JPH06347250A - Plate-thickness measuring apparatus - Google Patents

Abstract

PURPOSE:To provide a plate-thickness measuring apparatus wherein an ultrasonic probe is faced, at a prescribed interval, always perpendicular to the surface of a plate to be measured irrespective of the unevenness of the surface of the plate to be measured, a precise plate-thickness measurement can be executed and even the corner part of the plate to be measured such as the welded part at the lower part of a tank sidewall to a tank bottom plate can be scanned all over. CONSTITUTION:A bracket 30 is installed on a slider 24' which, is supported by an apparatus base body and which is moved and controlled along the surface of a tank bottom plate. A guide rail 31 which guides a raising and lowering slider 33 so as to be freely raised and lowered is installed at the bracket 30. A scanning push car is coupled to the raising and lowering slider 33 via a slider bracket 34 and a bearing box 35. An ultrasonic probe is mounted on the scanning push car.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, plate thickness measurement for automatically measuring and inspecting the wall thickness of the bottom plate of an outdoor storage tank for storing crude oil, petroleum products, chemicals, etc. using ultrasonic waves. It relates to the device.

[0002]

2. Description of the Related Art This type of outdoor storage tank has a structure in which the bottom plate of the tank, especially the part of the bottom plate near the side wall of the tank, is corroded and eroded by rainwater from the outside to reduce the wall thickness after many years have passed since it was constructed. , Regularly measure the thickness of the bottom plate
The law requires you to inspect.

Generally, an ultrasonic method is used for measuring the thickness of such a bottom plate, and conventionally, a portable type ultrasonic measuring device was brought into a tank and manually measured by an operator. However, in the case of measuring the plate thickness of the bottom plate of a large tank such as a crude oil tank or a naphtha tank, there are a large number of measurement points, and a lot of labor is required to measure in a short time. Moreover,
When many workers perform measurement, measurement errors may occur due to individual differences, and there is also a safety problem because it is work in a tank.Therefore, work efficiency is high, measurement accuracy is high, and measurement equipment that is automated as much as possible is used. Development was requested.

In order to meet such a demand, various automatic measuring devices have been proposed in recent years.

For example, Japanese Patent Laid-Open No. 3-53105 discloses a tank bottom plate having a drive source, an ultrasonic flaw detector, an ultrasonic probe, a data processor, and a control device mounted on a self-propelled carriage. A measuring device is described. This measuring device is configured to reciprocate the arm that holds the ultrasonic probe while moving the self-propelled carriage along the side wall of the tank. The facing distance between the acoustic probe and the surface of the bottom plate is fixedly determined.

[0006]

By the way, the tank bottom plate has subtle unevenness over the entire surface thereof, and in particular, there is a considerable step at the position where the rectangular plate or the annular plate is welded.

However, in the above-mentioned proposed measuring apparatus, since the facing distance between the ultrasonic probe and the surface of the bottom plate is fixedly set, the height of the ultrasonic probe depends on the unevenness of the bottom surface of the tank. However, it is difficult to send ultrasonic waves perpendicularly to the upper surface of these unevenness while smoothly scanning the upper part of these unevenness, and accurate plate thickness measurement can be performed. There wasn't. In addition, if there is a large undulation on the bottom of the tank, the self-propelled carriage cannot overcome the undulation and measurement becomes impossible, or even if the undulation is overcome, the posture of the self-propelled trolley becomes unstable. There was a possibility of causing a large measurement error. Furthermore, the places where the bottom plate of the tank is most likely to corrode are statistically concentrated in the vicinity of the welding points between the bottom of the side wall of the tank and the bottom plate, but there is also the problem that the probe cannot scan to such places. It was

The object of the present invention is to accurately measure the plate thickness by keeping the ultrasonic probe vertically opposed to the surface of the plate to be measured at a predetermined interval regardless of the unevenness of the surface of the plate to be measured. It is an object of the present invention to provide a plate thickness measuring device capable of performing the above-mentioned method and capable of scanning the corner portion of the plate to be measured such as a welded portion between the lower portion of the tank side wall and the tank bottom plate without any trouble.

