Modeling of a thermo-mechanically controlled virtual finishing mill process with coupled interactive rolling automation and setup calculations
Joonas Ilmola, Oskari Seppälä, Joni Paananen, Aarne Pohjonen, Juha Pyykkönen, Jari Larkiola
Abstract
The steel industry is facing a big change as they are reducing carbon dioxide emissions. The transition to carbon neutral or fossil free steel manufacturing requires investments in new technologies e.g. direct reduction of iron or scrap-based production. Consequently, compact hot strip rolling lines and electric arc furnaces will replace conventional hot strip rolling processes operating with slab reheating furnaces. In compact strip production lines, the casting size is significantly larger compared to conventional process with individual slabs. This reduces the possibility of experimental rolling tests and therefore experimental testing should be replaced with modelling and simulations. In order to create a comprehensive model of the finishing mill to reduce experimental tests significantly, the virtual finishing mill is required. Therefore, the virtual finishing mill is developed to simulate hot strip production considering the boundary conditions of an industrial scale finishing rolling mill using a finite element model. Virtual finishing mill contains implemented virtual rolling automation which performs setup calculations for mill stands, mass flow control and strip tensioning between sequential rolling stands and carries out roll gap clearance adjustments for six stands finishing mill. This research focuses on mechanical process stability in full scale FE-model of finishing mill. Also, the reliable boundary conditions addressed to the hot strip in the finishing mill process are produced. Developed virtual finishing mill delivers a thorough thermo-mechanical state of the strip through the finishing mill to be further utilized by sub-models of metallurgical phenomena like recovery, precipitation and grain growth. The validation for setup calculations and FE-model are completed by comparing results of mathematical methods and comparison to industrial data. • A Finite Element model of an industrial six-stand finishing mill with virtual rolling automation has been developed. • Setup calculation for roll gap presetting predicts roll force and WR flattening, integrated into virtual rolling automation. • Virtual rolling automation manages mass flow, strip tension, and roll gap clearance. • Thermal and mechanical boundary conditions corresponding to the industrial finishing rolling process can be produced. • The virtual finishing mill simulates strip exit gauge and temperature paths comparable to the industrial process.