GB1045017A - Vacuum chuck - Google Patents

Abstract

1,045,017. Vacuum chucks. DUNHAM TOOL CO. Inc. Feb. 10, 1964, No. 5528/64. Heading B3D. A vacuum chuck for use with any one of a series of ported surface plates 19, Figs. 1 and 2, comprises a onepiece integral base member 11 adapted to be anchored to a flat surface 17 and having an upper portion which is of predetermined outline and defines an endless sealing groove 13 at its outermost surface within said outline and a pattern of vacuum canals 14, 14a and surface plate support islands 15 surrounded thereby, holding means 20 disposed outside the outline of the sealing groove for mounting a surface plate in face-to-face contact with the support islands, and pressure control means 33 associated with the vacuum canals. The holding means comprise bolts 20 which hold a surface plate against the upper surface of the base member and compress an 0-type sealing ring 21 in the groove 13 to seal a chamber 22 formed by the canals 14, 14a in the upper surface of the base member which are covered by the surface plate. The upper surface of the plate is formed with a plurality of grid segments 23, each comprising a channel 24 and transverse channels 25. Each channel 24 has a tapped port 26 which effects communication between the channel and the chamber 22 and can be closed by a plug in the form of a bolt 27 and an 0-type sealing ring. In operation, a workpiece can be placed on the surface plate and abutting vertically adjustable bars B1, B2 and those grid segments which are not covered by the workpiece are disconnected from the chamber 22 by insertion of the plugs 27 so that vacuum applied to the chamber through a pipe 30 and passage 28 only acts in the segments covered by the workpiece. A pressure release 33 valve is adjustable to determine the vacuum force, as indicated on a gauge 31, acting in the chamber and passages 24, 25. In another embodiment, additional canals are provided in the base member to produce a plurality of smaller support islands 115, Fig. 3, and the surface plate 119 is formed with a plurality of vacuum holding ports 126, Fig. 4, which, when not covered by a workpieee W, can be sealed from the vacuum chamber 122 by bolts 126a having 0-type sealing rings. The workpiece may be arranged to abut a stop bar 36 which is held on the surface plate by bolts 38 passing through slots 37 in the bar and engaging tapped holes in the ports. In a further embodiment having a base member 219, Fig. 6, having surface plate support islands as shown in Fig. 4, the surface plate has rectangular ports 223 each of which is filled with a porous stainless steel element 224. When an irregularly shaped workpiec W<SP>1</SP> is placed on the surface plate, the parts of the elements not covered by the workpiece are covered by a sealable, non-porous plastic material 40 which may be sprayed on to the surface.