KR20000060369A - A automatic tester and method of grid of eggcrate iv vapor - Google Patents

Abstract

PURPOSE: An apparatus for automatically testing grids of an eggcrate of a steam generator and a method therefore are provided to exactly test the grids of the eggcrate by automatically correcting the position of the apparatus for testing to be put at the exact position of the grids. CONSTITUTION: A method for automatically testing grids of an eggcrate(21) of a steam generator includes the steps of performing settlement of zero point of a guiding device by CCD(Charge Coupled Device) camera after moving guide bodies(12,13) toward the motor and installing the eggcrate on a table and performing a test according to a program sequence based on a databased address assigned to each grid from the starting point; testing the grids by five gauges and marking an inferior grid by a spray incorporated within the gauges and storing an inferior position in a computer if the grid is inferior; rotating the eggcrate and a gauge head(24) by the motor at an angle of 90 degrees if the testing for one fourth surface of the eggcrate is completed by a control program.

Description

Steam generator egg crate automatic inspection device and inspection method {A AUTOMATIC TESTER AND METHOD OF GRID OF EGGCRATE IV VAPOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for inspecting the size of a hole or a grid, and includes a tube sheet hole of a grate of a crate or a large heat exchanger that maintains and supports a heat pipe inside a steam generator in a nuclear power plant facility. The present invention relates to an inspection apparatus for determining whether or not the design meets the allowable design dimension.

In a nuclear power plant, the heat pipes inside the steam generator provide heat exchange between the primary grid containing radiation and the secondary grid running the turbine, which separates the primary grid from the secondary grid. It is an important device.

If leakage occurs in this heat pipe, the problem arises that the plant must be shut down as the primary system coolant containing radioactive material leaks to the secondary side.

The steam generator design and manufacturing process is very important because it is not only an economic loss but also a serious problem for safety. Egg crate is a component to maintain and support the heat pipe inside the steam generator. It is inserted between each grid and fixed.

Egg crate is divided into three types: full type, half type, and partial type. Especially, the full size of the egg crate is a large structure with a diameter of 4m. It consists of 16,000 grids.

The steam generator egg crate is assembled by welding a slotted bar (Slotted Bar) up and down, and a heat pipe is inserted into each lattice. Slot bars are zigzag-assembled and welded to a specific area. When welding, slot bars do not meet the dimensional tolerances of a given grid due to distortion of the slot bar or thermal stress after welding.

Therefore, the dimensions and fabrication status of each grate of the egg crate have a significant influence on the tubing process, which is the next step. When the size of the grating is small, the tube is smoothly inserted into the egg crate. If this happens, scratches occur on the surface of the tube to be inserted, which adversely affects the service life of the tube. In some cases, a repair process such as reaming is required to insert the tube. Done.

In order to solve the above problems, it is necessary to perform a full inspection of the egg crate grating before the tubing operation and repair it before attaching the grating smaller than the tube size to the steam generator. I'm doing it.

Since the sampling test is performed by a person, there are differences in test results according to individual inspectors, and it is difficult to set test standards. In particular, the above-described problem occurs when there is a defect in the unchecked grating due to the sampling test, which determines whether or not the lattice dimension pass / fail is required.

As a result, the egg crate check that requires full inspection is being replaced with a sampling inspection due to a realistic problem, and in order to improve the above problems, an automatic inspection apparatus has been developed to enable full inspection.

Patents for conventional automated inspection devices have been published in US Pat. Nos. 4718277, 4788026, 5185124, and 5265130. In particular, US Patent 5265130 is an automatic inspection device that checks the cell size of the fuel assembly into which the fuel is inserted using a pin gauge, and is a device capable of inspecting the size of many cells at once using a plurality of pin gauges. The sensor was able to know the position of the defective cell.

Because the device places a 4m diameter fuel assembly on the base, the inspection device must be large, and as many gauges as a quarter cell total can be used to inspect the entire quarter. Since it requires a lot of manufacturing costs, there is a high possibility to determine the cell size of the good product by the interference between the gauges. In addition, there is a disadvantage that there is no versatility because it is a dedicated facility capable of inspecting only one type of inspection object.

In more detail, the above-described US Patent 5265130, Figure 1a is a device for inspecting a nuclear fuel assembly using a pin gauge (1) to check whether the cell size in the fuel assembly (2) is appropriate or not, as an inspection device for Consists of.

