GB308875A - Improvements relating to grinding or abrading machines - Google Patents

Abstract

308,875. Hughes, V. A. B., (Cincinnati Grinders, Inc.). Feb. 25, 1928. Centreless grinding; guides and rests. - In a machine for grinding cylindrical work-pieces, the work is automatically moved axially across the face of a grinding-wheel until its full length is in contact with the wheel, is allowed to remain axially stationary but rotating until the rough grinding is completed and is finally moved axially again while a finishing cut is being taken by the wheel. The machine comprises a two part base 1, 2 on which is mounted a slide 11 carrying the rapidly revolving grinding-wheel 12, driven by a belt 25, and a compound slide 14 carrying an abrasive regulating-wheel 15 driven slowly in the same direction as the grinding wheel by gearing which allows adjustment of the wheel 15. The regulating-wheel is mounted in bearings on a bracket 56 vertically adjustable by a screw and hand-wheel 55 on a slide 50 which is adjustable to and from the grinding-wheel by a screw and hand-wheel 43. The slide 50 is carried by the slide 14 and the latter is adjustable by a screw and hand-wheel 63 on a turntable 58 which is rotatably adjustable about a vertical axis by means of arcuate slots and bolts 60. The shaft 57, Fig. 2, on which the regulating-wheel 15 is mounted carries a spiral gear 72 engaging a similar gear on a shaft 74 provided with a second spiral gear engaging a similar gear 77 on a telescopic shaft 80, the casings 70, 73 being rotatable about the shafts 57, 74 respectively to allow the drive to be continued when the wheel 15 is adjusted. Similar gears 82 and casings 81 drive the shaft 80, through spiral gears 90, 93 and shaft 92 from the main drive shaft 26, Fig. 3. A telescopic rod 95, pivotally attached ta lugs 96, 97 on the upper and lower gear casings serves to rotate the latter as the regulating-wheel is adjusted and so relieve the driving shaft 80 from bending strains. The work W is supported during grinding by a rest 17, Figs. 1, 2, and 7 having a cylindrical surface 100 of exactly the same radius as the finished work-piece, terminating in tangential surfaces 100<a>, the construction being such that the lines a, b, passing through the centres of the regulating and grinding wheels 15, 12, respectively and the centre of the work W intersect the rest on the tangential surfaces. For all sizes of work the regulating-wheel is arranged as far above the work as possible so as to produce a resultant thrust R passing subtantially through the centre of the rest which may be cut away at 101. The rest is mounted by a clamp 20, on a slide 16, adjustable longitudinally on the slide 14 by means of a screw and hand-wheel (not shown). The grinding-wheel slide 11 is adjustable by means of a screwed shaft 34, Fig. 1, rotated through gearing 33 from a handle 30 and engaging a half-nut 35 on the slide. For operating on a succession of similar cylindrical blanks the grinding and regulating-wheels are arranged with their axes parallel and the blanks are supplied to a vertical shoot 136, Fig. 2, from which the lowest blank is removed by a plunger 110 reciprocated by a rotating cam 118 engaging a roller 114 thereon and a spring 116. The shoot, plunger and cam are carried by a bracket 112 adjustable transversely of the machine by a hand-wheel and screw 123 and the cam is rotated from the shaft 87 by spiral gearing 128 and a universally-jointed telescopic shaft 132. The work rest 17 extends on each side of the grind. ing throat and receives the lowermost blank from the shoot. The blank is then pushed into the throat and is allowed to remain axially stationary whilst the springiness of the wheel supports is taken up and the blank is ground down to size, after which the succeeding blank removes it from the throat and in so doing applies the finishing cut. The width of the grinding and regulating- wheels is preferably greater than the length of a blank so that their leading edges may be worn round and still leave a flat periphery on each wheel to give the correct size to the blanks. On leaving the work rest 17, the finished blanks enter an inclined shoot 142.