Cooling strategy for punches in hot compound extrusion of critical train components

Abstract

Failure of critical train components (CTCs) affects normal train operation or can cause serious accidents, resulting in economic losses. The design and manufacture of large, complex and precise punches is critical for the manufacture of CTCs. During extrusion, punches are at high temperature, which has a negative influence on the processing accuracy and reliability of CTCs. Hot compound deformation due to a long punch stroke reduces the life of punches, increasing manufacturing costs. Therefore, ensuring the timely cooling of punches is important for machining accuracy. A cooling strategy for punches under hot compound extrusion of CTCs is proposed. Based on computer-aided engineering technology, the cooling process of a punch was numerically simulated. Then, the design of an auxiliary mould was optimised and the process parameters were adjusted. The theoretical temperature rise of the punch was calculated and a formula for temperature rise and cooling of the punch obtained. According to the forced convective heat transfer of cooling water, the convective heat transfer coefficients on the surface of the cooling pipe were calculated. The interior and external heat dissipation of the punch were simulated using finite elements and the production beat and compound extrusion parameters were calculated. Interior circulation cooling equipment was then designed. Variations in the temperature field distribution were obtained after punch extrusion and heat dissipation using infrared temperature measuring equipment. The experimental and theoretical results agreed.