JPS61273273A - Inner face bead detecting device on welding zone of electric welded pipe - Google Patents

Abstract

PURPOSE:To enable the detection of the projection quantity of the inner face bead by scanning an ultrasonic wave from the outer face side of a pipe and by providing the timer circuit and memory circuit to measure and store respectively the differential detecting timing of the outer face reflecting wave and inner face reflecting wave on the welding zone as well. CONSTITUTION:The detecting device is composed of a detecting head 13, gate 18, timer circuit 19, memory circuit 20 and arithmetic circuit 21, control circuit 22. A probe 11 transmits in the prescribed pitch to welding zone 5 an ultrasonic wave nu from the outer face side of an electric welded pipe 4 and detects the outer face reflecting wave and inner face reflecting wave on the welding zone 5. The timer circuit 19 measures the time difference in the detecting timing of the outer face reflecting wave and the detecting timing of the inner face reflecting wave via the gate 18. The projection quantity of the inner face bead 6 is then operated by the arithmetic circuit 21 based on the data stored in the memory circuit 20. The projection quantity of the inner face bead 6 is thus detected.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides an electric resistance welding tube that can detect the inner bead of an electric resistance welded tube welded portion from the outer surface of the electric resistance welded tube and determine its protrusion amount. The present invention relates to an inner bead detection device of the section.

[Prior art and its problems]

In the conventional use of electric resistance welded pipes, it is not a problem even if the inner bead of the welded part or the inner bead remains due to rough cutting. However, recently, there is a growing demand for applications in which the remaining inner bead is not allowed, such as for cylinders. In electric resistance welded pipes for such applications, it is required to sufficiently cut the inner bead, but as there has been no suitable inner bead detection device, it has not been possible to determine the amount of protrusion of the inner bead and whether it remains after cutting. Currently, the amount of protrusion of the inner bead is checked manually.

Most conventional devices for detecting the amount of protrusion of the inner bead detect it from the inner surface of the electric resistance welded tube as described below. That is, in the conventional detection device shown in FIG. As shown in the figure, the electric resistance welded tube 4 is moved in a direction perpendicular to the axial direction, and the amount of protrusion of the inner bead 6 is detected from the amount of expansion and contraction of the contact bar 2 at that time. In another conventional detection device shown in FIG.
is irradiated toward the inner surface of the welding part 5, an optically sectioned image of the inner surface bead 6 and its surrounding area characterized by the slit light 8 is captured by the imaging tube 9, and the obtained image signal is processed by the signal processing device 10. The amount of protrusion of the inner bead 6 is determined by processing.

As described above, the conventional detection device detects the amount of protrusion of the inner bead 6 from the inner surface of the ERW tube 4, so there is no problem when the diameter of the ERW tube 4 is large. However, when it is small, it is difficult to set up the detection device and it is difficult to detect the amount of protrusion of the inner bead 6.

For this reason, there is a strong desire to develop a detection device that can detect the inner bead of an ERW pipe weld from the outside of the ERW pipe, but such a detection device has not yet been proposed. do not have.

[Purpose of the invention]

In view of the above-mentioned current situation, it is an object of the present invention to provide a detection device capable of detecting the inner bead of a welded portion of an ERW tube from the outer surface side of the ERW tube, and determining the amount of protrusion thereof.

[Summary of the invention]

The inner bead detection device for a welded portion of an ERW tube according to the present invention applies ultrasonic waves from the outer surface side of the ERW tube to the weld portion where the outer bead of the ERW tube is cut at a right angle to the axial direction of the ERW tube. a detection head for transmitting waves while scanning at predetermined intervals in a direction, and for receiving external reflected waves from the outer surface of the welding part and internal reflected waves from the inner surface of the welding part of the transmitted ultrasonic waves; and a first gate circuit for detecting the inner surface reflected wave received by the detection head, and a second gate circuit for detecting the outer surface reflected wave received by the detection head. , a timer circuit for measuring a time difference in detection timing between the detection timing of the internal reflected wave by the first gate circuit and the detection timing of the external reflected wave by the second gate circuit;
a memory circuit for storing the time difference between the detection timings measured by the timer circuit in correspondence with the position of the welded part from which the ultrasonic wave was transmitted; The present invention is characterized in that it comprises a calculation circuit for calculating the amount of protrusion of an inner bead formed on the inner surface side of the welded portion from data on the time difference between the detection timings stored in the circuit.

