WO2005118257A1

WO2005118257A1 - Method of manufacturing joint boot

Info

Publication number: WO2005118257A1
Application number: PCT/JP2005/004826
Authority: WO
Inventors: Katsushi Saito; Takenori Ohshita; Eiichi Imazu
Original assignee: Toyo Tire & Rubber Co., Ltd.
Priority date: 2004-06-03
Filing date: 2005-03-17
Publication date: 2005-12-15
Also published as: WO2005118258A1

Abstract

A method of accurately manufacturing a joint boot having a large diameter side mounting part in which outer and inner peripheral surfaces are different in shape from each other. A cylindrical parison (15) formed of a first portion (12) forming the product shape of the large diameter side mounting part (2), a second portion (13) forming the product shape of a small diameter side mounting part (4), and a third portion (14) connecting these both portions (12) and (13 ) to each other is injection-molded by using a molding material. After the parison is cooled, only the third portion (14) among the first portion, the second portion, and the third portion is heated, from the radial outer side, to a set temperature by a heater (B), and then the third portion is covered by an outer mold (51), a gas is jetted to the inner peripheral surface of the third portion, and the third portion is pressed against the outer mold to blow-mold a bellows part (5).

Description

Specification

Manufacturing method of joint boots

Technical field

[0001] The present invention relates to a cylindrical large-diameter mounting portion, in which a plurality of convex portions projecting from an inner peripheral portion are fitted into a concave portion of an outer case, and a small-diameter mounting portion, which is mounted on a shaft. The present invention also relates to a method of manufacturing a joint boot for manufacturing a joint boot including a bellows portion connecting these components.

Background art

[0002] As one of constant velocity joints provided on a drive shaft or the like of an automobile, there is a tripod constant velocity joint capable of changing the position in the axial direction and transmitting a rotational force. As shown in FIGS. 12 and 13, this constant velocity joint has three traverses 31 with rollers protruding from the input side (or output side) shaft 3 in the direction perpendicular to the axis, and The outer case 1 is provided at the end of the shaft 40 (or the input side), and three grooves 34 on which the rollers 32 roll are distributed and arranged in the circumferential direction on the inner periphery of the outer case 1. . 33 is a tripod.

[0003] The joint boots described at the beginning are provided for such a constant velocity joint, prevent dust and foreign matter from entering the constant velocity joint side, and hold a dolly around the constant velocity joint. I have. On the outer periphery of the outer case 1, a plurality of concave portions 8, which are concave inward in the radial direction, are provided dispersed in the circumferential direction to reduce the weight of the case. In response to this, a plurality of convex portions 7 projecting radially inward are provided on the inner peripheral portion of the large-diameter-side mounting portion 2 of the joint boot in a dispersed manner in the circumferential direction. On the other hand, the outer peripheral surface of the large-diameter side mounting portion 2 is formed in a circular cross section for fastening by the ring-shaped band 9.

Conventionally, resin joint boots are generally manufactured by molding a small-diameter side mounting portion by injection molding, and then blow-molding the other bellows portion and a large-diameter side mounting portion (for example, Patent Document 1). It is necessary to form the large-diameter-side mounting portion 2 as described above into an irregular shape in which the outer peripheral surface has a perfect circular shape and the inner peripheral surface has an uneven shape having convex portions at a plurality of circumferential positions. Some joint boots cannot be manufactured by such general injection blow molding. This is because the thickness in the circumferential direction is uniform or almost This is because such irregular shapes cannot be formed by blow-molding the large-diameter-side mounting portion in order to achieve uniformity.

[0005] Therefore, in Patent Document 2, a drawer having a cavity for forming a small-diameter-side mounting portion is brought into contact with an outlet gap of a nozzle base, and an outlet gap force injects molten resin into the cavity. After forming the small diameter side mounting part, the drawing device is separated while extruding the molten resin through the outlet gap to form a cylindrical nozzle, and then the top of the nozzle die is replaced with a blow mold. A method has been proposed in which a bellows portion is formed by blow molding, and a large-diameter-side mounting portion is injection-molded with a lower nozzle base to manufacture the above-described tripod-type joint boot.

[0006] However, the method described in Patent Literature 2 uses a method for injection-molding a large-diameter-side mounting portion, which is the most dimensional and requires the highest dimensional accuracy and is difficult to mold. It is used as a flow path for molten resin during injection molding of the cavitica and the small diameter side mounting portion and during extrusion of the parison. For this reason, it is necessary to maintain the temperature at a high temperature when using the cavity portion as a flow path for the molten resin, and to cool it during injection molding, which complicates the temperature control and makes it difficult to ensure high and dimensional accuracy. U, there is a problem.

[0007] Patent Document 3 discloses that a parison having a large-diameter side mounting portion, a small-diameter side mounting portion, and a hollow blow portion corresponding to a bellows portion is injection-molded, and after cooling, the molded parison is injected. It describes a method in which a bellows portion is formed by taking out a mold together with a core mold, attaching the core to a blow mold, and blowing air from the core mold into a blow portion. However, the document does not disclose how to heat Noson during blow molding. If the tip is heated as a whole, it may be deformed due to the heating of the large-diameter mounting part and the small-diameter mounting part formed precisely by injection molding.

