Patent GB-191200532-A (GB)
Title: Improvements in or relating to Feed Mechanism for Machines.
Inventor: PILKINGTON HERBERT MORRIS
IPC: G03F7/22
Filed: 1912-01-06
Granted: 1913-01-02
Abstract: 532. Pilkington, H. M. Jan. 6. Dividing - engines.- Relates to apparatus for accurately obtaining and repeating a predetermined amount of rotation of an operating-shaft, such as is required in dividing- engines or in photographic copying-apparatus such as is described in Specification 13,517/11, [Class 98 (i), Photographic cameras &c.]. In providing for a number of complete revolutions of the shaft, a locking- member moves between two positions determined by limiting stops, and in providing for a fraction of a revolution two other limiting stops are provided for another ultimate stop which, at the conclusion of the complete revolutions, is advanced from one stop to the other to complete the partial rotation required. The shaft may be rotated in either direction and means are provided whereby the stops may be automatically reset for a subsequent motion. To set the apparatus for, say, ten and twenty hundredths of a revolution of the shaft 1, Fig. 1, a handle 9 is rotated backwards through ten divisions on the index plate 11, thereby rotating the sleeve 8 and the arm 10. This arm is the limiting-stop and the starting-point of a pin 34 on a toothed disk 32, which is looselv mounted on a sleeve 27 and is turned by a coiled spring 37 to follow the stop 10. The sleeve 27 is coupled to the shaft 1 by a pin 28 which extends through a slot 30 in the shaft. For the odd fraction of the revolution, the handle 19 is rotated through twenty divisions on the index 21, thereby rotating the sleeve 18 and the arm 16, which, with the arm 17 in one with the index 21, constitute the limiting-stops for the partial rotation and control the motion of the ultimate stop 15. The handles 9, 19 are held by springs in engagement with teeth on the index plates 11, 21 respectively. To rotate the shaft 1, the knob 73 is pressed, moving an axial rod 29 and thereby moving the pin 28 along the slot 30 and the sleeve 27 and disk 32 along the shaft. This motion moves the teeth of the disk into engagement with pawls 42, 42<1>, Fig. 2. The pawl 42 is mounted on a spring-controlled arm 44, which is reciprocated on each revolution of the shaft in either direction by a cam 38. The arm 44 is pivoted to an extension 41 of the frame 14, which carries a slotted bolt 46 with a toothed edge 49, whereby it is locked to the teeth 7 of the casing 3 by the pressure of a spring 52. On each revolution of the shaft 1 and cam 38, the disk 32 is advanced one tooth by the pawl 42, and the additional pawl 42<1> holds the disk against being rotated backwards by the spring 37. At the end of the ten complete revolutions, an arm 53 on the disk 32 comes between two plates 57, 50 on the arm 44 and bolt 46 respectively, and raises the bolt 46 to unlock the frame 14 from the casing 3. Two spring dogs 49 on the bolt grip a finger 58 on the cam 38, thereby locking the frame 14 and wheel 32 to the shaft 1. On continuing to rotate the handle 63 and shaft 1, the whole frame 14 is rotated until the stop 15 which starts from the zero limiting-stop 16 is arrested by the stop 17. The stop 10 has rotated with the frame 14 so that it is still set relatively to the disk 32 for just ten complete revolutions of the shaft. On releasing the knob 73, the rod 28 is retracted by the spring 75, thereby retracting the sleeve 27 and disk 32, which is again rotated backwards to the stop 10. The retraction of the arm 53 also releases the bolt 46. which is thereupon locked to the case 3 by the spring 52 releasing also the finger 58 and cam 38. In order that the limiting stops 16, 17 may be automatically reset, they are connected by a friction clutch and spring mechanism to a disk 69 which is rotated with the handle 63. A friction plate 76 is held against the disk 69 by a ring 77 and springs 79. Two oppositelywound spiral springs 81, 81<1> are attached between the hub 80 of the plate 76 and a pin 82 on the toothed sector 25, which is locked to the toothed plate 6 on the casing 3 by the springs 85. A pin 83 on the friction disk 76 extends in the path of the pin 82. On rotating the shaft 1 and during the first revolution, the disk 76 is rotated by friction and tensions one or other of the springs 81, 81<1> until arrested by the pin 82 engaging the projection 83, after which the plate 76 slips between the ring 77 and plate 69. To reset the stops 16, 17, the handle 63 and knob 73 are gripped towards one another, thereby retracting the bar 64 and the plate 69 along the shaft against the spring 85 and unlocking the sector 25 from the sector 6. The sector 25 is rotated backwards by the spring 81 or 81' that was tensioned and rotates the stops 16, 17 which are coupled through the handle and index 19, 20. The rotation is arrested by the stop 15 engaging the stop 17. The grip between the handle 63 and knob 73 is now released, and the apparatus is ready for a repeat rotation, for which it was set. If it is required to reverse the rotation of the shaft after any movement, the stops 16, 17 are not reset, since the stop 15 will be against the stop 17, and at the completion of the complete revolutions backwards, the frame 14 will be rotated backwards until the projection 15 is arrested by the stop 16. In order to compensate for the thickness of the stops 15, 16, 17, each stop is constructed with a pivoted finger tip 90, Fig. 11, which moves between stops 92 so that the acting-edge of the stop always coincides with the centre line of the stop in both directions of rotation.