Method and device for overtwisting and undertwisting a steel cord
AssigneeNV Bekaert SA
InventorsJohan De Waegenaere, Luc Sabbe, Frans Van Giel
Life of this patent
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Abstract
A steel cord, having steel filaments twisted so as to have a final twist pitch, is manufactured by plastically deforming the steel filaments by overtwisting the steel cord to a twist pitch which is smaller than the final twist pitch, untwisting the steel cord to the final twist pitch, further untwisting the steel cord to a twist pitch which is greater than the final twist pitch, and twisting the steel cord again to the final twist pitch. The first two steps (i.e., overtwisting and untwisting) are done under a first tension and the third and fourth steps (i.e., further untwisting and twisting) are done under a second tension which is lower than half of the first tension.
Claims17
A process of treatment of a steel cord adapted for the reinforcement of rubber products, said steel cord comprising steel filaments which have been twisted to a final twist pitch, said process comprising the steps of:
- (i) plastically deforming the steel filaments by overtwisting the steel cord to a twist pitch which is smaller than the final twist pitch;
- (ii) untwisting the steel cord to the final twist pitch;
- (iii) further untwisting the steel cord to a twist pitch which is greater than the final twist pitch;
- and
- (iv) twisting the steel cord again to the final twist pitch,
- wherein steps (i) and (ii) are done under a first tension and steps (iii) and (iv) are done under a second tension, the second tension being lower than half of the first tension.
An apparatus for carrying out a treatment of a steel cord, the steel cord having a final twist pitch, said apparatus comprising:
- (i) first twisting means for overtwisting said steel cord under a first tension to a twist pitch that is smaller than the final twist pitch;
- (ii) pull-through means for pulling said steel cord through said first twisting means resulting in a second tension which is substantially smaller than said first tension;
- (iii) second twisting means for untwisting said steel cord under said second tension to a twist pitch that is greater than the final twist pitch;
- and
- (iv) final twisting means for twisting said steel cord from the second twisting means to the final twist pitch.
Dependencies are inferred from the claim text.