JP7631087B2 - Flaw detection device and flaw detection method - Google Patents

Description

The present invention relates to a flaw detection device and a flaw detection method for performing flaw detection testing.

Known methods for performing flaw detection on an object to be inspected include a method that uses ultrasonic echoes (ultrasonic flaw detection) and a method that uses eddy currents (eddy current flaw detection).

Patent Document 1 discloses a flaw detection device that uses ultrasonic flaw detection. In Patent Document 1, ultrasonic echo data is acquired while an ultrasonic sensor is moved using a movable arm, and the ultrasonic sensor position data and ultrasonic echo data are stored in association with each other. Then, based on the stored data, the positions of scratches and defects in the object to be inspected are detected.

In eddy current testing, the end face of the flaw detection probe containing a coil is brought into surface contact with the surface of the object being tested, so that the coil is kept close to the surface of the object being tested. In this state, when a current is passed through the coil, eddy currents flow on the surface of the object being tested.

While maintaining surface contact between the end face of the flaw detection probe and the object being inspected, the flaw detection probe is moved along the surface of the object being inspected. During this movement, changes in the eddy currents are monitored, and if a change occurs in the eddy currents, it can be determined that a flaw exists at the location where this change occurred.

Patent No. 5495562

In ultrasonic testing, if surface shape information such as the waviness of the surface of the test object is obtained before the test (a so-called teaching process), the position and orientation of the test probe can be set to match the surface shape of the test object. However, it takes a lot of effort to obtain surface shape information over the entire scanning path of the test probe.

In eddy current testing, eddy currents are affected by the state of contact between the inspection probe and the surface of the object being tested, so it is necessary to maintain a state in which the entire end face of the inspection probe is in surface contact. If part or the entire end face of the inspection probe is separated from the surface of the object being tested (a state in which lift-off is increased), the eddy currents become smaller. When the eddy currents are small, the change in the eddy currents also becomes small, and the inspection accuracy deteriorates. To prevent the inspection object from being scanned in such a state, even in conventional eddy current testing, a teaching operation that requires a great deal of effort is performed to obtain surface shape information over the entire scanning path of the inspection probe.

The present invention aims to provide a flaw detection device and flaw detection method that reduces the effort required for teaching and enables the surface of an object to be scanned while aligning the end face of a flaw detection probe with the surface of the object.

A flaw detection device according to one aspect of the present invention is configured to perform flaw detection inspection while scanning a surface of an object to be inspected. The flaw detection device includes a flaw detection probe having an end face facing the surface of the object to be inspected, a manipulator configured to hold the flaw detection probe with the end face of the flaw detection probe facing the surface of the object to be inspected and to move the flaw detection probe in a predetermined scanning direction along the surface of the object to be inspected and in a direction perpendicular to the surface of the object to be inspected, a detection unit that detects a reaction force and a torque that the flaw detection probe receives from the object to be inspected, a control unit that controls the manipulator so that the flaw detection probe moves in the scanning direction, and a storage unit configured to store history data of the position of the flaw detection probe while the surface of the object to be inspected is being scanned . The control unit is configured to control the manipulator to adjust the position of the flaw detection probe in a direction perpendicular to the surface of the object to be inspected so that the reaction force detected by the detection unit is within a predetermined threshold range while controlling the manipulator to move the flaw detection probe in the scanning direction, and to control the manipulator to tilt the flaw detection probe to adjust the attitude of the flaw detection probe so that the torque detected by the detection unit is within a predetermined torque threshold range, and to determine that an abnormality has occurred in the scanning of the object to be inspected if the reaction force detected by the detection unit falls outside the threshold range or the torque exceeds the torque threshold, and to execute a predetermined abnormality control to prevent the scanning of the object to be inspected from being continued while the abnormality occurs . In the abnormality control, after stopping the manipulator, the control unit controls the manipulator based on the historical data so as to return the flaw detection probe to the position of the flaw detection probe before the manipulator was stopped, and controls the manipulator to move the flaw detection probe that has been returned to the position before the manipulator was stopped, at a speed slower than the moving speed of the flaw detection probe before the manipulator was stopped, toward the position of the flaw detection probe when the manipulator was stopped, to scan the inspection object.

According to the above-mentioned configuration, the flaw detection probe is held by the manipulator so that it faces the surface of the object to be inspected. When the control unit controls the manipulator in this holding state, the flaw detection probe moves along the surface of the object to be inspected.

During this time, the detection unit detects the reaction force from the object being inspected acting on the flaw detection probe. This reaction force increases or decreases if there is waviness or a change in roughness on the surface of the object being inspected. If the reaction force decreases, it is assumed that the end face of the flaw detection probe is moving away from the surface of the object being inspected due to the waviness of the surface of the object being inspected. In such a case, the control unit adjusts the position of the flaw detection probe in a direction perpendicular to the surface of the object being inspected so that the reaction force is within the threshold range, thereby preventing the flaw detection probe from moving away from the surface of the object being inspected.

Conversely, if the reaction force increases, it is assumed that the end face of the flaw detection probe is approaching the surface of the object being inspected due to undulations on the surface of the object being inspected. In such a case, the control unit adjusts the position of the flaw detection probe in a direction perpendicular to the surface of the object being inspected so that the reaction force is within the threshold range, and therefore the load on the flaw detection probe does not become excessively large.

