JP2002323080A - Tubular bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a ratio of wrenched rigidity and rigidity in the shaft direction larger in a suspension bush, and to prevent wrinkles of an outer cylinder metal fixture or cracking of the metal fixture generated at the time of intensive pressurizing working. SOLUTION: A spherical part 21A is provided at a central part of an inner cylinder metal fixture 21, and the outer cylinder metal fixture 22 is arranged in spaced apart concentrically so as to face it. The thickness of the vicinity of both end edge parts of the outer cylinder metal fixture 22 is reduced beforehand toward the edge parts, a bent part 22A can be formed approximately rectangularly by executing the intensive pressurizing working to the vicinity of the both end edge parts, and the ratio of the wrenched rigidity and rigidity in the shaft direction can be made larger since the rubber elastic body 23 and the bent part 22A are brought into pressure contact. Furthermore, the wrinkles or the cracking of the metal fixture are not generated at the bent part 22A after the intensive pressurizing working since the thickness of the vicinity of the both end edge parts is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension bush that is press-fitted into, for example, a suspension arm for an automobile and is used by being fitted and arranged.

[0002]

2. Description of the Related Art Conventionally, two functions have been required as functions required in a suspension bush of an automobile, namely, improvement of ride comfort and improvement of steering stability.
Generally, when a vehicle travels on an uneven road surface, the tires move up and down. As means for smoothing the vertical movement and not deteriorating the riding comfort, it is known to reduce the rigidity of the bush in the twisting direction. On the other hand, when the vehicle turns a curve, the vehicle largely moves left and right, and the steering stability is unstable. As means for avoiding this, it is known to increase the rigidity of the vehicle in the left-right direction, and it is known to increase the rigidity of the bush in the axial direction. That is, in order to improve both ride comfort and steering stability, it is required to increase the ratio of the twisting rigidity of the bush to the axial rigidity.

[0003] Forms for this purpose have conventionally been presented. For example, in a cylindrical bush 1 as shown in FIG. 6, an inner cylindrical fitting 2 as an inner axial fitting and an outer cylindrical fitting 3 as an outer cylindrical fitting arranged axially and concentrically with the inner cylindrical fitting 2. These metal fittings are integrally vulcanized and formed by a rubber elastic body 4 and are connected to each other. The inner cylindrical member 2 has a cylindrical shape extending in the axial direction and having the same thickness. The inner cylindrical member 2 is located at a substantially central portion of the inner cylindrical member, and includes a substantially spherical spherical portion 2A which is formed outwardly. Have one. The outer cylinder fitting 3 is provided with a tapered portion 3A that is bent toward the inner cylinder fitting 2 by a predetermined amount in the vicinity of both end edges. This bending method can be formed by subjecting the vicinity of both end edges to high pressure processing. First, as shown in FIG. 8 and FIG.
A forming part 11B which is equally divided into two and has a space on the inner peripheral side to reduce the diameter of the outer cylindrical member 3, and a block taper which is inclined at an angle θ with the forming part 11B to form a tapered part 3A of the outer cylindrical member 3. Dice blocks 11 and 11 provided with a portion 11A are prepared. Next, as shown in FIG. 7, first, the die blocks 11, 11 are arranged on the base 12 with a small gap therebetween, and the cylindrical bush 1 is arranged on the inner peripheral surface side. Next, when the press pressing unit 13 is pressed downward from above, as the pressing inclined unit 13A moves downward, there is a gap between the die blocks 11, 11.
Sliding occurs between 1C and the pressurized inclined portion 13A. Then, an inward force acts on the die blocks 11, 11, and the die blocks 11, 11 move inward. Thereafter, the die blocks 11, 11 move inward until the gap between the die blocks 11, 11 disappears, and the outer peripheral surface of the outer cylinder 3 is reduced in diameter by the forming portion 11B so that a desired outer diameter can be formed. At the same time, a taper portion 3A as shown in FIG. 6 is formed by a block taper portion 11A, which is bent in a tapered shape toward the inner cylinder fitting 2 over a predetermined amount in the vicinity of both end portions of the outer cylinder fitting 3. It is done. As a result, the main rubber elastic body 4 is provided with a constricted portion 4A narrowed by the spherical portion 2A of the inner cylinder and the tapered portion 3A of the outer cylinder 3. In addition, a gap 5A is formed between the tapered portion 3A and the narrowed portion 4A. Further, when the vehicle is assembled, the cylindrical bush 1 is press-fitted with an outer cylindrical member 3 into a suspension arm (not shown) made of iron and having an inner hole, and the both end surfaces 2B, 2C of the inner cylindrical member 2 are connected to the left and right of the vehicle. And is fastened to the vehicle via a bracket (not shown). The outer tube fitting 3 press-fitted to the arm is arranged via the rubber connector 4 in the vehicle vertical direction.

