Research On The Key Technology Of Hang Type Centrifuge Design

The main shaft system of the hang type centrifuge will be affected by the electromechanical coupling and the fluid-solid coupling in normal operation, which will generate intense nonlinear vibration. With the increasing of the main shaft system’s speed, the vibration of the centrifuge will become more and more serious, and then affects the safe operation of the hang type centrifuge. In order to design excellent dynamic performance of the hang type centrifuge, it is necessary for the main shaft system to be deeply studied in the nonlinear dynamic characteristics and coupling dynamics, and other deep-seated problems. This paper consists of the following:From the viewpoint of the electromechanical coupling and the fluid-solid coupling, the mathematical model of the main shaft system of the hang type centrifuge is established by using the finite element method in this paper. Then the global coupled nonlinear dynamic equation of electromechanical fluid is built. Firstly, considering the conditions of the electromechanical coupling caused by the vibration eccentricity of the motor rotor, the dynamic model of the motor unit is established; Secondly, the centrifuge spindle is regarded as beam element, and the dynamic model is built by the finite element method; Thirdly, according to the connection form and structure characteristics of the rotating hub, it will be regarded as a curved plate unit, and the corresponding dynamic model is established; Finally, according to the large deformation theory of shell and the structure characteristics of the drum, the drum will be regarded as the shell, and the shell was meshed by the triangular plate element, considering the fluid-solid coupling between the massecuite and the drum, then the dynamic model of drum unit is established. From this, using the corresponding coordination unit matrix and coordinate transformation matrix between the local unit and whole system, the dynamic model of the main shaft system of the hang type centrifuge is built. And then the frequency factors of the system are obtained by the multi-scale method. By analyzing the characteristics of various frequency factors, parametrically excited vibration of the system under electromagnetic excitation, and the coupling mechanism of parameter excitation and forced vibration of the system under combined electromagnetic excitation and inertia excitation is studied.Take primary resonance of the main shaft system of the hang type centrifuge under the joint action of internal resonance and primary resonance as an example, the nonlinear dynamic equation of the spindle system is solved by the multi-scale method, and the stability of nonlinear vibration of the system is analyzed.After established the nonlinear dynamic equation of the spindle system, choose the minimum output amplitude of the main shaft system of the hang type centrifuge as the objective function, the structure parameters of the spindle system as the design variables, using the genetic algorithm to establish mathematical model of the optimum design of the spindle system, finally the optimum design method of the spindle system is determined.Through the simulation analysis of nonlinear vibration characteristics and structure optimization of the main shaft system of the hang type centrifuge, the correctness and feasibility of the theoretical research in this paper is verified.