JPH03180313A - Manufacture of synthetic resin bearing cage - Google Patents

Abstract

PURPOSE:To generate a weldline at a portion having large wall thickness and, at the same time, prevent the generation of asymmetric shape from occurring by a method wherein synthetic resin material is poured under the condition that the magnitude of an approach angles is set so as to generate a weldlike at a portion, which is off the bottom of a pocket. CONSTITUTION:A cage 1 consists of a plurality of pockets 2, which are provided at fixed space intervals on one edge face of an annular member, and pillars 3, each of which is left between the pockets 2. A gate 5 has a fixed approach angle, which is determined by a first approach angle alpha1 and a second approach angle alpha2. When the first approach angle alpha1 is set to be a fixed angle exceeding 0 deg., the difference between the speeds of bisected resin flows is developed in proportion to the magnitude of the first approach angle alpha1. As a result, the difference develops in the times of the flows, which are bisected after the pouring through the gate 5, for reaching the confluence of the flows (weldline). Since said time difference can be changed by properly changing the magnitude of the first approach angle alpha1, the portion of the weldline 6 can be set so as to generate at a portion, which has large wall thickness, or at a pillar 3 and not to generate at a portion, which has small wall thickness, such as the bottom of the pocket 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of manufacturing a cage for holding rolling elements of a bearing, and in particular to a method for manufacturing a cage made of synthetic resin for a rolling bearing that holds an odd number of rolling elements. This relates to a manufacturing method.

[Conventional technology]

Synthetic resin cages for bearings are generally manufactured by injection molding. In this case, the molten synthetic resin material is injected into the annular cage cavity through a single gate formed in the mold.

The injected material separates into three directions at the exit of the gate, each travels half a circle inside the cavity, and joins and joins at a position 180 degrees apart from the gate position.

This junction is called the weld line.

The retainer is composed of a pocket portion that holds the rolling elements and a pillar portion that connects the pocket portions to each other, but the wall thickness of the pocket portion, particularly the bottom portion thereof, is smaller than the pillar portion. For this reason, the exit of the gate has a sufficient wall thickness and is therefore provided so as to face the strong column.

However, when the number of pocket portions is odd, the pocket portion exists on the opposite side to the position of the pillar portion provided with the gate, that is, at a position extending 180° from the gate. For this reason, when the synthetic resin material separated into three sides at the gate exit moves at the same speed, they merge at the pocket on the opposite side, creating a weld line at the bottom of the pocket, which is the thinnest part of the pocket.
There is a problem of reducing the strength of that part.

In order to avoid a weld line from forming at the bottom of the pocket, the gate is placed at a position slightly offset from the column to the bottom of the pocket. There is a known method for making the
(See Publication No. 23).

In addition, in order to create a difference in the time it takes for the three-way flow of synthetic resin material to reach the weld line, a method has also been proposed in which a reservoir (well) of synthetic resin material is provided in the middle of one flow. (Refer to Utility Model Application Publication No. 59-88574).

[Problem to be solved by the invention]

However, with the method of shifting the gate position, both the gate and weld line will be located between the thickest part and the thinnest part, so the weld line position will be shifted in the direction of increasing strength. However, the problem is that the gate position is moved in the direction of weakening the strength.

Further, in the case where a weld is provided in the middle of the material flow, there is a problem that an unnecessary protrusion remains in a part of the completed cage, resulting in an asymmetric shape in terms of shape and weight.

Therefore, in the present invention, when the number of pocket portions is an odd number, even if the gate position is set at the thickest portion, a weld line will be formed in the thickest portion, and the shape will be asymmetrical. The present invention aims to provide a method for manufacturing a synthetic resin cage without any blemishes.

[Means to solve the problem]

In order to solve the above problems, the method of the present invention provides a gate with an entrance angle, sets the entrance angle to a size where the weld line is outside the bottom of the pocket, and uses a synthetic resin material. It was designed to be injected.

[Operation 1] The synthetic resin material injected from the gate at a certain angle of approach is divided into three directions at the gate exit and flows inside the cavity. In this case, the flow along the direction of the approach angle has a larger velocity component than the flow in the opposite direction, resulting in a difference in flow velocity. For this reason, by appropriately setting the angle of approach, they merge at a portion off the bottom of the pocket on the opposite side to the gate, and a weld line is formed at the merge point.

