JP2008128816A - Non-destructive inspection device by potential difference method, and measurement method of non-destructive inspection using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-destructive inspection device by a potential difference method that eliminates error due to the positional displacement of a current supply terminal and a potential difference measurement terminal, and reduces the error due to the displacement of the distance between the terminals, and to provide a measurement method of the non-destructive inspection capable of increasing the reproducibility and accuracy of the measurement result using it. <P>SOLUTION: The non-destructive inspection device has a plate-like base 2 that faces a structure 1 via a plurality of leg sections 7 and 8 and has a plurality of holes 23, 24, 25 and 26. The non-destructive inspection device has a pair of current supply terminals 3 and 4 disposed so that their tips can come into contact with or separate from a structure 1 surface, and a pair of potential difference measurement terminals 5 and 6 that are arranged inside or outside the space between the current supply terminals 3 and 4 and disposed so that their tips can come into contact with or separate from the structure 1 surface. The current supply terminals 3 and 4 and potential difference measurement terminals 5 and 6 are guided to the holes 23, 24, 25 and 26 in the plate-like base 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a nondestructive inspection apparatus using a potential difference method used for nondestructive inspection of a structure such as a metal tube in a nuclear power plant, and a measurement method of nondestructive inspection using the same, and in particular, the reproducibility and accuracy of measurement results are improved. The present invention relates to a non-destructive inspection apparatus using a contact potential difference method that can be enhanced and a measurement method using the same.

  Currently, maintenance standards have been introduced for defect inspection of structures in nuclear power plants. It is economically beneficial to operate the plant while monitoring small defects that do not affect the soundness of the structure based on maintenance standards. Proper operation of maintenance standards for structures requires high defect detection and dimensional evaluation capabilities with nondestructive inspection technology. One of non-destructive inspection methods for structures is a contact potential difference method.

The contact potential difference method, V ₁ the potential difference measured by the location of the defective portion is pressed against the terminals on the object to be measured, the potential difference measured by the healthy portion and V _0, these differences, i.e. [Delta] V = (V ₁ This is a method for determining the presence or absence of a defect by detecting -V ₀ ).

  In the potential difference method using direct current, a current flows also in the plate thickness direction of the member. Therefore, a buried crack and a back surface crack can be detected as a change in potential difference caused by a disturbance in the current field. Further, it has been confirmed that this method can evaluate closed cracks such as stress corrosion cracks and fatigue cracks which are currently problematic (see, for example, Patent Document 1, Patent Document 2, or Patent Document 3). However, with the conventional method, if the part to be inspected is about 3 cm to 4 cm thick, it is difficult for current to reach the back of the part where the crack exists, and detection sensitivity is insufficient. Not. In particular, there is a problem that the potential difference measured at the actual potential difference measuring terminal has a large variation every time the measurement is repeated. This variation is because the current supply terminal and the potential difference measurement terminal are provided on one probe, and the probe is lifted from the surface of the object to be measured by handling or brought into contact with the surface of the object to be measured. This is because errors due to misalignment caused by handling when they are brought into contact with errors due to differences in contact postures caused by handling and distances between terminals caused by mechanical crossing of springs formed on the terminals.

As for the point that the current is difficult to reach and the detection sensitivity is insufficient, a method of simply increasing the detection sensitivity by adding a large current has been attempted. However, in this case, there is a problem that noise due to the Seebeck effect is generated due to heat generation of the terminal portion, and the detection sensitivity cannot be improved.
For this reason, attention has been focused on measurement techniques that can improve the reproducibility and accuracy of measurement results and increase the detection sensitivity.

Japanese Patent No. 2856413 Japanese Patent No. 3167449 JP 2006-308324 A

  As described above, in the conventional technology, the error due to the positional deviation of the current supply terminal and the potential difference measurement terminal overlaps with the error due to the deviation of the distance between the terminals, so that there is a large variation each time the measurement is repeated, and reproducibility and accuracy are high. It was low and there was a problem with reliability.

