JP7250767B2 - Constant velocity joint boot Manufacturing method for constant velocity joint boot Manufacturing apparatus for constant velocity joint boot - Google Patents

Description

The present invention is a constant velocity joint boot (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. It relates to a constant velocity joint boot to be mounted. The present invention also relates to a method for manufacturing the constant velocity joint boot and a manufacturing apparatus for the constant velocity joint boot used in the manufacturing method.

Constant velocity joints are used at both ends of drive shafts for automobiles. In the constant velocity joint on the differential side (inboard side), a tripod joint (triport joint) is generally used.
In order to reduce the thickness and weight of the tripod joint, the outer casing of the tripod joint is formed with, for example, three groove-shaped recesses distributed in the circumferential direction on the outer peripheral surface thereof in the axial direction. On the inner peripheral surface of the large-diameter side end of the boot for a constant velocity joint used in this type of tripod joint, a thickness is formed so as to conform to the surface of the recess and project, for example, in the shape of an arc when viewed in the axial direction. Meat is formed. As this type of tripod joint boot, the inventors of the present application have previously proposed a technique described in Japanese Patent No. 4359532 (see Patent Document 1). In this prior art, it is possible to integrally form a thick portion and a thin portion continuously in the circumferential direction on the inner peripheral surface of the large-diameter end portion of the preform. It is characterized by facilitating the pulling out of the boot from the core mold even if it has an undercut portion.

2. Description of the Related Art In recent years, in order to meet the demand for low fuel consumption and low cost of automobiles, further weight reduction of various parts has been attempted.

Therefore, there is an increasing demand for weight reduction of this type of tripod joint boot, and the structure disclosed in Patent Document 2 has been proposed as a constant velocity joint boot improved with a focus on weight reduction. Proposed.
In Patent Document 2, the weight is reduced by removing the thickness from the outer surface side of the thick portion of the large-diameter end portion (see Patent Document 2).
In addition, such a lightening structure is such that the tripod joint boot (constant velocity joint boot) of this type has a thick portion and a thin portion having different thicknesses at the large-diameter side end. Since there is a risk of shrinkage during molding, it also has the role of preventing shrinkage (sink marks) 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 by tightening the outer peripheral surface of the large diameter side end using a metal tightening band. A lip portion protruding from the inner peripheral surface of the large-diameter end portion is pressed against the outer peripheral surface of the outer casing for sealing.
At this time, it is preferable to concentrate the tightening force of the tightening band on the lip portion protruding from the inner peripheral surface of the large-diameter end portion, in order to improve the sealing performance.

However, in the case of the structure of the tripod joint boot disclosed in Patent Document 2, since the outer peripheral surface of the large-diameter end on the side where the tightening band comes into contact is lightened, the open side of the lightened groove is tightened. Facing the band, the area where the tightening band contacts is small.
In other words, in the tripod joint boot disclosed in Patent Document 2, a hollowed out groove is located in the lower portion of the band where the greatest 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 of the groove (the outer peripheral surface of the end on the large diameter side) is greatly deformed, and the tightening force is not concentrated on the lip (lip The tightening force at the part is weak.) This point will also be described in detail in comparison with the embodiments described later.

In addition, when forming the lightening portion on the outer peripheral side of the large-diameter end portion, a parting line at the time of molding appears on the outer peripheral surface.
As mentioned above, the outer peripheral surface of the large-diameter end is the fastening surface of the tightening band, so it is preferable that it be a flat surface without unevenness. , there is a risk of causing a decrease in tightening force.

Furthermore, since the location where the constant velocity joint boot is installed is in a harsh environment where muddy water and dust are scattered, as disclosed in Patent Document 2, a lightening groove is provided on the outer peripheral side of the large diameter side end. is provided, there is a risk that dust, stones, mud, muddy water, etc. will enter the groove, resulting in a decrease in fastening force.
In addition, since the fastening band is made of metal, if chemicals such as road surface antifreeze agents or muddy water accumulate, the fastening band is likely to be damaged (rust, scratches), etc., and the life of the product may be shortened.

Japanese Patent No. 4359532 JP-A-2002-13546

The present invention has been made in view of the problems of the prior art, and its object is to reduce the weight of the tripod joint boot while imparting an appropriate tightening force by means of a fastening band. Another object of the present invention is to provide a boot for a tripod joint which can prevent the decrease in tightening force and maintain good sealing performance.

In order to achieve such a task, a first aspect of the present invention provides an annular large-diameter end into which an outer casing of a tripod joint is inserted;
an annular small-diameter end into which the shaft connected to the tripod joint is inserted;
A boot for a constant velocity joint comprising a bellows portion which is integrally provided in a continuous manner between the large diameter side end portion and the small diameter side end portion, and which is formed by repeatedly arranging the large diameter portion and the small diameter portion. There is
The inner peripheral surface of the large-diameter end has a plurality of thick-walled portions formed to fit in a plurality of recesses formed on the outer peripheral surface of the outer housing and protrude in the inner diameter direction of the boot, and the plurality of thick-walled portions. a thin wall portion disposed between the wall portions;
A circumferentially continuous lip portion is formed on the inner peripheral surface of the thick portion and the inner peripheral surface of the thin portion so as to come into contact with the outer peripheral surface of the outer housing including the recess and seal the inner region of the boot. cage,
At least one or more grooves recessed in the boot outer diameter direction from the inner peripheral surface side are formed in the thick portion,
The groove portion is formed along the circumferential direction of the thick portion,
The boot for a constant velocity joint is characterized in that the outer peripheral surface of the thick portion that contacts the tightening band is flat .

A second aspect of the present invention is the first aspect of the present invention, wherein two or more lip portions are formed,
At least two of the lip portions are positioned across the groove portion in the axial direction of the boot.

A third aspect of the present invention is the first aspect of the present invention or the second aspect of the present invention, wherein the thick portion extends in the circumferential direction of the large-diameter end portion when viewed from the bottom surface side of the large-diameter end portion. The constant velocity joint boot is characterized in that it is formed in an arc shape that rises and slopes from the left and right skirts toward the top.