Patent Document 1: Japanese Patent Application Laid-Open No. 6-234150

Patent Document 2: Japanese Patent Application Publication No. 2002-361715

Patent Document 3: Japanese Patent Laid-Open No. 2003-222155

Disclosure of the invention

Problems the invention is trying to solve [0008] The present invention has been made in view of the above points, and a joint capable of accurately manufacturing a joint boot having a large-diameter-side mounting portion having an outer peripheral surface and an inner peripheral surface having different shapes. An object of the present invention is to provide a manufacturing method.

Means for solving the problem

[0009] The method of the present invention is characterized in that the cylindrical large-diameter side mounting portion in which a plurality of convex portions projecting from the inner peripheral portion are fitted and fitted to the concave portion of the outer case, and the cylindrical small-diameter mounting portion mounted to the shaft. A method for manufacturing a joint boot comprising a side mounting portion and a bellows portion connecting the side mounting portions, including the following steps.

[0010] (1) A first portion forming the product shape of the large-diameter side mounting portion, a second portion forming the product shape of the small-diameter side mounting portion, and a second portion connecting the first portion and the second portion. Injection molding a cylindrical parison having three parts with a molding material,

(2) after cooling the parison, heating only the third part of the first part, the second part, and the third part from a radially outer side to a set temperature with a heating device;

(3) Then, a step of covering the third portion with an outer mold, injecting gas into the inner peripheral surface of the third portion, and pressing the third portion against the outer mold to form the bellows portion.

[0011] According to this means, the large-diameter side mounting portion and the small-diameter side mounting portion are formed into a final product shape with high dimensional accuracy at the time of injection molding of the parison, and the bellows portion is blown later. Since the final product shape can be formed by molding, accurate molding can be performed even if the large-diameter mounting portion and the small-diameter mounting portion have different shapes.

[0012] According to this means, only the third portion for forming the bellows portion is heated to the set temperature by the heating device, and then the third portion is blow-molded. Variations in the temperature distribution of the three parts can be generated. Here, even if the parison temperature distribution varies when a cylindrical noson is formed in the parison forming process, blow molding without such heating directly results in a lower temperature. The high part swells well and the low temperature part swells, which makes it difficult to uniformly form the bellows wall thickness. On the other hand, according to the present invention, after the injection molding, once cooled, only the third portion is heated from the radially outer side as described above, so that the temperature distribution of the third portion varies. It can be difficult. Therefore, the third part When it is shaped, the third portion can be inflated uniformly, and the bellows can be formed with a uniform thickness.

[0013] In the manufacturing method of the present invention, the first portion is coaxially fitted to the lower fitting portion of the support, and the second portion is coaxial to the upper fitting portion of the support. The parison is supported by the support so that the third portion surrounds the upper and lower intermediate portions of the support concentrically, and the third portion is radially outwardly positioned. Can be heated. After the heating is completed, the parison is covered with the outer mold that can be divided into a plurality of pieces in the circumferential direction while the parison is supported by the support, and gas is injected from an injection port provided in the support. Injection is preferred. Since the gas is injected from the injection port provided in the support in this way, after the heating of the third portion is completed, it is not necessary to newly support the parison with a member dedicated to blow molding having the injection port, and the blow is not performed. The labor required for molding can be reduced.

[0014] In this case, the outer die includes a fitting type portion that coaxially fits a columnar support base on the lower end side of the support, and an outer peripheral surface of the support base is provided on the outer peripheral surface of the support base. A convex ridge extending in the circumferential direction is provided over the entire circumference, and a concave groove into which the convex ridge is fitted is provided on an inner peripheral surface of the fitting die portion, and at least one of upper and lower surfaces of the convex ridge is provided on the support. When the parison is covered with the outer mold, at least one of the upper and lower surfaces of the corresponding concave groove is formed in the same taper surface shape. In addition, it is preferable that the fitting die is closed with respect to a radially outward force with respect to the support base, so that the upper and lower surfaces of the ridge are brought into contact with the upper and lower surfaces of the groove without any gap.

[0015] As described above, the contact surfaces of the ridge and the groove are tapered, and when the outer die is closed with respect to the support, the upper and lower surfaces of the ridge contact the upper and lower surfaces of the groove without any gap. Since the fitting is performed in the state, the support and the outer mold can be positioned in the vertical direction, and the center of the outer mold and the support can be prevented by tilting and the centering between them can be performed. . As a result, the bellows can be blow-molded with high accuracy, and as a result, a joint boot having a large-diameter mounting portion having a plurality of convex portions on the inner peripheral portion can be formed with higher accuracy, so that a small diameter can be obtained. Seal leakage can be avoided not only in the side mounting portion but also in the large-diameter side mounting portion in which sealing performance has conventionally been difficult to secure, and the durability of the joint boot can be improved. [0016] In the manufacturing method of the present invention, the first portion is coaxially fitted to the lower fitting portion of the support, and the second portion is coaxial to the upper fitting portion of the support. The parison is supported on a support so that the third portion is fitted concentrically to the upper and lower middle portions of the support, and the third portion is radially outward. May be heated.

[0017] In this case, since the inner peripheral surface of the third portion is supported by the upper and lower intermediate portions of the support without any gap, the Norrisson shape can be maintained even when the third portion is heated to a high temperature. Therefore, by setting the heating temperature of the third part high, it is possible to blow-mold the third part even at a low blow pressure.

[0018] In the manufacturing method of the present invention, while rotating the support around the axis of the support, a pair of heaters provided opposite to each other with the support interposed therebetween, and the third part is provided. It is preferred to heat the minute. Thus, the third portion is heated radially outward while rotating the support around the axis of the support, so that the third portion can be uniformly heated.

