GB698372A - Improvements in orbital lathes for turning crankshafts - Google Patents

Abstract

698,372. Crank-shaft lathes. BOEHRINGER GES., GEB. Aug. 13, 1951, No. 19055/51. Class 83 (iii). An orbital lathe for simultaneously machining the crank-pins of a crank-shaft by tools arranged in pairs, the tools of each pair being attached to a tool-holder on opposite sides of a crank-pin, comprises a number of such tool - holders mounted for orbital motion on two synchronously rotating master crank-shafts journalled within a cradle pivotally mounted within the frame of the machine for rocking motion about an axis extending parallel to the work spindle, said cradle being rocked for advancing and retracting the cutting- tools mounted at substantially equal distances from said axis which is located between the master crank-shafts, work spindles for two crank-shaft blanks being mounted in the frame at substantially equal distances from said axis and each tool support carrying two pairs of tools. The machine frame comprises a base 11, Fig. 2, columns 10, 10<SP>1</SP>, rigidly connected therewith, and a hollow beam 12 at the top connect. ing the columns. The columns support headstocks 13, 13<SP>1</SP>, which carry synchronouslyrotated spindles with chucks 16, for supporting and driving at both ends, two crank-shafts K to be machined. Also supported between the columns on trunnions 22, Fig. 4, at the rear of the machine, is a cradle 21 rotatable about a central axis 20, Fig. 3, parallel to the work axes. The cradle carries a pair of master crank-shafts 25, 26, Fig. 3, equally spaced above and below its main axis and rotating synchronously with the work through gearing which remains unaffected by tilting movement of the cradle. The master crank-shafts are of the same throw as that required on the work-pieces K and each corresponding pair of master crank-pins is engaged by connecting bearings 45 on the arms 44 of tool carrier-plates 43. The latter are thus constrained to move in an orbital path and pairs of tools 46, 47, and 48, 49, operate respectively on the upper and lower work-pieces. Cutting feed of first the upper tools and then the lower tools is effected by the tilting movement of the cradle 21 through the reciprocation of a fluid piston-and-cylinder 51, 54. The main drive to the work and master work-shafts is from an electric motor 17, Fig. 2, and a variablespeed fluid transmission 18; means (not described), may be provided for varying the speed automatically in relation to the tool feed to maintain a constant cutting speed. Catching and removing cuttings.-A removable plate 55, Fig. 3, on the front of the machine, directs cuttings into a box 56, Figs. 2 and 3, on rails in a pit below the machine. Cuttings may thus be removed by drawing the box to the rear of the machine.