JPWO2019189603A1 - Constant velocity joint boots Manufacturing method of constant velocity joint boots Manufacturing equipment for constant velocity joint boots - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boot for a constant velocity joint capable of preventing a decrease in a tightening force due to a fastening band and maintaining a sealing performance while reducing the weight of the boot for a constant velocity joint. SOLUTION: The bellows portion 7 is integrally provided integrally between a large diameter side end portion 3 and a small diameter side end portion 5, and an outer casing is provided on the inner peripheral surface of the large diameter side end portion. It has a plurality of thick-walled portions 17 formed by projecting to the inner diameter side in conformity with a plurality of recesses formed on the outer peripheral surface, and a thin-walled portion 19 arranged between the plurality of thick-walled portions. On the inner peripheral surface of the thick portion and the inner peripheral surface of the thin portion, lip portions 21a and 21b continuous in the circumferential direction are formed in contact with the outer peripheral surface of the outer casing including the recess and seal the boot inner region. In the thick portion, at least one groove portion 18 recessed in the radial direction from the inner peripheral surface side toward the outer peripheral surface side of the large diameter side end portion is formed, and the groove portion is formed in the circumferential direction of the thick portion. Is formed over. [Selection diagram] Fig. 1

Description

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

Constant velocity joints are used at both ends of drive shafts for automobiles. The constant velocity joint on the differential side (inboard side) is a tripod joint (triport) in which, for example, three sets of rollers mounted in a trident shape on the shaft portion of the drive shaft are configured to be slidable in the axial direction. It is common to use a joint).
In order to reduce the wall thickness and weight of the outer casing of the tripod joint, recesses provided in a groove shape in the axial direction of the outer peripheral surface are formed, for example, dispersed at three locations in the circumferential direction. The inner peripheral surface of the large-diameter side end of the boot for constant velocity joint used for this type of tripod joint has a thickness formed by, for example, an axially projecting arc-shaped shape that matches the surface of the recess. The meat part is formed. As a boot for this type of tripod joint, the inventors of the present application have previously proposed the technique described in Japanese Patent No. 4359532 (see Patent Document 1). With this prior art, it is possible to integrally mold a thick part and a thin part on the inner peripheral surface of the large-diameter side end of the premolded product in the circumferential direction, and also on the thick part after molding. The feature is that it is easy to pull out the boot from the core type even if it has an undercut part.

In recent years, various parts of automobiles have been further reduced in weight due to demands for low fuel consumption and low cost.

Therefore, there is an increasing demand for weight reduction even in this type of tripod joint boot, and the structure disclosed in Patent Document 2 is an improved constant velocity joint boot with a focus on weight reduction. Proposed.
In Patent Document 2, the weight is reduced by removing the light from the outer surface side of the thick portion at the end on the large diameter side (see Patent Document 2).
Further, in such a lightening configuration, this type of tripod joint boot (constant velocity joint boot) has a portion having a thick portion and a thin portion having different thicknesses at the end portion on the large diameter side. Therefore, there is a risk of shrinkage during molding, so it also has the role of balancing heat and preventing shrinkage (sink) during molding.

Boots for this type of tripod joint (boots for constant velocity joints) are made by fitting the boots to the outer circumference of the outer casing and then tightening the outer peripheral surface of the large-diameter side end using a metal tightening band. The lip portion protruding from the inner peripheral surface of the large-diameter side end is pressed against the outer peripheral surface of the outer casing to seal it.
At this time, in order to improve the sealing performance, it is preferable that the tightening force of the tightening band is concentrated on the lip portion protruding from the inner peripheral surface of the large diameter side end portion.

However, in the case of the structure of the boot for the tripod joint disclosed in Patent Document 2, since the lightening is performed from the outer peripheral surface side of the large-diameter side end on the side where the tightening band contacts, the opening side of the lightened groove is tightened. The area facing the band and in contact with the tightening band is small.
That is, in the boots for tripod joints disclosed in Patent Document 2, a lightened groove is located in the lower part of the band where the tightening force is most applied, and a solid part exists between the groove and the lip part. 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 only 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 be described in detail in comparison with the embodiments described later.

Further, when the lightening portion is formed on the outer peripheral side of the large-diameter side end portion, a parting line at the time of mold molding appears on the outer peripheral surface.
Since the outer peripheral surface of the large-diameter side end is the fastening surface of the tightening band as described above, it is preferable that the outer peripheral surface is a flat surface without unevenness, and if there is an extra parting line, a uniform tightening force cannot be given. , There is a risk of reducing the tightening force.

Further, since the place where the boots for constant velocity joints are mounted is in a harsh environment where muddy water and dust fly, as disclosed in Patent Document 2, a lightening groove is formed on the outer peripheral side of the large diameter side end portion. If is provided, dust, stones, mud, muddy water, etc. may enter the groove, and as a result, the fastening force may be lowered.
In addition, if chemicals such as road surface antifreeze agents or 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 Japanese Unexamined Patent Publication No. 2002-13546

The present invention has been made in view of such problems of the prior art, and the subject thereof is to provide a tightening force by an appropriate fastening band while reducing the weight of the boot for the tripod joint. It is an object of the present invention to provide boots for tripod joints which can prevent this decrease in tightening force and maintain good sealing performance.

In order to achieve such a task, the first invention comprises an annular large diameter side 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 boot for constant velocity joints that is integrally provided in communication between the large diameter side end portion and the small diameter side end portion and is composed of a bellows portion formed by repeatedly arranging the large diameter portion and the small diameter portion. There,
On the inner peripheral surface of the large-diameter side end portion, a plurality of thick portions formed so as to fit a plurality of recesses formed on the outer peripheral surface of the outer casing and projecting in the inner diameter direction of the boot, and the plurality of thicknesses. It has a thin wall part arranged between the meat parts,
On the inner peripheral surface of the thick portion and the inner peripheral surface of the thin portion, lip portions continuous in the circumferential direction are formed in contact with the outer peripheral surface of the outer casing including the recess and seal the boot inner region. Ori,
At least one or more groove portions recessed in the outer diameter direction of the boot from the inner peripheral surface side are formed in the thick portion.
The groove portion is a boot for a constant velocity joint characterized in that it is formed over the circumferential direction of the thick portion.

In the second invention, in the first invention, two or more lip portions are formed.
Of these, at least two lip portions are constant velocity joint boots characterized in that they are located so as to sandwich the groove portion in the boot axial direction.

According to the third invention, in the first invention or the second invention, the thick portion is formed in the circumferential direction of the large diameter side end portion when viewed from the bottom surface side of the large diameter side end portion. The boots for constant velocity joints are characterized by having an arc shape that rises from the left and right hem to the top and is formed in an inclined shape.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the groove portion is formed so that the groove width in the boot axial direction at the hem portion is narrower than the groove width in the boot axial direction at the top of the thick portion. The boots for constant velocity joints are characterized by this.

A fifth aspect of the present invention is, in any one of the first invention to the fourth aspect of the present invention, the groove portion is formed in the boot outer diameter direction with respect to the boot axial groove width on the inner peripheral surface of the thick portion. This is a boot for constant velocity joints, which is characterized in that the groove width in the axial direction of the boot is narrowly formed.

A sixth aspect of the present invention is that, in any one of the first to fifth aspects of the present invention, the groove portion faces in the boot axial direction, and a rib is provided between the inner wall surfaces constituting the groove portion. The boots for constant velocity joints are characterized by the fact that they are used.

