ABSTRACT
Of all the machine tools, the power press or punch press has over the years presented one of the most formidable challenges to the acoustical engineer. In high-speed blanking operations, noise from the stripper plate is often the dominant source of noise. The only reported noise reduction measure is to cushion the plate where it strikes the workpiece with rubber or polyurethane pads or snubbers. In many automatic press operations, noise associated with high-velocity air ejection nozzles is dominant. The basic approach to noise reduction is of course to reduce velocity by moving nozzles closer, using additional nozzles, or using the quieter air shroud, eductor, or diffuser nozzles. The varieties of hydraulic pumps are far too numerous to list. However, there are four basic types which are commonly found in industrial applications: centrifugal, screw, reciprocating, and gear. The sources of noise are many, but general mechanical noise associated with gears, bearings, motor bearings, etc., is often the dominant source.
