piston and cylinder acts in a linear manner and is directly connected to the ram. The form of frame construction of hydraulic presses is largely similar to that of mechanical presses. The hydraulic drive units are easily accommodated in the machine frame. Consequently, several hydraulic drives can readily be built into a single machine for complicated forming and cutting operations (drawing, extruding, cutting, swaging, etc.), and the required motions may be easily coordinated.
A press brake is essentially same as a gap-frame press except for its long bed from 6 to 20 feet (1.8～6m) or more. It is used basically for various bending operations on large sheet metal parts. It can also be used with a series of separate sets of press tools to do light piercing, notching, and forming (Figure 11). This allows parts of a complex design to be accurately made without a high-cost press tool by simply breaking the complex part down into several simple operations. This type of operation is used on low-run or prototype parts.
Figure 10 typical hydraulic press Figure 11 Typical press brake
Sheet metal can be bent easily with simple fixtures using a press brake. This press brake utilizes long dies in a mechanical or hydraulic press and is suitable for small production runs. The tooling; is simple, and it is adaptable to a wide variety of shapes, furthermore, the process can be easily automated. Die materials for press brakes may range from hardwood (for low-strength materials and small production runs) to carbides. For most applications, carbon-steel or gray-iron dies are generally used.
