JPS5885153A - Surface flaw detecting device for round bar - Google Patents

Abstract

PURPOSE:To detect surface flaws with excellent S/N along the whole circumference and length of a round bar by providing the flaw detection head with flaw probes for an inclined angle more than one that transmit ultrasonic wave by refracting it in the round steel bar by 30-60 deg. to the side with respect to the vertical line. CONSTITUTION:When facing the cross-section of a round steel bar 1 a ultrasonic wave 3 is directed obliquely to the side direction with respect to the vertical line, that is, with an inclination by an angle theta1 to the direction that is perpendicular to the axis of a round steel bar, by means of an oblique angle probe 2 from above, the ultrasonic wave 3 is divided at the surface 4 into a component that is transmitted in the round steel bar with a refraction angle theta and a component that is reflected by an angle theta1. When the ultrasonic wave that is transmitted in the round steel bar with the refraction angle theta and reaches the side face 5 of the round steel 1, and there is a surface flaw at the side face 5, reflection echo (defect echo) develops due to the surface flaw and it is detected as 6A. According to the present invention, surface flaws of a round steel bar can be detected with excellent S/N round the whole circumference and the whole length.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface flaw detection device for rod-shaped objects such as round bars (hereinafter referred to as round steel).

Recently, the quality requirements for round steel have become more and more sophisticated), and 4IiFK has become stricter in terms of surface flaws in round steel. Surface flaws on round steel have traditionally been inspected using various non-destructive testing devices such as eddy current flaw detection devices and magnetic flaw detection devices, but these devices are generally expensive;
In addition, all of these methods inspect surface flaws from the surface side of the round steel, that is, from the outside of the round steel, so when detecting surface flaws that are shallow from the surface, it is necessary to check the irregularities and properties of the round steel surface. Detection signal/noise (hereinafter 8/N
Currently, there is no flaw detection device that fully satisfies the required level of 10 rows, because the probability of overlooking defects increases.

The present invention has been made in view of these points, and instead of the conventional method of detecting surface flaws from the outside of a round steel, it provides an apparatus for detecting surface flaws from the inside of a round steel. It consists of a transfer device that rotates and moves the round steel in the longitudinal direction, and an ultrasonic flaw detection head installed in the transfer line by this transfer device. Lateral to the perpendicular [3
The present invention relates to an apparatus for detecting surface flaws in a round steel from inside the round steel, which is equipped with one or more bevel probes that propagate ultrasonic waves by refraction of G to 60 degrees.

The structure of this device is extremely simple, so it is inexpensive.
In addition, since surface flaws on round steel are detected from inside the round steel, the influence of irregularities and properties on the surface of round steel can be greatly reduced, and even surface flaws with a shallow depth from the surface can be detected with a good 8/N stability. It has the great advantage of being able to perform flaw detection.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing the principle of the present invention, and FIG. 2 is a diagram showing the principle of the present invention.

FIG. 3 and FIG. 4 are diagrams showing an ultrasonic flaw detection head, a buffer mechanism, and a conveying device according to the present invention, respectively, and FIG. 5 is a diagram showing the detection results of surface flaws by the device of the present invention. 91
As shown in the figure, when the round steel 1 is viewed in cross section, the bevel probe 2 is tilted from above by an angle θ1 to the side with respect to the perpendicular line, that is, in the direction orthogonal to the axis of the round steel 1. When the ultrasonic wave 3 is incident obliquely on the surface 4 of the square steel 1, the ultrasonic wave 3 is divided into a component that propagates inside the round steel at a refraction angle of 0 and a component that is reflected at a reflection angle l. Most of this reflected component does not return to the probe 2, but a portion of it is diffusely reflected by small irregularities on the surface of the round steel 1 and returns to the probe, resulting in four reflected echoes (surface echoes). The width of this surface echo 4A is usually about 10 to 15, and even if there is a surface flaw on the surface 4 of the round steel 1, the surface flaw echo will fall within the width of the surface echo 4A and will be treated as a defect echo. It cannot be detected. However, the ultrasonic wave propagated inside the round steel at the refraction angle θ and reached the side surface 5 of the round steel 1! 1, if there is a surface flaw 6 on this side surface 5, the shape of the surface flaw is generally complex, so it always has a component that reflects the ultrasonic wave 5 to the probe 2. echo) is generated and can be detected as 6A.

In this case, the ultrasonic wave 6 that reached the side surface 5 of the circle-1 is reflected inside the round steel at the same reflection angle θ as the incident angle θ, so no reflected echo is generated, and the defective echo 6 due to the surface flaw 6 is reflected inside the round steel. Since only this occurs, there is no dead zone at all and detection can be performed with an extremely good S/N ratio.

Since the flaw detection W of the ultrasonic beam 3 emitted from the angle probe 2 is generally about 10 to 20, when testing the entire circumference of the round steel 1, it is necessary to rotate the nine copper 1 or What is necessary is to rotate the feeler 2 around the round steel 1.

Furthermore, since the shape of the surface flaw 6 is generally complex, depending on its directionality, the component that reflects the ultrasonic wave 3 toward the probe 2 may be very small. If equipped with a probe that emits ultrasonic waves in the opposite direction to the ultrasonic waves, the surface to be probed can be detected from the opposite direction, allowing the detection of areas with large reflected components of surface flaws, regardless of the shape or direction of the surface flaw. It is effective to set the refraction angle according to the present invention to more than 30 degrees and less than 40 degrees, which can be detected with high sensitivity.
If the temperature is less than 100 degrees, reflected echoes from the side surface 5 of the round steel 1 may occur, making it difficult to detect surface flaws. Moreover, when the angle exceeds 60 degrees, the ultrasonic wave 601 propagates on the surface of the round steel 1 as a surface wave, and this surface wave detects irregularities on the surface of the round steel, resulting in an increase in noise components, reducing the B/N. It will be necessary to do so.

