hot topping of the ingot. Furthermore, the mould is equipped with a slag bath level sensor as well as load cells for definition of an optimal and accurate withdrawal action.
the process automation and entire quality of ESR ingots.
Figure 2: Trend of the radar freeboard measurement at a 1900mm dia. short collar mould ESR plant.
Figure 1: Inner diameter 1980mm-short collar mould equipped with a cooling ring and a slag braking device for the production of a 145t ESR ingot. For a precise measurement of the liquid slag bath level INTECO special melting technologies has recently developed a radar slag bath level sensor, which already has reached industrial maturity. This equipment consists of a radar sensor, all necessary stainless steel parts for installation into the cooling ring as well as all necessary electrical equipment for implementation in the plant control system. The entire unit can be installed into the cooling ring of an already existing short collar mould with slight modifications. The previous slag bath level determination method is based on calculations of the freeboard with assumed parameters, which results in some disadvantages in process control. With a radar bath level control system it is possible to have continuous information of the actual slag bath level. This provides a more precise process control, e.g. automatic start and control of the ingot withdrawal mechanism and the operation at a preset slag bath level. Figure 2and Figure 3 show the radar freeboard measurement of a 1900mm dia. short collar mould ESR plant indicating the actual freeboard (blue line) as well as the actual electrode carriage position (violet line) and actual baseplate position (green line) at the beginning of the remelting process. It can be seen that after the slag bath reaches a predefined level the baseplate retraction starts and the freeboard stays at a constant position. Furthermore, in Figure 3 it can be seen that as soon as the radar signal reaches a certain value the retraction of the base plate starts. These precise measurements and thus the steady-going base plate retraction have a positive impact on
Figure 3: Radar freeboard measurement of the beginning of the baseplate retraction. Static Moulds Large static crucibles (see Figure 4) are most challenging in the manufacturing process of the copper inlet tube. Special manufacturing processes have been developed enabling the production of inlet tubes of an inner diameter of 2700mm and more. The copper welding process of a wall thickness of up to 80mm and copper tube weights of 35t had to be handled.
Figure 4: Diameter 2000mm and 5,85m long static crucible for the production of a 120t ESR ingot. In order to enable a save and long term reliable static crucible operation for the production of ESR ingots up to 250tons, which results in design loads of over 330tons, the design of all components have been optimized by using the
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