JP2008119975A - Manufacturing method of tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a tire which can easily manufacture the tire having structure for winding and latching a carcass ply around a bead ring from the outside toward the inside of the tire width direction, and can sufficiently improve the dimension accuracy of the tire and uniformity or the like. <P>SOLUTION: In manufacturing a pneumatic tire which extends one sheet or more of carcass plies made of steel cord 12 from a tread part to a bead part through a side wall part and winds them around the bead ring 5 disposed on the bead part from the outside toward the inside of the tire width direction, a carcass ply member 13 is formed by extending the respective steel cord 12 whose one end part is wound to the bead ring 5 on both side parts of annular rigid core 11 having an outer surface shape corresponding to an inner surface shape of the pneumatic tire toward the equator line e side of the rigid core 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a tire, for example, a pneumatic tire that can be used in heavy-duty vehicles such as trucks and buses. In particular, the present invention relates to a product tire in which a carcass ply is placed around a bead ring. The present invention proposes a technique for manufacturing a structure having a structure that is wound from the outer side in the width direction toward the inner side and hooked with ease and with high dimensional accuracy.

  For example, as described in Patent Document 1, in a tire in which a carcass ply is wound around a bead ring from the outside in the tire width direction toward the inside, the carcass ply tends to bulge to the outside of the tire. In addition to having a high degree of freedom in selecting the carcass ply pass line, it is possible to secure a large tire volume and effectively eliminate the possibility of carcass ply separation at the tire bead. While having the advantage of improving durability, there is a disadvantage that it is difficult to manufacture, and the realization of this structure is that the carcass ply made of steel cord is placed around the bead ring from the inside in the tire width direction to the outside It is much more difficult than the structure wound around

Therefore, in Patent Document 1, the carcass ply is made discontinuous in the central region of the tread portion to ensure the proper winding of the carcass ply with respect to each bead ring.
JP 2000-343907 A

  However, in manufacturing the pneumatic tire described in Patent Document 1, for example, the central portion is discontinuous on a band molding drum that has a uniform outer diameter over the entire length and has been widely used in the past. When forming a cylindrical carcass band, in the green tire molding process, for example, each end of the carcass band is wound around each of a pair of bead rings, and the radial positions of these bead rings are specified. In this state, the cylindrical carcass band is shaped so that the central portion bulges in the radial direction and is in close contact with the inner peripheral surface of the belt tread band, and the molded raw tire is vulcanized. The outer surface of the tread rubber is deformed and expanded under the action of a vulcanizing bladder, etc. Since the discontinuity of the center part of the carcass band cannot be specified exactly as expected when pressing, the discontinuous part of the carcass in the product tire after vulcanization molding However, the tire is caused by being biased on either side with respect to the tire equator surface, for example, the relative distance between the discontinuous portions being uneven in the circumferential direction, or the like. There was a problem that the dimensional accuracy, uniformity, and other risks of deterioration were high.

  The object of the present invention is to solve such problems of the prior art, and the object of the invention is to place the carcass ply around the bead ring from the outside in the tire width direction to the inside. It is an object of the present invention to provide a method for manufacturing a tire that can easily manufacture a tire having a structure that is wound and hooked toward the end, and that can sufficiently increase the dimensional accuracy, uniformity, and the like of the tire.

  In the tire manufacturing method according to the present invention, one or more carcass plies made of a steel cord are extended from the tread portion to the bead portion through the sidewall portion, and around the bead ring disposed in the bead portion, For example, when manufacturing a pneumatic tire wound from the outside in the tire width direction toward the inside under plastic deformation of the carcass ply, the outer shape corresponding to the inner shape of the pneumatic tire has From the start of tire molding to the end of vulcanization molding for that tire, each steel cord with one end wrapped around a bead ring on both sides of a disassembled annular rigid core that is attached to the tire In both cases, toward the equator line side of the rigid core, in a separated state from each other end or in an overlapping state between the other ends, In forming a carcass ply member by extending in the scan position.

  Preferably, the other end of each steel cord extending from the respective side portion of the rigid core to the equator line side of the rigid core is positioned at an interval of 20 mm or less around the equator line. The overlapping amount of the other end portions of both cords is set to 30 mm or less with the equator line as the center.

