JP2908862B2 - Forming method of annular molded body - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for forming an annular molded body which is molded by inserting a metal ring such as an oil seal.

(Prior Art) As an example of a conventional annular molded body of this type, for example, an oil seal as shown in FIGS. 6 and 7 will be described. An oil seal 100 includes a metal ring 101 and a metal ring 101. And a rubber-like elastic body 102 integrally baked.

To form the oil seal 100, as shown in FIG. 8, a metal ring 101 is placed at a predetermined position of a lower mold 103 which has been opened, and a rubber material 104 as a molding material is placed thereon. A projection 106 provided on the upper mold 105 by clamping the mold and the lower mold 103
By pressing the upper end surface of the metal ring 101 at a plurality of locations along the circumferential direction at predetermined intervals, the metal ring 101 is positioned in the width direction.

Thereafter, the upper mold 105 and the lower mold 103 are clamped and heated under pressure,
The metal ring 101 and the rubber material 104 are filled with a fluidized rubber material in a cavity 106 formed between the upper mold 105 and the lower mold 103.
And were integrally molded.

Due to the projections 106 of the upper die 105, a plurality of concave grooves 107 are formed on the end face of the oil seal 100 to be formed, as shown in FIGS.

(Problems to be Solved by the Invention) However, in the case of the above-described prior art, the final point of inflow of the rubber material 104 at the time of molding is concentrated on the portion of the concave groove 107, and a joint-shaped rubber chipped portion is generated. There is.

9 and 10, when the flow state of the molding material 104 in the cavity 110 at the time of molding is observed, the metal material flows into the spaces 108, 109 on the outer diameter side and the inner diameter side of the metal ring 101 as a boundary. However, it is considered that the terminal ends return to the upper end surface of the metal ring 101.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to make the flow of molding material smooth at a holding portion of an upper end surface of a metal ring held by a projection of an upper die. Accordingly, it is an object of the present invention to provide a method for forming an annular molded body that can prevent molding defects such as chipped rubber as much as possible.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a metal ring is placed at a predetermined position of a lower mold that has been opened, and a molding material is placed thereon. The upper mold is clamped to the lower mold to press the upper end surface of the metal ring at a plurality of locations at predetermined intervals along the circumferential direction and formed between the upper mold and the lower mold. In a method of forming an annular molded body in which a molding material fluidized in a cavity is filled and a metal ring and a molding material are integrally formed, a projection provided on the upper mold is provided on an inner side with a metal ring of the cavity as a boundary. A passage communicating the first space with the second space on the outer diameter side is formed, and the fluidized material being formed is circulated through the passage.

(Operation) In the method for molding an annular molded body having the above-described configuration, the fluidized molding material flows through the passage provided in the projection that presses the metal ring during molding, so that the circulation area increases.

(Example) Hereinafter, the present invention will be described based on an illustrated example. In FIGS. 1 and 2 showing an annular molded body to which the molding method of the present invention is applied, reference numeral 1 denotes an oil seal as the annular molded body. The oil seal 1 is a so-called outer peripheral rubber type oil seal with a spring, and includes a metal ring 2 and a rubber-like elastic body 3 integrally vulcanized and bonded to the metal ring 2.

The oil seal 1 is an annular member opened in a U-shaped cross section,
One leg is reinforced by the metal ring 2, and the other leg is a seal lip 4 composed of only the rubber-like elastic body 3.

The metal ring 2 has an L-shaped cross section, and includes a cylindrical outer tube portion 5 and an inward flange 6 extending radially inward from one end of the outer tube portion 5.

The rubber-like elastic body 3 covers the metal ring 2 and is integrally baked.
Of the metal ring 2 and an end face covering portion 7 for covering the end face of the inward flange 6 of the metal ring 2.

The end face covering portion 7 is provided with a plurality of grooves 8 at predetermined intervals along the circumferential direction. At the center of the groove 8, the inner side and the outer side are connected by a concave. A rubber flow partition 9 that bisects the groove 8 is provided.

3 to 5 show a molding method for molding the oil seal.

The molding die 10 is generally composed of an upper die 11 and a lower die 12, and the upper die 11 has a first upper die 13 arranged at the center thereof,
An annular second ring whose inner periphery closely fits the outer periphery of the first upper mold 13
The upper mold 14 is provided.

On the other hand, the lower mold 12 has a first lower mold 15 at the center and a first lower mold 15.
And a third lower die 17 attached to the outer periphery of the second lower die 16.