〔Example〕

FIG. 1 shows a cage 1 according to a first embodiment, and this cage 1 has a plurality of pockets 2 provided at regular intervals on one end surface of an annular member, and a pillar section between the pockets 2. This leaves 3. A pair of opposing claws 4 are provided at both ends of the pocket portion 2.
The pocket 2 and the inner surfaces of both claws 4 form a partially spherical surface.

FIGS. 2 and 3 show the positional relationship between the cage 1 which is bottom-shaped in the mold cavity and the gate 5 for injecting resin material into the cavity. is provided so as to face the inside of one column 3.

The gate 5 has a constant approach angle, and this approach angle is defined by a first approach angle α1 shown in FIG. 2 and a second approach angle α2 shown in FIG.

The first approach angle α is
When the diameter line drawn from the tip of the gate 5 on the plane coincides with the Y-axis, the second approach angle α2, which refers to the inclination angle α1 with respect to the Y-axis, is the inclination of the gate 5 with respect to the Z-axis on the XZ plane. It refers to the angle α2.

In the case of the first embodiment, the above-mentioned first approach angle α1 is appropriately determined in an angle range exceeding 0° and not exceeding ±90°.

In short, inside the cavity of cage 1, 0'
Any angle can be taken on either side of the Y-axis except for (on the Y-axis).

The second approach angle α is appropriately determined within the range of 0° or more and ±90°.

The second embodiment shown in FIGS. 4 and 5 has the following features, except that the gate 5 is located inside the cage cavity.
The rest is the same as in the first embodiment.

In the case of the third embodiment shown in FIGS. 6 to 8, the cage 1
They are different in form, in that both end surfaces of the pocket portion 2 are closed, and the pocket portion 2 is open on both the inside and outside of the retainer 1.

In this case, the gate 5 can be provided inside or outside the cage cavity as in the first and second embodiments described above, but here, as another method, the gate 5 can be provided on one end surface of the cage 1. An example is shown in which a gate 5 is provided so as to be attached to one pillar 3.

In this case, the first approach angle α is arbitrarily determined within the range of ±180° exceeding Oo. The second approach angle α2 is the first
Depending on the magnitude of the approach angle α, it is arbitrarily determined within a range of more than 0″ and less than 180°.

As mentioned above, in any embodiment, the first approach angle α1
Any angle can be taken except when it is perpendicular (α,=O') to a line l parallel to the X-axis drawn at the exit of the gate 5. The magnitude of the second approach angle α2 is not particularly limited in this invention and is set around 0, usually O@.

In each of the above embodiments, the first approach angle α is O.

If the angle is set to a certain value exceeding the first approach angle α, a difference will occur in the speed of the resin flow divided into three directions depending on the magnitude of the first approach angle α. That is, the flow along the direction of the approach angle has a larger velocity component than the flow in the opposite direction. Therefore, gate 5
This results in a difference in the time it takes for the flows injected from and split into three directions to reach the confluence (weld line 6).

This time difference can be changed by appropriately changing the magnitude of the first approach angle α1, so the position of the weld line 6 should be adjusted to avoid areas with small wall thickness, such as the bottom of pocket portion 2, and to It can be set so that it grows on a large part of the area or on the pillar part 3.

〔Effect of the invention〕

As described above, according to the present invention, the position of the gate is not shifted to one side, it is provided so as to be compared to the cavity corresponding to the pillar part, and the shape of the cage is not made asymmetrical.
By appropriately setting the entrance angle of the gate, the weld line can be formed in a thicker area, avoiding the bottom of the pocket.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a cage whose bottom shape has been shaped by the method of the first embodiment, FIG. 2 is a plan view showing the positional relationship between the cage and the gate, and FIG. 3 is a front view of FIG. Fig. 4 is a plan view showing the positional relationship between the retainer and the gate of the second embodiment, Fig. 5 is a sectional view taken along the FIG. 7 is a plan view showing the positional relationship between the cage and the gate, and FIG. 8 is a front view of FIG. 7. 1...Retainer, 3...Column section, 5...Gate, 2...Pocket section, 4...Claw, 6. ...weld line.

Claims (1)

[Claims] (1) In a method of manufacturing a synthetic resin cage for bearings by placing a gate facing the cavity of the cage formed in the mold and injecting synthetic resin material through the gate, the approach angle is adjusted to the gate as described above. Manufacturing a synthetic resin cage for a bearing, characterized in that the synthetic resin material is injected by setting the approach angle to a size where the weld line is located outside the pocket bottom of the cage. Method.