| Minicars assembly manufacturing is the main task of each component parts assembled into the whole car, and almost all of the assembly parts are closely related with screw thread connection. Thread connection structural reliability relates to the overall performance of the car, especially,the high-strength thread connections of chassis and other parts of the car are related to the driving safety. Aiming at high strength bolt looseness problem of a mini car company, this paper combined with domestic and foreign research results, using a combination of theoretical calculation and simulation analysis method to analyze the factors affecting the properties of bolt locking. Then having study on the influence factors of loosening with vibration experiment to find enhancement method of bolt fastening performance.Finally, classifying the connection’s security of micro-vehicles with high-strength bolts, using theoretical analysis and experimental research to propose locking improvements on the part of key location connection, having improved the properties of high strength bolt and effectively control production costs.This paper research content consists of the following several aspects: 1) Having a systematic analysis of the force on the bolt, the bolt stress model was established, Analysis of loosening causes of threaded connections from many angles, and finally proposed measures of anti-loosening in four aspects which are bolted friction inherent characteristics, fastening systems, stability of the preload as well as the new structure. 2) Using ABAQUS to simulate the dynamic vibration processes of threaded connections, analysis of minicars commonly used different bolt head combination and the influence of different friction coefficient of residual stress of bolt connection, found its effect on the properties of locking. 3) Selecting multiple variables for experimental study on transverse vibration of high strength bolts, obtained key factors affecting anti-loosening performance of high-strength bolts, which found that the bolts with spring washers have not improved anti-loosening performance significantly, and the result provides guidance for micro assembly cost control. 4) Divided the security levels to high strength bolts in accordance with the degree of impact on vehicle safety and corresponded to some parts of micro-car assembly positions. Analyze locking way of the key points which frequently loosed and proposed the locking improved method. |
