JPH10325464A - Rubber made cvj boots - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a vulcanization time and increase a productivity and also equalize the tightening force by a band by forming a recessed part on the outer periphery surface of a thick part projected to the inner periphery surface side of a large diameter side fixing part. SOLUTION: A boot 1 is provided with a thick part 5 projected to the inner periphery surface 4a side of a large diameter side fixing part 4 and can be installed on the boots installation part 2 of the large diameter side of a triport joint 3 on whose outline shape is formed in a non-circle shape. In this large diameter side fixing part 4, the thick part 5 projected inside and a thin part with an equal thickness are alternately formed, and the inner periphery surface 4a is molded along the outer priphery surface of the boots installation part 2. A recessed part 6 called as a pin hole is formed on the outer periphery surface 5a of the thick part 5. By forming this pin hole 6 to a slightly deeper than the half of the thickness of the thick part 5, a vulcanization time can be reduced without hurting a seal property. By nearly equalizing the volume of respective pin holes 6, it is prevented that the tightening force at the band tightening time becomes unequal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber CVJ boot which is mounted on two shafts rotating at an operating angle like constant velocity joints by fixed portions at both ends of a bellows portion and used for holding grease and preventing dust. About. More specifically, according to the present invention, a mating member, such as a tripod joint, in which a contour shape (outer contour of a cross section) of an outer peripheral surface of a portion to which a boot is to be attached (hereinafter, referred to as a boot attaching portion) is non-circular. Rubber CVJ to be attached to something like
Regarding boots.

[0002]

2. Description of the Related Art A CVJ boot to be mounted on a mating member having a non-circular boot mounting portion, such as a tripod joint, having a non-circular outer peripheral surface is provided with a thick portion protruding inward at a fixing portion thereof. It is shaped to follow the contour of the outer peripheral surface of the mating member. This is because, in the case of a tripod type constant velocity joint, 3
Since the recessed portion is formed and the profile of the cross section of the boot mounting portion is non-circular, it is necessary to project the inner peripheral side of the fixing portion of the CVJ boot in accordance with the non-circular shape. The reason is that the contour of the outer periphery must be formed in a perfect circle in order to enable uniform tightening over the entire periphery.

[0003]

However, in the rubber CVJ boots described above, since the fixing portion has a thick portion, the vulcanization time during molding is governed by the vulcanization time required for the thick portion. Has the problem that it takes time. That is, the productivity of the CVJ boots deteriorates.

[0004] Further, since the fixing portion has a thick portion and a thinner portion, it is difficult to tighten the boundary portion with a band or the like.
There is a possibility that the sealing performance may decrease.

Accordingly, the present invention can improve the productivity of the entire CVJ boot by shortening the vulcanization time of the thick portion of the fixing portion of the rubber CVJ boot, and can even out the tightening force of the band or the like. An object of the present invention is to provide a rubber CVJ boot.

[0006]

In order to achieve the above object, the invention according to claim 1 is provided with a thick portion protruding inward on the inner peripheral surface side of the large-diameter fixing portion, and the outer peripheral surface has a contoured shape. In a rubber CVJ boot mounted on the large diameter boot mounting portion of the non-circular mating member, a concave portion is formed on the outer peripheral surface of the thick portion.

Therefore, during vulcanization, a part of the mold forming the concave portion of the thick portion remains inserted into the thick portion, and the thick portion is simultaneously heated from inside and outside. The vulcanization proceeds.

Further, since the concave portion is formed on the outer peripheral surface of the fixing portion, the twist of rubber generated on the outer peripheral surface of the fixing portion by the tightening of the tightening band is absorbed by the concave portion. In addition, since the concave portion is formed on the outer peripheral surface of the fixed portion, a convex portion is formed on the cavity surface of the outer mold. For this reason, the die is easily removed.

Further, in the rubber CVJ boot according to the second aspect, the concave portion is formed so that the volume of each thick portion is substantially the same. Therefore, irrespective of the number, shape and depth direction of the recesses formed in each thick portion, the crushing margin is moved by the tightening of the tightening band, and the distribution of the rubber becomes substantially uniform. Further, there is no variation in the vulcanization time in each thick portion.

Further, in the rubber CVJ boot according to the third aspect, the bottom surface of the concave portion and the inner peripheral surface of the thick portion in the cross section of the fixing portion have the same arc of the center of curvature. Therefore, the thickness between the inner peripheral surface of the thick portion and the bottom surface of the concave portion becomes substantially uniform, and the tightening force at this portion becomes uniform.

