JPS5913706B2 - Weld position detection device - Google Patents

Description

[Detailed Description of the Invention] The present invention detects the amount of ferrite in a welded part of a material mainly made of austenitic stainless steel. ・The position of the welded part is detected by a ferrite amount measuring track that moves along the welded part. The present invention relates to a welding position detection device having a correction function.

In nuclear power plants, chemical plants, etc., materials mainly made of austenitic stainless steel are often used for containers, piping, etc. that prevent the contents of containers from becoming contaminated due to corrosion.

Welded parts of materials mainly made of austenitic stainless steel may be subjected to various non-destructive inspections during container manufacturing and during use, as with general carbon steel materials.In particular, in the case of nuclear power plants, welded parts are inspected during construction and during use. It is necessary to check the soundness by ultrasonic flaw detection test etc. during the period of use. For this reason, it is common practice to attach a rail or the like along the welding area in advance during welding, and to perform welding using a drive mechanism that runs on the rail. However, whether the rails are parallel to the welds cannot be detected except by installing the rails during construction, and in particular, once installed inside the reactor containment vessel, the rails cannot be detected if they are parallel to the welds due to some external force. Even if the position changes, it is often impossible to correct it due to the amount of radiation exposure.Also, vacuum the area where there is no rail!
There are examples of moving the ultrasonic probe by suction, etc., but it is especially difficult to determine the direction when automatic operation is used.Also, when the welded surface of a welded part of a material mainly made of austenitic stainless steel is finished using a grinder, etc. There are cases where the welding position cannot be determined with the naked eye at all. When performing a non-destructive inspection such as an ultrasonic flaw detection test, an acoustic emission test, or a radiographic examination on a welded part, it is not possible to carry out the inspection and analyze the welded part unless it is determined where the welded part is. Especially in ultrasonic flaw detection tests, it is necessary to know the position of the weld accurately■0
There is. There are two ways to accurately determine the position of a weld: one is to use ultrasonic waves to determine the difference in the amount of attenuation of the ultrasonic waves between the base metal and the weld, the other is to determine the amount of ferrite (hereinafter referred to as magnetization), which is based on the difference in minute electrical resistance. There are different methods based on the difference in the meaning of measurement (used in the general sense of measurement). ■5 The present invention takes advantage of the fact that the amount of ferrite in the welded part of the material mainly made of austenitic stainless steel is different from that of the base metal, while correcting the trajectory on the rail (or trackless surface) along the welded part. A method and device for detecting the position of a welded part, which is capable of changing the direction of travel by performing an ultrasonic flaw detection test and detecting the intersection point of a welded part or the end point of one weld line, is equipped with a trajectory correction and direction change function. The purpose is to obtain. That is, the present invention provides a main operating mechanism for the straight direction (including when there is no rail or unique track), a trajectory correction mechanism (sensor) for correcting the trajectory to the center of the weld line, and the end point or starting point of the weld and the intersection. A direction change mechanism that detects objects and changes the direction of travel (
It is characterized by being able to detect the welding position of the welded part of a material mainly made of austenitic stainless steel (sensor), correct the trajectory, and change the direction.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1a shows the distribution of the amount of ferrite when there is a welded part 2 in the base material 1, which is mainly made of austenitic stainless steel, as shown in Figure 1b. It is a figure showing that a welded part can be detected by the amount of ferrite because the amount of ferrite increases (generally 3 to 12%). As can be seen from this figure, since the waveform is trapezoidal, the amount of ferrite decreases rapidly as it leaves the weld. Figure 1Af)I
A''7 varies depending on the case, but 7B0 varies depending on the size of the surface width of the welded part 2 in Fig. 1b, and cannot be determined unconditionally. Figure 2 shows the progress of various trajectories while detecting the amount of ferrite. Figure 2 A shows an example of traveling straight on a welding line by detecting the amount of ferrite, and the vertical axis in the figure is Y, the horizontal axis is X. (
For X and Y in ), the main movement direction (progressing direction) is the X axis (horizontal axis)
No example is given for this case. In Figure 2 A, the main operating direction is the vertical axis (Y
(axis), the trajectory of the mechanism Y moving upward is detected by detecting the amount of ferrite, and the mechanism moves forward while adjusting the trajectory X. If the progress is not shown continuously, the diagram will look staggered. The relationship between the speed in the direction of travel and the amount of trajectory correction has a large effect on the ultrasonic flaw detection results, so the speed should be set to 0.5 to 5 WIJ!