If the surface of the object to be inspected and the end face of the flaw detection probe are parallel to each other, the reaction force can act approximately uniformly over the entire end face of the flaw detection probe. However, if the surface of the object to be inspected is wavy, the surface of the object to be inspected and the end face of the flaw detection probe are not parallel to each other, and a portion of the end face may receive a stronger reaction force than other portions. For example, if the front portion of the end face receives a stronger reaction force, the detection unit may detect a torque that tilts the flaw detection probe backward. Therefore, by detecting the reaction force and the torque, the detection unit can determine whether the surface of the object to be inspected and the end face of the flaw detection probe are parallel to each other. In the case where the reaction force is adjusted, if the value of the torque obtained when the surface of the object to be inspected and the end face of the flaw detection probe are in a non-parallel state is set as the torque threshold value, the attitude of the flaw detection probe can be adjusted by the control of the control unit so that the surface of the object to be inspected and the end face of the flaw detection probe are in a substantially parallel state. That is, the control unit adjusts the attitude of the flaw detection probe by tilting the flaw detection probe so that the torque detected by the detection unit falls within a range of a predetermined torque threshold value, so that the surface of the inspection object and the end face of the flaw detection probe can come into contact with each other in a substantially parallel state. That is, the end face of the flaw detection probe can come into surface contact with the surface of the inspection object. Therefore, a teaching operation for making the control unit memorize the tilting attitude of the flaw detection probe in advance is not required. If the reaction force falls outside the threshold range, there is a possibility that the surface contact state between the flaw detection probe and the inspection object is lost, or the flaw detection probe is pressed against the inspection object with an excessively strong force. In addition, if the torque detected by the detection unit is large enough to exceed the torque threshold value, it is assumed that the flaw detection probe is tilted significantly and a part of the end face of the flaw detection probe is separated from the surface of the inspection object. In order to prevent the scanning of the inspection object from continuing in such a state, the control unit executes an abnormality control. In the abnormality control, the control unit stops the manipulator. After that, the control unit can control the manipulator so that the flaw detection probe returns to the position before the manipulator was stopped. After returning the position of the flaw detection probe, the control unit controls the manipulator to move the flaw detection probe toward the position of the flaw detection probe when the manipulator is stopped to scan the inspection object. The moving speed of the flaw detection probe at this time is lower than the moving speed of the flaw detection probe before the manipulator is stopped, so that the control unit can easily follow the undulations of the surface of the inspection object. That is, the control unit controls the manipulator so that the position of the flaw detection probe in the direction perpendicular to the surface of the inspection object changes in accordance with the undulations, thereby making it easier to keep the reaction force within the threshold range and the friction force below the friction threshold. In addition, when the flaw detection probe moves at a low moving speed, even if the flaw detection probe comes into contact with a cause (for example, a minute protrusion on the surface of the inspection object) that has generated a torque larger than the torque threshold, the force that the flaw detection probe receives from this cause becomes smaller. That is, the torque detected by the detection unit is less likely to exceed the torque threshold. Therefore, it is possible to maintain a surface contact state between the flaw detection probe and the surface of the inspection object even at the position where the manipulator is stopped. As a result, the manipulator can be stopped and then resumed and continued scanning of the inspection object.
A flaw detection device according to another aspect of the present invention is configured to perform flaw detection inspection while scanning a surface of an object to be inspected. The flaw detection device includes a flaw detection probe having an end face facing the surface of the object to be inspected, a manipulator configured to hold the flaw detection probe with the end face of the flaw detection probe facing the surface of the object to be inspected and to move the flaw detection probe in a predetermined scanning direction along the surface of the object to be inspected and in a direction perpendicular to the surface of the object to be inspected, a detection unit configured to detect a reaction force and torque that the flaw detection probe receives from the object to be inspected and a frictional force acting on the end face of the flaw detection probe, a control unit configured to control the manipulator so that the flaw detection probe moves in the scanning direction, and a storage unit configured to store history data of the position of the flaw detection probe while the surface of the object to be inspected is being scanned. The control unit is configured to control the manipulator to adjust the position of the flaw detection probe in a direction perpendicular to the surface of the object to be inspected so that the reaction force detected by the detection unit is within a predetermined threshold range while controlling the manipulator to move the flaw detection probe in the scanning direction, and to control the manipulator to tilt the flaw detection probe to adjust the attitude of the flaw detection probe so that the torque detected by the detection unit is within a predetermined torque threshold range, and to determine that an abnormality has occurred in the scanning of the object to be inspected when the friction force detected by the detection unit exceeds a predetermined friction threshold, and to execute a predetermined abnormality control to prevent the scanning of the object to be inspected from continuing while the abnormality occurs. In the abnormality control, after stopping the manipulator, the control unit controls the manipulator based on the historical data so as to return the flaw detection probe to the position of the flaw detection probe before the manipulator was stopped, and controls the manipulator to move the flaw detection probe that has been returned to the position before the manipulator was stopped, at a speed slower than the moving speed of the flaw detection probe before the manipulator was stopped, toward the position of the flaw detection probe when the manipulator was stopped, to scan the inspection object.

Regarding the above-mentioned configuration, the flaw detection probe may be configured to emit ultrasonic waves from the end face and receive ultrasonic echoes at the end face via a contact medium applied to the surface of the object to be inspected.

Regarding the above-mentioned configuration, the flaw detection probe may be configured to generate eddy currents on the surface of the object to be inspected by passing a current through a built-in coil.

According to the above-mentioned configuration, the flaw detection probe can scan the inspection object while tilting according to the surface shape of the inspection object, even if a teaching operation is not performed to make the control unit memorize the tilting posture of the flaw detection probe in advance. In other words, the flaw detection probe can move along the surface of the inspection object while maintaining the entire end face of the flaw detection probe in surface contact. As a result, when ultrasonic flaw detection is performed, no air layer is formed between the flaw detection probe and the inspection object, and ultrasonic waves can be emitted and ultrasonic echoes can be received through the contact medium without being hindered by the air layer. In addition, when eddy current flaw detection is performed, eddy currents are less affected by the contact and separation of the flaw detection probe with respect to the surface of the inspection object, and flaw detection of the inspection object can be performed with high accuracy.

A flaw detection inspection method according to another aspect of the present invention can be used to scan an object to be inspected while moving an end face of a flaw detection probe along the surface of the object to be inspected. The flaw detection inspection method includes detecting a reaction force and a torque that the flaw detection probe receives from the object to be inspected while moving the flaw detection probe in a predetermined scanning direction along the surface of the object to be inspected with the end face of the flaw detection probe facing the surface of the object to be inspected, adjusting a position of the flaw detection probe in a direction perpendicular to the surface of the object to be inspected while moving the flaw detection probe in the scanning direction so that the detected reaction force is within a predetermined threshold range, and tilting the flaw detection probe to adjust the attitude of the flaw detection probe so that the detected reaction force is within a predetermined torque threshold range, and scanning the surface of the object to be inspected is performed. storing history data of the position of the flaw detection probe while the flaw detection probe is being scanned in a storage unit, determining that an abnormality has occurred in the scanning of the inspection object when the detected reaction force falls outside the threshold range or when the torque exceeds the torque threshold value, and executing a predetermined abnormality control to prevent the scanning of the inspection object from being continued while the abnormality has occurred, and in the abnormality control, after stopping the flaw detection probe, returning the flaw detection probe to a position of the flaw detection probe before the flaw detection probe was stopped based on the history data, and moving the flaw detection probe returned to the position before the flaw detection probe was stopped toward the position where the flaw detection probe was stopped . The moving speed of the flaw detection probe when moving toward the position where the flaw detection probe is stopped is smaller than the moving speed of the flaw detection probe before the flaw detection probe was stopped.
A flaw detection inspection method according to yet another aspect of the present invention can be used to scan an object to be inspected while moving an end face of a flaw detection probe along the surface of the object to perform flaw detection. The flaw detection inspection method includes detecting a reaction force and torque that the flaw detection probe receives from the object to be inspected and a frictional force acting on the end face of the flaw detection probe while moving the flaw detection probe in a predetermined scanning direction along the surface of the object to be inspected with the end face of the flaw detection probe facing the surface of the object to be inspected, adjusting a position of the flaw detection probe in a direction perpendicular to the surface of the object to which the flaw detection probe is subjected so that the detected reaction force has a magnitude within a predetermined threshold range, and tilting the flaw detection probe to adjust the attitude of the flaw detection probe so that the detected torque is within a predetermined torque threshold range while the flaw detection probe is being moved in the scanning direction. storing history data of the position of the flaw detection probe while the surface of the object is being scanned in a storage unit, determining that an abnormality has occurred in the scanning of the object when the frictional force exceeds a predetermined friction threshold, and executing a predetermined abnormality control for preventing the scanning of the object from being continued while the abnormality has occurred, and in the abnormality control, after stopping the flaw detection probe, returning the flaw detection probe to a position of the flaw detection probe before it was stopped based on the history data, and moving the flaw detection probe returned to the position before it was stopped toward the position where the flaw detection probe was stopped. The moving speed of the flaw detection probe when moving toward the position where the flaw detection probe is stopped is smaller than the moving speed of the flaw detection probe before it was stopped.

The above-mentioned flaw detection device reduces teaching work and makes it possible to scan the surface of the object to be inspected while aligning the end face of the flaw detection probe along the surface of the object to be inspected.

