Most of the bumper area of the vehicle located in front of and behind, and that the main absorption mitigate external impact, the safety device from the front and rear portions of the vehicle body guard. It is an important part of the vehicle body, which ,, except for decoration but also the protective role of the outer fender panel, and the heat sink fixture. Because the bumper is composed of a plurality of components, so that the material used is also very extensive. The bumper is one of the main pieces of plastic car, according to the requirements of different models, the current domestic car bumper is mostly gray and black. With the development of automobile industry, automobile bumpers as an important safety device on their way to the revolutionary road. The current car is now front and rear bumpers in addition to maintaining the existing protection, but also the pursuit of harmony and unity with the body shape, people are no longer satisfied with a black bumper, asking the same color bumpers and body. To achieve weight reduction itself. In order to achieve this purpose, the current car’s front and rear bumpers used plastic, known as the plastic bumper.
1 bumper effect
is designed to avoid the influence of the vehicle on the surface of the external damage caused by vehicle safety systems, they have a reduced occupants in high-speed impact damageAbility, now more and more are designed for pedestrian protection. Bumper into the front bumper and rear bumper, when its role is subject to the current car, slightly unexpected direction after a low-speed collision, ease the impact, absorbing energy of the collision, reduce vehicle damage, ensure the safety of occupants.
However, the bumper effect is limited, when subjected to a high speed collision, it can only absorb a small portion of the energy, and safety can not be relied on. Only can play a cushioning effect when a vehicle collision accident protection around the body. Front and rear bumper materials are metal, plastic, glass, steel, some bumper, fitted inside hydraulic cylinder, can absorb more impact energy. Modern automobile bumpers generally employed rigid polyurethane plastic injection molding.
Many of the bumper outer surface of granular striae, looks cortex sense. There above the bumper is equipped with turn signals and fog lamps.
2. Bumper lightweight design
of (a) the two routes lightweight design
1. To change the structure of automobile parts to achieve lightweight design purposes. By improving the structure of the thin-walled member, hollow, miniaturization and composite, and then the weight.
2. Use the lightweight materials, by employing a lightweight metallic and non-metallic materials, high-strength steel is mainly used, aluminum-magnesium alloy, engineering plastics and composite materials for various automotive lightweight design.
( b) lightweight materials
Aluminum 1.
the density of aluminum is only 1/3 of steel, the material is lightweight design targets of car bumpers frequently used. Audi 100C3 car front bumper outer plate made of plastic and the like beams made of aluminum alloy composition, cross material is a A1MgSMnW27, a thickness of 2.0mm. Made with aluminum front bumper beam main purpose is to reduce quality, followed by the use of its features to absorb collision energy.
2. Aluminum Foam
The foamed aluminum material automobile bumpers, a large degree of collision energy absorbed two vehicles, so that safety of the vehicle is greatly improved. From the performance that is filled with aluminum foam tube having excellent impact energy when axial impact absorption, so it has very broad application prospects in the mechanical cushioning means.
Compared to traditional thin-walled hollow metal bumpers, under the same energy absorption, tube wall thickness, tube length and tube inner radius being equal, aluminum foam just filled bubble tube car bumpers energy aluminum filled tube 11, and the hollow metal pipe bumpers required a hollow metal tube 20, a tube filled with aluminum foam energy absorbing hollow metal tube with an increased absorption as compared to 82 percentage, so bumper filling tube of aluminum foam mass ratio of the hollow metal pipe 55 is reduced the percentage of the bumper. Automotive Compound, functional masterbatch technology research and new product promotion.
3. nitinol
Nitinol is a new material, with other materials do not have special properties, such as shape memory and pseudoelastic properties, etc., currently used in some car bumper inner panel and an outer panel. Titanium is a typical light metal, while the overall density of the nickel alloy is also much lower than the conventional steel, which has high specific strength and specific stiffness. Great restoring force due to the shape memory characteristic is generated further increases the overall performance of the material.
4. A polypropylene (PP)
Polypropylene (PP) having a lightweight plastic, a rich source of raw materials, excellent cost performance as well as excellent heat resistance, chemical resistance, easy molding, ease of recycling and other characteristics, it is widely used in automobile bumpers. However, there are also PP low impact resistance, aging resistance and poor dimensional stability defect, it is difficult to meet the automotive parts flexural strength and impact strength balance requirements.
Thus in a PP material used in automobile parts, mostly modified PP, i.e. PP alloy. Rubber-modified polypropylene-based polymer commonly used are polybutadiene rubber (BR), ethylene-propylene rubber (EPR), ethylene propylene diene rubber (EPDM), SBS, POE like. BR, EPR, EPDM-modified PP blends equal, can greatly improve the impact strength, in particular of EPDM PP similar structure and similar solubility parameters, good compatibility with EPDM and therefore the most widely used toughening PP, a blend of the magnitude of the impact of performance improvement is very significant.
Automotive bumpers PP / EPDM formed with high rigidity, good impact properties, scratch resistance, gloss, and better flexibility and ease of coating properties, easily broken by impact when the car at high speed, and beautiful decoration.
5.PC / PBT alloy
The material PC / PBT alloy is not only good mechanical properties, and higher impact strength than many elastomer-modified PP, and easy welding and painting. US companies such as GE’s PBT / PC alloy, which XenoyXT especially for car bumpers. DaimlerChrysler’s Town, Country and Caravan rear bumper of the car on the use of this type of plastic alloy. Currently the production of engineering plastics several large companies in the world.
6. The thermoplastic elastomer TPE (ThermoPlasticElastomer)
The world market adoption bumper TPE has occupied a 53 percent share. Since the modified PP or PC / PBT alloy is not conducive to recycling, the foreign car companies using a single thermoplastic elastomer (TPE) producing automobile bumper panels, and glass fiber reinforced PP produced with matrix material, they are due to the same family of materials is conducive to recovery and recycling use.
TPE can be processed using thermoplastic processing equipment, but its performance exhibit rubber-like elasticity, so it was called 3rd generation rubber material.
TPE material of low density, easily recycled, performance between the plastic and rubber. Current common car 4 have the following main categories: thermoplastic polyolefin elastomers (TPO), thermoplastic polystyrene elastomers (TPS), polyester elastomer (TPEE) and a polyurethane elastomer (TPU), there are slight differences between them, for different occasions.
3. Bumper with airbag
is currently abroad working on a bumper car with airbags, in order to reduce such accidents to a minimum, bumper not only decorative landscaping the role of the car, more importantly, play a security role. It is to make pedestrians from injury or mitigate the harm of passive safety device in the car with the emergency frontal collision.
The device consists of a sensor, the inflator and airbag and other components, and concentrated loaded into the bumper, the bumper at the moment a pedestrian hit, the bumper fall rapidly built push plate, to prevent pedestrians was knocked under the car, at the same time, a sensor mounted on the bumper is triggered. The ignition circuit is turned on, flashing a spark, igniting the solid fuel gas in an inflator, releasing large amounts of combustion of the fuel nitrogen and a high temperature of about 1000 degrees, the gas cooled by the cooler layer, into the filter, through the filter the cleaned gas is quickly charged into the built-in wedge-shaped balloon, forwardly open, hold the pedestrian is hit.
Meanwhile, both sides of the wing-shaped bumper airbag inflated to lift both sides, to prevent pedestrians rolling on the road, and controls the emergency braking cars embodiment. People in the crash could not instinctively protect themselves against this new type of passive safety devices can reduce injuries. Due to the rapid development of automobile industry, the growing number of cars, the accident is inevitable.