De La Rue Giori S.a.

Joachim A Lapp

Johannes Georg Schaede

Albrecht J Germann

Hans B Bolza-Schunemann

Alfred Walter Weiler

The draw roller is designed as a suction roller with a rotatable roller casing having orifices, and the material web loops around the draw roller along a circumferential portion. The internal suction-air supply connectable to a negative-pressure source opens out on the inner circumference of the roller casing and is designed so that a stationary suction surface of wedge-shaped form is obtained on the casing circumference. The wedge tip is directed opposite to the direction of rotation of the roller casing and is located at the start of said circumference portion in the roller center. The suction surface widens obliquely outwards on both sides with an increasing looping angle and, at the end of the circumferential portion, has a width corresponding to the total width of the material web.

Draw roller for the transport of a material web, particularly a paper

The printing unit has two cooperating cylinders (1, 4) which form the printing nip and which have printing saddles (2, 5) separated by cylinder pits (3, 6). The paper web (7) passing through the printing nip is transported in the pilgrim-step mode, in order to print formats adjoining one another. The two cylinders (1, 4) are angularly adjustable relative to one another, in respect of the position of their printing saddles (2, 5) cooperating in the printing nip, in a manner offset by the amount of a circumferential distance which is approximately equal to the difference between the circumferential length (S) of a printing saddle and the circumferential length (B) of a printing image. The impression zone is therefore only approximately as large as the printing image, and the impression-free zone available for retracting the paper web is correspondingly enlarged.

Printing unit for a web-fed printing machine

The draw-roller unit has only one suction roller (20b, 21b) as a draw roller, in which a constantly acting suction effect is effective along that circumferential portion round which the paper web is looped, whilst the remaining circumferential portion experiences no suction effect. The suction roller has a fixed hollow roller core (65) and a roller casing (61) rotatable about this and consisting of plastic-impregnated carbon fibres, with suction ports (62) distributed over its circumference. The roller core (65) is equipped, on its one side, with an axial connection piece (68b) for fastening to the machine stand and for connection to a vacuum source, on its other side with a bearing journal (66) and, on its circumference having passage orifices (70) with two radial partition walls (69) which are arranged at a specific angular distance from one another and which enclose a suction chamber between them. The roller casing is mounted on the bearing journal (66) a conical connecting flange (61b) fastened directly to the rotor shaft of the drive motor and is mounted with its other end on the connection piece (68b), the gaps between roller casing and partition walls (69) being approximately airtight. Instead of a suction roller, a draw roller subjected to compressed air on the outside along the circumferential portion can also be provided, or else the suction-air and compressed-air effects are combined.

Draw-roller unit for a web-printing machine

The rotary web-fed printing machine has three successively arranged printing units, namely one offset and two intaglio printing units which are all of a similar design to sheet-fed printing units and in which the cylinders (2, 3) forming the printing nip have a plurality of sectors separated by cylinder pits (2a, 3b). Each printing unit has, in front of the printing nip, a first paper-web store (29) and an intermittently controllable first draw-roller unit (30) and, after the printing nip, an intermittently controllable second draw-roller unit (31) and second paper-web store (32), the draw-roller units (30, 31) which have only one suction roller being controllable for the forward and backward movement of the web (P) by means of individually regulated drives (30a, 31a) and at the same time serving for the register check. In front of the first paper-web store (29) of the first printing unit (A), between the printing units within the portions limited by the respective paper-web stores and behind the second paper-web store of the last printing unit, the web (P) is moved uniformly by continuously driven draw-roller arrangements (27), whereas during the run through the printing nip the paper-web transport takes place in the pilgrim-step mode.

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Margetshochheim, Germany

Joachim A Lapp