duct machine, shearing machine, press brake, bending machine

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Press Brake

A press brake can be described by basic parameters, such as the force or tonnage and the working length. Additional parameters include the amplitude or stroke and the distance between the frame uprights or side housings.

There are several types of brakes as described by the means of applying tonnage: mechanical, pneumatic, hydraulic and servo-electric. In a mechanical press, energy is added to a flywheel with an electric motor. A clutch engages the flywheel to power a crank mechanism that moves the ram. Pneumatic and hydraulic presses utilize air pressure or the pressure of hydraulic oil in cylinders to develop tonnage on the ram. Servo-electric brakes use a servo-motor to drive a ballscrew or belt drive to exert tonnage on the ram.

Until the 1950s, mechanical brakes predominated the world market. The advent of better hydraulics and computer controls have led to a transformation to hydraulic domination of the current market.

Pneumatic and servo-electric machines are typically used in lower tonnage applications. Hydraulic brakes produce accurate high quality products are reliable, use little energy and are safer.

Recent improvements are mainly in the control and a device called a back gauge. A back gauge is a device that can be used to accurately position a piece of metal so that the brake puts the bend in the correct place. Furthermore the back gage can be programmed to move between bends to repeatedly make complex parts. Early brakes relied on the tooling to determine the bend angle of the bend. While specialized tooling for special bends like offsets are still available most bending today is a process called air bending. The angle of the bend is determined in the control. The motion of the ram is controlled to accurately bend the part to the desired angle. Air bending uses less tonnage or energy compared to the old methods of bottoming or coining.