[0009]

A plate thickness measuring device of the present invention is a plate thickness measuring device for measuring a plate thickness of a plate to be measured using an ultrasonic probe facing a surface of the plate to be measured, An apparatus base movably mounted on the surface of the plate to be measured,
A slider, the movement of which is controlled along the surface of the plate to be measured by a slide mechanism provided in the device base body, and a scanning carriage which is equipped with the ultrasonic probe and can travel on the surface of the plate to be measured. A connecting mechanism for connecting the scanning carriage to the slider so as to be movable at least in a direction orthogonal to the surface of the plate to be measured.

[0010]

According to the plate thickness measuring apparatus of the present invention, a scanning carriage that is movable at least in a direction orthogonal to the surface of the plate to be measured is connected to a slider whose movement is controlled along the surface of the plate to be measured. Equipped with an ultrasonic probe, by moving the scanning carriage along the undulations of the surface of the plate to be measured, regardless of the unevenness of the surface of the plate to be measured, the ultrasonic probe is always Face the surface vertically with a certain space,
Perform accurate plate thickness measurement.

Moreover, the scanning carriage can be moved to a corner portion of the plate to be measured, such as a welded portion between the lower portion of the tank side wall and the tank bottom plate, and the thickness of the corner portion can be measured. Also possible.

[0012]

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

This embodiment is an application example as a plate thickness measuring device used for automatic inspection of a tank bottom plate, and FIG. 1 is a perspective view of the whole device.

In FIG. 1, reference numerals 1 and 1 denote pedestals that form a device base A by facing each other in parallel.
A slide 2 is fixed and bridged between the central portions of the mounts 1 and 1 so as to be orthogonal to the slides 1. As will be described later, an arm 3 is movably supported on the slide 2 in the arrow X direction, and a slider 24 'described later is movably supported on the arm 3 in the arrow Y direction. There is. A slide mechanism B, which will be described later, is constituted by the slide 2, the arm 3 and the slider 24 '. At the lower part of the slider 24 ', a connecting mechanism C
A scanning mechanism D, which will be described later, is connected via. E is
A control mechanism that is placed on a member 1A that is bridged between the rear ends of the gantry 1 and 1, and is composed of an ultrasonic flaw detector 5, a drive control device 6, a signal processor 7, a computer 8 and the like. Has been done. A water tank 4 filled with water used for measuring the plate thickness is placed on the slide 2.

A first leg portion 9 is provided so as to hang on each of the ends of the pedestals 1 and 1 constituting the apparatus base A, and a fixing pad 10 is provided at the lower end of each leg portion 9. It is equipped. This fixing pad 10 is already known, and when the descending pedal 10A is depressed, the pad 10B is displaced downward and comes into surface contact with the tank bottom surface, whereby the pedestals 1 and 1 are fixed on the tank bottom surface. While meanwhile,
By pressing the rising pedal 10C, the pad 10B
Is displaced upward to separate from the bottom surface of the tank to release the adhesion between the gantry 1, 1 and the bottom surface of the tank. Reference numeral 11 denotes a total of four second leg portions that are provided so as to hang down from the mounts 1 and 1, and a roller 12 that is rotatable in all directions is provided at the lower ends of these four leg portions. The device base A is movable on the bottom surface of the tank by these rollers 12. Moreover, in each of the mounts 1 and 1, the second leg portions 11 and 11 are provided so as to be located between the first leg portions 9 and 9. In this way, the gantry 1, 1, the leg portion 9, the fixing pad 10, the leg portion 1
1, the device base A is composed of the rollers 12.
Reference numerals 13 and 13 denote positioning arms of a predetermined length that are supported inside the respective tip portions of the gantry 1 and 1 and extend in the tip direction of the arm 3. A guide roller 14 which is rotatable around the axis of the direction is attached via a bearing.

