Method of making foam filled panels

Claim 1

A batch method of making a foam filled panel comprising: placing a first sheet in a generally stationary position; said first sheet having turned edges around its margin; placing against said first sheet a second flexible sheet adapted to rest at said marginal edges; selectively clamping marginal edges of said sheets together at one end thereof with individual clamps placed at laterally opposed marginal edges of said sheets; spreading said sheets apart from the opposite end thereof so that a hollow, closed space is formed between said sheets where so clamped; after said spreading, introducing foamable material into said hollow space while causing said foamable material to foam so as to fill said hollow space at least partially and then terminating the introduction of foamable material; while continuing to clamp said sheets at said one end, further selectively clamping laterally opposed marginal edges of said sheets adjoining said one end with additional individual clamps to extend said closed, hollow space; after said further clamping, introducing foamable material into said extended hollow space while causing said material to foam so as to fill said extended hollow space at least partially and then terminating the introduction of foamable material; progressively alternately selectively clamping with further additional clamps and filling adjoining portions of said sheets with foamable material which foams therein until a foam filled panel is formed; and keeping said sheets substantially stationary at a fixed location during the foregoing clamping and filling steps.