JP2010185167A - Steel cord - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel cord for reinforcement of rubber products for preventing a core filament of a core strand from escaping from a rubber member by enabling to let the rubber infiltrated up to the surface of the core filament of the core strand without lowering cutting load of the cord. <P>SOLUTION: The core strand 22 of the steel cord 10 is composed of one core filament 22C and five sheath filaments 22S stranded around the core filament 22C. Six sheath strands 26 are stranded around the core strand 22. Since each space between the core filament 22C is large enough, the rubber member is infiltrated more into the core filaments 22C. Consequently, the steel cord 10 for reinforcement of rubber products for inhibiting the escape from the core filament 22C is realized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steel cord for reinforcement incorporated in a rubber product.

  Steel cords are frequently used as reinforcing materials for rubber parts such as pneumatic tires and elastic crawlers. In pneumatic tires, elastic crawlers, and the like, in order to increase the load resistance of the steel cord, the structure of the steel cord is often a 7 × 7 structure with an increased cord cutting load.

  The 7 × 7 structure is a structure in which six sheath strands 86 are arranged around one core strand 82 as in a steel cord 80 shown in FIG. The diameters of the core filament 82C and the sheath filament 82S constituting the strand 82 and the diameters of the core filament 86C and the sheath filament 86S constituting the sheath strand 86 are all the same.

  However, in the structure as shown in FIG. 5, the gap between the sheath filaments 82 </ b> S constituting the core strand 82 is narrow, so that the rubber penetration into the core filament 82 </ b> C constituting the core strand 82 is low. For this reason, when a rubber product having the steel cord 80 is used (for example, when a pneumatic tire is used), the core filament 82C constituting the core strand 82 is changed to the steel cord 80 as a result of the load being repeatedly input to the rubber product. From the end of the rubber product to the surface side of the rubber product (mainly the tread surface side in the case of a pneumatic tire). Then, water enters and propagates from the outside starting from the filament exposed on the tread surface side, which causes corrosion fatigue and breaks the steel cord.

  In addition, the same problem has arisen even if it is the steel cord of the structure disclosed by patent documents 2-5.

  As a countermeasure against this, as shown in FIG. 6, a steel cord 90 in which the diameter of the core filament 92C of the core strand 92 is made larger than the diameter of the sheath filament 92S of the core strand 92 to prevent the core filament 92C from jumping out is It is disclosed in Document 6. In FIG. 6, the diameter of the core filament 96 </ b> C of the sheath strand 96 is also larger than the diameter of the sheath filament 96 </ b> S of the sheath strand 96.

  However, when the structure shown in FIG. 6 disclosed in Patent Document 6 is used, the diameters of the core filament 92C and the core filament 96C are increased. For this reason, there existed a problem that the weight of steel cord 90 itself will increase. Further, since the rigidity of the steel cord 90 is increased, it is difficult to bend the rubber product using the rubber crawler having the steel cord 90 and to prevent the joint portion from peeling off. There was also a problem that there was. Furthermore, the filament wound on the bobbin having the same shape is used as a core filament or a sheath filament, and the wound length varies depending on the filament diameter. ) Occurs, and there is a problem that wasteful costs increase.

Japanese Patent Laid-Open No. 11-93087 JP-A-6-240590 JP-A-8-27685 Japanese Patent Laid-Open No. 1-104888 JP-A-9-111679 JP 2001-20188 A

  In the present invention, in consideration of the above fact, in a steel cord in which a plurality of sheath strands are twisted around the core strand, rubber is infiltrated to the core filament surface of the core strand without reducing the cord cutting load. It is an object of the present invention to provide a steel cord for reinforcing rubber products in which the core filament of the core strand is prevented from jumping out of the rubber member.

  The invention according to claim 1 is a steel cord in which a plurality of sheath strands are twisted around a core strand of a two-layer twist composed of a plurality of filaments, and the core strand includes one or a plurality of core strands. Core filament and five sheath filaments twisted around one or more core filaments, and the sheath strand is twisted around one core filament and the core filament. And six sheath filaments combined.

