JPH03186626A - Bush - Google Patents

Abstract

PURPOSE:To eliminate the need of aligning a click at the time of replacing a brush so as to facilitate replacement by connecting a cylindrical outside member to a shaft by a rubber, and locking recess portions formed on projecting end portions of the shaft by cutting with burrs. CONSTITUTION:A bush 1 comprises a metallic cylindrical outside member 2, a shaft 3 and a rubber 4 filling between the member 2 and the shaft 3. A hollow portion 3 as a fitting hole is provided on a shaft 3, and both projecting end portions 6 are projected from the outside member. A joint surface 6a is machined to form a roughened surface having a lot of recess portions 7 and burrs formed on the peripheries thereof. When the projecting end portions 6 of the shaft 3 are brought into contact with connecting members 13, 14 as joint surfaces and fastened thereto, the burrs are easily buckled and deformed, so that the frictional force is increased and there is no biting into the connecting surface. Accordingly, it is not necessary to align with a click and a biting cave of the bush before replacement so as to provide a bush which can be easily replaced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to bushings mainly used in vehicles, such as those used to connect vibrating members in suspension parts, engine mount parts, etc. of automobiles.

(Background of the Invention) A bushing used for purposes such as vibration isolation and cushioning is generally a cylindrical outer member, a shaft inserted inside the bushing, and a bushing filled between the outer member and the shaft. The outer member is fixed to a swinging member such as an automobile suspension arm, and the joint surfaces of both ends of the shaft are pressed against the other connecting member and fastened with bolts, nuts, etc. This buffers the relative movement of the swinging member and the connecting member, and provides elastic connection with a degree of freedom in directionality in swinging.

In this type of product, if the joint surface of the shaft is smooth, when excessive torque is applied to the shaft due to the movement of the swinging member, etc., slippage will occur between the joint surface of the shaft and the connecting member, resulting in the fastening. Looseness occurs in the parts. Therefore, it is necessary to provide a locking mechanism on the joint surface of the shaft. Possible means for preventing loosening include performing shot processing such as sandblasting on the joint surface of the shaft, or forming sawtooth teeth or pawls by knurling, breath cutting, or the like.

In the former case, since masking the rubber is difficult, it is common to first perform shot processing on the shaft and then bake the rubber. However, the rough surface formed by shot processing is crushed and smoothed by the clamping of the mold in the rubber baking process, and is also smoothed when the rubber adhering to the surface is removed by puffing or the like after baking. Therefore, it is difficult to use as a locking means that moves to the right.

In the latter case, the teeth or claws are large in size and the connecting member is prevented from loosening by deeply biting the tip of the serrated teeth or claws formed at the end of the shaft into the contact surface of the connecting member. It is required to be harder than steel, and is usually hardened. However, biting the tips of the teeth or claws damages the contact surfaces of the connecting members and causes corrosion, and the bite marks become larger, so when replacing the bushing with a new one, avoid loosening during subsequent use. In order to reliably prevent this, it is necessary to tighten the tip of the new tooth or claw so that it matches the bite mark formed by the previous bushing. However, in practice, this kind of work is nearly impossible, making it extremely difficult to replace the bushings. Examples of such bushings include Utility Model Application No. 57-65245 and No. 57-16.
There are various publications such as No. 5827. The former publication discloses that a shaft is manufactured by winding a plate material into a cylindrical shape, and at that time, it is shown that the ends of the plate material are press cut to form sawtooth-like irregularities. However, when this unevenness is used as a bushing, if the tip of the convex part that comes into contact with the mating member becomes rounded, it is useless as a locking mechanism, so it is usually hardened by quenching beforehand. , has the problems described above. Furthermore, the edges during press cutting are formed perpendicular to the cutting direction, that is, the joining direction, and do not participate in any way in preventing loosening. Furthermore, the third publication of the latter publication
The figure also shows serrated claws. However, since this claw also needs to bite into the mating member to prevent it from loosening, it is thought that it is a similar type that has been quenched and hardened in advance.

(Objective of the Invention) The present application is intended to solve the above-mentioned problems. To provide a bushing formed with a locking mechanism of appropriate hardness that is not so hard as to bite into the contact surface of a connecting member.

(Means for Solving the Problems) The bushing of the present application includes a cylindrical outer member, a shaft that is inserted into a hollow portion of the outer member and extends longer than the outer member, and that has a protruding end portion on the right side. Rubber is filled in the hollow part to connect the outer member and the shaft, and a locking mechanism is formed on the joint surface of the protruding end with the connecting member, and the locking mechanism is attached to the connecting surface of the protruding end. It is characterized in that it is formed by a concave portion engraved by stamping on the joint surface of the end portion, and a protrusion raised from the periphery of the concave portion in the joining direction as the concave portion is formed.

