JPH0254901B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a probe rotation type ultrasonic flaw detection device used for flaw detection of test materials having a circular cross section such as pipes and round bars, and in particular, The present invention relates to a flaw detection device that includes a probe holder that rotates to follow the change in the axial center position of a specimen being transported in the axial direction.

[Prior art]

Generally, 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 tested while moving the material to be tested in the axial direction. A so-called rotary probe type flaw detection device is often used, which detects flaws over the entire length of the surface by scanning the probe in a spiral around the outer periphery of the test material.

This type of ultrasonic flaw detection device is equipped with a large number of probes to perform multi-strip spiral scanning, and the probe holder is rotated at high speed, so the flaw detection speed is fast and inspection can be performed with extremely high efficiency. Therefore, this flaw detection device is used as an important nondestructive testing device in various steel pipe manufacturing plants, steel bar manufacturing plants, and the like.

Although this conventional probe rotating type ultrasonic flaw detection device can perform inspection with high efficiency, it has various drawbacks. Therefore, the configuration of a conventional flaw detection device will be explained with reference to the drawings, and its drawbacks will be pointed out.

FIG. 1 shows an outline of a conventional rotating probe type ultrasonic flaw detection device. In the figure, the conventional flaw detection device is equipped with a rotating part main body 1 mounted on an elevation adjustment frame 2, and pinch roll stands 3 and 4 provided on the entrance and exit sides of the specimen, respectively, and these are mounted on a common base. It is assembled and configured on 5. The test material 6 passes through the main body 1, and its movement is controlled by the pinch roll stands 3 and 4 on the entry and exit sides.
It is transported in the direction of the arrow in the figure.

As shown in FIG. 2, the rotating section main body 1 includes a rotor 12 rotatably supported within a housing 11 by bearings 15a and 15b, and an end surface 1 of the rotor 12.
The test material 6 passes through the rotor 12 and the rotary probe holder 14 and is transferred in the direction of the arrow.

The rotor 12 is rotated by a timing belt 17 and a timing pulley 16 that meshes with the timing belt 17 in conjunction with a drive source (not shown). Further, a cylindrical fixed guide 18 is inserted inside the rotor 12. The fixed guide 18 is provided with tapers 18a and 18b inside the openings on the entry side and the exit side,
Even if the tip of the incoming test material 6 is slightly swayed, the tapers 18a and 18b forcefully guide the test material 6 and stabilize it in the inner hole of the rotary probe holder 14. It acts to introduce it. In addition,
The cylindrical outer circumference of the rotor 12 has a slip ring.
A signal transmission device (not shown) such as a brush or a rotary transformer is provided.

The rotary probe holder 14 is configured as shown in FIGS. 3 and 4, for example. This rotary probe holder 14 has a hole in the center for passing the test material 6, and a plurality of probes 20 are mounted around this hole, corresponding to each probe 20. do,
A spout 19 and a water channel 21 are formed. Further, as shown in FIG. 2, this probe holder 14 is provided with a fixed water supply ring 23, and this water supply ring 23 and the conical surface 22 at the end of the rotating probe holder are brought into sliding contact. Then, water as a couplant (hereinafter simply referred to as water) is supplied through this sliding contact surface.
By this water supply, the gap 24 between the outer surface of the test material 6 and the inner surface of the rotary probe holder 14 is filled with water, thereby obtaining acoustic coupling.

As mentioned above, in the conventional rotating probe type ultrasonic flaw detection device, if the straightness of the test material 6 is good,
When the specimen 6 enters the rotating part main body 1, the tapered guides 18a, 18 on the entrance side and exit side of the fixed guide 18
The test material 6 is guided by b and passed through the inner hole of the rotary probe holder 14 while being held concentrically therewith.

However, in this conventional probe rotating type ultrasonic flaw detection device, the center of the conveyance path and the axis of the rotating part main body 1 of the flaw detection device, including the input and exit side pinch roll stands, do not match well. However, if the material 6 to be inspected is bent, the following disadvantages arise in terms of flaw detection or maintenance of machine accuracy.

