JPH01265155A - Eddy current test equipment for pipe - Google Patents

Abstract

PURPOSE:To reduce the vibration of a pipe and to improve the detectability by switching a carrying machine of an eddy current test equipment to a belt conveyor system. CONSTITUTION:The overall constitution of an eddy current test equipment of a pipe is provided with carrying machines 40, 50 on both sides of a detection coil 2, and by the carrying machines 40, 50, a pipe to be inspected 7 is allowed to pass through the inside of the detection coil 2, and an eddy current test is executed. The pipe 7 is moved into an entry belt conveyor 3 by a kicker 8 from a test piece plate. The pipe 7 is carried by its conveyor 3, passes through a guide 10, and thereafter, brought to eddy current test by the detection coil 2, passes through a guide 23, and fed out onto a belt conveyor 17. Thereafter, the pipe 7 is moved out by a kicker 24. By switching to the belt conveyor system, the vibration of the pipe is reduced, and by following it up, the detectability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to equipment for performing eddy current flaw detection on pipes such as steel pipes using a penetrating coil.

(b) Prior Art Penetrating eddy current flaw detection methods are well known. In this penetrating eddy current flaw detection method, one of the problems when testing tubes is that the defect detection ability is reduced due to noise caused by conveyance vibration.

First, an alternating current is supplied to the bridge 102 by a transmitter 101, which will explain the signal flow of the eddy current flaw detection device with reference to FIG. The bridge 102 has a detection coil 10
3 is included.

An alternating current flows through the detection coil 103. The detection coil 103 interacts with a weak current induced in the article to be inspected 104, and its impedance changes depending on the state of the article to be inspected 104. The impedance change of the detection coil 103 is converted into an electric signal by the bridge 102, and the bridge 1
Generates a signal at the output of 02. Since the output signal of the bridge 102 is generally very small, it is converted into a large signal by the amplifier 105.

The output signal of the bridge 102 includes a signal due to scratches and noise generated due to changes in other factors. This noise is subjected to signal processing by the synchronous detector 106 and the filter 107.

Here, the phase shifter 108 suppresses the noise signal by synchronous detection, which is a type of phase analysis, by utilizing the phase difference between the signal caused by the scratch on the boat and the noise caused by the carrier vibration. Especially when detecting minute defects, the filter 10 after synchronous detection
No. 7 cannot suppress conveyance noise, which is a major factor in reducing the defect detection ability of current eddy current flaw detection devices.

Descriptions of other circuit configurations will be omitted.

Figure 5 shows the arrangement of a general eddy current flaw detection device.

All conventional tube conveyance systems are comprised of roller conveyor systems.

In the case of conveyance using this roller conveyor method, when the tip and rear ends of the tube come into contact with the rollers during tube conveyance (especially when the gap between the feed rollers is long), there may be problems such as insufficient centering of the rollers, bending or deflection of the tube, etc. This causes a shock and causes the tube to vibrate.

In order to solve this problem, in the past, in addition to centering the rollers, improvements in tube manufacturing technology led to tubes with less bending and flaw detection. However, this did not lead to fundamental noise removal and caused a decrease in detection ability.

Figure 6 shows the relationship between the difference between left and right misalignment (large) and (small) and the signal amplitude. The diameter of the coil is 60 m, and the pipe dimensions are 48.6 w in diameter and 5.0 m in wall thickness.
, a drill hole with a diameter of 1.6 fi was created as a defect.

FIG. 6 does not clearly show the influence of noise caused by tube vibration, but it does show that when the misalignment is large, the variation equation of the signal amplitude becomes large. If the eccentricity due to vibration is not within ±0.25 ws, an amplitude change of approximately ±10x will occur, and it can be determined that this is related to noise. .

(c) Problems to be Solved by the Invention The problems to be solved by the present invention are to solve the problem of minute conveyance noise that cannot be solved by the signal processing method of conventional eddy current flaw detection equipment by improving the conveyance surface of the noise source. The objective is to improve flaw detection detection ability.

