JPWO2006033158A1 - Manufacturing method of resin joint boots - Google Patents

Abstract

By reducing the number of processes, eliminating unnecessary labor, and shortening the cooling time, the molding cycle is increased, and a resin joint boot having a large-diameter mouth portion with high dimensional accuracy is efficiently manufactured. Therefore, the molten resin enters the cavity (11) of the drawing device (9) from the outlet gap (6) of the annular orifice nozzle (7) through the conical annular passage (14) formed by the auxiliary nozzle base (8). By injecting (5), the bellows-shaped hollow part (2) is first injection-molded with a large-diameter mouth part (3), and then the drawing device is moved to draw out the tubular parison (15). Subsequently, the bellows-shaped hollow portion and the small-diameter mouth portion (4) at the other end are integrally blow-molded using the blow-molding split mold (10).

Description

  The present invention is mainly used for a triport type constant velocity joint boot of an automobile, etc., and a resin joint which is integrally formed of a thermoplastic resin including a bellows-like hollow portion and connection ports at both ends thereof. The present invention relates to a boot manufacturing method and a manufacturing apparatus.

  This type of resin joint boot has a bellows shape to prevent dust and water from entering the triport type constant velocity joint of an automobile and to keep the enclosed grease from leaking out. One end of the hollow part has a large-diameter mouth part that is fastened and fixed to the outer case provided at the end part on the driven shaft side via a band or the like, and the band on the transmission shaft on the other end side of the bellows-like hollow part. And a small-diameter mouth portion that is fastened and fixed via, for example. As a means for producing such a joint joint boot made of resin, generally, after manufacturing a small-diameter mouth part by injection molding, a manufacturing method for forming other bellows-like hollow parts and large-diameter mouth parts by blow molding and therefore Is known (see, for example, Patent Document 1).

In addition, a small-diameter mouth forming cavity is formed on the outlet gap of the annular orifice nozzle formed by the nozzle core and the nozzle base that concentrically surrounds the core and forms an outlet gap for extruding the molten resin between the core. After forming a small-diameter opening by injecting a thermoplastic molten resin into the cavity of the drawing device from the outlet gap by bringing the drawing device into contact with the drawing device, the drawing device is formed in an annular shape while further extruding the molten resin through the outlet gap A tubular parison is drawn out by being moved away from the orifice nozzle, and then the bellows-like hollow is formed by blow-molding the tubular parison by replacing the uppermost part of the nozzle base forming the outlet gap with a blow molding split mold. The cavity for forming a large-diameter mouth part formed in the lower part of the nozzle base Te by injection molding a large 径口 portion, a manufacturing method for continuously forming a predetermined resin joint boot and the manufacturing apparatus therefor conventionally known (e.g., see Patent Document 2).
: Japanese Unexamined Patent Publication No. 6-234150 : Japanese Patent Laid-Open No. 2002-361715

  In the case of the conventional general manufacturing means disclosed in Patent Document 1, since only the small-diameter mouth portion at one end is injection-molded, the small-diameter having a different diameter whose thickness changes arbitrarily in the circumferential direction. Although it is possible to easily and accurately form the mouth portion, the other bellows-like hollow portion and the large-diameter mouth portion are blow-molded. All the diameter openings have uniform or almost uniform wall thickness in the circumferential direction, and can only produce general constant velocity joint boots for automobiles. Thus, it is desirable that the large-diameter mouth portion has a different diameter shape in which the outer peripheral surface is a perfect circle and the inner peripheral surface is an uneven shape having protrusions radially inward at a plurality of locations in the circumferential direction. Resin joint boots cannot be manufactured There was a problem.

  Further, in the case of the conventional manufacturing means disclosed in Patent Document 2, since both the small-diameter mouth portion and the large-diameter mouth portion are injection-molded, both of the both-end mouth portions are easily formed into different diameter shapes. It is possible to manufacture a triport type constant velocity joint boot. However, because it is the largest in size, it is injection-molded at a stage close to the final stage, which has the highest dimensional accuracy requirements and is difficult to mold. In order to make it uniform and stable, it is necessary to take sufficient time for cooling after the injection molding, and from these, there is a problem that there is a limit to the increase in the molding cycle and, consequently, the production efficiency. . In addition, since the cavity for molding the large-diameter mouth portion is used as a molten resin flow path at the time of injection molding and parison formation of the small-diameter mouth section, the cavity portion is used as a molten resin flow path. Sometimes, it is necessary to cool the large-diameter mouth portion after injection molding while maintaining a high temperature, and there is a problem that temperature control is complicated and it is difficult to ensure high dimensional accuracy.

