Two-Stage Skew Correction for Sheet Conveying Apparatus
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Solution Overview
Problem
Existing sheet conveying apparatuses face challenges in accurately correcting skew and misalignment of various sheet types, particularly with thick paper and large sizes, due to increased conveying load and size constraints, leading to deteriorated skew correction accuracy and increased apparatus size.
Innovation Solution
A sheet conveying apparatus that performs two-stage skew correction, with a first stage for rough correction and a second stage for high-precision correction, using a skew detection unit and skew correction unit with adjustable conveying velocities and forces to minimize slip and improve accuracy, even with a bent conveying guide and diverse sheet types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-stage skew correction method is used, then the apparatus size can be reduced, but the skew correction accuracy deteriorates for thick paper and large sizes
Solution Approach 1:
The skew correction process is divided into two distinct stages: a first skew correction operation for rough correction and a second skew correction operation for high-precision correction. This segmentation allows each stage to be optimized independently, with the first stage handling bulk correction and the second stage refining the alignment, thereby achieving high accuracy without requiring an overly complex single-stage system.
Solution Approach 2:
The first skew correction operation performs preliminary rough correction before the second operation. By preparing the sheet in advance through the first correction stage, the subsequent second stage can focus solely on high-precision refinement, improving overall accuracy while simplifying the control requirements for each individual stage.
2Productivity
If conveying velocity is increased to reduce paper interval, then productivity improves, but slip increases during skew correction
Solution Approach 1:
The conveying velocity is dynamically adjusted based on the correction stage. During the first skew correction operation, a first conveying velocity is used for rough correction, while during the second operation, a second conveying velocity is used for high-precision correction. This dynamic velocity adjustment allows the system to maintain high productivity overall while ensuring accuracy during the critical second correction stage.
Solution Approach 2:
The skew correction process operates in periodic cycles with distinct velocity profiles. The system alternates between the first conveying velocity for rough correction and the second conveying velocity for precision correction, creating a periodic action pattern that balances productivity and accuracy across multiple correction cycles.
3Manufacturing precision
If force applied during correction is increased to improve correction effect, then skew correction accuracy improves, but conveying load increases
Solution Approach 1:
The correction force is segmented into two distinct operations: a first correction operation with a first force level for rough correction and a second correction operation with a second force level for high-precision correction. This segmentation allows the system to apply higher forces during the first stage when needed, while using more gentle forces during the second stage to avoid excessive conveying load, thereby achieving accuracy without overwhelming the conveying system.
Solution Approach 2:
The first correction operation performs preliminary correction with appropriate force application, preparing the sheet for the second stage. By completing the bulk of the correction work in the first stage with suitably applied force, the second stage can use reduced force levels to achieve high precision without significantly increasing the overall conveying load.
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 accurate skew and misalignment correction of various sheet types, including thick paper and large sizes, while reducing apparatus size and maintaining high precision, by optimizing conveying velocities and forces across multiple correction stages.
Implementation Method 1
the thrust pitch between the skew correction roller pair is LRP... the conveying velocity at the time of correction by the skew correction roller pair are VL and VR
Data Source
AI summary
A sheet conveying apparatus includes a skew correction unit configured to correct the skew of a sheet while conveying the sheet, controls the skew correction unit to correct the rough skew of the sheet by a first skew correction operation, and accurately correct the reduced skew of the sheet by a second skew correction operation.