The Reason of Wrinkling
1.The Reason of Wrinkling
Stamping is a forming method that uses presses and dies to apply external force to plates, strips, pipes, and profiles to make them plastically deform or separate to obtain workpieces (pressed parts) of the desired shape and size. Stamping and forging are both plastic processing (or pressure processing), collectively called forging. The stamped blanks are mainly hot-rolled and cold-rolled steel plates and strips. 60-70% of the world's steel products are plates, and most of them are stamped to make finished products.
Car body, chassis, fuel tank, radiator sheet, boiler drum, container shell, iron core silicon steel sheet of motor and electrical appliances are all processed by stamping. There are also a large number of stamping parts in instruments, household appliances, bicycles, office machinery, household utensils and other products.
Stamping is the production technology of product parts with certain shape, size and performance by means of the power of conventional or special stamping equipment, so that the sheet material is directly deformed and deformed in the mold. Sheet metal, mold and equipment are the three elements of stamping processing.
In the production process of steel products, when the blank is stamped, the surface is wrinkled and the surface is uneven, which is a relatively common stamping defect. This not only causes the waste of raw materials, but also sometimes increases the subsequent scrap. For example, wrinkling of automobile stamping parts will directly lead to poor solder joint quality or even solder joint cracking in the subsequent welding process. So, how does wrinkling occur?
When the sheet is deformed by stamping, it is subjected to tensile stress in the plane tensile direction and compressive stress in the thickness direction. When the compressive stress in the thickness direction is much greater than the stability limit of the material, the sheet will wrinkle. Under certain pressure, the thinner the sheet, the easier it is to wrinkle. At the same time, during the machining process, the largest tangential compressive stress occurs at the edge of the flange, that is, the wrinkling of the outer edge is most obvious.
2.Causes of wrinkling and corresponding solutions
Product wrinkle mainly finds the reason from three aspects:
1.Design of parts
Does the product model reasonably take into account the molding problem, is the clamping bar set too small? Do you need to add wrinkles to the wrinkled areas?
Solution: Increase the pressure rib or change the layout of the pressure rib. The waste part increases the wrinkles.
2. Process design
a) Loose and tight inside the pressing surface
Solution: Grind the pressing surface.
b) The shape of the pressing surface is unreasonable
Solution: Modify the shape of the press-feeding surface to avoid uneven flow of the material due to its immobile shape.
c) The reason for the billet. The billet is too small or not properly positioned in the mold
Solution: increase the size of the billet. Improve the positioning of the billet on the mold, so that the mold can accurately press the material.
d) The pressing force is too small
Solution: Increase the jack pressure.
e) The gap between the upper and lower dies is too large
Solution: adjust the gap.
f) The radius of the corner of the die is too large, so that the punch cannot press the material
Solution: Reduce the radius of the fillet.
g) Too much lubricating oil
Solution: Carry out the oiling work according to the requirements of the operation regulations to ensure the correct position and amount of oiling
3. Materials
The yield strength of the material is not up to standard, and the material is too soft.
Solution: In the case of ensuring product performance, use materials with better formability.
