Development Of Key Dimension Measurement Equipment For Automobile Tailgate Screw Based On Machine Vision

As the transmission mechanism of trunk opening and closing,the screw rod of automobile tailgate is widely used in automobile industry.The quality of automobile tailgate screw is directly related to the failure rate and driving comfort of automobile tailgate,thus affecting the quality of automobile.Therefore,it is very important for the automobile industry to improve the quality of the tailgate screw.At present,manual sampling inspection is a common inspection method for the screw rod of automobile tailgate.This method can’t realize the full detection of automobile tailgate screw rod,and its detection results are greatly influenced by workers’ mood and state,resulting in product quality fluctuation.With the rapid development of optical components and measurement technology,the detection and measurement based on machine vision provides new opportunities for the above challenges.According to the measurement requirements of automobile tailgate screw rod,this paper develops a set of automobile tailgate screw rod measurement equipment based on machine vision,which has been successfully applied to a company in Shanghai.At present,it runs well,and plans to improve the automobile tailgate screw rod measurement equipment to adapt to the measurement of more types of parts.The major diameter and minor diameter of the screw thread of the automobile tailgate,the total runout of the top of the thread and the distribution of the spiral angle are the key factors to determine whether the trunk can be opened and closed smoothly.In addition,the total length of the tail door screw rod and the length of the knurled gear will directly affect the assembly feasibility of the tail door screw rod.In this paper,a multi-directional vision measurement method is proposed through reasonable layout design to measure the key dimensions of the screw rod of the automobile tailgate,such as the large diameter of the thread,the small diameter of the thread,the total run out of the top of the thread,the total length of the screw rod of the automobile tailgate,the distribution of the spiral angle and the length of the knurled gear.The main research contents of this paper are as follows:(1)Design of automobile tailgate screw rod detection equipment based on machine vision.Firstly,the core parameters and detection requirements of automobile tailgate screw rod are analyzed;Then,according to the testing requirements,the overall scheme of the automobile tailgate screw rod testing equipment is designed;Finally,the multidirectional imaging scheme of the visual inspection equipment is designed,and the visual hardware is selected.(2)Accuracy detection of motion module.The accuracy of the motion module is directly related to the detection accuracy of the equipment,so it is necessary to check the accuracy of the motion module before detection.The motion module is controlled to move,the moving distance of the motion module is measured by the visual system of the equipment,and the accuracy of the motion module is calculated by taking the visual measurement result as the actual moving distance.(3)Development of key dimension measurement algorithm for automobile tailgate screw rod.According to the obtained image of automobile tailgate screw rod,the corresponding measurement algorithm is designed for different measurement dimensions to realize the measurement of the key dimensions of automobile tailgate screw rod.(4)Development and performance verification of automobile tailgate screw measuring equipment system based on Lab VIEW.According to the requirements of automobile tailgate screw measuring equipment,the system development is completed,including three modules: login and management,screw measurement and measurement result query.Design verification experiments to verify the measurement accuracy and efficiency of the equipment,and analyze the error sources of the measurement results.