KR20010017228A - Tracking System for Automated Indestruction Inspection at Turbine Blade Root - Google Patents

Abstract

PURPOSE: A tracking system is provided to secure a stability of equipment by automating a turbine nondestructive inspection/evaluation. CONSTITUTION: A tracking system transfers a supersonic inspecting device to an inspected portion by adapting a radius of curvature in a turbine shroud band(100) and driving four magnetic wheels(70) toward a circumferential direction. The tracking system has the magnetic wheels composing of an opening washer and a washer for controlling an interval. The opening washer controls a width of a contacted face in the shroud band. A spring for buffering is installed in a wheel supporting portion to smoothly correspond to the radius of curvature. A turbine blade disk, a root portion and so on are nondestructively inspected by moving the supersonic inspecting device around the shroud band(100) toward the circumferential direction with the magnetic force through the magnetic wheels.

Description

{Tracking System for Automated Indestruction Inspection at Turbine Blade Root}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking system for automatic nondestructive inspection of a turbine blade root portion using a direct contact type magnetic wheel of a turbine shroud band for power generation.

Ultrasonic testing for fine crack detection on the turbine blade root and surface due to stress corrosion, fatigue, etc. is currently performed in a variety of ways, but ultrasound testing of the blade root region can be used to detect various types of blades and their structures Complexity and insufficiency of inspection technology have led to difficulties in inspection method, defect evaluation and signal interpretation. In the case of foreign countries, much research is being conducted to establish the ultrasound inspection technology for the root portion of the blade, and the turbine manufacturers have provided their own inspection techniques and procedures. However, in Korea, It is a fact that they are receiving foreign technology guidance and consultation. In particular, since the accident occurred in 1986 when the fork of the blade root portion was cut off at the fifth stage of the low-pressure turbine manufactured by General Electric Company (GE) of Gori No.3, the GE non- Ultrasonic inspection of the blade root area has been carried out by the team every year during regular maintenance period.

The ultrasonic inspection method for the main components of the primary system of the nuclear power plant has already established the inspection method and acceptance criteria by performing the inspection according to the ASME CODE, but the applicable codes, specifications and inspection standards have not yet been established for inspection of turbine blades And it is controlled by the unilateral recommendation of the manufacturer and inspection demand. Therefore, the ultrasonic inspection for this field adopts the method that is suitable for the purpose through stress analysis, fracture mechanics, material behavior analysis, etc., and establishes the ultrasonic inspection technique that reaches the inspection method and sum / .

At present, turbine blade ultrasonic inspection requires more than 7 ultrasonic transducers for one blade root, and when it is directly inspected by a human hand, the stability of the operation and the reliability of the inspection result are greatly degraded at the inspection area with limited access area.

In particular, the conventional turbine nondestructive inspection requires a lot of labor and time even if it is a skilled inspector. Therefore, the necessity of automatic inspection is strongly required in electric power companies of each country. For the automatic nondestructive inspection of turbine parts including the blade root part, a device that is automatically driven at the corresponding part of the turbine is essential, and a robot is used for this purpose. However, a general inspection robot is suitable for driving the plane portion, but it can not be applied to the complex geometry of the turbine.

As the operation period of power generation facilities has increased, frequent accidents due to major parts damage of turbine facilities have caused shutdown of power generation facilities. In order to secure the safety of power generation facilities and increase utilization rate, Has attracted considerable attention.

Rotating machinery, such as turbines, are subjected to more load by increasing the number of shutdown operations, and defects and material damage at these locations can cause gradual deterioration of the material and cause unforeseen problems at the plant. In some cases, incidents of power plant accidents can cause a situation in which the life and production activities of the entire power supply area are stopped. Therefore, it is essential to thoroughly inspect and repair equipment for accident prevention.

Since the turbine is a high-speed rotating machine under high temperature and high pressure, it has been known as a component that is likely to cause defects such as brittleness, stress corrosion, and corrosion fatigue in the blade, rotor or disk during a long operation. Among them, turbine blades are damaged due to various reasons. (VT), liquid penetration test (PT), and magnetic particle inspection (MT) are mainly performed after the blade is dismantled by the nondestructive inspection method. However, in this case, a minute defect such as a fatigue crack In addition to the difficulty of detection, there are various problems such as air delay and blade balancing when blades are fastened. Therefore, it is urgent to develop automatic nondestructive inspection technology for blade joints. In order to evaluate the test results, non - destructive testing techniques that can be applied to turbines by mechanical devices rather than by human hands are needed. The present invention aims at greatly improving the existing inspection speed by designing the probe to move around the shroud band having a geometric shape in most of the turbine.

