JPH02114114A - Detection of internally ground shape of weld part of seam welded pipe - Google Patents

Abstract

PURPOSE:To enable accurate detection of an internally ground shape of a weld part of a seam welded pipe by arranging a pair of linear array probes sandwiching a welding line to perform an overlap processing of position information measured with an alternate switching thereof. CONSTITUTION:A pair of linear array probes 3 and 4 are arranged along the circumferential direction of the seam welded pipe 1 at positions as opposed to each other centered on a weld bead part 2 on the outside of the seam welded pipe 1. Transmitting and receiving sections 5 and 6 have a function of transmitting and receiving transmitting and receiving signals of the probes 3 and 4 and the transmission and reception thereof are controlled by mutual switching by a measurement control section 7. With the mutual switching by the measurement control section 7, one of vibrators of the probes 3 and 4 is scanned sequentially to emit an ultrasonic beam to an internal bead grinding section 2a at a certain emission angle and reflected wave is received with the other vibrator of the probes 3 and 4 to measure time between the emission and reception of the beam with a measurement control section 7 and a position of the receiving vibrator. These signals measured with the alternate switching undergo an overlap processing with an arithmetic section 8 to display 9 the results of the processing.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for detecting the internally ground shape of a welded portion of an electric resistance welded tube.

<Conventional technology> ERW pipes are made by forming a band plate into an open pipe at -nF7, welding the abutting portions along the tube axis direction, and grinding the convex portions on the inner and outer surfaces of the weld bead portion with a cutting tool. After being smoothed and subjected to shaping and boss annealing, it is cut into desired lengths to produce products.

By the way, monitoring and optimizing the grinding status of the weld bead on the inner and outer surfaces is an important factor in manufacturing ERW pipes, and the grinding status of the outer bead can be easily monitored visually by an operator or with a camera. Yes, it is already in practical use.

On the other hand, regarding the monitoring of the internal bead grinding status, for example, as disclosed in Utility Model Application Publication No. 58-24062, an internal cutting tool attached to the tip of a rond protruding long into the oven pipe from the position of the oven pipe before welding is used. Means for providing a detector for detecting the inner surface layer of the tube at the tip, and Japanese Patent Application Laid-Open No. 56-35
A method such as that disclosed in Publication No. 057 in which an ultrasonic thickness gauge disposed on the outer periphery of a pipe is periodically moved in the circumferential direction of the pipe around the inner bead part, and the trajectory of the thickness is used to form the shape of the internal grinding. etc. have been proposed.

<Problems to be Solved by the Invention> However, the former method of Utility Model Application No. 58-24062 is difficult to install in the case of a small-diameter tube, and in order to install the detector inside the tube, There are problems such as contamination by bits generated during welding, making accurate detection impossible.

On the other hand, in the latter method of JP-A No. 56-35057, it is important to detect the bead immediately after it is cut after welding and feed it back to the position control of the inner bit. It is necessary to place an ultrasonic thickness needle.

However, since the temperature of the weld bead is usually as high as 300° C. or higher, it is extremely difficult with the current technology to bring the ultrasonic thickness needle into contact with the outer surface of the tube via acoustic coupling water. It should be noted that using a large amount of acoustic coupling water as a countermeasure against this problem results in rapid cooling of the bead cut section, which is a serious problem from the viewpoint of the quality of the weld bead section.

In order to solve these five problems, for example, the literature [Ultrasonic Synthetic Aperture Imaging (Non-Destructive Testing, Vol. 36, No. 10,
Published in May 1988, P, 742-747) J
It is possible to measure the inner surface profile by applying ultrasonic flaw detection from the outer surface of the tube, as introduced in .

However, in this method, since it is necessary to scan the ultrasonic probe so as to position it above the inner bead, there is a problem similar to that of the method of the above-mentioned Patent I7n No. 56-35057. Further, if a weld bead remains on the outer surface and the ultrasonic probe rides on it, there is a problem that acoustic coupling water is not retained and measurement cannot be performed. Furthermore, there is a problem in that the apparatus required to perform calculation processing of the synthetic aperture is complicated and expensive.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method suitable for detecting the internally ground shape of a welded portion of an electric resistance welded pipe.

