(1) Typical Transnational Industry
As the equipment of all walks of life, as a means of transportation, and as a durable consumer product of the family, the automobile has a history of only one hundred years, but the world now owns more than 600 million automobiles, with an average of less than 10 people having a car. The United States and other developed countries, but also by the automobile wheel rapid development. The rapid advancement of information technology has brought the world into the information age, more closely linked to each other, the earth seems much smaller, economic globalization is no longer a scholars' prophecy, but the reality of the WTO to give the globalization of economic exchanges to the prevailing "game" planning, more and more countries feel that the state of their own economies, and the global economy is closely related to the prosperity of the degree.
A few years ago, the Asian financial crisis affected most countries. The U.S. economic boom of several years in a row has led to many countries to take advantage of the development of the momentum, and now the U.S. economic growth rate has dropped significantly, and the negative impact will also be global.
As a typical multinational industry, automobile manufacturing plays an important role in the formation of economic globalization. The automobile industry is not only a large-scale overseas investment, in recent years is the transnational mergers and acquisitions, strong combination, are common, have set up transnational corporations, such as the sensational global "Daimler ---- Chrysler" transnational corporations is a few years ago came into being. The purpose of the formation of multinational corporations is to realize the resources *** enjoy, complementary advantages and low-cost scale effect. When the U.S. economy into recession, located across the ocean in Germany, Daimler - Chrysler multinational headquarters also had to announce that the next three years, layoffs 26,000 people, multinational corporations are the first transnational impact as a matter of course. Obviously, as a typical transnational industry, the organization of global automobile manufacturing is undergoing fundamental changes. In line with the pace of globalization of automobile manufacturing and sales, the global procurement system for automobile parts and components is also developing further. In the face of the new competitive situation formed by the growing trade and investment liberalization, it is difficult to develop a country's automobile industry in a closed state without separating from the global automobile industry's big pattern of division of labor. The introduction of technology and unremitting efforts at localization can play a role in replacing imports when the domestic market is well protected. However, due to the advantages of economies of scale on a global scale, they cannot be realized in the internal market of any one country. Therefore, as a typical transnational industry, the automobile industry of each country should dissolve into the division of labor system of the global automobile industry as much as possible, and continuously improve its international competitiveness by participating in global competition.
(2) China's automobile industry in the spotlight
Whether from the trend of economic globalization, or from the automobile industry is a typical multinational industry, the survival and development of China's automobile industry, with the domestic and foreign automobile demand market and the direction of the world's automobile development is inextricably linked.
Whether it is the United States, or the European Union, in the negotiations on China's accession to the WTO, one of the main focuses of the debate with China is related to the terms of the automobile. As the large-scale reorganization of the automotive industry, mergers and acquisitions continue, it is expected that by 2005 will form a pattern of 5-6 multinational conglomerates to control the global automotive industry. Therefore, the developed countries regard the only remaining potential market for the world's largest automobile, China, as a must for their global automobile development strategy, and pay much attention to China's automobile industry, and they pursue their competitive strategies through direct investment and international trade.
China's auto manufacturing industry started with trucks. The scale of medium- and heavy-duty trucks has ranked among the top few in the world, and is more suitable for China's national needs. The car started late, and the scale is not large, multinational companies are optimistic about the world's largest potential auto market in China, referring to China's car market, especially the family car market, the comparative advantage of China's automobile industry trucks, sedans, car's huge market potential, all sectors of the domestic sector is extremely concerned about the concern, attention.
The automotive industry has a large degree of industrial relevance, a strong driving force on the economy, and a ripple effect on the entire national economy and guidance, and it is inevitable that all parties pay attention to it.
