JP2008049995A - Pneumatic tire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire and its manufacturing method capable of improving uniformity, without degrading productivity. <P>SOLUTION: A plurality of belt-like carcass members 11 long in the tire width direction, are juxtaposed in the tire peripheral direction. Since a plurality of layers of carcass layers are formed by superposing a part in the tire peripheral direction of the respective carcass members 11 on a part of the other carcass member 11 positioned in one in the tire peripheral direction, and superposing a part of the other carcass member 11 positioned in the other in the tire peripheral direction on the other part of the tire peripheral direction of the respective carcass members 11, a splice part of partially thickening the thickness in the tire radius direction in the tire peripheral direction, is not formed, and the carcass layers can be formed without causing a rigidity difference by the splice part. In this case, there is no need to highly accurately butt end surfaces of the carcass members like a butt splice. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire used for, for example, a passenger car, a truck, a bus, and the like and a manufacturing method thereof.

  In recent years, with the upsizing and quieting of automobiles, many performances are also demanded for tires, especially in order to reduce vibration and noise during running caused by tire non-uniformity in the circumferential direction, Improvement of uniformity is desired. Such deterioration of uniformity is caused by the splicing of the carcass layer that forms the skeleton of the tire by wrapping the end portions of the sheet-like carcass members together, and this may cause a difference in rigidity due to the splicing portion. Are known. In particular, when there are two or more carcass layers, there are two or more splice portions in the circumferential direction, which further increases the non-uniformity in the tire circumferential direction. In addition, there is also known one in which a carcass layer is formed by arranging a plurality of strip-like carcass members that are long in the tire width direction and arranged in the tire circumferential direction (see, for example, Patent Document 1). Even in this case, since the splice portion of each carcass member is wrapped, non-uniformity in the tire circumferential direction is generated as described above.

Therefore, by forming the carcass layer by a so-called butt splice that abuts the end portions of the carcass member without wrapping, a splice portion in which the thickness in the tire radial direction is partially increased in the tire circumferential direction is not formed. (See, for example, Patent Document 2).
JP 2006-514589 A Japanese Patent Laid-Open No. 5-221204

  However, the molding method using the butt splice has a problem that it requires advanced manufacturing technology and reduces productivity because peeling tends to occur unless the end faces of the carcass member are abutted with high precision.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a pneumatic tire capable of improving uniformity without reducing productivity and a method for manufacturing the same. .

  In order to achieve the above object, the present invention provides a pneumatic tire in which a carcass layer is formed by arranging a plurality of strip-like carcass members that are long in the tire width direction and arranged in the tire circumferential direction. A part of the carcass member in the tire circumferential direction overlaps a part of the other carcass member located on one side in the tire circumferential direction, and another carcass located on the other side in the tire circumferential direction on the other part in the tire circumferential direction of each carcass member It forms so that a part of member may overlap.

  As a result, a part of each carcass member in the tire circumferential direction overlaps with a part of the other carcass member located on one side in the tire circumferential direction, and a position on the other side in the tire circumferential direction on the other part in the tire circumferential direction of each carcass member. Since part of the other carcass members to be overlapped with each other, a splice portion in which the thickness in the tire radial direction is partially increased in the tire circumferential direction is not formed.

  In order to achieve the above object, the present invention provides a method for manufacturing a pneumatic tire in which a carcass layer is formed by arranging a plurality of strip-like carcass members long in the tire width direction side by side in the tire circumferential direction. A part of the member in the tire circumferential direction is overlapped with a part of another carcass member located on one side in the tire circumferential direction, and another carcass located on the other side in the tire circumferential direction on the other part in the tire circumferential direction of each carcass member The carcass layer is formed by overlapping a part of the members.

  As a result, a part of each carcass member in the tire circumferential direction overlaps with a part of the other carcass member located on one side in the tire circumferential direction, and a position on the other side in the tire circumferential direction on the other part in the tire circumferential direction of each carcass member. Since the carcass layer is formed by overlapping some of the other carcass members, a splice portion in which the thickness in the tire radial direction is partially increased in the tire circumferential direction is not formed.