  Preferably, one or more bent portions provided in advance at one end of the steel cord are positioned in correspondence with the corner portion of the bead ring having a square cross-sectional shape, and the bent portion is connected to the bead ring. Each steel cord is wound around the bead ring in a posture aligned with the corner of the bead.

  By the way, in this case, one end of each steel cord with or without rubber coating can be wound around the bead ring, but preferably it is integrated with a plurality of draw steel cords. One end of a ribbon-like strip having a rubber coating is wound around the bead ring.

  In the manufacturing method of the present invention, one end portion of a steel cord is wound around a bead ring at each side portion of a decomposable rigid core that is attached to a tire from the formation of a green tire to the end of vulcanization molding. Therefore, regardless of whether or not the winding direction of the one end portion with respect to the bead ring is the direction from the outer side to the inner side in the tire width direction, the winding is performed easily and easily at all times. be able to.

  In addition, here, each steel cord having one end wound around a bead ring is extended toward the equator line side on a rigid core whose dimensions and shape are unchanged until the end of vulcanization molding. Therefore, the carcass ply member whose center portion bulges out as expected in the radial direction can be formed easily and always accurately. The ends can be arranged uniformly over the entire circumference at a predetermined position relative to the rigid core equator line and thus the equator plane of the product tire.

  Therefore, after the rigid core is disassembled and taken out from the product tire that has been vulcanized and molded, the other end of each steel cord has a predetermined distance from each other, and the other end of each of the steel cords. In any case where the portions overlap over a predetermined length, the dimensional accuracy, uniformity, etc. are sufficiently high.

  In this case, the other ends of the steel cords extended in a radial posture or a bias posture from each side of the rigid core to the equator line side of the rigid core are 20 mm or less centering on the equator line. When the product tires are positioned at a distance, when the product tires are filled with air pressure (for example, 900 kPa), the amount of variation in the distance between the other ends is kept sufficiently small to maintain excellent dimensional accuracy, uniformity, etc. In this way, the tire can exhibit the exercise performance as expected.

  On the other hand, when the other end portions of the steel cords are overlapped with each other and the mutual overlap amount is set to 30 mm or less around the rigid core equator line, the steel cord overlaps by vulcanization molding. When the tire is deflated by suppressing the stress remaining in the portion sufficiently small, the amount of protrusion toward the inner surface side of the tire can be suppressed, and as a result, riding comfort is improved.

  In addition, when one or more bent portions provided in advance at one end of the steel cord are positioned corresponding to the corner of the bead ring having a square cross-sectional shape, the steel cord is connected to the bead ring. The winding posture can always be as expected, and in addition, even when a large tension is applied to the steel cord, the steel cord can be effectively pulled out with a bead ring. it can.

  Here, when winding one end of the steel cord around the bead ring by winding one end of a ribbon-shaped strip in which a plurality of aligned steel cords are integrally coated with rubber, The formation efficiency of the carcass ply member can be greatly improved as compared with the case where the books are sequentially wound at a predetermined pitch.

  In this case, when the width of the ribbon-shaped strip is the same over the entire length thereof, the side surfaces of the respective ribbon-shaped strips are spaced from each other at the equator line position where the circumference of the rigid core is the longest. In order to make the pitch of the steel cords on the equator line sufficiently uniform over the entire circumference, the adjacent ribbon-shaped strips adjacent to each other at the radially inner portion of the rigid core are positioned in the radial direction. The amount of overlap gradually increases, and as a result, the overlap thickness at the bead ring portion becomes considerably thick. To effectively suppress such an increase in thickness, ribbon-like strips, especially coating The rubber thickness is gradually decreased from the position of the equator line toward the bead ring, increasing the thickness at the overlap part of the ribbon-like strip. Suppressing, or, the width of the ribbon-like strip, it is preferred to prevent mutual overlap of the ribbon-like strip adjacent gradually decreased toward the bead ring from the equatorial position.

FIG. 1 is a cross-sectional view in the tire width direction illustrating a main part of a pneumatic tire manufactured according to the present invention.
In the figure, reference numeral 1 denotes a carcass ply made of a steel cord and having a radial structure. A plurality of the carcass plies 1 showing only one in the figure can be arranged.

  Such a carcass ply 1 extends from the tread portion 2 through the sidewall portion 3 to the bead portion 4, and is disposed on the bead portion 4. The bead ring has a square cross section and a hexagonal shape in the figure. 5 is hooked by wrapping one side portion thereof from the outside in the tire width direction to the inside.