  The present invention has been made in view of the above circumstances, and is made of a resin that can efficiently manufacture a resin joint boot having a large-diameter mouth portion with a very high dimensional accuracy by increasing the molding cycle by shortening the cooling time. It aims at providing the manufacturing method and manufacturing apparatus of a joint boot.

  In order to achieve the above object, a method for manufacturing a resin joint boot according to the present invention includes a thermoplastic resin having a joint boot having a large-diameter mouth portion at one end of a bellows-like hollow portion and a small-diameter mouth portion at the other end. A method of manufacturing a resin joint boot integrally molded by the method of the present invention, wherein the annular orifice nozzle has a diameter corresponding to a small-diameter mouth portion of the joint boot and has an outlet gap that can extrude a thermoplastic molten resin. A conical annular molten resin passage in which the cavity of the drawing device having the large-diameter opening forming cavity of the joint boot is disposed between the outlet gap and the outlet gap from the outlet gap toward the drawing device cavity. In this state, the conical ring is formed from the outlet gap of the annular orifice nozzle. A step of forming a large-diameter mouth portion of the joint boot by injecting the molten resin into the cavity of the drawing device through the molten resin passage of the shape, and moving and retracting the auxiliary nozzle base to the side, In the state where the diameter port portion is kept cold, the step of drawing the tubular parison by moving the drawing device away from the annular orifice nozzle while extruding the molten resin through the outlet gap of the annular orifice nozzle, and the drawing device is a circular shape When the blow-off mold is moved away from the annular orifice nozzle by a predetermined stroke, the blow mold split mold is moved closer to the tubular parison side and clamped, and compressed gas is blown into the tubular parison to blow the parison. The bellows-shaped hollow part of the joint boot by blow molding into a shape along the inner surface shape of the molding split mold, and A step of integrally molding the diameter opening portion, moving the blow molding split mold to the side, opening the mold, and opening the split mold that constitutes the cavity for forming the large diameter opening portion; And a step of taking out the part.

  The resin joint boot manufacturing apparatus according to the present invention is a resin-made product in which a joint boot having a large-diameter mouth portion at one end of a bellows-like hollow portion and a small-diameter mouth portion at the other end is integrally formed of a thermoplastic resin. An annular orifice nozzle having a diameter corresponding to a small-diameter opening portion of the joint boot and having an outlet gap capable of extruding a thermoplastic molten resin, and the annular orifice nozzle It is possible to switch between the state of being placed in contact with the outlet gap of the nozzle and the state of being moved and retracted to the side of the annular orifice nozzle. An auxiliary nozzle base that forms a conical annular molten resin passage having a gradually increasing diameter, and a conical annular molten resin passage of the auxiliary nozzle base. It has a cavity for forming a large-diameter opening that can be connected to the outlet gap of the annular orifice nozzle. After molding the large-diameter opening of the joint boot by injecting molten resin into the cavity, it is separated from the annular orifice nozzle. A drawing device for pulling and forming the tubular parison by moving it, and when the drawing device is moved away from the annular orifice nozzle by a predetermined stroke, the drawing device is moved close to the tubular parison side and clamped, and the inside of the tubular parison A blow molding split mold that blow-molds the parison into a predetermined shape by injecting compressed gas and integrally molds the bellows-shaped hollow portion and the small-diameter mouth portion of the joint boot. is there.

  According to the present invention, among the joint boots, a large-diameter mouth portion that is most difficult to mold and requires the highest dimensional accuracy is first formed by injection molding, and the formed large-diameter mouth portion is kept in a cold state. Since the tubular parison is drawn and formed in a state where the shrinkage rate of the entire circumference is uniform and stabilized, and then the bellows-like hollow part and the small-diameter mouth part are integrally blow-molded using a blow molding split mold, For automobiles and the like where the surface is perfectly round and the inner peripheral surface is desired to have a large-diameter mouth portion with different diameters that are convex and concave having protrusions radially inward at a plurality of locations in the circumferential direction, etc. Even if it is a quick joint boot, it is possible to manufacture a high-quality resin joint boot in which the large-diameter opening is formed with high dimensional accuracy. In addition, cooling of the entire joint boot is completed almost simultaneously with the end of blow molding, and extra time is required for cooling the large-diameter opening as in the case of injection molding the large-diameter opening near the final stage. Therefore, the molding cycle can be increased, and the production efficiency of the high-precision, high-quality resin joint boot can be significantly improved.