[0004] By taking the form shown in FIG.
When the one end surface 2B of the inner cylindrical member 2 approaches the tapered portion 3A provided on the outer cylindrical member 3, that is, in the twisting direction (ω direction in FIG. 6).
When the inner metal fitting 2 moves in the direction shown in FIG.
As A moves, the rigidity gradually increases due to the spherical shape of the spherical portion 2A. That is, the prying rigidity does not suddenly increase. When the inner cylindrical member 2 moves in the axial direction (Y direction in FIG. 6), the tapered portion 3A and the spherical portion 2A of the outer cylindrical member 3 come closer to each other, and the constricted portion 4A is gradually compressed. Therefore, the rigidity in the axial direction becomes harder.

[0005]

However, in the cylindrical bush 1 of the conventional embodiment shown in FIG. 6, since the tapered portions 3A are provided at both ends of the outer metal fitting 3, the gap 5A is provided.
Will occur. For this reason, when the inner cylinder 2 moves in the axial direction, the tapered portion 3A and the spherical portion 2A approach each other, but the presence of the gap 5A causes the narrowed portion 4A to move at the same time as the inner cylinder 2 moves. Do not receive compression. For this reason, the initial rigidity in the axial direction is soft, and it is difficult to increase the ratio between the twisting rigidity and the rigidity in the axial direction from the beginning. Further, in order to eliminate the gap 5A, if the rubber elastic body 4 is extended to both ends of the outer cylindrical metal fitting before the high-pressure processing and a new constricted portion 4A is provided, the vicinity of both ends is strongly pressed and the tapered portion 3A is formed. Is provided, when providing the tapered portion 3A,
A large strain is applied to the constricted portion 4A, so that the rubber elastic body 4 is easily cracked at the end of the constricted portion 4A and the end of the tapered portion 3A, which causes a serious problem in durability. Further, when the predetermined bending amount of the tapered portion 3A is further increased, the inclination angle θ provided in advance in the block tapered portion 11A shown in FIG.
In this case, the amount of swelling of the outer surface of the metal fitting generated at the time of bending becomes large, and the metal fitting is easily wrinkled or broken on the surface of the tapered portion 3A. In addition, since a gap is provided between each of the die blocks 11 and 11 divided into eight equal parts or twelve equal parts, and processing is performed, by increasing the amount of bending, metal wrinkles easily enter the gaps, and Block 1
1, 11 may be damaged.

The present invention has been devised in view of the above situation, and increases the ratio of twisting rigidity to axial rigidity from the beginning, and reduces the diameter of the outer cylindrical fitting and bends the vicinity of both end edges. It is an object of the present invention to provide a bush that can prevent damage to the outer sleeve.

[0007]

A first aspect of the present invention for solving the above-mentioned problems is to form a substantially spherical shape outward on a peripheral surface of a cylinder extending in the axial direction. An inner shaft fitting having one spherical portion, and a cylindrical outer tube fitting which is axially opposed to the spherical portion and is concentrically spaced apart from the inner shaft fitting. ,
In a cylindrical bush, which is connected by an elastic body so as to cover the spherical portion, and a predetermined amount of the vicinity of both end edges of the outer tubular metal fitting is bent toward the inner shaft fitting, both ends of the elastic body are the outer It is extended to the vicinity of both ends of the cylindrical fitting, and the vicinity of both ends of the outer cylindrical fitting is bent at a substantially right angle toward the inner shaft fitting by high pressure processing, and with respect to both ends of the elastic body. It is characterized by being pressed. In the cylindrical bush having such a structure according to the present aspect, since the elastic body is provided up to the vicinity of both ends of the outer cylindrical fitting, the vicinity of both ends of the outer cylindrical fitting is substantially directed toward the inner shaft fitting. If the elastic body is bent at high pressure and bent at right angles, the elastic body is sandwiched in the axial direction from both ends in the vicinity of the edge of the outer tube fitting. Further, the elastic body is constricted between the spherical portion formed outward and the vicinity of the bent both end edges on the outer peripheral surface of the inner shaft bracket, and the inner shaft bracket is axially moved. When it moves, the vicinity of both edges bent substantially at right angles becomes a wall, and the elastic body is compressed and the rigidity in the axial direction increases. Furthermore, since the vicinity of both ends of the outer cylindrical metal fitting is in pressure contact with the elastic body from the beginning, there is no gap between the elastic body and the vicinity of both ends. For this reason, at the same time as the inner shaft fitting moves in the axial direction, the elastic body is compressed, so that the rigidity in the axial direction becomes harder than the initial stage. Further, when the inner shaft fitting moves in the twisting direction, the inner shaft fitting has a spherical portion, so that the rigidity does not suddenly increase. In other words, by adopting this aspect, the desired ratio of the twisting rigidity and the axial rigidity of the cylindrical bush can be increased from the initial stage, and when the bush of this aspect is assembled to a vehicle, the riding comfort and steering stability are improved. Both sexes will be satisfied.
Further, since there is no gap between the elastic member and the vicinity of both ends of the outer cylindrical metal member and the elastic member is pressed, the rigidity in the axial direction does not vary and a stable one can be obtained.

