Tire and tire manufacturing method

Abstract

To provide a tire whose conductive member is suppressed from being damaged, and a tire manufacturing method that can suppress the conductive member from being damaged.SOLUTION: A conductive member 11 extending in a tire radial direction is not arranged in a dividing position corresponding area Z in any dividing position corresponding position of a plurality of sector mold dividing position corresponding positions Y. A tire manufacturing method according to the present invention includes a step of vulcanizing a green tire in a state where a conductive member is not arranged in a dividing position area in a dividing position of any sector mold of a plurality of sector molds.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tire and a method for manufacturing a tire. [Background technology]

[0002] For example, as described in Patent Document 1, a tire having a carcass made up of one or more carcass plies is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-20499 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for reduced rolling resistance in tires. To achieve this, the amount of carbon in the covering rubber may be reduced, for example, to reduce the loss tangent of the covering rubber in the carcass ply. However, reducing the amount of carbon increases the electrical resistance of the covering rubber, which could potentially block the conductive path from the bead to the tread surface. In this case, it may be difficult for static electricity transmitted from the vehicle to the bead to escape from the tread surface to the road surface.

[0005] To address this issue, it is conceivable to form a conductive path by placing a conductive member inside the tire, thereby dissipating static electricity to the road surface.

[0006] However, if the conductive member is damaged (cut, etc.), the conductive path is lost, and static electricity cannot be released to the road surface.

[0007] Therefore, an object of the present invention is to provide a tire in which damage to conductive members is suppressed, and a method for manufacturing a tire in which damage to conductive members can be suppressed. [Means for solving the problem]

[0008] The gist and configuration of the present invention are as follows. (1) a pair of bead portions; a carcass consisting of one or more carcass plies toroidally spanning the pair of bead portions; a reinforcing member consisting of one or more reinforcing layers arranged on the tire radial outer side of the crown portion of the carcass; A tire including a conductive member extending in a tire radial direction, the conductive member extends from the tire radially inner end to the tire radially outer side at least to a position of any one of the one or more reinforcing layers that has conductivity, the tire has a plurality of corresponding split position positions corresponding to a plurality of sector mold split positions, When a tire circumferential direction region from the split position corresponding position to positions spaced apart by 1% of the tire circumference on both sides of the split position corresponding position in the tire circumferential direction is defined as a split position corresponding region, The tire, wherein the conductive member is not disposed within the split position corresponding area of ​​any of the split position corresponding positions among the plurality of split position corresponding positions.

[0009] Here, the "position corresponding to the split position" refers to a position corresponding to the split position between multiple sector molds that are divided circumferentially and used when manufacturing a tire, and since unvulcanized rubber flows into this position, it becomes the part where a ridge extending in the tire width direction is formed. Furthermore, the phrase "the conductive member is not disposed in the area corresponding to the split position" means that no part of the conductive member is disposed in the area corresponding to the split position.

[0010] (2) The tire according to (1) above, wherein the split position corresponding position is a portion where a ridge is formed.

[0011] (3) A method for manufacturing a tire comprising: a pair of bead portions; a carcass consisting of one or more carcass plies toroidally spanning the pair of bead portions; a reinforcing member consisting of one or more reinforcing layers arranged radially outward of a crown portion of the carcass; and a conductive member extending radially in the tire, wherein the conductive member extends radially outward from an inner end in the tire radial direction to at least the position of any one of the one or more reinforcing layers that has conductivity, When a region from a dividing position of a plurality of sector molds divided in the circumferential direction to a position spaced apart by 1% of the circumference of the green tire on both sides of the dividing position in the circumferential direction is defined as a dividing position region, a step of vulcanizing a green tire in a state in which the conductive member is not disposed within the division position area of ​​the division position of any of the sector molds among the plurality of sector molds. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a tire in which damage to conductive members is suppressed and a method for manufacturing a tire in which damage to conductive members can be suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram of a tire structure of a tire according to one embodiment of the present invention. [Figure 2] 10 is a side view schematically showing the positional relationship between the conductive member and the split position corresponding area. FIG. [Figure 3] 3 is a cross-sectional view taken along the line AA′ of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0015] (tire) Fig. 1 is a schematic diagram of the tire structure of a tire according to one embodiment of the present invention. In this example, the tire 1 is a pneumatic tire. As shown in Fig. 1, the tire 1 includes a pair of bead portions 2, a carcass 3, a reinforcing member disposed radially outward of the carcass 3, and a tread portion 5.

