JP2012135897A - Tire vulcanizing mold, and method for manufacturing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of aesthetic appearance of a tire while suppressing molding defects such as bares.SOLUTION: This tire vulcanizing mold 11 includes: a tread mold 12 having a tread molding surface 12s capable of molding an outer surface of a tread part 2 of the tire 1; a pair of bead rings 13 having bead molding surfaces 13s capable of molding outer surfaces of bead parts 4 of the tire 1; and a pair of side molds 14 extending in the tire radial direction in side regions Ts between the tread molding surface 12s and the bead molding surfaces 13s and having side molding surfaces 14s capable of molding side surfaces 1s of the tire 1. The side molds 14 are in a ring shape in which a plurality of side segments 21 divided in the tire circumferential direction are connected to each other in the tire circumferential direction. In the side molding surfaces 14s, a plurality of radial direction dividing surfaces 22, extending in the tire radial direction, that are mating surfaces of the side segments 21. The radial direction dividing surfaces 22 discharge the air between the tire 1 and the side molds 14.

Description

  The present invention relates to a tire vulcanization mold and a method for manufacturing a pneumatic tire that can suppress deterioration in the appearance of a tire while suppressing molding defects such as bears.

  Conventionally, in a vulcanization process of vulcanizing and molding a raw tire, it is known that air is trapped between the tire and a mold, thereby causing a molding defect such as a bear (dent) on the outer surface of the tire. . Such a molding defect tends to occur on the side surface of a tire including a sidewall portion having a relatively small rubber volume.

  In order to effectively prevent such molding defects, a method is known in which a plurality of vent holes are provided in a side mold that can mold the side surface of a tire and air is discharged.

  However, such a method has a problem that a part of the rubber is sucked up into the vent hole and a plurality of spews are formed on the side surface of the tire, and the appearance of the tire is remarkably impaired.

  Therefore, as shown in FIG. 10, by using a side molding die a composed of a plurality of segments b divided in the tire radial direction, the air is discharged from a long small gap c composed of the mating surfaces of the segments. A method has been proposed.

JP 2002-326227 A

  However, in the side molding die a as described above, since the small gap c is formed in a long and continuous shape in the tire circumferential direction, exhaust is not uniform in the tire radial direction, and molding defects such as bears occur. There was a problem that it was easy. In order to prevent the occurrence of molding defects such as bears, it may be possible to provide a vent hole, but there is a problem that spew is formed and the appearance of the tire is remarkably impaired.

  The present invention has been devised in view of the actual situation as described above, and forms a ring-shaped side molding die by connecting a plurality of side segments divided in the tire circumferential direction in the tire circumferential direction. Basically, multiple radial split surfaces extending in the tire radial direction are formed on the side molding surface of the mold by the mating surfaces of the side segments, and air is discharged from between the tire and the side mold from the radial split surface. The main object of the present invention is to provide a tire vulcanization mold and a method for manufacturing a pneumatic tire that can suppress the deterioration of the appearance of the tire while suppressing molding defects such as bears.

  The invention according to claim 1 of the present invention is a tire vulcanization mold for vulcanizing and molding a tire, the tread mold having a tread molding surface capable of molding the outer surface of the tread portion of the tire, and the tire A pair of bead rings having a bead molding surface capable of molding the outer surface of the bead portion, and a side molding in which a side region between the tread molding surface and the bead molding surface extends in a tire radial direction and a side surface of the tire can be molded. A pair of side molding dies having a surface, the side molding dies form a ring shape by connecting a plurality of side segments divided in the tire circumferential direction in the tire circumferential direction, and the side molding surface includes: A plurality of radial split surfaces extending in the tire radial direction are formed by the mating surfaces of the side segments, and the tire and the side mold are formed from the radial split surfaces. Characterized by discharging the air between.

  The invention according to claim 2 is the tire vulcanization mold according to claim 1, wherein each of the side molds comprises 4 to 100 side segments.

  The invention according to claim 3 is the tire vulcanization mold according to claim 1 or 2, wherein each side molding surface extends in the tire radial direction without being interrupted by the side region.

  According to a fourth aspect of the present invention, each side segment is formed by overlapping a plurality of ring pieces divided in the tire radial direction in the tire radial direction so that the side molding surface is divided in the radial direction. The tire vulcanization mold according to any one of claims 1 to 3, comprising a surface portion and a circumferentially divided surface portion extending in a tire circumferential direction, wherein the circumferentially divided surface portion discharges the air together with the radially divided surface portion. It is.

