Structure design and rotation control of the disc milling head in blisk manufacturing

Blisks are the most important and critical components in the gas turbine engines, which could reduce the weight obviously and improve the efficiency significantly. To achieve high efficient machining of the titanium-based blisk, a powerful and composite processing method is proposed and structure of disc milling head with high stiffness and high precision is designed, including mechanical transmission, electrical system, rotating control, locking device, and tool changer. Then, static and dynamic analyses are carried out for the disc milling head, and calculation results show that the static and dynamic performances are perfect, which satisfy the processing requirements. Considering friction and backlash in the worm gear transmission, parameters perturbation in the electrical control system, and process noise and measurement noise in the system have serious impact on the positioning precision of disc milling rotation system, a robust sliding mode control (SMC) algorithm based on linear quadratic optimal control (LQC) is proposed. Based on the traditional LQC, introduce the state estimation based on Kalman filter and control input, improve the system state space model, and define a new sliding surface equation, then, a robust SMC based on LQC is finished. Simulation and experiment results show that the designed controller is robust to the nonlinearities and uncertainties in the rotation control system of disc milling head and can achieve high positioning precision.