GB1231502A - - Google Patents

Abstract

1,231,502. Lapping. LIQUID ABRASIVE PROCESSES Ltd. 27 Aug., 1969 [28 Aug., 1968], No. 41013/68. Heading B3D. A lapping machine comprises a lapping head 20 which is slidably mounted on a bed plate 10 and includes a plurality of rotatably mounted lapping discs 54, and means for epicyclically moving the discs. As described, the machine has a pair of opposed lapping heads 20, 22 and a workpiece in the form of a steel sheet is reciprocated between the heads and is gradually raised or lowered so that the whole of both faces of the sheet is gradually lapped. The heads are movable along guideways 18 on the bed under the control of a lead screw 24 having right- and left-hand threaded parts engaging the heads. Each head carries a stationary gear 34 engaging gears 52 on shafts which are journalled in head plates 30 and secured to respective lapping discs 54, the head plates being carried by shafts 42 rotatable in the heads. The head plates are formed with peripheral teeth 46 engaging a toothed bolt 58 driven by pinion 56 of an electric motor. In use, the sheet is reciprocated between the lapping heads, the laps of which rotate in opposite directions about their own axes and the axis of the shafts 42. Abrasive slurry is supplied to the lapping discs and is collected in a sump 12 and magnetic or centrifugal means may be provided to remove swarf. The workpiece may be a valve body, gear-box or other structure having joint faces and the heads may be advanced towards each other by the lead screw to a position determined by limit stops to control the depth of lapping. The lapping heads may be resiliently loaded on the lead screw to accommodate surface irregularities. In another embodiment, a single set of lapping discs are disposed vertically above a machine table. Each lapping disc may consist of a dished plate 62 filled with abrasive, such as carbide tips 64 removed from other tools, in an epoxy resin. Alternatively, the discs may be formed with or made from hardened tool steel, nickel chrome chilled iron or other abrasion resistant material.