Workpiece shift apparatus for punch press

A workpiece shift apparatus comprising:

• a bottom plate, a first large piston cylinder being installed on the bottom plate and having a first large piston rod being movable in a first direction, a first small piston cylinder being movably connected with an end of the first large piston rod and having a first small piston rod being movable in a second direction perpendicular to the first direction, a first handspike being connected to and movable with the first small piston rod;
• a first pushing plate movably mounted on the bottom plate, the first pushing plate having a plurality of first cutouts defined in one edge thereof for receiving the first handspike, and a plurality of arcuate first steps formed at an opposite edge thereof;
• a middle plate slidably attached on the bottom plate, a second large piston cylinder being installed on the middle plate and having a second large piston rod being movable in a third direction that is opposite to the second direction, a second small piston cylinder being movably connected with an end of the second large piston rod and having a second small piston rod being movable in the first direction, a second handspike being connected to and movable with the second small piston rod;
• a second pushing plate movably mounted on the middle plate, the second pushing plate having a plurality of second cutouts defined in one edge thereof for receiving the second handspike, and a plurality of arcuate second steps formed at an opposite edge of the second pushing plate;
• and
• a top plate movably attached on the middle plate and adapted for holding a workpiece thereon, wherein
• the first steps of the first pushing plate push the combined middle plate and top plate in the second direction when the first handspike pushes the first pushing plate in the first direction;
• the second steps of the second pushing plate push the top plate in the first direction when the second handspike pushes the second pushing plate in the third direction;
• and
• the first handspike is sequentially engaged in the first cutouts to move the first pushing plate in the first direction, thereby pushing the combined middle plate and top plate in the second direction, and the second handspike is sequentially engaged in the second cutouts to move the second pushing plate in the third direction, thereby pushing the top plate in the first direction.