I. Introduction
China's accession to the WTO, market internationalization, procurement globalization will bring huge business opportunities to China's manufacturing industry, especially the automobile and aerospace manufacturing industries; the State Planning Commission and the Ministry of Science and Technology jointly issued the "priority of high-tech industrialization The Key Areas Guide has identified key industries that are prioritized in the automotive sector, mainly in the automotive parts manufacturing industry. The development direction of “small size, light weight and high speed†of the automobile industry has provided great development opportunities for the forging industry in China. 60% of the parts on the automobile are produced by the forging method. Relevant expert analysis pointed out that the automobile industry in the United States, Japan, and Germany is so developed, benefiting from the leading position of its forging technology and equipment. China's forging industry should adapt to the needs of international competition after China's entry into the WTO. It must use its high-tech to arm itself, upgrade itself, and unswervingly take the road of "precision, specialization, and modernization." The development of China's automobile industry has shown diversified tendencies, especially the development of family cars. In order to meet the requirements of different consumers, the car market has presented a pattern of multi-brand and multi-variety development, which will inevitably lead to diversification of forgings demand. In order to meet the needs of the market, the forging industry should give priority to how to make production more flexible in the past ten years, in order to meet the requirements of “timely production†in multiple varieties and small batches.
Second, the technological progress of the forging industry
The technological advancement in the forging industry is mainly reflected in the application of new materials, new processes and new equipment.
New material applications. According to relevant information, Germany is increasingly using microalloyed steel in the production of forgings. Since the subsequent heat treatment process can be eliminated in the process, the cost of the forging is reduced, and the forged piece made of the steel is rapidly cooled immediately after the die forging, and the fine grain structure strengthened by cyanide can be obtained, thereby Determine the better mechanical properties of the forging. The lightweight of automobiles will inevitably make the application ratio of magnesium, aluminum and titanium alloys higher and higher, and the demand for non-ferrous metal forgings will become higher and higher. The forging temperature of the alloy is low, the initial and final forging temperature range is small, and the forming speed and the matching forming equipment are relatively higher than the ordinary forgings. The application of new materials has increased the requirements for forging equipment and processes, and the added value of their products is also high. According to statistics, the sales of alloy steel forgings, which account for 5% of the total forgings in the United States and Canada, account for more than 20% of the total sales of forgings.
New process applications. The so-called "precision" means that a few net forming techniques are widely used, and the application of the new process achieves the goal of less chipping. Such as cross-rolling technology of rolling parts, roll forging technology; warm forging forming technology of flat-plate parts, swinging technology; multi-piece and multi-die forming technology of fork parts; powder forging forming technology of complex parts, etc. . The so-called "specialization" is the relative specialization of various types of parts manufacturing in terms of new process means. The application of the new process not only saves a lot of materials, but also improves the production efficiency and improves the internal and external quality of the forgings.
The application of new equipment. Due to the promotion and application of new materials and new processes, the forming equipment compatible with it has also gained a broad space for development. Forging equipment is gradually developing towards high efficiency, high precision, high reliability and low energy consumption. China's forging industry has scattered factory sites, backward technology, and aging equipment for forging. The production capacity of ordinary die forgings is very rich, but the production capacity of precision forgings that can reach the German DIN7526E standard is obviously insufficient, and the gap with foreign countries is large. Adapting to the needs of the international market, the forging industry actively promotes the specialization of technology on the one hand; on the other hand, it must adapt to the needs of multi-variety and small-volume production in a timely manner; vigorously promote technological transformation, actively adopt new equipment, and truly realize the modernization of the forging industry. Forging enterprises go abroad and meet the only way for the world's peers to compete.
3. The position and adaptability of forging hammer in the development of modern forging industry technology
Forging hammer is the pioneer of a variety of forging machines, and has a history of more than 100 years. Despite the continuous emergence of new forging and new processes and new equipment, the forging hammer still plays a very important role due to its simple structure, convenient operation, fast forming speed, strong adaptability and low investment. In particular, the emergence of program-controlled full-hydraulic forging hammers has once again revival of forging hammers in the development of modern forging industry technology. The special advantage of the hammer is that the striking speed is fast, so the contact time of the mold is short, which is especially suitable for the occasion where high-speed deformation is required to fill the mold. For example, forgings with thin ribbed plates, complex shapes and weight tolerance requirements. Due to its fast and flexible operating characteristics, its adaptability is very strong, and some people call it "universal" equipment. Therefore, it is especially suitable for the production of multiple varieties and small batches. Forging hammer is the most cost-effective forming equipment. The rapid forming characteristics of the forging hammer are not only fully utilized in the hot forging forming technology, but also have considerable advantages in the application of the cold forging forming process.
