Patent ID: 6217013
Filing Date: 2001-04-17
Classification: B25B

Abstract:
A workpiece holder assembly for vacuum-holding a workpiece for machining, the workpiece holder assembly comprising:a base plate having upper and lower surfaces, the base plate being adapted to be received within a recessed well of a generally flat mill bed defining vacuum passages therein, the base plate defining vacuum passages and being adapted to be installed in the well such that communication exists between the vacuum passages of the mill bed and the vacuum passages of the base plate, the upper surface of the base plate defining a recess therein, and the vacuum passages opening into the recess;an insert tool configured to be removably received in the recess of the base plate such that an upper surface of the insert tool and the mill bed collectively define a generally continuous surface for supporting a workpiece to be machined and such that the insert tool is maintained in a fixed position within the recess during machining of the workpiece, the insert tool defining vacuum passages opening at the upper surface thereof, the vacuum passages being configured such that communication exists between the vacuum passages of the insert tool and the vacuum passages of the base plate when the insert tool is installed in the recess, the insert tool including a first set of the vacuum passages therethrough and a first seal extending along the upper surface of the insert tool, and a second set of the vacuum passages and a second seal extending along the upper surface of the insert tool, the first set of vacuum passages and first seal collectively defining a first vacuum system for exerting vacuum on the workpiece, and the second set of vacuum passages and second seal collectively defining a second vacuum system for exerting vacuum on the workpiece such that vacuum applied through the vacuum passages causes a first surface of said workpiece to be suctioned against the insert tool to permit an opposite second surface of said workpiece to be machined to a predetermined contour including at least one protruding feature, the upper surface of the insert tool defining at least one depressed region configured such that said at least one protruding feature is received into said at least one depressed region when said workpiece is turned over after the second surface has been machined so as to allow the seals of the insert tool to sealingly engage the second surface such that the first surface can be machined.