JPS60154834A - Steel cord - Google Patents

Abstract

PURPOSE:To prevent the decrease in the life of a tire by covering the joint part of steel cords with a shrinkable tube made of a resin having good adhesion to rubber so that the steel cords and the rubber adhere securely over the entire length. CONSTITUTION:Both steel cords 1, 1' to be connected are butt welded and the flash 5 produced by welding is cut off to smooth the surface. A shrinkable tube 6 which is preliminarily passed onto the steel cord on one side is moved to be put onto the welded juncture. A material such as, for example, EVA resin or ethyl acrylate having good adhesion to rubber is preferable as the tube 6 or the tube made of the double structure of which the outside layer 8 consists of a material such as EVA resin, ethyl acrylate, etc. having good adhesion to rubber and the inside layer 7 consists of a material such as polyamide resin having good adhesion to the steel cords is preferable. When the shrinkable tube is heated to shrink, the juncture is securely covered by the tube 6.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to steel cords for reinforcing rubber used in automobile tires and the like.

Conventional technology Steel cord is used for reinforcing the rubber of automobile steel tires, etc., and is usually made by twisting together four thin high-hardness steel wires (2) plated with brass, as shown in Figure 1. A so-called twisted wire, which is made by twisting seven twisted wires together, is used. The center strand (3) is the core, the outer strand (4)
) is called a strand.

Conventionally, when jointing steel cords f++ and f1+, each cord is butted together and welded (5) as shown in Figure 2 (al), and then the °' burr (5) that occurs during welding is smoothed out (file). ) to make the surface smooth and jointed.

C1 Problems to be Solved by the Invention However, in the case of a conventional butt weld joint, if the "burr" is removed with a chisel, the brass plating layer of the steel cord will be scraped off at the welded part A in Figure 2 (1)). As a result, the steel cord and the rubber are not bonded to each other in that part, and as the tire deforms while the car is running, separation occurs between the steel cord and the rubber, which has the disadvantage of reducing the life of the tire.

21 Disclosure of the Invention The steel cord of this invention has a heat shrink tube (
A tube that shrinks when heated (hereinafter referred to as a shrink tube) is attached to improve the adhesion between the steel cord and the rubber over the entire length of the steel cord.

That is, FIG. 3 shows the connection process for the present invention.

As shown in Fig. 3 (ta+), first butt weld the two steel cords f1+, ++) to be connected, and remove the "' burr (5) caused by welding with a key and grinder as shown in Fig. 3 (1)). etc. to make the surface smooth.Next, the third
As shown in Figure (cl), move the shrink tube (6) previously placed through the steel cord on one side to cover the welded connection.

The shrink tube (6) is preferably made of a material that has good adhesion to rubber, such as EVA resin or ethyl acrylate, or the outer layer (8) is made of rubber, such as EVA resin or ethyl acrylate, as shown in the drawing. It is preferable that the inner layer (7) has a double structure made of a material that has good adhesion to the steel cord, such as polyamide resin. Next, heat the shrink tube with a simple device such as a hair dryer to shrink it. Then, as shown in FIG. 3, the connection part is firmly covered with the shrink tube (6). Particularly when double shrink tubing is used, when the shrink tubing shrinks, the inner polyamide layer softens and penetrates between the strands to ensure a secure bond with the steel cord.

When a steel cord with such a connection part is used to reinforce a rubber tire, the steel cord and the rubber will be firmly bonded over the entire length, and the life of the tire will be shortened due to the connection part not being bonded, unlike the conventional steel cord with a connection part. can prevent a decrease in

E, Example: 7 strands of 0.175 mmφ plus plated steel wires
The steel cords that have been twisted together are welded into a joint, and a length of 1 is placed in advance by passing the steel cord through the joint.
The 5 mm outer layer of EVA resin was covered with a polyamide shrink tube (manufactured by Sumitomo Electric Industries, Ltd., trade name: SUMITUBE), and the tube was heated to about 100° C. with a hair dryer to shrink the tube.

This steel cord was embedded in rubber (a specimen made of natural rubber and synthetic rubber) = 7), and after vulcanization at 15:3°C for 25 minutes, a peel test was performed and the adhesion between the rubber and the shrink tube was confirmed. Also, the adhesion between the shrink tube and the steel cord was good.

1. Effects of the Invention Since the joint portion of the steel cord of the present invention is covered with a resin shrink tube that has good adhesion to rubber, the adhesion between the rubber and the steel cord is good over the entire length of the steel cord. This solves the conventional surface problem of welded parts that form unbonded parts with rubber. Furthermore, the work is simple and requires simply covering the joint with a shrinkable tube, making it very effective in practice.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the steel cord, Figure 2 (al,
Figure (1)) is a front view showing the state of the conventional welding connection method. FIG. 3 is a drawing showing the process of forming a joint part of a steel cord according to the present invention, and FIG.
Figure (1)) is a front view with the burrs removed.
Figure 3 (cl is a perspective view of the joint part covered with a shrink tube, Figure 3 (dl is a perspective view of the completed joint part of the present invention) ++1, +1+... steel cord, (2) steel wire , [31, +31-core, +4) , +4+ Strand, (5) Welded part, Ribbon, (6) Shrink tube, (7) Inner layer, (8) Outer layer. Agent Patent attorney 1) Medium Rio

Claims (1)

[Scope of Claims] 1. A steel cord for reinforcing rubber, characterized in that the connecting portion of the steel cord is covered with a shrinkable tube whose surface layer is made of a resin that has good adhesion to rubber.2. The steel cord according to claim 1, characterized in that a double-layer shrink tube is used in which the outer layer is made of a material that has good adhesion to rubber, and the inner layer is made of a material that has good adhesion to steel cord. 3. The steel cord according to claim 1 or 2, characterized in that the outer layer of the shrink tube is made of EVA resin or ethyl acrylate resin, and the inner layer is made of polyamide resin.