Belt reinforcement layer, tire, and manufacturing method of belt reinforcement layer

Abstract

To provide a belt reinforcement layer, a tire, and a manufacturing method of the belt reinforcement layer capable of suppressing degradation of uniformity by reducing a three-layer part.SOLUTION: A belt reinforcement layer is stacked on an outer peripheral side of a belt layer embedded in a tread part of a tire, and includes: a body part 61; and a folding part 62 obtained by folding a side edge of the body part 61 to an inner peripheral side or an outer peripheral side. The body part 61 and the folding part 62 are formed by an arrangement body of a plurality of reinforcement cords extending continuously in a spiral shape. An angle range of the arrangement body extending substantially parallel to a peripheral direction CD in the side edge is greater than 0 degrees and less than 360 degrees.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a belt reinforcing layer that is a tire constituent member, a tire using the same, and a method for manufacturing the belt reinforcing layer. [Background technology]

[0002] Tires are known in which a belt reinforcing layer is laminated on the outer peripheral side of a belt layer embedded in the tread portion for the purpose of improving durability during high-speed driving. Patent Document 1 describes a pneumatic tire equipped with a belt reinforcing layer having a main portion and a folded portion formed by folding back the side edge of the main portion toward the inner or outer peripheral side. The belt reinforcing layer is formed by continuously spirally winding a tape (ribbon-shaped narrow cord rubberized sheet) including an arrangement of multiple reinforcing cords. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-105152 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method described in Patent Document 1, when the side edge of the main body portion is folded back, the tape is wound around the side edge of the main body portion (the side edge of the belt reinforcing layer) once. However, the belt reinforcing layer manufactured in this manner contains at least a number of three-layer portions in which three layers of tape (arrangements of multiple reinforcing cords contained in the tape) are overlapped (see Figure 6 described later). Such three-layer portions are relatively heavy and are formed locally, which may deteriorate the uniformity of the belt reinforcing layer and, ultimately, the uniformity of the tire.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a belt reinforcing layer, a tire, and a method for manufacturing a belt reinforcing layer that can suppress deterioration of uniformity by reducing the three-layer portion. [Means for solving the problem]

[0006] The belt reinforcing layer of the present disclosure is a belt reinforcing layer laminated on the outer peripheral side of a belt layer embedded in the tread portion of a tire, and has a main body portion and a folded portion formed by folding back a side edge of the main body portion toward the inner peripheral side or the outer peripheral side, the main body portion and the folded portion are formed by an array of multiple reinforcing cords extending continuously in a spiral shape, and the angle range over which the array extends substantially parallel to the circumferential direction at the side edge is greater than 0 degrees and less than 360 degrees.

[0007] The tire of the present disclosure includes a belt layer embedded in a tread portion, and the belt reinforcing layer laminated on the outer peripheral side of the belt layer.

[0008] The manufacturing method of the belt reinforcing layer of the present disclosure is a manufacturing method of a belt reinforcing layer laminated on the outer peripheral side of a belt layer embedded in the tread portion of a tire, and includes a step of continuously winding an array of multiple reinforcing cords in a spiral shape to form a main body portion and a folded portion formed by folding back the side edge of the main body portion toward the inner or outer peripheral side, and the angle range over which the array extends substantially parallel to the circumferential direction at the side edge is greater than 0 degrees and less than 360 degrees. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a tire meridian cross-sectional view schematically showing an example of a tire according to an embodiment of the present invention; [Figure 2] FIG. 1 is a diagram showing a schematic cross-sectional structure of a belt reinforcing layer. [Figure 3] Developed plan view of the belt reinforcement layer [Figure 4] FIG. 1 is a developed plan view showing the winding of the tape in the method of the present embodiment. [Figure 5] FIG. 1 is a developed plan view showing the winding of the tape in the method of the present embodiment. [Figure 6] FIG. 10 is a developed plan view showing the winding of the tape in the comparative example method. [Figure 7] FIG. 1 is a developed plan view showing the winding of the tape in the method of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments of the present disclosure will be described with reference to the drawings.