FIG. 2 is a perspective view of the slide mechanism B from diagonally below, and the slide 2 is formed in a substantially U-shaped cross section. The end of the slide 2 on the right side in FIG. 2 is connected and fixed to the center of one of the mounts 1 via a reinforcing member (not shown), while the end on the left side in FIG. 22 is provided, and the actuator 21 and the motor 22 are connected and fixed to the central portion of the other pedestal 1 through a reinforcing member (not shown). As a result, the slide 2 is bridged and fixed between the center portions of the gantry 1. A ball screw 23 is connected to the actuator 21 and extends in the longitudinal direction of the slide 2. A slider 24 is screwed onto the ball screw 23. Then, the ball screw 23 is rotated by the driving force of the motor 22 via the actuator 21, so that the slider 24 screwed with the ball screw 23 moves in the longitudinal direction (X-axis direction) of the slide 2.

The central upper surface of the arm 3 is fixed to the bottom surface of the slider 24 via a fixing member 25. Therefore, the arm 3 can move in the X-axis direction together with the slider 24.

The arm 3 has its longitudinal direction (Y-axis direction).
Equipped with a ball screw 23 'extending along
When the ball screw 23 'is rotated by the driving force of the motor 22' via the actuator 21 ', the slider 24' screwed to the ball screw 23 'moves in the Y-axis direction. After all, the slider 24 'can be controlled to move in the X-axis and Y-axis directions.

Next, the connecting mechanism C will be described.

This connecting mechanism C connects between the slider 24 'and the scanning carriage 80 of the scanning mechanism D, and is a bracket 30 fixed to the lower surface of the slider 24' (see FIG. 3).
(See reference), a guide rail 31 having a substantially U-shaped cross section is hung and fixed. An elevating slider 33 is supported in the guide rail 31 via a plurality of sliding balls 32 (see FIG. 4) so that the elevating slider 33 can move up and down. A slider bracket 34 is fixedly mounted on the elevating slider 33, and the bearing box 3 is attached to the lower end of the slider bracket 34.
5 is fixed. As shown in FIG. 4, convex portions 40, 40 are provided on the inner wall of the bearing box 35 so as to project relative to each other, and the bearing holding member 39 is interposed between the convex portions 40, 40 via the bearings 41, 41. Is the axis O1
It is rotatably held around. The axis O1 is
It is an axis line along the X-axis direction described above. The shaft 37 is rotatably held by the bearing holding member 39 via bearings 38, 38 about an axis O2 orthogonal to the axis O1. The shaft 37 is prevented from coming off through a bearing seat 42, a shaft stopper ring 43, and the like, and its tip (left end in FIG. 4) has a recess 36 of a scanning carriage 80 described later.
(See FIG. 4). A vertical stabilizing roller 44, which is in contact with the bottom surface of the tank, is rotatably provided below the bearing box 35.

Therefore, the connecting mechanism C is composed of the slider 2
4'is connected to the scanning carriage 80 so as to be movable up and down and rotatable about axes O1 and O2.

Next, the scanning mechanism D will be described.

In FIG. 5, reference numeral 50 is an already known ultrasonic probe, the upper end of which is connected to the above-mentioned control mechanism E through a cable 51, and the lower end of which is a piezoelectric element or a piezoelectric element. Sound absorbing material is built in. Probe 50
Is inserted into the middle cylinder (probe holding member) 52, and is capped by a cap 53 that is screwed onto the upper outer periphery of the middle cylinder 52.
Held within 2. The lower part of the middle cylinder 52 is the scanning carriage 8.
It is vertically movably fitted in the hollow portion 80A of No. 0. On the left and right sides of the upper surface of the scanning carriage 80, the lower ends of eight spring rods 55 each extending in the vertical direction are fixed. A space between the upper ends of the spring rods 55 is fixed to an annular upper spring receiver 56 which is loosely fitted in the middle cylinder 52 so as to be vertically movable. An annular lower spring receiver 58, which is located outside the middle cylinder 52, is vertically movably fitted to an intermediate portion of each spring rod 55. Further, the lower spring receiver 58 is connected via a connecting pin 57. It is connected to the middle cylinder 52.

