GB1226780A - - Google Patents

Abstract

1,226,780. Lapping. MONTECATINI EDISON S.p.A. 30 July, 1968 [2 Aug., 1967], No. 36251/68. Heading B3D. A machine for lapping elements of crystalline structured brittle material, such as semiconductors, quartz and the like comprises planetary gears 5 which are disposed between annular lapping plates 1, 2, have means 8 for receiving the elements, and are engaged by an outer stationary gear 3 and an inner rotatable gear 4. The gears 3, 4 are in the form of chains or rollers and the chain 3 is carried by a casing 13 in which is a motor 9 driving through a gear unit 10, a hollow shaft 11 coupled to a disc 12 secured to the chain 4 which imparts rotation to the planetary gears 5. The gears 5 have apertures 8 for receiving the elements and are disposed between the upper and lower lapping plates of cast iron. The lower plate 2 is carried by supports 18 from a worm nut 15 rotatable by a crank 17 to adjust the height of the plate. The upper plate 1 is carried by arms 23 on a cylinder 20 slidable on a hollow support 19, oil pressure supplied to the cylinder controlling the pressure applied by the upper plate to the elements. An annular reservoir 24 containing an abrasive suspension is rotated by a motor 25. Stationary agitators extend into the reservoir which is connected by an adjustable valve 30 to a pipe which delivers the suspension to a groove 32 in the upper plate, the groove being connected by ducts to the space between the plates 1, 2. The thickness of the elements being lapped is indicated on a mechanical, pneumatic or electronic indicator having arms which measure the relative positions of the upper and lower plates. The elements may be positioned in and removed from the recesses 8 in the planetary gears 5 by a vacuum workholding device which is connected to a vacuum pump and operated by manually opening and closing a suction inlet. The annular lapping plates may be trued by turning on a lathe or by replacing the planetary gears 5 with gears loosely containing abrasive rings. A known machine is described in which the planetary gears are disposed between an outer and an inner gear rotating at different angular velocities and the annular plates may be rotated.