1. Hole flanging
There are many types of hole flanging. This criterion only focuses on the inner hole flanging of the thread to be processed, as shown in the figure.
2. Through holes and countersunk seats for screws and bolts
The structural dimensions of screw, bolt through hole and countersunk seat are selected in the following table. For the countersunk seat of countersunk screw, if the plate is too thin to ensure through hole D2 and countersunk hole d at the same time, priority should be given to ensuring through hole D2.
Through holes for screws and bolts:
Countersunk head seat and through hole for countersunk head screw：
Countersunk seat and through hole for countersunk rivet：
