Construção e balanceamento de um cilindro a alta rotação

Abstract

It was developed a high speed rotor modelas a basis for a further study on dynamic of gases. We have obtained a model structure consisting of two round bases (where are fixed the bearings), spaced by three small columns. This assembly has one of its ends fixed to a bench. The rotor consists of three parts: two shaft-plates fitted each one at the ends of a hollow cilinder made with acrilic. Since we have this model carefully machined and assembled we have proceed toward the dynamic balance of the system. That was obtained through the vibration measurement at each one of the shaft-plates in three different arrangements: 1. the rotor as built up. 2. the rotor with a known weight in one of the shaft-plates. 3. the rotor with the sarne known weight at the other shaft- plate. So we have known the position and magnitude of its largest vibration and then we are able to balance the system. For the above mentioned measurements we have used a sensor specialls developed for measuring radial displacemenxs, in arder of micra, and also equipments for recording the vibrations detected by those sensors. At first have been used for recording a tape-recorder and an oscilograph. However these equipment was not adequate dueto the noise added to the sensors input signal by the tape-recorder. Also there have been demonstrated that the oscilograph could not respond quickly enough to the frequency generated by the sensors. Therefore it was used an osciloscopy anda Polaroid camera in order to register graphically the vibration amplitudes. We have concluded that in the shaft-plate close to the bench there was no vibration at all, however in the upper plate the vibration was considerable. Then the rotor was dinamically balanced using the ''discmethod". The results were well satisfactory, proving in that way the viability of the method.