Means for Solving the Problem> The present invention provides a method for detecting the internal grinding shape of an electric resistance welded pipe in which the welded bead is ground with a bead cutter after welding the abutting portion along the pipe axis direction. A pair of linear array probes are arranged along the circumferential direction at opposing positions centering on the weld bead portion on the outer surface of the sewing tube,
One linear array probe is used as the oscillation side, and the ultrasonic beam is oscillated while its transducer is scanned. Detect the reflected wave and obtain the position information of the reflection point, then switch between the linear array probe on the oscillating side and the linear array probe on the receiving side to transmit and receive in the same way (δ) to detect and reflect the reflected wave. This is a method for detecting the internal grinding shape of an electric resistance welded pipe welded part, which is characterized by obtaining positional information of a point, and then superimposing the positional information of these reflection points to obtain a grinding profile.

Below, a specific configuration of the present invention will be explained using FIG. 1.

FIG. 1 is a configuration diagram showing an embodiment of an internal grinding shape detection device for a welded portion of an electric resistance welded pipe according to the present invention.

In the figure, a pair of linear array probes 3.4 are placed at opposing positions centering on the weld bead 2 on the outer surface of the ERW tube l.
are arranged along the circumferential direction of the ERW tube 1.

The transmitting/receiving section 5.6 has a function of transmitting and receiving signals transmitted and received by the linear array probe 34, and the alternating switching between transmission and reception is controlled by the measurement control section 7.

The calculation unit 8 has a function of calculating and superimposing the signals measured by alternate switching, and the processing results are displayed on the display 9.

The linear array probe 3゜4 used here is described, for example, in the document "Nondestructive Testing (Vol. 35, No. 9).

As described in No. 667i) J, any ultrasonic beam may be used as long as it can scan an ultrasonic beam over a wide range by controlling the phase of the oscillation timing of each transducer.

<For production> The operation of the present invention will be explained below.

In the internally ground type depression detection device shown in FIG.
For example, assume that the skimp points are the same value, such as 0.5 skip.

Then, the transducer of one linear array probe 3 is sequentially scanned to oscillate an ultrasonic beam at a certain emission angle to the inner bead grinding portion 2a, and the other linear array probe 4 receives reflected waves.

At this time, the measurement control unit 7 measures the time (distance) from oscillation to reception of the ultrasonic beam and the position of the received transducer on the receiving side linear array probe 4.

In this way, the emission angle and injection position of the ultrasonic beam.

By measuring the incident position and the time until the incident (distance j!tI), the calculation unit 8 determines the position of the reflection point of the reflected wave.

Now, as shown in Fig. 2, the measurement surface is represented by the plane coordinates of the y-axis and the y-axis, and the coordinates of the injection point F1 are (x+, y
+), the coordinates of the incident point F, are (X,.

y8), the coordinates of the reflection point R are (χ, y), and the injection angle with respect to the normal ■ of the injection point F1 passing through the center point 0 of the ERW tube l is α, and the y-axis and the normal V The intersection angle is β, and the distance between the emission point F1 and the incident point 1 + the y-axis of z is F, the transmission tm distance of the ultrasonic beam, that is, the emission point F, → reflection reflection point 2
Make money.

Therefore, if the polar coordinates of the reflection point R of the reflected wave are (r, θ), then the position of the reflection point R mentioned above! The relationship with ff(x.y) can be expressed as follows.

x ”' r cos θ −−゛゛゛−−(+)y
=rsin θ ・− ・−〜ーー・−・・・−・−
・・−・−・−・−(2) Here, θ−α+β.

The locus of this reflection point R is as shown in FIG.
, and the point of incidence F, that is, the propagation distance NL of the ultrasonic beam, if we apply the definition of an ellipse in which the propagation distance NL of the ultrasonic beam is 11η along a constant locus, the ellipse E can be used to approximate the ultrasonic beam. That is, injection point F.

By using polar coordinates (r, θ) where F is the pole and F and −x are the raw cotton, the distance Nr can be expressed by the following equation (3).

r=p/ (1+εcos θ) −−−−1・−・
--------1 (3) Here, P: Half of the straight line ε: Eccentricity Now, if the short side of this ellipse E is a and the long side is b, then they are as follows (4) , expressed by equation (5).

a=L/2 −−−・−・・−・−・−−−−−・
−−−−−・−・−・− 441b=172fi lower
−−−・・−−−(5) Also, the randomness ε of this ellipse E is ε= (1/a), /7Y]]T = F/L Furthermore, half of the straight line p is: p=b”/a=(L”+F”)/2 L---
-(7) Therefore, the above equation (3) can be expressed by all known values as shown in the following equation (8).

r = (L"1-F") / (2 L+
Fcos θ) The r. By substituting θ into the above (+) and (21), the coordinates of the reflection point R (x
,y) can be calculated.

