JP2010188635A - Mold and method for manufacturing tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a tire which can improve the positional accuracy of a bead core by reducing the injection pressure of a thermoplastic material, and a mold. <P>SOLUTION: The bead core 11 is arranged at a prescribed position in the cavity S of a mold 10, and melt casting in which a molten thermoplastic resin is pressed and injected into the cavity S is carried out to mold a tire skeleton member 20. Since the melt casting is carried out, and the molten thermoplastic resin is pressed and injected, pressing force can notably be reduced as compared with the operation of injection molding. Since the movement of the bead core 11 when it is injected can easily be controlled, the positional accuracy of the bead core 11 can easily be improved. The pressure resistant structure of the mold 10 can remarkably be simplified. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire manufacturing method and a mold for molding a tire frame member.

  Conventionally, a tire formed of rubber, an organic fiber material, and a steel member is known. In recent years, from the viewpoint of weight reduction and ease of recycling, it is required to use a thermoplastic polymer material such as a thermoplastic elastomer (TPE) or a thermoplastic resin for a tire. For this reason, for example, Patent Document 1 proposes forming a tire frame member by covering a bead core with a thermoplastic elastomer.

JP 05-116504 A

  However, in Patent Document 1, since the pressure applied to the inside of the mold, that is, the injection pressure of the thermoplastic elastomer is extremely high, the bead core easily moves. For this reason, there existed problems, such as it being difficult to raise the positional accuracy of a bead core and a bead core deform | transforming.

  On the other hand, if the shape of the support piece is complicated or the support piece is made large in order to improve the position accuracy, it is necessary to destroy the thermoplastic material constituting the tire or form a hole in the thermoplastic material when removing the hook. There is a problem such as that there is a concern that the tire performance and the tire appearance may be adversely affected.

  In view of the above facts, an object of the present invention is to provide a tire manufacturing method and a mold that can improve the position accuracy of the bead core by reducing the injection pressure of the thermoplastic material.

  According to the first aspect of the present invention, a melting pot for melting a thermoplastic material is provided above a cavity of a mold for molding a tire frame member, a bead core is disposed in the cavity, and the molten material stored in the melting pot is stored. The tire frame member constituting at least the tire bead portion is molded by pressing the injected thermoplastic material into the cavity.

  In the invention described in claim 1, since the thermoplastic material is pressed and injected, the pressing force can be remarkably reduced as compared with injection molding. Accordingly, since the movement of the bead core during injection is easily suppressed, the position accuracy of the bead core can be easily increased. Moreover, the pressure | voltage resistant structure of a metal mold | die can be simplified greatly.

  The injection of the thermoplastic molten material may be high-pressure injection for injection molding. The tire frame member may be formed in a tube shape so that air can be filled in the tire frame member.

  As the thermoplastic material, a thermoplastic resin having a rubber-like elasticity, a thermoplastic elastomer (TPE), or the like can be used. In consideration of the elasticity at the time of travel and the moldability at the time of manufacture, the thermoplastic elastomer is injected. It is preferable.

  Examples of the thermoplastic elastomer include amide-based thermoplastic elastomer (TPA), ester-based thermoplastic elastomer (TPC), olefin-based thermoplastic elastomer (TPO), styrene-based thermoplastic elastomer (TPS) specified in JIS K6418, Examples thereof include urethane-based thermoplastic elastomer (TPU), crosslinked thermoplastic rubber (TPV), and other thermoplastic elastomers (TPZ). Examples of the thermoplastic synthetic resin include urethane resin, olefin resin, vinyl chloride resin, polyamide resin, and the like.

According to a second aspect of the present invention, melt casting is performed by melting resin pellets as the thermoplastic material, pressing the inside of the melting pot with a press machine, and pressing the thermoplastic material into the cavity.
Thereby, melt casting can be performed easily.

According to a third aspect of the present invention, a skeleton portion from a tire bead portion to a tire center is formed as the tire skeleton member.
In the invention according to claim 3, the tire frame member constituting the tire half is formed. Therefore, by joining two tire frame members at the tire center, a frame member with a bead core for the entire tire can be formed.

In the invention according to claim 4, the thermoplastic material is injected from the tire center side.
In the invention according to claim 4, it is not necessary to inject the thermoplastic material from the vicinity of the bead core when manufacturing the tire. In addition, when injecting a thermoplastic material, air is often exhausted by suction or the like from a bead portion forming end.
According to the fourth aspect of the present invention, it is possible to suppress the displacement and deformation of the bead core due to the injection of the thermoplastic material.

