the circumferential direction. The distance (pocket entrance dimension) Hw between the tips of the opposing claws 3 is made narrower than the diameter (ball diameter) Dw of the ball 6. The claw 3 is bent and formed in a bifurcated shape at the distal ends of a plurality of column portions 3A extending in the axial direction from the ring portion 2.

  The entire cage 1 is a molded body of resin, and each claw 3 and the base portion 3a of the claw 3 are formed from other parts of the cage 1, that is, the main body portion 1A including the ring portion 2 and the column portion 3A. Also, it is made of a resin material having a small elastic modulus. Specifically, the main body portion 1A is made of a fiber reinforced polyamide resin, and the claws 3 and the claw root portions 3a are made of a non-reinforced polyamide resin. As the fiber reinforced polyamide resin, 25% by weight of glass fiber is kneaded with nylon 66 (hereinafter referred to as PA66 + GF25), and as the non-reinforced polyamide resin, only nylon 66 (hereinafter referred to as PA66 natural) is used. Can be used. Table 1 shows typical physical property values of such a nylon resin.

  From Table 1, it is understood that the tensile modulus and flexural modulus of PA66 + GF25% are larger than PA66 natural. In addition, as a combination of the resin material of the main body portion 1A and the resin material of the nail 3 and the base of the nail 3a, in addition to the above-mentioned nylon resin, 30% by weight of a glass fiber containing polyphenylene sulfide resin is used. It is also possible to combine the resin reinforced with the above and a polyphenylene sulfide resin alone. In either case, the nail 3 and the nail root portion 3a are made of a resin material having a smaller elastic modulus than the main body portion 1A.

  The ball bearing crown-shaped resin cage 1 is integrally molded by a two-color molding method. That is, an injection mechanism for injecting a fiber-reinforced resin material into the main body portion 1A, an injection mechanism for injecting an unreinforced resin material into the nail 3 and the nail root portion 3a, and a gate are provided for one mold. A dedicated molding machine (not shown) is prepared, and the ball bearing crown-shaped resin cage 1 is integrally molded in a single molding process. And at the time of mold release, a metal mold | die is forcibly extracted by the part of the pocket 5 in the direction of the white arrow of FIG. At this time, the opening of the pocket 5 instantaneously expands from the pocket entrance dimension Hw to the pocket diameter HP, and the nail 3 and the nail root 3a are deformed. However, since the nail 3 and the nail root portion 3a are made of a resin material having a smaller elastic modulus than the main body portion 1A, the nail 3 and the nail root portion 3a have a sufficient amount of elastic deformation, and no stress is generated by this elastic deformation. Therefore, there is no concentration of stress on the nail root portion 3a, and neither the occurrence of the whitening phenomenon of the root portion 3a nor the damage starting from the root portion 3a is caused. Since the claw 3 is formed in a bifurcated shape at the tip of the column portion 3A, this shape characteristic promotes the elastic deformation and more effectively prevents stress concentration on the claw root portion 3a.

  Further, when the ball bearing crown-shaped resin cage 1 is incorporated in the bearing, the ball 6 is press-fitted into the pocket 5 so as to spread the pair of claws 3 facing each other. Since the deformation of the root portion 3a is accompanied by the same elastic deformation as described above, the stress concentration on the nail root portion 3a does not occur. The ball 6 inserted into the pocket 5 is stably held without coming out because the distance Hw between the tips of the opposing claws 3 is narrower than the diameter Dw of the ball 6. Furthermore, since the main body portion 1A is made of a resin material having a large elastic modulus and fiber reinforced, the body portion 1A is prevented from being deformed when the bearing is used, and durability is secured.

  4 and 5 show an example of an angular ball bearing using the crown-shaped resin cage 1 for ball bearings. FIG. 4 shows a single row angular contact ball bearing 10. The ball bearing crown-shaped resin cage 1 is incorporated in the outer ring 11 with each ball 6 held in the pocket 5, and then the inner ring 12 is incorporated. FIG. 5 shows a double row (two rows in the figure) angular contact ball bearing 20. This ball bearing 20 has two rows of outer rings 21 in common and two rows of inner rings 22 provided individually. Two rows of crown-shaped resin cages 1 for ball bearings in this case are prepared, and each ball 6 is held in the pocket 5 and incorporated in the outer ring 21, and then both rows of inner rings 22 are incorporated.

  When the angular ball bearings 10 and 20 are assembled, the balls 6 are inserted into the pockets 5 of the respective crown bearing cages 1 for ball bearings with the deformation of the claws 3. Since it is made of a resin material having a low modulus of elasticity including the portion 3a, no stress is generated due to the elastic deformation, no whitening phenomenon occurs due to stress concentration of the root portion 3a, and breakage starting from the root portion 3a There is no concern that this will occur. Furthermore, since the main body portion 1A is made of a fiber-reinforced high-strength resin material, deformation of the ball bearing crown-shaped resin cage 1 itself is suppressed when the angular ball bearings 10 and 20 are used. Durability is also secured, which contributes to a longer life as the angular ball bearings 10 and 20.

  In addition, the crown-shaped resin cage for ball bearings of this invention can be applied not only to angular ball bearings but also to deep groove ball bearings. In addition, the shape of the nail | claw 3 etc. is not limited to the thing of an illustration.

It is a partial top view of the crown-shaped resin retainer for ball bearings concerning one Embodiment of this invention. FIG. 3 is a cross-sectional view taken along line A-O-B in FIG. 1. It is CC sectional view taken on the line in FIG. It is a fragmentary sectional view of the angular ball bearing which incorporated the crown-shaped resin cage for ball bearings concerning one embodiment of this invention. It is a fragmentary sectional view of another angular contact ball bearing incorporating the cage. It is a fragmentary sectional view which shows the pocket part of the conventional crown-shaped resin cage for ball bearings.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Crown-shaped resin cage 1A for ball bearings ... Body part 2 ... Ring part 3 ... Claw 3a ... Claw root part 4 ... Recess 5 ... Pocket 6 ... Ball 10 ... Single row angular contact ball bearing (ball bearing)
20 ... Double row angular contact ball bearings (ball bearings)
Hw: Distance between the tips of the nails Dw: Diameter of the ball

Claims (4)

The ring portion has a plurality of circumferentially extending claws extending in the axial direction from the ring portion. Each of the claws is opposed to each other in pairs, and a recess is formed in the ring portion between the opposed pair of claws. Each of the pair of claws and the recess has a pocket for holding a ball, the distance between the tips of the opposing claws is narrower than the diameter of the ball, and the entire cage is made of resin. In the crown-shaped resin cage for bearings,
A crown-shaped resin cage for ball bearings, characterized in that each of the nails and the base portion of the nails are made of a material having a smaller elastic modulus than a main body portion which is another part of the cage.   2. A crown-shaped resin cage for ball bearings according to claim 1, wherein the main body portion is made of a fiber reinforced polyamide resin, and the claws and the base portion of the claws are made of an unreinforced polyamide resin.   3. A crown-shaped resin cage for ball bearings according to claim 1 or 2, wherein the main body portion, the claw and the claw root portion are formed of different resin materials by two-color molding.   A ball bearing incorporating the crown-shaped resin cage for a ball bearing according to any one of claims 1 to 3.

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