1 is a schematic diagram of a flaw detection device for performing ultrasonic flaw detection. 4 is a schematic flowchart of a control method for the flaw detection device. FIG. 1 is a schematic diagram of a flaw detection probe scanning a flat surface. FIG. 1 is a schematic diagram of a flaw detection probe approaching a sloped surface such that the distance to the end face of the flaw detection probe decreases as the flaw detection probe moves in the scanning direction. FIG. 1 is a schematic diagram of a flaw detection probe approaching a sloped surface such that the distance between the flaw detection probe end face and the surface increases as the flaw detection probe moves in the scanning direction. 1 is a schematic diagram of a flaw detection probe scanning a surface on which an obstacle is present; 4 is a schematic flowchart of a control method for the flaw detection device. 1 is a schematic diagram of a flaw detection probe of a flaw detection device that performs eddy current flaw detection. FIG. 4 is a schematic diagram showing a change in eddy current. FIG. 1 is a schematic diagram of a manipulator for scanning an inspection object on the YZ plane. 4 is a schematic diagram showing the relationship between the scanning direction on a curved surface and the position adjustment direction of the flaw detection probe. FIG.

First Embodiment
Fig. 1 is a schematic diagram of a flaw detection device 100 according to a first embodiment. The flaw detection device 100 will be described with reference to Fig. 1 .

The flaw detection device 100 is configured to perform ultrasonic flaw detection by the direct contact method. In ultrasonic flaw detection by the direct contact method, a layer of contact medium 220 is formed on the surface of the inspection object 210 with a substantially uniform thickness in order to efficiently propagate ultrasonic waves and ultrasonic echoes used in the flaw detection inspection. As the contact medium 220, a material having a higher acoustic impedance than air (for example, glycerin, motor oil, or machine oil) is used. The flaw detection device 100 is configured to perform flaw detection inspection by receiving ultrasonic echoes obtained by emitting ultrasonic waves through the contact medium 220 while scanning the surface of the inspection object 210.

The flaw detection device 100 includes a manipulator 111 (a six-axis articulated arm robot), a control unit 112, a flaw detection probe 120, a detection unit 130, and a memory unit 140. The flaw detection device 100 is configured so that the control unit 112 controls the manipulator 111 and moves the flaw detection probe 120 held by the manipulator 111 along a predetermined scanning path. The detection unit 130 and the memory unit 140 are used for control by the control unit 112.

The manipulator 111 has a first axis 151 to a sixth axis 156, and each arm is configured to be rotatable around the first axis 151 to the sixth axis 156.

The manipulator 111 is attached to a base 113 having a base mounting surface 115. The tip of the manipulator 111 is configured as a mechanical interface 116 for mounting the flaw detection probe 120 and the detection unit 130. The coordinate origin of the base coordinate system (a right-handed Cartesian coordinate system consisting of the X-axis, the Y-axis, and the Z-axis) is set on the base mounting surface 115 of the base 113. The X-axis and the Y-axis are horizontally extending axes. In this embodiment, the inspection target 210 is placed so that its scanning surface is along the X-Y plane, and scanning is performed within the X-Y plane. The Z-axis is a vertical axis that extends at right angles to the X-axis and the Y-axis. The base coordinate system is a fixed coordinate system, and the orientations of the X-axis, the Y-axis, and the Z-axis are constant regardless of the movement of the manipulator 111.

The manipulator 111 holds the flaw detection probe 120 and the detection unit 130 with the mechanical interface 116, and is configured to be able to move the flaw detection probe 120 and the detection unit 130 in the X-axis, Y-axis, and Z-axis directions of the base coordinate system. The coordinate origin of the tool coordinate system (a right-handed Cartesian coordinate system consisting of the x-axis, y-axis, and z-axis) is set in the mechanical interface 116 of the manipulator 111. The x-axis and y-axis of the tool coordinate system are set in directions along the surface of the mechanical interface 116. The z-axis is set in a direction perpendicular to the surface of the mechanical interface 116. The coordinate origin of the tool coordinate system can move in the X-axis, Y-axis, and Z-axis directions of the base coordinate system together with the mechanical interface 116.

The orientation of the mechanical interface 116, and therefore the flaw detection probe 120 and detection unit 130 attached to the mechanical interface 116, changes due to the rotational movement of the manipulator 111 around the first axis 151 to the sixth axis 156. When the orientation of the mechanical interface 116 changes, the orientations of the x-axis, y-axis, and z-axis of the tool coordinate system change in accordance with the change in the orientation of the mechanical interface 116.

The flaw detection probe 120 is configured to emit ultrasonic waves from an end face 121 and to receive ultrasonic echoes from the object to be inspected 210 at the end face 121. The flaw detection probe 120 is attached to the mechanical interface 116 of the manipulator 111 so that the end face 121 faces the object to be inspected 210 in the z-axis direction of the tool coordinate system.

The flaw detection probe 120 may be electrically connected to a data collection device (not shown) and configured to start emitting ultrasonic waves under the control of the data collection device. The flaw detection probe 120 may also be configured to output a flaw detection signal (intensity signal of the ultrasonic echo) to the data collection device based on the received ultrasonic echo.

The detection unit 130 is attached to the mechanical interface 116 of the manipulator 111 so as to detect the force that the flaw detection probe 120 receives from the inspection target 210. In detail, the detection unit 130 is configured to detect the forces shown below. The direction of the force detected by the detection unit 130 is in accordance with the tool coordinate system. The detection unit 130 may be configured using, for example, a six-axis force sensor.
A reaction force Fz that the flaw detection probe 120 receives from the inspection object 210 (in FIG. 1, a force acting in the negative direction on the z-axis of the tool coordinate system).
Friction forces Fx and Fy acting on the end face 121 of the flaw detection probe 120.
Torque Tx acting on the flaw detection probe 120 around the x-axis of the tool coordinate system.
Torque Ty acting on the flaw detection probe 120 around the y-axis of the tool coordinate system.

The detection unit 130 is configured to output signals representing the detected reaction force Fz, friction forces Fx, Fy, and torques Tx, Ty to the control unit 112. The detection unit 130 is configured to output a value of approximately zero as the reaction force Fz when the end face 121 of the flaw detection probe 120 is separated from the surface of the inspection object 210. The larger the value of the reaction force Fz, the stronger the force with which the end face 121 of the flaw detection probe 120 is pressed against the surface of the inspection object 210.

The control unit 112 is electrically connected to the manipulator 111 and configured to control the manipulator 111. Specifically, a scanning path for the inspection object 210 is set in advance for the control unit 112 using a base coordinate system. The control unit 112 controls the manipulator 111 so that the flaw detection probe 120 moves along this scanning path in the X-axis direction and/or Y-axis direction of the base coordinate system. The control unit 112 is also configured to give instructions to the manipulator 111 regarding the moving speed of the flaw detection probe 120.

In addition, the control unit 112 is electrically connected to the detection unit 130, and controls the manipulator 111 so as to change the position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system in response to a signal from the detection unit 130, or stops the manipulator 111. The control of the manipulator 111 by the control unit 112 based on a signal from the detection unit 130 will be described in detail later.

The control unit 112 is also electrically connected to the memory unit 140, and outputs data on the position of the flaw detection probe 120 on the X-axis, Y-axis, and Z-axis of the base coordinate system while the flaw detection probe 120 is moving, and data on the rotational position of the manipulator 111 around the Z-axis. These data are stored as history data in the memory unit 140, and are used for control after the manipulator 111 stops. Control after the manipulator 111 stops will be described in detail separately.

The operation of the flaw detection device 100 is described below. Note that the case where scanning is performed in the X-axis direction and the Y-axis direction within the X-Y plane of the base coordinate system is described here.

First, preparations are made for flaw detection inspection of the object to be inspected 210 (step S105: preparation for flaw detection). In preparation for flaw detection, the flaw detection probe 120 is attached to the manipulator 111. At this point, the end face 121 of the flaw detection probe 120 is in a position spaced apart from the surface of the object to be inspected 210 (a position spaced apart in the positive direction of the Z axis of the base coordinate system in FIG. 1). In this state, the control unit 112 controls the manipulator 111 so that the position of the flaw detection probe 120 coincides with the scanning start position in the X-axis and Y-axis directions of the base coordinate system.