[0019] The manufacturing method of the present invention includes a cylindrical first cover portion surrounding the outer periphery of the first portion, and a cylindrical second cover portion surrounding the outer periphery of the second portion. (1) Cover the parison with a cover member in which a part of the cover and the second cover part are connected by a connecting part and an opening for heat is provided at a position corresponding to the third part, and the third part is covered with the cover. Preferably, heating is performed.

[0020] According to this means, the third portion is heated through the opening of the cover member, and the first portion and the second portion are covered by the cover member, and thus are not easily heated by the heating device. ! / ,. Therefore, deformation of the large-diameter side mounting portion and the small-diameter side mounting portion due to the heating of the first portion and the second portion can be suppressed.

[0021] In the production method of the present invention, a plurality of the supports are arranged on the lower conveyor at intervals in the transport direction, and the supports are interposed between each support and the lower conveyor. A rotation drive mechanism for rotating around the axis is provided, and a plurality of the cover members are suspended from the upper conveyor facing the lower conveyor at an interval in the transport direction. An elevating mechanism for raising and lowering the cover member is provided between the conveyors, and heaters are arranged on both lateral outer sides between the lower conveyor and the upper conveyor. The heating can be performed using a heating device.

In this case, the parison is sequentially supported by the plurality of supports, the cover member is lowered by the elevating mechanism to cover each parison, and the upper conveyor and the lower conveyor are transported and driven. The third part of each parison is sequentially heated by the heater while the body is being rotated by the rotary drive mechanism. As described above, since the third portions of the plurality of parisons can be heated continuously, the efficiency of the heating operation can be increased.

[0023] In the manufacturing method of the present invention, the protruding portion includes an inner wall portion that protrudes in a radially inward curved shape, and an arc-shaped outer wall that forms a part of an outer peripheral surface of the large-diameter-side mounting portion. A radially extending central support wall connecting the inner wall portion and the outer wall portion at the center in the circumferential direction of the inner wall portion, and connecting the inner wall portion and the outer wall portion at both sides of the central support wall. Left and right side support walls may be provided, and the side support walls may be inclined so that the outer side is closer to the central support wall.

[0024] Thereby, the convex portion is provided with a hollow portion as a lightening hole between the central support wall and the side support wall and on both sides of the side support wall. Therefore, the molding material can be cooled faster than in the case where the convex portion is formed of a solid thick portion, and the occurrence of sink caused by shrinkage after molding can be prevented.

[0025] Further, since the side support walls are provided so as to be inclined outwardly closer to the center support wall, the following effects are obtained. In other words, when the side support wall is arranged parallel to the center support wall, the thickness of the lightening hole outside the side support wall becomes smaller, which makes it difficult to remove the core. By inclining toward the center support wall, the cross-sectional area of the lightening hole outside the side support wall can be secured, and the core can be easily removed.

[0026] Furthermore, by inclining the side support wall as described above, the side support wall supporting the outer side surface of the inner wall portion can be joined to the inner wall portion at an angle close to perpendicular. Therefore, when the large-diameter-side mounting portion is fastened and fixed, the surface pressure exerted on the outer case by the inner wall portion can be made uniform in the circumferential direction, and the sealing performance at the convex portion can be improved. From this point of view, it is preferable that the side support wall is connected substantially perpendicularly to the inner wall portion, and more particularly, the angle of the side support wall to the inner wall portion is 70 ° — 110 °. It is preferable that it is within the range. Further, in this case, the side support wall is coupled to the inner wall portion at an intermediate position between a connection portion of the inner wall portion to the central support wall and a root portion to the outer wall portion, and It is preferable that The weakest and weakest portions on both sides of the connecting portion between the inner wall portion and the central support wall are located at an intermediate point between the connecting portion and the base portion to the outer wall portion. If the wall is reinforced so as to be supported by the side support walls, it is more effective for the inner wall to uniform the surface pressure on the outer case.

The invention's effect

[0028] As described above, according to the present invention, a joint boot having a large-diameter-side mounting portion in which the outer peripheral surface and the inner peripheral surface have different shapes can be manufactured with high accuracy, and the bellows portion is formed. Since only the third portion is heated to the set temperature by the heating device and then the third portion is blow-molded, the thickness of the bellows portion can be formed uniformly.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIGS. 12 and 13 show a tripod type constant velocity joint of an automobile, and FIGS. 6 and 7 show a joint boot made of a thermoplastic elastomer resin for the constant velocity joint.

[0030] In the constant velocity joint, three traverses 31 with rollers are provided on the input side shaft 3 so as to protrude in a direction perpendicular to the axis, and an outer case 1 is provided at an end of the output side shaft 40. On the inner peripheral portion of the outer case 1, three grooves 34 on which the roller 32 rolls are distributed and arranged in the circumferential direction. 33 is the tripod.

[0031] The joint boot includes a cylindrical large-diameter side mounting portion 2 that is externally fitted to the outer case 1, a cylindrical small-diameter side mounting portion 4 that is mounted on the shaft 3, and a bellows portion 5 that connects these. The outer peripheral surface 2a of the large-diameter mounting portion 2 is formed in a circular cross-section, and the three protruding radially inward portions are formed on the inner peripheral portion 2b of the large-diameter mounting portion 2. Protrusions 7 are evenly distributed in the circumferential direction at every 120 degrees, and three protrusions 7 can be separately fitted to three recesses 8 formed on the outer periphery of the outer case 1. It is.

