In the era of rapid development of the automotive industry, every link in the car manufacturing process is of vital importance. From design and research to production and manufacturing, from parts supply to vehicle assembly, each step directly affects the performance, quality, and market competitiveness of a car. In this complex manufacturing system, precision forging technology, as one of the core technologies for automotive parts production, is gradually becoming a key force in driving the progress of the automotive industry. This article will delve into the application of precision forging in car manufacturing and how it brings about changes in the automotive industry.
Precision forging is an advanced manufacturing process that controls the deformation of metal with great accuracy to achieve extremely high precision in the shape and size of metal parts. This technology is widely used in car manufacturing, especially in the production of high-strength, high-toughness, and complex-shaped parts, where precision forging shows unparalleled advantages.
It is no accident that nearly 60% of car parts are produced by forging. Parts made by forging are strong and tough, capable of withstanding the high-intensity loads of a car under various complex working conditions. For example, key parts such as the engine crankshaft, connecting rod, and transmission gear require extremely high strength and toughness to ensure the safety and reliability of the car. Precision forging technology can precisely control the flow and deformation of metal, enabling parts to meet design requirements while also achieving lightweighting, which is of great significance for improving the fuel economy of cars and reducing exhaust emissions.
With the rapid increase in car production, while car manufacturers are enhancing and integrating the overall production capacity of vehicles, they are also actively seeking lightweight solutions for parts. Lightweighting can not only improve the fuel economy of cars but also reduce exhaust emissions, in line with environmental requirements. To achieve this goal, car manufacturers have turned their attention to precision forging technology.
Take the CVT transmission as an example. In order to meet the lightweight requirements, engineers combined the gear and shaft into a pulley and achieved near-net shape forming through precision forging. This design not only significantly reduced the size of the transmission but also made it more compact and environmentally friendly. More and more car manufacturers are pursuing lightweighting and fuel-saving rates, and replacing traditional cutting processes with precision forging technology has become the main direction for new product development. The emergence of precision forging technology has provided strong technical support for the lightweight development of the automotive industry.
Precision forging not only has significant advantages in product quality but also effectively reduces the manufacturing costs of the entire supply chain and improves production efficiency. In the field of automotive parts manufacturing, cost control and production efficiency are key factors for the survival and development of enterprises. The widespread application of precision forging technology has brought great economic benefits to car manufacturing companies.
In current practice, precision forging can reduce the manufacturing costs of the entire supply chain, with a general savings rate of more than 15%. Although the forging cost will increase after adopting precision forging technology, the machining cost is greatly reduced, thereby significantly lowering the total cost. For example, combining the overall forging of gears to replace the manufacturing process of separate machining of synchronous gears and the body can save about 25% of production costs. This not only represents the trend of future car transmission gear processing but also brings considerable cost savings to car manufacturing companies.
Another important feature of precision forging is that the manufacturing cost gradually decreases with the increase of production volume. This mainly reflects the advantages of the mold forming process, that is, high efficiency and high consistency. Although the fixed cost is relatively high in production, the production efficiency is also correspondingly increased. For mass-produced parts, only a small amount of additional cost is needed to achieve a great increase in production capacity. This highly efficient production model enables car manufacturing companies to occupy a favorable position in the fierce market competition.
The development of precision forging technology can be traced back to the early 20th century, but it has made breakthrough progress only in the past few decades. With the continuous development of the automotive industry, the requirements for the precision and performance of parts are getting higher and higher, and precision forging technology is also constantly innovating and improving.
In developed countries, such as Germany and Japan, precision forging technology is mainly used in the production of passenger car parts. From wheel bolts and alternators to air pump rotors, CVJ parts' outer and inner star wheels, these are all important products in the development of precision forging. Since the 1990s, precision gears have become the main target products, and this technology has now been further expanded to some important automotive parts, such as the production of bevel gears, connecting rods, crankshafts, and other forgings.
In China, precision forging technology is also constantly developing. At present, precision forgings in cars are mainly concentrated in the transmission and rear axle assembly. In addition, typical automotive precision forgings also include the transmission assembly in passenger cars and the half shafts in rear-wheel-drive vehicles. For traditional automotive forging companies, the development of precision forging technology is imperative. This can not only enhance the competitive advantage of automotive parts but also meet the market's demand for high-quality and high-performance parts.
