Tread element with color line and method of manufacturing the tread element

Abstract

To provide a tread member provided with a color line, capable of stably applying colored rubber to the tread member using a nozzle.SOLUTION: A tread member 1 with a side color line 31 is a rubber extruded shaped member having a predetermined cross-sectional shape and extending in an extrusion direction E, and comprises: the tread member 1 which has a first main surface 2 that constitutes an outer peripheral surface 50a of a green tire 50 in a tire radial direction when the tread member is wound in a cylindrical shape, and a pair of opposing wall surfaces 6a that extend in the extrusion direction E on the first main surface 2 and face each other in a left-right direction orthogonal to the extrusion direction E; and a color rubber 30 extending in the extrusion direction E between the pair of opposing wall surfaces 6a on the first main surface 2.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a tread element having a color line and a method for manufacturing the tread element. [Background technology]

[0002] Tread components are known that have colored lines on their outer surface for identification and / or as reference lines for assembly positions. Patent Document 1 discloses a method for manufacturing a tread component with a colored line, in which a rubber material is extruded from a die into a predetermined cross-sectional shape to form a tread component with ridges extending along the extrusion direction on its outer surface, and a colored rubber cement is transferred and applied to the tops of the ridges using a wide transfer roller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-61999 Summary of the Invention [Problem to be solved by the invention]

[0004] The method of Patent Document 1 aims to apply the colored lines with a transfer roller, so that even if the extruded rubber meanders, the colored lines can be stably applied to the protrusions of the tread member with a wide transfer roller. However, the method of Patent Document 1 applies the colored rubber with a transfer roller, and is not applicable to cases where the colored rubber is applied using a nozzle.

[0005] An object of the present invention is to provide a tread element having a color line, which allows colored rubber to be stably applied to the tread element using a nozzle, and a method for manufacturing the tread element. [Means for solving the problem]

[0006] One aspect of the present invention is a tread member that is a rubber extrusion profile that has a predetermined cross-sectional shape and extends in a first direction, and that has a first main surface that forms an outer peripheral surface in the tire radial direction of the green tire when wound cylindrically, and a pair of opposing wall surfaces that extend in the first direction on the first main surface and oppose each other in a second direction perpendicular to the first direction; a colored rubber extending in the first direction between the pair of opposing wall surfaces on the first main surface; With And, The tread element is a pair of protrusions protruding from the first main surface and extending in the first direction; a groove recessed with respect to the first main surface between the pair of protrusions and extending in the first direction; It has The pair of opposing wall surfaces are a pair of side surfaces of the pair of protrusions that face each other in the second direction; Both side surfaces that form the groove and face each other in the second direction; It is made up of The object of the present invention is to provide a tread element having a color line.

[0007] According to the present invention, when applying colored rubber using a nozzle to a tread member that is extruded and extending in a first direction, by positioning the nozzle between a pair of opposing wall surfaces, even if the tread member meanders in the width direction, the pair of opposing wall surfaces make it easy to hold the tip of the nozzle between the pair of opposing wall surfaces, and the colored rubber can be easily applied between the pair of opposing wall surfaces. In other words, since the colored rubber can be applied to the tread member while suppressing meandering, meandering of the colored line made of the colored rubber is suppressed in a pneumatic tire vulcanized and molded using the tread member. Therefore, the colored rubber can be stably applied to the tread member using the nozzle. Furthermore, a pair of opposing wall surfaces can be easily formed using a pair of ridges and grooves. In particular, it is easy to set the height of the ridges low and the depth of the grooves shallow, which makes it easy to secure the required amount of rubber while preventing an increase in the amount of rubber.

[0008] The colored rubber width dimension, which is the length of the colored rubber in the second direction, may be 67% or more and 133% or less of the wall surface spacing, which is the length in the second direction on the first main surface between the pair of opposing wall surfaces.

[0009] According to this configuration, it is easy to arrange the nozzle for applying the colored rubber between the pair of opposing wall surfaces. If the colored rubber width exceeds 133% of the wall surface spacing, it is difficult to arrange the nozzle between the pair of opposing wall surfaces. If the colored rubber width is less than 67% of the wall surface spacing, the nozzle can move in the width direction of the tread member between the pair of opposing wall surfaces, which makes it easy for the colored rubber applied between the pair of opposing wall surfaces to meander more.

[0010] The pair of opposing wall surfaces may have a height of 3 mm or more and 4.5 mm or less in a direction perpendicular to the first main surface.

