JP2017061233A - Retreaded tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retreaded tire capable of improving durability.SOLUTION: A retreaded tire 10 is equipped with a base tire 20 comprising a buff processing of the tread of a used tire and having plural crossing belts 141, 142, and a tread 30 installed on the buff processing surface of the base tire 20 to compose a tread surface. The center area of the tread and a right and left shoulder area are defined using a position of 25% of a tire grounding width TW from a tire grounding end T as a boundary. Besides, a crossing belt 142 laminated at the outermost side in a tire radial direction is defined as an outermost crossing belt among the crossing belts 141, 142 having an edge in the shoulder area. Further, a perpendicular drawn from the edge of the outermost crossing belt 142 toward a tread profile in a cross-sectional view in a tire meridian direction is defined as a perpendicular line L1. At that time, a new rubber gauge T1 on a tire equator plane CL and another new rubber gauge T2 on the perpendicular line L1 have the relation of T2<T1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a retreaded tire, and more particularly to a retreaded tire that can improve durability.

  Rehabilitated tires are tires that are reused by replacing the tread rubber of a tire whose remaining groove has reached the end of its life. For example, rehabilitated tires for heavy loads attached to trucks and buses, commercial tires attached to light trucks, etc. Classified as car retread tires. As a conventional retread tire related to such a problem, a technique described in Patent Document 1 is known.

Japanese Patent No. 3138404

  In the manufacturing process of the retreaded tire, the tread rubber of the tire whose remaining groove has reached the end of its life is cut, and the outer peripheral surface thereof is buffed to obtain a base tire. At this time, in a general tire structure, when the buffing thickness in the tread portion center region is appropriately set, the buffing thickness in the shoulder region tends to increase. Then, the end of the outermost belt ply in the shoulder region is exposed, or the old rubber gauge in the shoulder region becomes thin, and the durability of the retread tire is deteriorated.

  Accordingly, the present invention has been made in view of the above, and an object thereof is to provide a retread tire that can improve durability.

  In order to achieve the above object, a retread tire according to the present invention includes a base tire having a plurality of cross belts formed by buffing a tread portion of a used tire, and a tread that is installed on a buff processing surface of the base tire. A retread tire comprising a tread constituting a surface, wherein a center region and left and right shoulder regions of a tread portion are defined with a position of 25 [%] of a tire ground contact width as a boundary from a tire ground contact edge, and an edge is formed in the shoulder region The cross belt laminated on the outermost side in the tire radial direction among the cross belts having a portion is defined as an outermost cross belt, and a tread profile from an edge portion of the outermost cross belt in a sectional view in the tire meridian direction When defining the perpendicular line L1 drawn on the tire, the new rubber gauge T1 on the tire equator plane and the new rubber gauge on the perpendicular line L1 And gauge T2 is characterized by having a relationship of T2 <T1.

  In the retreaded tire according to the present invention, the new rubber gauge T1 on the tire equatorial plane and the new rubber gauge T2 on the vertical line L1 in the tread newly added by retreading have a relationship of T2 <T1, so the edge of the outermost cross belt The old rubber gauge of the base tire at the part can be secured. This avoids exposure of the end of the outermost cross belt during buffing of the base tire, and secures the old rubber gauge of the base tire near the end of the outermost cross belt. Thereby, there exists an advantage which the durability of a tire improves.

FIG. 1 is a cross-sectional view in the tire meridian direction showing a retread tire according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a tread portion of the retread tire described in FIG. 1. FIG. 3 is an enlarged view showing a tread portion of the retread tire described in FIG. 1. FIG. 4 is an explanatory view showing a modified example of the retread tire described in FIG. 1. FIG. 5 is an explanatory view showing a modified example of the retread tire described in FIG. 1. FIG. 6 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Rehabilitated tire]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a retread tire according to an embodiment of the present invention. This figure shows a cross-sectional view of one side region in the tire radial direction. Moreover, the figure has shown the tire for commercial vehicles manufactured by the remolding method as an example of the retreaded tire.

  In the figure, the cross section in the tire meridian direction means a cross section when the tire is cut along a plane including a tire rotation axis (not shown). Reference sign CL denotes a tire equator plane, which is a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. Further, the tire width direction means a direction parallel to the tire rotation axis, and the tire radial direction means a direction perpendicular to the tire rotation axis.

  The retread tire 10 is a tire that is reused by replacing the tread rubber of a tire whose remaining groove has reached the end of its life. For example, the retread tire 10 is mounted on a heavy load retread tire mounted on a truck, a bus, etc. Classified as commercial vehicle retreaded tires.

  The retread tire 10 has an annular structure centered on the tire rotation axis, and includes a base tire 20 and a tread 30. The base tire 20 is a member formed by cutting out a part of the tread rubber and a part of the side wall rubber of the tire whose remaining groove has reached the end of life and buffing the outer peripheral surface thereof. The tread 30 is a rubber member that constitutes a new tread portion of the retread tire 10 and is attached to the base tire 20 and installed. The retread tire 10 is manufactured by a remolding method or a precure method, as will be described later.

