JPH01308907A - System for measuring shape of steel pipe using gamma-ray - Google Patents

Abstract

PURPOSE:To simultaneously measure an outer diameter, an inner diameter, a wall thickness and a flaw using gamma-rays in a noncontact state by one scanning by the use of one apparatus by providing a feed system for allowing a steel pipe being an object to be measured to advance across a measuring position while rotating spirally. CONSTITUTION:A gamma-ray source part 1 receives a gamma-ray source and emits gamma-ray beam in a fan shape at a certain angle from an irradiation port and a multichannel gamma-ray detection part 2 is arranged at the position opposed to the gamma-ray source part 1 so as to interpose a steel pipe 3 being an object to be measured. The steel pipe 3 is fed on the drive roller 7 arranged so as to be inclined at a certain angle from a vertical direction with respect to the advance direction thereof while rotated spirally in such a state that the center position thereof is held by freely rotating balls 8. The signal from the gamma-ray detection part 2 is taken in a data processing part to perform image processing and data processing. On the basis of the measured data at each position taken in at a certain interval by sampling, not only the measurement of the outer diameter, inner diameter and wall thickness of the steel pipe 3 as well as the flaw present in the steel pipe but also the reconstitution of the cross-sectional image of the steel pipe can be performed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a gamma bare steel pipe shape measurement system, and is particularly suitable for measuring the shape and dimensions of steel pipes in a seamless steel pipe manufacturing line, and measuring internal flaws in steel pipes. This relates to a steel wire pipe shape measurement system.

[Conventional technology]

Regarding the conventional shape measurement of this type of steel pipe, measurement technology '87
．． ``Summary of quality inspection of medium-diameter seamless pipes'' by Otashiro (Nippon Kokan) in 12, and ``Crown meter for steel'' by Okinoyo (Toshiba) in the 18th Japan Isotope Radiation Bare Line Conference Materials November 1987. There is literature.

In quality inspection on a seamless steel pipe production line, inspection of the outer diameter, inner diameter, wall thickness, and flaws of the pipe are the most important inspection items. Looking at the methods that are currently commonly used for these inspections, first, an optical diameter meter is used to measure the outside diameter of the pipe, as shown in Figure 3 (a). . A pipe 11 passes through a parallel light beam 10 irradiated from equally spaced projectors 9, and the brightness of the light is detected by a semiconductor image sensor (for example, CCD) 12 and extracted as an electrical signal. , the pipe outer diameter is calculated from the correspondence between the physical position dimensions of the elements and the electrical signals.

An ultrasonic method is generally used to measure the pipe wall thickness, as shown in FIG. 3(b). This method requires a pipe 13
Ultrasonic waves are emitted from the probe 14 toward. The sound waves are reflected from the outer and inner surfaces of the pipe 13 and are transmitted to 15a and 15b.
Therefore, the wall thickness is measured by measuring the propagation time of the ultrasonic wave and multiplying the difference by the propagation speed of the ultrasonic wave. However, in this case, it is necessary to perform contact measurement between the probe 14 and the surface of the pipe 13 via the water film 16, and therefore it is necessary to correct the propagation velocity depending on the water temperature.

In addition, the inner diameter of the steel pipe was calculated from the measured values of the outer diameter and wall thickness as the difference between the two.

The ultrasonic method is still used to inspect steel pipes for defects.
Probes arranged radially in multiple stages were rotated around the pipe, and the entire surface was scanned and measured while the probe holder rotated once.

[Problem to be solved by the invention]

The above conventional technology has the following problems and drawbacks.

(1) Individual dedicated equipment must be used for each measurement item.

(2) As in the case of measuring pipe wall thickness, the outside diameter and wall thickness are measured using separate devices, and calculations are made from the difference between these measurements; the measurement method itself is direct. There were also problems with measurement accuracy.

(3) In outer diameter measurement, the bright and dark parts of the light beam are electrically measured and calculated using the relationship between the physical arrangement (pitch) of the elements. It is calculated based on the difference in propagation speed of waves reflected from the surface, requires temperature correction of the medium, uses a secondary measurement method, and tends to lack accuracy.

(4) Both wall thickness gauges and flaw inspections were measured using a medium such as water, and were not non-contact measurements.

The purpose of the present invention is to provide a gamma-ray steel pipe shape measurement system for seamless steel pipes that can simultaneously measure outer diameter, inner diameter, wall thickness, flaws, etc. in one scan with one device in a non-contact manner using gamma-rays. It is about providing.

