JPS6042402B2 - Tube wall thickness measuring device for tubular materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for measuring the wall thickness of a tubular material that can simultaneously measure the wall thickness dimensions at multiple points around the tubular material in a non-contact manner.

FIG. 1 is a conceptual diagram showing a method for measuring the wall thickness of a tubular material proposed by the present inventors and filed separately by the applicant. In the figure, a cross section of a tubular material 20 is shown. However, the thickness dimensions X, , X2, and X3 of each tube wall at points A, B, and C, which divide the tube circumference into three equal parts, are determined by measurement.

A radiation source 1 that emits a measurement radiation beam 3, a radiation source container 2 that accommodates the measurement radiation beam 3 and directs the radiation beam 3 in a predetermined direction, and a tubular member 2 corresponding to each of points A to C.
A measurement system is provided which includes a detector 4 that detects the radiation beam that has passed through the tube wall.

Each code numeral is suffixed with the letter A, B or C denoting the measuring system to which it belongs. Note that the detection output of the beam transmitted through the tube wall by the detectors 4A to 4C is set to 1 to 10, and the detection power when the tube wall does not exist (that is, when the beam enters directly) is 1, respectively. ,0,
11 and 130. The arrangement of each measurement system is as shown in Figure 1, and one radiation beam is transmitted to two measurement points. Two transmitted beams are configured to pass through the measurement point.
Now, in FIG. 1, the following relational expression is established between the output I of the detector 4 and the thickness dimension X of the tube wall as a basic expression of a general radiographic thickness gauge.

Otori 3-E 30 Tono! Hk′1tJv! See＼′ゝ31V(
'i However, μ is the absorption coefficient of the radiation used for the tube wall material, and k is the actual passage length S (see Figure 1A) of the radiation beam passing through the measurement point on the tube wall at that point. This is the number divided by the length X.

If the angle θ between the radiation beam transmission direction and the diameter direction of the tubular material at the measurement point is zero, k is 1. By selecting the number of measurement points, the width of the radiation beam, the radiation transmission method, etc. according to the shape of the tubular material, k can be set to a constant that is not affected by unevenness in the thickness of the tube wall. Now, as mentioned above (
When equations 1) to (3) are solved as simultaneous equations, the results are as follows.

Therefore, the detector outputs 110, 11, 12 of the radiation beam
0, 12, 130, 13 and constants P and k, the tube wall thicknesses Xl, X2 and X3 can be calculated by calculation.

Although the above explanation deals with the case where there are three measurement points, the above-mentioned measurement method can generally be extended to the case where there are n measurement points. Let the tube wall thickness at n measurement points be Xl, X2,
...Xn, the following constant relational expression (simultaneous equations) that changes cyclically is established between each thickness dimension. Note that the following relational expressions are obtained by logarithmically transforming the above-mentioned equations (1) to (3). Above (7)
The expression can be expressed using a matrix as follows.

However, n is an odd number.

FIG. 2 shows a modification of the measurement method described above, that is, n
FIG. 3 is a conceptual diagram showing a method in the case of =9.

In this case, the thickness dimensions Xl, X2... at each measurement point
It will be clear in light of the above equation (7a) that the simultaneous equations for finding the equation are expressed by the following matrix. FIG. 3 is a conceptual diagram showing another modification in the case where n=9.

Compared to the case of FIG. 2, the number of measurement points is the same, but the positions of the measurement points through which the radiation beam passes are different. That is, in FIG. 2, the combinations of beam transmission positions are X1 and X2, X2 and X3, X3 and Xl, X4 and X5,
etc., but in Figure 3, X1 and Xl, X2 and X5
, X3 and X6, Xi and X7, etc. When the simultaneous equations are expressed as a matrix, it becomes as follows. The above equation (9) can be rewritten and expressed as the following equation (10).

As is clear from the above equation (10), it can be said that the modification shown in FIG. 3 is nothing but a modification in which the three-point measurement method shown in FIG. 1 is carried out in three cases.

