JP5264094B2 - Steel cord for reinforcing rubber products and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel cord which is used for reinforcing rubber products, can reduce production cost, has good rubber material invasiveness, is little extended with low loads, and has a two-layered structure. <P>SOLUTION: The method for producing the steel cord 10 comprises forming spiral curls on all core strands 11, pressing the product to form smaller pitch approximately sine wave-like curls than pitches for twisting in an approximately sine wave-like shape, simultaneously twisting the core strands 11 with side strands 12 to form a bundle-twisted two-layered structure, and then pressing the product in the direction crossing the longitudinal direction of the cord. Thus, in the cord 10, the core strands 11 contact with each other at any places in the longitudinal direction of the cord, and are discontinuously arranged in the longitudinal direction of the cord to partially contact in approximate parallel. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  TECHNICAL FIELD The present invention relates to a steel cord for reinforcing rubber products (hereinafter sometimes simply referred to as “cord”) used as a reinforcing material for rubber products such as automobile tires and conveyor belts.

  Steel cords for reinforcing rubber products with two-layer structures used as rubber product reinforcements for automobile tires, conveyor belts, etc. Conventionally, multiple strands have been rigidly formed by two-layer twisting such as 1 + 6 structure, 3 + 9 structure, etc. A cord having a so-called closed twist structure, which is twisted and closely adhered, is generally used. However, this closed twisted cord has a closed cavity between adjacent strands, and when a composite sheet is formed by sandwiching the cord between two rubber sheets and heat-compressing the rubber, The material does not invade the cavity between the strands, and it is a composite that simply wraps the cord with the rubber sheet, and the rubber material completely penetrates into the cavity between the cord strands. Does not become a so-called perfect composite. Therefore, when a composite sheet obtained by compressing a conventional closed twisted cord sandwiched between rubber sheets is incorporated into, for example, an automobile tire, the adhesion between the rubber material and the cord is insufficient, and the rubber material peels off from the cord when the automobile is running. The so-called separation phenomenon is highly likely to occur, and when the moisture that has penetrated into the rubber material reaches the cavity of the cord, the moisture propagates through the cavity and quickly propagates in the longitudinal direction of the cord to corrode the cord. As a result, there is a problem that the mechanical strength of the cord is remarkably lowered. Furthermore, since the cord having a two-layer twisted structure is twisted twice, there is a problem that the manufacturing cost is increased.

  In addition, a gap is provided between the strands by reducing the number of strands (referred to as “side strands”) of the strands constituting the outer layer (referred to as “side strands”) in a two-layer twisted structure. A cord that facilitates the intrusion of rubber material is also known. However, since this cord is also twisted twice, the problem of high cost cannot be solved.

  Further, in order to reduce the manufacturing cost, the strands of the side strand group (side strands) and the strands of the strand group constituting the center layer (referred to as “core strand group”) (“core strands”) ")") Is twisted at a time to form a two-layer cord. This technique is called bundle twisting. A bundle-twisted two-layer structure is usually represented by “1 × P”.

  Since the cord of the twisted two-layer structure is twisted once, the manufacturing cost can be reduced. However, in this cord, the side strand enters into the recess between adjacent core strands (sinks), the rubber entry path is blocked, and the rubber material enters the space between the core strand and the side strand. Have the problem of not.

  Further, as shown in FIG. 5, in the cord 50 having a two-layer structure, the core strand group and the outer layer strand group are each composed of a predetermined number of strands 51 and 52, and are twisted to a part of the core strand group. It has a small helical comb that is different from the matching comb (the example shown in the figure shows a case where a helical comb is provided in one of the three strands 51 of the core strand group. .) It is proposed to be. Since the cord 50 is bundle-twisted, the manufacturing cost can be reduced. In addition, there is a gap 53 communicating with the outside between a strand provided with a spiral bevel (referred to as “spiral strand”) and a strand not provided with a spiral bevel (referred to as “non-spiral strand”). Rubber material invades.

  However, the cord in which only a part of the core wire group is provided with a spiral bend in this way becomes a closed cavity portion 54 surrounded by the non-spiral strands, and rubber does not enter there. .

