US 2001/0012558 A1 · Shape memory cords for reinforcing articles made from elastomeric material

Abstract

Process for the manufacture of a reinforcing fabric for articles made from rubber, such as pneumatic tires, conveyor belts, flexible tubes, and similar, comprising a plurality of metal cords orientated parallel to each other in a single direction and in which each cord comprises metal wires wound spirally around each other, wherein at least one of the wires of the cord consists of a shape memory material. During the phase of incorporation of the cords into the elastomeric material, the shape memory wire tends to recover the shape memorized initially and, by means of the force generated during this recovery, transmits by friction to the surrounding wires forces tending to shorten the pitch of the cord with spacing of each wire from the next, resulting in good penetration of elastomeric material between the wires. The closure of the cord is maintained in the subsequent heat cycles, owing to the memory degradation characteristics imparted to the wire. The invention is particularly suitable for fabrics forming belt layers and casing plies in pneumatic tires.

Claims26

Dependent claims

Metal cord for reinforcing articles made from elastomeric material, comprising a plurality of metal wires wound spirally around each other, at least one of which is formed from a shape memory material, has capacities of recovering a previously memorized shape, and is deformed from the said memorized shape, the said cord being characterized in that the said shape memory wire has the said recovery capacities substantially active in a first heat cycle and degraded to at least a significant predetermined extent after the said first heat cycle.

Pneumatic tyre for vehicle wheels, comprising a plurality of reinforcing cords, each formed by metal wires wound spirally around each other, at least one of which is formed from a shape memory material, has the capacity of recovering a previously memorized shape, and is deformed from the said memorized shape, the said tyre being characterized in that the said shape memory wire has the said recovery capacities substantially active in a first heat cycle and degraded to at least a significant predetermined extent after the said first heat cycle.

Rubberized fabric for reinforcing articles made from elastomeric material, comprising a plurality of cords incorporated in the elastomeric material of the said fabric and disposed so that they are coplanar with, parallel to and adjacent to each other in the same direction, each cord being formed by a plurality of metal wires wound together spirally, at least one of which is formed from a shape memory material, has capacities of recovering a previously memorized shape, and is deformed from the said memorized shape, the said fabric being characterized in that the said shape memory wire has the said recovery capacities substantially active in a first heat cycle and degraded to at least a significant predetermined extent after the said first heat cycle.

Process for the manufacture of a reinforcing rubberized fabric for articles made from elastomeric material, such as pneumatic tyres, conveyor belts, flexible tubes, and similar, comprising a plurality of cords orientated parallel to each other in the same direction and incorporated in the said elastomeric material, characterized in that it comprises the phases of:

a) preparing a plurality of metal cords to be sent to a fabric rubberizing device, each cord comprising a plurality of single metal wires wound spirally around each other, at least one of the said wires in at least one of the said cords being formed from a shape memory material, with the said shape recoverable by the action of a suitable heat cycle, wherein the said wire, at ambient temperature, has:
the memory of a different shape, with a length l0 which is less than the length l1 of the wire at ancient temperature, memorized at a temperature As which is greater than the ambient temperature T0;
a pseudo-plastic elongation sea eliminable by the shape memory effect, and having a value of between 0.2% and 8% of the length of the said memorized shape;
an elongation εtot having a value of at least 85% of the said value εmax;
a decrease in the residual eliminable pseudo-plastic elongation ε* after a first heat cycle carried out at a temperature T1>As, this decrease being at least 40% of the value of the said pseudo-plastic elongation εmax.
b) feeding the said cords, coplanar with and parallel to each other, to the said rubberizing device for the incorporation of the said cords in the said layer of elastomeric material,
c) carrying out the said incorporation at a temperature T1>T0 such that the said shape memorized in the wire is recovered, with recovery of the said recoverable pseudo-plastic elongation εmax, in such a way that the reconversion force produced by the said shape memory wire during the said recovery exerts on the surrounding wires actions of spacing between each of the said wires and the next, and penetration of elastomeric material into the cord which is in a substantially open configuration,
d) extracting the rubberized fabric from the said rubberizing device, in the form of a continuous strip, with a pull sufficient to restore the pseudo-plastic elongation εtot and the original configuration of the said cords, the fabric being cooled progressively to ambient temperature.

5 more elements

Dependencies are inferred from the claim text.

Shape memory cords for reinforcing articles made from elastomeric material

Life of this patent

Shape memory cords for reinforcing articles made from elastomeric material

Life of this patent

Abstract

Claims26