Precision forming of long-axis forgings with rib-web sections via billet optimization based on flow characteristics

Abstract

During the forming process, the flow characteristics of materials are crucial for obtaining qualified precise products. In the forging process of long-axis forgings with rib-web sections, the material in the section would be split and extruded to both sides. It could be easy to cause incomplete forming or excessive flash scrap by using the traditional center-coincidence rule to design billet. In present work, the material flow law and its influencing factors during forging the rib-web section were analyzed aiming to develop a better billet design method for obtaining high material utilization ratio and avoiding multiple trials and errors of finite element numerical simulation. Based on the stress analysis of material flow by slab method, a calculation model of splitting-flow was established to determine the location of the splitting line in each forming step. Furthermore, the material volume distribution model in the whole forming process was established through the step-by-step accumulation of the splitting-flow material volume. By iteratively changing the billet position and calculating the volume distribution, the center positions of the billet sections can be optimized to ensure that both sides of the section are simultaneously filled, which results in high material utilization ratio up to 98%. The effectiveness of the new billet design method was verified by forming a knuckle control arm.