Patent GB-668549-A (GB)
Title: Improvements in or relating to a duplicating machine including a rotatable drum
IPC: B41L3/00
Filed: 1949-02-11
Abstract: 668,549. Rotary duplicators. DITTO, Inc. Feb. 11, 1949 [Feb. 28, 1948; March 1, 1948], Nos. 3804/49 and 3805/49. Class 100 (ii). [Also in Group XXXV] The rotatable drum carrying the master sheet in a rotary duplicator is driven by a motor through an electromagnetic clutch. An electromagnetic brake is adapted to stop the drum. As shown, the duplicator 21, Fig. 1, is mounted on a stand 20 in which is a motor 43 provided with a shaft 45, Fig. 8, on which is freely mounted a pulley 46 having integral therewith a cylindrical armature clutch portion 50 surrounding a rotor 49 keyed to the shaft. When a field winding 55, Fig. 13, on the rotor is energised through brushes 56, 57 and commutators 58, 59, the pulley is driven. An electromagnetic brake comprising a fixed ring portion 63 surrounding the armature 50 is adapted to be energised by a field coil 64 to brake the armature and pulley. The pulley 46 is connected by a belt 47 to a pulley 48 fixed on a shaft to which is secured a further pulley 37, the latter being connected by a belt 36 to a pulley 34, Fig. 1, fixed on the shaft 35 of a drum 29 carrying the master sheet. The duplicator 21 is of known type generally, and comprises a platform 30 along which the paper sheets are fed between a pair of driven feed rolls and then between a platen roll and the drum 29. The upper feed roll is damped. The drum 29 may be rotated continuously on the operation of a hand switch 79. Further, depression of either of two foot buttons 68, Fig. 1, and 69 (not shown) causes a common shaft 71 to be rotated which is adapted to move a circuit breaker 75, Fig. 1, to open a normally-closed switch 76, Figs. 1 and 13, and depression of a treadle 80 causes rotation of a shaft 81 which moves a switch contact 84 from position 88 to position 89, these switches, respectively, as described below, causing one complete revolution of the drum 29, and bringing the drum to master sheet attaching position. Means for releasing the master sheet on the drum 29 comprises a bell-crank lever 92, pivoted at 93 on the frame 28, and adapted to be rocked by a Bowden cable means 95, 97 on depression of the treadle 80 to swing a pivoted arm 99 which, through pin-andslot means 102, 103, Fig. 9, is adapted to swing an arm 104 about a shaft 105. This arm 104 can engage an arm 107 secured at one end of a shaft 106, mounted transversely of the drum 29, to rock this shaft whereby a pair of spaced levers 108 secured to .the shaft urge outwardly the clamp 147 to release the master sheet. The arm 104 opens the clamp 147 in the master sheet changing position of the drum 29. An alternative arrangement whereby the master sheet is released before the changing position, comprises an arm 111, pivoted on the frame 28, and adapted to be rocked by a link 115 connected to the arm 99 to engage the arm 107 to release the clamp just after it has passed the platen roller. The drum 29 continues rotation beyond this point, and the master sheet is thrown clear of the drum into a discharge tray. The clamp 147 is again opened by the arm 104 in the changing position to receive another master sheet. The lever arm 99 can be manually operated to release the clamp 147. The pulley 34, secured to the shaft 35 of the drum 29, has secured thereto a cam 119, Fig. 13, having a single lift adapted to rock bell-crank levers 124, 125 to cause normally-open switches 132, 133, respectively, to be closed. Provision is made for adjusting the positions of these bell-crank levers. As described below, the switches 132, 133 determine, respectively, the " home " and master sheet attaching positions of the drum. The A.C. motor 43, Fig. 13, is of the induction type supplied from the mains 150. A transformer 154 and a rectifier 161 convert the current into D.C. for the clutch &c. With the switch 153 closed, the motor rotates, current passes through line 60, clutch winding 55, line 61a, rheostat 162, switch 163, and line 61, and the drum 29 is rotated through the energised clutch described above until it approaches home position. A relay coil 165 becomes energised to pull a switch 169 downwardly, this switch, being connected to the switch 163, opening the latter to cause the clutch winding 55, to be de-energised and the brake winding 64 to be energised. The drum 29 is therefore brought to rest at the home position ready for printing. The relay 165 is in a. circuit including line 173, foot-operated switch 76, manually-operated switch 79, lines 175, 176, foot-operated switch 84, either switch 132 or 133 (according to position of switch 84), and line 177. Just before the drum reaches home position, the cam 119 closes the switch 132 to energise the relay 165 which pulls down the switches 163, 169 and holds them even when the switch 132 is opened by further rotation of the cam 119 to home position. To effect one complete rotation of the drum 29, one of the foot buttons 68 or 69 (not shown), is momentarily depressed to deenergise the relay 165 whereby the switches 163, 169 rise, and the .motor 43 is operated as described above. For continuous operation of the drum, the manual switch 79 is opened so that the relay 165 cannot function. The rheostat 162 allows the drum speed to be varied. The drum is stopped by the switch 133 before reaching home position when a new master sheet is to be attached. By depressing and holding down the treadle 80 and momentarily depressing the foot button 68, the switch contact 84 is moved to the lower position 89, and the cam 119 operates the bell-crank lever 125 to open the switch 133 to energise the relay 165. In this new position, the clamp 147 for the master sheet is opened, and the master sheet is thus automatically released and thrown clear of the drum on to the discharge tray.