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Selection Skills of Punch Die (Bottom Die) for CNC Hydraulic Punching Machine


During the processing of CNC hydraulic punching machine and CNC angle steel production line, improper clearance selection will result in poor punching hole or increased damage to punch and die.

The selection of a reasonable clearance can ensure the section quality and dimensional accuracy of the hole and improve the service life of the die. However, it is not the same value to determine the reasonable clearance in terms of quality, impact pressure, die life, etc., but close to each other. In view of the deviation in the manufacture of stamping dies and the wear in use, usually only an appropriate range can be selected as a reasonable clearance.

According to Xiaochao’s years of research and practical experience in the use of dies, the parts with high requirements for dimensional accuracy and section perpendicularity should use smaller clearance values, and the stamping parts with low requirements for section perpendicularity and dimensional accuracy should focus on reducing the blanking force and improving the life of the stamping die, and larger clearance values can be used. The value can be calculated according to the following empirical formula:
For soft materials (assuming the material thickness is t and the gap is c):

When t = 1 ~ 4mm, c =(5%~8%)t
t = 4 ~ 5mm, c =(8% ~10%)t
Hard material
t= 1~4mm, c = (6%~8%)t
t = 4 ~ 8mm, c =(8% ~13%)t

It can be seen that for the harder the material, the thicker the material is, and the larger the gap should be selected.

1. Standard determination of aperture
When punching by hydraulic punching machine and angle steel punching production line, the standard of hole diameter is based on the diameter of punch. If 17.8mm is marked on the drawing, the diameter of the punch is selected as 17.8mm, and the clearance of the grinding tool is adjusted through the size change of the female die.

2. Selection of female die
The diameter of the cutting edge of the female die=the diameter of the punch+the unilateral punching clearance x2.

CNC connecting plate punching machine and CNC angle steel punching production line are mainly used in the processing of power tower, communication tower and steel structure. The punching materials are mainly carbon steel such as Q235, Q345, Q420, etc. According to the deformation characteristics of carbon steel materials and the requirements of power tower, communication tower and steel structure processing, the unilateral punching clearance is generally 0.08-0.1 times the material thickness.

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