  According to the present invention, since the splice portion in which the thickness in the tire radial direction is partially thick in the tire circumferential direction is not formed, the carcass layer can be formed without causing a rigidity difference due to the splice portion. . Therefore, uniformity can be improved, and vibration during traveling caused by non-uniformity in the tire circumferential direction can be reliably reduced. In this case, unlike the butt splice, it is not necessary to abut the end face of the carcass member with high accuracy, so there is an advantage that productivity is not reduced.

  1 to 5 show a first embodiment of the present invention. FIG. 1 is a partial front sectional view of a pneumatic tire. FIG. 2 is a side sectional view showing a part of a carcass member in an intermediate process. 4 is a plan view thereof, and FIG. 5 is a diagram showing test results.

  The pneumatic tire includes a tread portion 1 formed on the outer peripheral surface side, sidewall portions 2 formed on both sides in the width direction, and bead portions 3 formed on the tire radial direction inner side of the sidewall portions 2. A carcass layer 4 is formed between the left and right bead portions 3. That is, in this pneumatic tire, a sheet-like inner liner 10, a plurality of carcass members 11, and a plurality of belts 12 are overlapped on a forming drum and formed into a cylindrical shape. While forming in a toroidal shape so as to straddle between the bead members 13, both ends in the tire width direction of the carcass member 11 are rolled up from the periphery of the bead member 13 to the outer side in the tire width direction and folded back to the side wall portion 2 side. It is formed by sticking the tread member 14 and the sidewall member 15 to the outer peripheral surface.

  The inner liner 10 is made of a sheet-like rubber having airtightness, and is disposed on the inner peripheral surface side of the carcass member 11.

  Each carcass member 11 is formed by covering a plurality of carcass cords 11 a arranged in the tire circumferential direction with a sheet-like rubber, and is formed by a belt-like member that is long in the tire width direction. That is, each carcass member 11 forms the carcass layer 4 by being arranged in the tire circumferential direction.

  Each belt 12 is formed by covering a reinforcing wire made of a steel cord, high-strength fiber, or the like with a sheet-like rubber material, and is arranged on the outer peripheral surface side of the carcass member 11 so as to overlap each other.

  The bead member 13 includes a bead core 13a formed by bundling wires such as metal wires and a bead filler 13b formed of rubber having a substantially triangular cross section. The bead filler 13b is disposed on the outer periphery of the bead core 13a.

  The tread member 14 is made of rubber formed by extrusion molding, and is disposed so as to cover the center side in the width direction of the carcass member 11 and the outer peripheral surface side of each belt 12. A groove 14a forming a predetermined tread pattern is formed on the outer peripheral surface of the tread member 14 during vulcanization molding.

  The sidewall member 15 is made of rubber formed by extrusion molding, and is disposed so as to cover both ends of the carcass member 11 in the tire width direction.

  Next, a method for manufacturing the pneumatic tire will be described. In addition, the process demonstrated below shows the shaping | molding process of the carcass layer 4, Since it is equivalent to the former, about another manufacturing process, it abbreviate | omits.