FIG. 4 is a conceptual diagram showing yet another modification in the case where n=9.

In other words, the combination of the positions where the beam passes is X1 and X
6, X2 and X7, X3 and X8, X4 and X99X5 and Xl
9Xf. and. X29X7 and X39X8 and χ9 are like a sword. The simultaneous equations in this case can be expressed as a matrix as follows.

FIG. 5 is a conceptual diagram showing an embodiment in which n=8.

In this case, for an appropriate odd number m (5 in this example) among the n even measurement points, a simultaneous equation of the saw is established based on the output value of the measurement system, and for each of the m measurement points, Find each thickness dimension. Next, the thickness of the unknown measurement point is determined by measuring the intensity of the beam that passes through one of the m measurement points whose thickness has been determined and the unknown measurement point. Of course, the least squares method may be used. This will be explained in detail with reference to FIG. Since n=8, the thickness of each measurement point is assumed to be Xl, X2, . . ., X8.

First, five of the eight measurement points are selected, and the thickness dimensions of the selected points are Xl, X3, X4, . Let's first find X6 and X7. It will be easily understood from the previous explanation that the simultaneous equations are obtained as follows. Solve the above simultaneous equations to obtain the following solution.

The unknown dimensions are X5, X8, and X2.

Therefore, the following equation is obtained by transmitting the radiation beam through each combination of X5 and Xl, X8 and Xl, and X2 and X6. Since X1 is known, it is possible to find the speed from the above equation.

Similarly, Xl and X6 are known, so from the above formula, X8 and X
2 can be obtained respectively.

Now, when implementing the method for measuring the wall thickness of a tubular material described above with reference to FIGS. 1 to 5, there are the following problems.

That is, it is necessary to irradiate a plurality of measurement points on the circumference of the vibrator to be measured with at least the same number of radiation beams as the measurement points, but the configuration of the apparatus for this becomes complicated. Generally, when nuclear radiation is used, the thickness of the radiation source shield is increased to about 5 to 10 cm for safety reasons.

Furthermore, when used in an X-ray generator, the volume of the radiation source is often the same or larger. Concentrating at least the same number of radiation sources and radiation source containers of a certain size on the outside of the vibrator tube as the number of thickness measurement points on the tube circumference becomes structurally complicated as the number of measurement points increases. Eventually, it would no longer be possible to produce an actual machine. Even if it were possible to manufacture an actual device, maintainability as an online instrument would be extremely poor, and practical performance would decline. Online installation is difficult to implement due to its complex structure. This invention was made in order to solve the above-mentioned problems when trying to implement the method for measuring tube wall thickness, which was separately filed by the present inventor. A device for measuring the wall thickness of a tubular material that can implement the measurement method separately proposed by the applicant without having a complicated structure including a radiation source, a radiation source container, etc. on the outside of the periphery, and can be manufactured as an actual device. Our goal is to provide the following.

The main points of this invention are as follows.

(1) Taking advantage of the fact that in most of the manufacturing process of seamless steel pipes, etc., steel pipes are run in their axial direction,
The measurement system is distributed along the direction of movement of the steel pipe, making it possible to perform the same measurement when each radiation beam of the measurement system is in the same cross section.

(2) This eliminates the complexity of the device installation structure.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 6 is a schematic diagram showing an embodiment of the present invention. In the figure, three measurement systems, 1, 2, and 3, are used, which are combinations of radiation sources and detectors.

