JP4469201B2 - Pneumatic tire manufacturing method and pneumatic tire - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire, which is useful for simplifying a manufacturing process and providing a low-cost pneumatic tire, and a pneumatic tire.

  For example, Patent Documents 1 to 3 listed below describe a pneumatic tire using a butyl rubber material as a topping rubber on the tire lumen side of a carcass ply. In such a pneumatic tire, the topping rubber has the function of an inner liner that has been conventionally provided separately from the carcass. Therefore, it is not necessary to prepare an inner liner separately in the manufacturing process, and the step of attaching the inner liner to the forming drum can be eliminated. Thereby, the manufacturing process of a tire can be simplified and the weight of the tire can be reduced.

Japanese Patent No. 2962658 JP 2000-272306 A JP 2001-121905 A

  The inventors have conducted intensive research on the pneumatic tire as described above in order to further simplify the manufacturing process and further reduce the cost. The manufacturing process of the conventional pneumatic tire includes a step of attaching a sidewall rubber. This step is performed by first extruding a side wall rubber having a predetermined cross-sectional shape (profile) in a band shape from an extruder, and sticking it to the outside of a carcass ply previously wound around a cylindrical molding drum. .

  The process of extruding the sidewall rubber with a predetermined profile also requires a lot of man-hours.In addition to this, the carcass ply is prepared in a cylindrical shape, so the process of attaching the sidewall rubber is unavoidable. The part that depends on work is large. Therefore, if the side wall rubber attaching process can be reduced, the manufacturing process can be further simplified.

  The present invention has been devised in view of the above circumstances, and is substantially constant on a raw carcass ply in which one side of an array of carcass cords is covered with a butyl topping rubber that also serves as an inner liner. A composite carcass ply is pre-formed by pasting a raw side wall rubber that has the thickness of, and then the composite carcass ply is wound on a molding drum, and then the raw side wall rubber is molded as well as the molding process. It is an object to provide a pneumatic tire manufacturing method and a pneumatic tire that can simplify the manufacturing process by eliminating the process of attaching the raw sidewall rubber on the drum, thereby improving the production efficiency and reducing the cost. It is said.

According to the first aspect of the present invention, in the ply main body portion that extends from the tread portion through the sidewall portion to the bead core of the bead portion and the inner surface forms the tire lumen surface, the inner side in the tire axial direction is around the bead core. A carcass made of a single carcass ply provided with a series of ply turn-up portions that are turned back to the outside, and a bead apex rubber that extends between the ply body portion and the ply turn-up portion radially outward from the bead core. A pneumatic tire manufacturing method comprising at least a sidewall rubber forming an outer surface of the sidewall portion, and a chafer rubber forming a bottom surface and an outer surface of the bead portion,
In the carcass ply, the inner topping rubber on the inner surface side forming the tire cavity surface of the topping rubber covering the inner and outer sides of the carcass cord array is made of butyl rubber, and the outer topping rubber on the outer surface side is made of non-butyl rubber. As it is formed,
A composite carcass ply forming step of forming a composite carcass ply by attaching a sheet-like raw sidewall rubber having a substantially constant thickness to the outer surface of the raw carcass ply before vulcanization of the carcass ply;
Winding the composite carcass ply around the outer peripheral surface of the molding drum to form a cylindrical composite carcass ply wound body ,
The raw side wall rubber is composed of an endogenous side rubber part adhered to the outer surface of the raw carcass ply and an exogenous side rubber part disposed on the outside thereof, and the rubber hardened rubber after vulcanization of the endogenous side rubber part. Is made larger than the rubber hardness after vulcanization of the exogenous side rubber part,
The endogenous side rubber portion is an upper endogenous side rubber portion disposed in a range including the upper portion in the radial direction of the sidewall portion and the buttress portion, and
It consists of a lower endogenous side rubber part arranged in a range from the lower part in the radial direction of the sidewall part to the bead part,
And the rubber hardness of the upper inner side rubber part where the upper endogenous side rubber part is vulcanized is smaller than the rubber hardness of the lower inner side rubber part where the lower endogenous side rubber part is vulcanized. It is the manufacturing method of the pneumatic tire characterized.

  The invention according to claim 2 is the method for producing a pneumatic tire according to claim 1, wherein the raw side wall rubber is made of a rubber sheet having a thickness of 1.5 to 3.0 mm.

According to a third aspect of the present invention , the endogenous side rubber part is made of a rubber having a durometer A hardness of 70 to 110 ° of the vulcanized inner side rubber part, and the exogenous side rubber part is vulcanized. durometer a hardness of the outer side rubber portion is a method of manufacturing a pneumatic tire according to claim 1, characterized in that it consists of 50-70 ° of the rubber.

