Punching apparatus

An apparatus for punching transversely throughgoing coaxial holes in spaced walls of a workpiece, the apparatus comprising:

• a holder supporting the workpiece;
• an outer tool part formed with a pair of transverse bores and displaceable between an advanced position engaged over the workpiece on the holder and outwardly flanking the walls and a retracted position spaced from the holder;
• an inner tool part formed with a transversely throughgoing bore and displaceable in the advanced position of the outer tool part between an advanced position engaged between the walls and with its bore coaxial with the bores of the outer tool part and a retracted position with its bore spaced from the workpiece in the holder, the outer tool part being formed with a waste passage aligned with the inner-part bore in the retracted position of the inner part;
• respective punches axially displaceable in the outer-part bores;
• means for axially displacing each the punches in the outer-part bores in the advanced positions of the inner and outer tool parts and thereby punching a respective piece from the respective wall and pushing the punched-out piece into the bore of the inner tool part;
• a knockout element engageable in the retracted position of the inner tool part in the inner-part bore;
• and
• means including an actuator connected to the knockout element for advancing same through the inner-part bore and thereby pushing the piece therein into the waste passage.