WO2019189603A1

WO2019189603A1 - Boot for constant velocity joints, method for manufacturing boot for constant velocity joints, and device for manufacturing boot for constant velocity joints

Info

Publication number: WO2019189603A1
Application number: PCT/JP2019/013661
Authority: WO
Inventors: 末岡　一彦; 大野　雄三; 全二落合
Original assignee: 株式会社フコク
Priority date: 2018-03-29
Filing date: 2019-03-28
Publication date: 2019-10-03
Also published as: JPWO2019189603A1; JP7250767B2

Abstract

[Problem] To provide a boot for constant velocity joints, which is configured so that the boot is lightweight, a reduction in the fastening force of a fastening band is prevented, and sealing performance is maintained. [Solution] This boot for constant velocity joints comprises a bellows section 7 provided integrally, in a communicating manner, between a large-diameter-side end section 3 and a small-diameter-side end section 5. The inner peripheral surface of the large-diameter-side end section has: a plurality of thick-walled sections 17 which are formed protruding to the inner diameter side so as to match a plurality of recesses formed in the outer peripheral surface of an outer housing; and a thin-walled section 19 which is disposed between the plurality of thick-walled sections. The inner peripheral surfaces of the thick-walled sections and the inner peripheral surface of the thin-walled section have formed thereon lips 21a, 21b which continue in a circumferential direction and which are in contact with the outer peripheral surface of the outer housing, which includes the recesses, to seal the inside region of the boot. The thick-walled sections have formed therein one or more grooves 18 recessed in a radial direction from the inner peripheral surface side toward the outer peripheral surface side of the large-diameter-side end section. The grooves are formed in the circumferential direction of the thick-walled sections.

Description

Constant velocity joint boot Manufacturing method of constant velocity joint boot Manufacturing device of constant velocity joint boot

The present invention provides a constant velocity joint boot (CONSTANT VELOCITY UNIVERSAL JOINT), for example, an outer peripheral surface of a tripod type constant velocity joint used for a drive shaft or a propeller shaft that transmits the power of an automobile engine to a hub on which a tire is mounted. The present invention relates to a boot for a constant velocity joint to be mounted. The present invention also relates to a method for manufacturing the constant velocity joint boot and a constant velocity joint boot manufacturing apparatus used in the manufacturing method.

A constant velocity joint is used at both ends of a drive shaft for an automobile. A differential joint (inboard side) constant velocity joint includes, for example, a tripod joint (triport joint) in which, for example, three sets of rollers mounted on a shaft portion of a drive shaft are slidable in the axial direction. It is common to use a joint.
In order to reduce the thickness and weight of the outer casing of the tripod joint, concave portions provided in a groove shape in the axial direction of the outer peripheral surface are formed, for example, dispersed in three circumferential directions. The inner peripheral surface of the large-diameter side end of the constant velocity joint boot used in this type of tripod joint is adapted to the surface of the concave portion, and has a thickness formed, for example, by projecting in an arc shape in the axial direction. A meat part is formed. As this type of tripod joint boot, the inventors of the present application have previously proposed the technique described in Japanese Patent No. 4359532 (see Patent Document 1). In this prior art, a thick portion and a thin portion can be integrally formed in the circumferential direction on the inner peripheral surface of the large-diameter side end portion of the preform, and the thick portion after molding can be integrally formed. Even if it has an undercut portion, it is easy to pull out the boot from the core mold.

In recent years, automobiles have been made lighter in various parts due to demands for low fuel consumption and low cost.

Therefore, even in this type of tripod joint boot, there is an increasing demand for weight reduction, and the structure disclosed in Patent Document 2 is improved as a constant velocity joint boot with an emphasis on weight reduction. Proposed.
In Patent Document 2, weight reduction is achieved by removing the thickness from the outer surface side of the thick portion at the end portion on the large diameter side (see Patent Document 2).
In addition, such a thinning structure has such a tripod joint boot (constant velocity joint boot) having a thick portion and a thin portion having different thicknesses at the end on the large diameter side. Therefore, there is a possibility of causing shrinkage during molding, so that it also has a role of preventing heat shrinkage (sinking) during molding by balancing heat.

This type of tripod joint boot (constant velocity joint boot) is fitted to the outer periphery of the outer casing, and then tightened on the outer peripheral surface of the large-diameter side end using a metal fastening band, The lip projecting from the inner peripheral surface of the large-diameter side end is pressed against the outer peripheral surface of the outer casing to be sealed.
At this time, in order to improve the sealing performance, the tightening force by the tightening band is preferably concentrated on the lip portion protruding from the inner peripheral surface of the large-diameter side end portion.

However, in the case of the tripod joint boot structure disclosed in Patent Document 2, since the outer diameter side of the large-diameter end on the side in contact with the tightening band is thinned, the opening side of the thinned groove is tightened. Opposite the band, there is little area where the tightening band contacts.
That is, in the tripod joint boot disclosed in Patent Document 2, a grooved portion is located in the lower portion of the band where the largest tightening force is applied, and a solid portion exists between the groove and the lip portion. Therefore, even if the tightening band is fastened, the opening side portion of the groove (the outer peripheral surface of the large diameter side end portion) is greatly deformed, and the tightening force is not concentrated on the lip portion (lip The tightening force at the part is weak.) This point will also be described in detail in comparison with embodiments described later.

In addition, when forming the thinned portion on the outer peripheral side of the large-diameter end, a parting line at the time of mold forming appears on the outer peripheral surface.
Since the outer peripheral surface of the large-diameter side end is a fastening surface of the fastening band as described above, it is preferably a flat surface without unevenness, and if there is an extra parting line, a uniform fastening force cannot be given. There is a possibility that the tightening force is reduced.

Furthermore, since the place where the constant velocity joint boot is mounted is a harsh environment where muddy water, dust, etc. flies, as disclosed in Patent Document 2, a groove is formed on the outer peripheral side of the large-diameter end. Is provided, dust, stones, mud, muddy water and the like may enter the groove, and as a result, the fastening force may be reduced.
In addition, when chemicals such as road surface anti-freezing agents and muddy water accumulate, the fastening band is made of metal, so that the fastening band is likely to be damaged (rust, scratches) and the product life may be shortened.

Japanese Patent No. 4359532 JP 2002-13546 A

The present invention has been made in view of the above-mentioned problems of the prior art, and the object of the present invention is to provide a fastening force by an appropriate fastening band while reducing the weight of the tripod joint boot. An object of the present invention is to provide a tripod joint boot capable of preventing a decrease in the tightening force and maintaining good sealing performance.

In order to achieve such a problem, the first aspect of the present invention includes an annular large-diameter side end into which an outer casing of a tripod joint is inserted,
An annular small-diameter side end into which a shaft connected to the tripod joint is inserted;
A constant velocity joint boot comprising a bellows part integrally provided in a continuous manner between the large diameter side end part and the small diameter side end part and comprising a large diameter part and a small diameter part arranged repeatedly. There,
A plurality of thick portions formed on the inner peripheral surface of the large-diameter side end portion so as to fit in a plurality of concave portions formed on the outer peripheral surface of the outer casing and project in the boot inner diameter direction, and the plurality of thicknesses A thin wall portion disposed between the meat portions,
On the inner peripheral surface of the thick wall portion and the inner peripheral surface of the thin wall portion, a circumferentially continuous lip portion is formed in contact with the outer peripheral surface of the outer casing including the recess to seal the boot inner region. And
In the thick part, at least one groove part recessed from the inner peripheral surface side in the boot outer diameter direction is formed,
The groove portion is formed in a constant velocity joint boot characterized by being formed over the circumferential direction of the thick portion.

The second aspect of the present invention is the first aspect of the present invention, wherein two or more lip portions are formed,
Of these, at least two lip portions are located in the boot axial direction with the groove portion interposed therebetween, thereby providing a constant velocity joint boot.

According to a third aspect of the present invention, in the first aspect of the present invention or the second aspect of the present invention, when the thick portion is viewed from the bottom surface side of the large-diameter side end portion, This is a constant velocity joint boot characterized in that it has an arc shape formed in an upwardly inclined manner from the left and right hem parts to the top part.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the groove portion is formed such that the groove width in the boot shaft direction at the bottom portion is narrower than the groove width in the boot shaft direction at the top portion of the thick portion. This is a boot for a constant velocity joint.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the groove portion is in a boot outer diameter direction with respect to a boot axial groove width on the inner peripheral surface of the thick portion. This is a constant velocity joint boot characterized in that the groove width in the boot shaft direction is narrow.

