JP5113861B2 - Pneumatic tire manufacturing method and rigid core used therefor - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire in which the tire axial width of the rigid core can be adjusted according to the size of the pneumatic tire to be manufactured, and a rigid core used therefor.

  In recent years, in order to improve the formation accuracy of the tire and reduce the residual strain in the tire, as shown in FIG. 12 (A), using a rigid core a that matches the shape of the tire lumen surface of the vulcanized tire, On this rigid core a, an unvulcanized tire constituent member such as an inner liner, a carcass ply, a belt ply, a sidewall rubber, and a tread rubber is sequentially attached to form a raw tire t. Is introduced into the vulcanization mold b together with the rigid core a, and the tire is vulcanized and molded between the rigid core a as the inner mold and the vulcanization mold b as the outer mold. (For example, refer to Patent Document 1).

  As shown in FIG. 12B, the rigid core a is formed of a plurality of core segments c that are divided in the tire circumferential direction so as to be disassembled and removed from the tire after vulcanization molding.

  However, as shown in FIG. 12 (A), the core segment c is not divided in the tire axial direction, and the core segment c is formed as an integral part having an outer surface shape matching the tire cavity surface. That is, for each size of the pneumatic tire, a core segment c (rigid core a) corresponding to the size exists.

  For this reason, the types of the core segment c (rigid core a) are remarkably increased, resulting in problems such as a decrease in storage management efficiency, an increase in storage space, and an increase in manufacturing cost of the core segment c.

JP 2007-253415 A

  Therefore, the present invention is based on the structure in which the core segment is composed of a plurality of segment pieces divided in the tire axial direction, and the intermediate segment piece is configured to be replaceable. The child segments can be formed by using the side segment pieces in common, reducing the number of parts, and suppressing the decrease in storage management efficiency, the increase in storage space, and the increase in the manufacturing cost of the core segments. An object of the present invention is to provide a method for producing a pneumatic tire and a rigid core used therefor.

In the invention of claim 1 , a toroid having a tread molding portion that forms the inner surface of the tread portion of the pneumatic tire, and a side molding portion that forms the inner surface of the sidewall portion and the inner surface of the bead portion of the pneumatic tire. Hollow rigid core,
It consists of multiple core segments divided in the tire circumferential direction,
Each of the core segments is divided in the tire axial direction by a dividing surface passing through the tread molding portion, and has one side segment piece having a side molding portion on one side in the tire axial direction, and side molding on the other side in the tire axial direction. A plurality of segment pieces including the other side segment piece having a portion and an intermediate segment piece interposed therebetween,
Each segment piece is connected interchangeably between the divided surfaces via a connecting means,
Moreover, the coupling means is a bolt fitting embedded in each side segment piece, and having a screw shaft portion protruding from the split surface of the side segment piece,
An insertion hole portion formed on the split surface of the intermediate segment piece and through which the screw shaft portion passes, and a nut fitting connected to the insertion hole portion and screwed to the screw shaft portion passing through the insertion hole portion are accommodated. A mounting hole having a nut receiving hole,
And including the nut fitting,
The nut accommodation hole is opened at the inner surface in the tire radial direction of the intermediate segment piece.

In the invention of claim 2, the insertion hole portion comprises a first long hole portion that is long in the tire radial direction and a second long hole portion that is long in the tire circumferential direction,
The connecting means includes a disc-shaped height adjustment cam guided in the second elongated hole portion and accommodated so as to be movable and rotatable in the length direction thereof, and the height adjustment cam includes: A hole portion through which the screw shaft portion passes is provided at a position separated from the center point.
In the invention of claim 3, the tread portion, a pair of sidewall portions extending inward in the tire radial direction from both sides in the tire axial direction, and a bead portion positioned at an inner end in the tire radial direction of each sidewall portion. A toroidal pneumatic tire manufacturing method comprising:
A raw tire forming step of forming a raw tire by using the rigid core according to claim 1 or 2 and sequentially bonding unvulcanized tire constituent members to the outer surface of the rigid core; ,
And a vulcanization step of vulcanizing and molding the raw tire together with the rigid core into a vulcanization mold.

  As described above, in the present invention, the core segment is composed of side segment pieces on both sides in the tire axial direction which are divided by a dividing surface passing through the tread molding portion, and intermediate segment pieces interposed therebetween. Therefore, for example, the width of the core segment in the tire axial direction can be freely adjusted by replacing the intermediate segment piece with an intermediate segment piece of another size with a different width in the tire axial direction, or by increasing or decreasing the number of intermediate segment pieces to be attached. can do.

