Patent Application
20130306212
The present invention relates to a patch rubber for repairing a radial tire, a method for repairing a radial tire by using the patch rubber, and a radial tire repaired by the patch rubber. In particular, the present invention relates to a patch rubber for repairing a radial tire, which patch rubber is put, when a radial carcass ply and a belt ply are damaged in a tread portion of the radial tire, on these damaged portions inside the tire for reinforcing the damaged portions, a method for repairing a radial tire by using the patch rubber, and a radial tire repaired by the patch rubber.
A tread portion of a radial tire, in particular, a super large-size radial tire such as a tire for a construction vehicle is sometimes damaged by penetration of a bolt, a sharply cracked stone, or the like therethrough, so that both a carcass ply as rubber-coated carcass ply cords and a belt ply as rubber-coated belt cords disposed on the tire radially outer side of the carcass ply break.
There has been proposed as a method for repairing a radial tire of which tread portion has been damaged as described above a method for repairing a damaged radial tire by attaching a patch rubber, constituted of a reinforcing cord layer formed by coating plural reinforcing cords aligned in parallel to each other with rubber, on a damaged portion of a tread portion, i.e. a broken carcass ply cord and a broken belt cord, inside the tire by using an adhesive so that the damaged portion is reinforced by the path rubber (e.g. Patent Literature 1).
The conventional method for repairing a damaged radial tire described above also employs a patch rubber constituted as a laminate of plural reinforcing cord layers in terms of reliably obtaining a reinforcing effect.
In the case of the conventional patch rubber for repairing a damaged radial tire described above, however, respective end positions of reinforcing cords are aligned in the layer-lamination direction in the plural reinforcing cord layers, whereby respective end faces, relatively weakly adhered to rubber, of the reinforcing cords are positioned with relatively short interval therebetween in the layer-lamination direction. As a result, in a radial tire of which damaged portions have been repaired by using the aforementioned conventional patch rubber for repair, cracks generated between end faces, relatively weakly adhered to rubber, of the reinforcing cords and rubber surrounding the end faces easily spread across the end faces of the reinforcing cords adjacent to each other with relatively short intervals therebetween, possibly causing troubles at an early stage in the repaired radial tire.
In view of the situation described above, an object of the present invention is to provide a patch rubber for repairing a radial tire, which patch rubber is capable of preventing troubles from occurring at an early stage in a repaired radial tire to enhance durability of the repaired radial tire. Further, another object of the present invention is to provide a method for repairing a radial tire by using the patch rubber, and a radial tire repaired by the patch rubber.
The present invention, aiming at advantageously solving the problems described above, provides in a first aspect thereof a patch rubber for repairing a radial tire, the patch rubber being constituted of reinforcing cord layers each formed by coating plural reinforcing cords aligned in parallel to each other with rubber, characterized in that: the reinforcing cord layers constitute a laminate in which they are laminated from one side to the other side; and provided that: i) a region defined by a contour curve connecting adjacent cord ends of the plural reinforcing cords at one end side thereof, another contour curve connecting adjacent cord ends of the plural reinforcing cords at the other end side thereof, and the outermost reinforcing cords in a cord-juxtaposing direction of the plural reinforcing cords represents a reinforcing region in each reinforcing cord layer; ii) one reinforcing cord layer has one reinforcing region; and iii) another reinforcing cord layer, which includes the reinforcing cords having the same cord-extending direction as the reinforcing cords of the one reinforcing cord layer and is laminated on the other side in the layer-lamination direction of the one reinforcing cord layer, has another reinforcing region, the another reinforcing region resides within the one reinforcing region.
It is possible to prevent end faces, relatively weakly adhered to rubber, of the reinforcing cords of the one reinforcing cord layer from being positioned at relatively short interval in the layer-lamination direction with respect to the corresponding end faces of the reinforcing cords extending in the same direction as the reinforcing cords of the one reinforcing cord layer, of another reinforcing cord layer poisoned in the other side in the layer-lamination direction, by designing the one reinforcing region of the one reinforcing cord layer to reside within the another reinforcing region of the another reinforcing cord layer as described above. As a result, cracks generated between the end faces of the reinforcing cords and rubber surrounding the end faces are prevented from spreading across the end faces of the reinforcing cords adjacent to each other in the layer-lamination direction, thereby successfully enhancing durability of the radial tire repaired by using the patch rubber.
The “plural reinforcing cords aligned in parallel to each other” do not represent reinforcing cords aligned strictly in parallel to each other in mathematical terms but reinforcing cords simply extending in the same direction in the present invention. Further, “the cord-juxtaposing direction” represents a direction orthogonal to the cord extending direction in the present invention.
In a second aspect of the present invention, it is preferable that the patch rubber for repairing a radial tire is further characterized in that: the cord-extending direction of the reinforcing cords of at least one of the reinforcing cord layers is orthogonal to the cord-extending direction of the reinforcing cords of the rest of the reinforcing cord layers; width in the cord juxtaposing direction of the at least one of the reinforcing cord layers is narrower than length in the cord-extending direction of the outermost reinforcing cords in the cord juxtaposing direction of the rest of the reinforcing cord layers; and width in the cord-juxtaposing direction of the rest of the reinforcing cord layers is narrower than length in the cord-extending direction of the outermost reinforcing cords in the cord juxtaposing direction of the at least one of the reinforcing cord layers.
