Flaw detection device and flaw detection method

Abstract

To provide a flaw detection device that has multiple flaw detection sensors and can detect a flaw of an inspection object while detecting proximity of each flaw detection sensor to the inspection object without depending on a mechanical device, such as a proximity sensor, and to provide a flaw detection method using such a flaw detection device.SOLUTION: A flaw detection device includes a head section 2 and a conduction detection section, and the head section 2 includes a mounting member 31, a flaw detection sensor capable of detecting the flaw of an inspection object comprising metal, and a contact 35 made of a conductive material. Multiple flaw detection sensors are disposed along an array direction (y) and are mounted to the mounting member 31, the multiple contacts 35 are disposed along the array direction (y) while being lined up with the rows of flaw detection sensors, project to the outside while exceeding the flaw detection sensors relative to a surface 30a of the mounting member 31, and are mounted to the mounting member 31. The conduction detection section can detect presence or absence of conduction between each of the contacts 35 and the inspection object.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a flaw detection device and a flaw detection method, and more particularly, to a flaw detection device provided with a mechanism for detecting the proximity between a flaw detection sensor and an object to be inspected, and a flaw detection method using such a flaw detection device.

Background Art

[0002] Using a flaw detection device equipped with a flaw detection sensor such as an ultrasonic flaw detection type or an eddy current flaw detection type, it is possible to detect flaws inside or on the surface of an object to be inspected. In order to perform a highly accurate inspection on an object to be inspected having various surface shapes using such a flaw detection device, it is important to arrange the flaw detection sensor at a predetermined distance from the surface of the object to be inspected on the surface of the object to be inspected. In order to position the flaw detection sensor in this way, a profiling mechanism may be attached to the flaw detection device. The profiling mechanism is disclosed, for example, in Patent Document 1 and Patent Document 2 by one of the inventors of the present case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] When performing flaw detection on an object to be inspected, as described above, it is useful to use a mimicking mechanism to place the flaw detection sensor as close as possible to the surface of the object to be inspected at a predetermined distance. However, due to structural or cost constraints, etc., there may be cases where a mimicking mechanism cannot be attached to the flaw detection device. Also, even if a mimicking mechanism is attached to the flaw detection device and the mimicking mechanism is used to place the flaw detection sensor at a predetermined inspection position as close as possible to the object to be inspected, there may be cases where the flaw detection sensor cannot be placed close enough to the predetermined inspection position, such as when the surface of the object to be inspected has large irregularities. In those cases, it is conceivable to detect how close the flaw detection sensor is to the object to be inspected, and if it is farther away than a predetermined distance, to take measures such as adjusting the position of the flaw detection device, adjusting the mimicking mechanism, and changing the measurement conditions for flaw detection. For such purposes, it is conceivable to provide a proximity sensor on the flaw detection device that can detect how close the flaw detection sensor is to the object to be inspected. As the proximity sensor, as disclosed in Patent Documents 3 and 4 above, electromagnetic types, capacitance types, etc. are known.

[0005] However, in order to perform highly accurate flaw detection using ultrasonic flaw detection sensors or eddy current flaw detection sensors, it is necessary to place them in contact with or in a position close to the surface of the object to be inspected. On the other hand, ordinary proximity sensors are not suitable for being used close to the surface of the object to be inspected like flaw detection sensors, and in fact, it is not common to use them in combination with flaw detection sensors. If a proximity sensor is attached in the immediate vicinity of a flaw detection sensor in a flaw detection device, there is a possibility that the proximity sensor will come into contact with the object to be inspected, causing problems such as damage to the proximity sensor. In order to avoid contact of the proximity sensor with the object to be inspected, it is conceivable to attach the proximity sensor at a certain distance from the flaw detection sensor, while bringing the flaw detection sensor sufficiently close to the surface of the object to be inspected and ensuring that the proximity sensor maintains a safe distance from the surface of the object to be inspected. However, in that case, since the positions of the flaw detection sensor and the proximity sensor are separated, when there are irregularities on the surface of the object to be inspected, the surface condition of the object to be inspected at the position where the flaw detection sensor is attached may not be sufficiently reflected in the measurement results of the proximity sensor, and it may become impossible to accurately evaluate the proximity of the flaw detection sensor to the surface of the object to be inspected with the proximity sensor. In addition, proximity sensors, including those disclosed in Patent Documents 3 and 4, are precision instruments, and it is difficult to maintain them in a state where they operate with high precision in an environment exposed to severe conditions such as vibration, atmosphere changes, and temperature changes, like the manufacturing sites in the steel industry.

[0006] Furthermore, in recent years, as is also used in the flaw detection device of Patent Document 2, flaw detection devices in which a plurality of flaw detection sensors, such as array probes, are arranged are often used. In a flaw detection device equipped with such a plurality of flaw detection sensors, in order to accurately detect the proximity to the object to be inspected for each flaw detection sensor with a proximity sensor, it is necessary to provide a corresponding proximity sensor in the vicinity for each one or a small number of flaw detection sensors. Then, a large number of proximity sensors need to be provided for the entire flaw detection device. This may cause problems such as an increase in size, complexity of the structure, and a rise in manufacturing costs in the flaw detection device and its control system.

[0007] In view of the above, the problem to be solved by the present invention is to provide a flaw detection device equipped with a plurality of flaw detection sensors, which can detect flaws in an object to be inspected while detecting the proximity of each flaw detection sensor to the object to be inspected without using a mechanical device such as a proximity sensor, and a flaw detection method using such a flaw detection device.

Means for Solving the Problem

[0008] In order to solve the above problems, the flaw detection device and flaw detection method according to the present invention have the following configurations.

[0009] [1] The flaw detection device according to the present invention has a head portion and a conduction detection portion. The head portion includes an attachment member, a flaw detection sensor capable of detecting a flaw in an object to be inspected made of metal, and a contact made of a conductive material. The flaw detection sensors are arranged in a plurality along the arrangement direction and are attached to the attachment member. The contacts are arranged in a plurality along the arrangement direction side by side with the rows of the flaw detection sensors and protrude outward from the surface of the attachment member more than the flaw detection sensors and are attached to the attachment member. The conduction detection portion is capable of detecting the presence or absence of conduction between each of the contacts and the object to be inspected.

