Dynamic model construction and performance of centrifugal casting machine

(1) Taking the roller supported horizontal centrifugal casting machine as the research object, the calculation model of its support stiffness and damping is established, and then the vibration model of the mold rotor is established based on the vibration theory. The eccentricity and eccentricity angle of each section of the mold rotor are considered in the vibration model, which can calculate the different eccentricity mass and different distribution of the mold rotor The transfer matrix method is used to solve the model.

(2) Through the analysis of a specific centrifugal casting machine, the vibration performance of the mold rotor of centrifugal casting machine and the influence of some parameters on the vibration performance are studied. The results show that: the stiffness and damping of roller support change with the change of support angle: the larger the support angle is, the greater the support stiffness of single roller is; after equivalent to the horizontal and vertical direction, the horizontal support stiffness and damping increase with the increase of support angle, while the vertical support stiffness and damping decrease with the increase of support angle.

(3) Because the supporting stiffness and damping of the roller in the horizontal and vertical directions are not equal, the critical speeds in the two directions are not equal. The working speed of the centrifugal casting machine is about 75% of its first critical speed, and it is safe to run at its working speed. In addition, the roller supporting position and supporting angle also have certain influence on the critical speed: the critical speed in the X direction changes with the support angle The results show that with the increase of bearing angle a, the critical speed increases, and the critical speed decreases; the value of the first critical speed is the largest when the bearing span L3 = 2.8m, which indicates that the value of L3 = 3M is reasonable.

(4) The distribution of eccentric mass has a great influence on the unbalance response of the cast rotor. The maximum amplitude, mode shape and node position of the maximum amplitude of the cast rotor are different with different distribution of eccentric mass. Under the condition of equal eccentricity, the vibration quantity when the eccentricity azimuth changes according to a certain rule is obviously less than that when the eccentricity azimuth is fixed. The results show that the maximum amplitude of the rotor increases with the increase of the bearing angle, and the order of magnitude of the maximum amplitude is 10 (- 5) m; when the casting speed is 3000 r.min (- 1), the rotor vibration is large when the bearing spacing L3 = 3.6-3.7 M.

(5) In order to verify the correctness of the theoretical model, an experimental device for vibration measurement of roller supported centrifugal casting machine was designed and tested. During the test, different rotational speeds and different measuring positions were taken to observe the variation of vibration with rotational speed. The experimental results show that the vibration of each point increases with the increase of the rotating speed, which is consistent with the theoretical calculation results, indicating that the theoretical model established in this chapter is correct.

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