According to the seventh aspect of the present invention, 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 a small diameter side end portion. It has a bellows portion formed between the large-diameter side end portion and the small-diameter side end portion and formed by repeatedly arranging the large-diameter portion and the small-diameter portion, and the inner peripheral surface of the large-diameter side end portion has a bellows portion. It has a plurality of thick portions formed by projecting to the inner diameter side of the boot so as to fit the recesses of the outer casing of the tripod joint, and a thin portion arranged between the plurality of thick portions. It is a method of manufacturing boots for fast joints.
The core mold is arranged in the large-diameter side end of the pre-molded product formed by providing both the small-diameter side end and the large-diameter side end that communicate with the internal space of the bellows portion, and at least the large diameter side end of the pre-molded product is large. A holding mold is placed on the outer peripheral surface side of the radial end,
The upward protruding portion provided on the core mold is brought into contact with the inner peripheral surface of the bellows portion or the inner peripheral surface of the large diameter side end portion, and the inner peripheral surface of the holding mold is brought into contact with the large diameter side end portion. In contact with the outer peripheral surface of
A secondary molded portion composed of a plurality of thick portions and a plurality of thin-walled portions at the large-diameter side end portion between the inner peripheral surface of the large-diameter side end portion of the premolded product and the lower peripheral surface portion of the core mold. And the process of forming a secondary molding space for molding
A step of injecting a molten material into the secondary molding space and molding a secondary molding portion composed of a thick portion and a thin wall portion at the large diameter side end portion of the premolded product.
Including at least
The core includes the upward protruding portion corresponding to the thick-walled molding space constituting the secondary molding space, and the downward protruding portion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold. A step of retracting in the direction of the central axis of the mold to remove it from the thick-walled molding space region of the secondary molding space, and separating the core mold and the boot in that state.
It is a method of manufacturing boots for constant velocity joints, which is characterized by having.

In the eighth aspect of the present invention, in the seventh aspect of the present invention, one or both of the upward protrusion and the downward protrusion of the core mold corresponding to the thick portion molding space constituting the secondary molding space may be used. This is a method for manufacturing a boot for a constant velocity joint, which is characterized in that it is retracted from the thick region by driving a cam member that rotates around a core type central axis or an axis parallel to the core type central axis. ..

In the ninth invention or the eighth invention, the core-type downward protruding portion corresponding to the thick-walled portion molding space constituting the secondary molding space is the thick-walled portion. This is a method for manufacturing a boot for a constant velocity joint, which is characterized by having a die surface for forming a groove formed in the portion.

In the tenth aspect of the present invention, 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 It has a bellows portion formed between the large-diameter side end portion and the small-diameter side end portion and formed by repeatedly arranging the large-diameter portion and the small-diameter portion, and the inner peripheral surface of the large-diameter side end portion has a bellows portion. It has a plurality of thick portions formed by projecting to the inner diameter side of the boot so as to fit the recesses of the outer casing of the tripod joint, and a thin portion arranged between the plurality of thick portions. A device for manufacturing boots for fast joints.
A holding die for holding the outer surface of the preformed product formed by providing both the small diameter side end portion and the large diameter side end portion communicating with the internal space of the bellows portion.
A core mold inserted into the large diameter side end of the premolded product and
To mold a secondary molded portion composed of a plurality of thick-walled portion molding spaces and a plurality of thin-walled portion molding spaces formed between the inner peripheral surface of the large-diameter side end portion of the premolded product and the outer peripheral surface of the core mold. Equipped with an injection mechanism that injects and fills the molten material into the secondary molding space of
The holding mold has an inner peripheral surface that can come into contact with the outer peripheral surface of the large-diameter side end portion.
The core type has a plurality of thicknesses between an upward protruding portion capable of contacting the inner peripheral surface of the bellows portion or the inner peripheral surface of the large-diameter side end portion and the inner peripheral surface of the large-diameter side end portion. A lower peripheral surface portion that forms a secondary molding space for molding a secondary molding portion consisting of a meat portion and a plurality of thin-walled portions and a lower peripheral surface portion that is slidably provided in the central axis direction of the core mold. With a protrusion,
The upward protruding portion and the downward protruding portion of the core mold corresponding to the thick-walled portion molding space constituting the secondary molding space can advance toward the thick-walled portion molding space and are directed toward the core mold central axis direction. It is a manufacturing device for boots for constant velocity joints, which is characterized in that it can be retracted.

The eleventh invention has, in the tenth invention, a cam member that swivels about the core type central axis or an axis parallel to the core type central axis.
One or both of the upward protruding portion and the downward protruding portion of the core mold corresponding to the thick-walled portion molding space constituting the secondary molding space is directed toward the thick-walled portion molding space by the cam member. This is a device for manufacturing boots for constant velocity joints, which is characterized in that it can be moved forward and retracted toward the core type central axis.

In the twelfth invention, in the tenth invention or the eleventh invention, the core-type downward protruding portion corresponding to the thick-walled portion molding space constituting the secondary molding space is the thick-walled portion. It is an apparatus for manufacturing boots for a constant velocity joint, which is characterized by having a die surface for forming a groove formed in the portion.

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

It is a schematic vertical sectional view which shows one Embodiment of the boot for a constant velocity joint of this invention. It is a schematic bottom view which shows one Embodiment of the boot for a constant velocity joint of this invention. It is a schematic vertical sectional view which shows the thin part enlarged. It is a schematic vertical sectional view which shows the thick part enlarged. It is a schematic perspective view which shows the periphery of a thick part enlarged. It is a schematic perspective view which enlarges and shows another embodiment of the thick-walled part which ribs are formed between the facing inner wall surfaces of a pair of thick-walled part constituents which make up a thick-walled part. It is a schematic perspective view which enlarges and shows another embodiment of the thick-walled part which rib is formed between the facing inner wall surfaces of a pair of thick-walled part constituents which make up a thick-walled part. FIG. 6B is a schematic enlarged view of a thick portion viewed from a direction orthogonal to the inner peripheral surface of the large diameter side end portion of FIG. 6B. It is a partial schematic view which shows the difference in the width of the groove part. It is a schematic vertical sectional view which compares the thick part of this invention with the thick part of a comparative example. It is a schematic plan view which is the core mold used for the manufacturing apparatus of this invention, and shows the state which the 2nd mold part is extruded in the direction of the thick part molding space. It is a schematic vertical sectional view which is the core mold used for the manufacturing apparatus of this invention, and shows the state which the 2nd mold part is extruded in the direction of the thick part molding space. It is a schematic plan view which is the core mold used for the manufacturing apparatus of this invention, and shows the state which the 2nd mold part is retracted from the thick part molding space. It is a schematic vertical sectional view which is the core mold used for the manufacturing apparatus of this invention, and shows the state which the 2nd mold part is retracted from the thick part molding space. It is a core type used for the manufacturing apparatus of this invention, and is the schematic perspective view which is shown by the broken line with a part omitted. It is the schematic which shows the whole flow of the manufacturing method of this invention. It is another embodiment of the core type used in the manufacturing apparatus of this invention, and is the schematic vertical sectional view which shows the state which the 1st member and the 2nd member are located in the thick part molding space. It is another embodiment of the core type used in the manufacturing apparatus of this invention, and is the schematic vertical sectional view which shows the state which the 1st member and the 2nd member are retracted from the thick part molding space. Another embodiment of the boot for constant velocity joint of the present invention is a schematic partial enlarged cross-sectional view in which a space is formed between an inner surface of an inclined portion and an upper surface of a secondary molded portion.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that this embodiment is merely one embodiment of the present invention and is not construed as being limited thereto, and the design can be changed within the scope of the present invention.

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

[Explanation of boots for constant velocity joints]
The constant velocity joint boot (hereinafter, also simply referred to as a boot) 1 of the present embodiment is used for a tripod joint having a recess formed on the outer peripheral surface of the outer casing. That is, in the outer casing of such a tripod joint, for example, axial grooves formed in an arc shape in a cross-sectional view are formed at three locations at substantially equal intervals in the circumferential direction of the outer peripheral surface.

