Dynamic Analysis Of The Thru-Shaft Plate Mills

Since requirements for paper plate mills have been developed towards large size and refinement, there is a high demand for plate mill spindles. Based on the structure of spindles, there are two types of widely used paper plate mill, i.e. cantilever and thru-shaft paper plate mills. At present the cantilever plate mills are popular on the market. But the thru-shaft plate mills have their unique advantages in parallelism compared with cantilever plate mills. However, due to difficulties in changing abrasive discs, they gradually exited the market. This paper redesigned a thru-shaft plate mill while retaining its original advantages. The new plate mill is mainly composed of a spindle motor, a spindle, an adjusting device for moving disc, an adjusting device for fixing disc, front bearing assembly, back bearing assembly, and a base support etc.. Based on the new structure design, a simulation model of the spindle system has been built to analyze its static and dynamic characteristics. Main research work and conclusions are as follows:Firstly, a new paper plate mill has been designed after researching on old paper plate mills, hot grinding machines and other machinery. The plate diameter, power of motor, shaft diameter has been designed based on calculation. Also bearing type has been selected, and the structure of grinding chamber and fine adjustment device has been designed.Secondly,the simulation model of the spindle has been built using the ANSYS/Workbench platform to analyze spindle static characteristics. By observing stress and displacement of the spindle acquires its static stiffness in order to decide if the original design is reasonable.Thirdly, the spindle system is composed of a spindle, a moving disc and abrasive discs. The dynamic characteristics of the spindle system are analyzed including modal analysis and harmonica response analysis. The first six modals are calculated and modes of modals are described. The response of the spindle system under the cyclic loading is analyzed to predict system continuous dynamic characteristics. The results have verified that the spindle system can avoid resonance, and then deduces the fatigue and other harmful effects caused by forced vibration. The dynamic stiffness of spindle system is analyzed using ADAMS software. When the spindle system operates under steady status with symmetrical torque applied at the right of the spindle, the dynamic stiffness of the system is acquired by analyzing the displacement of the marked points on the spindle system.Fourthly, the Parametric modeling of the spindle has been built to get the optimal span of the spindle system. When maintaining the spindle diameter, the stiffness of the spindle system changes with the distance of left bearing and right bearing. When maximum spindle stiffness and minimum line variable have been acquired, the spindle span is defined as the optimal span.