(d) Means for Solving the Problems The tube eddy current flaw detection equipment of the present invention is provided with a conveyor on both sides of a detection coil, and the tube to be inspected is passed through the detection coil by the conveyor to perform eddy current flaw detection. In the equipment, the conveyor is formed by a belt conveyor, and in the conveyor on the inlet side of the detection coil, the conveyor is tilted in the width direction with the inlet side of the pipe to be inspected raised, and the inlet side belt conveyor is placed at a lower position. A backing plate is provided on the side to receive the transferred tube to be inspected, a guide is provided at the end of the inlet side belt conveyor to guide the tube to be inspected into the detection coil, and the belt conveyor is installed in a conveyor on the outlet side of the detection coil. The transfer side of the pipe to be inspected is lowered and inclined in the width direction, and a backing plate is provided on the lower side of the output belt conveyor to catch the tube to be inspected, and at the starting end of the output belt conveyor after the inspection is completed. The above problem is solved by providing a guide for guiding the pipe to be inspected to the exit belt conveyor.

(E) Function In the tube eddy current flaw detection equipment of the present invention, belt conveyors are used as the conveyors on the inlet and outlet sides, because with conventional roller conveyors, no matter how much the horizontal position of the rollers is adjusted, the tube This is because significant vibration occurs due to bending, etc., and if the distance between the rollers is made small to prevent this, the conveyor becomes expensive. In order to eliminate the drawbacks of the roller conveyor system, such as the rollers that come into direct contact with the pipe and often damage the pipe, they are also noisy and require expensive materials to prevent wear, a belt conveyor was adopted. .

The belt of the belt conveyor is preferably made of oil-resistant vinyl chloride or the like, and pipes, especially steel pipes, are coated with oil to prevent rust. The heat resistance of the belt should be 100℃ or less because the temperature of the tube is usually not high.The higher the drag resistance is, the better, as it determines the durability of the conveyor.However, if this is not possible, , all you have to do is replace the belt.
In any case, the belt should be selected according to the condition of the pipe to be inspected.

The belt conveyor can be driven by rotating the end rolls using a motor in the same way as a normal belt conveyor. A faster conveyance speed is preferable in terms of the process.In the case of conventional roller conveyors, when the conveyance speed is increased, it is easy to cause problems such as vibration, noise, and damage to the pipes.

However, conveyor belts do not have that problem.

Another feature of the belt conveyor of the present invention is that the belt conveyor on the entrance side is tilted in the width direction with the entrance side of the tube to be inspected elevated. This is to make it easier to transfer the tube to be inspected to the belt conveyor, and to prevent it from falling off the belt conveyor during transportation.

A backing plate is installed on the lower side of the slope to prevent the tube from falling and to determine the direction in which the tube will travel.

The tube may be introduced into the belt conveyor by a kicker or a roller. The inclination angle of the belt conveyor depends on the degree of roundness of the belt itself, but in the case of a normal roundness, it is preferably about 10 to 15 degrees.

The same applies to the belt conveyor on the exit side. When transferring the tube from the conveyor, the backing plate may be removed only at the transfer section, and the tube that has rolled away without the backing plate is transferred out using a kicker or roller. When transferring from multiple locations due to equipment constraints, it may be difficult to transfer using a belt conveyor.

In such a case, a roller conveyor may be installed downstream of the belt conveyor, and a kicker may be used to transfer the material.

Furthermore, in the present invention, guides are provided at the entrance and exit of the detection coil. This guide allows the tube to enter the detection coil smoothly, eliminates side-to-side deflection of the tube, and improves flaw detection accuracy. Centering for inserting the tube in the left and right direction at a fixed position is performed by the guide. Centering in the vertical direction is performed by moving the detection coil up and down. Since the pipe is long, it is insufficient to provide a guide only on the inlet side, so a guide is also provided on the outlet side.

(F) Embodiment An embodiment of the pipe eddy current flaw detection equipment of the present invention will be described with reference to FIGS. 1 to 3.

The overall configuration of the tube eddy current flaw detection equipment is such that a conveyor fi40.50 is provided on both sides of the detection coil 2, and the tube to be inspected 7 is passed through the detection coil 2 by the conveyor 40.50 to perform eddy current flaw detection. It has become.

The detection coil 2 is placed on a pedestal 1 and can be raised and lowered by an operation panel (not shown).

The entrance side conveyance R40 includes a belt conveyor 3 and a drive roller 5.
, roller 6. The belt is made of oil-resistant vinyl chloride.

The tube to be inspected 7 is transferred onto the belt conveyor 3 by a kicker 8. As shown in FIG. 2, the belt conveyor 3 is inclined in the width direction by about 10 degrees from the horizontal with the transfer side facing upward. A backing plate 9 is provided on the lower side (opposite the inlet side) to prevent the pipe 7 from falling.