  Therefore, as shown in FIG. 6, in the cord 60 of the bundle-twisted two-layer structure, the core strand group and the outer layer strand group are each composed of a predetermined number of strands 61 and 62. It is conceivable that the strand 61 is a spiral strand (for example, see Patent Document 1). By doing so, the gap 63 communicating with the outside is enlarged, and the closed cavity is eliminated. However, if all the strands 61 of the core strand group are spiral strands in this way, the elongation of the cord becomes large, which becomes a new problem.

  The cord needs to be stretched to some extent in order to obtain flexibility. However, if the cord is stretched more than necessary, the rigidity of the tire is lowered. In particular, a cord used for a carcass portion of a tire that is becoming steel in recent years is not suitable for a cord having a large low load elongation because the running stability of the tire is lowered.

Japanese Utility Model Publication No. 4-60590

  Accordingly, it is an object to obtain a steel cord for reinforcing rubber products having a two-layer structure that can reduce the manufacturing cost, has good rubber material penetration, and has low load elongation.

The above problem is that a steel cord having a 1 × P (P = 7 to 14) bundle-twisted two-layer structure has a gap between at least some of the strands of the strands constituting the outer layer, and the center Separately from the twist for twisting, all the strands of the strands that make up the layer are twisted in a substantially two-dimensional wave shape obtained by pressing and then twisting. An element having a smaller pitch than a habit, and is in contact with each other in a substantially parallel manner so that adjacent strands of the strand group constituting the central layer are substantially parallel to the cord central axis. By configuring so that the difference between the strand angle of the strands of the wire group and the strand angle of the strands of the strand group constituting the outer layer is partially present in a discontinuous arrangement in the cord longitudinal direction. Can be solved.

Since this cord has a twist structure once, the manufacturing cost can be reduced.
And the rubber material which penetrate | invaded from the clearance gap between the strands (side strand) of the strand group (side strand group) which comprises an outer layer of the strand group (core strand group) which comprises a center layer It enters a gap formed between a strand (core strand) having a pitch smaller than a strand for twisting and a side strand. Moreover, since all the strands of the core strand group have a smaller pitch than the twist for twisting, there is a closed cavity between the side strand group and the core strand group. It will not do. Therefore, the rubber material easily enters.

  Furthermore, this cord has a portion where adjacent core strands are in contact with each other in substantially parallel so as to be substantially parallel to the cord central axis, and the difference between the twist angle of the core strand and the twist angle of the side strand is increased. Because it is partly discontinuously arranged in the longitudinal direction of the cord, it is possible to prevent the side strands from entering into the recesses between adjacent core strands by aligning the twist angles, and the rubber material entry path Is secured.

  And, since adjacent core strands having a pitch smaller than the twist for twisting are in contact with each other in parallel in the longitudinal direction of the cord, the extension of the cord is small and the load is low as in the case of the closed twisted cord. Elongation can be suppressed.

  In the cord having the above-described configuration, the habit having a smaller pitch than the habit for twisting is preferably a habit obtained by pressing a strand after forming a helical habit on the strand. Even if a wire is passed between a pair of gears whose teeth have been processed into a desired shape, a small wrinkle can be obtained by bending the wire into a zigzag shape. The degree of work becomes greater than the part where there is not, stress remains in the bent part where the degree of work is large, and stress due to external force is added to this, so that the stress at the bent part becomes excessive and the fatigue resistance decreases. On the other hand, the wrinkle obtained by applying a pressurizing process after applying a helical wrinkle has a uniform degree of processing at any location, so that excessive stress does not act and it has excellent fatigue resistance. Become.

  Further, the pitch P1 is P1 = 0.2Pc to 0.5Pc (where Pc is the pitch of twisting) and the wave height h is h = 0.2d to It is preferably 1.2d (where d is the wire diameter). If the pitch P1 is smaller than 0.2 Pc, excessive plastic deformation is applied to cause excessive stress at the time of soldering, so that the strands are easily broken and the productivity is lowered, and the pitch P1 is less than 0.5 Pc. If it is large, the tensile force is not evenly applied, and the twist stability of the intermediate strand group is deteriorated and the fatigue resistance is deteriorated. Also, if the wave height h is less than 0.2d, the gap between the wires becomes too small, and even if a rubber material with good fluidity is used, the rubber material can sufficiently penetrate into the interior during pressure vulcanization. If the wave height h is greater than 1.2 dmm, the twist stability is deteriorated and the fatigue resistance is deteriorated. Note that the values of the pitch P1 and the wave height h, which have a smaller pitch than the twists for twisting, coincide with those of the strands obtained by untwisting the cord.

