1. Stainless steel drawing is suitable for stainless steel materials: 1Cr18Ni9Ti and 0Cr18Ni9Ti are commonly used in austenitic stainless steel. In the process of drawing, 1Cr18Ni9Ti is more stable than 0Cr18Ni9Ti and good anti-cracking. Therefore, 1Cr18Ni9Ti materials should be selected as far as possible.
2, stainless steel tensile reasonable selecting mould material: stainless steel hardening significantly in the process of deep drawing, there is a lot of hard metal, cause adhesion, easy to scratch, wear parts and mould surface, therefore cannot use the general mold tool steel. It is proved by practice that selecting copper base alloy mould can eliminate the surface scratches and scratches of stainless steel parts and reduce the damage rate. Another kind of material for high aluminum copper alloy mold material (including aluminum 13 wt % ~ 16 wt %), the material and SUS304 stainless steel solubility is small, deep drawing parts and moulds are not adhesive, not easily get scratches scratches on the surface of the deep drawing, product polishing cost is low, has successful application in the field of deep drawing of stainless steel. However, due to the low hardness of this mold (40HRC ~ 45HRC), it is often used in the production of relatively thick t/D products. General drawing depth of 1500 ~ 2000 pieces after the die surface is easy to start from the round Angle R is radiated drawing deep edge. Silicon nitride ceramics (Si3N4) has become an important engineering materials, especially the reaction sintered silicon nitride ceramic, has a good high and low temperature mechanical properties, thermal shock and chemical stability, and can be very convenient to make complex shape parts. The high hardness, high abrasion resistance and high chemical stability of ceramic materials can be used to replace the metal mould drawing and deep SUS304 stainless steel with the reaction sintering silicon nitride material.
3. The stainless steel drawing has reasonable convex and concave Angle, and the Angle of concave mould has a great relationship with the stress size and distribution. The radius of the circle is large, and the area of pressure margin is insufficient. And if the round corner is too small, the material into the concave die in the process of deformation resistance will increase, the material is not easy to flow and transfer, thereby increasing the maximum tensile stress of the force transmission area, may lead to cracking. Therefore, it is very important to choose reasonable convex and concave radius. The rp/t is approximately equal to 4, which is helpful to prevent cracking. The radius of the concave die and the convex mould is increased, and the deformation degree of the concave mold increases, and the concave mode is 5mm ~ 8mm
It helps prevent cracking.
4, stainless steel stretching with belt thinning drawing: previously discussed through experiment also proved by thinning drawing of deep drawing parts will be decreased and the maximum tangential residual stress, which can effectively prevent the longitudinal cracking. According to the different deformation degree and the original sheet thickness, select the appropriate attenuation coefficient Ψ n (average 0.9 t ~ 0.95 t), if Ψ n starts to make the deformation and stress values increase sharply, leading to the bottom of the deep drawing parts.
5, stainless steel tensile add intermediate annealing process in deep drawing process: after repeated drawing should be an intermediate annealing process, can completely eliminate the residual stress, and restore the organization of the austenitic stainless steel. For high hardness of stainless steel, usually after 1 ~ 2 drawing process, intermediate annealing is required. Like 1 crl8ni9ti generally heating temperature is 1150 ℃ ~ 1170 ℃, the heating time for 30 min, and in the air or water cooling. And, both between process, heat treatment and finally finished heat treatment, should immediately after deep drawing, as far as possible in order to avoid due to long-term storage, artifacts due to internal stress deformation or cracks. However, annealing and post-annealing cleaning can lead to an increase in production cycle and affect surface quality
6. Appropriate lubricant is used for the stainless steel drawing: it has obvious effect on the drawing of stainless steel with proper lubricant. The lubricant can form a thin film with a certain toughness and elongation between the convex and concave molds, which is conducive to the forming of stainless steel. For the tensile deep deformation and forming difficult stainless steel drawing, the polyfluoroethylene film can be used as lubricant in actual production. Polyfluoroethylene film has excellent tensile strength, toughness and elongation and easy cleaning. Shanghai juji dry film, in the deep drawing process can dry film with billet deformation, can always to separate billet and mold, combined with the film itself has a certain porosity and a large number of fiber crack, so it can deposit a certain amount of lubricating oil, so the film is equivalent to a layer of dry film lubricant.