GB972693A - Machine for smoothing and polishing natural and artificial stone surfaces - Google Patents

Abstract

972,693. Grinding and polishing. L. COLOMBI. Nov. 7, 1960 [Nov. 7, 1959], No. 38234/60. Heading B3D. A flat surface grinding and polishing machine comprises a polishing head with planetary arranged polishing and grinding tools 8, Figs. 1 and 2, having polishing surfaces rotating in their own plane and arranged perpendicular to a driving shaft, a carriage 5 raisably and depressably supporting the polishing head and adapted to run on carrying tracks movable in a direction transverse to the movement of the carriage, and a swinging transmission which co-operates with the driving shaft of the polishing head and imparts thereto additionally a circular swinging motion in a plane parallel to the surface of the grinding tools. A block L of stone to be ground and polished is placed on a bed 1 between supports 2, 3 along which is movable a span 4 supporting the movable carriage 5. The span and carriage are movable by rack-and-pinion gearing 24, 25, 31, 32, driven through reduction gearing and shafts 23, 30 from electric motors 16, 26. The carriage has a sector 47, Fig. 9, mounted on a pivot 48 and carrying a sleeve 52 supporting a shaft 56 which is rotatable by a pulley 57 connected by belts 58 to a motor 59 and at its lower end has a mount 60 for grinding and polishing wheels 89. The pulley 57 is also connected by a belt 62 to a reduction gear 64 mounted on the sector 47. The output shaft 65 of the reduction gear has an eccentric engaged with a rod 67 pivotally mounted to the carriage whereby the rotation of the shaft 56 is accompanied by an oscillating movement as a result of the movement of the sector about the pivot 48. The shaft 56 is axially adjustable to vary the height of the mount 60 by a hand wheel 79 which is lockable in position and operates a rack-andpinion mechanism 73, 75 to move a member 69 connected by bearings 70 to the shaft; a spring 74 between the rack and member 69 supplies a downward force to the latter to press the wheels 89 against the stone and to compensate for wear thereof. The mount 60 is formed with arcuate slots 61 which receive studs 85, Fig. 16, on a support 83 having shafts 86 carrying the grinding wheels 89. The shafts are provided with gears 92 engaging a toothed rim 93 which is rotatable relative to the mount and has wings 96 co-operable with resilient blocks 97 on the member 69 to prevent rotation of the toothed rim when the shaft 56 and support 83 are rotated whereby the grinding wheels rotate about their own axes and about the axis of the shaft 56 as the latter axis is oscillated. The shafts 23, 30 in the drive for the span and carriage from the motors 16, 26 have cams which operate switches controlling the motors so that, with switches actuated by adjustable blocks to control the extent of movement of the span and carriage, the grinding wheels can be moved to trace various paths over the surface of the stone.