The Modal Identification Of The Hybrid System Of GCD-1500 Percussive Drilling

Percussive drilling is used to impact rock and soil with the kinetic energy by the falling of percussive bit, which is lifted by a cable driven by a linkage or a hoist. Because of percussive drilling featuring with simple structure, low cost, simple operation and so on, it has been still widely used in domestic engineering fields, such as water-well drilling, railway, road construction, etc.Although percussive drilling is widely used, most of them are designed on empirical methods or simplified formulas, without considering the effect of the stiffness (flexibility) of the system on the dynamic characteristics of the system. The dynamic characteristics such as the correlation between the modal frequency of the system and the structure parameters have not been fully understood. Besides, the life of buffering spring is much shorter than the estimated life in accordance with the impact cycle, and the noise also hasn't been given a good treatment in the application of the drilling rig.Since the dynamic characteristics of the percussive drilling machine system are not understood satisfactorily, to develop the design theory of percussive drilling, this dissertation studies the hybrid system dynamic model of percussive drilling machine of GCD-1500 rig and places emphasis to the modal identification of the system. Besides, it also gives the preliminary analysis to the dynamic process. The issues being mainly studied are listed as follows:First, on the basis of the kinematics of percussive drilling machine, the differential equations of the multi-freedom relative motion system of percussive drilling machine in specific location are established, and the modal frequency of the system is obtained using numerical methods.Second, on the basis of the multi-rigid-body system model of percussive drilling machine, the flexible model of cable is developed using the macro command in ADAMS and the flexible body of spring is generated in ANSYS. Integrating these two flexible models and taking account of the boundary conditions of percussive bit and the driven conditions of motion, the hybrid system dynamic model of percussive drilling machine is set up.Third, the modal vibration of the relative motion system consisting of spring, cable and percussive bit is studied by simulation with pulse excitation in different conditions, and the modal frequency is identified. It is well agree with the results by numerical methods. The correlation between the modal frequency of the system and the structure parameters is set up for the first time, and it provides the basis for the system vibration control.Fourth, this dissertation reveals that the spring stress cycle is different from the impact cycle through analyzing the spring stress and strain, and lays the foundation for the further research of the fatigue life analysis of spring.By all the works above, this dissertation studies the dynamic characteristics of cable percussive drilling machine system, and sets up the correlation between the modal frequency of the system and the structure parameters, the performance parameters. Therefore, it develops the foundation for the design theory of percussive drilling, and makes preparations for the further research of the optimal design of percussive drilling machine system.