In a sixth aspect of the present invention according to any one of the first to fifth aspects of the present invention, the groove portion is opposed to the boot shaft direction, and a rib is provided between the inner wall surfaces constituting the groove portion. This is a constant velocity joint boot.

The seventh aspect of the present invention is a large-diameter side end portion into which an outer casing of a tripod joint having a plurality of recesses on the outer peripheral surface is inserted, a small-diameter side end portion into which a shaft portion connected to the tripod joint is inserted, A bellows portion formed between the large-diameter side end portion and the small-diameter side end portion and repeatedly arranging the large-diameter portion and the small-diameter portion; And a plurality of thick portions formed so as to protrude toward the inner diameter side of the boot in conformity with the concave portion of the outer casing of the tripod joint, and a thin portion disposed between the plurality of thick portions. A method of manufacturing a boot for a quick joint,
A core mold is disposed in the large-diameter side end portion of a preformed product formed with a small-diameter side end portion and a large-diameter side end portion communicating with the internal space of the bellows portion at both ends, and at least the size of the preformed product is large. Arrange the holding mold on the outer peripheral surface side of the diameter side end,
An upper projecting portion provided in the core mold is brought into contact with an inner peripheral surface of the bellows portion or an inner peripheral surface of the large-diameter side end portion, and an inner peripheral surface of the holding mold is set to the large-diameter portion side end portion. The outer peripheral surface of the
A secondary molding portion comprising a plurality of thick portions and a plurality of thin portions at the large-diameter end between the inner peripheral surface of the large-diameter end of the preform and the lower peripheral surface of the core mold. Forming a secondary molding space for molding,
Injecting and injecting a molten material into the secondary molding space, and molding a secondary molded part composed of a thick part and a thin part at the large-diameter side end of the preform;
Including at least
The upper protrusion corresponding to the thick wall forming space constituting the secondary forming space, and the lower protrusion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold, Retreating in the direction of the central axis of the mold and removing it from the thick part molding space area of the secondary molding space, and separating the core mold and the boot in that state;
And a method for manufacturing a constant velocity joint boot.

According to an eighth aspect of the present invention, in the seventh aspect of the present invention, either one or both of the upper projecting portion and the lower projecting portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space is provided. The constant velocity joint boot manufacturing method is characterized in that the cam member is retracted from the thick portion region by driving a core member center shaft or a cam member pivoting about an axis parallel to the core center shaft. .

According to a ninth aspect of the present invention, in the seventh aspect of the present invention or the eighth aspect of the present invention, the downward protruding portion of the core mold corresponding to the thick portion forming space constituting the secondary forming space is The present invention provides a method for manufacturing a constant velocity joint boot, characterized by having a groove forming die surface formed in the portion.

The tenth aspect of the present invention is a large-diameter side end portion into which an outer casing of a tripod joint having a plurality of recesses on the outer peripheral surface is inserted, a small-diameter side end portion into which a shaft portion connected to the tripod joint is inserted, A bellows portion formed between the large-diameter side end portion and the small-diameter side end portion and repeatedly arranging the large-diameter portion and the small-diameter portion; And a plurality of thick portions formed so as to protrude toward the inner diameter side of the boot in conformity with the concave portion of the outer casing of the tripod joint, and a thin portion disposed between the plurality of thick portions. A device for manufacturing a fast joint boot,
A holding mold for holding the outer surface of a preformed product formed with a small-diameter side end and a large-diameter side end communicating with the internal space of the bellows part at both ends;
A core mold inserted into the large-diameter end of the preform,
In order to mold a secondary molding part composed of a plurality of thick part forming spaces and a plurality of thin part forming spaces formed between the inner peripheral surface of the large-diameter end of the preform and the outer peripheral surface of the core mold. An injection mechanism for injecting and filling molten material into the secondary molding space of
The holding mold includes an inner peripheral surface capable of contacting the outer peripheral surface of the large-diameter side end,
The core mold has a plurality of thicknesses between an upper projecting portion capable of contacting the inner peripheral surface of the bellows portion or the inner peripheral surface of the large-diameter end, and the inner peripheral surface of the large-diameter end. A lower peripheral surface forming a secondary molding space for forming a secondary molding portion composed of a meat portion and a plurality of thin portions, and a lower portion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold A protrusion, and
The upper projecting portion and the lower projecting portion of the core mold corresponding to the thick portion forming space constituting the secondary forming space can be advanced toward the thick portion forming space, and directed toward the core mold central axis direction. In other words, the constant velocity joint boot manufacturing apparatus is configured to be retractable.

The eleventh aspect of the present invention is the tenth aspect of the present invention, comprising a cam member that pivots about the core-type central axis or an axis parallel to the core-type central axis,
Either one or both of the upper projecting portion and the lower projecting portion of the core mold corresponding to the thick portion forming space constituting the secondary forming space is directed toward the thick portion forming space by the cam member. This is a constant velocity joint boot manufacturing apparatus characterized in that it can be advanced and retracted in the direction of the core axis.

In a twelfth aspect of the present invention, in the tenth aspect of the present invention or the eleventh aspect of the present invention, the downward protruding portion of the core mold corresponding to the thick portion forming space constituting the secondary forming space is The apparatus for manufacturing a constant velocity joint boot is characterized by having a groove forming die surface formed in the portion.

According to the present invention, while reducing the weight of the constant velocity joint boot, it is possible to apply a tightening force by an appropriate fastening band, prevent a decrease in the tightening force, and maintain a good sealing performance. We were able to provide fast joint boots.

It is a schematic longitudinal cross-sectional view which shows one Embodiment of the boot for constant velocity joints of this invention. It is a schematic bottom view which shows one Embodiment of the boot for constant velocity joints of this invention. It is a schematic longitudinal cross-sectional view which expands and shows a thin part. It is a schematic longitudinal cross-sectional view which expands and shows a thick part. It is a schematic perspective view which expands and shows a thick part periphery. It is a schematic perspective view which expands and shows other embodiment of the thick part in which the rib is formed over the inner wall surfaces which a pair of thick part structure which comprises a thick part opposes. It is a schematic perspective view which expands and shows other embodiment of the thick part in which the rib is formed over the inner wall surfaces which a pair of thick part structure which comprises a thick part opposes. It is the schematic enlarged view of the thick part seen from the direction orthogonal to the internal peripheral surface of the large diameter side edge part of FIG. 6B. It is the partial schematic which shows the difference in the width | variety of a groove part. It is a schematic longitudinal cross-sectional view which compares the thick part of this invention with the thick part of a comparative example. It is a core type | mold used for the manufacturing apparatus of this invention, Comprising: It is a schematic plan view which shows the state by which the 2nd type | mold part is extruded to the thick part shaping | molding space direction. It is a core type | mold used for the manufacturing apparatus of this invention, Comprising: It is a schematic longitudinal cross-sectional view which shows the state by which the 2nd type | mold part is extruded to the thick part shaping | molding space direction. It is a core type | mold used for the manufacturing apparatus of this invention, Comprising: It is a schematic plan view which shows the state which the 2nd type | mold part has evacuated from the thick part molding space. It is a core type used for the manufacturing apparatus of the present invention, and is a schematic longitudinal cross-sectional view showing a state where the second die part is retracted from the thick part forming space. It is a core type used for the manufacturing apparatus of this invention, Comprising: It is a schematic perspective view shown with a broken line while omitting a part. It is the schematic which shows the whole flow of the manufacturing method of this invention. It is other embodiment of the core type | mold used for the manufacturing apparatus of this invention, Comprising: It is a schematic longitudinal cross-sectional view which shows the state in which the 1st member and the 2nd member are located in the thick part formation space. It is other embodiment of the core type | mold used for the manufacturing apparatus of this invention, Comprising: It is a schematic longitudinal cross-sectional view which shows the state which the 1st member and the 2nd member have evacuated from the thick part formation space. It is other embodiment of the boot for constant velocity joints of this invention, Comprising: It is a general | schematic partial expanded sectional view in which the space is formed between the inclined part inner surface and the secondary shaping | molding part upper surface.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, this embodiment is only one embodiment of the present invention, and is not construed as being limited thereto. The design can be changed within the scope of the present invention.

"First embodiment"
One embodiment of the constant velocity joint boot of the present invention, a manufacturing apparatus used for manufacturing the constant velocity joint boot, and a manufacturing method using the manufacturing apparatus will be described separately.

[Description of constant velocity joint boots]
A constant velocity joint boot (hereinafter also simply referred to as a boot) 1 according to the present embodiment is used for a tripod joint in which a concave portion is formed on an outer peripheral surface of an outer casing. That is, in the outer casing of such a tripod joint, for example, three axial grooves formed in an arc shape in cross section are formed at substantially equal intervals in the circumferential direction of the outer peripheral surface.