China's truck manufacturing industry has an economic scale, there is a more complete domestic marketing system, as long as adhere to the development of independent open, China's FAW, FAW has the potential to become Asia's number one, number two truck manufacturers, and the car industry has a great potential for development, according to the analysis of China's annual income of 8-10 million yuan or more, the family's need for a car will increase significantly. At present, the country's annual income of 90,000 yuan or more families have reached about 7 million households, in 2005 will reach more than 40 million households. By then, even if only 5% of the families buy cars, the demand for cars will reach 2 million units a year. Last year in the country's seven major cities for a sample survey, about 70% of the families said that the next five years have the intention to buy a car. 2000 China's total car sales of 2.08 million, of which only 610,000 cars, accounting for about 30% of the total sales of cars, while the developed countries of the total sales of cars. more than 70% of the car. The potential demand for cars in China is huge.
China's government formulated the tenth five-year plan, has been clearly set out: to develop economic cars, to support the key transformation of the automotive industry, to encourage cars to enter the family, to improve the level of automotive and key components manufacturing, to actively develop energy efficient, low emission vehicle engines and hybrid systems.
Of course, how to promote the potential huge market into a reality of the big market, to rely on long-term unremitting efforts, is currently vigorously regulate the automobile consumption environment and the use of the environment, and in order to meet the ever-changing diversified, personalized demand for sedans, car manufacturers are also developing development strategies and medium- and long-term planning, and to further expand the international strategic cooperation, accelerate the development of different cars to meet the different needs of the different users in China. The development of various kinds of cars to meet the different needs of users in China will be accelerated. Including trucks, cars and other passenger cars, commercial vehicles, including the entire Chinese automotive industry, after joining the WTO, no longer protected by the government extraordinarily, will be subjected to the automotive industry this transnational industry, fierce competition and large-scale reorganization of the test, and become a part of the global automotive industry, China's automotive industry to become a manufacturing link of the strongest is possible to do, and in the product development links and marketing to make great strides in the link is It will take a long time.
2. Overview of China's automotive foundry industry
1. Young industry
In general, as a foundry with thousands of years of foundry history, China's automotive foundry industry has only a history of 40 years, so young China's automotive foundry industry, basically in the planned economy established under the host plant's self-sustaining foundry. This is also due to the automobile industry itself is China's new infant industry, society as a whole can collaborate for the automobile industry supply capacity, level, at that time is extremely limited. Therefore, the automobile foundry that year's "big and full, small and full", is also a last resort. Automotive castings than the traditional industry castings complex, high quality requirements, supply faster beat, therefore, must be used with a certain level of higher productivity casting equipment, facilities, capital investment is also higher. However, due to the host plant, but not the host plant's main specialty, so the actual input can be arranged is very limited. Even if the introduction of certain foreign equipment, due to limited funds can only introduce part of the main equipment, but not the ability to introduce a full set of equipment, resulting in the casting plant than the same affiliated with the host plant machining, assembly and other specialized factories backward technical level, low productivity, often become a constraint on the host quot;bottleneck". After a difficult transition through the initial stage, China's automobile casting industry is facing its users - the automobile industry on the castings of the increasingly high requirements, facing the community on the casting industry more and more stringent requirements. In order to realize the sustainable development strategy, must make the car to achieve the goal of energy saving, environmental protection. Therefore, automobiles should strive to improve fuel economy and strictly control emissions. In order to achieve such a goal, reduce the weight of the car is an important measure, in order to make the car to reduce the weight of the car, it will require automotive castings must be lightweight, precise. Lightweight automotive castings, precision requirements, to China's automotive cast iron casting process level, equipment and mold level and casting raw and auxiliary materials to improve the level of the formation of a huge pressure. China's automotive aluminum casting, only in recent years with the rise of the car industry has just begun, automotive magnesium casting almost from scratch. See the pressure of China's automobile casting industry. On the other hand, society can no longer forgive the casting industry as a major energy consumer and polluter of the indulgence. The protection of resources, the protection of the environment has been everyone's **** knowledge. China's automobile foundry industry must take the road of high efficiency, energy saving, material saving, environmental protection, take the road of green casting, there is no choice. Young Chinese automobile casting industry has a long way to go.
