In modern vehicles, whether it is exterior decorative parts (such as bumpers, fenders, wheel covers, deflectors, etc.), interior decorative parts (such as instrument panels, door inner panels, sub-dashboards, glove compartment covers, seats) Chairs, rear guards, etc.), or functional and structural parts (fuel tank, radiator water chamber, air filter cover, fan blades, etc.), the shadow of plastic parts can be seen everywhere.At present, 100kg plastic materials on modern cars replace the traditional metal materials that originally required 200-300kg, and the weight-reduction effect is very prominent, which is of great significance for saving energy and reducing greenhouse gas emissions. For example, the replacement of metal by automobile plastic intake manifold can reduce the quality by 40% to 60%, and the surface light clear flow resistance is small, which can improve engine performance and play a certain role in improving combustion efficiency, reducing fuel consumption, vibration and noise reduction.According to statistics, there are dozens of plastics for automobiles, and the average amount of plastics per vehicle has accounted for 5% to 10% of the weight of automobiles. With the development of lightweight vehicles and the expansion of automotive plastics, automotive plastics The consumption of bicycles will further increase in the future.
There are two types of plastics for automobiles: one is a thermosetting plastic that can withstand ordinary baking operations; the other is a thermoplastic, which has the advantage of being easy and fast to process. Among the plastics for vehicles, the top 7 plastic materials and their proportions are roughly: 21% for polypropylene, 19.6% for polyurethane, 12.2% for polyvinyl chloride, 10.4% for thermoset composites, and ABS 8 %, nylon 7.8%, polyethylene 6%.
For example, the automobile bumper welding machine adopts a plate-type structure (reference material), and the heat of the heating plate is transferred to the welding surface of the upper and lower plastic heating members by an electric heating method. The surface is melted, and then the heating plate is quickly withdrawn. After heating the upper and lower heating members, the molten surface is fused, solidified and integrated. The whole machine is in the form of frame. It consists of three plates: upper template, lower template and hot template. It is equipped with hot mold, upper and lower plastic cold mold, and the action mode is pneumatic control. It is mainly used for welding of plastic parts such as household appliances, car lights and car dissolvers.The heating power and the die size can be set according to different plastic parts to realize welding of various plastic workpieces, and the operation is simple and convenient to use. The heating plate consists of two upper and lower blocks and is heated by an electric heating tube. There are two temperature controllers in the machine to control the temperature of the upper and lower molds. When welding, it can be set within the range of 0 to 600 °C according to the actual needs of welding. The control mode of the device can be divided into manual and automatic control. The manual is a single-piece action, which is mainly used for debugging of the mechanism and the mold. After manual debugging, the production is adjusted to automatic. The automatic control system is controlled by a programmable controller (PLC) and a touch screen human machine interface.
The car bumper welding machine uses the principle of electrothermal melting to prepare for controlling temperature changes, and is equipped with perfect mechanical devices to achieve perfect welding, which makes up for the shortage of ultrasonic welding machines for welding large and special plastic parts. It is mainly used for welding of thermoplastic materials such as PP and PE and plastic workpieces with large and complicated weld area.
Plastic connections are a key part of their widespread use. The plastic can be joined by mechanical fastening, bonding or welding. The fast fastening connection is suitable for all plastics, but it is costly, stress-concentrated, does not form a sealed joint or achieves proper performance. Bonding provides excellent performance and high quality joints, but it is difficult to operate, requires careful joint and surface preparation, and is very slow and not suitable for mass production. The welding is economical, simple, fast and reliable, and can form joints with static strength close to that of the base metal, so it is suitable for mass production and has been increasingly used in the automotive industry. The level of plastic welding technology has become one of the indicators to measure the level of automotive production technology and the level of new material development.