JPS6332140B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a probe rotating type ultrasonic flaw detector that can detect flaws by following the inspected material even if the position of the inspected material changes.

In order to perform ultrasonic flaw detection on long rolled products with a circular cross section, such as pipes or round bars, the probe is rotated at high speed along the outer circumference of the material to be inspected, and the material to be inspected is moved straight in the axial direction. A so-called rotating probe type ultrasonic flaw detector, which detects flaws over the entire length of the entire surface by scanning a spiral probe around the outer periphery of the material to be inspected, is often used in steel rolling mills. 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. It is used as an important non-destructive testing device in factories and other places.

In this way, this flaw detection device is suitable for high-efficiency flaw detection, but on the other hand, if the straightness of the inspected material is poor, problems such as those described later may occur, and flaw detection may become unstable or flaw detection may not be possible. In the past, the actual situation was to set strict limits on the straightness of the inspected material and use it within the limits.

The relationship between the rotating probe type flaw detector and the straightness of the tested material will be explained in detail below. FIG. 1 is a diagram showing the appearance of a conventional rotating probe type ultrasonic flaw detector, in which a main body 1 of the rotating probe type ultrasonic flaw detector is mounted on an elevating pedestal 2. As shown in FIG. 3 is a two-stage pinch roll stand on the input side of the material to be inspected, and 4 is a two-stage pinch roll stand on the exit side, and these are assembled on a common base 5. 6 is the material to be inspected, which passes through the probe rotating type ultrasonic flaw detector main body 1, and whose movement during transportation is restricted by the input pinch roll stand 3 and the output pinch roll stand 4, as shown by the arrows in the figure. transported in the direction of In this state, although not shown, a rotary probe holder built into the rotary probe type flaw detector main body 1 rotates around the outer periphery of the material to be inspected at high speed to perform flaw detection. FIG. 2 is a diagram schematically explaining the rotating probe holder section, in which the inspected material 6 passes through the rotor 102 and the rotating probe holder 104 attached to the end surface of the rotor 102 in the direction of the arrow. transported. At this time, the rotor 102 is rotated at high speed by a motor (not shown) or other appropriate drive source, and therefore the rotary probe holder 104 is also rotated at high speed. This rotating probe holder 104 has a cylindrical shape,
A required number of ultrasonic probes are attached to key points of this cylindrical body. 101 is an outer case of the rotor 102, and both ends of the rotor 102 are supported by the outer case using rolling bearings or other appropriate bearing elements.

Figure 3 shows the rotor 102 and rotating probe holder 10.
4 is a schematic cross-sectional view including the axis of rotor 10.
2 has rolling bearings 105A and 105B near both ends.
It is connected to an external drive source and rotationally driven by a timing belt 107 and a timing pulley 106 that meshes with the timing belt 107. Note that the rotor 102
A signal transmission element using a slip ring and a brush (not shown), an element for electromagnetically transmitting a signal without contact, or a signal transmission element of any other suitable method is arranged in the cylindrical portion of the cylinder. Reference numeral 108 denotes a fixed guide that is deeply inserted into the hole inside the rotor 102, so that even if the material to be inspected entering the material is swaying, it will remain on the entrance side.
The material to be inspected is guided by tapered guides 109A and 109B provided on the exit side of the rotary probe holder 104.
Stable introduction into the inner hole of the

On the other hand, the rotary probe holder 104 has a separate means for supplying couplant water to the rotary probe holder 104 (not shown), so that there is The void 110 is always filled with water.

FIG. 4A and FIG. 4B show the rotating probe holder 10.
4 and the inspected material 6. FIG. 4A shows the case where the rotary probe holder 104 and the inspected material 6 are concentric, and FIG. 4B shows the case where they are eccentric by a distance d. show. In the concentric case, the void 110 is uniform along the entire circumference and the couplant water is sheared uniformly;
The flow state is stable, but in the case of eccentricity, the gap 1
10 is not uniform, and the flow of water in the same direction as the rotating probe holder 104 rotates at high speed becomes unstable, and in particular, water tends to stick to the inner wall of the rotating probe holder 104 due to centrifugal force. If the amount of eccentricity is large, air bubbles will be drawn into the area of the largest gap, making flaw detection impossible. On the other hand, in the case of oblique flaw detection of steel pipes, for example, the ultrasonic beam emitted from the probe 111 attached to the rotating probe holder 104 is transmitted to the water column 11.
2 from the surface of the material to be inspected 6. However, if the rotating probe holder 104 and the material to be inspected 6 are concentric, the refraction angle is uniform regardless of the rotational position, allowing ideal flaw detection. . On the other hand, in the case of eccentricity,
The refraction angle varies depending on the rotational position. In this case, according to a flaw detection experiment using a groove-shaped artificial defect provided in the axial direction of the material to be inspected 6, the amount of eccentricity is equal to the outer diameter of the material to be inspected.
A defect echo height variation of approximately 3 dB was observed at 1.5%.
In normal flaw detection, it is necessary to suppress the variation in echo height for the same defect to about 3 dB, so it can be seen that the allowable limit for eccentricity should be about 1.5% of the material being inspected.