  The steel cord for reinforcing rubber products having a 1 × P (P = 7 to 14) twisted two-layer structure according to the present invention is obtained by attaching a helical habit to all the strands of the strand group constituting the central layer. A pressing process is performed to provide a two-dimensional wave shape with a pitch smaller than the twist for twisting, and a group of strands of the central layer and a group of strands of the outer layer composed of the strands having the substantially two-dimensional wave shape A steel cord having a bundle-twisted two-layer structure in which a gap exists between at least some of the strands of the outer layer by twisting at the same direction and at the same pitch is formed, and the steel cord is orthogonal to the longitudinal direction of the cord. It can be manufactured by pressing from the direction.

  In this way, a bundle formed by twisting together a group of strands (core strand group) in the central layer and a group of strands (side strand group) constituting the outer layer, composed of strands having substantially two-dimensional wavy combs. By pressing the steel cord with a twisted two-layer structure from the direction orthogonal to the longitudinal direction of the cord, adjacent strands of the strand group constituting the center layer are made substantially parallel so that they are substantially parallel to the cord central axis. A portion where the difference between the twist angle of the strands of the strand group constituting the central layer in contact with the strands (side strands) of the strand group constituting the outer layer is increased in the cord longitudinal direction. The code is partially present in a discontinuous arrangement.

  In this manufacturing method, the strands of the core strand group are wound on a reel or the like after being subjected to a pressing process by applying a helical crease and then being wound on a reel, etc. A predetermined number of wires may be set and twisted together, or the kneading process may be performed between the twisting device and the twisting opening.

  According to the present invention, it is possible to obtain a steel cord for reinforcing a rubber product having a two-layer structure that can reduce the manufacturing cost, has good rubber material penetration, and has low low load elongation. By using it as a reinforcing material, the life of the tire can be greatly extended. In addition, since the low load elongation is small, this cord can be used for a carcass portion of a tire that is becoming steel.

  In addition, this cord is made by making the strands of the core strands of the strands obtained by pressing after applying a spiral bevel, so that the degree of processing becomes uniform and excessive stress acts. Therefore, it can be made excellent in fatigue resistance.

  Also, this cord is in the state of the strand after untwisting, and the pitch P1, which is smaller than the twist for twisting, is P1 = 0.2Pc to 0.5Pc (where Pc is twisted) In this case, it is possible to avoid excessive plastic deformation and increase productivity, and to prevent the fatigue resistance of the core wire group from being deteriorated. In addition, by setting the wave height h of the habit having a smaller pitch than the habit for twisting to be h = 0.2d to 1.2d (where d is the wire diameter), the rubber material is sufficiently inside. It is possible to prevent the fatigue resistance from deteriorating.

  Hereinafter, a steel cord for reinforcing rubber products according to an embodiment of the present invention (hereinafter referred to as “steel cord” or simply “cord”) will be described with reference to the drawings.

  FIG. 1 shows a cross-sectional structure of a steel cord having a 1 × 11 structure as an example of a 1 × P (P = 7 to 14) bundle-twisted two-layer structure.

  The cord (steel cord) 10 shown in FIG. 1 has a 1 × 11 bundle-twisted two-layer structure, and after all three strands (core strands 11) arranged on the center side are provided with a helical wrinkle Bundle twisting 2 formed in this manner by pressing and forming a sinusoidal wave with a pitch smaller than that for twisting, arranging 8 strands (side strands 12) on the outside and twisting them at once. A cord having a layer structure is pressed from a direction orthogonal to the longitudinal direction of the cord.

