Sheet Stacker Guide Speed Control for Jam Prevention
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Solution Overview
Problem
In sheet stackers, sheet conveyance is hindered due to sheet bundle curl, causing jams when sheets move from the conveying member to the load tray.
Innovation Solution
A sheet stacker design that includes a load table, a conveyor, a guide with holders to hold and move sheets, and a leading-end alignment mechanism with a partition to align sheet ends, all controlled by circuitry to differentiate conveyance speeds and prevent sheet inflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guide accelerates to increase speed difference for reliable sheet detachment, then sheet detachment reliability improves, but sheet conveyance stability deteriorates due to curl-induced jams
Solution Approach 1:
The guide performs preliminary alignment of the sheet leading end before acceleration-induced detachment. The partition member prepositions the sheet at the correct location, and only then does the guide accelerate to create speed difference for detachment. This sequence ensures both stable conveyance during alignment and reliable detachment when needed.
Solution Approach 2:
The sheet handling process is segmented into distinct phases: (1) preliminary alignment phase where the guide moves at matched speed to position the sheet leading end using the partition member, and (2) detachment phase where accelerated speed difference causes separation. This segmentation allows optimization of each phase independently.
2Ease of operation
If the guide moves at matched speed to maintain sheet position, then sheet conveyance stability improves, but sheet detachment reliability deteriorates
Solution Approach 1:
The guide's speed is dynamically adjusted through two distinct modes: matched speed mode for stable conveyance and alignment, and accelerated mode for detachment. The system transitions between these dynamic states based on the operational phase, allowing both stability and reliability to be achieved at appropriate times.
3Productivity
If sheets are stacked densely to increase productivity, then stacking efficiency improves, but sheet curl increases causing conveyance jams
Solution Approach 1:
The guide mechanism extracts the sheet from the bundled stack by creating speed difference between the guide and conveyor. This extraction action removes sheets one by one from the bundle, preventing the accumulation of curl-induced jams while maintaining efficient stacking throughput.
Data Source
AI summary
A sheet stacker includes a load table to stack a bundle of sheets; a conveyor to convey a sheet to the load table in a conveyance direction at a conveyance speed; a guide including a holder to: hold a leading end of the sheet conveyed by the conveyor by the holder at a standby position; and move the holder to guide the sheet along a movement path in the conveyance direction at a moving speed while holding the sheet by the holder; and a leading-end alignment mechanism including a partition extending to the movement path of the holder, the leading-end alignment mechanism to align, in the conveyance direction, a leading-end position of the sheet on the load table; and circuitry configured to differentiate the conveyance speed of the conveyor and the moving speed of the holder.