It is desirable that the l/S1 trajectory correction amount be 0.5 to 2u. As a modification, the welding center position can also be determined by periodically swinging one sensor a certain amount over the welding width. The opening in Figure 2 shows the case where the weld is T-shaped, and when the weld is progressing vertically upwards, it crosses the end point of the vertical weld and reaches the base metal 1.
This is an example in which the main operating direction is automatically switched because the amount of ferrite is less than a predetermined amount when the amount reaches a predetermined amount.This example shows an example in which the direction is switched using a single sensor moving on the welding line. The main operating system moves up at a constant speed (in this case, the Y-axis). By detecting the amount of ferrite from the sensor, the trajectory is corrected (X-axis), and while finding a place with a large amount of ferrite, the trajectory is corrected to the direction where the amount of ferrite is large. Here, the main operating system is moving upward at a constant speed, so when the sensor moves beyond the boundary layer between the side weld and the base metal, the amount of ferrite begins to decrease rapidly (see Figure 1). Therefore, if you measure the amount of ferrite in advance, when the amount falls below a certain value, the main operating direction will switch (direction change) to the pre-specified right (or left) direction (X-axis), and the horizontal stripping will occur. We will proceed while adjusting the trajectory (Y axis). It is desirable that the direction of this decrease in the amount of ferrite be reversed when the amount of ferrite reaches 1 to 4% in materials mainly composed of austenitic stainless steel. Figure 2 C shows a case where the horizontal and vertical welds intersect or connect. If the vertical welds are continuous, there is no change in the amount of ferrite with the method shown in Figure 2, so the welds will move to the left (right) at the intersection. It is not possible to turn (change direction). Therefore, in this method (c), by running another ferrite sensor 18 parallel to the welding part, front and back or at the same time, the direction of the ferrite sensor 14 running on the welding part is set at the welding intersection or at the same time. It can be replaced at the connection part. This principle is based on the fact that in the case of the weld, a decrease in the amount of ferrite is detected, but in the case of the case of c, the sensor traveling over the base metal detects an increase in the amount of ferrite at the horizontal (vertical) weld. This indicates that the weld has been reached, indicating that the direction can be changed. Of course, according to this method C, it is possible to change the direction of the T-shaped crossover of the mouth without using the mouth method. Of course, it is also possible to change course over the weld and return the way you came. As mentioned above, in order to simplify the explanation, we have mainly explained the X and Y axes, but the plane (
The combination of the main movement drive mechanism 5 and the trajectory correction drive mechanism 4 shown in FIG. 3 can operate in any direction on a curved surface (including curved surfaces). FIG. 3 is a system diagram designed to detect ferrite and move it straight through the weld, and at the intersection of the welds it can move straight or change its direction of travel.
Contact the ferrite sensor 13a on the welded part 2 of the austenitic stainless steel base metal 1 (if the sensor contacts wear out due to direct contact, put a shield on, but of course calibration is required at this time). This ferrite sensor 13a, which measures the amount of ferrite, is used for trajectory correction (in the case of the entrance in Figure 2, it is also used for trajectory correction and direction change), and the trajectory correction drive mechanism 4a is used for trajectory correction on the main operation drive mechanism 5. installed on. The direction change sensor 30 changes the amount of ferrite in the base material 1 while bringing it into contact with the base material 1 (if the contact of the sensor wears out due to direct contact, it must be shunted; of course, calibration is required in this case). Measure. The structure is divided into main movements: 5 for straight movement, 4 for trajectory correction, and 3.