[0008] A second aspect of the present invention is characterized in that the thickness of the outer cylindrical metal fittings near both edges is reduced toward the edges. In such a tubular bush, since the thickness near the both end edges of the outer sleeve is reduced toward the edge, when the edge vicinity is strongly pressed and bent, it is provided on the block taper portion. Even if the inclination angle θ is increased, the metal fittings near the both end edges of the outer cylindrical metal fitting are hard to bulge, and wrinkles and metal fittings can be prevented, and further bent at a substantially right angle toward the inner shaft metal fitting. It is possible to do. In addition, since it is difficult for the metal fittings near the both ends of the outer cylindrical metal to bulge, even if a gap is provided between the die blocks during the high-pressure processing, the metal fittings do not wrinkle between the die blocks and the die block. Is not damaged, and the product becomes stable in production. In addition, the thickness of the outer cylinder is 1.2 mm to 3 mm in consideration of the strength after processing.
Is preferred. If it is less than 1.2 mm, the rigidity of the bracket is insufficient, and if it is more than 3 mm, the pressure for bending the bracket increases, and the processing may be insufficient. In addition, it is preferable to reduce the thickness in the vicinity of both end edges of the outer cylindrical metal fitting in a tapered state toward the edge preferably over 5 to 10 mm. If it is 5 mm or less, wrinkles remain in the metal fitting when bent, and if it is 10 mm or more, the thickness itself of the metal fitting is excessively reduced and the strength is weakened. Further, the thickness of both end portions of the outer cylindrical metal fitting is 1 mm or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cylindrical bush (hereinafter, referred to as a bush) 20 applied to a suspension for an automobile according to an embodiment of the present invention. In the bush 20, an inner cylindrical metal member 21 as an inner shaft metal member and an outer cylindrical metal member 22 as an outer cylindrical metal member are integrally vulcanized by a rubber elastic body 23 and are connected to each other. Outer tube fitting 22
Is press-fitted into a suspension arm E made of iron in the vertical direction of the vehicle. The suspension arm E is connected to a tire (not shown) via a ball joint (not shown) arranged at the tip of the arm. The inner tube fitting 21 is fixed to the left and right direction of the vehicle with a pointing bolt D via brackets F made of iron at both ends. The bracket F is attached to a vehicle body (not shown), so that the bush 20 connects the tire and the vehicle body with vibration isolation.

More specifically, the inner cylindrical member 21 has a cylindrical shape having the same thickness, and a substantially spherical portion 21A is formed outward in a substantially central portion of the outer peripheral portion. I have. This spherical part can be formed by swaging or bulging a cylindrical pipe. The material is STKM
Molded using materials. A similar shape can be formed by cold forging, in which case S10C material is used.

As shown in FIG. 1, the outer cylindrical member 22 is axially opposed to a spherical portion 21A provided on the inner cylindrical member 21 and is concentrically spaced apart from the inner cylindrical member 21. The part is composed of a flat fitting portion 22C and a bent portion 22A obtained by bending the vicinity of both end portions at substantially right angles by a high-pressure processing method to be described later. The diameter has been reduced. The axial length of the outer cylindrical member 22 is slightly longer than the spherical portion 21A of the inner cylindrical member, is substantially the same as the axial length of the suspension arm E, and is located at the inner peripheral surface of the suspension arm E. It is press-fitted with an interference. The bent portion 22A is connected to the fitting portion 22C at a corner R portion 25 formed by bending the bent portion 22A.
Extends to a position substantially the same as the outermost diameter of the spherical portion 21A, and the thickness of the bent portion 22A decreases from the corner R portion 25 toward the edge as shown in FIG. I have.

