Hammer Mill Dynamic Characteristics

Hammer mill is a machine which works in high-speed rotating condition. There is still static unbalance and dynamic unbalance problem, which inevitably cause vibration and noise as other high-speed rotating machinery. The violent vibration brings bad effect to the installed base of mill, its own structure, the using performance and the working environment.Based on linear vibration theories and rotor dynamics theories, the dynamic characteristic problems (such as vibration modal and unbalance response) of hammer mill was studied with computer finite element method (FEM).The structural characteristics of the hammer mill was analysed. The concentration mass dynamic model of hammer mill was built based on basic idea of the finite element method, and the movement equation of the rotor-support system was deducted; By reasonably simplifying the rotor-bearing system components, the finite element model of rotor-bearing system was established in ANSYS; Through doing the modal analysis on rotor system, the natural frequency and vibration mode of system were obtained; Different imbalance states of the rotor are simulated, and the response characteristcs of the rotor system were obtained, then the impact of the size and location of imbalance to vibration of the rotor system were studied; The intensity and resonance frequency of foundation of the hammer mill were checked, and the values of static stiffness and dynamic stiffness were obtained. The result of analyse shows that the stiffness of foundation has great impact on natural frequency of entire machine, and find out that the stiffness of level direction is weak part of supporting stiffness. The general method of structural dynamic optimization design was researched in FEM software, and the optimization of the hammer mill was studied. At last, several measures about vibration reduction of the hammer mill were recommended.The conclusion could provide theoretical reference for reducing vibration and noise of hammer mill and the verifying of rotor's static & dynamic balancing. At the same time, dynamic optimization design in hammer mill could provide an engineering reference for optimization design of other similar types of rotating machinery.