JPH04120456A - Nondestructive inspecting apparatus by skid - Google Patents

Abstract

PURPOSE:To discern the surface area and the kind of a defect by adapting an operating/processing part to obtain the difference of outputs of skids, thereby to make small a background signal resulting from the surface shape of an object to be measured. CONSTITUTION:Two pickup coils 1-1, 1-2 are provided with different distance from a surface 9 to be measured. When the interval between the pickup coils is set , and the initialization distance between the surface 9 and the coil 1-1 is h0, 20<=h0<=10mm are satisfied. These values are determined from experiences. Skid outputs V1 and V2 are outputs of skid devices 4 connected to the coils 1-1 and 1-2, respectively. V2-V1 is the difference of the outputs, which can remarkably reduce a background signal. The ratio of the signals V1 and V2 from a defect can be represented by the equation. Accordingly, the shape of the defect can be known through one time scanning. When the shape of the defect is determined, since the relation between the area of the defect and skid outputs is already known, the area of the defect can be detected easily. This process is performed by a computer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a non-destructive inspection device for defects in structures and equipment using a 5QUID device using magnetism.

[Conventional technology]

, rSQUID' 85, Superconducting Quantum Interference Devices and Their Applications: 1985 Walter de Gruyte
isCo, Berlin New York Pr1n
ted in GermmyS Q U ID -
'85- Superconducting Qu
mmtumInterference Devices
mmd their Applications). As a conventional technology, Japanese Patent Application Laid-open No. 1983-
No. 235876, Japanese Patent Application Laid-open No. 63-32384,
JP-A-60-147646 and JP-A-60-58
No. 565 is mentioned. These pickup coils have a high-order differential coil structure.

[Problem to be solved by the invention]

In the conventional technology, a problem arises in that signals from defects are superimposed on background signals caused by the surface shape (overall unevenness) of the steel plate or test piece. The background signal is very large, while the signal from defects is relatively small. Therefore, in order to detect a signal from a defect with a highly sensitive 5QUID device, it is necessary to reset the measurement range many times, and a certain amount of detection error occurs due to the reset. Furthermore, if the signal from the defect is quite small/h, there is also the problem that the signal from the defect is hidden by the background signal.

Furthermore, with conventional devices, it is difficult to determine the surface area of a defect from a single scan, and the surface area of a defect is determined by combining the results of multiple scans.

An object of the present invention is to provide a non-destructive inspection device using a skid that can reduce back-ground noise and determine the surface area and type of defects with a single scan.

[Means to solve the problem]

The present invention provides a plurality of pickup coils (gradiometers) at different distances from the object to be measured in order to reduce the background signal described above in non-destructive inspection of defects using 5QUID. The method for measuring the signal difference is to use 5QU for each pickup coil.
There is a method in which an ID device is provided and the difference between the 5QUID outputs of each device is taken, and a method in which a plurality of connected pickup coils is provided and the difference in sensor output is amplified by the 5QUID device.

That is, the present invention includes a pickup coil that detects a magnetic flux signal from an object to be measured, a skid device that receives a signal from the pickup coil, and an arithmetic processing section that receives and processes an output signal from the skid device. In a non-destructive inspection device using a skid, the pickup coil is covered with multiple layers at different distances from the object to be measured, a skid device is provided for each pickup coil, and an arithmetic processing unit calculates the difference between the outputs of each skid. The device is characterized in that it is formed so as to perform calculations to reduce a background signal caused by the surface shape of the object to be measured.

The present invention also provides a pickup coil that detects a magnetic flux signal from an object to be measured, a skid device that receives the signal from the pickup coil, and an arithmetic processing unit that receives and processes the 8-force signal from the skid device. In a skid non-destructive inspection device equipped with a skid, a plurality of pickup coils are provided at different distances from the object to be measured, a skid device is provided for each pickup coil, and an arithmetic processing unit is installed on a predetermined skid. The defect shape is determined from each actually measured skid output value based on the relationship between the output value, the distance from the object to be measured, and the defect shape of the object to be measured.

Further, the present invention includes a pickup coil that detects a magnetic flux signal from an object to be measured, a skid device that receives a signal from the pickup coil, and an arithmetic processing section that receives and processes an output signal from the skid device. In a non-destructive inspection device using skids, a plurality of pickup coils are provided at different distances from the object to be measured and with different winding directions, and a skid device is provided for each coil pair of each pickup coil with a different winding direction. The arithmetic processing unit is configured to determine the defect shape from each actually measured skid output value based on the relationship between the predetermined skid output value, the distance from the object to be measured, and the defect shape of the object to be measured. It is characterized by the fact that

In the non-destructive inspection device, the arithmetic processing unit is configured to calculate the area of the defect from the determined defect shape based on a predetermined relationship between the defect area and the skid output. good.