According to relevant data and research experiments, the higher deformation speed can increase the degree of plastic deformation of the metal, because the deformation speed is greater than the work hardening speed, so that the material can continue to deform without breaking; at the same time, due to the metal and the mold cavity The friction coefficient decreases with the increase of the deformation speed, which makes the metal flow speed increase and is easy to be filled and formed; the higher deformation speed not only reduces the deformation resistance, but also reduces the deformation non-uniformity. The rapid prototyping properties of the forging hammer are also applicable to the powder forging process. In order to reduce the contact time between the preform and the mold surface, to avoid the workpiece from being chilled and resulting in incomplete densification, and to reduce the thickness of the surface of the forging or the low-density layer of the partial surface, the high-impact speed and high precision full-hydraulic die forging hammer can be used. Improve the deformation speed, improve the life of the mold, reduce the deformation resistance, make the preform easy to fill the mold cavity, and ensure the quality and precision of the forging.
Fourth, the new development of forging hammer technology
Due to the versatile nature of the forging hammer, the forging hammer technology has been perfected with the development of science and technology, especially the development of modern hydraulic electrical control technology. The modern program-controlled full hydraulic die forging hammer has become a new type of forging device with high efficiency, energy saving, high precision and high reliability. The program-controlled full hydraulic die forging hammer adopts a unique full hydraulic transmission structure, which makes it possible for the hammer head to obtain huge energy in a short stroke, that is, short-stroke high-speed forging and high-frequency continuous forging are a reality. The flexible and fast characteristics of the hammer are fully utilized. The program-controlled full-hydraulic die forging hammer adopts the integral U-shaped cast steel anvil bed, which can easily replace the wide guide rail structure, and facilitates the mold fixing and adjusting structure of the mold, which provides a guarantee for the high precision requirements of the forgings. The hammer guide rail can reach 0.2mm, the working precision, the striking rigidity, the striking efficiency and the precision maintaining performance will be much better than the steaming hammer. The working state of the power head, especially the stress state of the hammer rod will be greatly improved; simple The structure is a prerequisite for the high reliability of the hammer. The program-controlled full hydraulic die forging hammer adopts advanced cone valve control technology, compound cylinder transmission technology, double anti-leakage technology and hydraulic integration technology to make the main oil circuit realize tubeless connection, and the system structure is much simple. The application of new technologies has greatly improved the reliability of equipment operation and laid the foundation for its successful application in the forging industry. The program-controlled full-hydraulic die-forging hammer is called modern forging equipment. It is not only because of its simple and reliable structure, but also its fast and flexible operation characteristics. It is also equipped with modern electronic monitoring systems such as online pressure, temperature and cleanliness. An energy self-control system that implements program blows. A good hydraulic system operating environment is a prerequisite for the normal operation of the hydraulic hammer; the precise impact energy control system not only reduces the vibration and noise caused by the extra-strike energy impact, but also improves the reliability of the equipment operation and the life of the mold, and stabilizes The quality of the forgings reduces the operator's proficiency requirements.
V. Application examples of program-controlled full hydraulic die forging hammer in the development of modern die forging technology
The high efficiency, energy saving, high precision and high reliability of the program-controlled full hydraulic die forging hammer have made the forging hammer revived in the advancement and development of the forging industry technology. Its adaptability is being proved by many practices.
The gear shifting fork of the sang car transmission of Shanghai Automobile Gear Factory was formed by the friction press. The forging temperature dropped rapidly due to the thin skin in the middle of the fork. The metal has poor fluidity, coupled with the slow forming speed of the press, the forming resistance of the forging is large, the cavity is not easy to fill, and the yield is only 80%. After the change to 25KJ hydraulic hammer two-mode é•— three hammer forging process, the forging contour is clear, full, the yield rate can reach 97%. Compared with the 25KJ hydraulic hammer, the 1000T friction press is much higher than the 25KJ hydraulic hammer in terms of energy consumption, mold life and production cost. At present, the plant has four forging production lines centered on hydraulic hammers.
