JP6076211B2 - Defect detection apparatus and defect detection method - Google Patents

Description

  The present invention relates to a defect detection apparatus and a defect detection method for detecting defects existing in the surface layer or inside of a steel bar or steel slab.

An ultrasonic flaw detection method is widely used as a method for nondestructively detecting defects existing on the surface of a metal material such as a steel bar or a steel piece, or on the surface. In general, the ultrasonic flaw detection method is a general term for three techniques of a vertical flaw detection method, an oblique flaw detection method, and a surface flaw detection method.
Here, the vertical flaw detection method is a technique for flaw detection in the inspected body using ultrasonic waves that travel perpendicularly to the surface of the inspected object, and the oblique flaw detection method is for the surface of the inspected object. This is a technique for flaw-detecting an inspected body or the surface of an inspected object using ultrasonic waves that travel obliquely. The surface flaw detection method is a technique for flaw-detecting the surface of the inspection object using surface ultrasonic waves that propagate on the surface of the inspection object.

  Specifically, the vertical flaw detection method uses a vertical probe that performs flaw detection by making ultrasonic waves enter the inside vertically from the surface of a steel piece and receiving reflected waves of the ultrasonic waves. With this vertical flaw detection method using a vertical probe, it is possible to detect defects present near the center inside the steel slab. However, the epidermis of the contact surface with the vertical probe on the surface of the steel piece has a problem that flaw detection cannot be performed because it is a surface dead zone.

  Based on such a background, Patent Document 1 discloses a method of flaw detection for surface layer defects of square steel pieces. The surface defect inspection method of Patent Document 1 is a surface defect inspection method for a square steel slab that detects an internal defect in the surface layer of a predetermined depth range below the surface of the square steel slab by ultrasonic flaw detection. A plurality of ultrasonic probes are arranged outside the surface on the opposite region side to detect internal defects of the square steel slab by the vertical method, and the regions on both sides of the square steel slab perpendicular to the surface of the surface layer region are detected. An ultrasonic probe is arranged outside the position adjacent to the edge to limit the flaw detection angle region, and internal defects of the square steel billets are detected by the bevel method, and the interior detected by these probes is detected. Defects in the surface region are evaluated based on the presence or absence of defects.

  As described above, in the surface layer flaw detection method disclosed in Patent Document 1, the inside of a steel piece is flawed by flaw detection by the vertical method (hereinafter referred to as vertical flaw detection method), and the surface layer region is flawed by flaw detection (hereinafter referred to as the flaw detection method). Flaw detection). In other words, the flaw detection area inside the steel slab is divided into a flaw detection area by the vertical flaw detection method and a flaw detection area by the oblique flaw detection method.

JP-A-2-210257

  In the surface layer defect inspection method disclosed in Patent Document 1, defects that cannot be detected well by the vertical inspection method must be detected by a probe used for the oblique inspection method (hereinafter referred to as an oblique inspection device). If it cannot be detected even by the oblique flaw detection method, the defect is overlooked. For example, if it is a defect with a shape close to a sphere like an inclusion, it can be expected that the ultrasonic wave will be reflected almost in all directions, so even if it cannot be detected by the vertical flaw detection method, it can be detected by the flaw detection method using the oblique flaw detection method. There is sex. However, in the case of a defect such as a crack, the progress of the defect has a direction, so that the ultrasonic wave may be reflected in a different direction from the oblique probe and the oblique flaw detection method may not detect the defect.

Therefore, the surface defect inspection method disclosed in Patent Document 1 is not a technique that considers the directionality of the defect, and there is a possibility that a defect that cannot be detected by the vertical inspection method may not be detected by the oblique inspection method. have.
In view of the above problems, an object of the present invention is to provide a defect detection apparatus and a defect detection method capable of reliably detecting a defect by at least one of a vertical flaw detection method and an oblique flaw detection method.

In order to achieve the above-described object, the present invention takes the following technical means.
A defect detection apparatus according to the present invention is a defect detection apparatus that detects an internal defect including a surface layer of an object to be inspected by using an ultrasonic wave, and is disposed on the surface of the object to be inspected. A transmitter that sends ultrasonic waves into the inspected object along the direction perpendicular to the inspection object, and receives ultrasonic waves that have been reflected and returned by defects existing inside including at least the surface layer of the inspected object A first probe having a wave receiving portion that is disposed on the surface of the object to be inspected, and along the direction oblique to the first probe relative to the surface. A second probe having a sending part for sending ultrasonic waves inside the inspection object and a wave receiving part for receiving ultrasonic waves reflected and returned by a defect existing at least inside the surface of the inspection object. A transducer and a surface disposed on the surface of the object to be inspected, closer to the first probe than the surface Along with the oblique direction, the transmitting unit that transmits ultrasonic waves to the inside of the object to be inspected and the ultrasonic waves reflected and returned by the defects existing at least including the surface layer of the object to be inspected are received. And a third probe having a wave receiving section.

  Here, the surface of the object to be inspected is composed of a plurality of surfaces, and the first probe is disposed on a first side surface that is one surface of the object to be inspected, and the second probe. A probe is disposed on a second side surface, which is a surface adjacent to one side of the first side surface, and transmits ultrasonic waves toward the first side surface, and the third probe is It may be disposed on a third side surface that is a surface adjacent to the other side of the first side surface, and may transmit ultrasonic waves toward the first side surface.

Further, the second probe sends out an ultrasonic wave toward a propagation region where the ultrasonic wave sent out by the sending unit of the first probe propagates, and the third probe sends the first probe to the first probe. You may send out the ultrasonic wave which goes to the area | region where the propagation area of the ultrasonic wave which the 1 probe sent out and the propagation area of the ultrasonic wave which the 2nd probe sent out cross | intersect.
Further, the first probe, the second probe, and the third probe are movable on the surface of the inspection object, and are moved on the surface of the inspection object. You may change the position of the area | region where the ultrasonic wave sent out from the said 3 probe cross | intersects.

