# Calculation function expression of mold and roller error in centrifugal casting

In practice, the geometric error between the supporting roller and the mold is often difficult to be expressed by a definite function. In this case, the calculation method established in this chapter can also be used to calculate it. Figure 1 shows the initial time of the left and right rollers and the outer circle of the mold? Discrete curve of group error. Through programming calculation, the amplitude frequency response of cast rotor in X direction can be obtained when the roller speed is in the range of 0-2000 r.min (- 1), as shown in Figure 2.

It can be seen from Figure 2 that the maximum amplitude of the rotor also has multiple local peaks when the driving roller speed is in the range of 0-2000 r.min (- 1). When considering the geometric errors between the roller and the mold surface, there are three obvious peaks, and the corresponding roller speeds are about 320r. Min (- 1), 925r. Min (- 1) and 1775r. Min (- 1), respectively. If only considering the geometric error between the roller and the mold surface, there are six obvious peaks, and the corresponding roller speeds are 320r. Min (- 1), 925r. Min (- 1), 1200R. Min (- 1), 1250r. Min (- 1), 1450r. Min (- 1) and 1725r. Min (- 1). When considering the bearing error at both ends, the maximum amplitude occurs at the roller speed of 925r.min (- 1), reaching 0.011mm. When considering only the bearing error at one end, the maximum amplitude occurs at the roller speed of 1725r.min (- 1), reaching 0.041mm.

Figure 3 shows the shape of the mold rotor caused by the error between the roller and the mold when ω 1 = 2000 r.min (- 1). It can be seen from the figure that, similar to figure 1, when the geometric errors between the roller and the mold surface at two supporting positions are considered at the same time, the shape of the mold rotor is symmetrical about the center of the mold, the point with the largest amplitude is at the end of the mold, and the maximum amplitude is 0.125 μ M. When only considering the geometric error between the roller and the mold surface at one supporting position, the shape of the mold rotor is asymmetric, and the maximum amplitude is also at the end of the mold, which is 0.272 μ M.

By summarizing the calculation results with and without considering the geometric error, it can be seen that the vibration performance of the casting rotor has changed greatly after considering the surface geometric error of the roller and the centrifugal casting mold. Therefore, in order to reduce the vibration, the machining accuracy of the roller and the mold should be ensured as much as possible. 