| 摘要 |
A vacuum holding platen is constructed as a lamination comprised of a thin center aluminum sheet to each side of which is adhered a Masonite sheet, the outward face of which has been routed to provide desired channel patterns through which air may be exhausted by connection to ducts leading from an air exhausting pump. The routed Masonite on the side of the platen upon which the sheet material is to be held, is adhesively covered with a perforated sheet. The other Masonite sheet is similarly covered with an unperforated thin sheet of aluminum. All of the unperforated sheets are appropriately orificed to enable the channels to be selectively connected, depending upon the size of the film or other sheet material to be held by the platen, through a valve block, movably disposed on the back of the platen, to the air exhausting pump. The orificed metal sheets may be of aluminum and punched to provide perforations or passage orifices. The Masonite sheets are routed and all contacting surfaces of the sheets are coated with epoxy and compressed between granite blocks which are hydraulically separable to permit insertion in between them of the sheets to be compressed and removal therefrom of the compressed platen.
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