  The defect detection method of the present invention is a defect detection method for detecting a defect existing inside including a surface layer of an inspection object by using an ultrasonic wave, and is perpendicular to the surface from the surface of the inspection object. A first probe that transmits ultrasonic waves to the inside of the object to be inspected and receives ultrasonic waves reflected and returned by defects existing inside including at least the surface layer of the object to be inspected. Ultrasonic waves inside the object to be inspected, along a direction oblique to the ultrasonic wave sent in the first probe process from the surface of the object to be inspected and from the surface of the object to be inspected A second probe step of receiving ultrasonic waves reflected and returned by defects existing inside including at least the surface layer of the object to be inspected, and from the surface of the object to be inspected to the surface On the other hand, along the direction oblique to the ultrasonic wave transmitted in the first probe step, A third probe step of transmitting an ultrasonic wave into the object to be inspected and receiving an ultrasonic wave reflected and returned by a defect existing inside including at least the surface layer of the object to be inspected; A defect existing inside the surface of the object to be inspected is detected based on the ultrasonic wave received in at least one of the probe process, the second probe process, and the third probe process. And a defect detection step.

Here, the second probe step sends out an ultrasonic wave directed to a propagation region where the ultrasonic wave sent out by the sending unit of the first probe propagates, and the third probe step includes the above-mentioned third probe step, You may send out the ultrasonic wave which goes to the area | region where the propagation area of the ultrasonic wave sent out by the 1st probe process and the propagation area of the ultrasonic wave sent out by the said 2nd probe process cross | intersect.
Further, the second probe step acquires a distance to a defect existing inside including the surface layer of the object to be inspected based on the received ultrasonic wave, and the third probe step receives the wave. A distance to a defect existing inside the inspection object is acquired based on the ultrasonic wave, and the surface subcutaneous defect detection step includes the distance to the defect obtained in the second probe step, and the third The position of the defect existing inside the surface of the object to be inspected may be detected using the distance to the defect obtained in the probe step.

Also, the first received intensity of the ultrasonic wave received in the first probe process is acquired, the second received intensity of the ultrasonic wave received in the second probe process is acquired, and the third The third received wave intensity of the ultrasonic wave received in the probe step is acquired, and the received wave intensity is obtained using the acquired first received wave intensity, second received wave intensity and third received wave intensity. You may provide the defect state detection process of detecting the progress direction of the defect which exists inside including the surface layer of a test body.
The most preferable form of the defect detection apparatus according to the present invention is a defect detection apparatus for detecting defects existing inside the surface of the inspection object using ultrasonic waves, on the surface of the inspection object. Reflected by a defect that is disposed and includes at least a surface of the object to be inspected, and a sending part that transmits ultrasonic waves to the inside of the object to be inspected along a direction perpendicular to the surface A first probe having a wave receiving portion for receiving the returned ultrasonic wave, and disposed on the surface of the object to be inspected, and is inclined toward the first probe with respect to the surface. A transmission unit that transmits ultrasonic waves to the inside of the object to be inspected along a direction, and a wave receiving unit that receives ultrasonic waves reflected and returned by a defect existing inside including at least the surface layer of the object to be inspected And a second probe having a surface of the object to be inspected, And a defect existing inside including at least a surface layer of the object to be inspected, along a direction oblique to the first probe with respect to A third probe having a wave receiving part for receiving the ultrasonic wave reflected and returned by the second probe, wherein the second probe is a sending part of the first probe. The third probe transmits an ultrasonic wave directed to a propagation region where the ultrasonic wave transmitted by the first probe propagates, and the third probe transmits the ultrasonic wave propagation region and the second probe transmitted by the first probe. By transmitting ultrasonic waves directed to a region intersecting with the ultrasonic propagation region transmitted by the sensor, a flaw detection region is formed, and the first probe, the second probe, and the third probe are formed. A probe is movable on the surface of the object to be inspected, and is transmitted from the three probes by moving on the surface of the object to be inspected. Wherein the ultrasonic waves is configured to change the position of the cross formed by the flaw regions.
Moreover, the most preferable form of the defect detection method according to the present invention is a defect detection method for detecting a defect existing inside the surface of the object to be inspected using an ultrasonic wave, from the surface of the object to be inspected. The ultrasonic wave is transmitted into the inspection object along a direction perpendicular to the surface, and the ultrasonic wave reflected and returned by at least a defect existing inside the surface including the surface layer of the inspection object is returned. A first probe step for receiving a wave, and from the surface of the object to be inspected, along the direction oblique to the ultrasonic wave transmitted in the first probe step with respect to the surface. A second probe step of transmitting ultrasonic waves to the inside of the inspection object and receiving the ultrasonic waves reflected and returned by at least a defect existing inside including the surface layer of the inspection object; and Ultrasonic waves sent from the surface to the surface in the first probe step The ultrasonic wave is sent to the inside of the object to be inspected along an oblique direction, and the ultrasonic wave reflected and returned by a defect existing at least inside the surface of the object to be inspected is received. 3 and a defect existing inside the surface of the object to be inspected based on the ultrasonic waves received in the first probe process, the second probe process, and the third probe process. A defect detection step of detecting the first and second detection steps, wherein the second probe step sends out an ultrasonic wave directed to a propagation region where the ultrasonic wave sent out by the sending portion of the first probe propagates, In the third probe step, an ultrasonic wave directed to a region where the ultrasonic wave propagation region transmitted in the first probe step intersects the ultrasonic wave propagation region transmitted in the second probe step is transmitted. Forming a flaw detection area, and the first probe, the second probe, and the third probe are arranged on the surface of the object to be inspected. Ultrasonic wave transmitted from the three probe by moving and changing the position of the flaw area intersected to form a.

  According to the defect detection apparatus and the defect detection method of the present invention, a defect can be reliably detected by at least one of the vertical flaw detection method and the oblique flaw detection method.

