Electrostatic Sheet Guidance in Sheet-Fed Printing Presses
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Solution Overview
Problem
Sheet-fed printing machines face challenges in maintaining print quality due to sheets lifting off or whipping during transport, causing fluctuations in distance between print heads and the surface, leading to reduced quality and potential disruptions in printing, especially with the integration of printing formeless devices like inkjet or laser systems.
Innovation Solution
Integrating an electrostatic device to charge the sheets, ensuring they adhere to the surface guiding them past printing formeless devices, combined with a blowpipe to prevent unwanted movements and ink smearing, and using a deionizer to minimize disruptions during transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If sheet guide rollers are used to fix printed sheets on the impression cylinder surface, then sheet stability is improved, but print quality deteriorates due to marks on the printed surface and limited printable width
Solution Approach 1:
The patent replaces mechanical sheet guide rollers with an electrostatic field-based sheet guiding system. An electrostatic device charges the impression cylinder surface, creating electrostatic attraction that holds the printed sheet without physical contact. This eliminates mechanical marks on the printed surface while maintaining sheet stability, and allows the entire sheet width to be printed without obstruction from guide rollers
Solution Approach 2:
The patent introduces an electrostatic field as an intermediary between the impression cylinder and the printed sheet. The electrostatic device creates a charged surface on the cylinder that attracts and holds the sheet through electrostatic forces, serving as a non-contact mediator that stabilizes the sheet without requiring physical guide elements that would leave marks or limit printable area
2Stability of the object's composition
If the printing formeless printing device is arranged in the printing nip area, then sheet guidance is improved, but print quality deteriorates due to sheet whipping at the trailing edge
Solution Approach 1:
The patent replaces mechanical sheet guidance systems with an electrostatic field-based guidance system. The electrostatic device charges the impression cylinder surface, creating continuous electrostatic attraction that stabilizes the entire sheet including the trailing edge, preventing whipping and distance fluctuations without requiring physical guide rollers that would interfere with printing
3Stability of the object's composition
If sheet guide rollers are used to prevent sheet whipping, then sheet stability is improved, but the printable width is reduced due to coverage of sheet areas
Solution Approach 1:
The patent replaces physical sheet guide rollers with an electrostatic field-based sheet holding system. The electrostatic device creates a charged surface on the impression cylinder that attracts and stabilizes the entire sheet without physical contact. This eliminates the need for guide rollers that would occupy space and prevent printing across the full sheet width, allowing the printing formeless device to print across the entire printable area
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution maintains sheets at a precise distance from print heads, ensuring consistent print quality across the entire sheet width and length, preventing print quality issues and allowing for high-quality digital printing systems in sheet-fed presses.
Implementation Method 1
an electrostatic device (7) is provided in the transport direction of the printed sheet in front of one or all printing formeless printing devices (8) by means of which a charge can be introduced into the sheet to be printed (B) so that it adheres to the surface guiding it
Implementation Method 2
a blowpipe (6) is provided in order to prevent unwanted movements
Implementation Method 3
a deionizer (9) is provided downstream of the printing formeless printing device (8) in the working direction (A) of the inkjet print head (8) by means of which charge can be removed from the printed sheet (B)
Data Source
Figure 1~2
Figure 3
AI summary
The sheet-fed-printing machine has a sheet feeder, a printing mechanism and coating unit for printing on the printing sheet (B) with a statistical printing image identical for all printing sheets. An ionization device (7) is arranged in sheet travel direction (A) and towards a column (5) formed by a pressing device (4) and cylinder guiding the sheets and is arranged in front of the informal pressure device (8) against the surface of the cylinder guiding the sheets.