Taking the roller supported horizontal centrifugal casting machine as the research object, the dynamic performance of the centrifugal casting machine, the influence of various parameters on the dynamic performance and the influence of vibration on the final quality of the centrifugal casting furnace tube were systematically studied. Through mechanical analysis, the calculation method of support stiffness and damping of centrifugal casting machine was established. According to the vibration theory, the dynamic model of centrifugal casting machine was established. Combined with the transfer matrix method, the dynamic model of centrifugal casting machine was solved. The vibration performance simulation test device of centrifugal casting machine was designed and built, and the theoretical results were verified by experiments. On this basis, several factors that may affect the dynamic performance of centrifugal casting machine mold were introduced into the dynamic model, including the influence of centroid distribution, the influence of roller and mold surface shape error and surface morphology, the influence of machine foundation and foundation characteristics, etc And the solidification process is included in the vibration model, and the interaction between them is studied. The research contents and conclusions are as follows
(1) The calculation model of support stiffness and damping of centrifugal casting machine is established. Considering the eccentricity and eccentric azimuth of the eccentric mass of each section of the casting rotor, the vibration model of the casting rotor is established. The transfer matrix method is used to solve the model. The case study shows that: the stiffness and damping of the roller support change with the change of the support angle; because the support 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 roller support position and the support angle also have a certain influence on the critical speed, the critical speed in the X direction increases with the increase of the support angle α, and the critical speed in the X direction decreases The results show that the rotational speed decreases with the increase of support angle α; 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 eccentric mass distribution. Under the condition of equal eccentricity, the vibration amount of eccentric azimuth changing according to a certain rule is obviously less than that of eccentric azimuth It’s a fixed situation. The vibration measurement device of centrifugal casting machine supported by roller was designed and built, and the test results were consistent with the theoretical calculation results.
(2) A mathematical model was established to describe the geometric error and surface roughness between the roller and the mold. The method to calculate the coordinates of the actual contact point between the roller and the mold was given. According to the position of the actual contact point, the exciting force of the supporting roller on the rotor of the mold was obtained. Combined with the transfer matrix method, a mathematical model was established to consider the geometric error and surface roughness of the roller and the mold The calculation method of mold vibration performance. The results show that: after considering the shape error of roller and mold, the number of resonance speed in amplitude frequency response curve increases; at the same speed, the rotor vibration caused by the shape error of roller and mold is larger than that caused by unbalanced centrifugal force; the excitation force caused by roughness and the maximum amplitude of node increase approximately linearly with the increase of roughness; the roughness is not uniform At the same time, the rotational speed with larger amplitude in amplitude frequency response is basically the same; at the same rotational speed, the rotor shape is similar at the same time, but the amplitude changes with the change of roughness; the range of motion trajectory of mold center increases with the increase of roughness.
(3) Based on the vibration theory and rotor dynamics theory, the vibration model of roller supported centrifugal casting machine was established. Firstly, the calculation method of the comprehensive stiffness and damping of the shoe foundation and the foundation when the rectangular foundation acts on the elastic half space foundation is established. According to the vibration theory, the vibration differential equation of the system is established, and the vibration equation is solved by the transfer matrix method. The results show that: after considering the foundation and foundation in the model, the natural frequency of the system is 2 orders more than that without considering the foundation and foundation, and the natural frequencies of each order decrease with the increase of foundation height, increase with the increase of foundation buried depth, and decrease with the increase of foundation bottom size? The results show that the resonance amplitudes of each order increase with the increase of the foundation height, decrease with the increase of the embedded depth, and decrease with the increase of the size of the bottom of the foundation; under the working speed, the higher the height of the foundation or the greater the embedded depth, the closer the vibration mode of the rotor is to that without considering the characteristics of the foundation and foundation; the influence of the size of the bottom of the foundation on the forced vibration performance of the rotor is more complex, However, when the size of foundation bottom increases to a certain extent, the foundation can be regarded as rigid in vibration analysis.
(4) The coupling model of molten steel flow and mold vibration in centrifugal casting of furnace tube was established. Combined with the transient transfer matrix method, the model was solved. At the same time, the amount of mold vibration and the flow of molten steel in each time were obtained. Combined with the example analysis, the influence of the coupling of molten steel flow and mold vibration on the wall thickness of centrifugal casting furnace tube was explained. The results show that the flow of molten steel and the vibration of the mold are influenced by each other. After the molten steel is poured into the mold, the vibration performance of the whole system is affected, including the amplitude and resonance speed. The amplitude increases with the increase of the amount of molten steel, and the resonance speed decreases slightly with the increase of the amount of molten steel. After considering the influence of mold vibration, the uneven wall thickness of the furnace tube occurs, which is related to the eccentricity of the mold and the amount of steel poured in: the greater the eccentricity of the mold, the more serious the uneven wall thickness of the furnace tube; the greater the amount of steel poured in, the more serious the uneven wall thickness of the furnace tube.
(5) A coupled model of molten steel flow mold vibration molten steel cooling in horizontal centrifugal casting was established. The model can be used to solve the flow of molten steel in each section at any time, the vibration of the mold and the temperature of each point. The results show that: the smaller the mass of the casting furnace tube, the shorter the time to complete solidification; the temperature of both ends of the casting tube and the mold is slightly lower than the intermediate temperature at the same time; in a certain period of time, the vibration of each node increases with the increase of time due to the gradual increase of mold temperature; in the same section, the maximum wall thickness of the casting tube increases with time The results show that the minimum wall thickness gradually decreases with time, that is, the wall thickness difference increases with time; the final wall thickness difference of each section of the casting furnace tube is in the order of micron, and the value of each wall thickness difference is determined by the mass eccentricity of the mold itself; the influence of the quality of the casting tube on the wall thickness difference is much smaller than that of the vibration.