Vacuum press

Claim 1

A vacuum press comprising: a work-support assembly including a first frame defining a first opening, means supporting said first frame, and a pliable air-impermeable sheet extending across said first opening and secured at its edges to said first frame, said sheet drooping between its edges; a platen assembly disposed above and hingedly connected to said work-support assembly so as to be movable into and out of engagement with said work-support assembly, said platen assembly including a second frame defining a second opening, a flexible metal platen extending across said second opening and overlapping the underside of said second frame, said metal platen being supported only at its edges by said second frame so that (a) said metal platen can droop between its edges under its own weight and (b) the edges of said metal platen are free to move relative to said second frame on expansion and contraction of said metal platen in response to changes in temperature thereof, and electrical heater means for heating said metal platen, said heater means being disposed within said second opening above said metal platen; said platen assembly and said work-support assembly when engaged providing an air-tight work-receiving chamber therebetween with said metal platen and said flexible sheet forming opposite side walls of said chamber; means for evacuating said chamber so that the atmospheric pressure exterior of said chamber will force said flexible sheet and said metal platen toward each other and thereby compress a workpiece supported on said sheet; and control means for operating said electrical heater means and said evacuating means so that a workpiece in said chamber is both heated and compressed.