A reinforcing effect of the patch rubber caused by a hooping effect thereof of suppressing popping-out of damaged portions due to internal pressure and rotation of the tire is enhanced and durability of the radial tire repaired by the patch rubber is further improved by designing the patch rubber such that the cord-extending direction of the reinforcing cords of at least one of the reinforcing cord layers is orthogonal to the cord-extending direction of the reinforcing cords of the rest of the reinforcing cord layers as described above.
A “width in the cord-juxtaposing direction” represents a distance in the cord juxtaposing direction between the two reinforcing cords disposed on outermost edges in the cord-juxtaposing direction.
Further, in a third aspect of the present invention, it is preferable that the patch rubber for repairing a radial tire is further characterized in that tensile modulus of elasticity of the reinforcing cords of the at least one of the reinforcing cord layers is higher than tensile modulus of elasticity of the reinforcing cords of the rest of the reinforcing cord layers.
Yet further, in a fourth aspect of the present invention, it is preferable that the patch rubber for repairing a radial tire is further characterized in that the at least one of the reinforcing cord layers is disposed on the outermost side in the layer-lamination direction in the laminate.
Yet further, in a fifth aspect of the present invention, it is preferable that the patch rubber for repairing a radial tire is further characterized in that the reinforcing cords of the at least one of the reinforcing cord layers are aramid cords or glass fiber cords.
Yet further, in a sixth aspect of the present invention, it is preferable that the patch rubber for repairing a radial tire is further characterized in that the at least one of the reinforcing cord layers is thicker than each of the rest of the reinforcing cord layers.
Yet further, in a seventh aspect of the present invention, it is preferable that the patch rubber for repairing a radial tire is further characterized in that: the plural reinforcing cords are constituted of: a long reinforcing cord having the longest length in the cord-extending direction among the reinforcing cords; and at least a pair of reinforcing cord disposed on respective sides in the cord-juxtaposing direction orthogonal to the cord-extending direction, of the long reinforcing cord; and cord ends of the reinforcing cord disposed the closer to the long reinforcing cord are positioned on the more outer side in the cord-extending direction, in said at least a pair of reinforcing cords disposed on respective sides in the cord-juxtaposing direction of the long reinforcing cord.
In an eighth aspect of the present invention, a method for repairing a radial tire having a tread portion, a pair of sidewall portions extending on the tire radially inner side from respective sides of the tread portion, a pair of bead portions extending on the tire radially inner side from the respective sidewalls, a radial carcass ply including at least one ply formed by plural ply cords coated with ply rubber and extending in a toroidal shape across the bead portions, and a belt ply including at least one ply formed by plural belt cords coated with belt rubber, comprises the steps of: attaching, when at least one of the ply cords of the radial carcass ply and the belt cords of the belt ply are broken in at least one of the sidewall portions and the tread portion, a patch rubber for radial tire repair on at least one of a damaged portion of the broken ply cords of the radial carcass ply and a damaged portion of the broken belt cords of the belt ply from at least one of the inner side and the outer side of the tire, for reinforcing the damaged portion; and using the patch rubber for repairing a radial tire of any of the first to seventh aspects of the present invention and attaching it on the damaged portion of the radial tire in the aforementioned reinforcing step.
Durability of a radial tire repaired by a patch rubber can be significantly enhanced by repairing the radial tire by using the patch rubber structured as described above.
Yet further, in a ninth aspect of the present invention, it is preferable that the method for repairing a radial tire is further characterized in that the reinforcing step comprising: attaching, when the ply cords of the radial carcass ply are broken in the sidewall portion, the patch rubber on the damaged portion of the broken ply cords of the radial carcass ply such that the reinforcing cords of all of the reinforcing cord layers constituting the patch rubber are inclined at an angle in the range of 0° to 30° with respect to the cord-extending direction of the ply cords of the radial carcass ply. The reinforcing effect caused by the patch rubber on the damaged portion of the broken carcass ply improves by attaching the patch rubber as described above.
Yet further, in a tenth aspect of the present invention, it is preferable that the method for repairing a radial tire is further characterized in that the reinforcing step comprising: attaching, when the belt cords of the belt ply are broken in the tread portion, the patch rubber on the damaged portion of the broken belt cords of the belt ply such that the reinforcing cords of at least one of the plural reinforcing cord layers constituting the patch rubber are inclined at an angle in the range of 0° to 30° with respect to the tire circumferential direction and the reinforcing cords of the rest of the plural reinforcing cord layers are inclined at an angle in the range of 0° to 30° with respect to the cord-extending direction of the ply cords of the radial carcass ply.
The reinforcing effect caused by the patch rubber on the damaged portion(s) of at least one of the broken carcass ply and the broken belt ply improves by attaching the patch rubber as described above.
An angle formed between the reinforcing cords of the patch rubber and the carcass ply cords and an angle formed between the reinforcing cords of the patch rubber and the tire circumferential direction represent smaller angles formed by the reinforcing cords with respect to the two relevant directions, respectively.
Yet further, in an eleventh aspect of the present invention, it is preferable that the method for repairing a radial tire further comprises setting dimension of a working area of the patch rubber to be put on a damaged portion of the radial tire from the inner side of the tire, to be 2 to 4 times as large as the damaged portion.
