With the rapid development of the plastic industry and automobile industry, the variety and application range of automotive plastics are expanding for the consideration of economy, safety, and environmental protection. Due to the superior performance of plastics, many plastics are used in automobile design, which can not only meet the design performance requirements of automobile structure, such as lightweight, safety, corrosion prevention, modeling, and comfort but also help to reduce costs and save energy. At the same time, the application of plastics in automobiles is mainly divided into three categories: exterior parts, interior parts, and functional and structural parts.
Today we will mainly explain the bumper in the car part. It not only makes the body beautiful and generous but also protects the body, fenders, radiators, hood, lamps, and other components and passengers when the car collides with other cars. Safety. In the event of a minor collision, the bumper system can absorb the impact energy and automatically return to its original state; in the event of a serious collision, the impact force is reasonably distributed to the entire body through the bumper system to avoid excessive deformation in local areas and protect the personal safety of passengers. The structural design of automobile bumpers not only affects the safety of drivers and passengers but also affects the durability of product use. Therefore, for the humanized and personalized development of the overall design, the function and concept of the bumper have also developed from the single protection of the car to the aesthetics of the car body, the coordination of the overall decoration, the reduction of the wind resistance coefficient and the improvement to driving maneuverability. Over time, the manufacturing process of bumpers has become more and more mature.
Features of Rapid Prototyping of Car Bumper:
(1) Molding Machining:
Now bumpers are generally made of modified polypropylene resin material. The injection molding machine uses a heating barrel to melt the resin and then pushes the molten resin into the mold. After the resin cools down, the mold is opened, and the product is taken out.
(2) Injection Molding Machining diagram:
Molding cycle: in the continuous production process, the time required to complete one mold production, molding cycle = WET TIME + DRY TIME WET. TIME (wet cycle): the processing time of product molding, which is composed of injection time + pressure holding time + cooling time, and is mainly affected by product structure, material, mold structure, and other factors. DRY TIME (dry cycle): the running time of the equipment, mold opening and closing time + take-out time + ejection time + metering time are mainly affected by the performance of the injection molding machine.
The following datasheet takes the molding cycle of the Honda CIVIC front bumper as an example, its weight is 4.3KG, and the cycle is 46.3 seconds.
(3) Equipment Features：
In order to achieve high cycle time, Mitsubishi Heavy Industries and Honda Technology Co., Ltd. cooperated to develop a 3000-ton injection molding machine. It adopts a two-plate hydraulic mold clamping structure and servo motor electric pre-molding. It can realize the synchronization of mold opening and plasticizing actions. The core oil circuit structure and the characteristics of the Honda mold can be well matched.
(4) Material characteristics：
Now bumpers are generally made of modified polypropylene resin materials because polypropylene is widely used in the front and rear bumpers of cars because of its excellent cost performance. Since the world's first bumper was made of blended materials, polypropylene has been widely used as a new and inexpensive general-purpose plastic in the automotive field. At present, more than 80% of the bumpers in the world are made of polypropylene-based TPO materials. , According to the requirements for the use of automobile bumpers, the development and development of bumper materials can be divided into three stages. Please see the following development stages of polypropylene materials for automotive bumpers:
(5) Mold requirements：
In order for the mold to adapt to a high rhythm, it needs to meet the following two conditions: ① The structure of the mold cannot be too complicated, and the action is simple and compact in the process of opening and closing the mold. ② The cooling effect of the mold is good, and it can be cooled to more than 200 ℃ in about 10 seconds. The melt is cooled to the surface 80-90 ℃ state. The material is required to have excellent thermal conductivity, and the mold design should also facilitate the arrangement of water channels. Now the bumper mold structure basically has two main structures, inner parting, and outer parting. The inner parting is mainly used by European and American car manufacturers. Its main feature is that to ensure product quality, the parting line is designed on the B side of the mold. The machining error or the flash generated after the mold is used for a long time will not affect the appearance of the product. The main reason is that the mold is complicated, usually 30-40 tons, and the product cycle is generally more than 60 seconds. Japanese car factories usually use the outer parting structure. The parting line is on the front of the product. In order to ensure the appearance quality, high requirements are placed on the mold processing, but the mold structure is simple, and the fastest cycle can reach less than 40 seconds.
The above is a brief introduction to the production and related information of car bumpers, but for the future development trend. The competition for cars is becoming more and more fierce, both high quality and low cost are required, so high-efficiency production is the unremitting pursuit of various auto parts processing plants. Many new technologies are being developed around this topic, such as low-pressure injection molding technology, thin-wall bumper design chemical, all-electric injection molding machine, etc.
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