[Means to solve the problem]

The above purpose is to house a gamma ray source and emit a gamma ray beam in a fan shape at a certain angle from the irradiation port, and to place the gamma ray source and the steel pipe, which is the object to be measured, in opposite directions. A multi-channel gamma ray detection unit is placed at a position where It is composed of a trolley equipped with a means for traveling in a vertical direction, and a data processing section that takes in the signal from the gamma ray detection section and performs image processing and data processing, and each position is taken in by sampling at a certain interval. The outer diameter and inner diameter of the steel pipe, which is the object to be measured, are determined based on the measurement data.

This was achieved by making it possible to measure the wall thickness and flaws present in the steel pipe, and to reconstruct the cross-sectional image of the steel pipe.

[Effect]

Since the steel pipe, which is the object to be measured, is equipped with a conveyance system that moves forward while rotating spirally, the average value of the outer diameter, inner diameter, and wall thickness of the steel pipe is calculated based on the data obtained by sampling as the steel pipe passes. ,maximum.

It is possible to perform online measurement of minimum values, deviations from set values, abnormal values, etc., and to detect defects in steel pipes, detect the abnormal values and draw a cross-sectional image on the display to search for them. Dimensions can be measured.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1-2.

FIG. 1 is a basic configuration diagram showing an embodiment of the 7 m steel pipe shape measuring system of the present invention. In Fig. 1, 1 is a gamma ray source section that has a gamma ray source such as 137Cs and 80G O with relatively large penetrating power, 2 is a mutually independent multi-channel gamma ray detection section, and 3 is a steel pipe that is the object to be measured. - Inside the shell, there is a predetermined position in the direction of the paper shown in the figure, so that it is conveyed in a direction perpendicular to the paper. Reference numeral 4 denotes a cart that can move the gamma ray source section 1 and the gamma ray detection section 2 in opposite positions as shown in the figure and move in a direction perpendicular to the length direction of the steel pipe 3;
Reference numeral 5 denotes a data processing section mainly composed of a computer that receives signals from the detection section 2 and handles image processing and various arithmetic controls, and the gamma ray steel pipe shape measurement system is composed of these.

A gamma ray beam 6 is emitted from the gamma ray source section 1 in a fan shape with a certain angular spread as shown in the figure.

Now, focusing on one detector in the gamma ray detection section 2, the detector receives opposing gamma ray beams, and if there is a substance in between, the gamma rays pass through that substance and some of them are detected. It will be absorbed by the substance. What is that relationship?

1 μt ■Work■. 0...(1)
μt=Qog(Io/I) −(2
) Here, I: γ-ray count rate after passing through a certain substance (cps); O: γ-ray count rate when there is no substance in between (cps);
s) μ: Absorption coefficient of intermediate material (alt-1) t: Thickness of intermediate material (cn). As can be seen from the above equation, if the material is the same, the ratio of the counting rate of 0 and 0 is the thickness (density) of the material.
It will be proportional to. That is, by measuring this from multiple directions, the intensity distribution of γ-rays passing through the material can be obtained. An image can be reconstructed based on this large amount of accumulated data, and a cross-sectional image of the steel pipe 3 and the state of flaws inside the steel pipe (flaw size and shape) can be determined.

Of course, the outer diameter, inner diameter, wall thickness, etc. of the steel pipe 3 can also be directly measured from this data.

In addition, the larger the amount of data and the greater the number of samples, the clearer the image will be during image reconstruction and the higher the resolution.
The most desirable condition is to obtain data from the entire 360° circumference of the object to be measured. However, the configuration shown in the figure is a practical configuration based on conditions such as product cost performance, constraints on actual device configuration, and required accuracy. In the apparatus of this embodiment, the cart 4 moves in a direction perpendicular to the length direction of the steel pipe 3 to perform sampling.

Generally, on a production line, it is desirable to measure while the line is in operation. This requirement is the same for current equipment.