A radial tire can be repaired with smaller amount of rubber and in shorter time necessitated for repair, with ensuring a satisfactory reinforcing effect on a damaged portion, by setting dimension of a working area of the patch rubber provided on the inner side of the tire to be 2 to 4 times as large as the damaged portion.
Yet further, in a twelfth aspect of the present invention, it is preferable that the method for repairing a radial tire further comprises setting dimension of a working area of the patch rubber to be put on a damaged portion of the radial tire from the outer side of the tire, to be 1.1 to 1.4 times as large as the damaged portion.
A radial tire can be repaired with smaller amount of rubber and in shorter time necessitated for repair, with ensuring a satisfactory reinforcing effect on a damaged portion, by setting dimension of a working area of the patch rubber provided on the outer side of the tire to be 1.1 to 1.4 times as large as the damaged portion.
Yet further, in a thirteenth aspect of the present invention, it is preferable that the method for repairing a radial tire is further characterized in that the rubber constituting the patch rubber for repairing a radial tire is unvulcanized rubber and the patch rubber is vulcanized after completion of the aforementioned reinforcing step. Forming the patch rubber by using unvulcanized rubber is advantageous because: the patch rubber can be put on a surface of a damaged portion with satisfactory adhesion therebetween, whereby air bubbles are less likely to remain around the damaged portion; and the patch rubber can be prevented from being excessively vulcanized when the damaged portion with the patch rubber put thereon is vulcanized.
Yet further, in a fourteenth aspect of the present invention, a repaired radial tire is characterized in that the radial tire has been repaired according to the aforementioned method for repairing a radial tire. A repaired radial tire which exhibits good durability and can be used for a long period is obtained by repairing a damaged radial tire by the method for repairing a radial tire of the present invention.
The patch rubber for repairing a radial tire of the present invention significantly enhances durability of a radial tire repaired by using the same. Further, durability of a radial tire repaired by using the patch rubber is significantly improved by the method for repairing a radial tire of the present invention. Yet further, the repaired radial tire according to the present invention is a repaired radial tire which exhibits good durability and can be used for a long period.
(Radial Tire)
An embodiment of the present invention will be described in detail with reference to the drawings hereinafter.
The radial carcass ply 5 is a rubber-coated cord layers constituted of plural carcass ply cords which are disposed to be inclined at a predetermined angle (e.g. 80° to) 90° with respect to the tire circumferential direction and coated with carcass rubber. The belt ply 10 includes rubber-coated cord layers each constituted of plural belt cords which are disposed to be inclined at a predetermined angle (e.g. 0° to 40°) with respect to the tire circumferential direction and coated with belt rubber. It should be noted that the predetermined angles formed by the carcass ply cords and the belt cords with respect to the tire circumferential direction are not restricted to the aforementioned ranges, respectively.
In one example of the method for repairing a radial tire of the present invention, when the radial tire 1 was damaged by penetration of a stone, a large projection or the like therethrough and the ply cords of the radial carcass ply 5, as well as the ply rubber, broke in the sidewall portion 2 or the tread portion 3, patch rubbers are attached on damaged portions for mending as shown in
(Patch Rubber)
A patch rubber 20 as an example of the patch rubber of the present invention has a sheet-like shape and is to be attached on the damaged portion of the tread portion 3 of the radial tire 1 from the inner side and the outer side of the tire, respectively, so that the patch rubbers 20 thus applied entirely cover the damaged portion.
Specifically, as shown in
A material of the rubber for coating the reinforcing cords with is preferably the same as the rubber material constituting a damaged portion of the radial tire, on which the patch rubber 20 is to be put.
The cord-extending directions of reinforcing cords 32, 42, 52, 64 of the reinforcing cord layers 30, 40, 50, 60 are alternately changed in
In the patch rubber 20 as an example of the patch rubber of the present invention, when one reinforcing cord layer 40 has one reinforcing region 45 and another reinforcing cord layer 60, which shares the same cord-extending direction of the reinforcing cords as that of the one reinforcing cord layer 40 and is laminated on the other side in the layer-lamination direction of the one reinforcing cord layer 40, has another reinforcing region 65, the another reinforcing region 65 resides within the one reinforcing region 45. Similarly, when one reinforcing cord layer 30 has one reinforcing region 35 and another reinforcing cord layer 50, which shares the same cord-extending direction of the reinforcing cords as that of the one reinforcing cord layer 30 and is laminated on the other side in the layer-lamination direction of the one reinforcing cord layer 30, has another reinforcing region 55, the another reinforcing region 55 resides within the one reinforcing region 35.
Accordingly, it is possible to avoid positioning respective end faces (42a, 64a), relatively weakly adhered to rubber, of the reinforcing cords with relatively short interval therebetween w in the layer-lamination direction in the reinforcing cord layers 40, 60 having the same cord-extending direction of the reinforcing cords. As a result, cracks generated between the end faces of the reinforcing cords and rubber surrounding the end faces are prevented from spreading across the end faces of the reinforcing cords adjacent to each other in the layer-lamination direction, thereby successfully enhancing durability of the radial tire repaired by using the patch rubber.
