Precautions for Sheet Metal Z-bending and N-bending

Table of Contents

Definition: zigzag bending is called Z bending.

Standard bending process range: height of Z bending > apothem of V groove + Thickness

The minimum processing size is limited by the model used while the maximum processing size is determined by the shape of the machine table.

Z Processing Procedures

Processing to form a L bending
Bend the horizontal side of the L bending to form a Z bending (or bend the vertical side of the L bending to form a Z bending)

A: Convenient, good stability.

B: Generally is similar to L-bending.

C: The workpiece is flat with the lower die during the 2^nd placement.

The angle of L bending should be as accurate as possible, normally ranging from 89.5 °to 90 °.
The back gauge should be set up to prevent deformation of the workpiece.

The processing sequence should be considered as shown in the following picture, first bend 1 and then bend 2.

First bend to form an L bending and then further processed to form a Z bending (if interfere with machine worktable, first bend 1 to form a large angle, then bend 2 and then press 1)
Using two acute angles to form Z bending: first bend into a right-angle, then insert 2 and then insert 1

1) If there is a collision, first bend 1 to form a large angle, then bend 2 and then press 1.

2) if no collision, as per general Z bending processing method, first bend 1 and then bend 2.

A: lower die decenter processing

B: small V groove processing

C: bending to form a large angle, then pressing

D: choose grindable lower die

A: process with offset die

B: process with the transformable die

Definition: continuously process the same machining surface twice to form N bending

if interfere with the top punch a little after Y sizes N-bending ==> flattening with hemming die after N-bending.
if interfere with top punch very serious after Y sizes N bending ==> bend to collision position after A bend press line, positioning C and bending B point, then use hemming die + padding to form into shape.