Patent GB-700130-A (GB)
Title: Apparatus for the feeding of magnetic sheet material
Inventor: FOWLER ALEXANDER
IPC: B21D43/24
Filed: 1951-08-01
Abstract: 700,130. Feeding sheets. HERCULES ELECTRIC & MANUFACTURING CO., Inc. Aug. 1, 1951, No. 18255/51. Class 100 (1) Sheet separators and forwarders.- Apparatus for separating and successively feeding magnetically responsive sheets from a stack of sheets 14 comprises a support 12 for the sheets and an induction coil 16 for separating the sheets surrounding the stack with the axis of the coil extending generally in the direction of the plane of the sheets and generally perpendicular to the desired direction of separation of the sheets. The coil 16 is energized in order to move and separate an end sheet 22, a magnetic feed roller 24 feeding the sheet away from the stack. The support for the sheets includes adjustable guides 30 and front stops 36. The feed roller 24 is magnetized by means of a coil 42 and is driven through a magnetic clutch 26 by a motor 28 which also continuously drives rollers 25. In operation a switch 52 is first closed thereby energizing a time delay relay 58 which on operation energizes a relay 64 to complete a circuit through a rectifier 48 to the coil 16. The sheet 22 thus flies upwardly so that it engages a feeler 44 to make a contact 46 thereby energizing a relay 54, energization of which causes de-energization of the coil 16 and energization of the coils of the roller 24 through a rectifier 50 so that the sheet 22 is held against the roller. Coils 74 and 78 of time delay relays 76 and 80 respectively are also energized. The return path for the current through the coil of roller 24 at this time includes two branches in parallel through adjustable resistors 92 and 98. Relay 80 then opens its contact thereby disconnecting the path through resistor 98 so as to weaken the magnetization of roller 24 so that in the event of two sheets being held by it one will now fall back. Relay 76 now closes its contact to energize relays 112 and 116 the former effecting a short circuit of the resistor 92 so that the roller 24 is fully magnetized and the latter effecting operation of the magnetic clutch 26 so that roller 24 starts rotating to feed the sheet to rollers 25. As soon as the sheet leaves the feeler 44 contacts 46 are broken and the circuit is returned to its initial state the coil 16 being again energized after the time delay introduced by relay 58 which ensures that the trailing edge of the sheet 22 is clear of the apparatus before the coil 16 is energized. Two coils may be provided to ensure separation of both leading and trailing edges, Fig. 4 (not shown) and as an alternative to the time delay relay 58 two feelers operating switches in parallel may be used one in front of and one behind the roller 24, Fig. 5 (not shown). When only one coil 16 is used a compressed air or electrically operated hold-down device may be provided for the trailing edges of the sheets to prevent slipping. The hold-down device is rendered operative at the same time as the coil 16, the air supply to the air cylinder, when the device is air operated, being controlled by a suitable solenoid operated air valve. The support 12 may be movable vertically so as to keep the topmost sheet at a constant distance from the roller 24 and the coil 16 and roller 24 may also be energized by A.C. instead of D.C., particularly when the support 12 is fixed. Electronic relays may be employed instead of mechanical ones. Faulty feed control devices.-In the event of two sheets being fed between rollers 25 a switch 29 is operated to break the circuit to the magnetic clutch 26 and thus stop the roller 24.