Patent GB-954764-A (GB)
Title: Web-advancing mechanism, more especially for paper webs in photographic printing machines
IPC: G03B27/58
Filed: 1963-03-13
Abstract: 954,764. Controlling clutch-brake combinations. AGFA A.G. March 13, 1963 [March 23, 1962], No. 10029/63. Heading F2L. [Also in Division B6] A variable length web-feeding mechanism, more especially for paper webs in photographic printing machines, comprises a web-feeding roller, means for intermittently coupling the roller to continuously rotating driving means and a rotary coupling interrupter arranged, when the coupling means is operative, to be rotated against return spring loading to an interruption position from an initial angular position which is variably settable by setting means for the distance of advancement of the web by the roller and, after having effected coupling interruption, to return to said initial position. The roller 7, Fig. 1, is the intermittently driven web feeding roller which is driven by a continuously rotating pulley 11. When at the commencement of a paper-feeding operation, a cam disc 15 pivots a lever 14 and thus a spindle 13 in a clockwise direction (see Fig. 3), a lever 17 is rotated to the right, as a result of which its upper end 17a is retained by a spring 19 in the catch recess 20b of a lever 20 which has been pivoted downwards. A bladed spring 22a is urged to the left by a lever 18 (see Fig. 3), and operates a starter switch 22 which connects up an electromagnetic clutch 10 and a control magnet 24. The control magnet 24, Fig. 1, by way of a lever 26 and rod 27, pivots a lever 28, Fig. 4, anti-clockwise against loading by an anchored tension spring 49. A tooth 28a is lifted from a ratchet wheel 8, connected to the shaft of the web roller 7, and an extension 29a, Fig. 3, co-operates with the teeth of a planet carrier 30 of a sun and planet mechanism, Fig. 2, freely rotatable on the shaft of the roller 7. The web roller 7 is now driven through the magnetic coupling 10 which indirectly drives a sun wheel 32 free on the shaft of the roller 7 by way of sun and planet gears 31, 33, 34, the sun wheel 32 moving in the direction of the arrow 35 out of the position shown in Fig. 2 to tension a torsion spring 46. At the end of the feeding movement, a pin 47 on the wheel 32 (see the broken line position in Fig. 3) meets the tooth 20a of the lever 20 and raises the latter, whereby the lever 17 returns to its initial position as shown in Fig. 3. As a result, the switch 22 is opened which switches-off the current engaging the electromagnetic clutch 10 and the control magnet 24. The detent tooth 28a of the lever 28 then engages the ratchet wheel 8 and arrests the feeding roller 7. Likewise, the extension 29a is raised, allowing the reaction carrier 30 to rotate freely. After release of the wheel 30, the sun and planet mechanism is returned by the torsion spring 46 to the initial position as shown in Fig. 2. Whereas the pin 47 always meets the tooth 20a of the lever 20 at the same point, its initial position can be varied by rotation of a setting lever 38 by means of a knob 39. In a second embodiment, Figs. 7-10, the web roller 57 is to be driven intermittently by a continuously driven sprocket wheel 70, Fig. 7. The hub 70a of the sprocket wheel 70 is provided with a helical coil spring clutch 78. The clutch is under control of two ratchet wheels 72, 73, fixed and free to rotate respectively, on a bush 67 which is keyed to the hollow shaft 56 of the web roller 57. One end of spring 78 is connected to the ratchet wheel 72 and the other to the ratchet wheel 73. Relative angular movement of the ratchet wheels 72, 73 releases or engages the spring 78 on the hub 70a as required. For controlling the ratchet wheels 72, 73 there is employed an angle lever 94 pivoted at 93, Fig. 10, of which a tooth 94a engages in both ratchet wheels 72, 73, as shown in Fig. 9. A tooth 94b thereof extends into the path of a roller 95 on a disc 96 having at its periphery two ratchet notches 96a, 96b. Using a similar helical coil spring clutch as 78, this disc has a corresponding second substantially identical disc of slightly less outer diameter, which controls the coupling to a sprocket wheel 97 which is driven by a chain 71 also driving the sprocket wheel 70. A detent tooth 98a of a lever 98 pivoted at 99 engages the wheel 96a to hold the disc 96. The lever 98 is connected by a link 100 to a crank-pin 101 of a rotary magnet 102. A tension spring 103 is connected between the lever 98 and a lever 106 pivoted at 109 to the lever 94. One end of lever 106 co-operates with a fixed pin 107. Pivoted at 87 to the ratchet wheel 72 is an angle lever 89a, 89b. A pin 90 on the wheel 73 engages on the arm 89a of the lever, and the other arm 89b carries a coupling lug 92 which engages a toothed interrupter wheel 84 when the clutch 78 is engaged. The wheel 84 is rotatably mounted on a sleeve 82 fixed to a shaft 58, Fig. 7. One end 86a of a two-armed torsion spring 86 wound around the sleeve 82, is connected to a pin 85 on the wheel 84. The other end 86b passes within the range of movement of the pin 85 and is anchored to a radial pin 83 on the sleeve 82. In operation, the magnet 102 is energized, and the disc 96 allowed to rotate. The roller 95 causes the lever 94 to tilt, thereby disengaging the ratchet wheels 72, 73. Angular displacement of the ratchet wheels 72, 73 takes place due to the spring 74, Fig. 9. The lever 106 engages the pin 107, as shown in Fig. 10, and the lug 92 engages the interrupter wheel 84 causing it to rotate. The wheel 84 continues to rotate until the pin 85 engages the end 106b of the lever 106, whereupon the end 106a disengages from the pin 107, and the lever 94 tilts to engage the ratchet wheels 72, 73, as shown in Fig. 9. The lug 92 is also raised from the wheel 84, which can therefore be turned by the spring 86 to the initial position shown in Fig. 10, in which the pin 85 meets the arm 86b of this spring. The angle of rotation of the wheel 84 is determined therefore by the position of the pin 83, which can be varied by the rotation of the advancement setting knob 60, Fig. 7, fixed to the shaft 58.