JPH10231874A - Preliminary compression method of rectangular elastic bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of a bush by connecting an inner cylinder and an outer cylinder of a rectangular cylindrical shape to each other by a rubber elastic body interposed between both of the cylinders by a vulcanizing adhesion means, extending dimensions of a cross-section of the inner cylinder and applying compression on the elastic body. SOLUTION: Rectangular cylindrical inner cylinder 1 and outer cylinder 2 concentrically arranged of metallic rectangular cylindrical bodies of steel pipes, etc., the inner cylinder 1, the outer cylinder 2 and an unvulcanized rubber material of a rubber elastic body 3 between the both cylinders 1, 2 are vulcanized and molded by setting them in a vulcanizing mold, and the rubber elastic body 3 is adhered and fixed on the both cylinders 1, 2. After vulcanizing and molding, the dimensions of the cross-section of the inner cylinder 1 is extended, and specified preliminary compression is given to the rubber elastic body 3. A processing method is to expand a constantly shaped rectangular cylindrical body inside dimensions of longitudinal and lateral two sides of which are smaller than inside dimensions A1, B1 of two sides of a finished article. Consequently, it is possible to extend the inner cylinder 1 without giving deformation of undulation, etc., on each of surface parts of four corners of the inner cylinder 1, and to give necessary and uniform optional preliminary compression to the rubber elastic body 3. Consequently, it is possible to improve durability and to provide a stable vibration proofing property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of applying a pre-compression in a manufacturing process of an elastic bush to be incorporated in a suspension of an automobile and the like, in particular, a square elastic bush.

[0002]

2. Description of the Related Art A connecting portion between a vehicle body and a suspension, for example, a connecting portion between a lower arm supporting a wheel and a vehicle body side member such as a frame, etc., is provided to reduce vibration of the vehicle body. Elastic bushes are commonly used.

As shown in FIG. 7, the elastic bush is formed by a rubber elastic body (53) having a cylindrical inner cylinder (51) and an outer cylinder (52) interposed between both cylinders by a vulcanization bonding means. It is common to form a combined circular cross section. Further, there is a type in which the outer cylinder (52) is press-fitted and fixed to the rubber elastic body (53) with an appropriate interference. Usually, an end of a lower arm or the like is fixed to the outer periphery of the outer cylinder (52) before use.

When a high load is applied in the direction perpendicular to the axis of the circular bush, the outer cylinder (52) is displaced toward the inner cylinder (51) as shown by a chain line in FIG. And outer cylinder (52)
Due to the difference in circumference, the maximum strain is concentrated on one portion (53a) of the rubber elastic body (53) on the side to which an external force is applied.

For this reason, in recent years, a rectangular cross-section in which the four circumferential surfaces of the inner and outer cylinders are opposed to each other so as to avoid concentration of strain when a load is applied and to obtain a large spring characteristic, that is, a vibration-proof characteristic in a certain direction. Square bush has also appeared.

Incidentally, in this type of elastic bush, a vulcanized rubber elastic body (53) is used for the purpose of reducing shrinkage after rubber vulcanization and tensile strain under load and improving durability.
The rubber elastic body (53) is compressed by applying a certain drawing process to the outer cylinder (52) to reduce the diameter of the outer cylinder (52).

[0007] In the case of the rectangular bush as well, the outer cylinder is drawn as in the case of the circular bush, so that the rubber elastic body is pre-compressed.

[0008] However, in the case of the above-mentioned rectangular bush, the strain under load does not concentrate on one place,
Drawing of the outer cylinder (52) for applying compression to the rubber elastic body (53) is very difficult. For example, a square outer cylinder (52)
Even if it is attempted to uniformly deform each surface portion of the four circumferences (surfaces of each side in the cross section) while drawing a flat shape by drawing, it is likely that some wavy deformation occurs as shown in FIG. When such deformation occurs, the inner rubber elastic body (5
As a result, uniform compression cannot be given to 3), and the effect of giving preliminary compression cannot be sufficiently obtained, resulting in poor durability.

