JPH0411092B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for manufacturing a synthetic resin bearing retainer using the so-called insert molding method, in which rotating members such as balls and rollers are inserted into a mold and then injection molded. Regarding.

[Conventional technology]

As a manufacturing method for a synthetic resin bearing retainer that is deformable and can be applied to various types of bearings, the manufacturing method proposed by the present applicant in Japanese Patent Application No. 60-252461 is based on a method for manufacturing synthetic resin bearing retainers that are deformable and can be applied to various types of bearings. After applying a mold release agent, the mold was inserted into a mold and a synthetic resin with a low shrinkage rate was injection molded.

[Problem that the invention seeks to solve]

However, in the case of the above-mentioned conventional method, the flow of the molten resin becomes poor due to the presence of the mold release agent or dirt, dust, etc. that easily mix with it, and the flow of the molten resin becomes difficult, for example, as shown in FIG. A weld line 11 occurs at the position where they collide with each other,
There was a problem in that the tensile strength of that part was about 1/2 that of other parts, which caused problems in use. still,
7 is a ball, 8B ₁ is an annular portion, and 8B ₂ is a ball-wrapping portion.

In addition, in order to maintain the gap between the molded product and the rotating member and to ensure smooth rotation of the rotating member, a synthetic resin material with a low shrinkage rate must be selected as described above, resulting in an increase in cost. .

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a method for manufacturing a synthetic resin bearing retainer, which increases the tensile strength of the retainer and reduces manufacturing costs.

[Means and actions for solving problems]

In the method of the present invention, a cleaned rotating member is inserted into a mold and molded without applying a mold release agent to the rotating member, thereby smoothing the flow of the molten synthetic resin and creating a weld line. I tried to avoid it.

In addition, the rotating member inserted into the mold is a dummy rotating member larger than the actually used rotating member, and by replacing the dummy rotating member with the actually used rotating member after molding, it can be adjusted to match the shrinkage rate of the synthetic resin material. By selecting the size of the rotating member for the dummy, it is possible to maintain a gap between the molded product and the rotating member to ensure smooth rotation of the rotating member, which also allows the use of synthetic resin materials with a high shrinkage rate. , the material cost is reduced.

〔Example〕

The present invention will be described in detail below based on the illustrated embodiments. In FIGS. 1 and 2, reference numeral 1 denotes a stationary die block, which has a sprue 1a. Reference numeral 2 designates one of the cavity halves, which includes a cavity 2a for molding a retainer annular portion, a plurality of cavities 2b for molding a retainer collar-shaped enveloping portion arranged at predetermined intervals, and a cavity corresponding to the cavity for molding the enclosing portion. It has a hemispherical recessed portion (ball accommodating portion) 2c arranged therein. 3 is a movable die block, and a stripper plate block 3 is configured to be separable.
It has a movable plate 3b, a runner 3c', and a core 3c integrated with the movable plate 3b.
4 is the other cavity half, which is formed by a stripper plate block 3a and a core 3c, and a cavity 4a for forming the retainer annular portion.
and a cavity 4b for molding a retainer collar-shaped enclosing part arranged at the same interval as the cavity 2b for molding the enclosing part.
and a hemispherical recessed portion (ball accommodating portion) 4c arranged corresponding to the cavity 4b for molding the enclosing portion. 5 is an ejector pin, and 6 is a runner protrusion pin. In this case, cavity half 2, 4
are fixed die block 1 and movable die block 3.
The pair of hemispherical recesses 2c and 4c align to define a complete spherical space when they are joined, that is, when the mold is clamped, and the cross section of the ejector pin 5 is circular or circular. It is rectangular.

Next, a molding method using the above mold will be explained.
FIG. 1A shows the so-called mold open state in which the mold is opened, and in this state, the hemispherical recesses 2c, 4c
A ball (such as a steel ball) 7 of a predetermined size and whose entire surface has been thoroughly cleaned with triclean, etc. is placed on either side (4c in the drawing) (see Fig. 1B), and in this state. The movable die block 3 is moved in the direction of the arrow to close the mold and heat the cavity halves 2 and 4. Subsequently, the synthetic resin 8 in a molten state is injected into the cavity halves 2 and 4 via the sprue 1a and the runner 3c' (see FIG. 1C). In this case, the synthetic resin 8 used is one that is flexible under normal conditions, has a small shrinkage rate, and has excellent abrasion resistance. After a predetermined period of time has elapsed, the movable die block 3 is separated from the stationary die block 1 to open the mold as shown in FIG.
The synthetic resin 8 solidified inside the die block a and the runner 3c' is separated from the fixed die block 1 together with the movable die block 3. Subsequently, when the stripper plate block 3a is pulled away from the movable plate 3b together with the ejector pin 5 and the runner ejection pin 6,
As shown in FIG. 1E, the synthetic resin portion 8A solidified within the sprue 1a and runner 3c' is separated from the synthetic resin portion 8B solidified within the cavity halves 2 and 4. Next, when the ejector pin 5 and the runner ejector pin 6 are respectively ejected in the direction of the arrows as shown in FIG. product). Thus, the ejector pin 5 and the runner ejection pin 6 are retracted,
By returning the stripper plate block 3a to the position where it joins with the movable plate 3b, the mold returns to the open state shown in FIG. 1A, completing one cycle of operation.

