JP2007278409A - Method for manufacturing bellows boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a bellows boot, which method is excellent in the workability in setting an insert to be gripped in an engaging portion into a boot forming die, and further hardly causes the defective forming of the engaging portion due to the displacement of the insert to be gripped. <P>SOLUTION: The method for manufacturing the divided bellows boot made of rubber-like elastic body is provided. The divided bellows boot comprises thick wall portions formed on both sides of the divided position of the boot, and a general portion which is thinner than the thick wall portions, and has nearly the same wall thickness, and is connected circumferentially. The thick wall portion comprises a seal fastener composed of an engaging strip portion which is formed along one end edge and has a swelled engaging portion at its tip end, and a strip portion to be engaged, which portion is formed along the other end edge and has an engaging groove. The portion to be engaged is formed by burying the insert to be gripped which is made of wire material and has a corrugated plane. The bellows boot is formed by setting the insert 34A to be gripped having a shape following the shape of the bellows at the thick-walled portion 18 in forming dies 36A, 36B. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a bellows boot that is divided in a vertical direction so that maintenance is easy, and a pair of fasteners are arranged in the divided portion. In particular, rubber shaft elastic joint boots (hereinafter simply referred to as “boots”) that are used as protective members for universal shaft joint parts of automobiles, machine tools, construction machines, and various industrial machines. This relates to a method of manufacturing a bellows boot suitable for manufacturing.

  Here, a universal shaft joint boot will be described as an example of the bellows boot.

  Conventionally, as a split type boot, a universal shaft joint boot having the following configuration has been proposed by the same applicant as the present applicant (see “Claims” of Patent Document 1).

“It is formed of a rubber-like elastic body, and the space between the small diameter ring portion 12 and the large diameter ring portion 14 is the bellows portion 16.
The small-diameter ring portion 12 to the large-diameter ring portion 14 are divided along the generatrix, and the thick-walled portions 18 and 18 formed on both sides of the divided position are thinner and substantially identical to the thick-walled portions 18 and 18. A general portion 20 that is thick and connected in the circumferential direction;
The thick-walled portions 18 and 18 are formed along one end edge and have a band-shaped occlusal portion 24 having a bulging engagement portion 22 at the tip, and the bulging portion along the other end edge. A universal joint joint boot having a structure in which a seal fastener 30 including a band-shaped occlusal portion 28 provided with an engagement groove 26 that engages with a joint portion 22 is formed. (The reference numerals are taken from FIGS. 1A and 1B.)
However, it has been found that there are the following problems in manufacturing the universal shaft joint boot having the above-described configuration.

  Usually, in the above-described configuration, the outer peripheral portion of the engagement groove 26 of the occlusal portion 28 is made of a linear (spring) material, and the sandwiching insert (U A spring) 32 is embedded, and a spring clamping force is applied between the opening end portions of the occluded portion 28. Further, the occlusal portion 24 is embedded with a sandwiched insert (flat spring) 34 made of a linear (spring) material and having a corrugated plane.

  Then, the boot having the above-described structure is formed by holding the sandwiching insert 32 with a core (not shown) that shapes the engaging groove 26 and setting the sandwiched insert 34 as shown in FIG. The elastic molding material is formed by injection vulcanization molding (in the case of rubber) or by injection cooling molding (thermoplastic elastomer) while being set between a pair of mating dies 36A and 36B to be shaped.

  After setting the linear sandwiched insert (straight shape) 34 on the corrugated plane made of the linear spring material to the pair of occlusal shaping portions 36A and 36B of the boot molding die (FIGS. 2A and 2B) ), After the injection and solidification of the molding material, it was released (FIG. 2 (C)).

  However, setting the sandwiched insert to the boot mold is troublesome and time-consuming. Also, the set position was not stable due to spring repulsion or the like. That is, the sandwiched insert is exposed near the peak portion or valley portion of the bellows, and the occlusal portion may be formed.

Although it does not affect the patentability of the present invention, Patent Documents 2 and 3 exist as split type universal shaft boots.
Japanese Patent No. 2714635 JP-A-8-261824 JP-A-9-119522

  In view of the above, the present invention has a good workability in setting the sandwiched insert to the boot molding die in the occlusal portion, and further, the occlusal boot which does not easily cause the occlusal portion molding failure due to the displacement of the sandwiched insert. An object (problem) is to provide a manufacturing method.

  As a result of diligent efforts to solve the above problems, the present inventor has conceived a method for manufacturing an accordion boot having the following configuration.