  That is, when the carcass layer 4 is formed, as shown in FIG. 2, a part of each carcass member 11 in the tire circumferential direction is overlapped with a part of the other carcass member 11 located at one side in the tire circumferential direction, Two parts of the carcass layer are formed by superimposing a part of the other carcass member 11 located on the other side in the tire circumferential direction on the other part in the tire circumferential direction of the carcass member 11 and forming the same in a cylindrical shape on a molding drum. 4 is formed. In this case, a splice portion is formed in which the thickness in the tire radial direction is partially increased in the tire circumferential direction by overlapping each carcass member 11 by a width W2 that is ½ of the width W1 in the tire circumferential direction. There is nothing to do. Further, as shown in FIG. 3, the carcass layer 4 is shifted every other predetermined length L in the tire radial direction with respect to the other carcass members 11 with respect to the positions of the longitudinal ends of some carcass members 11. Is molded by. As a result, when each carcass member 11 is folded back at a predetermined turn-up position TU, the end portions of the carcass members 11 are alternately arranged in the tire circumferential direction at two stages of turn-up heights T1 and T2 in the tire radial direction. Therefore, the stress generated at the folded end portion of the carcass layer 4 can be dispersed. In this case, if the length L for shifting the longitudinal end of each carcass member 11 in the tire radial direction is smaller than 10 mm, a sufficient stress dispersion effect cannot be obtained, and each length L is 10 mm or more. It is preferable to shift the carcass member 11. Each carcass member 11 has a width W1 in the tire circumferential direction of 30 mm or less, and is formed to have three or more carcass cords 11a.

  In FIG. 3, the end portion of each carcass member 11 is shifted in two stages in the tire radial direction. However, as shown in FIG. By shifting the length L of the other carcass members 11 in the tire radial direction by three stages, the carcass members 11 are arranged in the tire circumferential direction at three stages of turn-up heights T1, T2, and T3 in the tire radial direction. You may make it carry out, and you may make it shift in four steps or more.

  Here, as shown in FIG. 5, when the uniformity test and the low-pressure load endurance test were performed on the two types of Examples 1 and 2 of the present invention, the following results were obtained. In this test, tires having a tire size of 215 / 55R17 were used. In the comparative example, a single sheet-like carcass member was wrapped and spliced at one place in the circumferential direction, and two of them were formed to form two carcass layers. The turn-up height of each carcass layer was 78 mm and 18 mm. In Examples 1 and 2, carcass members each having a width of 20 mm in the tire circumferential direction are partially overlapped in the tire circumferential direction to form a carcass layer. In Example 1, the turnup height is 78 mm and 2 mm. Each carcass member is displaced so as to be in stages, and in the second embodiment, each carcass member is displaced so that the turnup height is in three stages of 78 mm, 48 mm, and 18 mm.

  In the uniformity test, RFV, LFV, and RRO are measured at an internal pressure of 200 kPa based on JIS D 4233, and the average value of 20 tires is evaluated using an index when a comparative example is 100. It was determined. The index is shown in parentheses in the figure.

  In the low-pressure load endurance test, a continuous running test is performed at an internal pressure of 120 kPa, and a comparative example of the running distance until the side wall is damaged is evaluated using an index when the conventional tire is set to 100. Judged as superior.

  As a result of the test, Examples 1 and 2 obtained better results than the comparative examples for RFV, LFV, and RRO of the uniformity test, and obtained better results than the comparative examples in the low-pressure load endurance test.

  Thus, according to the present embodiment, a plurality of strip-like carcass members 11 that are long in the tire width direction are arranged side by side in the tire circumferential direction, and a part of the tire circumferential direction of each carcass member 11 is on one side in the tire circumferential direction. A plurality of layers are formed by overlapping a part of the other carcass member 11 positioned and a part of the other carcass member 11 positioned on the other side in the tire circumferential direction on another part of the tire circumferential direction of each carcass member 11. Since the carcass layer 4 is formed, a splice portion in which the thickness in the tire radial direction is partially increased in the tire circumferential direction is not formed, and there is no difference in rigidity due to the splice portion. Can be formed. Therefore, uniformity can be improved, and vibration during traveling caused by non-uniformity in the tire circumferential direction can be reliably reduced. In this case, unlike the butt splice, it is not necessary to abut the end face of the carcass member with high accuracy, so there is an advantage that productivity is not reduced.

  In addition, since the positions of the longitudinal ends of some of the carcass members 11 are shifted in the longitudinal direction (tire radial direction) with respect to the positions of the longitudinal ends of the other carcass members 11, the carcass layer 4 is folded back. It is possible to disperse the stress generated at the end portion, which is extremely advantageous for improving durability during low-pneumatic running, such as prevention of separation failure.