(Function of the invention) The joint surface provided on the protruding end of the shaft in the bushing according to the present invention has four parts engraved by stamping, and along with the formation of the recesses, a groove is formed around the four parts in the joining direction. Since a protuberance is formed on the joint surface of the shaft, when the connecting member is brought into contact with the joint surface of the shaft and the two are strongly fastened with bolts, etc., the pad formed on the joint surface of the shaft can be easily removed by the pressure contact of the connecting member. It is buckled and crushed, but
Since the crushed part is on the joint surface of the shaft, the joint surface of the shaft is not smoothed but maintains a rough surface state to some extent, and the frictional force with the connecting member increases. Therefore, even if the connecting member swings or the like, relative slippage between the two is suppressed and loosening of the fastening portion is prevented. Furthermore, the ribs will not dig into the connecting member during fastening, making it less likely to damage the connecting member.

(Example) FIGS. 1 to 4 show press-fit bushings used in automobile suspension parts, which are examples of the present invention. As shown in FIGS. 1 and 2, the bush l includes an outer member 2 that is a metal cylinder, and a shaft 3 that is inserted into the outer member 2.
and rubber 4 filled between the outer member 2 and the shaft 3
It consists of.

The outer member 2 and the shaft 3 are cylindrical metal shaft members. However, these cross-sectional shapes may be polygonal or irregularly shaped. The hollow part of the shaft 3 forms a mounting hole 5, and both ends of the shaft 3 have projecting ends 6 extending outwardly from the outer member 2.
This end face serves as a joint surface 6a with a connecting member to be described later.

Although the mounting hole 5 is for passing a mounting member such as a bolt, it does not necessarily have to extend through the shaft 3 in the axial direction, and may be a screw hole formed in at least one of the protruding ends 6. Furthermore, instead of the mounting hole 5, the joint surface 6a
A fastening member such as a bolt may be installed in the.

The joint surface 6a is roughened to include a large number of recesses 7 and burrs 8 (FIG. 1) formed around the recesses.

The recess 7 has a substantially triangular cross section carved inward from the joining surface 6a, and the burr 8 is integrally formed around this in the joining direction (the joining direction with the connecting member, the vertical direction in FIG. 1). It is usually raised and protruded by about 0.04 to several mm. When the shaft 3 and the connecting member are strongly connected by tightening bolts or the like, the burr 8 is buckled and crushed, or is not completely smoothed and has a rough surface on the joint surface 6a. It is something.

The rubber 4 has a bridge portion 9 that connects the outer member 2 and the shaft 3, and a clearance portion 10 (FIG. 2) that is outlined in white to separate the outer member 2 and the shaft 3, which are formed in the axial direction. There is. However, the presence or absence of the clearance portion 10 can be freely determined as necessary.

3 and 4 show the state of use. First, as shown in FIG. 3, a bushing 1 is formed at the end of a swinging member 11 such as a trailing arm of a suspension system.
It is press-fitted into a holder 12 having a diameter slightly smaller than the outer diameter of the bushing 1, and the joint surface 6a of the shaft 3 is brought into contact with the side parts 13a and 15a of the connecting members 13 and 15 fixed to the vehicle body,
Mounting holes 14 and 16 formed in the connecting members 13 and 15
Align the mounting holes 5 and bolts 17 and 18)
Fasten with fasteners such as The state after fastening is shown in FIG. 4, and since the burr 8 on the joint surface 6a protrudes in the joining direction and has not been hardened, it is buckled and deformed by the pressure caused by fastening and is crushed. However, since crushed burrs remain on the joint surface, it is not completely smoothed and remains rough. That is, the burr 8 has a buckling property and is not completely smoothed during fastening. As a result, the frictional force at the contact surfaces 13a and 15a between the shaft 3 and the connecting members 13 and 15 increases, suppressing relative slippage on these surfaces and preventing loosening of the fastened portion. Moreover, since it has no directionality, it is still effective against rotation. Moreover, since the burr 8 is easily buckled and deformed, the contact surfaces 13a and 15a of the connecting members 13 and 15
Since it is difficult to deeply damage the connecting member 13.
Deep bite by the burr 8 is not formed on the 5 side. Therefore, when replacing the bushing 1 with a new one, the burr 8 can be immediately fastened to the contact surfaces 13a, 15a of the connecting members 13, 15 at any position. That is,
If a bite mark remains as in the conventional case, loosening may occur during use unless the new tooth tip is tightened with the tip of the new tooth aligned with the bite mark. However, according to this embodiment, this is impossible. Eliminates the need for close alignment. Therefore, the bushing l can be replaced easily and quickly, and maintainability is significantly improved. Moreover, since the burr 8 is not hardened and is essentially a hard material, the materials of the connecting members 13 and 15 and the shaft 3 can be made to have the same degree of hardness, that is, they can be a combination of materials of the same type, giving you greater freedom in material selection. increases.

FIG. 9 is a graph of the characteristics when the bushing 1 is fastened, and is a characteristic diagram when a torque detector is attached to the connecting member 13 or 15 and the outer member 2 is rotated. This graph shows the rotation angle on the horizontal axis and the torque on the vertical axis, and shows how much torque the fastening part can reach without slipping.Slippage occurs when the characteristic curve becomes parallel to the horizontal axis. Further, the solid line in the graph is for the example of the present invention, and the dotted line is for the comparative example in the case of sandblasting.

As is clear from this, the structure of this embodiment can withstand large torque and suppress slippage.

Next, the manufacturing method of this bushing will be explained with reference to FIGS. 5 to 8.

