JP3804885B2 - Bound stopper and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a bound stopper that is attached and fixed to, for example, an anti-vibration base such as a leaf spring of an automobile, or a vehicle body side frame on the top thereof, and a manufacturing method thereof.
[0002]
[Prior art]
The bound stopper is used to prevent the vibration-proof base such as a leaf spring from deforming beyond a certain limit or hitting the vehicle body side frame when the traveling automobile receives a very large impact. . Conventionally, as this type of bound stopper, one having a structure as shown in FIGS. 4 and 5 has been mainly employed.
[0003]
A bound stopper 100 of Conventional Example 1 shown in FIG. 4 includes a bottomed cylindrical bracket 101 and an inner rubber portion 102 accommodated therein, and a frustoconical outer rubber portion 103 from the opening of the bracket 101. And a rubber-like elastic body 104 from which is projected. In the bound stopper 100, a rubber adhesive is applied to the inner surface of the bracket 101 and the flange portion 105, the rubber-like elastic body 104 is filled, and the rubber-like elastic body 104 is firmly bonded and fixed by vulcanization.
[0004]
The bound stopper 106 of Conventional Example 2 shown in FIG. 5 is composed of a bottomed cylindrical bracket 107 and a substantially columnar rubber-like elastic body 108, and a rubber-like elastic body in which a plurality of lips 109 are formed in the lower step portion. The bounce stopper 106 was molded by a method in which 108 was previously vulcanized and pressed into the bracket 107.
[0005]
[Problems to be solved by the invention]
By the way, in the bound stopper 100 of the conventional example 1, since the rubber-like elastic body 104 is firmly vulcanized and bonded to the inner wall of the bracket 101 via the rubber adhesive, there is no fear of falling off due to vibration during vehicle travel. In its manufacture, complicated pretreatment steps such as shot blasting of the inner surface of the bracket 101, application of an adhesive, and surface coating are required, which has been a factor in increasing the product cost.
[0006]
Further, the bound stopper 106 of the conventional example 2 is not complicated to apply an adhesive to the inner surface of the bracket 107, but in addition to the step of pre-vulcanizing the rubber-like elastic body 108, the step of press-fitting into the bracket 107. Is required and requires two stages of equipment and work. In addition, since the rubber-like elastic body 108 is physically fixed to the bracket 107 using the lip 109 at the peripheral portion, the rubber-like elastic body 108 is caused by compression distortion, stress relaxation, etc. In some cases, the peripheral rubber portion was deteriorated and the holding force was reduced, and the peripheral rubber portion fell off from the bracket 107.
[0007]
The present invention has been made to solve the above-described problems of the conventional bound stopper, which simplifies the manufacturing process and reliably prevents falling out, and also has a desired non-linear spring characteristic. It aims at provision of the obtained bound stopper and a manufacturing method.
[0008]
[Means for Solving the Problems]
First, in order to simplify the manufacturing process, the present inventors focused on reducing the cost by eliminating the rubber adhesive and making it non-adhesive so that the pretreatment step before vulcanization can be omitted. did. However, if the rubber-like elastic body is not bonded to the bracket, there is a high possibility that the rubber-like elastic body will fall out of the bracket during use of the bound stopper, and this point will not change even as in the conventional example 2. Based on these findings, the inventors have intensively studied the shape of the bracket that can prevent the rubber-like elastic body from coming off even when the rubber-like elastic body is not bonded. As a result, it has been found that if the opening of the bracket is formed to have a smaller diameter than the inner diameter of the inner rubber accommodating portion, the inner rubber portion is held so as not to come out even in a non-bonded state with the inner wall of the accommodating portion. .
[0009]
When the rubber-like elastic body is accommodated in the bracket having such a shape, the manufacturing process can be simplified by vulcanizing and molding while keeping the unvulcanized rubber in the bracket, rather than putting the vulcanized rubber in the bracket. Is possible.
[0010]
In addition, when the rubber contained in the bracket is vulcanized, the inner rubber part and the bracket are not bonded, so that a gap is generated between the inner rubber part and the bracket due to the vulcanization shrinkage of the rubber. As a result, it has been found that the deflection of the inner rubber portion in the low load region is increased, and a non-linear spring characteristic capable of satisfactorily reducing the impact in the low load region can be obtained, and the present invention has been completed.
[0011]
That is, the present invention forms the opening of the bracket with a smaller diameter than the inner diameter of the accommodating portion, accommodates the inner rubber portion of the rubber-like elastic body in an unbonded state with the inner wall of the accommodating portion, and prevents the rubber from being removed. Using a rubber contraction after vulcanization molding of a cylindrical elastic body, a configuration is adopted in which a gap is formed between the peripheral edge of the inner rubber part and the inner wall surface of the bracket to obtain nonlinear spring characteristics. is there.
