In the rapid development of science and technology today, due to the special advantages of casting molding process, some complex structural parts are currently no other manufacturing process can be replaced. Casting process is still the most economical and convenient metal molding process. With the integration of the global economy, in the international cooperation is becoming increasingly close, increasingly fierce competition, China's automotive casting industry should more fully utilize the advantages of casting resources, the development of their own casting industry.
1. The status of China's foundry industry
China is the world's largest producer of castings, according to the data, China's casting products accounted for about 1% of the output value of the national economy. In recent years, the casting import and export trade has grown faster, the casting production has reached about 9%. China's foundry sites up to more than 20,000, casting industry employees up to 1.2 million. The "Yangtze River Delta" region's casting production accounted for 1/3 of the country, the region is mainly private enterprises, automobiles and auto parts industry development has strongly driven the development of the casting industry. Wanfeng Aote is Asia's largest aluminum alloy wheel enterprises, annual output value of more than 1 billion yuan, exports amounted to 6,000 U.S. dollars. Kunshan Fujiwa Machinery Co., Ltd. produces castings for automobile engines and brake systems, with an annual output of 40,000t and a sales revenue of 550 million yuan. East China Tekashi is an advanced modern cylinder block castings production enterprises, with an annual output of 1 million pieces
Car cylinder block casting capacity. Shanxi is a large province of foundry resources, there are rich pig iron, coal, aluminum and magnesium, electricity, labor resources, so that the foundry industry in Shanxi has a unique advantage, with 500 foundry enterprises, 80% of private enterprises. Shanxi International, Hejin Shanlian, Shanxi Huaxiang annual output of 40,000t, 20,000t, 120,000t. "Three Eastern Provinces" have FAW Group, Hafei Group and other key automotive enterprises to drive the growth of automotive casting production. FAW Group casting company, has formed a production capacity of 400,000t castings. Liaoning Northern Crankshaft Co., Ltd., to the "Eleventh Five-Year" end will form an annual output of 150,000 engines, 1 million pieces of crankshafts, crankshafts with an output value of 2 billion crankshaft production base. "Pearl River Delta" die-casting industry is developed, there are more than 700 die-casting enterprises, the annual output of 200,000 t. Dongfeng Nissan, Guangzhou Honda, Guangzhou Toyota and parts and components enterprises have driven the development of die-casting industry, the car cylinder block, cylinder head of the die-casting production growth year by year.
2. Foreign casting industry status
In recent years, the global casting industry continued to grow, casting production in 2004 than the previous year increased by 8.4%, China produces 22.42 million tons of castings, the world's first ranked, an increase of 23.6% over the previous year. The world's top ten producers of castings production and growth rate is shown in Table 1. from Table 1 can be seen, in 2004, China's casting production accounted for about 1/4 of the global casting production. the fastest growth in Brazil's casting production, amounting to 25.8%. Growth rate of more than 2-digit countries are Brazil, China, Mexico, India, are developing countries. The casting growth rate in developed countries is generally lower. U.S. casting production since 2000, has receded to No. 2. 2004 U.S. castings total output of 12.31 million tons, of which 35% of gray iron parts, ductile iron parts accounted for 33%, cast steel parts accounted for 8.4%, aluminum alloy parts accounted for 16%. From the point of view of demand, ductile iron castings and aluminum castings in the growth of demand. 2003 imported castings accounted for 1 5% of the total demand for imported castings, the price of imported castings than the U.S. domestic low 20% to 50%. In recent years due to casting environmental requirements, high energy consumption, labor is expensive, etc., the United States large automobile companies to produce ordinary automotive castings of the foundry has been closed, and gradually the production of castings to China, India, Mexico, Brazil and other developing countries. Japan's casting industry downturn, its employees in the reduction. 2004 Japan's total casting production of 6.39 million tons, of which 42% of gray iron parts, ductile iron parts accounted for 30%, cast steel parts accounted for 4%, aluminum alloy parts accounted for 21%. From the point of view of demand, ductile iron castings and aluminum castings in the growth of demand. Japan casting industry in technology innovation has done a lot of work, developed a spherical low expansion casting sand, high vibration cast iron materials, in silicon heat-resistant ductile iron and other materials. Its vacuum die casting castings can be welded and heat treatment, semi-solid casting production for automotive aluminum wheel hub, improved strength and elongation. Magnesium alloy die casting further development, and replace gravity casting, its performance improvement, cost reduction.
