Slidable Pressure Roller Crease Strength Optimization
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Solution Overview
Problem
Conventional sheet finishers with saddle-stitch functions face challenges in creating strong creases due to short pressing time and low pressing force, which affects the quality and productivity of the folding process.
Innovation Solution
A sheet folding apparatus with a folding unit, a pressing unit, and a control unit that allows the pressing unit to slide in a direction perpendicular to the sheet conveying direction, with the number of slides on each section of the folded side independently controlled based on distance from a reference position, enhancing the crease strength and reducing processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the set of sheets is pressed twice with multiple pairs of pressure rollers, then the crease strength is improved, but the pressing time remains short and the pressing force per unit area remains low
Solution Approach 1:
The pressure roller is made slidable along the folding line direction, transforming from a static pressing mechanism to a dynamic one. The roller slides along the folded side of the sheet set while maintaining pressing force, thereby extending the effective pressing duration without requiring multiple pressing cycles. This dynamic action allows continuous pressing along the entire folding line, solving the contradiction between short pressing time and insufficient crease strength.
2Ease of manufacture
If the pressure rollers nip the entire folded side at the same time, then the pressing operation is simplified, but the pressing force per unit area is distributed and remains low
Solution Approach 1:
The slidable pressure roller applies pressing force locally at different positions along the folding line sequentially. As the roller slides along the folded side, each section receives concentrated pressing force from the roller at that moment. This local quality approach concentrates the pressing force on small areas at any given time, significantly increasing the pressing force per unit area compared to distributed simultaneous pressing, while still covering the entire folded side through the sliding motion.
3Strength
If a slidable pressure roller is used to press the folded side while sliding perpendicular to the sheet conveying direction, then the crease strength is improved and the folded side thickness is reduced, but the sliding speed is slow due to screw rotation
Solution Approach 1:
The patent replaces the screw rotation mechanism with a more efficient driving mechanism. Instead of using screw rotation to drive the slidable pressure roller, the invention employs direct mechanical driving (such as a motor-driven belt or gear system) that can achieve faster sliding speeds while maintaining the pressing function. This substitution resolves the contradiction by eliminating the speed limitation inherent in screw mechanisms while preserving the beneficial pressing action along the folding line.
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 enables the creation of stronger creases with reduced thickness and increased productivity by optimizing the sliding pattern and speed of the slidable pressure roller, improving the overall sheet folding process.
Implementation Method 1
the slidable pressure roller slides on the folded side
Implementation Method 2
the folded side is pressed with the high pressing force. As a result, the strong crease is made on the set of sheets. Moreover, because the slidable pressure roller slides by the rotation of the screw, the folded side is pressed with the pressing force high enough and the crease strong enough is made on the set of sheets. This also results in decreasing a thickness of the folded side
Data Source
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AI summary
A folding unit (74, 81) folds a sheet. A pressing unit (525) presses a folded side of the folded sheet. A driving unit (501) causes the pressing unit (525) to slide in a direction perpendicular to a sheet conveying direction. A control unit (350) independently sets number of slides at which the pressing unit (525) is to slide on each of a plurality of sections of the folded side depending on a distance of each of the sections from a reference position, and controls the driving unit (501) so as to slide in each of the sections for the number of slides set for that section.