JP4488792B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a manufacturing method of a pneumatic tire in which a raw tire is molded on a rigid core having an outer surface shape corresponding to an inner surface shape of a product tire, and in particular, a carcass ply composed of a plurality of steel cords arranged in parallel. The present invention proposes a technique for preventing the carcass ply, or more directly, the steel cord from slipping out of the bead core in a radial or semi-radial carcass-structured truck / bus tire.

  A carcass material is formed in a cylindrical shape on a molding drum to form a carcass band, and an annular bead core and a bead filler are disposed on each end portion of the carcass band. For example, under the expansion deformation of a folded bladder, the carcass band Fold each edge of the bead core around to make a green case, and then shape this green case on the former ring to bulge and deform the central part in the axial direction in the crown area of the green case, For example, according to a conventional general pneumatic tire manufacturing method in which a green tire is molded by pasting a belt tread band that is integrally molded in advance, for example, in vulcanization molding of a raw tire The extension angle of the belt layer cord may change due to the expansion shaping in the vulcanization mold. The rubber thickness of the tread portion is reduced, and the belt composed of one or more belt layers cannot be maintained in the expected position and shape due to the action of the concavo-convex molding surface of the vulcanization mold. There was a problem such as.

In order to solve such problems, for example, as disclosed in Japanese Patent Application Laid-Open No. 11-11540, it is proposed to mold a green tire on a rigid core having an outer surface shape corresponding to the inner surface shape of the product tire. According to this method, it is not necessary to shape the green case or the like in the raw tire molding problem, and the raw tire on the rigid core is inserted into the vulcanization mold together with the rigid core. In addition, since the diameter-shaping shaping of the raw tire in the mold is also unnecessary, the extension angle of the belt layer cord, the position and shape of the belt, the rubber thickness of the tread portion, etc. are maintained as expected. It becomes possible.
Japanese Patent Laid-Open No. 11-11540

  However, when a green tire is molded using a rigid core, especially when a carcass ply is formed by a plurality of steel cords arranged in parallel, the carcass ply is generally prevented from coming off. For example, the annular bead core is embedded in the radial direction of the carcass ply between the adjacent bead core divided parts as a divided structure in the width direction of the bead part. Therefore, there has been another problem that the pull-out resistance of the carcass ply is inevitably lowered.

  The present invention has been made to solve such a problem in the case of molding a raw tire using a rigid core. The object of the present invention is to provide a raw tire using a rigid core. The advantage of molding is to provide a method for manufacturing a pneumatic tire in which the pull-out resistance of a carcass ply made of a steel cord is greatly improved.

  In the present invention, a green tire molded on a rigid core having an outer shape corresponding to the inner shape of the product tire is inserted into a vulcanization mold together with the rigid core while maintaining the molded state, and Under the support of the rigid core, it is formed on the assumption that it is molded with a molding surface and vulcanized.

Here, the manufacturing method of the pneumatic tire according to the present invention includes a raw tire including a carcass ply that extends between each bead core embedded in a pair of bead portions and reinforces the pair of sidewall portions and the tread portion. Is molded on the rigid core having the outer shape corresponding to the inner shape of the product tire as described above, at least one piece of a plurality of mutually independent steel cords disposed on the rigid core. The carcass ply is engaged with an annular bead core that is disposed in advance or afterwards in a bent portion formed by plastic deformation of both inner end portions in the radial direction of the carcass ply , Before the carcass ply is disposed on the rigid core, the bent portions are formed by plastic working at both end portions of each steel cord constituting the carcass ply. There to do by.

  Further, each curved portion can be formed by plastic deformation at one place with respect to the carcass ply, and can also be formed by plastic deformation at a plurality of places.

  Moreover, when a plurality of carcass plies are disposed, it is preferable that each of them is engaged with the bead core.

  More preferably in the method as described above, each bead core is constituted by two or more bead core divided parts arranged adjacent to each other in the width direction or the radial direction of the bead part, and one piece is provided between the divided parts. The above carcass ply is clamped.

  In this case, in addition to sandwiching each bent portion of the carcass ply between the bead core divided portions, it is also possible to sandwich a radially outer portion from the bent portion.

  When a raw tire is molded as described above, in the product tire formed by vulcanization molding, one or more carcass plies still engage with the bead core with a bent portion. The pull-out resistance of the carcass ply can be greatly improved as compared with the prior art in which the carcass ply is sandwiched between the divided portions.

However, each such folded portion of the carcass ply, by forming at the stage of the carcass ply material, regardless somewhat plastic deformation point, Ru can be accurately formed in desired the street.

  Here, the pull-out resistance of the carcass ply is the case where each bent portion is formed by plastic deformation at a plurality of locations, and the amount of the bent portion to be engaged with the bead core, in other words, the amount of winding around the bead core is increased. This also applies to the case where each of the plurality of carcass plies is engaged with the bead core.

  Further, the pull-out resistance of the carcass ply is such that each bent portion is engaged with the bead core, and the bent portion or the radially outer portion thereof is formed between the adjacent divided portions constituting the bead core. It is further improved by sandwiching between the two.