In the patch rubber 20 constituted of a laminate of plural reinforcing cord layers (30, 40, 50, 60) as one example of the patch rubber of the present invention, the reinforcing cord layers 30, 50 share the same cord-extending direction of the reinforcing cords thereof and the reinforcing cord layers 40, 60 share the same cord-extending direction of the reinforcing cords thereof, as shown in
In the patch rubber 20 of the present invention as a laminate of plural reinforcing cord layers, the number of the reinforcing cord layers is not particularly limited and it suffices that reinforcing cords of at least one reinforcing cord layer are orthogonal to reinforcing cords of the rest of the reinforcing cord layers when the cord-extending directions of these reinforcing cords are to be orthogonal to each other.
Further, when the cord-extending direction of the reinforcing cords of at least one of the reinforcing cord layers (e.g. the reinforcing cord layers 40, 60) is orthogonal to the cord-extending direction of the reinforcing cords of the rest of the reinforcing cord layers (e.g. the reinforcing cord layers 30, 50), width p in the cord-juxtaposing direction of the at least one of the reinforcing cord layers (e.g. the reinforcing cord layer 40) is narrower than length s in the cord-extending direction of the outermost reinforcing cords in the cord juxtaposing direction of the rest of the reinforcing cord layers (e.g. the reinforcing cord layer 50); and width r in the cord-juxtaposing direction of the rest of the reinforcing cord layers (e.g. the reinforcing cord layer 30) is narrower than length g in the cord-extending direction of the outermost reinforcing cords in the cord-juxtaposing direction of the at least one of the reinforcing cord layers (e.g. the reinforcing cord layer 60). In short, the patch rubber has a cross-like configuration in plan view in this case.
A reinforcing effect of the patch rubber caused by a hooping effect thereof of suppressing popping-out of damaged portions due to internal pressure and rotation of the tire is enhanced and durability of the radial tire repaired by the patch rubber is further improved by designing the patch rubber such that the cord-extending direction of the reinforcing cords of at least one of the reinforcing cord layers is orthogonal to the cord-extending direction of the reinforcing cords of the rest of the reinforcing cord layers as described above.
In the patch rubber 20 for repairing a radial tire as a laminate of the reinforcing cord layers 30, 40, 50, 60, tensile modulus of elasticity of the reinforcing cords 32 of the outermost reinforcing cord layer 30 on the one side in the layer-lamination direction (i.e. the lowest reinforcing cord layer in
When a force is applied to a damaged portion of a radial tire repaired by a patch rubber, a reinforcing cord layer remote from the damaged portion generally exhibits larger elongation than a reinforcing cord layer close to the damaged portion within the same one patch rubber. In the case of the patch rubber 20 as shown in
The reinforcing cord layer using the reinforcing cords having high tensile modulus of elasticity does not need to be the outermost reinforcing cord layer in the patch rubber of the present invention. Specifically, the aforementioned reinforcing effect can be obtained and durability of the radial tire repaired by the patch rubber is improved in the example shown in
Type of a material of the reinforcing cords 32, 42, 52, 64 is not restricted as long as the resulting reinforcing cords can reinforce a damaged portion in a satisfactory manner. Examples of the reinforcing cords include in terms of cord configuration twisted cords, single filament, and plural aligned filaments. Diameter of each of the reinforcing cords 32, 42, 52, 64 is preferably smaller than diameter of each ply cord of the damaged radial carcass ply and the reinforcing cords 32, 42, 52, 64 is preferably made of a material different from a material of the ply cords of the radial carcass ply because tensile force exerted on the reinforcing cords 32, 42, 52, 64 increases to possibly facilitate occurrence of separation at end portions of the reinforcing cords 32, 42, 52, 64 in the patch rubber when the reinforcing cords 32, 42, 52, 64 are made of the same material and/or each have the same diameter as the ply cords of the radial carcass ply.
Examples of the reinforcing cord 32 having high tensile modulus of elasticity for use in the reinforcing cord layer 30 include aramid cords and glass fiber cords. Examples of the reinforcing cord 42 having low tensile modulus of elasticity for use in the reinforcing cord layer 40 include nylon cords and rayon cords.
The reinforcing cord 32 having high tensile modulus of elasticity preferably has tensile modulus of elasticity in the range of 50 GPa to 70 GPa. The reinforcing cord 42 having low tensile modulus of elasticity preferably has tensile modulus of elasticity in the range of 3.0 GPa to 7.0 GPa. “Tensile modulus of elasticity” represents the average tensile modulus of elasticity at elongation of X/3 to 2X/3 when fracture elongation is X % at the room temperature (20° C.) in the present invention.
Increase in tensile modulus of elasticity of reinforcing cords results in higher rigidity of the reinforcing cords in a patch rubber for repairing a radial tire. The reinforcing cord layer 30 therefore experiences relatively large strain when a force is exerted on a damaged portion of a radial tire repaired by the patch rubber 20. In view of this, it is preferable in the patch rubber 20 of the present invention to set thickness L2 of the reinforcing cord layer 30 using the reinforcing cords having high tensile modulus of elasticity to be larger than thickness of L1 of the reinforcing cord layer 40 using the reinforcing cords having low tensile modulus of elasticity. As a result, strains generated in the reinforcing cord layer 30 is alleviated to successfully enhance durability of the repaired radial tire 1.
