High speed blanking press
The Problem
A high speed strip-fed press used to blank electrical trip-catch components generated operator noise levels of 101dB (at 270 strokes/minute) in a relatively quiet area.
The Solution
- The press legs were found to be welded construction and thus with little inherent damping. Consequently, they respond strongly to the vibration generated in the press frame (to which they are bolted). Calculations based on noise and vibration measurements showed them to be the major noise radiators.
- The press frame was isolated from the fabricated legs by inserting 6mm composite pads between frame and legs. The area and disposition of the isolating material was chosen to provide a mounting frequency of 65 Hz on both legs (despite the differing loads), with care taken to avoid vibration short-circuits.
- The selected mounting frequency avoided all major structural resonances, providing isolation at frequencies above 100 Hz. The octave band analysis below shows the expected increase in noise in the 63 Hz band and the reduction above 100 Hz.
Notes
Carefully designed local vibration isolation and damping can be very cost effective noise control techniques where structural vibration has been diagnosed as the major source of radiated noise. Care must be taken in the selection of the mounting frequency and mounting technique to avoid significant structural resonances.
The Results
An overall noise reduction of 9dB at the closest operator position was achieved. The modifications had no effect on normal machine operation, access or maintenance.
The Costs
£45 for materials.
Information supplied by
Industrial Noise and Vibration Centre Ltd.