[0011] According to this configuration, the nozzle for applying the colored rubber can be easily held between the pair of opposing wall surfaces. If the height of the pair of opposing wall surfaces is less than 3 mm, the nozzle cannot be held by the pair of opposing wall surfaces as easily. If the height of the pair of opposing wall surfaces exceeds 4.5 mm, the portions constituting the pair of opposing wall surfaces tend to flow to cover the colored rubber during vulcanization molding, thereby making it difficult to distinguish the colored rubber.

[0012] the tread element has a pair of protrusions protruding from the first main surface and extending in the first direction, The pair of opposing wall surfaces are the side surfaces of the pair of protrusions. of The second side surface may be formed by a pair of side surfaces facing each other in the second direction.

[0013] This configuration allows the pair of opposing wall surfaces to be easily formed using a pair of ridges. Compared to forming the pair of opposing wall surfaces using grooves, it is easier to ensure the amount of rubber and to prevent chipping of the rubber due to an insufficient amount of rubber during vulcanization molding.

[0014] the tread element has a groove recessed with respect to the first main surface and extending in the first direction, The pair of opposing wall surfaces may be formed by both side surfaces that form the groove and face each other in the second direction.

[0015] According to this configuration, the pair of opposing wall surfaces can be easily formed by grooves. Furthermore, compared to when the pair of opposing wall surfaces are formed by a pair of ridges, an increase in the amount of rubber can be suppressed.

[0018] The wall-to-wall distance may be 1.5 mm or more and 6.0 mm or less.

[0019] According to this configuration, since the wall spacing is 1.5 mm to 6.0 mm, it is easy to arrange a nozzle for applying colored rubber between the pair of opposing wall surfaces with a colored rubber width dimension of, for example, 2.0 mm to 4.0 mm. As a result, a colored line for identifying components can be formed by the colored rubber applied between the pair of opposing wall surfaces.

[0020] The wall-to-wall spacing may be 0.20 mm or more and 1.50 mm or less.

[0021] With this configuration, the wall spacing is 0.20 mm to 1.50 mm, making it easy to position a nozzle for applying colored rubber between the pair of opposing wall surfaces with a colored rubber width dimension of, for example, 0.25 mm to 1.00 mm. As a result, the colored rubber applied between the pair of opposing wall surfaces can form a reference line that serves as a reference for the assembly position when assembling a green tire.

[0022] In the cross-sectional shape, the pair of opposing wall surfaces may be perpendicular to the first main surface or may be inclined in directions away from each other at an angle of 60° to 90° with respect to the first main surface.

[0023] According to this configuration, the area defined between the pair of opposing wall surfaces to which the colored rubber is applied is set to an appropriate size, so that the amount of colored rubber used is optimized.

[0024] Another aspect of the present invention is a tread member is formed by extruding rubber from a mouthpiece in a first direction into a predetermined cross-sectional shape and having a first main surface that constitutes an outer peripheral surface in the tire radial direction of the green tire when wound into a cylindrical shape, and a pair of opposing wall surfaces that extend in the first direction on the first main surface and oppose each other in a second direction perpendicular to the first direction; Here, the tread element is a pair of protrusions protruding from the first main surface and extending in the first direction; a groove recessed with respect to the first main surface between the pair of protrusions and extending in the first direction; It has The pair of opposing wall surfaces are a pair of side surfaces of the pair of protrusions that face each other in the second direction; Both side surfaces that form the groove and face each other in the second direction; It is composed of A method for manufacturing a tread member having a color line is provided, in which colored rubber is applied to the first main surface of the tread member transported in the first direction by a nozzle positioned between the pair of opposing wall surfaces. [Effects of the Invention]

