GB749067A - Improvements in or relating to sheet separating machines - Google Patents

Abstract

749,067. Feeding sheets. BACKHOUSE, H. T. April 12, 1954 [April 14, 1953], No. 10190/53. Class 100 (1). Sheet-separators; faulty-feed control devices.- In sheet-separating apparatus wherein initially an edge portion of the top sheet is elevated from the pile, means is provided for detecting if two superposed sheets have been elevated and, if so, for stopping the separation of further sheets or operating a warning device. The invention is described as applied to apparatus disclosed in Specification 741,226 wherein suction grippers 140, carried on a sub-frame which descends as the pile 20 is consumed, raise and tauten the front edge 185 of the top sheet, and present it to mechanical grippers carried on upwardly moving chains. Prior to the transfer to the mechanical grippers, two devices each comprising a pair of jaws 300, 301 pivoted together at 302 in the manner of calipers are reciprocated on the sub-frame to the position shown. The jaw 300 passes beneath the sheet, and the jaw 301, which is initially open but is swung into closed position as it approaches the sheet, is separated from the bottom jaw by a distance of more than the thickness of two sheets. Each jaw is hollow and both are connected to a suction pipe 318, whereby if there are two superposed sheet portions 185, suction will build up in the system since the nozzle in each jaw will be sealed by a sheet. The application of suction to the nozzles in the jaws 300, 301 and the separators 140 is controlled by a rotary valve 320, 321 to which the main suction pipe 325 is connected. The rotor 321 has interrupted circumferential grooves therein whereby suction is established for predetermined periods to the pipes 318 and the pipes 329 of the separators, through pipes 324, 328 and an intermediate control device comprising a suction cylinder 330, piston 331, and rod 335. As shown, if suction builds up in the cylinder 330 due to two superposed sheets being separated from the pile 20 by the separators 140, the piston 331 is raised against the action of a spring 332, and, since the pipes 328, 329 communicate via a circumferential groove in the rod 335, the suction to the separators 140 is cut off. In this position, a flat portion 340 on the rod 335 vents the pipes 329 to atmosphere through an aperture 341 in the cylinder 330, and a latch 342 retains the piston in the raised position by engaging a groove in the rod. In addition, the separating apparatus as a whole may also be stopped by arranging the movement of the piston 331 (or a similar device connected thereto) to effect the tripping of the drive thereto e.g. as described in Specification 749,099, or to operate a switch in an electrically-operated driving clutch, or to operate a switch controlling a warning device. The invention may be applied to machines which operate to elevate the rear edges of the sheets, e.g. as described in Specification 427,041.