New technologies for the localisation and characterisation of sound sources in woodworking machines

摘要

Approximately one third of European workers are exposed to harmful levels of noise for a quarter of their working time.Woodworking machines are one of the noisiest machine tools. In order to protect workers from physical agents at work, the European Parliament and the Council of the European Union have adopted the Directive 2003/10/EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (noise). In order to develop low-noise woodworking machines, it is necessary to know the location of their dominant sound sources.In this paper new approaches are used to locate dominant machine assemblies by means of microphone arrays, such as beam forming or acoustic camera. The acoustic data, which is superimposed by the image of the woodworking machine,allows the localisation of sound source positions. On the basis of time data, it is possible to characterise each sound source time-and frequencydependently. Dominant noise sources in woodworking machines are primarily the fast rotating cutting tools in the area of suction hoods.The noise emission of such systems can be described by means of Computational Aero-acoustics(CAA).All aero-acoustic sources can be obtained from a complete CFD-solution (computational fluid dynamics).The numerical determination of aerodynamically generated noise and the potential of the above mentioned methods represent part of current research.