JPH0367573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the bending of a tube or rod-shaped body.

[Conventional technology]

Conventionally, the method of measuring the bending of a pipe or rod-shaped object is to measure the bending of a pipe or rod from a reference position at both ends and the middle of the object while it is stationary or being transported in a direction perpendicular to the longitudinal direction of the rod. A method of detecting the distances using an optical method and measuring the amount of bending from each of these distances (for example, JP-A-54-146653, JP-A-54-158261, JP-A-55-47406) or,
A method of supporting both ends of the material to be measured and rotating it, detecting the eccentric position of the center part and measuring the amount of bending (for example, JP-A-54-146656, JP-A-55
-63709) have been proposed.

[Problem that the invention seeks to solve]

It is of course possible to measure bending using the measurement method described above, but with the conventional method described above, for example, in the manufacturing process of electric resistance welded steel pipes,
Measurements can only be made at processes close to the final product storage area, and the measurement results are obtained too late to be of any practical use in order to feed back the measurement results to the pipe-making process to control the pipe-making process. The problem was that I couldn't get it.

In view of these circumstances, it is an object of the present invention to provide a method for measuring bending that is capable of measuring the bending of a pipe or rod even in the pipe-making process or a process close to this process, and that has high measurement accuracy. do.

[Means for solving problems]

For this purpose, in the present invention, an appropriate length portion of the material to be measured is supported in a cantilever state, and the material to be measured is placed in a plane including vertical cross sections at at least three locations in the longitudinal direction of the beam portion. A pair of distance detectors pointing at two different points on the same outer periphery of the material are arranged, and the geometrical arrangement of the distance detectors and the distance to the outer periphery of the material detected by the distance detectors are determined. and the outer diameter of the material to be measured, calculate the center position of each vertical cross section of the material to be measured, and calculate the amount of deflection of the material to be measured at each vertical cross section position due to the weight of the material to be measured. Each of the calculated center positions is corrected based on the calculated deflection amount, and the bending amount of the material to be measured is calculated from the series of each of the corrected center positions.

That is, in the present invention, for example, in the manufacturing process of electric resistance welded steel pipes, the pipe is rolled by left and right or top and bottom rolls on the output side of the pressure roll of the pipe making machine, the final roll of the straightening machine, or the pinch roll of the conveyance line. When the pipe is supported in a cantilevered state, the distance to two points on the outer circumference of the pipe is measured using a set of two distance detectors installed at positions corresponding to at least three points in the longitudinal direction of the pipe. Then, the center axis of the tube is calculated from the geometric arrangement of the distance detector, the distance to the outer circumference of the tube, and the outer diameter of the tube, and the amount of deflection due to the tube's own weight is calculated to determine the center axis calculated above. By correcting this, the direction and amount of bending in the pipe can be determined.

[Effect]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case in which the bending measuring method according to the present invention is applied to measuring the bending of a pipe will be described in detail based on the drawings.

FIG. 1 is a diagram showing the arrangement of a distance detector with respect to a material to be measured in an embodiment of the present invention.

In the figure, P is a pipe that is a material to be measured, and the left side portion of this pipe P in the drawing is supported by upper and lower rolls PR, and the part of the pipe P to be measured is in a cantilever state.

The distance detector measures the X-Y distance including the vertical cross section of the pipe P.
Two distance detectors D ₁₁ and D ₁₂ are arranged at a certain distance from the reference point O _z1 in the plane and at a certain interval. Although only one set of these two distance detectors D ₁₁ and D ₁₂ is shown in the figure, they are respectively arranged at at least three points in the longitudinal direction of the pipe P as shown in FIG.

As the distance detectors D ₁₁ and D ₁₂ , for example, known distance detectors such as a length meter using a laser or microwave, an eddy current displacement meter, or a capacitance displacement meter can be used. The distance detectors D ₁₁ and D 12 are mounted at a constant angle θ with respect to the X-axis, and detect the distance to the outer periphery of the pipe, which is on the extension of the axes of the distance detectors D _{11 and D 12} .

FIG. 2 is a diagram for explaining a method of calculating the center position of the tube from the geometrical arrangement relationship of the distance detectors D ₁₁ and D ₁₂ , the distance to the tube outer periphery, and the tube outer diameter.

