Sheet Discharge Fan Air Velocity Control for Stacking Alignment
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Solution Overview
Problem
Conventional sheet-discharge apparatuses experience a reduction in sheet alignment properties due to the curvature of the trailing edge during discharge, especially with sheets of higher stiffness, which can lead to improper stacking and reduced productivity.
Innovation Solution
A sheet-discharge apparatus with an inclined sheet-stacking portion and an air blow unit that adjusts air velocity based on the basis weight of the sheet, increasing air velocity for lighter sheets and setting it to a minimum for heavier sheets to prevent alignment issues without affecting productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If air is blown on the lower surface of the sheet to prevent the leading edge from hanging down, then sheet alignment properties are improved, but for sheets with high basis weight, the air pressure may press the trailing edge or raise it to close the discharge outlet, reducing alignment properties
Solution Approach 1:
The air blow unit dynamically adjusts its operation based on sheet basis weight. For sheets with basis weight of 70 g/m2 or less, air is blown at a first velocity to prevent hanging. For sheets with basis weight greater than 70 g/m2, air is blown at a second velocity (lower than the first) to avoid pressing or raising the trailing edge. This dynamic adjustment resolves the contradiction by adapting the air blow intensity to the specific sheet properties.
Solution Approach 2:
The invention changes the air velocity parameter based on the basis weight of the sheet. By detecting the basis weight and adjusting the air blow velocity accordingly (first velocity for light sheets, second velocity for heavy sheets), the system maintains optimal sheet alignment properties across different sheet types without causing harmful effects like trailing edge pressing or discharge outlet closing.
2Manufacturing precision
If air is continuously blown at high velocity to maintain sheet alignment, then alignment properties are improved, but productivity is reduced due to extended discharge time
Solution Approach 1:
The air blow unit operates periodically rather than continuously. Air is blown during the discharge process to maintain alignment, then stopped or reduced after the sheet is discharged. This periodic operation allows the sheet to be discharged efficiently without requiring continuous high-velocity air blow, thus maintaining both alignment properties and productivity.
Solution Approach 2:
The system dynamically adjusts the air blow duration and intensity based on the discharge process. Air is blown at high velocity during the critical alignment phase of discharge, then reduced or stopped once the sheet leaves the discharge roller. This dynamic control ensures alignment is maintained when needed while minimizing time loss, thereby resolving the contradiction between precision and productivity.
3Manufacturing precision
If the sheet-stacking portion is inclined to guide the sheet, then stacking alignment is improved, but for low basis weight sheets, the sheet may fit the stacking tray or stacked sheets, causing improper stacking
Solution Approach 1:
The system dynamically adjusts the air blow velocity based on sheet basis weight to compensate for the inclined stacking portion effect. For light sheets (70 g/m2 or less), higher air velocity is used to prevent the sheet from conforming to the tray inclination. For heavy sheets, lower air velocity is sufficient. This dynamic adjustment ensures proper stacking across different sheet types while maintaining the benefits of the inclined design.
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
The solution effectively maintains sheet alignment properties by adjusting air velocity according to sheet stiffness, preventing curvature and ensuring accurate stacking without reducing productivity, even for sheets with higher stiffness.
Implementation Method 1
an air blow unit that blows air downward of the sheet discharged by the sheet-discharge portion from an air blow outlet provided between the sheet-discharge portion and the sheet-stacking portion
Implementation Method 2
a sheet-stacking portion that is inclined so that a downstream side in a sheet-discharge direction is higher and on which the sheet-discharged by the sheet-discharge portion is stacked
Data Source
AI summary
The sheet processing apparatus includes a sheet-discharge fan that blows air downward of a sheet-discharged by an upper sheet-discharge roller, and a control portion configured to control an air velocity of air blown from the sheet-discharge fan according to a basis weight of the sheet. In the case where the basis weight of the sheet is a predetermined value or less, the control portion increases the air velocity of the sheet-discharge fan according to the basis weight of the sheet based on basis weight information from an input portion for inputting the basis weight information of the sheet. The control portion also controls the air velocity of the sheet-discharge fan to be a velocity at which the sheet whose rear edge contacts the sheet-stacking wall does not move in a sheet-discharge direction in the case where the basis weight of the sheet exceeds the predetermined value.