Regeneration Chatter Stability Research Of Axial-Torsion Coupling And Large Ratio Of Long-Diameter In High Speed Micro Hole Drilling

With the development of science and technology and the improvement of precision manufacturing capabilities,the demand for micro-holes in industrial production is increasing,and placing higher requirements on the processing quality of micro-holes.Hard and brittle materials are widely used in modern medicine,aerospace and microelectronics because of their good corrosion resistance,wear resistance and mechanical properties.At present,the most precise processing of micro holes in hard and brittle materials is adopted.Traditional micro-drilling is still one of the most effective processing methods.Its high hardness and high strength characteristics put forward higher requirements for the tools of micro-drilling.One of the important factors affecting product quality.is the regenerative chattering in micro-hole drilling.of large-diameter ratioIn order to improve the processing quality of the micro holes,the efficiency of processing is improved and the reduction of cost in processing.Based on the macro drilling dynamics model,this paper establishes a two-degree-of-freedom structural dynamics microscopic model,obtaining a two-degree-of-freedom nonlinear micro-hole drilling dynamic equation,introducing dimensionless parameters and variables,making nonlinearity of the kinetic equations dimensionless and linearized.The different dynamic system parameters are compared and the corresponding stability chatter limit diagrams are obtained to predict stable areas.Among them,the main parameters include axial/torsional damping coefficient,axial/torsional stiffness,natural frequency,cutting parameters,aspect ratio and micro-drilling radius;The studies show that the larger the aspect ratio,the more unstable the processing;In the domain of virtual frequency of 0<?<1,increasing the axial/torsional damping coefficient,the axial stiffness,the damping ratio,the cutting coefficient and the natural frequency of the system,and selecting the appropriate torsional stiffness,the chatter could be suppressed;In the domain of virtual frequency of ?>1,increase The large axial damping coefficient reduces the torsional damping coefficient,increasing the axial/torsional stiffness,reducing the damping ratio,the cutting coefficient,the natural frequency,and so on,then the chatter vibration.is suppressed.Analyzing the influence of the damping on the stabilization process under the tuned system and the detuned system.The research shows that the existence of damping enhancing the stability of the system.The stability of the system in the tuned state(?=1)is higher than that in the detuned state(??1).To explore the stability characteristics of the process of micro-drilling,the stable chatter limit cycle and the unstable chatter limit cycle are obtained according to the dynamic equations mentioned above.The course of the stability of the machining process system and the unstable chatter change are obtained through analysis,which provides another basis for the stability of the micro-drilling system.Finally,the partial verification of the above theoretical analysis is carried out.Two kinds of experimental materials of optical glass BK7 and ordinary glass with different hardness were selected.The theoretical analysis data in from the previous article are selected as experimental parameters,and the experimental comparison of the two materials is carried out.After the data is processed,the time domain vibration signal and power spectrum are obtained The experimental results prove the correctness of the above theoretical model.At the same time,it is found that the variation of power energy in micro-drilling is the same as that of macro-cutting.