JP4788252B2 - Manufacturing method of rigid core for tire vulcanization molding and pneumatic tire - Google Patents

Description

  The present invention relates to a method of manufacturing a rigid core for tire vulcanization molding and a pneumatic tire, and more specifically, for tire vulcanization molding capable of improving molding accuracy and quality accuracy at the time of vulcanization molding of a tire. The present invention relates to a method for manufacturing a rigid core and a pneumatic tire.

  Conventionally, in order to improve uniformity at the time of tire vulcanization molding, instead of the conventionally used bladder, as shown in FIG. 8, the medium-rigidity formed to correspond to the inner surface of the hollow portion of the unvulcanized tire W There has been proposed a tire manufacturing method in which a tire 1 is vulcanized and molded using the child 1 as an inner mold (see, for example, Patent Document 1).

  The rigid core 1 as described above is made of a metal material such as an aluminum alloy, and is divided into a plurality of pieces in the circumferential direction so as to be expandable / contractable in the radial direction as shown in FIG. The segment 2a, 2b is divided but not limited to the number of divisions, and the segments 2a, 2b are fitted to each other on the inclined fitting surface 2x, and the segments 2a, 2b Are sequentially expanded in the radial direction so that the diameter can be increased or decreased. Further, in the tire vulcanization molding process, the segments 2a and 2b, the upper and lower molds 3a and 3b, and the sector mold 4 divided in the circumferential direction are configured so as to maintain the shape of the inner and outer surfaces of the unvulcanized tire W. is doing.

By the way, the conventional rigid core 1 for tire vulcanization molding as described above has the same outer peripheral surface shape as the inner peripheral surface shape of the product tire. When vulcanization molding of unvulcanized tire W is used, it is difficult to adjust the volume due to expansion and contraction during vulcanization molding, and light failure (indentation of the inner surface due to air accumulation) occurs in the tire bead and shoulder. There was a problem that it was easy.
Japanese Patent Application No. 2000-141380

  The present invention pays attention to such conventional problems, can easily adjust the volume during vulcanization molding, can suppress light failure, and improve the molding accuracy and quality accuracy during vulcanization molding of tires. An object of the present invention is to provide a rigid core for tire vulcanization molding and a method for producing a pneumatic tire.

In order to achieve the above object, the rigid core for tire vulcanization molding according to the present invention has an inner volume when molding the hollow cylindrical core body as A and an inner volume during vulcanization molding as B. In this case, the inner volume A at the time of molding the core body is configured to be increased and deformed to the inner volume B at the time of vulcanization molding, and the ratio of the increased deformation is set in the range of 0.1% to 5%. The gist of the invention is that the core body is divided in the tire width direction or the tire radial direction, and a deformed connecting member is provided at the divided portion so that the inner volume A can be increased to the inner volume B.

Here, the deformable connecting member, is a more structure to the rubber-like elastic body or bending deformation member.

  Further, the rate of change of the inner volume Va above the position where the tire width of the hollow cylindrical core body is the widest is set smaller than the rate of change of the inner volume Vb below it.

  Further, the method for producing a pneumatic tire according to the present invention provides an inner surface configuration of an unvulcanized tire by a rigid core for tire vulcanization molding as described above when an vulcanized tire is vulcanized in the tire vulcanization molding step. The gist is to vulcanize and mold the tire while holding the tire.

Since the present invention is configured as described above, the following excellent effects can be obtained. (a). Since the force to press the unvulcanized tire against the mold is applied, the volume can be adjusted easily during vulcanization molding, so light failure can be suppressed at the tire bead and shoulder. .
(b) Even if the volume during tire vulcanization molding varies somewhat, it becomes difficult for light failure to occur. (c) It is possible to improve molding accuracy and quality accuracy at the time of vulcanization molding of a tire. (d) After the tire vulcanization molding, the rigid core can be easily taken out from the molded tire.
(e) A tire with few light failures can be manufactured.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the same components as those in the conventional example are denoted by the same reference numerals and description thereof is omitted.

  FIG. 1 is a perspective view of a rigid core for tire vulcanization molding according to the present invention, and FIG. 2 is a partially enlarged cross-sectional view taken along the line AA of FIG. The main body 11 is made of a metal material such as an aluminum alloy. The core main body 11 is divided into a plurality of types (in this embodiment, eight divisions, but not limited to the number of divisions) in the circumferential direction. The segments 12a and 12b are configured to be arranged annularly so as to be expandable / contractable in the radial direction, and the core body 11 is configured to maintain the inner surface form of the unvulcanized tire W in the tire vulcanization molding process. It is.

  In this embodiment, when the inner volume during molding of the hollow cylindrical core body 11 is A and the inner volume during vulcanization molding is B, the core body 11 is molded (before vulcanization: FIG. The internal volume A (shown by a solid line in FIG. 2) is configured to be increased and deformed (shown by a two-dot chain line in FIG. 2) to the internal volume B at the time of vulcanization molding. % To 5%, preferably 1 to 3%, more preferably 1.5 to 2.5%.

  If the ratio of the increased deformation is 0.1% or less, there is no effect in reducing the light failure of the tire to be molded, and if it is 5% or more, the amount of deformation is large and the uniformity (uniformity) of the tire is deteriorated. To do.

Specifically, as shown in FIG. 2, the core body 11 is divided in the tire width direction or the tire radial direction, and the deformed connection member capable of increasing the inner volume A to the inner volume B in the divided portion K. 13 is provided. In addition, although the division | segmentation part K is one place in this embodiment, it is also possible to provide in several places, and to provide the deformation | transformation connection member 13 in this division part K of several places.

