PURPOSE: To work plural processes at the same working machine and to reduce residence times at the stages by providing a means for tapping so that upper and lower dies can be exchanged in a bending machine.
CONSTITUTION: A tap driver 4 is engaged with an upper die fitting block 3 and inserted into an upper ram 2. A tap 12 is rotated and lowered mechanically by the vertical movement of the upper ram 8. Further, electric motor drive system by a battery, too, can be used. Dies can respectively be engaged with and inserted into the upper die fitting block 3 and the lower die fitting block and they can be exchanged with each other. When the tap 12 is exchanged with a tap of another kind, the whole driver 4 is exchanged. The work receiver 9, too, is exchanged similarly.