During the bending process in a press brake, the ends of the ram bear the greatest force. The reactive force generated when bending the sheet metal causes a concave deformation on the underside of the ram, with the central portion experiencing the largest deformation. This results in inconsistent angles along the entire length of the bent workpiece. To counteract the negative effects of this ram deformation, it’s essential to compensate for the deflection in the ram, and mechanical compensation is the most commonly used method.
Mechanical compensation in CNC press brakes is a method that adjusts the mechanical structure to counteract machine deformation caused by reactive forces during metal bending, thereby improving bending precision and workpiece quality.
The mechanical compensation system is made up of a set of inclined compensation wedge blocks. Each wedge is designed based on the deflection curve derived from finite element analysis of the ram and worktable. By applying an opposite force through these wedges, the system offsets the deformation of the ram and worktable caused by bending the sheet metal. Based on the load exerted during bending (which causes deflection in the ram and the worktable stand), the CNC system calculates the necessary compensation and automatically controls the relative movement of the wedge blocks to effectively counter the deflection in the ram and stand. This enables an ideal bending result. Mechanical deflection compensation is achieved by creating a “pre-bulge” in a controlled position, forming a curve along the worktable’s length that matches the actual deflection curve. This ensures consistent spacing between the upper and lower dies during bending and consistent angles along the length of the workpiece.
This compensation method effectively addresses unpredictable errors caused by material variations, machine deflection, and other factors, ensuring that the workpiece maintains a stable angle and straightness throughout the bending process, thus preventing deformation or twisting.
The advantage of a mechanical compensation system is that it uses mechanical structures rather than relying on hydraulic systems, which makes it relatively simple, requires no complex control system, and is more cost-effective. Compared to hydraulic compensation, mechanical compensation is simpler to operate, requires less training, provides precise compensation, and achieves accurate bending with ease.
Mechanical compensation also offers lasting stability, reducing maintenance difficulty and frequency, unlike hydraulic compensation systems (e.g., issues like oil leakage from damaged seals). It is maintenance-free over the machine’s lifespan.
In conclusion, mechanical compensation offers numerous advantages in press brake applications, making it a valuable option to consider.
