Development of foundry technology in foreign countries

In the face of the rapid development of information and technology in the world, and the rapid improvement of the modernization level of machinery manufacturing industry, especially the equipment manufacturing industry, China’s foundry industry (here we only talk about the situation in the mainland, excluding Taiwan, Hong Kong and Macao) should be aware of its historical responsibilities and the actual gap with developed countries, and make bold use of the latest achievements of modern science and technology and management, We should recognize the truth that “only the realization of high and new technology can keep up with the pace of the times”, grasp the development trend of modern foundry technology, adopt advanced and applicable technology, implement the strategy of sustainable development, base ourselves on the reality and look forward to the future, and lay a solid foundation for the process of modern industrial civilization in China by revitalizing and developing China’s foundry industry.

In general, developed countries have advanced casting technology, good product quality, high production efficiency, less environmental pollution, and a series of commercialized supply of raw and auxiliary materials. For example, transnational service system has been established in Europe. The production generally realizes mechanization, automation and intelligence (computer control, robot operation).

The cupola with large scale, high efficiency, dust removal, microcomputer measurement and control, external hot air supply, no furnace lining and water-cooled continuous operation is used for cast iron smelting. The cupola or electric furnace and cupola are commonly used for duplex smelting. The sulfur content in the molten iron is less than 0.01% by adopting nitrogen continuous desulfurization or shaking ladle desulfurization. AOD, VOD and other equipment are commonly used for alloy steel refining, Make h, O, N in liquid steel reach several or dozens of 10-6 levels.

In the production of important castings, the material requirements are high, such as the requirements of ductile iron P < 0.04%, s < 0.02%, cast steel p, s are < 0.025%, using thermal analysis technology to timely and accurately control the content of C and Si, using direct reading spectrometer to analyze more than ten elements in 2-3 minutes with high accuracy, C and S analysis and control can make the C and s content of ultra-low carbon stainless steel accurately controlled, The advanced nondestructive testing technology is used to effectively control the quality of castings.

Liquid metal filtration technology is widely used, and the filter can adapt to the filtration of high temperature such as cobalt base, nickel base alloy and stainless steel liquid. After filtration, the grade a qualification rate of steel castings was increased by 13%, the tensile strength and elongation of castings were increased by 50% and 100% respectively.

The technology of alloy cored wire treatment is widely used, which makes the technology of nodular iron, vermicular iron and inoculated cast iron stable, the recovery rate of alloy elements is high, and the treatment process is pollution-free. The microcomputer automatic control is realized.

Aluminum matrix composite materials are widely valued for their superior performance and increasingly turn to industrial scale applications. For example, various important parts such as driving rod, cylinder block, cylinder liner, piston, connecting rod, etc. can be made of aluminum matrix composite materials and have been used in advanced racing cars. In the process of automobile development towards lightweight, the amount of making various important automobile parts with magnesium alloy materials is second only to aluminum alloy.

The hot blast cupola, two rows of cupola with large spacing and oxygen enriched air supply are used. The electric furnace adopts preheating of furnace charge, reducing melting temperature, improving furnace operation rate, reducing opening time of furnace cover, strengthening heat preservation and implementing microcomputer control to optimize smelting process. Small riser and non riser casting are widely used in the production of ductile iron castings. The steel casting adopts heat preservation riser and heat preservation subsidy, and the process yield is increased from 60% to 80%. Considering the high labor cost and poor production conditions, robots are widely used. Due to strict environmental protection laws (electric furnace dust discharge has 9 national regulations of 100-250 mg / m3, cupola dust discharge, 11 national regulations of 100-1000 mg / m3, or 0.25-1.5 kg / T molten iron; sand treatment dust discharge, 8 national regulations of 100-250 mg / m3), the foundry attaches great importance to environmental protection technology.

In the production of large quantities of small and medium-sized castings, the computer-controlled high-density static pressure, injection pressure or air impact molding mechanization and automatic high-efficiency assembly line green sand molding process are mostly used. The sand processing adopts high-efficiency continuous sand mixer and artificial intelligence online control expert system of molding sand. The core making process generally adopts resin sand hot, warm core box and cold core box methods. In investment casting, silicasol and ethyl silicate are commonly used as binder in shell making.

The automatic die casting machine is used to produce aluminum cylinder and cylinder head, and several low-pressure casting production lines of iron-based alloy have been built. Special steel castings are produced by differential pressure casting. The production of centrifugal ductile iron pipes with various diameters accounts for more than 95% of the total cast iron pipes, and the annual output of ductile iron pipes accounts for 30% – 50%.

The EPC technology has been successfully applied to mass production of complex castings such as 4-cylinder cylinder block and cylinder head, with a productivity of 180 models / h. In the process design and mold processing, CAD / CAM / RPM technology is used; in the specialized and complete set preparation of casting machinery, CIMS technology is used.

In the whole process of casting production, technical standards are implemented actively and strictly. The scrap rate of castings is only 2% – 5%. The standards are updated rapidly (standard age is 4-5 years). ISO 9000, ISO 14000 and other certifications are generally carried out.

Pay attention to the development and use of Internet technology, and build their own home pages and sites. The rapid development of e-commerce, remote design and manufacturing, virtual foundry in foundry industry.

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