[0011] 1 is a tire meridian cross-section diagram schematically illustrating an example of a tire according to this embodiment. The tire T is a pneumatic tire including a pair of bead portions 1, a pair of sidewall portions 2 extending radially outward from each of the bead portions 1, and a tread portion 3 continuing to the radially outer ends of each of the sidewall portions 2. A tread surface 30 formed on the outer peripheral surface of the tread portion 3 is provided with circumferential grooves 31 extending along the tire circumferential direction and lateral grooves 32 extending in a direction intersecting with the circumferential grooves 31, thereby forming a tread pattern according to the required tire performance and usage conditions.

[0012] Here, the tire circumferential direction is the direction around the central axis (tire rotation axis) of the tire T. The tire radial direction is the direction along the diameter of the tire T. The side closer to the central axis of the tire T is the inner side in the tire radial direction, and the side away from the central axis of the tire T is the outer side in the tire radial direction. The tire width direction is the direction parallel to the central axis of the tire T. The side away from the center of the tire width direction of the tire T is the outer side in the tire width direction, and the side closer to the center of the tire width direction of the tire T is the inner side in the tire width direction.

[0013] An annular bead core 1a and a bead filler 1b are embedded in the bead portion 1. The bead core 1a is formed of a bundle of rubber-coated steel wires or the like. The bead filler 1b is formed of rubber with a roughly triangular cross section and is positioned radially outward of the bead core 1a.

[0014] The carcass layer 4 is provided in a toroidal shape between the pair of bead portions 1. The ends of the carcass layer 4 are wound up so as to sandwich the bead cores 1a and the bead fillers 1b. The carcass layer 4 is composed of carcass plies formed by rubber-coating carcass cords that extend approximately perpendicular to the tire circumferential direction. Organic fiber cords such as polyester, rayon, nylon, and aramid are preferably used as the carcass cords. A belt layer 5 is laminated on the outer peripheral side of the carcass layer 4 in the tread portion 3.

[0015] The tire T includes a belt layer 5 embedded in a tread portion 3 and a belt reinforcing layer 6 laminated on the outer peripheral side (outside in the tire radial direction) of the belt layer 5. The belt layer 5 reinforces the carcass layer 4 by a hoop effect. The belt layer 5 is composed of a plurality of belt plies (two in this embodiment). Each belt ply is formed by rubber-coating belt cords that extend obliquely with respect to the tire circumferential direction, and the belt cords are laminated so as to cross each other in opposite directions between the plies. Steel cords are preferably used for the belt cords.

[0016] The belt reinforcing layer 6 is provided so as to cover the belt layer 5. The belt reinforcing layer 6 is composed of a reinforcing ply formed by rubber-coating reinforcing cords 6c (see Figs. 2 and 3) extending along the tire circumferential direction. As the reinforcing cords 6c, organic fiber cords such as polyester, rayon, nylon, and aramid are preferably used. In this embodiment, an example is shown in which the belt reinforcing layer 6 is composed of a single reinforcing ply. Fig. 2 shows a schematic cross-sectional structure of the belt reinforcing layer 6.

[0017] The belt reinforcing layer 6 has a main body portion 61 and folded-up portions 62 formed by folding back the side edges of the main body portion 61 to the inner circumferential side (inner side in the tire radial direction) or outer circumferential side (outer side in the tire radial direction). The main body portion 61 covers the entire belt layer 5, and the folded-up portions 62 cover the ends of the belt layer 5. The belt reinforcing layer 6 having such folded-up portions 62 more firmly reinforces the ends of the belt layer 5, which are prone to distortion during high-speed running. In this embodiment, folded-up portions 62 are provided on both side edges of the main body portion 61, one of which is a folded-up portion 62a folded back to the inner circumferential side, and the other is a folded-up portion 62b folded back to the outer circumferential side.

