Optimization of a transfer carriage along crane girders

Drever International S.A., located in Liège and part of SMS Siemag Group, is a market leader for continuous annealing furnaces and galvanizing plants for steel and stainless steel strips. Liège University and Drever International collaborate for many years in R & D. For the heat treatment of the strips (automotive qualities), it is necessary to use a transfer carriage in order to translate along crane girders an induction furnace (with a weight of about 60 tons) and a mobile cooler system (having a weight around 20 tons). This carriage, which has several overhangs, consists of I beams and box girders and integrates devices to compensate torsional effects. The design of this equipment is guided by the respect of strict deflection criteria, imposed by the pro-duction conditions. An optimization of the presently used carriage was required, especially in terms of total weight. A study aimed at proposing several new carriage configurations and discussing their respective advantages and drawbacks has been initiated and, as a result, the most promising configuration has been selected and carefully designed, including the fabrication and erection constraints. The use of tubular sections appeared quickly as an evidence, leading at the end to a very significant decrease of the weight and fabrication costs, while satisfying requests in terms of resistance, deformation and stiffness. In the paper, the way on how tubes have been used to achieve the industrial goals is presented and illustrated.