Taking out the alloy liquid from the smelting furnace and pouring it into the mold is a key process in the casting production process. Although this process takes a short time, the movement of the alloy liquid during the transmission process is very intense, and the liquid level The oxide film of the alloy is continuously damaged, new oxide film is continuously generated, and the ‘oxide film interlayer’ is continuously involved in the alloy liquid. Therefore, most waste products are caused at this stage. From the perspective of being involved in the ‘oxide film interlayer’, the control of the pouring process is much more important than the control of the smelting process.
When the aluminum alloy liquid flows, if the flow rate is low, the surface tension of the alloy liquid can restrict the liquid flow, so that it will not disperse and splash; if the flow rate is high, the liquid flow will inevitably disperse and splash. Many research works have shown that for many liquid casting alloys, the critical velocity of the liquid flow without dispersion and splashing is 0.5m/s. At present, the widely used casting method is still the traditional gravity casting, and it will also be Cast Aluminum Alloy Motor Parts injected into the casting mold from the top of the casting mold by using the gravity of the alloy liquid itself. In fact, for aluminum alloys, this is a very undesirable pouring method, because when the liquid flow falls from the sprue to its bottom, the flow velocity is much higher than 0.5m/s, and the liquid flow is unavoidable. of. In addition, there are many problems in the design principles of the gating system that are regarded as conventional by some people.
The liquid flow in the gating system often occurs turbulent flow and splashing, which will cause a large number of ‘oxide film interlayers’ and air bubbles to be involved in the alloy liquid, resulting in Various casting defects. Using differential pressure casting or low pressure casting process, the liquid flow enters the mold from the bottom of the mold. If controlled properly, the alloy liquid can fill the mold smoothly and slowly, with few defects in the casting, and the mechanical properties of the material are of course greatly improved. It is known from the literature that many of the larger aluminum alloy and magnesium alloy castings used in American aviation and aerospace are manufactured by the differential pressure casting process. There is also a smooth filling pouring process worth noting, which will be “tiltcasting or tiltfilling” that transfers the liquid flow horizontally.
The pouring method is: the mold and the ladle (or other alloy containing liquid Container) is placed in a tiltable device to align the gate of the mold with the outflow port of the ladle, and then the device is slowly tilted to smoothly transfer the alloy liquid from the ladle to the mold. At present, there have been reports of using this process for the production of aluminum alloy castings and titanium alloy castings, mainly for some particularly important castings. Although the latter two casting processes work well and are more suitable for the production of aluminum alloy castings, gravity casting is, after all, a traditional process that has been used for thousands of years, and there are also constraints on production conditions. Today, the vast majority of castings are still produced by gravity casting.
In order to further improve the quality of castings and make full use of the potential of aluminum alloys in terms of mechanical properties in casting production, improving the gating system is a topic that must be seriously faced at present. In recent years, the use of video radiography and computer simulation can better understand the filling process of alloy liquid. However, due to the constraints of the parameters currently available for reference, there are still many gaps in the understanding of the filling process. very precise. There are many process methods suitable for aluminum alloys. The following sand casting process only involves horizontal parting. Some suggestions for improving the gating system are summarized based on the research results of J. Compbell and others, and cannot be considered very mature. It can only be used as the starting point for us to update the concept, and the effective specific process plan still needs to be analyzed, researched and explored in the actual production.
Tags: Aluminum Alloy Die Casting Parts, Cast Aluminum Alloy Motor Parts, Cast Aluminum alloy Parts
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