JP2005037407A - Ultrasonic defect detection method, and ultrasonic flaw detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an detecting method of flaws ultrasonic, capable of flexibly following the positional fluctuations of a material to be inspected during feed and capable of simply extending a flaw detecting region, and an ultrasonic flaw detector. <P>SOLUTION: In the ultrasonic flaw detecting method, the respective vibrators of an array probe are vibrated while shifting the exciting timings of the vibrators at a predetermined time interval to generate ultrasonic waves in the advance direction having an angle from a right-angled direction on the surface of the array probe and the predetermined time interval is altered at each irradiation with ultrasonic waves to change the advance direction of ultrasonic waves, while providing an overlap with respect to the previously generated ultrasonic waves, to perform the setting of a flaw gate corresponding to the shape of the material to be inspected at every irradiation with ultrasonic waves. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic flaw detection technique for detecting an internal defect of a material to be inspected by irradiating the material to be inspected with ultrasonic waves.

  Shaped steel such as rails is produced by rolling a steel piece heated to 1300 degrees or more through a hole mold between upper and lower rolling rolls called a caliber. The rolled rail is cut to a predetermined length and cooled, but the shape of the rail is not uniform, and the cooling rate varies from part to part, so that bending occurs at the time of cooling. This bending is corrected by a roller straightening machine in which rolls are arranged in a staggered manner. The rail whose curvature has been corrected by the roller straightening machine is transported after inspecting its length, shape, etc., and surface defects and internal defects are inspected during this transport. Then, both ends are cut off and aligned to a predetermined length, and those that need to be bent are corrected.

  Of the quality inspection performed in the series of manufacturing processes described above, ultrasonic flaw detection is generally used for inspection of internal defects, and the following two methods are used as ultrasonic flaw detection techniques for rails during conveyance. Are known.

  One method is to mount an ultrasonic probe (hereinafter referred to as a “probe”) in a holder, place the holder in contact with the material to be inspected, and distance between the surface of the material to be inspected and the probe. This is a method for flaw detection while maintaining a constant value. This method includes a local immersion method in which the holder is filled with water and ultrasonic waves are irradiated to the material to be inspected through the water, and a split type probe as a probe without using water in the holder. There is a gap method using.

  Another method is called the water column ultrasonic method. A certain distance is provided between the holder to which the probe is attached and the material to be inspected, and water is drawn from the holder to which the probe is attached. The water column is formed between the holder and the material to be inspected, and the rail is irradiated with ultrasonic waves through the water column for flaw detection.

Furthermore, the technique disclosed in Patent Document 1 proposes a mechanism that can easily adjust the angle of the probe holder so that the surface reflection echo is maximized when positioning the probe holder on the material to be inspected. Has been.
Japanese Patent Laid-Open No. 10-282069

  Of the methods for flaw detection by attaching the probe to the holder and attaching the holder to the material to be inspected, the gap method keeps the gap between the probe and the surface of the material to be inspected as small as about 0.5 mm. In addition, it is necessary to prevent multiple reflection echoes between the surface of the material to be inspected and the probe from entering the receiving side from the ultrasonic transmission side by the projection of the shielding plate that is the acoustic dividing surface of the split type probe. is there.

  By the way, in the rail, the scale of the rail surface produced at the time of rolling is destroyed by passing through the roller straightening machine for correcting the bending, so that the rail is easily peeled off. Therefore, if a surface property with a surface scale floating is detected, the projection on the shielding plate is shaved and consumed, and the projection on the shielding plate is easily damaged, making it difficult to keep it healthy for a long time. It becomes. If the projections on the shielding plate are damaged, multiple reflection echoes between the rail surface and the probe enter the receiving side from the ultrasonic wave transmitting side, increasing noise and making it impossible to perform highly reliable flaw detection.

  On the other hand, the local water immersion method does not cause a problem such as damage to the shielding plate. However, when a material to be inspected with a surface scale floating like a rail is inspected, the scale peeled off from the rail surface during the inspection is in the holder. As a result of the multiple reflection of ultrasonic waves between the scale and the surface of the material to be inspected or between the scale and the probe to generate noise, there is a problem that highly reliable flaw detection cannot be performed.