  The cord 10 has a gap 13 between at least some of the strands (side strands 12) of the strands (side strands) constituting the outer layer and the strands constituting the core layer All of the strands (core strands 11) of the (core strand group) are substantially two-dimensional waves apart from the twist for twisting, and have a pitch and a wave height smaller than the twist for twisting. Yes. This substantially two-dimensional wavy beak is obtained by adding a helical beak to the strand (core strand 11) and then pressing the strand, and is substantially sinusoidal in the state of the strand before twisting. is there.

  The substantially sinusoidal habit of the strands before twisting means the length (period) P1 from the valley of the wave to the valley or from the peak to the peak as shown in FIG. 3, and the wave height is from the valley of the wave. It means the height (amplitude) h to the mountain. And, the substantially two-dimensional wavy habit of the core strand 11 has a pitch P1 of P1 = 0.2 Pc to 0.5 Pc (where Pc is a twisted pitch) and a wave height h of h = 0.2 d to 1.2d (where d is the wire diameter). In addition, it is preferable that the strand diameter d is 0.15-0.40 mm. If it is less than 0.15 mm, the strength of the steel cord is lowered, and if it exceeds 0.40 mm, the flexibility is deteriorated. The twist pitch Pc is usually 8.0 to 18.0 mm.

  As shown in FIG. 4, in the cord 10, the strands of the core strand group (core strands 11) are partly in contact with each other in a discontinuous arrangement in the longitudinal direction of the cord. Of the strand (side strand 12) of the strand group (side strand group) constituting the outer layer (not shown) in which the twist angle α of the core strand 11 is 0 (zero) at the location (range) A in contact with The difference from the twist angle (same as the twist angle α in the non-parallel portion of the core wire 11) is large.

  Side strands 12 are arranged outside a plurality of core strands 11 (three in the example shown in the figure) having a small sinusoidal shape, and twisted at a time to form a cord, orthogonal to the cord longitudinal direction. When the pressing process is performed from the direction in which the wires are pressed, the plurality of core strands 11 come into contact with the portions that become the predetermined twist angle α by periodically adapting at intervals in the longitudinal direction of the cord and being pressed in a substantially parallel manner. As a result, a twisted structure as shown in FIG. 4 is obtained.

Since the cord 10 has a twisted structure, the manufacturing cost can be reduced.
And the rubber material which penetrate | invaded from the clearance gap 13 between the strands (side strand 12) of the strand group (side strand group) which comprises an outer layer is the strand group (core strand group) which comprises a center layer ) Enters the gap 14 formed between the strand (core strand 11) having a small two-dimensional wavy shape and the side strand 12. Moreover, since all the strands (core strands 11) of the core strand group have a small two-dimensional wave shape, this cord 10 is a cavity closed between the side strand group and the core strand group. The part does not exist. Therefore, the rubber material easily enters.

  Furthermore, the cord 10 has a core wire 11 having a substantially two-dimensional wave-like bevel in contact with the cord in the parallel direction in the longitudinal direction of the cord. it can.

  Further, in the cord 10, the adjacent core strands 11 are brought into contact with each other substantially in parallel, and the portion where the difference between the twist angle of the core strand 11 and the twist angle of the side strand is large is discontinuous in the longitudinal direction of the cord. Since this arrangement is partially present, the side wires 12 are prevented from falling due to the uniform twist angles, and a rubber material intrusion path is secured.

  FIG. 2 shows a cross-sectional structure of a steel cord having a 1 × 12 structure as another example of an embodiment having a 1 × P (P = 7 to 14) bundle-twisted two-layer structure.

  The cord (steel cord) 20 shown in FIG. 2 has a 1 × 12 bundle-twisted two-layer structure, and after all three strands (core strands 21) arranged on the center side have been given a helical wrinkle Bundle twisting 2 formed in this manner by pressing and forming a sinusoidal shape with a pitch smaller than the twist for twisting, arranging 9 strands (side strands 22) on the outside and twisting them at once. A cord having a layer structure is pressed from a direction orthogonal to the longitudinal direction of the cord.

  The cord 20 includes a gap 23 between at least some of the strands (side strands) constituting the outer layer (side strands 22) and the strands constituting the core layer. All of the strands (core strands 21) of the (core strand group) are substantially two-dimensional wavy apart from the twist for twisting and have a smaller pitch and wave height than the twist for twisting. Yes. This substantially two-dimensional wave-like beak is obtained by adding a helical beak to the strand (core strand 21) and then pressing the strand, and is substantially sinusoidal in the state of the strand before twisting. is there.