3. The direction of development of automotive casting technology
Automotive technology is developing towards lightweight, numerical value, environmental protection. According to relevant information reports, the car weight every 10% reduction, fuel consumption can be reduced by 5.5%, fuel economy can be improved by 3% -5%, while reducing emissions by about 10%. There are two main ways to lighten castings. One is the use of aluminum, magnesium and other non-ferrous alloy castings, U.S. statistics in 2003, there are 2/3 of the aluminum castings used in automobiles, each car reached 107 kg. The second is to reduce the wall thickness of the castings, the design of the multi-part combination of castings, the production of thin-walled high-strength composite castings, and to reduce the amount of machining, the production of near-end shape castings. With the rapid development of automotive technology, in order to shorten the casting production preparation cycle and reduce the risk of new product development, requires the use of rapid mold making technology, computer simulation, three-dimensional modeling, CNC technology. And cleaner production, waste regeneration is the development trend of the foundry industry, reduce energy consumption is the theme of its sustainable development. China's automobile foundry industry must take the road of high efficiency, energy saving, material saving, environmental protection and green casting, because the state and society require strict control of the automobile foundry industry's energy consumption and pollution of large households, in order to facilitate the improvement of the foundry industry, hot, dirty, tired of the labor-intensive industry staff's labor environment.
4. Automotive casting technology development trend
Domestic and international automotive casting technology development trend is a lot, now only some of the automotive industry in the automotive industry in a large number of castings in the assembly line production technology and development trends.
4.1 Sand casting molding technology
Tide molding through the manual compacting a shock + compaction compacting → high-pressure + micro-vibration compacting → gas punch compacting → static pressure compacting several stages of development. The essence of the static pressure modeling technology is "gas pre-compacting + compaction", which has the following advantages: clear casting contour, high surface hardness and uniformity, pulling the mold inclination is small, high utilization rate of the type plate, small wear and tear of the process equipment, casting surface roughness is low, low casting type waste rate. Therefore, it is the newest and most advanced molding process, and has become the mainstream compacting process. At present, high-pressure molding and a single gas impulse molding has been gradually replaced by static pressure molding, the original high-pressure molding line and gas impulse molding line host has been gradually updated to static pressure molding host, new foundries are preferred to use static pressure molding technology. At present, the more famous foreign manufacturers of static pressure molding equipment manufacturers have Germany's KW company, HWS company and Italy's Savelli company. Most of the domestic automobile casting manufacturers choose HWS company or KW company manufacturing equipment, such as FAW Foundry, Dongfeng Automobile Foundry, Shanghai St. Germain Foundry, East China Tektronix, Shanxi Sanlian, Guangxi Yuchai, Wuxi Diesel Engine Plant and so on.
