Comprehrensive Error Compensation For Milling Thin Wall Workpiece

Made in China 2025 ranked high-end CNC machine as one of the most prioritized developed areas.Speeding up the research of high-precision machine technology is of great importance to enhance the national industrial power and comprehensive strength.With the development of aerospace industry,requirement of high-accuracy thin wall workpiece is increasing gradually and demand for dimension precision is growing higher accordingly.But the rigidity of thin wall workpiece is so low that the workpiece is easily distorted by cutting force.Besides,influenced by the machine geometrical error,machining accuracy can't be guaranteed.As a result,taking cutting force induced error and machine geometrical error into overall consideration is extremely significant to enhance the cutting precision.Based on the shearing and ploughing mechanism during milling process,the paper proposed an infinitesimal milling force model.By the geometrical information of the cutter and workpiece,the infinitesimal milling force is integrated through cutting areas and the overall milling force model is obtained.As the tool cuts in and off the workpiece,the milling force can be considered as a periodical signal and solved by the Fourier Transform in frequency domain.After analyzing the machine geometrical error and cutting force induced error during milling thin wall workpiece as well as error transition during motion chain,comprehensive error model is established based on error transition model.Aimed at overcoming the shortage of complicated computation,the paper put forward an APDL program by integrating modeling automatically,applying force movably,selecting points adaptively,thus simplifying computation operations and decreasing calculation time.By using External Machine Zero Point Shift of Fanuc numerical system and adding compensation to motion shafts,an error compensation device is produced.Side mill thin wall workpiece and compare cutting accuracy among machine without error compensation,only with geometrical error compensation,only cutting force induced error and comprehensive error compensation.It can be inferred that the error compensation device is valid and efficient.