JP2009197906A - Crowned retainer and ball bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a claw of crowned retainer from being damaged in whitening phenomenon or broken. <P>SOLUTION: An opening width A of a pair of claws 3, 3, which is formed in a plurality of pockets 2 opened circumferentially in a circular body 1 and at one side in the axial direction, is set to be 94-97% of diameter of a ball 4, and a projection length B from the circular body 1 in the axial direction of the claw 3 is set to be 10-20% of the diameter of the ball 4. Furthermore, by setting the opening width A to be the range, a mold-release characteristic of die at the time of manufacture and an interfitting easiness of the ball 4, and a sure holding of an interfit ball 4 can be compatible. Additionally, by setting the projection length B to be the range, the whitening phenomenon or breakage caused by a generation of big distortion in a root of the claw 3 when the ball 4 is interfit can be prevented from occurring. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crown-shaped cage that prevents whitening and breakage from occurring in a claw portion formed in the pocket when a rolling element is fitted into the pocket, and a ball bearing incorporating the crown-shaped cage. .

As shown in FIG. 3, the crown-shaped cage is formed with pockets 2 that are opened at one end in the axial direction at equal intervals on the entire circumference of the annular body 1, and a pair of pockets 2 on both sides of the opening of each pocket 2. Claw portions 3 and 3 are provided (see, for example, FIG. 4 of Patent Document 1).
The crown-shaped cage is arranged between the inner ring and the outer ring of the bearing, and the rolling elements 4 are fitted into the pockets 2, and the rolling elements 4 roll in the pockets 2. Smooth relative rotation is possible. The opening width A of the pair of claw portions 3 and 3 is usually in a range of 85 to 92% of the diameter of the rolling element 4 fitted in the pocket 2 and smaller than the diameter of the rolling element 4. For this reason, the rolling element 4 is pawled by the claw portion 3 and does not fall out of the pocket 2.
JP 2007-139025 A

  On the other hand, the crown-shaped cage can employ various materials such as a resin material and a metal material. However, in the case of the one made of a resin material, the production is often performed by injection molding. This injection molding is performed by pouring a raw material resin having fluidity into a mold and curing the raw material resin. After this curing, an external force is applied to release the crown-shaped cage from the mold.

When the mold is released, the mold part that forms the pocket 2 of the crown-shaped cage is larger than the opening width A of the pair of claws 3 and 3. The mold part is forcibly expanded so that the mold part is pulled out (forcibly removed) from the pocket 2. Also, when the rolling elements 4 are fitted into the pockets 2, it is necessary to expand the opening width A in the same manner.
At the time of these expansions, if the amount of strain of the claw part 3 made of a resin material exceeds the strength limit, plastic deformation occurs, whitening occurs near the base of the claw part 3 and the strength decreases, or the claw part 3 breaks. There is a risk of doing.

As a conventional technique for preventing this whitening phenomenon and breakage, a fibrous filler such as glass fiber or carbon fiber is premixed in a resin material before molding, and the strength of the resin material is improved by this fibrous filler. (See paragraph numbers 0017 to 0025 of Patent Document 2).
JP 2000-227120 A

  The strength improvement effect of the method for improving the strength with the fibrous filler varies greatly depending on the ratio of the filler to be added, the orientation of the fibers, and the degree of uniform dispersibility. For example, if the dispersion of the filler is insufficient, the adhesion between the resin material and the filler may be insufficient, and the strength may decrease. For this reason, it is necessary to pay close attention when mixing the filler and the resin material, and the work is complicated.

  Accordingly, an object of the present invention is to prevent the whitening phenomenon and breakage of the claw portion of the crown-shaped cage by means other than mixing the fibrous filler into the resin material.

  In order to solve the above-described problems, the present invention provides a plurality of pockets opened in one axial direction in the circumferential direction of the annular body, and a pair of the pockets facing each other in the circumferential direction of the annular body. In the crown-shaped cage for resin bearings in which the claw portion is formed, the tip opening width of the claw portion on both sides of the opening of the pocket is in the range of 94 to 97% of the diameter of the rolling element fitted in the pocket, The protrusion length in the axial direction of the claw portion from the annular body is set to a range of 10 to 20% of the diameter, and the crown-shaped cage is configured.

