JP2010064688A - Pneumatic radial tire for heavy load - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for heavy load enhancing tire durability by strengthening protection function of a carcass layer by improving compression fatigue property of a chafer reinforcement layer by suppressing fretting abrasion generated between a steel cord body and a wrapping filament in a steel cord used for the chafer reinforcement layer. <P>SOLUTION: The steel cord 4S constituting the chafer reinforcement layer 4 is constituted by the steel cord body comprising a plurality of steel filaments 4a, 4b and the wrapping filament 4z helically wound on the periphery. The lapping filament 4z is constituted by a brass element wire. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heavy-duty pneumatic radial tire. More specifically, the present invention relates to a carcass layer protection function required for a chafer reinforcement layer by suppressing wear in the chafer reinforcement layer disposed around the winding portion of the carcass layer. The present invention relates to a heavy-duty pneumatic radial tire that enhances tire durability by strengthening.

  In general, a chafer reinforcement layer made of a steel cord is arranged around a bead in a pneumatic radial tire used for heavy duty vehicles such as trucks and buses for the purpose of protecting the carcass layer (for example, Patent Document 1). And in the case of heavy-duty pneumatic radial tires with particularly heavy loads, the steel cords that make up the chafer reinforcement layer are wrapped around the steel cord body so that they do not break due to compressive stress and break due to fatigue. Measures have been taken to increase the binding property of the steel cord by winding the steel filament in a spiral (for example, see Patent Document 2).

However, in this type of steel cord, at the point contact portion between the filament constituting the steel cord main body and the steel filament for wrapping, the steel cord is easily damaged due to fretting wear caused by repeated friction. As a result, there is a problem that the protection function for the original carcass layer is lowered.
JP 2000-168309 A JP 2004-68213 A

  An object of the present invention is to solve the above-mentioned conventional problems, and suppresses fretting wear occurring between a steel cord body and a wrapping filament in a steel cord used for a chafer reinforcement layer, thereby reducing the chafer. An object is to provide a heavy-duty pneumatic radial tire that improves the tire durability by enhancing the protective function of the carcass layer by improving the compression fatigue property of the reinforcing layer.

  The heavy-duty pneumatic radial tire of the present invention that achieves the above object rolls up a carcass layer around the bead core embedded in the pair of left and right bead portions from the inside to the outside of the tire, and the winding portion of the carcass layer In a heavy duty pneumatic radial tire with a chafer reinforcement layer made of steel cord around it, the steel cord that constitutes the chafer reinforcement layer is spirally wound around the steel cord body consisting of multiple steel filaments and the surrounding area. The wrapping filament is made of brass wire, and the wrapping filament is made of brass wire.

  Moreover, in the structure mentioned above, it is preferable to comprise as described in (1)-(6) below.

(1) The winding direction of the wrapping filament is opposite to the twisting direction of the outermost layer of the steel cord body.
(2) The strand diameter of the wrapping filament is 0.20 to 0.40 mm.
(3) The winding interval of the wrapping filament is set to 4 mm or less. In this case, the winding interval of the wrapping filament is preferably 2 mm or more.
(4) The brass wire is composed of an alloy of 60 to 70% by weight of copper and 30 to 40% by weight of zinc.
(5) Brass plating is applied to the surface of the steel filament in the steel cord body.
(6) The twist structure of the steel cord body was selected from 3 + 9, 3/9, 3 + 8, 3 + 7, 1 + 18, 1 × 27, 1 × 9, 3 + 9 + 15, 3 + 8 + 13, 3/8 + 13, 4 + 9 + 14, 7 × (3 + 9 + 15) Either.

  According to the present invention, the steel cord main body composed of a plurality of steel filaments and the wrapping filament wound spirally around the steel cord constituting the chafer reinforcement layer disposed around the winding portion of the carcass layer. In addition, since the wrapping filament is made of a soft brass wire compared to the steel filament, the wrapping filament can be used early even if repeated friction occurs between the steel filament of the steel cord body and the wrapping filament. As a result, the wear of the steel filament in the steel cord body is suppressed, so that the compression fatigue resistance as a chafer reinforcement layer is secured, and the carcass layer protection function originally required for the chafer reinforcement layer is ensured. Can be strengthened Now, it is possible to improve the tire durability.

  In addition, as the wear of the brass wire progresses, the steel cord body and the wrapping filament are in surface contact with each other, so the progress of the wear of the brass wire is gradually suppressed and the carcass layer is protected over a long period of time. It becomes possible to strengthen the function.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a half cross-sectional view showing an example of a heavy-duty pneumatic radial tire according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an example of a steel cord constituting a chafer reinforcement layer in the tire of FIG. .

  In FIG. 1, a heavy-duty pneumatic radial tire 1 according to the present invention has a carcass layer 3 wound around a bead core 5 and 5 embedded in a pair of left and right bead portions 2 and 2 from the tire inner side toward the outer side. Chafer reinforcement layers 4 and 4 made of steel cords are disposed around the winding portion of the carcass layer 3 in the portions 2 and 2.