4.2 Near-net shape technology
(1) disappearing mold casting forming process
Disappearing mold casting is also known as gasification mold casting, solid casting, no cavity casting. The dimensional accuracy of the process is as high as 0.2 mm or less, the surface roughness can reach Ra5μm ~ Ra6μm, by the casting industry as "the 21st century casting new technology", "casting of the green project". The process is the use of non-binder dry sand and vacuum technology. According to the statistics in 2003, there are 150 enterprises in China to use this process to produce the box class, pipe fittings valve class, heat-resistant wear-resistant alloy steel and other three major categories of castings, with a total output of more than 100,000 t. Domestic automobile foundry, some of the casting production line using domestic: some simple production line or stand-alone production; some of the casting production line production using foreign imports. In 1993, FAW Group Company introduced shaking table for molding, pre-foaming machine for EPS mold and molding machine from American Fukang Company to produce automobile intake pipe. Changsha Engine General Factory introduced automatic casting line from Italy to produce aluminum alloy cylinder block and cylinder head castings. Hefei Forklift Group produces complex case castings with 4-section foam mold pieces bonded into a whole process, and the dimensional accuracy can reach CT7-CT8 level, and the products are exported to the United States. Chengdu Cheng Gong Group, with 8 pieces of foam mold piece bonded into a whole process to produce loader transmission, casting quality of 320 kg, compared with the sand casting, blank weight reduction of 15%, the yield rate of more than 95%. Vanishing mold process in recent years in the United States has a greater development, General Motors invested in the construction of six vanishing mold casting production line, mass production of aluminum alloy cylinder block, cylinder head castings. In the future, the process will be a large number of rapid mold technology and simulation technology, in order to shorten the production preparation cycle, to achieve rapid production of castings. The future direction of development must be high-grade molds with good quality, complexity, precision and long life. Improve the technology of the mold materials, molding process, coating technology, tooling equipment technology level, so that the EPS castings to obtain a broader development prospects.
(2) investment casting forming process
China's automotive investment casting technology has made great strides, the use of near-net shape technology can be produced without the amount of casting products. Investment casting process has a water glass shell process, composite shell process, silica gel shell process. Automotive product materials are carbon steel, alloy steel, non-ferrous alloys and ductile cast iron. Foreign high-alloy steel, superalloy materials. Melting equipment domestic use of ordinary, fast medium-frequency furnace; foreign use of vacuum furnace, rotary furnace, high-frequency furnace technology. The surface roughness of the parts using silica-sol shell-making process can reach Ra1.6μm, dimensional accuracy up to CT4 level, the minimum wall thickness up to 0.5 ~ 1.5mm. Europe, the United States, Japan and other countries are beginning to pay attention to the fine castings in the automotive industry and the expansion of the application. China's automotive precision castings market demand is also growing rapidly and development, in 2003 the production of precision castings for 600,000t, the output value reached 11 billion yuan. Dongfeng Motor Precision Casting Co., Ltd. adopts silica sol + water glass composite type shell making process to produce high technology content, high value-added products, the original castings, forgings, machining and multi-piece assembly structure design and manufacture of a whole precision castings, significantly reducing the manufacturing cost.
Melt mold precision casting forming process in the future development trend is the casting products are increasingly close to the parts and components products, the traditional precision castings only as a blank, has not adapted to the market's rapid response. The complexity of parts and components products and quality grade is getting higher and higher, the means of research and development is getting stronger and stronger, specialized collaboration began to emerge, CAD, CAM, CAE application has become the main technology of parts and components product development. Dongfeng Motor Corporation, FAW Group Corporation precision casting enterprises as China's precision casting industry leader, must be able to rely on strong R & D strength and advanced technology rapid development.
4.3 core technology
At present, the domestic and foreign automobile casting core has three kinds of core technology, in modern automobile casting is often used in parallel with the main process of hot core box core, shell core core, cold core box core, etc., the traditional combined fat or oil sand core has been eliminated. Cold core box technology process has two characteristics: first, fast hardening speed, high initial strength, high productivity; second is the high precision of the core size to meet the production of thin-walled high-strength castings of the core. Therefore, the core process technology has a cold core box technology-based development trend. FAW Foundry, Dongfeng Automobile Foundry, Shanghai St. Germain Foundry, East China Tektronix, Shanxi International Foundry, etc. are used in cold core box core technology. Contemporary advanced 110L cold core box core making machine see Figure 1.
The most advanced core making process is a combination of core locking (Key Core) and cold core box and other technologies of the core center, the entire core shooting, core, trimming burrs, multiple cores are positioned in a combination of one, coating, drying and other processes, all with one or more core making machine and robot automation completed. More famous foreign core making center manufacturers are Spain LORMENDl company, Germany Laempe company and Hottinger company, Italy's FA company. Dongfeng Automobile Foundry, FAW Foundry, Shanghai St. Germain Foundry, East China Tektronix, Shanghai Diesel, Luotuo two iron, Weichai, Jiangxi Isuzu, etc. are used in cold core box core center technology.
