Research On Dual-torch Automatic Welding Machine And Process For Long-distance Pipeline Construction

Along with the pipeline construction developing towards high pressure, big size and high grade of steel, the pipeline welding shall make great strides toward high efficiency and high quality. It is the important measure which vigorously promote and apply pipeline all-position automatic welding technology to realize the highly efficiency of pipeline welding. But as a result of the restriction effect between quality and efficiency, the welding efficiency of single set of automatic welding machine is difficult to be enhanced any more, it can only increase welding machine's quantity to improve the construction efficiency of the entire welding spread (the restriction factor of the root weld efficiency is excluded), which may cause the equipment investment to be increased, the construction operating time to be lengthened and the worker working time to be increased.The dual-torches all-position automatic welding machine could obviously improve the weld bead deposition rate and the welding speed, and promote the single set of equipment ability greatly. This machine is one kind of new pipeline automatic welding equipments, in which two torches are installed together into the welding machine (with consistent welding speed), others such as welding current, the arc voltage, the oscillation frequency, the edge resident time, the welding torch posture and so on are all respectively set and adjusted, the welding process "shield gas+solid wire" is applied, and there's certain distance between two torches to avoid the electric arc disturbance problem. The dual-torches all-position automatic welding machine has manifested the new tendency of current international pipeline welding outfit development.Using the full-digital intellectualization motion control technology and the embedded operating system which takes DSP digital signal processor CPLD complex programmable logic device as the core, the developed dual-torches pipeline all-position automatic welding machine with high automatic control level is domestically originated in pipeline building field. In the research on pipeline automatic welding equipment, the laser structure light weld joint tracking technology with good stable, reliable and the strong anti-jamming ability has been utilized for the first time so as to realize the welding torch position automatically hacking and adjusting. For the advantage of high control precision and sensitive response, the equipment difficulty to operate is reduced and the labor intensity is greatly decresed, the fine weld joint quality is assured. Based on cubic spline interpolation theory, using the Matlab programming method which matches the motion characteristic of servo motor, the welding parameters spatial interpolation and the welding parameter curve automatic fitting are realized for the first time, therefore the stability of pipeline circiunferential all-position welding process is guaranteed. Using the design concept of the mechatronics (i.e.mechanical-electrical integration) and the advanced control theory, this dissertation has emphatically studied the structure of welding bug and the guiding track as well as the control system of dual-torches pipeline all-position automatic welding machine.The application for West East Gas Pipeline Project II indicates that each system which this research completed is coordinated and stable, each performance figure achieves the destined requirements and meets actual project desire. With advanced control mode, the entire machine is simply to been operated, which can obviously raise the welding construction speed, guarantee the welding quality, and has the very broad application prospect. The welding process parameters for the X80 steel have very important applicable value on instructing the project application.