[0010] [2] In the aspect of [1] above, the contact may be composed of a rolling member that can roll on the surface of the object to be inspected, and a plurality may be arranged along the arrangement direction on both sides sandwiching the row of the flaw detection sensors.

[0011] [3] In the aspect of [2] above, the rolling member is preferably a ball roller.

[0012] [4] In any one of the aspects from [1] to [3] above, the conduction detection portion preferably includes a power supply portion that applies a voltage between the object to be inspected and the contact, and a measurement portion that detects the presence or absence of conduction between each of the object to be inspected and the contact.

[0013] [5] In any one of the aspects [1] to [4] above, the flaw detection sensor may be an eddy current flaw detection sensor.

[0014] [6] In any one of the aspects [1] to [5] above, the flaw detection sensor may be attached to the attachment member in the form of a plurality of flexible probes arranged along the arrangement direction on the surface of a substrate that can be bent and deformed.

[0015] [7] In the aspect of [6] above, a support member and an elastic member are coupled to the flexible probe. One end of the elastic member is coupled to the support member along the deformation axis, and the other end is coupled to the side opposite to the surface of the flexible probe where the flaw detection sensor is provided. The elastic member may be elastically deformable along the deformation axis with different deformation amounts for each position along the arrangement direction.

[0016] [8] In the flaw detection method according to the present invention, when performing flaw detection on an inspection object made of metal while moving the head portion along the surface of the inspection object using any one of the flaw detection devices [1] to [7] above, the flaw detection is started with each of the contacts in contact with the surface of the inspection object, and while performing flaw detection while moving the head portion, when the conduction detection unit detects that there is a contact that does not conduct with the inspection object, it is preferable to determine that the head portion is separated from the surface of the inspection object at the position of the contact.

Effect of the Invention

[0017] In the flaw detection device according to the present invention having the configuration of [1] above, a contact made of a conductive material is arranged on the attachment member of the head portion together with the flaw detection sensor, and a conduction detection unit for detecting the presence or absence of conduction between each of the contacts and the inspection object is provided. The contact and the conduction detection unit function as a proximity detection mechanism in the flaw detection device, and by the following mechanism, each flaw detection sensor can detect whether it is arranged close to the surface of the inspection object at a predetermined distance.

[0018] Since the contact is provided to protrude outward more than the flaw detection sensor with respect to the surface of the mounting member, when the contact is in contact with the surface of the inspection object, it is guaranteed that the flaw detection sensor is arranged at a position separated by a predetermined distance corresponding to the difference in the protruding amount from the contact (including the case where it is zero) with respect to the surface of the inspection object. And since the contact is made of a conductive material, when the contact comes into contact with the surface of a metal inspection object, conduction occurs between the inspection object and the contact. Therefore, when the conduction detection unit detects that there is conduction between the inspection object and the contact, it can be determined that the contact is in contact with the surface of the inspection object and the flaw detection sensor is arranged at a position at a predetermined distance with respect to the surface of the inspection object. On the other hand, when the conduction detection unit detects that there is no conduction between the inspection object and the contact, it can be determined that the contact is separated from the surface of the inspection object and the flaw detection sensor is arranged at a position farther than the predetermined distance with respect to the surface of the inspection object. Further, in the mounting member of the head portion, a plurality of flaw detection sensors are provided along the arrangement direction, and a plurality of rows of contacts arranged along the same arrangement direction are provided side by side with the row of flaw detection sensors. Thus, for each of the plurality of flaw detection sensors, it can be determined whether each flaw detection sensor is arranged at a predetermined distance with respect to the surface of the inspection object, using the presence or absence of conduction between the contact arranged in the vicinity of each flaw detection sensor and the inspection object as an index.

[0019] In this way, for each of the plurality of flaw detection sensors provided in the head portion, the proximity to the inspection object, that is, whether it is arranged sufficiently close to the surface of the inspection object, can be easily detected using the presence or absence of conduction between each of the plurality of contacts and the inspection object as an index. The contact only needs to be a member having conductivity, and there is no need to use a precision instrument such as a proximity sensor to detect the proximity of the flaw detection sensor. Therefore, the head portion can be configured with a simple structure and at low cost. Also, even in a harsh environment such as a manufacturing site in the steel industry, the proximity of the flaw detection sensor can be stably detected.

[0020] In the aspect of [2] above, the contactor is composed of rolling members, and a plurality of them are arranged on both sides with the rows of flaw detection sensors therebetween. In this case, in addition to serving as a proximity detection mechanism that detects the proximity of the flaw detection sensor to the inspection object using the electrical continuity between the contactor and the inspection object as an indicator, the contactor also serves as a motion assistance mechanism that assists the smooth movement of the head portion on the surface of the inspection object by rolling.

[0021] In the aspect of [3] above, the rolling member is a ball roller. Since the ball roller can freely roll in each direction on the surface of the inspection object, the contactor can function effectively as a proximity detection mechanism and a motion assistance mechanism even when the surface of the inspection object has a complex shape or is extensive.

[0022] In the aspect of [4] above, the conduction detection unit includes a power supply unit that applies a voltage between the inspection object and the contactor, and a measurement unit that detects the presence or absence of conduction between each of the inspection object and the contactor. In this case, it is possible to sensitively detect the presence or absence of conduction between the contactor and the inspection object while simplifying the configuration of the conduction detection unit.

[0023] In the aspect of [5] above, the flaw detection sensor is an eddy current flaw detection sensor. For the eddy current flaw detection sensor to perform flaw detection stably, it is particularly important to be arranged at a predetermined distance from the surface of the inspection object. However, in the flaw detection device according to this embodiment, based on the presence or absence of conduction between the contactor and the inspection object as an indicator, it is possible to sensitively determine whether the flaw detection sensor is arranged at a predetermined distance from the surface of the inspection object. Therefore, based on the determination result, if the flaw detection sensor is held at a predetermined distance from the surface of the inspection object, flaw detection by the eddy current flaw detection sensor can be stably executed.

