JPH0648172B2 - Steel pipe end profile and wall thickness measuring device - Google Patents

Description

The present invention relates to a device for measuring the profile and wall thickness at the end of a steel pipe.

<Prior Art> Conventionally, as a method of non-contact measurement of material thickness,
There are many known methods such as using an ultrasonic thickness gauge or a radiation thickness gauge.

Further, for a material having a shape such as a flat plate, the thickness can be calculated by simply measuring the displacement between the front surface and the back surface using a laser distance meter or the like.

By the way, in the case of measuring the wall thickness and the profile of the end portion of the steel pipe, for example, a method using a radiation thickness gauge as disclosed in JP-A-57-12307 or JP-A-61-219810.
A method using an ultrasonic thickness gauge as disclosed in Japanese Patent Publication has been proposed, but all of these methods require large-scale equipment and complexity, and thus are expensive.

Therefore, it is necessary to manually insert a micrometer or the like into the end of the pipe to actually measure it, or, for example, see, for example, the actual model 61-131610.
As disclosed in Japanese Patent Publication, a wall thickness measuring device in which a detection roller is brought into contact with the inner and outer surfaces of a pipe and converted into an electric signal by a rotary encoder has been proposed and used.

<Problems to be Solved by the Invention> However, in the above-mentioned interpolation type or contact type, in an automatic processing line in which pipes are continuously conveyed, for example, to measure the wall thickness, for example, 3 pipes per pipe are used. Although it requires a high speed of about 5 seconds, it actually takes more time, or there is a problem in terms of efficiency and safety such as a failure due to collision with a conveyed pipe. .

Further, it is difficult to measure the profile of the pipe end, which is one of the objects of the present invention.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a non-contact and inexpensive steel pipe end profile and wall thickness measuring device.

<Means for Solving the Problems> The gist of the present invention is that the inside of the pipe wall of the steel pipe to be measured has a center of an arc on the pipe axial surface and is 45 ° to the pipe axial surface. First positioned to face the outer surface of the end at an angle
Circular arc cone band mirror, a second circular arc cone band mirror provided opposite to the first circular arc cone band mirror at an angle of 45 ° in the opposite direction, a light projecting section for emitting a laser beam, and this projecting section. The 45 ° half mirror and 45
A rotating mirror that swingably rotates along the circular arc of the second circular-conical-zone mirror through a circular mirror to form a light-section beam, and the end portion received by the first circular-conical-zone mirror. And a signal from this two-dimensional position detecting element for detecting the reflected light of the light cutting beam from the inner and outer surfaces of the lens through the imaging lens system arranged facing the 45 ° half mirror. And a display device for displaying a calculation result of the arithmetic processing device, and a profile and thickness measuring device for an end portion of a steel pipe.

<Operation> Generally, in an optical displacement sensor, the position of a laser spot, for example, is detected by a one-dimensional position detection element, and the displacement can be measured from the position by using a triangulation method.

The principle will be described below with reference to FIG.

As shown in the figure, for example, two optical displacement sensors A and B
Are arranged at intervals of L, and at positions C and D at a distance 1 from the pipe end 1a of the steel pipe 1 toward the inside, θ from the inner and outer surfaces, respectively.
_A laser beam is emitted at an angle of ₁ and θ _{2 and} the reflected light reflected from the laser spot is detected.

At this time, the distance from the optical displacement sensor A to the point C is r
_1, and the distance from the optical displacement sensor B to point D and r _2, the thickness t of the pipe wall 1b to be measured can be calculated by the following equation (1).

t = L−r ₁ cos θ ₁ −r ₂ cos θ ₂ (1) However, in practice, it is difficult to set the angles θ ₁ and θ ₂ appropriately, and a slight error in the displacement sensor setting or the pipe end An error occurs due to a slight inclination of the part, and it is impossible to measure the wall thickness with high accuracy.

Therefore, as a result of various researches, the present inventor has made a two-dimensional position detecting element of this optical displacement sensor, and makes it possible to scan a laser spot by using an arc-shaped conical band mirror. The inventors have found that it is possible to measure the edge profile with high accuracy and, as a result, to measure the wall thickness.

According to the present invention, since a pair of opposing circular-arc conical band mirrors are used as the reflecting mirrors, it is possible to simultaneously measure a laser spot on the back surface that could not be measured by a shadow in the past. Therefore, the wall thickness of the pipe end can be measured.

