JP2016147384A - Method for manufacturing pneumatic tire, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a uniformity while increasing production efficiency of a green tire.SOLUTION: A core construction method includes a process in which a carcass ply, in which strip pieces are located in a tire circumferential direction, is formed. This process includes the first to n-th pasting steps of independently pasting the first to n-th strip pieces at the first to n-th stations respectively. In the first pasting step, the first strip pieces are pasted over one round in a cutting order thereof and with a clearance D of (n-1) piece therebetween. In the n-th pasting step, the n-th strip pieces are pasted over one round in the cutting order thereof and one by one in each clearance D, and further, the n-th strip pieces are so pasted as to be adjacent to the (n-1)th strip pieces which have been pasted in the (n-1)th step.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a pneumatic tire manufacturing method and a pneumatic tire that improve uniformity while increasing production efficiency of raw tires in a core method.

  Patent Document 1 below proposes a tire manufacturing method (sometimes referred to as a “core method”) using a rigid core having an outer shape substantially equal to the lumen shape of a vulcanized tire. In this proposed core method, a raw tire is formed by sequentially sticking tire components onto a rigid core, and a raw tire is inserted into a vulcanization mold together with the rigid core. And a vulcanization step of vulcanization molding.

  In the green tire forming step, the carcass ply a, which is one of the tire constituent members, is formed from a plurality of strips c on the rigid core b as shown in FIGS. 10 (A) and 10 (B). It is formed by sticking sequentially in the circumferential direction. The strip c is formed by sequentially cutting a narrow rubber strip d having a carcass cord f aligned in the length direction at a predetermined length. The rubber strip d is continuously formed by a topping device using a rubber extruder, and the rubber strip d is once wound in a roll and stored.

  When forming the raw tire, the roll body of the rubber strip d is supplied to a carcass ply forming station, and the rubber strip d rewound from the roll body is sequentially cut from the front end side and cut. The strips c are attached to the rigid core b in the cutting order.

  However, in the case of a roll body, the rubber strip d is deformed to have a larger strip width and a larger carcass cord distance toward the radially inner end side (winding start side) due to the influence of tension or the like. For example, in the case of a rubber strip d having a length of 180 to 200 m, a difference of 0.25 to 0.30 mm occurs in the strip width between the radially inner end (winding end) and the radially outer end (winding end). To do.

  Accordingly, when the roll body is used up in the course of forming the carcass ply and replaced with a new roll body, as shown in FIG. ) To the region of the strip strip ca (the strip width is large) and the strip strip cb (the strip width is small) formed from the radially outer side (winding end side) of the roll body after replacement. Divided in the direction. As a result, unevenness occurs in the circumferential direction, resulting in a decrease in uniformity, such as worsening the roundness of the tire.

  On the other hand, in the carcass ply formation process, since the number of strips attached is very large, the process time becomes long, which is one of the causes of a decrease in production efficiency of raw tires. For this reason, it is desirable to reduce the cycle time by attaching the strip pieces by dividing them by a plurality of stations. However, when strips are pasted continuously in each station, strip strips c1 pasted at one station P1, as shown in FIG. 11B, when divided into two stations P1 and P2. And the area of the strip c2 to be pasted at the other station P2 are divided into two in the circumferential direction. As a result, the uniformity is reduced as described above. In addition, when the roll body is exchanged in at least one of the stations, the deterioration of the uniformity is further increased.

International Publication WO2014 / 054403

  An object of the present invention is to provide a pneumatic tire manufacturing method and a pneumatic tire that improve uniformity while reducing the cycle time of the carcass ply forming process and improving the production efficiency of the raw tire in the core method. Yes.

