US 4,436,988 A · Spiral bifilar welding sleeve

Abstract

A bifilar resistance element for use in preparing heating elements used in thermal bonding and the like, wherein two electrically conducting wires are embedded in a thermoplastic sheath which is fusible when sufficient current is passed through the bifilar resistance element. A heating element is prepared by joining the pair of wires in a length of the bifilar resistance element together at one end to form an electrically conductive path and then winding the length into a spiral shape. Two articles of thermoplastic material may be bonded together by placing the heating element in a recess simultaneously adjacent both articles with a pair of leads to the heating element extending externally from the two articles to be bonded, and applying an electrical current so that the thermoplastic sheath and a portion of the adjacent articles themselves are fused, to bond the articles together upon cooling.

Claims13

Dependent claims

A spiral bifilar welding sleeve for positioning between two thermoplastic members to be bonded together, said sleeve comprising;

an elongated thermoplastic sheath of generally rectangular cross-section, having a pair of short sides and a pair of long sides;
a pair of electrically conductive wires embedded within said sheath in a spaced, generally parallel relationship;
and
coupling means for electrically coupling said wires together at one end of said sheath, said wires at the other end being adapted for connection to an electrical current source, said sheath being wound into a plurality of turns defining a generally spiral coil with the short sides of adjacent turns being bonded together, said sheath being fusible when electrical current is passed through said wires to bond the thermoplastic members with respect to each other.

1 more element

Dependencies are inferred from the claim text.

Spiral bifilar welding sleeve

Life of this patent

Spiral bifilar welding sleeve

Life of this patent

Abstract

Claims13