[0025] According to the present invention, when a tread member having a color line is manufactured, the color rubber can be stably applied using a nozzle while suppressing meandering of the color rubber relative to the tread member. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic view of a manufacturing apparatus for a tread member according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the base as viewed from the arrow A in FIG. [Figure 3] FIG. [Figure 4] FIG. 4 is a perspective view showing application of colored rubber to a tread member by a nozzle. [Figure 5] 5 is a cross-sectional view showing a pair of side protrusions taken along line VV in FIG. 4 together with a nozzle. [Figure 6] FIG. 6 is a cross-sectional view similar to FIG. 5 of a pair of center ridges. [Figure 7] FIG. 4 is a diagram schematically showing a process of winding a tread element onto a building drum. [Figure 8]FIG. 1 is a perspective view schematically illustrating a green tire. [Figure 9] Front view of a base according to a second embodiment [Figure 10] 10 is a cross-sectional view similar to FIG. 5 showing the tread element extruded by the die of FIG. 9. [Figure 11] FIG. 10 is a front view of a base according to a third embodiment. [Figure 12] 12 is a cross-sectional view similar to FIG. 5 showing the tread element extruded by the die of FIG. 11. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following description is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0028] [First embodiment] Fig. 1 schematically shows a tread production line 10 that produces a tread element 1. As shown in Fig. 1, the tread production line 10 has an extruder 11 that extrudes a rubber material R into a predetermined cross-sectional shape to form the tread element 1, and nozzles 16 and 17 that apply a colored rubber 30 (see Fig. 3) to the tread element 1.

[0029] The extruder 11 includes a hopper 12 into which the rubber material R is fed, a screw 13 that kneads and transports the rubber material R fed into the hopper 12, a drive source 14 (e.g., a motor) that drives the screw 13, and a die 20. The extruder 11 kneads and heats the rubber material R by rotating the screw 13 through the drive source 14, and extrudes the rubber material R from the die 20 in an extrusion direction E (first direction). The extruded rubber material R forms a tread member 1, which is a long, strip-shaped extruded profile having a predetermined cross-sectional shape.

[0030] The nozzles 16 and 17 are located downstream of the extruder 11 in the extrusion direction E, and apply the colored rubber 30 to the surface of the tread member 1 being conveyed.

[0031] 2 is a front view of the die 20 as seen from the arrow A in FIG. 1. As shown in FIG. 2, the die 20 has a horizontally elongated opening 21. The opening 21 has an opening top surface 22 and an opening bottom surface 23 that extend in a left-right direction (second direction) perpendicular to the extrusion direction E, and a pair of opening side surfaces 24 that extend in the up-down direction. The opening top surface 22 is shorter in the left-right direction than the opening bottom surface 23. The pair of opening side surfaces 24 connect the left and right side portions of the opening top surface 22 and the left and right side portions of the opening bottom surface 23, respectively. The opening 21 is formed in a trapezoidal shape that is symmetrical with respect to a center line CL in the left-right direction. The rubber material R is extruded through the opening 21 of the die 20 in a trapezoidal cross-sectional shape.

[0032] The opening top surface 22 is formed with a notch 25 that is recessed upward and extends in the extrusion direction E. In this embodiment, the mouthpiece 20 has, as the notches 25, a pair of left and right side notches 26 and a pair of left and right center notches 27 formed on the left side and the center in the left-right direction of the opening top surface 22. In this embodiment, the side notches 26 and the center notch 27 are formed with a triangular cross section, for example, by marking the opening top surface 22 in the extrusion direction E. Alternatively, the side notches 26 and the center notch 27 may be formed with any cross-sectional shape, such as a rectangular, trapezoidal, semicircular, or curved shape.

[0033] The pair of side notches 26 each have a recession H1 of 3 mm or more and 4.5 mm or less from the opening top surface 22, and are inclined at an angle K1 of 90° or 60° or more away from the opening top surface 22. The left-right distance D1 between the pair of side notches 26 is 1.5 mm or more and 6.0 mm or less.

[0034] Similarly, the pair of center notches 27 each have a recession amount H2 of 3 mm or more and 4.5 mm or less from the opening top surface 22, and an angle K2 relative to the opening top surface 22 is 90° or is inclined at an angle of 60° or more in directions away from each other. The left-right distance D2 between the pair of center notches 27 is 0.20 mm or more and 1.50 mm or less.

[0035] FIG. 3 is a perspective view of the tread element 1. The tread element 1 has a cross-sectional shape corresponding to the shape of the opening 21 of the mouthpiece 20, and has a first main surface 2 formed by the opening top surface 22, a second main surface 3 formed by the opening bottom surface 23, and a pair of tread side surfaces 4 formed by a pair of opening side surfaces 24. In FIG. 3, the first main surface 2 and the second main surface 3 extend in the left-right direction. The first main surface 2 is shorter in the left-right direction than the second main surface 3. The pair of tread side surfaces 4 connect both left and right side portions of the first main surface 2 and both left and right side portions of the second main surface 3 in the up-down direction. The tread element 1 is a long extruded member having a horizontally elongated cross-sectional shape extending in the extrusion direction E.

