Tooling and method for scanning blade root defects of steam turbine

Abstract

The invention discloses a tooling and method for scanning blade root defects of a steam turbine. Two ends of a flexible operating rod of the tooling are separately connected to a handle and a probe frame; a protective jacket is arranged in the probe frame; an ultrasonic probe is arranged in the protective jacket; a coupling agent outlet is arranged on the wall of the probe frame, and communicatedwith a coupling agent hose; and two permanent magnets are arranged on the wall of the probe frame at intervals. According to the method in the invention, the ultrasonic probe is connected to an ultrasonic flaw detector; the coupling agent outlet is connected to the coupling agent hose; the coverage area of the ultrasonic probe is checked by adoption of a comparison specimen; furthermore, the checksensitivity is adjusted; the probe frame is moved to the inner side of a blade root along the outer cambered surface of a blade through the handle and the operating rod; the probe frame is stably located on the step surface at the inner side of the blade root by the two permanent magnets; the liquid flow of a coupling agent is adjusted, so that the waveform of the ultrasonic flaw detector is stably displayed; scanning is carried out by moving of the probe frame; and, in combination with a scanning result, defect evaluation is given. By means of the tooling and the method in the invention, defect check of blade root parts is realized; steady coupling is achieved; potential safety hazards are found in time; and thus, security and reliable operation of the steam turbine can be ensured.

Description

technical field [0001] The invention relates to a scanning tool and method for defects at the root of steam turbine blades. Background technique [0002] The structure of large steam turbine blades is complex, and they are densely arranged along the circumference of the rotor. Without dismantling, the inner root is in a shielded state, but the root of the blade bears high stress under the action of high-speed load, and has the potential to produce fatigue cracks. Possibility, especially the stress concentration at the ends on both sides of the blade root is more serious, so it is very necessary to detect crack defects on the blade root to find potential safety hazards in time. [0003] Large-scale steam turbines are generally inspected and repaired by shutting down and on-line detection. The detection of blade root defects on the outer side of the blade is easier to achieve, but because the distance between the blades is narrow (only about 40mm), manual scanning to detect th...

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Problems solved by technology

[0002] The structure of large steam turbine blades is complex, and they are densely arranged along the circumference of the rotor. Without dismantling, the inner root is in a shielded state, but the root of the blade bears high stress under the action of high-speed load, and has the potential to produce fatigue cracks. Possibility, especially the stress concentration at the ends on both sides of the blade root is more serious, so it is very necessary to detect crack defects on the blade root to find potential safety hazards in time

[0003] Large-scale steam turbines are generally inspected and repaired by shutting down and on-line detection. The detection of blade root defects on the outer side of the blade is easier to achieve, but because the distance between the blades is narrow (only about 40mm), manual scanning to detect the blade root position on the inner side of the blade The inspection cannot be carried out, that is, the probe cannot be placed at the step of the blade root on the inner side of the blade, it is difficult to position and fix the probe, it is difficult to fit the probe and the surface of the blade root well, and it is difficult to achieve stable coupling scanning

Especially for complex structures like fir-tree-shaped blade roots, it is more possible to inspect the defect of the blade root; it seriously affects the safe and reliable operation of the steam turbine, and there are certain safety hazards

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