Considering the processing method of roller and mold, the surface roughness Ra is in the range of 1.6-25 μ m. The Ra value is in this range when the influence of surface morphology on mold vibration performance is studied. Figure 1 shows the variation of the maximum amplitude of the excitation force caused by surface roughness with a. It can be seen that the excitation amplitude increases approximately linearly with the increase of RA. In addition, at the same rotational speed and RA, the excitation amplitude in the horizontal X direction is smaller than that in the vertical direction. This is because the component direction of the excitation force caused by the contact between the left and right sides is opposite in the horizontal direction, and part of the excitation force is offset, while the component direction in the vertical direction is the same.
Fig. 2 shows the variation of the maximum amplitude of three nodes with the excitation force. Node 1 is located at the end of the mold, node 21 is located at the roller support, and node 51 is located in the middle of the mold. It can be seen that the variation trend of the maximum amplitude with RA is consistent with that of the excitation force amplitude with RA in Figure 1. When the value is larger, the amplitude is also larger, and the relationship between them is approximately linear.
Figure 3 shows the amplitude frequency response of node 1 in the range of 0-2000r.min (- 1) under different roughness. It can be seen that under different roughness, the rotation speed with larger amplitude is basically the same. In this example, when it is about 600r.min (- 1), 800r.min (- 1), 950r.min (- 1), 1550r.min (- 1) and 1900r.min (- 1), the rotor amplitude is larger.
Figure 4 shows the rotor configuration at different values when ω 1 = 1500 r.min (- 1). It can be seen from Figure 4 that at the same time, the shapes of rotors with different RA values are similar, and the difference lies in the amplitude. Figure 5 shows the node motion trajectory (node 1) under different RA values when ω 1 = 1500r. Min (- 1). The node motion trajectory more intuitively reflects the influence of RA on the amplitude: the larger the Ra value is, the larger the motion range of the node center is, that is, the larger the amplitude is.