Fan Ding

RESEARCH ON THE CORRELATION BETWEEN THE STATUS OF THREE-DIMENSIONAL WELD POOL SURFACE AND WELD PENETRATION IN TIG WELDING

Measurement of the weld pool surface is a difficult but urgent task in the welding community.It plays an important role in developing the next generation intelligent welding machines,in particular,controlling the weld joint penetration in automatic welding.In this work,the images of front-side free surface and back-side width of the weld pool are synchronously captured with two CCD cameras in tungsten inert gas(TIG) arc welding process based on laser vision,and the three dimensional weld pool surface is reconstructed using designed algorithm.Then,the correlation between the weld pool surface under different weld joint penetration and its back-side width is analyzed qualitatively.The variation of reflected laser dots shape is reversely simulated under different depths of weld pool surface,which represents the different weld joint penetration,after established the standard model of weld pool,incident,reflected ray and imaging plans mathematical model.It is found that the change of weld pool surface obtained by this method has an intimate immanent correlation with the weld joint penetration.When the weld joint penetration changes from partial penetration to complete joint penetration,the weld pool surfaces shape changes from convexity to concave,and its depth is increasing with the increased back-side width.The row curvature of reflected laser dots is diminishing.When the penetration achieves excessive penetration,the depth of the weld pool surface is more rapidly increased,and the row curvature is also increased.The gathered laser dots is drawn back again at parallel direction.The simulated results associate with the measurement very well.The variations of reflected laser dots shape can represent the degree of weld joint penetration.This research lays a good foundation for the control of weld joint penetration using the characteristics of weld pool surface.

Force Analysis of Metal Transfer in Dual Bypass MIG Welding

Aiming at the dual bypass metal inert gas(MIG) welding process, pictures of the process of metal transfer under different bypass currents using the high speed camera is taken and the data of metal transfer by the image processing is obtained. The main forces affected the drop is calculated by the data. In addition, the situation of force under different welding parameters which act on the drop and researched the mechanism of metal transfer promoted are compared. The results indicated that electromagnetic force has the most important influence to the process of metal transfer of the dual bypass MIG welding. By the promoting of expand the area of arc root, the bypass arcs promote the metal transfer of the dual bypass MIG welding and this influence will be increased by bypass current. Moreover, with the increase of bypass current, the frequency of the metal transfer could be increased and the size of the drop is decreased when the total current is constant. The type of metal transfer is changed to spray transfer from globular transfer.

Computer Simulation of Neural Network Control System for CO2 Welding Process

In this paper, neural network control systems for decreasing the spatter of CO2 welding have been created. The Generalized Inverse Learning Architecture(GILA), the Specialized Inverse Learning Architecture(SILA)- I & II and the Error Back Propagat Model(EBPM) are adopted respectively to simulate the static and dynamic welding control processes. The results of simulation show that the SILA-I and EBPM have better properties. The factors affecting the simulating results and the dynamic response quality have also been analyzed

Predication of properties of welding joints based on uniform designed neural network

It is difficult to predict the mechanical properties of welded joints because of non-linearity in welding process and complicated mutual effects in multi composition welding material. Based on these practical problems, the application of neural network technology in predicting mechanical properties of welding joints is developed. The modeling method has been studied and the author puts forward that the parameters of neutral network can be optimized by the method of uniform design. The neutral network model of mechanical properties of welding joints is established on the basis of the data of welding thermal simulation, and the experimental results show that this model can predict the mechanical properties including impact toughness, tensile strength, subdued strength, reduction ratio of area and hardness more accurately. At the same time, using this method can improve estimating precision largely compared with using traditional statistic method. That is, this method provides an effective approach to estimate the mechanical properties of welding joints.

Intelligent neural network control system for gas metal arc welding

A neural network control system for keeping arc stability and decreasing the spatter during gas metal arc welding have been created. The characterization and relationship between arc sound and arc stability was studied. Tree kinds of neural network control constructions were presented. After simulated the static and dynamic performance in welding processes, it can be found that the error back propagating model neural network have better properties. The factors affecting the simulating results and the dynamic response quality have also been analyzed.

Visual-based Intelligent Control System for Robotic Gas Metal Arc Welding

Sensing and control the weld pool is a crucial problem for robotic gas-metal arc welding (GMAW) process. In present research, a special vision sensing system, assisted by a narrow-band filter which could overcome the influence of the strong arc light of GMAW, was integrated with the morphological image-processing algorithm to improve the weld pool edge extracting performance. On the basis of welding pool image vision sensing and processing system, an intelligent controller based on Fuzzy and expert system (ES) for robotic GMAW process is proposed. The experiments show that the real-time and precision requirements for detecting and control of weld pool width of robotic GMAW process could be satisfied by the established system.

Development of a Visual-Based Welding Pool Width Control System for Al-P-MIG Welding Process

An intelligent controller based on Fuzzy controller and expert system (ES) control action for Aluminum alloy Pulsed Metal Inert Gas (Al-P-MIG) welding process is proposed. On the basis of welding pool image vision sensing and processing system, the identification model of welding pool width dynamic response in Al-P-MIG welding process has been setup. And then, in the case that welding pool width reference input value is 3mm, 4mm and 5mm respectively, the PID and Fuzzy control effects are simulated and analyzed. The experiments show that the real-time and precision requirements for detecting and control of weld pool width of Al-P-MIG welding process could be satisfied by the established system