  1 and 2 are cross-sectional views of the main part in the width direction showing an example of the product structure of a large tire for trucks and buses to which the present invention is directed, in which 1 is a bead portion and 2 is each bead portion. Reference numeral 1 denotes a sidewall portion continuous outward in the radial direction, and 3 denotes a tread portion that bridges the pair of sidewall portions 2.

And here, it consists of one or more carcass plies 5 extending between both bead cores 4 buried in each bead part 1 and reinforcing each of the bead part 1, the sidewall part 2 and the tread part 3. A carcass 6 having a radial or semi- radial structure is disposed, and the tread portion 3 is further reinforced by a belt 7 made of a plurality of belt layers disposed on the outer peripheral side of the crown region of the carcass 6.

  By the way, in the place shown in the drawing, each bead core 4 is composed of two bead core divided portions 8 disposed adjacent to each other in the width direction of the bead portion 1. In the tire shown in FIG. The inner end portion in the radial direction of one carcass ply 5 made of a steel cord is bent in a bowl shape by one plastic deformation through the bead core divided portions 8 to the outside or inside in the width direction of the bead portion. The bent portion 9 is engaged with the bead core divided portion 8 located on the outer side or the inner side, and according to such a bead portion configuration, the carcass ply 5 is bent into the bead core divided portion 8 and eventually the bead core 4. It is firmly prevented from coming off by the engagement of the portion 9 and the clamping of the radially outer portion of the bent portion 9 between the bead core divided portions 8.

  On the other hand, in the tire shown in FIG. 2, a carcass 6 is formed by two inner and outer carcass plies 5, and the inner end portion in the radial direction of the inner carcass ply 5 is bent into a bowl shape by plastic deformation at one place. The bead core 10 is hooked to the bead core 4 with the bent portion 10 facing outward in the width direction of the bead portion, and the radially inner end portion of the carcass ply 5 on the outer peripheral side passes between the bead core split portions 8 and extends in the width direction of the bead portion. A bend portion 11 formed by bending in the same manner to the outside or the inside is engaged with the bead core 4.

  According to such a structure, the carcass 6 is effectively prevented from coming off by engaging the bent portions 10 and 11 with the bead core 4 and holding the outer peripheral side carcass ply 5 between the bead core divided portions 8. Will be.

On a rigid core composed of a plurality of segments that can be disassembled and assembled, with the outer shape corresponding to the inner shape of the product tire, for the product tire as described above, having a structure substantially similar to that of the tire. For example, as shown in a perspective view in FIG. 3, a plurality of steel cords 22 are arranged at a predetermined pitch on a rigid core 21 that is rotationally displaced as required. A bent portion 9 that is plastically deformed in a bowl shape and is bent in an L shape outward in the width direction of the rigid core 21 is formed on each inner end portion in the radial direction of the carcass ply 5 formed in the above-described manner. pre, in other words, the plastic machining to result form for the carcass material before the formation of the carcass ply 5, also, the outer peripheral side of the bent portion 9, formed by an endless form in advance an annular, or, Dokodo, thereby forming a bead core 4 or bead core wedges 8 formed by laminating winding ex post spiral.

  Here, in the case where the bead core 4 has a two-way structure in the width direction of the bead portion as shown in FIG. 1A, for example, FIG. 4 is a partial sectional view in the width direction of the rigid core. As shown, prior to the formation of the carcass ply 5 on the core 21, the inner split portion 8 is formed on the outer side of the inner liner 23 by, for example, a pre-helical winding stack of bead cords, and the outer By forming the divided portion 8 on the outer peripheral side of the bent portion 9 of the carcass ply 5 formed thereafter as described above, the bent portion 9 is engaged with the bead core 4 and the bent portion 9 is formed. The more radially outer portion can be sandwiched between the bead core divided portions 8.

  Further, in the tire having the structure shown in FIG. 1B, the bent portion 9 provided in advance in the formation of the carcass ply 5 after the formation of the inner divided portion 8 is replaced with the existing inner divided portion. By engaging with the portion 8 and then forming the outer divided portion 8 in the same manner, the bent portion 9 is engaged with the bead core 4 and between the divided portions 8 at the radially outer portion from the bent portion 9. Can be pinched.

  Here, the bending portion as shown in FIG. 1 is formed in advance on the carcass material, for example, as shown in a partial sectional perspective view in FIG. In the state where the steel cords 22 are aligned and held, the bending blades 25 are applied to the protruding portions of the both ends of the respective steel cords 22 from the support base 24, and the required end portions of all the steel cords 22 are required. This can be performed by plastic working the L-shaped bent portion 9a having an angle of.

  The carcass ply 5 is formed of the carcass material in which the bent portion 9 is preliminarily formed in this way. After the disposition of the inner divided portion 8 shown in FIG. 1, the carcass ply 5 is formed in the carcass shown in FIG. In a state where the bent portion 9 of the material is oriented upward as shown in FIG. 6A, and in the tire shown in FIG. 1B, the bent portion 9 is shown in FIG. As shown in (b), it can be performed by arranging the rigid core 21 around the entire circumference in a state of facing downward.

