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4 axle lowbed semi trailer manufacturer in China is a special transport vehicle for construction machinery such as crawler excavators, road rollers and pushers. It has the advantages of improving transportation efficiency and ensuring transportation safety. The frame is the main bearing part of the low-bed semi-trailer, and its structure directly affects the performance of the vehicle.
4 axle lowbed semi trailer manufacturer in China is a special transport vehicle for construction machinery such as crawler excavators, road rollers and pushers. It has the advantages of improving transportation efficiency and ensuring transportation safety. The frame is the main bearing part of the low-bed semi-trailer, and its structure directly affects the performance of the vehicle. In this article, low-plate semi-trailer is analyzed, and its strength and stiffness are analyzed by finite element theory.
The frame of the 4 axle lowbed semi trailer manufacturer in China is a welded joint composed of 2 longitudinal beams, 13 transverse beams, 18 wing beams and 2 side beams. In order to ensure the transportation safety of crawler-type construction machinery, the height of the bearing surface should be reduced as much as possible in the design. Therefore, the frame adopts a concave beam structure.
The longitudinal beam is the main load-bearing part of the frame and it is subjected to large bending stress during the driving of the car. In order to meet the needs of the low-bed semi-trailer, the longitudinal beam adopts a stepped structure, the section is I-shaped with material of 16Mn. To ensure that there is enough space for the hoisting device and the suspension system, the gooseneck is designed to have a variable cross-section and the height of the suspension support is as small as possible for 4 axle lowbed semi trailer manufacturer in China.
For 4 axle lowbed semi trailer manufacturer in China, the height of the main section of the longitudinal beam is 500mm, the height of the goose section is 400mm, and the height of the suspension support is 320mm. The width of the upper and lower wings of the longitudinal beam is 180mm with thickness of 20mm .The thickness of the web is 8mm or per customer’s request.
Due to the small height dimension of the longitudinal beam at the part of the suspension support, the support reaction force at this part is relatively large. In order to ensure sufficient strength in this area for 4 axle lowbed semi trailer manufacturer in China, the inner and outer reinforcement plates and the lower reinforcement plates are arranged here. The inner and outer reinforcement plates are welded with the I-beam to form a box-shaped structure. There are several plug welding holes on the lower reinforcement plate, which are connected to the lower wing surface of the I-beam through plug welding and break welding on both sides.
In order to reduce stress concentration, the ends of the inner and outer reinforcement plates are designed into a U-shaped structure. The end of the lower reinforcement plate adopts a 45° inclined plane and the end of the lower reinforcement plate and the end of the inner and outer reinforcement plates are avoided for 4 axle lowbed semi trailer manufacturer in China.
The cross beam is used to connect the left and right longitudinal beams in the frame and constitute the main component of the frame. The torsional performance of the beam itself and its distribution directly affect the internal stress of the longitudinal beam and its distribution. Reasonable design of the beam can ensure that the 4 axle lowbed semi trailer manufacturer in China frame has sufficient torsional rigidity.
4 axle lowbed semi trailer manufacturer in China has a 4 rear axle structure and adopts a 4 axle balanced suspension system. The front middle and rear suspension supports are directly welded to the lower side of the longitudinal beam. When the car is running, the suspension part of the frame bears a large torsional stress. Three box-shaped beams with larger cross-sectional dimensions are set at the front, middle and rear supports. This way, it is ensured that the frame has sufficient torsional rigidity and can transmit the load more ideally.
Due to the high torsional stiffness at the traction pin and rear axle, the deformation in the middle of the frame tends to be large. In order to allow the frame to have a slight warpage, I-shaped beams are welded to the longitudinal beam web that are arranged in the middle of the frame. The beam spacing is 800 mm for 4 axle lowbed semi trailer manufacturer in China.
The joint stiffness of the connection between the beam and the longitudinal beam directly affects the overall stiffness of the frame, and the rational design of the node structure of the beam and the longitudinal beam is a serious problem in the design of the frame. There are usually two forms of connection between beams and longitudinal beams.
The advantage of the structure that the beam is connected to the upper and lower airfoils of the longitudinal beam is that it is beneficial to improve the torsional rigidity of the frame, but the disadvantage is that in the case of severe torsion, the longitudinal beam flange will have a large stress. Due to the small torsional deformation of the traction pin and the suspension support of the frame, this continuous pressing method is adopted in this part, and a diagonal brace is added at the rear beam of the traction pin to improve the torsional rigidity of the longitudinal beam of the 4 axle lowbed semi trailer manufacturer in China.
The beam is only connected to the web of the longitudinal beam. This structure has poor rigidity and allows free warping of the longitudinal beam section without restraint torsion. Because the middle part of the frame is deformed greatly, this connection method is adopted.
Since the gravity of the construction machinery acts on the left and right sides of the bearing surface of the frame through the crawler, for this reason, 18 variable-section equal-strength spars are symmetrically arranged on both sides of the longitudinal beam. The spar section is I-shaped with a spacing of 400mm.
In order to meet the needs of crawler-type construction machinery transportation, the frame of 4 axle lowbed semi trailer manufacturer in China is designed to be a special structure with extra width (referring to the width limit specified by the national standard) according to the size of the crawler. A box-shaped bracket with a larger cross-sectional size is set at the front, middle and rear suspension supports. The height of the bracket is equal to the diameter of the tire. The tire and the bracket bear the load until the construction machinery travels.
In order to make the bottom plate of the frame have certain elasticity and prevent the track from slipping, the frame adopts a wooden bottom plate in the load-bearing part and patterned panel for the rest of the frame. Anti-skid ribs are arranged appropriately to ensure safe transportation. On the 4 axle lowbed semi trailer manufacturer in China, the wooden base plate is connected to the beam with countersunk head screws.