A total of eight compression springs (biasing means) 59 are interposed between the upper and lower spring receivers 56 and 58, and the spring rods 55 are passed inside them. Therefore, the middle cylinder 52 is vertically movably guided by each spring rod 55 and is urged downward by each spring 59.

Reference numeral 60 denotes an elastic water supply tube which communicates with the water tank 4 described above, and this tube 60 is connected to the water supply port 52A of the middle cylinder 52. The water supplied into the water supply port 52A passes through the gap between the probe 50 and the middle cylinder 52 and the gap between the middle cylinder 52 and the hollow portion 80A of the scanning carriage 80, and then the probe. It is discharged below 50. In the hollow portion 80A of the scanning carriage 80, a substantially cylindrical gap spacer 61 for keeping a constant gap h between the lower surface of the probe 50 and the bottom surface of the tank is inserted. Since the gap spacer 61 is constantly in contact with the bottom surface of the tank during scanning by the probe 50, its tip is gradually worn. Therefore, in order to keep the gap h constant, between the probe 50 and the shoulder portion 52B of the middle cylinder 52,
An annular gap adjusting shim ring 62 is inserted to finely adjust the gap h. The water discharged below the probe 50 fills the space of the gap spacer 61.

A gap h between the lower surface of the probe 50 and the bottom surface of the tank
The reason for filling the part with water is as follows. That is, from the piezoelectric element of the probe to the surface of the DUT (in this example,
When ultrasonic waves are emitted vertically toward the bottom of the tank,
Part of the light is reflected, and the rest passes through the object to be measured. Their proportions are the sound velocity and the velocity of sound in the object to be measured (for example, steel) and the substance in contact with the surface (for example, air). It depends on its density. Therefore, by filling a liquid medium such as water, oil, or glycerin between the probe and the surface of the object to be measured, ultrasonic waves can easily pass through the object to be measured, improving the measurement accuracy. Will be done. The liquid medium is not limited to water.

Two support shafts 54 projecting outward in the horizontal direction are fixedly mounted on both sides of the scanning carriage 80, and the resin sleeves 7 are provided on the outer periphery of each support shaft 54 as shown in FIG.
4 is fitted, and a roller mounting bracket (rotating body) 71 is mounted on the outer peripheral portion of the support shaft 54 via a bearing 75.
It is fitted so as to be rotatable about the axis O3. Then, the fixing nut 73 is screwed to the tip of the support shaft 54 via a washer and a spacer, and the bracket 7
The bracket 71 is prevented from slipping off by fitting the spring ring 76 to the inner peripheral surface of 1. The bracket 71 has a substantially square shape in a plane, and four shafts 72 projecting inward in the horizontal direction are fixedly provided at respective four corners thereof, and each shaft 72 has its axis O4 as a center. A rotatable traveling roller 70 is attached. The tops 77 at the four corners of each bracket 71 are obliquely cut out as shown in FIGS. 5 and 6.

Next, the operation will be described.

The present measuring apparatus is disassembled into a plurality of parts of, for example, a device base A and respective mechanisms B, C, D and E, and the device base A further includes a plurality of pedestals 1, 1 and legs 9, 11. It is disassembled into parts, loaded into the tank, and easily assembled in the tank with one touch. The control mechanism E is connected to a power source outside the tank via a distributor and a cable (not shown), and the switch of the distributor is turned on to enable the control mechanism E to operate. The computer 8 includes inspection conditions for the tank bottom plate to be inspected, for example, a plate thickness measurement range of the tank bottom plate, scanning conditions of the probe 50, and color classification for each numerical value for displaying the measured plate thickness of the tank bottom plate. Is set in advance.

First, the device base A is manually moved, and as shown in FIG. 7, the guide rollers 14 at the tips of the positioning arms 13, 13 are brought into contact with the tank side wall W, and the device base is fixed by the fixing pad 10. Fix A on the bottom of the tank.

