1.All carbon fiber hard shell car body Lamborghini's new flagship super sports car aventador lp700-4 has a future style. The cabin is made entirely of carbon fiber, and its bearing structure is "single shell" design. It can be used as a single component in structure, so as to make full use of the super rigidity of carbon fiber reinforced materials.
F1 racing car adopts carbon fiber reinforced hard shell structure for many years, and its crashworthiness has been tested. Carbon fiber cockpit is as firm and reliable as metal cage. In fact, the name of "single shell" is just a description. The new Lamborghini hard shell car body is actually made of a series of independent components with different functions, which are reinforced by "braiding" technology This is one of them.
Although it is composed of many parts, but after curing, this structure can be turned into a single part to work together. The bottom structure of the single shell is made of aluminum "skeleton". This structure of carbon fiber body and aluminum alloy frame is a bit like China's "gold inlaid jade" process, which can ensure the light weight and the strength and style of the body. In addition to the superior passive safety, the all carbon fiber hard shell car body also has another major advantage - Ultra-high torsional stiffness. The whole body in white only weighs 229.5kg, but its torsional rigidity is extremely outstanding, up to 35000nm. The front and rear parts of the hard shell car body are connected with the aluminum subframe with the same stiffness, and the suspension, engine and transmission are installed on the subframe. According to the shape, function and requirements of each component, Lamborghini uses three main manufacturing methods to make carbon fiber reinforced materials. (1) Resin transfer molding: In this process, the carbon fiber felt is preformed and impregnated with a precise amount of resin. Then, the carbon fiber felt needs to be cured at high temperature, and the parts are molded immediately. (2) Prepreg: The carbon fiber felt treated in this way is usually called "prepreg", that is to say, it is pre injected with thermosetting liquid resin and stored at low temperature. Then, the carbon fiber felt is laminated in the mold and cured by hot pressing in the heat exchanger. The manufacturing process of prepreg parts is very complex, but the surface finish is excellent (grade a finish), so it is the best choice to create the exposed parts of the car. (3) Weaving: This carbon fiber weaving technology comes from the textile industry and is used to manufacture hollow parts for special purposes such as roof structural pillars and door panels. The braiding part is composed of several layers of fiber in diagonal direction.
Quality management is a crucial factor - the tolerance of each hard shell car body is strictly controlled below 0.1 mm, so as to ensure that the whole vehicle reaches the extremely accurate quality standard.
2. Challenging carbon fiber body painting Lamborghini supercar is made of carbon fiber without exception. But carbon fiber body is very challenging for baking paint. Lamborghini's two production lines almost occupy the entire assembly space, where there is no room for the paint room. They had to send the unpainted car shell to the town of Mirandola, 35 kilometers away. The factory has been in charge of many Lamborghini cars since the 1970s. All carbon fiber body parts need to be sanded to make the surface rough to facilitate paint adhesion. At the same time, the sanding process can also eliminate some defects on the surface of carbon fiber. Like steel body, primer must be applied before topcoat. It's all painted by hand, less than three of them a day. The primer is beige in color, two layers on top, and then baked at 70 ℃ for two hours in the heating chamber. After the primer is dry and solid, the surface is wet treated with a special solvent, which helps to reveal the subtle defects that can only be seen by the traveler. After finding out the defects, the craftsman carefully grinds them out before spraying the topcoat. It's two people's job to spray the top coat by hand. A painter is responsible for spraying the inside of the car body, such as the inside of the door panel. Another painter is responsible for painting the outside, such as the outside of the door. There is a reason for this. Although the technical requirements and spraying methods are the same, the color absorbed by each spraying technician is still slightly different. Therefore, a car's body finish only by the same spraying technician to implement, in order to make it achieve the unity of the vehicle, flawless. Depending on the color, the paint should be applied in two or three layers. The spray starts from the roof, from top to bottom, and then moves to both sides. It takes about 12 hours to apply the topcoat. After the final coat is dry and solid, the car should be sprayed with protective transparent paint. Carbon fiber parts that don't need to be painted inside the car are also sprayed with clear paint as protection. The last step in the paint baking process is polishing. More than 50 hours of polishing operation to ensure that the topcoat will never crack. The qualified body shell will be transported to the main assembly line.
3. High performance forged carbon fiber In 2018, the first Lamborghini SUV, urus, will be launched in mass production. In order to make the SUV still reach the road performance of sports cars, weight reduction is the primary task. So Lamborghini has developed new carbon fiber manufacturing technology to meet the requirements of large-scale, assembly line production, and at the same time to reduce its cost significantly. This is carbon fiber forging composite technology. This new carbon fiber manufacturing technology is different from the current mass application of carbon fiber woven cloth + resin manufacturing process, it can be mass and efficient flow production, laying a solid foundation for Lamborghini mass production of new models. This technology is named carbon fiber forging composite, which has many advantages: it can be applied to complex geometry, save manufacturing time and reduce the cost of raw materials. This technology was first applied in 2010. After six years of technology accumulation, it can now carry out large-scale production. At present, Lamborghini has deeply cooperated with Japan's Mitsubishi Liyang Co., Ltd. to jointly develop carbon fiber forging technology, which will be applied to new models. This new carbon fiber composite material is made by stamping according to the die: after adding carbon fiber and resin into the die, it is forged by hydraulic press, so the production time is greatly reduced.
“FORGED COMPOSITE is produced by Sheet Moulding Compound process with carbon fibres (opposited traditional glass fibre SMC) It uses pre-fabricated sheet material made of vinylester resin and short length carbon fibres (chopped fibers)”
This is to quote the application of forging composite technology in the official publicity materials of Lamborghini. In short, it is the SMC process of carbon fiber.
As like as two peas, the other products are similar in molding process.
From the figure above, we can see that forging composite technology has an overwhelming advantage over other processes in cycle time, which is also determined by the characteristics of molding process. The production cycle is short and the production efficiency is high.
Compared with RTM process, the cycle time is reduced by 44% Although this technology has been used in glass fiber composites for a long time, it is rare in carbon fiber composites, because using this technology, the fiber length needs to be in a certain range, such as glass fiber is generally 6 ~ 25mm (it may not be accurate by memory). For the molding of carbon fiber, the glass fiber used is a kind of short carbon fiber material. After this material is mixed with resin, under the action of high pressure, it has good fluidity and can form parts with complex structure. The more famous suppliers of this kind of chopped carbon fiber are quantum composites and Mitsubishi Liyang, which are also suppliers of Lamborghini.
So, to sum up, forging composite technology is not a particularly black technology. It is the application of carbon fiber composite, SMC material and molding process. However, for publicity, Lamborghini registered a patent name that sounds very tall. For the technology of packaging, this is worth learning.
Content source: Automobile Knowledge
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