JPH10141326A - Clamping method between cylindrical bracket part and bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with any work for finishing an inner circumferential surface of a cylindrical bracket part so accurately by inserting and setting up a bush in this cylindrical bracket part, and then clamping an outer diameter of this bush after diametrically contracting the cylindrical bracket part by means of electromagnetic forming. SOLUTION: A bush 3 is inserted and set up in a cylindrical bracket part 2a. Afterward, electromagnetic forming is applied to this bracket part. This electromagnetic forming uses a pipe contracting electromagnetic forming coil 4, and the cylindrical bracket part 2a of a bracket 3 is set up in this coil 4 in a concentric state, while a flux concentrator 6, excluding a projection 2b of the bracket 2, is set up in a C- shaped form in space between the cylindrical bracket part 2a and the coil 4. In addition, an insulator 7 is set up in circumferential double ends of the flux concentrator 6 in response to the projection 2b, and an instantaneous large current is impressed to the coil 4. Owing to impression of this instantaneous large current, the flux concentrator 6 and the cylindrical bracket part 2a both cause magnetic repulsion, and thereby the cylindrical bracket part 2a is diametrally contracted by this magnetic repulsion, clamping an outer circumferential part of the bush 3 tight enough.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fastening a cylindrical bracket portion and a bush used in the manufacture of, for example, an engine mount and a suspension arm for an automobile.

[0002]

2. Description of the Related Art For example, a vehicle engine mount and a suspension arm are provided with a tubular bracket portion, and a bush for vibration isolation or the like is arranged in the tubular bracket portion in an outer peripheral tightening state. Done. For the bush, for example, an inner cylinder made of the same metal is arranged in a metal outer cylinder with its axial direction parallel to each other, and an elastic body such as rubber is loaded between the outer peripheral portion of the inner cylinder and the inner peripheral portion of the outer cylinder. What is integrated by baking or the like is used.
Conventionally, the fastening between the tubular bracket portion and the bush as described above has been performed by press-fitting the bush into the tubular bracket portion.

However, in the fastening method by press fitting,
In order for the cylindrical bracket to hold the outer periphery of the bush in the proper tightening state, extremely troublesome cutting work must be performed to finish the inner peripheral surface of the cylindrical bracket with high dimensional accuracy, increasing costs There was a drawback of inviting.

The present invention has been made in view of the above-mentioned conventional drawbacks, and has been made in consideration of the above-mentioned drawbacks. It is an object to provide a fastening method of

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to insert a bush into a cylindrical bracket portion, and then reduce the diameter of the cylindrical bracket portion by electromagnetic forming and tighten the outer peripheral portion of the bush. The problem can be solved by a method of fastening the cylindrical bracket portion and the bush.

That is, in the method of the present invention, since the outer diameter of the bushing is tightened by reducing the diameter of the cylindrical bracket by electromagnetic forming, the inner peripheral surface of the cylindrical bracket can be finished with high dimensional accuracy. Thus, a firm fastening structure can be obtained without performing the cutting process, and the tubular bracket portion and the bush can be advantageously fastened in terms of cost. In particular, by using electromagnetic molding, it is possible to adjust the fastening force between the cylindrical bracket portion and the bush by changing the charging energy for molding, and it is easy to adjust the fastening force. Together with this, the reduction of the fastening cost is realized.

In the present invention, by using a cylindrical bracket having a concave and convex portion on the inner peripheral surface thereof, the concave and convex portion bites into the outer peripheral portion of the bush.
A more secure fastening state is obtained. In this case, it is preferable to use a bush whose outer peripheral surface is made of an elastic body such as rubber.

[0008]

Next, an embodiment of the method of the present invention will be described with reference to the drawings.

FIGS. 1 to 4 show a first embodiment. This embodiment relates to a method for fastening a tubular bracket portion and a bush in an automobile engine mount (1) as shown in FIG.
(3) is a bush.

First, a bush (3) and a bracket (2) are prepared as shown in FIG. The bush (3) has a circular cross-sectional outer peripheral shape and a rubber body (3
A liner (3b) made of a metal such as steel is provided integrally as an outer cylinder material on the outer peripheral portion of a).

