The dissimilar galvanized steel sheets with thickness of 0.7 mm St17E and FC180/340HD for car door were tested and studied for laser welding process. The effects of key process parameters (laser power and welding speed) on the weld surface morphology and weld cross section were investigated. The microstructure and mechanical properties of welded joints were analyzed and evaluated. The results indicate that when the laser power and welding speed are 1 300 W and 2.0 m/min respectively, there are less welding spatters and the weld surface is smooth. As the laser power increases and the welding speed decreases, the weld penetration depth and weld area increase. For the dissimilar galvanized steel sheets welded joint, the hardness of the St17E base metal is the lowest, and the hardness of the weld zone is much higher than that of the base metal zone. The tensile specimen of the welded joint obtained with optimized parameters fractures in the St17E base metal.

The current cleaning solvent has the problem of endless cleaning for the long used automobile base coat pipeline. In this paper, the principle of paint remover was applied to the cleaning of automobile paint pipelines. A cleaning solvent and its corresponding cleaning program with benzyl alcohol and lye as the main agents and ethylene glycol butyl ether, isopropyl alcohol and ethyl acetate as auxiliary agents were developed to realize efficient cleaning of paint transfer pipelines. The results show that, compared with traditional cleaning solvents, this formula is not only suitable for water-based paint topcoat systems, but also for solvent-based topcoat systems, and the cleaning effect of long-term used pipes is greatly improved, the cleaning time is shortened by more than 50%, the cost of cleaning materials and VOC emissions are reduced by 50%, and the cleaning efficiency of the paint transfer system is effectively improved.

A complete visual inspection system based on YOLOv5 combining with PLC, RFID, Python, OpenCV and DingTalk, was designed to replace manual inspection and recognition of the installation status of automotive parts. Accuracy and recall rate of the sample models trained in this system are both above 98%. From actual operation observation, the probability of identifying and accurately reminding is above 99%, and it meets the requirements of production takt, superior to the actual results of current manual detection, with low cost and good economic promotion.

This paper introduced the planning layout, equipment composition, process flow and application prospect of the workstation through survey and research on the CMT arc welding workstation of the new dual-machine coordinated robot with positioner. In combination with the application description of the emerging technology of arc welding quality tracing system and arc welding visual guidance system in arc welding process, this paper expounded how to solve the problems of low robot utilization rate, low welding efficiency and poor control of weld quality of traditional arc welding workstation. The purpose of improving and optimizing of arc welding process, in-depth research and development has been realized, and the efficiency and intelligence of arc welding workstation have been improved.

To solve the problems existing in the selection method of typical test conditions of the traditional load spectrum, this paper explored the potential relationship between process parameters by fuzzy clustering analysis, and realized the classification and primary selection of operating conditions data, meanwhile, the fuzziness of the classification process was fully considered and the subjective randomness of the preliminary selection of the scheme was avoided. On the basis of the preliminary selection results, the Analytic Hierarchy Process (AHP) was introduced to comprehensively consider the 4 comprehensive evaluation indexes, namely, the typicality and comprehensiveness of the selection of test conditions, the economy of the test and the amount of spectral data. The hierarchical structure model of the system was established, and the representative test conditions were selected by combining qualitative analysis and quantitative calculation, thus improving the scientificity and systematization of the selection of typical test conditions.

Based on the technologies of vision detection, Automated Guided Vehicle (AGV) transmission, industrial robot intelligent grasping and automatic tightening, the automatic assembly efficiency, assembly quality and flexibility of welding and adjusting door cover have been greatly improved. The multi-channel cameras were integrated on the grab, and the key feature points were identified and extracted by taking photos of the door cover and the body-in-white, and the clearance and difference of each position between the door cover and the body-in-white were calculated, and then the clearance and difference matching algorithm was adopted to calculate the best position of the door cover relative to the body in white, then the transfer robot was guided to grab the door cover to reach the best assembly position. The door cover was tightened automatically by the tightening robot carrying the tightening shaft. The door cover automatic assembly technology not only improves the assembly efficiency and quality, but also reduces the labor load and cost, and ensures the overall appearance quality of the body-in-white.

In this paper, based on the poor dimension matching accuracy of engine hood caused by the deformation of gas springs acting on the hood, through the simulation analysis of CATIA three-dimensional virtual assembly, and using MATLAB to numerically optimize the installation parameters of gas springs, reasonable design parameters of gas spring were worked out, and then corresponding design changes were made, and the assembly effect on the real vehicle was verified, controlling the dimension matching accuracy of engine hood within the target range. For the design parameters’ change law of the engine hood gas springs, the following conclusions can be drawn: (1) the more front gas springs are installed on the engine hood, and the more backward gas springs are installed on the vehicle body, the larger the elastic force ratio of gas springs is; (2) the more front gas springs are installed on the engine hood, and the more front gas springs are installed on the vehicle body, the larger its travel S is; (3) in order to improve the deformation problem of the gas springs acting on engine hood, the gas springs should be installed as front as possible on the engine hood, on account of reducing the maximum compressive force.

Bolt connection is the most commonly used connection technology in automobile industry, its connection failure is a common problem in automobiles, in particular, bolt looseness is the most common problem. Through the research on self-tapping locking bolt, it is found that it has the advantages of high connection reliability, repeated use and low system cost. Through the bolt assembly process development, the difference of torque-clamping force relationship with ordinary bolts was distinguished, the assembly process parameters were determined and reliable bolt connection was realized.

The assembling and commissioning of high voltage parts of the new energy vehicle prototype is divided into 3 steps, i.e. pre-test, test and electric test. 14 control items including power battery, motor, high voltage wiring harness, high-voltage control system, other high-voltage parts, vehicle insulation resistance, vehicle potential balancing, oil & fluids filling, commissioning preparation, commissioning procedure, were analyzed and studied comprehensively through 3 steps, forming a set of prototyping & commissioning method for high-voltage parts of new energy vehicles.

Using the traditional personnel beat calculation method usually can only calculate the approximate time, which is quite different from the actual result. This paper elaborated the principle of Methods-Time Measurement (MTM) calculation method, through the MTM analysis, accurate calculation of worders load of the welding line, at the same time introduced different kinds of feeding ports of the automobile welding line and analyzed its advantages and disadvantages. According to the calculation results of MTM, this paper proposed the optimization scheme of the worker number on the welding line and the form of feeding port to ensure the rationality of the workers number and improve the efficiency of the factory.