The present invention has been made in view of the above, and in a rectangular elastic bush, it is possible to apply uniform preliminary compression to a rubber elastic body and to improve the durability of the bush. Provide a way.

[0010]

SUMMARY OF THE INVENTION The present invention is a method for pre-compressing a rectangular elastic bush, which solves the above-mentioned problem. It is characterized in that the rubber elastic body interposed between the inner and outer cylinders is expanded by expanding the cross-sectional dimension of the inner cylinder by compressing the rubber elastic body between the inner and outer cylinders.

According to the method of the present invention, the cross-sectional dimension can be increased without giving a deformation such as waving to the four circumferential surfaces of the inner cylinder by the pipe expanding process. Can give compression.

According to a second aspect of the present invention, in the above-described pre-compression applying method, the rectangular cylinder whose inner dimensions (A) and (B) of two sides are smaller than the inner dimensions (A1) and (B1) of the two sides of the finished product. The body is used as an inner cylinder, and the inner cylinder is formed into an inner dimension of two sides of the finished product by expanding the inner cylinder after vulcanization molding. As a result, uniform pre-compression can be reliably applied to the rubber elastic body, and a finished product having a constant inner dimension of the inner cylinder can be obtained.

According to a third aspect of the present invention, in the above-described pre-compression applying method, the rectangular cylindrical body in which the inside dimensions of the two sides at the center of each of the four circumferential surfaces are smaller than the inside dimensions of the two sides at the side edges. Used for cylinders, by expanding the inner cylinder after vulcanization molding,
It is characterized in that the inside dimensions of the two sides are formed into the inside dimensions (A1) and (B1) of the two sides of the finished product. In this case, the tube can be expanded without giving the metal material of the inner tube itself an excessive extension, and the rubber elastic body can be uniformly pre-compressed without causing damage to the expanded inner tube.

According to a fourth aspect of the present invention, there is provided the pre-compression applying method, wherein a rectangular cylindrical body having constant inner dimensions (A) and (B) of two sides is used for the inner cylinder, and the rubber elastic body is vulcanized and formed. When
By keeping a gap between the core of the vulcanizing mold inserted inside the inner cylinder and the inner cylinder, each surface portion of the inner cylinder is bent inward by the vulcanization pressure of the rubber elastic body and deformed inward. And the inside dimensions of the two sides of the inner cylinder to the inside dimensions of the two sides of the finished product (A1)
And (B1), the inner product after vulcanization molding is expanded to form two inner sides of the finished product.

In this case, depending on the size of the core of the vulcanizing mold,
The inner dimensions of the two sides when the inner cylinder is deformed are determined. Therefore, by forming this into the inner dimensions of the two sides of the finished product by expanding the pipe, each of the deformed surface portions is extended in a flat plate shape. As a result, the thickness of the pre-compressed rubber elastic body becomes constant, and stable characteristics can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a pre-compression applying method of the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 show a rectangular elastic bush manufactured by applying a pre-compression according to the method of the present invention. (1) and (2) in the figure are an inner cylinder and an outer cylinder of a concentrically arranged rectangular cylinder shape, both of which are formed by a metal square cylinder such as a steel pipe. A rubber elastic body (3) is interposed between the outer cylinder (1) and the outer cylinder (2) by being bonded to the two cylinders by vulcanization bonding means, and the two cylinders are connected.

The square elastic bush is formed by setting an inner cylinder (1) and an outer cylinder (2) and an unvulcanized rubber material of a rubber elastic body (3) between the two cylinders in a vulcanization mold. Perform sulfur molding,
It can be obtained by bonding and fixing the rubber elastic body (3) to the inner and outer cylinders (1) and (2). In the case of the present invention, in particular, after the vulcanization molding, the inner cylinder ( By expanding the cross-sectional dimension of 1), a predetermined pre-compression is given to the rubber elastic body (3) around it. The two-dot chain lines in FIGS. 1 and 2 show the cross-sectional shape of the inner cylinder (1) before the expansion, and this is expanded and expanded to the cross-sectional shape of the solid line.