After that, by operating the computer 8, the drive control device 6 operates the motors 22 and 22 'of the slide mechanism B according to preset inspection conditions such as measurement accuracy and scanning speed to perform scanning. The scanning carriage 80 of the mechanism D is controlled to move in the X and Y axis directions.
For example, the control of moving the scanning carriage 80 by 1000 mm in the Y-axis direction and then moving it by 5 mm in the X-axis direction is repeated so as to draw the trajectory shown by the dotted line in FIG. 7, and the scanning carriage 80 is moved by 5 mm in the Y-axis direction. A total of 200 points for each movement is set as a measurement point of the tank bottom plate by the probe 50.

While the scanning carriage 80 is moving, the water supplied from the water tank 4 is discharged into the gap between the probe 50 and the tank bottom plate, and the probe 50 presses ultrasonic waves of, for example, 5 MHz. While transmitting from the electronic toward the tank bottom plate,
Receives the reflected waves from the tank bottom plate. Ultrasonic flaw detector 5
Measures the plate thickness at the measurement point on the tank bottom plate based on the time difference between the time when the ultrasonic wave transmitted from the probe 50 is reflected from the tank bottom plate and returns. The measured value is A / D converted and then input to the computer 8 via the signal processor 7. The computer 8 is provided with a display, and the plate thickness measurement value at the measurement point on the tank bottom plate is displayed on the display screen thereof. By displaying the measured values displayed by color in a predetermined five-color range, for example, the degree of thinning of the tank bottom plate can be displayed in an easy-to-understand manner based on the shade of those colors. Furthermore, when checking the degree of thinning of the tank bottom plate in detail, it is possible to enlarge and display the plate thickness measurement value in that range by performing image processing after specifying the range. In this case, it is possible to more accurately grasp the thinned portion of the tank bottom plate that is equal to or larger than the reference value. Of course, since the measurement data of the plate thickness is stored in the computer 8, the data can be output together with the name of the tank to be measured, the measurement date, etc., if necessary.

By the way, the scanning carriage 80 moves smoothly regardless of the unevenness on the surface of the tank bottom plate, and the probe 5 is moved.
0 is always positioned perpendicular to the surface of the bottom of the tank.

That is, as shown in FIG. 3, the bearing box 35 moves while keeping the vertical stabilizing roller 44 in contact with the tank bottom plate, and moves up and down together with the slider bracket 34 in accordance with the undulation of the surface of the tank bottom plate. . Therefore, the coupling position between the bearing box 35 and the scanning carriage 80 is always maintained at a predetermined height above the surface of the tank bottom plate. Moreover, the scanning carriage 80 has axes O1 and O2 with respect to the bearing box 35 (see FIG. 4).
Since it is rotatably connected about, the posture is changed according to the ups and downs of the surface of the tank bottom plate. As a result, the scanning carriage 80 moves smoothly on the tank bottom plate, and the probe 50 is always positioned vertically to the surface of the tank bottom plate. Furthermore, the probe 50 has a total of 8
Since it is biased downward by the book spring 59, as shown in FIG. 5, the gap spacer 61 maintains a predetermined gap h facing the tank bottom plate.

As a result, the probe 50 always vertically opposes the tank bottom plate at a predetermined distance h, and the scanning range in which the scanning carriage 80 moves (for example, 1000 mm × 10).
This enables accurate plate thickness measurement over the entire area (00 mm).

When the tank bottom plate has a relatively large step such as a welded portion, the roller mounting brackets 71, 71 of the scanning carriage 80 rotate about the axes O3, O3 by the step. However, the traveling roller 70 that rotates while moving in contact with the tank bottom plate, that is, the rolling traveling roller 70 is replaced. As a result, the scanning carriage 80 smoothly rides over the step portion and enables continuous plate thickness measurement. Moreover, since the tops 77 of the roller mounting brackets 71, 71 are scraped off, the tops 77 do not hit the stepped portion.

