Patent GB-653142-A (GB)
Abstract: 653,142. Dividing-engines. LIPP, R. W. Sept. 15, 1948, No. 24290. Convention date, Sept. 15, 1947. [Class 97 (iii)] A machine for dividing circles comprises a parent disc 21, Fig. 6, of unalterable radius carrying an angular scale or scales 9, 10 on its cylindrical circumference, a second carrier disc 19 secured to rotate with the parent disc 21 and whose radius may be varied, and a flexible band or tape 1, Fig. 4, of fixed length, marked with equidistant divisions 4 and perforated equidistantly by holes 2, the band being adapted so that a portion of its length corresponding to the number of divisions of 360 degrees required, may be wound round the periphery of the carrier disc 19 whose radius is then adjusted until such portion rests in tight circumferential relationship to the disc, the zero division of the scale 4 being coincident with the zero division of the angular scale 9 on the parent disc 21. The remainder of the band runs over a curved guide 23, Fig. 5, whose radius of curvature corresponds to the smallest radius of the carrier disc 19 on to the tap rolling-up drum 24 and its end 22 is secured to a spring-loaded lever 5 keeping the band under continual tension. As shown, the adjustable radius carrier disc 19 comprises a plurality of outer sectors each having an inwardly-directed radial segment 11 shiftably guided by means of a projection 13 in a radial slot 17 of the parent disc 21 and each being provided at each of its circumferential ends with an arm 20 having a pin 12 engaging both a lug in the segment 11 and a groove 18 in the parent disc 21, so that the ends of each sector are drawn in as the radius of each sector of the disc is decreased. The projection 13 on each segment 11 bears a nut engaging a threaded spindle 14 which carries at its inner end a bevel 15 engaging a common gear 16 coaxially mounted with the discs 19, 21, rotation of this gear this adjusting radially the position of each segment and thereby varying the radius of the carrier disc 19. The ends of each of the sectors may be in slot and key engagement with the ends of adjacent sectors. In a modification, the carrier disc comprises a plurality of narrow segments radially guided on the parent disc 21 each segment being provided with gear-teeth engageable by a centrally-mounted worm-gear. The mechanism for obtaining a step-by-step motion of the dividing discs comprises a guide 34, Fig. 14, for a slide 33 carrying an index pin 35 and operating lever 44. The operating lever 44 carries a two-surfaced cam 45, 46, Fig. 12, and is mounted on a slide 42 displaceable between two adjustable stops 43 in a partcircular guide 41 on the slide 33. Operation of the lever 44 in the direction of the arrow p lifts by means of the cam 46 the index pin 35 from the band 1 and engages therein, by means of the cam 45, a shifting pin 47a. Subsequently a pin 61 on the lever 44 abuts the end of a slot 61a and further operation of the lever moves the slide 42 from against the right-hand stop 43 to against the left-hand stop 43, thus moving the pawl 47 and its pin 47a and thereby the band 1 and the discs into the next position. On release of the lever 44, pin 35 engages the tape, pin 47a is withdrawn therefrom and the slide 42 may be restored to its initial position. The slide 33 is operatively connected to the main shaft of the dividing discs through bevel gearing 53, 54 turning a threaded shaft 57, gearwheel 50 and a rack on the slide so that the slide moves at right-angles to the parent disc 21 when the latter is rotated so that the index pin 47a follows the helical path of the band 1 on the carrier disc 19. A fine-adjustment device may be provided comprising a mounting for a microscope for reading the scales 9, 10 and a wedge-shaped sector which can be urged into engagement in a groove 67, Fig. 6, on the parent disc 21 and a worm gear by means of which the disc may be rotated when the wedge is in position.