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 axial direction of the boot at the bottom portion of the thick portion is narrower than the groove width in the axial direction of the boot at the top portion of the thick portion. The constant velocity joint boot is characterized by:

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

According to a sixth aspect of the present invention, in any one of the first aspect to the fifth aspect of the present invention, the groove portion is opposed to the axial direction of the boot and is provided with a rib bridging between inner wall surfaces constituting the groove portion. The constant velocity joint boot is characterized by:

A seventh aspect of the present invention is a tripod joint having a plurality of recesses on its outer peripheral surface, a large-diameter end into which an outer casing of the tripod joint is inserted, a small-diameter end into which a shaft connected to the tripod joint is inserted, a bellows portion formed between the large-diameter end portion and the small-diameter end portion and formed by repeatedly arranging the large-diameter portion and the small-diameter portion; , a plurality of thick-walled portions formed so as to fit in the recesses of the outer housing of the tripod joint and protrude toward the inside diameter of the boot, and a thin-walled portion disposed between the plurality of thick-walled portions, etc. A method of manufacturing a quick joint boot, comprising:
A core mold is placed in the large-diameter end of a pre-formed product having a small-diameter end and a large-diameter end communicating with the internal space of the bellows portion, and at least the size of the pre-form is large. A holding mold is arranged on the outer peripheral surface side of the diameter side end,
The upper 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. is brought into contact with the outer peripheral surface of
A secondary molded portion comprising a plurality of thick portions and a plurality of thin portions on the large diameter side end between the inner peripheral surface of the large diameter side end portion of the preform and the lower peripheral surface portion of the core mold. A step of forming a secondary molding space for molding the
a step of injecting a molten material into the secondary molding space to form a secondary molding portion comprising a thick portion and a thin portion at the large diameter side end portion of the preform;
including at least
The upper protruding portion corresponding to the thick portion forming space constituting the secondary forming space, and the lower protruding portion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold are arranged in the core. a step of retracting the mold in the central axis direction to remove it from the thick portion molding space region of the secondary molding space, and separating the core mold and the boot in this state;
A method of manufacturing a constant velocity joint boot characterized by:

The eighth aspect of the present invention is the seventh aspect of the present invention, in which one or both of the upwardly projecting portion and the downwardly projecting portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space are A method of manufacturing a boot for a constant velocity joint characterized in that the boot is retracted from the thick-walled region by driving a cam member that turns around the central axis of the core mold or an axis parallel to the central axis of the core mold. .

A ninth aspect of the present invention is the seventh aspect of the present invention or the eighth aspect of the present invention, wherein the downward protruding portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space includes: A method of manufacturing a boot for a constant velocity joint characterized by having a mold surface for forming a groove formed in a part.

A tenth aspect of the present invention is a tripod joint having a plurality of recesses on its outer peripheral surface, a large-diameter end into which an outer casing of the tripod joint is inserted, a small-diameter end into which a shaft connected to the tripod joint is inserted, a bellows portion formed between the large-diameter end portion and the small-diameter end portion and formed by repeatedly arranging the large-diameter portion and the small-diameter portion; , a plurality of thick-walled portions formed so as to fit in the recesses of the outer housing of the tripod joint and protrude toward the inside diameter of the boot, and a thin-walled portion disposed between the plurality of thick-walled portions, etc. A quick joint boot manufacturing device comprising:
a holding mold for holding an outer surface of a preform having a small-diameter end and a large-diameter end communicating with the internal space of the bellows portion;
a core mold inserted into the large-diameter end of the preform;
For molding a secondary molding portion consisting of a plurality of thick portion molding spaces and a plurality of thin portion molding spaces formed between the inner peripheral surface of the large diameter side end of the preform and the outer peripheral surface of the core mold. and an injection mechanism that injects and fills the molten material into the secondary molding space of
The holding mold has an inner peripheral surface capable of coming into contact with the outer peripheral surface of the large-diameter end,
The core mold has a plurality of thicknesses between an upward protruding portion capable of coming into contact with 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 portion forming a secondary molding space for molding a secondary molding portion composed of a thick 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;
The upper protruding portion and the lower protruding portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space are capable of moving forward toward the thick portion molding space and directed toward the center axis of the core mold. The constant velocity joint boot manufacturing apparatus is characterized in that the constant velocity joint boot can be retracted.

According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, the cam member has a cam member that turns around the core mold central axis or an axis parallel to the core mold central axis,
Either one or both of the upward and downward protrusions of the core mold corresponding to the thick portion molding space constituting the secondary molding space are moved toward the thick portion molding space by the cam member. The constant velocity joint boot manufacturing apparatus is characterized by being capable of moving forward and retractable toward the central axis of the core mold.

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

According to the present invention, it is possible to reduce the weight of the constant velocity joint boot, provide an appropriate tightening force by the fastening band, prevent the tightening force from decreasing, and maintain good sealing performance. We were able to provide quick joint boots.

1 is a schematic longitudinal sectional view showing an embodiment of a constant velocity joint boot of the present invention; FIG. 1 is a schematic bottom view showing an embodiment of a constant velocity joint boot of the present invention; FIG. 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. FIG. 10 is an enlarged schematic perspective view showing another embodiment of a thick portion in which ribs are formed across the opposing inner wall surfaces of a pair of thick portion forming bodies forming the thick portion. FIG. 10 is an enlarged schematic perspective view showing another embodiment of a thick portion in which ribs are formed across the opposing inner wall surfaces of a pair of thick portion forming bodies forming the thick portion. FIG. 6B is a schematic enlarged view of the thick portion viewed from a direction perpendicular to the inner peripheral surface of the large-diameter end portion of FIG. 6B; FIG. 5 is a partial schematic diagram showing a difference in groove width; It is a schematic longitudinal cross-sectional view which compares the thick part of this invention, and the thick part of a comparative example. FIG. 3 is a schematic plan view of the core mold used in the manufacturing apparatus of the present invention, showing a state in which the second mold portion is extruded toward the thick portion molding space. FIG. 4 is a schematic vertical cross-sectional view of the core mold used in the manufacturing apparatus of the present invention, showing a state in which the second mold portion is extruded toward the thick portion molding space. FIG. 3 is a schematic plan view of the core mold used in the manufacturing apparatus of the present invention, showing a state in which the second mold portion is retracted from the thick portion molding space. FIG. 4 is a schematic vertical cross-sectional view of the core mold used in the manufacturing apparatus of the present invention, showing a state in which the second mold portion is retracted from the thick portion molding space. 1 is a schematic perspective view of a core die used in a manufacturing apparatus of the present invention, partly omitted and indicated by broken lines; FIG. It is a schematic diagram showing the flow of the whole manufacturing method of the present invention. FIG. 10 is a schematic vertical cross-sectional view showing another embodiment of the core mold used in the manufacturing apparatus of the present invention, showing a state in which the first member and the second member are positioned in the thick portion molding space. FIG. 10 is a schematic longitudinal sectional view showing another embodiment of the core mold used in the manufacturing apparatus of the present invention, showing a state in which the first member and the second member are retracted from the thick portion molding space. FIG. 5 is a schematic partial enlarged cross-sectional view of another embodiment of the constant velocity joint boot of the present invention, in which a space is formed between the inner surface of the inclined portion and the upper surface of the secondary molded portion;

An embodiment of the present invention will be described below with reference to the drawings. It should be noted that this embodiment is merely one embodiment of the present invention and is not to be construed as being limited to this, and design changes are possible within the scope of the present invention.

"First Embodiment"
An 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.

[Explanation about 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 the 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 arcuate cross-sectional view are formed at approximately 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 has a large diameter side end 3 into which the outer housing of the tripod joint is inserted, and an inner diameter and an outer diameter than the large diameter side end 3. It has a small-diameter side end portion 5 formed to have a small diameter. A shaft portion of a drive shaft connected to a tripod joint is inserted into the small-diameter end portion 5 . A bellows portion 7 formed in a bellows shape is provided between the large-diameter end portion 3 and the small-diameter end portion 5 .
In the boot 1, the large-diameter end portion 3, the small-diameter end portion 5, and the bellows portion 7 are integrally formed by a known preforming process using resin such as thermoplastic elastomer (hereinafter referred to as this molded article). will be referred to as a preform.) Further, on the inner peripheral side of the large-diameter end portion 3 of the preform, two portions having different thicknesses are formed using a resin such as thermoplastic elastomer. A subsequent molding portion 13 is integrally molded.

