JPH0146024B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating probe type ultrasonic flaw detector for inspected materials such as pipes and round bars, and particularly for inspected materials whose axial center position changes in the axial direction. This invention relates to a rotary probe holder that can follow and rotate.

In general, in order to perform ultrasonic flaw detection on long rolled products with a circular cross section such as pipes and round bars, the probe is rotated at high speed along the outer circumference of the material to be inspected while moving the material to be inspected in the axial direction. A so-called rotary probe type flaw detector is often used, which moves straight ahead and performs spiral probe scanning around the outer periphery of the material to be inspected to detect flaws over the entire length of the entire surface.

This type of ultrasonic flaw detection equipment rotates a rotary probe holder equipped with multi-channel probes at high speed, so the flaw detection speed is fast and inspection can be performed with extremely high efficiency, making it suitable for use in steel pipe manufacturing factories, steel bar manufacturing factories, etc. It is used as an important non-destructive testing device.

Although this flaw detection device is suitable for highly efficient flaw detection, if the straightness of the inspected material is poor, problems such as those described below may occur, making flaw detection unstable or making flaw detection impossible. Conventionally, there was a drawback that strict limits were placed on the straightness of the material to be inspected, and it had to be used within the limits. Next, I will discuss these.

Figure 1 is a schematic diagram showing the entirety of a general rotating probe type ultrasonic flaw detector. A two-stage pinch roll stand on the input side and a two-stage pinch roll stand 4 on the output side are assembled on a common base 5. The material to be inspected 6 passes through the main body 1 and is transported in the direction of the arrow in the figure while its movement is restricted by the pinch roll stands 3 and 4 on the entry and exit sides.

FIG. 2 is an explanatory axial cross-sectional view of the conventional probe rotating type ultrasonic flaw detector main body 1, in which the inspected material 6 is supported by a rotor 12 supported by bearings 15a and 15b in a box 11 of the main body, and It passes through a rotating probe holder 14 attached to the end face 13 of the rotor and is transferred in the direction of the arrow. Further, the rotor 12 is connected to an external drive source by a timing belt 17 and a timing pulley 16 that meshes with the timing belt 17, and is rotationally driven. Note that the cylindrical portion of the rotor 12 is generally provided with a slip ring or other elements for signal transmission. In addition, even if the fixed guide 18 inserted deeply into the hole inside the rotor 12 swings due to the bending of the material 6 to be inspected entering, the fixed guide 18 remains in the taper guides 18a and 18b provided on the entry side and the exit side. Therefore, the inspection object 6 is forcibly guided and stably introduced into the inner hole of the rotary probe holder 14.

On the other hand, the rotating probe holder 14 has a required number of probes 20, a spout 19, and a water channel 21, and is fixed at all times through a tapered surface 22 and pressed against the tapered surface 22 by a spring (not shown). supply child 2
The rotary probe holder 14 has a means for supplying water as a couplant from the outer surface of the material to be inspected 6 and the rotating probe holder 14.
Water, which is a couplant, is always supplied so as to fill the gap 24 between the inner surface of the substrate and the inner surface of the substrate.

FIG. 3 is a diagram illustrating the relationship between the positions and functions of the rotating probe holder 14 and the inspected material 6.
B shows a case where the rotary probe holder 14 and the inspected material 6 are concentric, and B shows a case where they are eccentric by a distance d. In the case of concentricity, the air gap 24 is uniform along the entire circumference;
The couplant water is sheared uniformly and the flow state is stable, but if it is eccentric, the gap 24 is not uniform, and the circumferential flow of water due to the high speed rotation of the rotary probe holder 14 is It becomes unstable, and water tends to stick to the inner wall surface of the rotating probe holder due to centrifugal force, so if the amount of eccentricity is large, air will be drawn into the largest gap, making flaw detection impossible.

On the other hand, for example, in the case of oblique flaw detection of steel pipes, the ultrasonic beam emitted from the probe 20 attached to the rotating probe holder 14 as shown in the figure is transmitted to the water column 25.
However, if the rotating probe holder 14 and the inspected material 6 are concentric, the refraction angle is uniform regardless of the rotational position, and ideal flaw detection can be performed. On the other hand, in the case of eccentricity, the refraction angle changes depending on the rotational position as the rotary probe holder 14 rotates.