[0036] The first main surface 2 is formed with ridges 5 extending in the extrusion direction E. The ridges 5 have a pair of side ridges 6 formed by a pair of side notches 26, and a pair of center ridges 7 formed by a pair of center notches 27.

[0037] Fig. 4 is a perspective view showing the periphery of the tip 16a of the nozzle 16. As shown in Fig. 4, the tip 16a of the nozzle 16 is located between the pair of side ridges 6. The colored rubber 30 is supplied from the nozzle 16, and is applied between the pair of side ridges 6 on the first main surface 2. The colored rubber 30 is applied onto the first main surface 2 as the tread member 1 is transported in the extrusion direction E, and therefore extends downstream of the nozzle 16 in the extrusion direction E.

[0038] FIG. 5 is a cross-sectional view taken along line VV in FIG. 4 , showing the tread member 1 with the pair of side protrusions 6 and the nozzle 16 located between them, viewed from the extrusion direction Z. The pair of side protrusions 6 are formed with a triangular cross-section corresponding to the shape of the pair of side notches 26. The pair of side protrusions 6 each have a protrusion amount X1 of 3 mm to 4.5 mm, and an angle Y1 relative to the first main surface 2 of 90° or an angle of 60° or more inclined in the direction away from each other. The inner diameter W1 of the nozzle 16 is 67% to 133% of the distance Z1 (wall surface spacing) between the pair of side protrusions 6 on the first main surface 2 in the left-right direction. The inner diameter W1 of the nozzle 16 is 2.0 mm to 4.0 mm. Therefore, the distance Z1 between the pair of opposing wall surfaces 6a on the first main surface 2 is 1.5 mm to 6.0 mm.

[0039] In this embodiment, the nozzle 16 has an inner diameter W1 of 3.0 mm, and therefore the distance Z1 between the pair of side ridges 6 is 2 mm or more and 4 mm or less. In other words, the distance D1 between the pair of side notches 26 in the nozzle 20 is set so that the distance Z1 between the pair of side ridges 6 is within the above range. The pair of side ridges 6 have opposing wall surfaces 6a that face each other in the width direction (the left-right direction in FIG. 5).

[0040] The nozzle 16 has a tip 16a located above the first main surface 2 and below the apexes of the pair of side ridges 6. That is, the tip 16a of the nozzle 16 is sandwiched in the left-right direction between the pair of side ridges 6, i.e., the pair of opposing wall surfaces 6a. In this embodiment, the distance Z1 between the pair of side ridges 6 is set to 2.0 mm, and by supplying the colored rubber 30 from the nozzle 16, a side colored line 31 is formed on the first main surface 2 between the pair of side ridges 6 and extending in the extrusion direction E with a width F1 (colored rubber width dimension) corresponding to the inner diameter W1 of the nozzle 16. In this embodiment, the width F1 of the side colored line 31 is approximately equal to the inner diameter W1 of the nozzle 16 and is 2.0 mm or more and 4.0 mm or less.

[0041] Similarly, FIG. 6 is a cross-sectional view of the tread member 1, showing a pair of center ridges 7 and the nozzle 17 located between them, as viewed from the extrusion direction E. The pair of center ridges 7 are formed with a triangular cross section corresponding to the shape of the pair of center notches 27. The pair of center ridges 7 each have a protrusion amount X2 of 3 mm to 4.5 mm, and an angle Y2 relative to the first main surface 2 of 90° or an angle of 60° or more inclined in the direction away from each other. The inner diameter W2 of the nozzle 17 is 67% to 133% of the distance Z2 (wall surface spacing) between the pair of center ridges 7 on the first main surface 2 in the left-right direction. The inner diameter W2 of the nozzle 17 is 0.25 mm to 1.00 mm. Therefore, the distance Z2 between the pair of opposing wall surfaces 7a on the first main surface 2 is 0.20 mm to 1.50 mm.

[0042] In this embodiment, the nozzle 17 has an inner diameter W2 of 0.5 mm, and therefore the distance Z2 between the pair of center ridges 7 is 0.3 mm or more and 0.7 mm or less. In other words, the distance D2 between the pair of center notches 27 in the nozzle 20 is set so that the distance Z2 between the pair of center ridges 7 is within the above range. The pair of center ridges 7 have opposing wall surfaces 7a that face each other in the width direction (the left-right direction in FIG. 6).