As shown in FIG. 1, the bellows portion 7 is formed to have a large diameter, a large diameter portion (also referred to as a mountain portion) 7a formed so that the outer side of the boot 1 is convex, and a small diameter portion, A small-diameter portion (also referred to as a trough portion) 7b formed to be concave on the outer side of the boot 1 is repeatedly formed in the axial direction of the boot 1. As shown in FIG. For example, in the case of this embodiment, there are five large-diameter portions 7a and five small-diameter portions 7b arranged on the large-diameter end portion 3 side with respect to the five large-diameter portions 7a. is configured as Each of the large-diameter portion 7a and the small-diameter portion 7b is formed such that its diameter increases sequentially from the small-diameter end portion 5 toward the large-diameter end portion 3, and as a result, the boot 1 as a whole is substantially frusto-conical. formed in the shape of

In the present invention, the bellows portion 7 is not particularly limited. Best conditions apply.
Further, in this 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 desired uniform thickness. These thicknesses are not particularly limited, and optimal arbitrary thicknesses are selected.
Various conditions of the large-diameter end portion 3 and the small-diameter end portion 5 are not particularly limited, and optimum conditions are appropriately applied within the scope of the present invention. In this embodiment, the large-diameter side end portion 3 and the small-diameter side end portion 5 have a uniform thickness, but 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 portion 3, which is a preform, is formed in a substantially circular shape, and the outer peripheral surface 15 is provided with a band for attaching the boot 1 to the tripod joint. A portion 37 is recessed. The secondary formed portion 13 formed inside the outer peripheral surface 15 includes a plurality of thick portions 17 formed to protrude toward the inner peripheral side, and a plurality of thick portions 17 formed between the thick portions 17 . A single thin portion 19 is provided.
In the case of this embodiment, for example, three thick portions 17 are formed at approximately equal intervals in the inner peripheral direction of the large diameter side end portion 3 , and between the adjacent thick portions 17 . is formed with three thin portions 19 having a substantially constant thickness along the circumferential direction.

The thick portion 17 is formed between a pair of thick portion forming bodies (bases) 17a, 17a and between the pair of thick portion forming bodies 17a, 17a. and a groove portion 18 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 continuously formed in the circumferential direction of the thick portion 17. (See FIGS. 1 to 8).

When viewed from the bottom side of the large-diameter end portion 3, the thick portion forming body 17a rises from left and right skirt portions 17b, 17b toward the top portion 17c in the circumferential direction of the large-diameter end portion 3. It is formed in a slanted bottom view shape and is formed to protrude in an arc shape (see FIG. 2).
The approximate arc shape of the thick portion 17 (thick portion forming body 17a) is set so as to fit 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, the pair of thick portion constituents 17a and 17a are formed with the same axial width (thickness), but the pair of thick portion constituents 17a and 17a have different axial widths (thicknesses). is within the scope of the present invention.

The groove shape of the groove portion 18 in the boot radial direction (R1) is such that from the inner peripheral surface of the thick portion (groove opening position near the top portion 17c of the thick portion forming body 17a) to the large diameter side end portion 3, It is formed so as to become narrower in the radial 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 end portion 3 is indicated by W2 (see FIGS. 4, 7 and 8). In this embodiment, the width is slightly narrowed, but the shape is not limited to that. The same width is not excluded, and the design can be changed within the scope of the present invention.

A groove width W3 in the axial direction of the boot between the bottom portions 17b, 17b facing each other is narrower than a groove width W4 in the axial direction of the boot between the top portions 17c, 17c facing each other (see FIG. 5). .
In the present embodiment, the axial width (thickness) of the hem portion 17b of each thick portion forming body 17a is made larger than the axial width (thickness) of the top portion 17c, so that the groove width W3 and A relationship of W4 is formed. By increasing the axial width (thickness) of the bottom portion 17b in this way, the rigidity of the top portion 17c with respect to the bottom portion 17b can be reduced, that is, it can be softened. As a result, it is possible to improve the adhesion of the lip portion, which will be described later, and to improve the effect of preventing grease leakage.

At least one or more grooves 18 may be provided, and the number of grooves 18 to be provided is not limited. Further, in the present embodiment, the grooves are formed in a continuous groove shape in the circumferential direction, but intermittent grooves are also within the scope of the present invention.

As shown in FIGS. 1 to 8, on the inner peripheral surface of the large-diameter side end portion 3, the surfaces of the thick portion forming bodies 17a of the thick portion 17 (the inner peripheral surface of the thick portion) are formed. ) and the surface of the thin-walled portion 19 (inner peripheral surface of the thin-walled portion), a lip continuous in the circumferential direction and arranged in parallel to contact the outer peripheral surface of the outer housing including the recess to seal the inner region of the boot. Portions (seal lips) 21a and 21b are provided.
These lip portions (seal lips) 21a and 21b seal the interior region of the boot to prevent grease from leaking and to 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 extend in the axial direction of the boot (direction indicated by arrow S1 in the figure). are located across the groove portion 18 at the .
The lip portions (seal lips) 21a and 21b are formed as ridges having, for example, a substantially triangular or trapezoidal cross-sectional shape. Although not shown, the tops of the lip portions (seal lips) 21a and 21b are rounded.
In this embodiment, two lip portions (seal lips) 21a and 21b are provided, but the number and shape of the lip portions are not limited. Can be changed.

The thick portion 17 of the present embodiment and the thick portion of the boot disclosed in Patent Document 2 are compared with each other based on FIG. 8 as follows.
FIG. 8(a) is a view when the thick portion 17 of the present embodiment is tightened and fixed in the axial groove 201 of the outer housing 200 via the tightening band 300, and (b) is a boot disclosed in Patent Document 2. FIG. 10 shows a view when the thick portion is tightened and fixed to the axial groove 201 of the outer casing 200 via the tightening band 300. FIG.
In order to facilitate understanding of the differences, the thick portion 17 of the present embodiment and the thick portion of Patent Document 2 have substantially the same shape, and only the arrangement position of the groove portion 18 is changed. , and the thick portions of Patent Document 2 are also denoted by the same reference numerals as in the present embodiment.