  As described above, in the method for flaw detection by bringing the holder into contact with the material to be inspected, a method for performing highly reliable ultrasonic flaw detection has not yet been established for the material to be inspected whose surface scale is easily peeled off.

  In the water column ultrasonic method, the problem of noise due to the mixing of the above-mentioned peeling scale does not occur, but the shape of the water column changes due to the position fluctuation of the material to be inspected in the vertical and horizontal directions. Noise may occur due to reflection in the water column. On the other hand, the probe holder must always move accurately following the material to be inspected while maintaining a predetermined distance from the material to be inspected, but this requires a scanning control device and the equipment cost is high. Become.

  Therefore, there has been a demand for a copying mechanism that can flexibly follow the position variation of the material to be inspected while being conveyed by a simple mechanism.

  Furthermore, in the technique disclosed in Patent Document 1, when presetting the probe holder with respect to the material to be inspected, the angle is adjusted so that the surface reflection echo is maximized corresponding to the rail type of each rail. In this case, however, the angle adjustment mechanism and a function for controlling the probe are required for each probe, and the mechanism becomes complicated. In order to widen the flaw detection cover range of the rail cross section, it is necessary to attach a large number of probes having such a mechanism, which not only makes the apparatus large, but also increases the manufacturing cost of the apparatus.

  The present invention has been made in view of such circumstances, and uses a method in which a holder is brought into contact with a material to be inspected to detect flaws, and is highly reliable for a material to be inspected whose surface scale is easily peeled off. To provide an ultrasonic flaw detection method and a flaw detection device that can perform ultrasonic flaw detection, can flexibly follow position fluctuations of a material to be inspected during conveyance, and can easily expand a flaw detection area. Objective.

  The ultrasonic flaw detection method according to claim 1 according to the present invention for solving the above-described problem is that the array probe is oscillated while shifting the excitation timing of each transducer of the array probe at a predetermined time interval. While generating ultrasonic waves in the traveling direction with an angle from a right angle on the surface of the probe, and further changing the predetermined time interval for each ultrasonic irradiation to overlap the previously generated ultrasonic waves By changing the traveling direction of the ultrasonic wave, the defect gate is set in accordance with the shape of the non-inspection material for each ultrasonic irradiation.

  Moreover, the ultrasonic flaw detection apparatus according to claim 2 of the present invention penetrates the inspection target material provided with an ultrasonic probe holder for inspecting an internal defect of the inspection target material being conveyed. A mechanism frame, a scanning roll which is provided opposite to a side surface of the mechanism frame and abuts on both side surfaces of the material to be inspected with a predetermined pressure; and the mechanism frame is arranged in the horizontal direction of the cross section of the material to be inspected And a slide mechanism that allows the mechanism frame to follow the movement of the cross-section of the material to be inspected so as to be movable.

  According to a third aspect of the present invention, in the ultrasonic flaw detector according to the first aspect of the present invention, another probe holder that can be moved up and down from above the material to be inspected is disposed. The upper frame, a scanning roll provided on the lower surface of the upper and lower sides of the upper frame and supplementing the upper surface of the material to be inspected, and the upper frame movable in the vertical direction of the cross section of the material to be inspected. And a link mechanism that follows the upper frame in accordance with the vertical movement of the material to be inspected.

  According to a fourth aspect of the present invention, in the ultrasonic flaw detector according to the above-described invention, the material to be inspected is a rolled rail.

  According to the present invention, it is possible to flexibly follow a change in position of a material to be inspected during conveyance, and it is possible to easily expand a flaw detection area.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an ultrasonic flaw detector according to the present invention will be described using a rail ultrasonic flaw detector as an example.

  FIG. 1 is a front view of an ultrasonic flaw detector according to the present invention, and FIG. 2 is a side view.