As shown in the figure, since the mounting angle θ of the distance detectors D ₁₁ and D ₁₂ and their coordinates (x ₁₁ , y ₁₁ ), (x ₁₂ , y ₁₂ ) are known, the distance to the tube outer circumference L ₁₁ , Once L ₁₂ is obtained, the coordinates of points A ₁₁ and A ₁₂ on the outer circumference of the tube can be calculated.

Since the cross-sectional contour of the material to be measured P is a circle or an approximate circle, geometry shows that the center of the material to be measured P is located on the perpendicular bisector of the line segment A ₁₁ -A ₁₂ .

Therefore, from the mounting angle θ of the distance detector, the coordinates (x ₁₁ , y ₁₁ ), (x ₁₂ , y ₁₂ ), the distances L ₁₁ , L ₁₂ and the outer diameter D of the tube (known value or measured value), The center of the pipe P at the measurement point P′ ₁₀ (this is called the apparent center)
The coordinates (xp′ ₁₀ , yp′ ₁₀ ) of can be calculated.

Since this calculation procedure is a simple geometrical problem, explanation of the calculation formula etc. will be omitted.

By the way, as shown in Fig. 1, the pipe P is shaped like a cantilever.
When supported, the tube is deflected due to its own weight, so by correcting the amount of movement of the center of the tube due to this deflection, the center P ₁₀ of the tube P when there is no deflection (this is called the true center) can be calculated. I need to find the coordinates.

Deflection amount yt of the pipe P due to its own weight at the measurement point
is calculated using the formula of mechanics of materials using the cross-sectional dimensions of the pipe P, specific gravity, elastic modulus, pipe length from the support point to the measurement point, and the amount of protrusion of the material to be measured (the length from the support point to the tip of the pipe). Can calculate.

It is not necessary to provide a measuring device for measuring the amount of protrusion of the material to be measured, as long as the bending measurement is performed when the tip of the material to be measured reaches the third detector position. The fact that the tip of the material to be measured has come to the third detector position means that
This can be easily determined by monitoring the signal from the second detector. In addition, if you want to measure the bending continuously, if you add various known length measuring means such as rotary encoders to the upper and lower PR rolls, the protrusion amount can be easily determined continuously. The amount of deflection and bending after the tip of the tube passes through the detector can also be easily and continuously determined.

The apparent center coordinates (x _p ′ ₁₀ , y _p ′ ₁₀ ) are corrected by the amount of deflection yt due to this self-weight, and the coordinates after this correction (x _p10 , y _p10 ) are the coordinates of the true center P ₁₀ . do.

Now, if three sets of two distance detectors are installed at intervals in the longitudinal direction of the pipe P and the above calculation is applied to each measurement point, the true center coordinates of the three points in the longitudinal direction of the pipe can be obtained. It will be done.

Now, assuming that the longitudinal direction of the pipe is the z-axis and the installation positions of the three sets of distance detectors are equally spaced, that is, |Oz ₁ −Oz ₂ |= |Oz ₂ −Oz ₃ |, the distance between each measurement point and each measurement point is The geometric relationship of is shown in Fig. 3, and the coordinates of the true center of the tube P ₁₀ , P ₂₀ , P ₃₀ at each measurement point are (xp ₁₀ , yp ₁₀ , Oz ₁ ), (xp ₂₀ , yp ₂₀ , Oz ₂ ),
(xp ₃₀ , yp ₃₀ , Oz ₃ ).

As can be seen from Fig. 3, the left-right component of the pipe's bend is found on the X-Z plane, and the vertical component of the pipe's bend is found on the Y-Z plane. , on the X-Z plane as shown in FIG. 4a, and on the Y-Z plane as shown in FIG. 4b.

The amount of bending Lx on the X-Z plane is the line segment xp ₁₀ −
When the midpoint of xp ₃₀ is xp″ ₂₀ , Lx≒(xp ₂₀ −xp ₂₀ )・cosφx …(1) However, φx＝tan ⁻¹ ｜(xp ₃₀ −xp ₁₀ )／(Oz ₃ −Oz ₁ )｜xp ₂₀ = (1/2)・(xp ₁₀ + xp ₃₀ ).