In the case of this embodiment, A is the region of the band fastening portion 37 with which the tightening band 300 contacts, B is the solid region directly below the band fastening portion 37, C is the region where the groove portion 18 is provided, and C is the lip portion 21a (21b). Define the region as D.
On the other hand, in the case of the thick portion disclosed in Patent Document 2, A is the region of the band fastening portion 37 with which the tightening band 300 contacts, B is the region immediately below the band fastening portion 37 where the groove portion 18 is provided, A solid region between the groove 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 this embodiment, tightening of the tightening band 300 causes the tightening force applied to A to be transmitted from A to C via B. FIG. Here, since B is composed of a solid region, the tightening force is transmitted to C almost as it is. Since C has a smaller cross-sectional area (volume that can receive a load) due to the presence of the groove 18, the tightening force transmitted to the base of C is transferred to the top D, that is, the lip portion 21a (21b). ). Furthermore, since C is less rigid and elastically deformable than B, which is a solid region, C can elastically apply the tightening force transmitted to B to D.
Furthermore, the area (cross-sectional area) of region C is configured to gradually decrease toward the lip portion 21a (21b), thereby adopting a configuration in which deformation tends to gradually occur toward the top, thereby reducing running vibration. As a result, even if the outer casing of the tripod joint, which is the mating member with which the lip portion 21a (21b) abuts and seals, is slightly shaken due to vibration or the like, the tightness 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 is transmitted from A to C via B by tightening the tightening band 300 . Here, since B has a groove 18 that opens in the outer diameter direction, the cross-sectional area (the volume that can receive a load) is small, so B deforms and absorbs the tightening force, The clamping force transmitted from A through B is less. In other words, the tightening force transmitted from A is lost in the region B. Furthermore, since the area C is solid and has a large area (the volume that can receive a load), it is difficult for the area C to deform with a small tightening force transmitted through B (the diameter cannot be greatly reduced). Therefore, the tightening force is not concentrated on the lip portion 21a (21b) existing in the area D, and the pressing force against the outer casing of the tripod joint, which is a mating member, is small, and the outside of the tripod joint due to vibration etc. If the housing is displaced, there is a possibility that the adhesion cannot be maintained.
Therefore, in the case of this embodiment according to the present invention, it is possible to elastically apply a sufficient tightening force to the outer housing of the tripod joint, which is the mating member. It is possible to have a structure that can maintain a good airtightness.

Furthermore, in molding the groove 18, the width W1 on the opening side of the groove 18 is formed to be larger than the width W2 on the inner bottom surface side in consideration of ease of mold removal. Therefore, in the case of Patent Document 2, since the area of B is further reduced, the deformation of the area of B is increased and the loss of force is increased, thereby deteriorating the sealing performance. On the other hand, according to the present embodiment, since the opening side of the groove 18 having the larger 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. It will be done.

Therefore, in the case of Patent Document 2, as described above, the groove portion 18 exists in the region B, and this region is greatly deformed and the band fastening force is greatly lost, and the band fastening reaches the lip portion 21a (21b). In the case of this embodiment, the area gradually increases from the area A near the tightening band 300 to the area D where the lip portion 21a (21b) exists. is reduced, force is concentrated 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 according to the region C, that is, the size (width W1, W2), depth, and shape of the groove, the sealing performance is extremely high. expected to be effective.

According to this embodiment, as described above, it is possible to improve the sealing performance and reduce the weight of the boot as a whole, so that the initial problem can be sufficiently achieved, and the needs of consumers can be fully met. .
Further, by changing the circumferential width of the groove portion 18 between the width W4 of the central region of the groove portion 18 (the region between the top portions 17c and 17c) and the width W3 between the skirt portions 17b and 17b, the lip portion (seal lip 21a , 21b), it is possible to appropriately adjust the band tightening force, 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 unevenness of the material volume between the thick portion 17 and the thin portion 19 can be reduced, so the difference in the amount of shrinkage during molding can be reduced, and the problem of shrinkage can be reduced. difficult to occur.
Further, by providing the groove portion 18 in the thick portion, it is possible to reduce the amount of resin material used and the manufacturing cost.

As shown in FIG. 6A, the groove portion 18 includes ribs that bridge between axially opposite inner wall surfaces 17d, 17d of the pair of thick portion constituent bodies 17a, 17a that constitute the groove portion 18, respectively. It is possible to employ a configuration in which a (bearing wall) 20 is provided.

By bridging the ribs 20 in this manner, the strength of the thick portion 17, that is, the thick portion forming bodies 17a, 17a can be maintained, and unexpected deformation can be suppressed.
Although the ribs 20 are not particularly limited, the size of the ribs 20 can be changed within a range that can reduce the weight of the boot as a whole. It is also possible to arrange Further, in the present embodiment, the rib 20 is formed integrally with the thick portion 17 by a manufacturing method to be described later. is within the range of
The width of the rib 20 on the base end side (groove inner bottom surface side) can be made larger than the width on the tip side (groove opening side).

In the present embodiment, the outer wall 17e of the thick portion forming body 17a positioned axially inward and the outer wall 17f of the thick portion forming body 17a positioned axially outward are provided with Although ribs are not provided to prevent the respective thick portion forming bodies 17a from collapsing, they may be provided, and the design can be changed within the scope of the present invention.
Since other configurations and effects are the same as those in FIG. 5, the same reference numerals are given to the same portions and the description thereof will be omitted.

The width (thickness) of the thick portion forming body 17a in the axial direction S1 is not particularly limited. preferable.
6B and 6C show another embodiment in which the width (thickness) in the axial direction S1 of the thick portion forming body (base) 17a is made thicker than in FIGS. 5 and 6A. 1 shows an embodiment.
6B and 6C, the thick portion forming body (base) 17a shown in FIGS. It is made thicker than the thick portion forming body (base) 17a.
In this embodiment, the convex portion 22 is integrally provided continuously with the thick portion forming body (base) 17a on the inner side (inner side in the axial direction). is provided toward the inner surface of the small diameter portion 7b. Further, in the present embodiment, a portion of the convex portion 22 is thinned in a predetermined range to reduce the weight (in the drawing, reference numeral 22a indicates the thinned portion).
Since other configurations and effects are the same as those in FIGS. 5 and 6A, the same reference numerals are given to the same portions and the description thereof will be omitted.

The thermoplastic resin that constitutes the preformed product consisting of the large-diameter end portion 3, the small-diameter end portion 5, and the bellows portion 7, and the secondary molded portion 13 that consists of portions with different thicknesses is not particularly limited, and the thermoplastic resin of the present invention is not particularly limited. An optimum material is selected within the range, and it is within the scope of the present invention whether they are the same material, different hardness materials, or different materials. It should be noted that the portion of the secondary molded portion 13 having a different thickness is preferably made of a material having good sealing properties, while the preformed product is made of a material purely intended for its original purpose, namely 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 to manufacture the constant velocity joint boot of the present invention will be described.

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, will be described as follows. 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, the inner surface of a holding mold (split mold) 51 is formed with a contour 57 to which the external shape of the preform is closely attached (holding the outer surface of the preform). When the (split mold) 51 is clamped, a preformed product accommodation space 55 is formed that matches the external shape (outer contour) of the boot 1 .
In this preformed article accommodation space 55, the opening edge 59 of the outer peripheral surface 15 of the large diameter side end portion 3 of the preformed article accommodated in the preformed article accommodation space 55 at the time of mold clamping is a holding mold (split mold). It is formed so as to be positioned on the same plane as the lower end surface 51a of 51 .

