By adopting a non-contact type steady rest, a large vibration reduction effect is obtained.

Noise was generated in the vicinity of the steady rest of the 750A vertical pipe for cooling water, and as a result of investigation, it was found to be a solid sound disturbance due to the vibration propagated from the steady rest to the body. As shown in Fig. 1, the existing steady rest is a type in which a rubber pad is sandwiched and tightened with steel plates, and the pipe and steel frame contacted to transmit vibration.

We have newly delivered a non-contact type steady rest. Unlike the conventional steady rest, the clearance with the pipe is increased to prevent the vibration of the pipe from propagating to the body. A 6-point rubber is placed inward as a piping guide to serve as a cushioning material when the piping comes into contact (Fig. 2). The amount of rubber deflection during contact is assumed to be approximately 1 mm, which is effective in suppressing excessive pipe displacement. The vibration isolation level is positioned as an intermediate performance between the rubber pad and the spring pad as shown by the orange line in Fig. 3.

The main component of the vibration propagating from the pipe is the peak component of 147.5Hz (4 pole motor 24.5Hz x pulsation of 6 blades) as shown in Fig. 4, and this component is 20dB or more (1/10 or less) due to steady rest update measures. To). The noise level near the shaft on each floor was NC-45 to 55 before the countermeasure, but was reduced to NC-25 to 30 after the countermeasure.