[0016] A pair of bead cores 2a are embedded in the pair of bead portions 2, and bead fillers 2b are arranged on the radially outer sides of the bead cores 2a. The cross-sectional shape and material of the bead cores 2a are not particularly limited, and may be any of the structures normally used in tires. The bead fillers 2b may have a substantially triangular cross-section, but the cross-sectional shape of the bead fillers 2b is not limited to this example, and the material is not particularly limited either.

[0017] The carcass 3 is made up of one or more carcass plies, each of which includes a carcass body 3a that straddles a pair of bead cores in a toroidal shape and a carcass folded-up portion 3b that extends from the carcass body 3a and folds back around the bead cores 2a. In this embodiment, the carcass ply is made of organic fibers coated with rubber, and the coated rubber has a small loss tangent. This reduces the rolling resistance of the tire. Here, "loss tangent" refers to the ratio (E" / E') of the dynamic loss modulus E" to the dynamic storage modulus E', obtained using a dynamic tensile viscoelasticity measuring tester on a vulcanized rubber test piece having a thickness of 2 mm, a width of 5 mm, and a length of 20 mm, under conditions of a temperature of 60°C, a frequency of 52 Hz, an initial strain of 2%, and a dynamic strain of 1%. In this embodiment, the carcass ply is non-conductive (it does not function sufficiently as a conductive path to release static electricity inside the tire to the road surface).

[0018] Additionally, a rubber chafer (gum chafer) 6 is disposed on the outer side of the bead filler 2b in the tire width direction. The rubber chafer 6 covers the carcass folded-up portion 3b from the outer side in the tire width direction. The rubber chafer 6 is electrically conductive. The rubber chafer 6 is disposed in at least a part of the contact portion of the bead portion 2 with the rim.

[0019] A canvas chafer 7 is disposed around the bead core 2a. The canvas chafer 7 covers the inner side of the bead core 2a in the tire radial direction and both sides in the tire width direction. The canvas chafer 7 is electrically conductive. The canvas chafer 7 is made of a woven fabric and rubber impregnated into the woven fabric. The woven fabric is made of warp and weft threads, and the warp and weft threads are made of organic fibers.

[0020] As shown in Fig. 1, a squeegee rubber 8 is disposed on the radially inner side of the bead core 2a (in the illustrated example, on the radially inner side of the carcass folded-up portion 3b and on the radially inner side of the canvas chafer 7). This prevents contact between the carcass ply and the canvas chafer 7, thereby suppressing breakdowns due to friction. The squeegee rubber 8 is non-conductive.

[0021] Here, a reinforcing member consisting of one or more reinforcing layers is arranged on the tire radially outer side of the crown portion of the carcass 3. In the illustrated example, the reinforcing member includes a belt 4 consisting of two belt layers 4a and 4b, one belt reinforcing layer 9 arranged on the tire radially outer side of the belt 4, and a reinforcing rubber (tread undercushion) 10 arranged on the tire radially outer side of the belt reinforcing layer 9.

[0022] The belt layers 4a, 4b are made of plies of rubber-coated belt cords that are inclined (for example, at an inclination angle of 30 to 60 degrees) with respect to the tire circumferential direction so that they intersect with each other between the layers. The belt cords may be, for example, steel cords. The belt layers 4a, 4b are electrically conductive. In this example, there are two belt layers, but one or more layers may be used, and the inclination angle with respect to the tire circumferential direction is not limited to the above range.

[0023] The belt reinforcing layer 9 is made of a ply of rubber-coated cords extending in the tire circumferential direction. In this example, the belt layer 9 is a pair of layer layers that cover only the tire width direction ends of the belt 4. The cords can be, for example, steel cords. The belt reinforcing layer 9 is non-conductive. When the belt reinforcing layer 9 is a layer layer, the belt layer is not disposed except at positions corresponding to the belt ends, so that the tire width direction region between the pair of layer layers forms a conductive path. Note that in this example, the belt reinforcing layer 9 is a single layer layer, but it can also be made of two or more layers. For example, a so-called cap layer that covers the entire belt width can be further disposed between the belt 4 and the layer layer in the tire radial direction. Alternatively, only a cap layer can be disposed. In the case of a cap layer, it is conductive. Each reinforcing layer is either conductive to form a conductive path, or non-conductive but is disposed only in a portion in the tire width direction, so that the area where the reinforcing layer is not disposed becomes a conductive path. Note that in this embodiment, the tire 1 does not necessarily have to have the belt reinforcing layer 9. The belt reinforcing layer 9 can also be disposed on the inner side of the belt 4 in the tire radial direction.

