①The thickness is accurate and uniform. The stamping die is precise and has a small gap. If the thickness of the sheet is too large, it will increase the deformation force and form a jam, or even burst the die. If the sheet is too thin, it will affect the quality of the product, and may even show cracks during deep drawing.
②The appearance is smooth, no spots, no scars, no scratches, no appearance cracks, etc. All appearance defects will remain on the surface of the product, and the crack defect may extend to the deep and wide in the process of bending, deep drawing, and forming, forming a waste product.
③ Uniform yield strength without obvious directionality. Anisotropy (see plastic deformation of sheet metal in the drawing, flanging, bulging and other stamping processes, due to the appearance of all-direction obedience, the amount of plastic deformation is inconsistent, which will cause uneven deformation and inaccurate forming. Defective or scrap.
④High uniform elongation. In the tensile test, the elongation before the sample begins to show the phenomenon of narrow neck is called uniform elongation. During deep drawing, the deformation of any area of the sheet material cannot exceed the uniform extension range of the material, otherwise it will show uneven deformation.
⑤The yield ratio is low. The ratio of the yield limit of the data to the strength limit is called the yield ratio. The low yield ratio not only reduces the deformation resistance, but also reduces the tendency to wrinkle during deep drawing, reduces the amount of springback after bending, and improves the accuracy of the bending parts.
⑥ Low work hardenability. The work hardening that appears after cold deformation will add the deformation resistance of the material, making it difficult to continue to deform. Therefore, plates with a low hardening index are generally used. However, materials with a high hardening index have good plastic deformation stability (that is, more uniform plastic deformation) and are not prone to localized cracks.