After the user has used the outrigger blocks of sand casting for a period of time, in order to improve the pressure bearing capacity of the product, the technical requirements of the drawings have been modified and the metal casting process is required. The rough mass of the product is 90kg, and the process yield is 82%.This type of casting generally has to bear a large load and the quality cannot be too large for handling. The third is that when using the metal mold casting top-pouring process, if it is not convenient to set up enough risers, a funnel-shaped sprue can be set in the key parts. During process design, attention should be paid to dealing with 4 problems: First, the machining allowance is 8mm on the upper surface of the big end, so that the floating oxide inclusions can be removed by processing as much as possible.
Due to the chilling effect of the metal mold, after the molten metal is poured, the outer layer of the casting Wholesale Automobile Parts Casting manufacturers solidifies quickly, and the partition requires more molten aluminum to feed during the solidification process, so the molten metal level of the runner continues to sink, so it is necessary Stop the ground and carry out supplementary pouring many times until the liquid level of the runner no longer sinks. The outer diameter of the large end of the casting is \u0026lt;850mm, the outer diameter of the small end is ;540mm, the height is 208mm, the thickness of the small end plane is 15mm, and the partition wall thickness is 12mm. On the one hand, it can reduce the entrapment of gas during the pouring process, and on the other hand, it is convenient for the subsequent supplementary pouring process. The fourth is to design the sprue into a funnel shape with a size of <80mm;45mm.
The second is to set 4 square risers uniformly on the upper plane circumference of the large end of the casting, and their functions are: feeding during solidification, when assembling, you can check whether the positioning of the upper box with the gating system and the metal mold is accurate. 3 waist round risers are set on the small end. At the beginning of the trial production, according to the usual situation, the sand casting process was used, with the big end facing down, the outer mud core formed 16 fan-shaped cavities, and the inner mud core formed a cylindrical cavity with cross-ribbed plates. As the liquid level in the sprue continues to sink, multiple supplementary pouring is performed to achieve sufficient The effect of feeding.. Therefore, using the top-injection semi-metallic casting process with the big end facing upwards, 16 fan-shaped mud cores and cylindrical mud cores are made into integral hanging cores, and the pouring system is set in the upper box.
Second, for large aluminum castings with many partitions, to avoid insufficient casting defects, the exhaust of the aluminum casting itself is very important. The third is to set up the air outlet riser above 8 of the 16 places where the casting partition intersects (the interval is taken), which is beneficial to the filling of the partition. Since the pouring and raising system is generally set above the casting, and the cushion aluminum casting has to bear the load, there are many partitions inside, and the structure is more complicated. In this way, when the molten metal is top-poured, serious problems will occur in the cavity. The phenomenon of turbulence, oxidation inclusions are more serious.
The rough mass of the product is 87kg, and the process yield is 73%. A set of sprue pouring, wet type dry core, the first product was successfully manufactured, no casting defects. The working temperature of metal type is 90~120. The following factors should be paid attention to in the process design of this kind of aluminum castings: First, the upper surface of the casting should be left with a large machining allowance in order to remove as much as possible the oxide inclusions floating on the top. Therefore, the product generally requires a metal mold casting process, but in actual production, the pouring and ram system is still formed in the sand mold. The outrigger block used for railway cranes is made of ZL104
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