How is the impact line generated in the processing of stamping parts?

The impact line is caused by the deviation of the contact point between the material and the punch during the molding process, and the resistance of the stamping material is different when the material is formed. The bottom sheet moves through the top of the punch, and the static friction of the surface motion is transformed into a trace formed by the impact caused by dynamic friction. ; The main reasons for the stamping line are: 1. There is poor resistance in the sheet forming process; 2. The bottom surface of the part deforms greatly. According to the law of stamping deformation tendency, the stamping part is drawn and deformed along the periphery of the blank in the deformation zone. The distribution of the blank is uneven. The area at the straight edge of the blank is smaller than the area at the round corner of the blank, so the compression deformation at the straight edge requires less deformation than the round corner; because the force on the blank is the same, a smaller deformation force is required The straight edge deforms first; at the beginning of forming, the uppermost part of the upper mold surface of the punch first contacts the sheet metal to produce plastic deformation. Because the curvature of the bottom surface changes drastically and the area contacting the punch is small, it becomes thinner under the action of large tensile stress. Bulging, the sheet material at the straight edge of the flange produces tangential compression and radial elongation under the combined action of radial tensile stress and tangential compressive stress, and is gradually pulled into the concave mold, the convex mold continues to move upward, and the sheet material hangs in the air The part gradually fits the convex mold to form a curved surface. Because the curvature and length of the two cylinders are different, the resistance on the two cylinders is also different during forming. The deep side has large curvature, large drawing deformation and relatively forming resistance. The forming speed is relatively slow. At the same time, when the punch begins to stretch, the contact with the drawn blank is on the deep side. The blank must move from the shallow side to the deeper side through the top of the punch, causing the top of the punch and the drawing blank to move from the shallow side to the deeper side. Excessive friction of the deep blank, the sheet metal in the contact position changes from static friction to sliding friction. The inner surface of the contact with the stamping mold produces an impact to form a slippage trace. Due to the imbalance of the punch contacting the sheet material, the bottom plate is caused During the process of material flow, there is a mode change, that is, the impact line generated in the process of transforming from initial bulging to deep drawing; article recommendation: What are the technical and economic advantages of stamping parts processing? Previous post: What are the technical and economic advantages of stamping parts processing?