  The retread tire 10 includes a pair of bead cores 11 and 11, a pair of bead fillers 12 and 12, a carcass layer 13, a belt layer 14, a tread rubber 15, and a pair of sidewalls as general components. Rubber 16 and 16 and a pair of rim cushion rubbers 17 and 17 are provided (see FIG. 1). Among these components, the tread rubber 15 is composed of a new tread 30 and a part of the tread rubber of the used tire remaining on the base tire 20 (reference numeral omitted). The sidewall rubber 16 and the rim cushion rubber 17 are included in the base tire 20.

  The carcass layer 13 is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. Further, both ends of the carcass layer 13 are wound and locked from the inner side in the tire width direction to the outer side in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, nylon, polyester, rayon, etc.) with a coating rubber and rolling them, and has an absolute value of 85 [deg] or more and 95. [Deg] The following carcass angle (defined as the inclination angle of the longitudinal direction of the carcass cord with respect to the tire circumferential direction). In the configuration of FIG. 1, the carcass layer 13 has a single-layer structure composed of a single carcass ply. However, the present invention is not limited to this, and the carcass layer 13 has a multilayer structure formed by laminating a plurality of carcass plies. Also good.

  The belt layer 14 is formed by laminating a plurality of belt plies, and is arranged around the outer periphery of the carcass layer 13. The plurality of belt plies are formed by rolling a plurality of belt cords made of steel or organic fiber material coated with a coat rubber, and are defined as a predetermined belt angle (the inclination angle of the belt cord in the longitudinal direction with respect to the tire circumferential direction). Have). Further, the plurality of belt plies include a pair of cross belts 141 and 142 having a belt angle of 10 [deg] or more and 55 [deg] or less in absolute value, and belt angles having mutually different signs. Also, a belt cover (not shown) having a belt angle of 45 [deg] or more and 70 [deg] or less in absolute value and laminated on the radially outer side of the pair of cross belts, 0 [deg] or more and 10 [absolute value] deg] A pair of belt edge covers (not shown) having the following belt angles and covering the left and right edge portions of the cross belt may be arranged.

  For example, in the configuration shown in FIG. 1, the retread tire 10 is a commercial vehicle tire, and the belt layer 14 is formed by laminating a pair of cross belts 141 and 142 made of steel belt cords.

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of rim cushion rubbers 17, 17 are respectively disposed on the inner side in the tire radial direction of the wound portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute the contact surfaces of the left and right bead portions with respect to the rim flange.

  Further, in the configuration of FIG. 1, the retread tire 10 includes a plurality of circumferential main grooves 21 and 22 that extend in the tire circumferential direction, and a plurality of land portions 31 to 33 that are partitioned by these circumferential main grooves. On the tread surface. Further, the circumferential main grooves 21 and 22 and the land portions 31 to 33 are disposed symmetrically about the tire equatorial plane CL. In addition, the left and right land portions 33, 33 on the outermost sides in the tire width direction have one circumferential narrow groove 23, respectively.

  The circumferential main groove is a groove having a duty indicator display obligation defined in JATMA. In a heavy load retread tire and a commercial vehicle retread tire, generally a groove width of 4.0 [mm] or more and a 6.5 [ mm] and a groove depth of 25.5 [mm] or less.

  The groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening in a no-load state in which the tire is mounted on the prescribed rim and filled with the prescribed internal pressure. In the configuration where the land part has a notch part or a chamfered part at the edge part, the groove width is based on the intersection of the tread surface and the extension line of the groove wall in a cross-sectional view in which the groove length direction is a normal direction. Measured. In the configuration in which the groove extends in a zigzag shape or a wave shape in the tire circumferential direction, the groove width is measured with reference to the center line of the amplitude of the groove wall.

  The groove depth is measured as the maximum value of the distance from the tread surface to the groove bottom in an unloaded state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a groove | channel has a partial uneven | corrugated | grooved part and a sipe in a groove bottom, groove depth is measured except these.

  The specified rim refers to an “applied rim” defined in JATMA, a “Design Rim” defined in TRA, or a “Measuring Rim” defined in ETRTO. The specified internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means the “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

[Rehabilitated tire by remolding method]
In the retread tire 10 manufactured by the remolding method, the tread 30 is unvulcanized rubber at the material stage, and constitutes the tread portion of the retread tire 10 at the product stage. Further, the tread 30 can be made of, for example, a strip-shaped unvulcanized rubber, a plate-shaped unvulcanized rubber, or the like.

  The remolded tire 10 by this remolding method is manufactured by the following process (not shown).

  First, the tread rubber of the tire whose remaining groove has reached the end of its life is cut out, and the outer peripheral surface thereof is buffed to obtain the base tire 20. This buffing process is performed in a state where an internal pressure is applied to the tire.

  Next, the tread 30 is disposed on the outer peripheral surface of the base tire 20. At this time, (a) strip-shaped unvulcanized rubber may be spirally wound around the outer peripheral surface of the base tire 20 to form the tread 30, or (b) a base plate-shaped rubber member may be formed. The tread 30 may be formed by being wound around the outer peripheral surface of the base tire 20 and spirally winding a strip-like unvulcanized rubber around the outer periphery. In the case of the latter (b), the time required for the installation process of the tread 30 can be shortened compared to the case of the former (a).