Here, as shown in the figure, this winding of one side portion of the carcass ply 1 includes the carcass ply 1 made of a steel cord, and thus the corner portion of the bead ring 5 provided in advance at one or more locations of the steel cord. Corresponding bending plastic processing portions, in the figure, three bending processing portions b ₁ , b ₂ , b ₃ are positioned corresponding to the respective corner portions of the bead ring 5, and their bending processing portions b _1. , B ₂ , and b ₃ are aligned by their corners, and it is preferable to hold the steel cord around the bead ring 5 in order to secure excellent winding accuracy and winding strength.

  Further, in the figure, such a carcass ply 1 has a so-called hollow structure that is discontinuous over a predetermined distance around the tire equator plane E at the center portion of the tread portion 2. The carcass ply 1 may have a so-called overlap structure in which respective portions extending through the pair of bead portions 4 and the sidewall portions 2 overlap each other at the central portion of the tread portion 2.

  In the figure, reference numeral 6 denotes a belt composed of, for example, three belt layers disposed on the outer peripheral side of the crown region of the carcass ply 1 having a hollow structure, and 7 is disposed further on the outer peripheral side of the belt 6. The tread rubber that defines the tread contact surface of the tire is shown.

The method according to the present invention for producing a pneumatic tire as described above, in particular, corresponds to the inner shape of the pneumatic tire as conceptually shown in the partial sectional perspective view of FIG. It has an outer surface shape and is disassembled on both sides of the disassembling toroidal rigid core 11 that is attached to the tire from the green tire molding to the end of the vulcanization molding of the tire. For example, one end portion of each steel cord 12, preferably one or more bent portions b ₁ , as described above, is disposed around each bead ring 5 having a square cross-sectional shape, for example, as described above. One end of b ₂ and b ₃ formed in advance is wound around the product tire so as to face inward from the outside in the tire width direction as shown in the drawing, and each bent portion b ₁ , b ₂ , b ₃ , beadlin The steel cords 12 are extended on the outer surface of the rigid core 11 in the radial posture or the bias posture toward the equator line e side thereof, Such plastic deformation of the individual steel cords 12 along the outer surface of the core can be performed by repeating the entire circumference of the rigid core 11 to form the carcass ply member 13.

Here, it is not essential to provide the angularly bent portions b ₁ , b ₂ , and b ₃ as shown in the drawing at one end of the steel cord 12, and a curved crease that bends in a curved shape at one end thereof. It is also possible to provide.

  In forming the carcass ply member 13 in this way, the other ends of the steel cords 12 extending from the respective side portions of the rigid core 11 to the equator line e side thereof are, for example, shown in FIG. ), It is preferable that the equator line e is positioned at a relative distance C of 20 mm or less, while the other end portions of the steel cords 12 are overlapped with each other. As illustrated in FIG. 3B, the overlapping amount O is preferably 30 mm or less with the core equator line e as the center.

  By the way, in addition to the relative distance C and the overlap amount O set in this way on the rigid core 11, other aspects of the extension of the steel cord 12, etc. are sequentially formed on the rigid core 11. In both cases where the raw tire is molded and the raw tire is inserted into the vulcanization mold together with the rigid core 11 and vulcanized and molded there, the initial state is kept on the rigid core 11. Since they are restrained and held, the relative position C and the generation position and size of the overlap amount O are maintained as they are in the product tire, and preferably the tire equatorial plane E is centered. Are accurately specified to values of 20 mm or less and 30 mm or less, respectively.

  When the carcass ply member 13 is formed as described above, each steel cord 12 with or without rubber coating is wound around the bead ring 5 and onto the outer surface of the core. Of course, in place of the steel cords 12 one by one, a plurality of steel cords arranged at a predetermined pitch are integrally coated with rubber, for example, When one end of a ribbon-like strip having a width of about 5 to 15 mm is wound around the bead ring 5 and disposed on the outer surface of the rigid core 11, the forming work efficiency of the carcass ply member 13 can be greatly improved.