  In the present invention, the resin joint boot to be molded is formed such that the outer peripheral surface of the large-diameter mouth portion at one end of the bellows-like hollow portion is formed in a substantially perfect circle shape, and the inner peripheral surface thereof is provided at a plurality of locations in the circumferential direction. In the case of being formed in a concavo-convex shape having a radially inward projecting portion, the projecting portion in the large-diameter mouth portion projects into a radially inward curved shape, and the large-diameter mouth portion An arc-shaped outer wall portion that constitutes a part of the outer peripheral surface, a radially extending central support wall that connects the inner wall portion and the outer wall portion at the center in the circumferential direction thereof, and on both sides of the central support wall It may be provided with left and right side support walls connecting the inner wall portion and the outer wall portion, and the side support walls may be inclined so as to approach the central support wall toward the outside. As a result, the protruding portion is provided with a hollow hole as a hollow portion, and therefore, the protruding portion can be cooled more quickly than in the case where the hollow hole is not formed. In addition, when the side support wall is arranged in parallel to the central support wall, the outer side hole of the side support wall becomes small, so that it is difficult to remove the core, as described above. By inclining toward the center support wall side, the cross-sectional area of the outside hole on the side support wall can be ensured, and the demoldability of the core can be ensured. Furthermore, by tilting the side support wall as described above, the outer side surface of the inner wall portion can be supported by the side support wall substantially perpendicular to the inner wall portion, and therefore, when the large-diameter mouth portion is fastened and fixed, The surface pressure at the inner wall portion can be made uniform in the circumferential direction, and the sealing performance at the large-diameter mouth portion can be improved. From such a viewpoint, the side support wall is coupled substantially perpendicularly to the inner wall portion at an intermediate position between the root portion of the inner wall portion to the outer wall portion and the connecting portion of the central support wall. Preferably it is.

  Further, in the case of providing the protruding portion provided with such a hollow hole, the manufacturing apparatus includes a large-diameter mouth portion forming cavity that is provided at a plurality of locations in the circumferential direction on the inner peripheral surface of the large-diameter mouth portion. A concave portion for forming a protruding portion toward the side, and the drawing device includes a core for forming a hollow hole in the axial direction in the protruding portion, the core being axial with respect to the concave portion In order to ensure the demolding property of the large-diameter mouth portion, it is preferable to be provided so as to be able to advance and retract.

  In the resin joint boot manufacturing apparatus according to the present invention, the split mold constituting the cavity for forming the large-diameter mouth portion in the drawer device is connected to the recessed portion formed at the distal end portion of the drawer device body. An inner mold that can be inserted and fixed in and pulled out in the pulling movement direction, and an outer mold that can be moved laterally by forming an annular portion around the recessed portion and opened. In this case, when taking out the large-diameter opening, the outer mold may be moved sideways to open the mold. Then, by incorporating the split mold that constitutes the cavity into the drawer device in this way, the mold structure is simplified compared to the case where it is provided separately, and the equipment cost of the entire manufacturing apparatus is reduced, while the inner side is reduced. By exchanging and using the mold, it is possible to selectively form a large-diameter opening having various different diameters.

  Further, in the resin joint boot manufacturing apparatus according to the present invention, the split mold constituting the large-diameter opening forming cavity may be provided with a cooling water pipe for cooling and holding the injection-molded large-diameter opening. preferable. In this case, it is possible to quickly and uniformly cool and stabilize the first injection-molded large-diameter opening, and to quickly move to the next parison drawing process, thereby further improving the molding cycle. At the same time, the large-diameter mouth portion can be reliably kept cold even when the tubular parison is pulled out to prevent deterioration of accuracy such as deformation.

  As described above, according to the present invention, it is possible to efficiently manufacture a resin joint boot having a large-diameter mouth portion with very high dimensional accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 and FIG. 2 are a longitudinal sectional view and a bottom view of a resin boot for a triport type constant velocity joint for automobiles, which is a representative example of a resin joint boot to be molded by the present invention. .

  The automobile triport type constant velocity joint resin boot 1 has a large-diameter mouth portion 3 at one end of a bellows-like hollow portion 2 and a small-diameter mouth portion 4 at the other end, which are thermoplastic. As shown in FIG. 2, the large-diameter mouth portion 3 at one end has an outer peripheral surface 3 a formed in a perfect circle shape and an inner peripheral surface 3 b at a plurality of locations in the circumferential direction. (In the drawing, it is shown in three places spaced at equal intervals in the circumferential direction, but it may be two places or four places or more) and is formed in a concavo-convex shape having a radially inwardly projecting portion 3c. The projecting portion 3c of the inner peripheral surface 3b ensures a sealing property between the large-diameter mouth portion 3 when the large-diameter mouth portion 3 is fastened and fixed to an outer case provided at an end portion on the driven shaft side (not shown) via a band or the like. Therefore, it is fitted into a concave portion formed on the outer peripheral surface of the outer case. On the other hand, the small-diameter opening 4 at the other end is shown as it is after blow molding, which will be described later, and finally the tip 4a is cut off along the alternate long and short dash line x to become a product.