2. Several typical automotive castings
(1) cylinder
The most important and complex castings on the car is located in the heart of the car - engine. In order to prevent the car has a "heart attack, the quality of the main castings on the engine is particularly important. Cylinder block is the largest and most complex castings on the engine, the thinnest wall thickness is often less than 3mm, most of the high-strength gray cast iron casting, there are also useful for creep castings, due to the progress of automotive lightweight, the use of aluminum alloys are also more and more foreign car manufacturers even began to consider the use of magnesium alloy casting cylinder block. Production of cylinder block casting method used for different materials, due to different conditions in various plants have a variety of options, including wet sand molding in the air impulse molding, static pressure molding, high-pressure multi-contact molding, no box extrusion molding, vibration pressure molding and so on. For cast aluminum cylinder block, the use of die-casting, low-pressure casting, foreign countries also use disappearance mold casting, extrusion casting (with aluminum-based composite materials for embedded cylinder sleeve), and semi-solid casting, etc., and the use of sand casting (such as DISA modeling process).
At present, the casting material for the cylinder, the most widely used is still wet sand molding, especially the emergence of static pressure or gas impulse molding of the air to compact, and embodies a lot of superiority - low energy consumption, low noise, less pollution, high efficiency, reliable operation. Recently, foreign equipment manufacturers on the molding machine and continuous improvement, has appeared in the air punch plus compaction, airflow gain air punch plus compaction, static pressure plus compaction, active multi-contact compaction, molding extrusion, compaction, and other improvements to make the hardness of the sand more uniform. With the development of high-power semiconductor components and computer, microelectronics technology, the use of electric servo system instead of the usual molding line used in the hydraulic, pneumatic drive, so that the molding line beat further accelerated, and greatly improve the reliability of the operation, and at the same time significantly simplify the hydraulic control system, so that the maintenance workload is also reduced accordingly. Moulding line adopts double-cylinder type sand dropping machine, it can make castings and pouring risers in the sand dropping at the same time to get pre-cleaned. Moulding line pouring often restricts the whole line of the opening rate, should adopt automatic pouring equipment. Some manufacturers use air pressure pouring package and contact pouring process, is conducive to saving iron, quality assurance and protection of sand box. Pouring process with the flow of pregnancy more, some use the type of pregnancy and filtration combined.
The cylinder block is the casting with the most sand core. In addition to the water jacket core is thin and complex, according to the different conditions of each factory, respectively, using cold core box core, hot core box core or shell core core, other sand core - including crankcase core, cylinder cylinder with the top of the core, the front, rear face core, etc. Most of the sand core using cold core box core, in order to ensure the dimensional accuracy and energy saving, the cold core box is becoming more and more widely used. Cold core box core making to ISOCURE triethylamine hardening method mostly (recently, the United States has developed a more advanced ISOMAX), SO2 method of hardening has its advantages. The warm core box core method is energy saving and environmental protection both advantages, strengthen the core unit sealing and ventilation is necessary. The development and application of non-toxic, non-polluting environmentally friendly resin binder is more important. In order to improve the quality of the inner surface of the casting and the cleanliness of the inner cavity, the sand core should be coated. Water-based paint instead of alcohol-based paint is conducive to anti-pollution. After coating, microwave drying is energy-saving and highly efficient. Key - core process, the use of sand core on the opening of the process holes, the second filling of sand curing, so that more than one sand core combination for a whole combination of sand core, and then the whole coating, drying, so that the casting dimensional accuracy can be greatly improved, the overall dimensional error can be <0.3mm. computer-controlled "core center" can make all the core making process automated. Cylinder block sand core is very much, in order to reduce the impact of the core sand on the performance of the sand and strengthen environmental protection, should vigorously implement the core sand regeneration and reuse, especially the use of thermal regeneration, can make the quartz sand by roasting phase change, high temperature expansion rate is greatly reduced, the use of such regeneration of the sand to make the core, than the new quartz sand to ensure that the quality of casting, regeneration of the sand used to reduce the cost of production.
