JP2011051451A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire having a belt reinforced by a metal reinforcing body, without thickening both side parts of a belt ply and providing cutting ends in both side parts of the belt ply. <P>SOLUTION: This belt 4 is constituted by laminating one or more layers of belt plies 5, each of which is composed of the reinforcing body 6 and coating rubber 7 coating the reinforcing body 6. The reinforcing body 6 is formed by inclining and arranging one or more bundles of metal wire surface bundles 11 arrayed by arranging a plurality of untwisted metal wires 8 in plane in a peripheral direction, and folding back the metal wire surface bundles 11 by being reversed in belt ply side parts 12 on both sides. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which a belt is disposed between a carcass extending in a toroidal shape between both bead cores and a tread, and particularly to a tire capable of preventing a decrease in durability due to belt end separation. .

  In a pneumatic tire in which a belt is disposed between a tread and a carcass extending in a toroidal shape between both bead cores, conventionally, the belt is formed by laminating one or more belt plies. The metal stranded wire cords covered with rubber are arranged at a small angle with respect to the tire circumferential direction.

  However, since such a belt ply is formed by arranging metal stranded cords cut at both ends, both ends cut by repeated input accompanying the running of the tire pierce the surrounding rubber part. There was a problem that the rubber and the metal cord peeled off as a nucleus of destruction, and developed into belt end separation. For this reason, an annular belt ply (for example, refer to Patent Documents 1 and 2) made of a metal stranded wire cord having no cut ends on both sides of the belt ply, or a metal stranded wire cord radially outward at both ends of the belt. It has been proposed to use a folded belt ply (see, for example, Patent Document 3).

JP 2006-069283 A JP 2004-001611 A JP 02-141306 A

  However, in the proposed annular belt and fold belt, the cord is a stranded wire, and therefore the radius of curvature of the folded portion of the cord increases, and the cord rises in the thickness direction of the belt ply. The side part of the belt ply becomes thick. This is not only because the folded portion itself causes an increase in the belt mass, but also because a gap in the thickness direction due to folding occurs on the side of the belt ply and the gap needs to be filled with a new member such as rubber. This causes the problem of increasing weight.

  The present invention has been made in view of such a problem, and is reinforced with a metal reinforcing body that does not thicken both sides of the belt ply and does not have cut ends on both sides of the belt ply. An object is to provide a pneumatic tire having a belt.

<1> is a pneumatic tire in which a belt is disposed between a tread and a carcass extending in a toroidal shape between both bead cores.
The belt is composed of at least one layer of a belt ply made of a reinforcing body and a covering rubber covering the reinforcing body, and the reinforcing body in the belt ply of at least one layer is formed by aligning a plurality of untwisted metal wires in a plane. A pneumatic tire characterized in that one or more of the arrayed metal wire surface bundles are inclined with respect to the circumferential direction, and the metal wire surface bodies are formed by being turned upside down on both sides of the belt ply. is there.

  <2> In <1>, the belt ply having the metal wire surface bundle has an endless loop shape in a cross section passing through the tire central axis, and the metal wire bundle is continuous for one turn in the tire circumferential direction. This is a pneumatic tire.

  <3> in <1>, the belt ply having the metal wire surface bundle has a C-shaped end shape in which both side portions in the tire width direction are folded back radially outward in a cross section passing through the tire central axis, The metal wire bundle is a pneumatic tire characterized by extending from one folded end to the other end.

  <4> is a pneumatic tire characterized in that, in any one of <1> to <3>, the inclination angle of the metal linear body with respect to the circumferential direction is small at the center in the tire width direction and large at both sides. is there.

  According to <1>, the reinforcing body constituting the belt ply is formed by folding back untwisted metal wires at both sides of the belt ply, so that both sides of the belt ply are not thickened, and the belt There is no cut edge on both sides of the ply. Moreover, since the untwisted metal wires are folded back by turning the front and back sides of both sides of the belt ply as a bundle of metal wires arranged in a plane and arranged in a plane, the strength can be increased.

  <2> According to <2>, since the belt ply having the metal wire surface bundle has an endless loop shape in a cross section passing through the tire central axis, one belt ply can cover two layers of cross belt plies. They can be formed together.

  According to <3>, the belt ply having the metal wire surface bundle has a so-called fold shape in which a cross section passing through the tire central axis has a C-shaped shape with both ends in the tire width direction folded back radially outward. Because it is a belt ply, when forming a fold belt ply, the belt does not expose the cut end of the metal stranded wire at the belt end by folding the belt ply made of a conventional metal stranded cord so as to wrap both ends of the belt ply. In this case, the belt can be easily manufactured.

