Stretch Reducing Mill Control for Pipe Wall Thickness Compensation
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Solution Overview
Problem
Existing control systems for stretch reducing rolling mills struggle to accurately compensate for short-wave wall thickness variations and unpredictable conveying speeds, leading to arbitrary wall thickness variations in rolled pipes due to delayed detection and contamination of optical sensors.
Innovation Solution
A method and control unit that continuously measure the instantaneous position of the pipe using a pipe position measuring device and adjust roll stand rotational speeds based on both wall thickness progression and real-time pipe position data, ensuring precise compensation of wall thickness variations within a narrow tolerance range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors are used to detect pipe position, then detection can be performed, but the sensors become contaminated and provide inaccurate or delayed detection results
Solution Approach 1:
The patent introduces an intermediary measurement system that indirectly determines pipe position through wall thickness measurements and conveying distance calculations, rather than directly detecting the pipe with contaminated optical sensors. This intermediary approach filters out the contamination issue while preserving position information.
Solution Approach 2:
The patent replaces the optical detection system with a measurement system based on wall thickness data and conveying distance calculations. This substitution eliminates the harmful optical sensors while maintaining the ability to determine pipe position through alternative physical measurements.
2Loss of time
If wall thickness measurement is performed well before the pipe enters the rolling mill, then measurement time is sufficient, but the pipe position becomes unpredictable during rolling
Solution Approach 1:
The patent implements a feedback system where wall thickness measurements taken earlier in the process are continuously correlated with subsequent pipe position data. This feedback loop allows the system to track and compensate for position variations, maintaining measurement precision despite the time delay.
Solution Approach 2:
The patent performs preliminary wall thickness measurements before the pipe enters the rolling mill, storing this data for later correlation with actual pipe position during rolling. This preliminary action captures essential data early while the system prepares for more precise position-based control as the pipe approaches.
Data Source
AI summary
A stretch reducing rolling mill for rolling pipes has a plurality of roll stands arranged in series in a conveying direction of a pipe. A wall thickness measuring device determines a wall thickness progression of the pipe prior to rolling. A control unit controls respective rotational speeds of the roll stands. A pipe position measuring device is arranged in front of the roll stands and continuously measures a current longitudinal coordinate of the pipe. The measured values of the longitudinal coordinate of the pipe are transmitted to the control unit. The control unit controls the rotational speeds of the roll stands based on both the determined wall thickness progression and the transmitted measured values of the current longitudinal coordinate of the pipe, in order to compensate for wall thickness variations of the pipe. A stretch reducing rolling mill is designed to carry out the method.