The bracket (2) has an inner circular cylindrical bracket (2a) for holding the bush (3), and a protruding portion (2b) projecting laterally from the cylindrical bracket (2a). An extruded aluminum material cut by a predetermined length from an aluminum extruded material extruded including the hollow part in the cylindrical bracket part (2a). It is. The inner diameter of the cylindrical bracket (2a)
In order to ensure easy insertion of the bush (3), the bush (3) is designed to be larger than the outer diameter. In addition, the bracket (2) may be made of a cast product or a forged product, in addition to the product made of the extruded product.

Next, as shown in FIG. 2B, the bush (3) is inserted and arranged in the cylindrical bracket portion (2a). As described above, the inner diameter of the cylindrical bracket (2a) is
By being designed to be larger than the outer diameter of the bush (3), it can be easily inserted.

Thereafter, this is subjected to electromagnetic molding. As shown in FIG. 3, the electromagnetic molding uses an electromagnetic molded coil (4) for contracting a tube, and the cylindrical bracket portion (2a) of the bracket (2) is concentric with the coil (4). The magnetic flux concentrator (6) is arranged in a C-shape between the cylindrical bracket part (2a) and the coil (4) except for the protruding part (2b) of the bracket (2). Bracket (2)
An insulator (7) is arranged between both circumferential ends of the magnetic flux concentrator (6) corresponding to the protrusions (2b) of the
This is performed by applying an instantaneous large current to (4). Due to the application of the instantaneous large current, the magnetic flux concentrator (6) and the cylindrical bracket (2a) cause magnetic repulsion, and the magnetic repulsive force causes the cylindrical concentrator (6) and the cylindrical bracket (2a) to have a cylindrical shape as shown in FIGS. The diameter of the bracket portion (2a) is reduced, and the outer peripheral portion of the bush (3) is tightened, so that the cylindrical bracket portion (2a) and the bush (3) are fastened. Incidentally, in the above-mentioned automobile engine mound, when the charging energy E was set to 20 KJ and the electromagnetic molding was performed, the tubular bracket portion (2a) and the bush (3) were firmly fastened. As described above,
An engine mount (1) as shown in FIG. 1 is obtained.

As described above, in the above fastening method,
The bush (3) is inserted and arranged in the cylindrical bracket (2a), and the outer diameter of the bush (3) is tightened by reducing the diameter of the cylindrical bracket (2a) by electromagnetic molding. As in the fastening method by press fitting, it is possible to obtain a firm fastening structure without finishing the inner peripheral surface of the cylindrical bracket part with high dimensional accuracy by cutting, and the cylindrical bracket part (2a) and the bush (3) Can be fastened very advantageously in terms of cost. In particular, since the fastening is performed by electromagnetic molding, it is possible to adjust the fastening force between the cylindrical bracket portion (2a) and the bush (3) by changing the charging energy for the electromagnetic molding. It is possible to reduce the fastening cost.

In the second embodiment shown in FIG. 5, the bush (3) has a structure in which the outer peripheral liner is omitted and the outer peripheral surface is made of rubber. Others are the first
This is the same as the embodiment. As described above, by using the outer peripheral rubber structure as the bush (3), the bush (3) can elastically absorb the diameter reduction deformation of the cylindrical bracket portion (2a).

In the third embodiment shown in FIGS. 6 to 9, as shown in FIG. 7A, the outer peripheral liner is omitted as the bush (3), and the outer peripheral surface is made of rubber. Use something. In addition, bracket (2)
Is similarly provided integrally with a cylindrical bracket portion (2a) for holding the bush (3) and a protruding portion (2b) protruding laterally from the cylindrical bracket portion (2a). On the inner peripheral surface of the cylindrical bracket portion (2a), there are provided recesses and projections (5).

The concave / convex portion (5) has a structure in which concave and convex stripes extending in the axial direction are alternately arranged in the circumferential direction, and has a cross-sectional inner peripheral shape of the cylindrical bracket portion (2a). Has a wavy shape in the circumferential direction. The bracket (2) is made of a cut extruded material manufactured by cutting an aluminum extruded material formed by extrusion including the concave and convex (5) for cutting into predetermined length units. In addition to extruded products, cast products and forged products may be used.

