Method for producing layered steel cord
Provided is a method for producing a layered steel cord and belongs to the technical field of steel cord production. The method includes: prestressing some of steel filaments in each layer other than a core wire to obtain prestressed steel filaments; and arranging conventional steel filaments and the prestressed steel filaments in each layer alternately in a stranding machine and performing twisting to obtain the layered steel cord. In the prior art, during the twisting process of a steel cord, due to the residual stress of a steel filament itself and the fluctuation of the tension during the unwinding process, a layered steel cord has a problem of a large interlayer residual stress. The methods controls the stress distribution state of a twisted layered steel cord by prestressing steel filaments, and avoids unflatness of a cord fabric during calendering and warping during cutting in the production process of tires.
1 . A method for producing a layered steel cord, comprising:
prestressing some of steel filaments in each layer other than a core wire to obtain prestressed steel filaments; and
arranging steel filaments without prestressing and the prestressed steel filaments in each layer alternately in a stranding machine, and twisting the steel filaments around a core wire to obtain the layered steel cord, wherein
performing the prestressing on a filament production water tank to prestress some of the steel filaments.
2 . The method for producing a layered steel cord according to claim 1 , wherein, performing the prestressing by a prestressing device, wherein the prestressing device comprises a straightener and an overtwister.
3 . The method for producing a layered steel cord according to claim 1 , wherein, performing the prestressing before a twisting point of the stranding machine to prestress the steel filaments.
4 . The method for producing a layered steel cord according to claim 3 , wherein, a number of the prestressed steel filaments is at least one.
5 . The method for producing a layered steel cord according to claim 3 , wherein,
during the twisting process, controlling an interlayer stress state,
wherein the interlayer stress state is characterized by a sum of absolute values of the stress states of all layers, and the stress state of each layer is characterized by an algebraic sum of a residual torsion of the steel filaments in the layer divided by a number of steel filaments in the layer.
6 . The method for producing a layered steel cord according to claim 5 , wherein, controlling a number of turns of interlayer twist to be 0-1.5 turns, preferably 0-1 turn.
7 . A layered steel cord, being produced by the production method according to claim 1 , wherein the layered steel cord comprises the core wire, the steel filaments without prestressing and the prestressed steel filaments; the core wire is located in a center, and the steel filaments without prestressing and the prestressed steel filaments are arranged alternately around the core wire.
8 . The layered steel cord according to claim 7 , wherein, performing the prestressing by a prestressing device, wherein the prestressing device comprises a straightener and an overtwister.
9 . The layered steel cord according to claim 7 , wherein, performing the prestressing before a twisting point of the stranding machine to prestress the steel filaments.
10 . The layered steel cord according to claim 9 , wherein, a number of the prestressed steel filaments is at least one.
11 . The layered steel cord according to claim 9 , wherein,
during the twisting process, controlling an interlayer stress state,
wherein the interlayer stress state is characterized by a sum of absolute values of the stress states of all layers, and the stress state of each layer is characterized by an algebraic sum of a residual torsion of the steel filaments in the layer divided by a number of steel filaments in the layer.
12 . The layered steel cord according to claim 11 , wherein controlling a number of turns of interlayer twist to be 0-1.5 turns, preferably 0-1 turn.