In this way, the scanning of the transducer of one linear array probe 3 is completed, and the reflection point R of the reflected wave is
After performing arithmetic processing on the coordinates (x, y) of and obtaining positional information, the measurement control unit 7 controls switching control j to oscillate an ultrasonic beam from the other linear array probe 4 and receive it at the linear array probe 3. In this way, the calculation section 8
Similar arithmetic processing is performed to obtain position information.

Furthermore, by superimposing the position information of both in the calculation unit 8, even if one linear array probe cannot detect a part that is shadowed by the reflected wave, the other linear array probe Therefore, it is possible to obtain an accurate grinding profile of the inner bead grinding portion 2a with the shadow portion eliminated.

In the above description, the distance P from the center of the weld bead portion 2 to the linear array probes 3, 4 is, for example, 0.
-5 skip points were set, but considering the thermal influence from the weld bead portion 2, it is desirable to make the distance l as large as possible according to the skip distance of the ultrasonic beam.

<Example> Examples of the present invention will be described below.

Using the internal grinding shape detection device shown in Fig. 1, the outer diameter 1
60m of ERW pipe with 14.3mmφ and wall thickness of 9.52mm
It was applied to a production line that welds at winO pipe manufacturing speed.

The linear array probe used here had 64 elements (0,
5mm pitch) were placed facing the 1.5 skip point from the welding line, and the 12 elements were phase-controlled and excited so as to form an incident angle beam (45") synthesized by phase control. Linear array probe is 10kPRF
Since the ultrasonic beam is emitted at a rate of 10 times per second, one scan corresponds to 52 times, which is 192 scans/S. If you switch the linear array probe left and right to scan and make two scans into one screen, 96ii per second! j
You will get a surface.

Therefore, if we average the 16 screens, the length of the ERW tube will be 1
It can be measured every 66M.

An example of a 100-page display of the measurement results is shown in Figure 4 (
Shown in a) and (b).

FIG. 4(a) shows a case where the inner bead portion is properly ground, and the locus of the profile is almost continuous.

On the other hand, FIG. 4(b) shows that there is some residual grinding, but a break point is recognized in the locus of the profile.

This is because when measuring by cutting two linear array probes, the parts with large irregularities were in the shadow from both linear array probes and could not be detected, so when processing their position information to superimpose them, This is what was missing. However, it can be determined that there is some residual grinding from the entire profile.

Thereby, the weld bead grinding status can be monitored almost continuously. In addition, even if the profile changes drastically or dangerously due to, for example, missing bites, an alarm can be issued in less than 0.5 seconds, and the signal can also be fed and transmitted, so it can be used effectively for practical purposes. be able to.

<Effects of the Invention> As explained above, according to the present invention, a pair of linear array probes are arranged across a welding line, and the position information measured by switching them alternately is superimposed to perform internal bead grinding. Since the profile of the part is determined, it is possible to accurately detect the ground shape, which contributes to improving the quality and yield of the electric resistance welded pipe.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the internal grinding shape detection device according to the present invention, FIGS. 2 and 3 are explanatory diagrams showing the measurement principle of the present invention, and FIG. 4 is a diagram showing a measurement example. It is. 3.4...Linear array probe. 5.6...Transmission/reception unit, 7...Measurement control unit. 8... Arithmetic unit, 9... Display. ■...Erw pipe, 2...Weld bead part. 2a...Inner bead grinding part.

Claims (1)

[Claims] In a method for detecting the internal grinding shape of an ERW tube in which the butt portion along the tube axis direction is welded and the weld bead portion is ground with a bead cutter, the electrodes are opposite to each other centering on the weld bead portion on the outer surface of the ERW tube. A pair of linear array probes is placed along the circumferential direction at the position where one linear array probe is used as the oscillating side to oscillate an ultrasound beam while scanning its transducer, and the other linear array probe is used as the receiving side. While scanning the vibrator in synchronization with the oscillation cycle, the reflected wave is detected to obtain the positional information of the reflection point, and then the linear array probe on the oscillating side and the linear array probe on the receiving side are switched and the same process is performed. The inner surface of a welded part of an ERW pipe is characterized in that the position information of the reflection point is obtained by transmitting and receiving signals to and from the ERW pipe, detecting the reflected waves, and then superimposing the position information of these reflection points to obtain a grinding profile. How to detect grinding shape.