[0018] FIG. 3 is a developed plan view showing the belt reinforcing layer 6. The length L6 corresponds to one revolution in the circumferential direction CD of the belt reinforcing layer 6 (one revolution around the drum 9, which will be described later), and the angular range extending in the circumferential direction CD around the central axis is 360 degrees. As shown in FIG. 3, the main body portion 61 and the folded-back portion 62 are formed by an array of multiple reinforcing cords 6c extending continuously in a spiral shape. The belt reinforcing layer 6 is formed by winding a tape T6, which is obtained by rubber-coating the array, continuously in a spiral shape around a rotating support. Note that even in the tire T after vulcanization, the boundaries of the tape T6 may be distinguishable by observing the cut surface, and even if this is not the case, at least the array of the reinforcing cords 6c can be distinguished.

[0019] 4 and 5 show how the belt reinforcement layer 6 is manufactured by winding a tape T6 around a drum 9 serving as a rotary support. The circumferential direction CD, the widthwise outer side WD1, and the widthwise inner side WD2 correspond to the tire circumferential direction, the tire widthwise outer side, and the tire widthwise inner side, respectively. The number of cords in the array included in one tape T6 is not particularly limited, but is, for example, 3 to 10. As shown in FIGS. 4 and 5, the manufacturing method of the belt reinforcement layer 6 of this embodiment includes a step of continuously winding an array of a plurality of reinforcing cords 6c in a spiral shape to form a main body portion 61 and a folded-back portion 62 formed by folding back a side edge of the main body portion 61. The process will be explained in order below.

[0020] First, as shown in FIG. 4A, the tape T6 is continuously wound spirally from the starting point S6 where winding begins toward the outer side WD1 in the width direction to form the turned-up portion 62 (turn-up portion 62a). The tape T6 makes two revolutions around the drum 9 from the starting point S6 until it reaches position E6, which becomes the side edge of the main body portion 61 (the side edge of the belt reinforcing layer 6). Specifically, the tape T6 makes 0.5 revolutions from position a to position b, then makes one revolution from position b to position c, and then makes 0.5 revolutions from position c to position d. The number of revolutions of the tape T6 to form the turned-up portion 62 is, for example, 2 to 4 revolutions, but is not particularly limited.

[0021] While the tape T6 is being spirally wound (from position a to position d in the range shown in FIG. 4(A)), the tape T6 is positioned so as to extend at a predetermined inclination angle θ6 with respect to the circumferential direction CD. The inclination angle θ6 is not particularly limited, but is set to be greater than 0.0 degrees, preferably 0.3 degrees or greater. The inclination angle θ6 is set to, for example, 1.0 degrees or less, preferably 0.6 degrees or less. Although not shown, a belt layer 5 is arranged on the outer peripheral surface of the drum 9, and the tape T6 is wound so as to cover the belt layer 5.

[0022] In this embodiment, a gap Gt smaller than the tape width Wt is provided between adjacent tapes T6 in the width direction. That is, the tape T6 is wound at a pitch Pt equal to the tape width Wt plus a predetermined gap Gt. However, this is not limited to this, and the gap Gt may be set to zero, and adjacent tapes T6 may be wound while their side edges are butted against each other. Furthermore, as long as the reinforcing cords 6c do not overlap each other, the rubber portions forming the side edges of adjacent tapes T6 may be overlapped when wound.

[0023] Next, as shown in FIG. 4B, the tape T6 that has reached side edge position E6 is wound substantially parallel to the circumferential direction CD for less than one revolution. In other words, the angle range over which the array (including the tape T6) at the side edge substantially extends in the circumferential direction CD is greater than 0 degrees and less than 360 degrees. In this embodiment, the tape T6 makes 0.5 revolutions around the drum 9 between positions d and e, and the angle range over which the array extends substantially parallel to the circumferential direction CD at the side edge is 180 degrees. Between positions d and e, the inclination angle of the tape T6 with respect to the circumferential direction CD is smaller than the inclination angle θ6 (see FIG. 4A) when wound spirally, and is substantially zero degrees.

