Punch press

A punch tool to be mounted on a punch press for punching a sheet-like workpiece in cooperation with a die being formed with a diehole, comprising:

• a punch guide adapted to be mounted on a punch holder of the punch press in a vertically movable manner,
• the punch guide being formed with through-hole means communicating with an interstice between the punch guide and the punch holder, and
• a punch mounted in the punch guide in a vertically movable manner,
• the punch being formed with a fluid discharge orifice means for discharging a fluid into the diehole, and a communication orifice means communicating with the through-hole.

A punch press comprising:

• a frame,
• a die holder mounted on the frame,
• a die formed with a diehole and mounted on the die holder;
• a punch set provided with a punch mounted on a punch holder for performing a punching process on a workpiece in cooperation with the die,
• the punch set being formed with a fluid discharge orifice means for discharging a fluid into the diehole, and
• the punch being formed with a communication orifice communicating with the fluid discharge orifice;
• a ram for striking the punch, formed with a fluid supply orifice for freely communicating with the communicating orifice;
• a connecting pipe means for connecting the fluid supply orifice with a fluid source;
• a shut-off valve means for opening and shutting of the connecting pipe;
• a stroke position detection means for detecting values of the stroke of the ram;
• and
• a shut-off valve control means for controlling the opening and shutting of the shut-off valve means according to the values detected by the stroke position detection means.