JP6130761B2 - Tire molding die and tire molding method - Google Patents

Description

  The present invention relates to a tire molding die and a tire molding method.

  2. Description of the Related Art Conventionally, as a tire molding die, a mold having a configuration in which an arc segment is elastically supported by a holder in a radial direction of an unvulcanized tire (green tire) via a compression spring is known (for example, see Patent Document 1) ).

However, in the conventional tire molding die, the role of the compression spring is merely to gradually increase the pressure contact force of the arc-shaped segment to the tread portion of the unvulcanized tire. The arc-shaped segment cannot move in the vertical direction, and there is a possibility that an unvulcanized tire may be caught between the arc-shaped segment and the lower mold during mold clamping.
The arc segment can move in the radial direction with respect to the circumferential groove formed on the inner periphery of the holder, but cannot move in the vertical direction, and both require high assembly accuracy.

JP 2012-166532 A

  An object of the present invention is to effectively prevent rubber biting during vulcanization molding of a green tire without requiring high assembly accuracy.

As a means for solving the above problems, the present invention provides:
A first mold and a second mold that are relatively movable along the axial direction of the green tire and can be press-contacted to the respective side portions of the green tire;
A third mold that is movable in the radial direction of the green tire and that can be pressed against the tread portion of the green tire;
With
The third mold is
A plurality of segments divided in the circumferential direction and movable in the radial direction of the green tire;
For each of the segments, a sector that is elastically supported so as to be movable in the axial direction and the radial direction of the green tire and can be pressed against the tread portion of the green tire ,
Equipped with a,
It said segments, to provide a tire mold, characterized in der Rukoto intended to correct the position of the green tire while moving the sectors in the axial direction and the radial direction of the green tire.

  With this configuration, that is, a configuration in which the sector is elastically supported so as to be movable with respect to the segment, the assembly accuracy of both members is not so required. When the mold is clamped, the sector is movable, so that it does not cause problems such as collision and wear as in the case of being fixed. In mold clamping, the sector first comes into contact with the tread portion of the green tire. In this state, the sector is movable in both the axial direction and the radial direction of the green tire. Therefore, even if the green tire is deviated from the normal position, when the segment is pushed into the inner diameter side, the sector moves so as to have an appropriate positional relationship with the tread portion. When the sector is further pushed in by the segment, the elastic force acting on the tread portion from the sector gradually increases. Then, the elastic force acting on the tread portion from the sector further increases, and the misalignment of the green tire is corrected (centering). That is, the green tire can be vulcanized and molded at the regular position, and the occurrence of tire defects (rubber biting) can be prevented.

The segment has a recess extending in the circumferential direction of the green tire on the inner peripheral surface,
It is preferable that the sector has a convex portion that is guided in the concave portion while limiting a movement range in an axial direction and a radial direction of the green tire.

  With this configuration, the sector guide state by the segment can be stabilized. That is, it is possible to easily limit the movable range of the sector with respect to the segment simply by positioning the convex portion of the sector in the concave portion.

Each mold is installed so that the radial direction of the green tire set in the mold coincides with the horizontal direction,
It is preferable that a vertical elastic support for elastically supporting at least the lower surface of the sector is provided for the segment.

  With this configuration, the movement state of the sector at the time of mold clamping can be stabilized. Further, when the sector comes into contact with the tread portion of the green tire and is pressed toward the inner diameter side by the segment, the displacement of the green tire can be corrected by the urging force of the upper and lower elastic supports.

The upper and lower elastic supports include a first elastic support that supports the upper surface of the sector and a second elastic support that supports the lower surface,
It is preferable that the first elastic support and the second elastic support have different spring constants.

  With this configuration, for example, if the pressure applied from above increases during vulcanization, the spring constant of the first elastic support can be increased to make it difficult to deform. On the other hand, if the weight of the sector is large, the spring constant of the second elastic support can be increased to stabilize the sector support state.

  Furthermore, it is preferable to provide a horizontal elastic support for elastically supporting the outer peripheral surface of the sector with respect to the segment.

  With this configuration, when the urging force by the horizontal elastic support body is not so large, the positional deviation of the green tire can be corrected by the vertical elastic support body. After the correction of the positional deviation, the urging force by the horizontal elastic support body is increased, and a tread portion having a desired shape can be obtained.

