GB162216A - Improvements in grinding and polishing machines - Google Patents

Abstract

162,216. Kliem, E. July 2, 1920. Disc apparatus; bevelling; vacuum chucks and work-holders; driving and feed devices. - A machine especially for bevelling the edges of circular or oval discs of glass, granite, hardwood, &c. comprises an adjustable travelling workholder which is propelled by its own driving-shaft towards the grinding-wheel and is automatically released and returned to the starting-point on completion of the grinding. The machine shown comprises a grindstone i on a headstock h, and a workholder f vertically and angularly adjustable on a pillar e. The headstock h and the base d of the pillar are mounted in guides c on the base b, and are adjusted by screws l, k. The work is placed on a vacuum plate 48 attached to a variable chuck, shown also in Fig. 6, and is rotated by the main shaft 10, which is mounted in bearings z, 1, and is driven by a rope &c. on a pulley x through worm-gearing t and toothed gearing q, p. The bearings z, 1 are parts of the work-holder f, which is mounted in guides m in a frame n pivotally mounted on a collar or sleeve 32 on the pillar e. The work-holder f is advanced by a spindle 6 rotated intermittently by a pin 9 on a wheel 10 engaging with a star-wheel 7 similar to a Maltese cross, the screwed part of the spindle 6 engaging with a half-nut 13, which is normally retracted by a spring 19, but is brought forwards when necessary by a handle 20, and retained in gear by a spring-pressed detent 21, which is removed by a trip lever. The work-holder is moved forwards until the bevelled collar 2 on the spindle 6 engages with the trip lever, when the spring 19 withdraws the half-nut, and the spring 31 retracts the workholder. The chuck consists of a vacuum plate 48 on a spindle 36<a> on a plate 36 which is adjustably attached to a disc-shaped slide 41 on the end of the main shaft o. At the rear of the shoe 41 are arms 44 embracing the diameters of a circular ring 40 on a plate 39 adjustably attached to a plate 37 on the end of the bearing z. If the ring 40 is set concentrically with the shaft o, the vacuum plate rotates so as to grind circular discs; if it is set eccentrically, as shown, the machine grinds elliptical discs. The vacuum plate is connected by a pipe 46 to a pump. The grinding- wheel is reciprocated in its own plane by means of an eccentric 49, which bears against lugs 54 inside the upper part of the headstock h and moves it on the lower part q, which contains the adjusting-screw l. The wheel spindle 35 is pressed forward by a weighted lever 57, a spring 60 tending to retract it. The shaft o is divided within the bearing z, and the parts are connected for example by a spigot and socket joint. A spring 5 enables tho upper end to yield when the grinding-pressure is excessive.