JP2000043062A - Production of vibration-proof bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of rubber burr on the outer peripheral surface not covered with a rubber material of the end part of the inner cylinder of a vibration-proof bush. SOLUTION: In a vibration-proof bush producing method wherein an inner cylinder 3 is set to the interior of a mold and a rubber material is injected in the almost cylindrical cavity formed between the outer peripheral surface of the inner cylinder 3 and the mold, a small diameter part 5b of which the outer peripheral surface is not covered with a rubber material and a large diameter part 6 of which the outer peripheral surface is covered with the rubber material are formed to the inner cylinder 3 and, in such a state that the edge 15 holding the small diameter part 5b and provided to the mold 10 forming a part of the cavity is brought into contact with the entire periphery of the stepped part of the small diameter part 5b and the large diameter part 6 under pressure, the rubber material is injected into the cavity. By this constitution, the generation of rubber burr on the outer peripheral surface of the small diameter part 5b can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an anti-vibration bush.

[0002]

2. Description of the Related Art As a method of manufacturing a vibration-isolating bush, there is provided an inner cylinder made of metal and a rubber material fixed so as to cover the outer peripheral surface of the inner cylinder. The vibration bush sets the inner cylinder in a mold, and injects a rubber material into a substantially cylindrical cavity formed between the outer peripheral surface of the inner cylinder and the mold to form the inner cylinder and the rubber material. Is generally formed integrally.

For example, in a method of manufacturing a vibration-isolating bush described in Japanese Utility Model Publication No. 5-28020, as shown in FIG. 7, the upper end surface of an inner cylinder 30 set in a molding die is pressed by a separation die 31. The lower surface of the inner cylinder 30 is brought into contact with the surface 32 and the lower end surface of the inner cylinder 30 is urged by a spring member 33.
By pressing the upper surface of the inner cylinder 30 against the upper and lower end surfaces of the inner cylinder 30, the pressing surface 32 and the upper surface of the inner cylinder support portion 34 are strongly pressed by the spring member 33 when the molds are matched, Cavity 3 with no gap
5 is filled with a rubber material.

[0004]

In such a method of manufacturing a vibration-isolating bush, it is possible to reliably prevent rubber burrs from being formed on both end faces of the inner cylinder 30, but as shown in FIG. In order to prevent rubber burrs occurring on the outer peripheral surface 36 that is not covered with the rubber material at the end of the cylinder 30,
It is necessary to fit the outer diameter of the end of the inner cylinder 30 with the circular dimension of the separation mold 31 that contacts the end of the inner cylinder.

However, in this case, if the outer diameter of the end of the inner cylinder 30 has a large variation, it cannot be taken out at the time of demolding. Therefore, it is necessary to improve the dimensional accuracy by polishing the end of the inner cylinder 30 or the like. However, there is a problem that the cost increases.

[0006]

According to a first aspect of the present invention, an inner cylinder is set in a molding die comprising a plurality of dies, and a substantially cylindrical member formed between the outer peripheral surface of the inner cylinder and the molding die. In a method of manufacturing a vibration-isolating bush, in which a rubber material is injected into a cavity and integrally molded with the inner cylinder and the rubber material, a large-diameter portion facing the cavity and a small-diameter portion continuous with the large-diameter portion are provided. , Formed in the inner cylinder, holding the small-diameter portion, and providing an edge in a mold that forms a part of the mold surface of the cavity, wherein the edge is a stepped portion between the small-diameter portion and the large-diameter portion. The rubber material is injected into the cavity while being pressed against the entire circumference. When the edge is pressed against the entire circumference of the step portion between the small diameter portion and the large diameter portion, the cavity end is completely closed. Accordingly, it is possible to prevent the occurrence of rubber burrs on the outer peripheral surface of the small diameter portion protruding from the cavity end.

According to a second aspect of the present invention, in the first aspect of the present invention, the mold provided with the edge can be opened and closed in the axial direction of the inner cylinder.

According to a third aspect of the present invention, in the first or second aspect of the invention, a step portion between the small diameter portion and the large diameter portion of the inner cylinder forms a tapered surface, and the edge plastically deforms the tapered surface. The feature is that it is in a bite state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a method of manufacturing an anti-vibration bush 1 according to the present invention.
A rubber material is injected into a substantially cylindrical cavity 4 formed between the outer peripheral surface of the metal inner cylinder 3 set in the molding die 2 and the inside.