It is a figure which shows the external appearance of the defect detection apparatus by embodiment of this invention. It is a figure which shows schematic structure of the defect detection apparatus by this embodiment. It is a figure explaining the relationship between the angle of a defect, and the echo level of an ultrasonic wave. It is a figure which classifies and shows the defect detection operation | movement of the defect detection apparatus by this embodiment. It is a figure explaining the defect detection operation | movement by the bevel probe of the defect detection apparatus by this embodiment. It is a figure which shows schematic structure of the modification of the defect detection apparatus by this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
Hereinafter, the defect detection apparatus 1a according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5 and a defect detection method using the defect detection apparatus 1a will be described.
FIG. 1 is a diagram illustrating an appearance of the defect detection apparatus 1a according to the present embodiment. The defect detection device 1a detects (defects) a defect existing inside including the surface layer of an object to be inspected having a plurality of outer surfaces such as a prismatic steel bar or a steel piece, for example, using ultrasonic waves. Device. In this embodiment, the steel piece W is illustrated as a to-be-inspected object.

  The defect detection apparatus 1a includes a first probe 2, a second probe 3a, and a third probe 4a, which will be described later. The first probe 2 is disposed on the surface of a steel slab W that is an object to be inspected, and a sending section (sending ultrasonic waves into the steel slab W along a direction perpendicular to the surface) ( And a wave receiving portion (not shown) for receiving the ultrasonic wave reflected and returned by a defect existing inside including at least the surface layer of the steel slab W. The second probe 3a is disposed on the surface of the steel slab W, and transmits ultrasonic waves into the steel slab W along a direction that is inclined toward the first probe 2 with respect to the surface. And a receiving section (not shown) for receiving the ultrasonic wave reflected and returned by a defect existing inside including at least the surface layer of the steel slab W. The third probe 4a is disposed on the surface of the steel slab W, and transmits ultrasonic waves into the steel slab W along a direction that is inclined toward the first probe 2 with respect to the surface. And a receiving section (not shown) for receiving the ultrasonic wave reflected and returned by a defect existing inside including at least the surface layer of the steel slab W.

  Although the detailed configuration of the first probe 2, the second probe 3a, and the third probe 4a will be described later, the defect detection apparatus 1 includes the first probe 2, the second probe, and the like. The contact 3a and the third probe 4a are arranged on the surface of the steel slab W to detect defects existing inside the steel slab W including the surface layer. Here, the surface layer is a region having a predetermined depth range below the surface of the steel piece W (subcutaneous surface), particularly a region having a depth of several mm to several tens mm. The inside of the steel slab W includes the surface layer and a portion deeper than the surface layer.

Next, the defect detection apparatus 1 that detects defects existing inside the steel slab W including the surface layer will be described in detail with reference to FIGS. 1 and 2.
FIG. 2 is a diagram showing a schematic configuration of the defect detection apparatus 1, and the first probe 2, the second probe 3 a, and the third probe 4 a are arranged on the outer surface of the steel piece W. Shows the state. The outer surface of the steel piece W is composed of a plurality of surfaces, and has, for example, four surfaces as side surfaces as shown in FIG.

With respect to the steel piece W having such a shape, the first probe 2 is disposed on the first side surface 5 which is one of the four side surfaces of the steel piece W. The first probe 2 transmits an ultrasonic wave substantially perpendicular to the first side surface 5, and the transmitted ultrasonic wave propagates from the first side surface 5 into the steel slab W. Here, the 1st side surface 5 is a surface right above the surface layer used as the object which detects a defect.
Next, the second probe 3 a is disposed on the second side surface 6 that is a surface adjacent to one side of the first side surface 5. The second probe 3a transmits ultrasonic waves in a direction toward the first side surface 5, that is, obliquely with respect to the second side surface 6, and the transmitted ultrasonic waves are transmitted from the second side surface 6 to the second side surface 6. Propagates the inside of the steel slab W toward the side surface 5 of 1.

  Further, the third probe 4 a is a surface opposite to the second side surface 6 with the first side surface 5 interposed therebetween, and is a surface adjacent to the other side of the first side surface 5. Is disposed on the side surface 7. The third probe 4a transmits ultrasonic waves in a direction toward the first side surface 5, that is, obliquely with respect to the third side surface 7. The transmitted ultrasonic waves are transmitted from the third side surface 7 to the first side surface 5. Propagates the inside of the steel slab W toward the side surface 5 of 1.

As described above, the defect detection apparatus 1 has an oblique probe on both side surfaces (the second side surface 6 and the third side surface 7) sandwiching the first side surface 5 on which the first probe 2 is disposed. The second probe 3a and the third probe 4a are arranged.
Here, FIG. 2 shows a region in which the ultrasonic wave transmitted from the first probe 2 propagates inside the steel piece W as a propagation region 8 by a broken line. Further, FIG. 2 shows the propagation region 9 of the ultrasonic wave sent out from the second probe 3a by a dotted line, and shows the propagation region 10 of the ultrasonic wave sent out from the third probe 4a by a one-dot chain line. ing. The ultrasonic wave transmitted from the first probe 2 propagates toward the opposite side of the first side surface 5 while diffusing from the first side surface 5.

The ultrasonic wave transmitted from the second probe 3 a propagates toward the first side surface 5 while diffusing from the second side surface 6. At this time, the second probe 3 a propagates the ultrasonic wave toward the ultrasonic wave propagation region 8 sent out by the sending unit of the first probe 2 and the first probe 5 of the first side face 5. 3 so as to propagate toward the side surface 7 side.
Further, the ultrasonic wave transmitted from the third probe 4 a propagates toward the first side surface 5 while diffusing from the third side surface 7. At this time, the third probe 4a transmits ultrasonic waves to the ultrasonic wave propagation region 8 sent from the first probe 2 and the ultrasonic wave propagation region 9 sent from the second probe 3a. Is transmitted so as to propagate toward the region where the two intersect with each other and propagate toward the second side surface 6 side of the first side surface 5.