Also, the distance (h) between the object to be measured and the pickup coil is 2
It is best to set the distance between the pickup coils to 0 to Loom and set the interval (Δ) between the multiple pickup coils to 2 to Low.Also, the distance between the object to be measured and the pickup coil (h), and the interval between the multiple pickup coils (△) But, 10≦h/△≦20
It is better to set the conditions to satisfy the following.

[Effect]

Assuming that the distance (interval) between the pickup coil and the object to be measured is h, the relationship between the 5QUID output V and h is expressed as the following equation (1) when there is no defect.

■N=αh-1...River...(1) Here, α is a constant.

Further, when there is a defect, the relationship between ■ and h is expressed by the following equation (2) or (3).

In the case of a rectangular defect In the case of a circular defect V H = γh-' ...
...(3) Here, β and γ are constants. Above formula (1)
The basis for ~(3) is shown below.

The characteristics of various defect signals in 5QUID were investigated. 8th
As shown in Figures to Figures 10, a flat plate with no defects (background noise) (Figure 8), slits (Figure 9), and holes (Figure 10) is placed at the bottom of the 5QUID sensor,
The output of the skid when moving in the h direction was measured. The results are shown in FIG.

The relationship between skid output V and position is V=ahx...
... (A) QogV=noga+xQogh −
-(B), then from the slope of the straight line in Figure 4, the background noise is x = -1, the slit is x = -3,5,
For the hole, x=-5 is found. In this way, it has been experimentally found that the output of the skid changes depending on various defects.

The magnetic application non-destructive testing 5QUID device measures the 5QUID output by horizontally scanning a sensor consisting of a pickup coil. The surface of the object to be measured is not necessarily flat. Therefore, when the sensor is scanned, the distance between the sensor and the object to be measured changes due to the unevenness of the object to be measured, and even if there is no defect, the 5QUID output changes as expressed by equation (1) above. . This is the background signal. In order to reduce this background signal, a sensor consisting of a plurality of pickup coils located at different distances from the object to be measured is provided.

For example, when two pickup coils are used and a 5QUID device is provided for each pickup coil, if the interval between both pickup coils is Δ, then from equation (1), 5QUID device is provided for each pickup coil.
The UID output is VN = αh-1...
...(4)■N2=α(h+△)-1...
...(5).

If we take the difference in surface output, we get the following equation (6).

Δ The initial setting distance between the pickup coil and the object to be measured is ho
For example, Δ/h is set to =1/10. Then, since h=h, Δ/h: 1/10, and equation (6) is VN, -Vs,? 0,091a h-1--(7)
becomes.

Equation (7) is approximately 1710 smaller than Equation (1).

That is, the background signal can be reduced.

Note that by setting Δ/h0=,=1/20, the background signal can be reduced to about 1/2o. In other words, measuring the difference in 5QUID outputs is (△/
h, ), which leads to the fact that the background signal can be reduced.

In the case of a rectangular defect, each 5QtOD output at a defective location is expressed by the following equation based on equation 1 (2).

■s2=β (h+Δ)...
(9) As before, if we set Δ/h″ to 1/10 and take the difference between the two, we get:

Further, in the case of a circular defect, it is expressed by the following equations from equation (3).

vH1=γh-5・・・・・・・・・(11)VHz”
'l (h +Δ) −' ・=...=
...(12) As before, if we set Δ/h41/10 and take the difference between the two, we get Vn, Vn2"Fo, 379Yh-" ...-
−・(13).

Formula (10) is approximately 1/4 of formula (2), and formula (13) is approximately 1/4 that of formula (2).
3), which is about 1/3 smaller than 3). Therefore, by taking the difference between the 5QUID outputs, the signal from the defect becomes smaller, but the background signal decrease due to the surface shape (unevenness) of the object to be measured ( (approximately 1/10). From the above, it can be seen that measuring the difference between the 5QUID outputs has the effect of highlighting signals from defects.

This effect is the same even when a plurality of connected pickup coils are provided. When two pickup coils are used as a sensor, the coils are wound in opposite directions. Therefore, the currents generated in the coils by the magnetic field are in opposite directions, and the difference between the outputs of each pickup coil becomes the output of the sensor body. This output is amplified by a 5QUID device and output.

In this case, the number of range changes (resets) of the 5QUID device can be significantly reduced. Therefore, as described above, there is an effect that measurement errors caused by resetting can be reduced.

