Patent ID: 7171883
Filing Date: 2007-02-06
Classification: B21D,Y10T

Abstract:
1. The punching unit for a punching apparatus for punching a hole at a predetermined location on a work since, comprising a punch; a die; and a fitting jig for positioning the punch and the die relative to each other, wherein each of the punch and the die has plurality of faces for fitting and the fitting jig has datum planes to be fitted with the planes for fitting of the punch and the die, wherein said punch and the die are rotatable independent of the punching machine, about an axis parallel to the direction for punching and can rotate simultaneously in a state where the datum planes of the fitting jig are attached with each of the planes for fitting of the punch and the die, and wherein said fitting jig has a U-shaped cross section having a pair of arms on one inner surface of which one of the datum planes is arranged and on the other one inner surface of which the other one of the datum planes is arranged in order to hold the punch and the die between said pair of arms and also order to fit the planes for fitting of the punch and the die with the datum planes of the fitting jig while rotating about the axis.