  In FIG. 1 and FIG. 2, tracks 32a and 32b are laid on the base surface in a direction perpendicular to the conveying direction of the rail 1 as the material to be inspected, and the carriage 3 traveling on the tracks 32a and 32b is The wheels 31a, 31b, 31c, 31d provided on the lower surface can move in the left-right direction in FIG.

  Hereinafter, the traveling direction of the carriage will be described as the left-right direction.

  Slide mechanisms 7a, 7b, 7c, and 7d are disposed on the carriage 3, and the mechanism frame 2 is loaded on the slide mechanisms 7a, 7b, 7c, and 7d so as to be movable in the left-right direction. Centering devices 8a and 8b composed of air cylinders for moving the mechanism frame 2 to a predetermined position are provided at the left and right ends of the carriage 3.

  The mechanism frame 2 is formed in a rectangular parallelepiped shape, and has an opening in at least two directions in the front and rear direction of the rail 1 so that the rail 1 is transported through the inside of the mechanism frame 2.

  Hereinafter, the conveyance direction of the rail 1 will be described as the front-rear direction.

  A lifting device 4 having a pulse motor 41 is provided on the ceiling of the mechanism frame 2, and ball screws 42 a, 42 b, 42 c, 42 d that mesh with a rotation shaft of the pulse motor 41 via a gear mechanism (not shown) are provided. The provided lifting frame 43 is suspended inside the mechanism frame 2 by screwing ball screws 42 a, 42 b, 42 c, 42 d into the screw holes of the lifting device 4.

  An air cylinder 44 is mounted on the lifting frame 43 with the rod 45 facing downward, and the upper frame 5 is parallel to the ceiling surface of the mechanism frame 2 at the tip of the rod 45 penetrating the lifting frame 43. It is connected. Further, the upper frame 5 is connected to the respective fulcrum portions installed on the ceiling of the mechanism frame 2 by parallel link mechanisms 51a, 51b, 51c, 51d.

  The copying rolls 52a and 52b are attached to the lower surfaces of the front and rear end portions of the upper frame 5, and the arm 91 for connecting the head detection flaw holder 9 of the rail 1 so as to be rotatable at one end thereof, for the head side of the rail 1. The other ends of the arms 101 and 111 for connecting the flaw detection holders 10 and 11 at one end thereof and the arm 121 for connecting the flaw detection holder 12 for the web of the rail 1 at one end thereof are rotatably connected to the upper frame. 5 is pivotably connected to each fulcrum part installed at 5.

  Further, an arm 131 for rotatably connecting the sole flaw detection holder 13 of the rail 1 at one end thereof is rotatably connected to a fulcrum portion provided on the bottom surface portion on the bottom surface of the mechanism portion 2. ing.

  Further, air cylinders 61a, 61b, 61c, 61d are attached by inserting a rod shaft into the inner surface of the mechanism portion 2 at a total of four positions on the front and rear end portions of the left and right side surfaces of the mechanism portion 2, and the rod shaft ends. Are provided with copying rolls 62a, 62b, 62c, and 62d for contacting and copying the foot side portion of the rail 1. These air cylinders and copying rolls constitute rail supplement mechanisms 6a, 6b, 6c and 6d.

Next, the operation of the flaw detection apparatus will be described.
As a preparatory operation for starting the flaw detection of the rail 1, by driving the wheels 31a, 31b, 31c, 31d with a motor (not shown), the carriage 3 is moved in the left-right direction on the rails 32a, 32b, and the rail 1 is conveyed. Position the table so that the center of the table is at a predetermined position of the mechanism frame 2. This operation is called a line insertion operation. The reverse operation is called a line extraction operation.

Subsequently, a preset operation for the type of rail 1 (rail type) is performed.
When the rail type of the rail 1 is set through a control device (not shown), the pulse motor 41 is rotated according to the setting value stored in the control device in advance, and thereby the ball screws 42a, 42b, 42c, and 42d are rotated. The lift frame 43 is moved up and down by the rotation of the ball screws 42a, 42b, 42c, and 42d, but the upper frame 5 and the lift frame 43 are connected via the shaft of the air cylinder 44 mounted on the lift frame 43, so The frame 5 also moves up and down integrally with the lifting frame 43.