[0043] The nozzle 17 has a tip 17a located above the first main surface 2 and below the apexes of the pair of center ridges 7. That is, the tip 17a of the nozzle 17 is sandwiched in the left-right direction between the pair of center ridges 7, i.e., the pair of opposing wall surfaces 7a. In this embodiment, the distance Z2 between the pair of center ridges 7 is set to 0.25 mm, and by supplying the colored rubber 30 from the nozzle 17, a center colored line 32 is formed between the pair of center ridges 7 on the first main surface 2, extending in the extrusion direction E with a width F2 (colored rubber width dimension) corresponding to the inner diameter W2 of the nozzle 17. In this embodiment, the width F2 of the center colored line 32 is approximately equal to the inner diameter W2 of the nozzle 17 and is 0.25 mm or more and 1.00 mm or less.

[0044] 7 schematically shows a process of forming a tread ring 51 by winding a tread element 1, which has a first main surface 2 coated with a side color line 31 and a center color line 32, into a cylindrical shape on a forming drum 40. The forming drum 40 rotates about a central axis O1 and winds the tread element 1 around its outer periphery. A belt 52 is wound around the forming drum 40 in advance. The tread element 1 is wound around the outer periphery of the belt 52.

[0045] At this time, the tread component 1 is wound with the first main surface 2 positioned on the outer periphery and the longitudinal direction aligned with the circumferential direction of the forming drum 40. As a result, the tread component 1 is wound cylindrically so that the side color line 31 and the center color line 32 extend along the outer periphery of the forming drum 40 on the outer periphery.

[0046] The forming drum 40 is provided with a laser marker 41 that irradiates a central portion in the width direction with a laser beam. The tread member 1 is wound around the forming drum 40 with the center color line 32 aligned in the width direction of the forming drum 40 with the laser beam L irradiated from the laser marker 41 toward the forming drum 40. This makes it easier to wind the tread member 1 accurately by suppressing misalignment of the tread member 1 with respect to the forming drum 40 in the width direction of the forming drum 40. In other words, the center color line 32 forms a reference line that serves as a reference for the assembly position when assembling the tread member 1 onto the forming drum 40.

[0047] 8 is a perspective view of a green tire 50 formed by expanding a separately molded carcass band 53 to the outer diameter side in a toroidal shape and attaching it to the inner peripheral surface of a tread ring 51. As shown in FIG. 8, an outer peripheral surface 50a of the green tire 50 is constituted by a first main surface 2 of a tread member 1, and a side color line 31 and a center color line 32 extend in the circumferential direction of the green tire 50.

[0048] The type of the green tire 50 can be identified by the color, width, position in the tire axial direction, etc. of the side color line 31. Therefore, the side color line 31 constitutes an identifying color line for identifying the type of the tread member 1, the green tire 50, and the pneumatic tire (not shown) obtained by vulcanizing and molding the green tire 50.

[0049] The tread member 1 and the manufacturing method for the tread member 1 according to the above embodiment have the following advantages. Note that, although the following describes the advantages of the pair of opposing wall surfaces 6a and the side color line 31, the same advantages are also achieved for the pair of opposing wall surfaces 7a and the center color line 32 unless otherwise specified, and therefore the description thereof will be omitted.

[0050] (1) The tread member 1 is a rubber extrusion profile that has a predetermined cross-sectional shape and extends in the extrusion direction E. When wound cylindrically, the tread member 1 has a first main surface 2 that forms the outer peripheral surface 50a in the tire radial direction of the green tire 50, and a pair of opposing wall surfaces 6a that extend in the extrusion direction E on the first main surface 2 and face each other in the width direction perpendicular to the extrusion direction E, and a side color line 31 that extends in the extrusion direction E between the pair of opposing wall surfaces 6a on the first main surface 2.

[0051] That is, the manufacturing method of the tread member 1 having the side color line 31 involves extruding the rubber material R from the nozzle 20 in the extrusion direction E into a predetermined cross-sectional shape to form the tread member 1 having a first main surface 2 that forms the tire radial outer surface 50a of the green tire 50 when wound into a cylindrical shape, and a pair of opposing wall surfaces 6a that extend in the extrusion direction E on the first main surface 2 and face each other in the left-right direction perpendicular to the extrusion direction E, and applying color rubber 30 to the first main surface 2 of the tread member 1 that is transported in the extrusion direction E using a nozzle 16 positioned between the pair of opposing wall surfaces 6a to form the side color line 31.