The opening width can be expanded by shortening the protruding length of the claw portion from the annular body in the axial direction. However, if the protrusion length is simply shortened, the flexibility of the claw portion is lost, and on the contrary, the smoothness such as mold release may be impaired. Therefore, while keeping the opening width within the above range as described above, the width of the annular body in the opening direction is reduced so that the protruding length in the axial direction is within the above range. Thereby, the said nail | claw part becomes what can deform | transform supplely and the said smoothness can be maintained.
As described above, by smoothly performing the mold release or the like, an excessive external force acts on the nail portion, and a whitening phenomenon occurs in the vicinity of the nail portion, resulting in a decrease in strength or breakage. Can be prevented.

In this configuration, the opening width is in the above range. When the opening width is smaller than the above range, the rolling element is inserted into the pocket when the mold is released from the mold, as in the conventional crown-shaped cage (the opening width is 85 to 92% of the rolling element diameter). At this time, it is necessary to greatly deform the claw portion. When the strain due to this deformation exceeds the strength limit, the plastic deformation region is reached, and the claw portion may be whitened or broken.
On the other hand, when the opening width is larger than the above range, since the mold release and the like can be performed smoothly, the whitening phenomenon and breakage are hardly caused, while the pawls are hardly pawled by the claw part, and There is a risk that the rolling element will fall out of the pocket.

Moreover, the protrusion length to the axial direction of the said nail | claw part shall be the said range. If the protrusion length is smaller than the above range, the deformation needs to occur at the short claw portion, and therefore the strain due to the deformation easily exceeds the strength limit and reaches the plastic deformation region. For this reason, in the nail | claw part, there exists a possibility that a whitening phenomenon and breakage may arise.
On the other hand, when the protruding length is larger than the above range, most of the load of the rolling element is applied to the claw portion having a relatively low strength as compared to the annular body having a relatively high strength. For this reason, there is an increased risk of the nail portion being broken due to an excessive load.

  A wide variety of known resin materials can be used as the resin material used for the crown-shaped cage having the above-described configurations. Among them, polyamide-based resins such as nylon 66 and nylon 46 are preferable.

  This is because the polyamide-based resin has sufficient characteristics (such as mechanical strength and solid lubricity) as a cage material, and is superior in material cost as compared with other resin materials.

  The above-mentioned crown-shaped cage is used by being incorporated in a ball bearing. This ball bearing has a low rolling resistance of the rolling elements and is suitable for high-speed use. For this reason, it can be used by being incorporated in a speed reducer of a device that requires a particularly smooth and agile operation, such as a traveling mechanism of a construction machine hydraulic excavator or a movable arm portion of a robot.

  According to this invention, the opening width of the pair of claw portions facing each other is within a predetermined range, and the protruding length of the claw portion from the annular body in the axial direction is also within the predetermined range. Even when an external force is applied to the nail portion during the process, the nail portion can be elastically deformed flexibly. For this reason, the whitening phenomenon and breakage of the nail | claw part resulting from excessive distortion can be prevented, and the intensity | strength of this nail | claw part can be ensured. By ensuring the strength of the claw portion in this manner, the rolling element fitted in the pocket can be stably supported by the claw portion, and a smooth rotating state of the rolling element can be ensured.

  A crown-shaped cage according to the present invention will be described with reference to FIG. This crown-shaped cage has a plurality of pockets 2 opened in one axial direction (upward in the figure) in the circumferential direction of the annular body 1. A pair of nail | claw parts 3 and 3 which oppose a direction are formed. The claw portion 3 has the smallest opening width A at its tip. The inner surface of the pocket 2 is a part of a spherical surface, and the balls 4 fitted in the pocket 2 can roll smoothly.

  This crown-shaped cage is made of a polyamide-based resin and is manufactured by an injection molding method. In this injection molding method, a heated and softened resin material is supplied into a mold and then cooled while pressure is applied to mold the resin material into a predetermined crown-shaped cage shape. After the cooling, the mold is released from the crown-shaped cage as a whole while removing the mold part forming the pocket 2 from the pocket 2.

  The opening width A of the opening formed by the pair of claw portions 3 and 3 is designed to be in the range of 94 to 97% of the diameter of the ball 4 to be fitted into the pocket 2. This optimum range is determined by experiment, and by setting it as this range, it is possible to achieve both the mold releasability of the mold and the ease of fitting the ball 4 and the reliable holding of the fitted ball 4.