1-1, 1-2, 1-3, and 1-4 are the radiation source, source container, radiation beam, and detector of the first measurement system;
-1, 2-2, 2-3, 2-4 and 3-1, 3-2,
3-3 and 3-4 belong to the second measurement system and the third measurement system, respectively. Reference numeral 5 denotes a vibrator to be measured, and here it is assumed that the vibrator 5 does not rotate about its axis, but simply moves at a speed ν in the direction of the arrow in the drawing. For example, a plug mill satisfies this condition. The measurement systems are distributed along the moving direction of the vibrator 5 at intervals El and e2 as shown in the figure. The radiation beam of each measurement system is oriented as shown in FIG. 7 at the vibrator cross sections A, B, and C at each measurement location. When each of the rays in FIGS. 7A, B, and C are superimposed, it becomes as shown in FIG. 7A, which is the same as the arrangement of the measurement system in the measurement method separately filed by the present applicant shown in FIG. It will be recognized that

Now, return to Figure 6. As mentioned above, the three sets of measurement systems are distributed one by one along the vibrator 5, so
The area around the vibrator is not complicated and is simplified, making on-site installation and maintenance of the measurement system easier. The thickness of the three points on the tube circumference of the vibrator 5 is determined using the output signals 1''1, I゛2, 1''3 obtained from the three measurement systems, and the three sets of measurement systems are distributed in a distributed manner. Therefore, the output signals 1''1, I''2, and I''3 obtained simultaneously from the three sets of measurement systems are not values obtained for the same cross section of the vibrator 5. 6 is a drive roll for moving the vibrator 5 in the direction of the arrow or a vibrator movement detection roll such as an idler that is in contact with the vibrator without slipping when the vibrator moves, and its rotation A digital encoder 7 is attached to the shaft to output the amount of rotation (the amount of distance traveled by the vibrator 5) as a digital amount.

Here, the output P of the encoder 7 is output as a time-series vibration, and outputs the number of vibrations in proportion to the amount of rotation of the roll 6. For example, it is assumed that n vibes are output per rotation of the roll 6. The output P of the digital encoder 7 enters delay circuits 8 and 9, respectively. Delay circuits 8 and 9 output 1 of detectors 2-4 and 1-4, respectively.
``2,I'' is connected to 1. The delay circuit 9 uses the output P of the digital encoder 7 to delay the input signal 1''1 by a certain amount of time, and outputs the delayed signal as an output signal 11 to the signal processor (arithmetic unit) 10.

Further, the delay circuit 8 uses the encoder output P to delay the input signal 1''2 by a certain amount of time, and outputs the delayed signal as an output signal 12 to the signal processor 10.

The signal 11 input to the signal processor 10 in this way,
12 and 13 correspond to the detected amounts obtained by measuring the same cross section of the vibrator by three sets of rotating systems by applying the above-described delay operation to 11 and 12.

Hereinafter, the signal processing for obtaining the vibrator wall thickness dimension in the signal processor 10 is the same as that described above with reference to FIG. Although the embodiment in which three sets of measurement systems are distributed along the vibrator has been described above with reference to FIG. 6, the manner in which the measurement systems are distributed is not limited to this. The mode of dispersion can be arbitrarily changed depending on the number of measurement points, the installation conditions of the measurement system, the structure and dimensions of the rotation system, etc. FIG. 8 is a diagram used to explain another embodiment of the present invention, and is an explanatory diagram showing the direction of the radiation beam in cross sections A and B of the vibrator. It is a diagram in which A (5B) in the figure is shown superimposed.

That is, FIG. 8 shows a measuring device with eight measuring points as described above with reference to FIG. 5, with five measuring systems (cross section A) and three measuring systems. (Cross section B) is an explanatory diagram of an example in which the particles are dispersed. There is no need to explain that FIG. 8A, in which A (5B) of FIG. 8 is shown superimposed, coincides with FIG. An example will be explained with reference to FIG.

See FIG. 9.

Here, it is assumed that the detector output 1 is input as an analog voltage. The input signal I is first converted into a digital quantity having the required number of digits in the A/D converter 15. Assuming that the output is represented by an R-digit binary/w-adic code (BCD), the A/D converter 15 outputs a 4R-bit digital output. These outputs are connected to 4R serial shift registers 16a, 16b to 16n. The output P of the digital encoder 7 in FIG. 6 is used as the shift pulse CL of the shift register. The number m of bits of each shift register may be determined depending on the required delay time resolution. If it is desired to obtain the amount of delay in units of moving distance Δe of the measurement vibrator, m and n may be determined in the delay circuit 8 of FIG. 6 so as to satisfy the following.

