Tension reels are widely used as an exit-side winding system for continuous rolling mill lines to make coils by winding the strip onto a mandrel. A hydraulic cylinder expands a segmented mandrel, and a clamping mechanism causes the strip to be gripped over the mandrel at the same time. The whole components are mounted on the exit shaft of a gearbox whose power is provided by an electric motor. Parts of the driving gearbox of the mandrel are considered by exerting the torque which is provided by an electric motor. Bending and Contact stresses in Gears were derived and the safety factor of each gear was computed. Also fatigue failure of shafts of the gearbox was considered and the safety factors were considered. Finally The Bearings life was computed. Finite element analysis for all the mechanical components of the mandrel is done by using ABAQUS. As there are several statically-indeterminate mechanisms within the mandrel, usual solution methods are not capable of predicting stress and strain fields for all parts. The idea of substituting the two-force members with elastic linear springs is proposed in the present work. To estimate the longitudinal stiffness of each two-force member, the member is subjected to a longitudinal force to measure the corresponding displacement while the rest of the mechanism is assumed to be in stress-free conditions. Then the total nodal forces and displacements due to the presence of all members are obtained by dynamic simulation of the whole mechanism containing some linear springs instead of the actual two-force members in Autodesk Inventor, and the nodal forces are applied on the corresponding nodes in the primary ABAQUS model. Comparison of the results obtained using this method for selected mechanisms with known solutions shows good accuracy of the method. In addition, in analysis of the mandrel parts only part that needed modification was the spring box package. This part was found to fail under critical loading condition. An optimization problem was defined in which goal function was minimizing the shear in the inner face of the spring, considering geometrical constraints of the part. Using the varying value of stresses in all parts, static and fatigue failure criteria are evaluated for different components to find the critical elements. These data may be used in manufacturing of the components of the tension reel. Key Words Tension reel, Stress analysis, rolling mill, expandable mandrel, optimization, coiler