[Structure of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The inner bead detection device for a welded portion of an electric resistance welded pipe according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the inner bead detection device of the present invention. As shown in FIG. 1, the inner bead detection device of the present invention includes a detection head 13 consisting of a focusing globe 11 and a driving device 12, and a pulser 1.
4, a receiver 15, a gate 18 consisting of a first gate circuit 16 and a second gate circuit 17, a timer circuit 19, a memory circuit 20, an arithmetic circuit 21, and a control circuit 22. .

The focused probe 11 of the detection head 13 is placed on the outer surface of the welded part 5 where the outer bead of the ERW tube 4 is cut, via an ultrasonic propagation medium (a harpoon). The ultrasonic wave ν is transmitted from the outer surface side to the welding part 5 in a predetermined scanning pinch, and the outer surface reflected wave from the outer surface of the welded part 5 and the inner reflected wave from the inner surface of the welded part 5 of the transmitted ultrasonic wave ν are transmitted. The focal point Wf globe 1 should preferably have a beam diameter as small as possible.In order to improve detection stability, it is desirable that the diameter φ of P1 satisfies ψ≦W/3 with respect to the bead width wK.Driving The device 12 reciprocates the globe 11 in a direction perpendicular to the axial direction of the ERW tube 4, and causes the ultrasonic waves transmitted from the probe 11 to scan the welded portion 5 over a predetermined width. As shown in FIG. 2(a), upon receiving an initial pulse e1 instructing the start of detection from the control circuit 22, the rope 11 is moved to a position corresponding to the end of the scanning width, and thereafter the globe 11 is scanned. Drive continuously across the width.

The control circuit 22 outputs necessary signals such as the initial pulse e to control each part of the detection device.

The nozzle generator 14 applies a pulse voltage to the vibrator of the blower f11 to generate ultrasonic waves. ) 4 Luthor 14 is
As shown in FIG. 2(b), when a trigger pulse e2 outputted following the initial pulse e1 is received from the control circuit 22, a pulse voltage is generated. Welded part 50 by ultrasonic waves
Scanning at a predetermined pitch is carried out by the drive device 12 using the shibe lobe 11.
This is done by driving the oscillator of the globe 11 and applying a pulse voltage from the pulser 14 to the vibrator of the globe 11 at predetermined time intervals.

The receiver 15 receives the external reflected waves and the internal reflected waves by the transducer of the probe 11, and receives the external reflected waves.
As shown in FIG.

The first gate circuit 16 of the f-to 18 receives the external reflected wave II.
? The pulse voltage e is detected and, as shown in FIG. 2(d), the detected pulse voltage e of the external reflected wave is output. gate 1
The second gate circuit 17 of 8 detects the pulse voltage e4 of the internally reflected wave, and outputs the detected pulse voltage e6 of the internally reflected wave as shown in FIG. 2(e).

As shown in FIG. 2(f), the timer circuit 19 is activated by the detection pulse e of the external reflected wave output from the first gate circuit 16, and It is started and stopped by the detection pulse e6 of the internal reflected wave,
A time difference t in detection timing between the detection timing of the external reflected wave and the detection timing of the internal reflected wave is measured. The time difference measurement of the detection timing as described above is performed for all the ultrasonic waves transmitted at a predetermined scanning pitch to the welding part 5, and data of the time difference tn of each time is obtained.

The memory circuit 20 stores data on the time difference tn between the detection timings obtained by the timer circuit 19 in correspondence with the position of the welding part 5 to which the ultrasonic wave was transmitted.

The data of the time difference tn between the detection timings stored in the memory circuit 20 represents the inner surface shape of the welded portion 5 as shown in FIG. It represents the amount of protrusion relative to the surrounding area.

The calculation circuit 21 calculates the difference Δt based on the data of the time difference tn of the detection timing stored in the memory circuit 20, and then calculates the protrusion amount of the inner bead 6 from Δt based on the following formula (1). .

Protrusion amount of inner bead "Co・Δt/2...
(1) However, C0: Ultrasonic longitudinal wave propagation velocity of the electric resistance welded pipe pipe material Note that the ultrasonic propagation velocity C0 is affected by temperature, which may cause an error in detecting the protrusion amount of the inner bead 6. sometimes,
The calculation of the amount of protrusion of the inner bead by the calculation circuit 21 is preferably performed as follows. That is, the time difference t8 shown as the third factor corresponds to the wall thickness of the normal portion of the electric resistance welded pipe 4, and on the other hand, this wall thickness is measured in a process before pipe forming.