That is, even if the test material 6 is guided by the entrance and exit tapered guides 18a and 18b of the fixed guide 18, it will penetrate the inner hole of the rotary probe holder 14 in an eccentric state. In this case, the test material 6 is placed on the surface of the inner hole of the rotating probe holder 14 that is rotating at high speed.
There is a risk that the tip of the rotor 12 and the rotary probe holder 14 may be damaged due to collision.

On the other hand, in order to prevent damage, it is conceivable to increase the diameter of the inner hole of the rotary probe holder 14 to enlarge the gap 24 with the test material 6. However, in order to ensure good acoustic coupling as a condition for flaw detection, the gap 24 between the test material 6 and the inner hole of the rotary probe holder 14 must correspond to the outer diameter of the test material 6. It is necessary to set it to a minute value that can be determined by in particular,
It is desirable that the internal diameter of the rotary probe holder 14 has a gap of approximately 1.02D ₀ with respect to the nominal outer diameter D ₀ of the material 6 to be inspected. This causes air bubbles to be drawn in, making flaw detection impossible.

As mentioned above, with conventional flaw detection equipment, there is a requirement to make the air gap larger to prevent mechanical damage, and a smaller air gap to ensure acoustic coupling, and it is not possible to achieve both. There is a problem.

By the way, in order to prevent mechanical damage to the probe holder, as shown in Japanese Utility Model Application No. 56-66863, a nozzle block is fitted into the cavity inside the probe holder to prevent the probe holder from being damaged. A structure has been proposed that has a multi-tube structure and allows the easily damaged part (nozzle block) to be replaced. However, this only allows the inner hole of the conventional rotary probe holder, which is easily damaged, to be easily replaced in the event of damage.
This cannot be said to essentially solve the above-mentioned drawbacks.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and is designed to be able to follow the object even if the object to be examined, especially its tip, enters the rotating probe holder somewhat eccentrically or at an angle. , reduce damage to the rotating probe holder due to collision or contact with the test material, and maintain good acoustic coupling by setting the inner hole of the rotating probe holder to minimize the gap between the test material and the test material. The purpose of the present invention is to provide a rotating probe type ultrasonic flaw detection device that can perform the following steps.

[Structure of the invention]

In order to achieve the above object, the present invention attaches a plurality of probes to a rotary probe holder that is connected to a rotating part rotor and rotates, and places the plurality of probes around the outer periphery of a specimen moving straight. In a rotating probe type ultrasonic flaw detection device that rotates at high speed and performs full-length flaw detection over the entire surface, (a) the above-mentioned rotating probe holder includes an outer cylinder that is attached to a rotor of a rotating part and rotates; (b) A plurality of probes are arranged in the outer cylinder, and a plurality of probes are arranged in the corresponding position of the inner cylinder. (c) the inner cylinder has a mass that is greater than the mass of the medium excluded by the space partitioned by the inner cylinder in the outer cylinder; (d) The outer cylinder and the inner cylinder are characterized in that the space between them is watertightly sealed at both ends with the inner cylinder movable in the radial direction, and connected to an elastic member. shall be.

In the present invention, as shown in component a above, the rotating probe holder has a double structure of an outer cylinder and an inner cylinder, thereby making it possible to realize other components b, c, and d. By arranging the probe on the outer cylinder side and providing a jet nozzle in the inner cylinder (constituent requirement b), the outer diameter of the inner cylinder can be reduced and the mass can be reduced. This facilitates displacement in the half mold direction within the cylinder. That is, since the eccentricity of the test material is absorbed by the radial displacement of the inner cylinder, the inner diameter of the inner cylinder can be set to within about 2% of the outer diameter of the test material. Moreover, since the medium is injected into the inner cylinder from the ejection port through the space between the outer cylinder and the inner cylinder, the ejection pressure becomes uniform. As a result, the water column is stabilized and air bubbles are prevented from being entrained.

