Research On The Torsion Effect Of Swing Frame Of Single-plane Vertical Dynamic Balancing Machine

When the ratio of length to diameter is less than 1/5,the rotor is usually considered as a disc rotor.This kind of rotor is inevitably affected by its own unbalanced force at work,which will cause bad effects like vibration,noise,fatigue damage,etc.Therefore,a single-plane vertical balancing machine must be used to balance it.At present,hard bearing single-plane vertical balancing machine is usually calibrated by influence coefficient method or the three-point method.After the calibration,the “accurate measurement” can be achieved for the workpiece in the measurement range of the balancing machine.The calculation method of hard bearing single-plane vertical balancing machine is based on one degree of freedom(DOF)translational system.The load of the spring plate is the centrifugal force by the disc rotor.In fact,the vibration of swing frame system is the result of the coupling between the translational and torsional vibration,so the measurement error is caused by the neglect of torsional vibration.In the dynamic balance test,it is found that the change of workpiece masses or the positions will indeed bring a large measurement error.Therefore,this paper analyzed the measurement error of the hard bearing single-plane vertical balancing machine from torsion effect and explored the relationship between the torsion effect and the workpiece masses and the workpiece positions.A translational mechanical model of one DOF only considering translational vibration and two DOFs mechanical model considering translational and torsional vibration and corresponding kinematic equations are established.According to the kinematic equation of two degrees of freedom,the formula of the change law of the vibration center of the system is derived,and the influence of the rotation speed,the position and the mass of workpiece on the vibration center is analyzed.The formula of the translational stiffness and the torsional stiffness of the vibrating reed plate of a single side vertical balancing machine are derived by the method of material mechanics,and the relationship between the torsional stiffness and the size of the spring plate and the position of the spring plate is also analyzed.By experiment,the variation of the torsion effect with the mass and position of the workpiece is verified.Through the error analysis of the experimental torsional stiffness and the theoretical torsional stiffness,the correctness of the formula of the torsional stiffness of the spring plate is proved,and the nonlinear change law of the torsion effect and the torsional stiffness is proved.On the basis of experimental verification,the error of the single-plane vertical balancing machine is analyzed.The system error caused by the imbalance of spindle and fixture can be solved by the method of weight-removal method.The error caused by the eccentric installation of the workpiece can be solved by the electrical compensation method.At the same time,the principle error caused by the torsion effect is analyzed,and the measurement error caused by the change of the workpiece mass or position is analyzed by influence coefficient method.The maximum measurement error is 19.16% when different workpiece masses are calibrated,and the maximum measurement error is 32.95% when different workpiece positions are calibrated.It is proved that the permanent calibration method of the single-plane vertical balancing machine is not reasonable.