In recent years, with the rapid development of the automobile industry, the problems of fuel consumption, environmental protection and safety of automobiles are increasingly concerned by people. Looking forward to the future development direction of the automotive industry, lightweight, low fuel consumption and less emissions is the theme of development. According to the international authoritative department statistics data, 60% of the automobile fuel burning energy consumption in their own quality, despite the high strength sheet steel, aluminum and magnesium materials, metal matrix composites and plastic resin materials has played a role in the field of auto weight reduction, but the advent of automobile manufacture industrial titanium material have a better choice.
As the sales volume of automobiles is getting higher and higher, more automobile enterprises are also paying more attention to cost control. Cost control and research and development of new vehicles can make enterprises more competitive in the market. Currently, 3D printed parts can significantly reduce costs for enterprises. This paper will introduce the application of titanium alloy and 3D printing in automobile industry from the following aspects.
I. application status of titanium alloy in automobile industry
Titanium metal has the advantages of small density, high specific strength and good corrosion resistance. The adoption of titanium material in automobile can greatly reduce body quality, reduce fuel consumption, improve engine work efficiency, improve environment and reduce noise. However, due to its high price, titanium alloy can only be used in luxury models and sports cars in the automobile industry, but rarely in ordinary cars. Therefore, the research and development of low-cost titanium alloy to meet the needs of the market is the key to promote its application in ordinary household cars.
Although titanium alloys have been widely used in aerospace, petrochemical and ship industries, their applications in the automotive industry have developed slowly. From 1956 when the first all-titanium automobile was successfully developed by general motors of the United States, the titanium auto parts did not reach the level of mass production until the 1980s. In the 1990s, with the increasing demand for luxury cars, sports cars and racing cars, the titanium auto parts developed rapidly. In 1990, the titanium content of the world's automobiles was only 50t; in 1997, it reached 500t; in 2002, it reached 1,100t; in 2009, it reached 3,000t; it is expected that the titanium content of the world's automobiles will exceed 5,000t in 2015. At present, titanium alloy parts have the following more commonly used.
1. Application of titanium alloy in automobile parts
1.1 engine connecting rod
Titanium alloy is an ideal material for connecting rod. Engine connecting rod made of titanium alloy can effectively reduce engine quality, improve fuel efficiency and reduce exhaust. Compared with the steel connecting rod, the titanium connecting rod can reduce the mass by 15% ~ 20%. The application of titanium alloy connecting rod was first demonstrated on the 3.5LV8 and Acura NSX engines of the new ferrari car in Italy. The materials used in titanium alloy connecting rod mainly include ti-6al-4v, ti-10v-2fe-3al, ti-3al-2v and ti-4al-4mo-sn-0.5 Si, etc. Other titanium alloy materials, such as ti-4al-2si-4mn and ti-7mn-4mo, are also in the research and development of connecting rod.
1.2 engine valves
Automobile engine valves made of titanium alloy can not only reduce quality and prolong service life, but also reduce fuel consumption and improve automobile reliability. Compared with the steel valve, the quality of titanium valve can be reduced by 30% ~ 40%, and the limit speed of engine can be increased by 20%. For current applications, ti-6al-4v is the main material for the inlet valve, and ti-6242s is the main material for the exhaust valve. Usually Sn and Al are added together to obtain lower brittleness and higher strength. The addition of Mo can improve the heat treatment performance of titanium alloy, strengthen the strength of quenching and aging titanium alloy, and increase the hardness. Other potential titanium alloys include:
1) the inlet valve can adopt ti-62s, whose characteristics are equivalent to ti-6al-4v, and the price is relatively cheap.
2) the exhaust valve can be used Ti 6 al zr - 0.4-2 sn - 4 Mo - 0.45 - Si, because of the low Mo content, therefore, its resistance to creep resistance is Ti - 6242 - s, resistance to oxidation temperature can reach 600 ℃.
3) the exhaust valve can be used, which has the characteristics of high temperature resistance and light weight, but the traditional forging method is not suitable for processing, only suitable for casting and powder metallurgy processing.
