Flat cable and production method therefor

Abstract

A flat cable that includes a plurality of conductors respectively extending in an axial direction; and an insulating sheath configured to, in a state where the conductors are lined up in a width direction orthogonal to the axial direction of the conductors, restrict the conductors from outside and collectively cover the conductors, wherein the insulating sheath has an expander enabling bending in the width direction by permitting relative displacement between the conductors, and the expander, by expanding so as to partially separate from the conductors in at least a thickness direction orthogonal to both the width direction and the axial direction, forms an internal space permitting relative displacement such that adjacent conductors overlap in the thickness direction.

1 . A flat cable, comprising:
 a plurality of conductors respectively extending in an axial direction; and   an insulating sheath configured to, in a state where the conductors are lined up in a width direction orthogonal to the axial direction of the conductors, restrict the conductors from outside and collectively cover the conductors,   wherein the insulating sheath has an expander enabling bending in the width direction by permitting relative displacement between the conductors, and the expander, by expanding so as to partially separate from the conductors in at least a thickness direction orthogonal to both the width direction and the axial direction, forms an internal space permitting relative displacement such that adjacent conductors overlap in the thickness direction.   
     
     
         2 . A flat cable according to  claim 1 ,
 wherein the expander further expands so as to separate to the outside in the width direction from an outer circumferential face of outer conductors of the conductors positioned at both outer sides in the width direction.   
     
     
         3 . A flat cable according to  claim 1 ,
 wherein the expander has a bellows-like shape with a mountain portion configured to expand to the outside, and a valley portion having a smaller outer diameter than an outer diameter of the mountain portion and an inner diameter smaller than an inner diameter of the mountain portion, alternately lined up.   
     
     
         4 . A method for producing a flat cable, comprising:
 preparing a flat cable material having a plurality of conductors respectively extending in an axial direction, and an insulating sheath composed of a thermoplastic resin material and configured to, in a state where the conductors are lined up in a width direction orthogonal to the axial direction of the conductors, restrict the conductors from outside and collectively cover the conductors;   arranging a die, having an inner face with an expander having a shape expanding to the outside in a radial direction relative to an outer circumferential face of the flat cable material, around the circumference of a location of at least part of the flat cable material in the axial direction; and   by heating the thermoplastic resin material composing the insulating sheath to soften the thermoplastic resin material within the die and conferring a pressure difference such that pressure inside of the insulating sheath becomes higher than pressure outside of the insulating sheath within the die, forming, in the insulating sheath, the expander having a shape following the inner face of the die, the expander, by expanding so as to partially separate from the conductors in a thickness direction orthogonal to the width direction and the axial direction, forming an internal space permitting relative displacement such that conductors adjacent to each other overlap in the thickness direction.   
     
     
         5 . A flat cable according to  claim 2 ,
 wherein the expander has a bellows-like shape with a mountain portion configured to expand to the outside, and a valley portion having a smaller outer diameter than an outer diameter of the mountain portion and an inner diameter smaller than an inner diameter of the mountain portion, alternately lined up.   
     
     
         6 . A method according to  claim 4 ,
 wherein the expander further expands so as to separate to the outside in the width direction from an outer circumferential face of outer conductors of the conductors positioned at both outer sides in the width direction.   
     
     
         7 . A method according to  claim 4 ,
 wherein the expander has a bellows-like shape with a mountain portion configured to expand to the outside, and a valley portion having a smaller outer diameter than an outer diameter of the mountain portion and an inner diameter smaller than an inner diameter of the mountain portion, alternately lined up.   
     
     
         8 . A method according to  claim 6 ,
 wherein the expander has a bellows-like shape with a mountain portion configured to expand to the outside, and a valley portion having a smaller outer diameter than an outer diameter of the mountain portion and an inner diameter smaller than an inner diameter of the mountain portion, alternately lined up.