News Detail

The application of robot welding for large key parts of power generation equipment is difficult

Issuing time:2021-03-27 20:40

It is announced that Harbin Electric has successfully overcome the production and application problems of robot narrow gap gas welding, and has realized the robot welding of large key parts of power generation equipment for the first time, which indicates that this technology has reached the advanced level of the industry.

It's hard to weld -- it's like walking a tightrope

According to the introduction, Harbin Electric has successfully completed the welding of large mixed flow seat ring fixed guide vane and ring plate through the application of advanced, efficient and intelligent robot narrow gap gas welding technology. After inspection, UT (ultrasonic inspection) inspection of welding seam qualified for one time; Compared with the conventional welding method, the welding material consumption per welding joint decreased by 76% and the welding cycle decreased by 50%. This is another major key breakthrough in the field of intelligent manufacturing after Hadian Motor successfully cracked the automatic surfacing of nonferrous metals and the automatic production of Babbitt alloy bearing bush.

Welding itself is a complex process that is accompanied by changes in thermoplasticity and thermophysical properties of materials. Each parameter of welding process, such as current, voltage, welding speed, swing frequency and residence time, will have an impact on welding results. In the process of production and application of robot welding technology, it is particularly difficult to find a set of parameters with good matching. It is like an actor balancing on a steel wire without falling off. It requires skill, experience and perseverance. In order to realize the production and application of robot welding technology for large key parts of power generation equipment, Harbin Electric Motor faces not only these difficulties.

Due to the complex spatial structure of the product, the accessibility of the welding position is a key constraint. To avoid collision, the robot must be flexible enough to reach all sorts of nooks and crannies like an arm. However, in some extreme positions, the robot will be in a posture with a large eccentric moment, just like a long cantilever. Therefore, the robot must also have good stiffness to ensure the stability and accuracy of the welding arc at the end.

Large welding capacity, no loss. Large-scale key parts mostly adopt the ultra-thick plate structure of 150 ~ 270 mm. Compared with the mature construction machinery and vehicle manufacturing industry, the welding volume increases by more than ten thousand times. And, after the robot welding arc, there is no "back arrow", there is no possibility of starting again.

UT has strict inspection and quality control, and can not tolerate any defects. Each weld pass needs to ensure good fusion, no fusion, slag inclusion, porosity and other defects. A large mixed-flow seat ring has 6 fixed guide vanes for 1/4 flap, and each fixed guide vanes has 2 welds with a thickness of 175 mm. Under conventional process, about 90 single welds need to be welded for each welding joint. Only when all single welds have no defects can UT flaw detection of a single welding joint be qualified, and the difficulty can be seen.

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