Application of the hottest composite materials in

Application of composite materials in foreign heavy-duty automobile parts

parts made of sheet molding compound (SMC)

sheet molding compound (SMC) is a kind of molding compound for dry manufacturing unsaturated polyester FRP products. In the early 1960s, this kind of plastic first appeared in Europe, and then the United States and Japan successively developed the processing technology of this kind of plastic material. At the end of the 1960s, the global demand for SMC began to take shape, and has increased by 20%~25% every year since then. The main advantages of SMC are:

● compared with metal, SMC has superior electrical performance, corrosion resistance, medium resistance, low price and flexible engineering design

● compared with reinforced thermoplastic, this material has the characteristics of not easy deformation, high mechanical properties and thermal deformation temperature, chemical corrosion resistance, etc

● compared with hand pasted and sprayed FRP, this material performs better in terms of forming cycle, working environment, product appearance, etc

at present, SMC is widely used in transportation vehicles, but its performance depends on the operation of computer servo system. In construction, electronics, electrical appliances and other industries. In order to promote the application of SMC and other composite materials in automobiles, the "automobile composite Alliance (ACA)" has been established abroad. The alliance has 25 suppliers, including mold, tool manufacturing and raw material production, who can provide composite products for the automotive industry

plastic expansion water tank

expansion water tank is a functional component with high requirements. It should not only adapt to the high temperature requirements of the engine cooling system, but also withstand the test of the external climate. Therefore, it is required to have stable performance between -40 ℃ ~120 ℃. At the same time, it should also withstand the test of overpressure up to 100KPA and undervoltage up to 4kPa in the box

currently, plastic expansion water tanks are installed on Volvo heavy trucks in Sweden, man buses in Germany and Hino trucks in Japan. Among them, the Volvo expansion water tank is made of translucent polypropylene (PP), which makes the water level of green antifreeze clear at a glance. The box body is welded by two upper and lower injection molded parts with flanges, and there are some diaphragms inside the box body, so as to improve the overall strength of the box body and its application function. The plastic expansion water tank is installed on the fixing frame at the lower part of the cab and fastened with screws

man expansion water tank is made of black plastic and made of 20% glass fiber reinforced PP (vestolen p9503). The water tank is blow molded, and the expansion water tank is divided into 8 water chambers by reinforcing ribs in the middle, so that the strength of the water tank is improved and it is also conducive to heat dissipation. The average wall thickness of the water tank is 3~4mm, and the minimum wall thickness is 2.5mm. In order to save space, the expansion water tank is made into a flat shape, whose length, width and thickness are 94cm, 38cm and 8cm respectively

Hino expansion water tank is also made of black plastic, which is welded by two injection molded parts with flanges. The liquid level observation holes of the water tank are upper and lower, which are respectively at the allowable maximum water level and minimum water level. The observation hole is welded with the box body by transparent plastic. The hole is equipped with red floating beads. The height of the liquid level can be judged by the floating and falling of the balls. The installation method of the water tank is to bind it with a metal belt and then install it on the fixed frame at the rear of the cab

compared with the expansion water tanks of Volvo, man and Hino, the main problems of domestic expansion water tanks are: the products are rough, the surface is uneven, and there are irregular thin lines. The main reason for this problem is the rough surface of the die; There are dislocation and unevenness at the welding parts of each interface, and there are potential dangers of desoldering, which are mainly caused by improper welding methods; Compared with foreign parts, the material texture and transparency are obviously insufficient; The wall thickness uniformity and the machining accuracy of the filling port and cover need to be further improved

generally, the expansion water tank produced by blow molding process needs to be welded with accessories. The welding strength requirements can be found in the relevant data. For example, when 980n force is applied to the vertical direction of the attachment welding surface, no cracking shall occur; No cracking shall occur when a torque of 9.8N m is applied in the direction of the welding surface

fender

fender, also known as fender, is generally installed on the upper part of automobile wheels. Its working environment is usually poor. It is not only subject to frequent collision and vibration, but also subject to natural conditions such as sunshine, cold and hot, rain and snow, sand and so on. For this reason, the materials used for fenders in the past were generally polyurethane. Although these materials have excellent performance, they are expensive, thermosetting materials and cannot be recycled. At present, Volvo uses pp-t20 + EPDM materials to produce mudguards, and installs a stone striking pad on the inner surface of the mudguard, which can not only protect the mudguard, but also reduce the stone striking noise. Similar applications can also be seen on Mitsubishi trucks in Japan

pp-t20 + EPDM material is mainly made of copolymer polypropylene + about 20% talc powder + EPDM. The addition of EPDM improved the toughness and atmospheric aging resistance of the products. The material has good elasticity, aging resistance, low cost, recyclability and environmental protection. The notched impact strength (23 ℃) of the simply supported beam made of this material is ≥ 8kj/㎡, and the young's modulus is ≥ 1700mpa, which can withstand long-term aging at 100 ℃