[0024] 4(C), the tape T6 is continuously wound spirally from position e toward the widthwise inner side WD2 to form the main body portion 61. In this way, the main body portion 61 and the folded portion 62 (folded portion 62a) formed by folding back the side edge of the main body portion 61 are formed. Because the angle range at the side edge is less than 360 degrees, a triangular notch 63 is formed at the side edge of the main body portion 61 in which the array of reinforcing cords 6c (including the tape T6) is not placed.

[0025] Thereafter, when the tape T6 reaches the opposite side edge position E6 as shown in FIG. 5(A), the tape T6 is wound substantially parallel to the circumferential direction CD and for less than one turn as shown in FIG. 5(B). In other words, the angle range in which the array (including the tape T6) at the side edge substantially extends in the circumferential direction CD is set to be greater than 0 degrees and less than 360 degrees. In this example, as in the example of FIG. 4, the angle range is set to 180 degrees. Then, as shown in FIG. 5(C), the tape T6 is continuously wound spirally toward the widthwise inner side WD2, forming a turn-back portion 62 (turn-back portion 62b) and ending the winding at the end G6.

[0026] The comparative example shown in FIG. 6 is the same as FIG. 4 , except that the angular range over which the tape T6 extends substantially parallel to the circumferential direction CD at the side edge is 360 degrees. The same reference numerals are used for components already described, and redundant explanations will be omitted. In this comparative example, the tape T6 reaches the side edge position E6 and makes one revolution around the drum 9 from position d to position d, during which the inclination angle of the tape T6 with respect to the circumferential direction CD is substantially zero. From that point on, the tape T6 is continuously wound spirally toward the inner width direction WD2, as in FIG. 4(C). For ease of distinction in the drawings, in FIGS. 4 to 7, the "two-layer portion" where two layers of tape T6 overlap is colored gray, and the "three-layer portion" where three layers of tape T6 overlap is colored black.

[0027] 4 and 5, the angle range in which the array (including the tape T6) extends substantially parallel to the circumferential direction CD at the side edge is set to be greater than 0 degree and less than 360 degrees, thereby reducing the three-layer portion compared to the case where the angle range is set to 360 degrees (see FIG. 6). Such a three-layer portion is a portion with a relatively large weight and is formed locally as shown in FIG. 6. Therefore, by reducing this, it is possible to suppress deterioration of the uniformity of the belt reinforcing layer 6, and ultimately the uniformity of the tire T.

[0028] The smaller the angle range in which the array extends substantially parallel to the circumferential direction CD at the side edge, the more effectively the triple-layer portion tends to be reduced. From this perspective, the angle range is preferably 300 degrees or less, more preferably 270 degrees or less, and even more preferably 210 degrees or less.

[0029] The embodiment shown in Figure 7 is the same as Figure 4, except that the angle range is 270 degrees. In this example, tape T6 that has reached side edge position E6 makes 0.75 revolutions around drum 9 between positions d and e, and thereafter, tape T6 continues to be spirally wound toward the inside width direction WD2, as in Figure 4(C). In this case, too, the three-layer portion is reduced compared to the comparative example in Figure 6.

[0030] The larger the angular range in which the array elements extend substantially parallel to the circumferential direction CD at the side edges, the more likely it is that the stability of the side edges of the belt reinforcing layer 6 is maintained or the ease of measuring the width dimension of the belt reinforcing layer 6 is ensured. From this perspective, the angular range is preferably 60 degrees or more, more preferably 90 degrees or more, and even more preferably 150 degrees or more. Therefore, the angular range is preferably 150 degrees or more and 210 degrees or less (i.e., 180±30 degrees).

[0031] It is preferable that the belt reinforcing layer 6 does not include a portion where the array is overlapped by three layers in the thickness direction (tire radial direction) (i.e., a three-layer portion). When the belt reinforcing layer 6 includes a three-layer portion, it is necessary to set the rubber gauge from the groove bottom of the lateral groove 32 to the belt reinforcing layer 6 relatively large in consideration of this. On the other hand, when the belt reinforcing layer 6 does not include a three-layer portion, it is possible to set the rubber gauge relatively small, thereby reducing the weight of the tire T and thereby improving fuel efficiency. However, as long as the angle range in which the array extends substantially parallel to the circumferential direction CD at the side edge is greater than 0 degree and less than 360 degrees, the three-layer portion may be included as shown in Fig. 7, and even with such a structure, an improvement effect can be obtained by reducing the three-layer portion compared to when the angle range is 360 degrees.

