Steps for selecting blanking gap of deep throat punch

No matter what shape of the sheet metal stamping parts, it must go through the punching process (step) to complete the stamping. The manufacturer of deep-throat punching presses said that punching is a general term for punching and blanking. Even if it is directly from the raw materials (including plates, strips, strips, coils), using a multi-station continuous compound mold to form and punch various complex shapes of three-dimensional stamping and forming parts, it must have a blanking station .

In order to achieve the required size and shape accuracy of the punching parts, the quality of the punching surface, and the life of the die during the stamping process, the material grade, supply status (soft, hard, and semi-hard state), thickness of the material and the shear strength of the material must be based on the stamping material. eτ is used to select a reasonable blanking gap.

Choose a reasonable blanking gap in two steps, the so-called two-step method:

Step 1 Determine the choice of gap category

According to the technical requirements of the blanking parts: the quality of the blanking surface, the dimensional accuracy and the life of the die, select the clearance category to be used from the “Blanking Clearance Classification Table” listed in GB/T16743.

Step 2 Select the gap ratio and calculate the gap value

According to the selected gap category, find the gap ratio of the corresponding gap category in the “Blanking gap ratio table” given by the national standard, and obtain a reasonable gap value after calculation. For metal materials not listed in the blanking gap ratio table of the national standard, a reasonable gap ratio can be selected by referring to materials with similar shear strength eτ in the table.

Since the various gap ratios given in the gap ratio table are within a range of relatively large numerical fluctuations, some of the lower limit ratio and the upper limit ratio are more than doubled. This situation is more obvious in the Type I gap of the blanking ratio table. For example, the gap ratio of the low carbon steel type I is (3.0~7.0)%t, the medium carbon steel is (3.5~8.0)%t, and the electrical silicon steel reaches (2.5~5.0)%t. The national standard stipulates that the thickness of the punching material is t> After 1.0mm, as the value of t increases, the material thickness area divided by the gap ratio table shall increase (0.5~1.0)%t step by step (non-ferrous metals and low carbon steel take a small value, medium and high carbon steel take a small value) Great value).

Therefore, when the material grade, material thickness t and eτ of the stamping parts are known, and the gap type to be used is selected according to the technical requirements and dimensional accuracy of the stamping parts, the gap ratio can be checked from the gap ratio table.

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