[0024] In the illustrated example, the reinforcing rubber (tread undercushion) 10 is disposed between the tread portion 5 and the belt reinforcing layer 9 in the tire radial direction. The tread undercushion 10 is electrically conductive. The tread portion 5 is not electrically conductive. The tread portion 5 can have, for example, a so-called cap and base structure, in which a cap rubber is arranged on the radially outer side of a base rubber. A part of the tread portion 5 in the tire width direction serves as an antenna rubber 5a. The antenna rubber 5a is electrically conductive. The antenna rubber 5a can be arranged continuously in the tire circumferential direction, or can be arranged intermittently.

[0025] Here, the tire 1 of this embodiment further includes a conductive member 11 extending in the tire radial direction. In this example, the conductive member 11 is a conductive fiber member. The conductive fiber member can be, for example, a mixture of cotton fiber and SUS fragments twisted together. This allows for a lightweight and conductive fiber. For weight reduction, it is preferable for the fiber to consist of only one strand.

[0026] In this example, the tire radially inner end of the conductive member 11 is located at the tire radially outer end of the rubber chafer 6 or, as shown in the figure, in a tire radial region that is radially inward of the tire radially outer end of the rubber chafer 6. This allows electrical contact between the rubber chafer 6 and the tire radially inner end of the conductive member 11. The conductive member 11 also extends from the tire radially inner end to the tire radially outer side, at least to the position of one of the one or more reinforcing layers that has conductivity. In the embodiment shown in FIG. 1 , the tire 1 has a pair of conductive members 11, one on each half of the tire width direction, with the tire equatorial plane as the boundary. Therefore, each conductive member 11 has a tire radially outer end. The tire radially outer end of the conductive member 11 terminates at the end of one of the one or more reinforcing layers that has conductivity (the belt layer 4a in the illustrated example). That is, the outer end in the tire radial direction of the conductive member 11 terminates in a region in the tire radial direction between the crown portion of the carcass 3 and the innermost conductive reinforcing layer in the tire radial direction (in the illustrated example, the belt layer 4a) among the one or more reinforcing layers, thereby electrically connecting the outer end in the tire radial direction of the conductive member 11 and the belt 4a.

[0027] Here, the tire of this embodiment has a plurality of corresponding split position positions corresponding to a plurality of sector mold split positions. The corresponding split position positions are portions where ridges are formed. FIG. 2 is a side view schematically showing the positional relationship between the conductive member and the split position corresponding area. In FIG. 2, an area Y that covers the entire area in the tire radial direction and the entire area in the tire width direction at the tire circumferential direction positions that correspond to the split positions is indicated by a rectangular dashed line. As shown in Fig. 2, the tire circumferential region (the region spanning the entire tire radial direction and the entire tire width direction) from the split position corresponding position (in this example, from the center of the width of the ridge) to positions spaced apart by 1% of the tire circumference on both sides of the tire circumferential direction (along the tire outer surface) from the split position corresponding position (in this example, from the center of the width of the ridge) is defined as split position corresponding region Z. For simplicity, Fig. 2 shows one split position corresponding position and its corresponding split position corresponding region Z, but in reality, if a tire is manufactured using a sector mold divided into n (n≧2), there will be n split position corresponding positions Y and their corresponding split position corresponding regions Z. In this embodiment, the conductive member 11 is not disposed within the split position corresponding area Z of any of the multiple split position corresponding positions Y. In other words, in this tire 1, the conductive member 11 is disposed so as to avoid all of the multiple split position corresponding areas Z. The effects of the tire according to this embodiment will be described below.

[0028] The tire of this embodiment includes a conductive member 11 extending in the tire radial direction, and the conductive member 11 extends from the tire radially inner end to the tire radially outer side to at least the position of one of the one or more reinforcing layers that has conductivity, thereby forming a conductive path that allows static electricity to escape from the conductive member 11 to the road surface via the reinforcing layer. In the illustrated example, static electricity can escape from the rubber chafer 6 to the reinforcing layer and from the reinforcing layer to the road surface. Fig. 3 is a cross-sectional view taken along the line AA' in Fig. 2. As shown in Fig. 3, if a conductive member is disposed near a split position of the sector mold, stress from the inner surface of the tire to the outer surface is applied to the conductive member due to the flow of rubber during vulcanization, increasing the risk of damage (e.g., breakage) to the conductive member during vulcanization. This can occur at any of the multiple split positions present in the circumferential direction. Therefore, in this embodiment, the conductive member 11 is not disposed within the split position corresponding area Z of any of the multiple split position corresponding positions Y. This makes it possible to suppress damage to the conductive member 11.

[0029] The conductive member is preferably a conductive fiber member. This can suppress the weight increase due to the addition of the conductive member and suppress the increase in rolling resistance. In particular, it is preferable that the conductive fiber member be a mixture of cotton fiber and SUS fragments, which can be made lightweight and conductive.