[0012]
In this case, the shape of the bracket only needs to be narrowed so that the opening has a smaller diameter than the inner diameter of the housing portion, and as the shape of the housing portion, for example, a barrel shape, a truncated cone shape, etc. Any shape can be used. The truncated conical shape is preferable in that a gap is easily formed between the bottom side peripheral edge of the inner rubber portion and the bottom inner wall of the housing portion, and it is easy to bend in a low load region. Moreover, the presence or absence of the flange in the opening part of a bracket does not ask | require.
[0013]
The inner rubber part of the rubber-like elastic body preferably has a shape that matches the shape of the bracket housing part. In this case, transfer molding or injection molding can be used, which simplifies the manufacturing process. Achieved.
[0014]
The shape of the outer rubber portion may be set in accordance with desired spring characteristics, and the shape is not limited to a conical shape, and may be a cylindrical shape, a truncated cone shape, or the like. At that time, when the flange is formed on the periphery of the opening of the bracket, the diameter of the bottom of the outer rubber part is made larger than the diameter of the opening, and the bottom surface is received by the surface of the flange. The pressure receiving area can be increased, and local fatigue of the rubber near the opening caused by repeated vibration during use is also reduced, which is preferable.
[0015]
Since the gap formed between the inner rubber part and the inner wall of the bracket housing part is usually about 1 to 3% after rubber vulcanization, it is relatively easy to use this phenomenon. It can be formed. By forming this gap, as shown in the load-deflection curve of FIG. 3, a non-linear spring characteristic with a large amount of deflection in the low load region can be easily obtained as compared with the spring characteristic of Conventional Example 1.
[0016]
A method of manufacturing this bound stopper will be described by taking a bounce stopper having a truncated cone shape as an example. A bracket formed in a truncated cone shape is used, and a rubber adhesive is applied to the accommodated portion. And filling the unvulcanized rubber into an inner rubber part, and forming the outer rubber part by raising the unvulcanized rubber up to the top of the flange formed at the peripheral edge of the opening. A rubber-like elastic body composed of the outer rubber portion and the outer rubber portion is vulcanized and molded so that a gap is formed between the inner rubber portion and the inner wall of the housing portion by shrinking the rubber after vulcanization.
[0017]
Embodiment
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a bound stopper when filled with unvulcanized rubber according to the present invention, and FIG. 2 is a cross-sectional view of the bound stopper after vulcanization shrinkage of a rubber-like elastic body.
[0018]
As shown in the figure, the bound stopper 1 is composed of a rubber-like elastic body 2 and a bottomed cylindrical bracket 5 having an accommodating portion 4 in which an inner rubber portion of the rubber-like elastic body 2 can be accommodated. The shaped elastic body 2 is composed of an inner rubber portion 6 housed in the bracket 5 and an outer rubber portion 8 that protrudes outward and upward from the opening 7 of the bracket 5 continuously to the inner rubber portion. Has been.
[0019]
As a material of the rubber-like elastic body 2, natural rubber or synthetic rubber generally used for vibration-proof rubber, for example, SBR (styrene butadiene rubber), BR (butadiene rubber), IR (isoprene rubber), NBR (Acrylonitrile butadiene rubber), CR (chloroprene rubber), IIR (butyl rubber), EPDM (ethylene propylene rubber), urethane elastomer or the like is used. These raw rubbers contain compounding agents such as vulcanizing agents, vulcanization accelerators, anti-aging agents, reinforcing agents, fillers, softeners, etc., and predetermined elastic modulus, mechanical strength, dynamic characteristics, fatigue characteristics, etc. To get.
[0020]
The bracket 5 has a bottomed cylindrical shape made of metal having an accommodating portion 4 inside, and the opening 7 has a smaller diameter than the inner diameter of the bottom surface portion 11 of the accommodating portion 4 that accommodates the inner rubber portion 6. Thus, the accommodating portion 4 is formed in a truncated cone shape, and a flange portion 10 that extends outward is formed on the periphery of the opening portion. An outer rubber portion 8 is also placed on the upper side of the flange portion 10, and the outer rubber portion 8 is formed in a truncated cone shape.
[0021]
Bolt holes 12 are formed in the bottom surface portion 11 of the bracket 5 as attachment means for fixing the bound stopper 1 to a vehicle body side frame (not shown). It is designed to be fastened and fixed.
[0022]
Next, a manufacturing method of the bound stopper 1 will be described. The housing portion 4 of the bracket 5 is filled with unvulcanized rubber without using a rubber adhesive to form the inner rubber portion 6. The vulcanized rubber is raised up to the upper portion of the peripheral flange portion 10 of the opening 7 of the bracket 5 to form a frustoconical outer rubber portion 8. Next, the unvulcanized rubber-like elastic body 2 is vulcanized and molded, and a gap for obtaining a non-linear spring characteristic between the inner rubber portion 6 and the inner wall of the housing portion 4 due to rubber shrinkage after vulcanization. 14 is formed.
