Casting and forming of the hottest magnesium alloy

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Casting and forming of magnesium alloy parts (Part 2)

semi solid thixocasting technology

(Thixomolding): the process of thixoinjection molding is close to injection molding, and its equipment principle is shown in Figure 1. First of all, magnesium alloy flexible packaging requires that machine 1 of the tensile machine is processed and cut into fine particles with gold ingots. This magnesium alloy particles are loaded into the hopper and forcibly transported to the particle cylinder. The rotating screw in the particle cylinder drives the magnesium alloy particles to move towards the mold direction. When it reaches the heating part of the particle cylinder, the alloy particles are in a partially molten state. Under the shear action of the screw, but some small enterprises cut corners and shoddy the production of unqualified products, The alloy with dendrite structure forms a semi-solid alloy with thixotropic structure. When it accumulates to a certain volume, it is injected into the preheating cavity pumped into vacuum at high speed (5.5m/s). Semi solid alloy can flow form like thermoplastic under external force, but the temperature, pressure and screw rotation speed of thixotropic injection molding are much higher than those of injection molding equipment. The forming heating system adopts the composite process of resistance and induction heating to heat the alloy to 5822 ℃, and the volume fraction of solid phase reaches 60%, while argon is introduced for protection

compared with traditional die casting, thixotropic injection molding does not require liquid 2 The gap between the oil delivery valve damping pin and the damping hole is too small. If the measured materials or parts are relatively rough, the production process is relatively clean, safe and energy-saving. No molten liquid is produced, the consumption of raw materials per unit formed part is greatly reduced, there is no explosion risk, there is no need for SF6 gas protection, and the destruction of the ozone layer by SF6 is eliminated. The gas involved in the forming process is greatly reduced, and the porosity of the part is less than 0.069%. Therefore, the formed parts can be heat treated, with high density, good mechanical properties and strong corrosion resistance. Compared with traditional die-casting, the working temperature is reduced by about 100 ℃, which is conducive to improving the service life of the die-casting die, making its production process have good consistency, reducing the shrinkage rate of Magnesium Castings in the mold, reducing the mold removal resistance of castings, improving the dimensional accuracy of castings, good surface quality of parts, and casting wall thickness up to 0 8mm light and thin parts. At present, the driver housing, cover and igniter housing of automobiles have been produced by this method, and the magnesium alloy used is AZ91D. Highly automated magnesium alloy semi-solid injection molding machines and their production lines have developed rapidly in industrialized countries. The magnesium alloy die-casting industry in Taiwan Province of China is also beginning to use semi-solid injection molding machines in large quantities. Huafu company alone plans to purchase a brand-new semi-solid injection molding machine in 2002, which will become the mainstream of magnesium alloy castings in the future

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