fan shroud

the fan shroud is located around the engine cooling fan, and has the function of wind direction diversion and protection. The Volvo fan shield is made of PP. the notched impact strength (23 ℃) of the simply supported beam made of this material is ≥ 4kj/㎡, and the young's modulus is ≥ 2000mPa. It can be used at higher temperatures for a long time

air filter shell

generally, the air filter shell is welded from metal plate, with many forming processes, requiring phosphating, painting and other anti-corrosion treatment, and there is a hidden danger of ash leakage from the weld. In order to solve these problems, the shell of Volvo air filter is blow molded with black PP plastic. Its processing process is simple and does not need painting. The product is not only light in weight, but also never rusted. The air filter shell formed by PP blow molding is installed with embedded metal parts. The embedded metal parts and the blow molding shell are connected by overheating welding. The welding part has a unique structure, including both surface welding and riveting. The filter element is placed in the middle and fixed with steel. After the filter element is placed, use bolts to fix the plastic cover to the plastic housing. There is a rubber ring between the cover and the housing for sealing

sunshade

at present, domestic heavy-duty vehicles basically use indoor sunshades or sunshades, which have the disadvantages of small area, poor sunshade effect and easy to cause driver eye fatigue. However, heavy-duty vehicles produced abroad, especially long-distance transport vehicles and container transport vehicles, such as Volvo, Steyr, Scania, man, etc., all use external sunshades. This piece is installed above the front windshield of the cab, with a length of about 2100mm and a height of about 300mm. It is hot pressed with organic glass (PMMA) plastic plate, and the colors are dark green, coffee, smoke, etc. The utility model has the advantages of both shading and light transmission, can thoroughly filter out harmful ultraviolet rays, and has a clear front view. After installing the outer sunshade, the light in the cab is soft, and the driving wind resistance is reduced due to the diversion effect

at present, the domestic sunshade often breaks and deforms during installation and use. The main reason is that the materials have poor impact resistance and heat resistance, which can also be confirmed from the test data of domestic and imported parts. Generally, the impact strength of the cantilever beam of domestic parts is 10kj/㎡, and the heat-resistant deformation temperature is not suitable for all testing machines. The porosity in the tensile test of flexible packaging materials is 90 ℃, while the impact strength of the cantilever beam of imported parts is 12kj/㎡, and the heat-resistant deformation temperature is 110 ℃. Therefore, it is hoped that relevant manufacturers will actively develop materials with good impact resistance

front grille and dashboard

plastic alloy is a polymer multi-component system with plastic characteristics, which includes copolymers (block copolymers such as ABS, graft copolymers such as PPO and PS graft copolymers) and blends (physical blends, chemical blends, etc.). In general, the performance of a single polymer is limited, while the plastic alloy can improve its shortcomings, so it is more widely used. For example, the impact performance of a single PS is poor and easy to crack, while the impact performance of PS with propylene hydrocarbon and butadiene, that is, ABS, is significantly improved. In addition, PPO has poor processability, which can be overcome by graft copolymerization with PS

for the front grille of the car installed in the front of the cab, it is generally required to be beautiful, heat-resistant and impact resistant. For this reason, Volvo uses PC + PBT GF20 material to produce such parts by injection molding process. The density of the material is about 1.2g/m, the tensile strength can reach 57MPa (equivalent to SMC), the elongation can reach more than 80%, the bending strength can reach more than 65mpa, and the thermal deformation temperature can reach 135 ℃ under the load of 1.8MPa

for the instrument panel, it is usually required to be able to withstand a high temperature of 110 ℃, which is difficult for a single ABS material. Therefore, man uses ABS + PC material to produce the instrument panel. By adding P with excellent heat resistance and impact resistance to ABS, the testing speed is fast, and the test piece is placed vertically on the torque disc C during measurement, which can not only meet the high temperature requirements of 110 ℃, but also enhance its impact resistance. In addition, the wall thickness of the left and right air guide hoods produced by man using PPO ＋ PA materials is 3mm, and its service temperature is -40 ℃ ~135 ℃

heat insulation and sound absorption parts

in the past, the heat insulation and sound absorption parts installed on some heavy-duty vehicles were generally small, usually installed in the machine compartment, and the materials used were glass wool board covered with aluminum foil, polyurethane foam board, etc. In principle, although these materials can play a role in sound insulation and heat insulation inside the cab, they can not reduce the noise outside the vehicle. In order to reduce the noise outside the vehicle at the same time, it is necessary to install sound insulation and absorption parts on the whole engine. At present, the upper part of Volvo car engine is equipped with heat insulation and noise reduction parts, which are composed of fabric fiber and polyester layer (cotton fiber, polyester fiber, flame retardant and curing agent). The surface is covered with needled felt. After high temperature hot pressing, its area can cover the whole engine, with good heat insulation and noise reduction effect, especially the noise outside the car can be significantly reduced. (end)