Research On Vibration Characteristics Of High-speed Franking Machine Based On Operational Modal Analysis

At present, franking machines which can print stamps automaticly are used intensively by postal services cause they greatly increased the work efficiency of postal department. However, a current domestic high-speed franking machine is only capable to keep working stably within the rate of 20,000 envelops per hour. And while reaching the rate of 30,000 envelops per hour, the vibration of the machine will be acute, which will reduce the quality of stamps distinctly. Therefore, it is extremely necessary to make an intensive study into the vibration characteristics of franking machine.Classically dynamics analysis always use Finite Element Modal Analysis(FMA) method or Testing Modal Analysis(TMA) method. However, both of them have shortages. Accordingly, this paper applies a new kind of research method combining both FMA and TMA which are mentioned above. Besides, it also replaces the traditional TMA by operational TMA which is based on the theory of operational model analysis. This kind of analysis method can extract modal parameters from response-only data, so that it enables equipments to be identified in modes under normal operating conditions.The main work and achievements of this dissertation are listed as follows:1) Mainly introduces FMA and TMA in theory, especially the operational modal analysis.2) Establishes the three-dimensional model of the stamping part of franking machine in Pro/E and import it into ANSYS to obtain finite element model and figures out the first 5 steps of modal parameters of the stamping part.3) Practises an operational TMA to obtain the first 5 steps of modal parameters of a franking machine. Then compares the parameters extracted respectively by FMA and TMA to validate the correctness of theoretic modal model.4) Under the guidance of finite element model, the franking machine could be improved. Then repeats the operational TMA to prove that the vibration situation of the equipment has been greatly improved, the quality of stamps are increased evidently, and finally the high-speed franking machine is able to work smoothly at target speed.