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EP-4577413-B1 - SHEET-FED ROTARY HAVING AN ELECTRODE UNIT

EP4577413B1EP 4577413 B1EP4577413 B1EP 4577413B1EP-4577413-B1

Inventors

  • Koch, Heinz Michael
  • Hoyer, Philipp
  • KÖHLER, Ulrich
  • SCHUBERT, WOLFGANG
  • SINGER, STEFAN

Dates

Publication Date
20260513
Application Date
20231108

Claims (15)

  1. Sheet-fed rotary printing press, wherein the sheet-fed rotary printing press has at least one coating unit (05; 06; 07) which has at least one impression cylinder (34; 61) and at least one further cylinder (33; 63) forming a contact zone (55) with the impression cylinder (34; 61) and designed as a transfer cylinder (33) or a coating forme cylinder (63), and wherein the coating unit (05; 06; 07) has at least one charging device (86) for electrostatically fixing sheets (B) to the impression cylinder (34; 61), which has at least one electrode unit (88) aligned and/or alignable on a lateral surface (87) of the impression cylinder (34; 61), and wherein a charge core zone (89) is a region (89) of a cylinder lateral surface (92) enveloping a cylinder barrel (91) of the impression cylinder (34; 61) closest to the at least one electrode unit (88), and wherein the charge core zone (89) is arranged, as seen in the direction of rotation (R) of the impression cylinder (34; 61), after the contact zone (55) and before a transfer point (101) leading away from the impression cylinder (34; 61), characterized in that at least one electrode (93) of the at least one electrode unit (88) has a minimum first distance (94) from the impression cylinder (34; 61) which is at least 4 mm and which is at most 13 mm, and in that the at least one electrode (93) of the at least one electrode unit (88) has a minimum second distance (96) from the further cylinder (33; 63) which is at least 4 mm and which is at most 35 mm.
  2. Sheet-fed rotary printing press according to claim 1, characterized in that at least one inspection system (97) is associated with the coating unit (05; 06; 07), which has a camera (99) aligned on an inspection zone (98) associated with the impression cylinder (34; 61), and in that the inspection zone (98) is arranged, as seen in the direction of rotation (R) of the impression cylinder (34; 61), after the contact zone (55) and before the transfer point (101) leading away from the impression cylinder (34; 61).
  3. Sheet-fed rotary printing press according to claim 2, characterized in that the charge core zone (89) is arranged, as seen in the direction of rotation (R) of the impression cylinder (34; 61), before the inspection zone (98).
  4. Sheet-fed rotary printing press according to claim 1 or 2 or 3, characterized in that the minimum first distance (94) is at least 5 mm or at least 7 mm or at least 9 mm.
  5. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4, characterized in that the minimum first distance (94) is at most 12 mm or at most 11 mm.
  6. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4 or 5, characterized in that the minimum second distance (96) is at least 5 mm or at least 7 mm or at least 9 mm.
  7. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that the minimum second distance (96) is at most 30 mm or at most 20 mm or at most 15 mm or at most 12 mm.
  8. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that an operationally applied and/or appliable working voltage of the electrode unit (88) is at least 2 kV.
  9. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that an operationally applied and/or appliable working voltage of the electrode unit (88) is at most 20 kV.
  10. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9, characterized in that at least one charging device (86) is circuit-technically connected to a superordinate machine control of the sheet-fed rotary printing press.
  11. Sheet-fed rotary printing press according to claim 10, characterized in that at least one charging device (86) is circuit-technically connected to the superordinate machine control of the sheet-fed rotary printing press in such a way that the operationally provided working voltage is applied to the at least one electrode (93) only when sheet run is activated.
  12. Sheet-fed rotary printing press according to claim 10 or 11, characterized in that at least one charging device (86) is circuit-technically connected to the superordinate machine control of the sheet-fed rotary printing press in such a way that settings concerning this charging device (86) can be made via an operating element of the sheet-fed rotary printing press.
  13. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12, characterized in that the impression cylinder (34; 61) is grounded via at least one carbon brush (112).
  14. Sheet-fed rotary printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13, characterized in that at least one electrode unit (88) is arranged movably between at least two positions and in that one of the at least two positions is a working position and another of the at least two positions is a rest position, and in that at least one first retaining element (102) is arranged for holding the electrode unit (88) in the working position.
  15. Sheet-fed rotary printing press according to claim 14, characterized in that an evasion force (K) is to be understood as a force (K) which is exerted directly or indirectly by the at least one electrode unit (88) on the at least one first retaining element (102), and in that the at least one first retaining element (102) only permits a movement of the at least one electrode unit (88) out of the working position caused by such an evasion force when this evasion force exceeds a first threshold value.

