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First, the status quo of domestic automotive suspension spring industry
1. Industry Profile
There are more than 160 domestic automobile suspension spring production enterprises, which are located throughout the country. There are about 80 professional production companies (with a production scale of over 0.8 million tons). The automobile suspension spring industry is affiliated to the China National Automobile Industry Association Leaf Spring Committee. Nearly 50 domestic companies have joined the China Automotive Leaf Spring Committee. The quality of the raw materials used by the participating units is good, the product reputation is high, and the vicious market competition is not conducted. The product quality level is It has reached the level of the advanced countries of the 1990s. Since the domestic spring industry is basically developed from small workshops, there are still more than 80 local enterprises with production scale below 5,000 tons. Due to the relatively small scale of production and relatively weak ability to resist risks, such production enterprises are generally It will not last long.
There are too many and chaotic phenomena in the production enterprises of the suspension spring industry. Among them, only a few companies have truly formed large-scale and large-volume production. Most of them still remain at the level of simple production processes. The higher product costs make it difficult to participate in international market competition. . There are only four domestic enterprises capable of producing high-grade automobile steel plate suspension springs: FAW Group Liaoyang Automobile Spring Factory, Dongfeng Automobile Suspension Spring Co., Ltd., Chongqing Hongyan Automobile Spring Factory, and Shandong Leaf Spring Factory, which have a variety of laminated springs, Gradient stiffness springs, small pieces of variable leaf springs, and double curvature radius and straight sections of automotive leaf springs. There are only three domestic manufacturers that can simultaneously produce passenger cars, trucks, and car suspension springs: FAW Group Liaoyang Automobile Spring Factory, Dongfeng Automobile Suspension Spring Co., Ltd. and Shandong Leaf Spring Factory.
2. Quality requirements of suspension springs for automobiles
Suspension springs are subjected to high-frequency reciprocating compression motion during driving of the vehicle, which plays a role of cushioning and shock absorption. The quality of the suspension spring plays a crucial role in the stability and safety of the vehicle. The automobile suspension springs produced by professional and regular enterprises are smooth, standardized, and have a high level of spray painting technology. The performance requirements of suspension springs for passenger cars and passenger cars are high to achieve features such as reduced noise, high speed, low vibration, improved comfort, good elasticity, and good stability; Heavy-duty and ultra-heavy duty trucks require high-strength suspension springs. The technical development trend of the suspension spring is generally lightweight (high stress) and high reliability. The design stress of the suspension spring is generally required to be greater than 1100 MPa, and the high one can reach 1200 MPa.
3. Steel plate suspension spring market demand
At present, domestic steel suspension springs have all been domestically produced. The market for the steel plate suspension spring industry is mainly the domestic market, and exports account for a very small proportion of sales, which is less than 1%. During the period of 95 to 96 years, there was a small amount of domestic steel leaf spring plants that were exported to Italy, the United States, Taiwan, India, France, and other countries. Among them, the Dongfeng export steel plate suspension spring is exempt from inspection. The domestic export leaf springs are all small leaf springs less than 1t. They are used for small trucks such as foreign pickup trucks. The prices are low, the technical content is not high, and the added value is low. Therefore, the domestic leaf springs are basically not exported.
The domestic suspension spring industry has developed rapidly with the development of the automobile industry in the late 1980s and early 1990s. By 2004, the domestic automobile production volume has reached 5.07 million vehicles, roughly estimating the annual demand for suspension springs in the domestic automobile industry. With 4.5 million pieces, each major spring supporting plant has also expanded its own production capacity according to the needs of users. The current production capacity of suspension springs is in excess of demand due to market demand.
The rapid development of the automobile industry has an extremely significant role in promoting the development of spring products and technological advancement. It is expected that by the middle of 2010, the annual demand for suspension springs in the domestic automobile industry will be about 8 million pieces.
4. Suspension spring industry production equipment level
Due to the particularity of the suspension spring industry, the main processing equipment of the suspension spring industry is basically non-standard equipment, such as coil spring machines, variable cross-section spring-rolling machines, forming machines, shot blasting machines, etc. There are only a few specialized manufacturers of such equipment. With production capacity. Western industrialized countries have strong industrial bases, and equipment manufacturers have a fairly high level of manufacturing and technology. However, domestic domestic equipment has lower processing accuracy, lower production efficiency, low automation, poor reliability, and aging models compared to imported equipment. . So now the advanced manufacturing equipment in the suspension spring industry is generally imported from abroad, such as variable cross-section, high-strength rolling spring machine. The main problems in imported equipment are high prices, maintenance difficulties, and long supply cycle of spare parts.
