JP2009242978A - Steel cord for reinforcing rubber structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel cord for reinforcing rubber structures which has good handleability, excellent strength, excellent elasticity, excellent rubber penetrability, and excellent fatigue resistance, does not cause problems of flare and shape ununiformity, even when the twisting pitch of a cord is increased to reduce the cost of production, and does not disorder the twisting. <P>SOLUTION: Provided is the steel cord having a twist structure of 1×2+1 obtained by twisting a strand 5 (core strand) of two twisted element wires 2, 3 (core element wires) with one element wire 4 (side element wire), wherein the twist direction of the strand 5 and the twist direction of the cord 1 are the same , and the pitch P of the strand is larger than the pitch p of the cord to satisfy a relation of 1.15≤P/p≤1.80. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steel cord for reinforcing a rubber structure used as a reinforcing material for tires and belts, particularly a steel cord for reinforcing a rubber structure in which three strands are twisted together (hereinafter simply referred to as a steel cord or a cord). Sometimes).

  Steel cords for reinforcing rubber structures used as reinforcing materials for tires, belts, etc. Especially for steel cords consisting of three strands (steel filaments), three strands of the same diameter are bundled together and twisted In general, a 1 × 3 twisted structure with open strands where the strands are not in close contact with each other to ensure rubber penetration, but such 1 × 3 open twisted steel cords are There is a problem that handling is poor due to large elongation.

  Moreover, as a steel cord for reinforcing a rubber structure composed of three strands, for example, two strands (core strands) are in the same spiral shape and do not wrap around each other so that they are in parallel and become parallel. There is known a 2 + 1 twisted cord in which two strands are bundled, and another strand (side strand) is spirally wound around the strand (see, for example, Patent Document 1). However, in the case of this cord, since the two core strands are parallel, the twist angle between the core strand and the side strand is greatly different, and the core strand and the side strand are close to point contact and fretting. Wear is likely to occur, which causes a decrease in fatigue resistance. In addition, when this cord is used to reinforce an automobile tire, the two core strands are embedded in parallel in the tire width direction, so that force acts in the tire width direction at the cornering of the car. When this occurs, the core wire located on the outside in the bending direction is subjected to a greater force than the core wire located on the inside, resulting in a poor balance between the core wires, which is also fatigue resistant. It becomes a factor of sex decline. Therefore, sufficient fatigue resistance cannot be ensured.

  In addition, as a steel cord for reinforcing rubber structures consisting of three strands, the reinforcement of a rubber structure with a 1 × 2 + 1 structure, in which a strand twisted with two strands and one strand are twisted together Steel cords, strands and cords have the same twist direction, and strand pitch (strand twist pitch) is smaller than cord pitch (cord twist pitch), which is advantageous for shape stability and rubber penetration Steel cords that have a twisted pitch and the coated rubber material penetrates to the center of the steel cord and the rubber material and the steel cord are sufficiently bonded together and have elasticity in the longitudinal direction are known (for example, patents) Reference 2), as a method of manufacturing such a 1 × 2 + 1 structure cord, two strands fed from a reel are passed through a wire guide, and from one axial center of a rotating body Guided to the main body of the twisting machine, rotated around the cradle by rotating the rotating body through the guide roller, guided to the cradle from the other axis of the rotating body while twisting, and simultaneously from the outside of the rotating body from the reel The drawn-out strand is guided into the cradle from the axis of the rotating body, and is taken up by a take-up capstan provided on the cradle while simultaneously twisting the twisted strand and the strand, and then passed through a traverse roller. What is known to be wound on a take-up reel is known (for example, see Patent Document 3). However, in this cord, the twist pitch of the cord is larger than the twist pitch of the strand. Therefore, if the strand twist pitch (hereinafter also referred to as the strand pitch) is increased and the cord twist pitch (hereinafter also referred to as the cord pitch) is increased in an attempt to reduce the production cost, the cord pitch becomes too large and the twist is increased. The problem of flare at the tip and uneven shape tends to occur. Therefore, it is difficult to increase the twist pitch and reduce the production cost.