Then, the control unit 112 controls the manipulator 111 so that the flaw detection probe 120 approaches the test object 210 (in FIG. 1, in the negative direction of the Z axis of the base coordinate system). At this time, the control unit 112 determines whether or not the end face 121 of the flaw detection probe 120 has come into contact with the test object 210 based on the reaction force Fz detected by the detection unit 130. That is, if the end face 121 of the flaw detection probe 120 is away from the test object 210, the reaction force Fz detected by the detection unit 130 becomes approximately zero. On the other hand, if the end face 121 of the flaw detection probe 120 comes into contact with the test object 210, the reaction force Fz detected by the detection unit 130 becomes a relatively large value. Therefore, the control unit 112 can determine whether or not the end face 121 of the flaw detection probe 120 has come into contact with the test object 210 based on the reaction force Fz detected by the detection unit 130.

When the end face 121 of the flaw detection probe 120 is determined to be in contact with the object to be inspected 210, the control unit 112 determines whether the end face 121 is in surface contact with the object to be inspected 210 based on the torques Tx and Ty detected by the detection unit 130. That is, if a part of the end face 121 of the flaw detection probe 120 is in contact with the object to be inspected 210 and the remaining part is away from the object to be inspected 210, at least one of the torques Tx and Ty detected by the detection unit 130 will be a large value. On the other hand, if the end face 121 of the flaw detection probe 120 is entirely in contact with the object to be inspected 210, the torques Tx and Ty detected by the detection unit 130 will be zero or close to zero. Therefore, if a torque threshold close to zero is set for the torques Tx and Ty detected by the detection unit 130, taking into account the detection error of the detection unit 130, it is possible to know whether the end face 121 of the flaw detection probe 120 is in surface contact with the object to be inspected 210. In other words, if the torques Tx and Ty detected by the detection unit 130 are both equal to or less than the torque threshold values thus set, the end surface 121 of the flaw detection probe 120 is considered to be in surface contact with the object to be inspected 210, and control of the manipulator 111 can be executed.

Conversely, if at least one of the torques Tx, Ty detected by the detection unit 130 exceeds the torque threshold, the end face 121 of the flaw detection probe 120 is not in surface contact with the inspection target 210, and control of the manipulator 111 can be executed. In detail, if at least one of the torques Tx, Ty exceeds the torque threshold, the control unit 112 adjusts the position of the arm around the first axis 151 to the sixth axis 156 of the manipulator 111 so that both the torques Tx, Ty are equal to or less than the torque threshold. Such control can be realized by a method of simultaneously controlling the force and position of the manipulator 111, for example, a hybrid control method or a compliance control method.

When the end face 121 of the flaw detection probe 120 is brought into surface contact with the object to be inspected 210 by the above-mentioned control, the control unit 112 judges whether the reaction force Fz detected by the detection unit 130 has reached a predetermined target value (step S110). This target value is set so that the flaw detection probe 120 is not subjected to an excessively strong force from the object to be inspected 210 during scanning of the object to be inspected 210.

If the reaction force Fz detected by the detection unit 130 has not reached the target value (step S110: No), the control unit 112 causes the manipulator 111 to continue to move the flaw detection probe 120 closer to the inspection object 210. If the reaction force Fz detected by the detection unit 130 reaches the target value (step S110: Yes), scanning of the inspection object 210 is started. During scanning of the inspection object 210, the flaw detection probe 120 emits ultrasonic waves from the end face 121 and receives ultrasonic echoes from the inspection object 210 at the end face 121.

When scanning of the inspection target 210 is started, the control unit 112 controls the manipulator 111 so that the flaw detection probe 120 moves a predetermined distance along the scanning path at a predetermined first speed (step S115). During this time, the control unit 112 monitors the reaction force Fz, friction forces Fx, Fy, and torques Tx, Ty detected by the detection unit 130, and performs a predetermined determination process (step S120).

In this determination process, a predetermined threshold range set for the reaction force Fz, a predetermined friction threshold set for the friction forces Fx and Fy, and the above-mentioned torque threshold are used. The friction threshold is set to a value that can guarantee that the entire end face 121 of the flaw detection probe 120 is in surface contact with the surface of the test object 210. The lower limit of the threshold range for the reaction force Fz is set to a value that can guarantee that the end face 121 of the flaw detection probe 120 is in contact with the surface of the test object 210. The upper limit of the threshold range is set to a value lower than the reaction force Fz that the flaw detection probe 120 can tolerate. In detail, the threshold range is set so that the reaction force Fz falls between the lower limit and the upper limit if a predetermined film thickness of the contact medium 220 on the surface of the test object 210 is obtained. The above-mentioned target value is set to a value within the threshold range.

The control unit 112 compares the friction forces Fx, Fy and torques Tx, Ty detected by the detection unit 130 with the friction threshold and torque threshold (step S120). If the friction forces Fx, Fy and torques Tx, Ty detected by the detection unit 130 are equal to or less than the friction threshold and torque threshold, the control unit 112 determines that the end surface 121 of the flaw detection probe 120 is maintaining surface contact with the surface of the inspection object 210.

The control unit 112 causes the manipulator 111 to adjust the position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system so that the reaction force Fz detected by the detection unit 130 falls within the above-mentioned threshold range. In detail, the control unit 112 causes the manipulator 111 to adjust the position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system so that the reaction force Fz detected by the detection unit 130 approaches the above-mentioned target value.

The reaction force Fz detected by the detection unit 130 is affected by the shape of the surface of the test object 210. If the surface of the test object 210 is parallel to the scanning direction of the flaw detection probe 120 (the X-axis and Y-axis directions in the base coordinate system) as shown in FIG. 3, the reaction force Fz detected by the detection unit 130 fluctuates little and can continuously take a value close to the target value.

On the other hand, if the surface of the object to be inspected 210 is wavy, the reaction force Fz detected by the detection unit 130 will fluctuate more than when the surface of the object to be inspected 210 is parallel to the scanning direction of the flaw detection probe 120 (the X-axis and Y-axis directions in the base coordinate system).

For example, when the surface of the object to be inspected 210 is undulated, the surface shape shown in FIG. 4 can be considered. In FIG. 4, a gradient is generated on the surface of the object to be inspected 210 such that the distance between the end face 121 of the flaw detection probe 120 and the surface of the object to be inspected 210 decreases as the flaw detection probe 120 moves in the positive direction on the X-axis of the base coordinate system. When the flaw detection probe 120 approaches this gradient portion, the reaction force Fz and friction force Fx detected by the detection unit 130 increase. In this state, in order to reduce the reaction force Fz and bring it closer to the target value, the control unit 112 moves the flaw detection probe 120 in the positive direction on the Z-axis of the base coordinate system. This reduces the reaction force Fz, and therefore the friction force Fx also decreases.

Even after the reaction force Fz is reduced, the reaction force Fz acting on the end face 121 of the flaw detection probe 120 may be non-uniform in the gradient portion of the surface of the test object 210. That is, in the gradient portion of the surface of the test object 210, the front portion of the end face 121 of the flaw detection probe 120 in the scanning direction may receive a stronger reaction force than the rear portion. When such a reaction force state occurs, the detection unit 130 may detect a torque Ty that exceeds the torque threshold value. In this case, the control unit 112 adjusts the position of the arm around the first axis 151 to the sixth axis 156 of the manipulator 111 until the torque Ty detected by the detection unit 130 becomes equal to or less than the torque threshold value. As a result, the flaw detection probe 120 tilts backward in the scanning direction so that the end face 121 of the flaw detection probe 120 follows the surface of the test object 210.

