When the hole distance near the bending line is smaller than the minimum distance mentioned above, deformation will occur after bending. In such cases, the following methods can be used based on different product requirements. However, it can be seen that these methods have poor processability, and structural design should be avoided as much as possible.
1. Cut holes or slots along the bending line: Cut holes or lines along the bending line. When the bending line has no impact on the appearance of the workpiece or is acceptable, cutting holes can improve its processability.
Drawback: Affects the appearance and generally requires cutting with a laser machine due to the need for cutting lines or narrow slots.
2. Add material first and then remove it: After bending near the hole edge, process to the design size. When it is required to ensure the hole edge distance, this method can be used. Generally, this secondary material removal cannot be completed on a punch press and can only be done with secondary cutting on a laser cutting machine, which is troublesome to position and has high processing costs.
3. Grooving: Pre-bending grooving treatment. In practical design, due to the needs of structural design, situations arise where the actual distance is even smaller than the aforementioned distance. Manufacturers often use pre-bending grooving treatment, as shown in the figure below. The drawback is that it adds an extra process step, slightly lowers efficiency, and reduces accuracy. In principle, it should be avoided as much as possible.
4. Customized molds: The minimum width of the upper die on the bending machine is 4.0mm (currently). Due to this limitation, the hole opening of the internal bending processed part of the workpiece must not be less than 4.0mm. Otherwise, the hole opening must be enlarged or consider using easy-mold forming.
Drawbacks: Low efficiency in making easy molds, low efficiency in easy mold production; enlarging holes affects appearance.
5. Enlarging holes after bending: When only one or a few pixel holes are closer to the bending line than the minimum hole distance, and strict product appearance requirements are needed to avoid material pulling during bending, pixel holes can be reduced before bending by cutting out a small concentric circle (generally 1.0). Drawback: Many engineering steps, low efficiency.
