JPH0741779B2 - Bead wire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bead wire for a tire.

[Problems to be Solved by the Prior Art and Invention] The ends of the cords of the fiber or steel wire forming the carcass, which is a strength member for maintaining the inner pressure of the tire, are wound around and fixed, and the dimension of the inner circumference of the tire is fixed. The bead wire, which is an important tire material for securing the fit with the rim, is (1) a strand bead wire having a rectangular cross section,
It is classified into three types: (2) single wire bead wire having a hexagonal cross section and (3) cable bead wire having a circular cross section.

A quadrangular strand bead wire is a bead wire in which a plurality of steel wires are arranged in parallel and covered with rubber, and the steel wire strips are laminated and wound. A hexagonal cross section single wire bead wire is made of rubber on one steel wire. It is a bead wire that is covered and continuously wound in parallel and in layers to form a bales, and a cable bead wire with a circular cross section has another steel wire on the peripheral surface of an endless metal wire. It is a spirally wound bead wire.

The quadrangular cross-section strand bead wire has the drawback that the cross-sectional shape is easily distorted when it is embedded in a tire carcass and molded and vulcanized, and it could still be used in bias tires, but it becomes inconvenient and not useful in radial tires. Came. A hexagonal bead wire whose cross-sectional shape was difficult to change during molding and vulcanization of the tire was introduced later, but it was useful for some truck tires with a low shape of so-called 15 degree taper, but generally steel wire is With bead wires arranged in parallel, the effective strength used for the finished tire is about 40% of the inherent strength of the wire.
It is a degree.

Ideally, a bead wire that can maintain the same cross-sectional shape and, if possible, has a generally circular cross-section. In particular, a bead wire having a circular cross section is optimal for a tire using a steel cord for a carcass such as an all-steel radial tire. This is the reason why the cable bead wire with a circular cross section appeared.

A circular cross-section having the same cross-sectional shape in the length direction (some cross-sectional shapes such as rectangular cross-sections are not circular)
75% of the material strength of the cable bead wire, which is constructed by closely arranging the high carbon steel wire in spiral winding around the core metal of butt-welding the low or medium carbon steel wire in a ring shape, is useful. Made it possible. This cable bead wire facilitates sliding motion between the cord and the spirally wound high carbon steel wire and between the spirally wound high carbon steel wire and the core metal against displacement of the carcass cord during tire molding vulcanization. , Therefore, it is possible to keep the cross-sectional shape, but the high-carbon steel wire of circular cross section closely wound spirally is closely arranged in line contact with the core metal of circular cross section without rubber coating. As a result, a new triangular void is formed between the spiral winding line and the core metal, and new problems such as rust generation and a reduction in adhesive strength with rubber have arisen due to frictional heat between metals.
Furthermore, there is a demand to make the portion from the bead of the tire to the sidewall thinner, but the overall diameter of the cable bead wire should be the sum of the actual diameters of the core metal and high carbon steel wire to reduce the overall diameter. Could not be obtained, and as a result, it became difficult to thin the portion.

The object of the present invention is to eliminate the defects in the above-mentioned conventional structure, in which a spirally wound high carbon steel wire and a core metal are arranged in surface contact with each other, and the spirally wound high carbon steel is arranged. It is to provide a cable bead wire that can make the wires non-contact with each other.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention has an endless groove having an arcuate cross-section so as to be circumferentially continuous with a predetermined twist angle on the peripheral surface of an annular core metal. Is formed into a spiral shape, and an endless hard steel wire is spirally wound in the concave groove.

[Operation] Therefore, in the present invention, the cored bar and the hard steel wire are in surface contact with each other so that a slip phenomenon does not occur between the cored bar and the hard steel wire, and the structure is hard by the spiral winding configuration in the spirally formed endless groove. The steel wire is restrained integrally with the core metal. Further, a gap can be maintained between the hard steel wires, and friction between the metals is not generated at all. Further, since the hard steel wire is located in the groove, the overall diameter of the bead wire can be reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. Eight low carbon steel wires with 0.695R recessed grooves 10 provided at 45 ° intervals on the outer circumference are formed into an annular shape and butt welded to form a core metal 2.
Are formed. The groove 10 has a lead length of 170.84, a twist angle of 3 °, and is processed by a twist die on the left side of the twist direction.
It is designed so that one turn of the metal core makes eight turns (one turn means one turn of the diameter of the metal core) to form adjacent grooves separated by 45 °. This continuously makes eight rounds and one groove 10 is apparently formed in eight lines at the cross-section position in the drawing. One 1.39φ high-carbon steel spiral winding line 11 as a hard steel wire is closely arranged in the concave groove 10 of the core metal 2, and the concave groove 10 and the outer periphery of the spiral winding line 11 have the same curvature. However, they are in surface contact with each other. A gap 3 is provided between each spiral winding line 11.
In addition, is a tire bead toe, 5 is a bead heel, and 6 is a code.

To explain the winding state of the spiral winding line more easily, the spiral winding line 11 made of high carbon steel starts from one point of the concave groove 10 of the butt weld portion of the core metal 2 as the starting point, and is closely contacted with the concave groove 10 on the left side. Twist around the core metal 2 for 8 turns to reach the butt weld,
While closely contacting the adjacent groove 10, twist leftward to move around the core metal 8
Turn to reach the butt weld. When 64 spiral windings are completed while repeating this winding, one end of the high-carbon steel spiral winding line 11 faces the other end on the same spiral orbit at the butt weld portion, and a conventionally known method (for example, the spiral winding line 11). Both ends are inserted into a connection pipe and both ends are connected with a connection pipe), and the bead wire 1 of the present invention is obtained. The gap 3 is filled with rubber by applying a rubber cover to the outer peripheral surface of the ring body 1 or by applying an adhesive when the tire is molded and vulcanized.

In addition, although the concave groove 10 has one line in the above-described embodiment, it may have a plurality of lines. However, in the case of multiple lines, multiple spiral winding lines are required.

EFFECTS OF THE INVENTION As described in detail above, according to the present invention, the cored bar and the hard steel wire are in close contact with each other in the spirally formed endless groove while being integrated with each other with a predetermined binding force. Therefore, there is no sliding motion due to external load. Therefore, the open gap between the hard steel wires is maintained, and the hard steel wires are adjacent to each other with the rubber layer interposed therebetween. There is no air pocket and there is no concern about metal friction. There was nothing, and it was possible to completely solve the problems such as the generation of rust due to the frictional heat generation of the conventional cable bead wire and the reduction of the adhesive force with rubber. Also, since the hard steel wire is located on the center side of the core metal by the depth of the groove, the overall diameter of the bead wire is reduced to thin the portion from the tire bead and diamond bead to the sidewall. Can contribute to When arranging the hard steel wires with a gap between the hard steel wires, the number or thickness of the hard steel wires can be regulated by the size of the width of the gap, and the range of selection of the strength of the bead wire is widened. This is easily understood.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a bead wire embodying the present invention. 2 ... Core bar, 10 ... Recessed groove, 11 ... Spiral winding line as hard steel wire.

Claims (1)

[Claims] 1. An endless groove (10) having an arcuate cross-section is spirally formed on the peripheral surface of an annular core metal (2) so as to be continuous with a predetermined twist angle, and the groove (10) is formed. A bead wire characterized by spirally winding an endless hard steel wire (11).