It is formed of a rubber-like elastic body, and the space between the small diameter ring part and the large diameter ring part is the bellows part,
It is divided along the generatrix from the small-diameter ring portion to the large-diameter ring portion, and the thick-walled portion formed on both sides of the divided position is made thinner than the thick-walled portion so that it is substantially the same thickness and is connected in the circumferential direction. With general part,
The thick-walled portion is formed along one end edge and has a belt-like occlusal portion provided with a bulge engagement portion at the tip, and a member engaged with the bulge engagement portion along the other end edge. A seal fastener composed of a band-shaped part to be bitten with a groove is formed,
The outer periphery of the engagement groove is made of a linear spring material, and a sandwich insert having a cross-sectional shape that has substantially no corners is embedded, and a spring is interposed between the opening end portions of the occlusal portion. A sandwiching force is applied, and in the occlusal part, a corrugated flat or strip-shaped sandwiched insert made of a wire is embedded in a manufacturing method of a bellows boot,
As a sandwiched insert, a bellows boot is molded by setting a seal portion having a shape conforming to the bellows shape in a molding die.

  Since the sandwiched insert is molded using a shape that conforms to the bellows shape of the seal portion, the set workability for the molding die is greatly facilitated. In other words, the sandwiched insert is set in the mating part occlusal shaping portion, and the elastic material flows from both sides, so that the sandwiched insert is held and molded at the center position, and the sandwiched insert is unevenly formed. It will not be done.

  In the above configuration, the forming process of the sandwiched insert into the bellows shape is performed by the shaping mold having the bellows shaping section, and further, the shaping mold having the bellows shaping section is a pair of matching. It is desirable to be a shaping type.

  Further, in the above configuration, it is desirable to perform the forming process of the sandwiched insert into the bellows shape while heating, and this heating is performed by forming the sandwiched insert with a conductor and conducting the shaping process on the sandwiched insert. It is desirable to carry out with resistance heating.

  In each of the above configurations, the sandwiched insert is usually formed of stainless spring steel.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the configuration. That is, various design changes can be made without departing from the gist of the present invention.

  The boot 10 of the present embodiment is applied to the vertically divided type boot described in the above-mentioned Patent Document 1 (see FIG. 1). That is, the basic form is described below by adapting to the boot of the conventional form as follows. can do.

  The boot 10 of the present invention is formed of a rubber-like elastic body, and a space between the small diameter ring portion 12 and the large diameter ring portion 14 is a bellows portion 16. And it is divided | segmented along a bus line from the small diameter ring part 12 to the large diameter ring part 14, and the thick part 18 and 18 formed in the both sides of this division | segmentation position, and it is thinner than this thick part 18 and 18, and is substantially It is the form provided with the general part 20 made into the same thickness and connected in the circumferential direction.

  The boot 10 of this embodiment (usually grease is enclosed in the boot 10) uses a rubber-like elastic body having grease resistance, specifically, a rubber material such as chloroprene rubber or acrylic rubber. Vulcanization molding in the expanded state by injection molding. When the rubber-like elastic body is molded from a thermoplastic elastomer (TPE) such as polyester or polyolefin, injection blow molding is also possible.

  The small-diameter ring portion 12 and the large-diameter ring portion 14 serve as a fixed portion when the boot 10 is mounted on the universal shaft joint portion. Further, the bellows portion 16 plays a role of covering and protecting the mounting portion after the boot 10 is mounted on the universal shaft coupling portion. In FIG. 1, the peak portions 38 and the valley portions 40 of the bellows portion are both provided at four locations, but may be three locations or less or five locations or more as long as the bellows shape is provided.

  The reason why the boot 10 is divided (opened) is to facilitate the work of attaching / detaching the boot 10 to / from the universal joint portion. Since the boot 10 is a protective member, it is often replaced periodically, and facilitating the mounting / demounting operation at the time of replacement is beneficial.

  That is, if it is not divided, it is necessary to insert the boot 10 into the universal joint portion from the small diameter ring portion 12 side or the large diameter ring portion 14 side in the mounting operation. There is a need to disassemble. However, by dividing, the boot 10 can be mounted so as to sandwich the universal joint portion. Therefore, particularly when mounted on a steering unit or the like, disassembly work and adjustment work accompanying disassembly are not required.

  In order to close the division, the boot 10 has thick portions 18 and 18 on both sides of the division position. The thick portions 18 and 18 are formed along one edge and swell at the tip. From a belt-like occlusal portion 24 provided with a protruding engagement portion 22 and a belt-like occluded portion 28 provided with an engagement groove 26 that is formed along the other edge and engages the bulging engagement portion 22. A seal fastener 30 is provided.

  On the outer peripheral portion of the engagement groove 26, a sandwiching insert 32 made of a linear spring material and having a cross-sectional shape substantially having no corners is embedded, and an end portion of the opening of the occlusal portion 28 is embedded. A spring clamping force is applied between them, and a corrugated flat or strip-like sandwiched insert 34A made of a wire is embedded in the occlusal portion 24. These inserts 32 and 34A are embedded from the viewpoint of insertion workability and sealing performance.

  The bulging engagement portion 22 and the engagement groove 26 are engaged, and the seal fastener 30 (the occlusal portion 24 and the occluded portion 28) is closed (engaged). Then, the general part 20 and the thick parts 18 and 18 are closed, and the boot 10 becomes a circumferential direction continuous shape. At this time, the engagement interface between the occlusal portion 24 and the occluded portion 28 is buried inside the thick portions 18 and 18, and the sealing performance necessary as a protective member is ensured.