As shown in FIG. 1, the constant velocity joint boot (boot for tripod joint) 1 has a large-diameter side end portion 3 into which the outer housing of the tripod joint is inserted, and an inner diameter and outer diameter than the large-diameter side end portion 3. It has a small diameter side end portion 5 formed to have 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.
Then, in this boot 1, the large-diameter side end portion 3, the small-diameter side end portion 5, and the bellows portion 7 are integrally molded by a well-known premolding process using a resin such as a thermoplastic elastomer (hereinafter, this molded product). (I will be described as a premolded product.) Further, on the inner peripheral side of the large-diameter side end portion 3 of the premolded product, a resin such as a thermoplastic elastomer is used to form a portion having a different wall thickness. The next molding portion 13 is integrally molded.

As shown in FIG. 1, the bellows portion 7 has a large diameter portion (also referred to as a mountain portion) 7a formed so that the outside of the boot 1 is convex, and a small diameter portion formed. A small diameter portion (also referred to as a valley portion) 7b formed so that the outside of the boot 1 is concave is repeatedly formed in the tubular 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 3 side of each of the five large diameter portions 7a. It is composed of. Each of these large-diameter portions 7a and small-diameter portions 7b is formed to have a larger diameter in order from the small-diameter side end portion 5 side to the large-diameter side end portion 3 side, respectively. It is formed in a shape.

In the present invention, the bellows portion 7 is not particularly limited, and various conditions such as the wall thickness of the bellows portion 7 and the pitch between the large diameter portion 7a and the small diameter portion 7b are appropriate within the scope of the present invention. Optimal conditions apply.
Further, in the present embodiment, both the large-diameter side end portion 3 and the small-diameter side end portion 5 of the premolded product described above have a uniform wall thickness of a desired thickness. These wall thicknesses are not particularly limited, and an optimum arbitrary thickness is selected.
The conditions of the large-diameter side end portion 3 and the small-diameter side end portion 5 are not particularly limited, and the optimum conditions are appropriately applied within the scope of the present invention. In the present embodiment, the wall thicknesses of the large-diameter side end portion 3 and the small-diameter side end portion 5 are made uniform, but even if the wall thickness is not made 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 portion 3 which is a preformed product is formed in a substantially circular shape, and the outer peripheral surface 15 is band-fastened when the boot 1 is attached to the tripod joint. The portion 37 is recessed. Then, in the secondary forming portion 13 formed inside the outer peripheral surface 15, a plurality of thick-walled portions 17 formed overhanging on the inner peripheral side thereof and a plurality of thick-walled portions 17 formed between the thick-walled portions 17. The thin-walled portions 19 are provided.
In the case of the present embodiment, for example, three thick-walled portions 17 are formed at substantially equal intervals in the inner peripheral direction of the large-diameter side end portion 3, and between the adjacent thick-walled portions 17. Is formed with three thin-walled portions 19 having a substantially constant wall thickness in the circumferential direction.

The thick portion 17 is formed between a pair of thick portion constituents (bases) 17a and 17a and a pair of thick portion constituents 17a and 17a, and has a large diameter from the inner peripheral surface side of the large diameter side end portion 3. It is composed of a groove portion 18 that is recessed in the radial direction (the direction indicated by the arrow R1 in the figure) toward the outer peripheral surface side of the side end portion 3 and 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 portion 3, the thick-walled portion component 17a rises from the left and right hem portions 17b and 17b toward the top portion 17c in the circumferential direction of the large-diameter side end portion 3, respectively. It has an inclined bottom view shape and is formed so as to project into an arc shape (see FIG. 2).
The substantially arc shape of the thick portion 17 (thick portion component 17a) is set so as to fit an axial groove (recess) on the outer peripheral surface of the outer casing of the tripod joint to which the boot 1 is mounted.
In the present embodiment, the pair of thick-walled portions 17a and 17a are formed with the same axial width (thickness), but the pair of thick-walled portions 17a and 17a have different axial widths (thickness). It is within the scope of the present invention even if it is formed by.

The groove shape of the groove portion 18 in the boot radial direction (R1) is the large-diameter side end portion 3 from the direction of the inner peripheral surface of the thick-walled portion (groove opening position near the top 17c of the thick-walled portion component 17a). It is formed so as to become narrower in the outer diameter direction. The groove width at the groove opening position is shown by W1, and the groove width near the outer diameter of the large diameter side end portion 3 is shown by W2 (see FIGS. 4, 7, and 8). In the present embodiment, the width is slightly narrowed, but the shape is not limited to that, and the width may be further extremely narrowed, and the width from W1 to W2 is wide. It is not intended to exclude the same width, and the design can be changed within the scope of the present invention.

The groove width W3 in the boot axial direction between the opposing hem portions 17b and 17b is formed narrower than the groove width W4 in the boot axial direction between the opposing top portions 17c and 17c (see FIG. 5). ..
In the present embodiment, the axial width (thickness) of the hem portion 17b of each thick portion component 17a is formed to be larger than the axial width (thickness) of the top portion 17c, thereby forming the groove width W3. It forms a W4 relationship. By increasing the axial width (thickness) of the hem portion 17b in this way, the rigidity of the top portion 17c with respect to the hem portion 17b can be reduced, that is, softened. As a result, the adhesion of the lip portion, which will be described later, can be improved, and the grease leakage prevention effect can be improved.

It is sufficient that at least one groove portion 18 is provided, and the number of groove portions 18 is not limited. Further, in the present embodiment, the groove shape is formed continuously in the circumferential direction, but even if it is formed intermittently, it is within the scope of the present invention.

Then, as shown in FIGS. 1 to 8, on the inner peripheral surface of the large-diameter side end portion 3, the surface of each thick-walled portion component 17a of the thick-walled portion 17 described above (inner peripheral surface of the thick-walled portion). ) And the surface of the thin-walled portion 19 (inner peripheral surface of the thin-walled portion), the lips are arranged in parallel in the circumferential direction in contact with the outer peripheral surface of the outer casing including the concave portion to seal the boot inner region. Parts (seal lips) 21a and 21b are provided.
The lip portions (seal lips) 21a and 21b seal the inner region of the boot to prevent grease leakage and prevent dust and muddy water from entering.
That is, two lip portions (seal lips) 21a and 21b are formed in parallel, and the respective lip portions (seal lips) 21a and 21b are in the boot axial direction (direction indicated by arrow S1 in the figure). Is located across the groove 18.
The lip portions (seal lips) 21a and 21b are formed as ridges having a cross-sectional view shape of, for example, a substantially triangular shape or a trapezoidal shape. Although not shown, the tops of the lip portions (seal lips) 21a and 21b are chamfered with R.
In this embodiment, an example in which two lip portions (seal lips) 21a and 21b are provided is shown, but 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, a comparison between the thick portion 17 of the present embodiment and the thick portion of the boot disclosed in Patent Document 2 is as follows based on FIG.
FIG. 8A is a view when the thick portion 17 of the present embodiment is tightened and fixed to the axial groove 201 of the outer casing 200 via the tightening band 300, and FIG. 8B is a view of the boot disclosed in Patent Document 2. The figure when the thick part was tightened and fixed to the axial groove 201 of the outer casing 200 through the tightening band 300 is shown.
In order to help understanding the differences, 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 18 is changed. , The thick portion of Patent Document 2 will be described with the same reference numerals as those of the present embodiment.