As shown in FIG. 2, the ultrasonic wave is transmitted by the first probe 2, the second probe 3a, and the third probe 4a as described above, so that the bottom of the first probe 2 is obtained. A region where the ultrasonic wave propagation regions 8, 9, and 10 from these three probes 2, 3a, and 4a intersect (overlap) is formed inside the surface layer, and this region and its peripheral region are the flaw detection region. 11
The first probe 2, the second probe 3a, and the third probe 4a can be configured by, for example, a general ultrasonic probe configured by a piezoelectric element, and have a predetermined voltage. When a pulse current is applied, it has a function as a transmission unit that transmits ultrasonic waves of a predetermined frequency and a function as a reception unit that receives reflected ultrasonic waves. In addition, the direction (namely, angle) which sends out an ultrasonic wave can be set arbitrarily, and the 1st probe 2 is perpendicular to the 1st side surface 5 (namely, in order to perform a vertical flaw detection (i.e. 90 °), and the second probe 3a and the third probe 4a are inclined with respect to the second side surface 6 and the third side surface 7 in order to perform oblique flaw detection. (Ie, at a predetermined angle).

  As shown in FIG. 1 and FIG. 2, the defect detection apparatus 1 is configured to move the C-shaped probe up and down across the third side surface 7 from the second side surface 6 to the first side surface 5 along the shape of the steel slab W. A mechanism 12a is provided. The probe elevating mechanism 12 a is provided on the first side elevating mechanism 13 disposed along the first side surface 5, the second elevating mechanism 14 disposed along the second side surface 6, and the third side surface 7. A third elevating mechanism 15 arranged along the C-shaped configuration is arranged, and the first probe 2 is arranged in the first elevating mechanism 13 and the second elevating mechanism 14 is arranged. The second probe 3a is held by the third lifting mechanism 15 with the third probe 4a, and the probes 2, 3a, 4a are respectively opposed to the side surfaces 5, 6, 7 of the steel piece W. Is raised and lowered.

  The defect detection apparatus 1 includes a contact medium supply unit 16 that supplies a contact medium to each of the probes 2, 3 a, and 4 a through a probe lifting mechanism 12 a. The contact medium is a substance that transmits ultrasonic waves, such as water, glycerin paste, and oil, and is a medium that transmits ultrasonic waves between the probe 2, 3a, 4a and the side surface of the steel piece W. . However, in the probes 2, 3a and 4a, when an electromagnetic ultrasonic sensor or the like is used instead of the piezoelectric element, a contact medium is unnecessary.

  The contact medium supply unit 16 is connected to each of the probes 2, 3a, and 4a by a contact medium supply pipe (not shown) via the probe lifting mechanism 12a, and the probes 2, 3a, and 4a are connected through the contact medium supply pipe. A contact medium is supplied to each of 4a. The contact medium supply unit 16 is also connected to each of the probes 2, 3 a, 4 a by a contact medium recovery tube (not shown), and the supplied contact medium is passed through the probe 2 through the contact medium recovery tube. Recover from each of 3a, 4a.

  The defect detection apparatus 1 includes an ultrasonic flaw detector 17 connected to each of the probes 2, 3a, 4a via a probe lifting mechanism 12a. The ultrasonic flaw detector 17 generates a ultrasonic wave by outputting a pulse current of a predetermined voltage to a piezoelectric element that functions as a sending part of each of the probes 2, 3a, 4a, and the piezoelectric element receives a reflected ultrasonic wave. It receives a pulse current generated when it acts as a wave receiving section and outputs it as a reflected wave signal to a recording signal processing device 18 to be described later.

The defect detection device 1 includes a recording signal processing device 18 connected to the ultrasonic flaw detector 17. The recording signal processing device 18 receives the pulse current output from the ultrasonic flaw detector 17 based on the received reflected ultrasonic wave, and based on the received pulse current, the arrival time of the reflected ultrasonic wave (echo), That is, the position of the defect in the inside including the surface layer is calculated.
The defect detection apparatus 1 includes the above-described first probe 2, second probe 3a and third probe 4a, probe lifting mechanism 12a, contact medium supply unit 16, ultrasonic flaw detector 17 and recording. A signal processing device 18 is provided.

  Here, the first probe 2, the second probe 3 a, and the third probe 4 a are respectively supported by the first lifting mechanism 13, the second lifting mechanism 14, and the third probe. It is movable along the longitudinal direction of the lifting mechanism 15. Thereby, the first probe 2, the second probe 3a, and the third probe 4a are the first side surface 5, the second side surface 6, and the third side surface, which are the surfaces of the steel piece W. 7, the position of the flaw detection area 11 where the ultrasonic waves transmitted from the three probes 2, 3a, 4a intersect can be changed by moving on these side surfaces.

The defect detection apparatus 1 having the above-described configuration can detect a defect even when the progress of the defect has a direction like a crack.
The detection principle will be described below with reference to FIGS.
FIG. 3 is a diagram for explaining the relationship between the angle of the defect d and the ultrasonic echo level. FIG. 3A schematically shows the relationship between the position and angle of the defect d and the incident direction of the ultrasonic wave. ) Indicates a change in echo level when the defect angle is changed.

  Referring to FIG. 3A, a defect d having a length of 1 mm that has progressed in one direction is present in a state inclined by an angle θ (deg) with respect to the surface S of the steel piece W. At this time, the depth D of the defect from the surface S of the steel slab W is assumed to be 5 mm and 20 mm. For a defect d inclined at an angle θ (deg) with respect to the surface S of the steel slab W, an ultrasonic wave is transmitted (incident) perpendicularly to the surface S of the steel slab W by the vertical flaw detection method, and by the oblique flaw detection method. Ultrasonic waves are sent out (incident) from the side of the surface S of the steel piece W.

  As shown in FIG. 3B, when the angle θ of the defect d is changed in the vertical flaw detection method, the propagation direction of the defect d is close to perpendicular to the ultrasonic propagation direction (θ = 0 °, 180 °). Sometimes the reflection (echo) level of the ultrasonic wave at the defect d is high, but when the propagation direction of the defect d is close to parallel (θ = 90 °) to the propagation direction of the ultrasonic wave, the reflection (echo) of the ultrasonic wave. The level is lowered. The echo level in the vertical flaw detection method shows almost the same change regardless of whether the depth D of the defect d is 5 mm or 20 mm.