  In this case, since the length L of the longitudinal ends of some of the carcass members 11 deviates from the longitudinal ends of the other carcass members in the tire radial direction is 10 mm or more, the stress dispersion effect is It can be obtained sufficiently and is extremely advantageous for practical use.

  In addition, since each carcass member 11 is formed so that the width W1 in the tire circumferential direction is 30 mm or less, there is no deterioration in circumferential uniformity due to the width W1 of each carcass member 11 becoming too large. The uniformity improvement effect can be further enhanced.

  Furthermore, since each carcass member 11 is formed so as to have three or more carcass cords 11a, the carcass cord 11a included in one carcass member 11 is too small, and the carcass cord 11a is disturbed during molding. There is an advantage that productivity is not reduced. In this case, the number of carcass cords 11a may be three or more, but five or more are preferable.

  In the above embodiment, the two carcass layers 4 are formed by overlapping the respective carcass members 11 by a width W2 that is ½ of the width W1 in the tire circumferential direction. As shown in FIG. 6, the three carcass layers 4 may be formed by overlapping each carcass member 11 with a width W2 of 1/3 of the width W1 in the tire circumferential direction. It is also possible to form the carcass layer 4 in four or more layers. That is, when N = W1 / W2, if the dimensions of W1 and W2 are set so that N is an integer, the width W2 of the overlapping portion can be made uniform over the tire circumferential direction.

  FIGS. 7 to 12 show second to sixth embodiments of the present invention. FIGS. 7 to 11 are plan views showing a part of a carcass member in an intermediate process, and FIG. 12 shows test results. is there.

  In the second embodiment, as shown in FIG. 7, belt-like carcass members 16 having a width W1 in the tire circumferential direction are arranged without shifting their positions in the longitudinal direction, and each carcass member 16 is arranged in the tire circumferential direction. The portions overlap each other by a half of the width W1. Thereby, a two-layer carcass layer is formed. That is, according to the present embodiment, as in the first embodiment, a splice portion in which the thickness in the tire radial direction is partially thickened in the tire circumferential direction is not formed. A carcass layer can be formed without the occurrence.

  In the third embodiment, as shown in FIG. 8, a belt-shaped carcass member 17 in which the width W2 in the tire circumferential direction on both ends in the longitudinal direction is formed to be 1/2 of the width W1 in the tire circumferential direction on the central side in the longitudinal direction. A part of the tire circumferential direction excluding both ends in the longitudinal direction is overlapped by a width W2. In this case, both ends in the longitudinal direction of each carcass member 17 are formed so as to cut out one side in the tire circumferential direction. Thereby, one carcass layer is formed by the longitudinal direction both ends of each carcass member 17, and a two-layer carcass layer is formed by the portion excluding the longitudinal ends. In this case, each carcass member 17 is folded back from the turn-up position TU so that the outer side is a single carcass layer and the inner side is a two-layer carcass layer. That is, according to the present embodiment, as in the first embodiment, the stress generated at the end of the carcass layer can be dispersed, which is effective in preventing the occurrence of a separation failure.

  As shown in FIG. 9, the fourth embodiment has a belt-like first carcass member 18 having a width W1 in the tire circumferential direction, and the lengths at both ends in the longitudinal direction are shorter than the first carcass member 18. The band-like second carcass members 19 having the same width W1 as the first carcass members 18 are alternately arranged one by one in the tire circumferential direction, and each of the carcass members 18 and 19 has a width W1 partially in the tire circumferential direction. Are overlapped each other by a width W2. As a result, a single carcass layer is formed by both longitudinal ends of the first carcass member 18, and two carcass layers are formed by the portion excluding the longitudinal both ends of the first carcass member 18 and the second carcass member 19. Is formed. In this case, each of the carcass members 18 and 19 is folded back from the turn-up position TU so that the outer side is a single carcass layer and the inner side is a two-layer carcass layer. That is, according to the present embodiment, as in the first embodiment, the stress generated at the end of the carcass layer can be dispersed, which is effective in preventing the occurrence of a separation failure.