In the case of the present embodiment, the region of the band fastening portion 37 in contact with the tightening band 300 is A, the solid region directly below the band fastening portion 37 is B, the region where the groove portion 18 is provided is C, and the lip portion 21a (21b). The area is defined 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 in contact with the tightening band 300 is A, the region directly below the band fastening portion 37, and the region where the groove portion 18 is provided is B. The solid region between the groove portion 18 and the lip portions 21a and 21b is defined as C, and the region of the lip portions 21a and (21b) is defined as D.

In the case of the present embodiment, by tightening the tightening band 300, the tightening force applied to A is transmitted from A to C via B. Here, since B is composed of a solid region, the tightening force is transmitted to C almost as it is. Since the cross-sectional area (volume that can receive a load) of C is small due to the presence of the groove portion 18, the tightening force transmitted to the base portion of C is the top D, that is, the lip portion 21a (21b). ) Is concentrated and transmitted. Further, since C has lower rigidity and is elastically deformable than B, which is a solid region, C can elastically apply the tightening force transmitted to B to D.
Further, the region C has a structure in which the area (cross-sectional area) gradually decreases toward the lip portion 21a (21b), and a structure that gradually deforms toward the top is adopted, so that the running vibration As a result, even if the outer casing of the tripod joint, which is the mating member that the lip portion 21a (21b) abuts and seals, is slightly shaken due to vibration or the like, the adhesion of the lip portion 21a (21b) can be maintained. ..

On the other hand, in the case of the thick portion of the boot disclosed in Patent Document 2, the tightening force applied to A by tightening the tightening band 300 is transmitted from A to C via B. 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 that B is deformed to absorb the tightening force. The tightening force transmitted from A to B is reduced. That is, the tightening force transmitted from A is lost in the region B. Furthermore, since the region of C is solid and has a large area (volume that can receive a load), the region of 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 area D, the pressing force of the tripod joint which is the mating side member against the outer casing is small, and the outside of the tripod joint is caused by vibration or the like. If the housing is displaced, the adhesion may not be maintained.
Therefore, in the case of the present embodiment according to the present invention, a sufficient tightening force can be elastically applied to the outer casing of the tripod joint which is the mating side member, so that a decrease in the tightening force can be prevented and the tightening force is good. The structure can maintain a good sealing property.

Further, when molding the groove portion 18, the width W1 on the opening side of the groove portion 18 is formed to be larger than the width W2 on the inner bottom surface side in consideration of ease of die cutting. Therefore, in the case of Patent Document 2, since the area of B is further reduced, the deformation of the region of 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 having a large width W1 of the groove portion 18 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 done.

Therefore, in the case of Patent Document 2, as described above, the groove portion 18 exists in the region B, and the groove portion 18 is greatly deformed in this region to greatly lose the band fastening force, and the band fastening is performed up to the lip portion 21a (21b). The result is that the force is not applied and the sealing performance is not so high, whereas in the case of this embodiment, the area gradually extends from the area A near the tightening band 300 to the area D where the lip portion 21a (21b) exists. Since the structure is adopted, the force is concentrated on the lip portion 21a (21b), and the lip portion 21a (21b) can be deformed. Further, since the band tightening force applied to the lip portion 21a (21b) can be appropriately adjusted according to the region C, that is, the size (widths 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 problems can be sufficiently achieved and the needs of consumers 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 tops 17c and 17c) of the groove portion 18 and the width W3 between the hem portions 17b and 17b, the lip portion (seal lip 21a) is formed. , 21b), the band tightening force applied to the band can be adjusted appropriately, so that the effect of extremely high sealing performance can be expected.
Further, by providing the groove portion 18 in the thick-walled portion 17, the bias of the material volume between the thick-walled portion 17 and the thin-walled portion 19 is reduced, so that the difference in the amount of shrinkage during molding can be reduced, and there is also a problem of shrinkage (sink). Hard to occur.
Further, by providing the groove portion 18 in the thick portion, it is possible to reduce the amount of the resin material used and the manufacturing cost.

Further, as shown in FIG. 6A, the rib portion 18 is bridged between the axially opposed inner wall surfaces 17d and 17d of the pair of thick-walled portion components 17a and 17a constituting the groove portion 18. It is possible to adopt a configuration in which the (bearing wall) 20 is provided.

By bridging the ribs 20 in this way, the strength of the thick portion 17, that is, the thick portion constituents 17a and 17a can be maintained, and unexpected deformation can be suppressed.
Although the rib 20 is not particularly limited in interpretation, its size can be changed within the range in which the weight of the entire boot can be reduced, and a plurality of ribs 20 are spaced apart from each other in the circumferential direction in the groove portion 18. It is also possible to dispose of it. Further, in the present embodiment, the rib 20 is integrally molded at the same time as the thick portion 17 is molded by the manufacturing method described later, but it is also possible to mold the rib 20 separately and bond and fix it in the groove portion 18 of the present invention. Is within the range of.
The rib 20 can be formed so that the width of the base end side (groove inner bottom surface side) is larger than the width of the tip end side (groove opening side).

Further, in the present embodiment, the outer wall 17e of the thick wall structure 17a located inward in the axial direction and the outer wall 17f of the thick wall structure 17a located outward in the axial direction are formed. Although the ribs for preventing the thick-walled portion 17a from falling over are not provided, the ribs may be provided, and the design can be changed within the scope of the present invention.
Since other configurations and actions and effects are the same as those in FIG. 5, the same parts are designated by the same reference numerals and the description thereof will be omitted.

The width (thickness) of the thick-walled portion 17a in the axial direction S1 is not particularly limited, but it must be formed to at least have independence and shape retention when the band is tightened. preferable.
6B and 6C are other embodiments, and the width (thickness) of the thick-walled portion component (base) 17a in the axial direction S1 is thicker than that of FIGS. 5 and 6A. An embodiment is shown.
That is, in the form of the thick portion structure (base) 17a shown in FIGS. 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-walled portion structure (base) 17a.
In the present embodiment, the convex portion 22 is integrally provided continuously with the thick-walled portion component (base) 17a on the back side (inside in the axial direction), and the convex portion 22 is close to the large-diameter side end portion. It is provided toward the inner surface of the small diameter portion 7b of the above. Further, in the present embodiment, a part of the convex portion 22 is stealed in a predetermined range to reduce the weight (in the figure, reference numeral 22a indicates a meat stealing portion).
Since other configurations and actions and effects are the same as those in FIGS. 5 and 6A, the same reference numerals are given to the same parts and the description thereof will be omitted.

The thermoplastic resin constituting the premolded product composed of the large-diameter side end portion 3, the small-diameter side end portion 5 and the bellows portion 7 and the secondary molded portion 13 composed of the portions having different wall thicknesses is not particularly limited, and the thermoplastic resin of the present invention is not particularly limited. The optimum material is selected within the range, and the same material, different hardness materials, and different materials are within the scope of the present invention. It should be noted that the parts having different wall thicknesses, which are the secondary molded parts 13, are preferably made of a material having good sealing properties, while the premolded product is made of a material that is purely suitable for the original purpose, that is, flexibility, heat resistance, cold resistance, etc. The material having the above can be selected.

Description of [Manufacturing Device for Boots for Constant Velocity Joint] Here, an embodiment of a manufacturing device used for manufacturing boots for constant velocity joint of the present invention will be described.