The present invention eliminates the error due to the positional deviation between the current supply terminal and the potential difference measuring terminal, limits the cause of the error to the error due to the deviation between the distances between the terminals, and reduces the error due to the deviation between the distances between the terminals. An object of the present invention is to provide a nondestructive inspection apparatus using a potentiometric method capable of suppressing the above.
Moreover, it aims at providing the measuring method of the nondestructive inspection which can improve the reproducibility and accuracy of a measurement result using this.

  According to the present invention, a plate-like base having a plurality of terminal guides facing the object to be measured via a plurality of legs disposed on the surface of the object to be measured, and a tip that is in contact with or separated from the surface of the object to be measured. A pair of current supply terminals that can be provided, and a potential difference measurement that is disposed inside or outside the pair of current supply terminals and that has a tip that can be contacted and separated from the surface of the object to be measured. A non-destructive inspection apparatus using a potentiometric method, wherein the pair of current supply terminals and the pair of potential difference measuring terminals are guided by the terminal guides of the plate base. It is done.

  In addition, there is provided a nondestructive inspection apparatus using a potentiometric method, comprising a first elastic member for applying a bias to the current supply terminal so that the tip of the current supply terminal protrudes in the direction of the object to be measured. .

  Furthermore, there is provided a nondestructive inspection apparatus based on a potentiometric method, comprising a second elastic member that applies a bias to the potential difference measuring terminal so that a tip of the potential difference measuring terminal protrudes in the direction of the object to be measured. .

  In addition, the present invention provides a nondestructive inspection apparatus using a potentiometric method, characterized in that a first lock member is provided for preventing the tip of the current supply terminal from contacting the surface of the object to be measured.

  Further, the present invention provides a nondestructive inspection apparatus using a potential difference method, comprising a second lock member that prevents the tip of the potential difference measuring terminal from contacting the surface of the object to be measured.

  Further, the present invention provides a nondestructive inspection apparatus using a potential difference method, wherein each of the pair of current supply terminals comprises a plurality of current supply terminals.

  Further, the Z-axis stage that enables the plate base to move in a direction perpendicular to the surface of the object to be measured, or the current supply terminal and the potential difference measuring terminal to move in a direction perpendicular to the surface of the object to be measured. A non-destructive inspection apparatus using a potential difference method is provided.

  According to the present invention, the non-destructive inspection apparatus based on the potential difference method is used, and the current supply terminal and the potential difference measurement terminal are contacted and separated a plurality of times with respect to a predetermined location on the surface of the object to be measured. A nondestructive inspection measuring method is obtained, in which the potential difference corresponding to is measured a plurality of times, and an average value of the measured values is obtained and used as a measurement result of the predetermined portion.

  According to the present invention, a plate-like base facing the object to be measured is provided via a plurality of legs arranged on the surface of the object to be measured, and a pair of current supply terminals and a pair of potential difference measuring terminals are provided on the plate. Since it is guided by the terminal guide of the base and can be moved to and away from the surface of the object to be measured, handling for contact and separation is not required by fixing the leg to the surface of the object to be measured and moving the terminal to and away from the surface. It becomes. Therefore, there is no position shift due to handling, and errors caused by it are eliminated. Furthermore, the cause of the deviation of the distance between the terminals is not the component of the contact posture difference accompanying the handling, and is limited to the component due to the gap between each terminal guide and each terminal.

  If the deviation of the distance between the terminals is limited to the gap component between the terminal guides and the terminals, the variation due to this can be easily grasped by measuring the contact and separation of the terminal tip a plurality of times. Therefore, the reproducibility and accuracy of the measurement result can be improved by averaging the measurement result.

  Each terminal guide desirably guides the terminal in a direction perpendicular to the plate base. Each terminal guide guides the terminal along a certain trajectory, and can have a hole, groove, rail shape, or bowl-like configuration. The number of legs is preferably three in terms of stabilizing the posture of the plate-like base with respect to the surface of the object to be measured. If the weight is attached to the plate-like base, the position of the leg portion can be stabilized and the posture of the plate-like base can be kept stable.

