Numerical and experimental investigation of trapezoidal wire cold drawing through a series of shaped dies

摘要

Trapezoidal-shaped aluminium wires are in demand for the production of the aluminium conductor steel supported/trapezoidal wire (ACSS/TW) conductor. In this work, it is proposed to manufacture such wires by a multi-pass cold drawing process using a series of shaped dies with an initial aluminium wire, which has an outer diameter of 9.5 mm. The ruled surface partition method is introduced to design the intermediate die profile of the multi-pass cold drawing. It is possible to design the intermediate die profile efficiently according to the suggested reduction ratio and save time regardless of the geometric complexity. A multi-pass drawing machine and a universal testing machine are both used to investigate the drawing process of trapezoidal-shaped aluminium wires. Wire break occurs when a five-pass drawing process is introduced. The six-pass drawing process is suggested to apply in a consideration of die cost. The final production has a good surface finish and a dimensional accuracy, suitable for the production of the ACSS/TW conductor. A finite element method (FEM) simulation approach is used to analyse stress and drawing force for the proposed process. The Von Mises stress values gradually increases and the drawing force values decrease along the pass schedule. The influence of the number of the drawing passes is numerically assessed. The drawing force value and the Von Mises stress value are lower when the number of dies is larger. The numerical compute drawing force of the six-pass drawing process is compared with the experimental ones. A good agreement between the predicted and experimental results can be observed.