1. Field of the Invention
The present invention relates to stripping electrical wires and more particularly, to a spiral stripping electrical wire. The invention relates also to the fabrication of the spiral stripping electrical wire.
2. Description of the Related Art
The outer insulative material of an electric wire or cable is formed by means of extrusion coating. During extrusion, the conductor is extruded with the polymer out of the hole of the die at the same time.
The insulator of an electric wire or cable is made in one single color. There are some electric wires and cables that the insulator extruded from two different colors of plastics. The double color design is for easy identification. Further, the double color design also adds to beauty, thus enhancing market competivity.
FIG. 1 is a sectional view of a conventional double color electric wire extrusion device. According to this design, the extrusion device 80 comprises a main flow passage 81 and an auxiliary flow passage 82. During extrusion, the screw rod (not shown) squeezes a first insulative material 92 in the main flow passage 81 axially forwards (along the electric wire extruding direction), and simultaneously squeezes a second insulative material 93 in the second flow passage 83 perpendicularly into the first insulative material 92 in the main flow passage 81, enabling the first insulative material 92 and the second insulative material 93 to be extruded with a conductor 94 out of a die hole 83 to form an electric wire 90 having an insulative coating layer 91. FIG. 2 illustrates the outer appearance of an electric wire 90 made by means of the aforesaid extrusion device 80.
In the aforesaid extrusion device 80, the second insulative material 93 is squeezed into the first insulative material 92 from a fixed point, therefore the second insulative material 93 forms a strip in the first insulative material 92. The strip of the second insulative material 93 provides the insulator of the finished electric wire a second color for identification. To have a breakthrough in visual effect in a double color electric wire, a wire twister may be used to twist a double color electric wire spirally, changing the straight strip into a spiral strip. However, because the electric wire is flexible, it will return from the spirally deformed shape to its former straight strip shape or become not apparent in twisted shape when the external force is disappeared. For once and for all, it is not the cleaver way to change a double color electric wire into a spiral stripping design by twisting.