JP2012242160A - Ultrasonic flaw detection method of welded steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method of a welded steel pipe, which can accurately perform ultrasonic flaw detection of a welded part of the welded steep pile over the whole length of the welded steel pipe.SOLUTION: Ultrasonic flaw detection of a welded steel pipe is performed by using an ultrasonic flaw detection apparatus 3 including: a steel pipe support 4 for horizontally supporting a welded steel pipe 1; an ultrasonic probe 5 arranged above the steel pipe support; a probe lifting mechanism 6 for lifting the ultrasonic probe in a vertical direction; a probe transfer mechanism 7 for transferring the ultrasonic probe integrally with the probe lifting mechanism in an axial direction of the welded steel pipe; a probe position detection device 8 for detecting a probe position of the ultrasonic probe; an arithmetic unit 9 for calculating distances from the probe position detected by the probe position detection device up to both end parts of the welded steel pipe; and an initial flaw detection direction setting device 10 for setting a direction directing to the steel pipe end part of which the distance up to the ultrasonic probe is nearer out of both the end parts of the steel pipe as compared with the distance calculated by the arithmetic unit as an initial flaw detection direction.

Description

  The present invention relates to a method for ultrasonic flaw detection of a welded steel pipe such as an electric resistance steel pipe.

An electric resistance steel pipe is usually manufactured by bending a steel plate into a cylindrical shape and then welding and joining both end portions of the steel plate. For this reason, when a welded steel pipe such as an electric resistance steel pipe is shipped as a product, an ultrasonic flaw inspection is performed to confirm that no weld defect exists in the welded portion of the welded steel pipe.
As a method for ultrasonic flaw detection of welded steel pipes such as ERW steel pipes, all the ultrasonic probes are attached to the surface of the welded steel pipe, and then the degree of freedom of the ultrasonic probes is eliminated by the probe fixing device. There is known a method for ultrasonic flaw detection of a welded steel pipe by moving the welded steel pipe in the axial direction of the welded steel pipe (see Patent Document 1).

JP-A-6-58909

According to the above-described method, it is possible to ultrasonically detect the welded portion of the welded steel pipe over the entire length of the welded steel pipe. Therefore, there has been a problem that ultrasonic flaw detection cannot be performed accurately on the welded portion of the welded steel pipe.
Further, in order to specify the occurrence position of the welding defect, two measuring rolls formed in an annular shape are arranged before and after the ultrasonic probe, and the surface of the welded steel pipe is brought into contact with the inner peripheral surface of the measuring roll. Therefore, when the surface of the welded steel pipe is separated from the inner peripheral surface of the measuring roll due to the movement of the welded steel pipe, there is also a problem that the position where the welding defect occurs cannot be specified with high accuracy.

Further, when there is a place with a poor weld shape, there is a problem that the ultrasonic probe is separated from the surface of the welded steel pipe.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an ultrasonic flaw detection method for a welded steel pipe capable of accurately performing flaw detection on the welded portion of the welded steel pipe over the entire length of the welded steel pipe. To do.

  In order to achieve the above object, the present invention is a method for ultrasonic flaw detection of a welded steel pipe formed by welding both ends of a steel plate bent into a cylindrical shape, and ultrasonically flaws the welded steel pipe. As a device, a steel pipe support base that horizontally supports the welded steel pipe, an ultrasonic probe disposed above the steel pipe support base, a probe lift mechanism that drives the ultrasonic probe to move up and down, and the probe lift A probe transfer mechanism for transferring the ultrasonic probe in the axial direction of the welded steel pipe integrally with the mechanism, and a probe position detection for detecting the probe position of the ultrasonic probe transferred in the axial direction of the welded steel pipe by the probe transfer mechanism An apparatus, an arithmetic device for calculating a distance from the probe position detected by the probe position detection device to both ends of the welded steel pipe, and a distance calculated by the arithmetic device An ultrasonic flaw detection apparatus comprising: an initial flaw detection direction setting device that sets a direction toward the steel pipe end closer to the ultrasonic probe out of both ends of the welded steel pipe as an initial flaw detection direction. Use, after lowering the ultrasonic probe to contact the welded steel pipe, operating the probe transfer mechanism to move the ultrasonic probe in the initial flaw detection direction set by the initial flaw detection direction setting device, After the ultrasonic probe moves to the outside of the end of the welded steel pipe, the ultrasonic probe is lifted and the ultrasonic probe is transferred in the direction opposite to the initial flaw detection direction by the probe transfer mechanism. At the initial position, the ultrasonic probe is lowered and brought into contact with the welded steel pipe, and then the amount of movement of the ultrasonic probe is the total length of the welded steel pipe. Reach moving the ultrasonic probe in the axial direction of the welded steel pipe by the probe transport mechanism, characterized in that the ultrasonic testing of the weld steel pipe.