Further, in the rubber CVJ boot according to the fourth aspect, the depth direction of the concave portion is set to be the direction in which the molding die of the rubber CVJ boot is released. Therefore, the rubber C
When the mold is opened after vulcanization of the VJ boot, the mold opening direction and the depth direction of the concave portion match, so that the convex portion of the molding die for molding the concave portion can be extracted without catching on the product.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings. Figure 1 shows the rubber CVJ used for the tripod joint 3 for automobiles.
1 shows an embodiment of a boot (hereinafter simply referred to as “boot”). The boot 1 includes a thick portion 5 protruding inward on the inner peripheral surface 4a side of the large-diameter side fixing portion 4, and a mating member whose outer peripheral surface is formed in a non-circular shape, that is, a tripod joint. 3 can be mounted on the boot mounting portion 2 on the large diameter side. On the large diameter side fixing portion 4 mounted on the boot mounting portion 2, thick portions 5 protruding inward and thin cylindrical portions having a uniform thickness are alternately formed, and the inner peripheral surface 4a is formed in the boot mounting portion. 2 is formed in a shape along the outer peripheral surface. A concave portion (hereinafter referred to as a “pin hole”) 6 is formed on the outer peripheral surface 5 a of the thick portion 5 of the boot 1.

The boot 1 has a bellows portion 7, a large-diameter fixed portion 4 which is arranged at one end of the bellows portion 7 and is fitted to an outer ring portion 8 of the constant velocity joint 3, and is arranged at the other end of the bellows portion 7. Small-diameter side fixing portion 10 which is fitted to the rotating shaft portion 9 of the constant velocity joint 3
It is composed of The large-diameter side fixing portion 4 and the small-diameter side fixing portion 10 are respectively fastened and fixed to the constant-velocity joint 3 which is a mating member by a tightening band 11.

The large-diameter fixed portion 4 is integrally formed with a thick portion 5 that protrudes radially inward and fits into the concave portion 8a of the outer race portion 8 that becomes the large-diameter boot mounting portion 2 of the constant velocity joint 3. . Each thick portion 5 is provided at a position corresponding to each recess 8 a of the outer ring portion 8, that is, at three places at equal intervals in the circumferential direction of the large diameter side fixing portion 4. Further, the contour of the outer peripheral surface of the cross section of the large diameter side fixing portion 4 is a perfect circle so that uniform tightening can be performed over the entire circumference.

A pin hole 6 is formed on the outer peripheral surface 5a of each thick portion 5. The pin hole 6 is, for example, a cylindrical hole, is radially arranged toward the center of the large-diameter side fixing portion 4, and is formed slightly deeper than half the thickness of the thick portion 5. The present inventors have confirmed through experiments that there is a relationship between the depth of the pin hole 6 and the vulcanization time and sealing property. According to this experiment, the vulcanization time becomes shorter as the pin hole 6 is provided and the depth thereof is increased as compared with the case where the pin hole 6 is not provided, but the sealing property is deteriorated beyond a certain depth.
Therefore, the depth L of the pin hole 6 is 50 to 50 times the thickness T of the thick portion.
It is preferably set to 70%. In this case, the vulcanization time can be shortened without impairing the sealing property. Of course, this value is
It goes without saying that it depends on the shape and arrangement position of the pin hole 6.

A pin hole 6 provided in each thick portion 5
Is preferably formed to have substantially the same volume. In this case, the pin holes 6 are crushed at the same time when the band is tightened, so that the tightening force can be prevented from becoming uneven and the vulcanization time can be uniform.

The procedure for manufacturing the boot 1 will be described below. First, an unvulcanized rubber material obtained by kneading a vulcanizing agent and other necessary additives into chloroprene rubber, silicon rubber, or the like is injected into a heated mold. The mold 12 is, for example, as shown in FIG.
As shown in the figure, the outer mold 15 including the upper mold 13 and the lower mold 14
And a core mold 16. In addition, the upper mold 13 and the lower mold 14
Pins 17 and 18 projecting into the cavities are embedded in portions where the thick portion 5 is formed. Here, the pin 17 on the upper side 13 is fixed to the upper die 13. The pins 18, 18 of the lower mold 14 are inserted into the lower mold 14 so as to be freely inserted into and removed from the lower mold 14 through pin access holes 14a communicating with the outside. For this reason, the pins 18 can be protruded and retracted in a portion where the thick portion 5 of the cavity is formed. Although not shown, the tips of the pins 18 and 18 on the cavity side project outside the mold 12 with a predetermined length in the cavity, for example, the same length as the pin 17 projects into the cavity. Locking means for locking so as not to be pushed back is provided.

Then, the outer mold 15 and the core mold 16 are combined, and the pins 18, 18 are projected into the cavity by the same amount as the projected amount of the pin 17, and locked by the lock means. In this state, unvulcanized rubber is injected into the cavity.
At this time, since the outer mold 15 and the core mold 16 are heated in advance, the rubber in the cavity is heated and vulcanized.