4.4 cast iron melting technology
At present, cast iron melting technology at home and abroad, there are two main ways: one is the use of large-scale hot air dedusting cupola furnace and industrial frequency holding furnace duplex melting process; the second is the use of intermediate-frequency induction furnace melting process technology. U.S. Inda and Pilot company production of intermediate frequency furnace technology began to pay more and more attention to the technology is becoming more mature, its clean, environmentally friendly, energy saving, high efficiency, safety advantages are prominent, is the direction of future development.
Therefore, cast iron is from the past with the industrial frequency furnace melting gradually transitioned to the use of efficient and energy-saving medium-frequency furnace melting. First, the steam foundry company, Dongfeng Motor Company, the use of the company and the company's production of medium-frequency furnace and holding furnace technology, has developed the application of spheroidal agent, inoculant, peristaltic agent and a variety of other additives products, the formation of commoditization, standardization, specification, serialization. Cast iron gestation more with photoelectric control with the flow of gestation machine. Newly developed feed wire spheroidization method and its modern detection technology combined with
SINTER CASTZ art is a cast iron spheroidization and creep treatment of a very advantageous process, the increasing number of applicants. Foreign metal charge after crushing, purification, weighing, greatly improving the melting efficiency and iron quality. Domestic foundries such as Tianjin Toyota, Tianjin Qimeda, Suzhou Qimeda and other foundries have adopted the crushing process of furnace charge.
4.5 Aluminum alloy cylinder block, cylinder head die casting forming technology
Aluminum alloy is the fastest and most widely used light metal in the automobile, because the performance of the aluminum alloy itself has reached the quality of light, high strength, corrosion resistance requirements. Initially, aluminum alloys were used only for parts that were not subject to impact. Later, by strengthening the alloying elements, the strength of aluminum alloy has been greatly improved, and due to the characteristics of light weight and good heat dissipation, it can meet the requirements of engine piston, cylinder block and cylinder head working in harsh environments. Aluminum alloy cylinder block, cylinder head die-casting forming core technology can improve the purification, refining, refinement, metamorphosis and other material quality control, so that the quality of aluminum castings to achieve consistency and stability. With the development of China's automobile industry, especially the rapid increase in the family car and auto parts export volume increases, automotive aluminum castings will have a great growth. China's total casting output in 2003 was 19.87 million t, of which 1.17 million t of aluminum-magnesium alloy, accounting for 5.8% of the total output. Toyota hopes that in the past two years the aluminum cylinder block from the current 35% to 50%. Nissan plans to use aluminum for 70% of the cylinder blocks of gasoline-powered sedans before 2010, and nearly 100% of the cylinder heads and transmission cases are made of aluminum. Honda Motor Company as early as 1994, the gasoline engine cylinder block all replaced with aluminum cylinder block. Aluminum alloy cylinder block, cylinder head and other non-ferrous metals are used more die casting (including vacuum die casting), low-pressure die casting, high-pressure die casting, metal-type gravity casting as well as the promising semi-solid die casting forming technology. Dongfeng honda engine company, dongfeng nissan engine branch aluminum die casting workshop using 2500t die casting machine production of aluminum cylinder block, and realize the localization. Aluminum cylinder head forming process mainly has two kinds, one is to Europe and the United States as the representative of the gravity casting forming process, Shanghai Pilbaoge, Nanjing Tekashi and other companies choose the Italian Fata company gravity casting machine production of aluminum cylinder head; The second is to Japan and South Korea as the representative of the low-pressure casting forming process, the dongfeng nissan engine branch aluminum die casting workshop, guangdong zhaoqing casting company, tianjin toyota foundry company are used in japan, such as the new east company's low-pressure casting machine production of aluminum cylinder head. Low-pressure casting machine production of aluminum cylinder head.