  When a bias is applied to the current supply terminal by the first elastic member so that the tip of the current supply terminal protrudes in the direction of the object to be measured, the leg is placed on the surface of the object to be measured and at the same time the tip of the current supply terminal is on the surface of the object to be measured. Since a stable contact pressure is ensured while making contact, accurate measurement can be performed quickly.

  When a bias is applied to the potential difference measuring terminal by the second elastic member so that the tip of the potential difference measuring terminal protrudes in the direction of the object to be measured, the leg is placed on the surface of the object to be measured and at the same time the tip of the potential difference measuring terminal is on the surface of the object to be measured. Since a stable contact pressure is ensured while making contact, accurate measurement can be performed quickly. A spiral spring or the like can be used as the first elastic member and the second elastic member.

  If the first lock member that prevents the tip of the current supply terminal from contacting the surface of the object to be measured is provided, the tip of the current supply terminal is separated from the surface of the object to be measured during non-measurement or measurement standby, and the tip of the current supply terminal is damaged. Can be protected from etc.

  If the second locking member that prevents the tip of the potential difference measuring terminal from contacting the surface of the object to be measured is provided, the tip of the potential difference measuring terminal is separated from the surface of the object to be measured when not measuring or waiting for measurement to break the tip of the potential difference measuring terminal. Can be protected from etc.

  When each of the paired current supply terminals is composed of a plurality of current supply terminals, current is supplied simultaneously from the plurality of current supply terminals in parallel, and the current supplied from the individual current supply terminals is suppressed, while the current to be measured is large. A current can be supplied. Thereby, a potential difference can be increased and detection sensitivity can be increased. On the other hand, the amount of Joule heat generated at each terminal portion is reduced. Therefore, noise generation due to the thermoelectromotive force generated by conducting heat to the potential difference measurement terminal can be suppressed, and detection sensitivity can be improved. Furthermore, the melting phenomenon of each terminal accompanying Joule heat generation can be prevented.

When equipped with a Z-axis stage that allows the plate base to move in the vertical direction with respect to the surface of the object to be measured, the position of the plate base is controlled in the vertical direction by an actuator, etc. to automate the contact and separation of each terminal. Is possible.
In addition, if a Z-axis stage is provided that allows the current supply terminal and the potential difference measurement terminal to move in a direction perpendicular to the surface of the object to be measured, the positions of the current supply terminal and the potential difference measurement terminal are controlled in the vertical direction by an actuator or the like It is possible to automate contact and separation of each terminal and measurement.

  Using these non-destructive inspection devices based on the potential difference method, the current supply terminal and the potential difference measurement terminal are contacted and separated multiple times with respect to a predetermined location on the surface of the object to be measured, and the potential difference corresponding to the predetermined location is measured multiple times. If the average value of the measured values is obtained and used as the measurement result at a predetermined location, the reproducibility and accuracy of the measurement result will be improved, and even a defect with low detection sensitivity typified by a crack on the back of a thick member can be detected. Become.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining the principle of an embodiment of a nondestructive inspection apparatus according to the potential difference method of the present invention. In the figure, reference numeral 1 denotes a structure which is an object to be measured, and here, a part of a metal circular tube is shown. The structure 1 has a thickness t, a width w, and a length l. The rear surface 1b of the structure 1 has a width b extending toward the pq plane, that is, the front surface 1a along the qr plane. A semi-elliptical crack 1c having a depth a is formed. In the figure, an arrow p, an arrow q, and an arrow r indicate orthogonal coordinate axes.

  Reference numeral 2 denotes a plate-like base of the nondestructive inspection apparatus. The plate-like base 2 is provided with a pair of current supply terminals 3 and 4 and a pair of potential difference measuring terminals 5 and 6. The tips of the current supply terminals 3 and 4 and the potential difference measurement terminals 5 and 6 are in contact with the surface 1a of the structure 1 on the p-axis, and their positions are arranged symmetrically with respect to the qr plane. .

