In stamping processing, blanking is a fundamental and important process, widely used in the shaping and cutting of metal parts. Blanking refers to the process of separating sheet materials into the required shape and size through the interaction between the punch and die of the mold. Blanking force is the force required to perform blanking operations, and its calculation is of great significance for mold design, equipment selection, and the safety of the production process.



One, Definition of shearing force



Shearing force refers to the minimum pressure required to produce plastic deformation and ultimately fracture in the metal sheet during the shearing process. It is an important basis for selecting the tonnage of stamping equipment and the foundation for the design of mold strength and rigidity.



Two, Main factors affecting shearing force



1. Material mechanical properties: The higher the shear strength of the material, the greater the required shearing force.

2. Material thickness: The thicker the plate material, the greater the shearing force.

3. Workpiece contour perimeter: The larger the shearing area, that is, the longer the circumference of the sheared edge, the greater the shearing force.

4. Molding clearance: Reasonable clearance can reduce shearing force, while excessive or insufficient clearance will increase shearing force.

5. Blade condition: Worn blades will significantly increase the shearing force.



Three, Shearing force calculation formula



Shearing force is usually estimated according to the following empirical formula:



F = K × L × t × τ



Among them:



- F: Shearing force (unit: N)

- K: Safety factor, generally taken as 1.3, used to consider factors such as blade wear and uneven mold clearance

- L: Perimeter length of the shearing part (unit: mm)

- t: Material thickness (unit: mm)

- τ: Material shear strength (unit: MPa)



For example, if the circumference of a shearing part is 200 mm, the material is Q235 steel (shear strength is about 300 MPa), and the material thickness is 2 mm, then the calculation of shearing force is as follows:



F = 1.3 × 200 × 2 × 300 = 156,000 N = 156 kN



That is, the required shearing force is about 156 kN.



Seven, Precautions



6. Consider compound shearing: When multiple shearing actions are carried out simultaneously, the shearing forces of each part should be superimposed to determine the total pressure.

5. Shearing force curve: During the actual shearing process, the shearing force does not reach the maximum value instantaneously, but changes with the stroke. Therefore, the equipment should be able to withstand the maximum instantaneous pressure.

4. Equipment selection: When selecting a press, a certain margin should be left according to the calculated shearing force, usually 1.2 to 1.5 times the calculated value.



Five, Conclusion



Accurate calculation of shearing force is a key step to ensure the quality and efficiency of shearing. By reasonably selecting parameters and calculation methods, not only can the mold life be improved, but also the safe operation of production equipment can be ensured. In actual production, adjustments and optimizations should be made in combination with specific process conditions to achieve efficient and stable shearing processing.



In summary, the correct calculation of shearing force is the foundation of stamping process design. Mastering its principles and methods is of great significance for improving product quality and reducing production costs.