The inner cylinder 3 has a small diameter portion 5 and a large diameter portion 6. That is, both ends of the inner cylinder 3 are small-diameter portions 5, and a central portion of the inner cylinder 3 sandwiched between these small-diameter portions 5 is a large-diameter portion 6. The inner cylinder 3 has a through hole 7 having a constant inner diameter over the entire length in the axial direction. The outer peripheral surface of the large-diameter portion 6 and the outer peripheral surface of the small-diameter portion 5a located in FIG. 1 are covered with an elastic portion 8 made of a rubber material, and the small-diameter portion 5b located in FIG. The outer peripheral surface is not covered with the rubber material.

The step between the small-diameter portions 5a and 5b and the large-diameter portion 6 is continuous with a tapered surface 9 as shown in FIG.

The lower mold 10 holds the lower end of the inner cylinder 3 and can open and close in the axial direction of the inner cylinder 3.
A middle mold 11, which has a cavity 4 between itself and the outer peripheral surface of the inner cylinder 3 and is capable of opening and closing in the radial direction of the inner cylinder 3,
11 and an upper die 12 that holds the upper end of the inner cylinder 3 and that can be opened and closed in the axial direction of the inner cylinder 3.

The upper mold 12 is in pressure contact with the end face of the small diameter portion 5a, and forms a part of the cavity 4 for forming an outer surface of a lip 13 of an elastic portion 8 described later.

On the other hand, the lower die 10 has an annular groove portion 14 for holding the small diameter portion 5b, and an elastic portion 8 described later.
The lip 13 has a mold surface 26 for molding the outer surface of the inner cylinder 3 along the radial direction.

When the molds are matched, as shown in FIG. 3, the outer peripheral surface 25 of the groove 14 and the mold surface 26
The edge 15 formed at the boundary between the small diameter portion 5b and the large diameter portion 6 of the inner cylinder 3 is cut into the tapered surface 9 of the step portion over the entire circumference. In this state, a rubber material is injected into the cavity 4 and held at a predetermined temperature for a predetermined time, and after the rubber material is vulcanized and bonded to the outer peripheral surface of the inner cylinder 3, the mold is removed.

The anti-vibration bush 1 removed from the mold is shown in FIG.
As shown in the figure, an elastic portion 8 formed in a substantially cylindrical shape is integrally formed on the outer peripheral surface of the inner cylinder 3, and both ends of the elastic portion 8 in the axial direction are provided in the radial direction of the inner cylinder 3. Lip 13 is formed.

As shown in FIG. 5, the anti-vibration bush 1 has a through hole 1 provided in a rack 16 which is an outer cylinder.
The small-diameter portion 5 b of the elastic portion 8, which is press-fitted into the elastic member 8 and protrudes in the axial direction, is fitted in a hole 19 provided in the mounting member 18. The inner cylinder 3 is provided with a bolt 22 inserted from the upper end of the inner cylinder 3 in FIG.
Is fixed to the mounting member 18.

At this time, the lip 13 is sandwiched between the washer 21 and the upper end surface of the rack 16 at the upper end of the vibration isolating bush 1 and the mounting member 18 is formed at the lower end of the vibration isolating bush 1. And the lower end surface of the rack 16, and the anti-vibration bush 1 can secure high rigidity by being tightened with the bolt 22.

The anti-vibration bush 1 thus mounted
Is a small-diameter portion 5b that fits into the hole 19 of the mounting member 18.
When the rubber material flowing out of the cavity 4 is sandwiched between the outer peripheral surface of the mounting member 18 and the inner peripheral surface of the hole 19 of the mounting member 18 fitted with the outer peripheral surface as a rubber burr,
When an external force acts on the vibration isolating bush 1 in the direction of the arrow in the drawing, the lower end surface of the inner cylinder 3 in FIG. 22 becomes loose.

However, in the vibration isolating bush 1 formed by the above-described manufacturing method, the lower mold that opens and closes in the axial direction of the inner cylinder 3 when the rubber material to be the elastic portion 8 is injected into the cavity 4. By the movement of 10, the edge of the lower mold 10 is cut into the tapered surface 9 of the step portion between the small diameter portion 5b and the large diameter portion 6 on the lower end side of the inner cylinder 3 over the entire circumference. The rubber material injected into the cavity 4 is
The outflow to the outer peripheral surface of the small diameter portion 5b on the lower end side of the inner cylinder 3 can be reliably prevented.

Therefore, a grinding step for removing the rubber burrs flowing out of the outer peripheral surface of the small diameter portion 5b fitted to the mounting member 18 becomes unnecessary, and the cost can be reduced.