FIG. 2 is a diagram showing an ultrasonic flaw detection head. The flaw detection head has a shell 7 on its bottom surface, and a wall 21 is provided to surround the shell 7. It is equipped with an oblique angle probe 2. Probe 2 and round steel 1 are: L-7
Therefore, a gap of about K11Ls■ is normally maintained, and the flaw detection water supplied from the water supply port 8 flows while forming a water film between these gaps.

Therefore, the incidence of ultrasonic waves from the probe 2 to the round steel 1 can be maintained extremely stably. This flaw detection head has a simple structure and is compact, with a total length of about 120 mm. Furthermore, even if the size of the round steel changes, this device is structured so that it can be handled simply by replacing the seam 7.

FIG. 5 is a diagram illustrating the buffer mechanism of the flaw detection head.

The flaw detection head 9 is installed to be able to move up and down via a drive device of an air cylinder 10, and when the round bar 1 is transferred and its tip reaches the installation position of the head, the drive device [1
0, connect the head 9 to the outer peripheral surface of the round steel 1, and press the round w4
After completing the flaw detection at the rearmost part of the head 9, the scoop head 9 is retracted to its original position by the scoop drive device 10. The vertical vibration that occurs when the round bar 1 is transferred is transmitted to the driving device 1 using an air cylinder via a gimbal mechanism 14 and two parallel link mechanisms 11.
0, and left and right vibrations are tracked by a rotating mechanism 12°13*2oA.

20B and 2QC are bins.

FIG. 4 is a plan view showing the entire apparatus of the present invention, which includes a material feeding bed 15, a feeding device 16 (hereinafter referred to as a flaw detection table) that rotates and conveys the discharged round steel in the longitudinal direction, and
It consists of a flaw detection head 9 for flaw detection on the round steel transported by a flaw detection table 16, and a wood collection floor 1B for storing the round steel after flaw detection. Further, a PLO device 19 for detecting the conveyance rotation speed of the round steel is installed at the end of the drive shaft of the flaw detection table, and the flaw detection head 9 is attached to the flaw detection stand 17.

The round steel discharged from the material supply bed 15 is transferred by the flaw detection table 16, and when the tip of the round steel reaches the flaw detection head, the flaw detection head 9 is brought into contact with the round steel to start flaw detection.

After that, when the rear end of the round steel is transported to the flaw detection head 9, it is separated from the round steel by the flaw detection head 9t, and based on the pass/fail results of the flaw detection, the passed material is placed in the good material pocket, and the rejected material is placed in the defective material pocket. The wood is distributed on the wood collection floor 18. The position of the surface flaw on the round steel detected by the flaw detection head 9 is detected from the rotation feed pitch of the PLO device 19 installed at the end of the drive shaft of the flaw detection table 16, and the position of the surface flaw on the round steel detected by the flaw detection head 9 is detected. The site can be marked with a marking device (not shown) to reveal the location of the surface flaw.

The device of the present invention detects surface flaws in round steel using a method in which ultrasonic waves are propagated obliquely inside the round steel, that is, by the bevel method. All certain defects are detected.

In general, both surface flaws and internal flaws in round steel are equally harmful, so they do not pose a problem for defect detection, but especially when it is necessary to distinguish whether a surface flaw is an internal defect, the path from the surface echo to the defect echo is In other words, when the ultrasonic wave 3 propagates through the round steel 1 at a refraction angle θ as shown in Fig. 1, the path A from the beam incidence point to the side surface is as follows, where D is the diameter of the round steel. A = D C (IIθ), and in the case of a surface flaw, a defect echo appears near this path.Therefore, a defect echo that appears at a location as short as this path can be determined to be an internal defect.Also, it is difficult to distinguish between a surface flaw and an internal defect. It is also possible to investigate the area marked using the above-mentioned marking device.

This flaw detection device detects flaws around the entire circumference and entire length of the circular saw while rotating and transporting the round steel with a fixed probe. The depth of the surface flaw and the depth of 8.
FIG. 7 is a diagram showing the relationship with 7N. From this, surface flaws with a depth of 0-2wm or more from the surface can be detected at 8/N1Gd1 or more.

As described above, according to the device of the present invention, it is possible to stably detect surface flaws on round steel with a good 8/N over the entire circumference and entire length, and the device is inexpensive. It is extremely effective as a quality assurance device.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the principle of the device of the present invention, Figures 2 and 3.
FIG. 4 is a diagram showing the entirety of the ultrasonic flaw detection head, slow bonding mechanism, and flaw detection device according to the device of the present invention, and FIG. 5 is a diagram showing the results of surface flaw detection of round steel by the device of the present invention. 1: Round steel 1 Parallel link mechanism 2: Oblique angle probe 12.15: Rotating mechanism + S: Ultrasound Ultrasonic
14 Nishinpal mechanism 4: Maru f1401NVl
1s: Material supply floor 5: Side surface of round steel 16: Feeding device 6: Surface flaw 17: Flaw detection stand 7: -18: Material collection floor 8: Water supply port 19: PLG device 9: Flaw detection head 21: Wall body 10 :Drive device applicant Nippon Steel Corporation

Claims (1)

[Claims] There is a transfer device that moves the round bar in the length direction while rotating it, and an ultrasonic flaw detection head that is installed in the transfer line of this transfer device so that it can move forward and backward. - and a wall surrounding this island -, and inside the wall of Jin, there is a side [30
A surface flaw detection device for a round bar, which is equipped with one or more oblique angle probes that propagate ultrasonic waves by refraction of up to 60 degrees, and detects surface flaws in the round bar from inside the bar. .