GB809292A - Improvements in and relating to sheet feeding apparatus - Google Patents

Abstract

809,292. Feeding sheets. COURTAULDS Ltd. Jan. 10, 1957 [Jan. 11, 1956], No. 942/56. Class 100(1) Mechanism for feeding stacks of rigid sheets to a sheet separator operating at a uniform rate, has a low speed drive which corresponds to the rate at which the separator removes sheets from a stack, a detector arranged to engage a high speed drive when the last sheet of a stack has been separated, and a feeder adapted to disengage the high speed drive and engage the low speed drive upon a stack being presented to the separator. As shown in Fig. 1 a stack of sheets 1 on a conveyer 3 is presented to a pusher or cradle 4 which is pivotally mounted on a frame member 10 and which lifts the stack and presents them to rotating separator 6. The pusher is operated by a hydraulic ram 11. When the pusher is in its lowermost position it lies upon a bed 12 above which are supported two sets of rollers 13 placed between prongs 14 of the pusher 4. The pusher 4 depresses a spring-loaded stop 15 which operates a switch 16 causing the conveyer 3 to deliver a stack 1 on to the rollers 13. When the stack is in position it depresses a switch 17 which stops the conveyer 3, causes a feeler in the shape of a rectangular frame 18 to be raised by pneumatic cylinder 19 into the position shown in dash-lines in Fig. 1 and operates the ram 11 causing the pusher to rise at a high speed. When the leading sheet of the stack strikes the frame 18 the latter is moved against the action of the cylinder 19 until a cam 21 fixed to the frame, releases a switch 22 which admits air to the cylinder 19 causing the frame to swing to the position shown in full lines in Fig. 1 and also causes the speed of the pusher 4 to be reduced so that one sheet is presented to the separator 6 at each rotation. The separator 6 consists of a disc having a blade formed by cutting away a portion of the disc. Each separated sheet is guided by a plate 28 on to a belt 7. As the last sheet is fed to the belt 7 a member 29 on the pusher 4 strikes a switch 30 which causes the pusher to be returned rapidly to the bed 12 for the next stack. To control the cylinder 11 fluid from a tank is delivered at high pressure by way of one of two pipes 36, 37 selected by a four-way valve 38. Fluid is also continuously delivered to the ram by a metering pump 39 by way of a pipe 40. The valve 38 is operated two solenoids 41, 42. With the pusher 4 in the leading position operation of the switch 17 energizes the solenoid 42 and fluid is directed through a balance valve 43 and pipe 37 to the right-hand side of the ram 11, the fluid in the left-hand side of the ram escaping to the tank by way of pipe 36, valve 38 and pipe 45. The solenoid 42 is de-energized when the switch 22 is operated but fluid is still supplied to the right-hand side of the ram by the pump 39 for inching the pusher forward during sheet separation. When the switch 30 is operated the solenoid 41 is energized so that fluid is supplied to the left-hand side of the ram, the fluid in the right-hand side escaping by way of pipe 37, valve 43, valve 38 and pipe 45. The valve 43 is such that it will allow the escape of fluid from the right-hand side of the ram only when the pressure therein is greater than that developed by the pump 39. In a second embodiment (Fig. 6, not shown) the pusher 4 is replaced by endless chains carrying a plurality of cradles, one of which is loaded at the time when another has just presented a new stack for separation by the separator 6. The drive for the chains is effected by a slow motor which normally drives a shaft on which the chains are mounted but which is overridden by a fast motor by virtue of a free wheel when a projection of a cradle operates a switch. The fast motor is switched off when the switch 22 is operated by the cam on the frame 18. In a third embodiment (Fig. 10) a stack of sheets 2 on a conveyer 65 is turned on edge onto a conveyer 67 by a star wheel 66. The wheel 66 is mounted on the shaft carrying rollers 80 of the conveyer 67. The conveyer 67 is driven from a shaft 75 which may be clutched to run either fast or slow. A further conveyer 86 is provided which is driven from, and runs parallel with, the conveyer 67. Both conveyers slope upwardly and are provided with projections 84, 85 which engage the rear of the stack of sheets and advance it at a speed from the wheel 66 and slowly during sheet separation, separation being effected by a reciprocating' blade separator 68. The clutch controlling the speed of rotation of the shaft 75 is controlled by catch members operated by contact with a stack of sheets being advanced. Specification 549,610 is referred to.