[0032] In this embodiment, one of the side edges of the main body 61 is provided with a folded portion 62a folded back toward the inner periphery, and the other is provided with a folded portion 62b folded back toward the outer periphery, and the above angle range is satisfied on each of the side edges of the main body 61. Therefore, the belt reinforcing layer 6 can be formed by continuously winding the tape T6 from the starting point S6 to the terminal point G6 so as to form an S-shape in cross section (see FIG. 2), and moreover the three-layer portion is reduced on each of the side edges of the main body 61.

[0033] The angle range at the side edge where the folded portion 62a is provided and the angle range at the side edge where the folded portion 62b is provided may be different from each other, but it is preferable that they are the same as in this embodiment in order to improve uniformity. In the example shown in Figures 4 and 5, the angle range at the side edge is set to 180 degrees on both the left and right sides, and the phases of these are shifted by 180 degrees in the circumferential direction CD. This configuration improves weight balance, which is advantageous in suppressing deterioration of uniformity.

[0034] As described above, in this embodiment, the three-layer portion is reduced by extending the array body as described above at the side edge of the main body portion 61. Therefore, there is no particular problem even if the array body includes a portion extending parallel to the circumferential direction CD in other locations. For example, the portion extending one turn or less from the starting end S6 and / or the portion extending one turn or less to the terminal end G6 may extend parallel to the circumferential direction CD. In addition, although the example shown in Figures 4 and 5 shows an example in which the starting end S6 and the terminal end G6 are aligned in the circumferential direction CD, this is not limiting.

[0035] In the present embodiment, an example has been shown in which one of the folded portions 62 provided on both side edges of the main body portion 61 is folded back to the inner circumferential side as the folded portion 62a and the other is folded back to the outer circumferential side, but this is not limited thereto, and for example, both may be folded back to the inner circumferential side, or both may be folded back to the outer circumferential side. Of course, the belt reinforcing layer 6 may be any one that has the main body portion 61 and the folded portion 62 formed by folding back at least one of both side edges of the main body portion 61 to the inner circumferential side or the outer circumferential side.

[0036] In the tire T of this embodiment, the angular range over which the array bodies extend substantially parallel to the circumferential direction CD at the side edges of the main body portion 61 is greater than 0 degree and less than 360 degrees, thereby suppressing deterioration of uniformity caused by the three-layer portion of the belt reinforcing layer 6. Therefore, the tire T is useful as a large-inch tire with particularly strict requirements for uniformity, for example, a tire with a rim diameter of 19 inches or more, 20 inches or more, or 21 inches or more.

[0037] The tire T can be constructed in the same manner as a normal pneumatic tire, except that it has the belt reinforcing layer 6 as described above, and any of the conventionally known materials, shapes, structures, etc. can be employed.

[0038] It will be understood by those skilled in the art that the above-described embodiments are examples of the following aspects.

[0039] [1] The belt reinforcing layer of the present disclosure is a belt reinforcing layer laminated on the outer peripheral side of a belt layer embedded in a tread portion of a tire, and has a main body portion and a folded-back portion formed by folding back a side edge of the main body portion toward the inner peripheral side or the outer peripheral side, the main body portion and the folded-back portion being formed by an array of a plurality of reinforcing cords extending continuously in a spiral shape, and the angle range in which the array extends substantially parallel to the circumferential direction at the side edge is more than 0 degree and less than 360 degrees. With this configuration, the number of three-layer portions is reduced compared to when the angle range is 360 degrees, and therefore deterioration of uniformity can be suppressed.

[0040] [2] In the belt reinforcing layer of the above [1], the angle range is preferably 150 degrees or more and 210 degrees or less.