In addition, in the present invention, the apparent specific gravity of the inner cylinder relative to the medium is reduced (constituent requirement c), and the inner cylinder is always kept at the center of rotation by the buoyant force against the centrifugal force accompanying the high-speed rotation of the rotating probe holder. to be located in
It produces a centripetal action.

Furthermore, in the present invention, by watertightly sealing the space between the outer cylinder and the inner cylinder (constituent requirement d), a medium reservoir is formed in the outer cylinder, and the ejection pressure of the medium from the jet port is uniformized. At the same time, it produces the buoyancy mentioned above. Then, the outer cylinder and the inner cylinder are connected by an elastic member (constituent feature d), and the inner cylinder is held movable in the radial direction and rotated as the outer cylinder rotates, and the above-mentioned Together with the effect of buoyancy, the inner cylinder is biased to be held in a predetermined position.

In the present invention, as described above, by displacing the inner cylinder in the radial direction to accommodate the curvature of the specimen, the water column is stabilized to maintain a good acoustic coupling state. Flaw detection is performed by propagating ultrasonic waves between the probe and the material to be inspected via a water column formed at the spout. If the inner cylinder is displaced during flaw detection, the positional relationship between the probe attached to the outer diameter and the material to be inspected will be displaced, but if the diameter is relatively large, this will have little effect on flaw detection.

In addition, in the present invention, even if the inner cylinder is eccentric at the end of flaw detection of the preceding material, it automatically returns to the center position by the action of the buoyant force and the elastic member until the next material enters. The test material is prevented from colliding with the inner cylinder.

〔Example〕

The embodiments of the present invention will be described above with reference to the drawings.

FIG. 5 is a sectional view showing an embodiment of a rotating probe holder which is a main part of the rotating probe type ultrasonic flaw detection apparatus of the present invention, and FIG. 6 is a sectional view taken along line A-A.

In the figure, the rotary probe holder constituting the present invention has a double structure consisting of an outer tube 30 and an inner tube 32, and is rotatably supported by a housing, as in the conventional example shown in FIG. It is connected to the rotor part to form a rotating part main body, and as shown in Fig. 1, it is placed on a lifting adjustment frame and assembled on a common base together with pinch roll stands on the entry side and the exit side. Configure flaw detection equipment.

The outer diameter 30 is formed by mounting a plurality of probes 20 in the radial direction from the side surface, and a flange 31 is attached to the probe holder attachment end surface of the rotor part of the rotating part main body (not shown in this embodiment). Can be installed at At the outlet end of the outer cylinder 30, there is a conical surface 22 for slidingly contacting a fixed water supply ring similar to that explained in FIGS. 2 and 3 to receive supply of water as a couplant;
A water guide hole 3 that communicates between the conical surface 22 and the inside of the outer cylinder 30
9 is provided.

In this embodiment, eight probes are attached, but the number of probes is not limited to eight and can be set as appropriate.

The inner cylinder 32 has an outer diameter smaller than the inner diameter of the outer cylinder 30, is loosely fitted into the outer cylinder 30, and forms a cavity 36 between its outer periphery and the inner periphery of the outer cylinder 30. ing. In addition, the inner cylinder 32 forms a water column by spouting water in the cavity 36 into the inner cylinder 32 at a position corresponding to each probe 20 attached to the outer cylinder 30, and A spout 19 is provided to allow the ultrasonic waves from the child 20 to pass through and enter the specimen. Furthermore, a taper 33 is provided on the inside of the inner tube 32 on the side where the test material enters, and serves as a guide when the test material enters.

The inner cylinder 32 has a diaphragm 3 concentrically with the outer cylinder 30 at both ends on its inlet and outlet sides.
It is suspended at 4.35. The diaphragms 34 and 35 are elastic and expandable in the radial direction of the inner cylinder 32, and water-tightly seal the cavity 36 between the outer cylinder 30 and the inner cylinder 32.
An outer cylinder 30 and an inner cylinder 32 are connected.

