Design and FEA of die sets for backpressure extrusion processes: A case study for twist extrusion

Abstract

The research focused on the development of a new die set for the implementation of pressure-assisted stamping technologies using the twist extrusion (TE) process as an example. The TE process belongs to the group of severe plastic deformation methods (SPD) and is a typical representative of this group of technologies. The main challenge in creating such die sets is the complex kinematics of the tool movement, a large stroke of the deforming tool, and increased height of the stamping block construction, which results in significant deformation of the structure. Similar problems arise in the implementation of hydroforming, stamping of elongated blanks, and pressing of parts from powder materials such as high bushings. The analysis of constructive and technological solutions implemented in existing die sets for SPD with TE has been carried out. The practical experience of operating die sets and equipment for obtaining billets of alloys of various classes in pilot and serial production is analyzed. As a result, requirements were developed for implementing the force, kinematic, and thermal. Analysis of the cycle of movement of the working tool during the operation of the die set showing that expanding the technological capabilities of universal hydraulic presses is necessary to implement this group of processes. It is proposed to use temporary mechanical fixation of the device parts relative to the moving elements of the hydraulic cylinders and the press frame. It allows expanding the technological capabilities of universal hydropress when implementing TE. The load transfer scheme to the base of the stamping die has been modified, improving the design's manufacturability and reducing deformation during maintenance operations. The advantages and disadvantages of the proposed solutions have been identified based on practical industrial experience with the proposed stamping die design. To further improve the stamping block, finite element analysis was performed to examine the loading of its structural elements during operation. Based on the modeling, structural solutions were proposed for attaching the working tool and guiding nodes of the design, which reduce the influence of elastic deformation on the die's performance. The ways of further developing the design of dies of a similar class to improve their technical characteristics are proposed.