As shown in FIG. 14, the stationary platen 49a of the mold 49 is formed with a gate 47 for injecting the thermoplastic resin into the secondary molding space 43 through runners 45. As shown in FIG. In this embodiment, the gate 47 is provided at one or more selected locations 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, the injection gate 47 to the thick portion molding space 43a The thin part molding space 43b also serves as a narrow runner, and the molten material is instantly sent to the thick part molding space 43a at high speed and high temperature while maintaining a high temperature state, so there is no weld or air entrainment. , the inner surface of the large-diameter end portion 3 of the preform and the outer surface of the secondary formed portion 13 are welded.
Of course, the gate 47 may be provided at any one or more locations in the thick portion molding space 43a, or at any one or more locations including the thin portion molding space 43b and the thick portion molding space 43a. It is possible to select and prepare without any problem.
The gate 47 may be provided in the thick portion molding space 43a, and the thermoplastic resin may be injected from only the thick portion molding space 43a or from a plurality of locations including the thick portion molding space 43a. From the viewpoint of preventing defects, it is preferable to provide the thin portion molding space 43b with the gate 47 as in the present embodiment.

The core die 69 is provided between the upper protrusions 74 and 81 a that can contact the inner peripheral surface of the bellows portion 7 or the inner peripheral surface of the large diameter end portion 3 and the inner peripheral surface of the large diameter end portion 3 . Lower peripheral surface portions 76a and 81c forming a secondary molding space 43 for molding a secondary molding portion consisting of a plurality of thick portions and a plurality of thin portions, and a core mold on the lower peripheral surface portions 76a and 81c The core mold 69 corresponds to the thick portion molding space 43a that constitutes the secondary molding space 43. The upward projecting portion 81a and the downward projecting portion 81b are configured to be able to move forward toward the thick portion molding space 43a and retract toward the center axis direction of the core mold 69. As shown in FIG.

As shown in FIGS. 9 to 14, the core die 69 is provided in the central part and configured to be horizontally rotatable around the central axis, and includes a rotary piece 89 (cam member 99), a first mold portion (base portion) 70 forming thin portion molding spaces 43b provided alternately in the circumferential direction around the rotating piece portion 89 (cam member 99), and a thick portion molding space. The whole is formed in a disk shape with a desired thickness by the second mold portion 79 forming 43a.
Further, the outer diameter of the core mold 69 is designed so as 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 preform. 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 fan shape in plan view, and is at least closer to the small diameter side end 5 than the small diameter portion 7b closest to the large diameter side end 3 of the preform. A tip end face (upper end face in FIG. 10) located in the outer diameter direction than the inner face of the small diameter portion 7b and a lower end face (lower end face in FIG. 10) located on the same plane as the end face 3a on the large diameter side. ) 72.
Three pieces are provided with a desired interval in the circumferential direction centering on the rotary piece portion 89, and the inner surface of the small diameter portion 7b of the preform, which is in the vicinity of the large diameter side end portion 3, of the preform is fitted to the outer periphery of the upper end side. A concave circumferential groove (upward projection) 74 is provided. A surface portion (lower peripheral surface portion) 76 a is provided to form the inner surface shape of the thin portion 19 formed between the inner peripheral surface of the side end portion 3 .

A second mold portion sliding groove 90 is provided between the adjacent first mold portions 70, 70 so that the second mold portion 79 can slide (slid) in the radial direction (horizontal direction). (See FIG. 13).

In the groove 90 for sliding the second mold portion, two interior plate portions 91, 91 are arranged horizontally across the groove inner side surfaces 90a, 90a facing each other with a predetermined interval in the vertical direction.
The interior plate portion 91 has a flat rear surface 91a facing the rotary piece portion 89 disposed in the center of the core mold, and a curved front surface 91b facing the thick portion molding space 43a that is recessed in the direction of the rear surface 91a. (See FIG. 13).

These two interior plate portions 91, 91 are used to form thick portion forming bodies (bases) 17a, 17a that constitute the thick portion 17, and the second die portion 79 is the thick portion. When moved in the direction of the molding space 43a, the second member 92 of the second mold portion 79 is accommodated in two deep grooves 93, 93 recessed inward from the tip of the downward projecting portion 81b.
When the interior plate portions 91, 91 are accommodated in the two deep grooves 93, 93, the plate portion front surfaces (curved surface portions) 91b, 91b and the openings 93a, 93a of the deep grooves 93, 93 , are provided at predetermined positions of the groove inner side surfaces 90a, 90a so that predetermined cavities (molding spaces) 110, 110 for molding the thick portion forming body (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 the first mold portion 70 and the It is configured to be slidable in the central axis direction of the core mold 69 or slidable in the direction of the thick portion molding space 43a on the integrally provided fixed portion 80 in accordance with the lateral rotation of the rotary piece portion 89. It is

The second mold portion 79 has a width provided between the adjacent first mold portions 70 and 70 and has the same thickness (thickness in the vertical direction) as that of the first mold portion 70 . Three pieces are provided in the circumferential direction centering on the piece portion 89 .
The second mold portion 79 is composed of a first member 94 and a second member 92 that are arranged in the vertical direction. A sliding surface portion 95 formed in a circular arc shape in a plan view is provided on the side facing the piece portion 89 (cam member 99), and an outer periphery composed of an upward projecting portion 81a and a downward projecting portion 81b is provided on the opposite surface. A face 81 is formed.

The second mold portion 79 is internally provided with a core material 79a that is vertically erected. A tension spring 96 is bridged therebetween and biased so that the core mold 69 is pulled toward the center. That is, each of the three second mold portions 79 is pulled in the center direction of the core mold 69 by a tension spring 96 that spans between each of the three second mold portions 79 and the core material 89a that is housed in the rotary piece portion 89 (cam member 99). is biased to

When the second mold portion 79 is pushed out by the rotating piece portion 89 and protrudes into the thick portion molding space 43a, the first member 94 is formed in the circumferential direction with the recessed circumferential groove 74 of the first mold portion 70. The second member 92 is provided with an upward protrusion 81a having a recessed circumferential groove 85 that communicates with the outer peripheral surface of the upper end side. A downward protruding portion 81b is provided on the lower peripheral surface portion 81c as a mold surface for forming the groove portion.

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

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

The rotary piece portion 89 is composed of a core member 89a and a cam member 99 attached to the core member 89a. The core member 89 a is erected vertically at substantially the center of the core mold 69 and arranged 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 plan view, and has three recessed side portions 99a, 99a, 99a formed with gently curved surfaces in which respective central regions are recessed in plan view. and three convex side portions 99b, 99b, and 99b formed between the respective concave side portions 99a.
Also, on the top surface of the cam member 99, there is provided a protrusion 100 in which a locking groove 100a for locking the locking arm 101a of the operating member 101 is recessed.
That is, by rotating the rotary piece 89 (cam member 99) in the horizontal direction about the central axis of the core die 69, the sliding surface 95 of the second die 79 is moved to the above-described position. It slides linearly in the horizontal direction along the convex side portion 99b and the concave side portion 99a.
For example, in the present embodiment, when the rotating piece 89 (cam member 99) is rotated and the convex side surface portion 99b reaches a position where it presses the sliding surface portion 95 of the second mold portion 79, the second mold portion 79 slides (moves forward) so as to position the downward protruding portion 81b in the thick portion molding space 43a, and rotates the rotary piece portion 89 (cam member 99) in the opposite direction, thereby forming the second mold portion 79 slides (backwards) 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, and the downward protrusion provided on the lower end side outer peripheral surface of the tip of the second member 92. 81b is retracted from the thick portion 17 area.

