Punch holder apparatus

A punch holder apparatus (1), for holding a punch chip (11), the holder apparatus (1) comprising:

• a punch holder (7) including a punch mounting hole (9) extending in a longitudinal direction of the punch holder, the punch holder comprising an inspection hole (35) extending in a direction perpendicular to the longitudinal direction of the punch holder, the inspection hole (35) being opened from an inner circumferential surface of the punch mounting hole (9) toward an out side of the punch holder (7) thereby enabling to see the inner surface of the punch mounting hole (9) of the punch holder through the inspection hole (35) from the out side of the punch holder (7);
• an engagement piece (37) to be mounted in the inspection hole (9), the engagement piece being movable in the inspection hole to the inner circumferential surface of the punch mounting hole (9), the engagement piece (37) being spherical in shape so as to engage in a groove (25) in a periphery of the punch chip (11) which is inserted into the punch mounting hole (9);
• a lock piece (45) including a receiving allowable concave section (41) which has a smaller radius than a radius of the lock piece thereby forming a circumferential recess (41a) surrounding a peripheral portion of the receiving allowable concave section (41), the lock piece (45) being movable in a direction parallel to the longitudinal direction of the punch holder (7), the circumferential recess (41a) receiving the engagement piece (37) which is movable in the direction perpendicular to the longitudinal direction of the punch holder (7) in a first position where the receiving allowable concave section (41) and the circumferential recess (41a) are located at a height of the inspection hole (35) in the longitudinal direction of the punch holder (7) to receive the engagement piece (37) into the circumferential recess (41a), the lock piece (45) further including an engagement piece pushing-out holding section (43) at a top end of the receiving allowable concave section (41) which has the same radius as the radius of the lock piece (45);
• and
• a device (39) pressing the lock piece (45) so that the engagement piece pushing-out holding section (43) is normally located in a second position where the engagement piece pushing-out holding section (43) is located at a height of the inspection hole (35) in the longitudinal direction of the punch holder (7) to push the engagement piece (37) toward the groove (25) in the periphery of the punch chip (11),
• wherein the location of the lock piece (45) is capable to be inspected from the out side of the punch holder (7) through the inspection hole (35) in the direction perpendicular to the longitudinal direction of the punch holder (7) whether the lock piece (45) is located in the first position or the lock piece is located in the second position in the direction parallel to the longitudinal direction of the punch holder (7).