  Next, a vulcanization process is performed. In this vulcanization step, the assembly of the tread 30 and the base tire 20 is filled into a tire vulcanization mold (not shown) having a tire molding die. Next, the assembly of the tread 30 and the base tire 20 is expanded radially outward by the pressurizing device, and the tread 30 is pressed against the tire molding die. Further, the assembly of the tread 30 and the base tire 20 is heated, so that the tread 30 is vulcanized and the shape of the tire molding die is transferred to the tread 30. Thereafter, the vulcanized tire is taken out from the tire vulcanization mold.

[Rehabilitated tire by precure method]
In the retread tire 10 manufactured by the precure method, the tread 30 is a tread rubber (so-called precure tread) vulcanized at the material stage, and constitutes a tread portion of the retread tire 10. Further, the tread 30 has a plate-like structure or an annular structure, and has a tread pattern when the retread tire 10 is new on its outer peripheral surface in advance.

  The retreaded tire 10 by this precure method is manufactured by the following processes (not shown).

  First, the tread rubber of the tire whose remaining groove has reached the end of its life is cut out, and the outer peripheral surface thereof is buffed to obtain the base tire 20. This buffing process is performed in a state where an internal pressure is applied to the tire.

  Next, cushion rubber (not shown) is pasted over the entire circumference of the outer peripheral surface of the base tire 20. The cushion rubber is a sheet-like unvulcanized rubber at the material stage. Thereafter, the tread 30 is disposed on the outer peripheral surface of the base tire 20 and bonded to the base tire 20 via a cushion rubber.

  At this time, when the tread 30 has a plate-like structure, the tread 30 is wound around the base tire 20 and is fixed by temporarily fixing both ends by a fixing member (not shown). On the other hand, in the configuration in which the tread 30 has an annular structure, the tread 30 is expanded and contracted by a dedicated expanding / contracting diameter device (not shown) and is fitted to the outer periphery of the base tire 20.

  Next, a vulcanization process is performed. In this vulcanization process, the assembly of the tread 30 and the base tire 20 is accommodated in a vulcanization can (not shown), the air in the vulcanization can is sucked in vacuum, and then heated and pressurized. The cushion rubber is vulcanized. Thereafter, the vulcanized tire is taken out from the vulcanization can.

[Tread structure]
As described above, in the retreaded tire manufacturing process, the tread rubber of the tire whose remaining groove has reached the end of its life is cut out, and the outer peripheral surface thereof is buffed to obtain the base tire. At this time, in a general tire structure, when the buffing thickness in the tread portion center region is appropriately set, the buffing thickness in the shoulder region tends to increase. Then, the end of the outermost belt ply in the shoulder region is exposed, or the old rubber gauge in the shoulder region becomes thin, and the durability of the retread tire is deteriorated. On the other hand, if the buffing thickness in the shoulder region is set appropriately, the old rubber gauge in the center region becomes excessive, and the low heat buildup of the retread tire is deteriorated.

  Therefore, the retread tire 10 has the following tread configuration in order to improve durability and low heat generation.

  2 and 3 are enlarged views showing a tread portion of the retread tire described in FIG. In these drawings, FIG. 2 shows an enlarged cross-sectional view of one side region with the tire equatorial plane CL as a boundary, and FIG. 3 shows an enlarged cross-sectional view of the vicinity of a groove formed on the tread surface. In FIG. 2, point T is the tire ground contact end. In the configuration of FIG. 2, the retread tire 10 has a square shoulder, so that the tire ground contact end and the tread end (defined as a tread width measurement point) are in the same position.

  In FIG. 2, the center region and the left and right shoulder regions of the tread portion are defined with the position of 25 [%] of the tire ground contact width TW from the tire ground contact edge T as a boundary.

  The tire ground contact width TW is the contact surface between the tire and the flat plate when the tire is mounted on the specified rim to apply the specified internal pressure and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. It is measured as the maximum linear distance in the tire axial direction.

  Moreover, the cross belt 142 laminated | stacked on the outermost side of the tire radial direction among the cross belts 141 and 142 which have an edge part in a shoulder area | region is defined as an outermost cross belt. The belt layer 14 may include three or more cross belts (not shown). Further, a cross belt having an edge portion in the center region (that is, having no edge portion in the shoulder region) is excluded from the definition of the outermost cross belt.

  The edge portion of the cross belt is defined by the belt cord located on the outermost side in the tire width direction among the belt cords constituting the cross belt in a sectional view in the tire meridian direction.

  In addition, a perpendicular line L1 drawn from the edge portion of the outermost cross belt 142 to the tread profile in a cross-sectional view in the tire meridian direction is defined. More specifically, the perpendicular line L1 is defined as a straight line that passes through the center of the belt cord at the edge of the outermost cross belt 142 and is perpendicular to the tread profile.

