State-space theory-based closed-loop control of machining error of thin-walled part modeling and application

The thin-walled part is a key component in the aerospace field. However, its low stiffness makes it highly susceptible to deformation during milling. An adaptive compensation method for machining deformation based on state-space control is proposed to aim at the problem of precise wall thickness control of large thin-walled parts. Firstly, based on the state space theory, a closed-loop control model for machining errors of thin-walled parts is established. Taking the overall deformation and the cutter-relieving deformation into consideration comprehensively, a tool position compensation model considering the overall deformation is established, and the structural deformation is compensated based on the dimension correlation. Secondly, the influencing factors of the cutter-relieving deformation are analyzed, and the error model of the deformation during machining is established. The parameters are predicted based on the multi-round on-machine measurement (OMM) data; considering the coupling effect of the compensation value and the cutter-relieving deformation, the compensation value calculation that meets the expected machining wall thickness is realized. Finally, a measurement and processing test is carried out on a certain type of rocket fuel tank to verify the feasibility and effectiveness of the proposed method. The experimental results show that the compensation tool position trajectory based on state-space control can adapt to the deformation state of the actual parts, and the machining accuracy of the fuel tank has been significantly improved.