4.6 magnesium alloy forming technology
Magnesium alloy specific strength and high specific stiffness i better than steel and aluminum alloys, much larger than engineering plastics. Magnesium alloy also has high temperature resistance, corrosion resistance and creep resistance. Magnesium is currently used in the automotive industry the lightest metal, it is lighter than aluminum 1/3, lighter than steel 3/4, lighter than non-metallic plastics 1/5. therefore, magnesium alloy is the ideal material to reduce the quality of the automobile, magnesium alloy die casting can replace some of the complex structural parts, such as the instrument panel skeleton of dozens of steel parts by stamping, welding and become, a quality of about 10 kg, if the change to the magnesium alloy die casting, die-casting, the quality of only 4 kg. Forming, the quality is only 4 kg, the production cost is greatly reduced. Along with, magnesium alloy new material development and processing technology improvement, magnesium alloy in the automobile market will continue to broaden and continue to grow steadily. Magnesium alloy production to die casting-based molding technology, has been the focus of attention of the automotive industry, magnesium alloy die casting demand accounted for 80% of the demand for magnesium alloy in the automotive industry, automotive magnesium alloy die casting materials, in addition to meet the performance of high temperature resistance and creep resistance, but also must give full consideration to the design, processing, surface treatment, and the related die casting molding process. As die casting magnesium alloy has castability outstanding advantage. Casting wall thickness can reach 1 ~ 1.5 mm, draw mold slope 1 ° - 2 ° Although the focus of magnesium alloy casting is still on pressure die casting, but still face the performance and cost of die casting magnesium alloy problem. Therefore, a new process - semi-solid processing technology of magnesium alloys appeared. The technology process has been mainly used in the production of integrated magnesium, aluminum alloy castings. Foreign magnesium alloy in the automobile application prospects are broad, Europe and the United States domestic magnesium alloy die casting production to the annual rate of 25% growth. Audi A6 sedan transmission shell for magnesium alloy die casting, the quality of only 14.2 kg, Audi company will be the first magnesium castings for the instrument panel skeleton. Ford motor company with magnesium alloy production seat skeleton, instead of steel skeleton, so that the quality of the seat from 4 kg to 1 kg. Ford is studying the production of cylinder block with magnesium alloy. Japan's mitsubishi company and the australian ministry of science and technology cooperation to develop a kind of ultra-light quality of magnesium alloy engine mass is only 7.5 kg. BMW inline six-cylinder magnesium alloy cylinder block has been mass production. American general production of magnesium die casting intake manifold. Renault has produced magnesium alloy wheel castings. Dongfeng automobile foundry has mass production of magnesium alloy die castings, at present, dongfeng automobile company and faw casting company is developing to undertake the national ministry of science and technology key science and technology projects, such as transmission shell, gear room cover, valve room cover, steering wheel skeleton magnesium alloy die castings. Shanghai qiantong automobile accessories limited company took the lead in the production of magnesium alloy transmission shell die castings for cars. In recent years, the country has also established a number of large foreign-funded magnesium die-casting enterprises, such as Shanghai magnesium magnesium, Suzhou GF and other companies.
4.7 Semi-solid die-casting molding technology
Semi-solid technology originated in the United States, in the United States this technology has been basically mature and in the global leading position. This technology is called the 21st century the most promising material forming technology. alumax company took the lead in this technology into productivity, the production of aluminum alloy automotive brake master cylinder body blank size close to the part size, processing accounted for the casting of 13% of the quality of the same metal casting of the machining allowance accounted for the casting of 40% of the quality of the 20 century, since the 1980s, the European and other countries in the semisolid application made a A lot of research and application work. Italy is one of the earliest countries to apply semi-solid machining technology, Stampal-saa company with the technology for Ford Motor Company to produce gear box cover and rocker parts. At present, Japan's Speed Star Wheel Company has used this technology to produce aluminum alloy wheel castings weighing about 5 kg. China's semi-solid metal processing technology started late, began in the late 1970s. Compared with foreign countries, China's research in the field of semi-solid metal forming technology is still very backward. As far as the current research status in China is concerned, the development trend of this technology is that the metal touch forming technology has basically matured, while the development of rheological forming technology is slow. Therefore, in the future, more researchers will turn to the theory and application of rheological forming research. At present, semi-solid metal forming technology is mainly applied to aluminum, magnesium, lead and other low melting point metal forming, less application to high melting point ferrous metals, which is the direction of future research. At present, scholars at home and abroad have developed a semi-solid forming process numerical simulation software, but there are still shortcomings, the need to strengthen the application of computer technology.
