Patent ID: 8049146

Claim:
A device for welding two polymer parts via fusion, the device comprising: a heater mat knitted from a continuous resistive wire having first and second ends and coated with an insulating varnish, wherein the heater mat is flexible, the heater mat has a mesh of cells ranging in size from 1.5×3 mm 2 to 2.5×4.5 mm 2 , the resistive wire has a diameter ranging from 0.2 mm to less than 0.3 mm, the varnish melts at a predetermined temperature, short circuiting the resistive wire so that heating of the heater mat, in response to an electrical current through the resistive wire from the first end to the second end, stops, and the heater mat is folded at least partially on itself and has a first region with a relatively high density of the cells and a second region with a relatively low density of the cells, the first region reaching a higher temperature than the second region in response to the electrical current flow through the resistive wire from the first end to the second end.