The plural reinforcing cords 41, 42, 43 in the same one reinforcing cord layer include: a long reinforcing cord 41 having the longest length in the cord-extending direction among the reinforcing cords 41, 42, 43; and at least a pair of reinforcing cords 42, 43 disposed on respective sides in the cord juxtaposing direction orthogonal to the cord-extending direction, of the long reinforcing cord 41 in the patch rubber for repairing a radial tire of the present invention, as shown in
It should be noted that other reinforcing cord layers 30, 50, 60 of the patch rubber 20 each have a structure similar to that of the reinforcing cord layer 40 in this regard.
Accordingly, it is possible to prevent respective end faces, relatively weakly adhered to rubber, of the reinforcing cords from being positioned at relatively short interval therebetween in the layer-juxtaposing direction in each reinforcing cord layer in the patch rubber 20. As a result, cracks generated between the end faces of the reinforcing cords and rubber surrounding the end faces are prevented from spreading across the end faces of the reinforcing cords adjacent to each other, thereby successfully enhancing durability of the radial tire repaired by using the patch rubber.
Further, the patch rubber 20 can eliminate portions remote from a damaged portion and thus relatively irrelevant to an effect of reinforcing the damaged portion (the hatched corner portions in
(Method for Repairing a Radial Tire)
One example of a method for repairing a radial tire according to the present invention is characterized in that a damaged portion of a radial tire is repaired by using the patch rubber 20 having the reinforcing cord layers structured as described above.
In the one example of the method for repairing a radial tire of the present invention, a damaged portion generated in the tread portion 3 is repaired.
Reference number 8 indicates a portion where the radial carcass ply 5 and the belt ply 10 are fractured (i.e. a damaged portion).
According to the one example of the method for repairing a radial tire of the present invention mentioned above, tread rubber 13 and in particular the belt ply 10 in the vicinity of the damaged portion 8 (indicated by broken lines in
The vicinities of the belt ply 10 thus exposed may be subjected to finishing operation by buffing or the like to increase an adhesion (press-contact) area between the belt ply 10 and the patch rubber 20 for repairing a radial tire.
Next, inner liner rubber 12 in the vicinity of the damaged portion 8 (indicated by broken lines in
The surfaces of the radial carcass ply 5 thus exposed may be subjected to finishing operation by buffing or the like to increase an adhesion (press-contact) area between the radial carcass ply 5 and the patch rubber 20 for repairing a radial tire.
The patch rubber 20 described above is then attached on the damaged portion 8 from the respective (i.e. the outer and inner) sides of the tire. Specifically, one patch rubber 20 integrated with a new piece 12a of inner liner rubber in advance is attached on the damaged portion 8 from the inner surface side of the radial tire by, e.g. using an adhesive, and another patch rubber 20 integrated with a new piece 13a of tread rubber in advance is attached on the damaged portion 8 from the outer surface side of the radial tire by, e.g. using an adhesive.
The new piece 12a of inner liner rubber and the new piece 13a of tread rubber are preferably made of the same materials as the materials of the inner liner rubber 12 and the tread rubber 13 to be repaired, respectively, because then adhesion properties between the new piece 12a of inner liner rubber and the inner liner rubber 12 of a pneumatic tire to be repaired when they are combined, as well as adhesion properties between the new piece 13a of tread rubber and the tread rubber 13 of the pneumatic tire when they are combined, improve, whereby durability of the radial tire 1 repaired by using the patch rubber 20 enhances.
Further, rubbers 32b, 42b, 52b, 64b of the patch rubber 20 prior to being put on the damaged portion 8 are preferably unvulcanized rubber. That is, it is preferable to attach the patch rubber 20 made of unvulcanized rubber on the damaged portion 8 and then subject the damaged portion 8 with the patch rubber 20 thereon to partial vulcanization. The patch rubber 20 made of unvulcanized rubber can sufficiently firmly adhere to a surface of the damaged portion 8, thereby allowing few bubbles to remain between the patch rubber and the vicinities of the damaged portion 8. Further, the patch rubber 20, made of unvulcanized rubber, can avoid excessive vulcanization when the new piece 12a of inner liner rubber and the new piece 13a of tread rubber are subjected to vulcanization.
According to the aforementioned method for repairing a radial tire, i) the patch rubber 20 is oriented such that the reinforcing cord layer 30 thereof on the one side in the layer-lamination direction, made of the reinforcing cords 32 having high tensile modulus of elasticity, directly faces the damaged portion; ii) and the patch rubber 20 thus oriented is attached to the damaged portion such that the reinforcing cords 32 of the reinforcing cord layer 30 adjacent to the radial carcass ply 5 are in parallel to the extending-direction of the carcass ply cords 6 of the fractured radial carcass ply 5. As a result, the reinforcing cords 32 of the reinforcing cord layer 30 can exhibit the maximum support force in the carcass ply cord-extending direction when a force is exerted on the repaired portion of the radial tire, thereby enhancing the reinforcing effect of the patch rubber 20 and well suppressing shear deformation of the rubber constituting the reinforcing cord layer.
In this connection, it is acceptable that the patch rubber 20 is oriented such that the reinforcing cord layer 60 thereof on the other side in the layer-lamination direction directly faces the damaged portion; and the patch rubber 20 thus oriented is attached to the damaged portion such that the reinforcing cords 64 of the reinforcing cord layer 60 adjacent to the radial carcass ply 5 are in parallel to the extending-direction of the carcass ply cords 6 of the fractured radial carcass ply 5.
