Compared with the cupola, the medium-frequency melting furnace smelting iron liquid can not only reduce environmental pollution, but also control the quality of molten iron. It has less investment and can easily carry various cast irons such as ductile iron, vermicular cast iron and gray cast iron. Multi-brand production and flexible production methods. Compared with the melting using the pig iron as the main ingredient, the molten iron can be smelted by the scrap carbon increasing process, which can reduce the cost of the molten iron by 1,000 yuan. The medium frequency electric furnace can realize self-fault diagnosis and protection, reduce maintenance time and workload, and can be connected with the computer smelting process automatic control management system, which is easy to operate and manage. Therefore, after the 1990s, most of the new cast iron foundries in foreign countries and China used molten iron in a coreless induction furnace.
When the medium frequency induction electric furnace melts the molten iron, the recycled material that has been crushed and shot blasted cleanly can significantly improve the quality of the molten iron and reduce the energy consumption of the molten iron. Our foundry has done production test on the 10t intermediate frequency furnace, using clean returning materials to produce high-power diesel engine cylinder heads, the casting porosity of the castings is reduced by 6 percentage points, and the electricity consumption of molten iron is reduced by 90kW·h/t; At the same time, it can effectively reduce the labor intensity of workers' slag, improve the casting smelting operation environment, reduce the slagging phenomenon of the power frequency furnace mouth, solve the difficult problem after the slag slag formation, and improve the service life of the power frequency furnace lining by 20%. Smelting production efficiency. Therefore, when using medium frequency induction furnace to smelt molten iron, it is necessary to attach great importance to the purification of the charge, especially the crushing and shot blasting of the recycled material. This is an important part of the efficiency of the medium frequency furnace smelting iron.
The medium frequency induction electric furnace smelting iron liquid can also produce gray cast iron cylinder block and cylinder head with excellent processing performance. The influence of smelting furnace type on the machinability of gray cast iron has been debated for many years. Most founders believe that the gray cast iron parts produced by induction furnace melting are inferior to the gray cast iron parts produced by cupola smelting. In this regard, in 1998, the American Foundry Association organized researchers to study the effects of induction furnace melting and cupola melting on the workability of gray cast iron (equivalent to HT150, HT200, HT250) by turning and drilling test methods.
Studies have shown that when the cupola is smelted, the material processing performance is not better than that of the induction furnace, and for some processability data, the gray cast iron smelted by the induction furnace is more processable. Our company has also studied the processing properties of gray iron castings produced by induction furnace melting, and verified it on the mass-produced HT250 cylinder: the medium frequency induction furnace produces the cylinder processing performance, which is better than the hot air cupola and electric furnace. The processing performance of the cylinder produced by the smelting is improved by 20%, the mechanical properties of the casting are improved by 10%, the metallographic structure is improved, and the compactness of the cylinder casting is improved. This shows that the smelting iron in the medium frequency induction furnace can produce ash with excellent processing performance. The key to cast iron cylinders and cylinder heads is to use a good smelting process - scrap steel carbonization process, and the use of high-quality recarburizers and good breeding process.
