Key points of trimming and punching design for automotive parts:
1. Force calculation
1. Punching force P=Lt Ltσ (N)
L: Punching profile length (mm) (mm)
t: Plate thickness (mm) (mm)
σ: Tensile strength (σ=350N/mm2)
Pressing force P1=0.05P(N) P1=0.05P(N)
2. Principles for selecting force source
The force source applies pressure to the pressing core to press the plate. There are generally three types of force sources: ① Coil spring ② Polyurethane ③ Nitrogen spring (expensive)
According to the actual situation of our company, we generally choose coil springs.
We prefer medium-load springs, model SWM 50--X (MISUMI standard)
Where "50" is the outer diameter of the spring, and "X" is the length of the selected spring
3. Calculation of the number of springs
When the upper die trimming knife is about to contact the plate, it is necessary to ensure that there is sufficient pressing force on the plate.
P1=nkx
P1: Pressing force
n: Number of springs
k: Spring constant (N/mm)
x: Stroke of the pressing core ST--The amount of upper die knife block (generally: ST--66)
4. Force source distribution principle
The force source distribution should be balanced and as close to the working part as possible
