Thirteen points principles of sheet metal bending parts
- Minimum bending radius of plate
When sheet metal bending , if the rounded corner of the bend is too small, the outer surface is prone to cracks. If the bend fillet is too large, the accuracy of the bent part is not easy to guarantee due to the effect of springback. For this purpose, a minimum bending radius is specified. See table 4.1-3.
2. The height of the curved straight edge should not be too small, otherwise it will not be easy to form a sufficient bending moment, and it will be difficult to obtain a part with an accurate shape. Its value is h≥R+2t. See figure 4.1-5.
3. When punching holes with bending edges, the distance L from the edge of the hole to the center of the bending radius R must not be too small to avoid deformation of the hole after bending. Its value is L≥2t. See figure 4.1-6.
4. When a<R, after bending, there is still a residual arc on the b surface near a. In order to avoid the residual arc, a≥R must be made.
5. On U-shaped bending parts, the two bending sides are best to be of equal length to avoid shifting to one side when bending. If not allowed, a process positioning hole can be set. As shown in Figure 4.1-8.
6. Prevent cracks or deformities when bending the side surface (trapezoid) . Should design to reserve grooves, or change the root to a stepped shape. Slot width K≥2t, slot depth L≥t+R+K/2.
7. To prevent the rounded corners from wrinkling after being compress during bending, a reserved cut should design. Such as the form of incisions at the rounded corners of the side panels (upper and lower ends) of the outdoor unit.
8. After preventing the bending, the planes on both sides of the right angle will produce wrinkles, and the cut should be designed.
9. After preventing bending, the cut form of springback is produced.
10. Prevents the notch form of cracking after punching.
11. Prevent one side from shrinking inward when bending. The process positioning hole can be designed, or both sides can be bent at the same time, and the shrinkage problem can be solved by increasing the width.
12. Lap joints bent at right angles.
13. Bending of convex part
If the bending line and the step line are the same as in the picture a, the root may crack and deform. So let the bending line leave the step line as shown in figure b, or design the cut like c and d.
14. When preventing bending, the holes on the curved surface will deform after being stressed, and the value of the hole edge distance (to the bottom root) is A≥4.
