GB190209981A - Method and Apparatus for Preventing the Formation of Folds or Creases during Printing - Google Patents

Abstract

9981. Rich, H. April 30. Feeding sheets; lithographic and like printing.- Relates to a method and means for preventing the creasing of paper or cardboard during printing in lithographic or heliographic printing, bronzing, gumming, or varnishing machines. The sheet, after it is placed on the feed-board, is depressed at its front part midway between its side edges, before the grippers of the impression cylinder close on its front edge. This depression causes the front edge to be drawn back at the central part, so that the grippers close on the sheet at greater distance from its front edge at the side portions than they do at the central portion. The operation may be performed by hand, in feeding the sheets, or by mechanical means. Fig. 3 shows parts of a printing-machine, in which the sheet n is fed on the feed-board b to the front guides c, d, to be taken by the grippers f of the cylinder a. Before the grippers close on the sheet, it is pressed down evenly by the usual presserbar e. On this bar e is adjustably fixed a bar g, the end of which comes into contact with the centre of the free portion of the sheet n and depresses it, as shown, before the bar e presses on the sheet. In a modification, suitable for thick paper or card, the sheet is gripped at its sides, before the bar g presses on its central part, by toothed springs fixed on the ends of the presserbar e.