JPH06156253A - Method for molding bearing for piston rod of master cylinder - Google Patents

Abstract

PURPOSE:To provide a method for molding a synthetic resin bearing having annular inner and outer sealing grooves on inner and outer peripheral surfaces by using a simple structure molding die device having an integral core die. CONSTITUTION:After a synthetic resin insert ring 15, which has a channel shaped section and an inner seal groove 10 on its inside, is attached to a core die 21, a pair of side wall dies 22, 23 and an end wall die 24 are closed for forming a cavity 25, then a bearing body 16, which has an outer seal groove 11 and laps the insert ring 15, is formed by filling the cavity 25 with a synthetic resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing mounted on a cylinder body for supporting a piston rod projecting from a rear end surface of a piston in a master cylinder for operating a brake, a clutch and the like of an automobile, and more particularly, an inner and outer circumference. The present invention relates to a method of forming a bearing having annular inner and outer seal grooves on its surface.

[0002]

2. Description of the Related Art A conventional piston rod bearing is made of metal, and a seal groove is formed on the outer peripheral surface of the bearing by cutting.

[0003]

Recently, as part of the weight reduction of the master cylinder, there is a demand for resinizing the above bearing.
However, if this entire bearing were to be obtained by a single injection molding of synthetic resin, the core mold had to be composed of a complicated split mold due to the existence of the inner seal groove, and the equipment cost was high. As a result, the cost of the bearing will increase.

The present invention has been made in view of the above points, and by using an insert ring made of synthetic resin having an inner seal groove, the bearing is formed of synthetic resin without dividing the core mold. The purpose is to provide a simple and effective possible method.

[0005]

In order to achieve the above object, the present invention provides an inner seal by mounting an insert ring made of synthetic resin having a U-shaped cross section, the inner side of which is an inner seal groove, in an integral core type. Closing the open surface of the groove with the outer peripheral surface of the core mold, and closing a pair of side wall molds that open and close in the radial direction of the core mold and end wall molds that open and close in the axial direction of the core mold to close the cavity around the insert ring. And a step of filling the cavity with a synthetic resin to form a bearing body having an outer seal groove on the outer periphery and enclosing the insert ring.

According to the present invention, in addition to the above characteristics, an L-shaped ring formed by integrally connecting an annular end wall portion to one end of a cylindrical body is formed, and an L-shaped ring formed separately from the L-shaped ring is formed. Secondly, the insert plate is formed by engaging the end plate with the other end of the cylindrical portion.
It is a feature of.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 1, a master cylinder M for a brake of an automobile is constructed in a tandem type in which a pair of front and rear pistons 2f and 2r are slidably fitted in a cylinder hole 1a of a cylinder body 1. The inside of the cylinder hole 1a is divided into independent hydraulic chambers 3f and 3r by both pistons 2f and 2r. When the rear piston 2r is moved forward, the hydraulic pressure generated in these hydraulic chambers 3f and 3r is applied to each wheel brake of the automobile (Fig. (Not shown).

On the rear end surface of the rear piston 2r, a piston rod 4 extending rearward from the cylinder body 1 is integrally projected, and a bearing 5 for slidably supporting the piston rod 4 is provided on the cylinder body. It is attached to 1.

That is, as clearly shown in FIG. 2, at the rear end portion of the cylinder body 1, from the rear end of the cylinder hole 1a to the bottom surface 6a.
Is formed into a bottomed hole-shaped bearing housing 6, and a synthetic resin bearing 5 having a stepped outer peripheral surface is fitted from the bearing housing 6 to the rear end of the cylinder hole 1a. Then, in order to prevent the retaining, the circlip 7 as a retaining ring is engaged with the annular retaining groove 8 on the inner peripheral surface of the bearing housing 6.

On the inner and outer peripheral surfaces of the bearing 5, annular inner and outer seal grooves 10 and 11 are provided, and the inner seal groove 1 is formed.
No. 0 is equipped with a cup seal 12 as an inner seal member for bringing the lip portion into close contact with the outer peripheral surface of the piston rod 4, and the outer seal groove 11 is provided with an outer seal member for contacting the inner peripheral surface of the bearing housing 6. The O-ring 13 is attached.

A circlip 7 is provided on the rear end surface of the bearing 5.
When the diameter is reduced so as to be released from the locking groove 8, an annular stopper wall 14 that restricts the diameter reduction limit is integrally provided.

The bearing 5 is composed of an insert ring 15 having a U-shaped cross section that defines the inner seal groove 10 inside, and a bearing body 16 molded so as to enclose the insert ring 15. An outer seal groove 11 is provided on the outer circumference.

Referring again to FIG. 1, the cylinder body 1 is connected to the shell 32 of the negative pressure booster B by a bolt 33 at a flange 31 provided at the rear portion thereof, and the output rod 34 is connected to the piston rod 4 in the shell 32. The rear piston 2r is driven forward by the thrust of the output rod 34.

