Metal cord and process for manufacturing a metal cord
AssigneePirelli Tyre S.p.A.
InventorsFabrizio Cristofani, Luca Cirilli
Life of this patent
Estimating the term…
Abstract
A metal cord includes at least one preformed elementary metal wire. The metal cord has an elongation at break, measured on the bare cord, higher than or equal to 3%, preferably 4% to 6%; an elongation at break, measured on the rubberized and vulcanized cord, which differs in an amount not higher than or equal to 15%, preferably 2% to 10% with respect to the elongation at break measured on the bare cord; a part load elongation, measured on the bare cord, higher than or equal to 0.4%, preferably 0.5% to 1.5%; a part load elongation, measured on the rubberized and vulcanized cord, which differs in an amount not higher than or equal to 15%, preferably 0.5% to 10%, with respect to the part load elongation measured on the bare cord.
Claims29
A metal cord comprising at least one preformed elementary metal wire, comprising:
- an elongation at break, measured on a bare cord, higher than or equal to 3%;
- an elongation at break, measured on a rubberized and vulcanized cord, which differs in an amount not higher than or equal to 15% with respect to the elongation at break measured on the bare cord;
- a part load elongation, measured on the bare cord, higher than or equal to 0.4%;
- and
- a part load elongation, measured on the rubberized and vulcanized cord, which differs in an amount not higher than or equal to 15% with respect to the part load elongation measured on the bare cord.
A process for manufacturing a metal cord comprising the steps of:
- (a) permanently deforming at least one elementary metal wire according to a substantially sinusoidal deformation lying in a plane obtaining a preformed metal wire;
- (b) permanently deforming the preformed elementary metal wire obtained in step (a) in a helicolidal way along its longitudinal axis, so obtaining a double-preformed elementary metal wire;
- and
- (c) stranding the at least one double-preformed elementary metal wire obtained in step (b) with at least one additional elementary metal wire by twisting, thus obtaining the metal cord.
An apparatus for manufacturing a metal cord comprising:
- at least one rotor engaged to a supporting structure and rotatable according to a rotation axis;
- feeding devices to feed a plurality of elementary metal wires from respective feeding spools, said elementary metal wires being driven onto the rotor according to a stranding path with end sections coinciding with a rotation axis of said rotor and with a central section spaced from said rotation axis;
- at least one first preforming device, positioned in a section upstream with respect to the first end section of the stranding path, operating on one of said elementary metal wires, said at least one first preforming devices providing said elementary metal wire with a substantially sinusoidal permanent deformation;
- and
- at least one second preforming device, positioned after said first preforming device in a section upstream with respect to the first end section of the stranding path, operating on the same elementary metal wire, said at least one second preforming device providing said elementary metal wire with a substantially helicoidal permanent deformation along its longitudinal axis.
Dependencies are inferred from the claim text.