  Then, the upper frame 5 is set at a position that matches the height dimension of the rail 1 to be flawed. Here, the upper frame 5 is connected to the mechanism frame 2 via parallel link mechanisms 51a, 51b, 51c, 51d. For this reason, the upper frame 5 can be kept horizontal even when it is lifted and lowered by the lifting mechanism 4.

Next, the flaw detection operation of the rail 1 is started.
When the rail 1 is conveyed into the mechanism frame 2 from the direction of the arrow A shown in FIG. 2, the air cylinders 61a and 61c of the left and right catching mechanisms 6a and 6c at the timing when the tip of the rail 1 passes the left and right copying rolls 62a and 62c. The left and right copying rolls 62a and 62c are moved forward, pressed against the rail 1 and captured, and held with a predetermined pressure applied.

  If the center of the rail 1 moves in the left-right direction from the center of the mechanism frame 2, for example, if the rail 1 moves in the direction of the copying roll 62a, the force acting on the copying roll 62a is transmitted via the rail supplementary mechanism 61a. Acting on the mechanism frame 2. As a result, the mechanism frame 2 moves on the slide mechanisms 7a and 7c in the right direction in FIG. 1 and stops at a position where the center of the rail 1 and the center of the mechanism frame 2 coincide. In this way, the mechanism frame 2 can be made to follow the left and right movement of the rail 1.

  In addition to the copying operation of the mechanism frame 2, the air cylinder 44 is operated to lower the upper frame 5 to bring the upper copying roll 52 a into contact with the top of the rail 1. Copy 5

  Further, each time the rail 1 passes a predetermined position in accordance with the progress of the rail 1, the arm 91, the arm 131, the arm 121, the arm 101, and the arm 111 are operated by an air cylinder (not shown), respectively. A sole flaw detection holder 13, a web flaw detection holder 12, and head side flaw detection holders 10 and 11 are brought into contact with the rail 1.

  The flaw detection holder 9 and the arm 91 for the head, the flaw detection holder 13 and the arm 131 for the sole, the flaw detection holder 12 and the arm 121 for the web, the flaw detection holder 10 and the arm 101 for the head side, and the flaw detection holder 11 and the arm 111 for the head side are respectively gimbal. It is connected by a mechanism so that it can follow the angle change of the contact surface with the rail 1.

  In this embodiment, since the local water immersion method is adopted, water is supplied to the flaw detection holder 9 for the head, the flaw detection holder 13 for the sole, the flaw detection holder 12 for the web, and the flaw detection holders 10 and 11 for the head side. It ejects from the contact surface with the rail 1.

  FIG. 3 shows a state in which the head flaw detection holder 9, the sole flaw detection holder 13, the web flaw detection holder 12, and the head side flaw detection holders 10 and 11 are attached to the rail 1 in the cross-sectional direction of the rail 1. FIG.

  In this way, the ultrasonic waves emitted from the ultrasonic probes attached in the respective holders of the flaw detection holder 9 for the head, the flaw detection holder 13 for the sole, the flaw detection holder 12 for the web, and the flaw detection holders 10 and 11 for the head side are contained in the holder. The rail 1 is irradiated through the water supplied to, and the flaw detection operation is started.

  Further, the air cylinders 61b and 61d of the left and right capturing mechanisms 6b and 6d are operated at the timing when the rail 1 advances and the tip passes through the left and right scanning rolls 62b and 62d, and the left and right scanning rolls 62b and 62d are moved forward to the rail 1. Press to capture and hold it under a certain pressure.

  If the center of the rail 1 moves in the left-right direction from the center of the mechanism frame 2, for example, when the rail 1 moves in the direction of the copying roll 62b, the force acting on the copying roll 62b is transmitted via the rail supplementary mechanism 61b. Acting on the mechanism frame 2. As a result, the mechanism frame 2 moves on the slide mechanisms 7b and 7d in the right direction in FIG. 1 and stops at a position where the center of the rail 1 and the center of the mechanism frame 2 coincide.