  Further, when the angle θ of the defect d is changed in the oblique flaw detection method, when the propagation direction of the defect d is close to the perpendicular (θ = 90 ° to 120 °) with respect to the propagation direction of the ultrasonic wave, Although the reflection (echo) level of the sound wave is high, the reflection (echo) level of the ultrasonic wave becomes low when the propagation direction of the defect d is close to parallel (θ = 0 °, 180 °) with respect to the propagation direction of the ultrasonic wave. . The echo level in the oblique flaw detection method also shows almost the same change regardless of whether the depth D of the defect d is 5 mm or 20 mm, but at the time when the depth D of the defect d is 20 mm than when the depth D is 5 mm. The echo level is generally higher.

As described above, the echo level that can be detected by the vertical flaw detection method and the echo level that can be detected by the oblique flaw detection method when the defect angle θ is changed is increased if one is decreased, and the other is increased if one is increased. The relationship that decreases is established. Therefore, a defect d having any defect angle θ can be detected by the vertical flaw detection method or the oblique flaw detection method.
Therefore, referring to FIG. 4, the first probe (vertical probe) 2, the second probe (bevel angle 1 probe) 3a and the third probe (bevel angle 2 probe) 4a described above. The difference between the defect angle θ, that is, the success or failure of the flaw detection due to the direction of the defect d when the vertical flaw detection method and the oblique flaw detection method are applied will be described.

FIG. 4 is a diagram schematically showing the defect detection operation of the defect detection apparatus.
The following Table 1 summarizes the success or failure of defect detection in each probe for the four types (a) to (d) shown in FIG.

  In FIG. 4 (a), the defect d is a planar shape that has developed substantially parallel to the propagation direction of the ultrasonic wave from the vertical probe 2, and the ultrasonic wave from the oblique angle 1 probe 3a and the oblique angle 2 probe 4a. Nearly perpendicular to the propagation direction. At this time, the defect d hardly reflects the ultrasonic wave from the vertical probe 2 toward the vertical probe 2, reflects the ultrasonic wave from the bevel 1 probe 3 a to the bevel 1 probe 3 a, and the bevel 2 probe. The ultrasonic wave from 4a is reflected to the oblique angle 2 probe 4a. Accordingly, as indicated by the symbol “x” in Table 1 (a), the vertical probe 2 cannot detect the ultrasonic wave (defect signal) reflected by the defect d, and is indicated by the symbol “◯”. As described above, the bevel angle 1 probe 3a and the bevel angle 2 probe 4a detect the defect signal.

  In FIG. 4 (b), the defect d is a planar shape that extends substantially perpendicular to the propagation direction of the ultrasonic wave from the vertical probe 2, and the ultrasonic wave from the oblique angle 1 probe 3a and the oblique angle 2 probe 4a. Nearly parallel to the propagation direction. At this time, the defect d reflects the ultrasonic wave from the vertical probe 2 almost toward the vertical probe 2, but not only reflects the ultrasonic wave from the bevel 1 probe 3 a to the bevel 1 probe 3 a but also the bevel angle. The ultrasonic waves from the two probes 4a are hardly reflected to the oblique angle two probe 4a. Accordingly, the vertical probe 2 detects a defect signal as indicated by the symbol “◯” in Table 1 (b), and the oblique angle 1 probe 3a and the oblique angle 2 probe 4a as indicated by the symbol “x”. Cannot detect a defect signal.

  In FIG. 4C, the defect d has a surface shape that progresses from the upper right to the lower left toward the paper surface of FIG. 4C, and one surface is between the vertical probe 2 and the oblique angle 2 probe 4a. And the other surface is directed to the bevel 1 probe 3a. That is, it is neither parallel nor perpendicular to the propagation direction of the ultrasonic waves from the vertical probe 2 and the oblique angle 2 probe 4a, but is almost perpendicular to the propagation direction of the ultrasonic waves from the oblique angle 1 probe 3a. At this time, the defect d reflects the ultrasonic wave from the oblique angle 1 probe 3a substantially toward the oblique angle 1 probe 3a, but not only reflects the ultrasonic wave from the vertical probe 2 to the vertical probe 2 but also the oblique angle. The ultrasonic waves from the two probes 4a are hardly reflected to the oblique angle two probe 4a. However, the ultrasonic wave from the oblique angle 2 probe 4a is reflected by the defect d and then returns to the oblique angle 2 probe 4a while being largely attenuated by being reflected by the surface on which the vertical probe 2 is disposed. Accordingly, the vertical probe 2 cannot detect the defect signal as indicated by the symbol “x” in Table 1 (c), but the oblique angle 1 probe 3a detects the defect signal as indicated by the symbol “◯”. In addition, the bevel angle 2 probe 4a detects a slight defect signal based on the attenuated reflected wave, as indicated by the symbol “Δ”.

  In FIG. 4D, the defect d has a surface shape that progresses from the upper left to the lower right toward the paper surface of FIG. 4D, and one surface is between the vertical probe 2 and the oblique angle 1 probe 3a. The other surface is directed to the bevel angle 2 probe 4a. That is, the arrangement is symmetrical with respect to FIG. Therefore, the success or failure of the defect detection is also symmetrical with respect to FIG. 4C, and the vertical probe 2 cannot detect the defect signal as indicated by the symbol “x” in Table 1 (d), but the symbol “O”. As shown by “”, the oblique angle 2 probe 4a detects a defect signal. Further, the bevel angle 1 probe 3a detects a slight defect signal based on the attenuated reflected wave, as indicated by the symbol “Δ”.

  As described above, the defect detection apparatus 1 according to the present embodiment can reliably detect a defect by at least one of the flaw detection method and the vertical flaw detection method. Since the conventional technology does not have a configuration that takes into account the direction of defect propagation, when a defect is detected by both the vertical flaw detection method and the oblique flaw detection method, it is determined that the defect exists under the steel slab W. In the case where it was detected by the oblique flaw detection method but not detected by the vertical flaw detection method, it was determined that the defect was present inside the steel piece W. However, even if a defect exists under the steel slab W, it may not be detected by the vertical flaw detection method depending on the direction of the defect, and the conventional technique cannot be said to be a sufficient technique for identifying the defective part. It was.