  In the above configuration, the thickness difference between the thick portions 18 and 18 and the general portion 20 is about 0.5 to 3.0 mm, and further 1.0 to 2.0 mm may satisfy the required use characteristics. It is possible and desirable.

  In this embodiment, when the boot 10 having the above-described configuration is manufactured, the sandwiched insert 34A is set to a molding die (matching dies 36A, 36B) having a shape that conforms to the bellows shape of the thick wall portion. 10 is formed (FIGS. 3A to 3C).

  Note that the sandwiched insert 34A is inserted into the gap between the closed mating dies 36A and 36B, and then incorporated into the boot body molding die using the mating dies 36A and 36B as a core. Then, the molding material is injected. At this time, as shown in FIG. 4A, even if the set position of the sandwiched insert 34A is slightly shifted, the material flows from both sides of the sandwiched insert 34A and is sandwiched. In the insert 34 </ b> A, the occlusal portion 24 (the bulging engagement portion 22) is formed with the insert 34 </ b> A substantially returned to the neutral position.

  In the example shown in the figure, the sandwiched insert 34A has a flat corrugated shape made of a wire, but may be a strip. For example, in the case of a flat corrugated shape, the sandwiched insert 34A before the shaping process is formed into a flat corrugated shape by plastic processing of a wire with a comb-shaped male / female side.

  Although the shaping process to the shape which follows the bellows shape of the to-be-clamped insert 34 is not specifically limited, For example, as shown in FIG. 5, it is desirable to perform with a pair of matching shaping type | molds 42A and 42B. At that time, it is desirable that the sandwiched insert 34 is formed of a conductor such as stainless spring steel, and the shaping process is performed while energizing the sandwiched insert and performing resistance heating. Heating facilitates the shaping process. As a heating means, it is conceivable to heat the mold itself, but resistance heating has better thermal efficiency.

  For example, when the wire rod is 0.3 mmφ and the total length is 250 mm, instantaneous (0.5 to 1 second) is sufficient at 200 V × 40 A.

  In addition, you may perform a shaping process, pressing on the one-piece shaping mold like a jig, without using a matching shaping mold.

  The insert material is not limited to a conductor (metal material) such as stainless steel, but may be a hard plastic or the like. In the case of a hard plastic material, it is desirable that the insert material be simultaneously shaped during preparation (molding).

It is a perspective view in the open state of the division | segmentation boot to which this invention is applied. It is a process perspective view which shows an example of the shaping | molding method of the conventional entanglement part. It is a process perspective view which shows an example of the method of shape | molding the occlusion part of this invention in the case of manufacture of a division | segmentation boot. It is a sectional view for explanation similarly. It is a process perspective view which shows an example of the shaping process method of the to-be-clamped insert in this invention.

Explanation of symbols

10 Universal shaft joint boots (split boots)
DESCRIPTION OF SYMBOLS 12 Small diameter ring part 14 Large diameter ring part 18 Thick part 22 Swelling engagement part 24 Occlusion part 26 Engagement groove 28 Occlusion part 30 Seal fastener 32 Clamping insert 34, 34A Clamping insert 42A, 42B Fitting shaping type

Claims (6)

It is formed of a rubber-like elastic body, and the space between the small diameter ring part and the large diameter ring part is the bellows part,
It is divided along the generatrix from the small-diameter ring portion to the large-diameter ring portion, and the thick-walled portion formed on both sides of the divided position is thinner than the thick-walled portion and is substantially the same thickness and connected in the circumferential direction. And general part to
The thick wall portion is formed along one end edge, and is formed along a belt-like occlusion portion having a bulge engagement portion at the tip, and the other bulge engagement portion. A seal fastener comprising a band-shaped portion to be engaged with an engaging groove to be engaged,
On the outer peripheral portion of the engagement groove, a sandwiching insert made of a linear spring material and having a cross-sectional shape substantially having no corners is embedded, and between the opening end portions of the occluded portion A method of manufacturing a bellows boot having a corrugated flat or strip-like sandwich insert made of a wire, embedded in a spring clamping force,
A manufacturing method of the bellows boot, wherein the sandwiched insert is formed in a shape that conforms to the bellows shape of the thick portion in a molding die, and the bellows boot is molded.   The method for manufacturing an accordion boot according to claim 1, wherein the forming processing of the sandwiched insert into an accordion shape is performed by an shaping mold provided with an accordion shaping portion.   The manufacturing method of the bellows boot according to claim 2, wherein the shaping mold provided with the bellows shaping section is a pair of matched shaping molds.   The method for manufacturing a bellows boot according to claim 2 or 3, wherein the forming process of the sandwiched insert into a bellows shape is performed while heating.   5. The method of manufacturing a bellows boot according to claim 4, wherein the sandwiched insert is formed of a conductor, and the shaping process is performed while energizing the sandwiched insert and performing resistance heating.   6. The method of manufacturing a bellows boot according to claim 5, wherein the sandwiched insert is made of stainless spring steel.

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