  The tread profile is an outline of the tread surface in a cross-sectional view in the tire meridian direction, and is measured using a laser profiler in a no-load state in which a tire is mounted on a specified rim and filled with a specified internal pressure. As the laser profiler, for example, a tire profile measuring device (manufactured by Matsuo Corporation) is used.

  At this time, the new rubber gauge T1 on the tire equatorial plane CL and the new rubber gauge T2 on the perpendicular L1 have a relationship of T2 <T1. Specifically, it is necessary that the actual dimensions of the new rubber gauges T1 and T2 satisfy the relationship of 0.2 [mm] ≦ T1-T2. Moreover, it is preferable that the new rubber gauges T1 and T2 have a relationship of T2 / T1 ≦ 0.93. The lower limit of the ratio T2 / T1 is not particularly limited, but is restricted by the relationship with tread gauges Tc, Ts and the like described later. In a general heavy-duty tire having a circumferential main groove in the tread shoulder region, the ratio T2 / T1 is in the range of 0.30 ≦ T2 / T1.

  The new rubber gauges T1 and T2 are rubber gauges of the tread 30 newly added by rehabilitation, and are measured as a distance from the tread profile to the buffed surface of the base tire in a sectional view in the tire meridian direction.

  In the case of a general heavy load tire, as shown in FIG. 2, the edge portions of the pair of cross belts 141 and 142 are the outermost circumferential main grooves 22 (circumferential main grooves 22 on the outermost side in the tire width direction). Defined) and extends outward in the tire width direction and is located in the tread shoulder region. However, the present invention is not limited to this, and some cross belts may be positioned on the inner side in the tire width direction with respect to the outermost circumferential main groove 22 (not shown).

  In FIG. 2, the tread gauge Tc on the tire equatorial plane CL and the tread gauge Ts on the normal L1 have a relationship of 0.80 ≦ Ts / Tc ≦ 1.30.

  Furthermore, it is preferable that the tread gauges Tc and Ts have a relationship of Tc <Ts. Specifically, it is preferable that the actual dimensions of the tread gauges Tc and Ts satisfy the relationship of 0.2 [mm] ≦ Ts−Tc. In this case, the old rubber gauge Tc-T1 of the base tire 20 on the tire equatorial plane CL and the old rubber gauge Ts-T2 of the base tire 20 on the vertical line L1 inevitably have a relationship of Tc-T1 <Ts-T2. Have

  In the tread shoulder region, the new rubber gauge T2 and the tread gauge Ts on the perpendicular L1 preferably have a relationship of 1.0 [mm] ≦ Ts−T2 ≦ 5.0 [mm], and 2.0 [ It is more preferable to have a relationship of mm] ≦ Ts−T2 ≦ 4.0 [mm].

  The tread gauges Tc and Ts are the sum of the new rubber gauges T1 and T2 of the new tread 30 and the old rubber gauge of the tread rubber remaining on the base tire 20, and the tread profile and the belt layer in the tire meridian cross-sectional view. It is measured as a distance from an imaginary line that smoothly connects the top surfaces of the belt cords constituting the outermost layer 14 in the tire radial direction.

  In a general heavy load tire, the new rubber gauge T1 and the tread gauge Tc on the tire equatorial plane CL are 7.5 [mm] ≦ T1 ≦ 31.0 [mm] and 8.5 [mm] ≦ Tc ≦. It is in the range of 36.5 [mm].

  In the above configuration, the new rubber gauge T1 on the tire equatorial plane CL and the new rubber gauge T2 on the vertical line L1 in the tread 30 newly added by rehabilitation have a relationship of T2 <T1, so that the vertical line L1 on the base tire 20 The old rubber gauge (Ts-T2 in FIG. 2) can be secured. Thereby, exposure of the end of the outermost cross belt 142 during the buffing of the base tire 20 is avoided, and the old rubber gauge of the base tire 20 in the vicinity of the end of the outermost cross belt 142 is secured. Thereby, durability of a tire improves.

  In the configuration of FIG. 2, the curvature radius Ra1 of the tread profile and the curvature radius Ra2 of the buffed surface of the base tire 20 have a relationship of Ra1 <Ra2. Specifically, the curvature radii Ra1 and Ra2 preferably have a relationship of 1.1 ≦ Ra2 / Ra1 ≦ 2.0, and more preferably have a relationship of 1.3 ≦ Ra2 / Ra1 ≦ 1.7. .

  The radius of curvature Ra2 of the buffed surface is a radius of curvature in a cross-sectional view in the tire meridian direction of the portion facing the tread profile of the buffed surface of the base tire 20, and the tire is mounted on the specified rim and filled with the specified internal pressure. Measured with a laser profiler under no load. Therefore, the buffed surface facing the sidewall portion is excluded from the measurement target of the radius of curvature.

  In FIG. 3, a new rubber sub-groove gauge G1 of the deepest groove disposed in the center region and a new rubber sub-groove gauge G2 of the deepest groove disposed in the shoulder region are 1.0 [mm] ≦ G1 ≦ 3.5 [mm] and 1.0 [mm] ≦ G2 ≦ 3.5 [mm].