Figure 5 shows a case where a gradient opposite to that in Figure 4 occurs. That is, on the surface of the object to be inspected 210 in Figure 5, a gradient occurs such that the distance between the end face 121 of the flaw detection probe 120 and the surface of the object to be inspected 210 increases as the flaw detection probe 120 moves in the positive direction on the X-axis of the base coordinate system. When the flaw detection probe 120 approaches this gradient portion, the reaction force Fz and the friction force Fx decrease. In this case, the control unit 112 moves the flaw detection probe 120 in the negative direction on the Z-axis of the base coordinate system. This increases the reaction force Fz and approaches the target value.

At this time, it is assumed that only the rear portion of the end face 121 of the flaw detection probe 120 in the scanning direction is in contact with the object to be inspected 210, and the front portion is separated from the object to be inspected 210. In this case, the detection unit 130 may detect a torque Ty that exceeds the torque threshold. When the detection unit 130 detects a torque Ty that exceeds the torque threshold, the control unit 112 adjusts the position of the arm around the first axis 151 to the sixth axis 156 of the manipulator 111 until the torque Ty detected by the detection unit 130 becomes equal to or less than the torque threshold. As a result, the flaw detection probe 120 tilts forward in the scanning direction so that the end face 121 of the flaw detection probe 120 is aligned with the surface of the object to be inspected 210.

While the flaw detection probe 120 is moving a predetermined distance (step S115), the control unit 112 controls the manipulator 111 while performing the above-mentioned judgment process (step S120) to adjust the position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system. In this judgment process, if all of the following conditions are satisfied, the control unit 112 judges that the scan while the flaw detection probe 120 is moving a predetermined distance is normal (step S120: Yes).
The reaction force Fz falls within the threshold range.
- The friction forces Fx and Fy are equal to or less than the friction threshold value.
The torques Tx and Ty are equal to or less than the torque threshold values.

If the result of the determination indicates that the scan is normal, data on the position of the flaw detection probe 120 on the X-axis, Y-axis, and Z-axis of the flaw detection probe 120 and the rotational position of the manipulator 111 around the Z-axis are output from the control unit 112 to the memory unit 140 (step S130). The data output from the control unit 112 to the memory unit 140 is stored in the memory unit 140 as history data.

After the history data is stored in the memory unit 140, the control unit 112 determines whether the flaw detection probe 120 has reached the scan end position (step S135). If the flaw detection probe 120 has reached the scan end position (step S135: Yes), the flaw detection inspection ends. If the flaw detection probe 120 has not reached the scan end position (step S135: No), the control unit 112 continues the movement of the flaw detection probe 120 (i.e., scanning the inspection target 210) (step S115). In this case, the control unit 112 controls the manipulator 111 while repeating the processing loop of steps S115 to S135, and continues scanning the surface of the inspection target 210 with the flaw detection probe 120. During this time, the history data is accumulated in the memory unit 140, and the position on the scanning path to which the flaw detection probe 120 has normally scanned the inspection target 210 is recorded.

While the flaw detection probe 120 is scanning a predetermined distance, the position of the flaw detection probe 120 is adjusted, but it is possible that the reaction force Fz falls outside the threshold range, or that the friction forces Fx, Fy and torques Tx, Ty exceed the friction threshold and torque threshold.

When the reaction force Fz falls outside the threshold range (step S120: No), it may be that the control by the control unit 112 is unable to keep up with the fluctuations in the reaction force Fz. That is, since the position of the flaw detection probe 120 is adjusted after the reaction force Fz is detected, a time lag occurs between the detection of the reaction force Fz and the adjustment of the position of the flaw detection probe 120. During this time lag, it is expected that the reaction force Fz will fall outside the threshold range.

For example, if the gradient shown in FIG. 4 is steep, the reaction force Fz may exceed the upper limit of the threshold range. Also, if the gradient shown in FIG. 5 is steep, the reaction force Fz may fall below the lower limit of the threshold range. If the reaction force Fz falls outside the threshold range (step S120: No), the control unit 112 determines that an abnormality has occurred in the scanning of the inspection object 210, and executes abnormality control to prevent the scanning from continuing while the abnormality exists. In this embodiment, the control unit 112 stops the manipulator 111 in abnormality control (step S125).

When a gradient that increases the reaction force Fz occurs in the object of inspection 210, the frictional forces Fx and Fy also increase. Even if the end face 121 of the flaw detection probe 120 is in surface contact with the surface of the object of inspection 210, if the frictional forces Fx and Fy are large enough to exceed the friction threshold, it is predicted that the flaw detection probe 120 will subsequently tilt significantly, and a part of the end face 121 will separate from the surface of the object of inspection 210. For this reason, even if the frictional forces Fx and Fy become larger than the friction threshold, the control unit 112 determines that an abnormality has occurred in the scanning of the object of inspection 210, and executes abnormality control to prevent the scanning from continuing while the abnormality exists.

On the other hand, if an obstacle that impedes the movement of the flaw detection probe 120 occurs on the surface of the object to be inspected 210 (see FIG. 6), the flaw detection probe 120 may tilt without an increase in frictional forces Fx and Fy appearing as a sign of a large tilt of the flaw detection probe 120. FIG. 6 shows a minute protrusion protruding from the surface of the object to be inspected 210 as an obstacle that impedes the movement of the flaw detection probe 120, and the flaw detection probe 120 in FIG. 6 has moved in the X-axis direction of the base coordinate system and is in contact with this minute protrusion.

When the flaw detection probe 120 moves in the X-axis direction of the base coordinate system and comes into contact with a microprotrusion, causing the flaw detection probe 120 to tilt, the detection unit 130 detects a torque Ty that is greater than the torque Ty before the flaw detection probe 120 came into contact with the microprotrusion. In such a case, it is considered that the change in torque Ty is more noticeable than the change in friction force Fx. Therefore, when the flaw detection probe 120 actually tilts, it is considered that the determination process (step S120) using the torques Tx and Ty can determine the tilted state of the flaw detection probe 120 more accurately than the determination process using the friction forces Fx and Fy.

If the torques Tx and Ty are greater than the torque thresholds (step S120: No), tilting of the tip portion 118 of the manipulator 111 holding the flaw detection probe 120 may have caused a portion of the end face 121 of the flaw detection probe 120 to become separated from the surface of the object to be inspected 210. To prevent scanning of the object to be inspected 210 from continuing in this state, the control unit 112 executes the abnormality control described above (stop control of the manipulator 111) (step S125).

When the manipulator 111 is stopped (step S125), after the stop control, control is performed to resume scanning of the inspection object 210 using the history data stored in the memory unit 140. Note that as a result of repeating the processing loop of steps S115 to S135, the history data includes information on the positions of the flaw detection probe 120 on the X-axis, Y-axis, and Z-axis immediately before the stop control, and the rotational position of the manipulator 111 around the Z-axis.

After stopping the manipulator 111 (step S125), the control unit 112 controls the manipulator 111 based on the history data in the memory unit 140 so that the flaw detection probe 120 returns to its previous position (step S140). This control causes the flaw detection probe 120 to return to the position indicated by the history data stored in the memory unit 140 immediately before the manipulator 111 was stopped (step S125). In other words, the positions of the flaw detection probe 120 on the X-axis, Y-axis, and Z-axis and the rotational position of the manipulator 111 around the Z-axis return to the states immediately before the abnormality control (step S125).