According to a fourth aspect of the present invention, the upper endogenous side rubber portion is made of the same rubber composition material as the raw chafer rubber, and the lower endogenous side rubber portion is made of the same rubber composition as the raw bead apex rubber. The method for manufacturing a pneumatic tire according to claim 1 .

According to a fifth aspect of the present invention, in the composite carcass ply forming step, a sheet-shaped raw chafer rubber having a substantially constant thickness is formed on an inner surface of the raw carcass ply, and an outer end of the raw carcass ply is formed on the inner surface of the raw carcass ply. The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, further comprising a process of sticking with an overhanging portion protruding from an end edge .

The invention described in claim 6 is the pneumatic tire characterized by vulcanization molding the green tire by any of a method of manufacturing a pneumatic tire according to claim 1 to 5.

According to a seventh aspect of the present invention, the radial height of the bead apex rubber from the bead base line is 5% to 35% of the tire cross-section height, and the ply turn-up portion is formed of the bead apex rubber. The pneumatic tire according to claim 6, wherein the pneumatic tire terminates at an outer side surface .

The invention according to claim 8, wherein the sidewall rubber, the radially inner end, said ply main body portion, according to claim 6 or 7, wherein the terminating between said bead apex rubber This is a pneumatic tire.

According to a ninth aspect of the present invention, the chafer rubber is disposed so as to cover a radially inner end portion of the ply main body portion, a ply folded portion, a bead apex rubber, and a bead portion side of the sidewall rubber. A pneumatic tire according to claim 6-8 .

In the invention according to claim 10, the ply main body part that extends from the tread part through the sidewall part to the bead core of the bead part and whose inner surface forms the tire cavity surface is provided around the bead core from the inside in the tire axial direction. A carcass formed of a single carcass ply provided with a series of ply turn-up portions folded back toward each other, a bead apex rubber extending radially outward from the bead core through the ply main body portion and the ply turn-up portion, and the side A pneumatic tire comprising at least a sidewall rubber forming an outer surface of the wall portion and a chafer rubber forming a bottom surface and an outer surface of the bead portion;
In the carcass ply, the inner topping rubber on the inner surface side forming the tire cavity surface of the topping rubber covering the inner and outer sides of the carcass cord array is made of butyl rubber, and the outer topping rubber on the outer surface side is made of non-butyl rubber. As it is formed,
The sidewall rubber is composed of an inner side rubber portion adhered to the outer surface of the carcass ply and an outer side rubber portion disposed on the outer side thereof, and the rubber hardness of the inner side rubber portion is determined by vulcanization of the outer side rubber portion. Greater than the rubber hardness after
The inner side rubber part is an upper inner side rubber part disposed in a range including the upper part in the radial direction of the sidewall part and the buttress part, and
It consists of the lower inner side rubber part arranged in the range from the lower part in the radial direction of the sidewall part to the bead part,
And rubber hardness of the inner side rubber portion on the is empty pneumatic tire you wherein the smaller rubber hardness of the Shimonouchi side rubber portion.

The invention according to claim 11 is characterized in that the durometer A hardness of the inner side rubber portion is 70 to 110 ° and the durometer A hardness of the outer side rubber portion is 50 to 70 °. 10. The pneumatic tire according to 10 .

  The dimensions of each part of the tire, such as the tire cross-section height, are values specified when the bead part is held in accordance with the rim width specified by the tire size in a non-rim assembled state unless otherwise specified. And ,

  According to the present invention, it is possible to simplify the manufacturing process by eliminating the process of extruding the raw sidewall rubber in a complicated shape and attaching the raw sidewall rubber on the molding drum. Reduction can be achieved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a case where a pneumatic tire 1 manufactured by the manufacturing method of the present invention is a tubeless tire for a passenger car.

  The pneumatic tire 1 of the present embodiment includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer disposed on the outer side in the tire radial direction and inside the tread portion 2. 7 is provided. The pneumatic tire 1 includes a tread rubber Tg provided outside the belt layer 7 and forming the outer surface of the tread portion 2, and a sidewall rubber Sg provided outside the carcass 6 and forming the outer surface of the sidewall portion 3. A chafer rubber Cg provided on the bead portion 4 and having a bottom surface and an outer surface, and a bead apex rubber Bg provided on the bead portion 4 and rising from the bead core 5 are arranged.

  The belt layer 7 includes at least two belt plies 7A and 7B in this example, in which high-strength belt cords such as steel cords are arranged at an angle of, for example, 10 to 45 ° with respect to the tire circumferential direction. Each belt ply 7A, 7B is placed on the inside and outside in the radial direction with the direction of the inclination of the cord being different so that the belt cords cross each other, thereby increasing the belt rigidity and reinforcing the overall width of the tread portion 2. To do.