  When the number of core filaments constituting the core strand is plural, it is preferable that the core filaments are twisted together from the viewpoint of ease of manufacture and from the viewpoint of strength. In this case, the steel cord may be manufactured by simultaneously supplying the filament constituting the core strand and the sheath filament constituting the sheath strand, or while supplying the core strand that has been produced in advance. Steel cords may be manufactured by supplying filaments that form sheath strands. In addition, when making the number of the core filaments which comprise a core strand into a plurality, and twisting together, since a twisting process increases one, it is preferable to make the number of a core filament into one from a viewpoint of productivity.

  When the number of sheath filaments constituting the core strand is 4 or less, deviation tends to occur when twisted, and strength reduction tends to occur when subjected to a load.

  It is possible to omit the wrap filament.

  As described above, in the invention according to the first aspect, the number of sheath filaments constituting the core strand is five, which is one less than the conventional one, so that the core strand is not reduced without reducing the cord cutting load. A steel cord capable of infiltrating rubber up to the surface of the core filament is realized. Therefore, a steel cord for reinforcing rubber products that suppresses the jump-out of the core filament is realized.

  According to a second aspect of the present invention, the diameter dk of the core portion constituting the core strand and the diameter ds of the sheath filament constituting the core strand satisfy a relationship of 1.1 × ds ≧ dk ≧ ds. It is characterized by being.

  The core part is composed of one or a plurality of core filaments. When the core part is composed of a plurality of core filaments, the diameter dk of the core part is the same as the diameter of the projected locus in the cord longitudinal direction.

  By satisfying the relationship of dk ≧ ds, it is easy to sufficiently infiltrate the rubber into the gap between the sheath filaments constituting the core strand, and therefore it is easy to sufficiently reach the core. Moreover, by satisfying the relationship of 1.1 × ds ≧ dk, it is possible to prevent the occurrence of bias when the core strand is twisted or the decrease in strength when the load is applied.

  The invention according to claim 3 is characterized in that the twisting direction of the sheath filament constituting the core strand and the twisting direction of the sheath filament constituting the sheath strand are opposite to each other.

  Thereby, since the contact area of a core strand and a sheath strand can be reduced, the rubber penetration property to the core strand surface can be improved.

  Since the present invention is configured as described above, in a steel cord in which a plurality of sheath strands are twisted around the core strand, it is possible to allow rubber to enter the core filament surface of the core strand without reducing the cord cutting load. By doing so, it is possible to realize a steel cord for reinforcing a rubber product in which the core filament of the core strand is prevented from jumping out of the rubber member.

It is a tire width direction sectional view showing that the steel cord of the 1st form is used as a reinforcement member for construction vehicles. FIGS. 2A and 2B are perspective views for each step when manufacturing an elastic crawler using the steel cord of the first form as a reinforcing member. It is sectional drawing which shows the structure of the steel cord of a 1st form. It is sectional drawing which shows the structure of the steel cord of a 2nd form. It is sectional drawing which shows the structure of the conventional steel cord. It is sectional drawing which shows the structure of the conventional steel cord.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described.

[First form]
First, a 1st form is demonstrated. As shown in FIGS. 1 to 3, the steel cord 10 according to the first embodiment includes a reinforcing member such as a belt 14 that constitutes a pneumatic tire 12 (see FIG. 1) for a construction vehicle, and an elastic crawler 16 (FIG. 2). Steel cord used as a reinforcing member. The steel cord 10 includes a single core strand 22 and six sheath strands 26 twisted around the core strand 22.

  As shown in FIG. 3, the core strand 22 includes one core filament 22C and five sheath filaments 22S twisted around the core filament 22C. Each of the sheath strands 26 includes one core filament 26C and six sheath filaments 26S twisted around the core filament 26C.