As shown in FIG. 1, a constant velocity joint boot (tripod joint boot) 1 includes a large-diameter side end portion 3 into which an outer casing of the tripod joint is inserted, and an inner diameter and an outer side of the large-diameter side end portion 3. A small-diameter side end portion 5 having a small diameter. The shaft portion of the drive shaft connected to the tripod joint is inserted into the small diameter side end portion 5. A bellows portion 7 formed in a bellows shape is provided between the large diameter side end portion 3 and the small diameter side end portion 5.
In the boot 1, the large-diameter side end 3, the small-diameter side end 5 and the bellows 7 are integrally formed by a known preforming process using a resin such as a thermoplastic elastomer (hereinafter, this molded product). In addition, the inner peripheral side of the large-diameter side end portion 3 of the preform is a portion having a different thickness using a resin such as a thermoplastic elastomer. The next molding part 13 is integrally molded.

As shown in FIG. 1, the bellows portion 7 is formed with a large diameter, a large diameter portion (also called a mountain portion) 7 a formed so that the outside of the boot 1 is convex, and a small diameter, A small-diameter portion (also referred to as a trough portion) 7b formed so that the outer side of the boot 1 is concave is formed repeatedly in the cylinder axis direction of the boot 1. For example, in the case of the present embodiment, there are five large-diameter portions 7a and five small-diameter portions 7b arranged on the large-diameter side end portion 3 side with respect to the five large-diameter portions 7a. Configured. Each of the large diameter portion 7a and the small diameter portion 7b is formed such that the diameter gradually increases from the small diameter side end portion 5 side toward the large diameter side end portion 3 side. As a result, the boot 1 is generally a truncated cone as a whole. It is formed in a shape.

In the present invention, the bellows portion 7 is not particularly limited, and various conditions such as the thickness of the bellows portion 7 and the pitch of the large diameter portion 7a and the small diameter portion 7b are appropriately set within the scope of the present invention. Optimal conditions apply.
In the present embodiment, both the large-diameter side end portion 3 and the small-diameter side end portion 5 of the above-described preform are each made to have a uniform thickness with a desired thickness. These wall thicknesses are not particularly limited, and an optimum arbitrary thickness is selected.
Various conditions for the large-diameter side end 3 and the small-diameter side end 5 are not particularly limited, and optimum conditions are appropriately applied within the scope of the present invention. In the present embodiment, the thicknesses of the large-diameter side end 3 and the small-diameter side end 5 are made uniform. However, even if the thickness is not uniform, it is within the scope of the present invention.

As shown in FIGS. 1 to 4, the outer peripheral surface 15 of the large-diameter side end 3, which is a preformed product, is formed in a substantially circular shape, and band fastening when the boot 1 is attached to the tripod joint is formed on the outer peripheral surface 15. The portion 37 is recessed. The secondary molded portion 13 formed inside the outer peripheral surface 15 includes a plurality of thick portions 17 formed so as to project to the inner peripheral side and a plurality of thick portions 17 formed between the thick portions 17. A thin portion 19 is provided.
In the case of the present embodiment, for example, three thick portions 17 are formed at substantially equal intervals in the inner circumferential direction of the large diameter side end portion 3, and between the adjacent thick portions 17. Are formed with three thin portions 19 having a substantially constant thickness over the circumferential direction.

The thick portion 17 is formed between the pair of thick portion constituent bodies (bases) 17 a and 17 a and the pair of thick portion

constituent bodies

17 a and 17 a, and has a large diameter from the inner peripheral surface side of the large diameter side end portion 3. It is constituted by a groove portion 18 that is recessed in the radial direction (the direction indicated by the arrow R1 in the drawing) toward the outer peripheral surface side of the side end portion 3 and that is continuously formed over the circumferential direction of the thick portion 17. (See FIGS. 1 to 8).

When viewed from the bottom surface side of the large-diameter side end 3, the thick-walled component 17a rises from the left and

right skirts

17b, 17b toward the top 17c in the circumferential direction of the large-diameter side end 3. It is formed in an arc shape with a bottom view shape formed in an inclined shape (see FIG. 2).
The substantially arc shape of the thick portion 17 (thick portion constituent body 17a) is set so as to match the axial groove (recess) of the outer peripheral surface of the outer casing of the tripod joint to which the boot 1 is attached.
In this embodiment, although a pair of

thick part structure

17a and 17a is formed with the same axial width (thickness), a pair of

thick part structure

17a and 17a differs in axial width (thickness). It is within the scope of the present invention.

The groove shape in the boot radial direction (R1) of the groove portion 18 is the shape of the end portion 3 on the large diameter side from the direction of the inner peripheral surface of the thick portion (the groove opening position near the top portion 17c of the thick portion structure 17a). It is formed so as to be narrow in the outer diameter direction. The groove width at the groove opening position is indicated by W1, and the groove width near the outer diameter of the large-diameter side end 3 is indicated by W2 (see FIGS. 4, 7, and 8). In this embodiment, it is formed in a slightly narrow shape, but is not limited to that shape, and may be formed in an extremely narrow shape, and the width from W1 to W2 is also possible. The design is changeable within the scope of the present invention.

The groove width W3 in the boot axis direction between the

opposed skirts

17b and 17b is formed narrower than the groove width W4 in the boot axis direction between the opposed

top parts

17c and 17c (see FIG. 5). .
In this embodiment, by forming the axial width (thickness) of the skirt part 17b of each thick part structure 17a larger than the axial width (thickness) of the top part 17c, the groove width W3 and The relationship of W4 is formed. Thus, by increasing the axial width (thickness) of the skirt portion 17b, the rigidity of the top portion 17c with respect to the skirt portion 17b can be reduced, that is, softened. Thereby, the adhesiveness of the lip | rip part mentioned later can be improved and the grease leak prevention effect can be improved.

In addition, the groove part 18 should just be provided at least 1 or more, and it is not limited to the arrangement | positioning number. Moreover, in this embodiment, although it forms in the groove shape continuous in the circumferential direction, even if it forms intermittently, it is in the scope of the present invention.

As shown in FIGS. 1 to 8, the inner peripheral surface of the large-diameter side end portion 3 has a surface (the inner peripheral surface of the thick portion) of each thick portion constituent body 17a of the thick portion 17 described above. ) And the lip disposed in parallel in the circumferential direction over the surface of the thin portion 19 (inner peripheral surface of the thin portion) and in contact with the outer peripheral surface of the outer casing including the recess to seal the boot inner region. Portions (seal lips) 21a and 21b are provided.
The lip portions (seal lips) 21a and 21b seal the boot inner region to prevent grease leakage and prevent entry of dust, muddy water, and the like.
That is, two lip portions (seal lips) 21a, 21b are formed in parallel, and each lip portion (seal lip) 21a, 21b is in the boot shaft direction (direction indicated by arrow S1 in the figure). In FIG.
The lip portions (seal lips) 21a and 21b are formed as ridges whose cross-sectional shapes are, for example, substantially triangular or trapezoidal. Although not shown, the crests of the tops of the lip portions (seal lips) 21a and 21b are rounded.
In this embodiment, an example in which two lip portions (seal lips) 21a and 21b are provided is shown. However, the number and shape of the lip portions are not limited, and one or three or more lip portions may be designed. It can be changed.

Here, it is as follows when the thick part 17 of this embodiment and the thick part in the boot disclosed by the said patent document 2 are compared based on FIG.
FIG. 8A is a view when the thick portion 17 of the present embodiment is fastened and fixed to the axial groove 201 of the outer casing 200 via the fastening band 300, and FIG. 8B is a view of the boot disclosed in Patent Document 2. The figure when the thick part is fastened and fixed to the axial groove 201 of the outer casing 200 via the fastening band 300 is shown.
In order to help understand the difference, the thick portion 17 of the present embodiment and the thick portion of Patent Document 2 are substantially the same, and only the arrangement position of the groove portion 18 is changed. The thick portion of Patent Document 2 will be described with the same reference numerals as in the present embodiment.

In the case of this embodiment, the area of the band fastening part 37 that the fastening band 300 contacts is A, the solid area directly below the band fastening part 37 is B, the area where the groove part 18 is provided is C, and the lip part 21a (21b) Define the region as D.
On the other hand, in the case of the thick portion disclosed in Patent Document 2, the region of the band fastening portion 37 with which the fastening band 300 is in contact is A, the region immediately below the band fastening portion 37, and the region where the groove portion 18 is provided is B, A solid region between the groove portion 18 and the

lip portions

21a and 21b is defined as C, and a region of the lip portions 21a and (21b) is defined as D.

