JP4171095B2 - How to squeeze the outer cylinder of the rubber bush - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for squeezing an outer cylinder of a rubber bush that is press-fitted into a cylinder part of a connecting part such as a suspension arm of an automobile.
[0002]
[Prior art]
A rubber bush 100 as an anti-vibration rubber is mainly used for elastically supporting each connecting portion such as a suspension of an automobile, and is generally inserted into a metal vehicle side bracket as shown in FIG. An inner cylinder 101 as a shaft member, an outer cylinder 104 disposed around the inner cylinder 101 and press-fitted into the connecting cylinder 103 of the suspension arm 102, and interposed between the inner and outer cylinders 101, 104, and vulcanized into the inner and outer cylinders. And a rubber-like elastic body 105 bonded thereto.
[0003]
The rubber bush 100 with the outer cylinder is drawn into the outer cylinder 104 in the direction of diameter reduction for the purpose of taking the rubber contraction of the rubber-like elastic body 105 after the rubber vulcanization adhesion and improving the durability of the rubber. Is applied to the connecting cylinder 103.
[0004]
[Problems to be solved by the invention]
By the way, when the rubber bush is press-fitted into the connecting cylinder, the press-fitting allowance increases, and when the press-fit load exceeds 3 ton, in the case of the bush with the outer cylinder flange, the flange is deformed (bent) at the time of press-fitting, resulting in poor press-fitting. In addition, the capacity limit value of the press-fitting machine is exceeded regardless of whether it is a straight pipe type or a rubber bush with an outer cylinder flange.
[0005]
On the other hand, the pull-out load from the connecting cylinder of the rubber bush is set to a minimum of 0.5 ton from the track record. When the outer cylinder is not plastically deformed by press-fitting, the relationship between the pull-out load and the press-fitting load is the removal load ≧ the press-fitting load, and the press-fitting load is 0.5 ton or more and 3 ton or less.
[0006]
In general, as shown in FIG. 7, the press-fitting allowance during press-fitting is set to about φd−φD = 0.05 mm to 0.4 mm (where φd is the outer diameter of the outer cylinder, φD is the inner diameter of the connecting cylinder). If this is the case, the press-fitting load of the rubber bush 100 is MAX 3 ton or less, the removal load can be 0.5 ton or more, and the press-fitting of the rubber bush is within the capacity range of the press-fitting machine and without deformation of the outer cylinder flange. It becomes possible.
[0007]
Therefore, conventionally, in order to ensure the above-described press-fit load and removal load at predetermined values, the dimensional tolerance of the outer diameter of the rubber bush and the dimensional tolerance of the inner diameter of the cylinder portion of the mating member such as the connecting cylinder are set small. In order to satisfy this, the inner surface of the connecting cylinder has been subjected to cutting or the like.
[0008]
However, recently, with a reduction in manufacturing cost and the like, the connecting cylinder such as the suspension arm has been made into a wound pipe or less processing, and the tolerance of the inner diameter of the connecting cylinder has increased. Therefore, when a rubber bush is press-fitted into such a connecting cylinder, it has become difficult to set the press-fitting allowance as described above. The advent of a rubber bush that can be optimized with the above is desired.
[0009]
[Means for Solving the Problems]
As a result of diligent research to provide a rubber bush that immediately responds to the current situation as described above, the present inventors have found that protrusions projecting radially outward at a plurality of locations on the outer peripheral surface of the outer cylinder are formed on the shaft member such as the inner cylinder. By forming along the axial direction, the contact with the inner surface of the connecting tube portion of the counterpart member is mainly performed by a convex strip, and the inner diameter of the counterpart member is adjusted by adjusting the contact area of the convex strip with the counterpart member. Even when the dimensional tolerance increases, the rubber bush can be incorporated with a press-fit load of a predetermined value or less.
[0010]
Therefore, even if the inner diameter of the connecting cylinder portion of the counterpart member such as the suspension arm is small and the press-fitting allowance is large, the ridge can be deformed to the outer cylinder cylinder surface located on the inner diameter side than that, The press-fit load can be controlled.
[0011]
The protrusions in this case may be any shape that can be deformed to the cylindrical surface side of the outer cylinder at the time of press-fitting into the counterpart member. For example, the thickness difference from the cylindrical surface of the outer cylinder may be questioned. In addition, the formation time is not limited before and after the drawing process, and whether or not the drawing process is performed. However, if a ridge is applied when a thin outer cylinder of uniform thickness is squeezed in the circumferential direction, it will be possible to control the press-fit load while improving the durability of the rubber-like elastic body. It can be said that it is a suitable aspect.
[0012]
Further, the axial formation position of the ridges can be adopted at any position in the axial direction of the outer cylinder or over the entire length in the axial direction, but it is possible to press-fit the mating member into the connecting cylinder part. In consideration of easiness, a configuration in which ridges are formed except for the press-fitting side end is preferable.
[0013]
In addition, the number of protrusions in the circumferential direction of the outer cylinder is not limited as long as it is plural, and the circumferential width of each protrusion and the circumferential width of the outer cylinder surface between them are also set appropriately. However, when forming ridges at the time of drawing using n-divided die pieces, it is easier to form one or every other number corresponding to the inner surface width of the divided dies. Can be formed.
