JP2001181989A - Twistless steel cord and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twistless steel cord having an oval cross section comprising at least 8 element wires capable of holding their reinforcing strengths while reducing producing costs. SOLUTION: This twistless steel cord having an oval cross section is obtained by bundling at least eight element wires 1 into a circle and then loosely winding a wrapping wire 2 around the element wires with a margin length and then pressing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord for reinforcing rubber products such as tires, and more particularly to a non-twisted steel cord made of eight or more strands, while ensuring the reinforcement strength while reducing the production cost. Is what you can do.

[0002]

2. Description of the Related Art There are various types of steel cords for reinforcing rubber products such as tires, which are roughly classified into non-twisted steel cords and twisted steel cords. The non-twisted type does not perform twisting, so the production cost of steel cord is low, while the twisted type requires twisting, so the manufacturing cost is high, but the non-twisted type is also ,
Twisted types also have excellent characteristics. There are two types of non-twisted steel cord: a flat type in which the wires are arranged in a plane and the wrapping wires are tightly wound around them, and a round type in which the wires are bundled and the wrapping wires are tightly wound around them. , Round types are also classified into those in which the strand is typed and those in which the type is not typed. As for the round type, there are those in which the strands are arranged concentrically in a plurality of layers. In this case, there are various combinations of the number of strands in each layer, and each layer has different characteristics depending on the combination of the number of strands in each layer. . In addition, twisted steel cords include those in which multiple strands are concentrically twisted in multiple layers, multiple layers are twisted multiple times, and those in which multiple layers are twisted at once, with a round cross section And an elliptical shape obtained by flattening this. In order to improve the penetration of the rubber material into the steel cord during calendering, the twisted wire is subjected to molding, and a gap for introducing rubber is created between the twisted wires. Since the penetration of rubber into the inside of the steel cord has a significant effect on the durability of the steel cord, the strands of each layer should be used to improve the penetration of this rubber material. Various combinations have been devised in connection with the wire diameter of the wire, the flatness of the steel cord, and the like, and the combination of the number of wires and the size of the shaping of the wire have been devised, and various types have been put into practical use. The twisted type has various characteristics of the steel cord such as strength and flexibility depending on the combination of the number of strands in each layer. Japanese Patent Application Laid-Open No. 6-10281 and Patent No. 2 are examples of twisted steel cords.
No. 920110. On the other hand, examples of a non-twist type steel cord include JP-A-8-120578, JP-B-7-42667, JP-A-7-82679, and JP-A-7-304307. By the way, 1
FIG. 6 shows a wire arrangement of a collectively twisted steel cord composed of two strands, and FIG. 7 shows a wire arrangement of a collectively twisted steel cord composed of 19 strands. FIG. 8 shows an arrangement of two twisted steel cords of two core strands and seven side strands, and three strands of five, nine, and fifteen layers. The strand arrangement of the twisted steel cord is shown in FIG. Further, FIG. 10 shows a strand arrangement and a wrapping structure of three strands of a non-twisted flat steel cord, and FIG. 11A shows a strand arrangement of five strands of a non-twisted round steel cord. FIG. 11B shows an arrangement of three non-twisted triangular steel cords, and FIG. 11B shows an arrangement of 12 non-twisted polygonal steel cords. Each of them is shown in FIG.

[0003]

SUMMARY OF THE INVENTION A non-twisted one is obtained by arranging a plurality of wires flat and wrapping them tightly with a wrapping wire, or by bundling a plurality of wires into a circle, a triangle or a polygon. Tightly wrapped, Tokuho 6
As described in JP-A-63187, it has already been realized, but when a plurality of strands are arranged in a plane, the thickness of the steel cord is small, so that a calender sheet (reinforced with a steel cord) is used. This is suitable for making the rubber sheet thinner, but has the disadvantage that the number of strands of the steel cord per unit width of the calender sheet is small, and thus the reinforcing strength is low. On the other hand, when the strands are bundled in a circular or polygonal shape, the reinforcement strength is high because the number of strands per unit width of the calendar sheet is large, but the calender sheet is thick because the steel cord is thick. However, there is a disadvantage in that the thickness of the steel cord becomes unnecessarily thick, and there is still a problem in the penetration of rubber into the steel cord. From the above, it is expected from the above that it is desirable for the reinforcing strength and calender sheet thickness to be intermediate between the untwisted flat type and the round type, however, the untwisted steel cord of such a structure is realized. It has not been.
Therefore, an object of the present invention is to realize a non-twisted steel cord having an elliptical cross section.

