Patent ID: 8215148
Filing Date: 2012-07-10
Classification: B21D,Y10T

Abstract:
1. A shear punching die assembly having first and second die units in which a material is punched to form a work while the material is clamped between the first and second die units, comprising: a main punch contained in the first die unit and having a cross-sectional shape corresponding to a shape of the work; an ejector contained in the second die unit and positioned axially opposite to the main punch; an ejector biasing member normally biasing the ejector toward the main punch; an ejector retaining device that is capable of acting on the ejector when the first and second die units are in a closed condition, thereby retaining the ejector in a predetermined position; and an ejector releasing device that is capable of acting on the ejector retaining device when the first and second die units are opened over a desired distance, thereby releasing the ejector, wherein the ejector retaining device comprises a pressing body and a retainer member, wherein the retainer member is arranged and constructed to engage the pressing body and press the pressing body toward an outer circumferential surface of the ejector when the first and second die units are in the closed condition, wherein the retainer member is arranged and constructed to be disengaged from the pressing body when the first and second die units are moved to an opened condition, so as to permit the pressing body to move away from the outer circumferential surface of the ejector, wherein the ejector releasing device is composed of the ejector biasing member, wherein the ejector biasing member is arranged and constructed to be capable of moving the ejector when the first and second die units are moved to the opened condition, thereby moving the pressing body away from the outer circumferential surface of the ejector, wherein the ejector is arranged and constructed to vertically move to a desired position against a force of the ejector biasing member when the first and second die units are moved to the closed condition, wherein the pressing body is arranged and constructed to move toward the outer circumferential surface of the ejector when the ejector moves to the desired position, so as to press the outer circumferential surface of the ejector at one end thereof, thereby maintaining the ejector at the desired position, and wherein the retainer member is arranged and constructed to contact the other end of the pressing body so as to prevent the pressing body from moving when the pressing body moves toward the outer circumferential surface of the ejector and presses the outer circumferential surface of the ejector at one end thereof.