How Does a Hydraulic Press Brake Work?

Hydraulic press brakes are versatile machine tools used in sheet metal manufacturing industries for bent metal shapes.

The primary components of a hydraulic press brake are its hydraulic system, cylinders, rams and controls. Gaining an understanding of how these elements function is essential for successful use.

Hydraulic system

Hydraulic press brakes operate by exerting force on metal sheets with a hydraulic cylinder. This method is precise and gives you more control over how much pressure is applied to the sheet.

Hydraulic press brake systems consist of four primary elements: the pump, motor, series of valves and hydraulic fluid. When combined, these elements produce an incredibly powerful bending machine.

Hydraulic press brakes are widely used in various industries to stamp, form, bend or press metal products. They're especially ideal for producing parts with complex shapes.

Hydraulic press brakes are not only highly reliable, but also efficient and cost-effective. Not only that, but they use minimal energy and safety compared to pneumatic or servo-electric machines.

Cylinders

Hydraulic press brakes work by creating a pressure difference between two pistons. This produces higher force than mechanical presses and offers greater versatility when it comes to bending materials.

On a hydraulic press brake, two cylinders are connected by a tube filled with fluid. When an operator presses one of these cylinders, fluid pushes through the pump and onto the second piston.

During operation, the valve 57 opens, the motor 56 runs and the weight of ram 28 presses pistons 88 in each cylinder downwardly to create a pressure differential between them. This pressure differential is then transferred to fluid in each cylinder 32 and then transferred up into hydraulic fluid reservoir 52.

Cylinders 32 consist of a housing 38 and end closure member 82, both secured to the housing with tie rods. An inlet 76 allows pressurized hydraulic fluid from line 50 into each cylinder, while an outlet 83 allows communication with the closure member 82.

Rams

Hydraulic press brakes use their rams to press metal into shape, with some models even moving the bed up for extra pressure application.

A hydraulic press brake is equipped with a ram and back gauge that move independently. This back gauge measures the flange length of a workpiece and adjusts its bending angle accordingly.

Some hydraulic press brakes are direct drive, where an electric motor propels the ram up and down. These machines are faster and more efficient than hydraulic presses but usually have a much lower tonnage limit.

Another type of press brake is a hybrid, which utilizes a servo-electric motor to drive the ram. This motor can be programmed to pump or unpum the ram according to what your CNC commands specify.

Some hydraulic press brakes also feature a rupture disc to relieve system overpressure before damage can occur to the press brake. This helps avoid operator injuries and costly repairs.

Controls

Hydraulic press brakes operate by applying hydraulic pressure to a ram that presses sheet metal against its lower die, creating an incredibly accurate and customizable process.

They can also be utilized to shape parts that are long and thick. When combined with robots, these automated bending systems help save time and energy on the shop floor by creating automated bends.

Press brake hydraulic cylinders are controlled by a computer program, enabling an operator to set the machine up for bends. This process is known as NC (Numeric Controlled) or CNC (Computer Numeric Controlled).

The CNC ESA S630 control system allows programs to be edited graphically or numerically, new dies and punches can be managed, bending sequences controlled, collisions avoided, simulations conducted on sheet metalwork components and machine sensors/inputs/outputs diagnosed intuitively and clearly.