How to Improve Machine Accuracy of CNC Bending Machine

HARSLE precision machinery added 400 tons 6 meters full CNC bending machine, its tonnage is large, can be folded 20 thick steel plate; Table size 6200, folding 6 meters long steel plate, stainless steel plate, titanium plate, aluminum plate, copper plate and other plates; Full numerical control: precise bending size, small error, high efficiency.

For the improvement of machining precision of CNC bending machine, I would like to say:

1.Control the depth of punch into the die: the depth of punch into the die is the most important factor affecting the bending accuracy. In the realization of the control measures for the depth of punch into the die, there are mainly the following:

● Use mechanical block. The function of the mechanical block is to prevent the piston or slider of the hydraulic cylinder from continuing to move downward so that the depth of the punch into the die reaches the set value. The structure of mechanical blocks is varied, most of which are installed in or above the hydraulic cylinder, or on the rack at both ends of the slider.

The most common structure is that the motor is decelerated through the worm transmission pair and the screw is rotated to adjust the axial position of the stop nut in the hydraulic cylinder. The mechanical block structure is reliable, but the machining is difficult.

● use hydraulic block: the repeated positioning accuracy of the hydraulic block is generally 0. 05 mm, which can be adjusted in the bending process, especially in the trial folding can be continuously adjusted until the required bending Angle, to bring convenience to the operation.

● the use of three-point bending: another important advantage of this bending process is that the three points of the sheet material contact are on the same side of the sheet material during bending, so the deviation of the sheet material thickness basically has no effect on the bending Angle. Furthermore, as the top of the punch and the bottom of the die are in contact with the plate material, the stress state of the bending area of the plate material is changed, and the outside of the neutral layer is changed from tensile stress to compressive stress, so the rebound amount is greatly reduced.

Crack may occur on the outer surface of the sheet material with poor tensile ductility when it is bent freely. Generally, the shell can only be coated by increasing the radius of the rounded corner, and the three-point bending is not easy to crack.

2.Compensation for deflection deformation of slider and worktable: when bending, the middle part of the slider of bending machine produces upward elastic deformation, while the middle part of the worktable produces downward elastic deformation, resulting in the depth of punch into the die is not consistent in the full length, is an important factor affecting the bending precision. So in recent years, more and more bending machines adopt the deflection compensation measures of slider and worktable.

3. Mold fine-tuning: when the slider and the workbench produce deflection in opposite direction, it is difficult to completely eliminate even if compensation measures are taken, resulting in uneven wear of the mold in the process of use. 

The measure of mould fine adjustment can further compensate the deflection of slider and worktable, overcome the influence of mould wear and effectively improve the bending precision.

4. There is a certain thickness deviation in the automatic thickness measurement of the four plates. When the punch enters the die depth, the die opening width and other parameters are determined, the change of plate thickness will cause the change of bending Angle. Therefore, the precision of bending Angle can be improved by realizing automatic measurement of sheet metal thickness.

5. Bending Angle automatic measurement and rebound compensation: even if the same brand plate, the mechanical properties of some differences. Therefore, even when the same die and the same punch are used to enter the deep processing of the die, the bending Angle will be changed due to the difference in the mechanical properties of the plate.

While the bending Angle is affected, the difference of mechanical properties also affects the springback rate. Therefore, the automatic measurement of bending Angle and the automatic measurement and compensation of springback are also important measures to improve the precision of bending Angle.