  In the case of this cord 20 as well, as shown in FIG. 3, the pitch P1 is P1 = 0.2Pc to 0.5Pc (where Pc is Pc) as shown in FIG. Twist pitch), and the wave height h is h = 0.2d to 1.2d (where d is the wire diameter). In addition, it is preferable that the strand diameter d is 0.15-0.40 mm. If it is less than 0.15 mm, the strength of the steel cord is lowered, and if it exceeds 0.40 mm, the flexibility is deteriorated. The twist pitch Pc is usually 8.0 to 18.0 mm.

  In addition, as shown in FIG. 4, the cord 20 is also configured such that the strands (core strands 21) of the core strand group are in contact with each other in a discontinuous arrangement in the longitudinal direction of the cord, and are approximately parallel. Of the strand (side strand 22) of the strand group (side strand group) constituting the outer layer (not shown) when the twist angle α of the core strand 21 is 0 (zero) at the location (range) A in contact with The difference from the twist angle (same as the twist angle α in the non-parallel portion of the core wire 21) is large.

  Side strands 22 are arranged outside a plurality of core strands 21 (three in the example shown in the figure) having small sinusoidal wrinkles and twisted at a time to form a cord, which is orthogonal to the cord longitudinal direction. When the pressing process is performed from the direction in which the wires are pressed, the plurality of core strands 21 come into contact with the portions that are periodically adapted to the predetermined longitudinal angle α with an interval in the longitudinal direction of the cord and in a substantially crushed shape in a substantially parallel manner. As a result, a twisted structure as shown in FIG. 4 is obtained.

Since the cord 20 has a twisted structure, the manufacturing cost can be reduced.
And the rubber material which penetrate | invaded from the clearance gap 23 between the strands (side strand 12) of the strand group (side strand group) which comprises an outer layer is the strand group (core strand group) which comprises a center layer ) Enters the gap 24 formed between the strand (core strand 21) having a small two-dimensional wavy shape and the side strand 22. In addition, since all the strands of the core strand group (core strand 21) have a small two-dimensional wave shape, this cord 10 has a closed cavity between the side strand group and the core strand group. The part does not exist. Therefore, the rubber material easily enters.

  Further, the cord 20 has a core wire 21 having a substantially two-dimensional wavy comb in contact with the cord in the parallel direction in the longitudinal direction of the cord. it can.

  Further, in the cord 20, adjacent core strands 21 are in contact with each other in approximately parallel, and the portion where the difference between the twist angle of the core strand 21 and the twist angle of the side strand is large is discontinuous in the longitudinal direction of the cord. Since this arrangement is partially present, the side strands 22 are prevented from falling due to uniform twist angles, and a rubber material intrusion path is secured.

  As an example, a steel wire having a diameter of 5.5 mm was repeatedly subjected to patenting and wire drawing, and then subjected to brass plating on the surface to form a strand having a wire diameter of 0.25 mm. 1 × 11 (sometimes expressed as 3/8) bundled two-layer structure with 3 strands on the side and 8 strands on the outside and 1 × 12 (3/9) 2 types of cords having a bundle-twisted two-layer structure (in some cases) were manufactured.

  The cords of the bundle-twisted two-layer structure of the 1 × 11 structure and the 1 × 12 structure of these examples are obtained by attaching the three strands (core strands) that form the core strand group to each of the helical strands. , Processed into strands having a small sine wave-like bevel (a pitch smaller than that for twisting) by pressing, and the core wire having the small sine wave-like bean and the side disposed on the outside The strands are twisted together at the same direction and at the same pitch, and are manufactured by pressing the bundle-twisted two-layer structure cord thus formed from the direction perpendicular to the cord longitudinal direction.

  In any case, the helical wrinkle was applied using a wrinkle device (a wrinkle device described in Japanese Patent Publication No. 63-63293, etc.) that rotates using the supplied strand as an axis. The comb shape was adjusted by the spacing of the tacking pins, the dimension of the tacking pins, and the number of rotations rotating around the element wire.

