A steel cord includes one or more core filaments, and outer sheath filaments provided so as to surround the one or more core filaments. The one or more core filaments and the outer sheath filaments have an identical wire diameter and an identical twist pitch. At least one of the one or more core filaments is a waved filament having a bent portion and a non-bent portion along a longitudinal direction.

The invention provides a steel cord for rubber reinforcement. The steel cord comprises a core strand and at least three outer strands twisted around the core strand, the core strand comprises at least one first core filament and multiple first outer filaments twisted around the first core filament, each outer strand comprises a number of second filaments, at least one of multiple first outer filaments is preformed prior to being twisted into the core strand, and at least one of second steel filaments is straight prior to being twisted to form each outer strand. The steel cord has improved performance on core filament migration.

The invention provides a steel cord for rubber reinforcement. The steel cord comprises a core strand and at least three outer strands twisted around the core strand, the core strand comprises at least one first core filament and multiple first outer filaments twisted around the first core filament, each outer strand comprises a number of second filaments, at least one of multiple first outer filaments is preformed prior to being twisted into the core strand, and at least one of second steel filaments is straight prior to being twisted to form each outer strand. The steel cord has improved performance on core filament migration.

The invention provides a steel cord for rubber reinforcement. The steel cord comprises a core strand and at least three outer strands twisted around the core strand, the core strand comprises at least one first core filament and multiple first outer filaments twisted around the first core filament, each outer strand comprises a number of second filaments, at least one of multiple first outer filaments is preformed prior to being twisted into the core strand, and at least one of second steel filaments is straight prior to being twisted to form each outer strand. The steel cord has improved performance on core filament migration.

The invention provides a steel cord for rubber reinforcement. The steel cord comprises a core strand and at least three outer strands twisted around the core strand, the core strand comprises at least one first core filament and multiple first outer filaments twisted around the first core filament, each outer strand comprises a number of second filaments, at least one of multiple first outer filaments is preformed prior to being twisted into the core strand, and at least one of second steel filaments is straight prior to being twisted to form each outer strand. The steel cord has improved performance on core filament migration.

A manipulation rope having an excellent torque transmittability is provided. A manipulation rope 2 is a rope 2 that is advantageously used as a manipulation rope for a medical instrument, and includes a side wire 6 or a side strand which is an outermost layer, the side wire 6 or the side strand having a spiral shape in which a flatness that is an aspect ratio obtained by a major axis being divided by a minor axis is greater than 1.00 and not greater than 1.10. An elongation of the rope at a time when a tensile load that is 1.0% of a breaking load is applied, is preferably not less than 0.04% and preferably not greater than 0.10%.

A manipulation rope having an excellent torque transmittability is provided. A manipulation rope is a rope that is advantageously used as a manipulation rope for a medical instrument, and includes a side wire or a side strand which is an outermost layer, the side wire or the side strand having a forming rate that is greater than 100% and not greater than 110%. The side wire or the side strand having been formed has a spiral shape in which a flatness that is an aspect ratio obtained by a major axis being divided by a minor axis is preferably not less than 1.01 and preferably not greater than 1.10. Further, an elongation of the rope at a time when a tensile load that is 1.0% of a breaking load is applied, is preferably not less than 0.04% and preferably not greater than 0.10%.

An apparatus for producing an assembly of filamentary elements that are wound together in a helix includes a twisting device, a preforming device, and an assembling device. The twisting device is structured to twist at least first and second filamentary elements individually, such that each filamentary element is twisted separately from another filamentary element, to produce at least first and second twisted filamentary elements. The preforming device, which is arranged downstream of the twisting device, is structured to preform each of the twisted filamentary elements individually into separate preformed helixes, to produce at least first and second preformed helixes. The assembling device, which is arranged downstream of the preforming device, is structured to assemble the preformed helixes into an assembly.

[Object] A hollow stranded wire line, for manipulation, having an excellent torque transmittability is provided. [Solution] A hollow stranded wire line 2 for manipulation is a hollow stranded wire line 2 that is advantageously used as a stranded wire line for manipulation in a medical instrument, and a side wire 4 or a side strand which is an outermost layer has a forming rate that is greater than 100% and not greater than 110%. The side wire 4 or the side strand having been formed has a spiral shape in which a flatness that is an aspect ratio obtained by a major axis being divided by a minor axis is preferably not less than 1.01 and preferably not greater than 1.10.

A facility for manufacturing at least first and second assemblies of M1 filamentary elements and M2 filamentary elements, in which each of the first and second assemblies includes a plurality of filamentary elements wound together in a helix, includes an assembling apparatus and a splitting apparatus. The assembling apparatus of the facility assembles M filamentary elements together into a layer of M filamentary elements around a temporary core, to form a temporary assembly. The splitting apparatus of the facility splits the temporary assembly into at least the first and second assemblies of M1 filamentary elements and M2 filamentary elements.