The convex portion 7 includes an inner wall portion 71 that protrudes inward in the radial direction, and an arc-shaped outer wall portion 72 that forms a part of the outer peripheral surface 2a of the large-diameter-side mounting portion 2. A central support wall 73 that connects the two wall portions 71 and 72 at the center in the circumferential direction is provided in a hollow portion between the inner wall portion 71 and the outer wall portion 72. And a pair of left and right side support walls 74, 74 connecting the two wall portions 71, 72 on both left and right sides of the vehicle.

The outer wall portion 72 is an arc-shaped wall portion having a substantially constant thickness in the circumferential direction, and is integrated with the arc-shaped wall portion 76 interposed between the projections 7 to form a single cylindrical body. It is configured to make! The inner wall portion 71 is a wall portion having a substantially constant thickness and formed in a curved shape so as to project radially inward from the inner peripheral surface of the cylindrical body.

As shown in FIG. 8, the central support wall 73 is a wall portion extending in the radial direction for supporting the inner side wall portion 71 with respect to the outer side wall portion 72, and has a height at which the inner side wall portion 71 projects inward. It is provided at the center in the circumferential direction where the maximum height is obtained.

[0035] The side support wall 74 is a wall that supports the inner wall 71 to the outer wall 72, and is parallel to the central support wall 73 provided radially from the center of the large-diameter mounting portion 2. It is formed to be inclined so that the outermost part becomes closer to the central support wall 73. More specifically, the side support wall 74 is formed so that the inner wall 71 is supported by the center support wall 73 and the side support walls 74, 74 at equal intervals in the circumferential direction. The inner wall portion 71 is supported at an intermediate position between the base portion 71a and the connecting portion 71b between the central support wall, that is, the inner wall portion 71 is connected at the intermediate position. Further, the connecting portion is provided so as to intersect approximately perpendicularly with the inner wall portion 71, so as to go outward from the connecting portion toward the center, that is, to be inclined so as to approach the central support wall 73. Te ru.

Here, the connection angle Θ of the side support wall 74 with respect to the inner wall portion 71 is preferably substantially vertical. More specifically, the connection angle is 0 ° 70 ° — 110 ° (ie, 90 ° ± 20 °). The angle is more preferably in the range of 80 ° to 100 °. This coupling angle Θ is an angle formed between the center lines Nl, N2 of the side support walls 74 and the tangent Q on the inner peripheral surface of the inner wall portion 71 intersecting the center lines Nl, N2.

In this embodiment, the center line N1 in the thickness direction of one side support wall 74 and the center line N2 in the thickness direction of the other side support wall 74 are the center line of the center support wall 73 in the thickness direction. It intersects L at one point of intersection R, and this intersection R is located radially outside the outer peripheral surface 2a of the large-diameter-side mounting portion 2. As a result, the side support walls 74, 74 are not connected to the outer wall 72 at the connecting portion of the center support wall 73 to the outer wall 72, It is joined to the outer wall 72 at a position circumferentially spaced from the joint. As a result, the thickness of the outer wall 72 at the center thereof can be reduced, so that the occurrence of sink after molding can be more effectively prevented.

[0038] With such a configuration, the convex portion 7 is provided with a lightening hole 75 that is a plurality of hollow portions arranged in the circumferential direction. Specifically, the convex portion 7 is formed with two pairs of bottomed lightening holes 75a, 75b, 75c, 75d that are open to the end face of the large-diameter mounting portion 2 and that are symmetrical with respect to the circumferential center line L. The depth of each of the lightening holes 75a-75d is set to be the same. The inner pair of lightening holes 75b and 75c partitioned by the central support wall 73 has a trapezoidal cross section in which the outer peripheral surface 2a side of the large-diameter mounting portion 2 is narrowed. The lightening holes 75a and 75d have a triangular cross section having a vertex angle directed inward in the radial direction.

As shown in FIG. 6, the outer peripheral surface 2a of the large-diameter mounting portion 2 has a fixing member extending in the circumferential direction for receiving a ring-shaped band 9 (see FIG. 12) as a fastening member. A recess 60 is provided. In addition, two sealing ribs 61 extending in the circumferential direction are provided on the inner peripheral surface of the large diameter side mounting portion 2. Similarly, in the small-diameter side mounting portion 4, a fixing recess 62 extending in the circumferential direction for receiving the ring-shaped band 9 as a fastening member is provided on the outer peripheral surface, and the inner peripheral surface is provided on the inner peripheral surface. Is provided with two sealing ribs 63 extending in the circumferential direction.

[0040] The joint boot is manufactured through the following Norrison molding step, heating step, and blow molding step.

[Parison molding step]

As shown in FIG. 1, the molding material is discharged from a nozzle 11 of the parison molding apparatus A, and a first portion 12 corresponding to the large-diameter mounting portion 2, a second portion 13 corresponding to the small-diameter mounting portion 4, A cylindrical parison 15 including a third portion 14 corresponding to the bellows portion 5 is injection-molded.