  11 is a stabilized DC power supply for supplying current to the current supply terminals 3 and 4 of the nondestructive inspection apparatus, 12 is a shunt resistor connected in series to the DC stabilized power supply 11, and 13 is a potential difference between the shunt resistors 12. A digital multimeter for confirming the current of the DC stabilized power supply 11, 14 is a digital multimeter for measuring the potential difference between the potential difference measuring terminals 5 and 6, and 15 is a recording of the potential difference obtained by the digital multimeter 14. The computer performs arithmetic processing for obtaining an average value, arithmetic processing for obtaining a standard deviation, comparison / analysis processing, and the like.

  When such a nondestructive inspection apparatus is used, the potential difference between the potential difference measuring terminals 5 and 6 is large at the crack 1c portion of the structure 1 and the potential difference is small at the portion away from the crack 1c. Thus, the presence or absence of the crack 1c or the size of the crack 1c can be evaluated.

  FIG. 2 is a front view of an essential part of the plate-like base 2 related to FIG. In the figure, the plate-like base 2 is attached with leg portions 7 and 8 with sharp tips and a leg portion 9 (not shown) toward the structure 1 side. Both are h. Therefore, the plate-like base 2 is provided in parallel with the surface 1a of the structure 1 while maintaining a distance h.

  Holes 23 and 24 and holes 25 and 26 as terminal guides are provided in the plate-like base 2 perpendicularly to the plate-like base 2 and symmetrically in the figure. The holes 23 and 24 have current supply terminals 3 and 4. The holes 25 and 26 are provided with potential difference measuring terminals 5 and 6, respectively. Terminal stops 33, 34 and terminal stops 35, 36 are attached to the current supply terminals 3, 4 and the potential difference measuring terminals 5, 6 so that their tips are not in contact with the surface 1 a of the structure 1. The terminal stoppers 33 and 34 and the terminal stoppers 35 and 36 are detachable from the current supply terminals 3 and 4 and the potential difference measuring terminals 5 and 6. FIG. 2 is an inserted diagram and shows a state where measurement is not performed. When the terminal stoppers 33 and 34 and the terminal stoppers 35 and 36 are removed, the tips of the current supply terminals 3 and 4 and the potential difference measuring terminals 5 and 6 come into contact with the surface 1a of the structure 1 and measurement is possible.

  Shelves 21 and 22 are attached to the left and right sides of the plate-like base 2, and weights 31 and 32 having predetermined weights are placed on the shelves 21 and 22. The weights 31 and 32 stabilize the positions of the leg portions 7, 8 and 9 and prevent the posture of the plate-like base 2 from becoming unstable due to the repulsive force of the spring 43 described later.

  FIG. 3 is an explanatory diagram for explaining the relationship between the current supply terminal 3 and the hole 23, and FIG. 3A is a cross-sectional view of the main part of the hole 23. The hole 23 has a structure in which the diameter of the lower end thickness M1 portion is Φ1, the intermediate thickness M2 is Φ2, and the upper end is attached with a lid 2a having a thickness M3 and a diameter Φ1. Yes. The relationship between Φ1 and Φ2 is Φ1 <Φ2.

  FIG. 3 (b) shows a cross-sectional view of the current supply terminal 3. The current supply terminal 3 has a diameter slightly smaller than Φ1 and is cylindrical, the lower end 3a is convex, and the distance L1 from the lower end 3a. Is provided with a flange portion 3b having a thickness L2 and a diameter larger than Φ1 and smaller than Φ2. A screw 3c having a predetermined length is formed from a position at a distance L3 above the flange 3b.

  FIG. 3C is a cross-sectional view of the main part in a state where the current supply terminal 3 is incorporated in the hole 23. In order to incorporate the current supply terminal 3, first, the spiral spring 43 is passed to the flange 3b, and the current supply terminal 3 is inserted into the hole 23 in a state where the lid 2a is removed. Next, the upper side of the current supply terminal 3 is passed through the hole of the lid 2 a, and the lid 2 a is attached to the plate base 2 integrally. Subsequently, the screw 3c and the ring 37 formed with a screw on the inner surface are screwed together. The diameter of the ring 37 is substantially the same as Φ2. In this state, the spring 43 is slightly contracted between the flange 3b and the lid 2a, and the lower end 3a of the current supply terminal 3 protrudes toward the structure 1. At this time, the relationship between the height h, the thickness M1, and the distance L1 is L1> (M1 + h). The relationship between the distance L3 and the thickness L2, the thickness M2, and the thickness M3 is L3> (M2 + M3) −L2.