[0041] [3] In the belt reinforcing layer of [1] or [2] above, one of the two side edges of the main body portion may have a folded portion folded back toward the inner periphery, and the other may have a folded portion folded back toward the outer periphery, and each of the two side edges of the main body portion may satisfy the angle range.

[0042] [4] The tire of the present disclosure includes a belt layer embedded in the tread portion and one of the belt reinforcing layers [1] to [3] laminated on the outer peripheral side of the belt layer. With this configuration, the number of three-layer portions is reduced compared to when the angle range is 360 degrees, and therefore deterioration of uniformity can be suppressed.

[0043] [5] The tire of the above item [4] may have a rim diameter of 19 inches or more.

[0044] [6] The manufacturing method of the belt reinforcing layer of the present disclosure is a manufacturing method of a belt reinforcing layer laminated on the outer peripheral side of a belt layer embedded in a tire tread portion, and includes a step of forming a main body portion and a folded portion formed by folding back a side edge of the main body portion toward the inner peripheral side or the outer peripheral side by continuously winding an array of a plurality of reinforcing cords in a spiral shape, and the angle range in which the array extends substantially parallel to the circumferential direction at the side edge is greater than 0 degree and less than 360 degrees. According to this method, the number of three-layer portions is reduced compared to when the angle range is 360 degrees, and therefore deterioration of uniformity can be suppressed.

[0045] [7] In the method for manufacturing a belt reinforcing layer of the above [6], it is preferable that the angle range is 150 degrees or more and 210 degrees or less.

[0046] Although the embodiments of the present disclosure have been described, the specific configurations are not limited to these embodiments. The present disclosure is not limited to the above-described embodiments, and various improvements and modifications are possible within the scope of the present disclosure. Furthermore, the configurations employed in the above-described embodiments can be combined in any desired manner. [Explanation of symbols]

[0047] 1 bead portion, 2 sidewall portion, 3 tread portion, 6 belt reinforcing layer, 6c reinforcing cord, 9 drum (an example of a rotating support), 61 main body portion, 62 turned-up portion, 62a turned-up portion, 62b turned-up portion, E6 side edge position, G6 end, S6 start, T tire, T6 tape

Claims

1. A belt reinforcing layer laminated on the outer peripheral side of a belt layer embedded in a tread portion of a tire, a main body portion and a folded portion formed by folding a side edge of the main body portion toward an inner circumferential side or an outer circumferential side, the main body portion and the folded-back portion are formed by an array of a plurality of reinforcing cords that extend continuously in a spiral shape, A belt reinforcing layer, characterized in that the angular range over which the array members extend substantially parallel to the circumferential direction at the side edges is greater than 0 degrees and less than 360 degrees.

2. 2. The belt reinforcing layer according to claim 1, wherein the angle range is 150 degrees or more and 210 degrees or less.

3. 2. The belt reinforcing layer according to claim 1, wherein one of the two side edges of the main body portion has a folded portion folded inward, and the other has a folded portion folded outward, and each of the two side edges of the main body portion satisfies the angle range.

4. A tire comprising: a belt layer embedded in a tread portion; and the belt reinforcing layer according to any one of claims 1 to 3 laminated on the outer peripheral side of the belt layer.

5. 5. The tire according to claim 4, wherein the rim diameter is 19 inches or more.

6. A method for manufacturing a belt reinforcing layer laminated on an outer peripheral side of a belt layer embedded in a tread portion of a tire, comprising: a step of continuously winding an array of a plurality of reinforcing cords in a spiral shape to form a main body portion and a folded-back portion formed by folding back a side edge of the main body portion toward the inner circumferential side or the outer circumferential side, A method for manufacturing a belt reinforcing layer, characterized in that the angular range over which the array members extend substantially parallel to the circumferential direction at the side edges is greater than 0 degrees and less than 360 degrees.

7. The method for manufacturing a belt reinforcing layer according to claim 6, wherein the angle ranges from 150 degrees to 210 degrees.

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