The present invention is a green tire forming step of forming a green tire by sequentially affixing a tire constituent member including an unvulcanized carcass ply on a rigid core;
A method of manufacturing a pneumatic tire comprising a vulcanization step of vulcanizing and molding the raw tire together with the rigid core into a vulcanization mold,
The raw tire forming step includes a carcass ply forming step in which a plurality of strip pieces form a carcass ply arranged in the tire circumferential direction without overlapping at least on the tire equator,
The strips use first to n-th roll bodies in which narrow rubber strips having carcass cords aligned in the length direction are wound in a roll shape, and the first to n-th roll bodies are used. Each of the rubber strips rewound from each of the first to nth strips formed by sequentially cutting at a predetermined length from the tip side,
The carcass ply forming step includes first to n-th pasting steps for pasting the first to n-th strip pieces separately at first to n-th pasting stations,
Moreover, in the first pasting step, in the first pasting station, the first strip pieces are arranged in the cutting order and spaced apart by an interval (n-1) in the tire circumferential direction over the entire circumference. pasting,
In the n-th pasting step, after the preceding (n-1) pasting step, at the n-th pasting station, the n-th strips are cut one by one in the interval D in the cutting order. In addition, it is pasted in the tire circumferential direction over the entire circumference adjacent to the (n-1) strip strips pasted in the (n-1) pasting step,
Thereby, the 1st to n-th strips are characterized by forming carcass plies dispersedly arranged in the tire circumferential direction in such a manner that (n-1) pieces are skipped.

  In the method for manufacturing a pneumatic tire according to the present invention, for each of the first to n-th pasting stations, cutting of the strip pieces from the respective roll bodies and pasting of the cut strip pieces may be performed. preferable.

  In the method for manufacturing a pneumatic tire according to the present invention, the rigid core is transported in a stoppable manner for each of the first to n-th pasting stations, and each pasting step is performed at the pasting station to be stopped. Are preferred.

  The present invention is characterized by being formed by the manufacturing method according to any one of claims 1 to 3.

  In the present invention, as described above, the strips in the carcass ply forming process are divided into first to n-th pasting stations. Therefore, the cycle time can be shortened to about 1 / n as compared with the case where no division is performed.

  Further, in each pasting station, strips formed from the respective roll bodies are pasted over the entire circumference in the respective cutting orders and at intervals of (n-1) sheets. As a result, a carcass ply is formed in which the first to n-th strips are dispersedly arranged in the tire circumferential direction so as to fly (n−1).

  In such a carcass ply, for example, the first strip is formed from the radially inner side (winding start side) of the roll body, and the second strip is formed from the radially outer side (winding end side) of the roll body. In this case, the uniformity can be improved because each of them is distributed in the circumferential direction.

  In addition, when the roll body is newly replaced in at least one pasting station, for example, when the first roll body is newly replaced in the first pasting station, the width before replacement is included in the first strip. Wide strips and narrow strips after replacement are mixed. However, since the 2nd to nth strips are interposed between the wide strip and the narrow strip, the uniformity can be improved.

It is sectional drawing which shows one Example of the pneumatic tire formed by the manufacturing method of this invention. It is sectional drawing which shows a raw tire formation process. It is sectional drawing which shows a vulcanization | cure process. (A), (B) is a meridional section perpendicular to the tire equator and a side view for explaining the carcass ply formation step. It is a perspective view which shows the formation method of the strip piece from a roll body. It is the conceptual diagram which looked at the 1st-nth sticking station from the upper part. It is a side view which represents the nth sticking station on behalf of. (A)-(C) are the conceptual diagrams which show sticking of the strip piece by the 1st-nth (n = 3) sticking step. It is a conceptual diagram explaining the problem in a comparative example. (A), (B) is a perspective view explaining the manufacturing method of the conventional pneumatic tire using the rigid core. (A), (B) is a conceptual diagram explaining the problem.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a cross-sectional view showing an example of a pneumatic tire 1 formed by the manufacturing method of the present invention. A pneumatic tire 1 according to this embodiment includes a carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to bead portions 4 on both sides, and a belt disposed radially outside the carcass 6 and inside the tread portion 2. With layer 7.

  The carcass 6 is formed of a carcass ply 6A in which carcass cords are arranged at an angle of, for example, 50 to 90 ° with respect to the tire circumferential direction. The carcass ply 6 </ b> A has a toroidal shape straddling the bead portions 4 and 4. Each bead portion 4 is provided with a bead core 5 including core pieces 5i and 5o inside and outside in the tire axial direction. Each of the core pieces 5i and 5o has a ring shape in which a bead wire is wound in a spiral shape, and is sandwiched between the core pieces 5i and 5o so that both ends of the carcass ply 6A are locked. Further, a tapered bead apex 8 made of hard rubber having a durometer A hardness of, for example, 70 to 100 degrees is disposed on the outer side of each core piece 5i, 5o in the tire radial direction.