[0042] The injection molding die 80 is an injection outer die 81 that can be divided into a plurality of parts in the circumferential direction for molding the outer peripheral side of the parison 15, and is mounted inside to form the inner peripheral side of the parison 15. A core 83 is provided between the outer die 81 and the core 82. The outer mold 81 for injection is configured to be dividable into two right and left parts in this embodiment. The core mold 82 is provided so as to form the second portion 13 at the top portion 82a, and covers above the top portion 82a. A gate hole 84 communicating with the nozzle 11 is provided on the upper surface of the outer die 81.

The first portion 12 is molded as the large-diameter mounting portion 2 in the cavity 83, that is, is injection-molded into the final product shape of the large-diameter mounting portion 2. Therefore, the first portion 12 is formed into a shape having an outer peripheral surface having a circular cross section and having a plurality of the convex portions 7 on the inner peripheral portion. 75d is molded. The fixing recess 60 is formed on the outer peripheral surface, and two ribs 61 are formed on the inner peripheral surface.

The second portion 13 is molded as the small-diameter side mounting portion 4 in the cavity 83, that is, is injection-molded into the final product shape of the small-diameter side mounting portion 4. At this time, the second portion 13 is formed into a cylindrical shape having a smaller diameter than the first portion 12, and the fixing recess 62 is formed on the outer peripheral surface, and the two ribs 63 are formed on the inner peripheral surface. . Further, the opening surface at the upper end of the second portion 13 is closed after the injection molding, and the closed portion 13a is cut off after the blow molding in the present embodiment.

On the other hand, the third part 14 is a parison part interposed between the first part 12 and the second part 13 which does not have a bellows shape corresponding to the final product shape, and connects them. It is injection molded into a tapered cylinder. That is, the third portion 14 is formed in a tapered shape in which the diameter is gradually reduced from the large-diameter mounting portion 2 to the small-diameter mounting portion 4.

[0046] The parison 15 thus injection-molded is taken out of the injection molding die 80, and thus also removed from the core die 82, and cooled (natural cooling) at room temperature.

[Heating Step]

Next, as shown in FIG. 2, the cooled parison 15 heats only the third part 14 of the first part 12, the second part 13, and the third part 14 by the heating device B (for example, at 160 ° C.). — 200 ° C). The heating device B is configured as follows so that a plurality of parisons 15 can be heated continuously.

As shown in FIG. 9 and FIG. 11, a plurality of stepped columnar supports 16 for the parison 15 are arranged on the lower conveyor 17 at regular intervals in the transport direction, and A rotation drive mechanism M for rotating the support 16 around the axis O of the support 16 is provided between each support 16 and the lower conveyor 17.

[0049] The support 16 includes a columnar support base 19 at the lower end and a first portion 12 having a smaller diameter than the support base. A lower fitting portion 20 for external fitting concentrically, a tapered pillar-shaped upper and lower intermediate portion 21 concentrically surrounded by the third portion 14, and a second portion 13 provided at the upper end of the upper and lower intermediate portion 21; And an upper fitting portion 22 for externally fitting the same. The upper and lower middle portions 21 are formed so that the third portion 14 is fitted externally concentrically, that is, such that the inner peripheral surface of the third portion 14 is abutted against the upper and lower middle portions 21 without any gap. It has an outer shape that matches the inner peripheral surface of 14.

[0050] Then, a plurality of cylindrical cover members 24 are suspended from the upper conveyor 23 opposed to the lower conveyor 17 at fixed intervals in the conveyance direction, and are supported. A cylinder 25 (equivalent to an elevating mechanism) that raises and lowers the cover member 24 is provided between the lower conveyor 17 and the upper conveyor 23. It is arranged.

[0051] The cover member 24 is a member that covers the parison 15 held on the support body 16 and limits the location where the heat rays from the heater 45 are irradiated. A large-diameter cylindrical first cover portion 41 that surrounds the first portion 41 and a small-diameter cylindrical second cover portion 42 that surrounds the outer periphery of the second portion 13 with a gap therebetween are provided. The two cover portions 42 are connected by a connection portion 43, and a heating opening 44 is provided at a location corresponding to the third portion 14. The connecting portion 43 is a narrow plate-like support member that connects two radially opposed portions of the first cover portion 41 and the second cover portion 42, and by connecting with such a connecting portion 43, Between the first cover part 41 and the second cover part 42, a pair of left and right openings 44, 44 respectively facing a pair of heaters 45, 45 provided on both lateral outer sides of the conveyors 17, 23 are provided. Is provided.

[0052] The upper end of the first cover portion 41, that is, the lower end 44a of the opening portion 44 is set at the boundary between the first portion 12 and the third portion 14, and the lower end of the second cover portion 42, that is, the upper end 44b of the opening portion 44b. Is set at the boundary between the second part 13 and the third part 14. Accordingly, the cover member 24 is configured such that the first portion 12 and the second portion 13 are not irradiated with the heat rays from the heater 45, that is, far infrared rays, and thus are not heated. Covers the Norrison 15 so that far infrared rays from the heater 45 are radiated over the entire height direction through the opening 44.

[0053] The cover member 24 is not limited to such a form. For example, the cover member 24 is concentric with the entire Norrisson 15 in the height direction, that is, from the first portion 12 to the second portion 13. Condition A pair of left and right heating openings may be formed in the shape of a window at a location that covers the third portion 14 in this case. In this case, the connecting portion between the openings is the above-described connecting portion. .