Here, since the pins 17 and 18 protrude from the portions where the thick portions 5 of the cavity are formed, the rubber of the thick portions 5 is heated from the periphery by the outer mold 15 and the core mold 16. In addition to the above, the pins 17 and 18 heat the inside from the inside. Therefore, heat is quickly applied to the thick portion 5, and the vulcanization time of the thick portion 5 can be reduced.

After the vulcanization, the pin 18 is pulled out of the cavity and retracted, and then the outer die 15 is divided. At this time, even if the longitudinal direction of the pin 18 is different from the mold opening direction, the pin 18 is not caught at the time of the mold splitting and does not hinder the mold splitting or damage the pin hole 6 portion of the product. Further, it is not necessary to divide the outer mold 15 into three parts, and the product can be taken out simply by dividing it into two parts.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, as shown in FIG. 3, a plurality of pin holes 6 may be formed in one thick portion 5. In this case, since the specific surface area of the pin hole 6 can be increased, more heat can be applied to the inside of the thick portion 5 in a short time, and the vulcanization time can be further reduced.

Further, as shown in the figure, the depth direction of the pin hole 6 can be inclined with respect to the thick portion 5 in accordance with the die-cutting direction. In this case, as shown in FIG. 4, even if all the pins 17 and 19 projecting into the cavity of the mold 12 are fixed pins, when the mold is split after vulcanization, all the pins 17 and 19 are in the pin holes 6. It can be easily pulled out without getting caught. For this reason, the workability of manufacturing the boot 1 can be improved.

Further, since the pin hole 6 is formed obliquely to the thick portion 5, the pin hole 6 can be deeper than when the pin hole 6 is formed perpendicular to the thick portion 5. Therefore, even in the same hole shape, the pin 19 and the thick portion 5 can be brought into contact with each other in a larger area, and a small number, for example, only one pin hole 6 is provided in order to provide a predetermined heating amount. And the number of parts can be reduced.

Although the shape and number of the pin holes 6 are not particularly limited, the bottom shape of the pin holes 6 may be the same as that of the inner peripheral surface 4a of the thick portion 5 as shown in FIG. It is preferable that the wall thickness t between the bottom surface of the pin hole 6 and the inner peripheral surface 4a of the thick portion 5 is made uniform by forming an arc, that is, a concentric circle. In this case, when the boot 1 is mounted on the constant velocity joint 3 and tightened with a band, the pin hole 6 does not completely collapse as shown in FIG. 6, but slightly collapses in such a manner as to expand inward. Therefore, boot 1 in this part
The clamping force by itself is slightly greater in the central part.
On the other hand, in the fastening by the fastening band 11, the fastening band 11 and the boot 1 are not in direct contact with each other in the pin hole 6, so that the fastening force in the central portion is considered to be weaker than in other portions. Therefore, the overall tightening force of the tightening force of the boot 1 itself and the tightening force of the tightening band 11 is made uniform. As a result, uniform sealing over the entire circumference of the large-diameter-side fixing portion 4 of the boot 1 can be obtained.

As shown in FIG. 7, a plurality of pin holes 6 are formed in each thick portion 5, and the bottom surface of each pin hole 6 is formed concentrically with the inner peripheral surface 4a of the thick portion 5. You can also. Also in this case, when the boot 1 is mounted on the constant velocity joint 3 and the tightening band 11 is mounted, the tightening force becomes uniform over the entire circumference of the fixing portion 4, so that a uniform sealing property can be obtained.

Further, in each of the above-described embodiments, the cylindrical pin hole 6 is formed as the concave portion of the thick portion 5.
It is not limited to this. For example, holes having various shapes such as a hemispherical shape, a semi-cylindrical shape, a rectangular parallelepiped shape, a pyramid shape, a prism shape, etc. can be employed as necessary. Further, as shown in FIG. The groove may be an axial groove 6 ′ reaching the groove or a circumferential groove (not shown). In any case, the vulcanization time of the thick portion 5 can be shortened by forming the heated pin in the groove 6 ′ of the boot 1.

In each of the above-described embodiments, the thick portions 5 are formed at three places at equal intervals in the circumferential direction of the large-diameter side fixing portion 4, but the number and positions of the thick portions 5 are not particularly limited. It is not something to be done. Also, the shape of the thick portion 5 is not particularly limited.

[0028]

As shown in FIG. 9, the thickness of the thick portion 5 having a thickness T is 60 to 80% of the band width so that the pin hole 6 is not collapsed even if the diameter is tightened by the tightening band 11.
Boot 1 provided with one pin hole 6 set in
By changing the ratio L / T between the depth L of the pin hole 6 and the thickness T of the thick portion 5 within the range of 10 to 90%, the vulcanization time and the sealing property as compared with the case where the pin hole 6 is not formed are improved. Was determined by experiment. The results are shown in FIG.