  The belt layer 7 is formed of two or more belt plies 7A, 7A in this example, in which belt cords are arranged at, for example, 10 to 60 ° with respect to the tire circumferential direction. The belt layer 7 enhances the belt rigidity by crossing the belt cords between the plies, and reinforces substantially the entire width of the tread portion 2 with a tagging effect. In this example, a band layer 9 in which a band cord is spirally wound in the circumferential direction is arranged on the outer side in the radial direction of the belt layer 7 for the purpose of improving high-speed performance.

  A non-air permeable inner liner rubber 10 forming a tire lumen surface is disposed inside the carcass 6. Further, on the outside of the carcass 6, a sidewall rubber Sg that forms the outer surface of the sidewall portion 3 and a tread rubber Tg that forms the outer surface of the tread portion 2 are disposed. Further, clinching rubber Cg for preventing rim deviation is arranged on the outside of the bead core 5.

  Next, a method for manufacturing the pneumatic tire 1 will be described. This manufacturing method includes a raw tire forming step K1 and a vulcanizing step K2. As shown schematically in FIG. 2, in the raw tire forming step K <b> 1, the tire constituent members including the unvulcanized carcass ply 6 </ b> A are sequentially attached onto the rigid core 20 to form the raw tire 1 </ b> N. As shown schematically in FIG. 3, in the vulcanization step K <b> 2, the raw tire 1 </ b> N is put into the vulcanization mold 24 together with the rigid core 20, whereby the rigid core 20 and the vulcanization mold 24 are separated. The raw tire 1N is vulcanized and molded between. The rigid core 20 has a well-known structure, and the outer shape thereof substantially matches the lumen shape of the pneumatic tire 1.

  The raw tire forming step K1 includes an inner liner forming step of attaching a member for forming the inner liner rubber 10 to the rigid core 20, a carcass ply forming step of attaching a member for forming the carcass ply 6A, and a bead core 5 forming step. A bead core forming step for attaching a member, a bead apex forming step for attaching a member for forming a bead apex 8, a belt forming step for attaching a member for forming a belt ply 7, and a band forming step for attaching a member for forming a band layer 9 And a sidewall molding step for attaching a member for forming the sidewall rubber Sg, a tread molding step for attaching a member for forming the tread rubber Tg, and the like.

  Among these, in the processes other than the carcass ply forming process, various known ones using the rigid core 20 can be appropriately employed. Therefore, in the present specification, only the carcass ply forming step will be described below.

As shown in FIGS. 4 (A) and 4 (B), in the carcass ply forming step, a plurality of strips 12 are arranged in the tire circumferential direction without overlapping at least on the tire equator Co, thereby allowing unvulcanized A carcass ply 6A is formed. The strip piece 12 includes first to nth strip pieces 12 _{1 to} 12 _n . In this example, the case of n = 3 is shown.

As shown in FIG. 5, each strip 12 has a length L that extends between the bead portions 4, 4, and the length direction thereof is arranged in accordance with the direction of the carcass cord 14 a in the pneumatic tire 1. The strip 12 has a width W smaller than the length L, and the width W is preferably in the range of 10 to 50 mm. Each of the first to n-th strips 12 _{1 to} 12 _n has a narrow length of rubber strip 14 rewound from the _first to n-th roll bodies 13 _{1 to} 13 _n with a predetermined length from the tip side. It is formed by sequentially cutting. The rubber strip 14 is formed by, for example, using a topping device having a rubber extruder and covering an array of carcass cords 14a aligned in the length direction with topping rubber. By winding the rubber strip 14 in a roll shape, the first to n-th roll bodies 13 _{1 to} 13 _n are formed, respectively. That is, each of the _first to nth roll bodies 13 _{1 to} 13 _n is formed of a rubber strip 14 having substantially the same configuration.