After the development and construction of the automotive industry in recent years, at present, there are some companies that produce suspension spring equipment in China. Through technological transformation, equipment investment, or foreign investment, the equipment accuracy and production efficiency have approached the level of imported equipment.
5. Suspension Spring Industry Product Development Level
Since the suspension spring type product is not an end product, it is a component belonging to other products, and it has a great dependence on the main plant. In the past, it was basically the main plant responsible for the suspension spring design. The suspension spring enterprises processed according to the plan. Now, some OEMs need the part manufacturers to jointly participate in product design and development. However, overall new product development is slow, and there is a lack of system management. Theoretical support.
Domestic development of new products and new processes is lagging behind, such as air suspension springs, etc. In terms of production equipment, automated on-line detection methods, the display of test result data, automatic mathematical statistics, and automatic feedback adjustment functions have been commonly used abroad. Automatic pressure sorting and other control means; 100% automatic detection of suspension spring dimensions, such as height, outside diameter, number of turns, load and flaw detection, which not only improves production efficiency, reduces scrap rate and rework rate, but also makes Product quality reliability and stability are guaranteed. Domestic air suspension spring products are now in the experimental stage.
Second, the use of steel suspension springs
1. Total spring steel used for suspension springs
The use of suspension springs in the automotive industry is divided into leaf springs and springs (also called spiral suspension springs).
The use of round springs for passenger cars, the use of steel diameter specifications for ? 9 ~ 16mm, a variety of cold-drawn round steel wire; In addition, some micro-car, van suspension springs, motorcycle shock absorber springs also use a round spring.
Light steel trucks, medium and heavy-duty vehicles, and passenger cars use leaf springs with dimensions of 6 to 30×50 to 140 mm and spring flat steel. Trucks generally use equal-section leaf springs, heavy-duty trucks use equal-section springs, and rear springs use variable-section leaf springs. Passenger cars generally use variable-section leaf springs. It is difficult to produce variable cross-sections, and only Dongfeng has introduced the British equipment with production capacity.
The development of the automobile industry will determine the use of leaf springs and round springs. According to statistics, at the end of 2004, the production of suspension springs for nearly 50 companies was about 500,000 tons, which was about 550,000 tons equivalent to spring steel, which accounted for 90% of the country's total usage. Therefore, the total demand for spring suspension of springs for national automobile suspension is about It is 600,000 tons, of which spring flat steel demand is about 560,000 tons, spring steel wire is about 40,000 tons.
2. Suspension spring using steel unit consumption
According to Dongfeng Automobile Suspension Spring Co., Ltd., the weight of the leaf spring of the front axle of a 5-ton truck (140 models) is approximately 50kg, the weight of the rear axle leaf spring is approximately 50-60kg, and the secondary bridge (placed on the rear axle). The weight of the leaf spring is about 70-80kg. In addition, the utilization rate of steel is calculated at 90%. A 5-ton truck needs 200-300kg of leaf spring.
The weight of the leaf spring of the front axle of an 8-ton truck (153 models) is approximately 90kg, the weight of the leaf spring of the rear axle is approximately 90-100kg, the weight of the spring of the secondary bridge is approximately 70-80kg, and the utilization rate of steel of 90% is also calculated. A total of 5 tons of trucks needs about 300kg of leaf springs.
A 13-ton heavy-duty truck requires approximately 400kg of leaf spring per vehicle.
Passenger cars use four suspension springs as an example. Each vehicle needs 200 to 300 kg of leaf springs on average.
The car uses 4 suspension springs (2 front and rear) as an example. Each car needs about 15kg of spring steel wire on average.
3. Suspension springs use steel grades, specifications and requirements
(1) Spring flat steel
Light steel trucks, medium and heavy-duty vehicles and passenger cars use leaf springs. The use of sub-steels is as follows:
60Si2Mn stands for specifications of: 10 × 60 (65, 75, 90, 100) mm, 11 × 60 (70, 75) mm, and the specification of the spring square steel is 18 × 18mm. The annual consumption accounts for about 35% of the total.
The specifications of 55SiMnB spring flat steel are: 10×75mm, 11×70 (90) mm, 12×70mm, 12×90mm, 13×70mm, 13×90mm, 17×70mm, and the specification of double-groove spring flat steel is 10×75mm The annual consumption accounts for about 35% of the total.
50CrVA use specifications 12×90mm, annual consumption accounts for about 30% of the total.
