EMG-Vivaldi®: Technology and market update
The radar-based EMG-Vivaldi® sensor system, which is used to determine the strip centre position, continues to establish itself within the market, while its technology is continuously being developed.
The sensor system, which is mounted externally on the furnace wall, focuses electromagnetic waves through the non-conductive insulation of the furnace and onto the edge of thin metal strip material. As the furnace wall is completely enclosed in a gas-tight manner, the strip is not able to damage the sensor itself, even in case of strip breaks.
The accuracy of the system depends on the exact dimensioning of the furnace geometry with the generated radar waves. For this purpose, a reference measurement is carried out in the cold furnace.. A problem in this regard is that the furnace geometry alters during the heating process in production mode. The measuring results produced by the sensor would therefore be falsified above a certain temperature in the furnace.
The EMG-Vivaldi® solution: Hot-referencing
When a certain temperature is exceeded in the furnace, the EMG-Vivaldi® system gradually adapts the reference value of the empty furnace. An empty furnace is virtually adapted to a hot state via this method. This adaptation operates continuously and utilises the strip width spectrum produced in the system. The duration of the adaptation process is dependent on the occurrence of different strip widths, i.e. from the minimum to the maximum value.
The algorithm used for hot-referencing is part of the extensive EMG-Vivaldi® software package.
The EMG-VivaldiⓇ installations
Since the solution was introduced in 2015, 58 EMG-Vivaldi® sensor systems have been ordered. 24 of these systems are now used in production operations.
The process for upgrading from an inductive IHM/IMM strip centre sensor to the EMG-Vivaldi® system is comparatively easy and is possible in a few steps:
- The existing control cabinet can be used furthermore. The control amplifier used must be an SPC16 with MCU24 or an EMG iCON®.
- An adapter plate is used to replace the sensor electronics in the control cabinet. This then replaces the evaluation electronics, e.g. for an IMH system (BMI electronics). The adapter plate contains the EMG-Vivaldi® data processing unit (DPU), an industrial PC (IPC) and the power supply.
- The programme is then adapted in the digital controller.
- For integration into the furnace wall, the old flange of the inductive sensor (IHM/IMM) must be cut out and replaced with the new EMG-Vivaldi® flange.
Conclusion: The EMG-Vivaldi® system is increasingly becoming the standard solution for strip centre control in continuous annealing furnaces. The system is characterised by its high level of accuracy, low maintenance requirements, insensitivity to strip fluctuations and the installation of all electronic and mechanical sensor components outside the furnace atmosphere.
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