After returning the flaw detection probe 120 to the state immediately before the abnormality control (step S125), the control unit 112 controls the manipulator 111 so that the flaw detection probe 120 moves along the scanning path at a second speed lower than the first speed of step S115 (step S145). As a result, the flaw detection probe 120 scans the inspection target 210 at a relatively low speed toward the stop position when the manipulator 111 stops (step S145).

While the flaw detection probe 120 is moving at a low speed (step S145), the control unit 112 performs a judgment process similar to the judgment process in step S120 (step S150). Since the flaw detection probe 120 is moving at a low speed, even if a steep gradient occurs on the surface of the inspection object 210 at the above-mentioned stop position, the position control of the flaw detection probe 120 in the Z-axis direction of the base coordinate system is easy to follow the shape change of the surface of the inspection object 210. That is, it is easy to obtain a scanning state for the inspection object 210 in a state where the reaction force Fz is maintained within the threshold range. In addition, if the reaction force Fz is within the threshold range, the friction forces Fx and Fy are also easy to take values below the friction threshold, so that large tilting of the flaw detection probe 120 due to the friction forces Fx and Fy is also difficult to occur. That is, it is easy to scan the inspection object 210 with the end face 121 of the flaw detection probe 120 in surface contact with the surface of the inspection object 210.

In addition, when the flaw detection probe 120 moves at a low speed, the force applied when the flaw detection probe 120 comes into contact with the object that generates the large torques Tx and Ty (for example, the micro-protrusions in FIG. 6) is small. Therefore, the flaw detection probe 120 is less likely to receive torques Tx and Ty that exceed the torque thresholds.

If the control unit 112 determines that the scanning while the flaw detection probe 120 is moving at a low speed is normal (step S150: Yes), the history data is stored in the memory unit 140 (step S130). Then, a process is performed to determine whether the flaw detection probe 120 has reached the scan end position (step S135). If the flaw detection probe 120 has not reached the scan end position (step S135: No), the control unit 112 increases the moving speed of the flaw detection probe 120 to the first speed and continues scanning the inspection object 210 (step S115).

If the reaction force Fz falls outside the threshold range or the friction forces Fx, Fy and torques Tx, Ty exceed the friction threshold and torque threshold while the flaw detection probe 120 is moving at the second speed (step S150: No), the control unit 112 ends scanning of the inspection object 210.

In the above embodiment, the control unit 112 controls the manipulator 111 so that both of the torques Tx and Ty detected by the detection unit 130 are equal to or less than the torque threshold value. At least one of the torques Tx and Ty detected by the detection unit 130 becomes larger if a state occurs in which a part of the end face 121 of the flaw detection probe 120 is in contact with the object to be inspected 210 more than the remaining part. In this case, since the torque threshold value is set to a value close to zero taking into account the detection error of the detection unit 130, at least one of the torques Tx and Ty may exceed the torque threshold value. At this time, the control unit 112 controls the manipulator 111 so that both of the torques Tx and Ty detected by the detection unit 130 are equal to or less than the torque threshold value. As a result, the flaw detection probe 120 can take a tilting posture such that the end face 121 of the flaw detection probe 120 follows the surface of the object to be inspected 210 (tracing operation). Therefore, it is not necessary to obtain information on the tilting posture of the flaw detection probe 120 as advance information before flaw detection inspection of the object to be inspected 210.

The position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system is adjusted based on the reaction force Fz detected by the detection unit 130. Therefore, there is no need to obtain information on the position of the flaw detection probe 120 in the Z-axis direction as advance information. Therefore, before flaw detection inspection of the inspection object 210, information for setting the scanning path on the inspection object 210 (i.e., the position of the flaw detection probe 120 on the X-axis and Y-axis of the base coordinate system) only needs to be set in the control unit 112. In other words, there is no need for a teaching operation to have the control unit 112 memorize in advance the tilting attitude of the flaw detection probe 120 and the position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system over the entire scanning path.

According to the above-described embodiment, the control unit 112 controls the position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system so that the reaction force Fz detected by the detection unit 130 falls within a threshold range. Therefore, as long as the control follows the shape changes (e.g., waviness) of the surface of the test object 210, the test object 210 can be scanned with the end face 121 of the flaw detection probe 120 in surface contact with the surface of the test object 210.

For example, when a gradient as shown in FIG. 4 occurs on the surface of the object to be inspected 210, the control unit 112 controls the flaw detection probe 120 to displace in the positive direction on the Z axis of the base coordinate system in accordance with the gradient of the surface of the object to be inspected 210. As a result, the end face 121 of the flaw detection probe 120 is prevented from coming too close to the surface of the object to be inspected 210. In other words, a state in which the thickness of the contact medium 220 between the end face 121 of the flaw detection probe 120 and the surface of the object to be inspected 210 becomes too small is avoided.

Conversely, when a gradient as shown in FIG. 5 occurs on the surface of the object to be inspected 210, the control unit 112 controls the flaw detection probe 120 to displace in the negative direction on the Z axis of the base coordinate system in accordance with the gradient of the surface of the object to be inspected 210. As a result, the end face 121 of the flaw detection probe 120 is prevented from moving away from the surface of the object to be inspected 210. In other words, no air layer is formed between the end face 121 of the flaw detection probe 120 and the contact medium 220, and flaw detection inspection of the object to be inspected 210 can be performed without being hindered by the air layer.

If the gradient on the surface of the object to be inspected 210 is steep, it is expected that the reaction force Fz will fall outside the threshold range between when the detection unit 130 detects the reaction force Fz and when the control unit 112 controls the position of the flaw detection probe 120 in response to this reaction force Fz. In this case, the control unit 112 stops the manipulator 111. This prevents the flaw detection inspection from being continued in a state where the end face 121 of the flaw detection probe 120 is excessively close to the surface of the object to be inspected 210 and in a state where the end face 121 of the flaw detection probe 120 is not in surface contact with the surface of the object to be inspected 210.

In any of the following cases, the control unit 112 stops the manipulator 111 and prevents the flaw detection inspection from continuing when a portion of the end face 121 of the flaw detection probe 120 is not in surface contact with the surface of the object to be inspected 210.
When the detection unit 130 detects frictional forces Fx, Fy that exceed a friction threshold value.
When the detection unit 130 detects torques Tx and Ty that exceed the torque threshold value.

Even if the end face 121 of the flaw detection probe 120 is in surface contact with the surface of the inspection object 210, if the friction forces Fx and Fy exceed the friction threshold, it is predicted that the flaw detection probe 120 will subsequently tilt significantly, and the surface contact state of the end face 121 of the flaw detection probe 120 will subsequently be lost. In other words, by performing a judgment process while monitoring the friction forces Fx and Fy, it becomes possible to detect a sign of a significant tilt of the flaw detection probe 120 and execute abnormality control while maintaining the surface contact state of the end face 121 of the flaw detection probe 120.

When the flaw detection probe 120 tilts, the tilt of the flaw detection probe 120 is more likely to be evident as a change in the torques Tx and Ty rather than a change in the frictional forces Fx and Fy. Therefore, when the flaw detection probe 120 actually tilts, the tilt state of the flaw detection probe 120 can be accurately determined by a determination process using the torques Tx and Ty.