Also, by setting the arc center of the arc-shaped conical band mirror so that it is inside the tube wall, the optical path length when scanning the optical system in the arc direction may be the same length with respect to the arc center point. Therefore, the profile of the pipe end can be measured by obtaining the polar coordinates (r, θ) with the arc center point as the origin.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a plan view thereof.

In the figure, 2 is a first circular-arc conical band mirror having a constant radius of curvature, which has a central point O of a circular arc on the pipe axis surface inside the pipe wall 1b of the steel pipe 1 to be measured, and It is installed so as to face the outer surface of the tube end portion 1a at an angle of 45 ° with respect to the axial surface.

Reference numeral 3 denotes a second circular-arc-conical-band mirror having the same radius of curvature as that of the first circular-conical-band mirror 2, and is provided to face the first circular-conical-band mirror 2 at an opposite angle of 45 °.

Reference numeral 4 denotes a laser emitting device that emits a laser beam.
The laser beam LB _O output from the laser light emitting device 4
Is being swung rotated by the rotating mirror 5, 45 ° half mirror 6,45 ° scannable light cut mirror 7 via a along an arc of the second arc conical zone mirror 3 beam LB _C, and the further Steel pipe 1 by means of a first circular cone cone mirror 2
The inner and outer surfaces of the tube end portion 1a are irradiated.

An image forming lens system 8 is provided to face the 45 ° half mirror 6.

9 is a two-dimensional position detecting element for detecting the reflected light, the reflected light LB _H reflected from the laser spot tube end 1a light is irradiated to the cutting beam LB _C, arc conical band of the first and second It is detected as a two-dimensional signal via the mirrors 2, 3, 45 ° mirror 7, 45 ° half mirror 6 and imaging lens system 8.

The imaging lens system 8 and the two-dimensional position detecting element 9 are
Since profile measurement is performed by the triangulation method,
It is arranged at a slight angle α with respect to the laser emitting device 4.

Reference numeral 10 denotes an arithmetic processing device, which arithmetically processes a signal from the two-dimensional position detecting element 8.

Reference numeral 11 denotes a display device that displays the calculation result of the calculation processing device 10.

Here, the tube end portion 1a imaged on the two-dimensional position detecting element 8
A method of signal processing when obtaining the profile of will be described.

First, a measurement example when the steel pipe 1 is in a horizontal state will be described.

As shown in FIG. 3 (a), the steel pipe 1 is placed horizontally,
The arcuate center point O of the first arcuate conical band mirror 2 having a constant radius of curvature is installed so as to be located on the tube axis F inside the tube wall 1b. Then, by irradiating a light section beam LB _C,
The reflected light LB _H reflected from the laser spots on the inner and outer surfaces of the tube end portion 1a is received by the first arc-shaped conical band mirror 2 within an angle range of ± ω _m .

Then, the profile of the tube end portion 1a imaged on the two-dimensional position detecting element 8 has the same optical path length at the position of the arc center point O of the first arc-conical band mirror 2, and therefore, If the position of the center point O is adjusted so as to be on the x-axis of the xy-axis plane of the two-dimensional position detecting element 8, for example,
It is output as a value of ω in the x-axis direction and as a value of r in the y-axis direction, and as shown in FIG. 3 (b), the arc center point O of the first circular-conical-zone mirror 2 is the origin. It is projected on a locus of polar coordinates (r, ω) which is symmetrical.

Therefore, the arithmetic processing unit 10 can calculate as a profile by converting it with the following equations (2) and (3).

x = rcosω ... (2) y = rsinω ... (3) Next, a measurement example when the steel pipe 1 is inclined will be described.

As shown in FIG. 4 (a), when the pipe axis F of the steel pipe 1 is inclined by θ ₁ from the horizontal plane, its arc center point O is a point A when the vertical line OA to the pipe end 1a is drawn. The polar coordinate at (r ₁ , θ ₁ ), and the vertical line O to the inner and outer surfaces of the tube wall ₁ b.
When the polar coordinates at points B and C when B and OC are subtracted are (r ₂ , θ ₂ ), (r ₃ , θ ₃ ), respectively, these points A, B, and C can be used to determine the arbitrary end of the pipe 1a. The distances r _A , r _B , and r _{C to the} polar coordinates (r, ω) at point N are
It can be expressed by Eqs. (4), (5), and (6).

r _A = r ₁ / cos (θ ₁ −ω) …… (4) r _B = r ₂ / cos (θ ₂ −ω) …… (5) r _C = r ₃ / cos (θ ₃ −ω)… (6) Here, since the inclination angle θ ₁ of the tube axis F with respect to the horizontal plane can be measured, this θ ₁ and θ ₂ and θ ₃ have the following relationship.

