Research And Application Of Automatic Pre-welding Technology For Ignition Components Based On Image Recognition

With the advent of the "Made in China 2025",China has put forward higher requirements on manufacturing accuracy and automation.Small components have always been the bottleneck of the development of manufacturing industry because of their small size and high precision.Ignition component is a typical small component,which is often used in the ignition propulsion device of aerospace industry.Its electrical properties directly affect the response speed and stability of the device.The core process is to use very fine welding wire to weld the surface welding column of the component.At present,the welding process is mainly completed by manual,but manual welding requires high technical for workers,it is difficult to meet the demand of high quality and multi-batch products.Therefore,the research and development of automatic welding system for ignition components can achieve effective quality control for component manufacturing and improve the automation level of small component manufacturing in China.Aiming at the problem of automatic welding of ignition components,it can be divided into two steps: pre-welding step and welding step.The purpose of the pre-welding step is to adjust the posture of the ignition components placed arbitrarily by the workers and to bridge the welding wire.This step is the core step of automatic welding,which affects the accuracy and reliability of the whole welding process.Based on image recognition technology,this paper studies the key technology of pre-welding,designs and implements an automatic pre-welding system for ignition components,and the specific work is as follows.(1)Design the pre-welding system for ignition components.In order to realize the automatic pre-welding of ignition components,the mechanical design and electronic control design are designed in this paper.In the aspect of mechanical design,pre-welding is divided into four processes: surface treatment process,visual recognition process,posture adjustment process and bridge wire drawing process.The mechanical accuracy is guaranteed by using screw and coder,and the arrangement of motor is reduced by sharing moving axis,so the cost of equipment is reduced.In the aspect of electronic control design,the main control mode of industrial computer is used: camera takes pictures and transmits them to industrial computer through Ethernet network;industrial computer processes pictures,extracts information and transmits it to PLC through Ethernet network for motor control.(2)Establish the precision model of the pre-welding system for igniting components.This paper systematically considers the mechanical errors caused by installation and movement,and the visual errors caused by position and rotation detection.Mechanical accuracy and visual accuracy are combined to build the precision model of the pre-welding system of ignition components.So accuracy indicators can be provided to control the visual algorithm and system accuracy later in the paper.(3)Propose a high-precision position and posture detection algorithm for igniter image.Based on the proposed accuracy model,the position and rotation data parameters of ignition components are calculated by shape consistency filtering,sub-pixel contour recognition and iterative fitting algorithm.The pre-processing algorithm is used to extract the contour at the pixel level.The Zernike moment method is used to sub-pixelize the contour.An iterative contour fitting algorithm is developed based on the least square method to achieve high-precision posture detection of the ignition component image.(4)Based on the above theory,a pre-welding system for ignition components is developed and tested.This paper develops and implements the pre-welding system of ignition components based on image recognition,and the system is calibrated by Zhang’s calibration method.In this paper,the developed system is applied to production practice,and its workflow and system accuracy are analyzed.The bridge wire experiment shows that the system realizes the automatic pre-welding of ignition components,and the bridge wire accuracy meets the requirements of products.Considering the difficulty of automatic pre-welding of igniting components,this paper successfully develops the pre-welding system of igniting components based on the precision model and image recognition technology.The system effectively solves the difficult problem for manual production to meet the needs of high-quality and multi-batch products.This method can also be applied into the automated manufacturing of related small components,and has certain reference significance for the automated manufacturing of other small components.