It is divided into three parts: 30 for changing direction; First, when traveling straight over a welded part, the amount of ferrite detected by the ferrite amount measuring sensor 3a of the trajectory correction drive mechanism 4 is detected by the ferrite amount detector 7 (channel 1), and the amount of ferrite is detected by the ferrite amount measuring sensor 3a of the trajectory correction drive mechanism 4. In the case of a 2-figure exit, a signal may also be sent to the direction change device), and the trajectory can be corrected with a signal from the control device. The main operating drive mechanism 5 moves the vehicle straight in response to a signal from the control device (generally, constant speed is desirable, but it may be changed as necessary). Next, the direction is changed, and in the case of FIG. Ferrite content (ferrite content is often 0.5% or less in materials mainly made of austenitic stainless steel)
The amount of ferrite is measured by the ferrite amount detector 7 (for example, channel 1 2), and when the direction change sensor 30 approaches the welding part, the amount of ferrite increases rapidly. Control device 1 with a signal from
By sending a direction change signal from 0 to the main operating mechanism 5, it is possible to move from straight forward to left or right or back to the original direction. FIG. 4 shows an example where the width of the weld line is narrow and an example where it is wide. As shown in FIG. 4, by placing the measuring leg of the ferrite amount measuring sensor perpendicular to the weld line as shown in the figure, the weld center can be measured with an accuracy of about 1 inch. If the width of the weld is wide, it is not possible to detect the center of the weld with a precision of approximately 1 mJ1 with one sensor, so prepare two or more sensors like the mouth, and detect the direction in which the difference between the two is small. It is necessary to move in the direction where the amount of ferrite is large. Figure 5 shows an example of a drive device that operates along an austenitic stainless steel weld while detecting the amount of ferrite. The working rail 13 is welded to the austenitic stainless steel base metal 1. In this example, it is desirable that the main operating rail 13 is provided with a gear and that the wheel 49 is also a gear. The wheels 49 are rotatably provided on the track correction rail 12, and the track correction drive device 4 moves on this rail, and the ultrasonic probe holding device 14 and the ferrite amount measuring sensor are attached to the track correction device 4. There is. Power rail 36 onto rail 13
Sometimes it is run. The case shown in Fig. 5B is an example that can be used even when the welding part 2 intersects with another weld line, and the arch-shaped rail support 16 is welded to the base material 1, and the rail support 16 is attached to the rail 13. This is an example in which the entire drive unit is supported by a car 19. The entire drive mechanism is guided by the rail 13, and the rail 12 is used to guide the trajectory correction. A rail support 16 is attached to a cord 17 for the probe, a hose 18 for the couplant of the probe. FIG. 6 is an explanatory diagram of the drive mechanism in FIG. 5B. As shown in FIG. 6A, the main operation is to transmit the rotation of the main operation 1 drive motor 34 to the reducer 35 to reduce the speed and move the gear 21. 2
The wheel 15 is rotated by the gear 22 meshing with the wheel 15 to perform movement in the traveling direction. A bearing 23 is attached to the shaft of the wheel 15 to ensure smooth rotation. The drive device that corrects the trajectory while searching for the weld line has a thread cut in the trajectory correction rail 12, and a trajectory correction motor 26.
The rotation of is reduced by the reducer 27 and transmitted to the gear 32.
The gear 31, which rotates the gear 31 by rotation, has a female thread cut on its inner surface, and the track correction rail 12 has a male thread cut, so the gear 31 moves on the track correction rail 12, and the track correction rail 12 has two ends. Since it is fixed to the support 20, it does not rotate.Therefore, the rotational force of the gear 31 causes the gear 31 to correct its orbit together with the motor. The ultrasonic probe 50 is pushed by the spring 51, and water flows through the hose 18 as a couplant to the ultrasonic probe 50. A cover 52 is installed to prevent the water from flowing out.
FIG. 6B shows an example in which the ultrasonic probe holding device 14 and the ferrite amount measuring sensor 3 are integrated. FIG. 6C is a modification of FIGS. 6A and 6B, and shows an example in which the ultrasonic probe holding device 14 and the ferrite amount measurement sensor 3 are separate, each having a drive motor on the top. When conducting a flaw detection test, this diagram C in FIG. 6 is practical. If the rails 12 and 37 are rotated as a modification of FIG. As shown in Figure 6D, the rotation of the drive motors 26 and 28 is controlled by reducers 27 and 2.
9 to rotate gears 30, 30, gears 31,
The gears 31, 33 that rotate the gears 33 are integrated with the rails 12, 11, and the rails 12, 11 have bearings 38, 37 on both sides and rotate. The rails 12 and 11 have screws cut on their surfaces, and the rails 12 and 11 engage with the female threads of the ultrasonic probe holding device 14 and the ferrite measurement sensor 3, and the rails 12 and 11 rotate. 3 does not rotate, so it moves left and right in Figure 6 A and C.