[0052] As a result, when applying the colored rubber 30 to the tread member 1 extending in the extrusion direction E using the nozzle 16, by positioning the nozzle 16 between the pair of opposing wall surfaces 6a, even if the tread member 1 meanders in the width direction, the pair of opposing wall surfaces 6a make it easy to hold the tip 16a of the nozzle 16 between the pair of side protrusions 6, and the colored rubber 30 can be easily applied between the pair of opposing wall surfaces 6a. In other words, since the colored rubber 30 can be applied to the tread member 1 while suppressing meandering, meandering of the side colored lines 31 made of the colored rubber 30 is suppressed in a pneumatic tire vulcanized and molded using the tread member 1. Therefore, the colored rubber 30 can be stably applied to the tread member 1 using the nozzle 16.

[0053] In addition, the above-mentioned effect is preferably exerted when the tread member 1 is prone to meandering in the width direction, particularly in the initial stage until the extrusion of the tread member 1 stabilizes, such as when multiple rubber materials with different properties in the width direction of the tread member 1 are used as the rubber material R.

[0054] (2) The width F1 of the side color line 31 is 67% or more and 133% or less of the distance Z1 between the pair of opposing wall surfaces 6a. As a result, it is easy to arrange the nozzle 16 between the pair of opposing wall surfaces 6a. If the width F1 of the side color line 31 exceeds 133% of the distance Z1 between the pair of opposing wall surfaces 6a, it is difficult to arrange the nozzle 16 between the pair of opposing wall surfaces 6a. If the width F1 of the side color line 31 is less than 67% of the distance Z1 between the pair of opposing wall surfaces 6a, the nozzle 16 is more likely to move in the width direction of the tread member 1 between the pair of opposing wall surfaces 6a, which increases the amount of meandering of the side color line 31 between the pair of opposing wall surfaces 6a.

[0055] (3) The height of the pair of side protrusions 6, i.e., the opposing wall surfaces 6a, in the direction perpendicular to the first main surface 2 is 3 mm or more and 4.5 mm or less. As a result, the nozzle 16 is easily held between the pair of opposing wall surfaces 6a. If the height of the pair of opposing wall surfaces 6a is less than 3 mm, the pair of opposing wall surfaces 6a will not be able to hold the nozzle 16 as well. If the height of the pair of opposing wall surfaces 6a exceeds 4.5 mm, the pair of side protrusions 6 will flow to cover the side color line 31 during vulcanization molding, making it easier for the side color line 31 to become embedded, and making it difficult to distinguish by the side color line 31.

[0056] (4) The pair of opposing wall surfaces 6a are formed by a pair of side surfaces of the pair of side ridges 6 that face each other in the width direction. As a result, the pair of opposing wall surfaces 6a can be easily formed by the pair of side ridges 6. Furthermore, compared to when the pair of opposing wall surfaces are formed by grooves, it is easier to ensure the amount of rubber, and chipping of rubber due to an insufficient amount of rubber during vulcanization molding is suppressed.

[0057] (5) With respect to the pair of side protrusions 6, the distance Z1 between the pair of opposing wall surfaces 6a is 1.5 mm or more and 6.0 mm or less. Therefore, for example, a nozzle 16 for applying colored rubber 30 with a colored rubber width dimension of 2.0 mm or more and 4.0 mm or less can be easily positioned between the pair of opposing wall surfaces 6a. This allows the side colored line 31 formed by the colored rubber 30 applied between the pair of opposing wall surfaces 6a to be used as a colored line for component identification. Note that if the width of the side colored line 31 is less than 2.0 mm, the pair of side protrusions 6 will flow over the side colored line 31 during vulcanization molding, making the side colored line 31 more likely to be buried, reducing the identification capability of the side colored line 31. If the width of the side colored line 31 exceeds 4.0 mm, there is a risk of the side colored line 31 transferring to the mold during vulcanization molding.

[0058] (6) For the pair of center ridges 7, the distance Z2 between the pair of opposing wall surfaces 7a is 0.20 mm or more and 1.50 mm or less. This makes it easy to position the nozzle 17, which applies the colored rubber 30, between the pair of opposing wall surfaces 7a with a colored rubber width dimension of, for example, 0.25 mm or more and 1.00 mm or less. This allows the center colored line 32 formed by the colored rubber 30 applied between the pair of opposing wall surfaces 7a to serve as a reference line for the assembly position when assembling a green tire. Note that if the width F2 of the center colored line 32 is less than 0.25 mm, it is difficult to stably apply the colored rubber with the nozzle 17. If the width F2 of the center colored line 32 exceeds 1.00 mm, it is too wide to be used as a reference line for the assembly position, which can easily reduce assembly accuracy.

