Rotary Drum Sheet Handling with Meandering Air Flow Passage
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Solution Overview
Problem
High productivity printing systems with large drums face complexity and high air resistance issues, requiring powerful vacuum systems and increased operational costs due to friction and air leakage between the drum and shutter member.
Innovation Solution
A sheet handling apparatus with a rotary drum and stationary shutter member featuring a meandering air flow passage with protrusions and recesses, reducing air leakage and friction, and eliminating the need for a radial manifold, thus lowering air resistance and operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a large diameter drum is used to increase dwell time for heat exchange, then the dwelling time of sheets on the drum surface is sufficiently long for drying or cooling, but the device complexity and air resistance increase
Solution Approach 1:
The drum surface is segmented into multiple chambers distributed over the periphery, with each chamber having its own suction connection. This segmentation allows for localized control of suction in different angular positions, enabling efficient sheet handling without requiring an excessively large drum diameter.
Solution Approach 2:
The suction force is made dynamically controllable through the shutter member that can selectively block suction openings in different chambers at different angular positions. This dynamic control allows optimization of suction timing and location, improving sheet handling efficiency without increasing drum size.
2Productivity
If a segmented drum with radial manifold is used, then sheets can be handled in high productivity systems, but the air resistance between suction system and vacuum holes is relatively high
Solution Approach 1:
The radial manifold is completely removed from the design. Instead, each chamber is independently connected to the suction system through its own suction opening in the drum flange. This eliminates the long radial air passages through the manifold, dramatically reducing air resistance and the power required to drive the vacuum system.
Solution Approach 2:
The suction connections are moved from a radial configuration (through the drum wall and manifold) to an axial configuration (through the drum flange). This dimensional change creates much shorter and more direct air passages from the vacuum holes to the suction system, reducing air resistance.
3Force
If a powerful vacuum pump is used to overcome high air resistance, then sufficient suction force is achieved at vacuum holes, but operational costs increase
Solution Approach 1:
The design optimizes the pneumatic circuit by eliminating the radial manifold and directly connecting each chamber to the suction system through the drum flange. This creates efficient air flow paths with minimal resistance, allowing the use of a smaller, more energy-efficient vacuum pump while maintaining sufficient suction force for high productivity operation.
4Use of energy by moving object
If friction between drum and shutter member is reduced, then power consumption decreases, but air leakage between drum and shutter member increases
Solution Approach 1:
The mechanical contact between the drum and shutter member is replaced with a magnetic coupling system. The shutter member is magnetically attracted to the drum surface without physical contact, eliminating friction while preventing air leakage through the magnetic field. This substitution resolves the contradiction between reducing friction and preventing air leakage.
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
The solution reduces air resistance, allowing for stronger sheet holding and minimizing sheet deformation, increasing productivity and print quality while lowering power consumption and maintenance costs.
Implementation Method 1
a suction system for controlling a flow of air through the perforations of the drum, thereby to attract sheets to the peripheral wall of the drum
Implementation Method 2
The narrow passage comprises a large air resistance greatly reducing the amount of air leaking into the drum
Implementation Method 3
As the sheets come into intimate contact with the peripheral wall of the drum, the heat conductivity of that wall may be utilized for controlling the temperature of the sheets, i.e. for heating or cooling them
Data Source
AI summary
A sheet handling apparatus for a printing system includes a rotary drum having an inner chamber circumferentially surrounded by an outer peripheral wall with perforations formed therein. By means of sucking an air flow through the perforations of the drum to a suction system, sheets are attracted to the peripheral wall of the drum. A stationary shutter member is positioned inside the inner chamber for blocking the flow of air through the perforations when they pass, with the rotation of the drum, through a first predetermined angular range. The shutter member includes protrusions while the rotary drum includes recesses for receiving the protrusions, such that a meandering air flow passage is formed between the shutter member and the rotary drum. As such, friction between the rotary drum and the stationary shutter member is reduced, thereby reducing the power consumption of the suction system.