As shown in FIG. 1A, the nuclear fuel assembly 2 is placed on the table 3, and the actuator 4 allows the table to move from side to side on the rail 8. The head 5 with the pin gauge 1 is moved up and down along the rail 9 by the actuator 6.

The pin gauge (1) on the head (5) has a number of pin gauges (1) for inspecting one quarter of the nuclear fuel assembly (2) at a time, with each rotating quadrant rotating shaft Rotate by 90 ° by (7) to the next inspection, and work is completed by 4 inspections. When the pin gauge 1 encounters a defective cell, it is sensed by a needle-type contact sensor or a transceiving photodiode sensor.

The method of setting up the fuel assembly in the inspection apparatus is as shown in Fig. 1b, after moving the table 3 to a side, the fuel assembly is placed, fixed with the support device 10 and then the table 3 is fixed. It is to move back to the inspection position to perform the inspection work.

The above inspection apparatus puts the large fuel assembly 2 on the table 3, which makes the inspection apparatus bulky, especially because of the setup method, the volume is more than twice as large as the nuclear fuel assembly, thus increasing the working space with the enlargement of the inspection apparatus. This necessitates a disadvantage that the operator cannot easily find the location when the defective cell is repaired after the inspection is completed.

In addition, since the support device 10 is used for set up, it can be applied only to a specific size and shape such as a fuel assembly, and the shape such as a semicircle is difficult to set up and requires additional jig. The gauge head inspects the entire quarter of the fuel assembly at one time, requiring many gauges and difficult to apply to many types of product inspection, such as semicircles.

In such a situation, the quality of the entire steam generator will be seriously affected, so the egg crate will need to be fully inspected for the size of the grid.

Therefore, it is practically impossible for a person to fully inspect all the grids of each type of egg crate, so an automatic inspection device is required. In the present invention, an inspection apparatus capable of automatically performing a full inspection of the possibility of smooth insertion of a heat pipe into such a structure. Was constructed.

The present invention is designed to improve the problems of the conventional inspection apparatus and inspection method as described above, to minimize the volume of the inspection apparatus, to develop a new setup method to cope with various types of products, using five gauges Use the gauge head. In addition, in order to adjust the position of the gauge head to the center of the grating, a CCD camera for automatic position correction, a machine vision apparatus and a program are developed and applied to the apparatus of the present invention.

Figure 1a is a front view of a conventional inspection device,

Figure 1b is a plan view of a conventional inspection device,

2a is a plan view of an egg crate lattice inspection device,

2b is a front view of an egg crate lattice inspection device,

3a is a front view of the gauge head,

3b is a side view of the gauge head,

4 is the shape of the grid arrangement when the egg crate rotates 90 °,

5A shows the inspection of half type egg crate,

5b is a test of partial type egg crate,

6 is an egg crate image obtained using a CCD camera and a machine vision device,

7 is a position error correction and starting point positioning flow chart,

8 shows a region of interest (ROI) of an egg crate;

9 is a bisector and a center point when the position correction algorithm is applied.

(Explanation of reference numerals)

11 base, 12, 13, guide body,

15,16,25 ... motors, 17,18 ... ballscrews,

19,20 ... guide, 21 ... egcrate,

22 ... post, 23 ... table,

24 ... gauge head, 26 ... gear,

27 bearings, 28 cylinders,

29 gauge, 30 proximity sensor,

31 ... shaft, 32 ... rotating shaft,

33 ... CCD camera, 34,35 ... half and partial type crate,

36 ... Jig.

Hereinafter, with reference to the drawings will be described in detail the configuration and operation of the steam generator egg crate automatic inspection device of the present invention.

As shown in FIGS. 2A and 2B, the guide body 12 is fixed on the base 11, and the gauge head 24 is mounted on another guide body 13. This another guide body 13 is moved along the guide 19 on the guide body 12 by the motor 15 and the ball screw 17 (in the Y-axis direction), and the gauge head 24 is connected to the motor 16. And the ball screw 18 to move along the guide 20 on the another guide body 13 (X-axis direction).

The guide bodies 12 and 13 are sized to inspect the size of the quarter of the egg crate 21, and cantilever type to occupy the smallest possible volume.