FIG. 6 is a conceptual view of a part of the production line as viewed from above. As shown in the figure, the production line is provided with first to n-th pasting stations P _{1 to} P _n . The carcass ply forming step, the at first to joining station _P 1 to P _n of the n, joining steps _S 1 ~ of the first to n paste respective strips ₁₂ 1 to 12 _n into separate It comprises a S _n. The first to n-th pasting stations P _{1 to} P _n are provided on the transport track of the rigid core 20. The rigid core 20, first the first through while being stoppable transported to joining each station _P 1 to P _n of the n, to give first the a joining station _{P 1} a first paste the strips 12 ₁ joining step S ₁ is performed, the joining step S _n of the n is performed to paste strips 12 _n of joining stations P _n in the n-th of the n.

FIG. 7 representatively shows a side view of the nth application station _Pn . Note that the first to n-th pasting stations P _{1 to} P _n have substantially the same configuration, and in this example, the pasting station P _n is a reel stand 30 that rotatably holds the roll body 13 _n and the roll body. a strip transport unit 32 which transports the rubber strip 14 unwound from the 13 _n, and the cutting means 33 for forming the strips 12 _n by cutting the rubber strip 14 that has been conveyed, the rigid core receives the strips 12 _n 20 and a pasting device 34 for pasting to 20. The affixing device 34 includes an unwinding roller 36 supported by an elevating means 35, and the strip 12 _n is affixed while being unrolled along the outline of the rigid core 20 by lowering the unwinding roller 36. . That is, in this example, for each of the first to n-th pasting stations P _{1 to} P _n , the strip pieces 12 _{1 to} 12 _n are cut from the respective roll bodies 13 _{1 to} 13 _n and the cut strip pieces 12 are cut. _{1 to} 12 _n are pasted.

Further, as shown in FIG. 8 (A), the first joining step _{S 1,} in the first joining station _{P 1,} first the strips 12 _1, and (n-1) Like its cut order Affixed in the tire circumferential direction over the entire circumference with an interval D of flight.

Further, as shown in FIG. 8 (B), in the second joining step _{S 2,} after the first joining step _{S 1,} in the second joining station _{P 2,} the second strips 12 _2, The sheets are pasted in the tire circumferential direction over the entire circumference in the cutting order and one by one within each interval D, and adjacent to the _first strip strip 121 pasted first.

Further, as shown in FIG. 8 (C), in the joining step _{S n} of the n, after joining step _{S n-1} of the (n-1) which precedes, by joining station _{P n} of the n, the n Of the strips 12 _n in the cutting order and within each interval D, and the (n-1) _th strips pasted in the (n-1) th pasting step _Sn-1 Adjacent to the piece 12 _n-1 , it is pasted around the circumference in the tire circumferential direction.

Thereby, the carcass ply 6A can be formed in which the _first to _nth strip pieces 12 _{1 to} 12 _n are dispersed and arranged in the tire circumferential direction in such a manner that (n−1) pieces are skipped.

As a result, for example, the first strips 12 ₁ is formed from a radially inner side of the roll body 13 ₁ (winding start side), the second strips 12 ₂ radially outwardly of the roll body 13 ₂ (winding end side) Even when formed from the above, since they are dispersedly arranged in the circumferential direction, uniformity can be improved.

At least in one joining station, when replacing the roll body to the new, for example, when replacing the first roll body 13 ₁ in the first joining station P ₁ to the new roll body, the first strips the 12 _1, between the strips of the wide width before replacement, but the width narrow strips after replacement will be mixed, also in this case, the strips and Habasema of strips of wide width In addition, since the second to nth strip pieces 12 ₂ and 12 _n are interposed, uniformity can be improved.

  Note that an integer of 2 or more can be appropriately adopted as the “n”, but if it is too large, it is disadvantageous for equipment cost, line space, transfer time and the like. Therefore, n is preferably 2, 3 or 4.

Although different from the present invention, for example, using only the first strips 12 _1, in the first joining station P _1, in the first lap, attached at a distance D of flying one of the strips 12 ₁ with, in the second round, it is devised to paste the strips 12 ₁ to the distance D. However, in this case, when the roller body is replaced in the middle, as shown conceptually in FIG. 9, for example, the wide strips 12 ₁ a before replacement are dispersed, but the narrow strips after replacement are dispersed. A region Y in which 12 ₁ b continues is generated, and the dispersion effect is not sufficiently exhibited. Therefore, in this invention, the strip piece formed from the different roll body is used for each periphery.

