Patent GB-948748-A (GB)
Title: Polishing a convex surface of a work piece
Inventor: FORD ELWYN
IPC: B24B13/02
Filed: 1960-08-17
Abstract: 948,748. Polishing. AUTOFLOW ENGINEERING Ltd. Aug. 17, 1960, No. 28469/60. Heading B3D. In a machine for polishing a convex surface of a workpiece having a circular curvature in at least one direction, e.g. a torically curved optical lens, a circular holder 91 is adapted to support a plurality of workpieces 90 around its periphery and is adapted to be driven by a motor 108 so as to move the workpieces tangentially across a pair of diametrically-opposed polishing members 93, 94 which are held against the workpieces by spring devices 98, 98; the polishing members are adapted to be driven by respective links 96, 97 to reciprocate across the periphery of the holder in a direction parallel to its axis of rotation; the links are pivoted from the aligned arms 101, 102 of a T-shaped lever of which the third arm 103 is adapted to be oscillated by the motor 108 in order to reciprocate the said links 96, 97; the T-shaped lever is pivoted, intermediate its arms, from an eccentric which is driven by the motor 108 whilst the T-shaped lever is oscillating whereby to modulate the said reciprocations to delay the chance of the polishing members re-tracking on a workpiece. The motor 108 is electric and drives, through belt 111, a pulley 109 on a shaft 112 driving, through reduction gearing 119, a shaft 122. The latter drives, through chain and sprockets 125, 126, a shaft 127 driving, through reduction gearing 129, the shaft 92 of the holder 91 on the periphery of which concave-convex lenses 90 are mounted. Polishing blocks 93, 94 are rockably supported by pairs of pins 95 fast with arms 96, 97 and the desired polishing pressure is applied by spring devices 98 acting through pins 99. Each spring device includes a cylinder 156 in which is guided a rod 157; a compression spring 159 acts on a nut 158 adjustable along a screw-threaded portion of the rod. The cylinder 156 is pivotally connected with a pressure control lever 161 pivoted on the machine frame and having a head 163 extendible against a spring for engaging a locating pin 164 in a selected one of a number of holes in a stationary quadrant 165. To maintain engagement between the pins 99 and arms 96, 97 the latter are connected by tension springs 166 to the cylinders 156. The opposite ends of arms 96, 97 have parallel upper and lower bosses 100 by which pivotal connections, including thrust bearings, are made to the extremities of arms 101, 102 of the T-shaped lever which can oscillate about aligned pivotal supports 104, 105. The lever arm 103 is connected by rod 117 to a crank-pin 114 adjustable in a diametral T-slot 113 in pulley 109. The holder 91 rotates at about 60 r.p.m. and the blocks 93, 94 make 400 reciprocations per minute. The inner end of arm 103 has a boss 137 in which is journalled, by ball-bearing 139 and roller thrust bearing 140, a cylindrical member 138 having aligned eccentric extensions 141, 142 providing the inner members of the pivotal supports 104, 105 for the T-shaped lever. The pivotal support 104 is from a plate 143 detachably secured to the machine frame and the pivotal support 105 is from a plate 145 welded to the machine frame. Extension 142 carries a skew gear 147 driven by a coacting wheel 148 on shaft 149 carrying a worm wheel driven by a worm on shaft 122.