  In the heavy-duty pneumatic radial tire 1 of the present invention, the steel cord constituting the chafer reinforcement layer 4 is spirally wound around a steel cord main body composed of a plurality of steel filaments and the periphery thereof as described below. The wrapping filament is made of a brass wire. In the figure, reference numeral 6 denotes a belt layer.

  FIG. 2 is a cross-sectional view showing an example of a steel cord constituting the chafer reinforcing layer 4. In this embodiment, the steel cord 4S has a core 4A composed of three steel filaments 4a and nine wires arranged on the outer peripheral side. The steel cord body is composed of a sheath 4B composed of a steel filament 4b, and the wrapping filament 4z is composed of a single brass wire wound spirally around the steel cord body.

  In this way, by wrapping the wrapping filament 4z made of a brass wire softer than the steel filament 4b around the steel cord body, even if friction is repeatedly generated between the steel filament 4b and the wrapping filament 4z, Since the wrapping filament 4z is worn out at an early stage, the wear of the steel filament 4b in the steel cord body is suppressed, so that the compression fatigue resistance as the chafer reinforcement layer 4 is ensured. The required protective function of the carcass layer 3 can be strengthened, and the tire durability can be improved.

  Moreover, since the steel cord body and the wrapping filament 4z are in surface contact with the progress of wear of the brass wire, the progress of the wear of the brass wire is gradually suppressed, and the carcass layer 3 is maintained over a long period of time. It becomes possible to strengthen the protection function.

  In the above-described embodiment, the case where the twist structure of the steel cord main body in the chafer reinforcement layer 4 is 3 + 9 and the wrapping filament 4z is composed of one is exemplified, but the heavy load pneumatic of the present invention The structure of the steel cord 4S used for the chafer reinforcement layer 4 of the radial tire 1 is not limited to this. The steel cord body is composed of a plurality of steel filaments, and the brass for wrapping 4z is two or more. The case where it consists of the filament which consists of a strand is included.

  The winding direction of the wrapping filament 4z in the steel cord 4S of the present invention is preferably wound in the direction opposite to the twisting direction of the outermost layer (steel filament 4b in FIG. 2) of the steel cord body. Thereby, the bundling property of the steel cord 4S is enhanced, and the compression fatigue resistance can be secured at a high level.

  In the present invention, the wrapping filament 4z described above is preferably set to have a relatively large wire diameter so that the steel cord 4S is not scattered by the compressive stress applied to the chafer reinforcement layer 4. Specifically, the strand diameter of the wrapping filament 4z may be set to 0.20 to 0.40 mm, preferably 0.22 to 0.30 mm. If the wire diameter is less than 0.20 mm, it becomes difficult to prevent breakage during twisting, and at the same time, the binding property of the steel cord body is weakened, the compression fatigue resistance as the chafer reinforcement layer 4 is lowered, and the carcass The protective function of layer 3 will be reduced, and if it exceeds 0.40 mm, the durability of the brass wire itself will decrease, and at the same time, the thickness of the rubber covering the steel cord 4S will increase, causing the tire weight to increase. Become.

  In the present invention, the winding interval of the wrapping filament 4z is appropriately set according to the structure of the steel cord 4S and the wire diameter, but is preferably set to 4 mm or less. The lower limit is preferably set to 2 mm or more. If the winding interval exceeds 4 mm, the binding property of the steel cord 4S cannot be sufficiently obtained, the compression fatigue resistance of the steel cord 4S is reduced, and the tire durability is lowered. If the winding interval is less than 2 mm, the steel cord is reduced. The productivity of 4S will be significantly reduced.

  The winding interval mentioned above refers to the winding pitch of the wrapping filament 4z when the wrapping filament 4z is composed of one piece, and when the wrapping filament 4z is composed of a plurality of pieces, the respective wrapping intervals are used. This is the interval between the steel filament 4z and the longitudinal direction of the steel cord 4S. Accordingly, when a plurality of wrapping filaments 4z are formed, each wrapping filament 4z may be wound at intervals of 4 mm or less and 2 mm or more in the longitudinal direction of the steel cord body.

  In the present invention, the brass wire constituting the wrapping filament 4z is preferably composed of an alloy of 60 to 70% by weight of copper and 30 to 40% by weight of zinc. Thereby, the ductility of the wrapping filament 4z can be ensured while ensuring good adhesion to the surrounding rubber, and disconnection of the wrapping filament 4z can be prevented during the stranded wire processing.

  In the heavy-duty pneumatic radial tire 1 of the present invention, at least the surface of the steel filament 4b constituting the outermost layer among the steel filaments in the steel cord body of the steel cord 4S constituting the chafer reinforcement layer 4 is plated with brass in advance. It is good to give. As a result, the adhesion between the steel cord body and the wrapping filament 4z is improved, the compression fatigue resistance as the chafer reinforcement layer 4 can be secured at a high level, and the adhesion to rubber is also improved. be able to. Here, the composition of the above-described brass plating may be 60 to 70% by weight of copper and 30 to 40% by weight of zinc in the same manner as the brass wire constituting the wrapping filament 4z.

