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SynopsisThe bending theory of continuous beam has been applied to the analysis of bulging in continuously cast slabs. A simple algorithm was formulated to transform a through-thickness distribution of creep strain in a shell into the shell curvature, and equations were given for the analysis model of continuous beam with multi-supports. Simulations have proved that the model satisfactorily predicts the variations of bulging profile with multi-roll arrangement and the transitional bulging including unsteady fluctuations.

The effects of die dimensions on curvature-extrusion curved rectangular bars were investigated by experiments and numerical simulations. We conducted simulations and experiments of rectangular bar production using various die dimensions. The calculated trend of curvature showed good agreement with the experiment results, thereby validating the numerical simulation results. The curvature increases concomitantly with increasing exit height and exit width. The effect of die thickness on curvature is slight. Regarding the conditions of die dimensions, the exit height is the most important factor that affects the curvature. The curvature increases when the difference in exit velocity becomes large. The generation of a dead metal area, along with container configurations, affects the curved rectangular bar curvature.Results show that the curvature is determined by the difference in exit velocity, in conjunction with the die dimensions.

The effects of die dimensions on curvature-extrusion curved rectangular bars were investigated by experiments and numerical simulations. We conducted simulations and experiments of rectangular bar production using various die dimensions. The calculated trend of curvature showed good agreement with the experiment results, thereby validating the numerical simulation results. The curvature increases concomitantly with increasing exit height and exit width. The exit height ratio affects the curvature about 2.1 times more than the exit width ratio does. The effect of die thickness on curvature is slight. Regarding the conditions of die dimensions, the exit height is the most important factor that affects the curvature. The curvature increases when the difference in exit velocity becomes large. The generation of a dead metal area, along with container configurations, affects the curved rectangular bar curvature. Results show that the curvature is determined by the difference in exit velocity, in conjunction with the die dimensions.

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The mechanisms responsible for the formation of rectangular and trapezoidal bars by an extrusion process in which dies are inclined at various angles were investigated using numerical simulations. The greater the die inclination angle or the aperture exit angle, the smaller the radius of curvature of the extruded bar. The calculated radius of curvature agreed well with the radius observed in experiments. The particle flow pattern, one of the outputs of the simulation, was used as a basis for investigating the mechanisms of curvature generation. When the die inclination angle was increased in the case of the extrusion of rectangular bars, the volume of dead metal increased, causing material flow in the plane perpendicular to the extrusion direction. This material flow gave rise to curvature of the extruded bar. It was also found that when the cross section was trapezoidal, the asymmetry of the container aperture caused differences in material flow velocity between the top and bottom portions; these differences affected the curvature.

The effects of forming conditions on wrinkling in the neck of stainless-steel tubes were investigated using experiments and threedimensional finite element simulations. The materials used for this study were tubes designed for automotive exhaust parts. When the axial or radial forming pitch of the rollers is large, the outside of the tube is subjected to considerable compressive stress in the circumferential direction by contact with the rollers. Simultaneously, the inside of the tube is subjected to considerable tensile stress in the circumferential direction. Consequently, the tube is subjected to excessive localized forming, which causes the curvature to become uneven in the circumferential direction, thereby resulting in wrinkling. The number of contact points with the rollers was determined. Results show that the optimum forming conditions were easily determined to achieve short forming times and high dimensional accuracy.

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