JPS63159588A - Production of steel cord - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a steel cord for reinforcing rubber used as a rubber reinforcing material for tires, belts, etc., and particularly relates to a method for manufacturing a steel cord having a multi-strand structure. It is something.

(Prior art and its problems) In general, this kind of steel cord is constructed by twisting i[ to form a strand, and twisting a plurality of the strands to form a steel cord. As shown in Figures 3 (p) and (b), 7 strands of 4t having the same wire diameter are twisted together to form a strand 5. 1. 3 to 7 strands of 5t are twisted together to form a steel cord 6. . Further, as shown in FIG. 3(C), a cord 7 of a different structure may be used especially as the core of the hood.

A plurality of steel cords 6 having the above-mentioned structure are arranged in parallel and covered with a rubber material, and are used as a rubber reinforcing material for tires, belts, etc. When producing these multi-stranded steel hoods, both the strand twisting process and the hood twisting process have conventionally been produced using a Chepra type wire twisting machine.

However, recently there has been a strong demand from steel cord users to improve quality and reduce costs. ) is being considered for production.

The present inventor also tested the production of multi-stranded steel cord using the puncher twisting machine described above, and found that the strand production process was the same as that for single-layer twisting, so it could be produced without any problems. However, during the cord manufacturing process, the core filament of the strand was often exposed to the surface, resulting in poor twisting and filament breakage, resulting in a decline in both quality and production efficiency, which resulted in the manufacture of steel cords. It was very difficult to do so.

The biggest possible reason for this is that the puncher twisting machine is a twist type twister, so when twisting a multi-strand cord, not only each strand is twisted together, but each strand itself is also twisted. This is because the strand is twisted, that is, the twist of the strand is added by two steps: a strand twisting step and a cord twisting step.

This thing is puncher twisting mtf! When manufacturing multi-stranded cords using At, production efficiency is greatly improved, but on the other hand, the above-mentioned problem occurs, making it difficult to manufacture multi-stranded cords with a puncher twisting machine, and in practice. There was one reason why it wasn't used.

(Means for Solving the Problems) As a result of various experiments, the present inventor found that the phenomenon in which the core filament rises to the surface is due to the fact that the strands are twisted in two steps, and the twist rate of the side filaments ( (σ3. p is the twist pitch, d is the effective diameter of the side filaments) It was found that this varies between crab species and is due to an imbalance between the length of the core filament and the length of the filament.

The present invention was made in order to solve the above problems based on the above findings, and it includes a plurality of strands having a cored structure.
In a manufacturing method in which a steel cord with a single multi-strand structure is manufactured by twisting the strand in the same direction as the twisting direction of the strand, g, filament length 11, and core filament length jo are determined per unit length of the strand during strand manufacturing. Then, by twisting multiple strands together using a puncher twisting machine in the same direction as the strand twisting direction, we can produce a steel with excellent quality and production efficiency. A method for manufacturing a cord is provided. However, here, PO is the twist pitch of the strand after being twisted into the steel cord, and dε
is the effective diameter of one filament of the strand after being twisted into a steel cord.

The filament diameter used in these steel cords is 0
．． It has a diameter of 15 mm to 0.401 mm and is usually coated with plus plating on the surface to improve adhesion to rubber.

The appropriate range is that the twisting strength of the strands is from 2:5 to 1,000 yen, and the twisting pitch of the cord is from about 5 am to 20 W.

(Example) Embodiments of the present invention will be described below based on the drawings.

As shown in Fig. 1, the wire diameter R1 is 7mm,
Puncher twisting: Sm with a machine, twisted together at a pitch of 6u to form strand 2. At this time, steel! Twist the strands a little more strongly so that the strands have a value tLO9 of 214°. The cross section of the strand 2 at this time had a structure with gaps C' between the strands, as shown in the figure.

Next, 3 of strand 2 of this lX7xO, 20φ configuration
The book is twisted 8 times using a single puncher twisting machine and twisted at a twisting pitch of 6 to form a neatly twisted steel cord 3 with uniform tightness as shown in Fig. 2.

(Function) Since the present invention has the above configuration, when manufacturing one strand, the length of the side filaments is used in excess of the length of the core filament (Strand twisting pitch in the wire strand process) This is where they were being twisted. Then, a plurality of these strands are twisted together to create a cord pitch.

When this hood is finished, there is almost no imbalance between the lengths of the core filament and side filaments of the strand, making it possible to produce a neatly twisted steel cord.

Here, it has been experimentally confirmed that during strand manufacturing, an increase or decrease of about 5% in the right 4 degrees is allowable. The test results are shown below.

The value for the selvage is the average value actually measured for 1 m of strand after strand production.

Configuration 3 x 7 x O, 2φ Code pitch 6m
Strand Bifuchi 6 Maro s7s Twisted Po=:IQ da=Q, 4 (Reference) Composition 4X7X0.3 Food Pitch 8 Kaku Strand Pitch 4 rin 8/F3 Twisted Po=4. Q
d@=Q, 5 (reference) 11/! . When the value of is below the lower limit, a phenomenon in which the core filament of the strand jumps out during cord twisting is observed, and when it is above the upper limit, gaps are observed between the side filaments in the strand.

(Effects of the Invention) In the steel cord manufacturing method according to the present invention, the production efficiency can be improved by about twice in the strand twisting process compared to the case where steel cords are twisted using a Chepra type twisting machine. However, in the example above, when twisting steel cords with a cheapura, the pitch of the struts is 3 m from the beginning.
This is because I have to finish it. The efficiency can be further increased by using a double twist type puncher twisting machine. In addition, the filament breakage during the production of steel cord is about one time on average when the cord is twisted using a puncher twisting machine using the normal twisting method, but with the method of the present invention, there is no breakage of the filament. Ta. There were 14 bad twists, but there were none. As described above, it has very excellent effects in manufacturing multi-twisted hoods.

[Brief explanation of the drawing]

FIG. 1 is a cut end view showing one embodiment of the strand used in the steel cord of the present invention, and FIG. 2 is a cut end view showing one embodiment of the steel cord obtained by the method of manufacturing the steel cord of the present invention. End view 1 Figure 3 (a), (=),'
(c) is a cut end view showing a conventional i4 steel cord. l...-line, 2.5...strand, 3.6...
Steel cord, 4... bare wire, 7... cord. 1st Figure 2 Figure 3 (c)

Claims (1)

[Claims] In a manufacturing method for manufacturing a steel cord having a multi-strand structure by twisting a plurality of strands having a cored structure in the same direction as the twisting direction of the strands, when manufacturing the strands, the strand unit Per length, the ratio of side filament length l_1 to core filament length l_0 is {√[Po^2+(xdε)^2]/Po}×0.95
≦l_1/l_0≦{√[Po^2+(xdε)^2]
/Po}×1.05 (where Po: twist pitch of the strand after being twisted into the steel cord; dε: effective diameter of the side filament of the strand after being twisted into the steel cord); multiple strands of this,
A steel cord construction method characterized by twisting the strands together using a buncher twisting machine in the same direction as the twisting direction of the strands.