Sheet feeder

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The sheet feeder is a term from printing technology and refers to a person or device that feeds the sheets to the machine or system.

person

At the end of the 19th century, high-speed presses were built in which people inserted the sheets one by one. The company Schnellpressenfabrik Bohn & Herber was well known .

Device or unit

In sheet-fed printing machines, but also on punching and embossing machines, the devices are so-called that separate the sheets from the stack and transfer them to the next unit . The sheet feeder was invented by Caspar Hermann in 1909 . It is between single-sheet feeder and stream feeder distinguished.

Single sheet feeder

Here, the individual sheet is fed to the feed table on the printing unit by being lifted by several suction cups near the front edge and taken over by feed grippers or conveyor belts. These transport devices bring the sheet to the front and side marks , which are used for its exact alignment. The advantage of the single sheet feeder is that it is easier to adjust to the paper size and type.

Shed feeder

The shingle feeder transfers sheets that are shingled to the following unit. A suction head (also suction lock or sheet separator) separates the sheet at its end from the paper stack. Then lifting suction devices lift the end of the sheet, supported by blown air and scrapers. Clocked air is now blown between the sheets and makes the entire top sheet float. This is fed to the imbricated flow with suction cups. The speed of movement of the imbricated flow through the overlapping of the individual sheets corresponds to about a third of the printing speed. The shingled stream enables a high printing speed and is the prerequisite for the required precision when aligning the sheets at the front and side marks.

Individual evidence

  1. ↑ Rudi Riedl, Dieter Neumann, Jürgen Teubner: Technology of offset printing. VEB Fachbuchverlag Leipzig, Leipzig 1989, ISBN 3-343-00527-4 , p. 125ff.

literature

  • Helmut Kipphan (Hrsg.): Handbuch der Printmedien. Technologies and production processes. Verlag Springer, Berlin et al. 2000, ISBN 3-540-66941-8 .