[0029]

[Table 1] As is clear from FIG. 10 and Table 1, when the depth ratio L / T is 5
When the content was 0 to 70%, the vulcanization time could be shortened and good sealing properties could be obtained. Therefore, it was found that the pin hole 6 formed in the thick portion 5 preferably has a depth ratio L / T of 50 to 70%. In addition, the depth ratio L / T is 80%.
It is considered that the reason why the sealing performance is inferior when the value exceeds the above is that the thickness of the portion where the pin hole 6 is formed becomes too thin and is deformed by tightening the band.

[0030]

As is apparent from the above description, according to the first aspect of the present invention, the concave portion is formed on the outer peripheral surface of the thick portion. A part of the mold that forms the concave portion remains in a state where it is inserted into the thick portion, and the thick portion is simultaneously heated from inside and outside,
Allow vulcanization to proceed. For this reason, the vulcanization time of a thick part can be shortened, the manufacturing time of a rubber CVJ boot can be shortened, and workability can be improved.

Moreover, since the pin holes are formed on the outer peripheral surface of the fixing portion, the pin holes are formed on the outer peripheral surface of the fixing portion due to the tightening of the tightening band, so that a reduction in the tightening force is prevented. Can be.

Further, since the pin hole is formed on the outer peripheral surface of the fixed portion, a convex portion is formed on the cavity surface of the outer mold to be molded. For this reason, the die can be easily removed, and the workability can be improved.

In the rubber CVJ boot according to the second aspect, the concave portions are formed so that the volume of each thick portion is substantially the same, so that the number of concave portions formed in each thick portion and Irrespective of the difference in the shape and the depth direction, the crushing allowance is moved by the tightening of the tightening band, and the distribution of the rubber can be made substantially uniform. Thereby, the fastening force to the boot mounting portion by the fixing portion can be made uniform in the circumferential direction, and uniform sealing performance can be obtained over the entire circumference of the fixing portion. In addition, the variation in the vulcanization time at each thick portion is reduced, and the vulcanization time can be further reduced.

Further, according to the rubber CVJ boot of the third aspect, the thickness between the bottom surface of the concave portion and the inner peripheral surface of the thick portion can be made substantially uniform, so that the tightening force at this portion is uniform. Becomes Thereby, uniform sealing properties can be obtained over the entire circumference of the fixed portion.

According to the rubber CVJ boot of the fourth aspect, the depth direction of the concave portion is made to coincide with the mold split direction of the molding die.
A part of the mold for forming the concave portion and the convex portion can be extracted without being caught by the concave portion. Therefore, the mold opening operation can be easily performed, and the product is not damaged when the mold is opened.

[Brief description of the drawings]

FIG. 1 is a view showing a rubber CVJ boot according to the present invention, in which (a) is a longitudinal sectional side view and (b) is a front view.

FIG. 2 is a cross-sectional view showing a mold for manufacturing a rubber CVJ boot.

FIG. 3 is a front view showing another embodiment of a rubber CVJ boot.

4 is a cross-sectional view showing a mold for manufacturing the rubber CVJ boot shown in FIG.

FIG. 5 is a partially omitted front view showing another embodiment of a rubber CVJ boot.

6 is a partially omitted front view showing a state in which the rubber CVJ boot shown in FIG. 5 is attached to a constant velocity joint.

FIG. 7 is a front view showing still another embodiment of a rubber CVJ boot.

FIG. 8 is a front view showing still another embodiment of the rubber CVJ boot, in which (a) is a longitudinal sectional side view and (b) is a front view.

FIG. 9 is a longitudinal sectional side view showing dimensions of each part of a thick part.

FIG. 10 is a graph showing a correlation between a depth ratio and a vulcanization time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rubber CVJ boot 2 Boot attachment part 3 Constant velocity joint (partner member) 4 Large diameter side fixing part 5 Thick part 5a Outer peripheral surface of thick part 6 Pin hole (recess) 6 'groove (recess)

Claims (4)

[Claims] An inner peripheral surface of a large diameter side fixing portion has a thick portion protruding inward and is attached to a large diameter side boot mounting portion of a mating member whose outer peripheral surface has a non-circular contour. A rubber CVJ boot, wherein a concave portion is formed on an outer peripheral surface of the thick portion. 2. The rubber CVJ boot according to claim 1, wherein said thick portions have substantially the same volume. 3. The rubber C according to claim 1, wherein the bottom surface of the concave portion and the inner peripheral surface of the thick portion in the cross section of the fixing portion are arcs having the same center of curvature.
VJ boots. 4. The rubber CVJ is formed in a depth direction of the recess.
The rubber CVJ boot according to any one of claims 1 to 3, wherein the direction is a direction in which a molding die of the boot is removed.