[0014]
Moreover, although the radial direction height of a protruding item | line depends on the press fitting allowance to the other party member, it is desirable that it is a thing smaller than about 1.5 mm. If it is more than this, the difference in the amount of squeezing from the outer cylindrical surface becomes too large, which may affect the durability of the rubber-like elastic body.
[0015]
Further, the outer cylinder may be either a straight pipe or an outer cylinder flange that protrudes radially outward at the end of the cylinder. Generally, the outer cylinder is a rubber bush having an outer cylinder flange formed thereon. When the present invention is applied, the outer cylinder flange functions as a stopper at the time of press-fitting when it is press-fitted into the cylinder part of the counterpart member, which is preferable.
[0016]
For the formation of the ridges, when drawing is not performed, a method of alternately forming the cylindrical surface and the ridges in the circumferential direction of the outer peripheral surface of the outer cylinder by a press or the like may be adopted. In the case of applying, it can be easily formed by performing stepped drawing on the peripheral surface of the outer cylinder at the time of drawing.
[0017]
In general, the drawing of the outer cylinder is performed by setting the outer cylinder inside the radially divided n-piece dice pieces and moving each dice piece inward in the radial direction. In the case of stepped drawing for the purpose, if the dice obtained by retreating the inner surface of some of the n-divided dice pieces to the outside of the diameter are divided as in the general case By moving the die piece radially inward, the ridge and the cylindrical surface can be easily formed. In addition, what is necessary is just to use the die | dye which provided the level | step difference in the axial direction of die | dye, when forming only a part of axial direction of a protruding item | line (refer FIG. 5).
[0018]
When the press-fitting allowance to the connecting cylinder is large (for example, 0.5 mm or more) by combining these drawing die pieces, adjust the area of contact with the press-fit length of the rubber bush so that the press-fit load is 3 ton or less. Optimization of load and punching load can be achieved.
[0019]
In addition, as a rubber-like elastic body, the present invention can be applied to a rubber-like elastic body that is filled in a solid state between the inner and outer cylinders, or that has a hole formed therein or an intermediate cylinder interposed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a view when a rubber bush according to an embodiment of the present invention is incorporated in a connecting cylinder of a suspension arm, FIG. 2 is a sectional view taken along the line CC in FIG. 1, and FIG. 3 is a sectional view taken along the line EE in FIG.
[0021]
The rubber bush 1 in the present embodiment is vulcanized by being interposed between an inner cylinder 3 as a shaft member attached to a vehicle side bracket, an outer cylinder 4 disposed around the inner cylinder 3, and the inner and outer cylinders 3 and 4. And a rubber-like elastic body 5 bonded thereto.
[0022]
The inner cylinder 3 is a thick cylindrical pipe, and a bolt (not shown) for connecting to a bracket on the vehicle body side is passed through the center hole 6.
[0023]
The outer cylinder 4 is formed of a cylindrical member made of a thin metal having a uniform thickness, and an outer cylinder flange 7 protruding outward in the radial direction is formed at one end portion. As shown in FIG. 1, the outer cylinder 4 is press-fitted into a connecting cylinder 9 such as a suspension arm 8. The outer cylinder 4 employs the following configuration so that the outer cylinder 4 can be press-fitted with a predetermined press-fitting load and a predetermined pull-out load can be secured even when the inner diameter dimensional tolerance of the connecting cylinder 9 increases.
[0024]
That is, as shown in FIGS. 1 to 3, the outer cylinder 4 has a stepped drawing process on the outer peripheral surface thereof, which is the same as the cylindrical surface 10 having a large drawing amount radially inward along the circumferential direction. A plurality of ridges 11 having a small amount of drawing are alternately formed (in the embodiment of FIG. 2, the ridges 11 and the cylindrical surface 10 are each formed with six ridges). The circumferential intervals of the ridges 11 of the large diameter φd projecting radially outward from the cylindrical surface 10 of the small diameter Φd1 are equal, and the axial direction of the ridges 11 is the axial direction except for the press-fit side end 4a. Is formed up to the rising portion of the outer cylinder flange 7.
[0025]
As shown in FIGS. 4 and 5, the ridge 11 is formed at the time of drawing using an n-divided die 15. 4 is a view showing a cross-sectional form of the die before and after the drawing, FIG. 5A is a cross-sectional view taken along line AA of FIG. 4, and FIG. 4B is a cross-sectional view taken along line BB. As shown in FIG. 4, the die 15 is composed of 16 radially divided pieces, and the rubber bush 1 is set inside the die 15 (inner diameter φd0) having a gap 19 between each piece. The outer cylinder 4 is drawn by moving each die piece inwardly by a moving means such as a cylinder.
[0026]
As a part of the die pieces 15a of the dies 15 in this case, as shown in FIG. 5 (a), one having a step 16 having a die surface 17a receding to the outside of the diameter from the remaining die piece 15b is adopted. The protrusion 11 is formed, and the remaining die piece 15b is formed with a uniform die surface 17 as shown in FIG.
