Punch punch, blanking tonnage calculation formula: P=ltτ=0.8ltRm, where P is punching force, unit N, l is the stamping length of the parts, unit mm, t is the thickness of the parts, unit mm, τ is the shear strength of the stamping material, unit MPa, Rm is the tensile strength of the stamping material, unit MPa. The tensile strength of Q235B steel plate material is about 370-500mpa, and the middle value is calculated at 450MPa, and the stamping tonnage of Φ50 round hole is 0.8×3.14×50×12×450=678240N=678 kN =67.8 tons.