Even if the control unit 112 stops the manipulator 111, it is permitted to resume the flaw detection inspection from the position where the flaw detection inspection of the inspection target 210 was performed normally, as described below. Information on the position where the flaw detection inspection was performed normally is stored as history data in the memory unit 140. Therefore, based on the history data stored in the memory unit 140 immediately before the manipulator 111 is stopped, the control unit 112 can control the manipulator 111 so that the flaw detection probe 120 returns to the position represented by the history data. If the flaw detection probe 120 is returned to the position immediately before represented by the history data, the flaw detection probe 120 can take a posture such that the end face 121 is aligned with the surface of the inspection target 210 due to the reaction force Fz from the inspection target 210 at that position. Therefore, the memory unit 140 does not need to store the tilting posture of the flaw detection probe 120 as history data.

In the above-described embodiment, the magnitudes of the reaction force Fz, the frictional forces Fx, Fy, and the torques Tx, Ty are used to determine whether or not to stop the manipulator 111 (steps S120 and S150 in FIG. 2). In addition to these, the control unit 112 may determine whether or not to stop the manipulator 111 based on the rate of increase in the magnitudes of the reaction force Fz, the frictional forces Fx, Fy, and the torques Tx, Ty.

For example, the control unit 112 may stop the manipulator 111 if the rate of increase in the reaction force Fz exceeds a predetermined threshold even if the reaction force Fz is within the threshold range. By performing such control, it becomes possible to stop the manipulator 111 before an excessively large load acts on the flaw detection probe 120.

In the above embodiment, the control unit 112 stops the manipulator 111 in the abnormality control (step S125). Alternatively, the control unit 112 may notify the inspector that an abnormality has occurred in the scanning of the inspection target 210 by a notification means such as a sound or an image, and prevent the scanning from continuing.

In the above embodiment, even if the flaw detection probe 120 is moved at the second speed (step S145), if the control unit 112 determines that the surface contact state of the end face 121 of the flaw detection probe 120 is lost (step S150: No), the flaw detection inspection of the inspection object 210 is terminated. Instead of terminating the flaw detection inspection, the control unit 112 may move the flaw detection probe 120 at a third speed lower than the second speed and re-execute the determination process for the reaction force Fz, the friction forces Fx, Fy, and the torques Tx, Ty (step S150). If multiple setting values for the movement speed of the flaw detection probe 120 when resuming the flaw detection inspection of the inspection object 210 are prepared, it becomes easier to continue the flaw detection inspection of the inspection object 210.

In the above embodiment, the detection unit 130 detects the friction forces Fx, Fy and the torques Tx, Ty, which are compared with the friction threshold and the torque threshold. Alternatively, the detection unit 130 may detect the torques Tx, Ty but not the friction forces Fx, Fy. In this case, as shown in step S120 of FIG. 7, the torques Tx, Ty are compared with the torque threshold, but the friction forces Fx, Fy are not compared with the friction threshold. In the process shown in FIG. 7, the abnormality control cannot be executed before the flaw detection probe 120 tilts, but the abnormality control can be executed after the flaw detection probe 120 tilts with torques Tx, Ty larger than the torque threshold. In addition, since the determination process for the friction forces Fx, Fy is not performed, the determination process in the control unit 112 is simplified.

Second Embodiment
If the flaw detection probe 120 is configured to generate an eddy current on the surface of the inspection object 210, it is possible to detect the presence or absence of a flaw on the surface of the inspection object 210 by utilizing the change in the eddy current. In this case, the manipulator 111, the control unit 112, the detection unit 130, and the storage unit 140 may have the same configuration as in the first embodiment. Also, the contact medium 220 is not applied to the surface of the inspection object 210.

As shown in FIG. 8, the flaw detection probe 120 includes a coil 122. The coil 122 is connected to a bridge circuit 123. In detail, the bridge circuit 123 includes a power source 124, impedance sections 125 and 126, a variable impedance section 127, and a detection circuit 128. The impedance of the coil 122 and the impedance sections 125 and 126 is constant, while the impedance of the variable impedance section 127 is adjustable. The detection circuit 128 is provided to detect changes in eddy currents. The current flowing through the detection circuit 128 is monitored, and the presence or absence of scratches on the surface of the inspection object 210 is determined based on the change in current.

The flaw detection probe 120 is attached to the manipulator 111 as shown in FIG. 1. The flaw detection device 100 then operates according to the procedure shown in FIG. 7.

In the stage of preparing for flaw detection (step S105), after the flaw detection probe 120 is moved to the scanning start position, the position of the flaw detection probe 120 in the Z-axis direction of the base coordinate system is adjusted based on the reaction force Fz acting on the flaw detection probe 120 (step S110). In addition, the control unit 112 controls the manipulator 111 based on the torques Tx and Ty detected by the detection unit 130 so that the end face 121 of the flaw detection probe 120 is in surface contact with the object to be inspected 210.

After that, a current is passed through the coil 122, and the impedance of the variable impedance section 127 is adjusted so that the bridge circuit 123 is in a balanced state. When the bridge circuit 123 is in a balanced state, the current flowing through the detection circuit 128 is approximately zero. It is assumed that there are no scratches on the surface of the inspection target 210 at the scanning start position.

When there are no scratches on the surface of the inspection object 210, the eddy currents flowing on the surface of the inspection object 210 form a roughly concentric pattern, as shown in FIG. 9. In this state, the bridge circuit 123 is kept in a balanced state, and no current flows through the detection circuit 128.

When the flaw detection probe 120 is moved along the surface of the object to be inspected 210 and reaches a flaw on the surface of the object to be inspected 210, the concentric pattern of eddy currents is disrupted and the balanced state of the bridge circuit 123 is lost. In this case, a current flows through the detection circuit 128. Based on this current, it is possible to determine the size and depth of the flaw.

As described in the first embodiment, the position and attitude adjustment of the flaw detection probe 120 is controlled based on the detection result of the detection unit 130. Therefore, during scanning of the object to be inspected 210, the entire end face 121 of the flaw detection probe 120 is kept in surface contact with the object to be inspected 210. As a result, fluctuations in eddy currents (and thus fluctuations in the magnitude of the current flowing through the detection circuit 128) caused by lift-off fluctuations of the flaw detection probe 120 are less likely to occur. Therefore, the presence or absence of scratches on the surface of the object to be inspected 210 can be determined with high accuracy.

If the flaw detection probe 120 experiences increased lift-off, abnormality control is performed (steps S125 to S150 in FIG. 7). The abnormality control prevents scanning of the object to be inspected 210 from continuing in the lift-off state. In other words, scanning of the object to be inspected 210 is prevented from continuing in a state in which no eddy currents are generated on the surface of the object to be inspected 210 or in a state in which the eddy currents on the surface of the object to be inspected 210 are weak. As a result, the flaw detection device 100 is less likely to miss scratches on the surface of the object to be inspected 210.

In the above embodiment, the scanning path is set on the X-Y plane in the base coordinate system. Alternatively, as shown in FIG. 10, the scanning path may be set on the Y-Z plane in the base coordinate system. In this case, the position control (steps S120, S150) of the flaw detection probe 120 based on the reaction force Fz from the inspection object 210 is performed in the X-axis direction in the base coordinate system. The scanning path may be set on the X-Z plane in the base coordinate system, or along a plane of any orientation.

In the above embodiment, the scanning path is set on a flat surface of the inspection object 210. Alternatively, the scanning path may be set on a curved surface of the inspection object 210. For example, as shown in FIG. 11, if the inspection object 210 is a cylinder, the scanning path is set along the circumferential surface of the cylinder.

In this case, the scanning direction of the flaw detection probe 120 at point P on the circumferential surface of the cylinder approximately coincides with the tangent direction at point P. When the position of the flaw detection probe 120 is adjusted at point P based on the reaction force Fz from the inspection object 210, the manipulator 111 changes the position of the flaw detection probe 120 in a direction perpendicular to the tangent at point P (i.e., the normal direction).