  Further, the protruding length B in the axial direction of the claw portion 3 from the annular body 1 is a length from the tip of the claw portion 3 to a position where the maximum stress is concentrated, and is in a range of 10 to 20% of the diameter of the ball 4. Designed to be This optimum range is also determined by experiment as described above. Since this nail | claw part 3 is an elastic body, it can deform | transform when external force acts. The flexibility of the claw portion 3 varies depending on the protruding length B.

  For example, FIG. 2 shows a process in which balls 4 as rolling elements are fitted into the pockets 2 in which the claw portions 3 having different opening widths A and protruding lengths B are formed. In order to fit the ball 4 into the pocket 2, the opening width A is expanded to the diameter of the ball 4 while the ball 4 is brought into contact with the toes of the pair of claw portions 3 and 3 ((a) and ( (See broken line in b)). At this time, if the projecting length B is within the predetermined range while the opening width A is within the predetermined range, the entire claw portion 3 can be deformed smoothly (see FIG. 5A). For this reason, the distortion in the vicinity of the base of the claw portion 3 (see θa in FIG. 3A) is small, and the whitening phenomenon and breakage are unlikely to occur.

  On the other hand, when the opening width A is smaller than the predetermined range and the projecting length B is smaller than the predetermined range, a large deformation occurs near the root of the claw portion 3 (see FIG. 4B). ). For this reason, the distortion in the vicinity of the root is larger than that in the case where the opening width A or the like is within the predetermined range as described above (see θb in FIG. 5B, θa <θb), It is easy to break.

  When the ball 4 is fitted in the pocket, the pair of claw portions 3 and 3 return to the original opening width A due to their elastic force. In this state, since the ball 4 is pawled by the claw portion 3, the ball 4 can stably roll without dropping from the pocket 2.

  Thus, by changing the shape of the claw portion 3, the opening width A and the protruding length B are changed to prevent the whitening phenomenon or breakage of the claw portion 3. Can be used in Among these ball bearings, it is suitable for a construction machine hydraulic excavator, a speed reducer for a movable part of a robot, etc., which require a particularly smooth and agile operation.

  In this embodiment, the opening width A is in the range of 94 to 97% of the rolling element diameter and the protrusion length B is in the range of 10 to 20% of the rolling element diameter. It is also conceivable that only one of the lengths B is within the above range. This is because, if at least one is within the above range, an effect of suppressing the whitening phenomenon or breakage of the nail portion 3 can be exhibited.

  Moreover, in the said embodiment, the method of mixing a fibrous filler with a resin material can also be employ | adopted together. This is because the strength of the resin material itself is improved by the fibrous filler, and the effect of suppressing the whitening phenomenon and breakage is further enhanced by a synergistic effect by optimizing the shape of the claw portion 3.

Side view of crown-shaped cage according to the present invention It is a side view which shows the insertion process of the ball | bowl to a crown shape holder | retainer, Comprising: (a) is when both opening width and protrusion length are in a predetermined range, (b) is both opening width and protrusion length are predetermined. If smaller than range Side view showing a typical crown cage

Explanation of symbols

1 Toroidal body 2 Pocket 3 Claw 4 Ball (Rolling body)
A Opening width B Protrusion length

Claims (4)

A plurality of pockets (2) opened in one axial direction are provided in the circumferential direction of the annular body (1), and a pair of pockets (2) facing the circumferential direction of the annular body (1) is provided. In the crown-shaped cage for resin bearings in which the claw portions (3, 3) are formed,
The tip opening width (A) of the claw portions (3, 3) on both sides of the opening of the pocket (2) is in the range of 94 to 97% of the diameter of the rolling element (4) to be fitted into the pocket (2), and A crown-shaped cage, wherein a length (B) of the claw portion (3) protruding from the annular body in the axial direction is in a range of 10 to 20% of the diameter.   The crown-shaped cage according to claim 1, wherein the resin is a polyamide-based resin.   A ball bearing incorporating the crown-shaped cage according to claim 1.   The ball bearing according to claim 3, wherein the ball bearing is used by being incorporated in a reduction gear.

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