Due to the relationship between the allowable eccentricity of the rotating probe holder 104 and the inspected material 6, as shown in FIG.
A means is provided to not only restrict the movement of the inspected material 6 due to conveyance vibration by holding the exit side with a pinch roll, but also to ensure concentricity as much as possible. Assembling the main body of the rotating probe type flaw detector to improve vertical and horizontal centering accuracy, or when the material to be inspected 6 has a small diameter and thin wall.
If it can be elastically bent by an external force, the guides 109A, 1 on the entry and exit sides of the fixed guide shown in FIG.
Measures have been taken to increase the concentricity between the rotary probe holder 104 and the material to be inspected 6 by narrowing the inner diameter of the rotary probe holder 104, that is, by making the gap between the rotary probe holder 104 and the material to be inspected as small as possible.

If the material to be inspected 6 has a large diameter and thick wall and cannot be bent by external force, the legs 7A to 7D for attaching the rotary contact type flaw detector main body 1 to the lifting frame 2 shown in FIG.
(In the case of 4 installation legs) The probe is rotated via fixed guides 109A and 109B to the object to be inspected 6 by attaching it via a springy member such as a disc spring or a rubber limited pedestal. There is an idea that the main body 1 of the mold flaw detector is imitated, but since the rotating part has a large inertia factor and rotates at high speed, the rotating part as a whole acts as a type of gyroscope.
Such an idea is difficult to implement in practice since it creates a large perturbing couple when re-deflecting.

From the above points, as stated at the beginning, it is recommended that the inspected material 6 be inspected only if it is as straight as possible.
Normally, bent materials are subjected to processing such as detecting bends and popping them out upstream of the conveyance.

However, although steel pipes have relatively little bending due to the manufacturing process, round bars generally have more bends than steel pipes, and even if they are straightened and straightened, this will only increase the product cost and may have nothing to do with product quality. In general, round steel bars are not straightened into straight materials for flaw detection, and in this sense, there are far fewer examples of application of rotating probe type flaw detectors to round steel bars than to steel pipes. This is the current situation.

The present invention has been made in order to solve the above-mentioned problems, and even if the position of the probe rotating type flaw detector changes due to bending of the inspected material, the main body of the probe rotating type flaw detector can be inspected without causing gyroscope vibration. The object of the present invention is to provide a rotating probe type ultrasonic flaw detector that follows a material.

Next, the present invention will be explained with reference to the drawings.

FIG. 5 is a perspective view showing an embodiment of the rotating probe type flaw detector of the present invention. Furthermore, a cross-sectional structure mainly including the guide member and rotor portion is shown in FIG.

First, in FIG. 6, the guide member 108, which has a ratchet-shaped guide part 108A on the entry side and a constricted part 108B with an inner diameter slightly larger than the outer diameter of the material to be inspected 6 on the exit side, enters from the guide entry side. The material to be inspected 6 is guided. The outlet side of the guide has a constricted portion 108B whose inner diameter is larger, for example, by about 2% to 3% than the outer diameter of the material to be inspected, and the incoming material to be inspected is brought into contact with this portion. Furthermore, the aperture part 1
The inner diameter of the guide 108 reaching 08B has a gentle slope. On the other hand, the rotor section 200 is the rotor 10
2. Rolling bearings 105A and 105B, coil disk 201 of signal transmission element, and rotating probe holder 10
4, the rotor 102 has rolling bearings 105A,
105B and supported by the support frame 202. Elements for signal transmission (in this embodiment, a coil disk 2015 channel for electromagnetic coupling of an electromagnetic contact type is used) are arranged on the outer periphery of the rotor 102 between the rolling bearings 105A and 105B. be. A timing pulley 106 is provided at one end of the rotor 102 to connect it to an external drive source.
2 to rotate. Note that the rotating probe holder 10
4 has a configuration similar to that of FIG.