  In addition, as a cord composed of three strands, it has a 2 + 1 twist structure, and two strands are arranged in parallel as core strands, and another strand (side strand) on the outer periphery thereof Are wound in a spiral shape, and in that state, the bundle of these two core strands and one side strand are twisted at a predetermined pitch P, so that the winding direction of the side strands is the same as the twist of the cord The relationship between the winding pitch pw of one side strand wound spirally and the twist pitch P of the cord is pw <P, and the twist pitch of the side strand wound spirally is the cord The contact between the strands and the non-contact are repeated to form a gap between the strands, and the presence of this gap increases the rubber penetration, and the compression equivalent to that of the existing closed cord The one that can secure the rigidity is known. As a manufacturing method, after passing two strands (core strands) fed out from two reels through guides, they are guided to the flyer, and another one is placed on the outer periphery of the two strands passing through the center of the flyer. One strand (side strand) fed out from a reel (fixed reel) is spirally wound (a twist of one rotation is given for each rotation of the flyer), whereby two core strands arranged in parallel are After obtaining a strand of wire with one side strand wound spirally around the outer circumference, winding this strand of bundle around the twisted backflow prevention roller, and then passing it through the guide hole and twisting port of the eye plate to the stranding machine Guide, here we add a twist of pitch P to this strand of wire, twist the strand of wire in a spiral, finish it into a cord, shape it through a straightener, and wind the finished cord around a reel Has been known for a long time (E.g., see Patent Document 4.). However, in this cord, the two core strands are not twisted together, so that when a tensile load in the cord longitudinal direction is applied, the core strand and the side strand are not evenly applied with force, The balance between the lines deteriorates and the fatigue resistance decreases.

Japanese Patent Publication No.58-31438 JP 58-180690 A JP 58-180691 A JP 2006-89902 A

  Therefore, it is easy to handle, excellent in strength and elasticity, excellent in rubber penetration and fatigue resistance, and even if the cord twist pitch is increased to reduce production costs, flare and shape are not uniform. It is an object to provide a steel cord for reinforcing rubber structures which does not cause problems and does not disturb the twist.

  The steel cord for reinforcing a rubber structure according to the present invention is a cord having a 1 × 2 + 1 twist structure in which a strand twisted by two strands of the same diameter and one strand are twisted, and the strand twist The direction and the twist direction of the cord are the same, and the twist pitch of the strand is larger than the twist pitch of the cord.

  In this steel cord for reinforcing a rubber structure, it is preferable that the strands of the strands and one strand twisted with the strands have the same diameter, and the strand diameters of these strands are 0.20 to 0.38 mm. .

  This steel cord has a closed twist structure in which two strands (core strands) that are cores are twisted, and another strand (side strand) is twisted around it. The initial elongation is small, the handleability is good, and the strength and elasticity are excellent.

  In addition, this steel cord is also twisted in the core strand, so that stress is evenly applied, and the core strand and side strand compared to the 2 + 1 structure cord in which two core strands are parallel The difference in the twist angle is small, the contact length between the strands becomes long, and fretting wear hardly occurs, and therefore the fatigue resistance is good.

  Also, this cord has a different strand twisting pitch and cord twisting pitch (that is, the twisting pitch of the side strands), and there is a gap between the strands due to the deviation in the twisting process. Can be secured.

  And since this cord also has a twist in the same direction as the side strands in the core strand, the tip is difficult to flare, and since the strand pitch is larger than the cord pitch, it is possible to increase the cord pitch. Production cost can be reduced.

  In particular, the steel cord for reinforcing a rubber structure preferably satisfies the relationship of 1.15 ≦ P / p ≦ 1.80, where P is the strand twist pitch and p is the cord twist pitch.

  When P / p is smaller than 1.15, the difference in twist angle between the core strand and the side strand is reduced, the gap between the strands is reduced, and the rubber penetration is deteriorated. On the other hand, if P / p is greater than 1.80, the difference in twist angle between the core strand and the side strand becomes too large, the contact length between the strands becomes short, and fretting wear tends to occur. As a result, fatigue resistance deteriorates.

  As described above, the steel cord for reinforcing rubber structure of the present invention has good handleability, excellent strength and elasticity, excellent rubber penetration, excellent fatigue resistance, and a cord for reducing production cost. Even if the twist pitch is increased, the problem of flare and uneven shape does not occur, and the twist is not disturbed.

  That is, since this cord is a closed twist in which two core strands are twisted and one side strand is twisted around it, the initial elongation is small, the handleability is good, the strength and elasticity Is excellent.

  This cord is also twisted in the core wire, so that stress is evenly applied, the difference in twist angle between the core strand and the side strand is small, and the contact length between the strands is small. The fretting wear hardly occurs and the fatigue resistance is good.

  Further, this cord has a different strand pitch and cord pitch, and a deviation occurs in the progress of twisting, so that a gap is formed between the strands and rubber penetration can be ensured.

