Features stainless steel sheet drawing
Due to the high yield point of stainless steel 304ba, high hardness, work hardening effect is remarkable, stainless steel sheet were drawing the following features:
1) due to poor thermal conductivity than ordinary low-carbon steel, resulting in deformation force required;
2) stainless steel sheet drawing, the severe plastic deformation hardening, easy to wrinkle when drawing sheet, full BHF want greater;
3) sheet metal bending in the rebound and reverse pull furrow mold caused by bending at the corner, and usually forms a depression in the side wall of distortion product makes high dimensional accuracy and shape requirements of the product to achieve the required increase in plastic surgery procedures.
4) stainless steel sheet bonded tumor phenomenon drawing process prone.
From the microscopic point of view, the key panel material rough mold surfaces are uneven, due to the process of drawing BHF larger load raised by the local unit to withstand a lot of pressure parts; because between the sheet and the mold to produce relative motion and the plastic deformation of sheet metal production of heat, making the lubricating film viscosity decreases, lower intensity; protruding parts of the sheet in a high pressure, high temperature instantaneously by shearing motion, the lubricant film rupture, sheet metal in direct contact with the mold, sheet metal parts to be scraped off the mold raised bumps become part of people die in front of the debris pile protruding parts, such as the temperature is high enough so that the pieces soften, melt, dry welding in the mold to form an adhesive tumor. Bond and form a tumor is difficult to come off, and the more the bigger stick, causing deep drawing steel sheet products severe scratches left on the surface. In addition, the drawing speed, sheet deformed child size also plays an important role on the bond neoplasia. How to avoid drawing die bonding tumor formation, improve the surface quality of drawing parts are stainless steel sheet drawing technical problems lies.
2 solutions
Deep drawing steel sheet bonding occurs during tumor has been plagued by production site, a great deal of trouble to producers, but due to the bonding neoplasia and other issues related to tribology, influenced by many factors. Currently, we can only propose measures from different angles to prevent tumor formation and reduce adhesion.
2.1 working part mold material selection and heat treatment
For bond tumor problem, choose a stainless steel mold material Chak relations, two points should be combined according to the pro stainless steel sheet metal and mold material: Choose one anti-adhesion strength, and second mold material wear and friction reduction. In general, the metal lattice type, lattice pitch, electron density, electrochemical properties interlinked metal, which attract each other, dissolving ability, easy to adhere together, the results of the friction coefficient becomes large. Cr, Ni and Fe miscibility big, so when using steel deep drawing, bonding tumors more susceptible to the phenomenon. Practice has proved that: use aluminum bronze, aluminum bronze hard sticking better; using Steel bonded tungsten carbide manufacturing die than raise with Cr12Mov tufftride manufacturing die life several times, and non-stick mode; if using code 3054 alloy cast iron, just mold surface flame hardening, the mold surface does not appear bond tumor. Also in vulnerable parts of the mold can be used carbide inserts, it has excellent compression performance, superior wear resistance and long-lasting love of the surface roughness and dimensional control. However, due to the price, the production used less.
Surface processing mold work portion 2.2
Stainless steel drawing die surface quality requirements are high. Low surface roughness may serve to improve the anti-friction and anti-adhesion effect so. After drawing die during the grinding process, the more important is to eliminate machining marks. In the mold is often overlooked grinding and polishing processes. It should be noted. Throughout the mold process, polishing workload should account for one third, because the appearance of quality stainless steel products depends largely on the mold polishing techniques. Reduce mold surface roughness, a corresponding reduction in the number of grinding mold, mold life correspondingly improved.
If the mold surface polishing enough, coupled with deep drawing steel sheet bonded easily cause tumor characteristics, thus drawing out of the product scratches serious. And that the scratches on the product with polished to solve time-consuming and reach results. Therefore, we should step up and down in the mold polishing great effort, only the mold surface machining accuracy is improved in order to reduce scratches, mold repair mold life can be greatly improved. In recent years, there have been a variety of new techniques of polishing and polishing tools, the development of ultrasound, electrolytic polishing, abrasive blasting, honing extrusion and other new technology, new equipment. According to information on CrWMo, 3Cr12W8V, Cr12 mold test three materials studied electrochemical polishing, polishing prove that only 5-10 minutes from the mold cavity surface roughness of the original Ra3.2-Ra1.6 down to Ra0.4-RaO.2 basis. While by electrochemical polishing may improve the surface hardness to improve wear resistance. Again, ultrasonic polishing machine can be used by soft nitriding treatment cavity fine polishing, it is easy to avoid the disadvantages of manual polishing damage nitride film. For new polishing techniques we should take active steps to use and summary.
Stainless steel drawing die surface quality requirements are high. Low surface roughness may serve to improve the anti-friction and anti-adhesion effect so. After drawing die during the grinding process, the more important is to eliminate machining marks. In the mold is often overlooked grinding and polishing processes. It should be noted. Throughout the mold process, polishing workload should account for one third, because the appearance of quality stainless steel products depends largely on the mold polishing techniques. Reduce mold surface roughness, a corresponding reduction in the number of grinding mold, mold life correspondingly improved.
If the mold surface polishing enough, coupled with deep drawing steel sheet bonded easily cause tumor characteristics, thus drawing out of the product scratches serious. And that the scratches on the product with polished to solve time-consuming and reach results. Therefore, we should step up and down in the mold polishing great effort, only the mold surface machining accuracy is improved in order to reduce scratches, mold repair mold life can be greatly improved. In recent years, there have been a variety of new techniques of polishing and polishing tools, the development of ultrasound, electrolytic polishing, abrasive blasting, honing extrusion and other new technology, new equipment. According to information on CrWMo, 3Cr12W8V, Cr12 mold test three materials studied electrochemical polishing, polishing prove that only 5-10 minutes from the mold cavity surface roughness of the original Ra3.2-Ra1.6 down to Ra0.4-RaO.2 basis. While by electrochemical polishing may improve the surface hardness to improve wear resistance. Again, ultrasonic polishing machine can be used by soft nitriding treatment cavity fine polishing, it is easy to avoid the disadvantages of manual polishing damage nitride film. For new polishing techniques we should take active steps to use and summary.