  In the embodiment of FIG. 2 described above, the steel cord main body in the steel cord S has a twisted structure of 3 + 9, and the wrapping filament 4z is composed of one piece. However, as described above, The structure of the steel cord 4S used for the chafer reinforcement layer 4 of the heavy-duty pneumatic radial tire 1 is not limited to this.

  That is, in the present invention, in addition to the 3 + 9 described above, the twist structure of the steel cord body is 3/9, 3 + 8, 3 + 7, 1 + 18, 1 × 27, 1 × 9, 3 + 9 + 15, 3 + 8 + 13, 3/8 + 13, 4 + 9 + 14, 7 ×. (3 + 9 + 15) or the like, and one or a plurality of wrapping filaments 4z may be wound around the periphery.

  As described above, the heavy-duty pneumatic radial tire according to the present invention includes a steel cord body made of a plurality of steel filaments and a wrapping filament wound around the steel cord in a spiral shape. By configuring this wrapping filament with brass wire, fretting wear that occurs between the steel filament of the steel cord body and the wrapping filament is suppressed, and the compression fatigue property of the chafer reinforcement layer is improved By doing so, the protective function of the carcass layer is enhanced to improve the tire durability, and it is preferably applied to a heavy-duty pneumatic radial tire having a particularly large load.

  Conventional tires with a tire size of 295 / 80R22.5, a tire structure of Fig. 1, a steel cord twist structure used for the chafer reinforcement layer in common with 3 + 9 × 0.22 + 1, and a wrapping filament material made of steel ( Conventional example) and the tires of the present invention (Examples 1 to 3) in which the material of the wrapping filament was made of brass, and the wire diameter and winding bitch of the wrapping filament were different as shown in Table 1, respectively. Five pieces were produced. In Table 1, the twist pitch of each filament in the steel cord body is indicated as the winding pitch.

  Here, the specification of the chafer reinforcement layer in each tire is as follows, and the composition of the brass wire constituting the wrapping filament in the tire of the present invention is an alloy of 65 wt% copper and 35 wt% zinc. .

[Specifications of chafer reinforcement layer]
* Thickness: 1.8mm
* Total width when deployed in the tire axial direction: 100 mm
* Steel cord driving density: 20 per 50mm * Steel cord placement angle with respect to tire circumferential direction: 45 °

  The tire durability of these four types of tires was evaluated by the following test method, and the results are also shown in Table 1 using an index with the conventional example being 100. It shows that it is excellent in durability, so that a numerical value is large.

[Evaluation of tire durability]
Each tire is assembled into a rim (rim size: 22.5 × 8.25) and filled with air pressure of 850 kPa, and then an indoor drum tester (drum diameter: 1707 mm) is used to apply a load of 51.5 kN and a speed of 45 km. It was made to drive | work until a tire destroyed as / h, and the travel distance until it destroyed was measured. This test was performed for five tires each, and the average value was used as the tire durability evaluation.

  From Table 1, it can be seen that the tire of the present invention is superior in tire durability as compared with the conventional tire.

1 is a half sectional view showing an example of a heavy-duty pneumatic radial tire according to an embodiment of the present invention. It is sectional drawing which shows an example of the steel cord which comprises the chafer reinforcement layer in the tire of FIG.

Explanation of symbols

1 Heavy-duty pneumatic radial tire 2 Bead part 3 Carcass layer 4 Chafer reinforcement layer 4S Steel cord 4a, 4b Steel filament 4z Wrapping filament 5 Bead core

Claims (8)

Heavy load air in which a carcass layer is wound around the bead core embedded in the pair of left and right bead portions from the inside to the outside of the tire and a chafer reinforcement layer made of a steel cord is disposed around the wound portion of the carcass layer In entering radial tires,
The steel cord constituting the chafer reinforcement layer is composed of a steel cord body composed of a plurality of steel filaments and a wrapping filament spirally wound around the steel cord body, and the wrapping filament is composed of a brass wire. Heavy duty pneumatic radial tire.   The heavy-duty pneumatic radial tire according to claim 1, wherein a winding direction of the wrapping filament is opposite to a twisting direction of the outermost layer of the steel cord body.   The heavy-duty pneumatic radial tire according to claim 1 or 2, wherein a strand diameter of the wrapping filament is 0.20 to 0.40 mm.   The heavy-duty pneumatic radial tire according to any one of claims 1 to 3, wherein a winding interval of the wrapping filament is 4 mm or less.   The heavy-duty pneumatic radial tire according to claim 4, wherein a winding interval of the wrapping filament is 2 mm or more.   The heavy-duty pneumatic radial tire according to any one of claims 1 to 5, wherein the brass wire is made of an alloy of 60 to 70% by weight of copper and 30 to 40% by weight of zinc.   The heavy-duty pneumatic radial tire according to any one of claims 1 to 6, wherein the surface of the steel filament in the steel cord body is plated with brass.   The twist structure of the steel cord body is selected from 3 + 9, 3/9, 3 + 8, 3 + 7, 1 + 18, 1 × 27, 1 × 9, 3 + 9 + 15, 3 + 8 + 13, 3/8 + 13, 4 + 9 + 14, 7 × (3 + 9 + 15) The pneumatic radial tire for heavy loads according to any one of claims 1 to 7.

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