[0024] In the aspect of [6] above, the flaw detection sensor is attached to the attachment member in the form of a flexible probe. In this case, by utilizing the bending deformation of the flexible probe, the distance between each flaw detection sensor and the surface of the inspection object can be adjusted. For example, when it is detected that some flaw detection sensors are too far away from the surface of the inspection object, using the presence or absence of conduction between the contactor and the inspection object as an indicator, by applying bending deformation to the flexible probe, it becomes possible to arrange the flaw detection sensors at a predetermined distance from the surface of the inspection object.

[0025] In the aspect of [7] above, an elastic member that can be elastically deformed with different deformation amounts for each position along the arrangement direction is coupled to the flexible probe. In this case, the elastic member acts as a following mechanism. That is, when the surface of the flexible probe is pressed against the surface of the inspection object, even if there are irregularities on the surface of the inspection object, for each position, the elastic member is deformed with a deformation amount corresponding to the irregularities, and the flexible probe undergoes bending deformation following the irregular shape of the surface of the inspection object. In this way, the surface of the flexible probe can be made to follow the surface of the inspection object. By providing the flaw detection device with a following mechanism, even if there are irregularities on the surface of the inspection object, it becomes easier for each flaw detection sensor to be stably maintained at a predetermined distance from the surface of the inspection object. By providing the flaw detection device with a following mechanism together with a proximity detection mechanism composed of a contactor and a conduction detection unit, while stably maintaining the proximity of the flaw detection sensor to the inspection object by the following mechanism, even if the flaw detection sensor may move away from the surface of the inspection object to a position farther than a predetermined distance despite the following mechanism, it can be detected by the proximity detection mechanism. In this way, by providing the flaw detection device with both a following mechanism and a proximity detection mechanism, it is possible to strongly suppress performing flaw detection with some flaw detection sensors remaining separated from the surface of the inspection object.

[0026] In the flaw detection method according to the present invention having the configuration of [8] above, flaw detection is performed using a flaw detection device provided with a contact and a conduction detection unit as a proximity detection mechanism. Even when starting flaw detection with each of the contacts in contact with the surface of the inspection object, that is, with each of the flaw detection sensors arranged at a predetermined distance from the surface of the inspection object, due to factors such as unevenness on the surface of the inspection object, while performing flaw detection while moving the head portion, some of the contacts may separate from the surface of the inspection object. Then, the conduction detection unit detects that there is no conduction between the contact and the inspection object, and based on this, it can be determined that the head portion is separated from the surface of the inspection object at the position of that contact. That is, it can be determined that the flaw detection sensor arranged in the vicinity of that contact is separated from the surface of the inspection object by a distance greater than the predetermined distance. The operator performing the flaw detection can take measures such as interrupting the flaw detection inspection, adjusting the constituent members of the flaw detection device such as the following mechanism, and reviewing the parameters related to the flaw detection based on the determination result. Alternatively, if factors such as the flaw detection device being equipped with a highly functional following mechanism and most of the region of the surface of the inspection object being flat result in a situation where the head portion hardly separates from the surface of the inspection object, when it is determined that the head portion is separated from the surface of the inspection object at the position of some of the contacts, it can be determined that the surface of the inspection object has unevenness at the position of that contact. In this case, the surface shape inspection of the inspection object can also be performed simultaneously with the flaw detection inspection.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0028] The flaw detection device and flaw detection method according to an embodiment of the present invention will be described below. The flaw detection device according to an embodiment of the present invention is a device for performing flaw detection, that is, inspection regarding the presence, position, degree, etc. of flaws, on an inspection object made of a metal material. Further, the flaw detection method according to an embodiment of the present invention is a method for performing flaw detection of an inspection object using the flaw detection device.

[0029] [Regarding the Flaw Detection Device] The flaw detection device according to an embodiment of the present invention includes a head unit and a conduction detection unit. The head unit includes an attachment member, a plurality of flaw detection sensors, and a plurality of contacts. The contacts of the head unit and the conduction detection unit function as a proximity detection mechanism. Optionally, but preferably, the head unit further includes a mimicking mechanism.

[0030] (Configuration of the Head Unit) As the head unit, the flaw detection device disclosed in Patent Document 2 can be preferably used as it is. That is, by adding a conduction detection unit to the flaw detection device of Patent Document 2, the flaw detection device according to the present embodiment can be constructed. First, the configuration of the head unit will be briefly described below.

[0031] FIGS. 1 and 2 show the configuration of the head portion 2 of the flaw detector 1 according to an embodiment of the present invention. The head portion 2 includes a support member 10, an elastic deformation portion 20, an inspection portion 30, and a reciprocating portion 40. The inspection portion 30 includes a mounting member 31, a flexible probe 32 having a flaw detection sensor 32b, and a contact 35. The elastic deformation portion 20 includes elastic members 21 and 22 as imitation mechanisms. In the head portion 2, the inspection portion 30 is supported by the support member 10 via the elastic deformation portion 20 having the elastic members 21 and 22.

[0032] In this specification, as shown in the drawings, the x-direction, y-direction, and z-direction are set. The z-direction (the vertical direction in FIG. 1) is set along the mounting direction in which the flexible probe 32 and the contact 35 are mounted with respect to the mounting member 31, and the mounting direction is the -z direction (downward in FIG. 1). Then, in the plane orthogonal to the z-direction, the arrangement direction of the flaw detection sensors 32b in the flexible probe 32 is defined as the y-direction, and the direction orthogonal to the y-direction is defined as the x-direction.

[0033] (1) Inspection portion The mounting member 31 is a member that serves as a base material for mounting the flexible probe 32 and the contact 35. The mounting member 31 is made of a plate material of a material that can be reversibly bent and deformed, such as rubber or elastomer. The mounting member 31 has a frame shape with a rectangular opening in the center, and the flexible probe 32 is fitted and fixed in the opening. A plurality of contacts 35 are attached to the frame portion surrounding the opening. As also shown in FIGS. 1 and 2, the inspection portion 30 is attached to the head portion 2 in a state of gently bulging in the -z direction. Here, when explaining the structure of the inspection portion 30, the explanation will be made assuming a state where it is arranged orthogonally to the z-direction without bulging.