  3-6 is concrete embodiment of the deformation | transformation connection member 13, Comprising: In embodiment of FIG. 3, the division part K is provided in the side part of the core main body 11 corresponding to a tire side part, and this division | segmentation is carried out. The portion K is provided with a deformable connecting member 13a made of a rubber-like elastic body such as rubber or resin.

  2, 3, and 5, the two-dot chain line of the core body 11 indicates a state of expansion and deformation during vulcanization molding.

  In the embodiment shown in FIG. 4, it is also possible to provide a bending deformation member 14 such as a hinge as the deformation connection member 13 provided in the divided portion K. Further, as an embodiment shown in FIG. 6, as the bending deformation member 14, a part 15 of the side part of the core body 11 is thin (for example, 1/2 or less with respect to the thickness of other parts, preferably 1 / 10 or less) to form the bending deformation member 14a. The change in thickness is not particularly limited as long as it is a thickness that can be deformed during vulcanization molding.

  Further, as shown in FIG. 5, the divided portion K is provided in the tread portion 16 of the core body 11 corresponding to the tire tread portion, and the divided portion K of the tread portion 16 has rubber, resin, etc. as described above. It is also possible to provide a deformation connecting member 13a made of a rubber-like elastic body, a bending deformation member 14 such as a hinge, or a thin bending deformation member 14a.

  Furthermore, as another embodiment, as shown in FIG. 7, the rate of change of the internal volume Va above the position XX where the tire width of the hollow cylindrical core body 11 is the widest is lower than that. It is also possible to set it smaller than the rate of change of the internal volume Vb.

  Specifically, the thickness of the core body 11 below the position XX having the widest tire width is formed thinner than the position XX having the widest tire width, and the rate of change of the internal volume Vb. Can be configured to be larger than the rate of change of the internal volume Va.

Moreover, as said embodiment, the core main body 11 is divided | segmented into a tire width direction or a tire radial direction, and the deformation | transformation connection member 13 which can increasely deform the internal volume A to the internal volume B is provided in this division part K. However, during the vulcanization molding in which the core body 11 expands, there is a possibility that burrs may occur on the inner wall surface of the molded tire due to the formation of fine gaps between the segments. However, since the size (thickness and height) of the burr is small and can be formed on the inner surface of the tire, the appearance and performance of the tire are not affected at all.

  In order to reduce the amount of burrs generated during vulcanization, the amount of burrs can be reduced by forming the fitting surfaces 12x of the segments 12a and 12b on inclined surfaces. The diameter can be increased or decreased by sequentially moving 12b in the radial direction.

  By configuring the rigid core for tire vulcanization molding as described above, the force to press-bond the unvulcanized tire W to the mold can be added, and volume adjustment during vulcanization molding can be easily performed. Light failure can be suppressed in the tire bead portion and shoulder portion, and even if the volume during tire vulcanization molding varies somewhat, light failure is less likely to occur.

  Thereby, it becomes possible to improve the molding accuracy and quality accuracy at the time of vulcanization molding of the tire, and the core body 11 can be easily taken out from the molded tire after the tire vulcanization molding.

  Furthermore, a tire manufactured using such a rigid core for tire vulcanization molding has good uniformity and can manufacture a tire with little light failure.

It is a perspective view of the rigid core for tire vulcanization molding which implemented this invention. FIG. 2 is a partially enlarged cross-sectional view taken along line AA in FIG. 1. It is a partially expanded sectional view of embodiment which divided | segmented a part of side part of the core main body, and provided the deformation | transformation connection member in this division | segmentation part. It is a partial expanded sectional view of the Z section of Drawing 3 showing other embodiments of a deformation connection member. It is a partially expanded sectional view of other embodiment which divided | segmented a part of tread part of the core main body, and provided the deformation | transformation connection member in this division | segmentation part. It is a partially expanded sectional view of other embodiment which formed a part of side part of the core main body thinly. It is a partially expanded sectional view of other embodiment of a core main body. It is a partially expanded sectional view at the time of performing vulcanization molding using the conventional rigid core. It is a top view of the conventional rigid core.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rigid core 2a, 2b Segment 2x Mating surface 3a, 3b Upper and lower die 4 Sector mold W Unvulcanized tire 11 Core main body 12a, 12b Segment 13, 13a Deformation connection member 14, 14a Bending deformation member 15 Side part Part 16 Tread part K Split part XX Position with the widest tire width

Claims (5)

A plurality of segments divided in the circumferential direction constituting the hollow cylindrical core body are arranged in an annular shape so as to be expandable and contractable in the radial direction, and the inner surface form of the unvulcanized tire is maintained in the tire vulcanization molding process. In the rigid core for tire vulcanization molding,
When the inner volume at the time of molding the hollow cylindrical core body is A and the inner volume at the time of vulcanization molding is B, the inner volume A at the time of molding the core body is the inner volume B at the time of vulcanization molding. The ratio of the increased deformation is set in a range of 0.1% to 5%, the core body is divided in the tire width direction or the tire radial direction, A rigid core for tire vulcanization molding, characterized in that a deformable connecting member capable of increasing deformation of the inner volume A to the inner volume B is provided.   The rigid core for tire vulcanization molding according to claim 1, wherein the deformable connecting member is a rubber-like elastic body.   The rigid core for tire vulcanization molding according to claim 1, wherein the deformation connecting member is a bending deformation member.   The change rate of the internal volume Va above the position where the tire width of the hollow cylindrical core body is the widest is set to be smaller than the change rate of the internal volume Vb below it. Rigid core for tire vulcanization molding.   When an unvulcanized tire is vulcanized and molded in the tire vulcanization molding process, the inner surface form of the unvulcanized tire is retained by the rigid core for tire vulcanization molding according to any one of claims 1 to 4. A method of manufacturing a pneumatic tire that is vulcanized and molded.

Images