Next, in FIG. 5, the above rotor section 200
is suspended by a link member 203 and a link member 204 extending upward from the support frame 202, and the link member 204 is held by a fixing member 205. Fixed member 205 and link member 2
04 and link member 204 and link member 203
They are connected by rotatable pin joints 206 and 207, giving them the degrees of freedom indicated by arrows a and b. Note that the link member 204 has a coil spring 20 that engages with a hanging tool 208 provided near its free end.
9 to balance the moment around the pin joint 206 of each link member, rotor section 200, etc. Furthermore, the support frame 202 is equipped with coil springs 210 and 211 on the left and right sides to balance it in the left and right direction. With the above configuration, the rotor section 200 of the rotating probe type flaw detector is held at a spatially balanced equilibrium position. Furthermore, it has a motor 212 for rotationally driving the rotor, and the rotation is transmitted to the timing pulley 106 of the rotor by timing pulleys 215 and 216 via a timing pulley 213 attached to a motor shaft and idle timing pulleys 214A and 214B. The timing pulley 213 is an extension of the rotation axis of the pin joint 206, and the idle timing pulley 214A,
The rotational axes 214B are made to coincide with the extension of the rotational axis of the pin joint 207 so that the distance between the respective axes does not change even if the rotor section 200 of the rotating probe type flaw detector is spatially displaced.

Next, the operation of the rotating probe type ultrasonic flaw detector having the above configuration will be explained with reference to FIGS. 5 and 6.

The height of the rotor section 200 is adjusted by the handle 218 of the height adjustment mechanism 217 in accordance with the height of the conveyance line for the inspected material 6. When the material to be inspected 6 enters in this state, even if there is a slight difference between the axis of the material to be inspected 6 and the axis of the rotor section 200 of the rotor section 200 of the rotary probe-like The material 6 is automatically aligned as it enters, and the material 6 to be inspected passes through the rotor section 200. Even if the inspected material 6 is curved, the rotor section 200 can be displaced vertically and horizontally according to the curve. That is, the pin joint 20 of the link members 203, 204
The two degrees of freedom a given by 6,207,
b allows the rotor section 200 to be spatially displaced in parallel vertically and horizontally. At this time, the constricted part 1 of the guide is
08B is positioned as close to the rotating probe holder 104 as possible, and is further absorbed by the gap between the outer diameter of the inspected material 6 and the inner diameter of the probe holder 104.

As described above, in the rotating probe type ultrasonic flaw detector of the present invention, the axial direction of the rotating rotor is always spatially displaced in parallel in a constant direction, so it is There is no occurrence of a gyroscope perturbation couple, so tracking is performed smoothly, and no excessive load is applied to the rolling bearing.

In addition, when changing the outer diameter of the material to be inspected, by preparing a guide and a rotary probe holder according to the outer diameter and replacing them, setup changes can be made easily and in a short time.

In the above structure description, we have shown a structure in which coil springs are suspended in three directions to spatially balance the rotor part of the rotating probe type flaw detector, but in order to avoid excessive resonance when starting and stopping rotation, It is desirable to arrange a damper in parallel with the coil spring.

In addition, in the above embodiment, a configuration is shown in which spatial freedom is provided by the swinging motion of each of the link members 203 and 204, but one of the link members is guided in the horizontal direction and the other in the vertical direction. By combining these, it is possible to provide spatial freedom in the same way as described above.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the appearance of a conventional rotating probe type flaw detector, Figure 2 is a diagram showing the main parts of a rotating probe holder, and Figure 3 is an axial cross-sectional view of the rotating probe type flaw detector. Fourth
Figures A and B are diagrams explaining the relative relationship between the probe holder and the material to be inspected, Figure 5 is a perspective view showing an embodiment of the rotary flaw detector of the present invention, and Figure 6 is a guide member and rotor section. A sectional view of the main parts is shown. 6... Material to be inspected, 102... Rotor, 108... Guide member, 200... Rotor section, 203 and 204...
Link members, 206 and 207... pin joints, 209, 210 and 211... coil springs.

Claims (1)

[Scope of Claims] 1. A rotating probe type ultrasonic flaw detector, comprising: a guide member that guides the entry of a material to be inspected and has a constricted portion with an inner diameter slightly larger than the outer diameter of the material to be inspected; and a rotating probe. a support frame that supports a holder and a rotor portion including a rotationally driven rotor and the guide member; a first link member extending upward from the support frame; a second link member connected to the first link member, the other end of which is pivoted via a rotatable pin joint to the fixed member; The pin joint is engaged with the pin joint to balance the moment around the pin joint, and the support frame is suspended from side to side by springs to balance the support frame and give spatial freedom to the support frame. The rotating probe type ultrasonic flaw detector is characterized in that the rotor part is adapted to receive such positional fluctuations through contact with the guide member and to be spatially displaced while its rotation axis always maintains a constant direction. .