Description

The invention relates to a sheet-fed rotary printing press with an electrode unit according to the preamble of claim 1. In sheetfed offset printing presses, sheets are coated with a coating material, such as printing ink, in a contact zone between a transfer cylinder and an impression cylinder. Other coating units are also known, such as flexographic coating units, where the sheets interact directly with a forming cylinder and an impression cylinder. These are used, for example, as printing units or coating units. Depending on the properties of the coating material and the sheets, the sheets may adhere to the transfer cylinder or the forming cylinder. While the movement of the sheet's leading edge is largely determined by the grippers of the impression cylinder, the sheet can stretch considerably at the trailing edge and/or detach from the impression cylinder. As soon as the trailing edge of the sheet leaves the contact zone, an abrupt release movement of the sheet can occur. The trailing edge of the sheet may even temporarily overshoot its intended position on the cylinder circumference. This can negatively affect further sheet transport. It is particularly problematic, however, if an inspection system is installed, past which the sheets are transported while on the impression cylinder for inspection. The stretching and abrupt change in the bow's position makes evaluation difficult or impossible, especially in the rear area of the respective bow. Devices are known that use blown air and/or electrostatic charging to fix the sheets in the correct position on the counter-pressure cylinder. Through the US 3 346 253 A A sheet-fed rotary printing press is known which has an electrode unit in the area after the contact zone between the transfer cylinder and the impression cylinder, wherein this electrode unit is adjustable in its position by means of adjusting screws and is preferably arranged about two inches (5.08 cm) away from the impression cylinder. Through the US 3 342 129 A and the US 3 174 748 A A sheet-fed rotary printing machine is known which has an electrode unit in the area after the contact zone between the transfer cylinder and the impression cylinder in order to prevent smearing of printing ink. Through the DE 10 2008 001 165 A1 A sheet-fed rotary printing press is known in which sheets are electrostatically charged before the contact zone between the transfer cylinder and the counter-pressure cylinder in order to facilitate inspection after this contact zone. Through the DE 10 2010 003 046 A1 A sheet-fed rotary printing press is known which has a blowing device in the area after the contact zone between the transfer cylinder and the counter-pressure cylinder to facilitate inspection after this contact zone. Through the EP 2 982 510 A1 A sheet-fed rotary printing machine is known which has an inkjet module located in the area after the contact zone between the transfer cylinder and the impression cylinder and which has an electrostatic sheet guiding device within a housing of this module to facilitate inkjet printing and inspection within this module. Through the DE 100 33 839 A1 A sheet-fed printing press is known which can have a drying device at different locations, wherein for To support the drying process, an electrode is arranged whose distance to a counter-pressure cylinder can be changed to prevent a collision with a gripper system. Through the DE 100 41 934 A1 A sheet-fed printing machine is known which has a drying device, wherein an electrode is arranged to assist the drying process, the distance of which to a counter-pressure cylinder is a few millimeters. Through the WO 02/07977 A1 A sheet-fed printing machine is known that uses a combination of blown air and electrostatic charging to fix sheets in a suitable position on a counter-pressure cylinder in front of a printing gap. Through the DE 10 2005 031 498 A1 and the DE 12 86 051 B In each case a sheet-fed rotary printing machine is known, whose coating unit has a counter-pressure cylinder and a transfer cylinder forming a contact zone, as well as a charging device which has an electrode unit aligned with the counter-pressure cylinder, the charge core zone of which is arranged after the contact zone and before a transfer point. Through the WO 2020/074135 A1 A sheet-fed rotary printing machine is known, the coating unit of which has a transfer cylinder and a counter-pressure cylinder cooperating with it, wherein an electrode unit of a charging device is arranged aligned with a transport cylinder following the counter-pressure cylinder and wherein electrodes of the electrode unit have a minimum distance from this transport cylinder of at least 40 mm in order to avoid contact between the sheet and the transport cylinder. The invention is based on the objective of creating a sheet-fed rotary printing press with an electrode unit. The problem is solved according to the invention by the features of claim 1. According to the invention, a sh