Exemplification of Lightweight Semi-Trailers Trend Underlying.
Semi-trailers as the main force of logistics transportation, have gone through the development process from less to more, from crude to refined in the tide of rapid economic development. The high strength and light weight of semi-trailers have become the development trend of the industry, and the high strength and light weight pillars are one of the main components to achieve vehicle light weight.
Common lightweight pillars for semi-trailers
In order to achieve the lightweight and high strength of pillars, various manufacturers of semi-trailers have made some improvements to traditional pillars. This is mainly reflected in the pillar material, thickness, and structure, such as high-strength steel lightweight pillars, external plug-in pillars, and concave wide-body pillars. Taking the center pillar as an example, several common pillars are introduced below.
For general fence semi-trailers and grid semi-trailers, high-strength steel lightweight pillars and external plug-in pillars are used, with the characteristics of thin pillars and high strength (3mm thick Q550 material), canceling the internal cover plate and using a reinforcement plate to replace it, which reduces the weight of the pillars. The main body pillars are still pressed against the side beams, that is, the outside of the pillars is flush with the outside of the side beams. This is convenient for welding the pillar guard plates and strengthens the strength of the pillar and the frame.
For some open-door semi-trailers or lock-bar trailer vehicles, the strength of the above-mentioned pillars without inner cover plates is relatively small. Therefore, a concave wide-body pillar has been developed.
The main body of the pillar is formed by eight bends, and the concave structure on both sides of the pillar serves as a reinforcing rib for the pillar. In addition, the pillar is directly welded to the frame side beam, and the outside is reinforced with a protective plate, so the strength of the pillar is greatly improved. However, due to its structural characteristics, the width of the pillar is generally more than 300mm to be formed. When combined together, the main body pillar is still pressed against the side beam, and the outside of the pillar (with the concave part reinforced by the plate) is flush with the outside of the side beam. Moreover, the concave structure occupies the volume of the semi-trailer container, reducing the loading capacity when loading bulk cargo.
New type of pillar for semi-trailers
Analyzing the structure and characteristics of the above common pillars, in order to meet the requirements of high strength and light weight of trailers, and based on the characteristics of the bulk-grid semi-trailer and the bulk-open door semi-trailer, some manufacturers have developed a convex wide-body pillar.
The convex wide-body pillar combines the advantages of the above external plug-in pillar and concave pillar. The main body of the pillar is externally convex in the middle, and the convex platform on the sides acts as a reinforcing rib for the pillar. More importantly, the external convex part can increase the volume of the trailer container.
At the same time that the pillar is welded to the frame side beam, the external convex part is welded and reinforced with a "plug" and a "plug reinforcement box" on the outside of the side beam. The upper end of the pillar is welded to the upper side body as usual. The external convex part is reinforced with a "side body reinforcement box" on the outside of the side body, which also enhances the strength of the pillar as a whole. This structure requires that the pillar be a wide-body pillar, which can be achieved with a width of more than 300mm.
In addition, the "step" on both sides of the convex wide-body pillar is designed to meet the welding position of hinges or hinges of the trailer container door. If it is used for vehicles that do not require welding handles or hinges, the "step" of the convex wide-body pillar can be cancelled, and the thickness of the pillar side can be increased as a whole (that is, the pillar side width is d1 + d3), which can further increase the volume of the trailer container beyond the outside of the side beam.
Let's do some calculation on how the lightweight pillars can improve freight transportation: Assuming that each pillar is 300mm wide, 40mm high and 150mm wide, and the height of the pillar is 1800mm, with 10 pillars per trailer. Then, we can calculate that the increased volume of each pillar is 40mm × 150mm × 1800mm = 0.0108mm³.
If the cargo being transported is lime, which has a density of about 3.25 to 3.38 (here we take 3.3), then the added weight can be calculated as: 0.0108 × 10 × 3.3 × 1000 = 356.4kg. Subtracting the increased weight of the external convex pillar and the reinforcement plate, which is about 40kg, we can conclude that each trailer can carry about 300kg more lime.