[0004]

Means taken to solve the above problems have been devised to solve the above problems, and the structure of the non-twisted steel cord is as follows. Eight or more strands are bundled in a circle, a wrapping strand is loosely wound around it with a marginal length, and this is pressed to form an elliptical cross section.

[0005]

When eight or more strands are bundled round, the cross-sectional structure becomes a multilayer structure. When the wrapping wire is loosely wound around the wire with a margin, there is play between the wires. When this is pressed, the round bundle of strands is easily crushed and spread laterally by the margin of the wrapping strand, and the strands are in a state of being overlapped in two or three layers. On the other hand, the winding of the wrapping wire is deformed into an elliptical shape, and the eight wire bundles are wrapped in an elliptical shape. Accordingly, a wrapped, untwisted steel cord having an elliptical cross section is formed. The winding of the wrapping element wire of the above-mentioned elliptical steel cord is crushed by pressure processing to form an elliptical shape, and is not tightly wound into an elliptical shape, so the distance between the strands is still relatively large. Loose, leaving gaps between wires. Therefore, the rubber material enters the steel cord relatively smoothly. Therefore, the penetration of the rubber material is good, and sufficient durability is secured.

[0006]

[Embodiment 1] Embodiment 1 is that the wires in the above-mentioned solving means are preliminarily shaped and bundled in a circle.

[0007]

According to the present invention, since the strands are molded, the gaps between the strands after being pressed and flattened are almost uniformly secured.

[0008]

[Embodiment 2] Embodiment 2 is an embodiment of the above solution.
The flatness of the flat shape is 30 to 50%. The flattening ratio is a / b × 100 where b is the width between the outermost wires in FIG. 1 and a is the height between the outermost wires.

[0009]

A non-twisted steel cord having eight or more strands has the most desirable characteristics as a comprehensive evaluation of both the reinforcing strength and the calender sheet thickness.

[0010]

Next, an embodiment will be described with reference to FIGS.

Embodiment 1 Embodiment 1 shown in FIG. 2 is a non-twisted steel cord having eight strands, all of which have a wire diameter of 0.25 mm and are molded at a molding ratio of 140%. Things. The eight strands 1 are aligned in a round bundle, loosely wrapped with a lapping strand 2 having a wire diameter of 0.20 mm at a pitch of 5 mm, and pressed to flatten (flattening rate 49).
%). At this time, the wrapping length of the wrapping element wire 2 is 5 mm per pitch, which is about 1.05 times as long as dense wrapping, and wrapping is performed with a margin. In the case of the first embodiment, the element wire has a two-layer structure of three upper layers and five lower layers.

[Embodiment 2] Embodiment 2 shown in FIG. 3 is a non-twisted steel cord having ten strands, all of the strands 31 having a wire diameter of 0.25 mm and being molded at a molding ratio of 140%. Things. Ten wires 31 are aligned in a round bundle, and a wrapping wire 32 having a wire diameter of 0.20 mm has a pitch of 5
mm, and this was pressed and flattened (flattening rate 43%). At this time, the wrapping length of the wrapping wire 32 is 5 mm per pitch, which is about 1.05 times longer than that in the case of dense wrapping, and wrapping is performed with a margin.

[Embodiment 3] Embodiment 3 shown in FIG. 4 is a non-twisted steel cord having 15 strands, all of the strands 41 having a wire diameter of 0.25 mm and being molded at a molding ratio of 140%. Things. Fifteen strands 41 are aligned in a round bundle, and a wrapping strand 42 having a wire diameter of 0.20 mm is used to form a pitch 5
mm and lapping (flattening rate 36%) by pressing. At this time, the wrapping length of the wrapping wire 42 is 5 mm per pitch, which is about 1.1 times longer than the case of dense wrapping, and wrapping is performed with a margin.