  The carcass 6 includes a single carcass ply 6A in which carcass cords are arranged at an angle of, for example, 85 to 90 degrees with respect to the tire circumferential direction. In this example, a polyester cord is used as the carcass cord. However, in addition to this, an organic fiber cord such as nylon, rayon, aramid, vinylon, or a steel cord can be used as necessary.

  The carcass ply 6 </ b> A includes a series of ply folding portions 6 b that are folded back from the inside in the tire axial direction around the bead core 5 on both sides of the ply main body portion 6 a that extends between the bead cores 5 and 5. The tire 1 is constituted by a so-called inner linerless in which the inner surface of the ply main body portion 6a forms a tire lumen surface. Further, a bead apex rubber Bg made of hard rubber is provided between the ply main body 6a and the ply turn-up portion 6b so as to taper out from the bead core 5 in the radial direction of the tire. Ensures bead rigidity.

  Here, in the bead apex rubber Bg, the height h1 in the radial direction from the bead base line BL is set to be as low as 5% to 35% of the tire cross-section height h0. This is because in the tire 1 manufactured by the manufacturing method of the present invention, the height h2 in the radial direction of the chafer rubber Cg needs to be larger than the height h1. Therefore, if the height h1 exceeds 35% of the tire cross-section height h0, the chafer rubber Cg approaches the maximum width position M where the surface distortion during tire deformation is large. Tend to invite. Conversely, if the height h1 is smaller than 5% of the tire cross-section height h0, the bead rigidity becomes insufficient.

  In addition, as for the durometer A hardness Hsb of the bead apex rubber Bg, the range of 70-110 degrees is employ | adopted similarly to the conventional tire. The ply turn-up portion 6b is terminated at the outer surface of the bead apex rubber Bg, and preferably terminated at a lower position than the upper end (not shown) of the rim flange, thereby suppressing damage at the outer end of the ply turn-up portion 6b. is doing.

  Further, the carcass ply 6A is formed by covering the inside and outside of the array of carcass cords 10 with a topping rubber 12 as shown in FIG. The inner topping rubber 12i is made of butyl rubber, and the outer topping rubber 12o on the outer surface side is made of non-butyl rubber.

  Since the butyl rubber is excellent in air impermeability, the inner topping rubber 12i also functions as a conventional inner liner. Therefore, since it is not necessary to provide an inner liner separately from the carcass ply 6A, the tire weight is reduced. Further, since butyl rubber tends to have low adhesive force, non-butyl rubber is used for the outer topping rubber 12o that forms an adhesive surface with the side wall rubber Sg.

  In this specification, “butyl rubber” is rubber containing 10 parts by weight or more of butyl rubber and / or a derivative thereof in 100 parts by weight of a rubber polymer, and “non-butyl rubber” Defined as rubber. Derivatives of butyl rubber (IIR) include chlorinated butyl rubber obtained by reacting butyl rubber with chlorine, bromine and the like, and halogenated butyl rubber including brominated butyl rubber. In the butyl rubber, if the content of butyl rubber or a derivative thereof is not 10 parts by weight or more as described above, it is difficult to exert a sufficient internal pressure holding performance. From such a viewpoint, butyl rubber and / or its The content of the derivative is desirably 30 parts by weight or more.

  The butyl rubber can contain one or more diene rubbers such as natural rubber (NR), butadiene rubber (BR), and styrene butadiene rubber (SBR) as the balance of the rubber polymer. Moreover, various fillers (for example, reinforcing agents such as carbon black, vulcanizing agents, vulcanization accelerators, and softening agents) are added to the rubber polymer as necessary, as in general topping rubbers. The non-butyl rubber is not particularly limited, but desirably contains 95 parts by weight or more, more preferably 100 parts by weight of the diene rubber as a rubber polymer.

  Next, the sidewall rubber Sg disposed outside the carcass ply 6A has a maximum thickness T in the range of about 1.5 to 3.0 mm in this embodiment. In addition to the reduction of the inner liner, the thin sidewall rubber Sg is very useful for reducing the weight of the tire.

  In order to reduce the thickness of the side wall rubber Sg as described above, a rubber having a hardness capable of ensuring rigidity is required. However, if it is too hard, the flexibility of the side wall portion 3 is impaired. In addition to deterioration in comfort, crack resistance is reduced, and cracks are likely to occur on the tire surface early.

  Accordingly, in this example, the sidewall rubber Sg is formed in a two-layer structure including an inner side rubber portion 17 adhered to the carcass ply 6A and an outer side rubber portion 18 disposed on the outer side. At this time, the rubber hardness of the inner side rubber portion 17 is larger than the rubber hardness of the outer side rubber portion 18, and preferably, the durometer A hardness Hsi of the inner side rubber portion 17 is in the range of 70 to 110 ° and the outer The durometer A hardness Hso of the side rubber portion 18 is in the range of 50 to 70 °.

