1. Burr: Burr may occur when the die blanking clearance is too large, too small or uneven, the concave and convex die edges are not sharp enough, and the blanking state is not good.
2. Parts are warped:
a. In the blanking process, the stretching and bending forces of the parts are large, and the parts are prone to warp. The improved method can use punch and pressing plate to tightly press and keep sharp edge during blanking,
Can receive good results.
b. When the shape of the part is complex, the shear force around the part is uneven, so the force from the periphery to the center is generated, which makes the part appear warping. The solution is to increase the pressing force.
c. When there is oil or air between the die and the parts, or between the parts and the parts, the parts will warp, especially thin materials and soft materials. It can be realized through uniform oiling
Air vents are provided to eliminate warping.
3. Wrinkle:
a. The drawing depth of the stamping part is too deep, which causes the sheet metal to flow too fast in the process of feeding, forming wrinkles.
b. The R angle of the female die is too large during the drawing process of the stamping part, which causes that the punch cannot press the material during the drawing process, resulting in the sheet metal flowing too fast and forming wrinkles.
c. The pressing bar of stamping parts is unreasonable, too small and the position is incorrect, which can not effectively prevent the sheet from flowing too fast and forming wrinkles.
d. The design of die positioning is unreasonable, which leads to the inability to press the material or the small pressing edge during the stretching process of the stamping part, which leads to the inability to press the material during the stretching process, causing wrinkles.
The method to solve the wrinkle is to use reasonable pressing device and reasonable use of drawing rib.
4. Dimensional accuracy error:
a. The dimensional accuracy of the cutting edge in die manufacturing is not up to standard, which causes the size of the workpiece to be out of tolerance.
b. In the stamping production, the springback of the parts causes that the positioning surface of the next process is not completely consistent with the parts, and the deformation occurs in the stamping process, which affects the dimensional accuracy.
c. Poor positioning of parts, unreasonable design, moving parts during stamping. There are also defects in the design of parts, resulting in inaccurate positioning and affecting the dimensional accuracy.
d. Due to improper adjustment of the previous process or wear of fillets, the deformation of multi process parts is mentioned unevenly, resulting in dimensional changes after blanking. For the problems caused by the above points
Therefore, we should take necessary control measures, such as reasonable stamping part shape and tolerance grade, improving die manufacturing accuracy, designing rebound compensation mechanism, etc.
5. Crushing:
a. There are sundries on the material surface. Check whether there are sundries on the material surface during stamping, and clean them with air gun and rag if there are sundries.
b. There are foreign matters on the mold surface. Use tools to clean the foreign matters on the die surface, and select the appropriate lower die clearance according to the plate thickness.
c. The die strip is magnetic. Change the processing sequence, and process from outside to inside and line by line when punching the workpiece. First trim (trim) and then punch the mesh, and there is deformation in special forming and stamping,
It may be that the pressure is too high, and the spring in the mold needs to be replaced.
d. The stamping oil does not meet the requirements. Replace the current stamping oil, and select the special stamping oil containing
vulcanizing extreme pressure additive.
6. Scratch: The main reason for the scratches of parts is that there are sharp scars on the mold or metal dust falls into the mold. The preventive measure is to grind the trace on the mold and remove the metal dust.
7. Bottom crack: the main reason for the crack at the bottom of the part is poor plasticity of the material or too tight pressing of the die blank holder. The preventive measure is to replace the material with good plasticity or loosen the blank holder.
8. Side wall wrinkling: the main reason for the side wall wrinkling of parts is that the material thickness is not enough (if it is relatively small, the thickness can be thinner) or eccentric when the upper and lower molds are installed. Resulting in a large gap on one side,
The clearance on the other side is small. The preventive measure is to immediately replace the material and readjust the mold.