  That is, the width in the tire axial direction of the rigid core can be adjusted according to the size of the pneumatic tire to be manufactured while using the side segment pieces on both sides in common. The intermediate segment piece can be used in common for rigid cores with the same outer diameter, and the intermediate segment piece has a substantially plate shape so that it can be stored easily and in a small space. It is. Accordingly, it is possible to suppress a decrease in storage management efficiency, an increase in storage space, an increase in manufacturing cost of the core segment, and the like in combination with a reduction in the number of parts accompanying the common use of the side segment pieces.

It is sectional drawing which shows the raw tire formation process in the manufacturing method of the pneumatic tire of this invention. It is sectional drawing which shows the vulcanization | cure process in the said manufacturing method. It is a side view which shows a rigid core. It is a perspective view which shows a rigid core. It is sectional drawing which shows a core segment. (A) is sectional drawing of the tire axial direction which shows a connection means, (B) is the AA sectional drawing. It is a perspective view which shows a connection means notionally. (A)-(C) are explanatory drawings which show the effect | action of a height adjustment cam. It is explanatory drawing which shows the adjustment method of the tire axial direction width | variety of a rigid core. (A)-(C) are explanatory drawings which illustrate an exhaust passage. It is explanatory drawing which shows the other adjustment method of the tire axial direction width | variety of a rigid core. (A), (B) is sectional drawing and the side view explaining the manufacturing method of the conventional rigid core and a tire using the same.

Hereinafter, embodiments of the present invention will be described in detail.
As schematically shown in FIG. 1, the pneumatic tire manufacturing method of the present invention uses a toroid-shaped hollow rigid core 10, and an unvulcanized tire constituting member 12 is formed on the outer surface of the rigid core 10. The raw tire 1 is formed in the vulcanizing mold 11 together with the rigid core 10 as shown in FIG. And a vulcanization step S2 for vulcanization molding. Examples of the tire constituent member 12 include an inner liner rubber 12a, a carcass ply 12b, a belt ply 12c, a bead core 12d, a clinch rubber 12e, a sidewall rubber 12f, and a tread rubber 12g.

  As the raw tire forming step S1 and the vulcanizing step S2, various conventional raw tire forming steps and vulcanizing steps using a rigid core can be suitably employed. Is omitted.

  Next, as shown in FIG. 1, the rigid core 10 used in the method for manufacturing a pneumatic tire according to the present invention includes a tread molding portion 13 that forms the inner surface 2S of the tread portion 2 of the tire 1, and the tire 1. It is formed in a hollow toroid shape having a side molding portion 14 that forms the inner surface 3S of the sidewall portion 3 and the inner surface 4S of the bead portion 4. This rigid core 10 is a hollow toroidal rigid body formed using a metal material having excellent heat conduction, such as an aluminum alloy, and its outer surface matches the inner cavity surface (inner surface) of the tire. A cavity H for accommodating a vulcanizing heater (not shown) is formed in the inside thereof.

  The rigid core 10 is formed of a plurality of core segments 6 divided in the tire circumferential direction, as shown in FIGS. The plurality of core segments 6 includes first and second core segments 6A and 6B that are alternately arranged in the circumferential direction. Each core segment 6 is held in a toroidal shape by being prevented from moving inward in the radial direction by an inner ring 9 (shown in FIGS. 1 and 3) disposed in the inner hole 8 thereof.

  The first core segment 6A has a large circumferential width, and both end surfaces in the circumferential direction are inwardly inclined surfaces 7A that are inclined in a direction in which the circumferential width decreases toward the inside in the radial direction. The second core segment 6B has a small width in the circumferential direction, and both end surfaces in the circumferential direction are inclined in the direction in which the circumferential width increases toward the inside in the radial direction and the inwardly inclined surface 7A. And an outwardly inclined surface 7B. By configuring in this way, the rigid core 10 can be disassembled and removed from the inner hole 8 side by moving one by one radially inward from the second core segment 6B. .

  Next, as shown in FIG. 5, each core segment 6 is composed of a plurality of segment pieces 20 that are divided in the tire axial direction by a dividing surface K that passes through the tread molding portion 13. The segment piece 20 includes one side segment piece 20Aa having a side molding portion 14 on one side in the tire axial direction, the other side segment piece 20Ab having a side molding portion 14 on the other side in the tire axial direction, and an intermediate interposed therebetween. The segment pieces 20M are configured such that each segment piece 20 is connected between the dividing surfaces K and K via the connecting means 21 so as to be exchangeable, whereby the integral core segment 6 is formed. On the other hand, the other side segment pieces 20Aa and 20Ab are collectively referred to as side segment pieces 20A.