The operation member 101 is a desired rotatable member having a three-pronged locking arm portion 101a at its tip. It is engaged with the three-pronged engaging groove 100a and rotated in the horizontal direction by a predetermined angle, approximately 60 degrees in this embodiment. Note that the operation member 101 is not limited to the present embodiment, and can be appropriately selected within the scope of the present invention as long as it has a configuration that allows the cam member 99 to be rotated by a predetermined angle in a predetermined direction. be. Further, the operating member 101 may be of 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 area below the cam member 99 to automatically rotate 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 of manufacturing a constant velocity joint boot using the manufacturing apparatus (core mold 69).

The manufacturing method of the present embodiment is composed of "preforming process"→"secondary forming process"→"boot drawing process".

"Preforming process"
Blow molding, injection blow molding, and the like are well known as methods for molding the preform comprising the large-diameter end portion 3, the small-diameter end portion 5, and the bellows portion 7, but are not particularly limited. An optimum molding method is appropriately applied within the scope of the invention.

"Secondary molding process"
In this step, a core mold 69 is inserted into the large-diameter side end portion 3 of a preform formed by preforming and held in the injection mold 49, and a desired shape is placed in the mold 49. By injecting the molten material, a secondary molded portion 13 consisting of a thick portion 17 and a thin portion 19 is formed between the inner surface of the outer peripheral surface 15 of the large-diameter end portion 3 of the preform 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, description thereof will be omitted.

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

"(1) Step of forming secondary molding space"
For example, first, the preform is attached to the core die 69 by arranging the inner periphery of the large-diameter end portion 3 of the preform so that it comes to the outer periphery of the core die 69 that is provided in advance on the side of the stationary platen 49a. (FIG. 14(a)).
Next, the preformed product having the large-diameter end 3 attached to the outer periphery of the core mold 69 as described above is placed in the mold 49 by clamping the holding mold (split mold) 51 . (Fig. 14(b)).
At this time, the core die 69 engages the three-pronged locking arm portion 101a of the operating member 101 with the three-pronged locking groove portion 100a provided on the projection portion 100 of the rotary piece portion 89 (cam member 99). By rotating the rotating piece 89 (cam member 99) by a predetermined angle (60 degrees in this embodiment) in a predetermined direction (right or left direction), the convex side surface of the rotating piece 89 (cam member 99) is rotated. When the portion 99b reaches the position where it presses the sliding surface portion 95 of the second mold portion 79, the second mold portion 79 moves into the thick portion molding space 43a with the downward projecting portion 81b (the deep grooves 93, 93, the plate member for forming the groove portion). 97) is slid (moved forward).

When the holding mold (split mold) 51 is clamped in this way, as shown in FIG. A ridge 53 on the inner surface of a mold (split mold) 51 is fitted, and recessed circumferential grooves 74 and 85 of a core mold 69 are fitted on the entire inner surface of the small diameter portion 7b to form a holding mold (split mold). The small-diameter portion 7b is sandwiched between the ridges 53 of 51 and the recessed circumferential grooves 74, 85 of the core die 69. As shown in FIG.

Through these steps, the inner peripheral surface of the large-diameter end portion 3 is thickened between the inner peripheral surface of the large-diameter end portion 3 of the preform and the outer peripheral surfaces 76 and 81 of the core mold 69 . A secondary molding space 43 is formed for molding the secondary molding portion 13 consisting of the thick portion 17 and the thin portion 19 .
That is, in the secondary molding space 43, in this 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 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 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, two deep grooves recessed inward from the tip of the downward projecting portion 81b of the second member 92 of the second mold portion 79. The two interior plate portions 91, 91 provided in the second mold portion sliding groove 90 are accommodated in the interior plate portions 93, 93, respectively. Predetermined cavities (molding spaces for the thick portion forming body 17a) 110, 110 for molding the thick portion forming member (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, 93 passes between the two interior plate portions 91, 91 and protrudes into the thick portion molding space 43a. be prepared.
The present process described above is merely an example, and it is also possible to employ other processes within the scope of the present invention, and the design can be changed as appropriate.

"(2) Step of molding the secondary molded portion"
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 process.
Then, through the injection point, a thermoplastic resin heated to a high temperature of 260° C. or higher, for example, is injected at a high speed into the secondary molding space 43, and the large diameter side end 3 of the preform is injected. A secondary molded portion 13 consisting of a thick portion 17 and a thin portion 19 is integrally formed on the inner peripheral surface of the .
That is, the molten material injected from the thin portion molding space 43b flows into the thick portion molding space 43a, and the two deep grooves 93, 93 provided on the tip surface of the second mold portion 79 and the second mold portion slide A predetermined cavity (molding space for the thick portion constituting body 17a) for molding the thick portion constituting body (base) 17a formed by the two interior plate portions 91, 91 provided in the moving groove 90. The molten material enters 110, 110, and the thick portion forming bodies 17a, 17a and the groove portion 18 are integrally molded.
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 cause any problems.

"Boot withdrawal process"
Through the secondary forming step, the boot 1 is formed by integrally forming the secondary formed portion 13 consisting of the thick portion 17 and the thin portion 19 on the inner peripheral surface of the large-diameter end portion 3 of the preform (Fig. 1).
As shown in FIG. 4, the thick-walled portion 17 on the inner surface of the large-diameter end portion 3 of the boot 1 formed in this way has a thick-walled portion forming body 17a that serves as an undercut portion protruding in the axial direction of the boot, as shown in FIG. , 17a are provided.

Before separating the core mold 69 and the boot 1, the three-pronged locking arm portion 101a of the operating member 101 is formed into a three-pronged locking groove portion provided in the projection portion 100 of the rotary piece portion 89 (cam member 99). 100 a , and rotate the rotary piece 89 by a predetermined angle (60 degrees in this embodiment) in a predetermined direction (right or left direction). The sliding surface portion 95 slides (backwards) along the recessed side surface portion 99a from the shaped side surface portion 99b, and the downward protruding portion 81b provided on the lower end side outer peripheral surface of the tip of the second member 92 moves from the thick portion 17 area. Evacuate (FIG. 14(e)).

As a result, when the thick portion 17 is pulled out from the core mold 69, there is no core mold portion that is caught by the thick portion forming bodies 17a, 17a, which are the undercut portions of the thick portion 17. 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 forming bodies 17a, 17a, which are so-called undercut portions, are retracted in the direction of the central axis of the core mold 69 when the boot 1, which is the molded product, is pulled out. Therefore, the boot 1, which is a molded product, can be easily pulled out from the core mold 69, and so-called forced pulling out can be prevented.
It should be noted that 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 another embodiment of the core mold used in the method of manufacturing the constant velocity joint boot of the present invention.