As a means for solving the above problems, the present invention provides:
In any of the tire molding molds,
Mold clamping,
A first step of pressure-contacting the first mold and the second mold to both side portions of the green tire;
A second step of bringing the sector of the third mold into contact with the tread portion of the green tire;
A third step of correcting the position of the green tire while moving the sector in the axial direction and the radial direction of the green tire by the segment;
A fourth step of pressing the sector against the tread portion;
The tire molding method performed in is provided.

  According to the present invention, the third mold for vulcanizing and molding the tread portion of the green tire is separated into the segment and the sector, and the sector can be moved in the axial direction and the radial direction of the green tire with respect to the segment. It is designed to be elastically supported in a stable state. Therefore, a sector can be attached to a segment without requiring high assembly accuracy between the segment and the sector. The sector is elastically supported so as to be movable not only in the radial direction of the green tire but also in the axial direction. For this reason, even when the green tire is displaced from the normal position when the mold is clamped, the position can be corrected by the sector that is elastically supported and is movable in the axial direction and the radial direction of the green tire. As a result, it becomes possible to appropriately perform vulcanization molding of the green tire.

It is a general | schematic fragmentary sectional view which shows the clamping state of the metal mold | die for tire molding which concerns on this embodiment. FIG. 2 is a schematic partial cross-sectional view showing a mold opening state of the tire molding die shown in FIG. 1. FIG. 3 is a schematic partial cross-sectional view showing a state in which the sector is brought into contact with a tread portion of a green tire from FIG. 2.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, terms including “up”, “down”, “side”, “end”) are used as necessary. Is for facilitating understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a schematic cross-sectional view of a tire molding die 1 according to the present embodiment. The tire molding die 1 includes a first die 2, a second die 3, a third die 4, and a bladder 5.

The 1st metal mold | die 2 is comprised by the upper side plate here. The upper side plate is in pressure contact with the upper side portion (including the bead portion) of the green tire 6 disposed in the mold so that the axial center direction is aligned with the vertical direction.
The 2nd metal mold | die 3 is comprised by the lower side plate here. A lower side plate (including a bead portion) of the green tire 6 is placed on the lower side plate.

The third mold 4 includes a segment 7 and a sector 8.
The segments 7 are a plurality of segments divided in the circumferential direction, and can be reciprocated in the radial direction of the green tire 6 by a driving means (not shown). The outer peripheral surface of the segment 7 is formed in a conical surface shape that gradually spreads from the upper side to the lower side in the outer diameter direction.

  Further, the upper guide wall portion 9 and the lower guide wall portion 10 are respectively formed on the inner peripheral surface of the segment 7 by projecting the upper and lower end portions to the inner diameter side. A space surrounded by the lower surface of the upper guide wall portion 9, the upper surface of the lower guide wall portion 10, and the inner peripheral surface between both wall portions is a guide recess 11 extending in the circumferential direction.

  A first elastic support body 12 and a second elastic support body 13 which are upper and lower elastic support bodies are respectively attached to the upper guide wall section 9 and the lower guide wall section 10. In both cases, a configuration in which a metal sphere is integrated with the tip portion of the coil spring can be adopted. By adopting this configuration, that is, a configuration including a spherical body, when the sector 8 described later moves in the radial direction, the frictional resistance with the bottom surface of the groove portion 21 is suppressed so that the movement of the sector 8 is not hindered. Yes. In addition, such an up-and-down elastic support body has a simple configuration and excellent maintainability.

  A guide groove 14 extending in the circumferential direction is formed at the center in the vertical direction of the inner peripheral surface of the guide recess 11. The guide groove 14 is an example of a recess according to the present invention, and a communication hole 16 for inserting the guide pin 15 from the outer peripheral surface of the segment 7 is opened there. Further, horizontal elastic supports 17 are attached to the inner peripheral surface of the guide recess 11 in the vertical direction with the guide groove 14 interposed therebetween. As the horizontal elastic support members 17, similarly to the above, those having the same structure as the upper and lower elastic support members that do not hinder the movement of the sector 8 and are excellent in maintainability can be adopted.

  The segment 7 reciprocates in the radial direction on the outer peripheral surface thereof by a pressure ring 19 that moves up and down via a holster plate 18 by a driving means (not shown).