  In this example, the core segment 6 has a horizontal plane area Y on the tire equator CO side in which the outer peripheral surface of the tread molding portion 13 is substantially parallel to the tire axis in the meridional section, and the dividing plane K is the horizontal plane area Y Formed. Accordingly, the outer peripheral surface of the intermediate segment piece 20M is formed as a part of a cylindrical surface having a constant diameter. In this example, the dividing surface K is formed in parallel with the tire equator surface.

  As shown in FIGS. 6 and 7, the connecting means 21 includes a bolt fitting 22 embedded in each side segment piece 20A and having a screw shaft portion 22a protruding from the dividing surface K of the side segment piece 20A, A mounting hole 23 formed in the dividing surface K of the segment piece 20M, and a nut fitting 24 that is screwed to the bolt fitting 22 to connect the side segment piece 20A and the intermediate segment piece 20M interchangeably.

  The mounting hole 23 accommodates the insertion hole portion 25 through which the screw shaft portion 22a passes and the nut fitting 24 that is connected to the insertion hole portion 25 and is screwed to the screw shaft portion 22a that passes through the insertion hole portion 25. And a nut receiving hole portion 26 to be used. The nut housing hole 26 opens at the inner surface in the tire radial direction of the intermediate segment piece 20M, so that the nut fitting 24 can be screwed using a wrench or the like from the inner surface side.

  Further, in this example, the insertion hole portion 25 includes a first long hole portion 25a that is long in the tire radial direction and a second long hole portion 25b that is long in the tire circumferential direction. A disc-like height adjusting cam 27 is provided which is guided by the two long hole portions 25b and is accommodated so as to be movable and rotatable in the length direction. The first elongated hole portion 25a has a width Wa substantially equal to the diameter of the screw shaft portion 22a, and the second elongated hole portion 25b has a width Wb substantially equal to the diameter of the height adjusting cam 27. . The height adjusting cam 27 has a hole portion 27a through which the screw shaft portion 22a passes at a position separated from the center point P by a distance L. Therefore, as shown in FIG. 8, by turning the height adjustment cam 27, the screw shaft portion 22a can be height-adjusted in the tire radial direction by a distance of 2L, and the outer peripheral surface of the side segment piece 20A can be adjusted. And the outer peripheral surface of the intermediate segment piece 20M can be aligned with the same surface and can be accurately connected.

  In this example, when the core segment 6 is formed, the intermediate segment piece 20M is replaced with an intermediate segment piece 20Mi of another size having a different width in the tire axial direction, so that the size of the pneumatic tire to be manufactured is changed. Thus, the width W in the tire axial direction of the rigid core 10 is adjusted.

  Specifically, as shown in FIG. 9, a plurality of types of intermediate segment pieces 20M1 to 20Mn that differ only in the width in the tire axial direction are prepared in advance, and an intermediate segment piece 20Mi having a size according to the size of the pneumatic tire is prepared from these. Select and use. Thereby, the tire axial direction width | variety of the rigid core 10 can be adjusted, commonly using the side segment piece 20A of both sides. Further, the intermediate segment piece 20A can be commonly used for rigid cores having different tire cross section heights as long as they have the same outer diameter. Moreover, since the intermediate segment piece 20A has a substantially plate shape, it is excellent in storability and can be stored in a small space. Therefore, coupled with the reduction in the number of parts associated with the common use of the side segment piece 20A, the storage space can be reduced and the storage management efficiency can be improved, and the intermediate segment piece 20M supports core segments of various sizes. Therefore, it can contribute to the reduction of manufacturing cost.

  Further, in the vulcanization step S2, during vulcanization, air from the inside of the raw tire 1 tends to cause air accumulation between the raw tire 1 and the rigid core 10, and bears on the tire lumen surface. Therefore, an exhaust passage 30 for exhausting air is formed in the core segment 6 between the divided surfaces K and K to be connected.