  Thereby, riding comfort and crack resistance are satisfied while securing an appropriate rigidity to the sidewall portion 3. That is, the hard inner side rubber part 17 secures the rigidity of the side wall part 3 together with the carcass ply 6A, and on the other hand, the soft outer side rubber part 18 secures an appropriate flexibility, relaxes and absorbs large surface strain, and improves crack resistance. Can be improved.

  If the hardness Hsi and Hso are out of the respective ranges, the effect cannot be exhibited sufficiently. From such a viewpoint, the hardness Hsi of the inner side rubber portion 17 has a lower limit value of 80 ° or more and an upper limit value. Is preferably 100 ° or less, and in the outer side rubber portion 18, the lower limit value of the hardness Hso is more preferably 55 ° or more and the upper limit value is more preferably 65 ° or less.

  In addition, the thickness Ti of the inner side rubber portion 17 and the thickness To of the outer side rubber portion 18 are substantially the same in the present embodiment, but the thickness ratio (Ti / To) is, for example, 0.7 to It can be appropriately changed within a range of about 1.3.

  As conceptually showing the bead portion 4 in FIG. 3, the side wall rubber Sg has a radially inner end portion sandwiched between the ply body portion 6a and the bead apex rubber Bg and terminates. ing. Particularly, in this example, the inner end portion 17e of the inner side rubber portion 17 protrudes radially inward from the outer side rubber portion 18, and the protruding inner end portion 17e is formed between the ply main body portion 6a and the bead apex rubber Bg. The case where it interposes is illustrated. In such a case, the rigidity step at the outer end Eb of the bead apex rubber Bg can be relaxed and the bead durability can be improved. Therefore, it is preferable to secure 10 mm or more of the tire axial width W1 of the overlapping portion 20 between the inner end portion 17e (inner side rubber portion 17) and the bead apex rubber Bg. It is also preferable to form the inner side rubber portion 17 with the same rubber composition material as the bead apex rubber Bg. The outer side rubber portion 18 terminates radially outward and in the vicinity of the outer end Eb of the bead apex rubber Bg.

  However, as shown in FIG. 4A, the inner end portion 18e of the outer side rubber portion 18 is interposed between the ply main body portion 6a and the bead apex rubber Bg, and the inner side rubber portion 17 is disposed at the outer end of the bead apex rubber Bg. 4B, the inner end portions 17e and 18e of the inner side rubber portion 17 and the outer side rubber portion 18 are connected to the ply body portion 6a and the bead apex as shown in FIG. 4B. It can also be interposed between the rubber Bg. Although not preferable from the viewpoint of the rigidity step, both the inner side rubber portion 17 and the outer side rubber portion 18 may be terminated radially outward and in the vicinity of the outer end Eb of the bead apex rubber Bg.

  Note that the radially outer end of the sidewall rubber Sg has an overlapping portion 21 (shown in FIG. 1) with the tire axial direction outer end 7e of the belt layer 7 and is interposed between the carcass 6. Yes. At this time, the inner side rubber portion 17 is terminated before the outer end portion 7e, and the overlapping portion 21 is formed by the soft outer side rubber portion 18 and the belt layer 7, whereby the stress concentration at the outer end portion 7e. Is preferable in order to relax the ply end peeling.

  Next, the chafer rubber Cg for preventing rim displacement is made of rubber that is softer than the bead apex rubber Bg and harder than the outer side rubber portion 18 and has excellent wear resistance and cut resistance. The chafer rubber Cg sequentially covers the inner end portion in the radial direction of the ply body portion 6a, the ply turn-up portion 6b, the bead apex rubber Bg, and the bead portion side of the side wall rubber Sg. Covering and protecting the wall 3.

  FIG. 5 schematically shows another embodiment of the pneumatic tire 1. In this example, the inner side rubber portion 17 of the side wall rubber Sg includes an upper inner side rubber portion 17U disposed in a range YU including the buttress portion 3B in the radial direction of the side wall portion 3 and the side wall portion 3. It is formed from a lower inner side rubber portion 17L arranged in a range YL from the lower portion in the radial direction to the bead portion 4. In this example, the case where a space is provided between the upper and lower inner side rubber portions 17U and 17L is illustrated, but the upper and lower inner side rubber portions 17U and 17L may be continuous in the radial direction.