In this case, according to a flaw detection experiment using a groove-shaped artificial defect provided in the axial direction of the inspected material, the amount of eccentricity is
In the case of 1.5% of the outer diameter of the material to be inspected, a variation in defect echo height of approximately 3 dB is observed, and in normal flaw detection, it is necessary to suppress the variation in echo height for the same defect to approximately 3 dB, so the amount of eccentricity is 1.5 of the outer diameter of the test material
It can be seen that the permissible limit should be about %.

Such a rotating probe holder 14 and the material to be inspected 6
Due to the permissible limit of eccentricity of Measures are taken to ensure concentricity as far as possible, and as shown in FIG. 1, pinch roll stands 3, 4 and
When assembling the main body 1 to improve vertical and horizontal centering accuracy, or when the inspected material 6 has a small diameter and thin wall and can be elastically bent by external force, the inner diameter of the fixed guides 18a and 18b shown in FIG. By narrowing down the
That is, by making the gap 24 as small as possible, a means is implemented to increase the concentricity between the rotary probe holder 14 and the material to be inspected 6.

In addition, if the material 6 to be inspected has a large diameter and thick wall and cannot be bent by external force, the main body 1 can be floatingly supported on the elevating frame 2 using springs or cushioning rubber seats 7 as shown in FIG. Then, the tapered guides 18a, 18 of the fixed guide 18 in FIG.
The concept of making the main body 1 follow the pattern through the b is implemented, but in addition to the large mass of the main body 1, the rotor 12 also has a large rotational inertial mass, and when it makes an angular displacement due to the action of a kind of gyroscope, Since a large moving force is generated, it is not only difficult to carry out in practice, but also when the bending is large, the inspected material 6 gets caught in the taper guides 18a and 18b and cannot be transported, making it impossible to extract it let alone detect the flaw. There are also cases where it disappears.

From the above point of view, conventionally, it has been common practice to inspect only the straightest possible materials 6 to be inspected, and to inspect bent materials upstream of transportation for bends and to push them out. However, due to the manufacturing process of steel pipes,
Although there is relatively little bending, round steel bars generally have larger bends than steel pipes, and straightening them will only increase costs and have no value in terms of quality, so they are not straightened. There aren't many. In this sense, there are currently fewer examples of application of rotary probe type flaw detectors to round steel bars than to steel pipes.

The present invention was made in order to solve the above-mentioned problems.The rotating probe holder attached to the rotor of a flaw detector has a double cylindrical structure of an outer cylinder and an inner cylinder, and the rotating probe holder is attached to the rotor of a flaw detector. Even if the axial center position changes, the inner cylinder with a small mass is made to follow the inspected material. Therefore, it is not necessary to make the main body 1 of the probe rotation type ultrasonic flaw detector follow the entire body using the taper guides 18a and 18b as described above. At this time, the major difficulty is that when the next material to be inspected enters the flaw detector, if the inner cylinder is not held concentrically due to the eccentricity of the material to be inspected, as mentioned above, there is a risk of a major hindrance to its entry. It is a certain thing. However, the present invention uses the buoyancy force generated in the inner cylinder against the centrifugal force generated due to the high speed rotation of the inner cylinder when the inspected material passes after the inspection and the next inspected material enters. By holding the inner cylinder concentrically, the next material to be inspected can enter, thereby solving the above problem. The invention will be explained in detail below with reference to the figures.

FIG. 4 is an explanatory axial cross-sectional view of the main body of a rotating probe type ultrasonic flaw detector equipped with the rotating probe holder of the present invention, and FIG. 5 is an enlarged sectional view of the rotating probe holder of the present invention. 6 is a sectional view taken along the line V-V in FIG. 5, and FIG. 7 is an exploded perspective view of the probe mounting spacer mounting hole. In the explanation, the parts having the same reference numerals as those explained before FIG. 3 have the same names and the same parts, so the explanation will be omitted.

In FIG. 4, the rotating probe holder attached to the end face 13 of the rotor 12 has a double cylindrical structure. That is, there is an inner cylinder 32 inside the outer cylinder 31, the outer cylinder 31 is attached to the end face 13 of the rotor 12, and the entrance and exit sides of the inner cylinder 32 are connected to the outer cylinder by bellows 33 and 34, respectively. 31. Since the bellows 33 and 34 are flexible, the inner cylinder 32 can be eccentric with respect to the outer cylinder 31, and the rotation of the outer cylinder 31 can be transmitted to the inner cylinder 32. In addition, when using a bellows as shown in this figure, make sure that the inner cylinder 32 is not pulled toward the exit side due to contact with the inner surface of the inner cylinder 32 of the inspected material 6, and the bellows is not excessively deformed in the axial direction. A protrusion 35 is provided on the inner surface of the outer cylinder 31, and a protrusion 3 is provided on the outer surface of the inner cylinder 32.
By providing at least one of the protrusions 6 around the entire circumference, it is necessary to bring the protrusions into contact with each other to form an axial stopper. On the entrance side of the inner cylinder 32, there is provided a lapper guide 32a with an inner conical surface for guiding the tip when the inspected material 6 enters.

