The Key Technology Researches Of The Plate Complex Seam Tracking

Plate welding structure is widely used in industrial sectors, such as ship-building, largebridges, petrochemical, boiler containers, heavy machinery and so on. It is also themainstream trend for steel welding. Nowadays, the multi-pass welding is commonly used inwelding plate structure. But some problems leading to the low degree of automation appearedduring plate structure welding, for example: the welding energy can not be controlled duringwelding process, the direction of welding bead may be changed by the re-melting heattreatment effected from the posterior to the anterior layer, as well as the deformation of theparent material occurred by the heat-affection of multi-pass welding etc. Therefore, thetechnology to realize the automatic of seam tracking in plate welding is particularly urgentneeded.1. A rotating arc sensor that is suitable for the plate welding is first designed.Considering the requirements, the multi-pass welding for the sensor intelligent welding,and a rotating arc sensor with stepless eccentric adjustment is designed based on the usingrotating methods of rotating arc sensor. During the welding process, the intelligent control ofrotating radius can be realized as well. After the simulation of ADAMS, the optimal designparameters and motor sizes are determined, as well as the institutional rationality of designverified. Then, for the problems such as large quantity of heat in the plate welding, awater-cooled structure is designed. By the thermal analysis of ANSYS and experimental, thewater-cooled structure is further optimized. This mechanism has provided a guarantee forlong-time welding in the factory.2. The arc length model of multi-pass welding is established, as the seam deviation androtating radius under different welding pass have been solved out.Based on the groove model of multi-pass welding, welding arc signal model of rotatingarc sensor is built. It can achieve current analog output of different welding. And thecomparative analysis between this output and practical current signal is taken in this paper. Inorder to eliminate the serious signal interference of practical welding current, the hardwarefilter is used to preprocess that signal. In the following, the principal component method istaken to analysis the preprocessed data, and the regression equation is built to solve out theseam deviation values. As using the combination method of fitting and integral, the value ofrotating radius is optimized by the obtained deviation.3. With the program of oscillating rotating arc sensor first put forward, and the spaceposture arc length model of welding torch built, the torch gesture recognition has been realized.According to the single feature of arc sensor signal used at present, the program ofoscillating rotating arc sensor is put forward. And the arc length model of different posture inspace is also built based on the motion model of oscillating rotating arc sensor. Because thatthe eigenvalue of signal in gesture recognition algorithm requires higher, the processingprogram of Gabor filter is used for the sampled data. Meanwhile, the principal componentmethod is taken to extract the feature and to reduce dimension of signal data. Finally, the aimof welding torch gesture recognition is reached, after the current torch gesture obtained by theclassifier and the steepest descent method.4. The seam tracking system of multi-pass welding, based on the hardware platform ofmultiple freedom welding car is developed.On the basis of torch posture characteristics, the program of welding car with6-DOF isproposed, and the motion model is built then. Through the obtained information such as theoptimal rotating radius and the welding posture, the multi-pass welding seam tracking systemis developed. For this system, the control core is the industrial control computer, the hardwareexecution platform is the6-DOF welding car. And the automatic seam tracking for severalwelding beads or trajectory welding seams can be realized by this system.5. In order to improve the tracking accuracy of system, the different calculation methodsof tracking accuracy models based on different control schemes are finally put forward.By simplifying the model of multiple freedom welding car, the mathematical models ofseam tracking accuracy under different control options are established. Also, the correctionand efficiency of this tracking accuracy model are verified by the simulations and tests.Doubtlessly, these models can give theoretical guidance to the use of excellent controls in thefuture.