Methods of and apparatus for forming a metallic tape into a tube having an overlapped seam

A method of wrapping a corrugated metallic tape about a cable core to enclose the core in a shield having a substantially circular configuration and having a preformed, overlapped seam, said method comprising the steps of:

• advancing a cable core along a path of travel through a tube and a die;
• moving successive increments of length of a corrugated metallic tape into engagement with a converging, generally conically shaped surface which is disposed about said tube to cause the successive increments to have at least a partially curved configuration with longitudinal edges of the successive increments being adjacent each other;
• moving the successive increments having the at least partially curved configuration through a plurality of adjacent, sequentialy decreasing openings to cause the tape to have a generally circular configuration;
• then
• providing individual confinement for longitudinal edge portions of the tape for at least a portion of the length of the path of travel along which they are formed into a seam to engage the longitudinal edges of the tape;
• while
• moving the cable core and the tape through the die along the portion of the path of travel with the confinement of the longitudinal edge portions being effective to form an overlapped seam having an underlying edge portion and an overlying edge portion which is directed inwardly into substantially continuous engagement with the underlying edge portion to preclude its protrusion into a plastic jacket which is substantialy extruded over the enclosed core.