  Further, the invention according to claim 5 is the tire vulcanization mold according to claim 4, wherein the radial direction split surface portion is arranged in a staggered manner through the circumferential direction split surface portion.

  The invention according to claim 6 is the tire vulcanization mold according to any one of claims 1 to 5, wherein each of the split surface portions is a small gap of 0.01 to 0.05 mm.

  In addition, the invention according to claim 7 uses the molding step of molding a green cover having side rubber disposed on the side portion of the tire, and the tire vulcanization mold according to any one of claims 1 to 6. And a vulcanization step of vulcanizing and molding a raw cover, wherein the molding step forms a side rubber by spirally winding a ribbon-like unvulcanized rubber strip in the tire circumferential direction. The vulcanizing step is a method for producing a pneumatic tire, characterized in that the radially split surface portion is arranged and vulcanized in a direction crossing the longitudinal direction of the rubber strip.

  The tire vulcanization mold of the present invention includes a tread mold having a tread molding surface capable of molding the outer surface of the tread portion of the tire, and a pair of bead rings having a bead molding surface capable of molding the outer surface of the bead portion of the tire. And a pair of side molds having a side molding surface that can mold a side surface of the tire by extending a side region between the tread molding surface and the bead molding surface in the tire radial direction.

  The side mold has a ring shape by connecting a plurality of side segments divided in the tire circumferential direction in the tire circumferential direction. Further, a plurality of radial split surfaces extending in the tire radial direction are formed on the side molding surfaces by the mating surfaces of the side segments, and air between the tire and the side mold is discharged from the radial split surfaces.

  In such a tire vulcanization mold, a plurality of radially split surfaces are provided in the tire circumferential direction and extend in the tire radial direction. Therefore, the air between the tire and the side mold is removed from the tire radial direction and the tire circumference. It is possible to discharge uniformly in the direction. Thereby, since the tire tire vulcanization mold can effectively exhaust air without providing a vent hole, it is possible to suppress deterioration in the appearance of the tire while suppressing molding defects such as bears.

It is sectional drawing of the pneumatic tire obtained by the manufacturing method of this embodiment. It is sectional drawing of a tire vulcanization metal mold | die. It is a fragmentary perspective view which shows the raw cover of FIG. It is a perspective view of a rubber strip. It is a side view of a side mold. It is the elements on larger scale of FIG. It is a side view which shows a side shaping | molding die and a rubber strip. It is a side view which shows the side shaping | molding die of other embodiment. It is the elements on larger scale of FIG. It is a side view of the conventional side mold.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 obtained by the tire vulcanization mold and the pneumatic tire manufacturing method of the present embodiment is formed from a tread portion 2. A case of a radial tire for a passenger car including a toroid-like carcass 6 that reaches the bead core 5 of the bead portion 4 through the sidewall portion 3 and a belt layer 7 that is disposed radially outward of the carcass 6 is shown. ing.

  The carcass 6 includes a main body portion 6 a that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a folded portion 6 b that is connected to the main body portion 6 a and wound up around the bead core 5. It is formed from at least one carcass ply 6A. Further, a bead apex 8 extending from the bead core 5 to the outer side in the tire radial direction is disposed between the main body portion 6a and the folded portion 6b of the carcass ply 6A, and the bead portion 4 is appropriately reinforced.

  The belt layer 7 is formed of two belt plies 7A and 7B in which belt cords made of, for example, steel are arranged at an angle of, for example, 10 to 35 degrees with respect to the tire equator C. As the belt cord, a steel cord, or a highly elastic organic fiber cord such as aramid or rayon is appropriately employed.

  Further, the tire 1 includes a tread rubber 2G disposed on the outer side of the belt layer 7, a side rubber 3G disposed on the outer side in the tire axial direction of the carcass 6 in the sidewall portion 3 forming the side surface 1s of the tire 1, and a carcass 6 An inner liner rubber 9G made of air impermeable rubber disposed on the inner side, a clinch rubber 4G that is disposed on the outer side in the tire axial direction of the carcass 6 in the bead portion 4 and has excellent wear resistance that can contact a rim (not shown); And a bead chafer 10 made of hard rubber disposed on the inner side in the tire axial direction of the clinch rubber 4G.

  The tire 1 of the present embodiment has a so-called TOS (tread over sidewall) structure in which the outer end portion 3Go in the radial direction of the side rubber 3G is covered with the outer end portion 2Go in the tire axial direction of the tread rubber 2G. The case where it is is illustrated.