In the case of this embodiment, the tightening force applied to A by the tightening of the tightening band 300 is transmitted from A to C via C. Here, since B is constituted by a solid region, the clamping force is transmitted to C almost as it is. Since C has a small cross-sectional area (volume that can receive a load) due to the presence of the groove portion 18, the tightening force transmitted to the base portion of C is D, that is, the lip portion 21a (21b). ) Is transmitted in a concentrated manner. Furthermore, since C has a lower rigidity and can be elastically deformed than B which is a solid region, C can elastically apply the tightening force transmitted to B to D.
Furthermore, since the area C has a configuration in which the area (cross-sectional area) gradually decreases toward the lip portion 21a (21b) and adopts a configuration that gradually deforms toward the top portion, traveling vibration Even if the outer casing of the tripod joint, which is a mating member that the lip portion 21a (21b) contacts and seals, is slightly shaken by vibrations or the like, the adhesion of the lip portion 21a (21b) can be maintained. .

On the other hand, in the case of the thick part of the boot disclosed in Patent Document 2, the tightening force applied to A is transmitted from A to B to C by tightening of the tightening band 300. Here, since the groove portion 18 that opens in the outer diameter direction is formed in B, the cross-sectional area (volume that can receive a load) is small, so B deforms and absorbs the tightening force, The tightening force transmitted from A to B is reduced. That is, the tightening force transmitted from A in the region B is lost. Further, since the region C is solid and has a large area (volume that can receive a load), the region C is difficult to deform (cannot be greatly reduced in diameter) with a small tightening force transmitted via B. Therefore, the tightening force is not concentrated on the lip portion 21a (21b) existing in the region D, and the pressing force against the outer casing of the tripod joint which is the counterpart member is small. If the housing is displaced, the adhesion may not be maintained.
Therefore, in the case of this embodiment according to the present invention, a sufficient tightening force can be elastically applied to the outer casing of the tripod joint that is the counterpart member, so that a decrease in the tightening force can be prevented and good It can be set as the structure which can maintain a favorable sealing performance.

Further, when the groove 18 is molded, the groove 18 is formed so that the width W1 on the opening side is larger than the width W2 on the inner bottom side in consideration of the ease of punching. Therefore, in the case of Patent Document 2, since the area of B is further reduced, the deformation of the region B is increased and the loss of force is increased, so that the sealing performance is lowered. On the other hand, according to the present embodiment, since the opening side of the groove portion 18 having the large width W1 is formed closer to the lip portion 21a (21b), the areas of B and C are conversely increased and the sealing performance is improved. Will be.

Therefore, in the case of Patent Document 2, the groove portion 18 exists in the region B as described above, and the band fastening force is greatly lost due to the large deformation in this region, and the band fastening is performed up to the lip portion 21a (21b). In the case of this embodiment, the area gradually increases from the area A near the fastening band 300 to the area D where the lip portion 21a (21b) exists. Since a configuration in which is small is employed, the force concentrates on the lip portion 21a (21b), and the lip portion 21a (21b) can be deformed. Furthermore, since the band tightening force applied to the lip portion 21a (21b) can be appropriately adjusted by the region C, that is, the size (width W1, W2), depth, and shape of the groove, the sealing performance is extremely high. The effect can be expected.

According to the present embodiment, as described above, the sealing performance can be improved and the product weight of the entire boot can be reduced, so that the initial problem can be sufficiently achieved, and the needs of the customers can be sufficiently met. .
Further, by changing the circumferential width of the groove portion 18 between the width W4 of the central region (region between the

top portions

17c and 17c) of the groove portion 18 and the width W3 between the

skirt portions

17b and 17b, the lip portion (seal

lip

21a , 21b), the band tightening force can be appropriately adjusted, so that an effect of extremely high sealing performance can be expected.
Furthermore, by providing the groove portion 18 in the thick portion 17, the material volume is less biased between the thick portion 17 and the thin portion 19, so that the difference in shrinkage during molding can be reduced, and the problem of shrinkage (sinking) also occurs. Hard to occur.
Further, since the groove portion 18 is provided in the thick portion, it is possible to reduce the amount of resin material used and the manufacturing cost.

Further, as shown in FIG. 6A, the groove 18 has a rib that spans between the axially opposed inner wall surfaces 17d and 17d of the pair of thick

portion constituting bodies

17a and 17a constituting the groove 18. It is possible to adopt a configuration in which (support wall) 20 is provided.

By bridging the ribs 20 in this way, the strength of the thick portion 17, that is, the thick

portion constituting bodies

17a and 17a can be maintained, and unexpected deformation can be suppressed.
Although the rib 20 is not particularly limited, the size of the rib 20 can be changed within a range in which the weight of the entire boot can be reduced, and a plurality of ribs 20 are provided at predetermined intervals in the circumferential direction in the groove 18. It is also possible to arrange. Further, in the present embodiment, the rib 20 is integrally formed at the same time as the thick portion 17 is formed by the manufacturing method described later. However, the rib 20 can be formed separately and bonded and fixed in the groove portion 18. Is within the range.
The rib 20 can be formed to have a larger width on the base end side (bottom surface side in the groove) than the width on the tip end side (groove opening side).

In the present embodiment, the outer wall 17e of the thick part structure 17a positioned inward in the axial direction and the outer wall 17f of the thick part structure 17a positioned outward in the axial direction. Although ribs for preventing the collapse of the respective thick-walled parts 17a are not provided, they can be provided, and the design can be changed within the scope of the present invention.
Since other configurations and operational effects are the same as those in FIG. 5, the same portions are denoted by the same reference numerals and the description thereof is omitted.

The width (thickness) in the axial direction S1 of the thick-walled component 17a is not particularly limited, but it is at least self-supporting and formed so as to have shape retention during band tightening. preferable.
FIG. 6B and FIG. 6C are other embodiments, and the width (thickness) in the axial direction S1 of the thick part structure (base) 17a is configured to be thicker than in FIG. 5 and FIG. 6A. An embodiment is shown.
6B and 6C, the axial width of the base end portion continuous with the inner peripheral surface of the large-diameter side end portion 3 is shown in FIGS. 5 and 6A. It is configured to be thicker than the form of the thick part structure (base) 17a.
In the present embodiment, the convex portion 22 is integrally provided continuously with the thick-walled component (base) 17a on the back side (inner side in the axial direction), and the convex portion 22 is closest to the end portion on the large diameter side. It is provided toward the inner surface direction of the small diameter portion 7b. Further, in the present embodiment, a part of the convex portion 22 is stealed within a predetermined range to reduce the weight (in the drawing, reference numeral 22a indicates a meat stealing portion).
Since other configurations and operational effects are the same as those in FIGS. 5 and 6A, the same reference numerals are given to the same portions, and descriptions thereof are omitted.

There is no particular limitation on the thermoplastic resin constituting the preform formed from the large-diameter side end 3, the small-diameter side end 5 and the bellows portion 7, and the secondary molded portion 13 composed of portions having different thicknesses. The most suitable material is selected within the range, and the same material, different materials, or different materials are within the scope of the present invention. It should be noted that a portion having a different thickness as the secondary molded portion 13 is preferably made of a material having good sealing properties, while the preform is a material that is purely intended, that is, flexibility, heat resistance, cold resistance, etc. Can be selected.

Description of [Constant Velocity Joint Boot Manufacturing Apparatus] Here, an embodiment of a manufacturing apparatus used for manufacturing the constant velocity joint boot of the present invention will be described.

The schematic structure of the die 49, which is the main part of the manufacturing apparatus for manufacturing the constant velocity joint boot of the present invention, will be described. As shown in FIGS. 9 to 14, the main part of the apparatus is for injection molding. The mold 49 has a holding mold (split mold) 51 constituting the movable platen side, and a core die 69 provided on the fixed platen 49a side.

As shown in FIG. 14, a contour 57 is formed on the inner surface of the holding mold (split mold) 51 so that the external shape of the preform is in close contact (holding the outer surface of the preform). When the (split mold) 51 is clamped, a preformed product accommodation space 55 that matches the external shape (outer contour) of the boot 1 is formed.
In this preformed product accommodation space 55, the opening edge 59 of the outer peripheral surface 15 of the large-diameter side end 3 of the preformed product accommodated in the preformed product accommodation space 55 at the time of clamping is a holding mold (split mold). It is formed so as to be located on the same plane as the lower end surface 51 a of 51.

