ExtruTeC - High Precision Extrusion Temperature Control through Digital Technology

ExtruTeC is a 4-year project that started September 1st, 2020. It is a collaboration between Hydro Extruded Solutions AS, Cybernetica AS, the R&D institute SINTEF and NTNU. The main objective of the project is to develop a digital framework for temperature control in aluminium extrusion. This involves detailed modelling of the extrusion process and digital twins interacting with temperature sensors for process optimisation and precise temperature control. Extrusion trails at Hydro's pilot plant, which were started in 2020, have continued in 2021. A goal for these trials is to achieve a better understanding of how the cooling of the extrusion dies influences the temperature evolution and distribution during the extrusion process and the exit temperature of thin-walled profiles. To achieve a better understanding of mechanisms related to cooling, idealised laboratory cooling trials have also been done at Hydro Karmøy. An important result from the project in 2021 is the evaluation of and the instrumentation for temperature measurements with thermocouples in the extrusion tool package at Hydro's pilot plant. This is important as it will enables us to control the profile exit temperatures. In the project, Cybernetica will develop and implement new model based optimising control schemes, which will make it possible to control the temperature over the press cycle and yield precise control of the exit temperature of thin-walled profiles. In 2021, Cybernetica and NTNU have worked with coupled models for the billet heating and temperature evolution during the extrusion process, where the effects from the measured temperature have been included. These models are also installed on a server in Hydro's pilot plant. Cybernetica has also started to look on control schemes to keep the exit temperature constant, by varying the cooling or the extrusion speed. A PhD student has also been engaged at NTNU from August 31. 2021. SINTEF has worked with detailed models for the extrusion process (HyperXtrude) and the idealised cooling trials (Fluent). One of the objectives for this work is to get a better understanding of the relation between the measured temperature in the tool package and the exit temperatures, which cannot be measured. This will contribute to enabling us to optimise and control the exit temperatures.

Hydro Extruded Solutions - Precision Tubing produces thin walled MultiPort Extrusions (MPE) and round tubes. From the market, there is a continuous strong pull towards reduced tube weight and wall thickness and stronger alloys. Over the last years the typical MPE wall thickness has been reduced from 0.45 mm to 0.20 mm. It is Hydro's strategy to work towards further wall thickness reductions, while at the same time implementing stronger alloys. However, the achievements with thinner walls and stronger alloys have led to new challenges related to local overheating and more challenging flow balance. A major reason for this is a lack of temperature control. To achieve further wall thickness reduction with stronger alloys, there is therefore demands for much tighter temperature control than what has been needed earlier. The planned innovation involves: - To achieve full temperature control for extrusion of thin walled MPE profiles. This involves both the spatial temperature distribution and the temperature evolution over the press cycle. The project will develop and implement new model based optimising control schemes: A supervisory system for batch cycle optimisation, and a rapid, high precision model predictive temperature control system. This will make it possible to control the temperature over the press cycle and yield precise control of the exit temperature of thin walled MPEs. Such temperature control represents a major step change with respect to today's process capability for MPEs. With this project, MPE has been chosen as a strategic product for establishing high precision temperature control for extruded products. There are currently close to 150 extrusion presses owned and operated by Hydro, and the temperature control developed in this project, will in the longer term be of major importance for other extrusion products and markets.