JPH11108063A - Synthetic resin holder for rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve strength by forming a flow passage for a synthetic resin on an inner or outer diameter side of a holder correspondingly to a pocket of the holder, without interfering with the pocket at the time of injection molding, injection-molding the holder, and then removing the flow passage for the synthetic resin. SOLUTION: Resin 2 is charged from a gate 4 formed on a disc 3. The resin 2 charged from the gate 4 is flowed through a flow passage 6 formed on an inner diameter side of a pocket 5. Due to the presence of the flow passage 6, the resin 2 is smoothly charged to the opposite side to the gate in each pocket. Weld is generated partially in the pocket, so that strength is improved. The pocket 5 can be formed by arranging a slide core type die. A disc gate method is selected as a charging method. In such a case, flow of the resin is terminated at a disc end. Clear weld is hardly generated, for easily securing improvement of strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin cage for a rolling bearing for supporting a rotating body (for example, a spindle for a machine tool) which is operated at a relatively high speed.

[0002]

2. Description of the Related Art A bearing for a spindle of a machine tool spindle is required to have good characteristics such as vibration and sound in order to improve machining accuracy. In recent years, there has been a demand for high-speed rotation (that can be used stably at a high rotation speed for a long time) in order to further improve processing efficiency. Conventionally, in order to satisfy such characteristics, a synthetic resin cage which is lightweight and excellent in flexibility has been often used. The synthetic resin cage is formed by injection molding. In addition, machine tool bearings are often operated with a very small amount of grease or lubricating oil used in order to minimize heat generation during operation. This is because by minimizing the necessary amount of the lubricant, the stirring resistance of the lubricant such as grease or lubricating oil and the accompanying heat generation are suppressed.

However, there are various problems in pursuing higher speed. For example, when a synthetic resin cage, which is used as a standard for machine tool bearings, is used, the centrifugal force acting on the cage increases, causing the cage to come into strong contact with the balls and races, resulting in the strength of the cage. May have limitations. Conventional synthetic resin cages are manufactured by the axial or radial sliding type injection molding method, and the resin inlet or gate is located at one or several places, and is a joint part of the resin flow, which is stronger than other parts. Where the temperature tends to be low, that is, a weld portion occurs. FIG. 11 shows the locations where welds occur in the case of the one-point gate method. The weld includes a weld 50 and a gate 51 for each pocket, and a weld 52 at a target position. Breakage of the cage often occurs when the position where the weld is formed overlaps the stress concentration position of the cage. Furthermore, synthetic resin cages obtained by injection molding with a single point or multipoint gate generally tend to have poor dimensional accuracy, especially roundness, and this tendency is more remarkable as the size is larger. Not suitable for the required use.

In order to solve this problem, a copper alloy retainer having a higher strength than a synthetic resin is sometimes used, but the copper alloy retainer is used with a very small amount of grease or lubricating oil. The cage will wear easily,
Abrasion powder of the cage may cause minute scratches on the balls and races, and when the operating conditions are severe, there is a possibility that the improvement in seizure resistance and wear resistance may be limited. On the other hand, in the case of the synthetic resin cage, abrasion hardly occurs, and even when abrasion occurs, the abrasion powder rarely causes damage to the balls and the race. However, when fabricating a synthetic resin cage from a raw material, strength and processing accuracy can be secured, but processing is more difficult because glass fiber and carbon fiber are added to the synthetic resin to ensure high-speed performance. Was inevitable.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conditions of use of a rolling bearing for a machine tool, and solves the problems inherent in a synthetic resin cage used for a rolling bearing for a machine tool. The purpose is to do.

[0006]

Means for Solving the Problems Injection molding of synthetic resin,
Forming a flow path for synthetic resin on the inner diameter side or outer diameter side of the pocket without penetrating the pocket part of the cage at the time of molding,
After molding the cage, the flow path for the synthetic resin is deleted. In the method of manufacturing a cage made of synthetic resin for rolling bearings, injection molding of synthetic resin by single-point gate method, multi-point gate method, or disk gate method is applicable to the pocket part without penetrating the pocket part of the cage at the time of molding. The flow path for the synthetic resin is formed on the inner diameter side or the outer diameter side of the cage to be formed, and after the injection molding of the cage, the flow path for the synthetic resin is deleted.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a mold 1 for forming the retainer of the first embodiment, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. In this embodiment, resin is injected by a disk gate method. Resin 2 is disk 3
Is injected from the injection port provided at the gate 4, that is, the gate 4.
In FIG. 1, a flow path 6 is provided on the inner diameter side of the pocket portion 5, and the resin 2 injected from the gate 4 passes through the flow path 6. Due to the presence of the flow path 6, the resin is smoothly injected to the opposite side of the gate for each pocket,
Since the weld is generated only in a part of the pocket, the strength is improved. The pocket portion 5 can be formed by using a slide core system for the mold. Although the injection method is a disk gate method in this embodiment,
In this case, since the final portion of the resin flow is the disk end, a clear weld portion is not possible, which is extremely advantageous in the present invention, and it is easy to secure an improvement in strength. But,
A one-point gate system or a multi-point gate system may be used. As the material of the retainer, a thermoplastic resin that can be injection-molded is used. As the thermoplastic resin, polyamide 66, polyamide 46, polyphenylene sulfide, thermoplastic polyimide, or the like can be used as a base material. Further, in order to improve the strength of the retainer, it is preferable to add about 10 to 40% by weight of glass fiber and about 10 to 30% by weight of carbon fiber and aramid fiber. Further, carbon fibers and aramid fibers are more preferable to satisfy the specification of high-speed rotation, but glass fibers can be selected according to the specification. In addition, when the amount of the aramid fiber of the carbon fiber is 10 to 30% by weight, if it is 10% or less, the strength is not sufficiently secured, and if it is 30% or more, the moldability is deteriorated and the appearance is deteriorated. Also more preferably 20 to
If it is 30%, both the strength and the moldability will be good. In the case of glass fiber, the content is desirably 10 to 40%, for the same reason as described above. In addition, in the case of using glass fibers, the channel portion can be easily cut off and the cost can be reduced.
The cage 10 thus formed does not have the pocket portion 5 penetrated as shown in FIG. The cage 10 as shown in FIG. 4 is formed by penetrating the pocket portion 5 of the cage. In this case, if a method of penetrating the pocket portion by shaving off the inner diameter portion is used, the workability is good and the cost can be reduced. By shaving off only the flow path in this way, a highly accurate and high-strength cage can be obtained at a lower cost and faster than the whole shaving process.