Next, the flaw detection end operation of the rail 1 will be described.
At the timing when the rear end of the rail 1 passes through the left and right scanning rolls 62a and 62c, the left and right scanning rolls 62a and 62c are moved backward by operating the air cylinders 61a and 61c of the left and right capturing mechanisms 6a and 6c. Even when the left and right catching mechanisms 6a and 6c release the catch, the left and right catching mechanisms 6b and 6d still catch the rail 1 with the left and right copying rolls 62b and 62d, so that the mechanism frame 2 follows the left and right movement of the rail 1. Can do.

  Further, each time the rear end of the rail 1 passes a predetermined position, the arm 91, the arm 131, the arm 121, the arm 101, 111 are operated by an air cylinder (not shown), and the head flaw detection holder 9 and the sole flaw detection are performed. The holder 13, the web flaw detection holder 12, and the head flaw detection holders 10 and 11 are separated from the rail 1.

  Then, at the timing when the rear end of the rail 1 passes through the left and right scanning rolls 62b and 62d, the air cylinders 61b and 61d of the left and right capturing mechanisms 6b and 6d are operated to retract the left and right scanning rolls 62b and 62d to release the capture of the rail 1 To do.

  Thereafter, the air cylinders of the centering devices 8a and 8b are operated to return the position of the mechanism frame 2 to the center of the carriage 3, that is, the center of the table carrying the rail 1 in the width direction to prepare for flaw detection of the next material.

  The flaw detection over the entire length of the rail 1 is performed by the above operation. According to the present embodiment, since the probe holder can be accurately followed even when the position of the rail 1 changes during conveyance, the ultrasonic waves of the rolled rail being conveyed by the roller table can be obtained. The flaw detection can be performed stably. Furthermore, since it is not necessary to provide a copying mechanism for each flaw detection holder, the configuration of the apparatus does not become complicated. In addition, since the probe holder position can be preset in a short time even if the rail type of the rail for performing ultrasonic flaw detection is changed, the work efficiency for changing the rail type is improved.

Next, before describing the noise removal method using the peeling scale according to the present invention, a noise generation mechanism using the scale will be described.
In general, ultrasonic flaw detection for inspecting internal defects of a metal body irradiates the metal body with ultrasonic waves emitted from a probe through an acoustic medium such as water, and propagates ultrasonic waves inside the metal body. A defect gate is set in a time range in which an ultrasonic wave passes through a flaw detection range inside the metal body, and an ultrasonic wave reflected from the defect inside the metal body is detected in the defect gate time range to determine the defect.

  FIG. 4 is a diagram for explaining a noise generation mechanism using a scale.

  When the foreign object 203 exists in the acoustic medium between the probe 201 and the metal body 202, the ultrasonic wave T emitted from the probe 201 is reflected by the foreign object 203 and reaches the probe 201 as an echo E1. . On the other hand, the ultrasonic wave T that has not been reflected by the foreign matter 203 is reflected by the surface of the metal body and becomes a surface echo S to reach the probe 201. Further, a part of the surface echo S is reflected by the foreign matter 203, and the echo E2 reflected by the surface of the metal body reaches the probe 201.

FIG. 5 is a diagram illustrating the behavior of the ultrasonic wave with the transmission / reception waveform of the probe 201.
The reflected echo E2 from the foreign object 203 appears at a symmetrical position on the time axis with respect to the echo E1 directly reflected by the foreign object 203 with the surface echo S reflected on the surface of the metal body as the center. As a result, the echo E2 is detected within the time range of the defective gate and becomes noise.

  During the flaw detection of the rail 1, the flaw detection holder 9 for the head, the flaw detection holder 13 for the sole, the flaw detection holder 12 for the web, and the flaw detection holders 10 and 11 for the head side are in contact with the rail 1, so that the surface of the rail 1 The scale adhering to the surface peels off and enters the holder, and noise is generated by the mechanism described above.