  The sector 8 is formed with a molding recess 20 for forming a tread portion (including a shoulder portion) on the inner peripheral surface. The upper and lower surfaces of the sector 8 are configured as flat surfaces that respectively oppose the lower surface of the upper guide wall portion 9 and the upper surface of the lower guide wall portion 10 of the segment 7. On the upper and lower surfaces, groove portions 21 in which the spheres of the first elastic support body 12 and the second elastic support body 13 are positioned are formed.

The outer peripheral surface of the sector 8 is curved along the inner peripheral surface of the guide recess 11 of the segment 7, and a protrusion 22 extending in the circumferential direction is formed at the center portion in the vertical direction. The protrusion 22 has a guide hole 23 in the central portion in the circumferential direction, and is disposed in the guide groove 14 formed in the guide recess 11 of the segment 7. The guide hole 23 of the protrusion 22 is formed in a rectangular shape in which the guide pin 15 provided in the segment 7 can move within a predetermined range. Accordingly, the sector 8 is supported so as to be movable within a range limited by the guide hole 23 and the guide pin 15 in the circumferential direction and the radial direction with respect to the segment 7.
Further, the horizontal elastic support members 17 are in pressure contact with the outer peripheral surface of the sector 8 at positions above and below the protrusions 22, respectively.

  Thus, the sector 8 is supported so as to be movable in the axial direction and the radial direction of the green tire 6 with respect to the segment 7. Moreover, the sector 8 is elastically supported by the first elastic support body 12 and the second elastic support body 13 in the vertical direction and elastically supported by the horizontal elastic support body 17 in the radial direction. Therefore, the assembly accuracy of the sector 8 with respect to the segment 7 is not so required. When the mold is clamped, in the third mold 4, the molding recess 20 of the sector 8 moves in the axial direction and the radial direction along the tread portion regardless of the misalignment of the green tire 6. Correct the tire position to the proper molding position.

  The bladder 5 is disposed in the mold, swells in the radial direction, presses against the inner peripheral surface of the green tire 6, and the green tire 6 is attached to the first mold 2, the second mold 3, and the third mold 4. Vulcanization molding is possible.

  Next, a method for vulcanizing and molding the green tire 6 using the tire molding die 1 having the above-described configuration will be described.

  Open the mold and place the green tire 6 inside. In this state, the upper side portion of the green tire 6 is placed on the second mold 3. The first mold 2 is located above the green tire 6, and the third mold 4 is located on the outer diameter side of the green tire 6.

  As shown in FIG. 2, the first mold 2 is lowered, and its lower surface is brought into contact with the upper side portion of the green tire 6. The holster plate 18 is lowered and the segment 7 is moved in the inner diameter direction via the pressure ring 19. Thereby, as shown in FIG. 3, first, the molding concave portion 20 of the sector 8 comes into contact with the tread portion of the green tire 6. At this time, the elastic force acting on the sector 8 from each elastic support is weak, and the sector 8 can move freely in the circumferential direction, axial direction and radial direction with respect to the segment 7. Therefore, even if the green tire 6 set in the mold is displaced from the normal position, the sector 8 changes its position along the tread portion of the green tire 6.

  When the holster plate 18 is further lowered and the segment 7 is moved in the inner diameter direction, the elastic force acting on the sector 8 by each elastic support gradually increases. Thereby, even if the green tire 6 is set out of the normal position, the position shift is corrected. And finally, as shown in FIG. 1, the segment 7 and the sector 8 which were divided | segmented are connected cyclically | annularly, and the green tire 6 will be in the state which can be vulcanized-molded in a regular position. For this reason, unlike the prior art, a so-called rubber bite in which a part of the green tire 6 is sandwiched between molds does not occur.

  The green tire 6 corrected in the normal position in this way is vulcanized and molded into a tire by inflating the bladder 5 and heating it. As a result, the occurrence of defects (rubber biting) between the obtained tires and tires obtained with other molds was verified. The verification results are shown in Table 1 below. In Table 1, regarding the occurrence of defects (rubber biting), out of 100 vulcanizations, “Yes” is indicated when a defective tire is generated, and “No” when no defective tire is generated.

In Comparative Example 1, only the horizontal elastic support 17 that biases the outer peripheral surface of the sector 8 is provided.
In Comparative Example 2, only the upper and lower elastic supports that urge the upper and lower surfaces of the sector 8 were provided. In this case, the spring constants of the first elastic support 12 and the second elastic support 13 were the same.
In Example 1, both the horizontal elastic support 17 and the vertical elastic support were provided. In this case, the spring constants of the first elastic support 12 and the second elastic support 13 were the same.
In Example 2, both the horizontal elastic support member 17 and the vertical elastic support member were provided. In this case, the spring constant of the first elastic support 12 was made larger than that of the second elastic support 13.
In Example 3, both the horizontal elastic support 17 and the vertical elastic support were provided. In this case, the spring constant of the second elastic support 13 was made larger than that of the first elastic support 12.