As a specific processing method, as shown in FIG. 3, the inside dimensions (A) and (B) of the two sides are smaller than the inside dimensions (A1) and (B1) of the two sides of the finished product. A rectangular cylinder having a predetermined shape is used for the inner cylinder (1), and the inner cylinder (1) is formed into an inner dimension of two sides of the finished product by pipe expansion after the vulcanization molding.

By doing so, each surface portion (each side in the cross section) of four sides of the rectangular inner cylinder (1) (11) (1
2) Since the cross-sectional dimension can be increased without giving a deformation such as waving to (13) and (14), the rubber elastic body around it (3)
, A necessary and uniform pre-compression can be given to the inner cylinder (1), and a finished product in which the inner dimensions of two sides of the inner cylinder (1) are constant can be obtained.

The inner and outer dimensions (A) and (B) and the thickness (t) of the cylindrical body used for the inner cylinder vary depending on the location of the bush, for example, A = 10 to 30 mm B = 30 to 60 mm t = 1.2 to 3.2 mm. Of course, it is also possible to set the dimensions outside the above range.

Further, in the above-mentioned processing method, as shown in FIG. 4, the inner cylinder (1) has four circumferential surfaces (11).
(14) are concavely curved inward at the center, and the inner dimensions (a) and (b) of the two vertical and horizontal sides at the center are changed to the inner dimensions (A) (A) ( B) Using a rectangular cylinder smaller than that described above, and vulcanizing and expanding the pipe in the same manner as described above, thereby forming the concave portions (11a) (12) of the respective surface portions (11) to (14).
a) It is also possible to extend (13a) and (14a) into a flat plate shape to form the inside dimensions of the two sides into the inside dimensions (A1) and (B1) of the two sides of the finished product, respectively.

In this case, since the pipe can be expanded without giving an excessive elongation to the metal material itself of the inner cylinder (1), the inner cylinder (1) can be expanded.
A uniform pre-compression can be applied to the rubber elastic body (3) without causing damage to the rubber elastic body (3).

The difference between the inner dimensions (a) and (b) of the two vertical and horizontal sides at the center of each surface part and the inner dimensions (A) and (B) of the two sides at the side edges are respectively Aa = 0.3 to 1.0 mm Bb = 0.3 to 1.0 mm is particularly preferable from the viewpoint of the reliability of the molding by the pipe expanding process.

As the above-mentioned processing means, as shown in FIG. 5, a rectangular cylindrical body having constant inner dimensions (A) and (B) of two sides is used for the inner cylinder (1), and a rubber elastic body (3) is used. During vulcanization molding, the dimensions (C) and (D) of the two sides of the core (4) of the vulcanization mold inserted inside the inner cylinder (1) are respectively set to the two sides of the inner cylinder (1). By making the gap (S) between the inner core (4) and the inner cylinder (1) slightly smaller than the inner dimensions (A) and (B) of the rubber elastic body (3) Each surface portion (11) to (14) of the inner cylinder (1) is bent inward by the vulcanization pressure of (1), and the inner dimensions of the two sides of the inner cylinder (1) are changed to the inner dimensions (A1) of the two sides of the finished product. And (B1), which are then vulcanized and expanded in the same manner as described above, so that each of the flexurally deformed surface portions (11) to (14) is extended into a flat plate shape, and two sides of the finished product are formed. Inside It can also be molded to the dimensions.

In this case, the dimensions of the two sides of the core (4) of the vulcanization mold determine the inside dimensions of the two sides when the inner cylinder (1) is flexed and deformed. By molding to the inside dimensions of the two sides of the above, the thickness of the pre-compressed rubber elastic body (3) becomes constant, and stable characteristics can be obtained.

Dimensions (C) of two sides of the core (4)
The difference between (D) and the inner dimensions (A) and (B) of the two sides of the inner cylinder is as follows: AC = 0.3 to 1.0 mm BD = 0.3 to 1.0 mm It is particularly preferable for forming by pipe expansion. As the thickness (t) of the inner cylinder (1), one having a thickness that can tolerate the above-mentioned bending deformation due to the vulcanization pressure is used.

