JPH0988968A - Cage for ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing cage consisting of a pectinate segment type cage with no slant in a claw part by means of plastic injection molding. SOLUTION: In a segment type ball bearing cage, consisting of plural pieces of divided cage pieces in the circumferential direction, and having each pocket where each cage piece holds a ball at a fixed interval in the circumferential direction, this is a ball bearing cage formed with a notch part 2 notched beyond a virtual line connecting each bottom of respective pockets toward the pocket opening side from an end at the opposite side to an end of the pocket opening side, in space among respective these pockets of respective cage pieces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball bearing cage.

[0002]

Bearings for swivel seats are used for medical equipment such as bearings for supporting a CT scanner rotary dome, construction machinery, railway vehicles, etc.
It is used in various large industrial machines. Usually, since the ball shaft cage that constitutes such a swivel seat bearing has a large diameter, for example, a plurality of comb-shaped segment cages as shown in FIG. 4 are arranged in the circumferential direction. This is used as a cage for ball bearings.

As such a comb-shaped segment type cage, for example, there is a technology relating to a bearing having a ball bearing cage which is connected in plural numbers in the circumferential direction (Patent Document 5).
-22086).

There are two types of cages for ball bearings, one of which is made of metal and the other of which is made of plastic. Since cost reduction and weight reduction can be achieved, plastic cages are now widely used.

The cage made of plastic for ball bearings is, for example, a plurality of comb-shaped segment cages made by plastic injection molding or the like, which are connected in the circumferential direction by fitting or the like.

The comb-shaped segment type cage is formed by plastic injection molding from the end face side of the segment part because one side end face is continuous and the open side end having the other claw part is discontinuous. In this case, when the material is injected into the mold, the flow direction and orientation of the injected material are not continuous between the one end surface and the other end surface, and molding shrinkage occurs.
That is, when the reinforcing fiber is not added, the resin material shrinks three-dimensionally, so that the opening side sags due to the shape difference between the opening side and the opposite side of the pocket. Further, when reinforcing fibers are added, the fibers are oriented so that the side opposite to the opening side becomes a resistance during molding shrinkage, so that the opening side relatively sags.

Since this molding shrinkage causes the comb-shaped claws to sag, the cage for ball bearings composed of the comb-shaped segment type cage causes problems such as braking of the bearing.

[0008] Such a comb-shaped claw portion deflection caused by plastic injection molding can be prevented to some extent by considering the material to be used, the mold, and the like. However, the materials that have been studied so far cannot completely prevent sagging, and for example, in the method shown in FIG. I couldn't do it. In the figure, 7 represents a spine.

The material injection port, which was conventionally provided in the center of the mold, is provided at the side end as shown in FIG. Although measures to prevent it have been investigated, a slight effect was seen, but it was not completely resolved.

[0010]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a cage for ball bearings, which comprises a comb-shaped segment type cage which does not have the sagging of the claws formed by plastic injection molding. It is a thing.

[0011]

In order to solve the above-mentioned problems, the present invention comprises a plurality of cage pieces divided in the circumferential direction, and each cage piece keeps balls at regular intervals in the circumferential direction. In the cage for segment type ball bearings having pockets, between each pocket of each cage piece, an imaginary line connecting the bottom of each pocket from the end face on the side opposite to the pocket opening side to the pocket opening side is provided. It is characterized in that a notched portion which is notched over is formed.

The ball bearing cage according to the present invention will be described below.
This will be described with reference to the drawings. FIG. 1 is a perspective view of an example of a comb-shaped segment type cage constituting the cage for ball bearings of the present invention. In the figure, 1 represents a pocket. 2 represents a notch. 3 represents the center of the pocket. 4 represents the pocket centerline. Reference numeral 5 represents a virtual line (pocket bottom line) that connects the bottoms of the pockets. The pocket center line 4 is a line connecting the pocket center portions 3.

In the cage for ball bearings of the present invention, between the pockets 1, the pocket bottom line 5 and the pocket center line 4 are crossed from the end face on the side opposite to the end face on the pocket 1 opening side toward the pocket 1 opening side. The cutout 2 is formed. Since the notch 2 is formed in the ball bearing cage, when the comb-shaped segment type cage is molded, the flow direction and orientation of the material injected into the mold are As shown in FIG. 2, the shape is not linearly continuous in the circumferential direction, and the shapes of both ends (the side opposite to the pocket opening side) are similar to each other, so that there is no difference in molding shrinkage at both ends. In the figure, the dotted line represents the flow direction and orientation of the material.