  Furthermore, it is preferable that the new under-groove gauges G1 and G2 have a relationship of G2 <G1. Specifically, the actual dimensions of the new under-groove gauges G1 and G2 satisfy the relationship of 0.5 [mm] ≦ G1-G2, and 1.5 [mm] ≦ G1 ≦ 3.5 [mm]. And it is preferable that it exists in the range of 1.0 [mm] <= G2 <= 3.0 [mm].

  The new rubber sub-groove gauges G1 and G2 are rubber gauges of the new tread 30 at the maximum groove depth position of the groove, and buffing of the base tire 20 from the maximum groove depth position of the groove in a sectional view in the tire meridian direction. Measured as the distance to the surface. In addition, the new rubber sub-groove gauges G1 and G2 of the deepest groove disposed in each region are to be measured. The grooves include, for example, circumferential main grooves 21 and 22, a circumferential narrow groove 23, a lug groove (not shown), and the like.

  In FIG. 3, the total sub-groove gauge Gc of the deepest groove disposed in the center region and the total sub-groove gauge Gs of the deepest groove disposed in the shoulder region are 4.5 [mm] ≦ Gc ≦ It is in the range of 7.5 [mm] and 4.5 [mm] ≦ Gs ≦ 7.5 [mm]. The mutual relationship between the total sub-groove gauges Gc and Gs is not particularly limited, but the maximum groove depths Hc and Hs of the deepest groove disposed in each region, and the ratio Ts / Tc of the tread gauge of the new tread 30 Further, there is a restriction due to the relationship with the ratio of radius of curvature Ra2 / Ra1 described above.

  The total sub-groove gauges Gc and Gs are the sum of the new rubber sub-groove gauges G1 and G2 of the new tread 30 and the old rubber gauge of the tread rubber remaining on the base tire 20. Is measured as the distance between the maximum groove depth position and the imaginary line that smoothly connects the top surfaces of the belt cords constituting the outermost layer of the belt layer 14 in the tire radial direction.

  Further, the total sub-groove gauge Gc and the new rubber sub-groove gauge G1 of the deepest groove disposed in the center region have a relationship of 1.0 [mm] ≦ Gc−G1. In addition, the total sub-groove gauge Gs and the new rubber sub-groove gauge G2 of the deepest groove disposed in the shoulder region have a relationship of 1.0 [mm] ≦ Gs−G2. That is, the old rubber gauges Gc-G1 and Gs-G2 of the tread rubber remaining on the base tire 20 are 1.0 [mm] or more. The upper limits of the old rubber gauges Gc-G1 and Gs-G2 are not particularly limited, but are restricted by the relationship with the numerical ranges of the total under-groove gauges Gc and Gs and the new under-groove gauges G1 and G2.

[Modification]
FIG. 4 is an explanatory view showing a modified example of the retread tire described in FIG. 1. The figure shows a case where the belt layer 14 has a belt edge cover 143.

  In the configuration of FIG. 1, the outermost cross belt 142 is located in the outermost layer of the belt layer 14 as shown in FIG. 2. Then, the tread gauges Tc and Ts and the total sub-groove gauges Gc and Gs are measured using the outer peripheral surface of the outermost cross belt 142 as a measurement point.

  On the other hand, the belt layer 14 may include one or both of a belt cover and a belt edge cover in the outermost layer. The belt cover and the belt edge cover are configured by coating a belt cord made of steel or an organic fiber material with a coat rubber, and have a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. The belt cover and the pair of belt edge covers are, for example, a strip material formed by coating one or a plurality of belt cords with a coat rubber, and this strip material is a tire with respect to the outer peripheral surfaces of the cross belts 141 and 142. It is configured by winding a plurality of times in the circumferential direction and spirally. The belt cover is disposed so as to cover the entire area of the cross belts 141, 142, and the pair of belt edge covers are disposed so as to cover only the left and right edge portions of the cross belts 141, 142.

  In the configuration in which the belt layer 14 includes the belt cover or the belt edge cover described above, the outer circumferential surface of the belt cover or the belt edge cover in which the tread gauges Tc and Ts and the total groove lower gauges Gc and Gs are the outermost layers of the belt layer 14. Is measured as a measurement point. Specifically, a virtual line that smoothly connects the top surfaces of the belt cords constituting the belt cover or the belt edge cover on the outer side in the tire radial direction is the measurement point. Therefore, the thicknesses of the belt cover and the belt edge cover are excluded from the measurement targets of the tread gauges Tc and Ts and the total sub-groove gauges Gc and Gs.

  For example, in the modification of FIG. 4, the belt layer 14 includes a pair of belt edge covers 143 that cover the left and right edge portions of the outermost cross belt 142. Further, these belt edge covers 143 constitute the outermost layer of the belt layer 14. Then, the tread gauge Ts is measured using the intersection of the perpendicular L1 drawn from the edge portion of the outermost cross belt 142 to the tread profile and the outer peripheral surface of the belt edge cover 143 as a measurement point.