  Moreover, the pressing process which processes a helical comb into a substantially sinusoidal pattern and the pressing process after the stranded wire processing were performed by a known pressing device in which a plurality of freely rotating rollers are arranged in a staggered manner. However, the pressing means is not limited to this.

  The rubber penetration, low load elongation and stability of the twisted structure of the cords of the examples manufactured in this way were evaluated in comparison with the cords of the conventional examples.

  For rubber penetration, each cord is embedded in a rubber material under a tensile load of 49 N, and after pressure vulcanization, 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 traces in contact with rubber to the percentage was evaluated as a percentage.

  The low load elongation was evaluated by expressing the elongation at a load of 49 N as a percentage.

  In a conventional example, a steel wire having a diameter of 5.5 mm is subjected to patenting and wire drawing, and then subjected to plus plating on the surface to obtain a strand having a wire diameter of 0.25 mm. 1 × 11 cord with closed structure, 1 × 11 cord with two spiral strands, 1 × 12 closed cord, 1 × 12 core Four types of cords were manufactured, in which two of the three strands had a spiral bevel.

表１から、実施例のコードは全ての評価で従来コードより優れていることが明らかである。 The evaluation results are shown in Table 1.

From Table 1, it is clear that the code of the example is superior to the conventional code in all evaluations.

It is sectional drawing of the steel cord of the 1 * 11 bundle twist 2 layer structure of embodiment of this invention. It is sectional drawing of the steel cord of the 1 * 12 bundle twist 2 layer structure of embodiment of this invention. It is explanatory drawing of the pitch and wave height of the substantially sinusoidal habit in embodiment of this invention. It is explanatory drawing of the twist structure of the intermediate | middle strand group in embodiment of this invention. It is sectional drawing of the steel cord in which one strand of a core strand group has a helical habit different from the habit for twisting by the conventional 1x12 bundle twist 2 layer structure. It is sectional drawing of the code | cord | chord which has the helical habit different from the habit for twisting all the strands of the core strand group by the conventional 1 * 12 bundle twist 2 layer structure.

Explanation of symbols

10, 20 cord (steel cord)
11, 21 Core strands 12, 22 Side strands 13, 23 Gap

Claims (3)

1 × P (P = 7 to 14) bundle-twisted two-layer steel cord, wherein there is a gap between at least some strands of the strand group constituting the outer layer, and the central layer is Apart from the twist for twisting, all the strands of the group of constituent strands are approximately two-dimensional wavy obtained by pressing after forming a spiral warp than the twist for twisting A group of strands having a small pitch and forming a central layer by contacting the adjacent strands of the group of strands constituting the central layer substantially parallel to each other so as to be substantially parallel to the cord central axis A rubber product characterized in that a portion where the difference between the strand angle of the strands of the wire and the strand angle of the strands of the strands constituting the outer layer is partially present in a discontinuous arrangement in the cord longitudinal direction Steel cord for reinforcement. The pitch smaller than the twist for twisting is such that the pitch P1 is P1 = 0.2 Pc to 0.5 Pc (where Pc is the twisting pitch), and the wave height h is h = 0.2 d to 1. The steel cord for reinforcing rubber products according to claim 1 , wherein the steel cord is 2d (where d is a wire diameter). A method of manufacturing a steel cord having a two-layer structure of 1 × P (P = 7 to 14) bundle-twisting, in which all strands of the strand group constituting the central layer are subjected to a pressing process after being helically attached In the same direction, the strands of the central layer and the strands of the outer layer composed of strands having a substantially two-dimensional wave shape and a pitch smaller than the twist for twisting are formed in the same direction. And forming a steel cord of a bundle-twisted two-layer structure in which a gap exists between at least some of the strands of the outer layer by twisting at the same pitch at a time, from the direction perpendicular to the longitudinal direction of the cord provide Reinforced pressing process, strands of the strand groups wires adjacent the strand group constituting the central layer constitutes the said center layer in contact with the substantially parallel so as to be substantially parallel to the cord center axis Between the twist angle of the wire and the twist angle of the strands of the strands constituting the outer layer Larger portion is a rubber product manufacturing method of the reinforcing steel cord, characterized in that the code present partially in discontinuous located in code longitudinally.

Images