1.3 valve spring seat
High strength and fatigue resistance is the valve spring seat must have the performance, titanium alloy is heat treatment alloy, can get high strength through solid solution aging treatment, the corresponding suitable material is ti-15v-3cr-3al-3sn and ti-15mo-3al-2.7 nb-0.2 Si. Mitsubishi motors USES ti-22v-4al titanium alloy valve spring seat in its large-scale production vehicles, which reduces 42% of the mass compared with the original steel lock, reduces 6% of the inertial mass of the valve mechanism, and increases the maximum engine speed by 300r/min.
1.4 titanium alloy spring
(10) titanium and its alloys have low modulus of elasticity relative to steel and have high value of s/E. Compared with the steel car spring, the titanium spring is only 40% of the height and 30% ~ 40% of the mass of the steel spring under the premise of the same elastic work, which is convenient for the car body design. In addition, excellent fatigue performance and corrosion resistance of titanium alloy can improve the service life of the spring. At present, ti-4.5 fe-6.8 mo-1.5 Al and ti-13v-11c-3al are titanium alloy materials that can be used to make automotive springs.
Turbochargers can improve engine combustion efficiency and enhance engine power and torque. Turbocharger turbine rotor need to work for a long time in more than 850 ℃ high temperature exhaust gas, so demand has very good heat resistance. Traditional light metals such as aluminium alloys are not usable because of their low melting point. Although ceramic materials are used in turbine rotors due to their light weight and high temperature resistance, their applications are limited due to high cost and shape optimization. In order to solve these problems, Tetsui et al. developed the rotor of the capital turbine, which has been tested and verified for many times. It not only has good durability and efficiency, but also can improve the acceleration of the engine. The design has been successfully commercialized in the Mitsubishi Lancer Evolution series.
1.6 exhaust system and muffler
Titanium is widely used in automobile exhaust system. Exhaust systems made of titanium and its alloys not only improve reliability, life and appearance, but also reduce quality and improve fuel combustion efficiency. The titanium exhaust system has a mass reduction of about 40% compared to the steel exhaust system. In Golf series cars, the quality of titanium exhaust system can be reduced by 7 ~ 9kg. At present, the titanium used in the exhaust system is mainly pure industrial titanium.
The quality of titanium muffler is only 5 ~ 6kg, which is lighter than stainless steel muffler. The 2000 Chevrolet CorvetteZ06 replaces the 20kg stainless steel system with an 11.8kg titanium muffler and exhaust pipe system, resulting in a 41% reduction in mass. The replacement system has the same strength, and makes the car faster, more flexible and fuel saving. Muffler USES titanium material is also mainly pure industrial titanium.
1.7 body frame part
In order to improve the safety and reliability of automobile, the design and manufacturing aspects, especially the manufacturing materials, need to be considered. Titanium is a good material used to make the frame of the car body. It is not only higher than the strength, but also has good toughness. In Japan, car manufacturers choose pure titanium welded tubes as the body frame, which can make drivers feel safe when driving.
1.8 other titanium alloy parts
In addition to the above components, titanium is also used in engine rocker arm, suspension spring, engine piston pin, automotive fasteners, lug nut, car door protruding beam, car block support, brake caliper piston, pin pin, pressure plate, speed change button and car clutch circular plate and other auto parts.
2. Application of titanium alloy
2.1 the advantages
Titanium alloy has the advantages of light weight, high specific strength, good corrosion resistance, so it is widely used in the automotive industry, the application of titanium alloy is the most car engine system. There are many advantages in using titanium alloy to manufacture engine parts, which are mainly reflected in the following aspects:
1) the low density of titanium alloy can reduce the inertial mass of moving parts. At the same time, the titanium valve spring can increase the free vibration, weaken the body vibration, and improve the engine speed and output power.
2) reduce the inertia mass of moving parts, so as to reduce the friction and improve the fuel efficiency of the engine.
3) the choice of titanium alloy can reduce the load stress of the relevant parts, reduce the size of the parts, so as to reduce the quality of the engine and the vehicle.
4) the reduction of inertial mass of parts will weaken vibration and noise and improve engine performance.
The application of titanium alloy in other parts can improve the comfort of personnel and the aesthetics of cars. In the application of automobile industry, titanium alloy plays an immeasurable role in energy saving and consumption reduction.