  FIG. 3D is a cross-sectional view of the main part in a state where the leg portions 7 and 8 and the leg portion 9 are placed on the structure 1. In this state, the lower end 3a of the current supply terminal 3 is in contact with the surface 1a of the structure 1, and measurement is possible. Since the height h, the thickness M1, and the distance L1 have a relationship of L1> M1 + h, the lower end 3a of the current supply terminal 3 is pushed up against the force of the spring 43. The movement amount ΔL1 is obtained by the equation: ΔL1 = L1− (M1 + h).

  FIG. 4 is a cross-sectional view of the main part in a state where the terminal stopper 33 is attached to the current supply terminal 3. The current supply terminal 3 is further lifted against the force of the spring 43 from the measurable state, and the lower end 3a of the current supply terminal 3 and the surface 1a of the structure 1 are separated. Subsequently, a terminal stopper 33 is inserted into a gap formed between the lid 2 a and the ring 37. The terminal stopper 33 is a ring-shaped spacer having a predetermined height. An opening is provided in a part of the ring, and the current supply terminal 3 can be inserted and removed from this opening. When the terminal stopper 33 is attached in this way, the state where the lower end 3a of the current supply terminal 3 is stably kept away from the surface 1a of the structure 1 can be stably maintained. Is protected.

  As described above, the relationship between the current supply terminal 3 and the hole 23 has been described with reference to FIGS. 3 and 4. However, the relationship between the current supply terminal 4 and the hole 24 and the relationship between the potential difference measurement terminals 5 and 6 and the holes 25 and 26 are also completely different. Since it is the same, the description thereof is omitted below.

  FIG. 5 is a principle circuit diagram related to FIG. 1 and is for explaining the operation of the switch circuit used for supplying a stable current before and after the measurement. In the figure, reference numerals 16 and 17 denote switch circuits, and the same circuit elements as those in FIG. The illustration of the computer 15 is also omitted.

  When detecting a minute defect, the current supplied from the DC stabilized power supply 11 must be stable before and after measurement. As a work procedure of this circuit, first, the switch circuit 16 is turned on and the switch circuit 17 is turned off to stabilize the current. When the current is stabilized, the switch circuit 17 is turned on and the switch circuit 16 is turned off so that the current flows through the current supply terminals 3 and 4. When the current supply terminals 3 and 4 are turned off, the switch circuit 16 is turned on and the switch circuit 17 is turned off. Whether the current is stably supplied before and after the measurement is confirmed by the digital multimeter 13 that measures the potential difference between the shunt resistors 12. By operating in this way, a stable current before and after measurement is reliably supplied to the structure 1, and the reproducibility and accuracy of the measurement result can be improved. That is, compared with the conventional circuit which does not use such switch circuits 16 and 17, by providing the switch circuits 16 and 17, noise from the DC stabilized power supply 11 is reduced, and the reproducibility and accuracy of the measurement results are improved. Can be increased.

  Next, another embodiment of the nondestructive inspection apparatus according to the potential difference method of the present invention will be described. In the apparatus of this embodiment, each pair of current supply terminals is constituted by a plurality of current supply terminals, and three current supply terminals are provided on the plate-like base. Other configurations are the same as those of the apparatus of the above-described embodiment. Hereinafter, this main part will be described.

  FIG. 6 is an explanatory view of the main part of another embodiment of the present invention. FIG. 6A is a plan view of the main part of the plate-like base 51. The plate-like base 51 is provided with holes 62, 63, 64 and 65 as terminal guides so that three current supply terminals are provided respectively. , 66 and 67 are provided symmetrically in the figure, and the holes 68 and 69 are provided symmetrically in the figure. Current supply terminals 52, 53, 54 and current supply terminals 55, 56, 57 are attached to the holes 62, 63, 64 and holes 65, 66, 67, respectively, and potential difference measurement terminals 58, 59 are attached to the holes 68 and 69. Are attached to each.