The rubber elastic body 23 is vulcanized and bonded to the inner cylinder 21 so as to cover the spherical portion 21A of the inner cylinder 21. Both ends of the rubber elastic body 23 are extended from the inner peripheral surface of the bent portion 22A in a direction substantially perpendicular to the axis toward the inner cylinder fitting 21, and a concave portion 24A facing the spherical portion outside the spherical portion 21A is provided. It is vulcanized and adhesively molded with the metal fitting 21. Furthermore, inner cylinder fitting 2
A thin rubber elastic film is formed from the end of the recessed portion 24A on the surface of 1 and extends to the periphery of both edges. The outer tube fitting 22 is vulcanized and bonded only to the inner peripheral surface of the fitting portion 22C, is sandwiched from both ends by the bent portion 22A, and is compressed from the bent portion 22A from the beginning. .
Further, the outermost diameter of the spherical portion 21A provided on the inner cylinder 21 and the position of the edge of the bent portion 22A (in the direction of the inner cylinder 21).
Are substantially the same, the rubber elastic body 23 has the bent portion 2
A constricted portion 23A sandwiched between the spherical portion 2A and the spherical portion 21A is provided. Here, the inner tube fitting 21 is in the axial direction (Y in FIG. 1).
Direction), a compressive force is applied to the constricted portion 23A sandwiched between the spherical portion 21A and the bent portion 22A from the initial stage, so that the axial rigidity becomes harder than the initial stage. . When the inner cylinder 21 is inclined in the twisting direction (the direction of ω in FIG. 1), the surface of the spherical portion 21A is spherical, and the concave portion 24A is provided outside the spherical portion 21A. The body is initially soft, gradually becoming harder, and does not suddenly become harder. That is, the torsional rigidity does not become hard from the beginning.

This bush 20 is shown in FIG.
As shown in (b) and (c), it is manufactured by sequentially performing a preparation step (a) and a taper drawing step (b) and a caulking step (c), which are high-pressure processing steps. First, in the preparation step, as shown in FIG.
1, the outer cylindrical fitting 32 whose thickness near the both end edges of the outer peripheral surface is reduced toward the edge, and both ends of the rubber elastic body 23 extend to near the both end edges 32A of the outer cylindrical fitting 32. And an intermediate product A in which the metal fittings are vulcanized and bonded is prepared. In the intermediate product A, according to FIG.
Since both ends of the rubber elastic body 23 are formed by vulcanization bonding with the inner peripheral surface near the both ends 32A and a small recess 25, the vicinity 32A of both ends of the outer cylinder is strongly pressed. Even if the bent portion 22A is formed, no large distortion is generated in the rubber elastic body 23.

The next taper drawing step is described earlier with reference to FIG.

Item) Not shown because it is the same as the processing method. FIG. 3B shows the configuration after the taper drawing step. In order to form this form, first, a die block divided into eight equal parts or twelve equal parts having a block taper part set so as to obtain a desired taper part 42A on a base is opened with a gap. Deploy. Then, the intermediate body A shown in FIG. 3A is arranged with a space left on the inner peripheral surface of the die block. Thereafter, the press-pressing portion is disposed on the die block, and the press-pressing portion is pressed downward, so that a tapering process is performed on the vicinity 32A of both end edges in a tapered shape. The surface is reduced in diameter by a predetermined amount, and a tapered portion 42A in which the thickness of the outer peripheral surface decreases toward the edge is formed, and the secondary intermediate product B shown in FIG.
To form Here, since the outer peripheral surface of the outer metal fitting is reduced in diameter, the both ends of the rubber elastic body slightly bulge around the vicinity 32A of both ends, and are finally pressed against the bent portion 22A. The inclination angle θ of the block taper portion provided in the die block is set to an angle that makes it easier to bend the taper portion 42A in the next caulking step, and is preferably 30 ° to
It is set to 50 °.

