What are the reasons for analyzing the stripping of the trimming die for automobile stamping parts?

The trimming sequence die for stamping parts is generally prone to the phenomenon of upper die clamping during the debugging stage. The main reasons are:

• 1. The pressing core cannot perform the pressing and returning: the pressure on the pressing core is uneven, there is a gap in the guide, and the material will not be returned if it is stuck;
• 2. After trimming, the core pressing force is not enough;
• 3. After trimming, the parts are deformed and stuck in the pressure core.

The improvement and preventive measures of trimming clips are as follows:

1. Solve the problem

• 1) For the situation that the pressure core is stuck and cannot be returned normally due to the uneven force and improper orientation of the pressure core, the gap between the guide plate and the guide sliding surface can be adjusted.
• 2) The arrangement of springs and the specifications of the replacement springs ensure that the force is uniform.
• 3) Press core guide: guide the press core, mainly to ensure the gap between the press core and the die edge, the general value is 0.5mm.
• 4) Pressing core stroke: The pressing core stroke requires that the pressing core pre-compresses the workpiece before cutting the cutting edge; shearing before pressing the workpiece will easily cause deformation, trimming and tearing of the workpiece, and jamming. Before the die comes into contact with the stamping part, the pre-compression stroke of the pressure core is greater than or equal to 10mm.

2. Solve the problem

• 1) The return force varies with the thickness and shape of the plate, generally 4-20% of the punching force.
• 2) At the same time, when there is vertical cutting in the trimming die, it is necessary to increase the return force.
• 3) The force source is preferably a spring, and the force source is arranged close to the working part; for those with little requirement for the return force, the automobile stamping parts can use polyurethane to provide the return force.
• 4) Calculation of force. Spring pressure F=kL, k is related to spring cross-sectional shape, inner and outer diameter size and spring steel material performance, L is the amount of deformation; the pressure of nitrogen gas spring changes almost linearly, which has the advantages of no preloading, large initial pressure, small space occupation and long life. And the response frequency can reach more than 40 times per minute.

3. For the problem

• 1) If the mold is not in place, the parts are deformed, and the molds can be researched and combined to solve the problem of deformation of the parts and the phenomenon of jamming.
• 2) Add ejector pins in the pressure core to set the parts out of the pressure core.