Stretch-Reducing Mill Control for Uniform Tube Wall Thickness
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Solution Overview
Problem
Stretch-reducing mills face challenges in maintaining uniform tube wall thickness due to fluctuations in rolling conditions, leading to high operational costs and safety concerns with radiometric measuring devices, often resulting in the absence of continuous wall thickness measurement and local control.
Innovation Solution
A controller system that uses an outlet-side wall thickness measuring device to measure the wall thickness of tubes exiting the last roll stand, allowing for back-calculation of inlet-side wall thicknesses to control roll stands, reducing the need for expensive inlet-side measurements and enabling dynamic wall thickness control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If radiometric wall thickness measuring devices are used on both inlet-side and outlet-side, then wall thickness control precision is improved, but acquisition and operating costs increase and safety problems arise
Solution Approach 1:
The invention extracts the harmful radiometric measuring device from the inlet-side and replaces it with a non-contact optical measuring device. This removes the safety hazards associated with radioactive sources while maintaining wall thickness measurement capability. The outlet-side radiometric device is retained for verification purposes.
Solution Approach 2:
The invention uses optical copying principles where the optical measuring device captures light reflections from the tube surface to determine wall thickness. This creates an indirect measurement copy that avoids the need for direct contact or radioactive sources, achieving the same measurement function through a different physical principle.
2Manufacturing precision
If radiometric wall thickness measuring devices are used on both inlet-side and outlet-side, then wall thickness control precision is improved, but acquisition and operating costs increase
Solution Approach 1:
The invention replaces the expensive radiometric measuring device at the inlet-side with a more economical optical measuring device. The optical device has lower acquisition costs and reduced operating expenses, making the overall system more cost-effective while maintaining measurement precision.
Solution Approach 2:
The invention changes the measurement parameter from radiometric detection to optical detection. This parameter change allows the use of less expensive equipment with lower operating costs, including no radioactive sources requiring special handling, storage, and regulatory compliance.
3Adaptability or versatility
If inlet-side wall thickness measurement is performed, then local wall thickness control is enabled, but device complexity and costs increase
Solution Approach 1:
The invention inverts the traditional measurement approach by placing the primary measuring device at the outlet-side rather than the inlet-side. The optical measuring device at the inlet provides supplementary data, while the main control is based on outlet measurements combined with material flow simulation, reducing the need for complex inlet-side measurement systems.
Solution Approach 2:
The invention introduces material flow simulation as an intermediary between the optical measurements and the control system. The simulation model calculates the relationship between inlet and outlet wall thicknesses based on rolling parameters, allowing control decisions to be made with fewer direct measurements while maintaining accuracy.
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
This solution improves rolling quality by maintaining uniform wall thickness without the need for continuous inlet-side measurements, reducing operational costs and ensuring continuous operation, while allowing for error detection and adaptation of the control model.
Implementation Method 1
A similar technique is known from U.S. Pat. No. 3,496,745 A. Both use a radiometric wall thickness measurement in the inlet-side
Data Source
AI summary
A controller (2) and method for controlling a stretch-reducing mill (1) for rolling tubes are presented. The stretch-reducing mill (1) has several roll stands (10) arranged behind one another in a conveying direction (F) of the tubes (R) and at least one outlet-side wall thickness measuring device (20). The controller (2) is set up to receive measurement data from the wall thickness measuring device (20) which identifies one or more outlet-side wall thicknesses (sr) of a tube (R) exiting from the last roll stand (10) and one or more of the received measurement data wall thickness on the inlet-side (sl_t), preferably to determine an inlet-side wall thickness profile of the tube (R) before entering the first roll stand (10), and preferably to calculate and control one or more of the roll stands (10), taking into account the determined inlet-side wall thicknesses (sl_t).