Cylinder body molding sand, sand mixing equipment has a milling wheel type, pendulum wheel type, blade type sand mixer. Some manufacturers use double-disc milling wheel continuous sand mixer, some use counter-current rotor sand mixer, sand mixing efficiency are higher, while the installation of sand performance online control instrument to ensure the quality of sand mixing. In the sand system, there are still old sand magnetic separation equipment, sand crushing equipment and screening equipment and old sand cooling equipment to ensure the quality of old sand for reuse. At the same time on the new sand, coal powder, bentonite and other additive materials, accurate quantification, according to the process of determining the proportion of feed, and according to real-time control data at any time to adjust the amount of water, to ensure the performance of sand. There is also a closed-loop real-time control of the performance of the whole system sand or sand quality calculation online expert system control. It should be noted that the sand system has a large amount of sand turnover, strong inertia, the adjustment of sand performance should be judged by the trend, the use of predictive adjustment measures to ensure the stability of the quality of the sand system. For the sake of environmental protection, the comprehensive utilization of old sand regeneration and waste sand should be started.
For the cast iron cylinder, most of the smelting equipment used for the punch in the furnace - induction furnace duplex smelting, there are also induction furnace - induction furnace duplex smelting. The use of electric arc furnace as a holding furnace is decreasing, while the frequency induction furnace as a holding furnace is increasing. In order to save energy and environmental protection, the cupola should use water-cooled hot air dust removal cupola, hot air may improve the temperature and quality of molten iron and melting rate. With a high calorific value of casting coke instead of metallurgical coke is necessary to increase the temperature of molten iron, to ensure the quality of molten iron, and to improve the melting efficiency. The pre-purification treatment of furnace charge is necessary. The melting process control of the cupola can use microcomputer and other scattered control system, cupola melting molten iron testing using pyrometer, carbon equivalent detector and chemical composition of direct reading spectrometer and so on. Clean, long-life refractory materials are conducive to improving the life of the cupola lining and environmental protection. Comprehensive utilization of cupola smelting slag is conducive to reducing emissions pollution.
Cylinder block castings by removing the pouring riser, grinding all surfaces on the cleaning line, and then cleaned by the squirrel cage type shot blasting room. For more varieties of cylinder block is appropriate to use the clamping type high-efficiency shot blasting machine for shot blasting. Then manually finishing the cylinder one by one and blowing the water jacket cavity residues. After the size check, air tightness test, milling and positioning points and final inspection for paint or other rust treatment, become a qualified cylinder castings user requirements.
(2) Cylinder head
Cylinder head is also a complex and critical castings on the car, the engine's combustion chamber, air intake, exhaust port are located on the cylinder head. Cylinder head material can be high-strength gray cast iron or graphite cast iron, but the most widely used or aluminum alloy cylinder head, and magnesium alloy cylinder head in foreign countries also began to use. Cylinder head casting methods are more, such as: sand casting, metal-type gravity casting, low-pressure casting, foreign countries also include disappearing mold casting, die casting (using Douler sand core, etc.) and the emerging semi-solid casting.
Today, metal-type gravity casting aluminum cylinder head as an example. The shape of the cylinder head are formed by the metal mold, can be automatically controlled by the computer metal mold temperature, part of the cavity formed by the sand core, sand core manufacturing process and the aforementioned cylinder core process is basically the same, mainly core sand binder and core coating is different.
