Method and apparatus for butt welding thermoplastics sheets and films

A method of thermally splicing together the edges of a first and second thermoplastic foam sheet, comprising sequentially (a) providing a first and second thermoplastic foam sheet to be spliced, (b) providing at least two spaced-apart pair of edge guide means abutting said sheets at their respective lateral edges to laterally and axially align said first and second sheets to be spliced prior to splicing, (c) completely transversely severing the leading section of said first thermoplastic foam sheet with a heated element to expose a transverse edge of said first sheet to be spliced, (d) completely transversely severing, by continued movement of said heated element, the trailing section of said second thermoplastic foam sheet to expose a transverse edge of said second sheet to be spliced, (e) moving said heated element in the reciprocal direction adjacent the exposed transverse edges to heat said edges to a temperature sufficient for the edges to be thermally welded, and (f) bringing the heated transverse edges into abutting relationship to thermally weld said edges together, while maintaining the sheets aligned with said edge guide means.