In addition, the use of less steel 65Mn, on behalf of the specifications for the 10 × 75mm, 35CrMnSi representative specifications for the 10 × 75mm, 60CrMnA on behalf of the specifications of 12 × 60mm.
The list of suspension spring specifications for typical automotive use is as follows.
Table Typical suspension spring specifications for automobiles
Serial number Automobile company name Product name Material specification (mm) Applicable models
1 Dongfeng series vice spring assembly 8×75 EQ1030 to strengthen agricultural vehicles
2 Changzhou Iveco series rear spring assembly 25×100 Changzhou Iveco bus
Front spring assembly 2×90 Changzhou Iveco bus
3 JAC Refine Series 7×70, 14×70HFC6500 Refine Commercial Vehicle
14×70, 16×70 HFC6500 Van
4 Beiqi Foton Series 11×75
5 Hunan Axle Spring Rear Assembly 12×75, 11×75
Front spring assembly 11×75, 10×75
6 Nanjing Yuejin (Bus) Series Front Spring Assembly 18.5×90NJ6890 Bus Chassis
Rear Spring Assembly 80×17, 14×70 NJ6890 Bus Chassis
7 Jiangling Transcend Series Front Spring Assembly 12×60, 23×60 Transit Single Wheel Small Card
Rear spring assembly 10×60, 21×60 Transit 15 passenger cars
8 Hunan Sanxiang (Bus) Series Rear Spring Assembly 13×90 Hunan Sanxiang Bus CK6870
Front spring assembly 11×90 Hunan Sanxiang Bus CK6870
18×75HNQ6790
18×75HNQ6790
Leaf spring production enterprises also use a small amount of Q235 flat steel and 70 # cold drawn steel wire, Q235 flat steel used for connecting structural parts, specifications for 4 × 25mm, 5 × 25mm, 6 × 30mm. 70 # roll cold-drawn steel wire, cut into fine particles sprayed on the surface of the heat treated steel sheet, used to remove the regenerated iron oxide skin, wire using the specifications of ? 1.2mm.
(2) Spring wire
Springs are used for suspension springs of cars and mini-cars, vans, shock absorber springs for motorcycles, etc. Steel grades are 60Si2MnA, 55CrSi(SUP12), 50GrVA and other grades.
There are 4 suspension springs in the sedan, and there are 2 front and rear suspensions. Generally, the front diameter is slightly smaller than the rear diameter. The diameter of each model is not the same, and the specification range is 9~16mm.
The spring steel wire for passenger suspension is made of high-grade spring steel wire and requires high strength, long fatigue life, and good damping effect. Therefore, the chemical composition, number of inclusions, and shape distribution of spring steel wire rod are required. , surface quality, decarburization layer, microstructure and mechanical properties and other requirements. Suspension springs require that the surface decarburized layer is less than 0.5% of the diameter, the surface is ground, the fatigue life is long, the dimensional tolerances are more stringent, and there should be no defect delivery. It is difficult to achieve the user's requirement by adopting the usual hot working method. Therefore, the spring of the car's spiral suspension is gradually changed from thermoforming to cold forming. After drawing and heat treatment (quenching and tempering to obtain martensite structure), the coil spring is made. . The development direction of the suspension spring steel wire is to reduce the carbon content, reduce the tendency of decarburization, improve the plastic forming property and the resistance to elastic attenuation and the like.
4. Domestic steel major suppliers
(1) Main domestic flat steel production enterprises
At present, the annual demand for raw materials for spring flat steel is about 560,000 tons. The quality, variety and specifications of domestically produced spring flat steel can basically meet the requirements of users. Take Dongfeng Automobile Leaf Spring Co., Ltd. as an example, the spring flat steel purchased by it is all. Localization, the main procurement Yongtong Iron and Steel Co., Ltd., Jiangxi Changli Automobile Spring Co., Ltd., Daye Special Steel Co., Ltd., Jiangyin Xingcheng Iron and Steel Co., Ltd. and other enterprises. Now the domestic companies that can produce spring flat steel are as follows:
Jiangxi Changli Automobile Spring Co., Ltd. is located in the eastern suburbs of Nanchang City, Jiangxi Province. Nanchang Iron & Steel Co., Ltd. has standardized the reorganization of Jiangxi Automobile Leaf Spring Co., Ltd., a subsidiary of the company, through capital increase and stock expansion. At the same time, it cooperates with Jiangling Motors Group and Guangzhou City. Tiangao Co., Ltd., Jiangxi Shangrao Xinjiang Industrial Group, Jiangxi Province Imported Auto Parts Co., Ltd. jointly initiated the establishment of a joint-stock company, which is a member of China Auto Parts Industry and Trade Group and is a designated manufacturer of auto parts in China. The main production equipment is imported from Japan, with an annual output of 60,000 tons of spring flat steel. Single and double slot flat steel specifications for 3 ~ 10 #, flat spring flat steel specifications (5 ~ 22) × (50 ~ 120) mm, length 4.8mm, material 55Si2Mn, 60Si2Mn, 55SiMnVB, 55SiMnoBRe, 50CrVA and so on.