  <4> According to <4>, since the inclination angle with respect to the circumferential direction of the metal linear body is increased on both sides, if this inclination angle is reduced as in the center in the tire width direction, the aligned metal It is possible to prevent the distortion between the line surfaces from increasing and the durability from decreasing.

1 is a cross-sectional view in the width direction of a pneumatic tire according to a first embodiment of the present invention. It is the perspective view and sectional drawing which show the belt ply of the pneumatic tire of 1st Embodiment. It is a perspective view which shows typically the arrangement | sequence aspect of the reinforcing material of the belt ply of the pneumatic tire of 1st Embodiment. It is sectional drawing and an expanded view which show the belt ply of the pneumatic tire of 1st Embodiment. 3 is a cross-sectional view of a belt ply of a pneumatic tire of Comparative Example 1. FIG. 6 is a cross-sectional view of a belt ply of a pneumatic tire of Comparative Example 2. FIG.

  A pneumatic tire according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view in the width direction of the pneumatic tire according to the present embodiment. In the pneumatic tire 10, a belt 4 is disposed between a carcass 2 extending in a toroidal shape between both bead cores 1 and a tread 3. Configured. The belt 4 is configured by laminating one or more belt plies 5.

  2 (a) is a perspective view showing one belt ply 5 constituting the belt 4, FIG. 2 (b) is a cross-sectional view of a part cut out in the width direction, and the belt ply 5 is The reinforcing member 6 and the covering rubber 7 covering the reinforcing member 6 are used. FIG. 3 is a perspective view schematically showing an arrangement mode of the reinforcing body 6 of the belt ply 5. The reinforcing body 6 is characterized by a metal in which a plurality of untwisted metal wires 8 are arranged in a plane and aligned. One or more bundles of the linear sheet bundles 11 are inclined with respect to the circumferential direction, and the metal linear sheet bodies 11 are continuously formed in the circumferential direction by being turned upside down at the belt ply side portions 12 on both sides and turned up. Has been.

  The belt ply 5 as a whole is formed in a shape in which two layers connected at both ends extend in a ring shape, so-called a tube is crushed in the radial direction, and the inclination angle of the untwisted metal wire 8 with respect to the equator plane is The outer and inner sides of the two layers are inclined in the opposite direction at the same angle. In FIG. 2, G1 represents the total thickness of the belt ply 5, G2 represents the gap distance between the two layers of the metal linear planar bodies 11 constituting the belt ply 5, and G3 represents the same in-plane Represents a gap distance between adjacent metal linear planar bodies 11.

  Note that the covering rubber 7 must completely cover the untwisted metal wire 8 constituting the metal wire planar body 11 that becomes the reinforcing body 6, and if not, the untwisted metal wire 8. There is a possibility that the adhesion between the rubber and the rubber is lowered or the surface is corroded.

  Thus, since the reinforcement body 6 consists of the untwisted metal wire 8, when this is folded in the belt side part one by one, it can be folded without making the belt side part thick. In practice, these untwisted metal wires 8 are arranged in such a manner that a plurality of these untwisted metal wires 8 are arranged in a plane in order to increase the belt rigidity and ensure the desired movement performance and durability. Is folded at the belt ply side portions 12 on both sides, but since the folding is folded in the direction of reversing the front and back, the untwisted metal wires 8 are individually reversed. There is not much difference from the folded back, and thus the untwisted metal wires 8 are combined into a metal wire surface bundle 11 to prevent the belt side portion from becoming thick by folding it back and forth. can do.

  If the metal wire planar bundle 11 is folded in the same plane including the surface, the untwisted metal wire 8 folded on the inner side and the untwisted metal wire 8 folded on the outer side are generated, resulting in a large distortion. End up.

The inclination angle of the untwisted metal wire 8 with respect to the tire equator plane (that is, the inclination angle with respect to the tire circumferential direction) is preferably small at the center in the width direction and large at the belt side. That is, the inclination angle of the untwisted metal wire 8 with respect to the tire equatorial plane is basically the normal angle θ ₁ required from tire durability and exercise performance, which affects the tire durability and exercise performance. It is preferable that only the side portion of the belt having a small amount has an inclination angle θ ₂ larger than that of the central portion, and this makes it possible to reduce distortion at the time of folding back with the untwisted metal wire 8.