According to a fifth aspect of the present invention, an injection disk gate for injecting a molten thermoplastic material into the cavity is provided, and the thermoplastic material is injected from the injection disk gate.
Thereby, it is easy to uniformly inject the thermoplastic material into the cavity.

According to a sixth aspect of the present invention, an injection pin gate for injecting molten thermoplastic material into the cavity and an exhaust pin gate for exhausting air in the cavity are alternately arranged along the tire circumferential direction. Then, a thermoplastic material is injected from the injection pin gate while the air in the cavity is exhausted by the exhaust pin gate.
Thereby, it is easy to inject the thermoplastic material into the cavity in a state where air does not enter.
In addition, when exhausting the air in a cavity, the exhaust by suction is suitable from a viewpoint of moldability.

  According to the seventh aspect of the invention, a melting pot for melting the thermoplastic material is provided above the cavity, and the molten thermoplastic material stored in the melting pot is pressed and injected into the cavity. At least a tire frame member constituting the tire bead portion is formed.

  In the invention according to claim 7, since the thermoplastic material is pressed and injected, the pressing force can be remarkably reduced as compared with injection molding. Accordingly, since the movement of the bead core during injection is easily suppressed, the position accuracy of the bead core can be easily increased. Moreover, the pressure | voltage resistant structure of a metal mold | die can be simplified greatly.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the manufacturing method of a tire which improved the position accuracy of the bead core by reducing the injection | pouring pressure of a thermoplastic material, and a metal mold | die.

FIG. 1A to FIG. 1E are process diagrams respectively showing that the resin is melted in the melting pot and the molten resin is injected into the cavity and molded in the first embodiment. FIGS. 2A and 2B are a partial perspective sectional view showing that the bead core is disposed in the lower mold and supported by the support portion in the first embodiment, and a partial enlarged view of FIG. FIG. 3A to 3C are a perspective view of a heating and melting part, a perspective view showing that resin pellets are put in a melting pot of an overheating melting part, and a formed tire in the first embodiment, respectively. It is a perspective view of a frame member. It is side surface sectional drawing which shows the tire frame member of the whole tire in 1st Embodiment. In 2nd Embodiment, it is side surface sectional drawing which shows inject | pouring molten resin and forming a tire frame | skeleton member. FIG. 10 is a side cross-sectional view showing that a tire frame member is formed by injecting molten resin in a modification of the second embodiment. In the third embodiment, a perspective view for explaining that the resin injection pin gate and the air exhaust pin gate for exhausting the air in the cavity are alternately arranged in the upper mold along the tire circumferential direction in the third embodiment. It is. It is side surface sectional drawing which shows inject | pouring molten resin in a cavity from the resin injection pin gate in 3rd Embodiment.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. In this embodiment, a press machine is used. As shown in FIGS. 1 to 3, the press machine includes a mold 10 composed of an outer mold 12 and an inner mold 14, a heating / melting section 16 provided on the upper side of the mold 10, and heating. And a press part 18 provided on the upper side of the melting part 16.

  The mold 10 includes an outer mold 12 that molds the tire outer surface side and an inner mold that molds the tire inner surface side so that the tire frame member 20 constituting the bead portion B to the tire center CL can be molded. 14. A cavity S (space) in the shape of a tire frame member is formed between the outer mold 12 and the inner mold 14. A convex support 22 for fixing the bead core is formed on the outer mold 12 so as to protrude into the cavity.

  The upper part of the outer mold 12 and the upper part of the inner mold 14 form the same plane. The heating and melting part 16 is provided on the same plane. In the heating and melting portion 16, a melting pot 17 is formed in which a solid resin (for example, resin pellet P; see FIG. 3B) is injected as a thermoplastic material for injection. The heating and melting portion 16 is formed with a gate 26 communicating with the bottom surface of the melting pot 17 and the upper end ST of the cavity S. The gate 26 is formed with a frustoconical wall surface whose diameter gradually decreases from top to bottom. The press unit 18 includes an extruding unit 21 that is inserted into the melting pot 17 and extrudes the molten resin M in the melting pot 17 to the gate 26.