For reference , the subsequent formation of the bent portion 9 with respect to the carcass ply 5 formed on the rigid core 21 is not performed when the bead core 4 is composed of a plurality of divided portions 8 as shown in FIG. Regardless of whether or not the bead core 4 is formed as a whole, the ironing roller 26 is displaced outward in the width direction of the rigid core 21, and the end portion of the carcass ply 5 is ironed by the ironing roller 26 and the bead core 4. Ru can by Rigyo Ukoto to be deformed, but from the viewpoint of forming the bent portion 9 accurately and reliably, as in the present invention, distribution設前of the carcass ply 5, onto the rigid core 21 It is preferable to form the bent portion 9 at the same time.

As described above, the case where the raw tire is molded for the purpose of realizing the tire structure shown in FIG. 1 has been described. However, these are the same for the outer carcass ply 5 of the tire structure shown in FIG. structure shown in, in addition to the place described above, the distribution設前the bead core 4 and the outer carcass ply 5, on the inner liner 23 of the rigid core 21, pre-shape forming the bent portion 10 facing the outside of the bead portion The inner circumferential side carcass ply 5 to be attached can be attached and the outer bent portion 10 can be engaged with the bead core 4 as a result.

  After the carcass ply 5 is restrained from coming off by the bead core 4 in this way, as shown by the phantom line in FIG. 4, the required layer on the outer peripheral side of the crown portion of the carcass ply 5 and eventually the carcass 6. The arrangement of the belt layers 27, the arrangement of the side rubber 28 forming the outer skin of the bead part 1 and the side wall part 2 of the product tire, the arrangement of the tread rubber 29, etc. Thus, a raw tire as expected can be molded on the rigid core 21 by performing in the required order.

  Then, the raw tire is inserted into the vulcanization mold together with the rigid core 21, and is subjected to the required vulcanization molding, whereby the product tire shown in FIG. 1 or 2 is obtained. The product tire is completely separated from the rigid core 21 by disassembling and taking out the rigid core 21.

  By the way, each of the bent portions 9, 10, 11 of the carcass ply 5 described above is formed by bending plastic working on one portion of the carcass ply 5, but each bent portion is shown in FIG. As illustrated, it can also be formed by bending plastic working at two or more locations.

  Further, the bead core 4 can be divided not only in the width direction of the bead part but also in the radial direction of the bead part. In this case, as shown in FIG. The provided bent portion is sandwiched between the bead core divided portions adjacent to each other.

  Although the present invention has been described in the case of molding a large tire having a radial structure carcass made of steel cord, the present invention can also be used for molding a tire for a construction vehicle, a tire for a small truck, and the like.

It is principal part sectional drawing of the width direction which shows the structural example of a manufacture tire by this invention. It is principal part sectional drawing of the width direction which shows the other structural example of a manufacture tire by this invention. It is a perspective view which illustrates the molding process according to this invention. It is a fragmentary sectional view of the width direction of a rigid core which illustrates the forming process to the adjacent division structure of a bead core. It is a perspective view which shows the prior example of formation of the bending part with respect to a carcass raw material. It is a perspective view which illustrates the application mode of the carcass material which formed the bending part. It is principal part sectional drawing which shows the reference example of the subsequent formation of the bending part with respect to a carcass ply. It is a figure which shows the other example of formation of a bending part. It is a figure which illustrates the other division | segmentation aspect of a bead core.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Bead core 5 Carcass ply 6 Carcass 7 Belt 8 Bead core division part 9, 10, 11 Bending part 9a Bending process part 21 Rigid core 22 Steel cord 23 Inner liner 24 Support stand 25 Folding Bending blade 26 Ironing roller 27 Belt layer 28 Side rubber 29 Tread rubber

Claims (5)

A solid tire having a carcass ply extending between each bead core embedded in a pair of bead portions and reinforcing a pair of sidewall portions and a tread portion, and having an outer surface shape corresponding to the inner shape of the product tire In molding on the core,
At least one carcass ply made of a plurality of mutually independent steel cords arranged on a rigid core, and a bead core formed by bending the inner end portions in the radial direction into plastic bowls. to engage in,
Before forming the bent portion on the rigid core, the bent portion is formed by plastic processing the bent portion at each end portion of each steel cord constituting the carcass ply. Tire manufacturing method. The method for manufacturing a pneumatic tire according to claim 1 , wherein each bent portion is formed by plastic deformation at a plurality of locations of the carcass ply. The method for manufacturing a pneumatic tire according to claim 1 or 2 , wherein each of the plurality of carcass plies is engaged with a bead core. The method for manufacturing a pneumatic tire according to any one of claims 1 to 3 , wherein a carcass ply is sandwiched between bead core divided portions arranged adjacent to each other in a width direction or a radial direction of the bead portion. The method for manufacturing a pneumatic tire according to claim 4 , wherein the bent portion of the carcass ply or the radially outer portion of the bent portion is sandwiched between the bead core divided portions.

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