[0034] The flexible probe 32 has a plurality of flaw detection sensors 32b attached to a substrate 32a. The substrate 32a is made of a plate material of a bendable material such as rubber or elastomer, similar to the attachment member 31. The flaw detection sensor 32b is an element capable of detecting flaws existing on the surface or inside of an object to be inspected, and various known flaw detection sensors such as an eddy current flaw detection sensor, an ultrasonic flaw detection sensor, and a leakage magnetic flux flaw detection sensor can be used. In this embodiment, the case where the flaw detection sensor 32b is configured as an eddy current flaw detection sensor is mainly dealt with.

[0035] In the flexible probe 32, a plurality of flaw detection sensors 32b are arranged side by side along the y direction on the -z side surface of the substrate 32a. That is, a plurality of flaw detection sensors 32b are arranged along the y direction and are attached to the attachment member 31 via the substrate 32a. Each flaw detection sensor 32b can independently detect flaws in a metal object to be inspected and perform flaw detection. The flexible probe 32 is fixed to the attachment member 31 such that the surface of the substrate 32a to which the flaw detection sensor 32b is attached is substantially flush with the surface of the attachment member 31. Hereinafter, the -z side surface of the inspection unit 30, which is composed of the surface of this substrate 32a and the surface of the flexible probe 32, is referred to as the inspection surface 30a. Also, the +z side surface on the opposite side of the inspection surface 30a is referred to as the bonding surface 30b.

[0036] The contact 35 is a member made of a conductive material. In the illustrated form, it is a rolling member that can roll on the surface of the object to be inspected, particularly a ball roller. The contacts 35 are arranged and attached on both sides (+x side and -x side) across the rows of the flaw detection sensors 32b along the y direction on the inspection surface 30a of the attachment member 31. The contacts 35 are attached in a state of protruding outward more than the flaw detection sensors 32b with respect to the inspection surface 30a. That is, the lower end (-z side end) of the contact 35 is arranged at the same vertical position (position in the z direction) as the lower end of the flaw detection sensor 32b or at a position protruding downward (-z direction) from the lower end of the flaw detection sensor 32b. The contact 35 made of a ball roller has a metal sphere and can independently rotate freely in each direction within the plane of the inspection surface 30a on the spot.

[0037] (2) Support member The support member 10 is a frame member that supports the inspection unit 30 via the elastic deformation part 20. In the support member 10, hinges 14 that can flex in the ±z direction are attached to the -z side ends of the side wall surfaces 11 on both sides in the y direction, and the inspection unit 30 is attached via the hinges 14. The inspection unit 30 is fixed at the y-direction both ends to the tips of the hinges 14 on both sides. Also, a pressing surface 13 is provided and fixed across between the side wall surfaces 11 on the +z side part of the side wall surfaces 11.

[0038] (3) Elastic deformation part The elastic deformation part 20 includes elastic members 21 and 22 that can be elastically deformed along a deformation axis provided in the z direction. One ends (+z direction) of the elastic members 21 and 22 are coupled to the support member 10 along the deformation axis, and the other ends (-z direction) are coupled to the coupling surface 30b of the inspection unit 30. The elastic members 21 and 22 can be elastically deformed in the z direction with different deformation amounts for each position along the y direction. In the illustrated form, as the elastic members, it has a plurality of follower springs 21 and an elastic body block 22. The follower springs 21 have a higher elastic modulus than the elastic body block 22 along the z direction and exhibit a large spring constant.

[0039] The follower spring 21 is configured as a coil spring. The follower spring 21 is held between the elastic body holding surface 23 on which the spring column 24 is erected in a state where the spring column 24 is inserted through the hollow portion, and the pressing surface 13 of the support member 10 having a through hole and through which the spring column 24 is inserted. The elastic body holding surface 23 is movable in the ±z direction along the slit 12 provided on the side wall surface 11 of the support member 10.

[0040] The elastic body block 22 is configured as a block-shaped member made of a polymer elastic body typified by rubber or elastomer. The elastic body block 22 is disposed in the space surrounded by the elastic body holding surface 23 of the elastic deformation portion 20, the coupling surface 30b of the inspection portion 30, and the pair of side wall surfaces 11, 1 of the holding member. In the elastic body block 22, the end surface on the -z side facing the coupling surface 30b of the inspection portion 30 has a bulging shape in which the central portion bulges outward (-z direction) from both end portions along the y direction. Due to the end surface of the elastic body block 22 having a bulging shape, in the inspection portion 30, the mounting portion 31 and the substrate 32a of the flexible probe 32 also have a similar bulging shape. (4) Advancing / retreating portion The advancing / retreating portion 40 is a member that advances and retreats the entire elastic members 21, 22 along the z direction. The advancing / retreating portion 40 includes a advancing / retreating spring 42 having a spring constant larger than those of the follower spring 21 and the elastic body block 22 and being elastically deformable in the z direction, and a driving means 41 capable of compressing the advancing / retreating spring 42 by a forward movement in the +z direction. By the forward movement driven by the driving means 41, the support member 10, and the elastic deformation portion 20 and the inspection portion 30 supported by the support member 10 can be advanced downward (-z direction) as a whole via the advancing / retreating spring 42.

[0041] (Configuration of conduction detection portion) The conduction detection portion 5 can detect the presence or absence of conduction between each of a plurality of contacts 35 provided in the inspection portion 30 of the head portion 2 and an object to be inspected (work W). FIG. 3 schematically shows a configuration example of the conduction detection portion 5.

[0042] The conduction detection unit 5 includes a power supply unit 51 and a measurement unit 52. The power supply unit 51 and the measurement unit 52 are electrically connected to the workpiece W and each contact 35 by an external wiring 53. The power supply unit 51 can apply a voltage between the workpiece W and each contact 35 via the external wiring 53. The measurement unit 52 can detect the presence or absence of conduction between the workpiece W and each contact 35. In the illustrated form, the power supply unit 51 is disposed between the ground potential and the workpiece W, and applies a potential to the workpiece W with reference to the ground potential. The measurement unit 52 detects the presence or absence of conduction between the contact 35 and the ground potential.

[0043] As the power supply unit 51, an appropriate battery or power supply device can be used. The power supply unit 51 preferably applies a DC voltage. A voltage can be applied to the workpiece W by a single power supply unit 51 to detect the presence or absence of conduction between the workpiece W and each of the plurality of contacts 35.