4 axle lowbed semi trailer manufacturer in China is a special transport vehicle for construction machinery such as crawler excavators, road rollers and pushers. It has the advantages of improving transportation efficiency and ensuring transportation safety. The frame is the main bearing part of the low-bed semi-trailer, and its structure directly affects the performance of the vehicle.
4 axle lowbed semi trailer manufacturer in China is a special transport vehicle for construction machinery such as crawler excavators, road rollers and pushers. It has the advantages of improving transportation efficiency and ensuring transportation safety. The frame is the main bearing part of the low-bed semi-trailer, and its structure directly affects the performance of the vehicle. In this article, low-plate semi-trailer is analyzed, and its strength and stiffness are analyzed by finite element theory.
The frame of the 4 axle lowbed semi trailer manufacturer in China is a welded joint composed of 2 longitudinal beams, 13 transverse beams, 18 wing beams and 2 side beams. In order to ensure the transportation safety of crawler-type construction machinery, the height of the bearing surface should be reduced as much as possible in the design. Therefore, the frame adopts a concave beam structure.
The longitudinal beam is the main load-bearing part of the frame and it is subjected to large bending stress during the driving of the car. In order to meet the needs of the low-bed semi-trailer, the longitudinal beam adopts a stepped structure, the section is I-shaped with material of 16Mn. To ensure that there is enough space for the hoisting device and the suspension system, the gooseneck is designed to have a variable cross-section and the height of the suspension support is as small as possible for 4 axle lowbed semi trailer manufacturer in China.
For 4 axle lowbed semi trailer manufacturer in China, the height of the main section of the longitudinal beam is 500mm, the height of the goose section is 400mm, and the height of the suspension support is 320mm. The width of the upper and lower wings of the longitudinal beam is 180mm with thickness of 20mm .The thickness of the web is 8mm or per customer’s request.
Due to the small height dimension of the longitudinal beam at the part of the suspension support, the support reaction force at this part is relatively large. In order to ensure sufficient strength in this area for 4 axle lowbed semi trailer manufacturer in China, the inner and outer reinforcement plates and the lower reinforcement plates are arranged here. The inner and outer reinforcement plates are welded with the I-beam to form a box-shaped structure. There are several plug welding holes on the lower reinforcement plate, which are connected to the lower wing surface of the I-beam through plug welding and break welding on both sides.
In order to reduce stress concentration, the ends of the inner and outer reinforcement plates are designed into a U-shaped structure. The end of the lower reinforcement plate adopts a 45° inclined plane and the end of the lower reinforcement plate and the end of the inner and outer reinforcement plates are avoided for 4 axle lowbed semi trailer manufacturer in China.
The cross beam is used to connect the left and right longitudinal beams in the frame and constitute the main component of the frame. The torsional performance of the beam itself and its distribution directly affect the internal stress of the longitudinal beam and its distribution. Reasonable design of the beam can ensure that the 4 axle lowbed semi trailer manufacturer in China frame has sufficient torsional rigidity.
4 axle lowbed semi trailer manufacturer in China has a 4 rear axle structure and adopts a 4 axle balanced suspension system. The front middle and rear suspension supports are directly welded to the lower side of the longitudinal beam. When the car is running, the suspension part of the frame bears a large torsional stress. Three box-shaped beams with larger cross-sectional dimensions are set at the front, middle and rear supports. This way, it is ensured that the frame has sufficient torsional rigidity and can transmit the load more ideally.
Due to the high torsional stiffness at the traction pin and rear axle, the deformation in the middle of the frame tends to be large. In order to allow the frame to have a slight warpage, I-shaped beams are welded to the longitudinal beam web that are arranged in the middle of the frame. The beam spacing is 800 mm for 4 axle lowbed semi trailer manufacturer in China.
The joint stiffness of the connection between the beam and the longitudinal beam directly affects the overall stiffness of the frame, and the rational design of the node structure of the beam and the longitudinal beam is a serious problem in the design of the frame. There are usually two forms of connection between beams and longitudinal beams.
The advantage of the structure that the beam is connected to the upper and lower airfoils of the longitudinal beam is that it is beneficial to improve the torsional rigidity of the frame, but the disadvantage is that in the case of severe torsion, the longitudinal beam flange will have a large stress. Due to the small torsional deformation of the traction pin and the suspension support of the frame, this continuous pressing method is adopted in this part, and a diagonal brace is added at the rear beam of the traction pin to improve the torsional rigidity of the longitudinal beam of the 4 axle lowbed semi trailer manufacturer in China.
The beam is only connected to the web of the longitudinal beam. This structure has poor rigidity and allows free warping of the longitudinal beam section without restraint torsion. Because the middle part of the frame is deformed greatly, this connection method is adopted.
Since the gravity of the construction machinery acts on the left and right sides of the bearing surface of the frame through the crawler, for this reason, 18 variable-section equal-strength spars are symmetrically arranged on both sides of the longitudinal beam. The spar section is I-shaped with a spacing of 400mm.
In order to meet the needs of crawler-type construction machinery transportation, the frame of 4 axle lowbed semi trailer manufacturer in China is designed to be a special structure with extra width (referring to the width limit specified by the national standard) according to the size of the crawler. A box-shaped bracket with a larger cross-sectional size is set at the front, middle and rear suspension supports. The height of the bracket is equal to the diameter of the tire. The tire and the bracket bear the load until the construction machinery travels.
In order to make the bottom plate of the frame have certain elasticity and prevent the track from slipping, the frame adopts a wooden bottom plate in the load-bearing part and patterned panel for the rest of the frame. Anti-skid ribs are arranged appropriately to ensure safe transportation. On the 4 axle lowbed semi trailer manufacturer in China, the wooden base plate is connected to the beam with countersunk head screws.