Aluminum alloy melting can be used reflector furnace, but oxidation, suction is serious, burn large, difficult to control the temperature, waste of energy, pollution of the environment. The use of induction furnace, aluminum water in the furnace tumbling is conducive to homogenization of the composition, but the induction furnace magnetic field on the thermometer has interference, induction furnace maintenance is more difficult. It is worthwhile to widely used is a continuous high-efficiency gas furnace, can realize the charge preheating, continuous melting, composition uniformity, temperature control precision, energy saving, suitable for mass production. Attention should be paid to the furnace charge to be clean, in addition to the general aluminum refining, densification treatment methods, can be used in aluminum alloy melt blowing comprehensive treatment device - so that the refining, densification, grain refinement in one step. The traditional pouring method of cylinder head is bottom injection type, which is convenient for the smooth filling of aluminum liquid. Nowadays, the top injection type is mostly used, which matches with the cooling system of the mold, and is more conducive to the formation of sequential solidification, thus significantly improving the denseness of the castings. The exhaust of the mold should be smooth during the pouring process, and automatic pouring is mostly adopted - including single machine type, double unit type and multi-unit in-line type. The multi-station rotary pouring machine is suitable for mass production, but the investment is large. Multi-unit rotary casting machine is less investment. When using long-lasting strontium densifier, it is more effective to use quantitative heat preservation casting furnace. Aluminum liquid quality on-site inspection using hydrogen meter and direct reading spectrometer and so on. The maintenance of metal mold is very important, can be regularly used to spray small particles of dry ice to remove the mold scale, this method is simple and easy to carry out, does not pollute the environment.
After pouring the aluminum cylinder head castings in the clean-up line saw off the pouring, risers, milling plane, after the leakage test, often by roughing and milling positioning points before sending to the user.
The use of low-pressure casting aluminum cylinder head manufacturers are also more, and the electromagnetic pump low-pressure casting process, can improve the metallurgical organization and mechanical properties of the casting material.
(3) gearbox shell
Truck gearbox shell material is mostly gray cast iron, also useful for creep cast iron. Commonly used sand casting. The car gearbox shell, is a typical large, complex thin-walled shell castings, the material is mostly aluminum alloy, magnesium alloy is increasing, generally use die casting process. In order to improve the quality of die casting, can be used in low-speed pressure filling die casting, double compression injection punch die casting, vacuum die casting, oxygen die casting and so on. Die casting production in the spray coating, pouring and take pieces are automatic, and there are calibration die casting machine and casting molding condition of the on-line detection device.
The melting and refining of the aluminum alloy used for the gearbox shell is basically the same as that of the aluminum cylinder head described earlier. Pressure injection parameters on the die casting porosity effect is quite large, must be reasonably adjusted. The use of closed injection end time control system. Can realize no flying edge die casting. Die casting quality testing can be used X-ray flaw detection, ultrasonic testing. Die casting mold material ductility and toughness to prevent the die casting mold thermal cracking and cracking is very important. Improve the working condition of the mold good operation and maintenance will help to extend the service life of the die casting mold. Foreign recently developed semi-solid magnesium alloy injection molding technology, can make the magnesium alloy filling smooth, not turbulent flow, prevent hydrogen involved, avoid alloy - casting between reaction, is injection molding and die casting molding composite process.
(4) intake manifold
intake manifold irregular variable cross-section of the intake tract cavity shape has been the automotive casting industry problems. And in recent years, the development of engine electronic injection technology, so that the intake manifold is more complex. Therefore, it is only natural that many manufacturers choose the vanishing mold process as the casting method for intake manifolds. The intake manifold for trucks is mostly gray cast iron, commonly used in sand casting. The car intake manifold material for aluminum alloy, the casting methods used include vanishing mold casting, metal-type gravity casting.
The use of vanishing mold casting aluminum intake manifold, its melting and refining process and the cylinder head of the aforementioned aluminum alloy melting and refining the same. To use small particle size EPS beads to ensure pre-foaming and molding. The gluing of the molding die piece must be carried out according to the provisions of the process. The coating process of the assembled disappearing mold piece is very important to control the performance of the coating and the thickness of the coating, which is vital to the exclusion of the pyrolysis products of the mold piece during pouring, the filling speed of the aluminum liquid and the quality of the disappearing mold castings. After the coating is dried, the mold is filled with dry sand and can be poured after vibration. The obtained disappearing mold intake manifold castings after eliminating the risers, but also should do leakage check, if any leakage, can be in accordance with the contract provisions of the soak seepage to make up for the leakage.