[0044] The type of the measurement unit 52 is not particularly limited as long as it can monitor the presence or absence of conduction between the workpiece W and each contact 35. It may detect the presence or absence of conduction using any of current, voltage, and resistance as an index. In the illustrated form, the measurement unit 52 monitors the presence or absence of conduction at the contact 35 by measuring the voltage generated at the contact 35. The measurement unit 52 needs to be able to independently detect the presence or absence of conduction for each of the plurality of contacts 35. As such a measurement unit 52, for example, a multi-channel multimeter can be preferably used.

[0045] When a certain contact 35 is in contact with the surface W1 of the workpiece W (the state where the portion indicated by the dotted line in FIG. 3 is in contact), conduction exists between the contact 35 and the workpiece W. That is, the circuit including the power supply unit 51, the measurement unit 52, and the external wiring 53 is closed, a current flows from the power supply 51 through the circuit, and the measurement unit 52 detects the energization. On the other hand, when the contact 35 is separated from the surface W1 of the workpiece W (the state where the portion indicated by the dotted line in FIG. 3 is separated), no conduction exists between the contact 35 and the workpiece W. That is, the circuit including the power supply unit 51, the measurement unit 52, and the external wiring 53 is open, and no current flows through the circuit, so the measurement unit 52 does not detect the energization. In this way, the presence or absence of conduction between each contact 35 and the workpiece W, and further the presence or absence of contact between each contact 35 and the surface W1 of the workpiece W can be detected based on the presence or absence of detection of energization by the measurement unit 52.

[0046] The measurement unit 52 preferably notifies an inspector who performs a flaw detection inspection of the presence or absence of conduction between each contact 35 and the workpiece W through a display screen or the like. Alternatively, when at least some of the contacts 35 change from a state of being conductive with the workpiece W to a non-conductive state, this may be notified to the inspector by an alarm sound, an alarm display, or the like.

[0047] [Flaw Detection Method] Next, a flaw detection method according to an embodiment of the present disclosure using the flaw detection device 1 having the above configuration will be described. In the flaw detection method according to this embodiment, while moving the head unit 2 along the surface of the workpiece W made of metal, flaw detection of the workpiece W is performed by the flaw detection sensor 32b.

[0048] Prior to starting the flaw detection, the head unit 2 is arranged on the surface W1 of the workpiece W. At this time, each contact 35 protruding from the detection surface 30a of the head unit 2 is brought into contact with the surface W1 of the workpiece W. When arranging the head unit 2, it is preferable to use the elastic members 21 and 22 to make the detection surface 30a of the head unit 2 conform to the shape of the surface W1 of the workpiece W, that is, to arrange the surface of the inspection unit 30 of the head unit 2 along the surface W1 of the workpiece W.

[0049] Specifically, with the top of the bulging shape of the inspection unit 30 of the head unit 2 in contact with the work surface W1, a pressing force is applied to the inspection unit 30 via the support member 10 and the elastic deformation unit 20, and the inspection surface 30a of the inspection unit 30 is pressed against the work surface W1. The application of the pressing force may be performed by driving the forward movement (-z direction movement) of the support member 10 by the driving means 41 of the advancing / retreating unit 40. At this time, the elastic members 21 and 22 are compressed and exhibit a restoring force in the z direction. Due to this restoring force, the inspection surface 30a of the inspection unit 30 is pressed downward (-z direction) toward the work surface W1. By this pressing, the inspection surface 30a comes into close contact with the work surface W1 via the contactor 35 at each position. At this time, the elastic body block 22 elastically deforms in the z direction with different deformation amounts in each part within the xy plane and generates a restoring force corresponding to those deformation amounts. As a result, with the bending deformation of the mounting member 31 and the substrate 32a of the flexible probe 32, the inspection unit 30 is pressed against the work surface W1 via the contactor 35 at each position on the work surface W1. Whether the work surface W1 is planar, has a concave shape or a convex shape, or has both concavities and convexities depending on the position, the elastic members 21 and 22 elastically deform with different deformation amounts for each position and exhibit a restoring force corresponding to the deformation amount, so that the inspection surface 30a can be pressed along the work surface W1 at each position.

[0050] By conforming the inspection surface 30a of the head portion 2 to the shape of the work surface W1, each of the plurality of contacts 35 can be brought into contact with the work surface W1. When the contact 35 contacts the work surface W1, the distance between the flaw detection sensor 32b and the work surface W1 is thereby defined. That is, the lower end of the flaw detection sensor 32b is disposed at a position separated from the work surface W1 in the +z direction by a distance corresponding to the difference between the protruding amount of the contact 35 in the -z direction from the inspection surface 30a and the protruding amount of the flaw detection sensor 32b. On the inspection surface 30a, the rows of the contacts 35 are arranged on both sides in the x direction with respect to the row of the flaw detection sensors 32b, so that a state where each flaw detection sensor 32b is separated from the work surface W1 by a predetermined distance is stably formed and held. The conditions for the flaw detection measurement of the flaw detection sensor 32b may be determined so that flaw detection can be performed with sufficient accuracy in a state where a predetermined distance determined by the difference in the protruding amounts between the flaw detection sensor 32b and the contact 35 is taken with the work surface W1.

[0051] When starting the flaw detection of the work W, in addition to arranging the head portion 2 on the work surface W1, it is necessary to prepare the conduction detection unit 5 so that the presence or absence of conduction between each contact 35 and the work W can be continuously detected. That is, a circuit as shown in FIG. 3 is prepared, and the power supply unit 51 is set to a state where a voltage is applied. Also, the measurement unit 52 is prepared so that the presence or absence of energization between each contact 35 and the work W can be continuously detected.

[0052] In this way, with the head portion 2 arranged and the conduction detection unit 5 prepared, flaw detection is started. The flaw detection is carried out by inputting and outputting signals according to the type of the flaw detection sensor 32b. At this time, the flaw detection is carried out while scanning the head portion 2 on the work surface W1. That is, while keeping the head portion 2 in contact with the work surface W1, the entire head portion 2 is relatively moved along the x direction by a slider or the like (not shown), and the flaw detection is carried out. Specifically, at a certain position, after performing flaw detection on each part in the y direction simultaneously, the head portion 2 is moved in the x direction, and the process of performing flaw detection again is repeated, so that two-dimensional flaw detection can be performed in the xy plane with respect to the long work surface W1. Since the contact 35 is composed of a rolling member, when the head portion 2 is relatively moved while the detection surface 30a is in contact with the work surface W1, the contact 35 rolls on the work surface W1, and the movement can proceed smoothly. In particular, by using a ball roller as the contact 35, it can roll freely on a plane, and on the work surface W1, the head portion 2 can be smoothly moved two-dimensionally not only in one direction but also for flaw detection.