Explaining the schematic structure of the mold 49, which is the main part of the manufacturing apparatus for manufacturing the boots for constant velocity joints of the present invention, as shown in FIGS. 9 to 14, for injection molding, which is the main part of the apparatus. The mold 49 has a holding mold (split mold) 51 constituting the movable platen side and a core mold 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 appearance shape of the premolded product is in close contact (holds the outer surface of the premolded product), and the holding mold is formed. When the (split mold) 51 is molded, a premolded product accommodating space 55 that matches the external shape (outer contour) of the boot 1 is formed.
In the premolded product accommodating space 55, the opening edge 59 of the outer peripheral surface 15 of the large diameter side end portion 3 of the premolded article accommodated in the premolded article accommodating space 55 at the time of mold clamping is a holding mold (split mold). It is formed so as to be located on the same plane as the lower end surface 51a of 51.

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

The core type 69 is formed between the upward projecting portions 74, 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 forming the secondary molding space 43 for molding the secondary molding portion composed of the plurality of thick-walled portions and the plurality of thin-walled portions, and the lower peripheral surface portions 76a and 81c have core molds. The core mold 69 is provided with a downward projecting portion 81b slidable in the central axis direction of the 69, and corresponds to the thick portion molding space 43a constituting the secondary molding space 43. The upward projecting portion 81a and the downward projecting portion 81b are configured so as to be able to move forward toward the thick portion forming space 43a and retractable toward the central axis direction of the core mold 69.

As shown in FIGS. 9 to 14, the core type 69 is provided in the central portion, is configured to be rotatable left and right in the horizontal direction about the central axis, and functions as an operation portion. 99), a first mold portion (base portion) 70 forming a thin-walled portion forming space 43b alternately provided in the circumferential direction around the rotating piece portion 89 (cam member 99), and a thick-walled portion forming space. The whole is formed in a disk shape having a desired wall thickness by the second mold portion 79 forming 43a.
Further, the outer peripheral diameter of the core mold 69 is designed to constitute the inner diameter of the secondary molded portion formed on the inner surface of the large diameter side end portion 3 of the premolded product. The inner diameter of the secondary molded portion is a diameter that fits into the outer diameter of the outer casing of the tripod joint to be mounted.

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

A groove 90 for sliding the second mold portion 90 is provided between the adjacent first mold portions 70 and 70 so that the second mold portion 79 can slide (slide) 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 bridged over the groove inner side surfaces 90a, 90a facing each other are arranged at predetermined intervals in the vertical direction.
In the interior plate portion 91, the rear surface 91a facing the rotating piece portion 89 arranged in the center of the core mold is a flat surface, and the front surface 91b facing the thick portion forming space 43a is formed with a curved surface recessed in the rear surface 91a direction. (See FIG. 13).

The two interior plate portions 91 and 91 are used to form the thick portion constituents (bases) 17a and 17a constituting the thick portion 17, and the second mold portion 79 is the thick portion. When it moves in the molding space 43a direction, it is housed in the two deep grooves 93 and 93 recessed inward from the tip of the downward protruding portion 81b of the second member 92 of the second mold portion 79.
When the interior plate portions 91, 91 are housed in the two deep grooves 93, 93, between the front surface (curved surface portion) 91b, 91b of the plate portion and the openings 93a, 93a of the deep grooves 93, 93. , The groove inner side surfaces 90a and 90a are provided at predetermined positions so that predetermined cavities (molding spaces) 110 and 110 for molding the thick portion structure (base) 17a are formed.

As shown in FIGS. 9 to 14, the second mold portion 79 is arranged in the second mold portion sliding groove 90 between the adjacent first mold portions 70, 70, and is arranged with the first mold portion 70. It is configured to be slidable in the direction of the central axis of the core mold 69 or slidable in the direction of the thick portion forming space 43a according to the left-right rotation operation of the rotary piece portion 89 on the integrally provided fixed portion 80. Has been done.

The second mold portion 79 has a width arranged between the adjacent first mold portions 70, 70 and has the same wall thickness as the first mold portion 70 (thickness in the vertical direction), and the rotation Three pieces are provided in the circumferential direction centering on the piece 89.
The second mold portion 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 rotate. A sliding surface portion 95 formed in an arc shape in a plan view is provided on the side facing the piece portion 89 (cam member 99), and an outer circumference composed of an upward protruding portion 81a and a downward protruding portion 81b is provided on the opposite surface. A surface 81 is formed.

The second mold portion 79 contains a core material 79a erected in the vertical direction, and the core material 79a has a core material 89a installed in a rotating piece portion 89 (cam member 99) described later. A tension spring 96 is bridged between them and is urged to be pulled toward the center of the core mold 69. That is, each of the three second mold portions 79 is pulled toward the center of the core mold 69 by having a tension spring 96 bridged between the core member 89a and the core member 89a built in the rotating piece portion 89 (cam member 99). It is being urged to be.

The first member 94 has a circumferential direction with the concave peripheral groove 74 of the first mold portion 70 when the second mold portion 79 is pushed out by the rotating piece portion 89 and protrudes into the thick portion forming space 43a. An upward protruding portion 81a is provided on the outer peripheral surface on 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 as a groove forming mold surface for forming is provided on the lower peripheral surface portion 81c.

The downward protruding portion 81b is sandwiched between the two deep grooves 93 and 93 recessed inward from the tip of the second member 92 of the second mold portion 79 and the two deep grooves 93 and 93 and protrudes. A groove forming plate member 97 having a predetermined thickness is provided.
As described above, the two deep grooves 93 and 93 form thick-walled portions (bases) 17a and 17a together with the two interior plate portions 91 and 91 provided in the second mold sliding groove 90. 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 and is a thick portion. It is provided so as to project from the molding space 43a, and is used to form a groove portion 18 between the thick-walled portion components 17a and 17a.

The second mold portion 79 composed of the first member 94 and the second member 92 slides and moves in the thick wall forming space 43a direction by the left-right rotation operation of the rotating piece portion 89 (cam member 99). Then, together with the concave peripheral 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 peripheral groove 85, and the downward protrusion into the thick portion forming space 43a. The portion 81b can be projected or slid in the direction of the central axis of the core mold 69 so as to be retracted from the thick portion forming space 43a.

The rotating piece portion 89 is composed of a core material 89a and a cam member 99 attached to the core material 89a. The core member 89a is erected vertically at the substantially center of the core mold 69 and is arranged at the center of the cam member 99.

The cam member 99 is formed in a substantially triangular columnar shape having a deformed triangular shape in a plan view, and is formed with 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, on the top surface of the cam member 99, a protrusion 100 is provided in which a locking groove 100a for locking the locking arm 101a of the operating member 101 is recessed.
That is, the sliding surface portion 95 of the second mold portion 79 is formed by rotating the rotating piece portion 89 (cam member 99) in either the left or right direction in the horizontal direction around the central axis of the core mold 69. 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 portion 89 (cam member 99) is rotationally operated to reach the position where the convex side surface portion 99b presses the sliding surface portion 95 of the second mold portion 79, the second mold portion 79 Slides (forwards) so as to position the downward protruding portion 81b in the thick-walled portion forming space 43a, and when the rotary piece portion 89 (cam member 99) is rotationally operated in the opposite direction, the second mold portion 79 is a downward protruding portion provided on the lower end side outer peripheral surface of the tip of the second member 92 by sliding (moving backward) along the sliding surface portion 95 from the convex side surface portion 99b to the concave side surface portion 99a by the tension spring 96. 81b is retracted from the thick portion 17 region.

The operation member 101 is a desired member that can be rotated and operated with a three-pronged locking arm portion 101a at the tip, and the locking arm portion 101a is recessed in the top surface of the protrusion 100 of the cam member 99. It is locked to the three-pronged locking groove 100a and rotated at a predetermined angle in either the left or right direction in the horizontal direction, or about 60 degrees in the present embodiment. The operating member 101 is not limited to the present embodiment, and may be appropriately selected within the scope of the present invention as long as it has a configuration in which the cam member 99 can be rotated by a predetermined angle in a predetermined direction. is there. Further, the operating member 101 may be a manual type or may be configured to be automatically rotatable via power.
It is also possible to provide a predetermined power source in the lower region of the cam member 99 to automatically rotate the cam member 99.