Further, rubber burrs are formed on the outer peripheral surface of the small diameter portion 5b without fitting the outer peripheral surface of the small diameter portion 5b fitted into the hole portion 19 of the mounting member 18 and the peripheral surface 25 of the groove portion 14 of the lower die 10. Since the adhesion is prevented, it is possible to prevent the inner cylinder 3 from biting into the mold and being unable to be taken out when the mold is removed, and the inner cylinder 3 is not required to have high dimensional accuracy. The manufacturing cost can be reduced.

Since the inner cylinder 3 has a stepped portion, it is manufactured to have the small diameter portion 5 and the large diameter portion 6, but it is manufactured with little cost increase by cold forging or the like. be able to.

FIG. 6 shows an anti-vibration bush 1 according to a second embodiment of the present invention. In the second embodiment, similarly to the first embodiment, the edge 15 of the lower mold 10 is engaged with the mounting member 18 over the entire circumference of the step between the small diameter portion 5b and the large diameter portion 6. In this second embodiment, the large-diameter portion 6 that forms a step with the small-diameter portions 5a and 5b at both ends of the inner cylinder 3 is designed to prevent the occurrence of rubber burrs on the outer peripheral surface of the small-diameter portion 5b. It is not continuous in the axial direction of the inner cylinder 3, but has a central portion in the axial direction of the inner cylinder 3 having substantially the same diameter as the small diameter portion 5.

In such an anti-vibration bush 1, when there is a problem in durability of the elastic portion 8, the elastic portion 8 can be formed thick without increasing the maximum outer diameter of the anti-vibration bush 1. Becomes

The present invention is not limited to the above embodiments, but can be applied to a vibration-isolating bush having inner and outer cylinders. In addition, the step portion between the small diameter portion 5 and the large diameter portion 6 does not necessarily need to be formed in a tapered shape, and the step portion may rise in a stepwise manner at a right angle.

[0028]

According to the first to third aspects of the present invention,
The movement of the lower mold 10 that opens and closes in the axial direction of the inner cylinder 3 causes the edge provided on the mold to be pressed against the stepped portion between the small-diameter portion and the large-diameter portion of the inner cylinder over the entire circumference. It is possible to prevent rubber burrs from adhering to the outer peripheral surface of the small diameter portion of the inner cylinder protruding from the portion.

Further, it is possible to prevent rubber burrs from adhering to the outer peripheral surface of the small-diameter portion of the inner cylinder protruding from the end of the cavity without fitting the small-diameter portion of the inner cylinder to a mold holding the small-diameter portion. Since it can be prevented, high dimensional accuracy is not required for the inner cylinder. Therefore, the manufacturing cost of the inner cylinder can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding apparatus used for manufacturing a vibration-isolating bush according to the present invention.

FIG. 2 is an enlarged view of a region A in FIG. 1 before mold matching.

FIG. 3 is an enlarged view of an area A in FIG. 1;

FIG. 4 is a sectional view of an anti-vibration bush according to the present invention.

FIG. 5 is a cross-sectional view of a state in which the vibration isolating bush according to the present invention is press-fitted into a rack serving as an outer cylinder.

FIG. 6 is a sectional view of an anti-vibration bush according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a conventional vibration isolating bush forming apparatus.

FIG. 8 shows a conventional anti-vibration bush.

[Explanation of symbols]

 3 ... Inner cylinder 5b ... Small diameter part 6 ... Large diameter part 9 ... Tapered surface 10 ... Lower die 15 ... Edge

Claims (3)

[Claims] 1. An inner cylinder is set in a mold composed of a plurality of molds, and a rubber material is injected into a substantially cylindrical cavity formed between the outer peripheral surface of the inner cylinder and the mold. In the method for manufacturing a vibration-isolating bush in which the inner cylinder and the rubber material are integrally formed, a large-diameter portion facing the cavity and a small-diameter portion connected to the large-diameter portion are formed in the inner cylinder,
A state in which an edge is provided on a mold that holds the small-diameter portion and forms a part of the mold surface of the cavity, and the edge is pressed against the step portion between the small-diameter portion and the large-diameter portion over the entire circumference. A method of manufacturing a vibration-proof bush, characterized by injecting a rubber material into the cavity. 2. The method according to claim 1, wherein the mold provided with the edge is movable in an axial direction of the inner cylinder.
3. The method for manufacturing a vibration-proof bush according to claim 1. 3. A stepped portion between the small-diameter portion and the large-diameter portion of the inner cylinder forms a tapered surface, and the edge is a state where the tapered surface is plastically deformed and bites. A method for manufacturing the vibration-isolating bush according to claim 1.