  6B is a cross-sectional view of the main part when the current supply terminals 52, 53, 54, the current supply terminals 55, 56, 57, and the potential difference measurement terminals 58, 59 are attached to the plate-like base 51. Current supply terminals 52, 53, 54 and current supply terminals 55, 56, 57 are attached to 63, 64 and holes 65, 66, 67, and potential difference measurement terminals 58, 59 are attached to holes 68 and 69, respectively.

  The front ends of the current supply terminals 52, 53, 54 and the current supply terminals 55, 56, 57 can be brought into contact with and separated from the surface of the structure 50. The tips of the current supply terminals 52, 53, 54 and the current supply terminals 55, 56, 57 can be brought into contact with the surface of the structure 50, respectively, and current can be supplied simultaneously to the three current supply terminals in parallel. is there. When all the currents are supplied to the structure 50, a large potential change is generated in response to an increase in current even with a small change in resistance value, so that there is a crack on the back surface of the thick structure 50 member. Even in this case, the potential difference measurement terminals 58 and 59 can be measured with high sensitivity.

  In addition, since the current supplied to the individual current supply terminals 52, 53, 54, 55, 56, 57 is not increased, the amount of Joule heat generated at each terminal portion is reduced, and the heat is conducted to the potential difference measurement terminals 58, 59. Thus, noise generation due to the thermoelectromotive force generated can be suppressed.

  Next, still another embodiment of the nondestructive inspection apparatus according to the potential difference method of the present invention will be described. In this embodiment, although not shown, the plate base 2 described with reference to FIGS. 1 to 4 is attached to a Z-axis stage that can move vertically up and down with respect to the structure 1. The Z-axis stage is provided with a linear actuator, and the linear actuator moves the plate base 2 up and down. The height of the plate-like base is controlled by the operation of the linear actuator to control the contact and separation between each terminal and the structure 1. Furthermore, the sequencer incorporates a program for synchronizing the contact timing of each terminal and the measurement timing, and the program can be changed by the computer 15. The sequencer also has a built-in program for controlling the relay switch, and can supply a stable current to the sensor by operating the switch circuit. In this way, measurement automation was realized.

Table 1 shows data measured using the nondestructive inspection apparatus described with reference to FIGS.
The structure 1 used in this measurement is a SUS304 stainless steel material of l = 300 mm, w = 300 mm, t = 40 mm, and the size of the crack 1c is a / t = 0.37, b / a = 4.7. It is.

  A current of 20 amperes was supplied from the current supply terminals 3 and 4, and the same portion was measured 10 times for each measurement set, and an average value and a standard deviation were calculated. This was performed for 6 measurement sets, and the average value and standard deviation of each measurement set and the overall average value and standard deviation were calculated and used as experimental results. The overall average value and standard deviation are 430.1 μV and 0.99 in the region without cracks, 435.6 μV and 0.84 in the region with cracks, and the potential difference due to the presence or absence of cracks is 5 .5 μV. This result agrees well with the result obtained by theoretical analysis.

  Next, Table 2 shows data measured by changing the current supplied from the current supply terminals 3 and 4 with respect to the previous embodiment.

  In this measurement, a current of 30 amperes was supplied from the current supply terminals 3 and 4 without changing the structure 1, and the same part was measured 10 times per measurement set, and the average value and the standard deviation were calculated. This was performed for 6 measurement sets, and the average value and standard deviation of each measurement set and the overall average value and standard deviation were calculated and used as experimental results. The overall average value and standard deviation are 643.5 μV and 0.99 in the region without cracks, and 651.4 μV and 0.59 in the region with cracks. .9 μV. This result agrees well with the result obtained by theoretical analysis. The improvement in detection sensitivity can be confirmed as compared with the previous embodiment.

  The non-destructive inspection system based on the potential difference method according to the present invention can be used for non-destructive inspection of structures such as metal pipes in nuclear power plants, and detects defective parts such as cracks and thinnings in piping with high accuracy. it can.

