Patent ID: 6203621
Filing Date: 2001-03-20
Classification: B25B,C23C

Abstract:
A vacuum chuck for holding thin sheet material, said vacuum chuck comprising:a chuck body having a lower surface with an inlet therethrough, a plurality of side surfaces, and a gas-permeable support surface for supporting the thin sheet material, with thin sheet material inhibiting gas flow through said support surface so as to define a vacuum chamber having an inlet;a valve member for controlling gas flow through said vacuum chamber inlet; anda locking shim for holding said valve member in said vacuum chamber inlet, said locking shim responsive to said vacuum chamber inlet being coupled to a vacuum source for permitting said valve member to partially withdraw from said vacuum chamber inlet, to permit drawing of a vacuum in the vacuum chamber, and responsive to said vacuum chamber inlet being removed from the vacuum source for inserting said valve member more fully into the vacuum chamber inlet, to seal said vacuum chamber and retain the vacuum therein, holding the thin sheet material on said gas-permeable support surface, wherein said locking shim is formed of two layers of material having different coefficients of thermal expansion to cause said locking shim to curve in a preferred direction when heated, more firmly inserting said valve member into said vacuum chamber inlet to more firmly seal said vacuum chamber inlet.