  Also, this cord has a twist in the same direction as the side strands, so the tip is difficult to flare, and since the strand pitch is larger than the cord pitch, it is possible to make the cord longer pitch, Production cost can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show an example of an embodiment of the present invention. FIG. 1 is a cross-sectional view (a) and a front view (b) of a steel cord, FIG. 2 is an explanatory diagram of a stranded wire facility used for manufacturing a steel cord, and FIG. It is explanatory drawing of a sticking apparatus.

  A steel cord 1 shown in FIG. 1 is a steel cord for reinforcing rubber structures used as a reinforcing material for tires, belts, etc., and is composed of three strands 2, 3, 4 (steel filaments). The strands 2, 3, and 4 of the book have the same wire diameter (same diameter). And this steel cord 1 is a strand 1 (core strand) twisted by two strands 2 and 3 (core strands) and a strand 4 (side strand) 1 twisted together. A twisted structure of × 2 + 1, where the strand 5 and the cord 1 are twisted in the same direction, and the strand 5 has a twist pitch (strand pitch) P of the side strand 4, that is, a cord 1 twist pitch (cord (Pitch) larger than p. The strand diameters of the three strands 2, 3 and 4 are, for example, 0.20 to 0.38 mm. Moreover, it is preferable that the twist pitch P of the strand 5 and the twist pitch p of the cord 1 satisfy the relationship of 1.15 ≦ P / p ≦ 1.80.

  This steel cord is manufactured using, for example, a stranded wire facility 10 shown in FIG. This stranded wire equipment 10 uses a buncher type twisted wire machine 11. Two strands 2 and 3 (core strands) fed out from the respective reels 12 and 13 are converted into one strand 4. A through-hole 15 passing through the center of the feeding reel 14 wound with (side strands) in the axial direction is passed in parallel, and through the through-hole 17 passing through the center of the side strand feeding rotary disk 16, the brazing device 18. In this case, it is fed out from the feeding reel 14 by the rotation of the side wire feeding rotary disk 16 around the two strands 2 and 3 (core strands) arranged in parallel to each other. One strand 4 (side strand) is spirally wound, and the two strands 2 and 3 (core strand) and the wound one strand 4 (side strand) are bundled together Pass through the die 19 and lead to the buncher type stranding machine 11, Guide to the tip guide roller 22 through the center guide roller 21, guide from the tip guide roller 22 to the tip guide roller 24 of the other fryer 23, rotate the periphery of the cradle 25 by rotation of the fryer 20, 23, While twisting two strands 2 and 3 (core strands) and three strands 4 (side strands) at the same time, they are guided into the cradle 25 through the axial guide roller 26 of the fryer 23, It is taken up by a take-up capstan 28 via a turn roller 27 provided on the cradle 25 and taken up on a take-up reel 30 via a traverse roller 29.

  The steel cord 1 manufactured in this way has a strand 5 (core strand) twisted by two strands 2 and 3 (core strands) and one strand 4 (side strands) as shown in FIG. The strand 5 is twisted in the same direction as that of the cord 1. And this steel cord 1 can be made into the steel cord 1 larger than the twist pitch (strand pitch) P of the strand 5, and the twist pitch of the side strand 4, ie, the twist pitch (cord pitch) p of the steel cord 1. FIG.

  For example, the pitch of one strand 4 (side strand) that is spirally wound around two strands 2 and 3 (core strands) arranged in parallel is 28 mm. When the pitch for twisting three strands 2 and 3 (core strands) and three strands 4 (side strands) at the same time is 18 mm, the finished steel cord 1 has two core strands. The twist pitch (strand pitch) P of the strands 5 consisting of 2 and 3 is 18 mm, the twist pitch of the side wires 4, that is, the twist pitch (cord pitch) p of the steel cord 1 is 11 mm, and P> p. Appropriate selection of the pitch of one strand 4 (side strand) wound spirally around two strands 2 and 3 (core strands) arranged in parallel and the pitch to be twisted with a buncher twister By doing so, P and p can be set to satisfy 1.15 ≦ P / p ≦ 1.80.

  As shown in FIG. 3, the wrinkling device 18 is configured to pass the corrugation by passing the wires 2 and 3 between the two pins 31 and 32 arranged in the feeding direction. Two squeezing devices 18 may be provided in parallel so as to be squeezed separately one by one, or two squeezing devices 18 may be squeezed simultaneously by one device.