FIG. 2 shows a cross-sectional view of a tire vulcanization mold 11 used in the method for manufacturing the tire 1.
In the manufacturing method of the tire 1 of the present embodiment, a forming step of forming the green cover 1M having the side rubber 3G disposed on the side portion of the tire 1, and the raw cover 1M are vulcanized using the tire vulcanization mold 11. And a vulcanization step of molding.

  In the molding step, the raw cover 1M is molded using a molding drum (not shown) according to the custom. As shown in FIG. 3, the raw cover 1M includes a tread rubber 2G, a side rubber 3G, a clinch rubber 4G, a bead core 5, a carcass ply 6A, a belt layer 7, a bead apex 8, an inner liner rubber 9G, and a bead chafer rubber 10G. It is formed in a toroidal shape.

  Further, in the molding process of the present embodiment, as shown in FIGS. 3 and 4, a ribbon-like unshaped ribbon having a thickness t of 0.8 to 3.0 mm and a width W1 of about 5.0 to 30.0 mm. A step of forming a side rubber 3G by winding a vulcanized rubber strip S spirally in the tire circumferential direction is included. In the present embodiment, the clinch rubber 4G is formed by winding the rubber strip S together with the side rubber 3G.

  In the present specification, “unvulcanized” means all embodiments that have not reached complete vulcanization. Accordingly, the rubber member partially or partially vulcanized is included in the concept of “unvulcanized”.

  Such a side rubber 3G eliminates the splice portion (seam) formed in the conventional integrally-extruded side rubber, thereby improving the uniformity of the tire and helping to form them with high precision. At the time of this step, a plurality of irregularities 16 extending in the tire circumferential direction are formed on the outer surface of the side rubber 3G.

  In the vulcanization step, as shown in FIG. 2, the raw cover 1M is vulcanized using a tire vulcanization mold 11 having a cavity 11s that forms the outer surface of the raw cover 1M. The tire vulcanization mold 11 according to the present embodiment includes a pair of tread molding die 12 having a tread molding surface 12s that can mold the outer surface of the tread portion 2 and a bead molding surface 13s that can mold the outer surface of the bead portion 4. A pair of bead rings 13 (only one side is shown) and a side molding surface 14 s that extends in the tire radial direction of a side region Ts between the tread molding surface 12 s and the bead molding surface 13 s and can mold the side surface 1 s of the tire 1. It includes a side mold 14 (only one side is shown).

  In the tire vulcanization mold 11, the tread molding die 12, the bead ring 13, and the side molding die 14 are fitted together, whereby the tread molding surface 12s, the bead molding surface 13s, and the side molding surface 14s are smoothly connected. A cavity 11s is formed. The raw cover 1M disposed in the cavity 11s is vulcanized and pressed against the cavity 11s by the expansion of the bladder 18 to which a high-pressure fluid is supplied in accordance with the conventional practice.

  FIG. 5 shows a side view of the side molding die 14 of the present embodiment as viewed from the side molding surface 14s side. The side molding die 14 of the present embodiment is formed in a ring shape by connecting a plurality of side segments 21 that are equally divided in the tire circumferential direction and have a substantially fan shape in a side view in the tire circumferential direction.

  As shown in FIG. 6 in an enlarged manner, the side molding die 14 of the present embodiment includes a side segment group 21G formed by connecting a plurality of (two in this embodiment) side segments 21 in the tire circumferential direction. It is formed by connecting. The side segment group 21G is connected by a screw shaft 25 that is inserted into each side segment 21 and nuts 26 and 26 that are screwed to both ends thereof.

  The side molding surface 14 s has a plurality of radially split surface portions 22 formed by small gaps extending in the tire radial direction from the outer end 14 o to the inner end 14 i of the side molding die 14 by the mating surfaces of the side segments 21, 21. Is formed. By connecting a vacuum device (not shown) or the like to the radial direction split surface portion 22, air can be sucked from the side molding surface 14 s side.

  As shown in FIGS. 2 and 5, the side molding die 14 configured as described above is pressed against the side rubber 3 </ b> G in the vulcanization process, and the side surface 1 s of the tire 1 and the side surface from the radially split surface portion 22. The air interposed between the molds 14 is discharged. Thereby, the side shaping | molding die 14 can suppress that molding defects, such as a bear (dent part), arise in the side surface 1s of the tire 1. FIG.

