Abstract: Based on the extended Hamilton principle, the boring trepanning association(BTA) drilling shaft is established in the form of the Timoshenko element model using finite element method for vibrating drilling process. This model is developed that considers the axial vibration of drilling shaft containing vibrating cutting force and the hydrodynamic forces of cutting fluid. The linear degrees of freedom will be truncated by using modal synthesis with free-interface but nonlinear degrees of freedom of the system are retained in the physical space, and thus, the DOF of the coupled system are reduced. Further, the updated model is acquired to study the relationship between the axial hole straightness deviation and cutting parameters such as drilling shaft length and drilling depth. Simultaneously, the change rules of the axial hole straightness are obtained for the different position of intermediate supports or different initial deviation, so these can make a good reference for the dynamic design of large-scale drilling machine. Through the combination of theories with experiment, the correctness and effectiveness of the above methods have been verified.

Key words: Deep hole drilling, Finite element model, Initial deviation, Mode synthesis technique, Vibrating drilling, Cyclic symmetry, Gas excitation, Newmark method, Resonance, Time inclined, Transient response