2.2 application restrictions
Although titanium alloy parts have such superior performance, there is still a long way to go before titanium and its alloys are widely used in the automobile industry.
With the recent development of near-net forming technology of titanium alloy and modern welding technology such as electron beam welding, plasma arc welding and laser welding, the forming and welding problem of titanium alloy is no longer the key factor restricting the application of titanium alloy.
The price of titanium alloy is much higher than other metals in both the initial smelting and subsequent processing. The cost of titanium parts acceptable to the automotive industry is $8 ~ $13 / kg for connecting rods, $13 ~ $20 / kg for air valves, and $8 ~ $8 / kg for springs, engine exhaust systems, and fasteners. And the spare part cost that USES titanium material to produce at present is much higher than these prices, the production cost of titanium sheet is most prep above 33 dollars/kilogram, it is aluminium sheet 6 ~ 15 times, steel sheet 45 ~ 83 times.
Ii. Application of 3D printing in the automobile industry
3D printing, your first impression may be all kinds of plastic printed items. The main reason is that the most popular desktop 3D printers are basically made of FDM, and the materials are mostly plastics such as PLA and ABS. Currently, 3D printing technologies for metal preparation mainly include selective laser sintering (SLS), electron beam selective melting (EBSM), and laser near-net shaping (LENS).
At present, many automobile manufacturers will use 3D printing to make part prototypes for industrial verification and design modification in the research and development stage. Of course, many companies are already experimenting with 3D printing for cars. Among the metal parts used in automobiles, some are forged and some are cast, and the majority of them are cast. Forging mechanical properties, rigidity are better, generally used for important parts. The mechanical properties of castings are not as good as those of forgings. The current metal 3D printing parts are relatively poor in shear resistance, but other properties should be better than casting parts, but not as good as forging parts.
Therefore, many auto parts can be 3d-printed with metal. Previously, several giants including Google and BMW invested in Desktop Metal, a 3D printing company. BMW hopes to accelerate the use of 3D printing of metals in car manufacturing.
1.3d printing's application in automobile industry
1) first of all, 3D printing can be applied to the whole vehicle modeling, and the full size can be created in 1:1 according to the requirements of the designer through this process. It is necessary to design, review and determine the appearance and shape of automobile, interior decoration and so on.
2) 3D printing can be used to verify the design and the reliability of the product (installation structure, part matching, structural strength, etc.). At the same time, in order to make up for the design risk brought by the vehicle test in the middle and late stage of vehicle development, verification should be carried out in the early stage of design.
3) in the face of some parts with complex structure, which cannot be manufactured by traditional manufacturing process, or the conventional manufacturing cost is very high, the application of 3D printing process can be well solved.
4) lightweight automobile occupies a pivotal position in product development. 3D printing technology makes it possible to manufacture lightweight structural parts in plastics and even metals instead of relying on a single traditional process.
5) through 3D printing technology, assembly parts, measuring tools and gauges on the production line are also applicable in addition to auto parts.
2.3 advantages of D printing in automobile industry
A car takes a long time from product planning to launch, and the development of a brand new product can take up to 57 months. It will take much longer to develop the technology. 3D printing technology can greatly shorten the production cycle. Businesses can be more efficient. Secondly, more emphasis can be placed on product reliability during the development process. Thirdly, it can solve the limitation of product production process, for example, some parts cannot be reached by traditional technology. In terms of cost, the product development cost is reduced without the need to manufacture abrasive tools and specific production lines. Finally, the individualization of automobile products can be realized, which is suitable for small batch personalized manufacturing.
3.3d shortcomings of printing in the automobile industry
3D printing is still in the research and development stage and has not reached the mature level. It cannot replace the traditional technology in a short time. There is still a gap in surface quality, need polishing, dyeing, electroplating, spray paint and other follow-up treatment. The choice of materials is also limited. At present, the overall industrial chain is not mature.
The new generation of automobile design pays more attention to the lightweight of the body, low fuel consumption, low noise and light vibration of the engine to meet the increasingly demanding requirements of the environment. In this context, the light metal titanium will be a major application material of choice for future automobiles. Titanium alloys will eventually play an important role in the automobile industry. As a new technology, 3D printing is also serving the automobile industry.