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)
Workpiece Placement Principles for Z-bending
A: Convenient, good stability.
B: Generally is similar to L-bending.
C: The workpiece is flat with the lower die during the 2nd placement.
Matters Need Attention for Z-bending
- 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.
General Processing Methods of Z bending
- 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.
Special Processing Method of Z bending
A: lower die decenter processing
B: small V groove processing
C: bending to form a large angle, then pressing
D: choose grindable lower die
Other Z Bending Methods
A: process with offset die
B: process with the transformable die
N Bending Processing
Definition: continuously process the same machining surface twice to form N bending
Precautions for N-bending Processing
- the angle of the first bending should be less than or equal to 90°
- the back gauge of second bending should be based on the machining surface
Special Processing Method of 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.
- Processing with shaping punch and die.
Arc processing is divided into two kinds: circular cutting with bending model and circular cutting with arc knife.
The arc knife is divided into two types: fixed and rod.
A: when machining with 90°low die, there may be inadequate machining, so it is necessary to push the mold with hand or if possible, using 88°low die.
B: detect with detecting appliance to ensure the appearance size of the workpiece.
C: when processing 90°arc, the low die should choose 2 (R+T)