It consists of a table 23 and a post (22) to support the egg crate 21, so that the egg crate 21 can be rotated by 90 degrees by the motor 25 and the gear 26 It is. The post 22 is designed to be installed at an arbitrary position according to each type in order to support various types of egg crate, and the bearings 27 allow the egg crate 21 to rotate. .

In addition, the guide is made on the table to make it easy to install the egg crate 21 on the table 23, to prevent the shaking of the egg crate using a fixed plate (not shown).

As shown in FIGS. 3A and 3B, the gauge 29 for inspecting the grating in the egg crate 21 obtained the optimum number of gauges by experiment to minimize mutual interference between the gauges, and the number of gauges was 5 On the basis of the dog, the number of gauges can be increased to eight, depending on the type of egg crate.

The gauge 29 allows for quick determination of whether the design satisfies the diameter of the minimum inscribed circle of a given grating, and the configuration of the gauge head 24 consists of a cylinder 28 and a shaft 31 driven by pneumatic pressure. The gauge 29 is moved up and down, and if the grating is judged to be defective by the gauge 29, it is detected by the proximity sensor 30 so that it can be input to a computer and display its defective position with a spray mounted inside the gauge. It is.

In addition, the gauge head 24 has a characteristic that the gauge head 24 should rotate by 90 ° according to the egg crate grating type, and is configured to allow the gauge head to rotate by the rotating shaft 32.

In order to correct the position error of the guiding device that moves the gauge head 24 and to accurately select the position of the initial starting point, the CCD camera 33 and the machine vision device were used.

The inspection method of the inspection apparatus is as follows.

The egg crate lattice inspection starts with installing the egg crate on the table 23, as shown in Fig. 2B. After the guide body 13 is moved towards the motor 15, and the egg crate 21 is installed on the table 23, zero setting of the guiding device is performed by the CCD camera, and is assigned to each grating from this starting point. The check is performed according to the program sequence according to the databased address.

The grating inspection is performed by five gauges 29. When the grating is defective during inspection, the grating is marked by the spray inherent in the gage and the result of the defective position is stored in the computer.

When the inspection of the quadrant is completed by the control program, the egg crate 21 on the table 23 is rotated by 90 ° by the motor 25, and the gauge head 24 is also rotated by 90 ° at the same time. This is because, as shown in Figs. 4A and 4B, the rhombic lattice arrangement in the egg crate 21 changes by 90 degrees.

Each quadrant test is performed in the manner described above, and the test sequence of the control program is applied differently according to the type of egg crate.

The egg crate test of the type of the half 34 and the partial 35 is as described above, and the position of the post 22 is newly set as shown in FIG. As shown in 5b, the jig 36 which can be connected with the table 23 is used to rotate the partial crate 35 of 90 degrees.

In order to perform the inspection, the position of the gauge should be precisely centered on the center of the grating to minimize the interference between the gages and reduce the error of judging the good grating of the good. Position correction for this should be considered from two perspectives.

The first is the length compensation of the gauge in the X and Y axis direction, and the second is the angle (tilt) compensation of the gauge. For this purpose, the longitudinal direction correction and the tilt correction of the gauge head 24 are performed by using a CCD camera, and the correction time is performed at the beginning of the initial stage and 5 to 7 consecutive inspections.

As shown in FIG. 6, since the heights of the upper grating and the lower grating are different from each other, when the image is acquired through the CCD camera, the egg crate may look different depending on the depth of the upper and lower gratings.

That is, the upper grating appears thicker and the lower grating appears narrower. The machine vision algorithm was developed to detect the intersection of the upper and lower gratings and the direction of the egg crate for the surface of egg crate.

The overall flow chart of the developed algorithm is shown in FIG. The algorithm obtains an image after determining a region of interest (ROI) for accurate information extraction, and performs binarization and contour extraction, which are image processing techniques, on the image.

Next, the contour region of each grid is separated by using the coordinate values of the contours of the upper and lower grids obtained by performing the contour extraction. That is, the contour region of the upper and lower gratings is distinguished using a region separation technique using statistical characteristics of the Y axis of the image.

The linear regression equation is calculated based on the coordinate values of the contours of the extracted grids, and the linear equation for each contour group is calculated. Then, the piers of the straight lines are calculated and the value is within the given allowable range. Otherwise, this process is repeated after moving the region of interest using the information of the two straight lines.

When two linear equations are obtained through this process, the constraint regression is performed within a certain range centered on one of the linear equations. In other words, it means a regression given some constraints.

