Reducing foundry pipe spinning noise
The problem
An automatic pipe spinning machine in a foundry was generating A-weighted noise levels in excess of 90 dB. The pipe mould was housed in a sheet steel cabinet with the pipe being spun at high speed before molten metal was fed into the centre. The spinning action forced the molten metal to the outside of the mould while the cabinet was filled with water to cool the mould and solidify the spun pipe.
The primary source of noise was mechanical vibration in the hydraulic drive mechanism and main mould bearings being radiated from the sheet steel surfaces of the water cabinet and the machine support structure. Noise also came from the cabinet roof, steam vents and the hydraulic power pack.
Pipe spinning machine after modification
The solution
A number of modifications to the machine were made, including the following:
- stiffening the main bearing supports;
- isolating the supports from the main machine chassis, and the chassis from its supporting beams using proprietary machine mounting pads;
- sand-filling the chassis support beams and isolating them from the floor with similar pads;
- isolating the water cabinet from the machine support structure using the machine mounting pads;
- using rubber-bushed hinges on the water cabinet roof panel;
- fitting duct attenuators over steam vent outlets in the water cabinet roof;
- relocating the hydraulic power pack outside the shop.
The cost
About £2000. (1995)
The result
An overall noise reduction in the mould shop of 6 to 7 dB.
Source
Photographs courtesy of Glynwed Foundries. Consultants' report supplied by Sound Research Laboratories Limited, Wilmslow.