  At this time, the rubber hardness of the upper inner side rubber portion 17U is smaller than the rubber hardness of the lower inner side rubber portion 17L, thereby preventing the occurrence of cut scratches received from the road surface and the tire deformation. It is possible to suppress cracking of the upper inner side rubber portion 17U itself due to repetition. Therefore, it is preferable that the durometer A hardness Hsi1 of the upper inner side rubber portion 17U is in the range of 70 to 95 °, and the durometer A hardness Hsi2 of the lower inner side rubber portion 17L is in the range of 85 to 110 °. By forming the inner side rubber portion 17U with the same rubber composition material as the chafer rubber Cg, the cut resistance can be further improved. The lower inner side rubber portion 17L is preferably formed of the same rubber composition material as the bead apex rubber Bg from the viewpoint of securing rigidity.

  The upper inner side rubber portion 17U has a radial height h3 from the bead base line BL at the radially outer end of 70 to 90% of the tire sectional height h0 and a radial width W2 of the tire sectional width. The height is preferably 25 to 40% of the height h0. The lower inner side rubber portion 17L has a radial height h4 from the bead base line BL at the radially outer end of 25 to 60% of the tire cross-sectional height h0. It overlaps with the apex rubber Bg with the overlapping portion 20.

  Next, a method for manufacturing such a pneumatic tire 1 will be described. In this manufacturing method, the composite carcass ply forming step (FIG. 8), the winding step (FIG. 10), the bead core setting step (FIG. 10), the bulging / folding step (FIG. 11), and the joining step (FIG. 11) shown below. The tire 1 shown in FIG. 1 is manufactured by forming the raw tire 36 (FIG. 11) by a raw tire forming process including a) and vulcanizing the raw tire 36 with a vulcanization mold as in the conventional case. To do.

  First, an unvulcanized raw carcass ply 30 for forming the carcass ply 6A is formed as shown in FIG. In this raw carcass ply 30, the inner surface side of the array of carcass cords 10 is covered with the raw topping rubber 32 i made of the butyl rubber also serving as an inner liner, and the outer surface side is covered with the raw topping rubber 32 o of non-butyl rubber. It is formed by. This process is merely a change of the rubber material in the topping process that has been automated in the past, and is performed without any manual intervention. Therefore, the productivity is not particularly deteriorated by this process. In addition, since an inner liner that is separate and independent from the raw carcass ply 30 can be eliminated, there is no need for a process for preparing an inner liner rubber sheet separate from the carcass ply or a process for winding around a molding drum as in the prior art. The manufacturing process can be simplified.

In the present embodiment, the thickness t1 of the raw topping rubber 32i of butyl-based, but the thickness t2 of the raw topping rubber 32o non butyl type are exemplified as may be formed by substantially the same, e.g. As shown in FIG. 7, the thicknesses t1 and t2 can be different. In the example of FIG. 7, since only the raw topping rubber 32o having excellent adhesiveness is in contact with the array of the carcass cord 10, damage such as rubber peeling of the carcass cord 10 can be prevented, and the durability of the carcass 6 is improved. To help.

  The sum (t1 + t2) of the thicknesses t1 and t2 is preferably at least twice the outer diameter d of the carcass cord 10, more preferably at least 2.5 times, and the upper limit is preferably at most 5 times, more preferably 4 times or less is desirable. If the sum of the thicknesses (t1 + t2) exceeds 5 times the outer diameter d of the carcass cord 10, it is disadvantageous for weight reduction. Conversely, if it is less than 2 times, the ply strength tends to be insufficient.

  Further, the thickness t1 of the raw topping rubber 32i is preferably 0.5 mm or more, and more preferably 0.6 mm or more in order to improve air impermeability. However, if the thickness t1 is too large, an increase in weight is caused. Therefore, the upper limit is preferably 1.4 mm or less, and more preferably 1.2 mm or less.

  Next, as shown in FIG. 8, unvulcanized raw sidewall rubber Nsg for forming sidewall rubber Sg having a substantially constant thickness is pasted on the outer surface of the sheet-like raw carcass ply 30. The composite carcass ply 31 is formed (composite carcass ply forming step).

  As described above, the raw side wall rubber Nsg is a sheet body having a thickness of 1.5 to 3.0 mm. In this example, the raw side rubber Nsg is formed of a hard side rubber part 37 for forming the hard inner side rubber part 17, and soft. And an exogenous side rubber portion 38 for forming the outer side rubber portion 18. The raw side wall rubber Nsg is affixed at a symmetrical position with the center line CL of the raw carcass ply 30 as the center. The position of the raw side wall rubber Nsg is from the outer end 7e of the belt layer 7 to the bead apex. It is set so as to include at least a range corresponding to a region reaching the radially outer end Eb of the rubber Bg. In this example, as shown in an enlarged view in FIG. 9, the exogenous side rubber portion 38 has an endogenous side rubber portion 37 so that the overlapping portion 21 can be formed on the inner end side in the drum axial direction of the raw sidewall rubber Nsg. The inner side rubber portion 37 protrudes more inward in the drum axis direction than the exogenous side rubber portion 38 so that the overlapping portion 20 can be formed on the end side of the raw side wall rubber Nsg in the drum axis direction. It protrudes outward in the direction.