The constraint is that the angles of the two real grids are known in advance, so it is necessary to estimate them based on the grid angles that appear in the image. In other words, a regression equation must be obtained to maintain the known angle.

Using the pier on the image for the actual pier to find the intersection of the two straight lines to minimize the estimation error while maintaining the actual pier to calculate the difference from the center point of the original gauge head (24).

In addition, by calculating the inclination with the horizontal line by calculating the bisector of two straight lines, it is estimated how much the gauge head 24 is inclined relative to the horizontal line. This center point difference and the inclination in the bisectors are transmitted to the guiding device for transferring the gauge head 24 and the CCD camera 33 so that they are corrected in the correct position and direction.

As shown in FIG. 8, the region of interest set for obtaining the center point and the bisector is shown. As shown in FIG. 9, the image of the center point and the bisector when the algorithm is applied is shown.

The automatic steam generator egg crate lattice inspection device of the present invention having the above-described objects and configurations enables easy and rapid inspection of large egg crate while minimizing the volume of the device, and transfers various types of egg crate. The automatic inspection can be performed, and the position of the inspection apparatus to be placed at the correct position of the grid is always corrected automatically by the apparatus applying the machine vision algorithm according to the present invention.

Claims (4)

In the apparatus for inspecting the grate of the egg crate, Guide body 12 of cantilever type fixed on base 11 and another guide body 13 of cantilever type moving along guide 19 (Y-axis direction) by motor 15 and ball screw 17. A gauge head 24 installed above and moving along the guide 20 (X-axis direction) on the another guide body 13 by a motor 16 and a ball screw 18; It consists of four posts 22 mounted with bearings 27 to support the egg crate 21 and to rotate the crate 21 by 90 ° by the motor 25 and the gear 26. A table 23 on which guides and a fixed plate are installed; In order to inspect the grating in the egg crate 21, the cylinder 28 and the shaft 31 driven by air pressure can be moved up and down and rotated by the rotation shaft 32, but operated by the proximity sensor 30. A steam generator egg crates automatic inspection device, characterized in that the spray head is composed of a gauge head (24) consisting of five to eight gauges (29) mounted therein. In the inspection method for automatically inspecting the grid of egg crate, After the guide body 13 is moved toward the motor 15, and the egg crate 21 is installed on the table 23, zero setting of the guiding device is performed by the CCD camera 33, and from this starting point, each grating A check is made in accordance with a program sequence according to a data-based address assigned to; The lattice inspection is performed by five gauges 29, and if the lattice is defective when inspecting, the defect lattice is marked by the spray inherent in the gauge and at the same time, the result of the defective position is stored in the computer; When the inspection of the quarter of the egg crate 21 is completed by the control program, the egg crate 21 on the table 23 is rotated by 90 ° by the motor 25, and the gauge head 24 is also rotated. Steam generator egg crate automatic inspection method characterized in that rotated 90 °. The method of claim 2, Method for automatically testing the steam generator egg crate grating characterized in that it uses a jig (36) that can be connected to the table (23). Determine a region of interest (ROI), acquire an image, and perform binarization and contour extraction on the image; Next, using the coordinate values of the contours of the upper and lower grids obtained by performing the contour extraction operation, the contour regions of the respective grids are separated; The linear regression equation is calculated based on the coordinate values of the contours of the extracted grids, and the linear equation for each contour group is calculated. Then, the piers of the straight lines are calculated and the value is within the given allowable range. Otherwise, this process is repeated after moving the region of interest using the information of the two straight lines; When two straight equations are obtained through this process, Constrained Regression is performed within a certain range centered on one of the straight equations, and two straight lines are actually piers using the piers on the image of the actual piers. Calculate the difference from the center point of the original gauge head 24 by finding the intersection of the two straight lines to minimize the estimation error while maintaining? When the bisectors of two straight lines are calculated and the inclination with the horizontal line is estimated, the inclination of the gauge head 24 with respect to the horizontal line is estimated to transfer the gauge head 24 and the CCD camera 33 to the center point difference and the inclination in the bisector. Steam generator egg crate characterized in that the gauge 29 is controlled by performing the initial start step and 5 to 7 consecutive inspection cycles by using a machine vision algorithm which is transmitted to a guiding device to ensure correct position and orientation. Grid automatic inspection method.