Unlike the hydramechanical press brake that converted the hydraulic energy to mechanical energy with a hydraulic motor fixed to an eccentric shaft, the modern hydraulic press brake uses a hydraulic pump and hydraulic cylinders to mover the ram. This design is far more efficient, allowing increased speed and accuracy.
The modern hydraulic press brake can be divided into two basic subgroups , up-acting and down-acting(all other types of press brakes are down-acting only.)
The French designed and were first to use, the up-acting style of press brake. In our opinion, up-acting is the best type of press brake, not only because of the ram’s guidance and arrangement of rollers, but also because of its natural antideflection characteristics. On this machine you have gravity on your side, working with you instead of against you.
For any mechanical device to have movement, it must have some clearance built in to allow the mechanism to function freely. On the press brake, an important clearance lies between the power source and the ram body. The clearance is just right when the machine is new or rebuilt. However, with age and use this clearance will increase (sometimes dramatically), causing an ever-increasing amount of play in the mechanism. When the press is a down-acting, this excess clearance, or “play” is located on the bottom when no load is present. When a load is applied, such as when a piece of material is formed, this error moves to the toe of the connection. This hurts the ram’s repeatability, often leading to vast swings in bend angle from one workpiece to the next, the up-action press brake, on the other hand, always keeps this play on the bottom, whether under pressure or not.
Down-acting hydraulic press brakes represents 90% of all press brakes in use today. Of all the down-acting press brakes, the hydraulic is, by far, the most accurate, these machines are controller by a CNC or DNC controller (computer numerical control or direct numerical control). The computers, in turn, control a proportional valve system. This system allows for ram control in the downward direction, which, in turn, gives accurate bend angle control.