4.8 cast iron materials
(1) thin-walled high-strength gray cast iron parts technology
China's total casting output in 2003 was 19.87 million tons, of which 10.49 million tons of gray cast iron parts, accounting for 53% of the total output. Gray cast iron parts in a large number of automotive applications is due to the material has a lower cost and good casting performance advantages. With the automotive technology lightweight requirements, gray cast iron growth and development will be affected to some extent, so its development trend is to strengthen the thin-walled high-strength cylinder block, cylinder head casting technology development and application. Thin-walled high-strength cylinder block, cylinder head casting technology is the difficulty of making the thinnest wall thickness of only 3-5 mm of the body section hardness difference <40HBS, the organization is fine and uniform. Sedan cylinder block and high-power diesel cylinder block, cylinder head castings of hardness, pearlite amount, carbide content, graphite morphology and other metallurgical organization of the high technical requirements. Such as high-power diesel engine cylinder block, cylinder head requirements for the body hardness of 1 70 ~ 228 HBS, 179 ~ 235HBS, strength and size requirements, surface roughness Ra<50 pm. gray cast iron material grades in the continuous improvement of HT300 has been used in the production of cylinder block, cylinder head, some products may be up to HT350. the domestic automobile foundry in the material process, melting process, molding process, graphite morphology and other metallurgical organization of high technical requirements. The domestic automobile foundry in the material process, melting process, molding process, core making process, mold manufacturing process, testing technology and other aspects of a great deal of work, and will be applied to these technologies in the car cylinder block and high-power diesel engine cylinder block, cylinder head and other castings.
(2) peristaltic cast iron technology
Peristaltic cast iron has the strength of ductile iron, gray cast iron compared to similar vibration, thermal conductivity and casting performance. Have good plasticity and thermal fatigue performance, can solve the problem of high-power cylinder head thermal fatigue cracking. Ferritic body peristaltic iron working temperature can reach 700 ℃; high silicon molybdenum peristaltic iron working temperature up to 870 ℃. Peristaltic cast iron will not replace ductile cast iron, nor will it replace gray cast iron. Peristaltic cast iron widely used in the huge potential market is the automotive industry, its main products are engine cylinder block and high-power diesel engine cylinder head. With the automobile lightweight and than the power (power / displacement) to improve the cylinder block and cylinder head working temperature is getting higher and higher, many parts of the working temperature of more than 200 ℃, at this temperature, the strength of aluminum alloy has fallen dramatically, and peristaltic iron has a great advantage. It will become the only advanced automotive engine materials that can meet the technical, environmental and performance requirements. Because peristaltic iron is characterized by high strength and thin walls, it can reduce mass. Opel's research shows that the same power engine cylinder block if the use of peristaltic iron, wall thickness can be reduced from the original 7 mm to 3 mm, casting quality can be reduced by 25%.
Peristaltic cast iron creep processing range is very narrow, the core technology is to use the appropriate production technology and the corresponding creep agent. Foreign BMW Motor Company, Daimler Chrysler Automotive, Duff & Company's engine cylinder block with peristaltic cast iron production. Ford (Ford) and Sinter (Sinter) cooperation, in 1999 in Brazil to produce 100,000 pieces of cylinder block per year. Germany's Halberg foundry, from 1,991 years for Audi to produce V8 peristaltic iron cylinder block, wall thickness of 3.5 mm, 147 kW cylinder block quality of only 74 kg. Dongfeng Motor Company foundry, in May 1,984 formally in the production of peristaltic cast iron exhaust on the assembly line, to become China's first in the production of peristaltic iron cast iron on the assembly line of the factory. In the early 1990s, and has successfully developed a peristaltic iron transmission housing and Shanghai Volkswagen Santana car exhaust. FAW Casting Company Wuxi Diesel Branch in the 1980s {BANNED} began mass production of peristaltic iron cylinder head. Shanghai St. Germain Casting Co., Ltd. for the production of Shanghai Volkswagen silicon molybdenum peristaltic iron exhaust.