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

The manufacturing method of this embodiment is composed of "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 method for molding a preformed product including the large-diameter side end portion 3, the small-diameter side end portion 5, and the bellows portion 7 described above, but the present invention is not particularly limited. The optimum molding method is appropriately applied within the scope of the invention.

"Secondary molding process"
In this step, the core mold 69 is inserted into the large-diameter side end portion 3 of the premolded product molded by premolding and held in the injection molding mold 49, and is desired in the mold 49. By injecting the molten material, a secondary molded portion 13 composed of a thick-walled portion 17 and a thin-walled portion 19 is formed between the inner surface of the outer peripheral surface 15 of the large-diameter side end portion 3 of the premolded product and the outer surface of the core mold 69. It is integrally molded. Since known configurations are applied to configurations other than those described below, the description thereof will be omitted.

The secondary molding step includes (1) a step of forming a secondary molding space and (2) a step of molding a secondary molding portion.

"(1) Step of forming secondary molding space"
For example, first, the preformed product is attached to the core mold 69 by arranging the core mold 69 provided on the fixing plate 49a side in advance so that the inner circumference of the large diameter side end portion 3 of the preformed product comes to the outer circumference. (Fig. 14 (a)).
Then, as described above, the preformed product provided by attaching the large-diameter side end portion 3 to the outer periphery of the core mold 69 is formed in the mold 49 by molding the holding mold (split mold) 51. (Fig. 14 (b)).
At this time, the core type 69 locks the three-pronged locking arm portion 101a of the operating member 101 to the three-pronged locking groove portion 100a provided on the protruding portion 100 of the rotating piece portion 89 (cam member 99). Then, by rotating the rotating piece portion 89 (cam member 99) at a predetermined angle (60 degrees in this embodiment) in a predetermined direction (either left or right direction), the convex side surface of the rotating piece portion 89 (cam member 99) is formed. When the portion 99b reaches the position where the sliding surface portion 95 of the second mold portion 79 is pressed, the second mold portion 79 has a downward projecting portion 81b (deep grooves 93, 93, groove portion forming plate member) in the thick-walled portion forming space 43a. Slide movement (forward movement) so as to position 97).

When the holding die (split die) 51 is molded in this way, as shown in FIG. 14 (b), the entire outer surface of the small diameter portion 7b closest to the large diameter side end portion 3 of the bellows portion 7 is used for holding. The ridges 53 on the inner surface of the mold (split mold) 51 are fitted, and the concave peripheral grooves 74 and 85 of the core mold 69 are fitted in the entire inner surface of the small diameter portion 7b, and the holding mold (split mold) is fitted. The small diameter portion 7b is sandwiched between the ridges 53 of 51 and the concave peripheral grooves 74 and 85 of the core mold 69.

By undergoing such a process, the thickness is increased on the inner peripheral surface of the large-diameter side end portion 3 between the inner peripheral surface of the large-diameter side end portion 3 of the premolded product and the outer peripheral surfaces 76 and 81 of the core mold 69. A secondary molding space 43 for molding the secondary molding portion 13 portion including the meat portion 17 and the thin wall portion 19 is formed.
That is, in the secondary molding space 43, in the present embodiment, a thick portion forming space 43a is formed between the outer peripheral surface 81 of the second mold portion 79 of the core mold 69 and the inner peripheral surface of the large diameter side end portion 3. A thin-walled portion forming space 43b communicating with the thick-walled portion forming space 43a is formed between the outer peripheral surface 76 of the first mold portion 70 of the core mold 69 and the inner peripheral surface of the large-diameter side end portion 3. ..
When the second mold portion 79 moves in the direction of the thick portion molding space 43a, the two deep grooves are recessed inward from the tip of the downward protruding portion 81b of the second member 92 of the second mold portion 79. Two interior plate portions 91, 91 provided in the second mold portion sliding groove 90 are housed in 93, 93, respectively, and the front surface (curved surface portion) 91a, 91a of the interior plate portion and the deep grooves 93, 93 are housed. Predetermined cavities (molding spaces for the thick-walled component 17a) 110 and 110 for molding the thick-walled component (base) 17a are formed between the openings 93a and 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 portions 91 and 91 and projects into the thick portion forming space 43a. Be prepared.
The above-mentioned step is only an example, and it is possible to adopt a step other than this step within the scope of the present invention, and the design can be changed as appropriate.

"(2) Step of molding the secondary molding part"
First, the molten material injection points for secondary molding are positioned at any one or a plurality of locations in the thin-walled portion molding space 43b in the secondary molding space 43 formed by the above step.
Then, the thermoplastic resin heated to a high temperature of, for example, 260 ° C. or higher and melted through the injection point is injection-injected into the secondary molding space 43 at high speed, and the large-diameter side end 3 of the premolded product is injected. A secondary molding portion 13 portion including a thick-walled portion 17 and a thin-walled portion 19 is integrally molded on the inner peripheral surface of the above.
That is, the molten material injected from the thin-walled portion molding space 43b flows into the thick-walled portion molding space 43a, and the two deep grooves 93 and 93 provided on the tip surface of the second mold portion 79 and the second mold portion slide. A predetermined cavity (molding space of the thick-walled portion component 17a) for molding the thick-walled portion component (base) 17a formed by the two interior plate portions 91 and 91 provided in the moving groove 90. The molten material enters the 110 and 110, and the thick portion components 17a and 17a and the groove portion 18 are integrally formed.
As described above, the temperature of the thermoplastic resin to be injected is, for example, 260 ° C. or higher, but the temperature is not particularly limited, and the design can be appropriately changed as long as the material does not have any problems.

"Boot pulling process"
By the secondary molding step, a boot 1 in which a secondary molding portion 13 composed of a thick portion 17 and a thin wall portion 19 is integrally molded is formed on the inner peripheral surface of the large-diameter side end portion 3 of the premolded product (FIG. 1).
As shown in FIG. 4, the thick portion 17 on the inner surface of the large-diameter side end 3 of the boot 1 thus formed has a thick portion 17a which is an undercut portion protruding in the boot axial direction. , 17a are provided.

Then, before separating the core type 69 and the boot 1, the three-pronged locking arm portion 101a of the operating member 101 is provided on the protruding portion 100 of the rotating piece portion 89 (cam member 99). When the rotating piece portion 89 is locked to 100a and rotated in a predetermined direction (either left or right direction) by a predetermined angle (60 degrees in this embodiment), the second mold portion 79 is convex due to the tension spring 96. The sliding surface portion 95 slides along the concave side surface portion 99a from the shaped side surface portion 99b (reverse movement), and the downward protruding portion 81b provided on the lower end side outer peripheral surface of the tip of the second member 92 is moved from the thick portion 17 region. It is retracted (FIG. 14 (e)).

As a result, when the thick portion 17 is pulled out from the core mold 69, the core mold portion that is caught by the thick portion constituents 17a and 17a, which are the undercut portions of the thick portion 17, is eliminated, and the boot from the core mold 69 in that state. 1 is pulled out and separated (FIG. 14 (f)).

As described above, according to the present embodiment, the surfaces in contact with the thick portion components 17a and 17a, which are so-called undercut portions, are retracted in the central axis direction of the core mold 69 when the boot 1 which is a molded product is pulled out. Therefore, the boot 1 which is a molded product from the core mold 69 can be easily pulled out, and so-called forcible pulling can be prevented.
The present invention is not limited to the above-described embodiments, and modifications can be made as appropriate within the scope of the invention.