Xinjiang Bayi Steel: The main products produced are spring flat steel (including double-groove, T-shaped) series products, specifications for 6 × 50 ~ 20 × 100mm, length 6 ~ 9m, annual production of about 60,000 tons.
Sichuan Chuanwei Iron and Steel Group Co., Ltd.: The main products are spring flat steel, specifications for (50 ~ 120) × (5 ~ 30) mm, steel 60Si2Mn, 55SiMnVB, 60CrMnA.
Fushun New Fushun Steel Co., Ltd.: The main products are 6-25×60～120mm spring flat steel products.
Sichuan Sichuan Auto Parts Manufacturing Co., Ltd.: The main production of automotive leaf spring, rolling a variety of automotive flat spring steel and automobile wheels, suspension and so on. Annually rolling 100,000 tons of automobile spring flat steel, producing 30,000 tons of automotive leaf springs.
Shenyang Dongyang Steel Co., Ltd.: The main product is (6 ~ 20) × (80 ~ 120) mm flat spring steel, steel species 55SiMn, 60Si2Mn.
Daye Special Steel Co., Ltd.: The annual production capacity of spring flat steel can reach 100,000 tons.
Zhengzhou Yongtong Special Steel Co., Ltd.: The main products are spring flat steel, spring round steel, flat steel specifications from 5 ~ 20mm to 50 ~ 150mm.
Huaigang Group: It produces all kinds of flat spring steel. Its main material is 60Si2Mn and 55SiMnVB. It produces 20,000 tons per year.
(2) Domestic production of spring steel wire rods
At present, the annual demand for raw materials for spring steel wire rods is about 40,000 tons, but the quality, variety, and specifications of domestic spring steel wires cannot meet the requirements of users. In particular, suspension spring wire rods that are required for supporting cars are required to be imported from abroad. The main importing countries are Japan, South Korea, Sweden and France. In recent years, wire rods used by a group of companies such as Zhengzhou Pilot Plant II, Tianjin Yanhua, Changsha Sprueton, Nanjing Dongwu, and Shanghai Yinrong have come from Japanese companies such as Kobe, Sumitomo, and domestic Baosteel. There are 60Si2MnA steels in use. , 55CrSi (SUP12), 50GrVA and other grades. There is still a gap in the quality of domestic products compared with similar products from Japan and South Korea. However, due to the relatively low prices, some spring plants have provided components such as mini-cars, van suspension springs, and motorcycle shock-absorbing springs.
At present, the major manufacturers of domestic alloy spring wire rods are Baosteel, Shougang Special Steel Plant, Dalian Steel Plant, and Shanghai Steel Five Plant. The five plants of Baosteel and Shanghai Steel have quality advantages, but the price is relatively higher than that of other steel plants. The spring steel wire rod produced by Baosteel High-speed Plant has 55SiCr, 50CrV, and 60Si2MnA grades, among which 55SiCr spring steel wire rods have been used on Mazda, Chang'an, Santana, Jetta, and Fukang cars after drawing, heat treatment and coil spring treatment. .
Third, the steel demand forecast
According to the forecast of the proportion of future automobile production and various types of vehicle models, the demand for automobile flat spring steel will be 600,000 to 700,000 tons by 2010.
The requirements for high-quality spring steel wire rods are high. In 2010, the total domestic market demand was about 80,000 tons. Domestic steel spring wire rod production capacity is available, but product quality needs to be further improved. It is necessary to continue to strengthen scientific research and development to form large batches and stability. The production capacity.
Fourth, the future development trend of automotive suspension spring
1. Air suspension spring
Air Suspension Spring is a kind of suspension system used on high-grade passenger cars and heavy-duty trucks. It is the development trend of the world's leaf springs. 100% of foreign buses, 100% of trailers, and 85% of heavy-duty trucks use air suspension springs to reduce noise and improve stability and comfort.