  FIG. 5 is an explanatory view showing a modified example of the retread tire described in FIG. 1. This figure shows an enlarged view of the outermost circumferential main groove 22 and the circumferential narrow groove 23 arranged in the shoulder region of the tread portion.

  In the configuration of FIG. 1, as shown in FIG. 3, the outermost circumferential main groove 22 and the circumferential narrow groove 23 in the tread shoulder region have the same maximum groove depth Hs. Then, the new sub-groove gauge G2 and the total sub-groove gauge Gs are measured using the maximum groove depth position of the circumferential narrow groove 23 as a measurement point.

  In contrast, in the configuration of FIG. 5, the circumferential narrow groove 23 is a shallow groove, and the outermost circumferential main groove 22 has a maximum groove depth Hs deeper than the circumferential narrow groove 23. Therefore, the new sub-groove gauge G2 and the total sub-groove gauge Gs are measured using the maximum groove depth position of the outermost circumferential main groove 22 as a measurement point.

  In a general heavy duty tire, as shown in FIGS. 2 and 5, the outermost circumferential main groove 22 is located in the tread portion shoulder region. Further, the groove depth of the outermost circumferential main groove 22 is equal to or greater than the groove depths of the other circumferential narrow grooves 23 and lug grooves.

[effect]
As described above, the retreaded tire 10 is formed by buffing a tread portion of a used tire and having a plurality of cross belts 141 and 142 and a buffed surface of the base tire 20. And a tread 30 constituting a tread surface (see FIG. 1). Further, the center region of the tread portion and the left and right shoulder regions are defined with the position of 25 [%] of the tire ground contact width TW from the tire ground contact edge T as a boundary, and the tires of the cross belts 141 and 142 having edge portions in the shoulder regions The cross belt 142 laminated on the outermost side in the radial direction is defined as the outermost cross belt, and a perpendicular line L1 drawn from the edge portion of the outermost cross belt 142 to the tread profile is defined in a cross-sectional view in the tire meridian direction ( (See FIG. 2). At this time, the new rubber gauge T1 on the tire equatorial plane CL and the new rubber gauge T2 on the perpendicular L1 have a relationship of T2 <T1.

  In such a configuration, the new rubber gauge T1 on the tire equatorial plane CL and the new rubber gauge T2 on the vertical line L1 in the tread 30 newly added by rehabilitation have a relationship of T2 <T1, so that the edge portion of the outermost cross belt 142 The old rubber gauge (Ts-T2 in FIG. 2) of the base tire 20 can be secured. Thereby, exposure of the end of the outermost cross belt 142 during the buffing of the base tire 20 is avoided, and the old rubber gauge of the base tire 20 in the vicinity of the end of the outermost cross belt 142 is secured. Thereby, there exists an advantage which the durability of a tire improves.

  In the retread tire 10, the new rubber gauge T1 on the tire equatorial plane CL and the new rubber gauge T2 on the perpendicular L1 have a relationship of T2 / T1 ≦ 0.93 (see FIG. 2). In such a configuration, since the new rubber gauge T2 at the edge portion of the outermost cross belt 142 is set to be small, the old rubber gauge (Ts-T2 in FIG. 2) of the base tire 20 at the edge portion of the outermost cross belt 142 can be secured. Thereby, there exists an advantage by which exposure of the edge part of the outermost cross belt 142 at the time of the buff process of the base tire 20 is avoided appropriately.

  In the retread tire 10, the tread gauge Tc on the tire equatorial plane CL and the tread gauge Ts on the perpendicular L1 have a relationship of 0.80 ≦ Ts / Tc ≦ 1.30 (see FIG. 2). Thereby, there is an advantage that the tread gauges Tc and Ts are made uniform. That is, when 0.80 ≦ Ts / Tc, center wear due to an excessively large tread gauge Tc in the tread portion center region is suppressed. Further, when Ts / Tc ≦ 1.30, shoulder wear caused by an excessively large tread gauge Ts in the tread shoulder region is suppressed.

  In this retread tire 10, the tread gauge Tc on the tire equatorial plane CL and the tread gauge Ts on the perpendicular L1 have a relationship of Tc <Ts (see FIG. 2). In such a configuration, since the tread gauge Ts on the vertical line L1 is set large, the old rubber gauge (Ts-T2 in FIG. 2) of the base tire 20 at the edge portion of the outermost cross belt 142 can be secured. Thereby, there exists an advantage by which exposure of the edge part of the outermost cross belt 142 at the time of the buff process of the base tire 20 is avoided appropriately.

  In this retread tire 10, the radius of curvature Ra1 of the tread profile and the radius of curvature Ra2 of the buffed surface of the base tire 20 have a relationship of Ra1 <Ra2 (see FIG. 2). In such a configuration, since the radius of curvature Ra2 of the buffed surface of the base tire 20 is large, the old rubber gauge (Ts-T2 in FIG. 2) of the base tire 20 at the edge portion of the outermost cross belt 142 can be secured. Thereby, there exists an advantage by which exposure of the edge part of the outermost cross belt 142 at the time of the buff process of the base tire 20 is avoided appropriately.