Precision forging technology is widely used in the production of automotive parts and covers various types of parts. The following are the precision forging processes and characteristics of some typical parts.
The precision forging technology for bevel gears has been applied in production relatively early, and its development has evolved from the initial two-fire two-forging to one-fire two-forging. This technological progress enables the forming of larger diameter gears with complex shapes by hot forging with the fewest processes. Currently, the bevel gears of automotive differentials have basically eliminated cutting processing technology and turned to precision forging production. This process not only improves production efficiency but also reduces production costs, making the production of bevel gears more efficient and economical.
With the increasing requirements for product precision, the dimensional accuracy of hot precision forging gears can no longer meet the product precision requirements. For example, planetary semi-shaft gears in passenger cars have begun to adopt cold forging processes, such as closed die forging and cold rolling technology, and the product precision can reach IT7 level. However, the applicability of cold forging is relatively low, and currently, only gears with a diameter of less than φ90mm can be produced in China. In order to combine the advantages of hot forging and cold forging, the development trend is the combination of hot-cold or warm-cold composite forging processes, or using warm precision forging to directly form high-precision straight bevel gears.
With the increasing requirements for energy-saving, emission reduction, and lightweighting of automobiles, the structure of combined gears in the transmission is evolving towards integration. The method of combining hot forging forming with cold forging finishing is used to produce the integrated forgings of synchronizers and bodies of automotive transmissions. For the tooth shape of the combined gear, hot precision forging or warm forging is used, and then the precision forging piece is cold finished to ensure the tooth shape accuracy. This process not only improves the precision and performance of the gear but also reduces production costs, making the combined gear widely used in the automotive industry.
Straight bevel gears are the main parts of components such as transmissions, transfer cases, and drive axles. Due to the lack of draft angle, the precision forging process of straight bevel gears has certain difficulties in demolding and tooth tip forming, so its popularity is relatively low. At present, the precision forging processes for straight bevel gears mainly include hot precision forging, cold precision forging, cold extrusion, hot forging-cold extrusion, warm forging-cold extrusion, etc. For example, the reverse gear part of the manual transmission developed by the gear diversion forging process technology, since the reverse gear has certain conical requirements on the tooth surface, the tooth surface needs to be cold forged and shaped once after tooth forming. This process not only improves the precision and performance of the gear but also reduces production costs, making the production of straight bevel gears more efficient and economical.
Spiral bevel gears are large in size, deep in tooth slots, and affected by the helix angle, making precision forging more difficult. In developed countries, the precision of spiral bevel gears produced is high and has begun to be widely used in the automotive industry. At present, the domestic spiral bevel gears adopt the flashless closed die forging process. The blank is heated with little or no oxidation, and first, the blank is made by expanding and rolling process (upsetting, punching, and expanding), and after the blank is completed, pre-forging and final forging are carried out, leaving a small amount of allowance on the tooth surface for precision milling. The process is hot forging + warm finishing or hot forging + cold finishing. In the sub-hot forging range (950°C to 1050°C), the metal is plastically deformed and rapidly flows into the cavity in the closed die to obtain a precision forging gear blank with qualified tooth shape; in the warm forging range (800°C to 650°C), precision finishing and pressing are carried out to improve the tooth shape accuracy of the precision forging gear blank. This process not only improves the precision and performance of spiral bevel gears but also reduces production costs, making the production of spiral bevel gears more efficient and economical.
Precision forging technology, as one of the key technologies in car manufacturing, is gradually becoming a core force in driving the development of the automotive industry. It can not only improve the quality and performance of automotive parts but also effectively reduce manufacturing costs and increase production efficiency. With the continuous development of the automotive industry, precision forging technology will play an important role in more fields and provide strong technical support for the lightweight, efficient, and intelligent development of the automotive industry. In the future, precision forging technology will develop towards higher precision, wider application range, and intelligent production, bringing more opportunities and challenges to car manufacturing companies.