FIG. 5 shows the mold in the rubber baking process. The outer member 2 and the shaft 3 include an upper mold 20, a middle mold 21, and a lower mold 2.
2, and the shaft 3 is fixed in its mounting hole 5.
Guides 23 and 24 protruding downward and upward from the upper die 20 and lower die 22, respectively, are inserted and positioned. A cavity 25 formed between the outer member 2 and the shaft 3 is a space filled with rubber, and rubber liquid is press-fitted into the cavity 25 through an injection hole 26 and vulcanized. Note that at this time, the joint surface 6a of the shaft 3 has not been processed yet and remains a smooth surface. FIG. 6 shows the intermediate molded product 27 formed by this mold. This differs from the final molded product (bush 1) only in that, as described above, the joint surface 6a of the shaft 3 remains an unprocessed smooth surface. Therefore, this intermediate molded product 27 is fixed to a suitable jig of a press molding machine, and a mold formed by protruding a large number of molded protrusions 31 on a base 30 is applied to the joint surface 6a via a shaft 32 to apply pressure. and press. Then, as shown in FIG. 8, a recess 7 corresponding to the molded protrusion 31 is stamped on the joint surface 6a. At the same time, a gap 8 is formed around the recess 7 integrally and protruding toward the surface. In addition, when pressing the joint surfaces 6a, 6a at both ends, it is preferable to perform both at the same time. This results in
A bush I, which is the final molded product of the present invention, is obtained.

According to this method, roughening the joint surfaces at both ends of the shaft using a shot method such as sandblasting or steel blasting after the rubber baking process is practical because the outer members and rubber must be masked. Although it is difficult, even after the rubber baking process, it is possible to easily form the pad 8 above the joint surface 6a to a certain degree of effectiveness as a loosening preventer.

Note that, as in this embodiment, the joint surface 6a of the cylindrical shaft 3
Even if an attempt is made to process the end face of a cylindrical object using a method such as herolet processing, there is currently no tool that can be applied immediately, and a special dedicated machine must be developed. Furthermore, if the process is carried out by hand, the processed surface tends to be an irregularly curved surface, and the fastening part is likely to loosen. The same is true for other machining processes, which either require the development of special techniques or are extremely inefficient. However, if a mold equipped with the molding protrusion 31 as in this embodiment is used, efficient molding with high mass productivity is possible without the need for a special dedicated machine. That is, practical and efficient manufacturing becomes possible.

Note that the present invention can be applied in various ways, and the dimensions of the paris can be adjusted as appropriate depending on the fastening conditions. When forming a rib on the end face of the shaft, it may be formed on only one side instead of both sides.

Further, the shape of the outer member and the shaft is not limited to a circle, but may be a polygon or an irregular cross section. Furthermore, the bushing can be used not only in suspension parts and engine mount parts, but also in various places that require vibration isolation, elastic coupling, and the like.

(Effects of the Invention) The bushing according to the present application has a locking mechanism formed on the joint surface of the shaft, consisting of a stamped recess and a collar integrally formed around the recess to protrude from the surface in the joining direction. therefore,
When the shaft and the connecting member are fastened, this loosening preventer forms a contact area with a large frictional force at the joint between the two, suppressing relative slippage between the two, and effectively preventing loosening of the fastened part. It can be prevented. Moreover, since the ribs protruding in the joining direction are easily buckled when the two are fastened together, there is no risk of damaging the connecting member so deeply as to form bite marks. This eliminates the need to align the pawls or teeth of a new bushing with the bite marks of the previous bushing when replacing the bushing, unlike in the past, in order to prevent loosening during use. It becomes easier and faster, and maintainability is significantly improved. Furthermore, the connecting member and the shaft can be made of a combination of members having similar hardness, increasing the degree of freedom in material selection.

[Brief explanation of drawings]

1 to 9 show embodiments of the present invention, FIG. 1 is a cross section of the bushing taken along line II in FIG. 2, FIG. 2 is a perspective view of the bushing, and FIG. 3 is an exploded configuration showing the installed state. Figure 4 is an axial sectional view of the installed state, Figure 5 is a sectional view showing rubber baking molding, Figure 6 is a sectional view of an intermediate product, and Figure 7 is a partial sectional view showing the surface roughening method. , FIG. 8 is an enlarged sectional view of the molded surface after surface roughening, and FIG. 9 is a graph showing the characteristics of the bushing with respect to torque. (Explanation of symbols) 1: Push, 2: Outer member, 3: Shaft. 4: rubber, 6: protruding end, 7: recess, 8: burr. 12: Swinging member, 13/15: Connecting member.

Claims (1)

[Claims] 1. A cylindrical outer member, a shaft that is inserted into the hollow part of the outer member and has a protruding end that extends longer than the outer member, and a rubber that is filled in the hollow part of the outer member and connects the outer member and the shaft. , and a locking mechanism is formed on the joint surface of the protruding end with the connecting member, wherein the locking lock is formed with a recess formed by stamping on the joint surface of the projecting end. A bush characterized in that it is formed with a burr raised from the periphery of the recess in the joining direction as the recess is formed.