  In this retread tire 10, the radius of curvature Ra1 of the tread profile and the radius of curvature Ra2 of the buffed surface of the base tire 20 have a relationship of 1.1 ≦ Ra2 / Ra1 ≦ 2.0 (see FIG. 2). . Thereby, there exists an advantage by which the curvature radius Ra2 of the buff processing surface of the base tire 20 is optimized. That is, by satisfying 1.1 ≦ Ra2 / Ra1, the radius of curvature Ra2 of the buffed surface is ensured, and the old rubber gauge (Ts−T2 in FIG. 2) of the base tire 20 at the edge of the outermost cross belt 142 is obtained. Secured. In addition, since Ra2 / Ra1 ≦ 2.0, it is possible to suppress a situation where the low heat generation property of the tire is deteriorated due to an increase in the old rubber gauge of the base tire 20 in the shoulder region.

  Further, in this retreaded tire 10, a new rubber sub-groove gauge G1 of the deepest groove arranged in the center region and a new rubber sub-groove gauge G2 of the deepest groove arranged in the shoulder region satisfy G2 <G1. There is a relationship (see FIG. 3). In such a configuration, since the new rubber sub-groove gauge G2 in the shoulder region is small, the old rubber gauge Gs-G2 of the base tire 20 in the shoulder region can be increased. Thereby, there exists an advantage which can avoid appropriately the exposure of the edge part of the outermost cross belt 142 at the time of the buff process of the base tire 20. FIG.

  Further, in this retread tire 10, the new rubber sub-groove gauge G1 of the deepest groove disposed in the center region and the new rubber sub-groove gauge G2 of the deepest groove disposed in the shoulder region are 1.0 [mm. ] ≦ G1 ≦ 3.5 [mm] and 1.0 [mm] ≦ G2 ≦ 3.5 [mm] (see FIG. 3). Thereby, there exists an advantage by which new rubber | gum under groove gauges G1 and G2 are optimized. That is, when 1.0 [mm] ≦ G1 and 1.0 [mm] ≦ G2, the new under-groove gauges G1 and G2 are appropriately secured, and the occurrence of groove cracks is suppressed. Further, the old rubber gauges Gc-G1 and Gs-G2 of the base tire 20 are secured by G1 ≦ 3.5 [mm] and G2 ≦ 3.5 [mm], and the outermost intersection at the time of buffing the base tire 20 The exposure of the edge portion of the belt 142 can be appropriately avoided.

  Further, in this retread tire 10, the total sub-groove gauge Gc of the deepest groove disposed in the center region and the total sub-groove gauge Gs of the deepest groove disposed in the shoulder region are 4.5 [mm] ≦ It is in the range of Gc ≦ 7.5 [mm] and 4.5 [mm] ≦ Gs ≦ 7.5 [mm] (see FIG. 3). Thereby, there exists an advantage by which the total groove | channel gages Gc and Gs are optimized. That is, by satisfying 4.5 [mm] ≦ Gc and 4.5 [mm] ≦ Gs, the old rubber gauges Gc-G1 and Gs-G2 of the base tire 20 are secured, and the base tire 20 is buffed. Exposure of the edge portion of the outermost cross belt 142 can be appropriately avoided. Further, when Gc ≦ 7.5 [mm] and Gs ≦ 7.5 [mm], the deterioration of the low heat generation property of the tire due to excessive total sub-groove gauges Gc and Gs is suppressed. .

  Further, in this retreaded tire 10, the total sub-groove gauge Gc and the new rubber sub-groove gauge G1 of the deepest groove disposed in the center region have a relationship of 1.0 [mm] ≦ Gc−G1, and The total sub-groove gauge Gs and the new rubber sub-groove gauge G2 of the deepest groove disposed in the shoulder region have a relationship of 1.0 [mm] ≦ Gs−G2 (see FIG. 3). Thereby, the old rubber gauges Gc-G1 and Gs-G2 of the base tire 20 are secured, and the exposure of the edge portion of the outermost cross belt 142 during the buffing of the base tire 20 can be appropriately avoided.

  The retread tire 10 is manufactured by a remolding method. In the remolding method, unvulcanized rubber is attached to a base tire and vulcanization molding is performed, so that the tire is easily deformed. For this reason, there exists a subject that the low exothermic property of a retreaded tire is inferior compared with a precure system. Therefore, by using the remolded retreaded tire 10 as an application object, there is an advantage that the effect of improving the low heat generation can be remarkably obtained.

  FIG. 6 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, the durability performance was evaluated for a plurality of types of test tires. Further, a test tire having a tire size of 205 / 85R16 117 / 115L LTR is assembled to an applicable rim defined by JATMA, and a maximum air pressure and a maximum load defined by JATMA are applied to the test tire. In addition, the test tire is attached to all wheels of a truck having a maximum loading capacity of 3 [ton], which is a test vehicle. The test vehicle travels on a general paved road of 50,000 [km] at an average speed of 30 [km / h]. Thereafter, the circumferential length of the separation of the peripheral rubber generated at the edge portion of the outermost cross belt is measured, and index evaluation based on the conventional example as the standard (10) is performed. In this evaluation, the smaller the numerical value, the smaller the generated separation, which is preferable. Further, if the evaluation is 2 or less, it can be said that the effect of suppressing the separation is obtained.

