Stretch-Reducing Mill Control Using Virtual Tube Wall Thickness
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Solution Overview
Problem
Stretch-reducing mills face challenges in controlling tube wall thickness fluctuations due to high acquisition and operating costs associated with inlet and outlet side wall thickness measurements, particularly with radiometric devices, leading to operational issues and safety concerns, often resulting in the absence of continuous wall thickness control.
Innovation Solution
A control device that uses an outlet-side wall thickness measuring device to measure the wall thickness of tubes exiting the last roll stand, with data transmitted to calculate theoretical inlet-side wall thicknesses for controlling roll stands, allowing for dynamic wall thickness control without the need for continuous inlet-side measurements, thereby reducing metrology requirements and maintaining control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inlet-side and outlet-side wall thickness measuring devices are provided, then wall thickness control precision is improved, but device complexity and operating costs increase
Solution Approach 1:
The patent extracts the inlet-side wall thickness measurement function from the physical measuring device and replaces it with a calculation-based approach. The control device calculates the inlet-side wall thickness from outlet-side measurements and rolling parameters, eliminating the need for physical inlet-side measuring devices while maintaining control precision.
Solution Approach 2:
The patent creates a virtual copy of the inlet-side wall thickness measurement through calculation. Instead of physically measuring at the inlet, the system calculates what the inlet thickness should be based on outlet measurements and rolling process parameters, effectively copying the measurement information without the physical infrastructure.
2Measurement precision
If radiometric wall thickness measuring devices are used, then measurement capability is improved, but safety risks and operational problems increase
Solution Approach 1:
The patent replaces expensive, hazardous radiometric measuring devices with simpler, safer calculation-based methods. The 'measurement' is achieved through mathematical computation rather than physical radiation sources, eliminating safety risks while maintaining the ability to obtain wall thickness information.
Solution Approach 2:
The patent substitutes the physical radiometric measurement system with a computational system. Instead of using radiation to measure wall thickness, the system uses mathematical calculations based on outlet-side measurements and rolling parameters to determine inlet-side thickness, replacing a physical measurement mechanism with an information-processing approach.
3Manufacturing precision
If inlet-side wall thickness measurement is implemented, then control accuracy is improved, but acquisition and operating costs increase
Solution Approach 1:
The patent makes the outlet-side wall thickness measuring device serve multiple functions: it directly measures outlet thickness for quality control and simultaneously provides the basis for calculating inlet-side thickness for control purposes. This multi-functionality eliminates the need for separate inlet-side measurement resources.
Solution Approach 2:
The system uses its own outlet-side measurement capability to generate the information needed for inlet-side control. Rather than requiring external inlet-side measurement resources, the system serves its own control needs by calculating inlet thickness from its existing outlet measurements and process parameters.
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 approach enables effective wall thickness control, reduces operational costs, and allows for continuous operation even if inlet-side measurements fail, while also enabling adaptive corrections and fault detection, improving rolling quality and accuracy.
Implementation Method 1
A similar technique is known from US Pat. No. 3,496,745. Both use radiometric wall thickness measurement on the inlet side
Data Source
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AI summary
The invention relates to a controller (2) and a method for controlling a stretch-reducing rolling mill (1) for rolling tubes (R), having multiple roll stands (10) arranged one behind the other in the conveyor direction (F) of the tubes (R) and at least one wall thickness-measuring device (20) on the outlet side. The controller (2) is designed to receive measurement data, which characterizes one or more outlet-side wall thicknesses (s r ) of a tube (R) exiting the last roll stand (10), from the wall thickness-measuring device (20), to ascertain, preferably calculate, one or more inlet-side wall thicknesses (s l_t ), preferably an inlet-side wall thickness profile, of the tube (R) in the state prior to entering the first roll stand (10) from the receive measurement data, and to control one or more of the roll stands (10) while taking into consideration the ascertained inlet-side wall thicknesses (s l_t ).