Study On Dynamic Characteristics Simulation And Optimization Design Of Dynamical Vibration Absorption Boring Bar With Damping

The size and shape of the boring bar are restricted because of the special machining condition in the deep-hole turning. This produces the low stiffness of the boring bar which will become lower especially with large length to diameter ratio. The vibration in the cutting will be aggravated and the machining quality will be badly affected. More dramatically, the machining can not be on the rails due to the lower stiffness. How to reduce the vibration in the deep-hole turning has become an urgent problem.In this thesis, based on the summary of vibration technology, structural design, test methods and vibration absorption effect analysis at home and abroad of vibration absorption boring bar, the simulation model of the dynamical vibration absorption boring bar with damping is established, simulated and optimized by using the flexible multi-body dynamics simulation technique. On the basis of the simulation results, the dynamical vibration absorption boring bar with damping has been designed and manufactured. The main content of this thesis includes the following parts:Based on the research of structural features and vibration absorption characteristics of dynamical vibration absorption boring bar with damping, the knowledge of mechanics of materials and mechanics of vibration is used to derive the formula of the equivalent stiffness and equivalent mass of boring bar, establish the simplified mathematical model, and analyze the vibration absorption principle and vibration characteristics of the dynamical vibration absorption boring bar with damping. This provides the theoretical basis for further study on vibration absorption system of boring bar.The software of ADAMS and ANSYS is used to build up the flexible multi- body dynamics simulation model of the dynamical vibration absorption boring bar with damping. And the comparison between theoretical results and simulation results verifies the validity of the model. The influence of the radial stiffness coefficient of rubber brushes and the equivalent viscous damping coefficient of damping fluid on the vibration system is discussed by using the vibration analyses module of ADAMS. The flexible multi-body dynamics model of the dynamical vibration absorption boring bar with damping has been simulated, optimized and analyzed in frequency domain. And optimized parameters are obtained finally. Simulation analysis of optimized system shows the maximal frequency response value of the system reduces to one-third of that of original system. And the vibration resistance of the system is vastly improved.The finite element model of rubber bush is built up by using the software of ANSYS. Fast conversion between the radial Stiffness and design parameters of rubber bush is achieved with function approximation and gradient optimization algorithm. The influence of inner and outer radii and axial length on the radial stiffness of rubber bush is analyzed, which provides guidance for the design of the rubber bush. Based on the knowledge of fluid dynamics, an estimated formula between the equivalent viscosity coefficient and the movement viscosity coefficient of damping fluid is given. This provides guidance for the selection of damping fluid.In order to verify the correctness of theoretical calculation and simulation results, 2ch FFT analyzer SA-78 is used to test the vibration characteristic of the dynamical vibration absorption boring bar with damping on lathe CW6163. Experiments show that experimental values and simulation values are in good agreement, which verifies the correctness of the simulation model. The comparative test of the common boring bar and the dynamical vibration absorption boring bar with damping in actual boring processing indicates that the vibration resistance of the bar is vastly improved.Through design and dynamic characteristics simulation of the dynamical vibration absorption boring bar with damping, the optimization design proposal of it is given, which lays the foundation for the design and development of boring bar and provides a new analysis method for the research on the vibration technology of boring bar.