The core die 69 is composed of a plurality of (three as in the first embodiment) first die sections 70 and a plurality of (three as in the first embodiment) second die sections 79. The configuration of the second die portion 79 is different from that of the core die 69 of the first embodiment.
Therefore, the second mold portion 79 will be explained here, and the explanation of the first mold portion 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.
In the present embodiment, the upper region divided into two at the groove top surface position 93b that constitutes 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. 92 (see FIG. 15).

As in the first embodiment, the first member (first rectilinear advance/retreat member) 94 is configured to be able to move forward and backward by the cam member 99 of the rotary piece (rotating core) 89, and the rear end surface ( An arc-shaped sliding surface portion 95 is provided on the core mold center axis side surface), and a recessed portion for fitting the inner surface of the small diameter portion 7b in the vicinity of the large diameter side end portion 3 of the preform on the opposite end surface. 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 portion 70 in the circumferential direction.
The first member 94 is constantly biased by a tension spring 96 so as to pull toward the central axis of the core die 69, as in the first embodiment. 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 a shaft portion 120 provided substantially at the center of the rotating piece portion 89, which will be described later.

The rotary piece portion 89 is composed of 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 disc-shaped pressing portion 122 integrally formed with the upper end of the cylindrical shaft portion 121, and a disc-shaped contact portion 123 integrally formed with the lower end of the cylindrical shaft portion 121. A vertically slidable core 130, which will be described later, is inserted into a through hole 111 provided in the vertical direction at substantially the center of the core die 69 and substantially at the center of the rotary piece 89. 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 lifting core 130 . The length of the shaft portion 120 in the vertical direction is such that the pressing portion 122 extends outward from the top surface of the rotary piece portion 89 (the top surface of the projection portion 100) when the vertical lifting core 130 is raised (when not pressed). The length is set to such an extent that the pressing portion 122 can be accommodated inside the top surface of the rotary piece portion 89 (the top surface of the projection portion 100) when the vertical lifting core 130 is lowered (when pressed). It is

The cam member 99 is formed in a substantially triangular prism shape having a deformed triangular shape in plan view, and has three recessed side portions 99a, 99a, 99a formed with gently curved surfaces in which respective central regions are recessed in plan view. and three convex side portions 99b, 99b, 99b formed between the respective concave side portions 99a, 99a, 99a.
Also, on the top surface of the cam member 99, there is provided a protrusion 100 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 about the central axis of the core die 69, the sliding surface portion 95 of the first member 94 is brought into contact with the convex side portion 99b. It slides linearly in the horizontal direction along the concave side portion 99a.
For example, in this embodiment, when the rotating piece 89 is rotated and the convex side surface 99b reaches a position where the sliding surface (arcuate surface) 95 of the first member 94 is pressed, the first member 94 slides. Moving (moving forward), the recessed peripheral groove 85 at the tip fits the inner surface of the small diameter portion 7b in the vicinity of the large diameter side end 3 of the preform, and the other surface portion on the tip side forms a thick portion molding space. Located at 43a. When the rotating piece 89 is rotated in the opposite direction, the first member 94 slides (backwards) from the convex side surface portion 99b to the concave side surface portion 99a along the sliding surface portion 95 by the tension spring 96. Then, the first member 94 is retracted from the thick portion 17 area.

The second member (second rectilinear forward/backward member) 92 is configured to be constantly biased toward the center of the core die 69 by a tension spring 140 .
The second member 92 is moved forward and backward by the up and down movement of the core for vertical movement (core for straight movement) 130, which is always pushed upward in the vertical direction by a push-up spring 150 disposed below. is configured to 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 integrally projecting substantially at the center of a base core 160, which will be described later.

For example, the rear surface 92a of the second member 92 (the surface facing the central axis of the core mold 69) 92a is formed in a tapered shape, and the side peripheral surface upper region 130b of the vertical lifting core 130 facing the rear surface 92a is The second member 92 is formed in a tapered shape that matches the tapered rear surface 92a, and when the vertical lifting core 130 is lifted by the push-up spring 150, the second member 92 is slid by the tapered upper region 130b. and moves forward to position its tip end face in the thick portion molding space 43a.
A groove-forming downward protrusion 81b is formed on the tip end surface of the second member 92, and the groove-forming downward protrusion 81b is recessed inward from the tip of the second member 92. It has two deep grooves 93 and 93 and a groove-forming plate member 97 having a predetermined thickness and projecting between the two deep grooves 93 and 93 .
As in the first embodiment, the two deep grooves 93, 93 are formed together with the two interior plate portions 91, 91 provided in the second mold portion sliding groove 90 to form the thick portion forming body (base) 17a, 17a, and the groove-forming plate member 97 passes between the two interior plate portions 91, 91 provided in the second mold portion sliding groove 90 to It is provided so as to protrude into the thick portion forming space 43a, and is used to form the groove portion 18 between the thick portion forming bodies 17a, 17a.
When the vertical lifting core 130 is pushed down against the push-up spring 150, the tapered upper region 130b causes the second member 92 to slide and move backward, and the distal end surface thereof is thick. It is retracted from the part molding space 43a.

In order to rotate the cam member 99 and move the first member 94 forward and backward, the front end locking arm portion 101a of the operating member 101 is engaged with the locking groove 100a of the protrusion 100 and rotated. Further, when moving the second member 92 forward and backward, it is necessary to move the vertical lifting core 130 up and down. This is performed by pressing the shaft portion 120, which is erected with the contact portion 123 contacting the top surface of the core 130, with the operation member 101. As shown in FIG. Since the pressing portion 122 at the upper end of the shaft portion 120 protrudes above the projecting portion 100 of the cam member 99, the lower end of the operating member 101 (the surface portion on which the locking arm portion 101a is provided) is pressed against the pressing portion. This is done by depressing 122.

In the present embodiment, the push-up spring 150 is arranged in a storage space 161 with an open upper surface recessed in a base core 160 arranged below the core mold 69 in the vertical direction. The vertical elevating core 130 is formed in a cylindrical space having a size that allows it to move up and down. In addition, although a coil spring as shown in the figure is assumed as a member for pushing up and down the core 130 for vertical movement, it is not limited to this, and other spring members such as leaf springs can be used. The design can be changed within the scope of the invention, and it is also possible to adopt a push-up member made of rubber material, synthetic resin material, or the like having high elastic force in place of the spring member.

The operating member 101 is a desired rotatable member having a locking arm portion 101a at its tip. 100a, and is rotated by a predetermined angle in either the left or right direction in the horizontal direction, about 60 degrees in this embodiment. The operation member 101 is not construed as being limited to this embodiment, but has a configuration that allows the cam member 99 to be rotated in a predetermined direction by a predetermined angle, and has a configuration that allows the shaft portion 120 to be pressed. Any material can be used and can be appropriately selected within the scope of the present invention. Further, the operating member 101 may be of a manual type, or may be configured to be automatically rotatable via power.