Furthermore, two flanges 38a and 38b are provided at the inner center of the outer cylinder 30, projecting in the inner diameter direction, and on the other hand, the flanges 38a and 38b are provided at the outer center of the inner cylinder 32.
A flange 37 is provided in a position where it is sandwiched between the flange 38a and the flange 38b.
It is sandwiched and engaged with 38b. As a result, the inner cylinder 32
is movable in the radial direction by expansion and contraction of the diaphragms 34 and 35, but is restricted from moving in the axial direction. However, the prevention of axial movement of the inner cylinder 32 is not limited to the above-mentioned collar, but may be other means.

Note that it is desirable to provide a conduction hole 40 in the collar 37 in order to uniformly distribute the water within the cavity 36.

Next, the operation of the embodiment configured as described above will be explained.

It is assumed that the rotary probe holder of this embodiment is rotating at high speed while attached to the rotor part, and in this state, if the inner cylinder 32 is initially eccentric, the inner cylinder 32 has an eccentric amount. A proportional centripetal buoyant force acts. First, the reason for the generation of buoyancy will be explained with reference to FIGS. 7 and 8.

In FIG. 7, there is an inner cylinder 42 within the outer diameter 41, and the inner cylinder 42 is rotating together with the outer cylinder 41 at high speed. Here, it is assumed that the material of the inner cylinder 42 has the same specific gravity as water, and the inside of the outer cylinder 41, including the internal space of the inner cylinder 42, is filled with water.
In this case, a centrifugal force of {(mass of the inner tube 42) + (mass of water in the inner tube 42)} x eccentricity x (angular velocity) ² is acting on the inner tube 42, but The inner cylinder 42 does not change its relative position with respect to the outer cylinder 41 because it balances the pressure due to the centrifugal force exerted on the water between it and the outer cylinder 41 .

On the other hand, in FIG. 8, unlike the case in FIG. 7, water in the inner cylinder 42 is removed and replaced with air. In this case, the water outside the inner cylinder 42 is unbalanced by the amount of (mass of water in the inner cylinder 42) × eccentricity × (angular velocity) ² with respect to the pressure due to the centrifugal force, and this It acts on the inner cylinder 42 as a buoyant force in the centripetal direction.

This relationship is the same for the rotating probe holder of the embodiment shown in FIG. 5 above. In this case, the water spouted into the inner cylinder 32 through the spout 19 flows in a film form along the inner wall of the inner cylinder 32 due to centrifugal force, so the inside of the inner cylinder 32 becomes hollow, and as a buoyant force, {( A force of ² (mass of water removed by the inner cylinder 32) - (mass of the inner cylinder 32) x eccentricity x (angular velocity) acts on the inner cylinder 32 and attempts to return the inner cylinder 32 to the center.

However, in a region where the amount of eccentricity is small, the effect of buoyancy is small, but together with the elastic return force of the diaphragm 35 suspending the inner cylinder 32, it becomes a force toward the center that acts on the inner cylinder 32.

If the inner cylinder of the rotating probe holder is concentric with the outer cylinder in this way, when the next material to be tested enters the rotating probe holder, the tip of the next material will be aligned with the taper on the entry side of the inner cylinder 32. 33 and enters the inside of the inner cylinder 32. The rotary probe holder inner cylinder 32 rotates to follow the material to be inspected, and can detect and pass through the material to be inspected without causing damage due to collision.

Further, since there is a minute gap between the inner cylinder 32 and the material to be tested, the water from the jetting force 19 forms a stable water column within this gap and does not generate bubbles.
Moreover, even if the material to be inspected is bent, the inner tube 32 is displaced in the radial direction, so the water column is quickly stabilized and does not interfere with flaw detection. In this case, the pressure of the water spouted from the spout 19 is such that the water is
Moreover, since the change in volume of each part of the cavity 36 due to the displacement of the inner cylinder 32 is sufficiently small compared to the volume of the entire cavity 36, it is not affected by the displacement.