[0053] When the head portion 2 is moved along the work surface W1, even if there are irregularities on the work surface W1 in the movement path, due to the elastic deformation of the elastic members 21 and 22 of the elastic deformation portion 20, the detection surface 30a of the head portion 2 can maintain a state following the surface shape of the work W. Specifically, in the movement path of the head portion 2, if there is a change in the uneven shape of the work surface W1 along the y direction, the distribution of the vertical resistance force applied to the follower spring 21 and the elastic body block 22 from the work W changes. Therefore, the follower spring 21 and the elastic body block 22 immediately cancel the elastic deformation in the state before movement at each position in the y direction and cause elastic deformation according to the uneven shape of the work surface W1 at the new position after movement. As a result, during the movement, the inspection unit 30 can be bent and deformed following the uneven shape of the work surface W1 at each position, and flaw detection can be performed. As a result, during the movement, each contact 35 is in contact with the work surface W1, and the state where each flaw detection sensor 32b is disposed above the work surface W1 at a predetermined distance is likely to be stably maintained.

[0054] In this way, when the elastic members 21 and 22 function as a following mechanism, even if there are irregularities on the work surface W1, for each of the flaw detection sensors 32b, the maintenance of the state of being arranged at a predetermined distance from the work surface W1 is promoted. However, when the irregularities on the work surface W1 are large or numerous, even with the following mechanism, it may occur that the influence of these irregularities cannot be completely suppressed and the detection surface 30a of the head portion 2 cannot be sufficiently conformed to the irregular shape of the work surface W1. In such a case, at least a part of the plurality of contacts 35 cannot maintain the state of contacting the work surface W1 and will separate from the work surface W1. Specifically, for example, if there is a convex portion on the work surface W1 that protrudes in the +z direction more than the surrounding portions, the contact 35 located above the convex portion will be less likely to be arranged facing the work surface W1, and may separate from the work surface W1. In particular, when the spring constant of the following spring 21 is large (when the spring is strong), the contact 35 is likely to separate from the work surface W1 at the position of the convex portion. Also, when there is a concave portion on the work surface W1 that is recessed in the -z direction more than the surrounding portions, the contact 35 located above the concave portion may separate from the work surface W1. In particular, when the spring constant of the following spring 21 is small (when the spring is weak), the contact 35 is likely to separate from the work surface W1 at the position of the concave portion. When the contact 35 separates from the work surface W1 in this way, among the plurality of flaw detection sensors 32b, the distance between the one located near the contact portion 35 and the work surface W1 becomes larger than a predetermined distance defined by the difference in the protruding amounts of the contact 35 and the flaw detection sensor 32b, and there is a possibility that flaw detection by the flaw detection sensor 32b cannot be performed under appropriate conditions.

[0055] Therefore, in this flaw detection method, while the head portion 2 is moving, the conduction detection unit 5 monitors whether each contact 35 is in contact with the work surface W1. That is, while performing flaw detection while moving the head portion 2 on the work surface W1, the conduction detection unit 5 continuously monitors whether there is conduction between each contact 35 and the work W. Then, when it is detected by the screen display, alarm, etc. of the measurement unit 52 of the conduction detection unit 5 that there is a contact 35 that does not conduct with the work W, the inspector can determine that the head portion 2 is separated from the work surface W1 at the position of that contact 35. This means that the flaw detection sensor 32b located in the vicinity of that contact 35 is arranged at a position farther from the work surface W1 than a predetermined distance corresponding to the difference in the protruding amounts of the flaw detection sensor 32b and the contact 35. When performing flaw detection with the flaw detection sensor 32b in a state where it is separated from the work surface W1 by a distance greater than the predetermined distance, flaw detection under appropriate conditions preset according to the predetermined distance cannot be performed at the flaw detection sensor 32b, and the quality of flaw detection data such as the accuracy and stability of flaw detection may deteriorate.

[0056] In this way, when it is determined that any one of the contacts 35 is separated from the work surface W1 due to lack of electrical continuity, and it is found that the flaw detection sensor 32b in the vicinity thereof is separated from the work surface W1 by a distance greater than a predetermined distance, the inspector can take measures against those events. As a countermeasure, among the results of the flaw detection inspection already performed, at least during the period when the contact 35 was separated from the work surface W1, it is conceivable not to adopt the inspection results obtained by the flaw detection sensor 32b in the vicinity of the contact 35. In addition, after re-performing the installation of the head portion 2, adjusting the bending shape of the flexible probe 32, changing the amount of compression for compressing the elastic members 21 and 22 by the driving means 41, or replacing the elastic members 21 and 22 (replacement with those having different spring constants, etc.), adjusting each parameter related to flaw detection by the flaw detection sensor 32b, etc., reviewing and changing various conditions related to the flaw detection test, it is conceivable to continue the flaw detection or to perform the flaw detection again. By taking these measures, it is possible to correctly perform the flaw detection of the work W by avoiding the adoption of flaw detection results that may be inferior in terms of data quality, which are obtained in a state where some of the flaw detection sensors 32b are arranged at a distance greater than a predetermined distance from the work surface W1.

