I. Analysis of the causes of metal stamping parts waste, from five angles: man, machine, material, law, ring.
　　 A. The quality of stamping raw materials is inferior, such as uneven thickness and hardness, and the size of the shearing plate or strip is not accurate;
　　 B. The adjustment and improper use of the stamping die, such as the limit post is not attached, the mold is not completely closed during stamping production.
　　 C. The stamping operator does not feed the stamping strips correctly along the positioning or does not guarantee that the strips are fed at a certain gap;
　　 D. Due to long-term use of the stamping die, gap changes or wear of the working parts and guiding parts themselves;
　　 E. The stamping die is relatively loose due to the impact vibration time, and the fastening parts are loosened to make relative changes in the mounting positions of the die;
　　 F. The negligence of the stamping operator did not operate according to the operating procedures.
　　 G. The quality management system is not perfect, or the quality inspectors do not conduct inspections on time, and the sampling inspections find bad anomalies in time.
　　 F. The punching machine has insufficient precision for disrepair, and the parallelism of the upper and lower plates decreases or the pressing pressure decreases.
　　 2. The main measures for stamping processing plants to prevent metal stamping waste
　　 A. The stamping raw materials must conform to the specified technical conditions (strictly check the specifications and grades of the raw materials, and test the workpieces with high dimensional accuracy and surface quality requirements under certain conditions.)
　　 B. All aspects specified in the stamping process specification shall be fully and strictly observed;
　　 C. The working equipment such as presses and stamping dies should be used to ensure normal working conditions;
　　 D. Establish a strict inspection system during the production process. The first part of the stamping parts must be inspected thoroughly. Only after the inspection is passed can the production be put into production, and the inspections should be strengthened. When accidents occur, they should be promptly placed.
　　 E. Adhere to the civilized production system, such as the transfer of stamping workpieces and blanks, must use the appropriate station equipment, otherwise it will crush and scratch the surface of the workpiece to affect the surface quality of the stamping parts;
　　 F. In the stamping process, it is necessary to ensure the cleanness of the mold cavity, and the workpieces to be arranged in the work place should be placed neatly.
　　 3. Causes of burrs of punching parts
　　 A. The die blanking gap is too large, too small or uneven;
　　 B. The cutting edge of the working part of the stamping die becomes dull;
　　 C. The convex and concave molds change the center line due to long-term vibration shock, and the axes do not coincide, resulting in single-sided burrs.
　　 Stamping factory measures
　　 A. Ensure the machining accuracy and assembly quality of the convex and concave molds, ensure the verticality and the bearing side pressure of the punch and the entire stamping die to have sufficient rigidity;
　　 B. When installing the punch, the correct clearance of the male and female molds must be ensured and the male and female molds should be firmly fixed on the mold fixing plate. The end faces of the upper and lower molds should be parallel to the work surface of the press.
　　 C. The rigidity of the press is required to be good, the elastic deformation is small, the accuracy of the track and the parallelism of the pad and the slider are required to be high;
　　 D. Require the press to have sufficient punching force.
　　 Punching section shearing section allows height of burr
　　 Blanking plate thickness >0.3 >0.3-0.5 >0.5-1.0 >1.0-1.5 >1.5-2.0
　　 New test burr height ≤0.015 ≤0.02 ≤0.03 ≤0.04 ≤0.05
　　 The allowable burr height during production ≤0.05 ≤0.08 ≤0.10 ≤0.13 ≤0.15
　　 4. Causes of warping deformation of the blanking parts
　　 There are gap forces and reaction forces that do not generate torque on a line. (When the clearance between the convex and concave molds is too large and the edge of the concave mold has a reverse taper, or the contact area between the ejector and the workpiece is too small, warpage is generated)
　　 Measures:
　　 A. The clearance should be chosen reasonably;
　　 B. The stamping plate (or pallet plate) should be added to the die structure to be in plane contact with the pressure plate and have a certain pressure;
　　 C. Check the die edge If the reverse taper is found, the die edge must be trimmed properly.
　　 D. If the shape of the blanking part is complicated and the shearing force is uneven, the pressing force is increased, the stripping force is pressed before punching, or the high-precision guide pillar is used, or the high-precision pressure is adopted. Machine punching.
　　 E. The plate should be leveled before punching. If the warpage is still not eliminated, the punched workpiece can be leveled again through the leveling die.
　　 F. Regularly remove the dirt in the mold cavity, lubricate the surface of the thin sheet material, and provide oil and gas holes in the mold structure.
　　 5. When punching, the outer edge of the blanking part and the accuracy of the inner hole are reduced in size.
　　 the reason:
　　 A. The position of the positioning pin, the stopper pin, etc. change or wear too much;
　　 B. The operator's negligence is about to shift left and right when feeding.
　　 C. The dimensional accuracy of the strip is lower than the narrow and wide. The feeding difficulty makes it difficult to send to the designated place. The strip will be offset back and forth in the guide plate, and the inner hole of the workpiece that is punched out will have a large deviation from the front and rear positions of the shape.
　　 6. Reasons for unqualified size and shape when stamping parts are bent
　　 A. The rebound of the material causes the product to fail.
　　 Measures to reduce rebound:
　　 ◆. Selecting a stamping material with a stable mechanical modulus and a small yield point and a relatively stable mechanical property;
　　 ◆. Add correction process, using correction bending instead of free bending;
　　 ◆ Before annealing, the material should be annealed, so that the cold work hardening material is softened before being bent and formed;
　　 ◆ If the shape deformation occurs during the stamping process and it is difficult to eliminate; the slope of the punch and the die should be replaced or trimmed, and the gap between the die and the die should be equal to the minimum thickness.
　　 ◆. Increase the contact area between the die and the workpiece, and reduce the contact area between the punch and the workpiece.
　　 ◆. Use the "overkill" method to reduce the impact of rebound.
　　 B. The positioner is subject to wear and deformation, and the strip is not positioned properly. A new positioner must be replaced.
　　 C. In the unguided bending die, when the press is adjusted, the bottom dead center position of the press slide is improperly adjusted, and the shape and size of the bent piece are also unqualified.
　　 D. The die press device of the mold fails or does not work at all. It is necessary to re-adjust the press force or replace the pressure spring to make it work properly.
　　 7. Cracks occur in the bent part of the bent part (the internal stress in the bending deformation area exceeds the strength limit of the material)
　　 A. Eliminate the burrs on the outside of the bending zone, and the burrs will cause stress concentration in the area.
　　 ◆ Reduce the amount of bending deformation
　　 ◆ Clear the burrs in this area
　　 ◆ The burr side is placed on the inside of the bending zone.
　　 B. When bending the workpiece, it is preferable to make the bending direction perpendicular to the fiber direction (rolling direction) of the material.
　　 C. The bending radius should not be too small, and the radius of the fillet should be increased as much as possible.
　　 D. The surface of the curved blank should be smooth and free of obvious protrusions and scars.
　　 E. An intermediate annealing process is used during bending to eliminate internal stress, and cracks are rarely generated after softening.
　　 F. When bending, it is necessary to apply lubricant to large metal stamping and bending parts to reduce the friction during bending.