(3) ductile iron technology
Ductile iron due to high strength, high toughness and low price. So there is still a lot of development in the automotive market. China's ductile iron production is also continuing to grow, the output in 2003 accounted for 24% of the total output, while the development of many ductile iron standards, research and development to adapt to the mass production of ductile iron in the assembly line of advanced technology, such as shaking the package, pneumatic desulphurization, within the type, the cover packet spheroidization, a variety of instantaneous breeding, audio, ultrasound, thermal analysis and detection technology. Currently, in industrially developed countries, the production of ductile iron parts in the casting of the total output of more than 25%, the United States in 2003 ductile iron production accounted for 33% of the total output of castings. The development trend of ductile iron product technology process in the automobile casting industry has the following four aspects.
One is cast pearlite, high-strength (QT700-2, QT740-3) of the truck and car crankshaft, cast ferritic, high elongation (QT400-18, QT440-10) of the automobile exhaust and bridge chassis type castings. Higher grades QT800-2, QT900-2 are also being developed and applied.
The second is the security class castings, cast production of car steering knuckle material and technical conditions are very strict, requiring castings zero defects, 100% non-destructive testing, there are currently three automatic testing technology for production.
Third, heat-resistant ductile iron parts, namely, high silica-molybdenum, silica-molybdenum, high-nickel ductile iron, the material produced by the exhaust pipe parts, there is a very good high-temperature resistance: the current domestic automobile company foundry has produced a cast silica-molybdenum ferrite ductile iron exhaust pipe parts.
Four is Aube ductile iron, the material's unique material properties become the focus of the foundry industry, which is a very potential for the development and application of materials, mainly for the production of crankshafts and other products.
In addition to the above, automotive foundries have produced cast ductile iron cold-excited camshafts.
4.9 Casting process computer application technology
With the rapid development of automotive casting technology, in order to shorten the casting production preparation cycle and reduce the risk of new product development, the use of rapid prototyping technology, computer simulation, simulation, three-dimensional modeling, CNC technology is becoming more and more widely used. The application of rapid prototyping technology in casting production has developed greatly. It is in addition to the application of the development of new products for trial production of molds and wax molds for investment casting, but also can be made of phenolic resin shell type, shell core, can be used directly to assemble into a sand mold. Foreign companies in the receipt of customers to provide three-dimensional CAD data, according to different product structure, the fastest time in 3 weeks to provide customers with castings. Simulation of the molding process is becoming one of the cutting-edge areas of international automotive casting concerns, Tsinghua University, Japan's New East Industries, such as the simulation of the wet sand compacting process. It is worth noting that Germany's RWTH Aachen University, Tsinghua University is the core-shooting process of data simulation. Domestic automobile casting industry CAD-CAM-CAE integrated design and development has been fully applied, especially CAE solidification simulation of virtual technology, the application of Magma, China casting software for new products casting filling, solidification of the temperature field and flow field simulation and analysis of processing, prediction and analysis of casting defects. Casting expert system has been further applied, such as sand quality management, casting defects analysis, die-casting process parameters design and defect diagnosis.