  In the present embodiment, the bead core 11 is disposed in a predetermined position in the cavity S, and a thermoplastic material such as a thermoplastic resin is injected to form a tire skeleton member 20 that constitutes one half of the tire (FIG. 1E). 3 (see FIG. 3C). And the tire one side half part and the tire other side half part are joined by tire center CL, and the tire frame member Z for the whole tire is formed (refer FIG. 4).

  Then, as a reinforcement of the crown portion, the steel cord K is wound in a spiral manner in the tire circumferential direction to increase the circumferential rigidity. Moreover, the rubber material G1 is affixed to the site | part fitted to a wheel (rim flange), and the fitting property to a rim is improved. In addition, a rubber material (tread rubber G2) is attached to a portion in contact with the road surface to improve wear resistance and breakage resistance.

  Hereinafter, molding of the tire frame member 20 with the mold 10 using a thermoplastic resin will be described in detail.

  First, the mold 10 is opened, the bead core 11 is supported by the support portion 22 (see FIGS. 2 and 3A), and the mold 10 is closed. The support portion 22 may support the magnetic bead core 11 by magnetic force, for example.

  Moreover, the resin pellet P is thrown into the melting pot 17 as a thermoplastic solid resin (refer FIG. 3 (B)). When the resin pellet P is charged, the pellet may be charged using a resin extruder or the like. Alternatively, the melting pot 17 may be opened and poured directly, or the melting pot 17 may be closed so as not to be exposed to the atmosphere, and the molten pot 17 may be poured directly into it with a resin extruder or the like.

Furthermore, the resin pellet P is heated by the heating and melting unit 16 to be in the state of the molten resin M in the melting pot 17 (see FIG. 1A).
And the press part 18 is lowered | hung, the extrusion part 21 is inserted in the melting pot 17, and the molten resin M is pressed by low pressure (refer FIG. 1 (B)). As a result, the molten resin M starts to flow to the gate 26. At the beginning of the flow of the molten resin M, the press pressure by the press unit 18 decreases rapidly. Thereafter, the press portion 18 is pressed at a slightly high pressure to inject the molten resin M into the cavity S (see FIG. 1C).

  After the molten resin M is filled in the cavity S, cooling of the mold 10 is started and the molten resin M is solidified (see FIG. 1D).

  After cooling, the mold 10 is opened and the tire frame member 20 is taken out (see FIGS. 1E and 3C).

  As described above, in the present embodiment, since the thermoplastic molten resin is pressed and injected by performing melt casting, the pressing force required for injection can be remarkably reduced as compared with injection molding. For example, the pressure in the cavity can be reduced to 1/10 or less as compared with the case of injection molding. Further, since it is easy to suppress the movement of the bead core 11 during injection, a simple support portion 22 (for example, a support portion supported by magnetic force) that does not support the bead core 11 very firmly can be provided, and the positional accuracy of the bead core 11 can be provided. Can be easily increased.

  In addition, melt casting is performed by using resin pellets P as a thermoplastic material, and forming the molten resin M into the cavity S by the press portion 18. Thereby, melt casting can be performed easily.

  Further, as the tire frame member 20, a frame part from the bead part B to the tire center CL is formed. Therefore, the tire frame member 20 constituting the tire half is formed. Therefore, by joining two tire frame members at the tire center, a frame member with a bead core for the entire tire can be formed.

  Further, the molten resin M is injected from the tire center CL side. Thereby, when manufacturing a tire, the influence of the positional accuracy of the bead core 11 by injection | pouring can be reduced significantly.

  Note that an exhaust path for exhausting the air in the cavity S from the bead portion forming end SE may be formed, and the thermoplastic material may be injected into the cavity S while exhausting the air in the cavity. Thereby, the thermoplastic material can be smoothly injected into the cavity S.

[Second Embodiment]
Next, a second embodiment will be described. In the present embodiment, as compared with the first embodiment, instead of the heating and melting section 16, as shown in FIG. 5, an extrusion screw 30 provided with a screw section 29 for extruding a thermoplastic molten resin downward, A plate-shaped resin guide portion 34 is provided in which a resin injection port 32 is formed in the center portion on the upper surface side and molten resin from the extrusion screw 30 is injected. The resin guide portion 34 includes a lower portion 34L that forms a disk gate 36 communicating with the upper end side of the cavity S, that is, the tire center side, and a guide path 38 that guides the molten resin from the resin injection port 32 to the disk gate 36. And an upper portion 34U.