Shanghai Surgical Instrument Factory has mainly relied on friction presses for forming the knife and shear. Due to the thin workpiece, the forming resistance of the forging is large, the thickness of the flash is more than 1mm, the dimensional accuracy of the forging is poor, and the deformation of the forging after cutting is large. The shape and dimensional accuracy of the forgings are ensured by the precision pressing process of the following roads, and the amount of work for grinding the edges after the pressing is large. After the hydraulic hammer forging shape, the forging speed is fast, the impact energy can be accurately controlled, the flash of the forging can reach 0.5mm, the deformation of the forging after cutting is small, the shape and dimensional accuracy is guaranteed, after trimming The precision pressing process is no longer needed, and the grinding work is greatly reduced. The application of the hydraulic die forging hammer greatly shortens the production process route and reduces the production cost by 30%. In addition, due to the application of the hammer, the heating time of the forging is reduced once, the forging temperature of the forging is also reduced, the oxidation of trace elements caused by heating is greatly reduced on the surface of the forging, the chemical properties of the forging material are guaranteed, and the corrosion occurring during use is avoided. phenomenon.
Hangzhou Wanxiang Group cross-shaft hot forging, the original process uses air hammer to make a blank and then through a friction press a single piece forming process, in recent years has been changed into a program-controlled full hydraulic die forging hammer forming process, one material three, the process Route: Heating - die forging hammer (casting - pre-forging - final forging) five hammer forming - trimming. Due to the high striking frequency of the die forging hammer, the hammer energy and the striking step of each hammer can be set by the program. The operation of three people in one production line can complete the work of 15 people in the original three production lines. The use of a three-piece forging hammer forming process not only greatly increases labor productivity, but also saves material. One piece of three pieces can be shared between the two pieces, and the amount of flash of the three parts is the amount of flash of the original two pieces. The Baicheng Tongye connecting rod is forged, and the line is a fully imported hot forging production line centered on a program-controlled full hydraulic die forging hammer. The forming process is: heating-roll forging blank-hammer upper die forging (two modules Hammer forming) - trimming. The line heating and roll forging are automatic operation. The whole line is operated by 2 workers. The output of the line is more than 4,000. At present, the factory has two connecting rod forging production lines, and plans to use another 31.5KJ program control in 2003. The whole hydraulic forging hammer is the center of the forging production line. He Guangyuan, former Minister of Machinery Industry, pointed out that China's forging height is in Baicheng, which fully demonstrates the advanced nature of its hot forging technology.
Shanghai Jiaotong University Plastic Forming Engineering Department has been engaged in the research of cold, warm forging and powder forging forming process. The latest research results: automobile motor drive gear cold die forging process and motorcycle three pin gear cold squeezing process, all use hydraulic mold A successful example of cold forging for hammers. With the popularization and application of special forging technology, the application of full-hydraulic short-stroke forging hammer for high-efficiency, energy-saving, high-precision and high-reliability new forging equipment will become more and more extensive.
Sixth, the conclusion
At present, the promotion and application of “three new†technology featuring new materials, new processes and new equipment has been valued by many forging enterprises. The application of high-efficiency, energy-saving and high-precision electro-hydraulic hammer in the future advancement and development of forging industry technology The advantages have gradually become a consensus. However, due to various factors such as economy and system in the past few years, the development of hydraulic hammer technology is relatively slow. Foreign forging hammer manufacturers have entered the Chinese market. According to statistics, in the past 5 years, China has introduced nearly 20 sets of hydraulic die forging hammers of various specifications. "Who will arm our country's forging industry?" This is a question worthy of our "forging people".
Domestically, some research institutes have made great contributions to the energy-saving renovation of China's steam-air dual-purpose hammers after more than ten years of research, but it is not enough to solve the energy-saving problem. Flexibility, speed, high precision and high reliability are every A common requirement of an electro-hydraulic hammer user.
Sellers Union Co., Ltd , http://www.nbshousehold.com