What Is a Press Brake?
A press brake is a typical press machine for bending metal plates under pressure, also called a bending machine. Typically, it is used to bend steel plates, including aluminum and stainless steel plates, with lengths up to 4m and thickness ranging from 0.5 to 5mm.
The metal plate is placed between the upper die with a pointed tip, named “punch,” and the lower die with a V-shaped groove, named “die,” and the metal plate is bent by applying press pressure.
Incidentally, there is a theory that the name “press brake” comes from the fact that in the days when CNC press machines were not available, bending was performed by skillfully manipulating the brake of a press machine manually.
Uses of Press Brakes
Press brakes are mainly used to bend relatively thin stainless steel, aluminum, steel, and other metal sheets. The most basic application is 90-degree bending, also known as L-shaped bending.
Since metal sheets are subject to spring back, or warping due to elasticity that causes the sheet to return to its original shape, the pressure applied to the die and the positioning of the metal sheet are important points in the bending process that require precision accuracy.
In addition to L-shape, other applications include U-shape, V-shape, Z-shape, hemming of folded shapes, and forming of complex curves.
Principle of Press Brakes
Press brake drive systems can be broadly classified into mechanical, hydraulic, servo, and hybrid (hydraulic-servo) systems that combine hydraulic and servo systems.
In the past, most press brakes were mechanical press brakes with a crank-shaped power unit. However, due to their difficult controllability and inconsistent processing speeds, these press brakes are not widely used in recent years, with only a limited number of manufacturers producing them.
The hydraulic type is characterized by the use of a hydraulic cylinder to power the press, and despite its relatively compact structure, it is able to achieve high pressurizing capacity and is the mainstream in the industry.
The servo type uses a servomotor to generate press power and has the advantages of high controllability and the ability to change the processing speed freely, as well as low maintenance costs. However, compared to hydraulic presses, servo presses generally have a lower pressurizing capacity.
The servo-hydraulic system combines the advantages of the hydraulic and servo systems and is a drive system that has recently appeared in the press brake industry. The servo-hydraulic pump is driven by a servomotor, which enables high controllability and high pressurization of the hydraulic type at the same time.
In terms of machine shape, the C-type press, which has a wide space in front for easy operation versatility, and the straight-sided (gantry) press, which has pillars at the four corners and excels in high-pressure resistance, are generally used.