A press brake is fundamentally built on a vertical frame structure. Its core consists of seven major assemblies: the machine frame, power transmission system, ram actuating mechanism, back gauge positioning system, tooling system, CNC control system, and safety and auxiliary components. These parts work together to accurately form and bend sheet metal.
I. Machine Frame: The Load-Bearing "Skeleton"
The frame is the foundation of the entire machine. All core components are mounted on it, directly determining the machine's rigidity, resistance to deformation, and long-term precision stability.
It mainly comprises the left and right columns, the lower worktable (the lower die mounting platform), the upper connecting beam, the base frame, and internal reinforcing rib structures.
Mainstream models generally adopt an all-steel, integrally welded structure. After welding, the frame undergoes stress-relief annealing or vibratory aging treatment to eliminate internal stresses, giving it strong resistance to torsion and tilting. Small precision press brakes typically use a C-frame single-column design, which offers a more open operating space, while large-tonnage machines mostly use a two-column gantry frame for greater load-bearing rigidity.
To ensure a consistent bending angle across the full length of the workpiece, machines are generally equipped with a crowning compensation mechanism that actively offsets the elastic deformation of the frame during bending. Common forms include proportional hydraulic cylinder compensation and mechanical bottom-dead-center compensation.
II. Power Transmission System: The "Power Heart" of Bending
This system supplies power and bending force to the ram, determining the machine's bending capacity, response speed, and operating characteristics. It is divided into two types according to the drive method:
• Hydraulic transmission (conventional hydraulic press brake): Mainly comprises the drive motor, hydraulic pump, control valve block, hydraulic cylinders, oil lines, and oil tank. Oil pressure drives the extension and retraction of the cylinder piston rods, pushing the ram downward to deliver the bending force. This is widely used in large-tonnage machines.
• All-electric servo transmission (all-electric press brake): Mainly comprises the servo motor, timing pulley/reducer, ball screw, and screw nut. The servo motor drives the rotation of the screw, moving the ram up and down. This provides more precise position control, faster response, and eliminates hydraulic oil contamination.
III. Ram Actuating Mechanism: The "Stamping Arm" That Does the Work
Also known as the sliding beam, this is the core actuating component that drives the upper tool in its reciprocating up-and-down motion, applying the bending force directly to the sheet metal.
It mainly comprises the ram body, linear guide pair, tool clamping device (quick clamp), and stroke limit elements.
The ram moves vertically up and down along the column guides; guiding accuracy directly affects the perpendicularity and angle accuracy of the bend. The quick-clamp device at the front allows the upper die to be clamped and changed rapidly without complex tools, greatly reducing die-change time in high-mix production.
IV. Back Gauge System: The "Precision Ruler" of Size Control
Its function is to position the insertion length of the sheet, accurately controlling the size of the bent flange. It is the key component determining workpiece dimensional accuracy.
It mainly comprises the servo motor, ball screw, linear guide, gauge beam, and adjustable gauge fingers.
The back gauge on a standard three-axis press brake can move back and forth along the X-axis and up and down along the R-axis. Combined with laterally adjustable gauge fingers, it accommodates workpieces of different lengths and bend heights. High-end multi-axis models also support adjustments in more dimensions, handling multi-stage continuous bending of complex workpieces.
V. Tooling System: The "Shaping Mold" of the Workpiece
This is the part that contacts the sheet directly, determining the final bend angle, shape, and surface quality. It is divided into the upper die and lower die, which work together as a pair.
• Upper die (punch): Mounted on the ram. Common types include the standard acute punch, gooseneck punch, radius punch, and flattening punch. Different punch tip angles correspond to different bend angles.
• Lower die (die): Mounted on the worktable, usually a die block with V-shaped grooves. Different groove widths correspond to different sheet thicknesses, and some machines support quick switching between single-V and double-V grooves.
Tooling is a replaceable accessory that can be selected flexibly according to the workpiece material, thickness, and shape. Bending dies wear slowly and have a long service life, but care should be taken to avoid nicks and chipping during use.
VI. CNC Control System: The "Command Center"
This is the control hub of the entire machine, responsible for parameter input, computational control, motion execution, and error compensation. It determines the level of automation and the operating threshold of the machine.
It mainly comprises the operator touchscreen, CNC controller, encoder/linear scale (position feedback element), control buttons, and electrical cabinet components.
A basic NC system can only execute simple digital commands and is suitable for simple bending. A CNC system, by contrast, supports intelligent functions such as code programming, graphic import, automatic springback calculation, and process program storage. Working with feedback elements such as linear scales, it can achieve full closed-loop control for higher machining accuracy and batch-to-batch consistency.
VII. Safety and Auxiliary Components
These are accessory components used to ensure operator safety and improve ease of use.
Safety-related components mainly include light curtains, protective guards, interlocked door protection, and emergency stop buttons. Operating components mainly include the foot switch and two-hand control station, preventing operators from accidental contact and injury.
Auxiliary components mainly include leveling feet, catch trays, follow-up support devices, and work lights, all of which can be selected and configured according to the machining scenario to optimize the production experience.