θ ₂ = θ ₁ + π / 2 (7) θ ₃ = θ ₁ −π / 2 (8) Note that this θ ₁ is the locus of polar coordinates (r, ω) in Fig. 4 (b). As projected, the value θ of ω at the minimum value r ₁ of r
You may make it obtain ₁ .

This makes it possible to obtain the profile of the tube end portion 1a.

Further, in polar coordinates (r, ω) of the arbitrary point N, the distances r _Bm and r _Cm from the points B and C on the inner and outer surfaces of the tube end portion 1a when the angle ω is ± ω _m , respectively, are as follows ( 9), (1
There is a relation of expression (0).

r _Bm = r ₂ / cos (θ ₂ −ω _m ) …… (9) r _Cm = r ₃ / cos (θ ₃ + ω _m ) …… (10) Therefore, the wall thickness t of the pipe wall 1 b at this time is , Below (11)
Can be expressed as

t = r ₂ + r ₃ = r _Bm cos (θ ₂ −ω _m ) + r _Cm cos (θ ₃ + ω _m ) = r _Bm sin (θ ₁ −ω _m ) −r _Cm sin (θ ₁ + ω _m ) ... ( 11) In addition, r _Bm and r _Cm in the above formula (11), θ ₁ ,
Since all ω _m are known, the wall thickness t of the tube wall 1b can be obtained by the arithmetic processing unit 10.

If the steel pipe 1 is rotated, the profile and wall thickness of the entire circumference of the pipe end 1a can be measured continuously and at high speed.

As described above, by adjusting the center point of the arc of the circular cone band mirror to be located in the tube wall by using the present invention, it is possible to prevent the deviation due to the end bending of the tube end often occurring online without being affected. The wall thickness of the pipe wall can be measured, and the profile of the beveled end surface obtained by trimming the pipe end as shown in FIG. 5 can be measured accurately.

In addition, although the above-mentioned embodiment explained the measurement of the profile and wall thickness of the pipe end portion of the steel pipe, the present invention is not limited to this, and is also applicable to profile and thickness measurement of the edge portion of a flat plate, for example. It goes without saying that you can do it.

<Effects of the Invention> As described above, according to the present invention, since the circular-arc conical mirror is used, the profile and the wall thickness of the pipe end portion are online without contact and without being inserted into the pipe. Can be measured continuously and at high speed.

Further, by doing so, it is possible to eliminate troubles such as breakage of the device, which is often caused by the conventional contact type or interpolation type.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing an embodiment of the present invention, and FIG.
FIG. 1 is a plan view of FIG. 1, FIG. 3 is a schematic side view of a main part of a measurement example of the present invention, (a) is a side view thereof, (b) its characteristic diagram, and FIG. 4 is another measurement example. FIG. 5 is a side view showing an application example of the present invention, FIG.
FIG. 6 is an explanatory diagram showing the principle of the present invention. 1 ... Steel pipe, 2 ... First circular cone mirror, 3 ... Second
Arc conical mirror, 4 ... Laser emitting device (projector),
5 …… Rotating mirror, 6 …… 45 ° Half mirror, 7 …… 45
Mirror, 8 ... Two-dimensional position detection element (light receiving part), 9 ...
… Imaging lens system, 10 …… Computational processing unit, 11 …… Display unit.

Claims (1)

[Claims] 1. A steel pipe to be measured, which has a center of an arc on the axial surface of the pipe inside the pipe wall and is positioned to face the outer surface of the end portion at an angle of 45 ° with respect to the axial surface of the pipe. A first circular-arc-conical-band mirror, a second circular-conical-conical-band mirror that faces the first circular-arc-conical-band mirror and is provided at an angle of 45 ° in the opposite direction; A rotary mirror for swinging and rotating the laser beam from the light projecting portion through a 45 ° half mirror and a 45 ° mirror along the arc of the second arc-shaped conical band mirror to be a light cutting beam; Two-dimensional position for detecting the reflected light of the light cutting beam from the inner and outer surfaces of the end portion received by the first arc-shaped conical band mirror through an imaging lens system arranged facing the 45 ° half mirror. A light receiving part consisting of a detection element and a signal from this light receiving part That the processing unit and, the processor of the operation result display device for displaying, profile and wall thickness measuring apparatus of the steel pipe end, characterized in that they are composed of.