Similarly, the amount of bending Ly on the Y-Z plane is as follows: Ly≒(yp ₂₀ − yp ₂₀ )・cosφy …(2) However, φy=tan ⁻¹ | (yp ₃₀ − yp ₁₀ )/(Oz ₃ − Oz ₁ ) | yp ₂₀ = (1/2)・(yp ₁₀ + yp ₃₀ ).

Therefore, the combined bending amount L is obtained as L=√ ² + ² (3).

In addition, the apparent bending is calculated from the apparent center, P′ ₁₀ , P′ ₂₀ , P′ ₃₀ and the deflection equivalent P″ ₁₀ ,
It goes without saying that the true curvature can be determined by correcting the apparent curvature with the curvature due to the deflection determined from P″ ₂₀ and P″ ₃₀ . Further, the direction of bending can be expressed as follows, for example, when expressed by an angle φ clockwise with respect to the apex.

When Lx=0, Ly>0, φ=0...(4) When Lx=0, Ly<0, φ=π...(5) When Lx>0, φ=(π/2)−tan ^-1 ( Ly/Lx) …(6) When Lx<0 φ=(3π/2)−tan ^-1 (Ly−Lx) …(7) The reference point for expressing the bending direction is, for example, the welded part of a welded pipe. By measuring the position using another method and expressing that position as a reference point, you can see how the bending direction is relative to the welding point, which provides useful information for operations.

As described above, the amount and direction of bending of a tube supported in a cantilevered state can be measured.

By the way, in an actual pipe manufacturing line, the length of the pipe is not constant, and the length that can be supported in a cantilever state also changes depending on the outside diameter and wall thickness of the pipe, so the distance detection of the fixed arrangement described above is difficult. With the method using an instrument, it is not possible to measure the bending of the support section for all tubes of different support lengths.

To be able to measure support sections of different lengths, a number of distance transducers can be arranged within a range corresponding to the maximum length, or at least one distance transducer can be installed in a movable manner. There is a need to.

However, in the manufacturing of ERW pipes, for example, pipe bends often occur continuously with the same curvature, so in such cases, the method described above can be used to measure the amount of bend at a certain length. , the amount of bending of any length can be calculated from the amount of bending of this portion. This calculation method is as shown in Fig. 5. If the radius of curvature of the entire material to be measured is a constant value R, the length of the measured part is l, and the amount of bending at length l is L, then an arbitrary length l ₀ The amount of bending L ₀ can be approximately determined by L ₀ ≒ (l ₀ /l) ² ·L (8).

[Effects of the Invention] Since the method for measuring the bending of pipes and rod-shaped bodies according to the present invention is as described above, it is possible to measure the bending online in the manufacturing line of pipes and rods, and it is possible to It is possible to perform accurate bending measurements by excluding the influence of deflection due to the material's own weight.
Feedback of measurement results to operations can be made effective and can greatly contribute to improving product quality.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the arrangement of the distance detector with respect to the material to be measured in one embodiment of the present invention;
The figure is a front view for explaining the calculation method of the cross-sectional center position of the material to be measured, FIG. 3 is a perspective view showing a series of cross-sectional center positions of the material to be measured at each measurement point, and FIG.
Figures a and 4b are graphs for explaining the method of calculating the amount of bending of the material to be measured, and Figure 5 is a diagram for explaining the method of calculating the amount of overall bending from the amount of partial bending. This corresponds to a side view of the pipe P.

Claims (1)

[Claims] 1. Support an appropriate length of the material to be measured in the state of a cantilever beam, and place on the same outer periphery of the material to be measured within a plane including vertical cross sections at at least three locations in the longitudinal direction of the beam portion. A set of two distance detectors pointing at two different points is arranged, and the geometrical arrangement relationship of the distance detectors, the distance to the outer periphery of the material to be measured detected by the distance detectors, and the outer circumference of the material to be measured are determined. The center position of each vertical cross section of the material to be measured is calculated from the diameter, and the amount of deflection of the material to be measured at each vertical cross section position due to the weight of the material to be measured is calculated based on the amount of protrusion of the material to be measured. A method for measuring the bending of a tube-rod-shaped object, characterized in that each of the calculated center positions is corrected based on the calculated deflection amount, and the bending amount of the material to be measured is calculated from a series of the corrected center positions. .