Thermal Analysis of Flatness Measuring System for Rolling Applications
2018 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Student thesisAlternative title
Termisk analys av planhetsmätningssystem för valsningsapplikationer (Swedish)
Abstract [en]
In rolling applications it is critical to be able to control the flatness of the metal strip. An uneven strip may in the most extreme cases lead to strip breaks. One of the systems used to measure the flatness consists of a measuring roll, which the strip is deflected over. During the contact time, heat is transferred from the hot strip to the roll. The roll is not allowed to get too hot due to risks of overheating the electronics. Previously the measuring roll have only been used in cold rolling applications, where this is usually not a problem. There is now an increased interested in using the roll in more extreme applications with higher strip temperatures. This requires knowledge about all the potential heat sources present in the system. The subject of this thesis work has been to investigate some of the contributions to the thermal balances of the measuring roll. A numerical model has been developed to describe conductive heat transfer between the metal strip and the measuring roll. Using the numerical model, the heat transfer was obtained as a function of the temperature, contact time and thickness of the strip. From these simulations a heat transfer coefficient associated with an external cooling demand was derived. The flatness measuring roll is equipped with pressure sensitive sensors used to measure the flatness of the strip. These sensors are located in internal channels and generate heat through resistive heating. The impact of this on the overall temperature of the roll was determined to be small. In the internal channels there is also a flow of air. In normal operation scenarios the flow is very low, leading to a small cooling capacity. From the thermal balance of the system it was concluded that the dominant heat source was the heat transfer between the strip and roll. This heat transfer is however heavily dependent on material properties and surface characteristics. The model used to describe the conductive heat transfer assumes no contact resistance between the strip and roll. This provides an upper-bound estimate of the heat transfer. If the contact resistance is included within the model the impact of the individual heat sources increases. Both the material properties and contact resistance requires further investigation. Combining the results of M. Gustafsson (Master of Science thesis, Karlstad University, 2018), a thermal balance for the measuring roll has successfully been developed. This balance clarifies the critical parameters which should be considered when designing the external cooling of the roll.
Place, publisher, year, edition, pages
2018. , p. 69
Keywords [en]
hot rolling, cold rolling, heat transfer, thermal analysis, conduction, internal convection, numerical modelling, flatness measuring roll, thermal balance
National Category
Other Physics Topics
Identifiers
URN: urn:nbn:se:kau:diva-67667OAI: oai:DiVA.org:kau-67667DiVA, id: diva2:1218366
External cooperation
ABB
Subject / course
Physics
Educational program
Engineering: Engineering Physics (300 ECTS credits)
Supervisors
Examiners
2018-06-142018-06-142018-06-14Bibliographically approved