GB680666A - Improvements in or relating to grinding machines - Google Patents

Abstract

680,666. Grinding. MILLS (OPTICIANS), Ltd., A., and MILLS, S. April 20, 1951 [May 1, 1950], No. 10662/50. Class 60. A grinding-machine comprises a work holder which is adapted to be automatically traversed relative to the grinding wheel, a cam adapted to produce a predetermined range of automatic traverse of said holder during rotation of said grinding wheel, and means for adjusting the relative positions of said cam and holder to alter the mid-point of said range of traverse relative to said grinding wheel. In a machine for edge grinding optical lenses, the workholder comprises a bracket 10 having a body portion 10a by which the bracket is suspended from a shaft 11 so that it is free to slide thereon. Parallel arms 10b, 10c extending from the body portion 10a carry spindles 12, 13. The spindle 12 is free to rotate but is constrained against longitudinal movement and carries on its outer end a gear wheel 14 driven by a gear wheel 15 on the shaft 11; to the inner end of spindle 12 is fixed a pad holding member 16. The spindle 13 has a pad holding member 17 rotatably mounted on its inner end; the outer end of the spindle 13 has an internally threaded hole 13a engaged by a threaded spindle 18 having a handle 19 by rotation of which the spindle 13 is moved longitudinally. A lens 20 is held between pads 21, 22 fitted to the pad holding members 16, 17. In operation the bracket 10 hangs downward and the work is held against the grinding wheel 23 by a weight 24 on an arm 25 of the bracket, the pressure of the work against the wheel being adjusted by altering the position of the weight. For mounting the work, the bracket 10 is swung out and upwards so that the pad-holding members 16, 17 are uppermost. A cam 26 pinned to the shaft 11 has a grooved cam surface 26a in its periphery which is engaged by a roller 27 eccentrically mounted on a spindle 28 housed in a projection 29 on the arm 10c. At the other end of the spindle 28 to that at which the roller 27 is attached an arm 30 is pinned and carries a screw 31 engageable with .one of a number of holes equally spaced over half the periphery of a disc 32 fixed relative to the projection 29. Thus, with the cam 26 in any given position the bracket 10 occupies different positions on the shaft 11 depending upon which hole in the disc 32 is engaged by the screw 31. The shaft 12 carries a profile former 33 of hardened steel which bears against a fixed surface. The shaft 11 is driven from an electric motor through a clutch 34 which is disengaged when setting up the machine so that the shaft can be turned by hand.