Primapress is a professional manufacturer of CNC sheet metal CNC press brake bending machine, CNC shearing machines, and CNC rolling machines
CNC sheet metal CNC press brake bending machine is an important equipment in sheet metal processing, and its working accuracy directly affects the bending accuracy of the workpiece.
During the workpiece bending process of the bending machine, due to the maximum force on both ends of the slider, the reaction force during sheet bending causes concave deformation on the lower surface of the slider. The middle part of the slider has the largest deformation, and the angle of the workpiece ultimately bent varies throughout the entire length direction.
CNC bending machine CNC sheet metal CNC press brake
In order to eliminate the adverse effects of slider deformation, it is necessary to compensate for the deflection deformation of the slider. The usual compensation methods include hydraulic compensation and mechanical compensation, which generate upward elastic deformation in the middle of the workbench to offset the deformation of the machine tool slider, ensure the accuracy of the machining joint surface, and improve the accuracy of the workpiece. Primapress brand CNC bending machine adopts mechanical compensation method.
1. Hydraulic compensation method
The hydraulic automatic deflection compensation mechanism of the workbench is composed of a set of oil cylinders installed in the lower workbench. The position and size of each compensation cylinder are designed based on the deflection compensation curve of the slider and the finite element analysis of the workbench. Hydraulic compensation is achieved through the relative displacement between the front, middle, and rear three vertical plates to achieve the neutral version of protrusion compensation. Its principle is to achieve protrusion through the elastic deformation of the steel plate itself, So its compensation amount can be adjusted within the elastic range of the workbench.
2. Mechanical compensation method
Mechanical compensation is composed of a set of convex wedges with inclined surfaces, each of which is designed based on the deflection curve of the slider and workbench finite element analysis. The CNC system calculates the required compensation amount based on the magnitude of the load force during the bending of the workpiece (which will cause deflection deformation of the slider and the worktable vertical plate), automatically controls the relative movement of the convex wedge block, thereby effectively compensating for the deflection deformation caused by the slider and the worktable vertical plate. The ideal mechanical deflection compensation of the bent workpiece is achieved by controlling the position to achieve “pre protrusion”, A set of wedges forms a curve in the length direction of the workbench that matches the actual deflection, ensuring that the gap between the upper and lower molds is consistent during bending, ensuring that the angle of the bent workpiece in the length direction is consistent.
3. Comparison of Two Compensation Methods
Advantages of hydraulic compensation:
With the passage of time, there is no problem of wear and tear in hydraulic compensation, while wear and tear will occur in mechanical compensation screws, wedges, and other components over time.
Hydraulic compensation takes up less space, while mechanical compensation takes up more free space in both height and width directions.
When using hydraulic compensation, it is impossible for the plate to shift, as the lower workbench is in contact with the surface of the bent plate in an overall plane state. When the upper horizontal plane contacts the “clamping point” of the plate, the positioning of the stop finger is very stable. Mechanical compensation only takes effect after bending, and there is a probability of unpredictable errors.
Hydraulic compensation can also be adjusted when the workpiece is not removed, which is impossible in mechanical compensation.
Advantages of mechanical compensation:
Mechanical compensation has long-lasting stability and reduces the difficulty and frequency of hydraulic compensation maintenance, such as oil leakage caused by seal ring damage
Hydraulic crowning for cnc press brake machine
Mechnical crowning for cnc press brake.