On the other hand, since the defect detection apparatus 1 according to the present embodiment has a configuration in which the defect detection apparatus 1 considers the progress direction of the defect d, as shown in Table 1, the probes 2 and 3a that detect the defect d are provided. , 4a and the intensity of the defect signal, it can be said that the position of the defect d and the development direction (tilt) of the defect d can be reliably specified.
According to the configuration of the defect detection apparatus 1, as shown in FIG. 5, it is possible to improve the detection accuracy of the depth of the defect d.

FIG. 5 is a diagram for explaining a defect detection operation by the oblique angle probes 3a and 4a of the defect detection apparatus 1, wherein (a) shows an operation when the defect d exists inside the steel piece W. b) shows the operation when the defect d exists under the steel piece W.
As shown in FIG. 5A, the defect signal (bevel angle) detected by the bevel 1 probe 3a is detected by the bevel 1 probe 3a and the bevel 2 probe 4a but not by the vertical probe 2. 1 signal) 19 is displayed on the ultrasonic flaw detector 17 as an ultrasonic waveform, and the defect signal (diagonal angle 2 signal) 20 detected by the oblique angle 2 probe is also displayed on the ultrasonic flaw detector 17 as an ultrasonic waveform. The propagation distance of the ultrasonic wave can be obtained based on the time from the transmission of the ultrasonic wave until the ultrasonic waveform is obtained, and the distance from each of the probes 3a and 4a to the defect d can be obtained from this propagation distance. However, since only the distance from the probe 3a or the probe 4a corresponding to the ultrasonic waveform to the defect d is known only with one ultrasonic waveform, is the defect d present under the skin or inside deeper than the skin? Therefore, the depth of the defect d cannot be detected.

Therefore, the defect detection apparatus 1 determines the distance from the bevel 1 probe 3a to the defect d based on the defect signal 19 detected by the bevel 1 probe 3a and the bevel 2 probe 4a detected by the bevel 2 probe 4a. A position that simultaneously satisfies the distance to the defect d is specified in the steel slab W, and the specified position is detected as the position of the defect d.
Specifically, a circle having a radius that is the distance to the defect d detected with the bevel 1 probe 3a as the center is drawn, and at the same time, the distance to the defect d that is detected with the bevel 2 probe 4a as the center is the radius. Draw a circle to do. At this time, the position of the intersection of the two drawn circles is obtained, and the obtained position is in the ultrasonic wave propagation area from the oblique angle 1 probe 3a inside the steel piece W, and the oblique angle 2 probe 4a. Is within the ultrasonic wave propagation region, the obtained position is detected as the position of the detected defect d. The position of the defect d can be detected using such a geometric calculation, and this calculation is performed by the recording signal processing device 18.

  FIG. 5A shows an example where the ultrasonic waveform of the defect signal 19 by the oblique angle 1 probe 3a and the ultrasonic waveform of the defect signal 20 by the oblique angle 2 probe 4a have substantially the same propagation distance. 5 (b) shows a case where the propagation distance indicated by the ultrasonic waveform of the defect signal 20 by the oblique angle 2 probe 4a is larger than the propagation distance indicated by the ultrasonic waveform of the defect signal 19 by the oblique angle 1 probe 3a. An example is shown.

For the defect d that cannot be detected by the bevel 1 probe 3a and the bevel 2 probe 4a by the bevel flaw detection method but only by the vertical probe 2 by the vertical flaw detection method, the depth of the defect d can be determined from the propagation distance in the vertical direction. The position can be specified almost accurately.
The operation of the defect detection apparatus 1 according to the present embodiment having the above-described configuration will be described below as a defect detection method.

The defect detection apparatus 1 has the first lifting mechanism 13 along the first side surface 5 and the second lifting mechanism 14 along the second side surface 6, and the third lifting mechanism 15 is moved to the third side surface 5. The probe elevating mechanism 12 a is arranged with respect to the steel piece W along the side surface 7.
The probe lifting mechanism 12a brings the first probe 2, the second probe 3a, and the third probe 4a into contact with the steel piece W, and the contact medium supply unit 16 includes the probe lifting mechanism 12a. The contact medium is supplied to each of the probes 2, 3a, 4a via the. In this way, preparation for flaw detection under the first side surface 5 of the steel slab W is completed.

When preparation for flaw detection is completed, the ultrasonic flaw detector 17 outputs a pulse current of a predetermined voltage to each of the sending parts of the probes 2, 3 a, 4 a, and from above the surface of the steel piece (inspection object) W. The ultrasonic wave is sent into the steel slab W along the direction perpendicular to the surface via the first probe 2, and the defects existing inside the steel slab W including the surface layer are The reflected ultrasonic wave is received.
Then, the ultrasonic flaw detector 17 acquires the ultrasonic pulse of the ultrasonic wave received by the first probe 2, and the recording signal processing device 18 receives the ultrasonic wave (that is, the ultrasonic pulse). ), The distance to the defect existing inside including the surface layer of the steel slab W is obtained. This is the first probe step.

  Next, from the surface of the steel slab W through the second probe 3a, the surface is inclined toward the ultrasonic wave sent from the first probe 2 in the first probe step with respect to the surface. The ultrasonic waves are sent into the steel slab W along the direction to be received, and the ultrasonic waves reflected and returned by the defects existing inside including at least the surface layer of the steel slab W are received. At this time, the 2nd probe 3a sends out the ultrasonic wave which goes to the propagation field where the ultrasonic wave sent out from the 1st probe 2 propagates.

After that, the ultrasonic flaw detector 17 acquires the ultrasonic pulse of the ultrasonic wave received by the second probe 3a, and the recording signal processing device 18 receives the ultrasonic wave (that is, the ultrasonic pulse). ), The distance to the defect existing inside including the surface layer of the steel slab W is obtained. This is the second probe process.
Further, from the surface of the steel slab W through the third probe 4a, the surface is inclined obliquely toward the ultrasonic wave transmitted from the first probe 2 in the first probe process. The ultrasonic wave is sent into the steel slab W along the direction, and the ultrasonic wave reflected and returned by the defect existing inside including at least the surface layer of the steel slab W is received. At this time, the 3rd probe 4a sends out the ultrasonic wave which goes to the propagation field where the ultrasonic wave sent out from the 1st probe 2 propagates.