[0059] (7) The angle Y1 of the opposing wall surfaces 6a of the pair of side protrusions 6 relative to the first main surface 2 is between 60° and 90° so that the pair of opposing wall surfaces 6a are perpendicular to the first main surface 2 or inclined in directions away from each other. As a result, the area defined between the pair of opposing wall surfaces 6a to which the color rubber 30 is applied is set to an appropriate size, thereby optimizing the amount of color rubber 30 used. Note that the larger the angle Y1, i.e., the closer it is to 90°, the smaller the area to which the color rubber 30 is applied, and therefore the amount of color rubber 30 used is reduced.

[0060] [Second embodiment] Fig. 9 is a front view of a mouthpiece 60 according to a second modified example similar to Fig. 2, and Fig. 10 is an enlarged view of a tread element 70 extruded from the mouthpiece 60 similar to Fig. 5. As shown in Fig. 9, the mouthpiece 60 differs from the mouthpiece 20 in that, instead of the notch 25, it has a protrusion 65 that protrudes downward from the open top surface 62 and extends in the extrusion direction E.

[0061] In this embodiment, the base 60 has, as protrusions 65, a side protrusion 66 and a center protrusion 67 formed on the left side and in the center in the left-right direction of the open top surface 62. The side protrusion 66 and the center protrusion 67 are formed in a trapezoidal shape whose left-right distance decreases downward. Alternatively, the side protrusion 66 and the center protrusion 67 may be formed in any cross-sectional shape, such as a rectangular, triangular, semicircular, or curved shape.

[0062] As shown in Figure 10, the tread element 70 has side grooves 76 formed by the side protrusions 66, which are recessed downward relative to the tread top surface 71. The side grooves 76 are recessed in a trapezoidal shape and have a pair of opposing wall surfaces 76a that face each other in the left-right direction. The tip 16a of the nozzle 16 is disposed between the pair of opposing wall surfaces 76a. Although not shown in the figure, the center protrusion 67 forms a center groove recessed in a trapezoidal shape downward relative to the tread top surface 71, and the tip 17a of the nozzle 17 is disposed between the pair of opposing wall surfaces that define the center groove.

[0063] According to this embodiment, the pair of opposing wall surfaces 76a can be easily formed by the side grooves 76. Furthermore, compared to the first embodiment in which the pair of opposing wall surfaces 6a are formed by the pair of side protrusions 6, an increase in the amount of rubber can be suppressed.

[0064] [Third embodiment] Fig. 11 is a front view of a mouthpiece 80 according to a third modified example, similar to Fig. 2, and Fig. 12 is an enlarged view of a tread element 90 extruded from the mouthpiece 80, similar to Fig. 5. As shown in Fig. 11, the mouthpiece 80 differs from the mouthpiece 20 in that it has a protrusion 85 that protrudes downward at an open top surface 82 and extends in the extrusion direction E.

[0065] In this embodiment, the base 80 has, as the protrusions 85, side protrusions 86 formed between the pair of side notches 26 and a center protrusion 87 formed between the pair of center notches 27. The side protrusions 86 and the center protrusion 87 are formed in a trapezoidal shape whose left-right distance decreases downward so as to be continuous with both opposing side surfaces of the side notches 26 and the center notch 27. In addition, the side protrusions 86 and the center protrusions 87 may be formed in any cross-sectional shape, such as a rectangular, triangular, semicircular, or curved shape.

[0066] As shown in Figure 12, the tread element 90 has a pair of side ridges 96 formed by a pair of side notches 26 to protrude upward from the tread top surface 91, and a side groove 97 formed by a side projection 86 to recess downward from the tread top surface. The opposing side surfaces of the pair of side ridges 96 and the opposing side surfaces of the side grooves 97 are continuous in the vertical direction, and these form a pair of opposing wall surfaces 96a. The tip 16a of the nozzle 16 is disposed between the pair of opposing wall surfaces 96a. Although not shown, a pair of center ridges and center grooves are also formed by a pair of center notches 27 and a center projection 87, and the tip 17a of the nozzle 17 is disposed between these opposing wall surfaces.