  As described above, in this embodiment, the sheath filaments 22S constituting the core strand 22 are reduced to 5 pieces, which is one less than the conventional six pieces. The gap is sufficiently secured. Therefore, when manufacturing the pneumatic tire 12 and the elastic crawler 16, when the rubber member is infiltrated into the steel cord 10 from the periphery, the rubber member sufficiently enters between the sheath filaments 22S constituting the core strand 22, A sufficient amount of the rubber member can reach the surface of the core filament 22 </ b> C constituting the core strand 22. Therefore, even if the pneumatic tire 12 or the elastic crawler 16 incorporating the steel cord 10 is used, the core filament 22C can be prevented from popping out.

[Second form]
Next, a 2nd form is demonstrated. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  As shown in FIG. 4, the steel cord 30 according to the second embodiment includes one core strand 32 and six sheath strands 26 twisted around the core strand 32.

  The core portion 32C of the core strand 32 is composed of three core filaments 32C1 to C3 twisted together. Thereby, the surface area of 32 C of core parts can be increased, and the rubber penetration property to 32 C of core parts can further be improved. In this case, the diameter dk (see FIG. 4) of the core portion 32C is the same as the diameter of the projected locus in the cord longitudinal direction of the core portion 32C.

  The embodiments of the present invention have been described with reference to the embodiments. However, these embodiments) are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

[Experimental example]
(1) Steel cord 10 explained in the first embodiment, (2) Steel cord 30 explained in the second embodiment, (3) Steel cord composed of one core strand and four sheath strands, (4 ) Rubber crawlers using conventional steel cords as reinforcing steel cords were manufactured and tested for durability. As test conditions, the rubber crawler was run for 200 hours. Table 1 shows the core strand structure (1) to (4), the filament diameter (the core filament diameter dc of the core strand, the sheath filament ds of the core strand, the diameter dk of the core portion of the core strand), and the test results.

  As the evaluation of the durability test, the number of core filaments protruding from the rubber member of the pneumatic tire, that is, from the front surface or the back surface of the tread portion, and the strong utilization rate were evaluated.

Here, the strong utilization factor U is calculated | required with the following formula | equation, and shows that it is so favorable that a numerical value is large.
U = (breaking strength of steel cord) / (total breaking strength of filaments used)
As can be seen from Table 1, in Examples (1) and (2), the number of core filament jumps can be reduced without reducing the strength utilization rate, that is, without reducing the cutting load. It was.

  In the case of (3), which is a comparative example, the number of core filaments protruding was good, but the strength utilization rate was low. This is probably because the number of sheath filaments constituting the core strand has been reduced excessively.

  In the case of the conventional example (4), the number of core filaments popping out was large and the evaluation was bad. This is probably because the gap between the sheath filaments constituting the core strand is too narrow, and the rubber has not sufficiently reached the core filament constituting the core strand.

DESCRIPTION OF SYMBOLS 10 Steel cord 22 Core strand 22C Core filament 22S Sheath filament 26 Sheath strand 26C Core filament 26S Sheath filament 30 Steel cord 32 Core strand 32C Core part 32C1-C3 Core filament 80 Steel cord 82 Core strand 82C Core filament 82S Sheath filament 86 Sheath strand 86C Core filament 86S Sheath filament 90 Steel cord 92 Core strand 92C Core filament 92S Sheath filament 96 Sheath strand 96C Core filament 96S Sheath filament

Claims (3)

A steel cord in which a plurality of sheath strands are twisted around a core strand of a two-layer twist composed of a plurality of filaments,
The core strand includes one or more core filaments,
5 sheath filaments twisted around one or more core filaments, and
The sheath cord is composed of one core filament and six sheath filaments twisted around the core filament. The diameter dk of the core part that constitutes the core strand, and the diameter ds of the sheath filament that constitutes the core strand,
1.1 × ds ≧ dk ≧ ds
The steel cord according to claim 1, wherein the relationship is satisfied.   The steel cord according to claim 1 or 2, wherein the twist direction of the sheath filament constituting the core strand and the twist direction of the sheath filament constituting the sheath strand are opposite to each other.

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