Relaxation Curve Sheet Feeder Guide for Jam Reduction
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Solution Overview
Problem
Sheet jams occur due to high frictional forces at the boundary between linear and curved sections in sheet feeders, caused by drastic changes in acceleration as sheets transition from linear to curved paths.
Innovation Solution
The use of guide portions shaped as relaxation curves, specifically clothoid curves, in sheet feeders to gradually change the sheet's direction, reducing the drastic acceleration and frictional forces experienced by the sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a guide portion with constant radius of curvature is used to turn the sheet, then the structure is simple, but a great acceleration is applied to the sheet at the boundary between linear and curved sections, causing increased frictional force and sheet jams
Solution Approach 1:
The guide portion is designed with a variable curvature profile (relaxation curve) instead of a constant radius of curvature. The curvature radius gradually changes from large to small values along the sheet feeding path, which gradually increases the acceleration applied to the sheet and prevents sudden frictional force spikes that cause sheet jams.
Solution Approach 2:
The curvature radius parameter of the guide portion is changed along the feeding path. By making the curvature radius variable rather than constant, the acceleration profile is optimized to increase gradually, preventing the sudden frictional force increase that occurs with constant radius curves and thereby improving sheet feeding reliability.
2Volume of moving object
If the curvature radius of the turn-around section is reduced to compact the structure, then the device size is reduced, but the acceleration and frictional force increase, leading to sheet jams
Solution Approach 1:
The guide portion employs a relaxation curve with variable curvature that allows the sheet path to be compact while gradually increasing the curvature. This gradual curvature increase prevents sudden acceleration spikes and frictional force increases, maintaining sheet feeding reliability even in a compact device configuration.
Solution Approach 2:
The curvature radius parameter is varied along the feeding path to optimize both compactness and reliability. By controlling how the curvature radius changes along the path, the design achieves a compact form factor while preventing the acceleration and frictional force spikes that would cause sheet jams.
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 design effectively suppresses the rise in acceleration and frictional forces, preventing sheet jams and reducing manufacturing costs by stabilizing the sheet feeding process.
Implementation Method 1
A frictional force caused by contact between the guide portion and the sheet is generally proportional to a normal force applied to a contact surface therebetween. Further, the normal force is generally proportional to an acceleration applied to the sheet in a direction perpendicular to the sheet.
Implementation Method 2
The acceleration is generally inversely proportional to the curvature radius of a feeding path. Therefore, if a sheet having been fed on a linear feeding path is turned around, a great acceleration is applied to the sheet when transferred from the linear section onto the turn-around section.
Data Source
AI summary
A sheet feeder is provided that includes a feeding unit configured to feed a sheet through a feeding path and a guide portion that is bent in a shape of a relaxation curve and configured to feed the sheet thereon and turn a feeding direction of the sheet.