In this way, the scanning carriage 80 is moved within the scanning range (for example, 1000 mm × 1000 mm) regardless of the steps, unevenness, inclination, distortion, etc. of the welded portion of the tank bottom plate, and within that range. After the plate thickness is measured thoroughly, the fixing pad 10 is released, the apparatus base A is displaced in the circumferential direction along the tank side wall W, and then fixed again. Then, the measurement operation is performed in the same manner as described above, and the scanning range adjacent to the previous scanning range (for example, 1000 mm × 10
The plate thickness of 00 mm) is measured. In that case, it is preferable to partially overlap the scanning range in order to prevent leakage of the measurement points.

Thereafter, the same operation is repeated to measure the plate thickness over the entire circumference of the tank bottom plate.

By contacting the tip of the arm 13 with the tank side wall W, the thickness of the tank bottom plate near the tank side wall W can also be measured. For example, from the tank side wall W to 25
Measurement is impossible within the range of mm. Such a range is separately measured manually, and by supplementing the measurement data, the plate thickness measurement of the entire tank bottom plate is completed.

After the measurement work is completed, the measurement device is disassembled into a plurality of parts and carried out of the tank.

As a matter of course, the scanning range per scanning is not limited to 1000 mm × 1000 mm in the above embodiment, and the measurement points are not limited to 5 mm intervals, and may be arbitrary, depending on the width of the plate to be measured. It can be changed appropriately.

[0042]

As described above, according to the plate thickness measuring apparatus of the present invention, the slider, which is controlled to move along the surface of the plate to be measured, is capable of scanning at least in the direction orthogonal to the surface of the plate to be measured. Since the carriage is connected and the scanning carriage is provided with the ultrasonic probe, the scanning carriage can be moved along the undulations of the surface of the plate to be measured, and as a result, the surface of the plate to be measured can be moved. Regardless of the unevenness, the ultrasonic probe is always vertically opposed to the surface of the plate to be measured with a predetermined interval,
Accurate plate thickness measurement can be performed. Moreover, the scanning carriage can be moved to a corner portion of the plate to be measured, such as a welded portion between the lower side wall of the tank and the tank bottom plate, and it is possible to measure the plate thickness at such a corner portion. can do.

[Brief description of drawings]

FIG. 1 is a perspective view of the entire apparatus showing an embodiment of the present invention.

FIG. 2 is a perspective view of a slide mechanism portion shown in FIG.

3 is a side view of a scanning mechanism portion shown in FIG. 1. FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 is a cross-sectional view taken along the line VV of FIG.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is a plan view for explaining the operation of the scanning mechanism shown in FIG.

[Explanation of symbols]

 A Device Base B Sliding Mechanism C Coupling Mechanism D Scanning Mechanism E Control Mechanism 24 'Slider 50 Probe 52 Middle Cylinder (Probe Holding Body) 59 Spring (Biasing Means) 70 Traveling Roller 71 Roller Mounting Bracket (Rotating Body) ) 80 scanning carts

Claims (2)

[Claims] 1. A plate thickness measuring device for measuring the plate thickness of a plate to be measured using an ultrasonic probe facing the surface of the plate to be measured, wherein the plate is movably mounted on the surface of the plate to be measured. And a slider whose movement is controlled along the surface of the plate to be measured by a slide mechanism provided in the device base, and an ultrasonic probe on the surface of the plate to be measured. A plate thickness measuring device, comprising: a freely movable scanning carriage; and a connecting mechanism that connects the scanning carriage to the slider so as to be movable at least in a direction orthogonal to the surface of the plate to be measured. 2. The scanning carriage comprises a pair of left and right rotating bodies which are rotatably supported about an axis extending along the surface of the plate to be measured, and portions which are displaced in the respective rotating directions of the pair of left and right rotating bodies. A plurality of running rollers that are rotatably held on the surface of the plate to be measured and that are movable in the direction of contact with and away from the surface of the plate to be measured, holding the ultrasonic probe. 2. The plate thickness measuring device according to claim 1, further comprising: a probe holder and a biasing unit that presses the probe holder against the surface of the plate to be measured.