Influences des paramètres du roulage à trois rouleaux asymétriques sur la qualité de la pièce formée

Abstract

The process of rolling with an asymmetrical setup is one of the processes mostly used to form cylindrical or conical parts from a flat sheet of steel. The bending forces, the residual stresses and the necessary power for rolling are influenced by the parameters of the rolling process and the material properties (the yield stress of the material, the thickness, the working width of rolling, the radius of curvature and the conicity of a truncated cone). To show the effect of these parameters, theoretical analyses on the cylindrical and conical roll bending are presented, without taking into account the friction at the interface of the sheet of steel with the rollers. The material of the sheet steel is considered homogeneous, isotropic and is assumed to be elastic-perfectly plastic. The analytical studies showed that an increase of the yield stress of the material, the plate thickness, the working width of rolling or the conicity of the truncated cone, generated higher roll bending forces, higher residual stresses and an increase of the required power for rolling. On the other hand an increase of the radius of curvature generated lower roll bending forces, lower residual stresses and reduce the power consumption for rolling. These analytical results are validated by experimental tests in the laboratory. Geometrical control of the achieved parts were conducted, and showed that if the yield stress of the material, the thickness or the conicity are increased, the rolled part contains fewer geometrical defects. It is noted that when the working width or the diameter is increased the resulting part showed more geometrical defects. In order to better control the process of the roll bending with three asymmetric rollers, one needs to take in account the effect of the temperature and the number of passes on the quality of roll part.

Date	5 Jan 2012
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Henri Champliaud (Supervisor) & Thien-My Dao (Co-supervisor)