, D, the limits of the left and right movement of the ferrite amount measuring sensor 3 and the probe holding device 14 are set by limit switches 45, respectively.
automatically stops motors 28 and 26. The rotation from each motor is generated as a pulse signal by operating a reed switch 48 using a magnet 47 attached to the rotating shaft. Figure 7 shows the main movement (advancing) rail 13 mounted on the rail support 16.
A magnet 24 is attached to the rail support 16 so that the position can be displayed. Generally, when operating a reed switch with a magnet to display digital data, some noise may cause the digital display to appear. In some cases, the barrel display returns to zero, but in order to prevent the position from becoming completely unknown in that case, the origin can be found as shown in Figure 7.In other words, it takes a long time to return to zero after traveling a certain distance. Because of this loss, the size and arrangement of the magnets are simulated as shown in FIGS. 1-10. It is best to arrange the magnets in the large size 41, small 42, one that operates with a single reed switch (39), and the one that operates with a reed switch (40) in the second row. You can check the order of numbers 1 to 10 in the columns. Of course, you can check the position and order in the same way even if there is only one row or three or more rows. FIG. 9A shows an example of the structure of the rail 13 and the wheel 19. There are various structures as shown in A, C, and C, but it is preferable that the wheel 19 can rotate around an axis as in the case of C. FIG. 9B shows an example where the rails 13 intersect. Having the curved portion 25 on the rail 13 makes it easy to change direction. Figure 10 shows wheel 15
This is an example in which a spring 43 is attached so that the spring 43 can be rotated while being pressed against the base material 1 with a constant force.There are two ways to insert the spring, and there is no difference between the two.
FIG. 11 schematically shows the part that holds the measuring leg 6 of the ferrite amount measuring sensor, which is held down with a constant force by a spring 44. If the spring 46 shown in FIG. 5B is present, the spring 44 shown in FIG. 11 is not needed. Next, we will discuss the effects of the above device.It is difficult to detect welds with the naked eye after surface finishing of materials mainly made of austenitic stainless steel, but when performing an ultrasonic flaw detection test, welding It can be said that detecting is essential for defect wave analysis.

The main operation drive mechanism 5 for moving straight along the welding line on a trackless or non-track surface moves straight at a constant speed. The trajectory correction drive mechanism 4 moves on the main operation drive mechanism 5 while its trajectory is corrected by a trajectory correction device using a servo mechanism or the like to the welding center, that is, the one with a larger amount of ferrite. In addition, the direction change drive mechanism (sensor) moves along with the main operating mechanism over the base material, and when it reaches the weld, it detects the amount of ferrite in the weld and moves it in a predetermined direction by the direction change device (or manually remotely). In the case of operation, the direction can be changed in the direction determined at that time). Furthermore, by attaching a ferrite metal such as general steel to the surface of a material mainly made of austenitic stainless steel other than the welded part, the position can be detected as a ferrite marker and the direction can be changed. If the width of the weld is wide, it is difficult to find the center of the weld, but by installing two or more sensors, the difference between each sensor is detected, and each sensor moves toward the side with a larger amount of ferrite to determine the welding position. can be known accurately. While detecting the welded part, the reed switch is operated by the magnet, and the position can be detected by the pulse signal generated by the flashing of the reed switch. The limit switch determines the travel range and automatically stops the motor when the vehicle moves beyond the travel range and displays the display to prevent motor overload. The arch-shaped support at the welded part serves as a guide in the direction of movement, and the entire drive device is pressed with a constant force by a spring under the support. The ferrite amount measurement sensor detects the welding center position, and the ultrasonic probe performs an ultrasonic flaw detection test, so both operations can be performed separately if necessary. In order to detect the progress, it is convenient to attach a magnet with a different shape and arrangement as an origin (reference point) in addition to the magnet attached to the rotating shaft. As explained above, according to the present invention, it is possible to perform an ultrasonic flaw detection test on a welded part of a material mainly made of austenitic stainless steel while accurately detecting the welding position, and also to perform an ultrasonic flaw detection test on a welded part of a material mainly made of austenitic stainless steel. It is possible to detect parts, etc. and change direction or stop them.