  In the fifth embodiment, as shown in FIG. 10, strip-shaped carcass members 20 having the same length and having a width W1 in the tire circumferential direction are alternately arranged with their longitudinal positions shifted one by one. Each carcass member 20 is configured such that a part in the tire circumferential direction excluding one end in the longitudinal direction overlaps each other by a width W2 that is ½ of the width W1. Thereby, one carcass layer is formed by the longitudinal direction both ends of each carcass member 20, and a two-layer carcass layer is formed by a portion excluding the longitudinal ends. In this case, each carcass member 20 is folded back from the turn-up position TU so that the outer side is a single carcass layer and the inner side is a two-layer carcass layer. That is, according to the present embodiment, as in the first embodiment, the stress generated at the end of the carcass layer can be dispersed, which is effective in preventing the occurrence of a separation failure.

  In the sixth embodiment, as shown in FIG. 11, a pair of belt-like first members are disposed at positions excluding the center in the tire width direction such that one end in the longitudinal direction is spaced from each other and have a width W1 in the tire circumferential direction. The carcass member 21 and the second carcass member in the form of a belt having a width W1 equal to that of the first carcass member 21 is shorter than the other end in the longitudinal direction of each first carcass member 21. 22 are alternately arranged in the tire circumferential direction, and the carcass members 21 and 22 are partially overlapped by a width W2 that is a half of the width W1 in the tire circumferential direction. As a result, one carcass layer is formed by the other longitudinal end side of each first carcass member 21 and the longitudinal center side of the second carcass member 22, and the longitudinal direction of each first carcass member 21 and the like. Two carcass layers are formed by the portion excluding the end side and the second carcass member 22. In this case, each carcass member 21, 22 has one carcass layer formed by the first carcass member 21 on the outer side from the turn-up position TU, and two carcass layers formed by the respective carcass members 21, 22 and the first carcass member on the inner side. 21 is folded back to be a single carcass layer. That is, according to the present embodiment, as in the first embodiment, the stress generated at the end of the carcass layer can be dispersed, which is effective in preventing the occurrence of a separation failure. In addition, since the carcass layer on the center side in the tire width direction can be made into one layer, the strength of the carcass layer in the portion corresponding to the belt can be made lower than that in other portions, improving riding comfort and reducing unpleasant noise. Reduction can be achieved.

  Here, as shown in FIG. 12, when Examples 3 to 9 of the present invention were tested for uniformity, road noise, riding comfort, and durability, the following results were obtained. In this case, as a comparative example, one sheet-like carcass member was lap spliced at one place in the circumferential direction, and two of them were stacked to form a two-layer carcass layer. Examples 3 to 5 have the same configuration as that of the second embodiment, Example 3 is a carcass layer formed of three carcass members, and Example 4 is a carcass layer of 24 carcass members. In Example 5, a carcass layer was formed by 92 carcass members (20 carcass cords per carcass member). Further, Example 6 has the same configuration as that of Embodiment 3, Example 7 has the same configuration as that of Embodiment 4, and Example 8 has the same configuration as that of Embodiment 5. In Example 9, the one having the same configuration as that of the sixth embodiment was used. In this test, tires having a tire size of 205 / 55R16 were used.

  The uniformity and durability tests were performed by the same method as in the above embodiment. Further, in the road noise and ride comfort test, the test was performed based on the sensory evaluation of the passenger, and it was determined that the greater the index, the more superior. As a result of the test, each of Examples 3 to 9 was superior to the comparative example.

