When our car body was inspected, we found that the car skeleton was deformed, so we had to correct or replace the car body. The following small series will introduce you to the damage identification, body replacement and underbody correction of the accident car body. [Body Inspection] Generally, the frame is a part of the body, and the equilateral beam structure is mostly adopted. The front and rear beams of the equilateral beam are connected with the torsion frame through the two sides (side beams) of the middle car. When the chassis is impacted by external force, it is easy to be damaged at the bend. Different structures, different impact positions and impact forces will cause different damage. The collision of the car body may cause irregular creases on the stamped sheet metal. The car body was badly damaged in the accident and needs to be repaired. [Accident Body Damage Appraisal] For the car damaged by the accident, it is necessary to find out the speed, collision position and direction of the car at the time of the accident. You can also combine the test run and measuring instruments to conduct a comprehensive inspection of the car to confirm whether the bottom of the car is deformed, whether the whole car body is damaged or distorted, and whether the door can be opened freely. So as to determine the damage degree and repair method of the car. [Body replacement] When the car is seriously damaged, you can consider replacing the whole body. When replacing the car body, all available assemblies and parts can be removed from the damaged vehicle and reassembled into a new car. After the new car is installed, it must undergo thorough inspection, adjustment and road test before it can be put into use. [Partial body replacement] When the car is partially damaged, such as the front and rear fenders, doors, hood or trunk lid, you can consider partially replacing the car body to save time and money. According to the degree of damage, the damaged body panel can also be repaired separately or treated as scrap iron. [underbody correction] When the underbody is deformed, it can be repaired by correcting the underbody and the body. At the bottom of the car body without a frame, there is a punched locating pin hole. The locating hole on the floor of the car body is the locating reference when the car body is welded, which is used to determine the placement position of the engine powertrain and the front suspension. After correcting the underbody, repair the body sheet metal parts. [Body Side Plate Correction] When the side of the car is damaged, traction method can be used to correct the underbody and body. Repair the large area deformation first, and then repair the body side sheet metal parts. [Door post replacement] When the door post, windshield post, front wall post or rear wall post are seriously damaged, the damaged door post can be replaced by replacement method, and relevant parts can be corrected. Repair the joint after welding the reinforcement pillar. [Use of Hydraulic Molding Machine] If the car body is hit and twisted and the damage is not too serious, it can be corrected by hydraulic molding machine. Need to restore the shape of the roof, doorposts and suitcases.