Domestic turbines are predominantly manufactured by Westinghouse and GE, and even those who are producers are not able to easily automate turbine inspection. In this trend, turbine inspection of domestic power plants is insufficient, to be.

The key to non-destructive inspection of turbine components is to detect defects in the internal volume by ultrasonic inspection without removing parts such as turbine blades from the rotor and disk during power plant planning and maintenance. Even in the ASME Code, the inspection procedures and methods for the turbine are not clearly presented, so it is urgently necessary to secure the turbine automatic ultrasonic inspection technology. In order to overcome the limitations of conventional manual ultrasonic inspection and to enhance the capability of evaluating the high reliability fault signal, real-time acquisition of the inspection signal through the accurate speed control using the mechanical drive device is the optimum inspection requirement for the turbine tester's access restricted area. The key technology of the present invention is to provide a turbine shroud band part moving at a constant speed to automate the turbine nondestructive inspection / evaluation automation to secure safety of the equipment.

FIG. 1 is a perspective view of a turbine shroud band curved portion according to the present invention.

Fig. 2 is a plan view of Fig. 1

FIG. 3 is a side view of an actual application state of the present invention

Figure 4 is a front view of Figure 3

FIGS. 5A and 5B are explanatory diagrams for enabling the adhesive force to be maintained while freely changing the various shroud band widths in the form of a magnetic wheel of the inspection apparatus according to the present invention.

FIG. 6 is a diagram showing a configuration of a free-curvature-responsive and magnetic-wheel buffer portion adapted to smoothly adapt the radius of the shroud curvature according to the present invention

FIG. 7 is a diagram showing the configuration of the power transmitting portion of the first and the first rear wheel of the present invention

8 is a photograph of a conventional passive turbine blade root ultrasonic inspection scene and a main turbine inspection site

Description of the Related Art [0002]

10: fixed frame 20: spur gear 30: idle gear

40: spring shovel 50: direction detecting roller 60: timing belt

70, 70-1, 70-2, 70-3: Magnetic wheel 80: Encoder

90: Spur gears 100: Turbine shroud band

The present invention relates to a four-magnetic-wheel-drive system in which a turbine shroud band is directly contacted and moved in order to promote automation of turbine nondestructive inspection among power plant core facilities. This is a shroud band trekking device for turbine automatic nondestructive inspection which can perform nondestructive inspection on turbine while attached to turbine shroud band. It can be separated from turbine and separated from turbine or used by nondestructive tester The turbine blade disk, the root portion, and the fixed keyway of the turbine, which are attached vertically from the axial direction of the turbine while moving in the circumferential direction around the shroud band installed in the turbine by using the magnetic force through the magnetic wheel, It is a transducer transporting device that can perform nondestructive inspection for.

And to automate the inspection by driving the device to the shroud band part which fastens the turbine blades. Application of this inspection system can improve the reliability and speed of inspection by applying to the part where it is difficult to detect and evaluate defects due to the difficulty of approaching itself like the root part of the turbine blade, And can overcome access restrictions. However, since the width of the shroud band is different depending on the manufacturer of the turbine or the stage of the turbine, the washer can be detachably installed to adjust various widths, thereby increasing the applicability. The diameter of each end of the washer The large washer is tightened to increase the straightness of the drive. There is also a slight gap between the shroud bands, which may cause the drive unit itself to wobble or reduce its attachment force, so the front and rear wheels are cushioned . The power transmission drive system is designed to move the ultrasonic inspection apparatus between each stage of the narrow turbine on the outer shroud band part of the limited turbine approaching area. Because the turbine is a magnetic body, the four wheels of the test drive are made of strong magnets and the power is transmitted from the primary power transmission gear to the secondary using 1: 1 gear. In order to minimize the weight of inspection drive system, aluminum was used as a driving body. In order to precisely control the primary direction and speed control and to prevent the operation error, the secondary direction, which is close to the encoder, I made a roller.

The present invention solves the limitations of accessibility and the difficulty in maintaining a certain position of a probe that may occur in a long time test when the inspector performs a direct inspection. In addition, the present invention is a device capable of freely performing inspection without changing the attachment ability of the device due to the variation of the shroud band width and the radius of curvature of the shroud band according to the characteristic of each turbine when it is applied to the inspection, So that it can contribute greatly.

