Abstract: A method and apparatus are provided for welding vinyl window and door frames. The apparatus includes a counting circuit or the like for measuring the time taken for burning off a selected length of a thermoplastic frame member. This time can be used to calculate a sufficient or optimal period for performing a heating or plastification step. Once the ends of the frame members are properly heated (plastified), they are fused by urging them towards each other. The fused members are then cooled for a period of time which also corresponds to the time required for burn-off. The apparatus further includes a heating plate which is pivotable between an operating position and a retracted position. The heating plate is also movable so that different surface portions can be used during burn-off and heating phases.

Abstract: An apparatus for simultaneously welding two or more pairs of thermoplastic frame elements is disclosed. The apparatus includes a clamp or jig assembly which maintains the frame elements in alignment with respect to each other and to a heating plate. A driving assembly is provided for moving the frame elements towards the heating plate and/or towards each other for heating and fusion.