Furthermore, as shown in equations (1) to (13), the 5QUID depends on the measurement position depending on the background and defect type.
Since the signals are different, it is possible to determine the type of these signals. That is, using the known property that the relationship between the distance from the object to be measured and the 5QUID output depends on the defect shape,
It becomes possible to detect the shape of the defect and measure the surface area of the defect in a single scan.

〔Example〕

Examples of the present invention will be shown below. FIG. 1 shows an outline of the present invention when two pickup coils are used in non-destructive inspection of defects using magnetism.

The present invention is a 5QUID device which is connected to a pickup coil 1, an excitation coil 2, and a pickup coil 1 via a beat switch 3! 4. A control device that controls the 5QUID device 4 and measures the 5QUID output 5. A computer 6 that analyzes and processes the 5QUID output, a refrigerant 7 for achieving a superconducting state, and a balance ring for balancing the initial 5QUID output. In the magnetic application non-destructive inspection 5 QUID apparatus composed of 8, two pickup coils 1-1, 1-2 are provided at different distances from the surface 9 of the object to be measured.

Here, details of the pickup coil (radiometer) 1 are shown in FIG. 2. The winding direction of the outer coil is opposite to that of the inner coil.

Furthermore, an example in which two pickup coils are connected to form a sensor is shown in FIG. 3, and an outline of the apparatus in this case is shown in FIG. 4. In FIG. 3, the winding directions of the coils are opposite to each other. When a magnetic force acts on this sensor, the directions of currents generated in the coil are opposite to each other. Therefore, the difference between the outputs of each pickup coil becomes the output of the sensor body. In FIG. 4, the sensor output is amplified by a 5QUID device 4 via a heat switch 3.

With the above device configuration, it is possible to reduce the background signal depending on the shape of the surface 9 of the object to be measured, as described above.

In Figures 1 and 4, two pickup coils 1
The interval between -1 and 1-2 is △, the initial setting interval between the object surface 9 and the pickup coil 1-1 is ho, and 20
≦h0≦100+wn, 2≦△≦10 kaku or 10≦h
/Δ≦20. These dimensions are determined empirically based on mutual interference of the pickup coils, sensitivity, and the like.

5(a) to 5(c) schematically show the results of measuring defects using a conventional magnetic non-destructive inspection 5QUID device. Same figure (
5QUID on the object to be measured that has defects as shown in C)
When the sensor is scanned, the 5QUID output is as shown in the same figure (a).
become that way. The 5QUID device has a certain output value (
1 in the figure), it is necessary to change the range and reset. When these are combined, the result is as shown in the same figure (b). As can be seen from this figure (b), the background signal caused by the surface shape of the object to be measured is quite large, and as described above, it is necessary to reduce this.

Figure 6 schematically shows the results of defect measurement according to the present invention, in which 5QUID devices are provided for each pickup coil shown in Figure 1.
Shown in a) and (b). 5QUID output v1 and ■2 are
These are the outputs of each SQU cutting device connected to pickup coils 1-1 and 1-2, respectively. V□-v2 is the difference between the two, and the background signal can be significantly reduced.

Focusing on the signals △V□ and △v2 from the defect, formula (1)
, (2), and (3), the ratio between the two can be expressed as follows.

Here, N is an index. Transforming equation (14), if N″:1, it is determined from equation (1) that it is a background signal that depends on the surface shape of the object to be measured.If N clause is 3.5, then It is determined that it is a rectangular defect from Equation (2), and if it is N Misaki 5, it is determined that it is a circular defect from Equation (3).Therefore, the defect shape can be determined by a single scan, and conventional The time required to measure the defect shape can be significantly shortened compared to when the defect shape was determined by scanning.

Once the defect shape is determined, the relationship between the defect area and the 5QUID output is known, and the defect area can be easily measured. The above processing can be performed by the computer 6 shown in FIG. Although a description of the case where three or more pickup coils are provided is omitted, the measurement accuracy improves as more pickup coils are provided.

In addition, when the pickup coil is connected as shown in Fig. 4, the 5QUID output is Vl-V as shown in Fig. 6,
be equivalent to. In this case, it is not possible to obtain the index N for determining the defect shape as shown in equation (15). However, the 5QUID output is smaller than the value (indicated as 1 in the figure) that requires range switching, that is, range switching is not required during defect measurement. Therefore, in this case, measurement errors due to range switching can be eliminated.