Profile measurements are performed by moving the object to be measured on a line, rotating the measurement system around it once, and scanning it in a spiral pattern in the length direction. In order to shorten the measurement time as much as possible and to perform accurate measurements, a configuration as shown in FIG. 2 is adopted. In other words, the gamma ray detection unit 2 is configured to take the form of a third-generation CT, so that the number of channels can be increased as much as possible, and the measurement target is arranged to be approximately at the center of the circle with respect to the steel pipe 3, which is the measurement target. A drive mechanism is constructed so that the steel pipe 3, which is the object to be measured, is conveyed spirally within the γ-ray beam 6. For example, one embodiment will be described with reference to FIG. 2. A driving roller 7 for imparting rotation to the steel pipe 3 is arranged obliquely at a certain angle with respect to the direction perpendicular to the traveling direction of the steel pipe 3. When the rollers 7 displaced in this manner are rotated, a force that moves the steel pipe 3 forward and a force that rotates the steel pipe 3 are generated.

The rate of force can be controlled over a certain range by the magnitude of the deflection angle.

In this case, the steel pipe 3 must always travel in the center of the conveyance line, and the conveyance drive mechanism must be devised so as not to deviate from the central position. For example, a freely rotating ball as shown at 8 in FIG. Equipped with a mechanism that allows for free rotational operation. However, this is a proposal of one embodiment, and the gist of the embodiment of the present invention is that the steel pipe 3, which is the object to be measured, is equipped with a drive mechanism that moves the measurement position while rotating spirally. do it. As described above, in this embodiment, average values, maximum values, minimum values, and set values for the outer diameter, inner diameter, and wall thickness of the steel pipe 3 are determined based on data obtained by sampling when the steel pipe 3 passes. Online measurement of deviations, abnormal differences, etc. will be possible.

In addition, for flaws in steel pipes, the above-mentioned abnormal values are captured and a cross-sectional image thereof is drawn on a display to search for them, and at the same time, one dimension of the flaw shape is measured.

In addition, in the manufacturing process of the steel pipe 3, drilling is performed by a piercer machine using a drill around the hole called a plug, but sometimes the plug is left inside the steel pipe 3, and the machine in the first process, For example, elongator, mandrel mill.

A plug detection device is installed in the line to prevent damage to sizers, etc.

This plug detection can also be easily performed by this measurement system as an abnormal value detection.

〔Effect of the invention〕 The main effects of the present invention can be summarized as follows.

(b) Since it is a non-contact measurement, it can also be applied to hot online measurement.

(b) Measure the outside diameter, inside diameter, and wall thickness of steel pipes with one measurement system.

Can measure multiple items such as flaw or plug detection.

(c) Not only can various measured values be calculated and displayed from the sampled accumulated data, but also the cross section of steel pipes can be displayed.

The shape of flaws inside the steel pipe can be visualized.

be direct;

(d) Since gamma rays are used as radiation, it has penetrating power;
Suitable for measuring steel pipes.

In general, the specifications for medium-length pipes include an outer diameter of about 100 to 500 m, a wall thickness of several meters to several tens of meters, and a length of several meters to 20 m. In particular, the maximum penetration thickness of the steel pipe is required to be about 100 m. Therefore, it cannot be measured with X-rays.

(e) This measurement system configuration has a proven track record in hot applications, is resistant to harsh hot environments, and is easier to maintain than other measurement systems.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram showing an embodiment of the gamma ray steel pipe shape measurement system of the present invention, Fig. 2 is an explanatory diagram showing an embodiment in which the measurement system of Fig. 1 is provided with a steel pipe drive mechanism, and Fig. 3 The figure is an explanatory diagram of a conventional steel pipe outer diameter measuring method, steel pipe wall thickness measuring method, and flaw measuring method.

Claims (1)

[Claims] 1. A gamma ray source is housed, and gamma rays are emitted in a fan shape at a certain angle from the irradiation port.
A gamma ray source section that emits a ray beam, a multi-channel gamma ray detection section disposed oppositely to the gamma ray source section across the steel pipe that is the object to be measured, and the gamma ray detection section. a trolley equipped with means for mounting the gamma ray source sections facing each other with the object to be measured in between, and traveling in a direction perpendicular to the conveyance direction of the object to be measured; It consists of a data processing unit that takes in signals and performs image processing and data processing, and calculates the outer diameter and inner diameter of the steel pipe that is the object to be measured based on measurement data at each position taken by sampling at a certain gap. A gamma ray steel pipe measurement system that is capable of measuring wall thickness, flaws existing in steel pipes, etc., and reconstructing cross-sectional images of steel pipes. 2. A claim comprising a drive mechanism as a means for transporting the object to be measured, which rotates when the object to be measured passes through the γ-ray beam and moves straight in a direction perpendicular to the traveling direction of the trolley. The gamma ray steel pipe measurement system according to item 1.