Roller Gap Control for Sheet Forming Apparatus
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Solution Overview
Problem
Existing sheet forming apparatuses face challenges in precisely controlling the roller gap and maintaining a consistent load, leading to issues such as uneven sheet thickness, melt bank formation, and roller misalignment, which affect the quality of the formed sheet.
Innovation Solution
The apparatus incorporates a roller gap adjustment unit and a roller gap control unit with two modes: constant roller gap control and constant pressing load control, using servomotors, load cells, and linear sensors to automatically adjust the roller gap and pressing load to predetermined target values, ensuring precise control during startup and condition modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the roller gap is kept constant, then the device structure is simple, but the pressing load on the roller cannot be precisely controlled leading to sheet quality issues
Solution Approach 1:
The roller gap is made dynamically adjustable through a roller gap adjustment unit that can change the gap width based on process requirements. The gap adjustment unit includes a drive mechanism that responds to control signals to modify the roller gap dynamically during operation, enabling adaptation to different sheet thickness requirements and pressing load conditions.
Solution Approach 2:
A pressing load detection unit is implemented to measure the actual pressing load on the roller in real-time. This detection unit provides feedback to the control unit, which then adjusts the roller gap accordingly to maintain the desired pressing load, ensuring consistent sheet quality through closed-loop control.
2Quantity of substance
If the gap is enlarged to increase pressing amount, then more melting resin can be supplied, but the melt bank becomes larger causing roller motor overload and T-die lip contamination
Solution Approach 1:
The pressing load detection unit continuously monitors the pressing load and provides feedback to the control unit. When the melt bank size increases causing excessive pressing load, the system detects this through the load sensor and automatically adjusts the roller gap or pressing force to reduce the melt bank size, preventing motor overload and T-die contamination.
Solution Approach 2:
The system proactively monitors pressing load trends and makes preliminary adjustments to the roller gap before the melt bank becomes excessively large. By detecting early signs of increased pressing load, the control unit can prevent melt bank overgrowth before it causes harmful effects.
3Manufacturing precision
If the gap is narrowed to increase pressing amount, then sheet thickness is maintained, but the sheet may detach from rollers causing insufficient cooling and hardening
Solution Approach 1:
The pressing load detection unit provides real-time feedback on the contact between sheet and roller. If the sheet begins to detach, the pressing load decreases, and the control unit responds by adjusting the roller gap or increasing pressing force to restore proper contact, ensuring continuous cooling and hardening.
4Productivity
If automatic start-up speeds up immediately, then production efficiency increases, but the sheet thickness becomes thinner or melt bank fades causing sheet to slip off roller gap
Solution Approach 1:
Before full-speed operation begins, the system performs preliminary adjustments to the roller gap and pressing load based on detected sheet thickness and melt bank conditions. This preliminary action ensures that the roller gap is properly set before high-speed operation, preventing sheet thinning and slippage during the transition to full productivity.
Data Source
AI summary
An sheet forming apparatus selectively uses two control modes: a constant roller gap control mode where a roller gap is controlled by a roller gap adjustment means so that the roller gap converges a predetermined control target value; and a constant pressing load control mode where the roller gap is controlled by the roller adjustment means so that a pressing load converges a predetermined control target value.