FIG. 7 shows an embodiment in which double pickup coils are combined in consideration of background noise removal, and the types of defects can also be determined. Specifically, the same 5Q is added to the example in Figure 4.
This is in addition to the UID system. Pickup coils 1-1 and 1=-1' and 1-2 and 1-2' reduce background noise, respectively. Furthermore, the type of defect is determined by comparing the amount of difference between 1-1 and 1-1' and the amount of difference between 1-2 and 1-2'. According to this embodiment, background noise can be reduced and signals caused by defects can be amplified, so defects can be detected with high precision. An example using a fracture inspection device will be shown. In this device, a skid sensor is placed at the tip of a device for driving a skid inspection device, such as a commercially available articulated industrial robot, and measures objects to be inspected such as piping. Based on the results, we are equipped with a determination device that can calculate and evaluate the strength margin of the piping through stress analysis and other methods. This makes it possible to evaluate the strength of the inspection object at the same time as detecting defects, improving reliability.

〔Effect of the invention〕

According to the present invention, there is an effect that background signals depending on the surface shape of the object to be measured can be significantly reduced. moreover,
Since five QUID devices were connected to each pickup coil, the shape and area of the defect could be measured with a single scan. Furthermore, if a 5QUID device is connected to each pair of connected pickup coils whose winding directions are opposite to each other, the number of range changes is greatly reduced, and measurement accuracy is improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a perspective view showing the structure of a pickup coil, FIG. 3 is a perspective view showing the relationship between two pickup coils, and FIG. 5(a) to (c) are explanatory diagrams showing conventional measurement results. FIG. 6 is an explanatory diagram showing measurement results according to the present invention. FIG. 7 1 is a configuration diagram showing an embodiment of a multiplex pickup coil, FIGS. 8 to 11 are explanatory diagrams explaining the basis of formulas (1) to (3) used in the present invention, and FIG. 12 is a diagram showing a strength tolerance determination device. FIG. 2 is a configuration diagram using a skid device. 1...Pickup coil, 2...Excitation coil, 3
...Heat switch, 4...5 QUID device, 5... Control and measurement device, 6... Computer, 7.
...Refrigerant, 8...Balance ring, 9
...Object to be measured. Agent Unuma Tatsu Nohi Town 2 A, F 1 Coil M Fox Coil Heat Switch Skid It Control' F, J (a) (b) (a) (b) (a) (b) (a) (b) (a) (b) (a) (b) (a) (b) (b)

Claims (1)

[Claims] 1. A pickup coil that detects a magnetic flux signal from an object to be measured, a skid device that receives a signal from the pickup coil, and an arithmetic processing unit that receives and processes an output signal from the skid device. In a skid-based non-destructive inspection device equipped with a skid, a plurality of pickup coils are provided at different distances from the object to be measured, a skid device is provided for each pickup coil, and an arithmetic processing unit calculates the difference between the outputs of each skid. 1. A nondestructive inspection device using a skid, characterized in that it is configured to perform calculations to reduce a background signal caused by the surface shape of an object to be measured. 2. Using a skid that includes a pickup coil that detects a magnetic flux signal from the object to be measured, a skid device that receives the signal from the pickup coil, and an arithmetic processing unit that receives and processes the output signal from the skid device. In a non-destructive inspection device, a plurality of pickup coils are provided at different distances from the object to be measured, a skid device is provided for each pickup coil, and an arithmetic processing unit calculates a predetermined skid output value and the object to be measured. 1. A non-destructive inspection device using a skid, characterized in that the defect shape is determined from each skid output value actually measured based on the relationship between the distance from the object and the defect shape of the object to be measured. 3. Using a skid that includes a pickup coil that detects a magnetic flux signal from the object to be measured, a skid device that receives the signal from the pickup coil, and an arithmetic processing unit that receives and processes the output signal from the skid device. In non-destructive testing equipment, a plurality of pickup coils are provided at different distances from the object to be measured and with different winding directions, and a skid device is provided for each coil pair of each pickup coil with a different winding direction. is formed to determine the defect shape from each actually measured skid output value based on the relationship between the predetermined skid output value, the distance from the object to be measured, and the defect shape of the object to be measured. A non-destructive inspection device featuring a skid. 4. The skid according to claim 2 or 3, wherein the arithmetic processing unit is configured to calculate the area of the defect from the determined defect shape based on a predetermined relationship between the area of the defect and the skid output. non-destructive testing equipment. 5. In any one of claims 1 to 4, the distance (h) between the object to be measured and the pickup coil is 20 to 100 mm,
The spacing (Δ) between multiple pickup coils is 2 to 10 m.
A non-destructive inspection device using a skid set at m. 6. In any one of claims 1 to 4, the distance (h) between the object to be measured and the pickup coil and the interval (Δ) between the plurality of pickup coils are set under the condition that 10≦h/Δ≦20 is satisfied. Non-destructive testing equipment using skids.