  The test tires of Examples 1 to 8 have the configurations of FIGS. 1 to 3, and the new rubber gauge T1 on the tire equator plane CL and the new rubber gauge T2 on the perpendicular L1 have a relationship of T2 <T1. Further, the tire ground contact width TW is TW = 200 [mm], the new rubber gauge T1 and the tread gauge Tc on the tire equatorial plane CL are T1 = 13.5 [mm] and Tc = 16 [mm], The radius of curvature Ra1 of the tread profile in the region is Ra1 = 500 [mm], and the groove depths of the circumferential main grooves 21 and 22 and the circumferential narrow groove 23 are 10 [mm]. Further, the new sub-groove gauge G1 and the total sub-groove gauge Gc of the circumferential main groove 21 in the center region are G1 = 3.5 [mm] and Gc = 6 [mm].

  In the test tires of the conventional example, comparative example 1 and comparative example 2, in the test tire of example 1, the new rubber gauge T1 on the tire equatorial plane CL and the new rubber gauge T2 on the perpendicular L1 have a relationship of T1 <T2. Have.

  As the test results show, it can be seen that in the test tires of Examples 1 to 8, the durability performance of the tire is improved.

  10: retread tire, 20: tire, 30: tread, 11: bead core, 12: bead filler, 13: carcass layer, 14: belt layer, 141, 142: cross belt, 143: belt edge cover, 15: tread rubber , 16: sidewall rubber, 17: rim cushion rubber, 21, 22: circumferential main groove, 23: circumferential narrow groove, 31-33: land portion

Claims (11)

A retread tire comprising a base tire having a plurality of cross belts formed by buffing a tread portion of a used tire, and a tread that is installed on a buff processing surface of the base tire and constitutes a tread surface,
The center region of the tread portion and the left and right shoulder regions are defined with the position of 25 [%] of the tire contact width from the tire contact edge as a boundary, and the outermost portion in the tire radial direction of the cross belt having the edge portion in the shoulder region When defining the perpendicular line L1 drawn to the tread profile from the edge portion of the outermost cross belt in a cross-sectional view in the tire meridian direction,
A renewed tire characterized in that a new rubber gauge T1 on the tire equatorial plane and a new rubber gauge T2 on the perpendicular L1 have a relationship of T2 <T1.   The retreaded tire according to claim 1, wherein the new rubber gauge T1 on the tire equatorial plane and the new rubber gauge T2 on the perpendicular L1 have a relationship of T2 / T1≤0.93.   The retreaded tire according to claim 1 or 2, wherein the tread gauge Tc on the tire equatorial plane and the tread gauge Ts on the perpendicular L1 have a relationship of 0.80≤Ts / Tc≤1.30.   The retreaded tire according to any one of claims 1 to 3, wherein the tread gauge Tc on the tire equatorial plane and the tread gauge Ts on the vertical line L1 have a relationship of Tc <Ts.   The retreaded tire according to any one of claims 1 to 4, wherein a curvature radius Ra1 of the tread profile and a curvature radius Ra2 of the buffed surface of the base tire have a relationship of Ra1 <Ra2.   The retreaded tire according to claim 5, wherein a curvature radius Ra1 of the tread profile and a curvature radius Ra2 of the buffed surface of the base tire have a relationship of 1.1 ≦ Ra2 / Ra1 ≦ 2.0.   The deepest new groove sub-gauge gauge G1 disposed in the center region and the deepest new rubber sub-groove gauge G2 disposed in the shoulder region have a relationship of G2 <G1. The retreaded tire according to any one of 6.   The new rubber sub-groove gauge G1 of the deepest groove disposed in the center region and the new rubber sub-groove gauge G2 of the deepest groove disposed in the shoulder region are 1.0 [mm] ≦ G1 ≦ 3. The retreaded tire according to any one of claims 1 to 7, which is in a range of 5 [mm] and 1.0 [mm] ≤ G2 ≤ 3.5 [mm].   The total sub-groove gauge Gc of the deepest groove disposed in the center region and the total sub-groove gauge Gs of the deepest groove disposed in the shoulder region are 4.5 [mm] ≦ Gc ≦ 7.5 [ mm] and 4.5 [mm] ≦ Gs ≦ 7.5 [mm]. Rehabilitated tire according to any one of claims 1 to 8. The total sub-groove gauge Gc and the new rubber sub-groove gauge G1 of the deepest groove disposed in the center region have a relationship of 1.0 [mm] ≦ Gc−G1, and
The total sub-groove gauge Gs and the new rubber sub-groove gauge G2 of the deepest groove disposed in the shoulder region have a relationship of 1.0 [mm] ≦ Gs−G2. The rehabilitated tire described.   The retreaded tire according to any one of claims 1 to 10, which is manufactured by a remolding method.

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