Next, a method of molding the bearing 5 will be described with reference to FIG.

First, the insert ring 15 is prepared. The insert ring 15 is formed by integrally connecting an annular end wall portion 17b, which extends inward in the radial direction, to one end of a cylindrical portion 17a.
It is composed of two members, that is, a character ring 17 and an annular end plate 18 that engages the outer peripheral side surface with the other end of the circular cylinder portion 17a. Is formed. The two members are individually molded by a conventional injection molding method. By such individual molding, burrs are not formed on the bottom surface of the inner seal groove 10, and the insert ring 15 having high dimensional accuracy can be easily obtained.

The insert ring 15 may be integrally molded by a blow molding method.

After the insert ring 15 is prepared, it is mounted on the integral core mold 21 and the open surface of the inner seal groove 10 is closed by the outer peripheral surface of the core mold 21. Then, by closing the pair of side wall molds 22 and 23 that are opened and closed in the radial direction of the core mold 21, and then closing the end wall mold 24 that is opened and closed in the axial direction of the core mold 21, the bearing main body 16 is surrounded by the insert ring 15. To define a cavity 25 corresponding to. A pair of side wall type 2
2 and 23 are provided with semi-annular projections 22a and 23a corresponding to the semi-circumferential portion of the outer seal groove 11 on the inner surface, respectively.

Then, the synthetic resin melted through a gate (not shown) is injected and filled into the cavity 25 to mold the bearing body 16, and the bearing ring 16 is fused with the insert ring 15. At that time, especially the insert ring 15
Since the annular protrusions 19 and 20 have a small heat capacity, they are easily melted and reliably fused with the bearing body 16.

The bearing 5 molded in this way is the side wall mold 2
After opening 2, 23 and the end wall mold 24, the core mold 21 is taken out.

[0021]

As described above, according to the first feature of the present invention, the insert ring made of synthetic resin having a U-shaped cross section and having the inner side as the inner seal groove is attached to the integral core type, and the inner seal groove is formed. Closing the open surface of the core mold with the outer peripheral surface of the core mold, and closing the pair of side wall molds that open and close in the radial direction of the core mold and the end wall mold that opens and closes in the axial direction of the core mold to form a cavity around the insert ring. Since it includes a step of defining and a step of filling the cavity with a synthetic resin to form a bearing body having an outer seal groove on the outer periphery and enclosing the insert ring, an integral core mold, a pair of side walls and With a simple molding device having an end wall mold, a synthetic resin bearing having inner and outer seal grooves can be easily molded, which can contribute to weight reduction and cost reduction of the bearing.

Further, according to the second feature of the present invention, an L-shaped ring formed by integrally connecting an annular end wall portion to one end of the cylindrical portion is formed, and the ring formed separately from the L-shaped ring is formed. Since the end plate of the insert ring is engaged with the other end of the cylindrical portion to form the insert ring, the components of the insert ring can be easily and highly accurately molded by a simple molding die, and in particular, the inner seal groove The bottom surface of the can be formed to be smooth without burrs, and the sealing function of the inner sealing member attached thereto is not impaired.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a master cylinder equipped with a bearing formed by the method of the present invention.

FIG. 2 is an enlarged view of part 2 of FIG.

FIG. 3 is a vertical cross-sectional view of a molding die showing a method for molding the bearing.

[Explanation of symbols]

 4 Piston rod 5 Bearing 10 Inner seal groove 11 Outer seal groove 15 Insert ring 16 Bearing body 17 L-shaped ring 17a Cylinder part 17b End wall part 18 End plate 21 Core type 22 Side wall type 23 Side wall type 24 End wall type 25 Cavity M master cylinder

Claims (2)

[Claims] 1. A master cylinder (M) is mounted on a cylinder body (1) for slidably supporting a piston rod (4), and annular inner and outer seal grooves (10,
A method for forming a piston rod bearing of a master cylinder, which comprises 11), wherein a core-shaped synthetic resin insert ring (15) having a U-shaped cross-section, the inner side of which is an inner seal groove (10), is integrally formed (21). The inner seal groove (10) with the open surface of the core type (2
1) A step of closing by the outer peripheral surface, and a pair of side wall molds (2) that are opened and closed in the radial direction of the core mold (21).
2, 22) and the end wall mold (24) that opens and closes in the axial direction of the core mold (21) to define a cavity (25) around the insert ring (15); It is filled with a synthetic resin and has an outer seal groove (11) on the outer periphery and an insert ring (1
5) A step of forming a bearing body (16) enclosing the bearing 5), the method for forming a piston rod bearing of a master cylinder. 2. The L-shaped ring (17) according to claim 1, wherein an annular end wall portion (17b) is integrally connected to one end of the cylindrical portion (17a), and An annular end plate (18) formed separately from the cylindrical body (17)
A method for molding a piston rod bearing of a master cylinder, characterized in that the insert ring (15) is formed by engaging with the other end of (a).