Furthermore, the diaphragm that suspends the inner cylinder from the outer cylinder not only suspends the inner cylinder, but also transmits to the cylinder a torque corresponding to the frictional force acting between the inner cylinder and the material to be inspected. Therefore, the necessary conditions for the diaphragm are determined by the spring constant for eccentricity and the transmitted torque.

Next, FIG. 9 shows another example of a rotary probe holder. The rotating probe holder shown in the figure has elastic plates 43, 44, which are formed by drawing a metal plate into a ring shape having a C-shaped cross section, instead of the diaphragms 34, 35 shown in FIGS. 5 and 6 above. The other configurations are the same as those shown in FIGS. 5 and 6.

In each of the above embodiments, the inner cylinder is connected to the outer cylinder by a diaphragm or a C-shaped ring, and these diaphragms and rings watertightly seal the space between the inner cylinder and the outer cylinder, and also and the outer cylinder are elastically connected. Therefore, other materials may be used as long as they have the same function, such as a rubber tire-shaped molded product with a cord incorporated therein. Further, the water-tight sealing function and the elastic connection function may be configured as separate members. For example, the space between the outer cylinder and the inner cylinder may be sealed at both ends of the outer cylinder and the inner cylinder using a cloth-like sealing member, and the inner cylinder and the outer cylinder may be connected by a spring or the like.

[Effects of the Invention] As explained above, the present invention provides a rotating probe holder with a double structure in which an inner cylinder is loosely fitted into an outer cylinder so as to be freely displaceable in the radial direction, and the inner cylinder is By having a structure that automatically returns to the center due to its own buoyancy and bias from an elastic member,
Even if the tip of the sample to be tested enters the rotating probe holder with some eccentricity or inclination, the inner tube of the rotating probe holder can follow this, so the rotating probe holder will not be damaged. This has the effect that the inner diameter can be set to reduce the gap with the test material, and good acoustic coupling can be maintained.

[Brief explanation of the drawing]

Fig. 1 is a front view schematically showing a conventional rotating probe type ultrasonic flaw detection device, Fig. 2 is a sectional view showing the main body of the rotating part used in the conventional device, and Fig. 3 is a cross-sectional view showing the main body of the rotating part used in the conventional device. 4 is a sectional view showing a conventional rotating probe holder, FIG. 4 is a sectional view taken along the line A-A, and FIG. A cross-sectional view showing one embodiment, FIG. 6 is a cross-sectional view taken along the line A-A, and FIGS. 7 and 8 are explanatory views for explaining the effect of buoyancy acting on the inner cylinder.
FIG. 9 is a sectional view showing another example of a rotary probe holder which is a main part of the flaw detection apparatus of the present invention. 1...Rotating part main body, 2...Elevation adjustment frame, 3,
4...Pinch roll stand, 5...Common base, 6...Test material, 11...Housing, 12...Rotor portion, 19...Ejection port, 20...Probe, 22...
... Conical surface, 30 ... Outer cylinder, 32 ... Inner cylinder, 33 ...
...Taper, 34, 35...Diaphragm, 36...
...Cavity part, 37, 38a, 38b...Tsuba, 39...
...Water introduction hole, 40...Conduction hole.

Claims (1)

[Scope of Claims] 1. A plurality of probes are attached to a rotary probe holder that is connected to a rotary rotor and rotates, and the plurality of probes are rotated at high speed around the outer periphery of a specimen moving straight. In a rotating probe type ultrasonic flaw detection device that performs full-length flaw detection on the entire surface, (a) the rotating probe holder has an outer cylinder that is attached to a rotor of a rotating part and rotates, and a rotating outer cylinder that is loosely fitted into the outer cylinder. (b) A plurality of probes are disposed in the outer tube, and an outer tube is placed in the corresponding position of the inner tube. (c) the inner cylinder has a mass smaller than the mass of the medium excluded by the space partitioned by the inner cylinder in the outer cylinder; (d) The outer cylinder and the inner cylinder are characterized in that the space between them is connected at both ends with the inner cylinder movable in the radial direction, watertightly sealed, and connected by an elastic member. A rotating probe type ultrasonic flaw detection device.