  As shown in FIG. 10, the exhaust passage 30 can be formed by forming an uneven surface 31 at least one of the divided surfaces K and K to be connected. As the uneven surface 31, for example, as shown in FIG. 10A, a groove 31 a or a rib-like ridge is formed on the dividing surface K, and as shown in FIG. What formed the fine uneven part 31b in the division surface K etc. can employ | adopt suitably. The concave groove 31a (or ridge) is not limited to the one that extends linearly in the radial direction as in this example, but one that extends in a curved line in the radial direction, and straight in the direction inclined with respect to the radial direction. Various cases are included, such as a shape extending in a curved shape, a shape in which a plurality of types of concave grooves having different inclinations are mixed. Further, the uneven surface 31 does not need to be formed on the entire dividing surface K.

  As shown in FIG. 10C, a spacer plate 32 is disposed between the divided surfaces K and K, and the exhaust passage 30 is formed by a gap D between the divided surfaces K and K formed by the spacer plate 32. You can also. The spacer plate 32 can also be used for fine adjustment of the width of the rigid core 10 in the tire axial direction.

  Next, as another method for adjusting the tire axial width of the rigid core 10, as shown in FIG. 11, a plurality of intermediate segment pieces 20M are prepared which are relatively thin, that is, the tire axial width is relatively small. To do. And the tire axial direction width | variety of the rigid core 10 is adjusted by increasing / decreasing the number of the intermediate segment pieces 20M distribute | arranged between the side segment pieces 20A and 20A. In this case, the case where all the intermediate segment pieces 20M between the side segment pieces 20A and 20A are removed and the core segment 6 is formed only by the side segment pieces 20A and 20A is included.

  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.

DESCRIPTION OF SYMBOLS 1 Raw tire 2 Tread part 3 Side wall part 4 Bead part 6 Core segment 10 Rigid core 12 Tire component 13 Tread molding part 14 Side molding part 11 Vulcanization mold 20 Segment piece 20A Side segment piece 20M Intermediate segment piece 21 Connecting means 22 Bolt fitting 22a Screw shaft portion 23 Mounting hole 24 Nut fitting 25 Insertion hole portion 25a First elongated hole portion 25b Second elongated hole portion 26 Nut accommodating hole portion 27 Height adjusting cam 27a Hole portion 30 Exhaust passage 31 Uneven surface 32 Spacer plate D Gap K Dividing surface S1 Raw tire forming step S2 Vulcanizing step

Claims (3)

A toroid-shaped hollow rigid core having a tread molding portion that forms an inner surface of a tread portion of a pneumatic tire and a side molding portion that forms an inner surface of a sidewall portion and an inner surface of a bead portion of the pneumatic tire Because
It consists of multiple core segments divided in the tire circumferential direction,
Each of the core segments is divided in the tire axial direction by a dividing surface passing through the tread molding portion, and has one side segment piece having a side molding portion on one side in the tire axial direction, and side molding on the other side in the tire axial direction. A plurality of segment pieces including the other side segment piece having a portion and an intermediate segment piece interposed therebetween,
Each segment piece is connected interchangeably between the divided surfaces via a connecting means,
Moreover, the coupling means is a bolt fitting embedded in each side segment piece, and having a screw shaft portion protruding from the split surface of the side segment piece,
An insertion hole portion formed on the split surface of the intermediate segment piece and through which the screw shaft portion passes, and a nut fitting connected to the insertion hole portion and screwed to the screw shaft portion passing through the insertion hole portion are accommodated. A mounting hole having a nut receiving hole,
And including the nut fitting,
A rigid core for manufacturing a pneumatic tire, wherein the nut housing hole is opened at an inner surface in the tire radial direction of the intermediate segment piece . The insertion hole portion includes a first long hole portion that is long in the tire radial direction and a second long hole portion that is long in the tire circumferential direction,
The connecting means includes a disc-shaped height adjustment cam guided in the second elongated hole portion and accommodated so as to be movable and rotatable in the length direction thereof, and the height adjustment cam includes: The rigid core for manufacturing a pneumatic tire according to claim 1, wherein a hole portion through which the screw shaft portion passes is provided at a position separated from the center point. A toroidal pneumatic tire having a tread portion, a pair of sidewall portions extending inward in the tire radial direction from both sides in the tire axial direction, and a bead portion positioned at an inner radial end of each sidewall portion. A manufacturing method comprising:
A raw tire forming step of forming a raw tire by using the rigid core according to claim 1 or 2 and sequentially bonding unvulcanized tire constituent members to the outer surface of the rigid core; ,
A method for producing a pneumatic tire, comprising: a vulcanization step in which the green tire is put together with the rigid core into a vulcanization mold and vulcanized .

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