As the above-mentioned method of expanding the pipe, a conventionally well-known expanding method of expanding the inside of the inner cylinder (1) by driving a rod material such as a wedge for expanding the pipe can be used. In this case, either a method of enlarging the inside dimensions of the two sides of the inner cylinder (1) at one time, or a method of enlarging one dimension of the two sides and then enlarging the other dimension may be used.

When the elastic bush is fixed, the inner cylinder (1) can be expanded by press-fitting a fixing member. Further, as shown in FIG. 6, the pipe-shaped rod (5) used for the pipe expansion process by press-fitting can be used as it is as a support member having a double structure with the inner cylinder (1).

In any of the pipe expanding methods, the pipe can be easily and reliably expanded because it is a square bush and the inner cylinder (1) is also rectangular.

That is, when expanding the circular inner cylinder of the round bush, the diameter must be increased over the entire circumference, and the apparatus cannot be implemented unless a device jig capable of expanding the diameter over the entire circumference is used. On the other hand, if the bush is rectangular as in the bush of the present invention, the wedge having a square cross section is driven in two directions or one direction as described above, or a member having a square cross section is press-fitted to surely expand the pipe. can do.

[0032]

According to the pre-compression applying method of the present invention described above, despite the rectangular elastic bushing, the deformation of the corrugated shape as in the case where the outer cylinder is drawn by expanding the inner cylinder is performed. It does not occur, and uniform pre-compression can be reliably applied to the rubber elastic body, and its durability can be improved. In addition, stable anti-vibration characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a rectangular elastic bush in which a method of the present invention is performed.

FIG. 2 is a cross-sectional view of the same.

FIG. 3 is a front explanatory view exemplifying a state of an inner tube expanding process;

FIG. 4 is an explanatory front view illustrating another state of the pipe expanding process of the inner cylinder.

FIG. 5 is a front explanatory view exemplifying a state of still another expanding process of the inner cylinder.

FIG. 6 is a cross-sectional view of still another embodiment of the inner cylinder.

FIG. 7 is a cross-sectional view illustrating a conventional elastic bush.

FIG. 8 is an explanatory view showing a drawing state of an outer cylinder of a square bush.

[Explanation of symbols]

 (1) Inner cylinder (2) Outer cylinder (3) Rubber elastic body (4) Core

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Suzuki 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka Toyo Tire & Rubber Co., Ltd.

Claims (4)

[Claims] An inner cylinder and an outer cylinder each having a rectangular cylindrical shape are connected to each other by a rubber elastic body interposed between the two cylinders by a vulcanizing adhesive means, and a cross-sectional dimension of the inner cylinder is enlarged by pipe expansion processing. A method of pre-compressing a rectangular elastic bush, wherein compression is applied to the rubber elastic body between the inner and outer cylinders. 2. A rectangular cylindrical body whose inside dimensions (A) and (B) of the two sides are smaller than the inside dimensions (A1) and (B1) of the finished product are used for the inner cylinder. 2. The method for applying a pre-compression of a rectangular elastic bush according to claim 1, wherein the tube is formed to have inner dimensions of two sides of the finished product by expanding a tube. 3. An inner tube having a rectangular shape in which the inside dimensions of two sides at the center of each of the four peripheral surfaces are smaller than the inside dimensions of the two sides at the side edges is used as the inner cylinder, and the inner cylinder after vulcanization molding is expanded. By processing
3. The method according to claim 1, wherein the inside dimensions of the two sides are formed into the inside dimensions (A1) and (B1) of the finished product. 4. A vulcanization molding of a rubber elastic body, wherein a rectangular cylindrical body having constant inner dimensions (A) and (B) of two sides is used for an inner cylinder.
By keeping a gap between the core of the vulcanizing mold inserted inside the inner cylinder and the inner cylinder, each surface portion of the inner cylinder is bent inward by the vulcanization pressure of the rubber elastic body and deformed inward. The inner dimensions of the two sides of the inner cylinder to the inner dimensions of the two sides of the finished product (A1)
3. The square elastic bushing according to claim 1, wherein said inner cylinder is formed into an inner dimension of two sides of said finished product by expanding the inner cylinder after vulcanization molding. Compression application method.