According to the present invention, it is possible to ultrasonically detect the welded portion of the welded steel pipe over the entire length of the welded steel pipe without moving the welded steel pipe. Since it does not shift | deviate, it can ultrasonically detect the welded part of a welded steel pipe with sufficient precision over the full length of a welded steel pipe.
In addition, it is possible to set the ultrasonic probe quickly by moving the ultrasonic probe in the initial flaw detection direction set by the initial flaw detection direction setting device. Therefore, the welded portion of the welded steel pipe can be welded in a relatively short time. Ultrasonic flaw detection can be performed over the entire length of the steel pipe.

It is a front view which shows an example of the ultrasonic flaw detector used for the ultrasonic flaw detection method of the welded steel pipe which concerns on this invention. It is a side view of the ultrasonic flaw detector shown in FIG. It is a top view of the ultrasonic flaw detector shown in FIG. It is a figure for demonstrating the ultrasonic flaw detection method of the welded steel pipe which concerns on one Embodiment of this invention.

Hereinafter, an ultrasonic flaw detection method for a welded steel pipe according to the present invention will be described with reference to the drawings.
First, an example of the ultrasonic flaw detection apparatus used for the ultrasonic flaw detection method of the welded steel pipe concerning this invention is shown in FIG.1, FIG.2 and FIG.3. 1 to 3, reference numeral 1 denotes a welded steel pipe, 2 denotes a welded portion of the welded steel pipe 1, 3 denotes an ultrasonic flaw detector, and the ultrasonic flaw detector 3 includes a steel pipe support 4, an ultrasonic probe 5, and a probe lifting mechanism. 6, a probe transfer mechanism 7, a probe position detection device 8, a calculation device 9, and an initial flaw detection direction setting device 10 are provided.

The steel pipe support 4 supports the welded steel pipe 1 horizontally, and this steel pipe support 4 has a plurality of turning rollers 11 that rotatably support the welded steel pipe 1. In addition, the steel pipe support 4 can be moved in the direction of the arrow in the figure by a conveyor (not shown).
The ultrasonic probe 5 performs ultrasonic flaw detection on the welded portion 2 of the welded steel pipe 1, and the ultrasonic probe 5 is disposed above the steel pipe support 4.

The probe elevating mechanism 6 drives the ultrasonic probe 5 up and down. The probe elevating mechanism 6 includes, for example, a ball screw (not shown) and a drive motor (not shown) for driving the ball screw. ing.
The probe transfer mechanism 7 is for integrally transferring the ultrasonic probe 5 in the axial direction of the welded steel pipe 1 together with the probe lifting mechanism 6. The probe transfer mechanism 7 is driven to rotate by, for example, a drive motor 12 and the drive motor 12. And a ball screw nut 14 that moves in the horizontal direction as the ball screw shaft 13 rotates.

The probe position detection device 8 detects the probe position of the ultrasonic probe 5 that is transferred in the axial direction of the welded steel pipe 1 by the probe transfer mechanism 7. The probe position detection device 8 is, for example, a drive motor for the probe transfer mechanism 7. 12 is configured to detect the probe position of the ultrasonic probe 5 by counting the pulse signals from the pulse generator 15 attached to 12.
The calculation device 9 calculates distances X1 and X2 from the probe position of the ultrasonic probe 5 to both ends of the welded steel pipe 1, and this calculation device 9 is based on the initial probe position detected by the probe position detection device 8. It is comprised so that it may calculate so that distance X1, X2 may be calculated.