[0067] According to this embodiment, the pair of opposing wall surfaces 96a can be easily formed by the pair of side ridges 96 and side grooves 97. In particular, it is easy to set the height of the side ridges 96 low and the depth of the side grooves 97 shallow, which makes it easy to both ensure the amount of rubber and prevent an increase in the amount of rubber.

[0068] The present invention is not limited to the configurations described in the above embodiments, and various modifications are possible.

[0069] In the above embodiment, the case where both the side color line 31 and the center color line 32 are provided has been described as an example, but this is not limited to this. For example, the present invention can be applied to various cases, such as when only the center color line 32 is provided, when only the side color line 31 is provided, when multiple side color lines 31 are provided, etc. [Explanation of symbols]

[0070] 1 Tread material 2 Tread top surface 5 protrusions 6 Side ridges 6a Opposite wall 7 Center ridge 7a Opposite wall 16 nozzles 17 nozzles 20 nozzle 21 Aperture 22 Opening top surface 25 Notch 26 Side notch 27 Center notch 30 colored rubber 31 Side color line 32 Center color line 40 forming drum 41 Laser Marker 50 Green Tires 51 Tread Ring 53 Carcass Band

Claims

1. a tread member that is a rubber extrusion profile that has a predetermined cross-sectional shape and extends in a first direction, and that has a first main surface that forms an outer peripheral surface in the tire radial direction of the green tire when wound cylindrically, and a pair of opposing wall surfaces that extend in the first direction on the first main surface and oppose each other in a second direction perpendicular to the first direction; a colored rubber extending in the first direction between the pair of opposing wall surfaces on the first main surface; It has The tread element is a pair of protrusions protruding from the first main surface and extending in the first direction; a groove recessed with respect to the first main surface between the pair of protrusions and extending in the first direction; It has The pair of opposing wall surfaces are a pair of side surfaces of the pair of protrusions that face each other in the second direction; Both side surfaces that form the groove and face each other in the second direction; A tread member having a color line,

2. a color rubber width dimension, which is the length of the color rubber in the second direction, is 67% or more and 133% or less of a wall surface interval, which is the length in the second direction on the first main surface between the pair of opposing wall surfaces; A tread element comprising the color line according to claim 1.

3. The height of the pair of opposing wall surfaces in a direction perpendicular to the first main surface is 3 mm or more and 4.5 mm or less. A tread element comprising the color line according to claim 1 or 2.

4. the tread element has a pair of protrusions protruding from the first main surface and extending in the first direction, The pair of opposing wall surfaces are formed by a pair of side surfaces of the pair of protrusions that are opposed to each other in the second direction. A tread element comprising the color line according to any one of claims 1 to 3.

5. the tread element has a groove recessed with respect to the first main surface and extending in the first direction, The pair of opposing wall surfaces constitute the groove and are configured by both side surfaces opposing each other in the second direction. A tread element comprising the color line according to any one of claims 1 to 3.

6. The wall spacing is 1.5 mm or more and 6.0 mm or less. A tread element provided with a color line according to claim 2 or any one of claims 3 to 5 dependent on claim 2.

7. The wall spacing is 0.20 mm or more and 1.50 mm or less. A tread element provided with a color line according to claim 2 or any one of claims 3 to 5 dependent on claim 2.

8. In the cross-sectional shape, the pair of opposing wall surfaces are perpendicular to the first main surface or inclined in directions away from each other, and the angle with respect to the first main surface is 60° or more and 90° or less. A tread element comprising the color line according to any one of claims 1 to 7.

9. A tread element is formed by extruding rubber from a mouthpiece in a first direction into a predetermined cross-sectional shape and having a first main surface that constitutes the outer peripheral surface of the green tire in the tire radial direction when the rubber is wound cylindrically, and a pair of opposing wall surfaces that extend in the first direction on the first main surface and oppose each other in a second direction perpendicular to the first direction, wherein the tread element comprises: a pair of protrusions protruding from the first main surface and extending in the first direction; a groove recessed with respect to the first main surface between the pair of protrusions and extending in the first direction; It has The pair of opposing wall surfaces are a pair of side surfaces of the pair of protrusions that face each other in the second direction; Both side surfaces that form the groove and face each other in the second direction; It is composed of A method for manufacturing a tread member having a color line, the method comprising: applying colored rubber onto the first main surface of the tread member transported in the first direction using a nozzle positioned between the pair of opposing wall surfaces.

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