This paper introduces the assembly system model of drilling tool, drilling tool and fixture. In this system, the failure of drilling tools is caused by self-excited vibration, that is, the self-excited vibration of components in the axial direction. In this paper, the stable lobes of rock macro and micro drilling are established, the deep well rotary drilling system is analyzed in detail, the influence of changing the axial damping coefficient on the critical speed of drilling in macro and micro drilling is investigated, and the flutter behavior in the process of drilling is considered comprehensively, so as to avoid tool flutter damage and workpiece scrap and improve productivity.

Preventing resonance in boring bar vibration is the key to achieve high quality and efficiency. In this paper, using the three-dimensional nonlinear dynamic model of boring process, the cutter bar is simplified as a rotating non planar bending axis, starting from the constitutive relationship and stress displacement relationship of composite materials. Based on Hamilton principle, the nonlinear motion differential equation of cutting process is established. The nonlinear partial differential equations of bending vibration are discretized by Galerkin method. Using the multi-scale method, the frequency response functions of the system in the primary resonance and super resonance are obtained. Using this model, the effects of the length diameter ratio of nano-carbon materials and the content of nano-carbon materials on the vibration frequency response of the boring bar are studied. The results show that the steady vibration amplitude of the cutter bar can be reduced by adding nano-carbon materials to the fiber reinforced polymer composite (FRP) beam.

This paper studies the free vibration response of a spinning and variable cross-section composite cutter bar homogeneously enhanced with carbon nanomaterials. Based on the Rules of Mixture (ROM) and the Halpin–Tsai Model (HTM), we establish a motion model of the spinning and variable cross-section composite cutter bar by containing carbon nanomaterials, which combines the Euler–Bernoulli beam theory and Hamilton principle. In addition, the dynamic governing equations are solved by using the Galerkin method so as to obtain the characteristic equation. The curves of decay rate-rotating speed and natural frequency-rotating speed are obtained especially by numerical analysis, and the corresponding critical speed and instability threshold of the composite cutter bar are also calculated. By selecting different parameters such as length-to-diameter (or length-to-width-to-thickness) ratios and volume contents of carbon nanomaterials, cutter bar taper ratios, ply orientations, and stacking sequences, the relation between instability threshold and loss factor is obtained with respect to the composite cutter bar. The results obtained found that the cutter bar’s stiffness is increased by adding carbon nanomaterials into the carbon fiber-reinforced polymer composites. Its natural frequency and critical speed are increased, but the cutter bar’s damping decreases with the increasing content of carbon nanomaterials. The results of critical speed and fundamental natural frequency of composite cutter bar for high-speed machining are greatly meaningful.

The nonlinear dynamic analysis of rotating composite boring round bar containing carbon nanotubes (CNTs) in cutting system was investigated. Firstly, simplify the boring bar to the model of non-extendable rotary cantilever structure. Both the Halpin-Tsai model and micro-mechanical layering theory were used to predict the material properties of the boring round bar. Then the equations for the composite boring bar based on Euler Bernoulli shaft theory, including von Karman geometric nonlinearity are derived. The nonlinear dynamic model of cutting system including periodic regenerative chatter cutting force, periodic control force, viscoelastic and process damping is established by using Hamilton principle. The analytical solution of the steady-state response of the cutting system was subsequently obtained by the Galerkin approximation and the perturbation method of multiple time scales. Finally, the influences of carbon nanotube-related parameters, fiber volume fraction, fiber orientations, stacking sequences, damping coefficient and geometry properties of the cutter edge on the stability of the cutting system are evaluated. The obtained results show that the incorporation of CNTs has significant effect on the dynamic behavior of the cutting process. Increasing the process damping and changing the cutter edge and bar's cross section can improve stability of the cutting process. Furthermore, the unstable cutting region is sensitive to multi-valued properties generated by jumping.

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