[0057] As described above, in the present embodiment, the head portion 2 of the flaw detection device 1 includes a plurality of contacts 35 in addition to the plurality of flaw detection sensors 32b. By monitoring the conduction between each contact 35 and the work W, the proximity of each flaw detection sensor 32b to the work W, that is, whether the flaw detection sensor 32b is disposed close to the work surface W1 at a predetermined distance, can be detected while performing flaw detection on the work W. The contact 35 only needs to be a conductive member, and it is not necessary to attach a mechanical device such as the proximity sensors of Patent Documents 3 and 4 to the head portion 2 for evaluating the proximity of the flaw detection sensor 32b. By using the simple member of the contact 35, the structure of the head portion 2 and the control system of the flaw detection device 1 can be made simple, and the cost required for manufacturing the flaw detection device 1 can also be reduced. Further, even when the flaw detection device 1 is used in an environment exposed to severe conditions such as vibration, like the manufacturing site of the steel industry, the evaluation of the proximity of the flaw detection sensor 32b using the contact 35 can be continuously and stably performed with high precision over a long period of time. The contact 35 is not particularly specified in terms of its structure as long as it is made of a conductive material, particularly a metal. However, as in the form described above, when the contact 35 is configured as a rolling member including a ball roller, the contact 35 serves as a proximity detection mechanism for detecting the proximity of each flaw detection sensor 32b and also serves as a movement assisting mechanism for enhancing the smoothness of movement of the head portion 2 on the work surface W1.

[0058] In the head portion 2 of the flaw detection device 1, the elastic members 21 and 22 do not necessarily have to be provided. However, by providing the elastic members 21 and 22, a following mechanism can be utilized in the head portion. That is, even if the work surface W1 has irregularities, when the detection surface 30a contacts the work surface W1 with each contactor 35, and each flaw detection sensor 32b is arranged close to the work surface W1 up to a predetermined distance, the formation of such a state is promoted by the elastic members 21 and 22. In this way, by providing the flaw detection device 1 with a following mechanism including the elastic members 21 and 22 in addition to the proximity detection mechanism including the plurality of contactors 35 and the conduction detection unit 5, not only can it be detected when each flaw detection sensor 32b fails to maintain a predetermined proximity to the work W (non-proximity state), but also the occurrence of the non-proximity state itself can be made less likely to occur. Thereby, the situation of performing the flaw detection test in the non-proximity state can be doubly prevented from both the detection of the non-proximity state and the suppression of its occurrence. When the elastic members 21 and 22 are provided in the flaw detection device 1, if the attachment portion including the flexible probe 32 is configured to be bendable and deformable, the following mechanism by the elastic members 21 and 22 can be particularly effectively exerted. The elastic member is not limited to a specific type as long as it can be elastically deformed in the z direction. However, as described above, by using in combination the follower spring 21 having a relatively large spring constant and the elastic body block 22 having a relatively small spring constant, it is possible to achieve both the stabilization of the contact state of the inspection unit 30 by utilizing the large restoring force of the follower spring 21 and the faithful following of the inspection unit 30 to the surface shape of the work W by utilizing the flexibility and continuity of the elastic body block 22.

[0059] As described above, the flaw detection sensor 32b provided in the head portion 2 may be of any type, such as an eddy current flaw detection type, an ultrasonic flaw detection type, a magnetic flux leakage flaw detection type, etc. However, particularly when the eddy current flaw detection type flaw detection sensor 32b is used, by providing the head portion 2 with the proximity detection mechanism and the following mechanism, the effect of performing flaw detection while ensuring the proximity of the flaw detection sensor 32b to the work W can be highly enjoyed. This is because it is particularly important to maintain a constant distance between the work surface W1 and the flaw detection sensor 32b in order to perform eddy current flaw detection stably and with high precision.

[0060] In the embodiment of the flaw detection method described above, during the flaw detection inspection, when the conduction interruption between at least a part of the contacts 35 and the work W is detected by the conduction detection unit 5, it is determined that the head portion 2 has unintentionally separated from the work surface W1 at the location of the contact 35, and measures such as interruption of the flaw detection inspection, review and change of various conditions related to flaw detection are taken. However, when the following conditions are met: for example, the elastic members 21 and 22 have a large spring constant, so the following mechanism by the elastic members 21 and 22 is strong, and the detection surface 30a of the head portion 2 can follow even a work surface W1 with large unevenness, or when most of the region of the work surface W1 has high smoothness, and it is ensured that the frequency of detachment of the contact 35 from the work surface W1 is low, as a flaw detection method for the deformed state, the detection of the presence or absence of conduction between the contact 35 and the work W by the conduction detection unit 5 can also be actively used for the inspection of the unevenness of the work surface W1. In this case, while moving the head portion 2 on the work surface W1, a flaw detection inspection is performed by the flaw detection sensor 32b, and when it is detected by the conduction detection unit 5 that a contact 35 having no conduction with the work W has occurred, it may be regarded that the surface W1 of the work W has unevenness different from the surrounding region at the position directly below (-z direction) the contact 35. In this way, in the flaw detection method for the deformed state, the flaw detection inspection and the surface shape inspection can be simultaneously performed on the work W.

Example

[0061] Examples of the present invention are shown below. Note that the present invention is not limited by these examples. Here, during flaw detection using the above flaw detection device, it was confirmed whether it was possible to detect that a part of the region of the head portion had separated from the surface of the work.

[0062] (Test method) A flaw detector equipped with a head portion having the structure shown in FIGS. 1 and 2 and a conduction detection portion having the configuration shown in FIG. 3 was prepared. Also, as a sample, a metal material having the structure shown in FIG. 4 was prepared. The sample W has a protruding portion W2 at the central portion, and the surface W1 of the rectangular flat plate-shaped metal material bulges in a dome shape at the protruding portion W2. The protruding portion W2 has a bottom surface with a diameter of 100 mm, and the height of the bulge at the center portion is 3 mm. Also, the dimensions of the entire sample W were 500 mm along the longitudinal direction (x direction) and 100 mm along the width direction (y direction). That is, the dome shape of the protruding portion W2 is formed over the entire width direction of the sample W.

[0063] The head portion 2 of the flaw detector was placed on the surface of the sample W having the protruding portion. FIG. 4 schematically shows the relationship between the sample W and the head portion 2. As a constituent member of the head portion 2, only the contact 35 is shown. Here, the y direction of the head portion 2 (the direction in which a plurality of contacts 35 are arranged) was made parallel to the side in the width direction of the sample W, and the head portion 2 was placed on the surface W1 of the sample W. Then, by means of a following mechanism, the entire detection surface of the head portion 2 was brought into close contact with the surface of the sample. In this state, as indicated by the arrow in FIG. 4, the head portion 2 was moved along the x direction corresponding to the longitudinal direction of the sample W on the sample surface W1. During the movement, by monitoring the current flowing between each contact 35 and the sample W with the conduction detection portion, the presence or absence of conduction between each contact 35 and the sample W1 was continuously detected. As the contacts 35, eight were arranged in each row at an interval (center-to-center distance) of 12 mm, and two rows were provided. The detection of the presence or absence of conduction was performed on the contacts 35 in the row on the front side (+x side) in the moving direction among the two rows.