  In this example, as the composite carcass ply forming step, an unvulcanized raw chafer rubber Ncg for forming the chafer rubber Cg is stuck to the inner surface of the raw carcass ply 30 in addition to the sticking of the raw sidewall rubber Nsg. The thing including a process is illustrated. The raw chafer rubber Ncg is also formed of a sheet body having a substantially constant thickness, and has an overhang portion 23 protruding from the edge of the raw carcass ply 30 at the outer end in the drum axial direction. Worn.

  In this composite carcass ply forming step, the raw carcass ply 30, the raw side wall rubber Nsg, and the raw chafer rubber Ncg are sheet bodies each having a constant thickness, and therefore can be automatically attached using a known application device. Therefore, it is not necessary to manually attach the raw sidewall rubber and the raw chafer rubber to the raw carcass ply wound in a cylindrical shape as in the prior art, and the productivity can be improved. Furthermore, the raw sidewall rubber Nsg and the raw chafer rubber Ncg are not extrusion molding having a complicated cross-sectional shape as in the past, but are made of a sheet body having a constant thickness, so that the molding process itself can be greatly simplified, and productivity is improved. Can be further improved.

  Next, as shown in FIG. 10, the composite carcass ply 31 is wound around the outer peripheral surface of the forming drum D (one turn) to form a cylindrical composite carcass ply wound body 42 (winding step). . In this example, the forming drum D is a so-called single stage drum, and the winding process, bead core setting process, bulging / folding process, and joining process are performed on the single drum D. However, a so-called two-stage method can also be adopted.

  Next, a raw bead core assembly 33 formed by previously bonding a raw bead apex rubber Nbg to the bead core 5 is inserted into the composite carcass ply wound body 42 from both outer end sides in the drum axial direction. The joined body 33 is set at the position of the overlapping region 24 between the raw carcass ply 30 of the composite carcass ply wound body 42 and the raw chafer rubber Ncg (bead core setting step).

  After that, as shown in FIG. 11, the composite carcass ply wound body 42 includes an extending portion 25 that protrudes outward in the drum axial direction from the raw bead core assembly 33, and includes the raw chafer rubber overhanging portion 23. A folded portion 26 that is folded around the bead core assembly 33 is formed, and the bead cores 5 and 5 are bulged in a toroid shape to form a raw tire main portion 34 (a bulging / folding step).

  At this time, a raw tread ring 35 made of a tread member including a raw belt layer and a raw tread rubber Ntg waits in advance on the radially outer side of the composite carcass ply wound body 42 to bulge into the toroidal shape. Accordingly, the raw tire main portion 34 and the raw tread ring 35 are joined by pressure welding to form a raw tire 36 (joining step). And the tire 1 can be manufactured by vulcanizing-molding this raw tire 36 with a vulcanization mold according to the custom.

  In the case of the tire of FIG. 5, as shown in FIG. 12, the endogenous side rubber portion 37 in the raw sidewall rubber Nsg is replaced with the upper endogenous side rubber portion 37U for forming the upper inner rubber portion 17U. And the lower endogenous side rubber part 37L for forming the lower inner side rubber part 17L.

  As described above, the particularly preferable embodiment of the present invention has been described in detail. However, the present invention is not limited to the illustrated embodiment, and can be applied not only to passenger cars but also to various categories of tires such as motorcycles and trucks. However, the present invention can be implemented with various modifications. Further, the butyl-based inner topping rubber 12i does not have to be disposed on the entire inner surface side of the array of the carcass cords 10, but is limited to the range that forms the tire cavity surface, and non-butyl-based rubber is formed in the other portions. It can also be used.

  A passenger car radial tire (size: 195 / 65R15) having the basic structure shown in FIG. 1 was prototyped (Example tire) according to the method of the present invention, and its production cost, internal pressure retention performance, steering stability, and durability were evaluated. . For comparison, a comparative example tire in which the inner liner is formed of a sheet different from the carcass ply, and the side wall rubber and the chafer rubber are wound on a drum to form a green tire was manufactured and subjected to the same test. .

The common specifications of the example tire and the comparative example tire are as follows.
Number of carcass plies: 1 Carcass cord: Polyester, 1100 dtex / 2
Number of drives: 61 (5 / 5cm)
Carcass cord angle: 90 degrees (against tire equator)
Belt layer: Two-ply steel cord pread rubber: 63 degree durometer bead apex: 92 degree durometer Chaefa rubber: 70 degree durometer A test method is as follows.