Especially when the width of the weld is wide, it is possible to accurately detect the center position of the weld by having several sensors. If the rail once installed moves a little due to external force, even if the radiation dose is high and it is impossible to get close to the rail and it cannot be corrected, the method of the present invention will move approximately 1
The center of the weld can be detected with extreme precision, and highly reliable ultrasonic flaw detection tests can be performed, increasing safety (reliability) in nuclear power plants, etc.
In addition, this method can be used to perform ultrasonic flaw detection tests on welds by proceeding along the weld line even on a flat track without fixed rails. It is also possible to proceed while detecting the amount of ferrite in dots or along lines using ferrite metal powder or paint containing metal powder that has been placed in advance on a material mainly made of austenitic stainless steel or on a non-ferrous metal. It is. This device uses a magnet to detect the progress of the device with an accuracy of 1VI by operating a reed switch, and automatically stops the device by a limit switch to prevent it from moving beyond the travel range and overloading the motor.
If the display returns to zero due to noise during the movement, the position will not be known unless the display returns to the point where it first started moving, so consider the shape and arrangement of the magnets that were devised along the way, and make sure to return to the point where it first started moving. I'm avoiding it.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the difference in the amount of ferrite between the welded part of austenitic stainless steel and the base metal, and Figure 2 shows the drive unit moving along the weld line by switching directions at straight lines or intersections. Figure 2 A shows the case where the vertical and horizontal welds of T-joint welding intersect on a straight line, Figure 2 C shows the case where they intersect at right angles, Figure 3 is a drive sequence diagram, and Figure 4 Figure 5 shows a method for determining the weld center when the weld is wide. Figure 5 is an example of a drive device. Figure 5 A shows the case where the weld lines intersect or are not connected. Figure 5 B shows the weld line. FIG. 6 is a detailed configuration diagram of the drive device in FIG. 5. FIG. 6A is a diagram showing the case where each track correction drive motor moves along the track correction rail. Figure 6B
Figure 6C shows the case where the ferrite amount measurement sensor and the ultrasonic probe holding device move simultaneously. Figure 6C shows the track correction rail and the ultrasonic flaw detection rail separately, and the ferrite measurement sensor is attached to each drive motor on each rail. , a diagram showing an example in which the ultrasonic probe moves together with the ultrasonic probe holding device, FIG. 6D is the same as FIG. 6C, but a diagram showing a case in which each drive motor does not move on the rail, and FIG. 7 shows a rail support Figure 8 is a diagram showing an example of the arrangement of the magnet.
Figure 9 is an example of a car passing on the rail, Figure 9A is its shape, Figure 9B is a diagram showing the case where it crosses, Figure 10 is a diagram with springs installed in the wheels, and Figure 11 is the measurement of the amount of ferrite. It is a figure which shows the holding example of a sensor. 3... Ferrite amount measurement sensor, 4...
... Orbit correction drive device, 5 ... Main operation drive mechanism, 7 ... Ferrite amount detector, 8 ...
Orbit correction device, 9... Direction change device, 10...
...Control device, 11...Rail (for probe movement), 12...Rail (for trajectory correction), 13
...Rail (for main operation), 14 ... Ultrasonic probe holding device, 15 ... Wheels, 27 ...
...Reducer for trajectory correction, 28...Motor for moving probe, 29...Reducer for moving probe, 3
4... Main operation drive motor, 35...
Main operation drive reducer, 49... Wheels, 50...
...Ultrasonic probe.

Claims (1)

[Scope of Claims] 1. A ferrite sensor that detects the amount of change in the amount of ferrite in the welding base material, a trajectory correction drive device that holds and drives this ferrite sensor, and a trajectory correction drive device that runs and performs the welding process. A rail provided on the base material, a track correction device that receives a detection signal from the ferrite sensor and causes the track correction drive device to travel so that the detection signal is maximized, and a track correction device that moves the track correction drive device to the ferrite center. A welding position detection device consisting of a direction changing device that changes the running direction when the detection signal of 2. The welding position detection device according to claim 1, wherein two ferrite sensors are used, one for a trajectory correction device and one for a direction change device.