Rotary vacuum-chuck using no rotary union

Claim 1

In a rotary vacuum-chuck system having a rotary element with a work surface to which a workpiece is adhered by vacuum means and a fixed element providing support for said rotary element, an improvement for maintaining the vacuum to said work surface while said rotary element is in motion, said improvement comprising: (a) a substantially flat vacuum sealing element emplaced between said rotary element and said fixed element and having a smooth, self-lubricating surface providing low friction, slidable contact support for said rotary element; (b) on the side of said rotary element in contact with said sealing element, two radially spaced annular raised bearing surfaces defining a vacuum channel in close proximity to and concentric with the center of rotation of said rotary element, said vacuum channel being sized such that evacuation thereof improves the sealing contact of said raised bearing surfaces with said sealing element while permitting said rotary element to be rotated easily about its center of rotation, said sealing element having openings communicating with said vacuum channel; (c) means for exhausting the air from said vacuum channel through said openings; and (d) means for communicating the vacuum produced in said vacuum channel to said work surface such that a workpiece will adhere to said work surface.