Research on Constant Velocity Extruding Process Control for 36,000-Ton Vertical Extrusion Press

Metal extrusion is one of the most significant methods in the field of plastic deformation. The 36,000-ton vertical extrusion press uses one-piece hot extrusion molding method to produce high-pressure, large-diameter, thick-walled, seamless, alloy-steel pipe, which is required by ultrasupercritical power generator units and the third generation of nuclear power plants. The main table (extruding platform) is driven by 36,000-ton thrust. The extrusion process is a typical nonlinear multivariable strong-coupling finite-time system. In this paper, we analyze and solve the large-scaled engineering control problems, including (1) discussion of the mechanical structure of the controlled object and the feature of multivariable strongly coupling for large-scaled parallel-driving hydraulic system, (2) research on the engineering practical simplified control algorithm for multivariable system and propose a way to solve the coupling problem of the hydraulic system, and (3) design of double closed-loop control of velocity and pressure for the new technology of constant velocity extrusion. In our paper, we have proven through practice that the traditional proportional intergral (PI) controlling method, with proper controlling strategy, is still the most efficient and practicable way for a large-dimension complex object in industry.