Metal wire coated with a layer of metal material intended to reinforce elastomeric materials and methods for producing the same

Abstract

A metal wire for reinforcing an elastomeric material includes a metal core and a metal coating layer. The core includes a predetermined initial diameter. A method for producing the wire includes submitting the core to at least one surface treatment, thermally treating the core, depositing the coating layer on the core, and drawing the metal-coated metal core. The at least one surface treatment predisposes a surface of the core to being coated with the coating layer. The coating layer is deposited on the core to a predetermined initial thickness using a plasma deposition technique. The metal-coated metal core is drawn until the core includes a final diameter smaller than the predetermined initial diameter and the coating layer includes a final thickness smaller than the predetermined initial thickness. A metal cord for reinforcing an elastomeric material and a method for producing the metal cord are also disclosed.

Description

FIELD OF THE INVENTION [0001] The present invention refers to a method for producing a metal wire intended to reinforce elastomeric materials, such as for example semi-finished products intended for the manufacture of tires, tubes, conveyor belts, transmission belts and cables. [0002] In particular, the present invention refers to a metal wire of the type comprising a metal core and a metal coating layer. [0003] In the present description and in the following claims, the term “metal” is used to indicate both a single metal and a metal alloy. [0004] The present invention also refers to a metal wire intended to reinforce elastomeric materials, of the type comprising a metal core and a metal coating layer, as well as to a metal cord comprising a plurality of such metal wires and to a method for producing the same. PRIOR ART [0005] Methods for producing metal wires comprising a metal core and a metal coating layer and intended to reinforce elastomeric materials, such as for example semi...

AI Technical Summary

Benefits of technology

[0016] The Applicant has perceived the necessity of providing a method for producing a metal wire intended to reinforce elastomeric materials, of the type comprising a metal core and a metal coating layer, which allows to obtain a wire having suitable mechanical strength in view of the incorporation of the wire into elastomeric materials to be reinforced and comprising a coating layer of high quality, in particular with reference to the uniformity and homogeneity thereof, and improved corrosion resistance, with a positive effect upon the adhesion of the wire to elastomeric materials.

Problems solved by technology

Conventional methods of such type, although substantially suitable for the purpose, nevertheless have a series of drawbacks which have not been overcome yet, such as the excessive number of steps, the excessive duration of the above-mentioned diffusion step and the reduction of mechanical resistance of the wire following such a diffusion step.

Furthermore, in the brass coating layer there are undesired gradients of concentration of copper in the radial direction and in the axial direction of the wire, as well as a variability of the amount of brass both in the axial direction and in the radial direction of the wire.

The presence of β brass, particularly when in a concentration of more than 10% by weight, makes the drawing step extremely difficult and results in an excessive wear of the drawing dies, as well as the risk that there are areas of wire not completely coated and / or containing unacceptable amounts (in the order of about 50 mg / m2) of impurities, such as oxides deriving not only from the acid used in the above-mentioned picking step, but also from the oxides present in the coppering bath and from those present in the lubricant used in the drawing step.

However, the metal film is so thin (from some Å to 0.4 μm) that there is the risk that more or less large areas of the surface of the core are not perfectly coated or that surface areas, although substantially coated, present surface defects, thus not ensuring a suitable corrosion resistance of the wire.

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