  In this embodiment, when the molten resin is injected into the cavity S by melt casting, the resin is injected downward from the disk gate 36 opened in a ring shape. Thus, since it inject | pours from the disk gate 36, compared with the case where it inject | pours from a pin gate, it is easy to inject | pour molten resin uniformly in the cavity S, and is preferable from a viewpoint of a moldability.

  In this embodiment, the resin is injected from the disk gate 36 on the tire center side, but it is also possible to invert the mold 10 shown in FIG. 5 and inject the molten resin from the bead portion forming end SE.

  Moreover, as shown in FIG. 6, you may provide the extrusion screw 40 so that molten resin may be inject | poured from a side.

[Third Embodiment]
Next, a third embodiment will be described. In the present embodiment, as shown in FIGS. 7 and 8, the structures of the mold 50 and the resin guide portion 60 are different from those of the second embodiment. An extrusion screw 70 for extruding the thermoplastic molten resin downward is provided in place of the extrusion screw 30.

  The mold 50 includes an outer mold 52 and an inner mold 54. A hollow portion 56 is formed at the center of the mold 50. And as shown in FIG. 8, the exhaust path 58 which enables the air in the cavity S to be exhausted from the bead part formation end SE in the state which closed the metal mold | die 50 is formed. The exhaust path 58 communicates with the hollow portion 56.

  Further, as shown in FIG. 7, the resin guide portion 60 includes a resin injection pin gate 62 and an air exhaust pin gate 64 that exhausts air in the cavity S in the tire circumferential direction instead of the disk gate 36 (see FIG. 5). And lower portions 60L arranged alternately along the upper and lower portions 60L, and upper portions 60U formed with guide paths 68 for guiding the molten resin from the resin inlet 61 formed on the upper side to the resin injection pin gate 62. Yes.

  The extrusion screw 70 is disposed at a position where it can be injected into the resin injection port 61.

  In the present embodiment, when molten resin is injected into the cavity S by performing melt casting, the thermoplastic melt resin is extruded from the extrusion screw 70 while air is exhausted from the air exhaust pin gates 64 and the exhaust passages 58 in the cavity S. The resin is injected into the cavity S from each resin injection pin gate 62. Thereby, it is easy to inject the molten resin into the cavity S smoothly in a state where air does not enter. Further, since the exhaust path 58 is open to the bead portion forming end SE, the molten resin is easily filled up to the bead portion forming end SE.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. In these embodiments, it is preferable from the viewpoint of formability that the air in the cavity is exhausted by suction. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

10 Mold 18 Press part (Press part)
20 Tire frame member 36 Disc gate (Injection disc gate)
50 Mold 62 Resin injection pin gate (injection pin gate)
64 Air exhaust pin gate (exhaust pin gate)
B Tire bead CL Tire center P Resin pellet S Cavity

Claims (7)

A melting pot for melting the thermoplastic material is provided above the cavity of the mold for molding the tire frame member,
Placing a bead core in the cavity;
A tire manufacturing method in which at least a tire frame member constituting a tire bead portion is formed by pressing a molten thermoplastic material stored in the melting pot and injecting the molten thermoplastic material into the cavity.   The tire manufacturing method according to claim 1, wherein melt casting is performed by melting resin pellets as the thermoplastic material, pressing the inside of the melting pot with a press machine, and pressing the thermoplastic material into the cavity.   The tire manufacturing method according to claim 1, wherein a skeleton portion from a tire bead portion to a tire center is formed as the tire skeleton member.   The method for manufacturing a tire according to claim 3, wherein the thermoplastic material is injected from the tire center side.   The tire manufacturing method according to any one of claims 1 to 4, wherein an injection disc gate for injecting molten thermoplastic material into the cavity is provided, and the thermoplastic material is injected from the injection disc gate. .   An injection pin gate for injecting molten thermoplastic material into the cavity and an exhaust pin gate for exhausting air in the cavity are alternately arranged along the tire circumferential direction, and the air in the cavity is The method for manufacturing a tire according to any one of claims 1 to 4, wherein a thermoplastic material is injected from the injection pin gate while exhausting with an exhaust pin gate. A melting pot for melting the thermoplastic material is provided above the cavity;
The mold by which the tire frame member which constitutes at least a tire bead part is fabricated because the molten thermoplastic material stored in the melting pot is pressed and injected into the cavity.