  The initial flaw detection direction setting device 10 sets the direction toward the end of the steel pipe closer to the ultrasonic probe 5 among the both ends of the welded steel pipe 1 as the initial flaw detection direction. Is configured to compare the distances X1 and X2 calculated by the arithmetic unit 9 and to set the direction toward the end of the steel pipe closer to the ultrasonic probe 5 as the initial flaw detection direction. The initial flaw detection direction set by the initial flaw detection direction setting device 10 is supplied to a control device (not shown) that controls the probe transfer mechanism 7 and the like as information on the direction in which the probe is transferred when flaw detection is started. Yes.

FIG. 4 is a diagram for explaining an ultrasonic flaw detection method for a welded steel pipe according to an embodiment of the present invention. In the case where the welded portion 2 of the welded steel pipe 1 is subjected to ultrasonic flaw detection using the ultrasonic flaw detection apparatus 3 described above. First, the turning roller 11 is rotated by a roller drive mechanism (not shown) until the welded portion 2 of the welded steel pipe 1 is positioned directly above. At this time, the ultrasonic probe 5 is in the full length range of the welded steel pipe 1 and is waiting at a position close to any one of the pipe ends, spaced above the upper end surface of the steel pipe. This position is the initial position of the ultrasonic probe 5. The initial position is preferably a position close to the position where the previous steel pipe flaw detection is completed. This is because it is advantageous for shortening the probe transfer distance and shortening the time required for the flaw detection work.
At this position, as described above, the distances X1 and X2 between the ultrasonic probe 5 and both tube ends are measured, and the initial flaw detection direction setting device 10 is set with the direction toward the tube end having the shorter distance as the initial flaw detection direction. Set to. And the probe raising / lowering mechanism 6 is operated, and as shown to Fig.4 (a), the probe 5 and the welded steel pipe 1 are made to contact.

Next, the probe transfer mechanism 7 is operated to perform flaw detection while moving the ultrasonic probe 5 toward the initial flaw detection direction set by the initial flaw detection direction setting device 10 as shown in FIG.
When the ultrasonic probe 5 moves to the outside of the tube end, the operation of the probe transfer mechanism 7 is temporarily stopped. Next, the probe elevating mechanism 6 is operated in this state, and the ultrasonic probe 5 is raised and separated from the surface of the welded steel pipe 1 as shown in FIG.

Next, as shown in FIG. 4C, the probe transfer mechanism 7 is operated to move the ultrasonic probe 5 in the direction opposite to the initial flaw detection direction. When the ultrasonic probe 5 reaches the initial position, the ultrasonic wave is moved. The probe 5 is lowered again.
When the ultrasonic probe 5 is lowered to a position where it comes into contact with the surface of the welded steel pipe 1, the operation of the probe lifting mechanism 6 is stopped. Next, the probe transfer mechanism 7 is operated again, and the ultrasonic probe 5 is moved in the axial direction of the welded steel pipe 1 from the probe set position as shown in FIG. Then, the probe transfer mechanism 7 is operated until the moving amount of the ultrasonic probe 5 reaches the entire length of the welded steel pipe 1 to perform ultrasonic flaw detection on the welded steel pipe 1.
When ultrasonic flaw detection is performed on the next welded steel pipe 1, the welded steel pipe 1 is moved to a position below the ultrasonic flaw detector 3 and then the ultrasonic probe 5 is welded from the position indicated by the dotted line in FIG. The welded steel pipe 1 is subjected to ultrasonic flaw detection by moving in the axial direction of the steel pipe 1.