[0064] The test was conducted in two ways: when the mimicking mechanism did not work sufficiently and when it worked sufficiently, by adjusting the force applied to the elastic member in the -z direction by the driving means. As a case where the mimicking mechanism did not work sufficiently, by increasing the force that compresses the elastic member by the driving means (keeping the head portion pressed too strongly against the sample surface), the mechanism that deforms and follows the detection surface of the head portion due to the deformation of the elastic member with respect to the unevenness of the sample surface was made not to work sufficiently. On the other hand, as a case where the mimicking mechanism worked sufficiently, by relatively reducing the force that compresses the elastic member by the driving means (keeping the pressure for pressing the head portion against the sample surface within an appropriate range), the mechanism that deforms and follows the detection surface of the head portion due to the deformation of the elastic member with respect to the unevenness of the sample surface was made to work sufficiently.

[0065] (Test results) Figures 5 and 6 show the results of conduction detection obtained by the conduction detection unit for each contact. Figure 5 shows the case where the mimicking mechanism does not work sufficiently, and Figure 6 shows the case where the mimicking mechanism works sufficiently. In each case, (a) shows a two-dimensional display, and (b) shows a one-dimensional display, in which the voltage signals measured for each contact are displayed. The value of the voltage is proportional to the amount of current conduction between each contact and the workpiece. In the two-dimensional display of (a), the voltage value is displayed in gray scale, indicating that the lighter the color, the larger the measured value. In the one-dimensional display of (b), the obtained voltage values are displayed in the form of waveforms. In both the (a) two-dimensional display and the (b) one-dimensional display, the measurement results for each contact are arranged in order vertically, and the vertical direction corresponds to the y direction of the head portion and the width direction of the sample. The horizontal direction indicates the elapsed time while the head portion is being scanned, and corresponds to the x direction of the head portion and the longitudinal direction of the sample.

[0066] First, looking at the results in the case where the mimicking mechanism in Figure 5 does not work sufficiently, there are regions where the voltage does not show a value around the right side of the center in the horizontal direction. It can be seen that the conduction between the contact and the sample has disappeared in these regions. The regions where the conduction has disappeared correspond to the positions where protrusions are formed in the xy plane on the sample. That is, it can be seen that the contact is separated from the sample surface at the positions of the protrusions.

[0067] On the other hand, looking at the results when the imitation mechanism in Fig. 6 works sufficiently, throughout the area in the figure, that is, in the measurement results obtained at all the scanning positions on the sample for all the contactors, the voltage shows a stable value. That is, throughout the measured area, the state of having conduction between the contactor and the sample is stably maintained. This indicates that the contactor maintains the state of being in contact with the surface throughout the entire surface of the sample. By the sufficient operation of the imitation mechanism, even if there are protrusions on the sample surface, it is considered that the detection surface of the head part is deformed following the surface shape of the protrusions, and the state where the contactor is in close contact with the sample surface is maintained. As described above, from the comparison of the results in Figs. 5 and 6, it is confirmed that when some contactors separate from the sample surface due to insufficient imitation, it can be sensitively detected as the disappearance of conduction between the contactor and the sample.

[0068] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0069] 1 Flaw detector 2 Head part 5 Conduction detection part 10 Support member 20 Elastic deformation part 21 Follow-up spring (elastic member) 22 Elastic body block (elastic member) 30 Inspection part 30a Detection surface 31 Mounting member 32 Flexible probe 32a Substrate 32b Flaw detection sensor 35 Contactor 40 Advancing and retreating part 41 Driving means 51 Power supply part 52 Measuring part 53 External wiring W Workpiece (object to be inspected, sample) W1 work surface W2 protrusion

Claims

1. a head part, a conduction detection part, and has, the head part is, a mounting member, a flaw detection sensor capable of detecting a flaw in an inspection object made of metal, a contact made of a conductive material, and includes, the flaw detection sensors are arranged in a plurality along the arrangement direction and are attached to the mounting member, the contacts are arranged in a plurality along the arrangement direction side by side with the rows of the flaw detection sensors, and protrude outward more than the flaw detection sensors with respect to the surface of the mounting member, and are attached to the mounting member, the conduction detection part is a flaw detection device capable of detecting the presence or absence of conduction between each of the contacts and the inspection object.

2. The contact is composed of a rolling member that can roll on the surface of the inspection object, and a plurality are arranged along the arrangement direction on both sides sandwiching the row of the flaw detection sensors, respectively. The flaw detection device according to claim 1.

3. The rolling member is a ball roller. The flaw detection device according to claim 2.

4. The conduction detection part is, a power supply part that applies a voltage between the inspection object and the contact, a measurement part that detects the presence or absence of conduction between each of the inspection object and the contact, and includes. The flaw detection device according to claim 1.

5. The flaw detection sensor is an eddy current flaw detection sensor. The flaw detection device according to claim 1.

6. The flaw detection sensors are attached to the mounting member in the form of flexible probes arranged in a plurality along the arrangement direction on the surface of a substrate that can be bent and deformed. The flaw detection device according to claim 1.

7. A support member and an elastic member are coupled to the flexible probe, one end of the elastic member is coupled to the support member along the deformation axis, the other end is coupled to the side opposite to the surface of the flexible probe where the flaw detection sensor is provided, and is elastically deformable along the deformation axis with different deformation amounts for each position along the arrangement direction. The flaw detection device according to claim 6.

8. When performing flaw detection on an inspection object made of metal while moving the head part along the surface of the inspection object using the flaw detection device according to any one of claims 1 to 7, A flaw detection method, comprising: starting flaw detection with each of the contacts in contact with the surface of the object to be inspected; while performing flaw detection while moving the head portion, when the conduction detection unit detects that there is a contact that has no conduction with the object to be inspected, determining that the head portion is separated from the surface of the object to be inspected at the position of the contact.

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