[0054] With the above structure,

(1) With respect to the support 16 provided on the lower conveyor 17, the first part 12 is fitted concentrically to the lower fitting part 20 of the support 16, and the second part 13 is placed above the support 16. The parison 15 is supported by the support 16 such that the third portion 14 is fitted externally concentrically to the fitting portion 22 and the third portion 14 is fitted concentrically to the upper and lower intermediate portions 21 of the support 16 (see FIG. 9).

(2) The cover member 24 suspended and supported by the upper conveyor 23 is moved downward by extending and driving the cylinder 25 to cover the entire parison 15 supported by the support 16 (see FIG. 2).

(3) The upper conveyor 23 and the lower conveyor 17 are transported and driven, and the third part 14 is moved between the lower conveyor 17 and the upper conveyor 23 while rotating the support 16 around its axis O. Heat with heater 45 on the outside side. In this case, the Norison 15 rotates together with the support 16, but the cover member 24 does not rotate and the third portion 14 is heated over the entire circumference via the opening 44 facing the heater 45 (see FIGS. 2 and 10). , 11).

In this way, the plurality of parisons 15 are sequentially supported on the plurality of supports 16, and the third portion 14 of each parison 15 is heated. This heats the third part 14 of the plurality of parisons 15 continuously.

[Blow molding step]

After the heating of the third part 14 is completed, as shown in FIG. 3, while the parison 15 is supported on the support 16, the mold surface is covered with an outer mold 51 having a bellows shape, and the injection port provided on the support 16 is provided. Gas is injected from 52 to the inner peripheral surface of the third part 14, and the third part 14 is pressed against the outer mold 51 to form the bellows part 5.

The outer mold 51 is formed so as to be able to be divided into a plurality in the circumferential direction, and in this embodiment, it can be divided into two right and left parts. The outer mold 51 is formed by laminating a plurality of plate-like molds 54 in the vertical direction such that the mating surface 53 comes to the top of each crest of the bellows portion 5 to be molded. Occasionally, air in the mold can be exhausted through the mold mating surface 53, so that each peak of the bellows portion 5 can be reliably pressed against the mold surface. Also, the outer mold 51 is provided with a cooling pipe 55 as shown in FIGS. It is supposed to be. The cooling pipe 55 is configured by providing an arc-shaped groove extending along the outer periphery of the Norrison 15 in the plate-shaped mold 54 on each mold matching surface 53.

The support 16 that supports the parison 15 is a core that is mounted in the outer die 51 during blow molding, and includes a gas passage 56 that extends vertically along the axis O. . The gas passage 56 is connected to an injection port 52 provided on the outer peripheral portion of the lower surface of the upper fitting portion 22 of the support 16 and is switchably connected to a pressure increasing tank and an exhaust tank (not shown). It is used to send the gas from the booster tank to the injection port 52 and exhaust the gas in the mold by the action of the exhaust tank.

When the outer mold 51 is closed with respect to the strong support 16, the upper end opening surface of the second portion 13 is closed by the closing portion 13 a, so that the gas seal is formed at the upper end of the Norrison 15. Is unnecessary, and only the first portion 12 at the lower end need be sealed. For example, when the Norison 15 is attached to the support 16, the inner peripheral surface 12 a of the first portion 12 is fitted in close contact with the outer peripheral surface of the lower fitting portion 20 when the Norrisson 15 is attached to the support 16. That can be done.

[0062] After blow-molding the bellows portion 5 in this manner, by cutting off the closed portion 13a of the upper end opening surface of the second portion 13, a joint boot is obtained.

[0063] In the above-described manufacturing method, in the present embodiment, a professional mold including the outer mold 51 and the support 16 is further configured as follows. That is, as shown in FIG. 3, the outer die 51 includes a fitting die portion 57 for externally fitting the support base 19 of the support 16 concentrically, and the outer die 51 and the support 16 are connected to each other. When the mold is closed, the fitting mold 57 holds the outer periphery of the support base 19. A circumferentially extending ridge 58 is provided on the outer peripheral surface of the support base portion 19 at the center in the vertical direction over the entire circumference, and the inner peripheral surface of the fitting mold portion 57 has A concave groove 59 into which 58 fits is provided over the entire circumference.

As shown in FIG. 5 (a), the ridge 58 has its upper surface 58a and lower surface 58b both inclined with respect to a direction P perpendicular to the axis of the support 16 (a direction perpendicular to the axis O). It is formed in a tapered shape. Specifically, the ridge 58 has a trapezoidal cross-section that is gradually narrowed toward the top on the radially outward side, and the upper and lower inclined surfaces 58a and 58b are formed symmetrically. In addition, the upper surface 59a and the lower surface 59b of the concave groove 59 are also formed in the same tapered surface shape as the ridge 58, and the inclination angle of the upper and lower surfaces 59a, 59b is determined by the corresponding upper and lower surfaces 58a, 58b Is set to be the same as the angle. Further, as shown in FIG. 5B, the concave groove 59 is formed deeper than the protruding height of the ridge 58 so that a gap 91 is secured at the tip when the ridge 58 is fitted. Have been.

When the outer mold 51 and the support 16 are closed so as to cover the Norrisson 15 with the outer mold 51, the fitting mold 57 moves the support base 19 radially outward. The mold is closed to enclose the force. At this time, when the convex streak 58 of the support base 19 is fitted into the concave groove 59 of the mating mold part 57, the contact portion between the convex streak 58 and the concave groove 59 has a tapered surface as described above. The upper and lower surfaces 59a, 59b of the groove 59 are fitted in a state where the upper and lower surfaces 58a, 58b of the ridge 58 abut without any gap. Therefore, the support 16 and the outer mold 51 can be positioned in the vertical direction, and the axis of the outer mold 51 and the support 16 can be prevented from tilting and centered between them. Therefore, the bellows portion 5 can be blow-molded with high accuracy. Further, by providing the fitting mechanism with such irregularities, the fitting length in the axial dimension between the support base 19 and the fitting die 57 is short, and the centering can be performed.