FIG. 6 is a diagram for explaining a noise generation prevention method using a peeling scale.
FIG. 6 shows a state where the head-side flaw detection holder 10 is in contact with the head side surface of the rail 1. The inside of the head-side flaw detection holder 10 is filled with water supplied as an acoustic medium, and flows out from the gap between the head-side flaw detection holder 10 and the rail 1.

  A transmitting member 205 that transmits ultrasonic waves emitted from the probe 201 is attached to the inside of the head-side flaw detection holder 10 with a small gap from the surface of the rail 1. As the material of the transmitting member 205, it is desirable to use a material having an acoustic impedance equivalent to that of water, such as an acrylic resin.

  In general, when an ultrasonic wave is incident on materials having different acoustic impedances, the ultrasonic wave is reflected at the boundary surface. For this reason, if the acoustic impedance differs greatly, the energy of the incident ultrasonic wave is attenuated and the flaw detection ability is lowered.

  Here, according to the results of investigations by the inventors, it has been confirmed that when acrylic resin is used as the transmission member, the attenuation of ultrasonic waves is not particularly problematic, and the flaw detection ability comparable to the conventional one is exhibited. It was.

  Assuming that the acoustic impedance of water is about 3.7 and the acoustic impedance of acrylic is about 3.3, the transmission member can be used in the present invention as long as its acoustic impedance is up to about 3.0. Conceivable. When the acoustic impedance of water is 1, the acoustic impedance of the transmission member is a value corresponding to about 0.8. Therefore, it is desirable that the acoustic impedance of the transmissive member be in the range of 0.8I to 1.2I, where I is the acoustic impedance of water.

  In addition, considering that the acoustic impedance of iron as the material to be inspected is about 45.3 and the acoustic impedance of water as the acoustic medium is a difference of a dozen times, ultrasonic flaw detection is possible. It is estimated that the range of the acoustic impedance of the transmissive member is not limited to the case where the acoustic medium is water, and can be applied to an acoustic medium that is normally used in the local water immersion method.

  A through-hole for supplying water in the head-side flaw detection holder 10 between the transmission member 205 and the rail 1 is appropriately provided at a position outside the sound field of the transmission member 205. As a result, even when the scale 203 peeled off from the rail 1 enters between the probe 201 and the rail 1 and in the sound field of the ultrasonic wave T, the scale 203 is not connected between the transmission member 205 and the rail 1. Will exist only in That is, it exists only in the vicinity from the surface of the rail 1 and does not enter the inside of the head-side flaw detection holder 10. Accordingly, an ultrasonic wave is reflected multiple times between the scale 203 and the rail 1 and an echo E2 is generated. However, since the echo E2 is incident on the probe 201 before the start of the defective gate, it is detected in the defective gate. It does not become noise.

  In this embodiment, the distance d between the rail 1 and the transmission member 205 is important. In general, the speed of sound in water is 1480 m / sec and the speed of sound in steel is 5960 m / sec, so the speed of sound in steel is about four times that in water. This means that if the time range of the defective gate is determined so that the interval d in water is the dead zone, the dead zone of the steel material being the inspection material is expanded to 4d.

  Therefore, if the interval d is increased in order to reduce the influence of the scale 203 intrusion, the dead zone of the rail 1 also increases. Therefore, in this embodiment, the distance d is set to be ¼ or less of the surface dead zone of the rail 1.

  The thickness of the transmissive member 205 is not particularly limited. However, since the acoustic impedance of the transmitting member 205 is not the same value as that of water, it is desirable that the transmission member 205 is thin considering the propagation of ultrasonic waves. Accordingly, the thickness of the holder is not limited as long as it is strong enough to shield the inside and outside of the holder against the water supply pressure.

  According to the present embodiment, even when the surface scale peels off as in the case of flaw detection on a rolled rail, noise due to the scale can be avoided and the defect detection ability can be improved.

  Next, a method for simply changing and expanding the flaw detection cover range of the rail cross section will be described. Before that, the operation of the probe used in this embodiment will be described.

