Research On Adaptive Control For Robotic TIG Welding Of Aluminium Alloy Aerospace Components

In the field of Aerospace Manufacturing, with application of achievements in new materials and technology in products, the requirements of quality test and process control are being higher and higher. The application of automatic welding technology has become a inexorable trend in the development of welding technology in Aerospace Manufacturing. As to normal robotic welding equipment, because of the limits in the modulation of welding torch position and welding process parameters, though teaching and playback, relying on the observations and experience of people to set the welding torch position (including height and centering) and welding process parameters, it is impossible to adapt to the bevel condition and the real-time change of welding seam position automatically. The previous passive quality test cannot adapt to the requirements of the quality control and management. So, it is necessary to adopt active detection in welding process under this circumstance.A laser vision sensing based adaptive TIG welding system for aluminum alloy aerospace components is established to fit for the variety of weld groove condition. A new type laser vision sensor is used to precisely measure the weld groove. The joint geometry data, such as bevel angle, gap, area, mismatch, and etc, can be used in assembling aerospace components before welding and are applied for automatic seam tracking in welding. An adaptive welding process is realized by automatically adjusting the wire feeding speed and the welding current according to the groove conditions, with good weld formation and high welding quality which meet the requirements of the relative standards. Though the sets of vision algorithm for variable joints, the seam tracking in welding of some typical grooves such as I-groove, Y-groove, lap joint, interior fillet welded joint, has been accomplished, and stable and accurate path of tracking welding seam has been obtained. On that basis, good weld shaping was obtained in the welding of variable joints with gap which was 0 mm, by importing appropriate welding process parameters.For I-groove, get appropriate welding process parameters for different gap (gap range: 0-4mm), then import these parameters into adaptive control module and attach them to corresponding joint recognition algorithm. In the welding process of I-groove with changing gap, adaptive control of welding process parameters by the system has been realized by automatically adjusting the welding current, the welding speed and the wire feeding speed according to the groove condition real-time detected by the vision system. However, as to the thin wall components, limited by fixture and the condition of heat exchanging, the results using adaptive parameters control only, were not ideal. It is demanded that some other auxiliary technological method should be applied for different welding conditions, so that the results will be better. In the welding process of this product, by the application of both adaptive parameters control and sectional symmetry welding, it was promised that the welding process was accomplished smoothly, and also the welding seam met the requirements.Aerospace aluminum alloy products parameter adaptive welding, proves that adaptive control of welding technology in the actual production process plays a very important role. But for different products and welding conditions must adapt for different welding processes, so as to make laser vision sensing based adaptive welding technology promote better.