Sheet Folding Apparatus with Downstream Sensor for Accurate Positioning
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Solution Overview
Problem
Conventional sheet folding apparatuses struggle to maintain precise control over the position of the folded part in the sheet conveying direction due to variations in sheet behavior between rollers, leading to inconsistent folding results.
Innovation Solution
The apparatus employs a sheet leading end detection sensor positioned downstream of the conveying rollers to control the sheet's protrusion and folding, ensuring accurate positioning by adjusting the timing of the folding process based on the detection timing and sheet characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sheet leading end detection sensor is positioned upstream of the conveying rollers and stopping is based on predetermined time after detection, then the apparatus structure is simple, but the protrusion amount varies due to sheet behavior variations, resulting in poor folding precision
Solution Approach 1:
The patent inverts the conventional sensor positioning by placing the detection sensor downstream of the conveying rollers instead of upstream. This reversal allows the system to detect the leading end of the sheet at a location where the sheet has already been conveyed, enabling more accurate control of the protrusion amount by directly measuring the sheet's actual position rather than estimating it based on timing from upstream detection.
Solution Approach 2:
The patent implements feedback control by using the detection timing from the downstream sensor to dynamically adjust the stopping control of the conveying rollers. The control unit receives real-time detection information about the sheet's leading end position and uses this feedback to precisely control when to stop the rollers, ensuring the sheet protrudes by the exact predetermined amount required for accurate folding.
2Device complexity
If the sheet is held only by the upstream conveying rollers during travel, then the apparatus structure is simple, but the sheet behavior varies depending on stiffness and curling, causing timing variations in reaching the downstream rollers
Solution Approach 1:
The downstream detection sensor provides feedback on the actual arrival time and position of the sheet's leading end, allowing the control system to compensate for variations in sheet behavior. This feedback mechanism enables the system to adapt to different sheet characteristics (stiffness, curling) and maintain consistent folding accuracy despite the simple upstream-only holding mechanism.
3Manufacturing precision
If the detection sensor is positioned downstream of the conveying rollers, then the detection timing accurately reflects the sheet's actual position for precise protrusion control, but the apparatus requires more complex control logic
Solution Approach 1:
The control unit uses feedback from the downstream detection sensor to precisely determine when to stop the conveying rollers. By receiving real-time detection signals about the sheet's leading end position and using this information to control the roller stopping timing, the system achieves accurate protrusion amount control despite the increased control logic complexity.
Solution Approach 2:
The system uses the sheet's own passage through the detection sensor to trigger the stopping action. The sheet itself provides the timing signal through its interaction with the sensor, eliminating the need for external timing mechanisms or complex predetermined calculations, thereby simplifying the control logic while maintaining precision.
Data Source
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AI summary
A sheet folding apparatus (1) includes: a folded part forming unit (12, 13) that forms a folded part on the sheet (P) by nipping a curved portion formed on a part of the sheet (P) between an upstream first sheet conveying unit (11) and a downstream second sheet conveying unit (13, 14) by holding a part of the sheet (P) by the first sheet conveying unit (11) and applying conveying force to the sheet (P) to reverse the sheet (P) upstream by the second sheet conveying unit (13, 14); and a sheet leading end detection unit (22) disposed downstream of or at almost same position as the second sheet conveying unit (13, 14). The sheet (P) is conveyed based on a detection timing of the sheet leading end detection unit (22) such that the leading end of the sheet (P) protrudes by a predetermined protrusion amount from the second sheet conveying unit (13, 14) immediately before applying conveying force to the sheet (P) to reverse the sheet (P).