[0023]
This gap 14 is formed by rubber contraction after vulcanization of the rubber-like elastic body 2. However, when the inner rubber portion 6 is filled in accordance with the accommodation portion 4 as in the present embodiment, the shape of the accommodation portion 4 is obtained. From the relationship between the rubber shrinkage rate and the rubber shrinkage rate, the gap amount at the bottom peripheral edge 15 of the inner rubber portion 6 is the largest, becomes narrower as it approaches the opening 7, and becomes almost zero at the opening 7. For example, when the unvulcanized rubber is filled in the accommodating portion 4 having a maximum diameter of 50 mm and vulcanized and molded, the gap amount differs depending on the rubber shrinkage rate. For example, the bottom peripheral edge 15 of the inner rubber portion 6 and the accommodating portion 4. Is approximately 1 mm in diameter.
[0024]
Thus, since the gap | interval amount in the bottom part peripheral part 15 of the inner rubber part 6 becomes the largest, the amount of bending becomes large in a low load region. This spring characteristic will be described using the load-deflection curve of FIG. 3. In the figure, A represents the spring characteristic of the present embodiment, and B represents the spring characteristic of Conventional Example 1.
[0025]
When a load is applied from the upper side of the outer rubber portion 8 of the bound stopper 1, there is a gap 14 between the peripheral portion 15 of the inner rubber portion 6 and the accommodating portion 4 as shown in FIG. In the low load region until the peripheral edge 15 of the portion 6 abuts against the inner wall surface of the housing portion 4 of the bracket 5, the amount of bending is larger than that in the case B of the conventional example 1, and it is conventional from the middle load region to the high load region. A similar non-linear curve will be drawn.
[0026]
【The invention's effect】
As is clear from the above description, according to the present invention, the opening of the bracket is formed with a smaller diameter than the inner diameter of the housing portion, and the inner rubber portion of the rubber-like elastic body is not bonded to the inner wall of the housing portion. Bound stopper is in use because it is housed in a state where it cannot be pulled out and a gap is formed between the peripheral edge of the inner rubber part and the inner wall surface of the bracket using the rubber shrinkage after vulcanization molding of the rubber-like elastic body. The rubber-like elastic body can be prevented from slipping out, and the rubber-like elastic body is not required to be bonded. Therefore, the cost can be reduced by reducing the number of steps. Furthermore, since a gap is formed between the inner rubber portion and the bracket housing portion due to the rubber vulcanization shrinkage, the amount of bending in the low load region is large, and a good spring characteristic is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a bound stopper when an unvulcanized rubber is filled according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the bound stopper after vulcanization shrinkage of a rubber-like elastic body. FIG. 4 is a cross-sectional view of the bound stopper of the conventional example 1. FIG. 5 is a cross-sectional view of the bound stopper of the conventional example.
DESCRIPTION OF SYMBOLS 1 Bound stopper 2 Rubber-like elasticity 4 Housing part 5 Bracket 6 Inner rubber part 7 Opening part 8 Outer rubber part 10 Flange part 14 Clearance 15 Bottom peripheral part

Claims (4)

A bottomed cylindrical bracket having an accommodating portion capable of accommodating an inner rubber portion of a rubber-like elastic body, an inner rubber portion accommodated in the bracket, and the inner rubber portion. In a bound stopper comprising a rubber-like elastic body composed of an outer rubber portion protruding outward from the opening of the bracket,
The opening of the bracket is formed to have a smaller diameter than the inner diameter of the housing portion, and the inner rubber portion of the rubber-like elastic body is housed in an unbonded state with the inner wall of the housing portion so that it cannot be pulled out. Bound stopper characterized in that a gap for obtaining a non-linear spring characteristic is formed between the peripheral edge portion of the inner rubber portion and the inner wall surface of the bracket by utilizing the rubber shrinkage after vulcanization molding of . The housing portion of the bracket is formed in a truncated cone shape in which the opening is smaller in diameter than the bottom surface portion of the housing portion, and the gap is at least between the bottom side peripheral portion of the inner rubber portion and the housing portion. The bound stopper according to claim 1 formed. The bound stopper according to claim 1 or 2, wherein a flange for receiving a lower portion of the outer rubber portion is formed at a peripheral edge of the opening portion, and the outer rubber portion is formed in a truncated cone shape. By forming the opening with a smaller diameter than the bottom surface, the inner rubber part can be filled with unvulcanized rubber without using rubber adhesive in the bracket housing part formed in a truncated cone shape. And forming an outer rubber part by raising the unvulcanized rubber to the upper part of the flange formed at the periphery of the opening, and a rubber-like elastic body composed of the inner rubber part and the outer rubber part. A method for manufacturing a bound stopper, characterized by forming a gap for obtaining a non-linear spring characteristic between an inner rubber portion and an inner wall of a housing portion by vulcanization molding and rubber shrinkage after vulcanization.

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