A guide 10 is provided on the belt conveyor 3 near the entrance of the detection coil 2 . Guide 10 has hole 1
1 and a pair of guide plates 13.

The drive roller 5 is driven by a motor 14 through a chain 15 and gears 16, 16'.

The conveyance machine 50 on the output side similarly includes a belt conveyor 17, a drive roller 19, and a roller 20. The exit belt is also made of oil-resistant vinyl. As shown in FIG. 3, the belt conveyor 17 is tilted in the width direction with the side from which the tubes to be inspected 7 are transferred to be lowered, and a backing plate 28 is provided on the lower side of the belt conveyor 17 to receive the tubes to be inspected 7 to be transferred. ing.

The tube 7 to be inspected, which has undergone flaw detection, comes out of the hole 22 of the detection coil 2, passes through the guide 23, is conveyed to the belt conveyor 17, and is moved out through the kicker 24. The guide 23 consists of a passage plate 26 having a hole 25 and a pair of guide plates 27. The drive roller 19 is driven by a motor 31 through a chain 29 and gears 30, 30'.

According to the pipe flaw detection equipment of the present invention, the pipe 7 is TP (Test
Piece) W field (FIG. 5) is transferred to the entrance belt conveyor 40 by the kicker 8. The tube 7 is conveyed by the conveyor 40, passes through the guide 1°, is subjected to eddy current flaw detection at the detection nail 2, passes through the guide 23, and is sent onto the belt conveyor 5o. Thereafter, the tube 7 is transferred out by the kicker 24.

Although not shown, it is preferable to provide a demagnetizing device for demagnetizing the tube 7 magnetized by the detection coil 2.

In order to compare the conventional roller conveyor method and the belt conveyor method of the present invention, the detection ability associated with the amount of vibration and #ji #J amount was examined. The results are shown in Figure 7.
Detectability was determined by S/N ratio. The conditions at that time were that the dimensions of the pipe to be inspected were 21.7w in diameter and 2.8 ram in wall thickness, and a drill hole with a diameter of 0.8cm was provided as shown in Figure 0.By using a belt conveyor, vibration The amount is reduced, and the detection ability is dramatically improved compared to conventional roller conveyors.

(g) Effects According to the present invention, by changing the conveyor of the pipe eddy current flaw detection equipment from the conventional roller conveyor system to a belt conveyor system, the vibration of the pipe is reduced and the detection ability is improved accordingly. Furthermore, pipe noise, pipe damage, etc. are eliminated, and an inexpensive pipe eddy current flaw detection equipment with good detection performance, low pollution, and excellent product quality can be realized.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the pipe eddy current flaw detection equipment of the present invention. Figure 2 is a front view taken from line ■-■ in Figure 1, Figure 3 is a rear view taken from line 1-111 in Figure 1, Figure 4 is a block diagram of a conventional eddy current flaw detector, and Figure 5 is a block diagram of a conventional eddy current flaw detection device. The figure is a plan view of a conventional tube eddy current flaw detection equipment, and FIG. 6 is a graph showing the relationship between the runout of the tube to be inspected and the signal amplitude. FIG. 7 is a graph showing the relationship between the amount of vibration of the tube to be inspected and the S/N ratio. 1: Frame 2: Detection coil 3.17: Belt conveyor 5.19: Drive roller 40, 50: Conveyor 9.28:
Patent plate 10.23 Niguide Patent applicant Sumitomo Metal Industries, Ltd. (4 others)

Claims (1)

[Claims] A conveyor is provided on both sides of the detection coil, and the conveyor passes the tube to be inspected through the inside of the detection coil to perform eddy current flaw detection. In a certain conveyor, the conveyor is tilted in the width direction with the input side of the pipe to be inspected raised, and a backing plate is provided on the lower side of the input side belt conveyor to receive the transferred pipe to be inspected, and at the end of the input side belt conveyor. A guide for guiding the pipe to be inspected into the detection coil is provided, and a belt conveyor is tilted in the width direction with the exit side of the pipe to be inspected lowered in a conveyor on the exit side of the detection coil, and the exit side belt conveyor A backing plate is provided on the lower side of the pipe to receive the pipe to be inspected, and a guide is provided at the starting end of the exit belt conveyor to guide the pipe to be inspected after the inspection is completed to the exit belt conveyor. Eddy current testing equipment for pipes.