JPH0426403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for optically measuring the inclination angle of an inclined surface with respect to a predetermined reference plane, such as the bevel angle of an oil country tubular end.

[Prior art]

Steel pipes for oil wells are used for the extraction and production of crude oil and natural gas, and in the case of extraction, they are usually connected in large numbers to reach several thousand meters underground at angles that are perpendicular or close to perpendicular to the earth's surface. Ru.

There are various methods of connection, but in general oil well steel pipes, the end cross section of which is shown in Figure 3, are placed facing each other with their axes aligned, and a female screw called a couple ring is attached to the outer periphery of the oil well steel pipe. This is done by screwing onto a male threaded portion 16 formed on the end 1 of the steel pipe.

The yield strength, tensile strength, elongation, and dimensions of each part of oil well steel pipes used in this way are specified by API (American Petroleum Institute) standards, and the bevel angle of the end of oil well steel pipes is one of the specified items. It's becoming one.

The bevel angle refers to the angle between the inclined surface formed between the end of the male threaded portion 16 and the end edge and the plane perpendicular to the tube axis. In other words, this inclined surface, that is, the beveled portion 1a It refers to the angle between the generatrix of and the radial direction.

Conventionally, the bevel angle is inspected by pressing a reference gauge with the largest angle within the tolerance and a reference gauge with the smallest angle within the tolerance against the bevel portion 1a, and checking whether the bevel angle is within the two gauge angles. Either check or use a protractor type angle gauge.

However, when inspecting using the reference gauge and angle gauge, measurement errors due to individual differences cannot be avoided because the inspection is done manually, and automation has been desired.

This automation is possible by measuring with a device using a known optical cutting method. This device irradiates the bevel part with a long slit light in the axial direction of the oil well steel pipe from a direction perpendicular to the axis of the oil well steel pipe, and then photographs the irradiated beam with a TV camera, etc. from an angle of 45 degrees. The bevel angle is measured based on the inclination of the photographed irradiation ray, the receiving angle of the TV camera, etc., optical magnification, etc., and it takes advantage of the fact that the bending angle at the bevel part of the irradiation image depends on the bevel angle. do.

However, this device has the drawback that high-speed processing is difficult because it measures based on two-dimensional image information, and the device is quite large.

〔the purpose〕

The present invention has been made in view of the above circumstances, and its purpose is to provide a simple inclination angle measuring device that is capable of high-speed processing.

[Structure of the invention]

The inclination angle measuring device according to the present invention includes an optical scanning device that scans a spot light in the inclination direction of the inclined surface at a constant scanning speed and a fixed incident angle on the inclined surface of a material to be measured; A position detector that detects the position of the spot light obtained by imaging the reflected light from the inclined surface, and a speed calculator that calculates the moving speed of the spot light detected by the position detector. a circuit, a calculated moving speed and the scanning speed;
The present invention is characterized by comprising an arithmetic circuit that calculates the inclination angle of the inclined surface with respect to a predetermined reference based on the incident angle.

〔Example〕

The present invention will be specifically explained below based on the drawings.
FIG. 1 is a schematic plan view showing an embodiment of the present invention, and 1 in the figure indicates one end of a steel pipe for oil wells. The end portion 1 has a tapered sloped portion where the tip side is smaller in diameter than the center side, that is, a bevel portion 1a. A tapered thread is cut.

An F-theta lens 4 of a required diameter is located at a position a little apart in the axial direction from the end face of the oil well steel pipe, and the optical axis direction is aligned with the axial direction, and the optical axis is set near the center point of the generatrix of the bevel portion 1a. It is located and arranged. In the direction opposite to the bevel portion 1a of the F-θ lens 4, an optical scanner 3 is provided which has a reflective surface at a position separated by the focal length thereof and rotates back and forth at a constant angular velocity about the reflective point. The optical scanner 3 is composed of a specular body of a suitable area and a device for rotationally driving the mirror, and its pivot is installed so that it can reciprocate in the thickness direction of the steel pipe end 1 or in the radial direction thereof.

A laser generator 2 is disposed at a position perpendicular to the optical axis of the F-θ lens 4 and a suitable distance away from the optical scanner 3, and the spot light generated by the laser generator 2 is directed to the optical scanner 3. The irradiated light is reflected by the optical scanner 3, and the direction of reflection of the reflected light is changed according to the rotation angle of the optical scanner 3, and the reflected light is reflected by the F-θ lens 4.
The beam enters the bevel portion 1a, becomes a spot light parallel to the optical axis by the F-θ lens 4 regardless of the incident angle, and is irradiated onto the bevel portion 1a, forming a light spot Po there.

Since the angular velocity of rotation of the optical scanner 3 is constant, the moving speed of the spot light or the moving (scanning) speed of the light spot Po on the bevel portion 1a is constant.

The radial dimension of the steel pipe in the scanning area of the light beam is set to be larger than (maximum diameter - minimum diameter)/2 at the bevel portion 1a to eliminate the influence of deceleration during reversal of the reciprocating rotation of the optical scanner 3. It is said that

A convex lens 5 is arranged with its optical axis aligned with a perpendicular line erected at the center point of the bevel portion 1a, and a center point is aligned on the optical axis on the opposite side of the convex lens 5 from the bevel portion 1a. One-dimensional optical spot position detector (for example, Hamamatsu Photonics, S-1352)
6 points its longitudinal direction to the light spot of the beveled portion 1a.
It is arranged parallel to the scanning area of Po or in the direction of the generatrix of the bevel portion 1a.