  Table 1 shows the (1 × 2) +1 structure shown in FIG. 1, the strand diameter is 0.30 mm, the strand pitch (core): P = 24 mm, the cord pitch (side): p = 18 mm, P / p = 1 .33, steel cord satisfying the relationship of 1.15 ≦ P / p ≦ 1.80 (Example), strand diameter is 0.30 mm, strand pitch (core): P = 20 mm, cord pitch (side) : Steel cords (Examples) satisfying the relationship of 1.15 ≦ P / p ≦ 1.80 at p = 16 mm and P / p = 1.25 were prepared, fatigue resistance, rubber penetration, productivity Evaluate the handleability, and similarly, a 1 × 3 open twisted structure with a wire diameter of 0.30 mm, a cord pitch (side) of 16 mm steel cord (conventional example), and a 2 + 2 structure Steel cord with a diameter of 0.25 mm and a cord pitch (side) of 14 mm (conventional Example) and (1 × 2) +1 structure, strand diameter is 0.30 mm, strand pitch (core): P = 24 mm, cord pitch (side): p = 22 mm, P / p = 1.09, 1.15 ≦ P / p ≦ 1.80 Steel cord (comparative example) that does not satisfy the relationship, (1 × 2) +1 structure, strand diameter 0.30 mm, strand pitch (core): P = 24 mm , Cord pitch (side): p = 12 mm, P / p = 2.00, steel cord not satisfying the relationship of 1.15 ≦ P / p ≦ 1.80 (comparative example), and (1 × 2) +1 The structure has an element wire diameter of 0.30 mm, strand pitch (core): P = 20 mm, cord pitch (side): p = 18 mm, P / p = 1.11, 1.15 ≦ P / p ≦ 1. Steel cord that does not satisfy the relationship of 80 (comparative example), (1 × 2) +1 structure, wire diameter is 0.3 mm, strand pitch (core): P = 20 mm, cord pitch (side): p = 11 mm, P / p = 1.82, steel cord not satisfying the relationship of 1.15 ≦ P / p ≦ 1.80 Comparative example) was evaluated, and they were compared and displayed as a list.

  For fatigue resistance, a composite sheet is created by embedding a plurality of cords in a rubber material, and this sheet is used to create a composite sheet until the cord breaks through fretting wear, buckling, etc. The number of repetitions of the above was obtained and the index was displayed with the conventional example of 1 × 3 open twist structure as 100.

  For rubber penetration, each cord is embedded in a rubber material under a tensile load of 49 N, pressure vulcanized, the cord is taken out, the cord is disassembled and a certain length is observed, and the observed length The ratio of the length of the traces in contact with the rubber was obtained, and the index was expressed as an index, with the conventional example of a 1 × 3 open twist structure as 100.

  For productivity, the production cost of each cord is shown as an index with the conventional example of 1 × 3 open twist structure as 100.

  The handling workability was evaluated as ◯ when the conventional example of the 1 × 3 open twist structure was better than the standard (Δ).

  From this evaluation result, in the case of the conventional example and the comparative example, any of the characteristics of fatigue resistance, rubber penetration, productivity, and handleability is insufficient, whereas in the (1 × 2) +1 structure, It can be seen that the steel cords of Examples satisfying the relationship of 1.15 ≦ P / p ≦ 1.80 have good characteristics in all of fatigue resistance, rubber penetration, productivity, and handleability.

The steel cord which concerns on embodiment of this invention is shown, (a) is sectional drawing, (b) is a front view. It is explanatory drawing of the strand wire installation used for manufacture of the steel cord which concerns on embodiment of this invention. It is explanatory drawing of the brazing apparatus in the strand wire installation used for manufacture of the steel cord which concerns on embodiment of this invention.

Explanation of symbols

1 Steel cord 2, 3 Wire (core wire)
4 strands (side strands)
5 strand (core strand)
P Strand twist pitch p Side strand twist pitch (Cord twist pitch)
10 Twisted wire equipment 11 Buncher type twisted wire machine

Claims (3)

It is a cord of a 1 × 2 + 1 twist structure in which a strand twisted by two strands of the same diameter and one strand is twisted, and the twist direction of the strand and the twist direction of the cord are the same, A steel cord for reinforcing a rubber structure, wherein a twist pitch of the strand is larger than a twist pitch of the cord. The steel for reinforcing a rubber structure according to claim 1, wherein the strand of the strand and one strand twisted with the strand have the same diameter, and the strand diameter of the strands is 0.20 to 0.38 mm. code. 3. The steel cord for reinforcing a rubber structure according to claim 1, wherein a twisting pitch of the strand is P and a twisting pitch of the cord is p, and a relationship of 1.15 ≦ P / p ≦ 1.80 is satisfied.

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