Then, the ultrasonic flaw detector 17 acquires the ultrasonic pulse of the ultrasonic wave received by the third probe 4a, and the recording signal processing device 18 receives the ultrasonic wave (that is, the ultrasonic pulse). ), The distance to the defect existing inside including the surface layer of the steel slab W is obtained. This is the third probe step.
Through the first probe process to the third probe process, the recording signal processing apparatus 18 detects at least one of the first probe process, the second probe process, and the third probe process. Based on the ultrasonic wave received in the process, the position of the defect existing inside including the surface layer of the steel slab W is detected.

  The recording signal processing device 18 uses the distance to the defect obtained in the second probe process and the distance to the defect obtained in the third probe process to obtain the second signal in the second probe process. The position that simultaneously satisfies the determined distance and the distance to the defect obtained in the third probe step is specified in the steel slab W, and the specified position exists inside the steel slab W including the surface layer. It detects as the position of the defect to be. This defect position detection is a defect detection step.

  Further, the recording signal processing device 18 acquires a first received wave intensity that is the intensity of the ultrasonic wave received by the ultrasonic flaw detector 17 in the first probe process, and the ultrasonic flaw detector in the second probe process. A second received intensity that is the intensity of the ultrasonic wave received by the device 17 is acquired, and a third received intensity that is the intensity of the ultrasonic wave received by the ultrasonic flaw detector 17 in the third probe step. To get. After acquiring these received wave intensities, the recorded signal processing device 18 uses the acquired first received wave intensity, second received wave intensity, and third received wave intensity to include the inner layer including the surface layer of the steel slab W. The state of a defect existing in the area, for example, the inclination of the defect and the direction of progress are detected. The detection of the defect state is a defect state detection step.

  As described above, according to the defect detection apparatus 1 and the defect detection method according to the present embodiment, vertical flaw detection and oblique flaw detection from two directions with respect to one flaw detection area inside the steel slab W are measured in three directions. By this flaw detection, it is possible to detect a defect regardless of the direction in which the defect progresses. In addition, since the vertical probe 2 has a configuration in which the inside including the surface layer below the contact surface in contact with the steel slab W is detected, the detection sensitivity before the ultrasonic beam from the vertical probe 2 diffuses and spreads out. A defect can be detected using a good propagation region.

Here, in the vertical flaw detection method, there is a problem that flaw detection is difficult on the epidermis of the contact surface between the vertical probe and the steel piece W due to the surface dead zone. However, of the defects existing at the stage of the steel slab W, the defects that are harmful when rolled into a steel bar or wire are not inside the skin of the steel slab W but inside the surface layer (for example, a depth of 5 mm or more from the surface). It has become clear in recent years that this is a defect.
Therefore, the defect detection apparatus 1 according to the present embodiment can detect defects regardless of their progress direction, and can also accurately detect the depth of defects, so that defects that are harmful when rolled into a bar or wire rod Can be detected appropriately.
[Second Embodiment]
The defect detection apparatus 1b according to the second embodiment of the present invention will be described below with reference to FIG.

FIG. 6 is a diagram showing a schematic configuration of the defect detection apparatus 1b according to the present embodiment.
The defect detection apparatus 1b has substantially the same configuration as the defect detection apparatus 1a according to the first embodiment. However, the defect detection apparatus 1b uses the second probe 3b as an oblique probe instead of the second probe 3a and the third probe 4a of the defect detection apparatus 1a according to the first embodiment. And a third probe 4b.

The 2nd probe 3b and the 3rd probe 4b are arrange | positioned on the same 1st side surface 5 as the 1st probe 2 which is a vertical probe.
The second probe 3 b is disposed closer to the second side surface 6 than the first probe 2, and extends in a direction toward the third side surface 7, that is, obliquely with respect to the first side surface 5. A sound wave is transmitted, and the transmitted ultrasonic wave propagates in the steel piece W from the first side surface 5 toward the third side surface 7.

The third probe 4 b is disposed closer to the third side surface 7 than the first probe 2, and extends in a direction toward the second side surface 6, that is, obliquely with respect to the first side surface 5. Sound waves are transmitted, and the transmitted ultrasonic waves propagate through the steel piece W from the first side surface 5 toward the second side surface 6.
As shown in FIG. 6, by having the second probe 3b and the third probe 4b having the above-described configuration, the first probe 2, the second probe 3b, and the third probe Due to the transmission of ultrasonic waves by the probe 4b, the ultrasonic propagation regions from these three probes 2, 3b, 4b intersect (overlapping) the inside including the surface layer below the first probe 2. ) Region is formed, and this region and its peripheral region become the flaw detection region.

  That is, the defect detection apparatus 1b according to the present embodiment can also form a flaw detection area similar to that of the defect detection apparatus 1a according to the first embodiment, and has the same operations and effects as those of the defect detection apparatus 1a according to the first embodiment. Demonstrate. Further, according to the defect detection apparatus 1b according to the present embodiment, the probe lifting mechanism 12b may be provided only on the first side surface 5 and may not be provided on the second side surface 6 and the third side surface 7. . Therefore, since the defect detection apparatus 1b according to the present embodiment has a relatively small configuration, it is effective when the installation space of the apparatus for detecting defects is limited.

  Each embodiment disclosed this time should be considered as illustrative in all points and not restrictive. In particular, in each embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of the constituents are within the range normally practiced by those skilled in the art. It does not deviate and employs a value that can be easily assumed by those skilled in the art.

  Specifically, in each of the above-described embodiments, a defect detection apparatus using one each of the first probe 2, the second probe 3a or 3b, and the third probe 4a or 4b. Although 1a or 1b is configured, the defect detection device 1a or 1b may be configured by using a plurality of these probes. For example, if a plurality of first probes 2 are used, the flaw detection area in the surface area can be enlarged.