  As is apparent from Table 1, by providing both the horizontal elastic support 17 and the upper and lower elastic supports, it was possible to eliminate the occurrence of tire defects (rubber biting). Further, when the spring constant of the first elastic support 12 is increased, even the tire molding mold 1 of a type in which the pressure applied by the first mold 2 during vulcanization molding is large can be made difficult to deform. It is valid. Further, when the spring constant of the second elastic support 13 is increased, it is preferable in that the support state can be stabilized even if the weight of the sector 8 is large.

  In addition, this invention is not limited to the structure described in the said embodiment, A various change is possible.

  In the said embodiment, although the elastic support body was comprised with the coil spring and the spherical body, not only this but a various structure is employable. For example, the elastic support may be formed of a synthetic resin material as a whole, a leaf spring, or the like. It is also possible to adopt a form using air pressure or oil pressure instead of the elastic support.

  In the embodiment, the first mold 2 is contacted and separated from the upper side with respect to the second mold 3 arranged on the lower side, but the second mold 3 is moved downward with respect to the first mold 2. You may make it make it contact / separate from the side, or may make both molds contact / separate each other so that raising / lowering is possible.

  In the above embodiment, both the first elastic support 12 and the second elastic support 13 are provided as the upper and lower elastic supports. However, only the second elastic support 13 is provided. Is also possible.

DESCRIPTION OF SYMBOLS 1 ... Mold for tire molding 2 ... 1st metal mold 3 ... 2nd metal mold 4 ... 3rd metal mold 5 ... Bladder 6 ... Green tire 7 ... Segment 8 ... Sector 9 ... Upper guide wall part 10 ... Lower guide wall part DESCRIPTION OF SYMBOLS 11 ... Guide recessed part 12 ... 1st elastic support body 13 ... 2nd elastic support body 14 ... Guide groove 15 ... Guide pin 16 ... Communication hole 17 ... Horizontal elastic support body 18 ... Holster plate 19 ... Pressure ring 20 ... Molding recessed part 21 ... Groove part 22 ... Rid 23

Claims (6)

A first mold and a second mold that are relatively movable along the axial direction of the green tire and can be press-contacted to the respective side portions of the green tire;
A third mold that is movable in the radial direction of the green tire and that can be pressed against the tread portion of the green tire;
With
The third mold is
A plurality of segments divided in the circumferential direction and movable in the radial direction of the green tire;
For each of the segments, a sector that is elastically supported so as to be movable in the axial direction and the radial direction of the green tire and can be pressed against the tread portion of the green tire ,
Equipped with a,
It said segments, a tire mold, characterized in der Rukoto intended to correct the position of the green tire while moving the sectors in the axial direction and the radial direction of the green tire. The segment has a recess extending in the circumferential direction of the green tire on the inner peripheral surface,
2. The tire molding die according to claim 1, wherein the sector includes a convex portion that is guided in the concave portion while limiting a movement range in an axial center direction and a radial direction of the green tire. Each mold is installed so that the radial direction of the green tire set in the mold coincides with the horizontal direction,
The tire molding die according to claim 1 or 2, further comprising an upper and lower elastic support body that elastically supports at least a lower surface of the sector with respect to the segment. The upper and lower elastic supports include a first elastic support that supports the upper surface of the sector and a second elastic support that supports the lower surface,
The tire molding die according to claim 3, wherein spring constants of the first elastic support and the second elastic support are different.   The tire molding die according to claim 3, further comprising a horizontal elastic support body that elastically supports an outer peripheral surface of the sector with respect to the segment. In the tire molding die according to any one of claims 1 to 5,
Mold clamping,
A first step of pressure-contacting the first mold and the second mold to both side portions of the green tire;
A second step of bringing the sector of the third mold into contact with the tread portion of the green tire;
A third step of correcting the position of the green tire while moving the sector in the axial direction and the radial direction of the green tire by the segment;
A fourth step of pressing the sector against the tread portion;
The tire molding method characterized by performing by.

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