<Manufacturing cost>
The manufacturing cost required to manufacture one tire is indicated by an index with Comparative Example 1 as 100. The smaller the value, the smaller the manufacturing cost and the better.

<Internal pressure retention performance>
The test tire was assembled on a rim (6 × 15 JJ), filled with an internal pressure of 200 kPa, and allowed to stand for 30 days, and the reduction rate (%) of the internal pressure was examined. The smaller the value, the better the internal pressure retention performance.

<Steering stability>
Each test tire is mounted on all wheels of a domestic FF passenger car with a displacement of 2000cc under the conditions of rim (6 x 15 JJ) and internal pressure (200 kPa), running on a dry paved road test course, straight running, turning Stability, vehicle behavior during braking, etc. were comprehensively determined by a 10-point method based on sensory evaluation by a professional driver. The larger the value, the better.

<Durability>
Each test tire was run on a drum tester at a speed of 80 km / H under the conditions of a rim (6 × 15 JJ) and an internal pressure (200 kPa), and the running distance until the tire broke was examined. The evaluation is indicated by an index with the travel distance of Comparative Example 1 as 100, and the larger the numerical value, the better. Table 1 shows the test results.

  As a result of the test, it can be confirmed that the tire of the example greatly reduces the tire weight and the manufacturing cost as compared with Comparative Example 1. In addition, it can be confirmed that the internal pressure holding performance, durability, and steering stability exhibit the same performance as Comparative Example 1.

It is sectional drawing which shows one Embodiment of the pneumatic tire manufactured by the manufacturing method of this invention. It is the A section enlarged view. It is sectional drawing which shows a bead part notionally. (A), (B) is sectional drawing which shows the structure of the inner-end part of sidewall rubber. It is sectional drawing which shows other embodiment of a pneumatic tire. It is sectional drawing which shows an example of a raw carcass ply. It is sectional drawing which shows the other example of a raw carcass ply. It is a fragmentary perspective view which shows an example of a composite carcass ply. It is sectional drawing which expands and shows a part of composite carcass ply. It is a diagram explaining a winding process and a bead core setting process. It is a diagram explaining a swelling / folding process and a joining process. It is sectional drawing which expands and shows a part of composite carcass ply of another example.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Carcass ply 6a Ply main part 6b Ply folding | turning part 10 Carcass cord 12 Topping rubber 12i Inner topping rubber 12o Outer topping rubber 17 Inner side rubber part 17U On Inner side rubber portion 17L Lower inner side rubber portion 18 Outer side rubber portion 30 Raw carcass ply 31 Compound carcass ply 37 Endogenous side rubber portion 37U Endogenous side rubber portion 37L Lower inner side rubber portion 38 Exogenous side rubber portion 42 Composite carcass ply winding Round Bg Bead apex rubber Cg Chefa rubber Sg Side wall rubber Nbg Raw bead apex rubber Ncg Raw chafa rubber Nsg Raw side wall rubber

Claims (11)

