Adaptive control method and equipment of arc swing in narrow gap welding

An adaptive control method adapted to an adaptive control device for narrow gap welding arc swing, the adaptive control device comprising a narrow gap welding torch, an arc swing parameter control system, a computer image processing system, and an infrared camera system;

• one end of a bent conducting rod in the narrow gap welding torch is connected to a motor drive and feed mechanism, and the other end is connected to a straight contact tip;
• a welding wire passing through the narrow gap welding torch extends into a to-be-welded groove with a variable groove width, to generate a welding arc;
• the infrared camera system comprises a digital infrared camera and an infrared filter system;
• wherein:
• the computer image processing system comprises an image acquisition card, a groove width extraction module, and a swing angle calculation module that are sequentially connected;
• an output of the swing angle calculation module is connected to the arc swing parameter control system;
• the arc swing parameter control system is connected to the motor drive and feed mechanism in the welding torch through a control line, and is separately connected to the infrared camera and the image acquisition card through a signal line;
• wherein:
• the infrared camera system acquires an infrared image of a welding area in an arc position external triggering manner, and extracts information about a width of a groove in real time after processing by the computer image processing system;
• the computer image processing system calculates an arc swing angle target value according to the width of the groove;
• the arc swing parameter control system controls the motor drive and feed mechanism to directly rotate the bent conducting rod, and then drives an arc to swing along a circular arc trajectory with respect to the welding torch according to a target swing angle, realizing adaptive control for the arc swing angle according to changes in the width of the groove;
• wherein:
• the adaptive control method specifically comprises the following steps:
• {circle around (1)} in the swing angle calculation module, after presetting an arc swing radius r, a preserved process gap g, a groove width change determination threshold THw, and a groove width initial value Gs0, calculating an initial swing angle α0 corresponding to the initial groove width Gs0, and using the groove width initial value Gs0 as a sampling value at a position where an actual groove width is A0B0;
• then moving forward the welding torch and the infrared camera system together, at a welding speed Vw, and at the same time, controlling, by the arc swing parameter control system through the welding torch, the arc to conduct, within the to-be-welded groove, reciprocating swing along the circular arc trajectory with a swing angle of α0;
• {circle around (2)} sending, by the arc swing parameter control system, an arc photographing and image acquisition triggering signal PA to the infrared camera and the image acquisition card according to a motor rotation position detection signal PM when the arc is deviated towards a left or a right side wall of the to-be-welded groove or is located at the center of the groove, so that after the computer image processing system acquires the image of the welding area, the width extraction module extracts the width of the groove in real time by means of image processing;
• {circle around (3)} when the welding torch moves to any position where an actual groove width is AiBi, extracting, by the groove width extraction module in real time, a current detection value Gi of the groove width at this position, calculating a median or mean of a total of n (when n≥1) or i (when i<n) detection values of the groove width according to the current detection value and latest (n−1) (when i≥n) or (i−1) (when i<n) detection values of the groove width that are previously obtained at other positions, to use the median or mean as a current sampling value Gsi of the groove width at AiBi, and then inputting the current sampling value Gsi to the swing angle calculation module, wherein i is an actual sampling point ordinal number, and i≥1;
• {circle around (4)} comparing, by the swing angle calculation module, the current sampling value Gsi of the groove width with a previous sampling value Gs(i−1), wherein if an absolute value of the difference between the two sampling values is ΔGsi≤THw, the arc swing angle αi at the position where the actual groove width is AiBi is not adjusted;
• otherwise, after the swing angle calculation module calculates the arc swing angle target value αi at AiBi according to the current sampling value Gsi of the groove width, the preserved process gap g, and the arc swing radius r, driving, by the arc swing parameter control system, the bent conducting rod through the motor drive and feed mechanism, and controlling the arc to swing along the circular arc trajectory with an angle of αi, so that at side wall stay points Di and Mi, distances from the arc to the side walls of the groove are separately equal to the set preserved process gap g;
• {circle around (5)} repeating Step {circle around (2)} to Step {circle around (4)}, till the welding process is finished.