  Moreover, in each above-mentioned embodiment, the case where only the inside including the surface layer under the 1st side surface 5 which is one side surface among the four side surfaces of the steel slab W is flaw-detected is illustrated, and the defect detection apparatus 1a or 1b is illustrated. Explained the configuration. However, a plurality of defect detection devices 1a or 1b may be used so that the first probe 2 contacts each side surface of the steel piece W. In order to detect the inside including the surface layer under the four side surfaces of the steel piece W, four defect detection devices 1a or 1b are prepared, and the first probes 2 of the defect detection devices 1a or 1b are respectively different side surfaces. What is necessary is just to arrange | position the defect detection apparatus 1a or 1b so that it may contact.

1a, 1b Defect detection device 2 First probe (vertical probe)
3a, 3b 2nd probe (bevel 1 probe)
4a, 4b 3rd probe (bevel 2 probe)
DESCRIPTION OF SYMBOLS 5 1st side surface 6 2nd side surface 7 3rd side surface 8, 9, 10 Propagation area | region 11 Flaw detection area | region 12a, 12b Probe raising / lowering mechanism 13 1st raising / lowering mechanism 14 2nd raising / lowering mechanism 15 3rd raising / lowering mechanism 16 Contact medium supply unit 17 Ultrasonic flaw detector 18 Recording signal processing device 19 Defect signal (oblique angle 1 signal)
20 Defect signal (Bevel angle 2 signal)
W Steel bill (inspected object)
d Defect

Claims (5)

A defect detection apparatus for detecting defects existing inside the surface layer of an inspection object using ultrasonic waves,
An internal portion that is arranged on the surface of the object to be inspected and that sends out ultrasonic waves to the inside of the object to be inspected along a direction perpendicular to the surface, and at least a surface layer of the object to be inspected A first probe having a wave receiving portion for receiving the ultrasonic wave reflected and returned by the defect existing on the surface of the object to be inspected, and the first probe with respect to the surface A transmission unit that transmits ultrasonic waves into the inspected object along a direction oblique to the probe, and an ultrasonic wave reflected and returned by a defect existing inside including at least the surface layer of the inspected object A second probe having a wave receiving portion for receiving a sound wave, and disposed on the surface of the object to be inspected, along a direction oblique to the first probe with respect to the surface Including a sending section for sending ultrasonic waves into the inspected object, and at least a surface layer of the inspected object Includes a third probe and a reception unit which receives ultrasonic waves reflected back by defects present, to,
The second probe sends out an ultrasonic wave toward a propagation region where the ultrasonic wave sent out by the sending unit of the first probe propagates, and the third probe sends the first probe to the first probe. A flaw detection region is formed by transmitting an ultrasonic wave toward a region where an ultrasonic wave propagation region transmitted by the probe and an ultrasonic wave propagation region transmitted by the second probe intersect. ,
The first probe, the second probe, and the third probe are movable on the surface of the object to be inspected, and move 3 on the surface of the object to be inspected. It is configured to change the position of the flaw detection area formed by intersecting ultrasonic waves transmitted from two probes
The defect detection apparatus characterized by the above-mentioned. The surface of the object to be inspected is composed of a plurality of surfaces,
The first probe is disposed on a first side surface which is one surface of the object to be inspected;
The second probe is disposed on a second side surface which is a surface adjacent to one side of the first side surface, and transmits ultrasonic waves toward the first side surface;
The third probe is arranged on a third side surface that is a surface adjacent to the other side of the first side surface, and transmits ultrasonic waves toward the first side surface. The defect detection apparatus according to claim 1. A defect detection method for detecting a defect existing inside a surface layer of an inspection object using ultrasonic waves,
An ultrasonic wave is transmitted from the surface of the object to be inspected to the inside of the object to be inspected along a direction perpendicular to the surface, and is a defect that exists at least inside the surface of the object to be inspected. A first probe step for receiving the reflected ultrasonic wave;
From the surface of the object to be inspected, an ultrasonic wave is sent into the object to be inspected along a direction oblique to the ultrasonic wave sent in the first probe step with respect to the surface, A second probe step of receiving the ultrasonic wave reflected and returned by the defect existing inside including at least the surface layer of the object to be inspected;
From the surface of the object to be inspected, an ultrasonic wave is sent into the object to be inspected along a direction oblique to the ultrasonic wave sent in the first probe step with respect to the surface, A third probe step of receiving the ultrasonic wave reflected and returned by the defect existing inside including at least the surface layer of the inspection object;
It said first feeler step, the defect detection step of detecting a defect existing in the interior, including a surface layer of the test subject based on the ultrasonic waves received at the higher second feeler step and the third probe Sawako and, the Bei example,
The second probe step sends out an ultrasonic wave directed to a propagation region where the ultrasonic wave sent out by the sending unit of the first probe propagates, and the third probe step includes the first probe step. Sending ultrasonic waves toward the area where the ultrasonic propagation area sent out in the probe process and the ultrasonic propagation area sent out in the second probe process intersect to form a flaw detection area,
As the first probe, the second probe, and the third probe move on the surface of the object to be inspected, the ultrasonic waves transmitted from the three probes intersect with each other. A defect detection method , comprising: changing a position of the formed flaw detection area. The second probe step acquires a distance to a defect existing inside including the surface layer of the inspection object based on the received ultrasonic wave,
The third probe step acquires the distance to the defect existing inside the inspection object based on the received ultrasonic wave,
The surface subcutaneous defect detection step uses the distance to the defect obtained in the second probe step and the distance to the defect obtained in the third probe step, and The defect detection method according to claim 3 , wherein the position of a defect existing inside including the surface layer is detected. The first received intensity of the ultrasonic wave received in the first probe process is acquired, the second received intensity of the ultrasonic wave received in the second probe process is acquired, and the third probe is acquired. A third received intensity of the ultrasonic wave received in the touching process is acquired, and the object to be inspected is obtained using the acquired first received intensity, second received intensity, and third received intensity. 5. The defect detection method according to claim 3 , further comprising a defect state detection step of detecting a progress direction of defects existing inside including the surface layer.