FIG. 7 is a diagram for explaining a method of emitting ultrasonic waves from an ultrasonic probe in which six transducers are arranged in an array (hereinafter referred to as “array probe”).
When the vibrator V1, the vibrator V2, the vibrator V3, the vibrator V4, the vibrator V5, and the vibrator V6 are excited at the same time, these wavefronts are combined and perpendicular to the sound wave emitting surface of the ultrasonic probe. Ultrasound will be fired.

  Here, when the vibrator V1, the vibrator V2, the vibrator V3, the vibrator V4, the vibrator V5, and the vibrator V6 are sequentially excited while being delayed by a minute time Δt1, these wavefronts are synthesized and ultrasonic probe is performed. An ultrasonic wave is emitted from the direction perpendicular to the sound wave emitting surface of the child in the direction of angle θ1.

  Similarly, when excitation is performed while delaying by a minute time Δt2 (Δt1 <Δt2), an ultrasonic wave is emitted in a direction of an angle θ2 (θ1 <θ2) from a direction perpendicular to the sound wave emitting surface of the ultrasonic probe.

  In addition, when excitation is performed in the order of the transducer V6, the transducer V5, the transducer V4, the transducer V3, the transducer V2, and the transducer V1 while being delayed by a minute time Δt1, the direction perpendicular to the sound wave emitting surface of the ultrasonic probe Is emitted in the direction of the angle −θ1.

  Similarly, when excitation is performed while being delayed by a minute time Δt2 (Δt1 <Δt2), an ultrasonic wave is emitted in a direction of an angle −θ2 (θ1 <θ2) from a direction perpendicular to the sound wave emission surface of the ultrasonic probe.

  As described above, when the vibrators V1, V2, V3, V4, V5, and V6 are excited while being delayed by a minute time, the sound wave emitting surface of the ultrasonic probe is applied. An ultrasonic wave having an angle can be emitted from a right angle direction, and the angle can be changed according to the minute time.

  Therefore, by using the array probe and oscillating while shifting the excitation timing of each transducer of the array probe at a minute time interval, the surface of the array probe is moved in the direction of travel from the right angle. By generating ultrasonic waves and changing the time interval of ultrasonic waves at a high speed while changing the minute time interval for each ultrasonic irradiation and overlapping with the previously generated ultrasonic waves, the probe An arbitrary flaw detection range can be selected without changing.

  If the distance to the bottom surface of the metal body changes depending on the direction in which the ultrasonic waves are emitted from the ultrasonic probes in which the transducers are arranged in an array, the distance to the bottom surface of the metal body in advance for each ultrasonic wave emission direction. If the gate is set according to the distance, the flaw detection cover range of the cross section of the metal body can be expanded.

FIG. 8 is a diagram for explaining flaw detection on the top of the rail 1 using an array probe.
FIG. 8 shows a state in which the top flaw detection holder 9 is in contact with the rail 1. The inside of the parietal flaw detection holder 9 is filled with water supplied as an acoustic medium, and flows out from the gap between the parietal flaw detection holder 9 and the rail 1.

  An array probe Ha and an array probe Hb are incorporated in the parietal flaw detection holder 9. First, when all the transducers of the array probe Ha are excited simultaneously, an ultrasonic wave Ta1 is emitted. In FIG. 8, the ultrasonic irradiation range is expressed up to the end point of the defect gate set in the flaw detection range of the cross section of the rail 1 in the traveling direction of the ultrasonic wave Ta1.

  Next, the excitation timings of the individual transducers of the array probe Ha are vibrated while being shifted by a minute time interval, and an ultrasonic wave Ta2 having an overlap with the ultrasonic wave Ta1 is emitted. In this case as well, a defect gate is set in the flaw detection range of the cross section of the rail 1 in the traveling direction of the ultrasonic wave Ta2.

  In the same manner, the ultrasonic transducers Ta3, Ta4, and Ta5 that have been made to overlap with the previously irradiated ultrasonic waves are emitted by changing and shifting the minute time intervals of the excitation timing of the individual transducers of the array probe Ha. Let

  Similarly, the ultrasonic waves Tb1, Tb2, Tb3, Tb4, and Tb5 that are made to vibrate by changing the minute time interval of the excitation timing of the individual transducers of the array probe Hb and shifting the previous ultrasonic waves are overlapped. To fire.

