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In contrast to the United States, long head trucks are extremely rare in the country. Flat-head trucks are widely used in the market; if the time goes back to 20 years ago, the domestic transportation market was still dominated by long trucks. Then, in this 20 In the time of the year, what happened to the long trucks gradually withdrawing from the mainstream? Let us analyze it together. 
What models relevant policy guidance is the main reason <br> <br> truck belonging to the operation of vehicles, not just China will be policy interventions, the situation is similar in other countries, a national or regional policies on the use of commercial vehicles have a great tendency Impact. U.S. long-headed vehicles have thrown away geographical and environmental factors. Regulations and policies are also a kind of support for the long head. The length of the entire vehicle only calculates the space for carrying goods, and the space for non-carrying goods at the front of the vehicle does not count toward the length. Although there is no North American law that prohibits the use of flat-head trucks, it is rumored that some traffic police will “specially care for†flat-head trucks. The reason is that flat-bottom cars are not safe. Under the influence of unspoken rules, these people with flat cars will also prefer long-term trucks. Cars, don't make yourself look different.
On the other hand, in China, GB1589-2004 "Outline dimensions, axle loads and quality limits for road vehicles" clearly describes the requirements for the length of trucks. "Since January 1, 2008, and the overall closed box semi-trailer When the composed articulated train is used on a high-grade highway, the maximum limit of the vehicle length is 18,100mm;". Should standard container transportation be extended to the domestic transportation environment that widens and increases the loading space. Is it even more serious to use long trucks with longer dimensions? In accordance with one rule, it will destroy a large group of people who admire the large space of American long head cars.
Domestic conditions are limited, long models are not competitive?
The road environment needless to say, in some parts of the country, it is very difficult for flat cars to drive in. The blind spot of the American long head carriage is also an influence. Drive to wait to have a 360-degree panoramic view to avoid electric cars and pedestrians. One thing is ignored by many people. The mainstream type of vehicle will also affect the road design. There are many long-trailers in North America, and the construction of urban roads will reserve sufficient turning radius to facilitate long-wheel turning. 
Apart from external factors, the lack of competitiveness of domestic long trucks is also the main reason. In recent years, the domestic logistics market has developed rapidly. The demand for vehicles in the market is getting higher and higher. The imported vehicles with stable quality are not as bad as those in previous years. Vehicle comfort, aesthetics and dynamics are valued by truck drivers. In a word, it is more and more attention to vehicles. Flat-head trucks are growing at a fast speed. Liberation of J6, Dongfeng Tianlong, CNHTC, and Auman GTL are epoch-making products of domestic cars. However, there are fewer long-head car manufacturers and the low-end models are already incompatible with the user groups. The request. No high-powered engine, ugly shape, simple interior is destined to be long-term domestic products at the time can only be low-end products, such as Liuzhou Longka, Liberation Ansett production of a series of models.
Although the long head of the truck also occasionally show his face at the show, but are short-lived <br> <br> although the policy does not support long-trucks, some manufacturers have tried or trial of high-end domestic long trucks. At the 2011 Shanghai Auto Show Dongfeng Commercial Vehicle Booth, there was a long truck with a black Dongfeng Tianlong. At that time, it was a debut that attracted everyone's attention. The shape design of the vehicle continues the Dongfeng Tianlong's iconic front face style. Even if it does not carry the Dongfeng standard, it can be guessed that it is a Dongfeng truck.
According to Fan engineers who created it, Tianlong long-vehicle cockpit is based on Dongfeng Tianjin size design, but the vehicle space is not lost to the Tianlong model. Engine, transmission, axle power chain assembly and headlights, rearview mirrors, instruments and other interior and exterior trim parts are all common with Dongfeng Tianlong, and volume production will not be delayed due to accessories. The horsepower DCI engine and Dongfeng Tianlong use the same model, and the power configuration is not inferior to any domestically-made flat-head truck. The disadvantage of weak domestically-made long-powered vehicles is totally invisible in Dongfeng. 
The air suspension of the vehicle and the airbag suspension mechanism of the cab can be switched between 4x2, 6x2, and 6x4. The last axis can also be airbag lifted to admire the brain hole of the engineer. The car has 220V power jacks, microwave ovens, car water dispensers and other comfort configurations, comfort has been killing the same period flat truck. Unfortunately, in the past 5 years, Dongfeng still did not mass-produce this long-headed truck. It was only a flash in the Shanghai auto show. Many people who wanted to buy a car saw news reports watching the currency and hoped to buy Dongfeng Tianlong long heads. car. Once again verifying the good product will have market demand.
China National Heavy Duty Truck, the boldest new technology application in domestic truck brands, also displayed a "Deterrence" 6x4 long-haul tractor at the 2012 First Wuhan Commercial Vehicle Show one year later. The car is based on the heavy truck HOWOA7 model transformation, in the heavy truck A7 cab on the basis of pulling out a "long nose", front face headlights and grille shape consistent with the A7, but also with a strong family face characteristics. The appearance of the heavy truck deterrence design is not as good as that of the Dongfeng Tianlong long-distance car, and it is much better than the low-end domestic long-end car.
In terms of power configuration, Weihao can select the WD series of heavy-duty engines, the power chain and HOWOA7 are the same, the heavy-duty steam manual transmission and the MAN technology MCY13Q rear drive axle. The cab has a completely flat floor A7 style, light yellow main colors, wrap-around instrument panel, and the space is much larger than the Dongfeng Tianlong Long Header. Unfortunately, deterrence is finally gone.
In terms of vehicle configuration, Dongfeng Tianlong Long Header and CNHTC Deterrence Long Header are in line with the transportation environment at that time. The comfort of the vehicle is consistent with the end-users' needs. The high-power engine configuration and the growing high-speed logistics trend It is consistent. Constrained by the policy at that time, it was unwise for manufacturers to make great efforts to produce long cars. Only a small number of users had the demand for purchases, and the two cars were somewhat untimely.
Milling, boring, drilling, reaming, tapping and other processes are also used in regular mold processing.
The main material of the mould is high-quality alloy steel. Some moulds with a long service life are often made of Crl2, CrWMn and other ledeburite steels. The production and processing of this material is very strict, so the processing process cannot be ignored. The thermal deformation treatment is also an aspect that needs to be taken seriously in the processing. To sum up, when selecting the airport, the processing conditions should be met as much as possible, such as strong functionality, high accuracy of machine tool, good rigidity, good thermal stability, and anti-type function.
Some surface shapes are composed of multiple curved surfaces, such as automobile cover parts, aircraft, parts, toys, household appliances, etc., so the surface of the mold cavity is very easy to be complicated, and some can be processed through mathematical calculation.
Some molds have neither drawings nor data in the production process, and can only be imitated through physical objects, which requires high imitation accuracy and no deformation.