Next, a second embodiment of the present invention will be described. FIG. 5 shows a mold 2 for forming the cage of the present embodiment.
6 is a cross-sectional view taken along a line BB ′ in FIG. 5. In this embodiment, resin is injected by a disk gate method. The resin 22 is injected from a gate 24 provided on the disk 23. In FIG. 5, a flow path 26 is provided on the outer diameter side of the pocket portion 25,
The resin 22 injected from the gate 24 passes through the flow path 26. Due to the presence of the flow path 26, the resin is smoothly injected to the opposite side of the gate for each pocket, so that welding is unlikely to occur. The injection method is a disk gate method in this embodiment, but may be a one-point gate method or a multi-point gate method.

As the material of the retainer, a thermoplastic resin that can be injection-molded is used. Polyamide 6 as the thermoplastic resin
6, polyamide 46, polyphenylene sulfide, thermoplastic polyimide, or the like can be used as a base material. Further, in order to improve the strength of the retainer, 10 to 40% by weight of glass fiber and 10 to 3% of carbon fiber and aramid fiber are used.
It is preferable to add about 0% by weight. The cage thus formed does not have the pocket portion 25 penetrated as shown in FIG. The cage 30 as shown in FIG. 8 is formed by penetrating the pocket 25 of the cage 30. The cage 40 manufactured according to the present invention has a ball bearing 41 as shown in FIG.
Can be used for Further, the cage 40 manufactured according to the present invention can be used for a roller bearing 42 as shown in FIG.

Next, the results of experiments performed on the cage manufactured according to the present invention will be described.

[Table 1] Further, the results of experiments performed on a cage manufactured by a conventional method are shown.

[Table 2] Comparing Tables 1 and 2, it can be seen that the cage according to the present embodiment is superior in both strength and roundness to those according to the conventional method, and that the present embodiment has higher durability.

[0011]

According to the manufacturing method of the present invention, the occurrence of welds in the annular portion can be suppressed, so that the number of parts having reduced strength is reduced. In addition, since the number of weld generation portions is reduced, the strength of the annular portion is improved. Furthermore, since the deformation of the shape is suppressed, it is possible to improve the accuracy of the roundness and the like as compared with a synthetic resin cage manufactured by a conventional injection molding method. The synthetic resin cage obtained according to the present invention has an improved strength of the retainer ring portion and high accuracy. Therefore, stable high-speed operation is possible with the rolling bearing using this cage.

[Brief description of the drawings]

FIG. 1 is a diagram showing a manufacturing example of a cage according to a first embodiment.

FIG. 2 is a sectional view taken along the line A-A 'of FIG.

FIG. 3 is a view showing a molded state of the cage according to the first embodiment.

FIG. 4 is a view showing a completed processing state of the cage according to the present invention.

FIG. 5 is a diagram showing a manufacturing example of the cage according to the second embodiment.

FIG. 6 is a cross-sectional view taken along the line B-B 'of FIG.

FIG. 7 is a view showing a molded state of a cage according to a second embodiment.

FIG. 8 is a view showing a completed processing state of the cage according to the second embodiment.

FIG. 9 shows a ball bearing according to the invention.

FIG. 10 is a view showing a roller bearing according to the present invention.

FIG. 11 is a view showing a conventional cage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 2 Resin 3 Disk 4 Gate 5 Pocket part 6 Flow path 10 Cage

Claims (1)

[Claims] 1. A synthetic resin cage for a rolling bearing, wherein a synthetic resin is injection-molded, and an inner diameter or an outer diameter of a cage corresponding to the pocket is formed without penetrating a pocket of the cage at the time of molding. A synthetic resin cage for rolling bearings, characterized in that a flow path for synthetic resin is formed on the side, and the flow path for synthetic resin is deleted after injection molding of the cage.