CNC sheet metal bending machines generally use an all-steel welded structure with sufficient strength and rigidity. Hydraulic transmission, the cylinders at both ends are installed on the slider, which directly drives the sliding work. The slider synchronization mechanism adopts torsion shaft for forced synchronization. It adopts mechanical block structure, which is stable and reliable. The sliding stroke can be quickly adjusted manually, and the counter is displayed. The wedge deflection compensation mechanism ensures high bending accuracy. The three types of structures commonly used in sheet metal bending machines are as follows:
1. Upward movement, that is, the slider drives the punch downward. In order to ensure that the slider will not tilt relative to the work due to the unbalanced load on the slider and the difference in the resistance of the left and right oil cylinder pipelines, thus affecting the forming quality of the workpiece, the slider motion synchronization control system is usually equipped. The lift-up type is easily equipped with a mechanical or hydraulic synchronous control system. The mechanical synchronization device has a simple structure and low cost, and can obtain a certain synchronization accuracy, but the ability to bear eccentric loads is poor, so it is only suitable for small and medium hydraulic sheet metal bending machines. The hydraulic synchronization coefficient includes mechanical hydraulic servo synchronization system, electro-hydraulic servo synchronization system and numerical control synchronization system. This synchronization system has high precision and is suitable for sheet metal bending machines with high bending precision requirements. But the technology is complicated and the cost is high.
2. Downward type, that is, the slider is installed at the lower part of the machine tool, which drives the die to move up. The working oil cylinder is placed in the center of the slider, with a single oil cylinder when the nominal force is small, and three oil cylinders when the nominal force is large. Since the working cylinder is concentrated in the middle of the slider, the deformation of the slider and the beam is consistent, and the gap between the concave and convex dies is uniform over the entire length of the slider, so the bending accuracy of the workpiece is high. The slider returns by its own weight, and the hydraulic system is simple. The advantages of the downward-moving type are light weight, compact structure and easy maintenance; the disadvantage is that the synchronization accuracy is not high; it is difficult to solve the problem of the inclination of the slider with a single-piece cylinder; the depth of the punch entering the die is difficult to accurately control. It is not suitable for punching; and the die on the worktable runs up with the workpiece, which is not easy for operators to operate.
3. The CNC bending machine works according to the working origin of the above three-point bending method. The three-point bending machine has the advantages of high bending precision, wide technological application, and the function of a four-sided forming machine. However, the structure of the machine tool is complex and the cost is high.
