Forming process of aluminum alloy by rheo squeeze casting

(1) Pouring of semi-solid alloy melt: the semi-solid slurry prepared by lspsf process is poured into the barrel of semi-solid squeeze casting equipment under a certain forming temperature. The barrel has the function of heating and heat preservation, and has been preheated to a certain temperature before, so as to maintain a good semi-solid structure of alloy melt.

(2) Mold closing and barrel docking: when the semi-solid alloy melt is poured into the barrel, it is operated by a certain transfer and docking mechanism, so that the barrel and the mold gate are completely sealed and butted. Before docking, the equipment has completed the preheating, spraying, clamping and locking of the mold.

(3) Rheo squeeze casting: when the die is closed and locked and completely butted with the barrel, the injection hammer is driven by the injection cylinder for semi-solid squeeze casting. The semi-solid squeeze casting equipment should have the function of adjusting the injection pressure and injection speed. According to the semi-solid squeeze casting process, the maximum injection pressure of the equipment is 940kn. According to the minimum part projection area, the maximum injection specific pressure can reach 260mpa, and the injection speed range is 0.08 ~ 0.8m/s.

(4) Secondary cavity extrusion (forging) function (optional for this process): through the structural design of the die, the upper die is directly connected with the clamping cylinder. After the semi-solid alloy melt extrusion casting is completed to obtain the as cast parts, the clamping cylinder of the equipment carries out secondary cavity extrusion (forging) for the parts which are still in high temperature and not completely solidified through the upper die, and the extrusion reduction is determined by the die Generally, it does not exceed 5mm. Through the secondary cavity extrusion function, the casting defects can be better eliminated, and the plastic deformation strengthening effect can be achieved. The maximum extrusion force can reach 2800kn.

(5) Open the mold and eject the part: after the pressure maintaining and mold retaining are completed, the upper mold rises to open the mold, and the ejection cylinder pushes the injection hammer to eject the part directly, and then the part is manually removed with a clamp. The injection hammer is used not only as injection punch but also as ejector rod, with composite function.

According to the above process assumption, the injection mechanism of squeeze casting equipment is different from the traditional inverted pouring method, and the translational pouring injection structure is adopted, which has won the national patent. The squeeze casting process using the injection mechanism belongs to indirect squeeze casting process. During the design and development of the equipment, it is required that the equipment can change the mold structure through the clamping oil cylinder, without starting the injection mechanism, and can also carry out the direct squeeze casting production test through other ways of pouring alloy slurry directly into the mold. Secondary cavity extrusion (forging) will be the focus of follow-up research. As the reserve of equipment function, its essence is the combination of extrusion casting and forging process.

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