  Here, it is preferable that the number of untwisted metal wires 8 constituting one bundle of metal wire planar bundles 11 is 2 to 7. If the width of the belt ply 5 and the total number of untwisted metal wires 8 included in the belt ply 5 are constant, the strength is better when the number of untwisted metal wires 8 constituting one bundle is increased and the number of bundles is decreased. However, if the number of bundles is reduced, the width of the rubber-only portion between the bundles becomes wider. If the number of untwisted metal wires 8 is more than 8, nail etc. However, there is a risk of passing through the belt ply 5 through only the rubber part.

  Here, the wire diameter of the untwisted metal wire 8 is preferably 0.18 to 0.35 mm. When the wire diameter is less than 0.18 mm, many untwisted metal wires 8 are used to maintain the strength of the entire belt. Must be arranged in the belt ply, in this case, the separation distance between the adjacent untwisted metal wires 8 is narrowed, and the anti-peeling performance with the covering rubber 7 is liable to deteriorate, When the thickness exceeds 0.35 mm, the bending rigidity is increased, the radius of curvature when bending is increased, the belt ply side portion becomes thick, and a gap may be generated in the bent portion.

  The tensile strength of the untwisted metal wire 8 is preferably 3130 to 4410 MPa, and when this is less than 3130 MPa, the untwisted metal wire 8 is thickened or the number of wires is increased in order to ensure belt strength. If the weight of the untwisted metal wire 8 needs to be increased and the weight of the belt exceeds the preferred range and the weight reduction of the tire is inhibited, on the other hand, if it exceeds 4410 MPa, the untwisted metal wire 8 would be difficult to manufacture.

  The total thickness G1 of the belt ply 5 (refer to FIG. 2) is preferably 1.00 to 2.00 mm. When this is less than 1.00 mm, the treat in which the metal linear sheet bundle 11 is covered with the covering rubber 7. And the belt ply 5 is difficult to be applied in the tire molding process. On the other hand, if it exceeds 2.00 mm, the belt ply 5 becomes too thick and the weight of the belt is preferable. Exceeding the range will impede weight reduction of the tire.

  The gap distance G2 (see FIG. 2) between the two metal linear sheet bodies 11 constituting the belt ply 5 is preferably 0.32 to 0.65 mm, and when this is less than 0.32 mm, The belt tends to be deformed due to external input from the tire tread and the durability is reduced. On the other hand, if it exceeds 0.65 mm, the weight of the belt exceeds the preferred range and the tire is light. It will inhibit the conversion.

  The gap distance G3 (see FIG. 2) between the adjacent metal linear planar bodies 11 in the same plane is preferably 0.25 to 1.00 mm. If this is less than 0.25 m, the belt ply 5 is deformed. In this case, since the shear strain of the rubber portion in the gap between the metal linear bodies 11 becomes large, it becomes difficult to suppress the occurrence of peeling from the rubber at the belt ply side end and its growth, If this exceeds 1.00 mm, the gap distance between the metal wire-like bodies 11 becomes too large, causing not only a reduction in belt rigidity, but also resistance to penetration when stepping on nails, etc. The characteristics will deteriorate.

  FIG. 4 is a sectional view and a developed view showing a belt of a pneumatic tire according to a second embodiment of the present invention, and FIG. 4 (a) is a sectional view in a section passing through the tire central axis. 4B is a development view of the belt as viewed from the outside in the radial direction. The belt 25 includes a second belt ply 27 that constitutes a radially outer layer, and both end portions of the second belt ply 27. FIG. The first belt ply 26 is formed by folding both side portions 31 outward in the radial direction so as to wrap the wire, and the second belt ply 27 aligns the metal stranded wire cord or the plurality of untwisted metal wires 8 in a plane. The metal wire planar bundles 11 arranged in an inclined manner with respect to the equator plane are configured.

  As with the belt ply 6 of the first embodiment, the first belt ply 26 is formed by arranging one or more bundles of metal wire planar bundles 11 in which a plurality of untwisted metal wires 8 are arranged in a plane in the circumferential direction. The reinforcing body arranged in an inclined manner is covered with rubber. The metal linear sheet bundle 11 is different from the belt ply 6 of the first embodiment in that it terminates at the ends of both side portions 31, but is turned upside down at the belt ply side portions 32 on both sides. As in the first embodiment, it is possible to prevent the belt side portion from becoming thick.