  The manufacturing apparatus for the tripart type constant velocity joint resin boot 1 as described above is roughly divided as shown in FIGS. 3 to 7, as shown in FIGS. 3 to 7. An annular orifice nozzle 7 having a diameter corresponding to an inner diameter (D) and having an outlet gap 6 for extruding the thermoplastic molten resin 5 fed by a pressure piston (not shown), and the annular orifice A circumferentially divided auxiliary nozzle base 8 that can be switched between a state of being seated on the outlet gap 6 of the nozzle 7 and a state of being retracted to the side of the orifice nozzle 7, and the outlet gap of the annular orifice nozzle 7 6, a drawer 9 that can be driven and moved in the direction of an arrow ab that is close to and away from 6, and a circumferential direction that can be driven and moved in the direction of an arrow cd that is close to and away from the side of a tubular parison described later And a split blow molding mold part 10.

  The drawing device 9 is provided with a cavity 11 for injection-molding the large-diameter opening 3 of the resin boot 1. The cavity 11 is constituted by a split mold 12 incorporated in the drawer device 9. The split mold 12 includes an inner mold 12A that can be inserted, fixed, and pulled out in the moving direction of the drawer 9 with respect to a recessed section 9a formed at the tip of the drawer body 9A, and an annular portion around the recessed section 9a. The outer mold 12B is a circumferentially divided mold that can be attached to and detached from the outer peripheral surface of the drawer main body 9A from the side. A nozzle core 13 having a conical outer surface is concentrically fixed and held at the center of the inner mold 12A of the split mold 12, and the conical outer surface of the nozzle core 13 and the auxiliary nozzle base 8 are connected to each other in a circle. When seated on the outlet gap 6 of the annular orifice nozzle 7, the diameter gradually increases from the outlet gap 6 toward the cavity 11 between the conical inner surface on the side of the auxiliary nozzle base 8 facing it (conical outer surface). A conical annular molten resin passage 14 is formed. The inner mold 12A is formed of a heat insulating material in this example.

  The blow molding split mold 10 includes a bellows-shaped molding portion 10a corresponding to the outer surface shape of the bellows-shaped hollow portion 2 of the resin boot 1 and a cylinder corresponding to the outer surface shape of the small-diameter mouth portion 4 of the resin boot 1 at one end thereof. It is formed in the inner surface shape which has the shape forming part 10b.

  Further, cooling water pipes 16 are respectively built in the inner mold 12A and the outer mold 12B of the split mold 12 and the portions facing the cavity 11 of the drawer main body 9A. Further, the annular orifice nozzle 7 switches between a state in which the thermoplastic molten resin 5 fed by the pressure piston is pushed out from the outlet gap 6 and a state in which compressed gas for blow molding is sent out instead of the molten resin 5. It is configured to be possible.

  Next, a method of manufacturing the tripod type constant velocity joint resin boot 1 using the manufacturing apparatus having the above configuration will be described in the order of steps.

(1) As shown in FIG. 3, the auxiliary nozzle base 8 is moved and seated on the outlet gap 6 of the annular orifice nozzle 7 to form a conical annular molten resin passage 14 and its auxiliary. By bringing the tip of the drawing device 9 into contact with the nozzle base 8, the outlet gap 6 and the large-diameter mouth forming cavity 11 are connected via the molten resin passage 14. In this state, the molten resin 5 pumped by the pressure piston is injected from the outlet gap 6 of the annular orifice nozzle 7 through the molten resin passage 14 into the cavity 11 on the drawing device 9 side, thereby injecting the molten resin 5 into the cavity 11. First, the large-diameter opening 3 of the resin boot 1 is formed. Immediately after the injection molding, the cooling water is circulated through the cooling water pipe 16, and the large-diameter mouth portion 3 having a uniform shrinkage ratio on the entire circumference and having a dimensionally stable accuracy can be formed.

(2) Next, as shown in FIG. 4, the auxiliary nozzle base 8 is moved and retracted to the side as indicated by an arrow d, and the cold state of the injection molded large-diameter mouth 3 is maintained, While extruding the thermoplastic molten resin 5 from the outlet gap 6 of the annular orifice nozzle 7, the drawing device 9 is moved upwardly away from the annular orifice nozzle 7 as indicated by the arrow b, thereby drawing out the tubular parison 15. To do.