4.10 casting inspection technology
Casting inspection technology is the key means to ensure the quality of castings. Casting size inspection, there are commonly used inspection fixtures, cardboard, there are special testing fixtures. For the cylinder block, cylinder head and other complex parts, the use of three-coordinate meter automatic measurement of casting size and ultrasonic instrument to detect the wall thickness of the casting. The application of non-destructive testing technology is becoming more and more widespread, for important parts often use fluorescent magnetic particle detection of surface cracks; the use of ultrasonic or audio detection of ductile iron spheroidal rate; the use of eddy current to detect the matrix organization of the casting (pearlite content). In order to meet the inspection requirements of important parts, the above three inspection instruments can be combined into an automatic inspection line. Using X-ray to detect shrinkage and shrinkage defects inside the castings, Japan Honda uses X-ray flaw detection for 100% of ductile iron steering knuckle castings: using industrial endoscopy to detect the quality of the inner cavity of the castings, airtight leakage detection. Chemical composition testing, vacuum direct reading spectrometer and carbon and sulfur detector in the pre-furnace, after the furnace molten iron quality has been widely used. Trace elements and gas elements N, O, H analysis has been attached importance to: rapid thermal analysis before the furnace has been popularized and used to quickly forecast the carbon and silicon equivalent of cast iron, the effect of gestation, matrix organization and mechanical properties.
4.11 Green casting technology
"Green casting" is to make casting products from design, manufacturing, packaging, transportation, use to end-of-life treatment of the entire product life cycle, the least negative impact on the environment, the highest resource efficiency. Casting industry has always been considered a high energy consumption, high pollution industry, to continue to develop new energy-saving, clean, low emissions, low pollution casting materials to be put into production use. For resin, to find ways to reduce the content of free formaldehyde and free phenol and other harmful substances; gradually increase the application of cold core box technology to reduce the impact of resin sand on the environment, to achieve emission standards: reduce the curing temperature of hot core box, shell core sand, core process from the hot core box method to the warm core box method, in order to save energy. China's automobile foundries consume nearly ten million tons of new sand each year, the pollution of old sand emissions, as well as a large number of new sand resource depletion, overburdened, so the regenerative use of old sand technology is imperative. Waste sand emissions in advanced industrial countries have been reduced to less than 10%, and the recycling technology of old sand has been widely used in Europe, Japan and other regions. Harbin Dong'an Automobile Engine Company introduced Italian thermal regeneration equipment, which has been applied in production. FAW Casting Company introduced Japanese technology, thermal regeneration and mechanical regeneration combined to deal with core sand and type, core sand mixed sand has been applied in production. At present, Dongfeng Motor Company is also accelerating the old sand regeneration technology development and application work. Increase the use of scrap steel and furnace materials to reduce the consumption of new iron and aluminum resources. Automobile casting industry for the circular economy casting technology, to the circular economy 3R for the industry guidelines, that is, to reduce (Reduce), reuse (Reuse), recycle (Recycle) to carry out the work.
5. Problems faced by China's automobile casting industry
China's automobile casting industry after the "planned economy" into the "market economy" in the process of experiencing the start, stability, development, maturity of the four phases, and has made the world The world's attention. However, we must soberly recognize the historical importance of the automobile casting industry and the reality of the gap with the developed countries, firmly grasp the development trend of casting technology at home and abroad, the appropriate time to adopt advanced casting technology, the implementation of the sustainable development strategy of the foundry industry, the current automobile casting industry, the main problems are as follows.
The average size of casting enterprises and economic scale and abroad than there is a large gap. Although China's casting production has been ranked first in the world for five consecutive years, there are a number of high production of large and medium-sized enterprises, but most of the casting enterprise scale is small. On the whole casting industry. The status quo is still scattered (foundry points up to more than 20,000), more employees (up to 1.2 million people), low efficiency (factory castings only 500 t / year), only equivalent to the United States, Japan, Germany, France, Italy and other industrially developed countries, 1/1/9-1/4.
The casting enterprise overall level of technology and equipment and foreign countries than there is a large gap. The gap between the level of technology and equipment between enterprises is large, a small number of enterprises of individual production workshop level of technology and equipment, has been close to or reached the international advanced level, but the overall level is not high. According to statistics, China has imported from abroad more than 210 automatic molding line, there are more than 250 domestic molding production line, these production lines are mainly concentrated in the automotive internal combustion engine parts of the mass production enterprises.