Research On Narrow Gap Vertical Welding Based On Oscillating Arc Sensor

At present,large-scale welding components are becoming more and more popular,especially in large-scale manufacturing heavy industry such as large pressure vessels,hull manufacturing structures,marine industrial engineering,nuclear power industry and pipeline engineering.Medium and heavy plate welding is becoming more and more popular,and narrow gap welding is unique.The advantage has made it become the preferred welding technology in the production of modern heavy equipment,occupying a pivotal position.However,the difficulty of narrow-gap sidewall welding and the narrow gap weld tracking problem are still the development difficulties of narrow-gap welding.Vertical welding is an important part of all-position welding.The molten pool metal is affected by gravity,causing the molten pool to flow and weld.The occurrence of welding defects such as seam not forming and high weld height is further increased the difficulty of narrow gap welding.In view of the above problems,some research had been conducted in thesis from the following aspects,the specific research contents are summarized as follows:1.Study on droplet transfer during welding process of narrow arc gap weldingThe high-speed camera was used to collect the transition of the droplets during the narrow gap welding process of the oscillating arc.The law of droplet transfer in the process of flat welding,vertical up welding and vertical down welding was studied respectively,and the transition law of the narrow gap weld welding droplets was revealed.The influence of different welding positions on the droplet transfer provided a basis for the study of the sway arc narrow gap weld pool behavior and welding process.2.Simulation of weld pool behavior of narrow gap weld in different positionsThe force of the narrow gap vertical welding solution and the molten pool was studied.The heat source model of the narrow gap molten pool was established.The sysweld simulation software was used to study the behavior of narrow gap flat welding,vertical up welding and vertical down welding pool.The shape of the molten pool at different welding positions was obtained,and the influence law of the oscillating arc and gravity on the molten pool at different welding positions was revealed,which provided a theoretical basis for the formation and optimization of the narrow gap vertical weld.3.Analyze the gap weld tracking method and propose a software and hardware combination filter method.The narrow gap weld seam tracking filtering method was analyzed.A combination of hardware filtering and software filtering was proposed to filter the original welding current signal collected by the Hall sensor to obtain an ideal welding current signal,which provides for subsequent weld deviation extraction.basis.4.A method for extracting the integral difference deviation of the narrow gap of the oscillating arc is proposed.Based on the original oscillating arc integral difference algorithm,the modified arc left and right integral deviation extraction algorithm suitable for narrow gap welding is modified,and the weld deviation signal is extracted from the combined filtered welding current signal,and compared with the actual deviation.The accuracy of the algorithm satisfies the actual requirements of weld seam tracking.5.Build a three-axis vertical welding robot weld seam tracking experimental platform based on oscillating arc sensorThe oscillating arc narrow gap vertical welding seam tracking experimental platform is built,which is the self-designed three-axis vertical welding robot.The experimental platform is used to carry out the narrow gap weld tracking experiment.The experimental results verify the superiority of the combined filtering and improve the narrow gap.The accuracy and feasibility of the integral weld deviation algorithm.