Comparison of Stationary and Movable Valves for Continuous Hot Extrusion

The chapter delves into the comparison of stationary and movable valves in continuous hot extrusion processes. It begins by introducing the challenges of conventional extrusion methods, such as instationary profile properties and high scrap generation due to charge welds. The novel continuous extrusion process, combining direct and indirect extrusion with a valve, aims to address these issues by maintaining a steady state forming process and reducing scrap. The chapter then focuses on the function and differences between stationary and movable valves, with a particular emphasis on process forces, maximum temperatures, and profile properties. Numerical simulations and experimental setups are used to compare the two valve types, revealing that a stationary valve can significantly reduce process forces and enhance the process window. Additionally, the chapter examines the influence of valve geometry on profile properties, demonstrating that a stationary valve leads to a more homogeneous profile and absence of longitudinal weld seams. Overall, the chapter provides a detailed analysis of the benefits and drawbacks of stationary and movable valves in continuous hot extrusion, offering valuable insights for optimizing the extrusion process.