BORING DEVICE

摘要

There is provided a punching unit arranged so that a plurality of punches (52a through 52c and 53 or 89a through 89d) is grouped into a first group having a predetermined number of punches and into a second group containing any one of the punches in the first group and having a less number of punches and so as to produce a punching state of the predetermined number of punches by reciprocating a reciprocating member (35 or 75) within a first movable range and by vertically moving the punches of the first group through an intermediary of cams and followers (62 or 25) corresponding to the first group and another punching state of the less number of punches by reciprocating the reciprocating member (35 or 75) within a second movable range and by vertically moving the punches of the second group through an intermediary of cams and followers corresponding to the second group. This arrangement allows the number of punches and dies to be reduced as compared to the prior art unit and the structure of the unit to be simplified with less number of parts.