Glass Draw Roll Diameter Control for Ribbon Velocity Stability
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Solution Overview
Problem
Glass manufacturing processes face challenges in maintaining consistent glass ribbon velocity and thickness due to roll wear and refractory roll covering diameter changes, leading to force disturbances and residual stress in the glass sheets.
Innovation Solution
A method and apparatus that monitor actual velocities and diameters of pull rolls, adjusting predetermined equations to match actual conditions without changing angular velocities, and incorporating thickness control to maintain desired thickness ranges, ensuring consistent glass sheet production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refractory roll coverings are used on pull rolls to draw the glass ribbon, then the glass ribbon can be effectively drawn and tensioned, but the refractory roll covering wears away over time, changing the outer diameter and causing velocity mismatches
Solution Approach 1:
The system pre-calculates the actual outer diameter of the pull rolls by monitoring motor current and comparing it to the predetermined diameter in the control equation. This preliminary detection allows the system to compensate for wear effects before they significantly impact glass ribbon velocity and thickness consistency, extending the effective service life of the roll coverings.
Solution Approach 2:
The system continuously monitors the actual velocity of the glass ribbon and feeds this information back to the control device. The control device then adjusts the predetermined diameter in the control equation to match the actual worn diameter of the pull rolls, ensuring that the angular velocity to linear velocity conversion remains accurate despite wear, thereby maintaining consistent glass ribbon production.
2Measurement precision
If the predetermined diameter in the control equation is changed to accommodate roll wear, then velocity accuracy is maintained, but changing the diameter affects the relationship between angular velocity and linear velocity
Solution Approach 1:
The system dynamically changes the predetermined diameter parameter in the control equation to match the actual worn diameter of the pull rolls. This parameter adjustment maintains the accuracy of the velocity relationship (V = ω × D/2) by using the current actual diameter, ensuring that the conversion from motor angular velocity to glass ribbon linear velocity remains precise despite wear, thereby maintaining both velocity accuracy and thickness consistency.
3Ease of operation
If master/slave configuration is used with lower rolls as master and upper rolls as slave, then torque coordination is achieved, but force disturbances from glass ribbon growth and sheet formation propagate to the upper rolls
Solution Approach 1:
The system segments the pull roll system into independent controlled units with individual control equations for each roll. Instead of a rigid master/slave configuration where disturbances propagate, each roll has its own motor and control algorithm that independently adjusts based on real-time feedback, isolating force disturbances and preventing their propagation through the system while maintaining overall coordination.
Data Source
AI summary
A glass manufacturing apparatus includes a control device configured to modify a predetermined diameter of at least one of a first downstream pair of draw rolls in a first downstream equation based on a monitored actual velocity of a first edge portion of a glass ribbon such that a predetermined ribbon velocity of the first edge portion of the glass ribbon in the first downstream equation changes to substantially match the monitored actual velocity without substantially changing a first downstream angular velocity of the at least one of the first downstream pair of draw rolls. In further examples, methods of manufacturing a glass ribbon include the step modifying the predetermined diameter of at least one of a first downstream pair of draw rolls in the first downstream equation based on the monitored actual velocity of the first edge portion of the glass ribbon.