Multi-step bending machine e.g. press brake

摘要

A hydraulic pump is driven by a hydraulic motor with a main cylinder hydraulically moving an apron toward a fixed apron, and a limit valve (ULV) releasing hydraulic pressure supplied from the pump to the cylinder. A feed screw is rotated by a D-axis motor, and a movable element is moved to and fro by the screw. A lever pivotally supported by a link (13) has a free end (14A) contractable with the movable apron and a second free end (14B) contactable with the limit valve.When the moable element is driven in a first direction (+) by the D-axis motor via the feed screw, the second end of the lever actuates the limit valve open to move the apron away from thefixed apron. When the movable element is driven in a second direction (-), the second end of the lever deactuating the valve is closed to move the apron toward the fixed apron. When the apron is moved close to the fixed apron for bending, the first end of the lever is brought into contact with the movable apron so that the second end of the lever is to actuate the limit valve open to move the apron away from the fixed aprong for achieving multistep bending