Using the bush (3) and the bracket (2), as shown in FIG. 7B, the bush (3) is connected to the cylindrical bracket (2a) as in the first embodiment. 8), and as shown in FIG. 8, this is set in an electromagnetic forming apparatus, and an instantaneous large current is applied to the coil (4), as shown in FIGS. 9 (a) and 9 (b). Then, the outer diameter of the bush (3) is tightened by reducing the diameter of the cylindrical bracket (2a), and the cylindrical bracket (2a) and the bush (3) are fastened. As described above, the engine mount (1) as shown in FIG. 5 is obtained.

In the present embodiment, the cylindrical bracket portion (2a)
Since the inner peripheral surface of the bush (3) has the concave and convex portions (5), the concave and convex portions bite into the outer peripheral portion of the bush (3), and a very firm fastening state is obtained. In addition, since the bush has a structure in which the outer peripheral surface is made of rubber, the unevenness for biting (5)
However, the outer peripheral surface of the bush (3) is elastically deformed and bites deeply, so that a more secure fastening structure is realized.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made. For example, in the above-described embodiment, the fastening between the tubular bracket portion and the bush in the automobile engine mount is described, but in addition, the tubular bracket portion in various mounts and suspension arms, various rods, links, etc. It may be used for fastening with a bush. Further, the bush used in the method of the present invention may be any one provided with an elastic portion such as rubber, and the outer peripheral surface structure and the internal structure are not particularly limited, and may have various structures.

[0021]

As described above, according to the present invention, the method for fastening the cylindrical bracket portion and the bush is as follows. The bush is inserted and arranged in the cylindrical bracket portion, and then the cylindrical bracket portion is reduced in diameter by electromagnetic molding. At the very least, the outer periphery of the bushing is tightened, so that it is possible to obtain a firm fastening structure without finishing the inner peripheral surface of the cylindrical bracket portion with high dimensional accuracy by cutting. Can be fastened in terms of cost.

In particular, since the method is based on electromagnetic molding, it is possible to adjust the fastening force between the cylindrical bracket portion and the bush by changing the charging energy for molding, and to cope with the adjustment of the fastening force. Is very easy, and together with this, it is possible to reduce the fastening cost.

Moreover, since the diameter of the cylindrical bracket portion is reduced by electromagnetic molding, contact scratches for reducing the diameter are formed on the outer peripheral portion of the cylindrical bracket portion as in the case of pressing. And a good quality fastener can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment, in which FIG. 1A is a cross-sectional view of an engine mount as a fastening product, and FIG. 1B is a side view.

FIG. 2A is a cross-sectional view showing a bracket and a bush before fastening, and FIG. 2B is a cross-sectional view showing a state where the bush is inserted and arranged in a cylindrical bracket portion.

FIG. 3 is a cross-sectional view of a state set in an electromagnetic forming apparatus.

FIGS. 4A and 4B are cross-sectional views showing a state in which electromagnetic molding is being performed.

5A and 5B show a second embodiment, in which FIG. 5A is a cross-sectional view of an engine mount as a fastening product, and FIG. 5B is a side view.

FIG. 6 shows a third embodiment, wherein FIG. 6A is a sectional view of an engine mount as a fastening product, and FIG. 6B is a side view.

FIG. 7A is a cross-sectional view showing a bracket and a bush before fastening, and FIG. 7B is a cross-sectional view showing a state where the bush is inserted and arranged in a cylindrical bracket portion.

FIG. 8 is a cross-sectional view of a state set in the electromagnetic forming apparatus.

FIGS. 9A and 9B are cross-sectional views showing a state in which electromagnetic molding is being performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine mount 2a ... Cylindrical bracket part 3 ... Bush

Claims (1)

[Claims] A bush is inserted and arranged in a cylindrical bracket portion, and thereafter, the cylindrical bracket portion is reduced in diameter by electromagnetic molding and an outer peripheral portion of the bush is tightened. Fastening method.