As shown in FIG. 14, a gate 47 for injecting a thermoplastic resin through a runner 45 is formed in the fixed plate 49 a of the mold 49 in the secondary molding space 43. In the present embodiment, the gate 47 is provided by selecting any one place or a plurality of places in the thin portion molding space 43b. That is, if a thermoplastic resin injection (injection) point for secondary molding is provided at any one or a plurality of locations in the thin portion molding space 43b in the secondary molding space 43, from the injection gate 47 to the thick portion molding space 43a. The thin part molding space 43b serves as a narrow runner, and the molten material is sent to the thick part molding space 43a instantly at a high speed and high temperature while maintaining a high temperature state, so there is no occurrence of welds or air entrainment. The inner surface of the large-diameter side end portion 3 of the preform and the outer surface of the secondary molded portion 13 are welded.
Of course, the gate 47 may be provided with any one or more locations of the thick portion molding space 43a, or any one or more locations including the thin portion molding space 43b and the thick portion molding space 43a. There is no problem to select and prepare, and it can be set.
The gate 47 may be provided in the thick part molding space 43a, and the thermoplastic resin may be injected from only the thick part molding space 43a or from a plurality of locations including the thick part molding space 43a. From the standpoint of preventing defects, it is preferable to provide the gate 47 in the thin portion molding space 43b as in this embodiment.

The core die 69 is formed between the upper projecting

portions

74 and 81a capable of contacting the inner peripheral surface of the bellows portion 7 or the inner peripheral surface of the large-diameter side end portion 3, and the inner peripheral surface of the large-diameter side end portion 3. The lower

peripheral surface portions

76a and 81c for forming the secondary molding space 43 for forming the secondary molded portion consisting of a plurality of thick portions and a plurality of thin portions, and the lower

peripheral surface portions

76a and 81c, a core mold Of the core mold 69 corresponding to the thick portion molding space 43a that constitutes the secondary molding space 43. The lower projection 81b is provided so as to be slidable in the direction of the central axis of 69. The upper projecting portion 81a and the lower projecting portion 81b are configured to be able to advance toward the thick portion molding space 43a and to be retracted toward the central axis direction of the core die 69.

As shown in FIGS. 9 to 14, the core die 69 is provided at the center, is configured to be horizontally rotatable about the center axis, and is configured as a rotary piece 89 (cam member) that functions as an operation unit. 99), a first mold part (base part) 70 forming a thin part forming space 43b provided alternately in the circumferential direction around the rotary piece part 89 (cam member 99), and a thick part forming space The whole is formed in a disk shape having a desired thickness by the second mold part 79 forming 43a.
Further, the outer peripheral diameter of the core die 69 is designed so as to constitute the inner diameter of the secondary molding portion formed on the inner surface of the large-diameter end portion 3 of the preform. In addition, let the internal diameter of this secondary shaping | molding part be a diameter fitted to the outer casing outer diameter of the tripod joint used as attachment object.

As shown in FIGS. 9 to 14, the first mold part 70 is substantially fan-shaped in plan view, and at least in the direction of the small-diameter side end part 5 from the small-diameter part 7 b closest to the large-diameter side end part 3 of the preform. A front end surface (upper end surface in FIG. 10) 71 positioned in the outer diameter direction from the inner surface of the small diameter portion 7b, and a lower end surface (lower end surface in FIG. 10) located on the same plane as the large end end surface 3a. ) It has a thickness of 72.
Three pieces are provided at a desired interval in the circumferential direction with the rotary piece portion 89 as the center, and the inner surface of the small diameter portion 7b closest to the large diameter side end portion 3 of the preform is fitted to the outer periphery on the upper end side. A concave circumferential groove (upward projecting portion) 74 is provided, and an outer peripheral surface 76 from the peripheral edge 75 on the molten material injection side to the lower end surface 72 of the concave circumferential groove (upward projecting portion) 74 has a large diameter of a preformed product. A surface portion (lower peripheral surface portion) 76a that forms the inner surface shape of the thin portion 19 formed between the inner peripheral surface of the side end portion 3 is provided.

Between the adjacent

first mold parts

70, 70, a second mold part sliding groove 90 is provided in which the second mold part 79 can slide (slidably move) in the radial direction (horizontal direction). (See FIG. 13).

In the second mold portion sliding groove 90, two

interior plate portions

91, 91 that are horizontally spanned across the opposed groove

inner surfaces

90 a, 90 a are arranged at a predetermined interval in the vertical direction.
The interior plate portion 91 is formed with a curved surface in which the rear surface 91a facing the rotary piece portion 89 disposed in the center of the core mold is a flat surface and the front surface 91b facing the thick portion molding space 43a is recessed in the direction of the rear surface 91a. (See FIG. 13).

The two

interior plate portions

91 and 91 are used to form the thick portion constituent bodies (bases) 17a and 17a constituting the thick portion 17, and the second mold portion 79 is the thick portion. When it moves in the direction of the molding space 43a, it is housed in two

deep grooves

93, 93 that are recessed inwardly from the tip of the downward projecting portion 81b of the second member 92 of the second mold portion 79.
When the

interior plate portions

91 and 91 are housed in the two

deep grooves

93 and 93, the

interior plate portions

91 and 91 are located between the front surface (curved surface portions) 91 b and 91 b of the plate portions and the

openings

93 a and 93 a of the

deep grooves

93 and 93. The groove

inner side surfaces

90a, 90a are provided at predetermined positions so that predetermined cavities (forming spaces) 110, 110 for molding the thick part constituting body (base) 17a are formed.

As shown in FIGS. 9 to 14, the second mold part 79 is disposed in the second mold part sliding groove 90 between the adjacent

first mold parts

70, 70. It is configured to be slidable in the direction of the central axis of the core die 69 or to be slidable in the direction of the thick portion molding space 43a in accordance with the left and right rotation operation of the rotary piece 89 on the fixed portion 80 provided integrally. Has been.

The second mold part 79 has a width disposed between the adjacent

first mold parts

70 and 70 and is configured to have the same thickness as the first mold part 70 (the thickness in the vertical direction). Three pieces are provided in the circumferential direction around the piece portion 89.
The second mold part 79 is composed of a first member 94 and a second member 92 arranged in the vertical direction. In the present embodiment, the first member 94 and the second member 92 are integrally molded, and the second mold part 79 rotates. A sliding surface portion 95 formed in an arc shape in plan view is provided on the side facing the piece portion 89 (cam member 99), and an outer periphery composed of an upper protruding portion 81a and a lower protruding portion 81b is provided on the opposite surface. A surface 81 is formed.

The second mold portion 79 is internally provided with a core material 79a erected in the vertical direction. The core material 79a is connected to a core material 89a provided in a rotary piece portion 89 (cam member 99) described later. A tension spring 96 is stretched between them and is biased so as to be pulled toward the center of the core die 69. That is, each of the three second mold parts 79 is stretched in the center direction of the core mold 69 by the tension springs 96 being spanned between the core members 89 a housed in the rotary piece 89 (cam member 99). It is energized to be.

When the second mold part 79 is pushed out by the rotary piece part 89 and protrudes into the thick part molding space 43a, the first member 94 and the circumferential direction of the concave circumferential groove 74 of the first mold part 70 The upper member 81 is provided with an upper protruding portion 81a provided on the outer peripheral surface of the upper end side, and the second member 92 has a groove portion recessed in the radial direction from the inner peripheral surface side of the thick portion 17. A downward projecting portion 81b is provided on the lower peripheral surface portion 81c as a groove forming die surface for forming.

The downward projecting portion 81 b projects between the two

deep grooves

93 and 93 that are recessed inward from the tip of the second member 92 of the second mold portion 79, and the two

deep grooves

93 and 93. A groove forming plate member 97 having a predetermined thickness is provided.
As described above, the two

deep grooves

93 and 93 together with the two

interior plate portions

91 and 91 provided in the second mold portion sliding groove 90 form thick-walled components (bases) 17a and 17a. The groove portion forming plate member 97 passes between the two

interior plate portions

91, 91 provided in the second mold portion sliding groove 90, and is a thick portion. It protrudes and is provided in the molding space 43a, and is used for forming the groove portion 18 between the thick

portion constituting bodies

17a and 17a.

The second mold part 79 constituted by the first member 94 and the second member 92 slides in the direction of the thick part forming space 43a by the rotation operation of the rotary piece part 89 (cam member 99) in the left-right direction. Then, together with the concave circumferential groove 74 of the first mold portion 70, the inner surface of the small diameter portion 7b closest to the large diameter side end portion 3 is fitted into the concave circumferential groove 85, and the downward projecting into the thick portion molding space 43a. The portion 81b can be protruded, or can be slid in the central axis direction of the core die 69 and retracted from the thick portion forming space 43a.