A series of ply turn-up parts that are folded back from the inner side to the outer side in the tire axial direction around the bead core, on the ply main body part that extends from the tread part through the sidewall part to the bead core of the bead part and the inner surface forms the tire cavity surface. A carcass made of a single carcass ply provided on a bead, a bead apex rubber extending radially outward from the bead core through the ply main body portion and the ply folded portion, and a side wall rubber forming the outer surface of the side wall portion And a manufacturing method of a pneumatic tire comprising at least a chafer rubber forming a bottom surface and an outer surface of the bead portion,
In the carcass ply, the inner topping rubber on the inner surface side forming the tire cavity surface of the topping rubber covering the inner and outer sides of the carcass cord array is made of butyl rubber, and the outer topping rubber on the outer surface side is made of non-butyl rubber. As it is formed,
A composite carcass ply forming step of forming a composite carcass ply by attaching a sheet-like raw sidewall rubber having a substantially constant thickness to the outer surface of the raw carcass ply before vulcanization of the carcass ply;
Winding the composite carcass ply around the outer peripheral surface of the molding drum to form a cylindrical composite carcass ply wound body ,
The raw side wall rubber is composed of an endogenous side rubber part adhered to the outer surface of the raw carcass ply and an exogenous side rubber part disposed on the outside thereof, and the rubber hardened rubber after vulcanization of the endogenous side rubber part. Is made larger than the rubber hardness after vulcanization of the exogenous side rubber part,
The endogenous side rubber portion is an upper endogenous side rubber portion disposed in a range including the upper portion in the radial direction of the sidewall portion and the buttress portion, and
It consists of a lower endogenous side rubber part arranged in a range from the lower part in the radial direction of the sidewall part to the bead part,
And the rubber hardness of the upper inner side rubber part where the upper endogenous side rubber part is vulcanized is smaller than the rubber hardness of the lower inner side rubber part where the lower endogenous side rubber part is vulcanized. A method for producing a pneumatic tire.   The method for manufacturing a pneumatic tire according to claim 1, wherein the raw sidewall rubber is made of a rubber sheet having a thickness of 1.5 to 3.0 mm. The endogenous side rubber part is made of a rubber having a durometer A hardness of 70 to 110 ° of the vulcanized inner side rubber part, and the exogenous side rubber part has a durometer A hardness of the vulcanized outer side rubber part. 2. The method for producing a pneumatic tire according to claim 1 , wherein the pneumatic tire is made of 50 to 70 [deg.] Rubber . Raw side rubber portions of the above are made from raw chafer rubber the same rubber material, and the Shimonouchi raw side rubber portions, according to claim 1, characterized in that it consists of the same rubber composition as the raw bead apex rubber Method of manufacturing a pneumatic tire. The composite carcass ply forming step has a sheet-like raw chafer rubber having a substantially constant thickness on the inner surface of the raw carcass ply, and an overhanging portion that protrudes from the edge of the raw carcass ply. The manufacturing method of the pneumatic tire in any one of Claims 1-4 including the process to stick and stick . A pneumatic tire obtained by vulcanizing and molding a raw tire produced by the method for producing a pneumatic tire according to claim 1 . The bead apex rubber has a radial height from a bead base line of 5% to 35% of a tire cross-section height, and the ply turn-up portion terminates at an outer surface of the bead apex rubber. The pneumatic tire according to claim 6. The pneumatic tire according to claim 6 or 7 , wherein the sidewall rubber has a radially inner end portion that terminates between the ply main body portion and the bead apex rubber . The chafer rubber is claim 6 to 8, a radially inner end portion of the ply main body portion, and a ply turnup portion, and a bead apex rubber, characterized in that arranged over the bead portion of the side wall rubber the pneumatic tire according to. A series of ply turn-up parts that are folded back from the inner side to the outer side in the tire axial direction around the bead core, on the ply main body part that extends from the tread part through the sidewall part to the bead core of the bead part and the inner surface forms the tire cavity surface. A carcass made of a single carcass ply provided on a bead, a bead apex rubber extending radially outward from the bead core through the ply main body portion and the ply folded portion, and a side wall rubber forming the outer surface of the side wall portion And a pneumatic tire comprising at least a chafer rubber forming a bottom surface and an outer surface of the bead portion,
In the carcass ply, the inner topping rubber on the inner surface side forming the tire cavity surface of the topping rubber covering the inner and outer sides of the carcass cord array is made of butyl rubber, and the outer topping rubber on the outer surface side is made of non-butyl rubber. As it is formed,
The sidewall rubber is composed of an inner side rubber portion adhered to the outer surface of the carcass ply and an outer side rubber portion disposed on the outer side thereof, and the rubber hardness of the inner side rubber portion is determined by vulcanization of the outer side rubber portion. It is bigger than the rubber hardness after, and
The sidewall rubber, the radially inner end, said ply main body portion, the air-filled tire you characterized by terminating between said bead apex rubber. A series of ply turn-up parts that are folded back from the inner side to the outer side in the tire axial direction around the bead core, on the ply main body part that extends from the tread part through the sidewall part to the bead core of the bead part and the inner surface forms the tire cavity surface. A carcass made of a single carcass ply provided on a bead, a bead apex rubber extending radially outward from the bead core through the ply main body portion and the ply folded portion, and a side wall rubber forming the outer surface of the side wall portion And a pneumatic tire comprising at least a chafer rubber forming a bottom surface and an outer surface of the bead portion,
In the carcass ply, the inner topping rubber on the inner surface side forming the tire cavity surface of the topping rubber covering the inner and outer sides of the carcass cord array is made of butyl rubber, and the outer topping rubber on the outer surface side is made of non-butyl rubber. As it is formed,
The sidewall rubber is composed of an inner side rubber portion adhered to the outer surface of the carcass ply and an outer side rubber portion disposed on the outer side thereof, and the rubber hardness of the inner side rubber portion is determined by vulcanization of the outer side rubber portion. Greater than the rubber hardness after
The inner side rubber part is an upper inner side rubber part disposed in a range including the upper part in the radial direction of the sidewall part and the buttress part, and
It consists of the lower inner side rubber part arranged in the range from the lower part in the radial direction of the sidewall part to the bead part,
And rubber hardness of the inner side rubber portion on the can, air-filled tire you wherein the smaller rubber hardness of the Shimonouchi side rubber portion.

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