Sheet Processing Apparatus Fold Line Formation Mechanism
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Solution Overview
Problem
Conventional sheet processing apparatuses struggle to reduce the folded height of sheet bundles effectively due to the close superposition of sheets at fold lines, which limits deformation and crease formation, as the folding rollers hold the sheets tightly, preventing adequate space for deformation and resulting in insufficient creasing.
Innovation Solution
A sheet processing apparatus featuring a flexure forming unit that flexes sheets orthogonal to the conveying direction, a first pressing member pair to form fold lines, and a moving unit that adjusts the pressing position, allowing for the formation of two firm fold lines by creating spaces between adjacent sheets for deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the folding roller pair holds the entire region of the sheet bundle in the sheet width direction, then the sheet bundle is firmly held for folding, but the fold line portion only slightly protrudes from the nip part and sheets are closely superposed, preventing adequate deformation space
Solution Approach 1:
The invention divides the pressing function into two distinct stages: first the folding roller pair performs initial folding, then the additional folding roller performs secondary pressing. This segmentation allows each component to optimize its function - the folding roller pair provides firm holding while the additional folding roller provides focused pressing at the fold line to create adequate deformation space and improve crease quality.
Solution Approach 2:
The folding roller pair performs preliminary folding action before the additional folding roller applies pressure. This preliminary action creates the initial fold line structure, and then the additional folding roller reinforces it by applying pressure while the fold line portion protrudes, ensuring proper deformation space and crease formation.
2Device complexity
If additional folding is performed near the folding roller pair due to space constraints, then the apparatus structure is compact, but the sheet bundle is held by the folding roller pair when additional folding is performed, preventing fold line expansion
Solution Approach 1:
The additional folding roller is designed to be movable in the sheet width direction, allowing it to dynamically adjust its position. This enables the fold line portion to protrude adequately from the folding roller pair nip when pressing occurs, creating the necessary deformation space while maintaining a compact apparatus structure. The movability resolves the conflict between space constraints and fold line expansion requirements.
3Device complexity
If a single additional folding roller applies pressure on the fold line, then the apparatus structure is simple, but only one fold line is formed which prevents sufficient reduction of folded height
Solution Approach 1:
The pressing function is segmented into multiple stages using the folding roller pair followed by the additional folding roller. This sequential segmentation allows for the formation of multiple fold lines (initial fold by folding roller pair, reinforced fold by additional folding roller), achieving sufficient folded height reduction while keeping the overall apparatus structure relatively simple through functional division rather than simultaneous multi-roller complexity.
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 approach enables the formation of two firm fold lines, reducing the folded height of the sheet bundle and improving crease formation by providing necessary deformation spaces between sheets.
Implementation Method 1
a pair of folding rollers (hereinafter, 'folding roller pair') that are arranged to face each other across a transfer path of the folding plate and that sandwich the sheet bundle. The sheet surface is pushed by the folding plate to a sheet folding part and then the sheet bundle is conveyed with opposite side surfaces of the sheets at the folding position sandwiched by the folding roller pair, thereby folding the sheet bundle.
Implementation Method 2
Basically, folding of a sheet is achieved by deforming the sheet and breaking fibers of the sheet to form a crease on the sheet. Therefore, when the sheets are closely superposed one on top of another at the fold line of the sheet bundle, spaces for deforming the sheets are not provided between adjacent sheets, respectively, at the fold line.
Implementation Method 3
The sheet bundle having passed through the nip part of the folding roller pair tends to expand at the fold line due to firmness of the sheets.
Data Source
AI summary
A sheet processing apparatus includes a flexure forming unit configured to flex sheets to include a portion on which no fold line is formed in a direction orthogonal to a sheet conveying direction; a first pressing member pair configured to press a flexure portion of the flexed sheets to form a fold line thereon; and a moving unit configured to move a pressing position of the first pressing member pair in the direction orthogonal to the sheet conveying direction.