It is principle explanatory drawing of embodiment of the nondestructive inspection apparatus by the electric potential difference method of this invention. It is a principal part front view of the plate-shaped foundation of the nondestructive inspection apparatus by the potentiometric method shown in FIG. It is explanatory drawing for demonstrating the relationship between the electric current supply terminal and hole of the plate-shaped base of the nondestructive inspection apparatus by a potential difference method shown in FIG. (A) is a cross-sectional view of the main part of the hole, (b) is a cross-sectional view of the current supply terminal, (c) is a cross-sectional view of the main part in a state where the current supply terminal is incorporated in the hole, and (d) is the leg part and the leg part. It is principal part sectional drawing of the state which mounted on the structure. It is principal part sectional drawing of the state which attached the terminal stop to the current supply terminal of the plate-shaped base of the nondestructive inspection apparatus by the potentiometric method shown in FIG. FIG. 2 is a principle circuit diagram of the nondestructive inspection apparatus using the potential difference method shown in FIG. 1. It is principal part explanatory drawing of other embodiment of the nondestructive inspection apparatus by the potentiometric method of this invention. (A) is a principal part top view of a plate-like base, (b) is a principal part front view when attaching a current supply terminal, a current supply terminal, and a potential difference measurement terminal to a plate-like base.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,50 Structure 2,51 Plate base 3,4,52,53,54,55,56,57 Current supply terminal 5,6,58,59 Potential difference measurement terminal 7,8,9 Leg 11 DC stabilization Power supply 12 Shunt resistor 13, 14 Digital multimeter 15 Computer 16, 17 Switch circuit 23, 24, 25, 26, 62, 63, 64, 65, 66, 67, 68, 69 hole 33, 34, 35, 36 Terminal stop 37 Ring 43 Spring

Claims (8)

  A plate-like base having a plurality of terminal guides facing the object to be measured via a plurality of legs arranged on the surface of the object to be measured, and a pair of tips provided to be able to contact and separate from the surface of the object to be measured A current supply terminal that forms a pair, and a potential difference measurement terminal that forms a pair that is disposed inside or outside the pair of current supply terminals and that has a tip that can be contacted and separated from the surface of the object to be measured. A non-destructive inspection apparatus using a potential difference method, wherein a pair of current supply terminals and a pair of potential difference measuring terminals are guided by each terminal guide of the plate-like base.   The nondestructive inspection by the potentiometric method according to claim 1, further comprising a first elastic member that applies a bias to the current supply terminal so that a tip of the current supply terminal protrudes in a direction of the object to be measured. apparatus.   3. The potential difference method according to claim 1, further comprising: a second elastic member that applies a bias to the potential difference measurement terminal such that a tip of the potential difference measurement terminal protrudes in a direction of the object to be measured. Non-destructive inspection equipment.   The non-destructive method according to any one of claims 1 to 3, further comprising a first lock member that prevents the tip of the current supply terminal from contacting the surface of the object to be measured. Inspection device.   5. The non-destructive method according to claim 1, further comprising a second lock member that prevents the tip of the potential difference measuring terminal from contacting the surface of the object to be measured. Inspection device.   6. The nondestructive inspection apparatus according to the potential difference method according to claim 1, wherein each of the pair of current supply terminals includes a plurality of current supply terminals.   The Z-axis stage that enables the plate-like base to move in a direction perpendicular to the surface of the object to be measured, or the current supply terminal and the potential difference measurement terminal to be movable in a direction perpendicular to the surface of the object to be measured. The non-destructive inspection apparatus according to the potential difference method according to any one of claims 1 to 6, further comprising a Z-axis stage. The non-destructive inspection apparatus according to the potential difference method according to claim 1, wherein the current supply terminal and the potential difference measurement terminal are contacted and separated a plurality of times with respect to a predetermined location on the surface of the object to be measured. A non-destructive inspection measuring method, wherein a potential difference corresponding to a location is measured a plurality of times, an average value of the measured values is obtained and used as a measurement result of the predetermined location.

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