[0030] (Tire manufacturing method) Next, a method for manufacturing a tire according to one embodiment of the present invention will be described. The method of this embodiment is a method for manufacturing a tire including a pair of bead portions, a carcass consisting of one or more carcass plies toroidally spanning the pair of bead portions, a reinforcing member consisting of one or more reinforcing layers arranged radially outward of a crown portion of the carcass, and a conductive member extending radially in the tire, the conductive member extending radially outward from the radially inner end of the tire to at least the position of one of the one or more reinforcing layers that has conductivity. Examples of tires to be manufactured are the same as those already described in the tire embodiment, and therefore will not be described again.

[0031] Here, the division position region is defined as the region extending from the division position of each of the multiple sector molds divided circumferentially (in this example, the widthwise center of the division position) to positions spaced 1% of the circumference of the green tire on both sides of the division position in the circumferential direction. The tire manufacturing method of this embodiment includes a step of vulcanizing the green tire in a state in which the conductive members are not positioned within the division position regions of any of the multiple sector molds. In other words, in the vulcanization step, the conductive members are positioned so as to avoid all of the multiple division position regions, and vulcanization is carried out in this position.

[0032] According to the tire manufacturing method of this embodiment, the conductive members are arranged to avoid the areas where stress is applied from the inner surface side to the outer surface side of the tire due to the rubber flow during vulcanization, as described above, so that a tire can be obtained in which damage (e.g., breakage) to the conductive members is suppressed.

[0033] In the case of the manufacturing method, the conductive member is preferably a conductive fiber member. This can suppress the weight increase due to the addition of the conductive member and suppress the increase in rolling resistance. In particular, it is preferable that the conductive fiber member is a mixture of cotton fiber and SUS fragments, which can be twisted together to make the product lightweight and conductive. Other steps, molds to be used, vulcanization equipment, etc. may be conventional.

[0034] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. In the above embodiments, a pair of conductive members has been illustrated, but the present invention is not limited to this case. One conductive member may be configured to extend continuously from one half of the tire width direction (for example, the tire radially outer end of the rubber chafer or a tire radially inner region of the rubber chafer in the tire radial direction) to the other half of the tire width direction (for example, the tire radially outer end of the rubber chafer or a tire radially inner region of the rubber chafer in the tire radial direction). In this case, the conductive member extends over the entire area of ​​one or more conductive reinforcing layers. This configuration also provides a structure that easily dissipates static electricity from the vehicle to the road surface. [Explanation of symbols]

[0035] 1: tire, 2: bead portion, 3: carcass, 4: belt, 5: Tread part, 6: Rubber chafer, 7: Canvas chafer, 8: squeegee rubber, 9: belt reinforcing layer, 10: tread undercushion, 11: Conductive material

Claims

1. a pair of bead portions; a carcass including one or more carcass plies toroidally straddling the pair of bead portions; a reinforcing member consisting of one or more reinforcing layers arranged on the tire radial outer side of the crown portion of the carcass; A tire including a conductive member extending in a tire radial direction, The conductive member is a conductive fiber member, and is a mixed twist of cotton fiber and SUS fragments, the fibrous member extends continuously from an inner end in the tire radial direction to an outer end in the tire radial direction, from the bead portion to at least a position of any one of the one or more reinforcing layers that has electrical conductivity, the tire has a plurality of corresponding split position positions corresponding to a plurality of sector mold split positions, When a tire circumferential direction region from the division position corresponding position to positions spaced apart by 1% of the tire circumference on both sides of the division position corresponding position in the tire circumferential direction is defined as a division position corresponding region, The tire, wherein the conductive member is not disposed within the split position corresponding area of ​​any of the split position corresponding positions among the plurality of split position corresponding positions.

2. The tire according to claim 1 , wherein the split position corresponding position is a portion where a ridge is formed.

3. a carcass including a pair of bead portions, one or more carcass plies toroidally straddling the pair of bead portions, a reinforcing member including one or more reinforcing layers arranged on the tire radially outer side of a crown portion of the carcass, and a conductive member extending in the tire radial direction, wherein the conductive member is a conductive fiber member obtained by intertwisting cotton fiber and SUS fragments, and the fiber member extends continuously from an inner end in the tire radial direction to the outer side in the tire radial direction, from the bead portions to at least a position of any one of the one or more reinforcing layers that has conductivity, When a region from a dividing position of a plurality of sector molds divided in the circumferential direction to a position spaced apart by 1% of the circumference of the green tire on both sides of the dividing position in the circumferential direction is defined as a dividing position region, a step of vulcanizing a green tire in a state in which the conductive member is not disposed within the division position area of ​​the division position of any of the sector molds among the plurality of sector molds.

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