  Further, since the radial split surface portion 22 is formed extending from the outer end 14o to the inner end 14i in the tire radial direction and provided in the tire circumferential direction, air is exhausted in the tire radial direction and the tire circumferential direction. Becomes uniform. Thereby, since the side shaping | molding die 14 can discharge | emit air, without providing a vent hole, it can prevent that a spew is formed in the side surface 1s, and can suppress that the beauty | look of a tire falls.

  If the number of the side segments 21 of the side mold 14 is small, the air exhaust cannot be made sufficiently uniform, and molding defects such as bears may not be sufficiently suppressed. On the contrary, if the number of the side segments 21 is large, it takes time to connect the side segments 21 and the workability may be reduced. From such a viewpoint, the number of the side segments 21 is preferably 4 or more, more preferably 8 or more, still more preferably 16 or more, and preferably 100 or less, more preferably 70 or less. More preferably, 40 or less is desirable.

  Further, the length (not shown) of the gap in the radial direction split surface portion 22 can be set as appropriate. However, if the length is reduced, the air interposed between the tire 1 and the side mold 14 cannot be sufficiently discharged. There is a fear. On the other hand, when the length is increased, a part of the rubber enters the radially split surface portion 22, and there is a risk that spew or burrs may be formed on the side surface 1 s of the tire 1. From such a viewpoint, the length is preferably 0.01 mm or more, more preferably 0.02 mm or more, and preferably 0.20 mm or less, more preferably 0.10 mm or less.

  Further, when the side rubber 3G is formed by winding the rubber strip S in the tire circumferential direction as in the present embodiment, as shown in FIG. The rubber strips S are arranged in a direction substantially perpendicular to the longitudinal direction of the rubber strip S indicated by a broken line. Thereby, the radial direction split surface part 22 can discharge | emit the air which remains in the unevenness | corrugation 16 (shown in FIG. 3) of the side rubber 3G reliably, and can prevent defects, such as a bear, reliably.

  As shown in FIG. 2, when the tire 1 has a TOS structure, the outer end 14o of the side molding die 14 is the same as the outer end 2Go of the tread rubber 2G, or is arranged on the outer side in the tire radial direction. Is preferred. Furthermore, it is preferable that the inner end 14i of the side molding die 14 is disposed on the same side as the inner end 3Gi of the side rubber 3G or on the inner side in the tire radial direction. Thereby, the side shaping | molding die 14 can shape | mold the side rubber 3G over the whole region, and can discharge | emit the air which remains on the unevenness | corrugation 16 (shown in FIG. 3) of the side rubber 3G more reliably.

  Furthermore, each side molding surface 14s is preferably formed extending in the tire radial direction without being interrupted by the side region Ts. Such side molding surface 14s is useful for smoothly and accurately forming the side surface 1s of the tire 1 in the tire radial direction.

FIG. 8 shows a side mold 14 according to another embodiment of the present invention.
In the side molding die 14 of this embodiment, the side segment 21 is formed by overlapping a plurality of ring pieces 23 divided in the tire radial direction in the tire radial direction. Accordingly, the side molding surface 14s is formed by the radial split surface portion 22 and the circumferential split surface portion 24 extending in the tire circumferential direction by the mating surfaces in the tire radial direction of the ring pieces 23 and 23 adjacent in the tire radial direction. Is done. In the circumferential direction split surface portion 24, the air intervening between the tire 1 and the side mold 14 is discharged as in the radial direction split surface portion 22.

  The ring piece 23 of the present embodiment is arranged in a zigzag shape (substantially horseshoe-like shape) in a side view, and as shown in an enlarged view in FIG. 9, the screw shaft 25 inserted in the tire radial direction and both ends thereof The nuts 26 and 26 are screwed together. Thereby, the circumferential direction split surface portion 24 extends continuously in the tire circumferential direction, and the radial direction split surface portion 22 is arranged in a staggered manner via the circumferential direction split surface portion 24.

  Since such a circumferentially divided surface portion 24 and a radially divided surface portion 22 can uniformly exhaust the air between the tire 1 and the side molding die 14 in the tire radial direction and the tire circumferential direction, molding defects such as bears are caused. Can be effectively suppressed. Moreover, since the radial split surface portions 22 are arranged in a staggered manner via the circumferential split surface portions 24, the generation of bears can be more reliably suppressed.

  Note that if the number of the ring pieces 23 of the side segment 21 is too small, there is a possibility that the above-described effects cannot be sufficiently exhibited. Conversely, even if the number of ring pieces 23 is too large, it may take time to connect the ring pieces 23. From such a viewpoint, the number of the ring pieces 23 is preferably 16 or more, more preferably 24 or more, and preferably 96 or less, more preferably 48 or less.

