Circular knitted tubular structure, and manufacturing method and manufacturing device of the same

Abstract

A circular knitted tubular structure manufactured at low cost with use of a circular knitting machine is highly adaptable to bending due to flexibility, having tube inner and outer surfaces so soft that no abnormal noise is produced, and hence useful as a sleeve covering and thereby protecting a cable, such as an electrical wire and an optical fiber cable. The circular knitted tubular structure is formed of a fabric tape formed of circular knitted fabric having front yarn forming loops and back yarn having a higher heat shrinkage ratio than the front yarn and formed into a scrolled shape by letting the back yarn undergo heat shrinkage to have an overlap portion circumferentially overlapping 1.3 to 2.5 times. Apparatus for manufacturing the circular knitted tubular structure includes a furnace and a shape-forming jig.

1 . A circular knitted tubular structure formed of a circular knitted fabric tape having a length direction as a course direction, wherein:
 the circular knitted fabric tape has a cut edge in the length direction cut and left as is and is formed into a scrolled tubular shape to have an overlap portion in a width direction.   
     
     
         2 . The circular knitted tubular structure according to  claim 1 , wherein:
 the circular knitted fabric tape is formed of circular knitted fabric using yarn forming a right side and high shrinkage yarn passed on a wrong side and having a higher heat shrinkable property than the yarn forming the right side; and   the overlap portion of the circular knitted fabric tape circumferentially overlaps 1.3 to 2.5 times in a scrolled shape.   
     
     
         3 . The circular knitted tubular structure according to  claim 2 , wherein:
 circular knitted fabric is a single knit and the high shrinkage yarn is inserted in the width direction.   
     
     
         4 . The circular knitted tubular structure according to  claim 2 , wherein:
 the circular knitted fabric is a double knit and the high shrinkage yarn is passed in weave on the wrong side at least in part.   
     
     
         5 . The circular knitted tubular structure according to  claim 2 , wherein;
 a difference in dry heating shrinkage ratio between the yarn forming the right side of the circular knitted fabric and the high shrinkage yarn is 3 to 80%.   
     
     
         6 . The circular knitted tubular structure according to  claim 2 , wherein:
 the yarn passed on the wrong side of the circular knitted fabric includes at least one of monifilament having a single yarn fineness of 30 to 2400 dtex or multi-filament having a single yarn fineness of 30 to 2400 dtex.   
     
     
         7 . The circular knitted tubular structure according to  claim 2 , wherein;
 knit loops forming the right side of circular knitted fabric include loops having at least two loop lengths; and   loops having a shortest loop length account for 20 to 75% of all knit loops per unit area and a loop length of the loops having the shortest loop length is 20 to 80% of a loop length of loops having a longest loop length.   
     
     
         8 . A manufacturing method of a circular knitted tubular structure, comprising:
 knitting front yarn and back yarn having a higher heat shrinkage ratio than the front yarn into circular knitted fabric with a circular knitting machine by forming a front loop from the front yarn and passing the back yarn behind the front loop;   producing a fabric tape by cutting the circular knitted fabric knitted in advance in a course direction which is a length direction of knitted fabric at an interval of 1 to 30 cm in a width direction; and   forming the fabric tape into a scrolled shape with one end overlapping the other to have a scrolled overlap portion circumferentially overlapping 1.3 to 2.5 times in the scrolled shape by passing the fabric tape through a dried furnace at 70 to 190° C. in a range within which a length of the fabric tape becomes 0.8 to 1.3 times longer than an original length while the fabric tape is passed through a conical shape-forming induction jig which has a circular opening at an inlet and a scrolled, tapered opening at an outlet.   
     
     
         9 . A manufacturing device of a circular knitted tubular structure, comprising:
 a furnace heating a fabric tape formed of circular knitted fabric; and   a shape-forming induction jig shaping the fabric tape,   
       the manufacturing device being characterized in that:
 the shape-forming induction jig is of a conical shape having a circular opening at an inlet and a scrolled, tapered opening at an outlet; and 
 the shape-forming induction jig shapes the fabric tape inserted into the inlet and pulled out from the outlet into a scrolled shape with one end overlapping the other and allows the fabric tape to remain scrolled by heating in the furnace.