PURPOSE: To enable different machining simply and quickly by structuring a punch assembly with a punch ram and a sub-assembly which is removably secured to the front face of the ram and thereby exchanging only the sub-assembly instead of the whole punch assembly.

CONSTITUTION: When a sub-assembly 22 needs to be removed from a punch ram 20, the whole punch assembly is removed from the housing, with bearing plates 110, 112 taken off from the punch ram 20 and the sub-assembly 22. Then, the engagement of fasteners 82 are all released by inserting a wrench through each opening 90 and rotating for the purpose of reinforcing screws from the screw-attached opening of the punch ram 20. After that, the entire sub-assembly 22 is shifted with the entirety of a separate sub-assembly 22 moved and exchanged with it.