Also, as explained in FIG. It is led into a waterway space 21' created by the outer wall and bellows 33,34. That is, as shown in FIG. 6 and FIG.
Protrusion 39 of mounting spacer 39 for mounting 0
A sector-shaped space 4 formed between a and the mounting hole 41
0 through the gap 2 between the inner cylinder 32 and the material to be inspected 6
4, filling the void 24 with couplant water. This couplant water allows the ultrasonic beam emitted from the probe 20 to be incident on the inspected material 6, and the reflected echo can be received by the probe.

In the rotating probe holder 14 with the double cylindrical structure described above, as shown in FIG. It is necessary to install a plurality of probes in the same cross section and to arrange them so that the centrifugal force exerted on the inner cylinder by these probes is balanced. Note that when the material to be inspected enters the probe holder, it is necessary for the inner tube 32 to be rotated concentrically with respect to the outer tube 31 in order for the material to be inspected to enter smoothly. In order to maintain this concentric state, the mass of the inner cylinder is made smaller than the mass of water that is displaced by the total volume of the inner cylinder. It can be held concentrically using buoyancy. The center return function can be improved as the mass of the inner cylinder is made smaller than the mass of water removed by the total volume of the inner cylinder. Furthermore, a center return function using an elastic body may be used in conjunction with the inner cylinder relative to the outer cylinder.

As described above, according to the present invention, even if the material to be inspected 6 is eccentric, the inner tube 32 to which the probe 20 is mounted follows the eccentricity of the material to be inspected 6, and the inner tube 32 follows the eccentricity of the material to be inspected 6. 32 can be rotated at high speed,
The inspected material 6 completes the inspection and passes through, and the next inspected material enters without any hindrance and the probe 20 can be held at an ideal relative position with respect to this inspected material for rotational flaw detection. . Therefore, even when inspecting thick materials with large diameters and large bends, this is a versatile probe for rotating ultrasonic flaw detectors that can detect flaws at high speed and high efficiency without being restricted by the bends. A holder can be provided.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the overall appearance of a rotating probe type ultrasonic flaw detector, Fig. 2 is an explanatory axial cross-sectional view of a conventional rotating probe holder, and Fig. 3 is an explanatory diagram of a conventional rotating probe holder. 4 is an explanatory axial cross-sectional view of an embodiment of the probe holder for a rotating probe type ultrasonic flaw detector of the present invention, and FIG. 5 is a diagram showing the relationship with the inspected material. An enlarged sectional view of the rotating probe holder, Figure 6 is Figure 5V
-V sectional view, and FIG. 7 is an exploded perspective view of the probe, spacer, and mounting hole portion. DESCRIPTION OF SYMBOLS 1...Main body, 6...Test material, 12...Rotor, 14...Rotating probe holder, 19...Ejection port, 20...Probe, 22...Tapered surface, 24...
...Gap, 31...Outer cylinder, 32...Inner cylinder, 33,3
4...Bellows, 35, 36...Protrusion, 39...
mounting spacer.

Claims (1)

[Claims] 1. In a rotating probe holder attached to a probe rotating type flaw detector, the structure of the rotating probe holder is a double cylinder consisting of an outer cylinder and an inner cylinder that are attached to the rotor of the flaw detector and rotate. , connected to the entrance and exit sides of the material to be inspected that is being transferred in the axial direction by bellows surrounding the material to be inspected so that the inner tube is in a floating state with respect to the outer tube, and Contact between the probe attached to the inner cylinder and the inspected material is made by ejecting water filled in the gap formed by the inner wall, the outer wall of the inner cylinder, and the bellows from the inner cylinder. In addition to making it possible to transmit and receive ultrasonic waves as medium water, the mass of the inner cylinder is made smaller than the mass of water that the total volume of the inner cylinder excludes, and the inner cylinder resists the centrifugal force accompanying high-speed rotation. A probe holder for a probe rotating type ultrasonic flaw detector, characterized in that a centering force is applied to the cylinder.