GB726793A - Improvements in or relating to pressure sprayers in printing machines to prevent theset off of fresh printed sheets when leaving the machine - Google Patents

Abstract

726,793. Printing-machines. OTTE, K. July 11, 1952 [July 12, 1951], No. 17622/52. Class 100 (2). Set-off, preventing.-A powder spray for preventing set-off on freshly printed sheets is operated by a reciprocating part of the main printing-machine in such a manner that surplus powder on a printed sheet is removed by suction before the next sheet arrives. The apparatus comprises a blower 6 connected by a duct 9 to a powder container 14. A valve 28 is provided between the duct 9 and ducts 11 and 12 leading to the container 14. The valve serves to connect the duct 9 either to an outlet 8 or to the ducts 11 and 12 and is operated from the main machine by rotation by a string and pulley mechanism. Initially the valve 28 connects the duct 11 so that pressure air is directed over an opening 24 in the container 14, along tele. scopic duct 17, 18 to adjustable nozzles 20 over the sheet to be sprayed. Further movement of the reciprocating part of the main machine connects the valve also to the duct 12 which communicates directly with the container 14 so as to stir up the powder. The amount of air admitted through the ducts 11, 12 is controlled by regulator screws 23, 29. The cross-section of the opening 24 may be controlled by plate 26 turned by a handle 25. Further movement of the reciprocating part of the main machine rotates the valve in the opposite direction so that the ducts 12 and 11 are closed and the outlet 8 opened. The blower 6 then serves to suck the surplus powder from a hood 3 arranged over the delivery tray 2 through a duct 4 and filter 5, the air being expelled through the outlet 8. A bulb 32 may be provided in the container 14 so that the amount of powder therein is clearly visible.