Stamping tool for producing small precision - holes

摘要

Tool for the stamping out of small diameter precision holes in metal sheets has two concentric punches. The inner centrally disposed punch produces an initial blind pilot hole with bulges along its upper edges. After retraction the outer punch enters the workpiece material causing metal flow towards the centre where to it is free to expand. This is followed by the downward motion of the inner punch, catching up the outer punch creating a cpd. punch which finishes the hole by shearing the metal and etching the cut out piece produced. This method results in a hole which is free from distortion near its edges and cleanly cut.