  Further, it is desirable that the length (not shown) of the gap in the circumferential direction split surface portion 24 be formed in the same range as the radial direction split surface portion 22.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

Tires vulcanized and molded with a tire vulcanizing mold having the basic structure of FIG. 1 and having side molds specified in Table 1 were manufactured and their performance was tested. Further, as a comparison, a tire (Comparative Example 1) vulcanized with a tire vulcanization mold having a conventional side mold having a plurality of vent holes, and a tire continuous in the tire circumferential direction shown in FIG. A tire (Comparative Example 2) vulcanized with a tire vulcanization mold having a side mold having a gap was also tested in the same manner.
The common specifications are as follows.
Tire size: 215/45 R17
Rubber strip thickness t: 1.0 mm
Rubber strip width W1: 23mm
The test method is as follows.

<Assembly workability of side mold>
The work time A1 required to assemble each test side mold was measured, and the ratio (A1 / A2) to the work time A2 required to assemble the conventional side mold shown in Comparative Example 1 was determined. The evaluation is as follows.
○: Ratio (A1 / A2) <1.2
Δ: 1.2 ≦ ratio (A1 / A2) ≦ 2.0
X: Ratio (A1 / A2)> 2.0

<Number of bears generated>
1000 tires were vulcanized using a tire vulcanization mold having each test side mold, and the number of tires in which bears occurred on the side surfaces of the tires was counted.

<Tire aesthetics>
The tire was vulcanized using a tire vulcanization mold having each test side mold, and the presence or absence of spew on the side surface of the tire was visually confirmed. The evaluation is as follows.
○: There is no spew and the tire has an excellent aesthetic appearance.
(Triangle | delta): A spew is partially formed and it is a little inferior to the aesthetics of a tire.
X: A plurality of spews are formed, and the appearance of the tire is inferior.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the tire molded with the tire vulcanization mold having the side molding die of the example can improve the appearance of the tire while suppressing molding defects such as bears.

11 Tire vulcanization mold 12 Tread mold 13 Bead ring 14 Side mold 14s Side molding surface 21 Side segment 22 Radial split surface

Claims (7)

A tire vulcanization mold for vulcanizing a tire,
A tread mold having a tread molding surface capable of molding the outer surface of the tread portion of the tire;
A pair of bead rings having a bead molding surface capable of molding the outer surface of the bead portion of the tire;
A pair of side molding dies having side molding surfaces that can mold the side surfaces of the tire by extending a side region between the tread molding surface and the bead molding surface in the tire radial direction;
The side molding die has a ring shape by connecting a plurality of side segments divided in the tire circumferential direction in the tire circumferential direction,
A plurality of radially split surfaces extending in the tire radial direction are formed on the side molding surface by the mating surfaces of the side segments,
A tire vulcanization mold, wherein air between the tire and a side mold is discharged from the radially split surface portion.   The tire vulcanization mold according to claim 1, wherein each side mold includes 4 to 100 side segments.   The tire vulcanization mold according to claim 1, wherein each side molding surface extends in a tire radial direction without interrupting the side region. Each side segment is formed by overlapping a plurality of ring pieces divided in the tire radial direction in the tire radial direction, so that the side molding surface has a circumferential direction extending in the radial direction split surface portion and the tire circumferential direction. Including a split surface portion,
The tire vulcanization mold according to any one of claims 1 to 3, wherein the circumferential direction split surface portion discharges the air together with the radial direction split surface portion.   The tire vulcanization mold according to claim 4, wherein the radial direction split surface portions are arranged in a staggered manner via the circumferential direction split surface portions.   The tire vulcanization mold according to any one of claims 1 to 5, wherein each of the split surface portions includes a small gap of 0.01 to 0.05 mm. A molding process for molding a green cover having side rubber disposed on a side portion of a tire, and a vulcanization process for vulcanizing and molding the green cover using the tire vulcanization mold according to any one of claims 1 to 6. A method of manufacturing a tire including:
The forming step includes a step of forming the side rubber by spirally winding a ribbon-like unvulcanized rubber strip in the tire circumferential direction,
The said vulcanization | cure process distributes the said radial direction split surface part in the direction which cross | intersects the longitudinal direction of the said rubber strip, and vulcanizes it, The manufacturing method of the pneumatic tire characterized by the above-mentioned.

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