In the present embodiment, a force in which both the upper and lower surfaces of the ridge 58 and the concave groove 59 are tapered is used. Only one of the upper and lower surfaces is formed into a tapered surface, and the other surface is formed in a direction perpendicular to the axis. In this case, the protrusions 58 may be formed in a trapezoidal shape in which the width is gradually narrowed toward the top on the radially outward side. The effect of the present invention is achieved.

[0067] Further, the fitting mechanism based on the strong concave and convex can be similarly provided in the injection molding die 80 as shown in FIG. That is, as shown in the drawing, a ridge 85 is provided on the outer peripheral surface on the lower end side of the core mold 82 over the entire circumference, and the ridge 85 is formed on the inner peripheral surface of the corresponding outer mold 81 for injection. A concave groove 86 is provided for fitting. The specific shapes of the ridges 85 and the concave grooves 86 are the same as those of the above-described ridges 58 and the concave grooves 59 of the blow molding die, and therefore description thereof is omitted. In the case of the injection molding die 80, as shown in FIG. 1, since the upper end portion 82a of the core die 82 is not supported by the injection outer die 81, the core die 82 may be inclined by the injection pressure of the molding material. However, by ensuring the centering by fitting in such unevenness, the inclination of the core mold 82 can be prevented, and the Norrison 15 can be molded with high accuracy. Eliminates the required molding error in the large-diameter mounting part 2 and Performance can be improved.

In the present embodiment described above, the large-diameter-side mounting portion 2 and the small-diameter-side mounting portion 4 are formed into a final product shape with high dimensional accuracy by injection molding during parison molding, and the bellows portion is formed. 5 is formed into the final product shape by subsequent blow molding, so it is possible to accurately mold not only the small-diameter mounting part 4 but also the large-diameter mounting part 2 whose inner peripheral part is significantly different from the outer peripheral part. can do.

[0069] Further, only the third portion 14 for forming the bellows portion 5 is heated to the set temperature by the heating device B, and thereafter, the third portion 14 is blow-molded. Therefore, the third portion 14 can be uniformly expanded when blow-molded, so that the thickness of the bellows portion 5 can be formed uniformly.

[0070] Further, by providing the above-mentioned specific lightening holes 75a-75d in the convex portion 7, the large-diameter mounting portion 2 can be formed into a desired shape with high precision, and the large-diameter mounting portion 2 can be immediately attached to the outer case. Can improve the adhesion. Further, since the side support wall 74 is inclined so as to be closer to the center support wall 73 outward, the cross-sectional area of the outer lightening holes 75a and 75d is ensured, and the core mold 82 is removed. Type can be ensured. Further, since the side support wall 74 can be joined to the inner wall portion 71 at an angle almost perpendicular to the inner wall portion 71, when the large diameter side mounting portion 2 is tightened and fixed, the surface that the inner wall portion 71 exerts on the outer case is reduced. The pressure can be made uniform in the circumferential direction, and the sealing performance at the projection 7 can be improved.

[0071] Furthermore, by applying the above-described specific heating device B and heating method, it is possible to reduce the variation in the temperature distribution of the third portion 14 and to increase the efficiency of the heating operation. As well as the labor required for subsequent blow molding

Further, in the case of the heating device B, since the individual cover member 24 is placed on the Norrison 15 conveyed on the conveyor 17, one cover member can be used according to the product of the joint boot. By replacing it, it is possible to easily handle various types of joint boots. Instead of such an individual cover member 24, a wall-shaped cover member extending along the conveyor 17 facing the heater 45 may be provided to heat only the third portion 14. Industrial applicability The present invention can be suitably used for manufacturing a joint boot used for a constant velocity joint of an automobile or the like.

Brief Description of Drawings

[FIG. 1] Diagram showing a parison molding process

[Figure 2] Diagram showing the heating process

[Figure 3] Diagram showing the blow molding process

[Figure 4] Top view of blow mold

FIG. 5 is an enlarged sectional view of a main part of a blow molding die, wherein (a) shows a state before the mold is closed and (b) shows a state after the mold is closed.

[Figure 6] Partially cutaway sectional view showing joint boots

FIG. 7 is a diagram showing a large-diameter side mounting portion of a joint boot.

FIG. 8 is a cross-sectional view of a convex portion in a large-diameter side mounting portion of the joint boot

FIG. 9 is a view showing a heating device and a heating process.

FIG. 10 is a plan view showing a lower conveyor and the like with a parison attached.

[Figure 11] Side view of heating device during heating

FIG. 12 is a longitudinal sectional view showing a constant velocity joint and a joint boot.

