GB754357A - Improvements in or relating to a method of and apparatus for controlling the tools of machines for grinding and/or polishing glass - Google Patents

Abstract

754,357. Grinding or polishing glass. GLACERIES DE LA SAMBRE SOC. ANON. May 26, 1954 [May 27, 1953], No. 15616/54. Addition to 713,053. Class 60 The progressive adjustment of the pressures applied to the upper and lower tools of an apparatus for simultaneously grinding or polishing both faces of a horizontally moving glass sheet to compensate for the loss of weight due to the wear of the tools, as described in the parent Specification, is effected by utilizing the vertical movement of the tools to vary either the voltage applied to a pressure-compensating electromagnet or the degree of compression of a pressure-compensating spring. In Fig. 1, the upper tools 8 are rotated by a motor 14 and supported by a cross-member 7 which is in turn supported by hydraulic pressure acting on piston 6 and by a plunger 11 controlled by an electromagnet 1. The upward force exerted by the latter is decreased as the tools move downwardly due to wear by a variable resistor R2 the slider 10 of which is rotated by the plunger 11. The initial pressure applied to the tools is adjusted by a second variable resistor R1. An electromagnet 16 acts in a similar manner on a cross-member 18 for the lower tools 19 and may be arranged to apply either an increasing downward pressure or a decreasing upward pressure to that member. Safety abutments 13, 26 controlled by motors 12, 25 limit the movement of the members 7, 18. In a modification, the compensating adjustment of pressure is effected by connecting the electromagnet to a spring-loaded valve in the hydraulic supply line. In Fig. 3, upward pressure is applied to a cross-member 41 supporting tools 49 by springs 43 and by a pair of springs 65 arranged transversely of the cross-member. As the latter moves downwards due to the wear of the tools, a disc 44 supporting the lower ends of the springs moves downwards at the same rate so that the degree of compression of the springs 43 remains constant while the lower supports for the springs 65 move downwards at a higher rate thus allowing these latter springs to expand and reduce the upward pressure applied to the crossmember 41. The movement of the spring supports is effected either by screw and nut and toothed gearing operated by racks 53 mounted on the member 41 or by a motor receiving impulses as a function of the movement of the cross-member. A hand-wheel enables the initial pressure applied to the springs 43 to be adjusted. The cross-member 68 for the lower tools is urged upwardly by counter-weights 69 acting through racks 70 and toothed sectors and progressively compresses a spring 72 which thus applies an increasing downward pressure to the member 68 to compensate for the loss of weight of the tools.