(3) When the drawing device 9 is moved away by a predetermined stroke, that is, when the tubular parison 15 having a predetermined length is formed by being pulled out, the blow mold split mold 10 is moved to the side as shown in FIG. As shown by the arrow c, the mold is moved close to the tubular parison 15 and clamped.

(4) Subsequently, as shown in FIG. 6, from the outlet gap 6 of the annular orifice nozzle 7, a blown compressed gas (generally air) e is tubular instead of the thermoplastic molten resin 5. By blowing into the parison 15 and blow-molding the parison 15 into a shape along the inner surface shape of the blow molding split mold 10, that is, along the bellows-shaped molding portion 10a and the cylindrical molding portion 10b, a resin boot 1 bellows-like hollow portion 2 and small-diameter mouth portion 4 are integrally formed. At this time, the parison 15 is uniformly stretched over the entire circumference, and both the bellows-like hollow portion 2 and the small-diameter mouth portion 4 are formed into a uniform one with high wall thickness accuracy.

(5) Since the cooling of the entire boot 1 is completed almost simultaneously with the completion of the blow molding, the blow molding split mold 10 is moved to the side as shown by the arrow d in FIG. 7 immediately after the blow molding. Of the split molds 12 constituting the large-diameter mouth forming cavity 11, the outer mold 12B is moved to the side indicated by the arrow f to open the mold, and in this state, the resin boot By moving the drawing device 9 upward as indicated by the arrow b while holding 1, the large-diameter mouth portion 3 that is initially injection-molded is taken out from the split mold 12. Thus, a tripod type constant velocity joint resin boot 1 having a predetermined shape in which the large-diameter mouth portion 3 is integrally formed at one end of the bellows-like hollow portion 2 and the small-diameter mouth portion 4 is integrally formed at the other end is efficiently manufactured. be able to.

  8 and 9 are a longitudinal sectional view and a bottom view of a triport type constant velocity joint resin boot 20 according to another embodiment. In this embodiment, the configuration of the protruding portion 3c in the large-diameter mouth portion 3 and the manufacturing method therefor are different from the above-described embodiment, and other configurations are basically the same as those in the above-described embodiment. The parts are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, the projecting portion 3c includes an inner wall portion 31 projecting radially inwardly, an arc-shaped outer wall portion 32 constituting a part of the outer peripheral surface 3a of the large-diameter mouth portion 3, and A radially extending central support wall 33 connecting the inner wall portion 31 and the outer wall portion 32 at the center in the circumferential direction thereof, and left and right connecting the inner wall portion 31 and the outer wall portion 32 on both sides of the central support wall 33. The pair of side support walls 34, 34 are provided. The side support walls 34, 34 are not parallel to the central support wall 33 provided radially from the center of the large-diameter mouth portion 3, but are inclined so as to approach the central support wall 34 toward the outer side. . More specifically, the side support wall 34 is connected to the outer wall portion of the inner wall portion 31 so that the inner wall portion 31 is supported by the central support wall 33 and the side support wall 34 at equal intervals in the circumferential direction. The inner wall portion 31 is supported at an intermediate position between the base portion 31a and the connecting portion 31b between the central support wall, and is therefore connected to the inner wall portion 31 at the intermediate position. Further, the connecting portion is provided so as to be substantially perpendicular to the inner wall portion 31 so as to be closer to the center, that is, so as to approach the central support wall 34 as it goes outward from the connecting portion.

  Thereby, a plurality of (four in this example) lightening holes 36, 35, 35, 36 arranged in the circumferential direction are provided in the protruding portion 3c. The pair of inner hollow holes 35, 35 partitioned by the central support wall 33 has a trapezoidal shape in which the outer peripheral surface 3a side of the large-diameter mouth portion is narrowed. In addition, the pair of outer holes 36, 36 on the outside has a triangular shape.

  In order to form the protruding portion 3c having such a shape, a drawer device 9 shown in FIG. 10 is used in this embodiment. In the drawer 9, axial recess holes 35, 35, 36, 36 are formed in the protrusion 3 c in the recess 17 for forming the protrusion 3 c provided in the large-diameter mouth forming cavity 11. A core 18 is provided. The core 18 is provided so as to advance and retreat in the axial direction with respect to the concave portion 17 by a driving device 19 such as a hydraulic or air cylinder provided in the drawer main body 9A.

  When the resin boot 1 is manufactured, the large-diameter opening 3 is injection-molded with the core 18 projecting into the recess 17, and the core 18 is moved upward by the drive device 19 during demolding after blow molding. And the outer mold 12B is moved sideways to open the mold, and then the drawer device 9 is moved upward to remove the large-diameter opening 3. Other manufacturing methods can be performed in the same manner as in the above embodiment.

