Patent ID: 8225703

Claim:
A hold-down apparatus for plate shears, the hold down apparatus comprising: a hold-down device; and a mechanically controlled invariable displacement apparatus configured to press the hold-down device on a plate to be out by the plate shears, wherein the mechanically controlled invariable displacement apparatus further comprises: a cam having a cam surface; a roller lever configured to ride on the cam surface and to be raised from the cam surface; at least one actuating lever coupled to the hold-down device; and a threaded rod, the threaded rod having a first end with right-handed thread and a second end with a left-handed thread, the threaded rod coupled between the roller lever and the at least one actuating lever, wherein an initial position of the hold-down device, before the start of the invariable displacement, is adjustable, wherein a distance between the roller lever and the at least one actuating lever is varied by rotation of the threaded rod, whereby the initial position of the hold-down device is adjusted by the threaded rod.