PURPOSE: To increase the top surface space of a die block by pivotally providing a dhuck body and a chuck pawl on a supporting shaft provided in parallel behind a cam shaft with a supporting arm between, and allowing a check to have opening/closing interlocking mechanism and a cam to connect and disconnect each other.

CONSTITUTION: A check main body equipped with a chuck pawl 4 and a chuck opening and closing interlocking mechanism 5 is provided pivotally on a supporting shaft 9 provided in parallel behind a cam shaft 8 through a supporting arm 7 in such a way that it oscillates around the supporting shaft 9 as a fulcrum. A cam roller 17 is provided to the link lever 5a of the interlocking mechanism 5 and when the chuck main body 6 is sent down, the cam roller 17 and a cam 10 provided on a cam shaft are allowed to operate correspondingly; when the chuck main body 6 is raised, the chuck separates from the cam 10 to prevent the transmission of the motion of the cam 10. Consequently, while the chuck main body 6 is raised, the space A on the top surface of a die block 18 is increased greatly and repair, inspection, etc., are carried out in safe.