  In this embodiment, the core 18 is provided so as to be able to advance and retreat with respect to the recess 17 in this way, and the core 18 is removed after the core 18 is retracted. Compared with the fixed type, the large-diameter mouth portion 3 can be removed smoothly. In other words, if the core is fixed, the frictional resistance between the outer peripheral surface of the core and the inner peripheral surface of the cutout hole is large when the drawer 9 is moved upward to remove the mold. An excessive force acts on the resin boot 1 that holds the drawer device 9 so that it does not move, and there is a risk of deformation, but this problem can be solved by making the core 18 movable forward and backward. .

  In the present embodiment, the protrusion 3c can be cooled more quickly than the case where the hole 3 is not formed by providing the hole 3 and 36 in the protrusion 3c. Further, when the side support walls 34 and 34 are arranged in parallel to the central support wall 33, the lightening hole 36 on the outside of the side support wall 34 becomes small, so that it is difficult to remove the core 18. However, by inclining toward the central support wall 33 side as described above, the cross-sectional area of the outer lightening hole 36 can be secured, and the demoldability of the core 18 can be secured. Further, the inclination enables the outer side surface of the inner wall portion 31 to be supported by the side support wall 34 that is substantially perpendicular to the inner wall portion 31, so that when the large-diameter mouth portion 3 is fastened and fixed, the inner wall portion 31 becomes outer. The surface pressure exerted on the case can be made as uniform as possible in the circumferential direction, and the sealing performance at the large-diameter opening 3 can be improved.

  In the above-described embodiment, the resin boot used for the tripod type constant velocity joint has been described. However, the present invention is not limited to this, and it is effective if the large-diameter opening is a joint boot having a different diameter. Applicable.

  As described above, according to the present invention, among the joint boots, the large-diameter mouth portion that is most difficult to be molded and requires the highest dimensional accuracy is first injection-molded, and the molded large-diameter mouth portion is Since the tubular parison drawer is formed in a cold state, the bellows-like hollow part and the small-diameter mouth part are integrally blow-molded, the outer peripheral surface is a perfect circle and the inner peripheral surface is radially inward at a plurality of locations in the circumferential direction. Even when a constant velocity joint boot or the like for an automobile having a large-diameter mouth portion with an uneven diameter having a protruding portion is formed, the shrinkage rate is stable and the dimensional accuracy is very high. A high-quality resin joint boot having a large-diameter opening can be manufactured. In addition, the cooling of the entire joint boot is completed almost simultaneously with the end of the blow molding, and it is possible to increase the molding cycle in combination with the fact that no extra time is required for cooling the large-diameter opening. it can. Therefore, it is possible to remarkably improve the manufacturing efficiency of the high-dimensional accuracy and high-quality resin joint boot.

FIG. 1 is a longitudinal sectional view of a triport type resin boot for a constant velocity joint for automobiles, which is a representative example of a resin joint boot according to the present invention.
FIG. 2 is a bottom view of the resin boot for the constant velocity joint.
FIG. 3 is a longitudinal sectional view of a main part showing a molded state in a large-diameter mouth portion of the resin boot for a constant velocity joint.
FIG. 4 is a longitudinal sectional view of the main part showing the tubular parison drawer formation state of the resin boot for constant velocity joints.
FIG. 5 is a longitudinal sectional view of a main part showing a state of mold clamping before blow molding of the resin boot for a constant velocity joint.
FIG. 6 is a longitudinal sectional view of the main part showing the blow molding state of the resin boot for the constant velocity joint.
FIG. 7 is a longitudinal sectional view of a main part showing a mold opening state after completion of blow molding of the resin boot for the constant velocity joint.
FIG. 8 is a longitudinal sectional view of a resin boot for a constant velocity joint according to another embodiment.
FIG. 9 is a bottom view of the constant velocity joint resin boot of FIG.
FIG. 10 is a cross-sectional view of a drawer device used for manufacturing the resin boot for a constant velocity joint shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Resin boot for constant velocity joints, 2 ... Bellows-shaped hollow part, 3 ... Large-diameter mouth part, 3a ... Perfect circular outer peripheral surface, 3b ... Irregular-shaped inner peripheral surface, 3c ... Projection part to radial inner side, DESCRIPTION OF SYMBOLS 4 ... Small diameter opening part, 5 ... Thermoplastic molten resin, 6 ... Outlet gap, 7 ... Annular orifice nozzle, 8 ... Auxiliary nozzle nozzle, 9 ... Drawer apparatus, 9A ... Drawer apparatus main body, 9a ... Recessed part, 10 ... Blow Mold split mold, 11 ... cavity for molding large-diameter mouth, 12 ... inner and outer divided molds, 12A ... inner mold, 12B ... outer mold, 14 ... molten resin passage, 15 ... tubular parison, 16 ... cooling water piping, DESCRIPTION OF SYMBOLS 17 ... Cavity recessed part, 18 ... Core, 31 ... Inner side wall part, 32 ... Outer wall part, 33 ... Center support wall, 34 ... Side support wall, 35, 36 ... Meat hole