  Thus, according to the method for molding a tire according to the present invention, more directly, the method for forming the carcass ply member, the one end portion of the steel cord is directed around the bead ring from the outer side to the inner side in the tire width direction. The carcass ply member 13 of a required form can be formed on the outer surface of the rigid core 11 with high position and dimensional accuracy, and can be reliably and simply wound as expected. The carcass ply member 13 is inserted into the vulcanization mold together with the rigid core 11 whose dimensions and the like are unchanged, and is formed into a carcass ply 1 as a part of the product tire by vulcanization molding of the raw tire. When the other end of the cord 12 has a predetermined interval on the rigid core 11, and the other end of the steel cord 12 extends over a predetermined length on the core 11. In any case overlapping, it can bring the product tire, excellent dimensional precision, the uniformity and the like.

  Tires having a size of 495 / 45R22.5 were manufactured by variously changing the relative distance C between the other ends of the steel cords 12 on the rigid drum 11. The product tire was subjected to a CT scan to measure the relative distance between the other ends of the steel cord 12 in the carcass ply 1, and a measurement result substantially equal to the relative distance C on the rigid drum 11 was obtained.

  Various types of tires with different relative distances between the other ends of the steel cord 12 are assembled to a specified rim, and when the inflation is filled with air pressure of 900 kPa, the amount of increase in the relative distances is similarly measured by CT scan. When measured, the results shown in the graph of FIG. 4 were obtained.

  As shown in FIG. 4, it is clear that the increase amount of the relative interval during inflation increases rapidly when the relative interval during deflation exceeds 20 mm.

  Here, if the amount of increase in relative spacing during inflation exceeds 20 mm, the risk of an increase in vibration or the like increases.

  Tires having a size of 495 / 45R22.5 were manufactured by varying the amount of overlap O between the other ends of the steel cords 12 on the rigid drum 11 in various ways.

  Each overlap amount of the steel cord 12 in the product tire was substantially the same as the overlap amount O on the rigid drum.

  Various tires with different overlaps at the other end of the steel cord 12 are assembled to the specified rim, and after the air pressure of 900 kPa is once filled there, the steel cord overlaps in a deflated state in which the air pressure is completely discharged. When the amount of protrusion of the portion toward the inner surface of the tire was measured, the results shown in the graph of FIG. 5 were obtained.

  According to FIG. 5, it can be seen that when the overlap amount of the steel cord 12 exceeds 30 mm, the protrusion amount toward the inner surface side when the tire is deflated increases rapidly.

  Here, if the protrusion amount at the time of deflation exceeds 30 mm, the possibility of separation after deterioration on the inner surface becomes high.

It is sectional drawing of the tire width direction which illustrates the pneumatic tire manufactured by the method which concerns on this invention about the principal part. 1 is a cross-sectional perspective view conceptually showing a method according to the present invention. It is an enlarged view which illustrates the other end position of a steel cord. It is a graph which shows the variation | change_quantity of the other end space | interval of the steel cord at the time of inflation of a tire. It is a graph which shows the protrusion amount to the tire inner surface side at the time of tire deflation.

Explanation of symbols

1 carcass ply 2 tread portion 3 sidewall portion 4 bead portion 5 bead core 11 rigid core 12 steel cord 13 carcass ply member E tire equatorial plane e rigid core equator line b _{1, b} 2, _{b 3} bent portion C relative spacing O overlap amount

Claims (4)

One or more carcass plies made of steel cord are extended from the tread part to the bead part through the sidewall part, and around the bead ring arranged in the bead part, from the outer side to the inner side in the tire width direction. In manufacturing a wound pneumatic tire,
Each steel cord with one end wrapped around a bead ring on both sides of an annular rigid core having an outer shape corresponding to the inner shape of the pneumatic tire is extended toward the equator side of the rigid core. A method of manufacturing a tire for forming a carcass ply member.   While the other ends of the steel cords extending from the respective sides of the rigid core to the equator line side of the rigid core are positioned with an interval of 20 mm or less centered on the equator line, both the cords The tire manufacturing method according to claim 1, wherein an overlapping amount of the other end portion is set to 30 mm or less with the equator line as a center.   2. One or more bent portions provided at one end of a steel cord are positioned in correspondence with corner portions of a bead ring having a square cross-sectional shape, and each steel cord is wound around the bead ring. Or the manufacturing method of the tire of 2.   The method for manufacturing a tire according to any one of claims 1 to 3, wherein one end of a ribbon-shaped strip in which a plurality of drawn steel cords are integrally covered with rubber is wound around a bead ring.

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