Stainless steel products are favored by people for their beautiful appearance, excellent corrosion resistance, high temperature oxidation resistance and high and low temperature strength, and are more and more widely used in decoration, light industry, civil hardware, kitchen equipment and utensils and other industries. . Due to the high appearance quality requirements of this type of product, it is indeed very difficult to ensure that the surface of the high-brightness product is not scratched and scratched during the entire processing process of the product, especially due to the tensile properties of the stainless steel sheet. , heat treatment, processing and process lubrication problems directly affect product quality, output, cost and mold life.
Tensile characteristics and adhesion of stainless steel sheet: due to the high yield point, high hardness and significant cold work hardening effect of stainless steel, the characteristics of stainless steel sheet are as follows: 1) Due to the poor thermal conductivity than ordinary low carbon steel, The required deformation force is large; 2) When the stainless steel sheet is stretched, the plastic deformation is severely hardened, and the sheet is easy to wrinkle when stretched, and a large blank holder force is required; 3) The bending of the sheet at the rounded corners of the stretching die The springback caused by reverse bending and reverse bending usually forms concave deformation on the side wall of the product, so that products with high dimensional accuracy and shape requirements need to increase the shaping process to achieve. 4) The phenomenon of sticking nodules is easy to appear during the stretching process of the stainless steel sheet.
From a microscopic point of view, the surface of the sheet metal and the mold are rough and rough key surfaces. Due to the large blank holder force during the stretching process, the load is subjected to a large unit pressure by the local convex parts; The relative motion and the plastic deformation of the sheet produce heat energy, which reduces the viscosity of the lubricating film and reduces its strength; under the action of high pressure, instantaneous high temperature, and motion shear, the lubricating film on the convex part of the sheet is broken, and the sheet is in direct contact with the mold. The raised parts of the sheet metal are scraped off by the raised parts of the die and become fragments. In front of the raised parts of the die, if the temperature is high enough, the fragments will soften, melt, and dry on the die to form a bond tumor. Once the adhesion tumor is formed, it is difficult to fall off, and the more sticky it is, the bigger it is, resulting in serious scratches on the surface of the stainless steel sheet stretched product. In addition, the stretching speed and the size of sheet deformation also play an important role in the formation of bond nodules. How to avoid the formation of nodules in the stretching die and improve the surface quality of the stretched parts are the technical difficulties in the stretching of stainless steel sheets.