In the manufacturing method according to the present invention, in the step of forming the large-diameter mouth portion, the outer peripheral surface of the large-diameter mouth portion is formed in a substantially perfect circle shape, and the inner peripheral surface is a plurality of locations in the circumferential direction. Formed in a concavo-convex shape having a radially inwardly projecting portion, and the projecting portion is a circle constituting a part of the outer peripheral surface of the inner diameter side portion projecting in a radially inward shape and the large diameter mouth portion An arcuate outer wall, a radially extending central support wall connecting the inner wall and the outer wall at the center in the circumferential direction, and connecting the inner wall and the outer wall on both sides of the central support wall The left and right side support walls are provided, and the large-diameter mouth portion is formed by inclining the side support walls toward the center support wall toward the outside. As a result, the protruding portion is provided with a hollow hole as a hollow portion, and therefore, the protruding portion can be cooled more quickly than in the case where the hollow hole is not formed. In addition, when the side support wall is arranged in parallel to the central support wall, the outer side hole of the side support wall becomes small, so that it is difficult to remove the core, as described above. By inclining toward the center support wall side, the cross-sectional area of the outside hole on the side support wall can be ensured, and the demoldability of the core can be ensured. Furthermore, by tilting the side support wall as described above, the outer side surface of the inner wall portion can be supported by the side support wall substantially perpendicular to the inner wall portion, and therefore, when the large-diameter mouth portion is fastened and fixed, The surface pressure at the inner wall portion can be made uniform in the circumferential direction, and the sealing performance at the large-diameter mouth portion can be improved. From such a viewpoint, the side support wall is coupled substantially perpendicularly to the inner wall portion at an intermediate position between the root portion of the inner wall portion to the outer wall portion and the connecting portion of the central support wall. Preferably it is.

1 and 2 are a longitudinal sectional view and a bottom view of a triport type constant velocity joint resin boot for an automobile according to a reference example .

8 and 9 are a longitudinal sectional view and a bottom view of a triport type constant velocity joint resin boot 20 according to an embodiment of the present invention . Since in this embodiment, unlike the reference example configuration and manufacturing method therefor of the projecting portion 3c of the large径口section 3 above, the other structure is the same as in Reference Example basically the same configuration The parts are denoted by the same reference numerals and description thereof is omitted.

It is a longitudinal cross-sectional view of the resin-made boot for triport type constant velocity joints for motor vehicles concerning a reference example . It is a bottom view of the resin boots for constant velocity joints same as the above. It is a longitudinal cross-sectional view of the principal part which shows a molding state in the large diameter opening part of the resin boots for constant velocity joints same as the above. It is a longitudinal cross-sectional view of the principal part which shows the drawer formation state of the tubular parison of the resin boots for constant velocity joints same as the above. It is a longitudinal cross-sectional view of the principal part which shows the clamping state before blow molding of the resin boots for constant velocity joints same as the above. It is a longitudinal cross-sectional view of the principal part which shows the blow molding state of the resin boots for constant velocity joints same as the above. It is a longitudinal cross-sectional view of the principal part which shows the mold open state after completion of blow molding of the resin boot for constant velocity joints same as the above. It is a longitudinal cross-sectional view of the resin boots for constant velocity joints which concern on embodiment of this invention . It is a bottom view of the resin boots for constant velocity joints of FIG. It is sectional drawing of the drawer | drawing-out apparatus used for manufacture of the resin boots for constant velocity joints of FIG.