In each of the above-described embodiments, the upper protruding portions 74 and 81A of the core die 69 are abutted (fitted) against the inner surface of the small diameter portion 7b near the large diameter side end portion 3 (fitting). By adopting a core die 69 having an abutting flange (not shown) on the upper portion, the inner surface 8a of the inclined portion 8 and the upper surface 14 of the secondary formed portion 13 (the thin portion 19 in FIG. 17) as shown in FIG. It is also within the scope of the present invention to provide a constant velocity joint boot in which a space 16 is formed between the upper surface of the .

3 large diameter end 5 small diameter end 7 bellows portion 17 thick portion 17a thick portion forming body 18 groove portion 19 thin portion 21a, 21b lip portion

Claims (12)

An annular large-diameter end into which the outer casing of the tripod joint is inserted;
an annular small-diameter end into which the shaft connected to the tripod joint is inserted;
A boot for a constant velocity joint comprising a bellows portion which is integrally provided in a continuous manner between the large diameter side end portion and the small diameter side end portion, and which is formed by repeatedly arranging the large diameter portion and the small diameter portion. There is
The inner peripheral surface of the large-diameter end has a plurality of thick-walled portions formed to fit in a plurality of recesses formed on the outer peripheral surface of the outer housing and protrude in the inner diameter direction of the boot, and the plurality of thick-walled portions. a thin wall portion disposed between the wall portions;
A circumferentially continuous lip portion is formed on the inner peripheral surface of the thick portion and the inner peripheral surface of the thin portion so as to come into contact with the outer peripheral surface of the outer housing including the recess and seal the inner region of the boot. cage,
At least one or more grooves recessed in the boot outer diameter direction from the inner peripheral surface side are formed in the thick portion,
The groove portion is formed along the circumferential direction of the thick portion,
A boot for a constant velocity joint , wherein an outer peripheral surface of the thick portion in contact with the tightening band is flat . 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 across the groove portion in the axial direction of the boot. When viewed from the bottom surface of the large-diameter end, the thick-walled portion has an arc-like shape that rises and slopes from left and right skirts toward the top in the circumferential direction of the large-diameter end. The constant velocity joint boot according to claim 1 or 2, characterized in that: 4. A constant velocity joint as set forth in claim 3, wherein said 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 portion of said thick portion. boots for. The groove portion is formed so that the groove width in the axial direction of the boot is narrower toward the outer diameter direction of the boot than the groove width in the axial direction of the boot on the inner peripheral surface of the thick portion. 5. The constant velocity joint boot according to any one of 4. 6. The constant velocity joint boot according to any one of claims 1 to 5, characterized in that said grooves are provided with ribs that are opposed to each other in the axial direction of the boot and span between inner wall surfaces forming said grooves. . A large-diameter end into which an outer casing of a tripod joint having a plurality of recesses on the outer peripheral surface is inserted, a small-diameter end into which a shaft connected to the tripod joint is inserted, and the large-diameter end A bellows portion formed between the small-diameter end portion and the large-diameter portion and the small-diameter portion are repeatedly arranged, and the outer casing of the tripod joint is provided on the inner peripheral surface of the large-diameter end portion. A method of manufacturing a constant velocity joint boot comprising a plurality of thick portions formed to fit in the recesses of the above and protrude toward the inside diameter of the boot, and a thin portion disposed between the plurality of thick portions. and
A core mold is placed in the large-diameter end of a pre-formed product having a small-diameter end and a large-diameter end communicating with the internal space of the bellows portion, and at least the size of the pre-form is large. A holding mold is arranged on the outer peripheral surface side of the diameter side end,
The upper 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. and a plurality of thick portions and a plurality of thin portions on the large diameter side end between the inner peripheral surface of the large diameter side end portion of the preform and the lower peripheral surface portion of the core mold. A step of forming a secondary molding space for molding a secondary molding portion consisting of a part;
at least a step of injecting a molten material into the secondary molding space to mold a secondary molding portion consisting of a thick portion and a thin portion at the large diameter side end portion of the preform;
The upper protruding portion corresponding to the thick portion forming space constituting the secondary forming space, and the lower protruding portion provided on the lower peripheral surface portion so as to be slidable in the central axis direction of the core mold are arranged in the core. and a step of retracting the mold in the central axis direction to remove it from the thick portion molding space region of the secondary molding space, and separating the core mold and the boot in that state. A method for manufacturing a boot for joints. Either one or both of the upward and downward protrusions of the core mold corresponding to the thick-walled portion molding space constituting the secondary molding space is aligned with the core mold central axis or an axis parallel to the core mold central axis. 8. The method of manufacturing a boot for a constant velocity joint according to claim 7, wherein the cam member is driven to turn around the thick portion region. The downward protruding portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space has a mold surface for forming a groove portion formed in the thick portion. The method for manufacturing a constant velocity joint boot according to claim 7 or 8. A large-diameter end into which an outer casing of a tripod joint having a plurality of recesses on the outer peripheral surface is inserted, a small-diameter end into which a shaft connected to the tripod joint is inserted, and the large-diameter end A bellows portion formed between the small-diameter end portion and the large-diameter portion and the small-diameter portion are repeatedly arranged, and the outer casing of the tripod joint is provided on the inner peripheral surface of the large-diameter end portion. An apparatus for manufacturing a constant velocity joint boot, comprising a plurality of thick-walled portions formed so as to fit in the concave portion of the boot and protrude toward the inside diameter of the boot, and a thin-walled portion disposed between the plurality of thick-walled portions. and
a holding mold for holding an outer surface of a preform having a small-diameter end and a large-diameter end communicating with the internal space of the bellows portion;
a core mold inserted into the large-diameter end of the preform;
For molding a secondary molding portion consisting of a plurality of thick portion molding spaces and a plurality of thin portion molding spaces formed between the inner peripheral surface of the large diameter side end of the preform and the outer peripheral surface of the core mold. and an injection mechanism that injects and fills the molten material into the secondary molding space of
The holding mold has an inner peripheral surface capable of coming into contact with the outer peripheral surface of the large-diameter end,
The core mold has a plurality of thicknesses between an upward protruding portion capable of coming into contact with 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 portion forming a secondary molding space for molding a secondary molding portion composed of a thick 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;
The upper protruding portion and the lower protruding portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space are capable of moving forward toward the thick portion molding space and directed toward the center axis of the core mold. An apparatus for manufacturing a constant velocity joint boot, characterized in that the constant velocity joint boot is retractable. having a cam member that turns around the core mold central axis or an axis parallel to the core mold central axis;
Either one or both of the upward and downward protrusions of the core mold corresponding to the thick portion molding space constituting the secondary molding space are moved toward the thick portion molding space by the cam member. 11. The apparatus for manufacturing a constant velocity joint boot according to claim 10, wherein the boot is forwardable and retractable toward the central axis of the core mold. The downward protruding portion of the core mold corresponding to the thick portion molding space constituting the secondary molding space has a mold surface for forming a groove portion formed in the thick portion. The constant velocity joint boot manufacturing apparatus according to claim 10 or 11.

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