On the pre-processed metal punching hole or part of the hole (sometimes it is not necessary to pre-process the hole), we rely on the stretching deformation of the material to turn it into a vertical edge along a certain curve, which is called "flanging". Metal punching is divided into round hole flanging and outer edge flanging. Because it is formed by stretching the material, its forming is mainly limited by the elongation of the material. Flanging is mainly used for riveting, via hole, tapping and other functions.

The die, calculation formula and related technological requirements of metal stamping round hole flanging are as follows:

Formula: d = 0.5 ~ 0.6t; The value of d is inversely proportional to h, and when the value of d is small, the value of h is large.

D=D1+（D-D1）=D1+1.3T； In order to ensure the verticality of flanging D, in general, D ≤ D1+1.3t..

H=+0.43R+0，72T； The flanging height h (depending on the volume of flanging metal) is usually 1.7T~1.9T.

L=+2.5T； M is the thread specification.

Where d is the diameter of pre-punched hole.

D1-Inner diameter of flanging hole/punch

D2-Flanging vertical edge diameter (calculated according to the central layer) D-Flanging hole outer diameter H-Flanging hole height

R-inner radius of flanging/outer radius of female die

L-center distance margin of flanging hole

T-material thickness

The flanging data of small threaded holes are as follows:

Hardware stamping process requirements:

The height of flanging hole for metal stamping is h ≥ 3p; P is the thread pitch. The tolerance of hole spacing in the same plane of flanging is ≥ 0.15.

It is not recommended to use stainless steel with T=1.5mm for M3 flanging and stainless steel with T=2.0 for M4 flanging.

When aluminum plate is turned over and tapped, the force that thread can bear should be considered.

There are two types of outer edge flanging: outer convex contour flanging and inner concave contour flanging; The flanging of convex contour is also called compression flanging, and the flanging of concave contour is also called extension flanging.

Description: r-radius of fillet after flanging;

B- the difference between the radius before flanging and the radius after flanging;

Radius of fillet of R+b and R-b parts before flanging (blank)