The principles of the above-described embodiments can be suitably used for flaw detection testing.

100: Flaw detection device 111: Manipulator 112: Control unit 120: Flaw detection probe 121: End surface 122: Coil 130: Detection unit 140: Memory unit 210: Inspection object 220: Contact medium

Claims (6)

A flaw detection device that performs flaw detection while scanning a surface of an object to be inspected,
a flaw detection probe having an end face directed toward the surface of the object to be inspected;
a manipulator configured to hold the flaw detection probe with the end face of the flaw detection probe facing the surface of the object to be inspected, and to move the flaw detection probe in a predetermined scanning direction along the surface of the object to be inspected and in a direction perpendicular to the surface of the object to be inspected;
a detection unit for detecting a reaction force and a torque applied to the flaw detection probe from the inspection object;
a control unit that controls the manipulator so that the flaw detection probe moves in the scanning direction;
a memory unit configured to store historical data of the position of the flaw detection probe while the surface of the test object is being scanned;
The control unit is
While controlling the manipulator to move the flaw detection probe in the scanning direction, the manipulator is controlled so that the position of the flaw detection probe in a direction perpendicular to the surface of the object to be inspected is adjusted so that the reaction force detected by the detection unit is within a predetermined threshold range, and the manipulator is controlled so that the attitude of the flaw detection probe is adjusted by tilting the flaw detection probe so that the torque detected by the detection unit is within a predetermined torque threshold range,
When the reaction force detected by the detection unit falls outside the threshold range, or when the torque exceeds the torque threshold, it is determined that an abnormality has occurred in the scanning of the inspection object, and a predetermined abnormality control is executed to prevent the scanning of the inspection object from being continued while the abnormality is occurring,
In the abnormality control, the control unit controls the manipulator based on the history data so as to return the flaw detection probe to the position of the flaw detection probe before the manipulator was stopped after stopping the manipulator, and controls the manipulator to move the flaw detection probe that has been returned to the position before the manipulator was stopped at a speed slower than the moving speed of the flaw detection probe before the manipulator was stopped toward the position of the flaw detection probe when the manipulator was stopped to scan the object to be inspected . A flaw detection device that performs flaw detection while scanning a surface of an object to be inspected,
a flaw detection probe having an end face directed toward the surface of the object to be inspected;
a manipulator configured to hold the flaw detection probe with the end face of the flaw detection probe facing the surface of the object to be inspected, and to move the flaw detection probe in a predetermined scanning direction along the surface of the object to be inspected and in a direction perpendicular to the surface of the object to be inspected;
a detection unit that detects a reaction force and a torque that the flaw detection probe receives from the inspection object and a friction force that acts on the end surface of the flaw detection probe;
a control unit that controls the manipulator so that the flaw detection probe moves in the scanning direction;
a memory unit configured to store historical data of the position of the flaw detection probe while the surface of the test object is being scanned;
The control unit is
While controlling the manipulator to move the flaw detection probe in the scanning direction, the manipulator is controlled so that the position of the flaw detection probe in a direction perpendicular to the surface of the object to be inspected is adjusted so that the reaction force detected by the detection unit is within a predetermined threshold range, and the manipulator is controlled so that the attitude of the flaw detection probe is adjusted by tilting the flaw detection probe so that the torque detected by the detection unit is within a predetermined torque threshold range,
when the frictional force detected by the detection unit exceeds a predetermined friction threshold, it is determined that an abnormality has occurred in the scanning of the inspection object, and a predetermined abnormality control is executed to prevent the scanning of the inspection object from being continued while the abnormality is occurring,
In the abnormality control, the control unit controls the manipulator based on the history data so as to return the flaw detection probe to the position of the flaw detection probe before the manipulator was stopped after stopping the manipulator, and controls the manipulator to move the flaw detection probe that has been returned to the position before the manipulator was stopped at a speed slower than the moving speed of the flaw detection probe before the manipulator was stopped toward the position of the flaw detection probe when the manipulator was stopped to scan the object to be inspected. The flaw detection device according to claim 1 or 2, wherein the flaw detection probe is configured to emit ultrasonic waves from the end face and to receive ultrasonic echoes at the end face via a contact medium applied to the surface of the object to be inspected. 3. The flaw detection device according to claim 1 , wherein the flaw detection probe is configured to generate an eddy current on the surface of the object to be inspected by passing a current through a built-in coil. A flaw detection inspection method for detecting flaws by scanning an inspection object while moving an end face of a flaw detection probe along a surface of the inspection object, comprising:
detecting a reaction force and a torque that the flaw detection probe receives from the object to be inspected while moving the flaw detection probe in a predetermined scanning direction along the surface of the object to be inspected with the end face of the flaw detection probe facing the surface of the object to be inspected;
While moving the flaw detection probe in the scanning direction, a position of the flaw detection probe is adjusted in a direction perpendicular to the surface of the object to be inspected so that the detected reaction force is within a predetermined threshold range, and the flaw detection probe is tilted to adjust the attitude of the flaw detection probe so that the detected torque is within a predetermined torque threshold range.
storing historical data of the position of the flaw detection probe while scanning the surface of the object to be inspected in a memory unit;
if the detected reaction force falls outside the threshold range, or if the torque exceeds the torque threshold, determining that an abnormality has occurred in the scanning of the inspection object, and executing a predetermined abnormality control to prevent the scanning of the inspection object from being continued while the abnormality is occurring;
In the abnormality control,
After stopping the flaw detection probe, returning the flaw detection probe to a position of the flaw detection probe before the flaw detection probe was stopped based on the history data;
and moving the flaw detection probe, which has been returned to the position before the flaw detection probe was stopped, toward the position where the flaw detection probe was stopped.
A flaw detection inspection method , wherein a moving speed of the flaw detection probe when the flaw detection probe moves toward a stopped position is slower than a moving speed of the flaw detection probe before the flaw detection probe is stopped . A flaw detection inspection method for detecting flaws by scanning an inspection object while moving an end face of a flaw detection probe along a surface of the inspection object, comprising:
With the end face of the flaw detection probe facing the surface of the object to be inspected, the flaw detection probe is moved in a predetermined scanning direction along the surface of the object to be inspected, while detecting a reaction force and a torque that the flaw detection probe receives from the object to be inspected, and a frictional force that acts on the end face of the flaw detection probe;
While moving the flaw detection probe in the scanning direction, a position of the flaw detection probe is adjusted in a direction perpendicular to the surface of the object to be inspected so that the detected reaction force is within a predetermined threshold range, and the flaw detection probe is tilted to adjust the attitude of the flaw detection probe so that the detected torque is within a predetermined torque threshold range.
storing historical data of the position of the flaw detection probe while scanning the surface of the object to be inspected in a memory unit;
When the friction force exceeds a predetermined friction threshold, it is determined that an abnormality has occurred in the scanning of the inspection object, and a predetermined abnormality control is executed to prevent the scanning of the inspection object from being continued while the abnormality is occurring.
In the abnormality control,
After stopping the flaw detection probe, returning the flaw detection probe to a position of the flaw detection probe before the flaw detection probe was stopped based on the history data;
and moving the flaw detection probe, which has been returned to the position before the flaw detection probe was stopped, toward the position where the flaw detection probe was stopped.
A flaw detection inspection method, wherein a moving speed of the flaw detection probe when the flaw detection probe moves toward a stopped position is slower than a moving speed of the flaw detection probe before the flaw detection probe is stopped.