  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.

A tire for a passenger car (tire size 245 / 45R18) having the structure shown in FIG. 1 using a rigid core was manufactured based on the specifications shown in Table 1, and the uniformity and production efficiency of each tire were tested. The manufacturing method is the same except for the carcass ply forming step. The main common specifications are as follows.
-Number of carcass plies: 1-Carcass cord angle: 90 °
・ Ply width of strip ply piece: 32mm
・ Number of strip ply pieces: 60

  In Comparative Example 1, the strip pieces are pasted without leaving a gap D at one pasting station. In Comparative Example 2, the strip pieces are pasted by ½ round without leaving the interval D at the two pasting stations. In Comparative Example 3, the strip pieces are pasted by 1/3 rounds without any interval D at the three pasting stations. In Comparative Example 4, a single strip is made two rounds with a gap D between two strips at one pasting station. In Comparative Example 5, three strips are separated by an interval D between two strips at one pasting station.

(1) Uniformity:
In accordance with JASO C607: 2000 “Automotive Tire Uniformity Test Method”, the RFV of 30 tires was measured, and the average value of each tire was evaluated by a 10-point method. The larger the value, the better the uniformity.

(2) Production efficiency:
The number of green tires that passed through the carcass ply formation process during 60 minutes was evaluated by a 10-point method. The larger the value, the better the production efficiency.

  As shown in the table, it can be confirmed that the embodiment can improve the uniformity while increasing the production efficiency of the raw tire.

1N raw tire 6A carcass ply 12, 12 _{1 to} 12 _n first to n-th strips 13, 13 _{1 to} 13 _n first to n-th roll body 14 rubber strip 14 a carcass cord 20 rigid core 24 vulcanized gold joining step type Co tire equator K1 raw tire forming step K2 vulcanizing process _P 1 to P _n first to joining station _S 1 to S _n first through n of the n

Claims (4)

On the rigid core, a raw tire forming step of forming a raw tire by sequentially pasting tire constituent members including an unvulcanized carcass ply;
A method of manufacturing a pneumatic tire comprising a vulcanization step of vulcanizing and molding the raw tire together with the rigid core into a vulcanization mold,
The raw tire forming step includes a carcass ply forming step in which a plurality of strip pieces form a carcass ply arranged in the tire circumferential direction without overlapping at least on the tire equator,
The strips use first to n-th roll bodies in which narrow rubber strips having carcass cords aligned in the length direction are wound in a roll shape, and the first to n-th roll bodies are used. Each of the rubber strips rewound from each of the first to nth strips formed by sequentially cutting at a predetermined length from the tip side,
The carcass ply forming step includes first to n-th pasting steps for pasting the first to n-th strip pieces separately at first to n-th pasting stations,
Moreover, in the first pasting step, in the first pasting station, the first strip pieces are arranged in the cutting order and spaced apart by an interval (n-1) in the tire circumferential direction over the entire circumference. pasting,
In the n-th pasting step, after the preceding (n-1) pasting step, at the n-th pasting station, the n-th strips are cut one by one in the interval D in the cutting order. In addition, it is pasted in the tire circumferential direction over the entire circumference adjacent to the (n-1) strip strips pasted in the (n-1) pasting step,
Thereby, the manufacturing method of the pneumatic tire characterized by forming the carcass ply by which the 1st-n-th strip piece each disperse | distributed and arrange | positioned in the tire circumferential direction (n-1) sheets.   2. The pneumatic tire according to claim 1, wherein for each of the first to n-th pasting stations, cutting of the strip pieces from the respective roll bodies and pasting of the cut strip pieces are performed. Production method.   The said rigid core is conveyed so that it can stop at every 1st-nth sticking station, and each sticking step is performed in the sticking station to stop. Method of manufacturing a pneumatic tire.   A pneumatic tire formed by the manufacturing method according to claim 1.