By repairing the radial tire 1 by using the patch rubber 20 structured as described above, resistance force, exhibited when the reinforcing cord layer 30 using the reinforcing cords 32 having high tensile modulus of elasticity is elongated, increases and elongation width, observed when the reinforcing cord layer 50 using the reinforcing cords 52 (not shown in
According to the one example of the method for repairing a radial tire of the present invention described above, the patch rubber 20 is attached to the damaged portion 8 as shown in
A “damaged portion 8” represents a gap portion generated as a result of fracture of the carcass ply cord and carcass rubber of the radial carcass ply 5. Specifically, a damaged portion 8 is defined, in a perspective plan view of the radial carcass ply 5 viewed from the tire surface shown in
A working area of the patch rubber 20 is defined as a region where the reinforcing region 35 of the reinforcing cord layer 30 on the one end side in the layer-lamination direction as the reinforcing cord layer closest to the damage portion overlaps the reinforcing region 45 of the reinforcing cord layer 40 adjacent to the reinforcing cord layer 30 on the other end side in the layer-lamination direction. Dimensions in the carcass ply cord-extending direction and the tire circumferential direction of the working area may be set by multiplying dimensions in the carcass ply cord-extending direction and the tire circumferential direction of the damaged portion by predetermined times, respectively.
Dimensions of the working area of the patch rubber 20 to be attached to a damaged portion 8 from the inner surface side of the tire are preferably 2 to 4 times as large as dimensions of the damaged portion 8 in the carcass ply cord-extending direction of the radial carcass ply and the tire circumferential direction, respectively. The damaged portion can be sufficiently reinforced and thus repaired in a satisfactory manner by setting dimensions of the working area of the patch rubber 20 attached from the tire inner surface side to be at least two times as large as those of the damaged portion 8. Attaching the patch rubber to portions not necessitating it can be avoided by setting dimensions of the working area of the patch rubber 20 attached from the tire inner surface side to be four times or less as large as those of the damaged portion 8. That is, it is possible to reliably reinforce the damaged portion 8 of a radial tire, while reducing an amount of rubber and operation time required for repairing the radial tire to achieve efficient repair at low cost, by setting dimensions of a working area of the patch rubber 20 on the tire inner surface side to be 2 to 4 times as large as those of the damaged portion 8. Dimensions of the working area of the patch rubber 20 to be attached to a damaged portion 8 from the outer surface side of the tire are preferably 1.1 to 1.4 times as large as dimensions of the damaged portion 8. The damaged portion can be sufficiently reinforced and thus repaired in a satisfactory manner by setting dimensions of a working area of the patch rubber 20 attached from the tire outer surface side to be at least 1.1 times as large as those of the damaged portion 8. Attaching the patch rubber to portions not necessitating it can be avoided by setting dimensions of a working area of the patch rubber 20 on the tire outer surface side to be 1.4 times or less as large as those of the damaged portion 8. That is, it is possible to reliably reinforce the damaged portion 8 of a radial tire, while reducing an amount of rubber and operation time required for repairing the radial tire to achieve efficient repair at low cost, by setting dimensions of a working area of the patch rubber 20 attached from the tire outer surface side to be 1.1 to 1.4 times as large as those of the damaged portion 8.
In the one example of the method for repairing a radial tire damaged by penetration at the tread portion 3 of the present invention described above, the patch rubber may be attached from only one of the tire outer surface side and the tire inner surface side. When the patch rubber is put on a damaged portion for mending from only one of the outer surfaces and the inner surface of the tire, rubber on the opposite side of the patch rubber with respect to the radial carcass ply 5 (the inner liner rubber 12a in a case where the repair is done from the tire outer surface side, while the tread rubber 13a in a case where the repair is done from the tire inner surface side) is to be charged at the damaged portion prior to attaching the patch rubber 20 thereto, followed by the attachment of the patch rubber 20 as described above.
Further, the method for repairing a radial tire of the present invention is also applicable to a case where a damage at the tread portion 3 has not reached the radial carcass ply 5 and exists only in the belt ply 10. In this case, the damage can be repaired by removing the tread rubber 13 and in particular the broken belt ply 10 in the vicinities of the damaged portion 8 from the tire outer surface side and then attaching the patch rubber 20 as described above from the tire outer surface side.
Yet further, in yet another example of the method for repairing a radial tire of the present invention, a damage generated in the sidewall portion of a radial tire can be repaired by the repairing processes similar to those in the case of repairing a damage generated in the tread portion of the tire.
A portion where the radial carcass ply 5 has been fractured (i.e. a damaged portion) is indicated by reference number 8′ in
According to the another example of the method for repairing a radial tire of the present invention, sidewall rubber 11 in the vicinity of the damaged portion 8′ (indicated by broken lines in
The patch rubber 20 described above is then attached to the damaged portion 8′ from the respective (i.e. the outer and inner) sides of the tire. Specifically, one patch rubber 20 integrated with a new piece 12a of inner liner rubber in advance is attached on the damaged portion 8 from the inner surface side of the radial tire by, e.g. using an adhesive, and another patch rubber 20 integrated with a new piece 11a of side rubber in advance is attached on the damaged portion 8′ from the outer surface side of the radial tire by, e.g. using an adhesive.