Using this time difference t8 and wall thickness, the ultrasonic propagation velocity Co can be expressed as Co=2D/tB, so
The above formula (1) can be converted to the following (2) without using the ultrasonic propagation velocity C0.
) can be written as the formula.

Projection amount of inner bead 5=D・Δ1/1. ...(
2) Therefore, by calculating the amount of protrusion of the inner bead 6 based on equation (2), the amount of protrusion can be determined regardless of the ultrasonic propagation velocity C1.

When detecting the amount of protrusion of the inner bead 6 using the detection device described above, the detection accuracy depends on the time measurement resolution and the waveform stability of the ultrasonic reflected wave. There is no problem with technology. Regarding the waveform stability of the ultrasonic reflected wave, a known AGC method is applied to the receiver 15,
A significant improvement can be achieved by using the first gate circuit 16 and the second gate circuit 17 in the receiving system to eliminate the influence of amplitude fluctuations of the reflected ultrasound waves. According to the detection device with such improvements, the protrusion amount detection accuracy of the inner bead 6 can be improved by
It can be approximately o, i itx.

FIG. 4 is a block diagram showing another embodiment of the inner bead detection device of the present invention. The inner bead detection device shown in FIG. 4 differs from FIG. According to the drive device 12 shown in FIG.
) This is different from a detection device that mechanically drives the f a-p 11 to scan ultrasonic waves. Other configurations are the first
This is the same detection device as shown in the figure.

That is, in the detection device shown in FIG.
Pulsar Circuit Array 2 by Torigano Yarus from
A pulse voltage is selectively applied from 4 to the transducer elements of the globe 23 to generate ultrasonic waves while giving an appropriate delay time to each transducer element. Scan at a predetermined scanning pitch. In the receiving system, the probe 2 receives commands from the control circuit 22.
Only the third transducer element is selected by the multi-brephther 25, and the pulse voltage of the external reflected wave and the pulse voltage of the internal reflected wave from the transducer element are selectively guided to the receiver 15. Hereinafter, similarly to the detection device shown in FIG. 1, the pulse voltage of the external reflected wave received by the receiver 15 is detected by the first gate circuit 16 of the gate 18, and the pulse voltage of the internal reflected wave is detected. 2nd) The 1'-1 circuit 17 detects the signal, and the timer circuit 19 measures the time difference between the detection timings. Then, the time difference between the detection timings is stored in the memory circuit 2o in correspondence with the ultrasonic wave transmission position of the welding part 5, and based on the data of the stored time difference between the detection timings, the arithmetic circuit 21 uses the The amount of protrusion of the pin 6 is calculated.

〔Effect of the invention〕

Since the present invention is configured as described above, the inner bead of the welded portion of the electric resistance welded tube can be detected from the outer surface side of the electric resistance welded tube, and the amount of protrusion thereof can be determined.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the detection device of the present invention, FIGS. 2(a) to (f) are time charts showing time difference detection in the detection device of FIG. 1, and FIG. ,
FIG. 1 is an explanatory diagram showing the memory contents stored in the memory circuit of the detection device, FIG. 4 is a block diagram showing another embodiment of the detection device of the present invention, and FIG. 5 is a diagram showing a conventional detection device. FIG. 6 is an explanatory diagram showing a method for detecting the protrusion amount of the inner bead using another conventional detection device. In the drawing,

Claims (1)

[Scope of Claims] Ultrasonic waves are sent from the outer surface of the ERW tube to the welded portion where the outer bead of the ERW tube is cut, while scanning at predetermined intervals in a direction perpendicular to the axial direction of the ERW tube. a detection head for receiving external reflected waves from the outer surface of the welding part and internal reflected waves from the inner surface of the welding part of the transmitted ultrasonic waves; a first gate circuit for detecting the inner surface reflected wave received by the detection head; and a second gate circuit for detecting the outer surface reflected wave received by the detection head; a timer circuit for measuring a time difference in detection timing between a detection timing of a reflected wave and a detection timing of the external reflected wave by the second gate circuit; and a time difference between the detection timings measured by the timer circuit. a memory circuit for storing the data in correspondence with the position of the welded part from which the ultrasonic wave was transmitted; and data of the time difference between the detection timings stored in the memory circuit in correspondence with the position of the welded part. an arithmetic circuit for calculating the amount of protrusion of the inner bead generated on the inner surface side of the welded portion, and an inner bead detection device for an electric resistance welded pipe welded portion.