Hot Aluminium Strip Flatness Measurement with Trimmed Vibration Isolation
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Solution Overview
Problem
Existing rolling devices designed for cold rolling of steel are not suitable for warm rolling of aluminum due to differences in physical properties and vibration behavior, leading to issues with amplitude recording and potential damage to the aluminum band.
Innovation Solution
A modified rolling device with a trim device to separate strips from the aluminum band, a front steering roller to redirect the band and reduce vibration disturbances, and a mechanical stimulation device using suction to induce vibrations, along with a contactless measuring device to record amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical excitation device is used to induce vibrations in the aluminum strip for flatness measurement, then the amplitude of vibrations can be detected, but the natural vibrations of the aluminum strip interfere with the measurement due to its lower natural frequencies compared to steel
Solution Approach 1:
The harmful natural vibrations of the aluminum strip are extracted and isolated from the measurement process by using a contactless measuring device that detects vibrations in a specific frequency range, effectively filtering out the low-frequency natural vibrations of the aluminum strip while measuring the high-frequency induced vibrations
Solution Approach 2:
A contactless measuring device acts as an intermediary between the mechanical excitation device and the aluminum strip, using electromagnetic fields to induce and detect vibrations without physical contact, thereby avoiding interference from the strip's natural vibrations
2Ease of manufacture
If a trimming device is arranged on the outlet side of the rolling stand to cut edges of the aluminum strip, then the strip can be prepared for coiling, but the cutting process excites mechanical vibrations that interfere with amplitude recording
Solution Approach 1:
A front deflection roller serves as an intermediary element between the trimming device and the measuring arrangement, redirecting the aluminum strip to pass through the measurement zone before trimming occurs, thereby isolating the measurement process from vibration interference caused by the cutting operation
Solution Approach 2:
The process is segmented into distinct zones: a measurement zone where the strip is deflected and measured before trimming, and a trimming zone where edges are cut. This spatial segmentation ensures that vibration-generating trimming operations do not interfere with the sensitive amplitude recording process
3Measurement precision
If contact-based measurement using a segmented tensile measuring roller is used, then flatness can be measured, but the surface of the aluminum strip may be scratched or damaged
Solution Approach 1:
The mechanical contact-based measurement system is replaced with a contactless electromagnetic measurement system. The contactless measuring device uses electromagnetic fields to detect strip vibrations and flatness without physical contact, completely eliminating the risk of surface scratching or damage while maintaining measurement precision
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
The modified rolling device allows for accurate recording of amplitude vibrations in aluminum bands, reducing the risk of damage and improving the precision of planning measurements, while also increasing the self-frequencies of the aluminum band.
Implementation Method 1
a mechanical excitation device by means of which the metal strip can be excited to a mechanical oscillation in its thickness direction
Implementation Method 2
The mechanical excitation device can be designed, in particular, as a suction device, by means of which the metal strip can be periodically subjected to a negative pressure on one side
Implementation Method 3
a number of electromagnetic excitation devices for inducing eddy currents in the metal strip and at least one electromagnetic receiving device for detecting the amplitude of the mechanical oscillation
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The invention relates to a rolling stand (2) for rolling a hot aluminium strip (1), downstream of which on the outlet side are arranged – in this order – a trimming device (7), a front deflection roller (8), a measuring assembly (9) and a coiling device (10). The coiling device (10) has a coiler (11) and a rear deflection roller (12), the rear deflection roller (12) being upstream of the coiler (11). The trimming device (7) cuts a portion of the metal strip (1) from both sides of the metal strip (1) such that only the remaining central region of the metal strip (1) is fed to the downstream devices (8 to 10). The front deflection roller (8) deflects the metal strip (1) away from a direct connecting line (13) between the rolling stand (2) and the rear deflection roller (12). The measuring assembly has a mechanical excitation device (14) and a measuring device (19). The mechanical excitation device (14) excites the metal strip (1) to mechanically oscillate in the direction of its thickness. The measuring assembly (19) senses, for a plurality of regions (20) of the metal strip (1) lying adjacent to one another in the direction of the width of the metal strip (1), the amplitude of the excited mechanical oscillation of the respective region (20).