| 摘要 |
A punching machine has a power-driven plunger to which a punch is chucked to be driven into and out of a die for perforating sheet-metal work. The plunger has a punch socket formed centrally in its end for receiving the shank of the punch, and a plurality of ball guideways extending radially outwardly from the punch socket. Locking balls are slidably received one in each ball guideway for movement into and out of locking engagement in an annular groove in the shank of the punch received in the punch socket. Concentrically mounted on the plunger, a cam ring is sprung in one axial direction of the plunger for urging the locking balls into locking engagement with the punch shank. Each locking ball is elongated radially of the plunger with a view to reduction of the machine dimension axially of the plunger for given diameters of the plunger and the punch.
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