Rolling Mill Drive Load Redistribution With Stable Entry Speed
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Solution Overview
Problem
Existing methods for redistributing drive loads in rolling trains face challenges in maintaining process control and avoiding disruptions in upstream units due to changes in entry speed, leading to potential process slowdowns and interruptions, especially in hot and cold rolling operations.
Innovation Solution
The method involves setting the entry speed of the rolling stock as a function of the exit speed of a unit upstream in the mass flow direction, temporarily switching off Automatic Gauge Control for roll stands, and adjusting drive loads according to a second pass schedule to maintain constant outlet thickness, thereby minimizing disturbances to upstream processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drive loads are redistributed according to a second pass schedule during rolling, then drive load distribution is optimized, but entry speed changes cause disruptions in upstream units
Solution Approach 1:
The system determines a redistribution section of the rolling stock before actual drive load redistribution begins. By identifying this section in advance and monitoring when it passes through each roll stand, the system can coordinate entry speed adjustments with the physical state of the material, ensuring upstream units are not disrupted by unexpected speed changes.
Solution Approach 2:
The system continuously monitors the position of the redistribution section through the rolling train and uses this feedback to dynamically adjust entry speed. When the redistribution section is detected at a roll stand, the system triggers entry speed adjustment, and when the section has passed, the system returns to normal operation, creating a closed-loop control that prevents upstream disruptions.
2Productivity
If entry speed is adjusted during drive load redistribution, then mass flow changes occur, but this propagates disturbances to upstream units
Solution Approach 1:
The system applies drive load redistribution locally to specific roll stands rather than uniformly across the entire rolling train. By using Individual Stand Load Control (ISLC) to adjust only the necessary drives while keeping others constant, the system minimizes the scope of mass flow changes and limits disturbance propagation to upstream units.
Solution Approach 2:
The rolling stock is divided into different sections: a redistribution section where drive load changes occur and a constant section where normal operation continues. This segmentation allows the system to isolate the effects of mass flow adjustments to a localized area, preventing widespread disturbances in the rolling process.
3Manufacturing precision
If Automatic Gauge Control is active during drive load redistribution, then thickness control is maintained, but incorrect control interventions occur
Solution Approach 1:
The system temporarily switches off Automatic Gauge Control (AGC) only during the specific time window when the redistribution section passes through each roll stand. AGC remains active during all other periods, creating a periodic on/off pattern that prevents incorrect interventions during redistribution while maintaining thickness control during normal operation.
Solution Approach 2:
The system determines in advance which roll stands will process the redistribution section and pre-coordinates AGC switching with this information. By knowing the timing and location of redistribution events beforehand, the system can proactively disable AGC at the appropriate moments, preventing control conflicts before they occur.
Data Source
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AI summary
The invention relates to a rolling mill, a control and/or regulation device, a program code, a storage medium and a method for adjusting a drive load for a plurality of drives (20, 21, 22, 23) of a mill train (2) for rolling rolling stock (G). The mill train (2) comprises a plurality of rolling stands (4, 5, 6, 7) and at least one drive (20, 21, 22, 23) is associated with every rolling stand (4, 5, 6, 7) for driving the working rolls comprised by the respective rolling stand (4, 5, 6, 7), the drive loads being substantially adjusted to a first desired value based on an operation of the mill train (2) according to a first pass schedule. The drive loads are adjusted during rolling to a second desired value which is different from the first desired value based on an operation of the mill train (2) according to a second pass schedule which is different from the first pass schedule, a feed rate (Ve) of the rolling stock (G) into the mill train (2) being adjusted during adjustment of the second desired values depending on a discharge rate (Vg) of the rolling stock (G) of a unit (3) mounted upstream in the throughput direction of the mill train (2), thereby resulting in a rolling mill, a corresponding control and/or regulation device, a program code, a storage medium and a rolling mill which improve the redistribution of drive loads in a mill train.