Investigation and analysis of the pre-straightening influences in AISI 1045 steel drawn bars

The drawn bars are the raw material for manufacturing of automotive shafts for presenting high mechanical properties, good dimensional quality and surface finish. The residual stress generated in the manufacturing process can potentially lead to distortion and dimensional variations in mechanical components. Process parameters such as pressure and distance between the pre-straightening rollers, material properties, friction between the tool and the workpiece, as well as wire drawing parameters like reducing and die angle, influence the residual stresses induced in the final product. Numerical simulation is a resourceful tool to evaluate the level of influence of each parameter involved in the process: it does not require the manufacture of prototypes and it eliminates the "try-out" process which is very common in experimental procedures. The work presented herein mainly aims at investigation and improvement of the pre-straightening influences in the wire drawing process chain by investigating the behavior of residual stresses generated in the process of AISI 1045 steel bars. Besides, the variation of process parameter such distance of pre-straightening rolls, through numerical simulation and subsequent comparison with results from experimental measurements were performed. The numerical simulations of the pre-straightening process have shown heterogeneous profiles of deformation and, consequently, heterogeneous profiles of residual stress at both the surface and in the section of the simulated bars. This heterogeneity of deformation can be noted after drawing on specific areas of the workpiece, and it leads to the conclusion that the deformations are carried from one process to the next one. The changes in the distance of the rolls have shown that the first couple of the horizontal rolls has more significant influence in the distribution of stress and strains after wire drawing.