Finite Element Analysis And Optimization For9FQ-31Hammer Mill Based On Ansys Workbench

The development of hammer mill has decades of history in whole world. Hammer mill is the universal device for feed grinding due to its simple structure, convenient operation, low cost and wide adaptability. The research of hammer mill, both in China and abroad, mainly focus on hammer material selected, grinding room width, parameters design of screening disks structure. The optimization of its structures such as shaft and hammer plate are not designed. In this paper, the rotor-shaft structure of9FQ-31hammer mill was researched. Shaft and hammer plate, the main parts of rotor-shaft structure, were studied with finite-element analysis. The main content is that the rotor-shaft structure of hammer mill modeling is established; static and dynamic characteristics of rotor-shaft structure is analyzed; rotor-shaft structure is topology optimized and parameter optimized.We used the corn cob as machining target. First the static of hammer plate is analyzed. The load of hammer plate was maximized when the speed of rotor is maximized at4500r/min. The load of middle hammer plate was maximized by calculated. The stress of hammer plate is changed range of OMPa-71.7MPa, most of which were between1MPa-8MPa. The maximal stress of hammer plate focused on the edge of four holes and the maximal deformation of hammer plate occured on the vicinity of the holes, the value of deformation was7.26μm. The X-coordinate and Y-coordinate had the relatively large deformation. Then the static of shaft was analyzed and the load of main shaft was maximized when the first time that hammer touched materials via theoretical analysis. At this time the centrifugal force of hammer on the rotor was maximized that was2356N. It proved that the difference of centrifugal force between two hammers exercised a great influence on main shaft The stress of shaft was changed range of OMPa-77MPa, most of which are under IMPa. The maximal stress of main shaft focused on the shaft shoulder matched with bearing, it caused a large deformation when installing rotor, the value of deformation was14.1μm and Y-coordinate had the relatively large deformation. Thirdly, modal of shaft and hammer were analyzed. The first order natural frequency of main shaft and hammer plate were1145.2Hz and3921.49Hz respectively, which is dramatically higher than the excitation frequency of hammer mill and has good dynamic characteristics. Resonance did not occur in the device during operation. Finally, we optimized hammer plate and shaft based on the results of static and dynamic analysis. As the target, maximal stress of hammer plate’s topology was optimized and material of hammer plate was reduced to80%. The maximal stress as the objective function of the shaft, the mass、natural frequency and maximal deformation as the state variables of the shaft which to optimized the size of shaft. The result of maximal stress and deformation was45MPa and10.8μm. The maximal stress and maximal deformation reduced to58.4%and77.2%respectively, mass and first order natural frequency almost had no changed.In conclusion, shaft and hammer plate of hammer mill still can be optimized wi th their construction. Our research provides guidance for the structure design and has i mportant practical significance and reference value.