The rotary piece 89 is composed of a core material 89a and a cam member 99 attached to the core material 89a. The core material 89 a is erected in the vertical direction at the approximate center of the core die 69 and is disposed at the center of the cam member 99.

The cam member 99 is formed in a substantially triangular prism shape having a deformed triangular shape in a plan view, and has three concave

side surface portions

99a, 99a, 99a each having a gently curved surface in which each central region is recessed in a plan view. And three convex

side surface portions

99b, 99b, 99b formed between the concave side surface portions 99a.
Further, the top surface of the cam member 99 is provided with a projecting portion 100 in which a locking groove portion 100a for locking the locking arm portion 101a of the operation member 101 is recessed.
That is, by rotating the rotary piece 89 (cam member 99) in the horizontal direction in either the left or right direction around the central axis of the core die 69, the sliding surface portion 95 of the second die portion 79 is It slides linearly in the horizontal direction along the convex side surface portion 99b and the concave side surface portion 99a.
For example, in the present embodiment, when the rotary piece 89 (cam member 99) is rotated to reach a position where the convex side surface 99b presses the sliding surface 95 of the second mold 79, the second mold 79 is obtained. Is slidably moved (moved forward) so that the lower protruding portion 81b is positioned in the thick portion forming space 43a, and the second die portion is rotated by rotating the rotary piece 89 (cam member 99) in the opposite direction. 79 is a downward projecting portion provided on the lower end side outer peripheral surface of the tip of the second member 92 by the sliding spring 95 moving along the sliding side surface 99a from the convex side surface 99b to the concave side surface 99a by the tension spring 96. 81b is retracted from the thick portion 17 region.

The operation member 101 is a desired rotatable member having a trident locking arm portion 101a at the tip, and the locking arm portion 101a is recessed on the top surface of the projection 100 of the cam member 99. It is engaged with the three-pronged locking groove 100a and rotated by a predetermined angle in the horizontal direction in either the left or right direction, in this embodiment, about 60 degrees. The operation member 101 is not limited to the present embodiment, and any operation member 101 having a configuration capable of rotating the cam member 99 by a predetermined angle in a predetermined direction can be selected as appropriate within the scope of the present invention. is there. Further, the operation member 101 may be a manual type or may be configured to automatically rotate through power.
It is also possible to automatically rotate the cam member 99 by providing a predetermined power source in the lower region of the cam member 99.

[Description of manufacturing method using constant velocity joint boot manufacturing equipment]
Next, the manufacturing method (manufacturing process) of the constant velocity joint boot of the present invention using the manufacturing apparatus described above will be described.
FIG. 14 is a schematic diagram showing an embodiment of the overall flow of a method for manufacturing a constant velocity joint boot using the manufacturing apparatus (core die 69).

The manufacturing method of the present embodiment is configured by “preliminary molding process” → “secondary molding process” → “boot drawing process”.

"Preliminary molding process"
Blow molding, injection blow molding, and the like are well known as a molding method for the preform including the large-diameter side end portion 3, the small-diameter side end portion 5 and the bellows portion 7 described above. An optimal molding method is appropriately applied within the scope of the invention.

"Secondary molding process"
In this step, the core die 69 is inserted into the large-diameter side end portion 3 of the preform formed by the preforming and held in the injection mold 49, and the desired shape is put in the mold 49. By injecting the molten material, the secondary molded portion 13 composed of the thick portion 17 and the thin portion 19 is formed between the inner surface of the outer peripheral surface 15 of the large-diameter side end portion 3 of the preform and the outer surface of the core die 69. It is an integral molding. In addition, since a known configuration is applied to a configuration other than the configuration described below, the description thereof is omitted.

The secondary molding process includes (1) a process of forming a secondary molding space and (2) a process of molding a secondary molding part.

“(1) Process of forming secondary molding space”
For example, first, the preform is placed on the outer periphery of the core die 69 provided in advance on the fixed platen 49 a side so that the inner circumference of the large-diameter side end 3 of the preform is located. (FIG. 14A).
Next, a preformed product provided with the large-diameter end 3 attached to the outer periphery of the core die 69 as described above is clamped with a holding die (split die) 51 to close the inside of the die 49. (FIG. 14B).
At this time, the core die 69 locks the three-pronged locking arm portion 101a of the operation member 101 to the three-pronged locking groove portion 100a provided in the projection portion 100 of the rotary piece 89 (cam member 99), Then, by rotating the rotary piece 89 (cam member 99) in a predetermined direction (either left or right) by a predetermined angle (60 degrees in this embodiment), the convex side surface of the rotary piece 89 (cam member 99) is rotated. When the part 99b reaches a position where it presses the sliding surface part 95 of the second mold part 79, the second mold part 79 enters the thick part forming space 43a with the downward projecting part 81b (

deep groove

93, 93, groove part forming plate member). 97) slide to move (forward movement).

When the holding mold (split mold) 51 is clamped in this way, as shown in FIG. 14 (b), the entire outer surface of the small-diameter portion 7b near the large-diameter side end 3 of the bellows portion 7 is used for holding. The protrusions 53 on the inner surface of the mold (split mold) 51 are fitted, and the concave

circumferential grooves

74 and 85 of the core mold 69 are fitted over the entire inner surface of the small-diameter portion 7b, and the holding mold (split mold). The small-diameter portion 7 b is sandwiched between the convex line 53 of 51 and the concave

circumferential grooves

74 and 85 of the core die 69.

By going through such a process, the inner peripheral surface of the large-diameter side end portion 3 is thicker between the inner peripheral surface of the large-diameter side end portion 3 of the preform and the outer

peripheral surfaces

76 and 81 of the core die 69. A secondary molding space 43 for molding the secondary molding portion 13 portion composed of the meat portion 17 and the thin portion 19 is formed.
That is, in the present embodiment, the secondary molding space 43 is formed with a thick portion forming space 43 a between the outer peripheral surface 81 of the second mold portion 79 of the core die 69 and the inner peripheral surface of the large-diameter side end portion 3. Then, a thin portion forming space 43b communicating with the thick portion forming space 43a is formed between the outer peripheral surface 76 of the first mold portion 70 of the core die 69 and the inner peripheral surface of the large diameter side end portion 3. .
When the second mold part 79 moves in the direction of the thick part molding space 43a, two deep grooves recessed inwardly from the tip of the downward projecting part 81b of the second member 92 of the second mold part 79 93, 93 accommodates two

interior plate portions

91, 91 provided in the second mold portion sliding groove 90, respectively, and the interior plate portion front surfaces (curved surface portions) 91a, 91a and the

deep grooves

93, 93 Predetermined cavities (molding spaces for the thick portion structure 17a) 110, 110 for molding the thick portion structure (base) 17a are formed between the

openings

93a, 93a.
At this time, the groove forming plate member 97 provided between the two

deep grooves

93 and 93 passes between the two

interior plate parts

91 and 91 and protrudes into the thick part forming space 43a. Prepared.
In addition, this process mentioned above is only an example, and it is also possible to employ | adopt other processes other than this process within the scope of the present invention, and the design can be changed as appropriate.

“(2) Process of forming the secondary molding part”
First, a molten material injection point for secondary molding is positioned at any one or a plurality of locations in the thin portion molding space 43b in the secondary molding space 43 formed by the above-described process.
Then, through the injection point, for example, a thermoplastic resin heated and melted at a high temperature of 260 ° C. or higher is injected and injected into the secondary molding space 43 at a high speed, and the large-diameter side end portion 3 of the preformed product is injected. The secondary molding part 13 part which consists of the thick part 17 and the thin part 19 is integrally molded by the inner peripheral surface of this.
That is, the molten material injected from the thin part molding space 43 b flows into the thick part molding space 43 a, and the two

deep grooves

93, 93 provided on the tip surface of the second mold part 79, and the second mold part slide A predetermined cavity (molding space for the thick part structure 17a) for molding the thick part structure (base) 17a formed by the two

interior plate parts

91, 91 provided in the moving groove 90 The molten material enters 110 and 110, and the thick

portion constituting bodies

17 a and 17 a and the groove portion 18 are integrally formed.
Note that, as described above, the thermoplastic resin to be injected is, for example, 260 ° C. or higher, but is not particularly limited, and the design can be changed as appropriate within a range in which no problem occurs in the material.

