| During the high-speed dynamic balance,when the counterweight surface does not coincide with the actual unbalanced surface,due to the flexibility of the rotor,the rotor will be deformed,which will generate new unbalanced force and destroy the original balance.For this reason,a method was developed to identify the plane where the unbalanced force is located.This method improves the efficiency and accuracy of dynamic balance which has important engineering significance.First of all,taking the high and medium pressure rotor of a 600 MW steam turbine as the research object,the factors affecting the deformation of the shaft system are analyzed.When the counterweight surface does not coincide with the actual unbalanced surface,as the unbalance increases,the rotor speed increases,and the distance between the unbalanced surface and the counterweight surface increases,the deformation of the shaft system increases.If there is an imbalance in the middle of the shaft system,the bending deformation of the rotor is very small when the speed is low.According to the balance of force and couple,it is possible to achieve a better balance effect by adding weight on both sides of the shaft system.But for a flexible rotor running at high speed,the rotor will be bent and deformed under the combined action of the original unbalanced force and the weight on both sides.The bending deformation direction of the rotor is consistent with the unbalanced force acting direction.Under the coupling action,the two are completely positively superimposed,the vibration increases,and a good balance effect cannot be achieved.Therefore,the static force identification model can be introduced into the rotating coordinate system,the unbalance identification model in the rotating coordinate system is established,and the dynamic balance test method of the multi-wheel rotor system based on strain is proposed.Secondly,a static force identification model of multi-wheel discs is established.When there is static force on the discs,it will affect the bending moment distribution of the shafting.By measuring the strain values of the left and right sections of each wheel,the bending moment of each section can be obtained,and then the static force on each wheel can be obtained.For a stable running rotor,the unbalanced force is a constant force in a rotating coordinate system that rotates with the shaft.Compared with the traditional dynamic balancing method,this method does not require trial weighting.It can identify the distribution of imbalances on all disks at one timeFinally,a cantilevered and dual-supported rotor test bench was built to verify the dynamic balance method of the multi-disk rotor system based on strain.The results show that the method can accurately identify the imbalance of the cantilevered or double-supported rotor test bench in the rotating state.And the test error that may appear in the actual application of the project is analyzed. |
