大型振动筛的动态设计理论与应用 03.14.doc

Dynamic design theory and application of large vibrating screen Abstract The reliability is a key factor for the design and manufacture of large vibrating screen. In the paper, we presented a new large vibrating screen with hyperstatic net-beam structure. Dynamic characteristic of the vibrating screen was researched and dynamic simulation method of large screening machines was explored. We used finite element method (FEM) to analyze dynamic characteristic of large vibrating screen with hyperstatic net-beam structure. Multi natural frequency, natural modes of vibration and dynamic response of the vibrating screen were calculated. The structural size of stiffeners on the side plate was optimized under multiple frequencies constraints and an adaptive optimization criterion was given. The results show that the vibrating screen’s structural strength is increased and the natural frequency of bending deformation is enhanced. The modal frequencies are far from working frequency, and thus the structure is able to avoid resonance effectively and reduce the destructiveness. The maximum transverse displacement of the vibrating screen is 0.13 mm, the maximum difference in vibration amplitude of corresponding points is 0.44mm and the maximum dynamic stress is 16.63MPa. The structural optimization shows that the mass of the side plate is decreased by 194.50kg, the second and third modal frequency is increased by 1.73% and 2.91% respectively and a better optimal effect is received. Key Words: large vibrating screen; reliability; hyperstatic net-beam structure; finite element; dynamic optimization 1. Introduction The structural strength and stiffness needs to be improved with the maximization of screening machines. The enlargement of structure of vibrating screen will lead to the increase of vibration mass and exciting force. Dynamic load on the vibrating screen is also increased which will lead to a greater deformation, tear of the side plate, fracture of the crossbeam, and t