The next caulking step is performed by substantially the same processing method as the taper drawing step. FIG. 4 shows a processing method.
First, the secondary intermediate product (B) is placed on the base 52, and eight or twelve equally divided die blocks 51, 51 each having a gap so as to surround the outer peripheral surface of the outer tube fitting 42 are placed. . In the die block 51, a forming part 51B provided in parallel with the inner peripheral side along the direction perpendicular to the axis, and a caulking part 5 provided along the axial direction at an angle substantially perpendicular to the forming part.
1A. The outer peripheral surface is provided with a dice block inclined portion 51C which is inclined obliquely. Since the pressurizing portion 53 is provided with the pressurizing inclined portion 53A on the inner peripheral surface thereof, when the pressurizing portion is pressed downward in the state of being arranged as shown in FIG. Dice block 5
1 moves inward. The tapered portion 42A is
Caulking part 51A provided smaller than the edge of 2A
The pressure is gradually increased, and finally the tapered portion 42A is pushed into the caulked portion 51A. More specifically, as shown in FIG. 5, the tapered portion 42A is pressed against the inner peripheral surface of the caulked portion 51A and is bent to form a bent portion 22A. Here, the forming part 5 provided in the die block 51
Since 1B is in pressure contact with the outer surface of the outer cylindrical member 42, the corner R portion 25 is formed in the outer cylindrical member 42 by the swaged portion 51A. At this time, since the tapered portion 42A is pressed against the caulked portion 51A and bent to form the bent portion 22A, the thickness of the bent portion 22 is from the corner R portion 25 to the edge of the inner peripheral surface of the bent portion 22A. It will decrease. And FIG. 3 (C)
Bush 20 having bent portions 22A at both ends of the outer cylinder fitting shown in FIG.
It is in the form of

Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention can be applied to various types of cylindrical bushes without departing from the gist of the present invention. Various modifications can be made based on the knowledge of the above. For example, in the present embodiment, the bent portion 2
Although the length of 2A is the same at both ends, it is of course possible to change the length according to the demands of the vehicle and to mold it, and the thickness of the inner peripheral surface near the both end edges of the outer cylinder is defined as the edge. It is, of course, possible to decrease it.

[0018]

As is clear from the above description, in the tubular bush having the structure according to the present invention, the thickness of the outer cylindrical fitting near the both end edges is reduced, so that the product is free from wrinkles or cracks in the fitting. It is possible to bend both ends of the outer cylindrical fitting substantially at a right angle without causing any damage to the manufacturing equipment. Furthermore, since the bent portions at both ends generated after bending compress the rubber elastic body in advance, the rigidity in the axial direction is hardened from the beginning, and by providing a spherical portion in the inner cylindrical metal fitting, the twisting direction is improved. The rigidity does not become harder than the initial.
In other words, the ratio of torsional rigidity to axial rigidity can be increased, and both riding comfort and steering stability can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing a vehicle suspension bush as an embodiment of the present aspect.

FIG. 2 is a detailed view of a bent portion in FIG.

FIG. 3 is an explanatory diagram showing a form of a bush after a preparation process of the embodiment product and a high-pressure working process.

FIG. 4 is an explanatory view showing a caulking step of the product of the present embodiment.

FIG. 5 is a detailed view showing a relationship between a caulked portion and a bent portion in FIG. 4;

FIG. 6 is an explanatory longitudinal sectional view showing one example of a conventional example.

FIG. 7 is an explanatory view showing a conventional high-pressure processing step.

FIG. 8 is an explanatory diagram of a die block used when performing high-pressure processing.

FIG. 9 is a sectional view taken along the line II in FIG. 8;

[Explanation of symbols]

 Reference Signs List 20 bush 21A spherical part 22A bent part 32A near edge 42A taper part 51 die block 51A caulking part 51B molding part

Claims (2)

[Claims] 1. An inner shaft fitting having a spherical portion outwardly formed in a substantially spherical shape on an outer peripheral surface of a cylinder extending in an axial direction, and an inner shaft metal fitting facing the spherical portion in an axial direction. It has a cylindrical outer tube fitting concentrically spaced apart from the inner shaft fitting, and these fittings are connected by an elastic body so as to cover the spherical portion, and a predetermined amount is provided near both ends of the outer tubular fitting. In the cylindrical bush bent toward the inner shaft fitting, both ends of the elastic body are extended to near both ends of the outer tubular fitting, and both ends of the outer tubular fitting are near. A cylindrical bush that is bent at a substantially right angle toward the inner shaft fitting by high-pressure processing, and is pressed against both ends of the elastic body. 2. The cylindrical bush according to claim 1, wherein the thickness of the outer cylindrical fitting near both end edges decreases toward the edge.