"Second embodiment"
15 and 16 show other embodiments of the core type used in the method for manufacturing constant velocity joint boots of the present invention.

The core mold 69 is composed of a plurality of first mold portions 70 (three as in the first embodiment) and a plurality of second mold portions 79 (three as in the first embodiment). 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 type part 79 will be described here, and the description of the first type part 70 will be omitted.

The second mold portion 79 is composed of a first member 94 and a second member 92, and the first member 94 and the second member 92 are configured to operate independently of each other.
In the present embodiment, the upper region divided by the groove ceiling surface position 93b constituting the upper deep groove 93 in the vertical direction in the second mold portion 79 of the first embodiment is the first member 94, and the lower region is the second member. It is set to 92 (see FIG. 15).

Similar to the first embodiment, the first member (first straight-ahead advancing / retreating member) 94 is configured to be able to move forward and backward by the cam member 99 of the rotating piece portion (rotating core) 89, and has a rear end surface (rear end surface (rotating core) 89. The surface on the core type central axis side) is provided with an arcuate sliding surface portion 95, and the tip surface on the opposite side is concave in which the inner surface of the small diameter portion 7b closest to the large diameter side end portion 3 in the preformed product is fitted. A peripheral groove 85 is provided on the outer peripheral surface on the upper end side. The concave peripheral groove 85 communicates with the concave peripheral groove 74 of the first mold portion 70 in the circumferential direction.
Similar to the first embodiment, the first member 94 is always urged by the tension spring 96 to be pulled toward the central axis of the core type 69. One end of the tension spring 96 is connected to the core member 94a of the first member 94, and the other end is connected to the shaft portion 120 provided at the substantially center of the rotating piece portion 89 described later.

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

The shaft portion 120 is composed of a cylindrical shaft portion 121, a disk-shaped pressing portion 122 integrally formed at the upper end of the cylindrical shaft portion 121, and a disk-shaped contact portion 123 integrally formed at the lower end of the cylindrical shaft portion 121. The core 130 is located at the center of the core type 69 and is slidably inserted vertically into the through hole 111 provided at the center of the rotating piece 89 in the vertical direction. It is erected on the top surface 130a of the.
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 vertical elevating core 130. Further, the vertical length of the shaft portion 120 is such that when the vertical elevating core 130 is raised (when not pressed), the pressing portion 122 is outside from the top surface of the rotating piece portion 89 (the top surface of the protrusion 100). The length is set so that the pressing portion 122 can be accommodated inside the top surface (top surface of the protrusion 100) of the rotating piece portion 89 when the core 130 for raising and lowering up and down is lowered (when pressed). Has been done.

The cam member 99 is formed in a substantially triangular columnar shape having a deformed triangular shape in a plan view, and is formed with 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, 99a, 99a.
Further, on the top surface of the cam member 99, a protrusion 100 is provided in which a locking groove 100a for locking the locking arm 101a of the operating member 101 is recessed.

That is, by rotating the rotating piece portion 89 in either the left or right direction in the horizontal direction around the central axis of the core mold 69, the sliding surface portion 95 of the first member 94 becomes the convex side surface portion 99b. It slides in a straight line in the horizontal direction along the concave side surface portion 99a.
For example, in the present embodiment, when the rotary piece portion 89 is rotationally operated to reach the position where the convex side surface portion 99b presses the sliding surface portion (arc-shaped surface portion) 95 of the first member 94, the first member 94 slides. After moving (forward movement), the concave peripheral groove 85 at the tip fits the inner surface of the small diameter portion 7b closest to the large diameter side end portion 3 in the preformed product, and the other surface portion on the tip side is a thick portion forming space. It is located at 43a. Further, when the rotary piece portion 89 is rotationally operated in the opposite direction, the first member 94 slides (reverse movement) along the sliding surface portion 95 from the convex side surface portion 99b to the concave side surface portion 99a by the tension spring 96. Then, the first member 94 is retracted from the thick portion 17 region.

The second member (second linear advancing / retreating member) 92 is configured to be constantly urged toward the center of the core mold 69 by the tension spring 140.
Then, the second member 92 moves forward and backward by the up-and-down movement of the up-and-down elevating core (straight-moving core) 130 which is always pushed upward in the vertical direction by the pushing-up spring 150 arranged below. It 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 connected to a projecting portion 160a projecting integrally with a substantially center of the base core 160 described later.

For example, the rear surface (the surface of the core type 69 facing the central axis) 92a of the second member 92 is formed in a tapered shape, and the side peripheral surface upper region 130b of the vertical elevating core 130 facing the rear surface 92a is formed. When the vertical elevating core 130 is raised by the push-up spring 150, the second member 92 slides and moves due to the tapered upper region 130b. The tip surface is positioned in the thick portion forming space 43a.
A downward protruding portion 81b for forming a groove is formed on the tip surface of the second member 92, and the downward protruding portion 81b for forming the groove is recessed inward from the tip of the second member 92. It is provided with a groove forming plate member 97 having a predetermined thickness that is sandwiched between the two deep grooves 93 and 93 and the two deep grooves 93 and 93 and protrudes.
Similar to the first embodiment, the two deep grooves 93, 93, together with the two interior plate portions 91, 91 provided in the second mold portion sliding groove 90, are thick-walled portions (base) 17a, It is used to form 17a, and the groove forming plate member 97 passes between two interior plate portions 91 and 91 provided in the second mold portion sliding groove 90. It is provided so as to project into the thick-walled portion forming space 43a, and is used to form a groove portion 18 between the thick-walled portion components 17a and 17a.
Then, when the vertical evacuation core 130 is pushed down against the push-up spring 150, the second member 92 slides and retracts due to the tapered upper region 130b, and the tip surface thereof is thickened. It is retracted from the partial molding space 43a.

In order to rotate the cam member 99 to advance / retreat the first member 94, the tip locking arm 101a of the operating member 101 is locked in the locking groove 100a of the protrusion 100 to rotate. Further, when moving the second member 92 forward and backward, it is necessary to move the vertical lifting core 130 up and down, but when pushing down the vertical lifting core 130 against the pushing spring 150, the vertical lifting core 130 is moved up and down. This 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 operating member 101. Since the pressing portion 122 at the upper end of the shaft portion 120 projects above the protruding portion 100 of the cam member 99, the pressing portion is located at the lower end of the operating member 101 (the surface portion where the locking arm portion 101a is provided). This is done by pushing down 122.

In the present embodiment, the push-up spring 150 is arranged in the accommodation space 161 having an open top surface recessed in the base core 160 arranged below the core mold 69 in the vertical direction, and the accommodation space 161 is arranged. The vertical elevating core 130 is formed in a cylindrical space having a size that allows it to move up and down. Further, although a coil spring as shown in the figure is assumed as a push-up member for vertically raising and lowering the core 130 for raising and lowering, it 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 it is also possible to use a push-up member made of a rubber material, a synthetic resin material, or the like having high elasticity instead of the spring member.

The operation member 101 is a desired member capable of rotation operation having a locking arm portion 101a at the tip thereof, and the locking arm portion 101a is recessed in the top surface of the protrusion 100 of the cam member 99. It is locked to 100a and rotated by a predetermined angle in either the left or right direction in the horizontal direction, or about 60 degrees in the present embodiment. The operating member 101 is not limited to this 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. Anything can be appropriately selected within the scope of the present invention. Further, the operating member 101 may be a manual type or may be configured to be automatically rotatable via power.

