What is "welded" door? To put it bluntly, the "lower half of the car door" and the "window frame" are welded together, which is called "welded car door". Even if the door is welded, the lower part is "integrally formed", but the window frame is welded.
The "integrated door" is easier to understand. The "lower half" of the door and the "window frame" are stamped out in one piece, and there is no welding step. .
Friends who have worked in some iron works will understand very well that "stamping technology" has limitations. For example, when the "rigidity" and "thickness" of the "raw metal" are too strong, it is not suitable to adopt the "integrated stamping" technology at all. For example, some high-end models, such as 5 series, Mercedes-Benz E and so on. , use "welding" technology on the door. Because the material has a good texture, it can't be processed by "integrated stamping". The practice of high-end cars in Germany is to punch the lower half of the door at one time, and then weld the window frame and stiffener. The adoption of "integral stamping" must ensure that the steel has good ductility, while "good ductility" and "rigidity" must be reduced, and their nature is opposite.
To give a simple example, the vehicles with "integrated doors" include POLO, Jing Rui, Logo 206, Chevy Le Feng and converse. Will their safety factor be higher than that of German high-end cars? Safer than series 5 and class e? Of course that's impossible. As mentioned above, welding refers to "welding the window frame", and the lower part is also stamped. "Integral molding" is only the integration of the lower part and the window frame. So, is the design of Volkswagen CC without "window frame" unsafe? Most "super sports cars" in the world have no "window frames". Isn't it safer than an "integrated" door? The statement that "one-piece molding" is safe is a complete joke. The doors of high-end cars are generally welded, because "strong rigidity" and "large thickness" cannot be washed out by the process. As long as the "stamping" process is adopted, it can basically be judged that the "material" is not rigid.
Don't be so afraid of "welding technology". Tank armor is welded, and so is the deck of aircraft carrier. Whether it is a "tank" or an "aircraft carrier deck", it can withstand tremendous power. If "welding" is unsafe, then the "aircraft carrier" is likely to disintegrate. So don't always say "welding" the door is unsafe. The key is welding technology. High-end models with "thick door panels" and "strong rigidity" can't be punched at all, so they can only rely on welding. For some "low-end models", because of thin materials and low rigidity, the "one-piece molding" technology can be adopted.
Strictly speaking, there is no integrated metal body at present, because the structure of the body frame is complex, and no manufacturer can punch the whole metal plate into a cage body frame at one time. All parts of the car body are stamped with steel plates, then these parts are welded into the car body, and then the car body panels and various accessories are installed to assemble a complete car. Therefore, no matter how awesome the manufacturer is, his car should be welded.
However, some car body sides are not formed by stamping at one time, but by welding and splicing. As shown above. However, we have to say, however, this does not necessarily mean that such institutions are not strong. The above picture is said to be the body part of the old sagitar. Who will question the body strength of the old sagitar? The reason for this assembly is to decompose the collision energy of the car body. Using steel with different strength in different parts can achieve the design safety index. In serious collision accidents, passengers are guaranteed to suffer the least injury and impact through different degrees of collapse.
For the vehicle in the above picture, blue steel has the highest strength, followed by red and yellow. This can ensure that the yellow part of the front of the car deforms first and absorbs most of the collision energy, while the red cockpit components are firm and not easy to deform, which can better protect passengers, while the blue high-strength steel behind the front wheel is obviously designed to ensure the integrity of the cockpit in a small-area collision. For example, Toyota Rav4 was exploded last year, and 25% of the offset collision was qualified on the left side and unqualified on the right side. Is it because the steel on the left side is stronger?
So I think any fuselage design is scientific, and the difference lies in the requirements of different manufacturers for fuselage strength. A friend of mine is engaged in car sales. When a new car comes on the market, the manufacturer has a model training material, which is about the overall performance and selling points of the vehicle and the advantages of competing products at the same level. Simply put, it is to teach salespeople how to impress customers. Among them, I read his introduction, and the whole vehicle used the highest 960MPa high-strength steel. This value is not low, but some manufacturers are higher, thousands. In this way, the strength of 960 is not as good as that of 1000. So technology is on the one hand, and material is the key.