"Boot extraction process"
By the secondary molding step, the boot 1 is formed by integrally molding the secondary molded portion 13 including the thick portion 17 and the thin portion 19 on the inner peripheral surface of the large-diameter side end portion 3 of the preform (see FIG. 1).
As shown in FIG. 4, the thick portion 17 on the inner surface of the large-diameter end portion 3 of the boot 1 formed as described above is a thick portion constituting body 17 a serving as an undercut portion protruding in the boot axial direction. , 17a are provided.

Before the core die 69 and the boot 1 are separated, the trident locking arm portion 101a of the operation member 101 is provided on the protrusion 100 of the rotary piece 89 (cam member 99). When the rotary piece 89 is rotated by a predetermined angle (in this embodiment, 60 degrees) in a predetermined direction (either left or right), the second mold portion 79 is projected by the tension spring 96. The lower protrusion 81b provided on the outer peripheral surface on the lower end side of the tip of the second member 92 is moved from the thick portion 17 region by sliding (moving backward) while the sliding surface portion 95 extends along the concave side surface portion 99a from the concave side surface portion 99b. Evacuate (FIG. 14 (e)).

As a result, when the thick portion 17 is pulled out of the core die 69, the core portion that is caught by the thick

portion constituting bodies

17a, 17a, which are the undercut portions of the thick portion 17, is eliminated. 1 is pulled out and separated (FIG. 14F).

As described above, according to the present embodiment, the surfaces in contact with the thick

portion constituting bodies

17a and 17a that are so-called undercut portions are retracted in the direction of the central axis of the core die 69 when the boot 1 that is a molded product is pulled out. Therefore, it is easy to pull out the boot 1 as a molded product from the core die 69, and so-called unreasonable removal can be prevented.
In addition, this invention is not limited by embodiment mentioned above, A change can be suitably added within the scope of the invention.

"Second embodiment"
FIG.15 and FIG.16 shows other embodiment of the core type | mold used for the manufacturing method of the boot for constant velocity joints of this invention.

The core mold 69 is composed of a plurality of (same as in the first embodiment) first mold part 70 and a plurality of (same as in the first embodiment) second mold part 79. Therefore, the configuration of the second mold portion 79 is different from that of the core mold 69 of the first embodiment.
Therefore, the second mold part 79 will be described here, and the description of the first mold part 70 will be omitted.

The second mold part 79 includes a first member 94 and a second member 92, and the first member 94 and the second member 92 are configured to perform separate and independent operations.
In the present embodiment, the upper region divided into two by the groove ceiling surface position 93b constituting the deep groove 93 in the vertical direction in the second mold part 79 of the first embodiment is the first member 94, and the lower region is the second member. 92 (see FIG. 15).

The first member (first rectilinear advance / retreat member) 94 is configured to be movable forward and backward by the cam member 99 of the rotary piece portion (rotating core) 89, as in the first embodiment. The core mold central axis side surface) is provided with an arc-shaped sliding surface portion 95, and the opposite tip surface is a concave shape that fits the inner surface of the small diameter portion 7b in the immediate vicinity of the large diameter side end portion 3 of the preform. A circumferential groove 85 is provided on the outer peripheral surface on the upper end side. The concave circumferential groove 85 communicates with the concave circumferential groove 74 of the first mold part 70 in the circumferential direction.
Similar to the first embodiment, the first member 94 is always urged by a tension spring 96 so as to be pulled toward the central axis of the core die 69. One end of the tension spring 96 is connected to a core member 94 a of the first member 94, and the other end is connected to a shaft portion 120 provided substantially at the center of a later-described rotary piece 89.

The rotary piece portion 89 includes a shaft portion 120 and a cam member 99 attached to the shaft portion 120.

The shaft portion 120 includes a cylindrical shaft portion 121, a disk-shaped pressing portion 122 that is integrally formed with the upper end of the cylindrical shaft portion 121, and a disk-shaped contact portion 123 that is integrally formed with the lower end of the cylindrical shaft portion 121. In the through hole 111 provided in the vertical direction at the approximate center of the rotary piece 89 at the approximate center of the core die 69, the core 130 is inserted in a vertically slidable manner. Is provided upright on the top surface 130a.
The contact portion 123 at the lower end of the shaft portion 120 may or may not be fixed to the top surface 130a of the vertically elevating core 130. Further, the vertical length of the shaft portion 120 is such that the pressing portion 122 is removed from the top surface of the rotating piece portion 89 (the top surface of the projecting portion 100) when the vertical elevating core 130 is raised (when not pressed). Is set to a length that allows the pressing portion 122 to be accommodated inside the top surface of the rotating piece portion 89 (the top surface of the protruding portion 100) when the vertically moving core 130 is lowered (pressed). Has been.

side surface portions

99b, 99b, 99b formed between the concave

side surface portions

99a, 99a, 99a.
Further, the top surface of the cam member 99 is provided with a projecting portion 100 in which a locking groove portion 100a for locking the locking arm portion 101a of the operation member 101 is recessed.

That is, by rotating the rotary piece 89 in the horizontal direction in either the left or right direction around the central axis of the core die 69, the sliding surface portion 95 of the first member 94 and the convex side surface portion 99b. It slides in a straight line in the horizontal direction along the concave side surface 99a.
For example, in this embodiment, when the rotary piece 89 is rotated to reach a position where the convex side surface 99b presses the sliding surface (arc-shaped surface) 95 of the first member 94, the first member 94 slides. It moves (moves forward), and the concave circumferential groove 85 at the tip engages the inner surface of the small diameter portion 7b in the immediate vicinity of the large diameter side end portion 3, and the other tip side surface portion is a thick portion molding space. 43a. Further, when the rotary piece 89 is rotated in the opposite direction, the first member 94 is slid (reversely moved) by the tension spring 96 while the sliding surface portion 95 extends from the convex side surface portion 99b to the concave side surface portion 99a. Then, the first member 94 is retracted from the thick portion 17 region.

The second member (second rectilinear advance / retreat member) 92 is configured to be constantly biased toward the center of the core die 69 by the tension spring 140.
Then, the second member 92 is moved forward and backward by a vertical lifting operation of a vertical lifting core (straight forward core) 130 that is constantly pushed upward in the vertical direction by a lifting spring 150 disposed below. Is configured to do. One end of the tension spring 140 is connected to a core member 118 projecting from the lower surface of the second member 92, and the other end is coupled to a projecting portion 160a projecting integrally at a substantially center of a base core 160 described later.

For example, the rear surface of the second member 92 (the surface facing the central axis of the core die 69) 92a is formed in a taper shape, and the upper region 130b on the side circumferential surface of the vertical elevating core 130 facing the rear surface 92a is formed. When the upper and lower elevating core 130 is lifted by the push-up spring 150, the second member 92 is slid and moved by the tapered upper region 130b. The forward movement is performed, and the tip end face is positioned in the thick part forming space 43a.
A lower protrusion 81b for forming a groove is formed on the front end surface of the second member 92, and the lower protrusion 81b for forming a groove is recessed from the front end of the second member 92 inward. Two

deep grooves

93, 93 and a groove forming plate member 97 having a predetermined thickness protruding between the two

deep grooves

93, 93 are provided.
As with the first embodiment, the two

deep grooves

93, 93 are formed with the thick part structure (base) 17a, together with the two

interior plate parts

91, 91 provided in the second mold part sliding groove 90. 17a, and the groove forming plate member 97 passes between the two

interior plate portions

91 and 91 provided in the second mold portion sliding groove 90. It protrudes and is provided in the thick part forming space 43a, and is used for forming the groove part 18 between the thick

part constituting bodies

17a and 17a.
When the up / down raising / lowering core 130 is pushed down against the pushing-up spring 150, the second member 92 slides and moves backward by the tapered upper region 130b, and the tip end surface is thick. It is retracted from the part forming space 43a.

In order to rotate the cam member 99 and move the first member 94 forward and backward, the tip locking arm portion 101a of the operation member 101 is locked in the locking groove 100a of the protrusion 100 and rotated. Further, when the second member 92 is moved back and forth, it is necessary to move the vertical elevating / lowering core 130 up and down. However, when the vertical elevating / lowering core 130 is pushed down against the push-up spring 150, The operation is performed by pressing the shaft portion 120, which is erected with the contact portion 123 in contact with the top surface of the core 130, with the operation member 101. Since the shaft portion 120 has a pressing portion 122 at its upper end protruding above the protruding portion 100 of the cam member 99, the pressing portion is at the lower end of the operation member 101 (the surface portion on which the locking arm portion 101 a is provided). This is done by pressing 122 down.