The molded product 8B taken out as described above is
As shown in FIG. 3, the annular part 8B ₁ is flexible and has excellent wear resistance, and the collar-shaped enclosing part 8B _{2 is slightly raised from both sides of the annular part 8B 1} , and the enclosing part 8B ₂ is rotatably encased in the enclosing part. A radial ball bearing retainer including the balls 7 is obtained. In this case, since balls whose entire surface has been thoroughly cleaned are used, the flow of the molten synthetic resin is improved, no weld lines occur, and the tensile strength of the retainer itself is increased.
In addition, since the mold is heated to a predetermined temperature before being filled with the synthetic resin, the flow of the molten synthetic resin is improved, resulting in even greater effects.

Moreover, as mentioned above, this product 8B is flexible as a whole, and the ball 7 does not accidentally separate from the annular portion _8B1 , so it can also be used as shown in FIG. 4. That is, in FIG. 4, G is a guide,
S is a slider in which a pair of products 8B are housed so that their annular parts _8B1 each draw an oval shape, and a plurality of balls 7 are in rolling contact with the inner wall surface of the guide G. In this case, the slider When S is pushed in the direction of the arrow, the ball 7 that contacts the inner wall surface of the guide G moves the entire annular portion _8B1 in the direction of the arrow while rotating, and can be moved along the guide G extremely smoothly and easily.

Further, according to the method of the present invention, as shown in FIG. 5, it is also possible to manufacture a roller bearing retainer using rollers 9 instead of balls 7.

Next, other embodiments of the present invention will be described.
This differs from the above embodiment in that a dummy rotating member such as a ball or roller that is larger than the actually used rotating member is inserted into the mold and injection molded, and then the dummy rotating member is replaced with the actually used rotating member. This is what I did. Therefore, if the size of the dummy rotating member is selected according to the shrinkage rate of the synthetic resin material, the gap between the molded product and the rotating member can be maintained and the rotating member can rotate smoothly. It is also possible to use synthetic resin materials with a high shrinkage rate, resulting in lower material costs and lower manufacturing costs.

In addition, there is a conventional method in which the rotating member accommodating portion is filled with a part of the mold instead of the dummy rotating member, and in this case, the direction in which the part of the mold is removed is determined by the parting direction of the mold. However, in the case of the method of the present invention, the dummy rotating member can be pulled out in the most effective direction regardless of the parting direction of the mold. Since it is possible to select a direction that does not require excessive force, it is possible to obtain a rotating member accommodating portion with a uniform inner diameter and high precision. Furthermore, in this conventional method, since the thickness of the part of the mold and the rotating member accommodating portion are usually the same, burrs are generated in the radial direction of the rotating member accommodating portion. Although the frictional resistance of the rotating member increases due to the contact, in the case of the method of the present invention, burrs are generated along the circumferential surface of the dummy rotating member, so the frictional resistance of the rotating member does not increase.

In addition, especially when the rotating member is a roller, although the outer diameter of the roller can be finished with high accuracy, the dimensional tolerance in the longitudinal direction is large and the variation width is larger than in the radial direction. However, according to the method of the present invention, the dummy If a roller larger than the maximum dimension of the bearing roller is used as the roller, there is an advantage that dimensional variations can be absorbed.

〔Effect of the invention〕

As described above, according to the method for manufacturing a synthetic resin bearing retainer according to the present invention, the tensile strength of the retainer can be increased and the manufacturing cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts showing the manufacturing process of a ball bearing retainer according to an embodiment of the present invention, FIG. 2 is a plan view taken along the - line of FIG. FIG. 4A is a partially cutaway plan view showing a special usage example of the ball bearing retainer manufactured by the method of the present invention, and FIG. 4B is a perspective view of the ball bearing retainer manufactured by the method of the present invention. FIG. 5 is a perspective view of a roller bearing retainer manufactured by the method of the present invention, and FIG. 6 is a front view of main parts of a ball bearing retainer manufactured by the conventional method. 1... Fixed side die block, 2, 4... Cavity half, 3... Movable side die block, 5... Ejector pin, 6... Runner ejector pin, 7... Ball,
8B...synthetic resin part (molded article, product), 8B ₁ ...annular part, 8B ₂ ...wrapping part, 9...roller, 10...gate, 11...weld line.

Claims (1)

[Scope of Claims] 1. Insert molding using a mold having a pair of cavity halves, which bisect a cavity consisting of a continuous cavity for molding a retainer annular portion, a cavity for molding a retainer rotating member enveloping portion, and a cavity for accommodating a rotary member. In the method for manufacturing a synthetic resin bearing retainer according to the method, with the pair of cavity halves opened, placing a cleaned rotating member in a rotating member housing cavity of one of the cavity halves without applying a mold release material; A method for manufacturing a synthetic resin bearing retainer using an insert molding method, comprising the steps of closing and heating the pair of cavity halves. 2 A cavity for molding the retainer annular part, a cavity for molding the retainer rotating member enclosing part for enclosing a dummy rotating member that is larger than the actually used rotating member whose dimensions are controlled to be appropriate in terms of synthetic resin molding technology, and a cavity for accommodating the rotating member. A step of using a mold having a pair of cavity halves in which a continuous cavity is divided into two, and placing the dummy rotating member in a rotating member housing cavity of one of the cavity halves with the pair of cavities open. An insert molding method comprising the steps of: closing and heating the pair of cavity halves; and replacing the dummy rotating member enclosed in the molded product obtained by the ejection operation with an actually used rotating member. A method of manufacturing a synthetic resin bearing retainer.