When the notch 2 is formed from the end surface on the side opposite to the end surface on the opening side of the pocket 1 toward the opening side of the pocket 1 without exceeding the pocket bottom line 5, the resin injected into the mold and the filling fiber. As shown in FIG. 3, the flow directions and orientations of the materials such as, for example, are linearly continuous in the circumferential direction between the pocket bottom line 5 and the end face of the pocket 1 on the closing side. And on the closed side, and the comb-shaped claw part is sagging. In the figure, the dotted line represents the flow direction and orientation of the material.

The ball bearing cage is preferably made of a material to which reinforcing fibers are added. The reinforcing fiber is not particularly limited, and examples thereof include glass fiber, carbon fiber, whisker fiber, ceramic fiber, metal fiber and the like which are generally filled for the purpose of improving the strength of plastic materials.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

A mold having the shape shown in FIG. 1 is prepared,
When a material injection port was provided at the end of the segment and the material was injected to perform plastic injection molding, the material continuously flowed between one end surface and the other end surface of the comb-shaped segment type cage. Since the plastic was not linearly oriented on one side end surface in the circumferential direction, and therefore, no difference in molding shrinkage between both ends occurred, so that the comb-shaped claw portion did not sag.

A plurality of the comb-shaped segment type retainers are connected in the circumferential direction by fitting as shown in FIG. 7 to form a ball bearing retainer.

When the conventional comb-shaped segment type cage shown in FIG. 4 was produced by plastic injection molding,
Since these had a large deformation, when a plurality of them were connected in the circumferential direction, the cage for the ball bearing was sagging.

When a cage for ball bearings with sagging was incorporated into the bearing, the outer diameter of the cage for ball bearings contacted the inner peripheral surface of the outer ring, and at the same time, the inner diameter of the cage for ball bearings changed to the outer peripheral surface of the inner ring. And the starting torque was tripled.

In order to prevent the above-mentioned sagging, 6,6 nylon without reinforcing fibers, 6,6 nylon with reinforcing fibers, etc. were used as materials, but the sagging did not stop. Further, plastic injection molding was performed using a mold having a plurality of material inlets at the side ends as shown in FIG. 6, but the runout was only reduced by 20 to 30%.

[0022]

Since the cage for ball bearings of the present invention has the above-mentioned structure, the flow direction and orientation of the material injected into the mold are not linearly continuous in the circumferential direction, and the comb-shaped pawl is provided. It is suitable for a cage for ball bearings that constitutes a large bearing such as a bearing for a swivel seat, because the portion does not sag.

[Brief description of drawings]

FIG. 1 is a perspective view of an example of a comb-shaped segment type cage constituting a cage for ball bearings of the present invention.

FIG. 2 is a view showing the flow direction and orientation of the material injected into the mold of the comb-shaped segment type cage constituting the cage for ball bearings of the present invention.

FIG. 3 is a view showing a flow direction and an orientation of a material injected into a mold of a conventional comb-shaped segment type cage.

FIG. 4 is a perspective view of an example of a conventional comb-shaped segment type cage.

FIG. 5 is a view showing an example of spine removal processing applied to a mold of a conventional comb-shaped segment type cage.

FIG. 6 is a view showing an example of a conventional comb-shaped segment type retainer in which a material inlet is provided at a side end portion.

FIG. 7 is a diagram showing a connection method by fitting in the embodiment.

[Explanation of symbols]

 1 pocket 2 notch 3 pocket center 4 pocket center line 5 pocket bottom line 6 inlet 7 spine

Claims (2)

[Claims] 1. A segment type ball bearing cage comprising a plurality of cage pieces divided in the circumferential direction, each cage piece having pockets for keeping the balls at regular intervals in the circumferential direction,
Between each pocket of each of the cage pieces, a notch cut out beyond an imaginary line connecting the bottom of each pocket from the end surface on the side opposite to the pocket opening side toward the pocket opening side is formed. Characteristic cage for ball bearings. 2. The cage for ball bearings according to claim 1, which is made of a material to which reinforcing fibers are added.