The new piece 12a of inner liner rubber and the new piece 11a of sidewall rubber are preferably made of the same materials as the materials of the inner liner rubber 12 and the sidewall rubber 11 to be repaired, respectively.
Further, rubbers 32b, 42b, 52b, 64b of the patch rubber 20 prior to being put on the damaged portion 8′ are preferably unvulcanized rubber. That is, it is preferable to attach the patch rubber 20 made of unvulcanized rubber on the damaged portion 8′ and then subject the damaged portion 8′ with the patch rubber 20 thereon to partial vulcanization. The patch rubber 20 made of unvulcanized rubber can sufficiently firmly adhere to a surface of the damaged portion 8′, thereby allowing few bubbles to remain between the patch rubber and the vicinities of the damaged portion 8′. Further, the patch rubber 20, made of unvulcanized rubber, can avoid excessive vulcanization when the new piece 12a of inner liner rubber and the new piece 11a of sidewall rubber are subjected to vulcanization.
According to aforementioned another example of the method for repairing a radial tire of the present invention, the patch rubber 20 is attached to the damaged portion 8′ as shown in
By repairing the radial tire 1 by using the patch rubber 20 structured as described above, resistance force, exhibited when the reinforcing cord layer 30 using the reinforcing cords 32 having high tensile modulus of elasticity is elongated, increases and elongation width, observed when the reinforcing cord layer 50 using the reinforcing cords 52 (not shown in
According to the another example of the method for repairing a radial tire of the present invention described above, the patch rubber 20 is attached to the damaged portion 8′ such that the reinforcing cords, of the reinforcing cord layer 30 using reinforcing cords 32 having high tensile modulus of elasticity and laminated on the one side in the layer-lamination direction, are in parallel to the direction of the intermediate line C1. The present invention, however, is not restricted to this example. More specifically, according to yet another preferable example of the method for repairing a radial tire of the present invention, the cord-extending direction of the carcass ply cords 6′ of the radial carcass ply intersects the reinforcing cords of the reinforcing cord layer 30 attached to the damaged portion of the sidewall portion 2, of the patch rubber 30, at intersection angle θ3 (0°<θ1≦30°) in the sidewall portion 2 as shown in
It is preferable in the aforementioned examples of the method for repairing a radial tire of the present invention to set dimension of a working area of the patch rubber 20 to be put on the damaged portion 8′ to be 2 to 4 times as large as the damaged portion in a case where the patch rubber is to be attached form the tire inner surface side and 1.1 to 1.4 times as large as the damaged portion in a case where the patch rubber is to be attached form the tire outer surface side.
A damaged portion 8′ represents a gap portion generated as a result of fracture of the carcass ply cord and carcass ply rubber of the radial carcass ply 5, as shown in
The damaged portion can be sufficiently reinforced and thus repaired in a satisfactory manner by setting dimensions of the working area of the patch rubber 20 attached from the tire inner surface side to be at least two times as large as those of the damaged portion 8′; and attaching the patch rubber to portions not necessitating it can be avoided by setting dimensions of the working area of the patch rubber 20 attached from the tire inner surface side to be four times or less as large as those of the damaged portion 8′, as described above. Further, the damaged portion can be sufficiently reinforced and thus repaired in a satisfactory manner by setting dimensions of the working area of the patch rubber 20 attached from the tire outer surface side to be at least 1.1 times as large as those of the damaged portion 8′; and attaching the patch rubber to portions not necessitating it can be avoided by setting dimensions of the working area of the patch rubber 20 attached from the tire outer surface side to be 1.4 times or less as large as those of the damaged portion 8′, as described above. That is, it is possible to reliably reinforce the damaged portion 8′ of a radial tire, while reducing an amount of rubber and operation time required for repairing the radial tire to achieve efficient repair at low cost, by setting dimensions of a working area of the patch rubber 20 attached from the tire inner/outer surface side as described above.
In yet another example of the method for repairing a radial tire of the present invention described above, the patch rubber may be attached from only one of the tire outer surface side and the tire inner surface side. When the patch rubber is put on a damaged portion for mending from only one of the outer surfaces and the inner surface of the radial tire 1, rubber on the opposite side of the patch rubber with respect to the radial carcass ply 5 (the inner liner rubber 12a in a case where the repair is done from the tire outer surface side, while the sidewall rubber 11a in a case where the repair is done from the tire inner surface side) is to be charged at the damaged portion prior to attaching the patch rubber 20 thereto, followed by the attachment of the patch rubber 20 as described above.
According to aforementioned another example of the method for repairing a radial tire of the present invention, the patch rubber 20 is attached to the damaged portion 8′ as shown in
In the method for repairing a radial tire of the present invention, the patch rubber may be attached from only one of the tire outer surface side and the tire inner surface side as described above. When the patch rubber is put on a damaged portion for mending from only one of the outer surfaces and the inner surface of the tire, rubber on the opposite side of the patch rubber with respect to the radial carcass ply 5 (the inner liner rubber 12a in a case where the repair is done from the tire outer surface side, while the tread rubber 13a/the sidewall rubber 11a in a case where the repair is done from the tire inner surface side) is to be charged at the damaged portion prior to attaching the patch rubber 20 thereto, followed by the attachment of the patch rubber 20 as described above.