  As described above, the traveling direction of the ultrasonic wave is changed at a high speed while overlapping with the previously generated ultrasonic wave, and a defect gate that matches the shape of the rail is set in advance for each ultrasonic irradiation. Thus, the flaw detection range along the shape of the neck portion of the rail 1 can be set.

  In this embodiment, the array probe is provided with two elements Ha and Hb. However, the number of array probes is determined by a trade-off with the flaw detection time. The present invention is not limited to this configuration, and one array probe may be configured, or three or more array probes may be configured.

  In the present embodiment, the array probe is attached to the inside of the parietal flaw detection holder 9, but it is attached to any of the sole flaw detection holder 13, the web flaw detection holder 12, and the cranial flaw detection holders 10, 11. It may be a thing.

  According to the present embodiment, since the flaw detection cover range of the rail cross section can be greatly expanded with a small number of probes, the apparatus is compact and the equipment cost can be reduced. In addition, since it is not necessary to adjust the position of the probe for each object to be inspected, work can be efficiently performed.

  As described above, when the present invention is applied, it is possible not only to perform highly reliable ultrasonic flaw detection in rail internal defect inspection, but also to improve the efficiency of inspection work.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

1 is a front view of an ultrasonic flaw detector according to the present invention. 1 is a side view of an ultrasonic flaw detector according to the present invention. The figure which shows the state in which the probe holder was materialized by the rail in the cross-sectional direction of a rail. The figure explaining the noise generation mechanism by a scale. The figure showing the behavior of an ultrasonic wave with the transmission and reception waveform of a probe. The figure explaining the noise generation prevention method by a peeling scale. The figure explaining the emission method of the ultrasonic wave from the ultrasonic probe which arranged six vibrators in the shape of an array. The figure explaining the flaw detection of the top of a rail using an array probe.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rail, 2 ... Mechanism frame, 5 ... Upper frame, 5a ... Copying roll, 51a ... Link mechanism, 61a ... Rail catching mechanism, 62a ... Copying roll, 7a ... Slide mechanism, 9 ... Head flaw detection holder, 10 ... Head Flaw detection holder for side, 11 ... flaw detection holder for head side, 12 ... flaw detection holder for web, 13 ... flaw detection holder for sole, 201 ... probe, 203 ... scale, 205 ... transmission member.

Claims (4)

Oscillating while shifting the excitation timing of each transducer of the array probe at a predetermined time interval to generate ultrasonic waves in the traveling direction having an angle from a right angle on the surface of the array probe;
Furthermore, the predetermined time interval is changed for each ultrasonic irradiation and the traveling direction of the ultrasonic wave is changed while overlapping with the previously generated ultrasonic wave,
An ultrasonic flaw detection method characterized in that a defect gate is set in accordance with the shape of a non-inspection material for each ultrasonic irradiation. An ultrasonic probe holder for inspecting internal defects of the material to be inspected during transportation, and a mechanism frame for penetrating the material to be inspected;
A scanning roll which is provided opposite to the side surface of the mechanism frame and is in contact with both sides of the material to be inspected with a predetermined pressure;
An ultrasonic flaw detection apparatus comprising: a slide mechanism that allows the mechanism frame to move in the horizontal direction of the cross-section of the material to be inspected and causes the mechanism frame to follow the movement of the cross-section of the material to be inspected in the horizontal direction. An upper frame in which another probe holder is disposed, which can be raised and lowered from above the material to be inspected;
A copying roll that is provided on the lower surface of the upper frame on the entry side and the exit side and supplements the upper surface of the material to be inspected;
3. The link mechanism according to claim 2, further comprising a link mechanism that allows the upper frame to move in the vertical direction of the cross section of the material to be inspected, and that causes the upper frame to follow the movement in the vertical direction of the cross section of the material to be inspected. Ultrasonic flaw detector. 4. The ultrasonic flaw detector according to claim 2, wherein the material to be inspected is a rolled rail.

Images