The present invention having such a structure will be described in detail with reference to the accompanying drawings and photographs.

The present invention is a driving device capable of automatically inspecting turbine defects using a turbine shroud band (100), and is capable of transferring a probe (44) of an ultrasonic inspection apparatus. Conventional turbine ultrasonic inspection has used a method in which the inspector directly approaches the root portion 45 of the turbine or approaches the turbine at a position remote from the turbine by using various instrument devices.

However, the present invention is a transducer transporting device capable of inspecting each part of the turbine while moving around the shroud band 100 of the direct turbine, unlike devices that only approach the transducer at a position away from the turbine.

FIG. 1 is a typical view of the present invention in which the actual turbine shroud band is directly contacted while being smoothly corresponding to various types of curvature radii. Each of the magnetic wheels 70 maximizes the strength of the magnetic force by allowing the two magnets to face each other at the same inner diameter so that the same polarity can exert the maximum adhesion force. In the drawings, reference numeral 10 denotes a fixed frame, 20 denotes a spur gear receiving a driving force, 30 denotes an idle gear, 40 denotes a curved radial application spring shoe, 50 denotes a belt tension maintaining and direction detecting roller for controlling the running of the apparatus, ) 70, 70-1, 70-2, and 70-3 are front (rear) magnetic wheels, 80 is an encoder, 90 is a spur gear, and 91 is a timing belt pulley.

FIG. 2 is a plan view of the present invention. It is composed of four magnetic wheels 70 so that the turbine can be transported along the center along the shroud band 100. Each of the wheels is arranged in a straight line, and each of the magnetic wheels 70 has a timing belt pulley 65 fixed to the fixed frame 10 and capable of receiving power. In the figure, 101 and 102 are power transmission axes.

FIGS. 3 and 4 illustrate the actual turbine blade shroud band portion driven by the present invention. Four (4) magnetic wheels 70 were made to move the ultrasonic inspection apparatus properly as they were transported along the circumferential curvature portion. In the drawing, the present invention is constructed so as to generate torque from a power transmission part by an upper motor to lead to four magnetic wheels on a shroud band. In the above description, the basic information for controlling the feed direction, the feed distance, and the feed speed during feeding of the inspection apparatus is improved. Particularly, by adjusting the distance of falling from the frame using screws attached to the fixed frame of FIG. 2 It is a device that can adjust the tension of the timing belt at the same time, and the rotation direction is configured to be opposite to the rotation direction of the wheel so that the direction, distance, and speed can be recognized by the encoder of the original driving device. In addition, the part attached to the encoder has increased the frictional force by forming a paddle to eliminate the occurrence of a false feedback signal due to the slip that may occur during the initial start-up.

FIGS. 5A to 5C are explanatory views of magnetic wheels of the inspection apparatus. FIG. 5A is a magnetic wheel exploded view of the inspection apparatus. FIG. 5A is an exploded view of the magnetic wheel of the inspection apparatus. So that the exercise can be performed smoothly. In order to suitably cope with the change of the shroud band width according to the size of the turbine and the shape of the turbine, an opening washer 71 for adjusting the width is provided between the magnetic wheel 73 and the width adjusting washer 72, By adjusting the position of the spherical washer as 700-1 and 700-2, it is possible to cope freely with the shroud band width. Also, the opening-type adjusting washer 71 serves to stably locate the shroud band during transportation by using a tapered end face on the front face. In the drawing, reference numeral 700-1 denotes a magnetic wheel width L before adjustment, and reference numeral 700-3 denotes a reduced wheel width 1 after adjustment.

FIG. 6 is a front view of the wheel according to the present invention. In FIG. 6, each wheel is provided with a torsion spring 62 having a radius of curvature, and the magnetic wheel 70-3 can move freely Do. Thereby increasing the adherence to the shroud band while maintaining the driving of the device with four magnetic wheels even if the radius of curvature is changed. The principle is that even if the cushioning spring 62 changes its curvature due to the upward and downward elastic action, the axial gap maintaining link 63 and the rotary link 64 belt pulley adjust the mutual axis distance, that is, the distance between two magnetic wheels So that it is brought into close contact with the shroud band 100 by the self-weight of the present invention and the adhesive force of the magnetic wheel. In the figure, reference numeral 61 denotes a shock absorber fixing box.