  Here, also in the second embodiment, the inclination angle of the untwisted metal wire 8 with respect to the tire equatorial plane is small at the center in the width direction and large at the belt side portion, so that one bundle of metal wire planar bundles 11 is configured. The number of untwisted metal wires 8 is 2 to 7, the diameter of the untwisted metal wire 8 is 0.18 to 0.35 mm, the tensile strength of the untwisted metal wire 8 is 3130 to 4410 MPa, As described in the first embodiment, it is preferable that the gap distance G3 between adjacent metal wire planar bodies 11 in the same plane is 0.25 to 1.00 mm.

  A tire comprising a belt using one of the belt ply 5 according to the first embodiment (one belt ply is formed by laminating two layers of metal linear surface bodies) is used as an example, and a metal is used as a reinforcing body. A tire using a stranded wire cord instead of a linear body is referred to as Comparative Examples 1 and 2, and one of the belt plies in which the stranded wire cord is folded at the belt ply side end (one belt ply has two layers) A tire having a belt using a metal linear sheet is laminated in Comparative Example 2, and a belt ply in which stranded wires having cut ends at both ends are arranged in the circumferential direction is used. Tires in which two layers are stacked so as to be opposite to the equator plane are used as Comparative Example 1, and these tires are prototyped. The mass of the belt portion, the rolling resistance as the tire, and the belt end peeling resistance Sex (ie They were evaluated for peel resistance) with respect to the rubber in the preparative side end. Table 1 shows the belt specifications and evaluation results of each tire. G1 represents the total thickness of the belt ply, G2 represents the gap distance between the two layers of stranded wire cords 93 constituting the belt ply, and G3 represents the distance between adjacent stranded wire cords in the same plane. Represents the gap distance.

  5A is a perspective view showing the belt of Comparative Example 1, FIG. 5B is a cross-sectional view of a part cut out in the width direction, and FIG. 6A is a comparison. It is a perspective view which shows the belt of Example 2, FIG.6 (b) is sectional drawing of the part which cut out the one part in the width direction. 5 and 6, 92 represents a coated rubber, 93 represents a stranded wire cord, and 94 represents a metal wire constituting the stranded wire cord. Further, reference numerals 91a and 91b in FIG. 6 represent belt plies in which the cut ends of the cords are exposed on the side portions, and 90 in FIG. 5 represents an annular belt ply.

  In Table 1, the mass of the belt portion was obtained by dissecting the tire, cutting out only the belt portion, measuring the mass, and expressing the result as an index with Comparative Example 1 being 100. The larger the value, the greater the mass. The rolling resistance was measured according to ISO28580. The results were similarly expressed as an index with Comparative Example 1 as 100. The higher the value, the greater the rolling resistance. In addition, the belt edge peeling resistance is determined by attaching the tire to a regular rim, filling it with air pressure of 150 kPa and mounting it on a test passenger car. The length of cracks occurring in the film was measured and evaluated. The results were expressed as an index with Comparative Example 1 as 100. The larger the value, the longer the crack.

DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass 3 Tread 4 Belt 5 Belt ply 6 Reinforcement body 7 Cover rubber 8 Untwisted metal wire 10 Pneumatic tire 11 Metal wire planar bundle 12 Belt ply side part 26 1st belt ply 27 2nd belt ply 31 1st Both sides of belt ply 32 First belt ply turn-up part

Claims (4)

In a pneumatic tire in which a belt is disposed between a tread and a carcass extending in a toroidal shape between both bead cores,
The belt is composed of at least one layer of a belt ply made of a reinforcing body and a covering rubber that covers the reinforcing body, and the reinforcing body in the belt ply of at least one layer has a plurality of untwisted metal wires in a plane. One or more bundles of metal linear sheet bundles arranged in an aligned manner are inclined with respect to the circumferential direction, and the metal linear sheet is turned upside down on both sides of the belt ply and folded back. Enter tire.   The belt ply having the metal wire surface bundle has an endless loop shape in a cross section passing through the tire central axis, and the metal wire bundle is continuous for one turn in the tire circumferential direction. Pneumatic tire described in 2.   The belt ply having the metal wire surface bundle has a C-shaped shape with both ends of the tire width direction folded outward in the radial direction in a cross section passing through the tire central axis, and the metal wire bundle is folded back on one side. The pneumatic tire according to claim 1, wherein the pneumatic tire extends from one end to the other end.   The pneumatic tire according to any one of claims 1 to 3, wherein an inclination angle of the metal linear body with respect to the circumferential direction is small in the tire width direction and large at both side portions.

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