The laser beam irradiated onto the bevel portion 1 a is reflected here, and the reflected light is focused by a convex lens 5 and imaged on a position detector 6 .

Now, if the scanning speed of the spot light transmitted through the F-θ lens 4 is _V1 , then the moving speed _V2 of the light irradiated onto the bevel portion 1a on the surface of the bevel portion 1a is _V1.
Since the moving direction and angle of are different by the bevel angle θ, it is expressed by the following equation (1).

V ₁ =V ₁ /cosθ (1) Therefore, if V ₁ and V ₂ are known, cosθ is determined, and from this, the bevel angle θ can be determined.

V ₂ is determined from the velocity V ₃ of the light spot where the light reflected from the surface of the bevel portion 1a is focused by the convex lens 5 and imaged on the position detector 6. V ₂ is
It is expressed by the following equation (2), which is V ₃ multiplied by the magnification of the optical system.

V ₂ = (a/b)・V ₃ ...(2) However, a: Distance between the laser beam irradiation position of the bevel portion 1a and the convex lens 5 b: Distance between the convex lens 5 and the position detector 6 Therefore, instead of V ₂ By measuring V ₃ , the bevel angle θ can be measured.

That is, formula (3) is obtained from formulas (1) and (2), and V ₃ = (b・V ₁ )/(a・cosθ) …(3) Expressing this in terms of bevel angle θ, the following (4) The formula is obtained.

θ=cos ⁻¹ (a·V ₃ /b·V ₁ ) (4) Therefore, the bevel angle is substantially determined by a, b, V ₁ , and V ₃ . a, b, and V ₁ are obtained by measuring in advance when adjusting the optical system before measuring the bevel angle, and V ₃ is obtained from the output of the position detector 6 as follows.

The photoelectric conversion section of the position detector 6 has a light receiving surface that is long in the direction of the generatrix of the bevel section 1a, and as shown in FIG. IA and IB can be extracted.
The photocurrents IA and IB are inversely proportional to the distance from the end electrodes A and B to the spot position D, and are approximately proportional to the intensity of the incident light.

That is, if the distance between AB is L and the distance between AD is x,
The respective photocurrent values IA and IB are as follows: IA=IL-x/L (5) IB=Ix/L (6). Here I is the sum of IA and IB.

The position detector 6 supplies the photocurrent values IA and IB to the incident light position calculation circuit 7, which calculates the light spot position D.
Find the value of x representing x=LIB/IA/1+(IB/IA)...(7).

The incident light position calculation circuit 7 inputs the calculated x signal to the differentiation circuit 8.

The differentiating circuit 8 differentiates x, which changes continuously from moment to moment, with respect to time, and obtains the differential value of the amount of movement, that is, the speed _V3 .

V ₃ obtained in this way is input to the angle calculation circuit 9. The angle calculation circuit 9 uses the a, b, V ₁
This is an analog circuit that can calculate and output the bevel angle θ based on the above equation (4), and display the calculated value on the display 10.

The operator monitors this displayed value, and if the displayed value is within the allowable angle, the oil well steel pipe is determined to be a good product, and if it is outside of this range, it is determined to be a defective product.

In addition, in the present invention, the irradiation direction of the laser beam is not limited to the axial length direction between the oil wells, but it goes without saying that measurement can be performed even when the laser beam is irradiated from other directions. In this case, it is necessary to correct the angle in relational expression (1) between V ₁ and V ₂ according to the irradiation angle of the bevel portion 1a of the laser beam.

Further, in the above description, laser light is used for measurement, but the present invention is not limited to this, and other light may be used.

Furthermore, the present invention is not limited to reciprocating the optical scanner, but may also rotate at a constant angular velocity.

Furthermore, in the present invention, it goes without saying that an ordinary convex lens may be used in place of the F-.theta. lens, and the spot light may be moved at a constant speed in a direction perpendicular to the optical axis of the convex lens.

Furthermore, the present invention is applicable not only to the measurement of bevel angles of steel pipes for oil wells, but also to the measurement of inclination angles in general with respect to predetermined standards.

Note that a part or all of the position detector 6, the incident light position calculation circuit 7, the differentiation circuit 8, and the angle calculation circuit 9 can be configured with digital circuits and elements.

〔effect〕

As described in detail above, the present invention is configured to calculate the inclination angle by determining the one-dimensional positional movement of the spot light, so high-speed measurement is possible, and the apparatus has excellent effects such as being able to be simplified. play.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a diagram illustrating the measurement principle of a position detector, and FIG. 3 is a longitudinal cross-sectional view showing an end of a steel pipe for oil wells. 1... Oil well steel pipe end, 1a... Beveled part, 2
...Laser generator, 3...Optical scanner, 4...
F-θ lens, 5... Convex lens, 6... Position detector, 7... Incident light position calculation circuit, 8... Differentiation circuit, 9... Angle calculation circuit.

Claims (1)

[Scope of Claims] 1. An optical scanning device that scans a spot light in the direction of inclination of the inclined surface of a material to be measured at a constant scanning speed and at a constant angle of incidence, and installed toward the scanning area of the inclined surface. a position detector that detects the position of the spot light obtained by imaging the reflected light from the inclined surface; a speed calculation circuit that calculates the moving speed of the spot light detected by the position detector; An inclination angle measuring device comprising: an arithmetic circuit that calculates an inclination angle of an inclined surface with respect to a predetermined reference based on the calculated moving speed, the scanning speed, and the incident angle.