7 shows that the driving force transmission to the front (rear) wheel of the present invention is transmitted to the wheel which is the foremost wheel 70 of Fig. 1 of the present invention through the link 63 for maintaining the shaft spacing and the rotating link 64, In a manner that is transmitted to the rear wheels of the device. The power transmission to each wheel is transmitted from the power of the driving unit 200 to the spur gear 40 of the device through the idle gear 30 which only changes the rotating direction of the spur gear 20 of Fig. A timing belt is provided between the magnetic wheels transmitted into the frame, and the tension of the belt is adjusted by the encoder 80 of FIG. 1 in the middle thereof to obtain the conveying direction, distance, and speed value signal.

FIG. 8 shows a conventional ultrasonic inspection method. In the case of a single turbine, the probe 44 is required to be moved by a human hand, requiring a great deal of time and labor for the inspection area of 15,000 points or more. The illustrated turbine blade root (45) is a representative model for a nuclear power plant currently in operation. In the figure, reference numeral 200 denotes a turbine rotor disk.

The present invention relates to a power transmission gear device (20, 30, 40), a magnetic wheel (70, 70-1, 70-2, 70-3) for mounting a shroud band, an encoder detection roller 50, a shock absorber 62 capable of coping with various radii of curvature, and links 63, 64 for maintaining constant distances between front and rear wheels of the front and rear wheels, 20, and 90, and the idle gear 30 is connected in the middle in consideration of the transmission direction. The four magnetic wheels are driven by a timing belt 60 to receive power from four drive shafts while maintaining a straight line. Each of the wheels is constituted by an opening washer 71 and a gap adjusting washer 72 so as to be able to appropriately cope with the width of the shroud band 100, The inner surface of the outer diameter was machined to be inclined in order to appropriately search the band width. The direction detecting roller 50 is designed so that the encoder 80 can accurately recognize the moving direction and the speed distance while maintaining the tension of the power transmission timing belt while sensing the feeding state of the apparatus.

In order to smoothly adhere to various radii of curvature, the two magnetic wheels of the front and the rear are able to generate magnetic force perpendicular to the surface of the shroud band 100 at all times through the buffer spring 62 device And the power transmission between the front wheel and the rear wheel is transmitted through the shafts 101 and 102 which are independently separated from each other and the transmitted power is transmitted to the two pulleys 90, And a rotatable link 64 so that even if the distance between the wheels is different through the link, the rotatable link 64 can be properly balanced. Each of the shafts can rotate independently of the fixed frame 10.

The present invention is to achieve the next generation non-destructive new technology by transferring the turbine shroud band part in order to automate the ultrasonic inspection, which is a kind of non-destructive volume test, to evaluate the integrity of the root portion of the turbine blade which is a main high- It is considered a big towing. In the conventional turbine ultrasonic inspection, there was a great concern about the occurrence of safety accidents in the restricted area, and since the role of the transducer scanner by the human hand has a bad influence on the subjective judgment of the reliability of the inspection, the reliability of the inspection is questioned. . On the average, the inspection time including the equipment calibration can be shortened to half in the inspection of the root portion of the high-pressure turbine blade through the present invention, and securing the objectivity of the inspection result can secure high reliability as the life of the nondestructive inspection. In addition, since it is possible to systematize long - term history management of test data, it is possible to use test history in the follow - up test. Therefore, we overcome the problems of the nondestructive test that existed in the existing manual inspection and secure the automatic nondestructive inspection technique by using the present invention, thereby expecting the effect of greatly reducing the turbine inspection service cost of the domestic power plant spent for overseas service inspection .

Claims (4)

Wherein the four magnetic wheels (70) are driven in the circumferential direction while being adapted to the radius of curvature of the turbine shroud band (100) for power generation, so that the ultrasonic inspection apparatus is transferred to a region to be inspected at a desired speed and direction. Trekking system for automatic nondestructive inspection of root part. The trekking system for a turbine blade root non-destructive inspection according to claim 1, characterized by having a magnetic wheel composed of an opening washer (71) and a gap adjusting washer (72) for adjusting the contact surface width of the shroud band (100). The trekking system according to claim 1, wherein a buffer spring (62) is installed on a wheel supporting part to smoothly correspond to a circumferential radius of curvature of the shroud band (100). The trekking system for the automatic nondestructive inspection of a turbine blade root according to claim 1, wherein driving force transmission to a front (rear) wheel is made through an axis interval maintaining link (63) and a rotation type link (64).