Patent ID: 7559351

Claim:
An apparatus for joining multiple pieces of thermoplastic material to form a cellular block, comprising: a supplying mechanism for positioning a new piece to be added to the cellular block in opposing face-to-face relation with a last piece most recently previously welded to the cellular block; and a welding mechanism for contemporaneously forming multiple spaced apart and elongate welds between the new piece and the last piece while the new piece and the last piece are in the opposing face-to-face relation, so that each of the welds extends in a longitudinal direction and the welds are spaced apart from one another in a lateral direction, the welding mechanism comprising a pressing device and a heating device having a plurality of heating fingers that extend in the longitudinal direction and are spaced apart in the lateral direction, the heating device being movable in the longitudinal direction between an extended position in which the heating fingers are positioned between the last piece on the block and the new piece to be joined to the block and are in contact with the opposing surfaces of the new piece and the last piece to heat the new piece and the last piece at locations contacted by the heating fingers, and a retracted position in which the heating fingers are withdrawn from between the new piece and the last piece, the pressing device being structured and arranged to press the pieces together after the heating device is moved to the retracted position such that the new piece is welded to the last piece at said locations.