[0027]
The ridge forming die piece 15a has a large-diameter curvature radius portion 17a for forming the ridge 11 and a small-diameter curvature radius portion 17b for forming the cylindrical surface 10 at the press-fitting side end on the die surface 17. And a step 16 resulting from the difference in radius of curvature. The height of the step 16 sets the radial height of the ridge 11, and depends on the press-fitting allowance to the connecting cylinder 9, but is generally set to be smaller than 1.5 mm [φd−φd1 <1. 0.5 mm (where φd is the outer diameter of the projection, φd1: the outer diameter of the cylindrical surface)]. In FIG. 5, l0 corresponds to the axial length of the outer cylinder 4 and l corresponds to the axial length of the ridge 11. The relationship between l and l0 only needs to satisfy l / l0 ≦ 1.
[0028]
The rubber-like elastic body 5 is a cylindrical member interposed between the inner and outer cylinders 3 and 4 and is vulcanized and bonded to the inner and outer cylinders 3 and 4. As a material of the rubber-like elastic body, natural rubber or synthetic rubber generally used for vibration-proof rubber, for example, SBR (styrene butadiene rubber), BR (butadiene rubber), IR (isoprene rubber), NBR ( Acrylic nitrile 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.
[0029]
The rubber bush 1 having the above configuration is vulcanized and bonded by interposing a rubber-like elastic body 5 between the inner cylinder 3 and the outer cylinder 4, and in order to take a rubber contraction after vulcanization bonding, and durability of the rubber In order to improve this, the outer cylinder 4 is reduced in diameter radially inward using a die 15 as shown in FIG. At the time of drawing with the die 15, the die piece 15 a with the step 16 is incorporated into a part of the die 15, so that the cylindrical surface 10 with a large drawing amount and the ridges 11 with a small drawing amount are alternately arranged in the circumferential direction of the outer cylinder 4. The rubber bush 1 having a cross-sectional petal shape existing in FIG.
[0030]
The outer cylinder 4 fits the petal-like rubber bush 1 into the connecting cylinder 9 of the suspension arm 8 until the outer cylinder flange 7 comes into contact with the end face of the connecting cylinder. At this time, even when the inner diameter dimensional tolerance on the connecting cylinder 9 side is large, the rubber bush 1 sufficiently corresponds to this with a press-fit load (for example, MAX 3 ton or less) of a predetermined value or less and a removal load of a predetermined value or more (for example, 0 .5 ton or more).
[0031]
FIG. 6 shows a press-fit load and a tightening allowance between a normal rubber bushing having the same outer diameter drawing process (shown as “normal drawing” in the figure) and a rubber bushing of this embodiment (shown as “petal drawing” in the figure). It is a figure showing these relationships. In the figure, for example, when the tightening margin is set to 0.4 mm, the press-fit load of the present embodiment is less than that of the rubber bush having the same outer diameter. This is because, in the case of this embodiment, the contact surface with the inner surface of the connecting tube 9 is reduced, and the protruding strip 11 portion that has come into contact with the connecting tube 9 can release stress to the tube surface 10 side. Therefore, if the combination of the dice 15 is freely selected and the tightening margin is set based on the relationship between the press-fitting load and the punching load, the press-fitting load and the punching load can be optimized.
[0032]
【The invention's effect】
As is apparent from the above description, according to the present invention, since the ridges projecting radially outward are formed at a plurality of locations on the outer peripheral surface of the outer cylinder along the axial direction of the shaft member, Even when the inner dimensional tolerance increases, the rubber bush can be incorporated with a press-fit load of a predetermined value or less, and the press-fit load and the punch load can be optimized.
[Brief description of the drawings]
1 is a view when a rubber bush according to an embodiment of the present invention is incorporated in a connecting cylinder of a suspension arm. FIG. 2 is a cross-sectional view taken along a line CC in FIG. 1. FIG. 4] Cross-sectional view of the die before and after the drawing of the rubber bush [FIG. 5] (a) is a cross-sectional view taken along the line AA of FIG. 4, and (b) is a cross-sectional view taken along the line BB [FIG. Fig. 7 Comparison of the relationship between press-fit load and tightening allowance between this model and this product [Fig. 7] Diagram of installing a conventional rubber bush into the connecting cylinder of the suspension arm [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rubber bush 3 Inner cylinder 4 Outer cylinder 5 Rubber-like elastic body 10 Cylindrical surface 11 Convex strip 15 Dice 15a Stepped die piece

Claims (1)

In a rubber bush for interposing a rubber-like elastic body between a shaft member and an outer cylinder arranged around the shaft member and press-fitting into a cylinder portion of a counterpart member, Using a die in which one or a plurality of stepped die pieces whose inner surfaces are retreated to the outside of the diameter are partly placed, and each of the divided die pieces is moved radially inward, the outer cylinder A rubber bushing outer cylinder that alternately forms cylindrical surfaces with a large amount of drawing and protruding ridges with a small amount of drawing protruding outward in the radial direction in the circumferential direction of the outer cylinder Squeezing method.

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