Investigation of blanking noise reduction using a hydraulic inertia damper

In an effort to reduce blanking noise, which is very harmful to both the press operator and neighboring people at large, a hydraulic inertia damper has been developed, in which an inertia counter force caused by an inertia mass can be transmitted through a hydraulic conduit against the blanking punch force by means of either a pin provided beneath the punch bottom or a piston above a blank holder. This can effectively decrease the load reduction rate of the punch during breakthrough. This can result in a substantial noise reduction of more than 10 dB for a very simple structure, as well as simple operation of the damper. We also investigated, both experimentally and analytically, the effects of the inertia mass used for the damper and the timing of damper operation, respectively, on the amount of blanking noise reduction possible.