The Structural Optimization Design On No-centering Drilling Dynamometer

The piezoelectric drilling dynamometer is a fundamental device of researching the drilling process, as well as a necessary part of real-time monitoring, self-adapting, optimum control in the automatous machining process. With the development of technology, not only the performances of piezoelectric dynamometer but also the technique of design and manufacture are under improvement.This project is supported by the National Natural Science Foundation of China (No. 50475152). From the application aspect of engineering, interdisciplinary knowledge, such as Physics of Crystals, Physics of Dielectrics, Theory of Elasticity of an Anisotropic Body, Electromagnetics, Piezoelectricity is utilized in the investigation on design and manufacture of no-centering drilling dynamometer whose measuring range is Mz =0-200 N.m, Fz =5000 N.By the static calibration, the dynamic calibration, no-centering measurement and temperature effect test, it is showed that the performances of no-centering drilling dynamometer are up to need. This is a pilot study for working out the no-centering drilling dynamometer, which is on the principle of piezoelectric quartz crystal's torsional effect At the same time, the author use the software ANSYS about the finite element analysis to optimize structural parameters, which is got by experience. It provides a new thought for confirming structural parameters of a design. The piezoelectricity mechanism is discussed in this project and the mathematical model of no-centering drilling dynamometer is studied and analyzed. The contact analysis about the model, the piezoelectric analysis about the sensor and the design optimization are explained in detail. The mathematical model and the structural optimization enrich the theoretical system of the piezoelectric dynamometer and provide the theoretical guidelines.The primary advantages of the piezoelectric no-centering drilling dynamometer are as follows: it can measure the moment of torque on the operating platform of dynamometer, and the center of dynamometer need not correspond to that of drill, even if drilling on the brim of the platform, the relative error to that of the center is less than ±1%. The structure is simple and convenient for checkout. The technical performances of machining and assembling are good, and its production cost is low. So it is used not only in laboratory but also in testing of practical production and real-time control.