Sheet Processing Apparatus Fold Position Alignment
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Solution Overview
Problem
Conventional sheet processing apparatuses experience issues with improper folding due to deviations in the fold position from the nip of the conveyance roller pair, leading to the formation of box-folds when using a loop conveyance passage with curvature.
Innovation Solution
The apparatus includes a conveyor, a first folding roller, a second folding roller, a return conveyance passage with curvature, and a third folding roller. The second folding roller is positioned on the outer peripheral side of the return conveyance passage, and the third folding roller is positioned on the inner peripheral side, with the third folding roller conveying the sheet by a smaller amount than the second folding roller to align the fold position with the nip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a loop conveyance passage with curvature is used to convey the sheet, then the sheet can be conveyed through the folding process, but the fold position deviates from the nip of the conveyance roller pair causing improper folds and box-folds
Solution Approach 1:
The patent applies different conveyance amounts to different portions of the same sheet by using two separate folding rollers (second and third folding rollers) positioned at different locations. The second folding roller conveys the sheet by a first conveyance amount while the third folding roller conveys it by a second conveyance amount that is smaller. This local differentiation in conveyance behavior compensates for the curvature-induced deviation and maintains fold position accuracy.
Solution Approach 2:
The patent changes the conveyance parameter by using two different conveyance amounts (first conveyance amount and second conveyance amount) for different portions of the sheet. This parameter variation allows the system to compensate for the curvature effect in the loop conveyance passage, ensuring that the fold position aligns correctly with the nip of the conveyance roller pair despite the curved path.
2Ease of operation
If the sheet is conveyed through a curved return conveyance passage, then the folding process can be completed, but the conveyance distance varies depending on the portion of the sheet causing the fold to misalign with the nip
Solution Approach 1:
The patent addresses the non-uniform conveyance distance by applying different conveyance amounts to different portions of the sheet. The second folding roller (on the outer peripheral side) and third folding roller (on the inner peripheral side) create local quality differences in conveyance, allowing each portion of the sheet to be conveyed by the appropriate amount to reach the nip simultaneously.
Solution Approach 2:
The patent introduces asymmetry in the conveyance system by positioning the second and third folding rollers at different locations (outer peripheral side and inner peripheral side of the return conveyance passage) and assigning them different conveyance amounts. This asymmetric configuration compensates for the symmetric curvature of the loop conveyance passage, ensuring uniform effective conveyance across different sheet portions.
Data Source
AI summary
A sheet processing apparatus includes a conveyor, a first folding roller, a second folding roller, a return conveyance passage, and a third folding roller. The conveyor conveys a sheet along a main conveyance passage in a conveyance direction. The second folding roller facing the first folding roller across the main conveyance passage conveys the sheet by a first conveyance amount. The return conveyance passage having a curvature is branched from the main conveyance passage at a branching position and is merged to the main conveyance passage at a merging position. The third folding roller facing the second folding roller across the return conveyance passage conveys the sheet by a second conveyance amount smaller than the first conveyance amount of the second folding roller. The second folding roller is on an outer peripheral side and the third folding roller is on an inner peripheral side of the return conveyance passage.