Note that k is the diameter of the roll 6, and n is the number of pulses output by the encoder 7 when the roll 6 makes one revolution. Regarding the delay circuit 9 in FIG. 6, m'F)n may be determined so as to satisfy the following.

In this way, the input signal 1 to the delay circuit is converted into a digital quantity, and each time the measurement vibrator moves a certain distance, it moves one step at a time in the shift register, which is a delay circuit. , when the measuring vibrator moves by distance E2, input signal 1 is output to the register output side.
will appear, and for the delay circuit 9, ('1
When the vibrator moves by +'2), input signal 1 appears on the shift register output side. That is, delay circuits 8 and 9
will respectively delay the input signal 1.

As explained above, according to the present invention, it is not necessary to centrally arrange the measurement system at a specific location outside the vibrator tube, and the measurement system can be distributed along the moving direction of the vibrator. There are advantages in that a device for measuring the thickness of a tube wall of a tubular material can be provided, which can avoid the complexity of the surrounding structure, can be manufactured as an actual device, and is easy to maintain.

The measuring device according to the present invention can be applied to tubular materials made of materials such as glass, plastic, rubber, paper, fiber, metal, etc. by appropriately selecting the radiation species and the intensity of energy.

It goes without saying that the present invention can also be applied to hollow bodies having a certain cross-sectional shape, even if they are not tubular. Furthermore, instead of the radiation beam, it is also possible to use infrared, visible, and ultraviolet light rays, X-rays, various particle beams, and the like. Furthermore, when carrying out the present invention, it is advantageous to use a computer (minicomputer, microcomputer, etc.) for arithmetic processing of the measured values, as this enables rapid processing.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram showing a method for measuring the wall thickness of a tubular material, which is currently being applied for separately by the present applicant, Fig. 1A is an explanatory drawing showing the dimensional relationship of the main parts in Fig. 1, and Fig. 2 is , a conceptual diagram showing the first modification of the above measurement method, FIG. 3 shows the second modification, FIG. 4 shows the third modification, and FIG. 5 shows the fourth modification. 6 is a conceptual diagram showing an embodiment of the present invention, and FIG. 7 is an explanation showing the direction of the radiation beam in the vibrator cross sections A, B, and C in FIG. 6. Figure 7A shows A, B in Figure 7,
8 is a diagram used to explain another embodiment of the present invention, in which the cross section AI of the vibrator is
:． An explanatory diagram showing the direction shift of the radiation beam at B,
Figure 8A is a diagram in which A and B in Figure 8 are superimposed;
FIG. 9 is a block diagram showing an example of the configuration of a delay circuit used in the present invention. In the figure, 1 is a radiation source, 2 is a radiation source container, 3 is a radiation beam, 4 is the same detector, 5 is a vibrator, 6 is a vibration movement detection roll, 7 is a digital encoder, 8 and 9 are delay circuits, respectively. 10 is a signal processor (arithmetic unit), 15 is an A/D converter, 16 is a shift register, and 20 is a tubular member.

Claims (1)

[Claims] 1 At least three sets of beam projection systems that project at least three radiation beams such that they intersect with each other and form a regular-odd polygon with the intersection points as vertices, and the vertices of the polygons are all tubular. Each measuring means corresponding to the projection system positions the tubular material so as to be included in the thick part of the material, and measures the intensity of the radiation beam transmitted through the thick part of the tubular material. and an arithmetic device which receives these measured values and calculates the wall thickness of the tubular material at the location where the vertex of the polygon is located as the tube wall thickness. While moving the tubular material in its axial direction, the beam projection systems are distributed along the direction of movement, and the measured value signals from the measuring means corresponding to each projection system are transmitted to the tubular material. By inputting information to the arithmetic device according to the movement,
A device for measuring the wall thickness of a tubular material, characterized in that the wall thickness of the tubular material is measured in the same cross section.