Digital Printing Trays With Self-Closing Valves for Sheet Retention
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Solution Overview
Problem
Existing digital printing machines face challenges in efficiently transporting sheets of varying sizes without causing air leaks or significant air currents, particularly when smaller sheets are present.
Innovation Solution
The use of trays with a sandwich arrangement of plates and self-closing valves, where suction openings are on the upper plate, valve membranes are on the middle plate, and valve openings are on the lower plate, allowing for efficient sheet holding and air management through etched sheet metal construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-closing valves are used to prevent air leakage when transporting smaller sheets, then air leakage is reduced, but the device complexity increases due to the additional valve mechanism
Solution Approach 1:
The valve membrane automatically closes the valve opening when the suction opening is not covered by a sheet, and automatically opens when a sheet is placed on the tray. The system serves itself without external control mechanisms, using the presence or absence of the sheet to trigger the valve action.
Solution Approach 2:
The valve function is extracted as a separate membrane element that can independently respond to sheet presence. The membrane is connected to the tray structure but functions as an independent closing element that can be attached or detached based on operational needs.
2Manufacturing precision
If a sandwich arrangement of plates is used for tray construction, then manufacturing precision is improved through etched sheet metal, but the device complexity increases due to the multi-plate structure
Solution Approach 1:
The tray is divided into three separate plates (upper, middle, lower) that can be manufactured independently using etching processes. Each plate serves a specific function: the upper plate has suction openings, the middle plate has valve membranes, and the lower plate provides structural support and additional valve openings.
Solution Approach 2:
The tray uses a composite structure combining multiple sheet metal plates with different functions. The etched sheet metal provides both structural integrity and precise geometric features for suction openings and valve mechanisms.
3Reliability
If suction openings are continuously open for sheet transport, then sheet holding is effective, but air currents increase causing instability
Solution Approach 1:
The valve openings dynamically change from open to closed state based on sheet presence. When a sheet is on the tray, the valve openings remain open to allow suction. When no sheet is present, the valve openings automatically close to prevent air currents and maintain stability.
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
Enables the transportation of sheets of varying sizes with minimal air leakage and air currents, ensuring stable sheet retention and efficient air control.
Implementation Method 1
the valve openings 11 are connected to a vacuum generator and are subjected to vacuum V by the latter
Implementation Method 2
self-closing valves for suction air are formed on the plates... Each valve membrane 9 together with a valve opening 11 forms a self-closing valve which closes automatically when the associated suction opening 8 is not covered by the sheet 2
Implementation Method 3
Suction openings 8 are incorporated into the upper plate 5 to hold the sheet 2 in a regular distribution during transport
Data Source
Figure 1
Figure 2
AI summary
A digital printing press comprises trays for transporting sheets. The trays each comprise a sandwich arrangement of plates (5, 6, 7). Suction openings (8) for holding the sheets and self-closing valves for suction air, e.g., each with a valve membrane (9) and a valve opening (11), are formed on the plates (5, 6, 7).