In each of the above-described embodiments, the upward projecting portions 74 and 81A of the core mold 69 are abutted (fitted) against the inner surface of the small diameter portion 7b closest to the large diameter side end portion 3, but for example, By adopting the core mold 69 having the abutting flange (not shown) on the upper part, the inner surface 8a of the inclined portion 8 and the upper surface 14 of the secondary forming portion 13 (thin-walled portion 19 in FIG. 17) as shown in FIG. It is often within the scope of the present invention to provide boots for constant velocity joints in which a space 16 is formed between the boots and the boots for constant velocity joints.

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 part 21a, 21b Lip part

Claims (12)

An annular large-diameter side end into which the outer housing of the tripod joint is inserted,
An annular small-diameter side end into which a shaft connected to the tripod joint is inserted,
A boot for constant velocity joints that is integrally provided in communication between the large diameter side end portion and the small diameter side end portion and is composed of a bellows portion formed by repeatedly arranging the large diameter portion and the small diameter portion. There,
On the inner peripheral surface of the large-diameter side end portion, a plurality of thick portions formed so as to fit a plurality of recesses formed on the outer peripheral surface of the outer casing and projecting in the inner diameter direction of the boot, and the plurality of thicknesses. It has a thin wall part arranged between the meat parts,
On the inner peripheral surface of the thick portion and the inner peripheral surface of the thin portion, lip portions continuous in the circumferential direction are formed in contact with the outer peripheral surface of the outer casing including the recess and seal the boot inner region. Ori,
At least one or more groove portions recessed in the outer diameter direction of the boot from the inner peripheral surface side are formed in the thick portion.
A boot for a constant velocity joint, wherein the groove portion is formed over the circumferential direction of the thick portion. Two or more lip portions are formed.
The boot for a constant velocity joint according to claim 1, wherein at least two lip portions are located so as to sandwich the groove portion in the boot axial direction. When viewed from the bottom surface side of the large-diameter side end portion, the thick-walled portion has an arc shape formed so as to rise from the left and right hem portions to the top portion in the circumferential direction of the large-diameter side end portion. The boot for a constant velocity joint according to claim 1 or 2, wherein the boot is provided. The constant velocity joint according to claim 3, wherein the groove portion is formed so that the groove width in the boot axial direction at the hem portion is narrower than the groove width in the boot axial direction at the top of the thick portion. Boots for. The groove portion is characterized in that the groove width in the boot axial direction is formed narrower in the boot outer diameter direction with respect to the boot axial groove width on the inner peripheral surface of the thick portion. Boots for constant velocity joints according to any one of 4. The boot for constant velocity joint according to any one of claims 1 to 5, wherein the groove portion faces in the boot axial direction and is provided with a rib that is bridged between the inner wall surfaces constituting the groove portion. .. A large-diameter side end into which the outer casing of a tripod joint having a plurality of recesses is inserted on the outer peripheral surface, a small-diameter side end into which a shaft connected to the tripod joint is inserted, and the large-diameter side end. It has a bellows portion formed between the small diameter side end portion and formed by repeatedly arranging the large diameter portion and the small diameter portion, and the outer casing of the tripod joint is provided on the inner peripheral surface of the large diameter side end portion. A method for manufacturing a boot for a constant velocity joint, which has a plurality of thick-walled portions formed so as to fit into the recesses of the boot and project to the inner diameter side of the boot, and thin-walled portions arranged between the plurality of thick-walled portions. And
The core mold is arranged in the large-diameter side end of the pre-molded product formed with the small-diameter side end and the large-diameter side end communicating with the internal space of the bellows portion at both ends, and at least the large diameter side end of the pre-molded product A holding mold is placed on the outer peripheral surface side of the radial end,
The upward protruding portion provided on the core mold is brought into contact with the inner peripheral surface of the bellows portion or the inner peripheral surface of the large diameter side end portion, and the inner peripheral surface of the holding mold is brought into contact with the large diameter side end portion. In contact with the outer peripheral surface of
A secondary molded portion composed of a plurality of thick portions and a plurality of thin-walled portions at the large-diameter side end portion between the inner peripheral surface of the large-diameter side end portion of the premolded product and the lower peripheral surface portion of the core mold. And the process of forming a secondary molding space for molding
A step of injecting a molten material into the secondary molding space and molding a secondary molding portion composed of a thick portion and a thin wall portion at the large diameter side end portion of the premolded product.
Including at least
The core includes the upward protruding portion corresponding to the thick-walled molding space constituting the secondary molding space, and the downward protruding portion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold. A step of retracting in the direction of the central axis of the mold to remove it from the thick-walled molding space region of the secondary molding space, and separating the core mold and the boot in that state.
A method for manufacturing boots for constant velocity joints, which comprises. One or both of the upward protrusion and the downward protrusion of the core mold corresponding to the thick portion molding space constituting the secondary molding space is the core mold central axis or the shaft parallel to the core mold central axis. The method for manufacturing a boot for a constant velocity joint according to claim 7, wherein the cam member that swivels around the shaft is driven to retract the cam member from the thick portion region. The downward protruding portion of the core mold corresponding to the thick-walled portion molding space constituting the secondary molding space is characterized by having a groove forming mold surface formed in the thick-walled portion. The method for manufacturing a boot for a constant velocity joint according to claim 7 or 8. A large-diameter side end into which the outer casing of a tripod joint having a plurality of recesses on the outer peripheral surface is inserted, a small-diameter side end into which a shaft connected to the tripod joint is inserted, and the large-diameter side end. It has a bellows portion formed between the small diameter side end portion and formed by repeatedly arranging the large diameter portion and the small diameter portion, and the outer casing of the tripod joint is provided on the inner peripheral surface of the large diameter side end portion. A device for manufacturing a boot for a constant velocity joint, which has a plurality of thick-walled portions formed by projecting to the inner diameter side of the boot in conformity with the recesses of the above, and thin-walled portions arranged between the plurality of thick-walled portions. And
A holding die for holding the outer surface of the preformed product formed by providing both the small diameter side end portion and the large diameter side end portion communicating with the internal space of the bellows portion.
A core mold inserted into the large diameter side end of the premolded product and
To mold a secondary molded portion composed of a plurality of thick-walled portion molding spaces and a plurality of thin-walled portion molding spaces formed between the inner peripheral surface of the large-diameter side end portion of the premolded product and the outer peripheral surface of the core mold. Equipped with an injection mechanism that injects and fills the molten material into the secondary molding space of
The holding mold has an inner peripheral surface that can come into contact with the outer peripheral surface of the large-diameter side end portion.
The core type has a plurality of thicknesses between an upward protruding portion capable of contacting the inner peripheral surface of the bellows portion or the inner peripheral surface of the large-diameter side end portion and the inner peripheral surface of the large-diameter side end portion. A lower peripheral surface portion that forms a secondary molding space for molding a secondary molding portion consisting of a meat portion and a plurality of thin-walled portions and a lower peripheral surface portion that is slidably provided in the central axis direction of the core mold. With a protrusion,
The upward protruding portion and the downward protruding portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space can advance toward the thick portion molding space and are directed toward the core mold central axis direction. It is configured so that it can be saved.
A device for manufacturing boots for constant velocity joints. It has a cam member that swivels around the core type central axis or an axis parallel to the core type central axis.
One or both of the upward protruding portion and the downward protruding portion of the core mold corresponding to the thick-walled portion molding space constituting the secondary molding space is directed toward the thick-walled portion molding space by the cam member. The device for manufacturing a boot for a constant velocity joint according to claim 10, wherein the device is configured to be forwardable and retractable toward the core type central axis direction. The downward protruding portion of the core mold corresponding to the thick-walled portion molding space constituting the secondary molding space is characterized by having a groove forming mold surface formed in the thick-walled portion. The apparatus for manufacturing boots for constant velocity joints according to claim 10 or 11.

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