  As described above, the probe transfer mechanism 7 of the ultrasonic flaw detector 3 is operated to move the ultrasonic probe 5 toward the initial flaw detection direction set by the initial flaw detection direction setting device 10 so that the ultrasonic probe 5 is welded steel pipe. After moving from the end of 1 to the outside, the ultrasonic probe 5 is raised, and the ultrasonic probe 5 is transferred in the direction opposite to the initial flaw detection direction by the probe transfer mechanism 7 so that the ultrasonic probe 5 has reached the initial position. By the way, the ultrasonic probe 5 is lowered and brought into contact with the welded steel pipe 1, and then the ultrasonic probe 5 is moved in the axial direction of the welded steel pipe 1 by the probe transfer mechanism 7 until the moving amount of the ultrasonic probe 5 reaches the entire length of the welded steel pipe 1. By moving, the welded part 2 of the welded steel pipe 1 can be ultrasonically detected over the entire length of the welded steel pipe 1 without moving the welded steel pipe 1. Therefore, unlike the above-described conventional example, the position of the welded portion 2 is not shifted in the circumferential direction of the welded steel pipe 1 due to the movement of the welded steel pipe 1. Ultrasonic flaw detection can be performed with high accuracy.

In addition, the ultrasonic probe 5 can be quickly set by moving the ultrasonic probe 5 in the initial flaw detection direction set by the initial flaw detection direction setting device 10, and accordingly, the welded steel pipe 1 can be set in a relatively short time. The welded part 2 can be subjected to ultrasonic flaw detection over the entire length of the welded steel pipe 1.
Further, it is not necessary to arrange measuring rolls before and after the ultrasonic probe in order to specify the position where the welding defect occurs.
In the above-described embodiment of the present invention, the steel pipe support 4 that horizontally supports the welded steel pipe 1 is exemplified as having the plurality of turning rollers 11 that rotatably support the welded steel pipe 1, but is not limited thereto. The welded steel pipe may be supported horizontally by a steel pipe support that does not have a turning roller.

DESCRIPTION OF SYMBOLS 1 ... Welded steel pipe 2 ... Welded part 3 ... Ultrasonic flaw detector 4 ... Steel pipe support stand 5 ... Ultrasonic probe 6 ... Probe raising / lowering mechanism 7 ... Probe transfer mechanism 8 ... Probe position detection apparatus 9 ... Calculation apparatus 10 ... Initial flaw detection direction setting Device 11 ... Turning roller 12 ... Drive motor 13 ... Ball screw shaft 14 ... Ball screw nut 15 ... Pulse generator

Claims (1)

A method for ultrasonic flaw detection of a welded steel pipe formed by welding and joining both end portions of a steel plate bent into a cylindrical shape,
As a device for ultrasonic inspection of the welded steel pipe, a steel pipe support base that horizontally supports the welded steel pipe, an ultrasonic probe disposed above the steel pipe support base, and the ultrasonic probe is driven up and down in the vertical direction. A probe lifting mechanism, a probe transfer mechanism for transferring the ultrasonic probe in the axial direction of the welded steel pipe integrally with the probe lifting mechanism, and an ultrasonic probe transferred in the axial direction of the welded steel pipe by the probe transfer mechanism. The probe position detection device for detecting the probe position, the calculation device for calculating the distance from the probe position detected by the probe position detection device to both ends of the welded steel pipe, and the distance calculated by the calculation device are compared. First, the direction toward the end of the steel pipe that is closer to the ultrasonic probe among the both ends of the welded steel pipe is set as the initial flaw detection direction. Using an ultrasonic flaw detector and a flaw orientation device,
After the ultrasonic probe is lowered and brought into contact with the welded steel pipe, the probe transfer mechanism is operated to move the ultrasonic probe in the initial flaw detection direction set by the initial flaw detection direction setting device, and the ultrasonic wave After the probe moves to the outside from the end of the welded steel pipe, the ultrasonic probe is raised and the ultrasonic probe is transferred in the direction opposite to the initial flaw detection direction by the probe transfer mechanism, and the ultrasonic probe is moved to the initial position. The ultrasonic probe is lowered and brought into contact with the welded steel pipe, and then the ultrasonic probe is moved by the probe transfer mechanism until the moving amount of the ultrasonic probe reaches the entire length of the welded steel pipe. An ultrasonic flaw detection method for a welded steel pipe, wherein the welded steel pipe is ultrasonically flawed by moving in an axial direction.

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