In the present embodiment, the push-up spring 150 is disposed in the accommodation space 161 having an open top surface recessed in the base core 160 disposed below the core mold 69 in the vertical direction. The up / down raising / lowering core 130 is formed in a cylindrical space having a size capable of moving up and down. Further, although a coil spring as shown in the figure is assumed as a member for raising and lowering the vertical raising and lowering core 130, the invention is not limited to this, and other spring members such as leaf springs are used. The design can be changed within the scope of the invention, and a push-up member made of a rubber material or a synthetic resin material having high resilience can be employed instead of the spring member.

The operation member 101 is a desired rotatable member having a locking arm portion 101 a at the tip, and the locking arm portion 101 a is recessed in the top surface of the protruding portion 100 of the cam member 99. It is engaged with 100a and rotated by a predetermined angle in the horizontal direction in either the left or right direction, in this embodiment, about 60 degrees. The operation member 101 is not limited to the present embodiment, and has a configuration in which the cam member 99 can be rotated by a predetermined angle in a predetermined direction, and the shaft portion 120 can be pressed. Any material can be used as long as it is within the scope of the present invention. Further, the operation member 101 may be a manual type or may be configured to automatically rotate through power.

In addition, in each embodiment mentioned above, although the upper protrusion parts 74 and 81A of the core type | mold 69 are employ | adopted the structure which abuts on the small diameter part 7b nearest the large diameter side edge part 3 (fitting), for example, By adopting a core die 69 having an abutting flange (not shown) at the top, as shown in FIG. 17, the inner surface 8a of the inclined portion 8 and the upper surface 14 of the secondary molding portion 13 (in FIG. 17, the thin portion 19). It is also possible to provide a boot for a constant velocity joint in which a space 16 is formed between the upper surface and the upper surface of the same.

3 Large-diameter side end 5 Small-diameter side end 7 Bellows part 17 Thick part 17a Thick part component 18 Groove part 19

Thin parts

21a, 21b Lip part

Claims

An annular large-diameter end into which the outer casing of the tripod joint is inserted,
An annular small-diameter side end into which a shaft connected to the tripod joint is inserted;
A constant velocity joint boot comprising a bellows part integrally provided in a continuous manner between the large diameter side end part and the small diameter side end part and comprising a large diameter part and a small diameter part arranged repeatedly. There,
A plurality of thick portions formed on the inner peripheral surface of the large-diameter side end portion so as to fit in a plurality of concave portions formed on the outer peripheral surface of the outer casing and project in the boot inner diameter direction, and the plurality of thicknesses A thin wall portion disposed between the meat portions,
On the inner peripheral surface of the thick wall portion and the inner peripheral surface of the thin wall portion, a circumferentially continuous lip portion is formed in contact with the outer peripheral surface of the outer casing including the recess to seal the boot inner region. And
In the thick part, at least one groove part recessed from the inner peripheral surface side in the boot outer diameter direction is formed,
The groove for the constant velocity joint is characterized in that the groove is formed along the circumferential direction of the thick part.
Two or more lip portions are formed,
2. The constant velocity joint boot according to claim 1, wherein at least two of the lip portions are positioned with the groove portion interposed therebetween in the boot axial direction.
The thick-walled portion is an arc shape formed in an upwardly inclined manner from the left and right hem portions toward the top in the circumferential direction of the large-diameter side end when viewed from the bottom surface side of the large-diameter side end. The constant velocity joint boot according to claim 1, wherein the boot is provided.
4. The constant velocity joint according to claim 3, wherein the groove portion is formed so that a groove width in a boot shaft direction in a skirt portion is narrower than a groove width in a boot shaft direction in a top portion of the thick portion. Boots.
2. The groove width in the boot shaft direction is narrower toward the outer diameter direction of the boot than the groove width in the boot shaft direction on the inner peripheral surface of the thick wall portion. 4. The constant velocity joint boot according to any one of 4 above.
The constant velocity joint boot according to any one of claims 1 to 5, wherein the groove portion is provided with a rib facing the boot shaft direction and spanning between inner wall surfaces constituting the groove portion. .
A large-diameter side end portion into which an outer casing of a tripod joint having a plurality of recesses on the outer peripheral surface is inserted, a small-diameter side end portion into which a shaft portion connected to the tripod joint is inserted, and the large-diameter side end portion; A bellows portion formed between the small diameter side end portion and a large diameter portion and a small diameter portion repeatedly arranged on the inner peripheral surface of the large diameter side end portion. A method for manufacturing a constant velocity joint boot comprising a plurality of thick portions formed so as to project to the inner diameter side of the boot so as to conform to the concave portions of the boot and a thin portion disposed between the plurality of thick portions Because
A core mold is disposed in the large-diameter side end portion of a preformed product formed with a small-diameter side end portion and a large-diameter side end portion communicating with the internal space of the bellows portion at both ends, and at least the size of the preformed product is large. Arrange the holding mold on the outer peripheral surface side of the diameter side end,
An upper projecting portion provided in the core mold is brought into contact with an inner peripheral surface of the bellows portion or an inner peripheral surface of the large-diameter side end portion, and an inner peripheral surface of the holding mold is set to the large-diameter portion side end portion. The outer peripheral surface of the
A secondary molding portion comprising a plurality of thick portions and a plurality of thin portions at the large-diameter end between the inner peripheral surface of the large-diameter end of the preform and the lower peripheral surface of the core mold. Forming a secondary molding space for molding,
Injecting and injecting a molten material into the secondary molding space, and molding a secondary molded part composed of a thick part and a thin part at the large-diameter side end of the preform;
Including at least
The upper protrusion corresponding to the thick wall forming space constituting the secondary forming space, and the lower protrusion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold, Retreating in the direction of the central axis of the mold and removing it from the thick part molding space area of the secondary molding space, and separating the core mold and the boot in that state;
A method for manufacturing a boot for a constant velocity joint.
The core mold center axis or an axis parallel to the core mold center axis, either or both of the upper projecting part and the lower projecting part of the core mold corresponding to the thick part molding space constituting the secondary molding space The method for manufacturing a constant velocity joint boot according to claim 7, wherein the cam member is retreated from the thick portion region by driving a cam member that revolves around the center.
The downward protruding part of the core mold corresponding to the thick part forming space constituting the secondary forming space has a groove forming die surface formed in the thick part. The manufacturing method of the boot for constant velocity joints of Claim 7 or 8.
A large-diameter side end portion into which an outer casing of a tripod joint having a plurality of recesses on the outer peripheral surface is inserted, a small-diameter side end portion into which a shaft portion connected to the tripod joint is inserted, and the large-diameter side end portion; A bellows portion formed between the small diameter side end portion and a large diameter portion and a small diameter portion repeatedly arranged on the inner peripheral surface of the large diameter side end portion. The apparatus for manufacturing a constant velocity joint boot having a plurality of thick portions formed so as to project to the inner diameter side of the boot and conforming to the concave portions of the boot, and a thin portion disposed between the plurality of thick portions Because
A holding mold for holding the outer surface of a preformed product formed with a small-diameter side end and a large-diameter side end communicating with the internal space of the bellows part at both ends;
A core mold inserted into the large-diameter end of the preform,
In order to mold a secondary molding part composed of a plurality of thick part forming spaces and a plurality of thin part forming spaces formed between the inner peripheral surface of the large-diameter end of the preform and the outer peripheral surface of the core mold. An injection mechanism for injecting and filling molten material into the secondary molding space of
The holding mold includes an inner peripheral surface capable of contacting the outer peripheral surface of the large-diameter side end,
The core mold has a plurality of thicknesses between an upper projecting portion capable of contacting the inner peripheral surface of the bellows portion or the inner peripheral surface of the large-diameter end, and the inner peripheral surface of the large-diameter end. A lower peripheral surface forming a secondary molding space for forming a secondary molding portion composed of a meat portion and a plurality of thin portions, and a lower portion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold A protrusion, and
The upper projecting portion and the lower projecting portion of the core mold corresponding to the thick portion forming space constituting the secondary forming space can be advanced toward the thick portion forming space, and directed toward the core mold central axis direction. Configured to be evacuated,
An apparatus for manufacturing a constant velocity joint boot.
A cam member that pivots about the core-type central axis or an axis parallel to the core-type central axis;
Either one or both of the upper projecting portion and the lower projecting portion of the core mold corresponding to the thick portion forming space constituting the secondary forming space is directed toward the thick portion forming space by the cam member. The apparatus for manufacturing a constant velocity joint boot according to claim 10, wherein the apparatus can be moved forward and retractable in the direction of the central axis of the core mold.
The downward protruding part of the core mold corresponding to the thick part forming space constituting the secondary forming space has a groove forming die surface formed in the thick part. The apparatus for manufacturing a constant velocity joint boot according to claim 10 or 11.