[Figure 13] Diagram showing constant velocity joints

Explanation of symbols

[0075] 1 ... outer case, 2 ... large diameter side mounting part, 3 ... shaft, 4 ... small diameter side mounting part, 5 ... bellows part, 7 ... convex part, 8 ... concave part, 12 ... first part, 13 ... · Second part, 14… Third part, 15… Parison, 16 ··· Supporter, 17… Lower conveyor, 19 ··· Support base, 20… Lower fitting part, 21 ··· Up and down Middle part, 22 Upper fitting part, 23 Upper conveyor, 24 Cover member, 25 Elevating mechanism, 41 First cover part, 42 Second cover part, 43 · Connecting part, 44 ··· Opening part, 45 ··· Heater, 51 ···· Outer type, 52 ··· Injection port, 57 ··· Mating type part, 58 ··· Protrusion, 58a… Upper surface of the ridge, 58b: Lower surface of the ridge, 59 ·· Recessed groove, 59a… Upper surface of the groove, 59b… Lower surface of the groove, 71 ··· Inner wall, 71a- Root to outer wall, 71 ··· Connection between inner wall and center support wall, 72 ··· Outer wall, 73 ··· Central support wall, 74 ··· Side support Wall, 75a- 75d ... lightening holes, B ... heater, O ... axis of the support, M ... rotary drive mechanism

Claims

The scope of the claims

[1] A cylindrical large-diameter-side mounting portion in which a plurality of convex portions protruding from the inner peripheral portion are fitted to the concave portion of the outer case and a cylindrical small-diameter-side mounting portion to be mounted on a shaft. A joint boot consisting of a bellows portion connecting the

A tube comprising: a first portion forming the product shape of the large-diameter mounting portion; a second portion forming the product shape of the small-diameter mounting portion; and a third portion connecting the first portion and the second portion. Injection molding of Norrison

After cooling the parison, only the third part of the first part, the second part, and the third part is heated from a radially outer side to a set temperature by a heating device,

Thereafter, a method of manufacturing a joint boot in which the third portion is covered with an outer mold, gas is injected into the inner peripheral surface of the third portion, and the third portion is pressed against the outer mold to form the bellows portion. .

[2] The first portion is coaxially fitted to the lower fitting portion of the support, and the second portion is coaxially fitted to the upper fitting portion of the support. The parison is supported by the support so that the upper and lower intermediate portions of the support are concentrically surrounded, and the third part is heated from the radially outer side,

After the heating is completed, the parison is covered with the outer mold, which can be divided into a plurality of pieces in the circumferential direction, while the parison is supported by the support, and an injection port force provided on the support is provided. Which injects

The outer die includes a fitting die portion for externally concentrically fitting a columnar support base on the lower end side of the support, and a circumferentially extending ridge is provided on an outer peripheral surface of the support base. A groove is provided on the inner peripheral surface of the fitting die portion, and at least one of the upper and lower surfaces of the ridge is perpendicular to the axis of the support. And at least one of the upper and lower surfaces of the corresponding concave groove is formed in a similar tapered surface shape, and

When covering the parison with the outer mold, the fitting mold portion is closed from the radially outward side with respect to the support base portion, and the upper and lower surfaces of the convex strip are formed between the upper and lower surfaces of the concave groove. 2. The method for manufacturing a joint boot according to claim 1, wherein the joint boots are contacted without any gap.

[3] The first portion is coaxially fitted to the lower fitting portion of the support, and the second portion is coaxially fitted to the upper fitting portion of the support. The parison is supported by the support so that the outer periphery is concentrically fitted to the upper and lower middle portions of the support, and the third portion is heated in a radially outward direction. 2. The method for manufacturing the joint boot described in 2.

[4] The third portion is heated by a pair of heaters provided on both sides of the support while facing the support while rotating the support about the axis of the support. 3. The method of manufacturing the joint boot according to 3.

[5] A cylindrical first cover portion surrounding the outer periphery of the first portion, and a cylindrical second cover portion surrounding the outer periphery of the second portion, the first cover portion and the second cover being provided. 3. The third portion is heated by covering a parison member, which is provided with a heating opening at a portion corresponding to the third portion by connecting the portions by a connecting portion, to the parison. 5. The method for manufacturing a joint boot according to any one of 4.

[6] A rotation drive mechanism for arranging a plurality of the supports on the lower conveyor at intervals in the transport direction and rotating the supports around the axis between each support and the lower conveyor. And a lifting mechanism for suspending and supporting a plurality of the cover members on the upper conveyor facing the lower conveyor at intervals in the transport direction and raising and lowering the cover members between each cover member and the upper conveyor. A heater is arranged on both lateral outer sides between the lower conveyor and the upper conveyor,

The parison is sequentially supported by the plurality of supports, the cover member is lowered by the elevating mechanism to cover each parison, the upper conveyor and the lower conveyor are transported and driven, and each support is rotated by the rotation drive mechanism. The method for manufacturing a joint boot according to claim 5, wherein the third portion of each parison is sequentially heated by the heater while rotating the parison.

[7] The large-diameter-side mounting portion of the convex portion includes an inner wall portion that protrudes radially inwardly in a curved shape, and an arc-shaped outer wall portion that forms a part of an outer peripheral surface of the large-diameter-side mounting portion. A radially extending central support wall connecting the inner wall portion and the outer wall portion at the center in the circumferential direction, and left and right side supports connecting the inner wall portion and the outer wall portion on both sides of the central support wall. With the wall 17. The method for manufacturing a joint boot according to claim 16, wherein the side support wall is inclined so that the side support wall is closer to the central support wall toward the outside.

10. The side wall is coupled to the inner side wall at a position intermediate between a connection part of the inner side wall part to the central support wall and a root part to the outer side wall part. A method for manufacturing the joint boot described.