In the 1950s, air suspension springs began to be used on trucks, cars, buses and rail vehicles. In the 1960s, air spring suspensions were installed in most buses produced in industrialized countries such as Germany and the United States. At present, almost all foreign-made coaches, long-distance passenger cars and high-speed passenger cars use air spring suspensions, and some cars also use air spring suspensions, such as the German Mercedes-Benz 300SE and Mercedes-Benz 600. In addition, heavy-duty trucks have been used in recent years. It has also been widely used. Domestic air spring suspensions were designed and manufactured as early as the 1960s. However, due to the limited technical conditions in the industry, the products used at that time were not very satisfactory. After a long period of time, the products did not develop further. Therefore, foreign manufacturers producing air suspension springs have entered the domestic market with their capital and technical advantages, and have provided mature air spring suspension products for domestic manufacturers of luxury passenger cars.
Dongfeng Group is negotiating with US Rick and plans to introduce an air suspension spring production line. With the improvement of road conditions, the improvement of domestic consumption levels, and the upgrading of passenger car products, air suspension springs are gradually accepted by the market. At present, there are a number of luxury passenger cars produced by passenger car factories in the country that are equipped with air suspensions such as Ankai, Jinlong Bus, Guilin Daewoo, Hefei Hyundai, and Hangzhou Passenger Cars. The number of buses that use air suspension springs in China has exceeded 10,000. . With the increase of domestic automobile production, the number of air suspension springs will gradually increase, and the number of leaf springs will be in a downward trend. The cost of using an air suspension spring for a current truck is about 20,000 yuan, and an ordinary leaf spring spring is used for 2,000 yuan. Air suspension springs are more expensive. To reduce costs, some models use leaf springs on the front axle and air suspension springs on the rear springs. . At present, suspension springs are becoming lighter in weight and higher in stress. Some of the original mechanical devices consisting of springs are being replaced by pneumatic devices. Suspension springs should pay full attention to changes in this area and improve comprehensive development capabilities to adapt to the market. The needs and changes.
Air suspension springs are made of cast iron, forgings, thrust rods, guide columns and other structural components. If air suspension springs are used, most of the spring flat steel used in current trucks is replaced by a new type of structure. The ultimate development trend of air suspension springs is that no more or less spring flat steel is needed.
In the next 5 to 10 years, with the development of the domestic automobile industry, the total automobile production volume will increase, but it will also be the fastest growing period for air suspension springs. It is expected that the application of air suspension springs will offset the increase in automobile production volume. The demand for spring steel grows conservatively and it is estimated that the future spring steel demand will remain unchanged.
Passenger cars use air suspension springs on only a few high-end cars. The cost of a set of spiral springs for a typical car is several tens of yuan. The cost of a four-spoke spring car is 200 to 300 yuan, and a car with an air suspension spring has to pay 10,000 yuan. And the need to transform the electronic control system, the expensive cost, limiting the use of air suspension spring in the domestic car.
2. Variable Section Suspension Spring Development Trend
Profiled suspension springs are more reasonable than circular cross-section springs in terms of weight reduction, space saving, comfort improvement and spring stress distribution. However, these spring materials are expensive, and the spring manufacturing process is complex, making the spring production cost high. Due to the circular cross-section spring, there is currently no visible tendency for the profiled cross-section spring to completely replace the round cross-section spring. It is expected that the ratio of the round cross-section and the variable cross-section of the suspension spring will be approximately 3:1 in the period to come.
V. Conclusion
The use of suspension springs in the automotive industry is divided into leaf springs and springs. The passenger car uses a round spring and uses a diameter of 9 to 16mm, which is a type of cold-drawn circular steel wire. In addition, some micro-cars, van suspension springs, and motorcycle shock-absorbing springs also use springs. The annual demand for domestic round springs is 40,000 tons. Domestic spring steel wire rods are mainly produced by Baosteel and Shanghai Steel Fifth Plant. The quality of products is close to the advanced level in foreign countries, but the quantity cannot meet the needs of users.
The leaf springs are used for light trucks, medium and heavy-duty vehicles and passenger cars. The dimensions are 6 to 30×50 to 140 mm and the spring type is flat steel. The annual demand is about 560,000 tons. More domestic manufacturers, product quality can basically meet user needs, in addition to the user specified to import foreign steel spring flat steel, the basic use of domestic steel. In the next 5 to 10 years, with the development of the domestic automobile industry, the total automobile production volume will show an upward trend, but it is also the fastest growing period of air suspension springs. It is expected that the application of air suspension springs will offset the increase in automobile production volume. The spring steel demand caused by the increase, conservative estimates, the future spring steel demand will remain unchanged.