[Embodiment 4] Embodiment 4 shown in FIG. 5 is a non-twisted steel cord having 20 strands, all of the strands 51 having a wire diameter of 0.25 mm, and having a mold ratio of 140%. Things. Twenty strands 51 are aligned in a round bundle, and a wrapping strand 52 having a wire diameter of 0.20 mm has a pitch of 5
mm and lapping by flattening (flattening rate 33%). At this time, the wrapping length of the wrapping element wire 52 is 5 mm per pitch, which is about 1.25 times longer than that in the case of dense wrapping, and wrapping is performed with a margin. In each of the above embodiments, since all the wires are pre-molded, a gap between the wires is secured in an elliptical flattened state, and a rubber material is inserted into the steel cord from the gap during calendering. Penetrates, the penetration of the rubber material is good. The specifications and test results of the above embodiment are as shown in [Table 1]. Incidentally, the specifications and test results of the conventional example are also shown for comparison.

[0015]

[Table 1] Flatness: minor axis / major axis × 100 Strength reduction rate: total strength of strands before stranding / strength of cord Stranding cost: index with 3 + 9 + 15 × 0.22 being 100

[0016]

The steel cord according to the present invention is a non-twisted steel cord having eight or more strands. Therefore, the steel cord has the general characteristics of a non-twisted steel cord, that is, low cost and a reduction in cord strength. Since the cord height can be suppressed while securing the strength of the strands, the number of cords used per unit width of the calendar sheet can be reduced, and the unnecessary increase in the thickness of the calendar sheet is suppressed as much as possible. Can be. Therefore, a thin calendar sheet that is sufficiently reinforced can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a non-twisted steel cord.

FIG. 2 is a sectional view of a steel cord according to the first embodiment.

FIG. 3 is a sectional view of a steel cord according to a second embodiment.

FIG. 4 is a sectional view of a steel cord according to a third embodiment.

FIG. 5 is a sectional view of a steel cord according to a fourth embodiment.

FIG. 6 is a cross-sectional view of a conventional twisted steel cord by batch twisting.

FIG. 7 is a sectional view of another conventional twisted steel cord by batch twisting.

FIG. 8 is a sectional view of a conventional twisted steel cord by multi-layer twisting.

FIG. 9 is a sectional view of another conventional twisted steel cord by multi-layer twisting.

FIG. 10 is a plan view of a conventional flat non-twisted steel cord.

11A is a cross-sectional view of a conventional round non-twisted steel cord, FIG. 11B is a cross-sectional view of a conventional triangular non-twisted steel cord, and FIG. 11C is a cross-sectional view of a conventional polygonal non-twisted steel cord. FIG.

[Explanation of symbols]

 1, 31, 41, 51 ... strand 2, 32, 42, 52 ... wrapping strand a ... height between outermost strands b ... width between outermost strands

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[Procedure amendment]

[Submission date] December 27, 1999 (1999.12.
27)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

[0015] Flatness: minor axis / major axis × 100 Strength reduction rate: total strength of strands before twisting / cord strength Stranding cost: index with 3 + 9 + 15 × 0.22 being 100

Claims (5)

[Claims] 1. A non-twisted steel cord in which eight or more strands are bundled in a circular shape, a wrapping strand is loosely wound around the strand with a marginal length, and this is pressed to form an elliptical cross section. 2. The non-twisted steel cord according to claim 1, wherein the wire is pre-molded, bundled in a circle, and the wrapping wire is loosely wound. 3. The flattening rate of the elliptical cross section is 30 to 50%.
The non-twisted steel cord according to claim 1 or 2, wherein 4. The non-twisted steel cord according to claim 1, wherein the steel cord having an elliptical cross section has two or three layers in a short diameter direction at a central portion in a longitudinal direction. 5. Manufacturing of a non-twisted steel cord in which eight or more strands are bundled in a circular shape, and a wrapping strand is loosely wound with a marginal length around the strands, and is then pressed and flattened to have an elliptical cross section. Method.