Partial front sectional view of the pneumatic tire showing the first embodiment of the present invention Partial side sectional view of carcass member in intermediate process Partial plan view of carcass member in intermediate process Partial plan view of carcass member in intermediate process Diagram showing test results The partial side sectional view of the carcass member in the intermediate process which shows the modification of a 1st embodiment The partial top view of the carcass member in the intermediate process which shows the 2nd Embodiment of this invention The partial top view of the carcass member in the intermediate process which shows the 3rd Embodiment of this invention The partial top view of the carcass member in the intermediate process which shows the 4th Embodiment of this invention The partial top view of the carcass member in the intermediate process which shows the 5th Embodiment of this invention The partial top view of the carcass member in the intermediate process which shows the 6th Embodiment of this invention Diagram showing test results

Explanation of symbols

  4 ... carcass layer, 11, 16, 17, 18, 19, 20, 21, 22 ... carcass members.

Claims (11)

In a pneumatic tire formed by forming a carcass layer by arranging a plurality of strip-like carcass members long in the tire width direction in the tire circumferential direction,
The carcass layer is overlapped with a part of another carcass member in which one part in the tire circumferential direction of each carcass member is located on one side in the tire circumferential direction, and the other in the tire circumferential direction on the other part in the tire circumferential direction of each carcass member A pneumatic tire characterized by being formed so that a part of another carcass member located in the upper part overlaps. The carcass layer is formed such that the positions of the end portions in the longitudinal direction of some carcass members are shifted in the longitudinal direction of the carcass members with respect to the positions of the end portions in the longitudinal direction of other carcass members. The pneumatic tire according to 1. The carcass layer is formed so that longitudinal end portions of some carcass members are displaced from the longitudinal end portions of other carcass members by 10 mm or more in the longitudinal direction of the carcass members. Pneumatic tires. The pneumatic tire according to claim 1, 2, or 3, wherein each carcass member is formed so that a width in a tire circumferential direction is 30 mm or less. The pneumatic tire according to claim 1, 2, 3, or 4, wherein each of the carcass members is formed to have three or more carcass cords. The air according to claim 1, 2, 3, 4 or 5, wherein the carcass layer at the center in the tire width direction is formed so that there are fewer overlapping portions of the carcass members than the carcass layers on both sides in the width direction. Enter tire. In the method for manufacturing a pneumatic tire for forming a carcass layer by arranging a plurality of strip-like carcass members long in the tire width direction side by side in the tire circumferential direction,
A part of each carcass member in the tire circumferential direction is overlapped with a part of another carcass member located on one side in the tire circumferential direction, and the other part in the tire circumferential direction of each carcass member is located on the other side in the tire circumferential direction. A method of manufacturing a pneumatic tire, comprising forming a carcass layer by overlapping a part of another carcass member. The carcass members are formed such that carcass members having equal lengths are alternately shifted in the longitudinal direction, and part of the tire circumferential direction excluding one end in the longitudinal direction is overlapped. The manufacturing method of the pneumatic tire of description. A carcass layer in which the width in the tire circumferential direction at both ends in the longitudinal direction is smaller than the width in the tire circumferential direction at the center in the longitudinal direction so that a part in the tire circumferential direction excluding both ends in the longitudinal direction overlaps The method for manufacturing a pneumatic tire according to claim 7, wherein: The first and second carcass members having different lengths are alternately arranged one by one in the tire circumferential direction, and a part of the tire circumferential direction excluding one end in the longitudinal direction of one of the first and second carcass members is The method of manufacturing a pneumatic tire according to claim 7, wherein the carcass layer is formed so as to overlap. A pair of first carcass members arranged such that one end side in the longitudinal direction is spaced apart from each other at a position other than the center side in the tire width direction, and at both ends in the longitudinal direction than the other end side in the longitudinal direction of each first carcass member The second carcass members having a short length are alternately arranged one by one in the tire circumferential direction, and a part in the tire circumferential direction excluding the other longitudinal end of each first carcass member is the second carcass member. The method of manufacturing a pneumatic tire according to claim 7, wherein the carcass layer is formed so as to overlap.

Images