The method for repairing a radial tire of the present invention is applicable to any radial tire. The method for repairing a radial tire of the present invention is especially effective when it is applied to a super large-size radial tire such as a tire for a construction vehicle, which is not only expensive but susceptible to severe damages at a sidewall portion and/or a tread portion thereof.
A radial tire of which sidewall portion 2 and tread portion 3 have been repaired by the aforementioned method for repairing a radial tire is shown in
The present invention will be described further in detail by Examples hereinafter. The present invention is not restricted to these Examples by any means.
An off-the-road radial tire (ORR 46/90R57) as a test tire was assembled with an application rim prescribed in the JATMA standards and run at the speed of 8 km/hour for 1000 hours under the conditions of internal pressure: 700 kPa and load: 63 t. Then, a damage (length in the tire circumferential direction b=25 mm×length in the carcass ply cord-extending direction of radial carcass ply d=25 mm) was made in a tread portion of the tire, such that carcass ply cords of a radial carcass ply and belt cords of a belt ply were fractured. A patch rubber having characteristics shown in Table 1 and reinforcing regions decreasing on the other end side in the layer-lamination direction was prepared and attached on the damaged portion from the tire inner surface side for mending.
Durability of the test tire thus repaired was evaluated by the following method. The evaluation results, together with corresponding amount of rubber required for preparation of the patch rubber and time required for repair, are shown in Table 1.
(Evaluation of Durability of the Repaired Radial Tire)
The repaired test tire was assembled with an application rim prescribed in the JATMA standards, run at the speed of 8 km/hour for 3000 hours under the conditions of internal pressure: 700 kPa and load: 63 t and the running time prior to the tire experiencing troubles was measured. The longer running time indicates the higher durability of the patch rubber.
A patch rubber of Comparative Example 1 was prepared in the same manner as in Example 1, except that the positions of respective cord ends of reinforcing cords were aligned on straight lines in the cord-juxtaposing direction in each reinforcing cord layer as shown in
Off-the-road radial tires as test tires of Example 2 and Comparative Examples 1 to 6 were repaired in the same manner as in Example 1, except that patch rubbers having characteristics shown in Table 1 were used, respectively, in the former. Durability of each of the respective repaired tires was evaluated in the same manner as in Example 1.
An off-the-road radial tire (ORR 46/90R57) as a test tire was assembled with an application rim prescribed in the JATMA standards and run at the speed of 12 km/hour for 4000 hours under the conditions of internal pressure: 700 kPa (102 psi) and load: 62 t. Then, a damage (length thereof in the tire circumferential direction a on the radially outer side in the ply cord-extending direction=25 mm, length thereof in the tire circumferential direction b on the radially inner side in the ply cord-extending direction=23 mm, length thereof c in the ply cord-extending direction=100 mm) was made in a sidewall portion of the radial tire, such that four carcass ply cords of a radial carcass ply were fractured. A patch rubber having characteristics shown in Table 2a and Table 2b and an outermost reinforcing cord layer in the layer-lamination direction, using aramid cords, was prepared and attached on the damaged portion from the tire inner surface side such that the outermost reinforcing cord layer faced the damaged portion, for mending. Durability of the radial test tire thus repaired was evaluated by the following method. The evaluation results are shown in Table 2a and Table 2b.
(Evaluation of Durability of the Repaired Radial Tire)
The test tire thus repaired was assembled with an application rim prescribed in the JATMA standards, run at the speed of 12 km/hour for 4000 hours under the conditions of internal pressure: 700 kPa and load: 62 t and the running time prior to the tire experiencing troubles was measured. The longer running time indicates the higher durability of the patch rubber.
A patch rubber of Reference Comparative Example 1 was prepared in the same manner as in Example 1, except that the reinforcing cords of the reinforcing cord layers were unanimously made of nylon in the former. An off-the-road radial tire as a test tire was repaired by using the patch rubber thus prepared and durability of the repaired tire was evaluated in the same manner as in Example 1.
Off-the-road radial tires as test tires of Reference Examples 2 to 8 were repaired in the same manner as in Example 1, except that patch rubbers having characteristics shown in Table 2a and Table 2b were used, respectively, in the test tires of the former. Durability of each of the respective repaired tires was evaluated in the same manner as in Example 1.
The patch rubber for repairing a radial tire of the present invention can significantly enhance durability of a radial tire repaired by using the same. Further, durability of a radial tire repaired by using the patch rubber is significantly improved by the method for repairing a radial tire of the present invention. Yet further, the repaired radial tire according to the present invention is a repaired radial tire which exhibits good durability and can be used for a long period after repair.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-032304 | Feb 2011 | JP | national |
| 2011-032322 | Feb 2011 | JP | national |
This is a National Stage of International Application No. PCT/JP2012/001079 filed Feb. 17, 2012, claiming priority based on Japanese Patent Application Nos. 2011-032304 filed Feb. 17, 2011 and 2011-032322 filed Feb. 17, 2011, the contents of all of which are incorporated herein by reference in their entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/001079 | 2/17/2012 | WO | 00 | 7/17/2013 |
