Research On Quantitative Dosing System Of Molten Magnesium Alloys

The magnesium alloy parts have a great potential to be used in automobile and electronic products, and the application of magnesium alloys grows at 15% every year in the world. Over 90% of the magnesium alloy parts are produced by casting technology nowadays. While 90% of the casting magnesium alloy parts are produced by die-casting. However, molten magnesium alloys are prone to be oxidized,combusted, and bring burning loss and inclusions, which will badly affect the quality of the parts, and result in unsafety accidents. As a result, the cold chamber die casting machine has to be equipped with melting and transportation system of magnesium alloys. Nowadays, there are several companys oversea which produce the relative equipments. In domestic, the development of this field is much laggard, and most of the system unites are import.In this paper, a delivery system based on a vanaxial pump for magnesium alloys melt has been designed. The mathematic models have been deduced out based on the fluid dosing experiments, and the control system was developed based on Programmable Logic Controller (PLC). The application of this system in transportation of molten magnesium alloys confirmed that it could precisely dose Mg alloy melt, and the error could be controlled within 5%. This system can prevents the molten magnesium alloys from oxidization, combustion, melting loss, and inclusions efficiently during the casting process. This system is important to assure the quality of the casting and reduce the cost of die casting, and, it is useful to the development of the die-cast industry in our country.Firstly, based on the purpose and requirements of the transportation, the hardware system has been set up. The whole system includes driving device, mechanical device and electrical-controlling device. The frequency conversion driving system is used as power device. Vanaxial pump is chosed as mechanical device; and Programmable Logic Controller (PLC) is adopted as the upper controlling-device. LCD touch panel is chosed as Human Machine Interface (HMI).The controlling software of this system is created. The whole software consists of one main program and five subprograms, and they are free-port initialization subprogram, transporting formulae subprogram, transmitting subprogram, continuous transporting formulae, and running-time subprogram."WinCC flexible"is used as the configuration software to configurate the Human Machine Interface.In order to deliver dosing amount precisely, speed of the electromotor is altered through changing the frequency of the transducer, and running-time of the electromotor is also controlled. A mathematic model Q1=f(N,T)has been deduced out based on the fluid dosing experiments. The effect of different degrees of the vane-rotor on the dose has been discussed, and the testing results indicate that the dosing- precise of 15°degree of the vane-rotor is much higher than the 20°one.According to the examination test, the relationship between dosing amount Q1 ,which is used in water simulation formulas, and Q2 ,which is used in magnesium alloys simulation formulas, is achieved, and it is Q2=k Q1.Through the automatic controlling, this delivery system can achieve the goal that the dose of transportation can be altered from 500g to 5000g each time, and the error could be controlled within 5%.