Patent GB-1109405-A (GB)
Title: Improvements in or relating to arrangements of double conical grinding elements for relief-grinding hobs
Inventor: FLEMMING RUDOLF
IPC: B24B3/12
Filed: 1966-02-07
Abstract: 1,109,405. Grinding. MIKROMAT DRESDEN VEB. 7 Feb., 1966, No. 5311/66. Heading B3D. An arrangement of a double conical grinding element for relief grinding hobs comprises a grinding element 11 profiled correspondingly to the required tooth profile of the hob 15, adjusted to the helix angle of the tooth about an axis 5 oriented radially of the hob, and reciprocated in the direction of the axis in order to obtain the required relief grinding as a function of the rotation of the hob and its number of teeth, the centre of the grinding wheel being below the centre of the hob by an amount x in accordance with the function x = r tan gamma, where r is the radius of the grinding wheel and gamma is the clearance angle of the hob, and the angle of the grinding element about the axis 5 being modified during the stroke as a function of stroke magnitude in accordance with the function where alpha0 is the helix angle of the hob profile at the pitch circle diameter do, #alpha is the modification of the helix angle, and h is the relief machining height. The grinding element 11 is mounted in a spindle mounting 9 slidable along a guideway 8 on a rocking part 4 rotatably adjustable about the axis 5 by a worm and gear arrangement 33, 36, Fig. 6, having a hand wheel 34 and scale 35 by which the grinding element is adjusted to the helix angle alpha0 of the hob at the pitch circle diameter do. The spindle mounting 9 has a nut 16 which engages a threaded spindle 22 and is connected to a worm wheel engaged by a worm on a shaft having a hand wheel and scale by which the grinding element is adjusted to have its centre the distance x below that of the axis 5. The spindle 22 has a second threaded part engaging a nut 31 on a trueing device 30, and the spindle can be rotated by a hand wheel 28 having a scale 27 so as to adjust both the trueing device and grinding wheel to maintain the grinding wheel the distance x = r tan gamma below the hob. A ring 6 is mounted on the part 4 and carries the shaft 32, Fig. 6, for the worm 33, the shaft having an extension 44 carrying a roller 43 engaging a bar 40, Fig. 7, which is pivoted to one arm of a U-shaped member 37 and rests on a cam 39 engaged by a threaded shaft 38 having a hand wheel 42 and scale 41 by which the modification of the helix angle #alpha is set to adjust the grinding wheel about the axis 5, the member (37) being moved during the cutting stroke of the grinding wheel to cause the bar (20) to adjust the angle alpha during the stroke. The movement is effected by a screw which engages a nut 45 on the member and is rotated in accordance with the rotation of a shaft effecting the cutting stroke of the carriage 3 supporting the rooking part 4. In operation, the grinding element is adjusted to the distance x below the hob by rotation on the spindle 22, and is adjusted to the helix angle alpha0 by the hand wheel 34 and gearing 33, 36. The bar 40, Fig. 7, is then adjusted in accordance with the function #alpha by the hand wheel 42 so that during the cutting stroke the helix angle alpha is continuously modified.