The mating surface between the upper mold 11 and the lower mold 12 is the second upper mold 14
The oil seal 1 is constituted by a lower surface and a joining surface of the third lower mold 17 and is disposed between the upper mold 11 and the lower mold 12 in a clamped state.
A cavity 18 for molding the rubber-like elastic body 3 is formed. The metal ring 2 of the oil seal 1 is inserted into the cavity 18, and the metal ring 2 is attached to the end face of the annular projection 19 provided on the second lower mold 16 of the lower mold 12. Is placed. The outer cylindrical portion 5 of the metal ring 3 is in contact with the outer peripheral surface of the protrusion 9.

On the other hand, the outer peripheral edge of the first upper die 13 of the upper die 11 is provided corresponding to the end face of the protruding portion 19 of the second lower die 16.
In FIG. 13, the metal ring 2 is pressed between the protrusion 19 and the metal ring 2.
A projection 20 for forming a width direction presser and a flow groove for a molding material such as rubber is provided. A plurality of the projections 20 are arranged at predetermined intervals along the circumferential direction, and the projections 20 constitute the concave grooves 8 of the end face covering portion 7 of the oil seal 1.

The projection 20 is divided into two parts as shown in FIG. 3 (b), and the cavity 18 is formed at the center of the projection 20 with the first space 22 on the inner diameter side and the outer diameter side with the metal ring 2 as a boundary. A rubber flow groove 21 is provided which forms a passage communicating with the second space 23. The rubber flow groove 21 forms the rubber flow partition 9 of the oil seal 1.

To form the oil seal, the upper mold 11 and the lower mold 12 are opened, and the metal ring 2 is attached to the projection 19 of the second lower mold 16 of the lower mold 11.
And the rubber material 21 as a molding material is placed. Then clamp the rubber material 21
Is pressurized and heated to fluidize the rubber material 21 and the cavity 18
The rubber-like elastic body 3 of the oil seal 1 is formed by filling the inside.

During the molding, the inward flange 6 of the metal ring 2 is pressed by the projection 20 of the first upper mold 13, and the molding material flows through the gap between the projection 20 and the metal ring 2. In particular, at the projection 20 portion which is the final flow point of the rubber material 21, the rubber material 21 flows through the rubber flow groove 21 provided on the projection 20 portion, the flow area becomes large, and molding defects such as chipping of rubber are prevented. .

In the above embodiment, an oil seal is described as an example of the annular molded body. However, the present invention is not limited to the oil seal, and is widely applied to a method of manufacturing an annular molded body in which a metal ring and a rubber-like elastic body are integrally baked. can do.

(Effects of the Invention) The present invention has the above-described configuration and operation, and since the metal ring presser projection provided on the upper die is provided with a passage, the flow area of the molding material flowing through this passage is increased. As a result, molding defects such as breakage of the joint at the final point as in the related art are unlikely to occur, and the quality of molded products can be improved.

[Brief description of the drawings]

FIGS. 1 and 2 show an oil seal formed by the method of forming an annular molded body according to the present invention. FIG. 1 is a bottom view of the oil seal, and FIG. FIG. 3 (a) is a half sectional view of an oil seal forming die, FIG. 3 (b) is a side view of the projection in FIG. 3 (a), and FIG.
FIGS. 5 and 5 are semi-longitudinal sectional views of a molding die showing respective molding steps, FIGS. 6 and 7 show an oil seal as a conventional annular molded body, and FIG. FIG. 7 is a bottom view, FIG. 8 is a sectional view of a main part of a molding die for molding a conventional oil seal, and FIG. 9 shows a flow state of a molding material when the molding die of FIG. FIG. 10 is a sectional view schematically showing a flow state of the molding material of FIG. DESCRIPTION OF SYMBOLS 1 ... Oil seal (annular molded body) 2 ... Metal ring 3 ... Rubber-like elastic body 4 ... Seal lip 5 ... Outer cylinder 6 ... Inward flange 7 Part 8: groove, 9: rubber sink partition 10: molding die, 11: upper die 12, lower die, 13: first upper die 14: second upper die, 15: first Lower die 16: Second lower die, 17: Third lower die 18: Cavity, 19: Annular protrusion 20: Projection, 21: Rubber flow groove (passage)

Claims (1)

(57) [Claims] 1. A metal ring is placed at a predetermined position of a lower mold that has been opened and a molding material is placed thereon. The upper mold and the lower mold are clamped by a projection provided on the upper mold. The upper end face is pressed at a plurality of locations at predetermined intervals along the circumferential direction, and the cavity formed between the upper mold and the lower mold is filled with the fluidized molding material to form a metal ring and the molding material. In the method of forming an annular molded body to be integrally molded, a passage communicating between a first space on an inner diameter side and a second space on an outer diameter side is formed in a projection provided on the upper mold with a metal ring of the cavity as a boundary. And flowing the fluidized material being formed through the passage.