Claims (8)

A resin joint boot manufacturing method in which a joint boot having a large-diameter mouth portion at one end of a bellows-like hollow portion and a small-diameter mouth portion at the other end is integrally formed of a thermoplastic resin,
For forming the large-diameter mouth portion of the joint boot on the outlet gap of the annular orifice nozzle having a diameter corresponding to the small-diameter mouth portion of the joint boot and having an outlet gap capable of extruding the thermoplastic molten resin. A cavity of a drawing device having a cavity is brought into contact with each other via an auxiliary nozzle base that forms a conical annular molten resin passage whose diameter gradually increases from the outlet gap toward the cavity of the drawing device. Molding the large-diameter mouth portion of the joint boot by injecting the molten resin into the cavity of the drawing device from the outlet gap of the annular orifice nozzle in the state through the molten resin passage having a conical annular shape;
The auxiliary nozzle base is moved and retracted to the side, and the drawn-out device is moved away from the annular orifice nozzle while extruding the molten resin through the outlet gap of the annular orifice nozzle while keeping the formed large-diameter mouth portion cooled. Drawing and forming a tubular parison by:
When the drawing device is moved away from the annular orifice nozzle by a predetermined stroke, the blow molding split mold is moved closer to the tubular parison side from the side and clamped;
Blowing compressed gas into the tubular parison and blow molding the parison into a shape that conforms to the inner surface shape of the blow molding split mold, and integrally molding the bellows-shaped hollow portion and the small diameter mouth portion of the joint boot;
Opening the mold by moving the blow molding split mold to the side, and opening the split mold that constitutes the cavity for forming the large-diameter mouth part and taking out the large-diameter mouth part;
A method for producing a resin joint boot, comprising: In the resin joint boot to be molded, the outer peripheral surface of the large-diameter mouth portion at one end of the bellows-shaped hollow portion is formed in a substantially circular shape, and the inner peripheral surface is radially inward at a plurality of locations in the circumferential direction. The method for producing a resin joint boot according to claim 1, wherein the resin joint boot is formed in an uneven shape having a protruding portion. The projecting portion of the large-diameter mouth portion includes an inner wall portion projecting in a radially inward shape, an arc-shaped outer wall portion constituting a part of the outer peripheral surface of the large-diameter mouth portion, and these inner wall surfaces A central support wall extending in the radial direction connecting the outer wall portion and the outer wall portion at the center in the circumferential direction, and left and right side support walls connecting the inner wall portion and the outer wall portion on both sides of the central support wall. The method of manufacturing a resin joint boot according to claim 2, wherein the side support wall is inclined so as to approach the central support wall toward the outer side. The side support wall is connected substantially perpendicularly to the inner wall portion at an intermediate position between a base portion of the inner wall portion to the outer wall portion and a connecting portion of the central support wall. The method for producing a resin joint boot according to claim 3. A resin joint boot manufacturing apparatus for integrally molding a joint boot having a large-diameter mouth portion at one end of the bellows-shaped hollow portion and a small-diameter mouth portion at the other end with a thermoplastic resin,
An annular orifice nozzle having a diameter corresponding to the small-diameter mouth portion of the joint boot and having an outlet gap capable of extruding a thermoplastic molten resin;
It is possible to switch between a state in which the annular orifice nozzle is disposed in contact with the outlet gap and a state in which the annular orifice nozzle is moved and retracted to the side. In the state in which the annular orifice nozzle is disposed in contact with the outlet gap, An auxiliary nozzle base that forms a conical annular molten resin passage that gradually increases in diameter from the outside to the outside,
The auxiliary nozzle base has a large-diameter mouth forming cavity that can be connected to the outlet gap of the annular orifice nozzle through the conical annular molten resin passage, and the joint boot is injected by injecting the molten resin into the cavity. A drawer device that draws and forms a tubular parison by moving away from the annular orifice nozzle after forming the large-diameter mouth portion of
When the drawing device is moved away from the annular orifice nozzle by a predetermined stroke, the drawing device is moved close to the tubular parison side and clamped, and compressed gas is blown into the tubular parison to blow the parison into a predetermined shape. A blow molding split mold that integrally molds the bellows-shaped hollow portion and the small-diameter mouth portion of the joint boot,
An apparatus for manufacturing a resin joint boot, comprising: The split mold that constitutes the cavity for forming the large-diameter mouth portion in the drawer device is an inner mold that can be inserted and fixed in and pulled out from the recessed portion formed at the tip of the drawer device body in the drawer movement direction. An apparatus for manufacturing a resin joint boot according to claim 5, further comprising: an outer mold that forms an annular portion around the recessed portion and that can be moved laterally to open the mold. The resin mold according to claim 5 or 6, wherein the split mold that constitutes the cavity for forming the large-diameter opening is provided with a cooling water pipe for cooling and holding the large-diameter opening of the injection-molded joint boot. Joint boot manufacturing equipment. The large-diameter mouth forming cavity includes concave portions for forming radially inward projecting portions at a plurality of locations in the circumferential direction on the inner peripheral surface of the large-diameter mouth portion, and the drawer device includes the projecting portion. A core for forming an axial hole is formed in the core, and the core is provided so as to be movable back and forth in the axial direction with respect to the recess. Equipment for plastic joint boots.

Images