(5) exhaust manifold
Because of the high exhaust temperature of the automobile engine, therefore, the exhaust manifold material is basically gray cast iron, ductile iron or or creep cast iron. Exhaust manifold is also a thin-walled castings of more complex shape. Most of the sand casting, there is also the use of disappearance mold casting. Today to ductile iron material sand casting exhaust manifold as an example. Its modeling and core making process and the previous said cylinder body modeling, core making process is basically the same.
In terms of ductile iron melting, many manufacturers use cupola - induction furnace duplex melting. In order to ensure the quality of ductile iron, in addition to the use of pig iron for ductile iron, the use of casting coke, should also be desulfurization of the cupola molten iron, more than nitrogen porous plug bottom blowing desulfurization package continuous desulfurization, the use of moisture-resistant, explosion-proof granular desulfurization agent. Spheroidization treatment is mostly cover package method, recently has been the metallurgical industry core wire method introduced into the foundry industry as a spheroidization treatment process. This is beneficial to improve the absorption rate of spheroidized alloy, stabilize the quality of spheroidization, reduce costs and reduce environmental pollution. Inoculation mode is to follow the flow of the majority of inoculation, but also the use of in-type spheroidization and in-type inoculation, and the use of bead-like spheroidization, can extend the spheroidization of the time of failure, and can be supplemented at any time the spheroidization to ensure that the spheroidization of the molten iron state. Foreign countries also use desulfurization - spheroidization - gestation of a new process, can reduce the consumption of magnesium and gestation, improve the spheroidization rate, energy saving. Carbon equivalent test before the furnace, rapid carbon, sulfur determination and rapid metallurgical analysis is very important to control the quality of ductile iron iron.
The exhaust manifold is a cast ductile iron part without heat treatment, the detection of spheroidization rate of ductile iron castings, can use ultrasonic method.
As peristaltic cast iron has good heat fatigue resistance, it is very suitable for the production of exhaust manifolds. Strict chemical composition control and good peristaltic agent is the key to stable production of peristaltic iron castings.
(6) crankshaft, camshaft
By the shaft, camshaft is a typical automotive shaft castings, is both toughness, fatigue resistance, but also required in the friction parts of the surface of the wear-resistant high-speed rotary movement of the thick section of the automotive castings. The material used is mostly ductile iron. Including Aube ductile iron. Camshaft material sometimes also use alloy cast iron, cold cast iron or alloy steel. Modeling methods used, in addition to a variety of sand casting methods, the use of shell (including iron over sand) casting a lot. There is also the use of self-hardening sand molding and disappearance mold casting.
(7) piston
The top of the piston is part of the combustion chamber of the engine, the cylindrical surface of the piston through the piston ring close to the cylinder cylinder wall to do high-speed reciprocating motion. Piston is the key automotive castings to form the engine power. Its material is aluminum alloy, including fiber-reinforced composite aluminum alloy. Casting methods include metal-type gravity casting, low-pressure casting, extrusion casting and so on.
(8) wheel hub
Hub is a rotary motion class of automotive castings, car wheel hub material for aluminum alloy. There are several casting methods - low-pressure casting, extrusion casting (including rotary vertical extrusion), metal-type gravity casting, differential pressure casting.
Of course, there are many types of castings on the car, not to mention. In recent years, many kinds of foreign car castings began to use magnesium alloy to adapt to the requirements of automotive lightweight. These magnesium alloy castings include: clutch housing, transmission housing, transmission top cover, hood cover, steering wheel skeleton, seat skeleton, instrument panel skeleton, inner door panels, rims, steering bracket, brake bracket, valve bracket, etc., and even cylinder head and cylinder block.
3. Aluminum and magnesium casting industry in the ascendant