JPH0671359A - Method for detecting bend of steel tube - Google Patents

Abstract

PURPOSE:To enable measuring in real time the direction and amount of bend of steel tube during expansion by arranging a prescribed number of non-contact type distance measuring devices in the downstream direction from a tube expansion head. CONSTITUTION:The non-contact type distance measuring devices 4a-4f are arranged at least in three places at equal spaces apart on a boom 2 in the downstream direction from the tube expansion head 3. Also these distance measuring devices 4a-4f are arranged for an adequate angle on the peripheral surface of the boom 2 so as to measure in at least two directions a distance to the inner surface 5, 6 of the steel tube 1 with the peripheral surface of the boom 2 as a reference. Namely, the distance measuring devices are arranged dividedly in groups, 4a-4c and 4d-4f. The distance measuring devices of each group are arranged in parallel to the center axis 7 of the boom 2 and nearly in a straight line. A reference ultrasonic distance measuring device 4l is attached to the boom 2, and the variance of sound velocity due to temperature is compensated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting bending of a UOE steel pipe by detecting the bending direction and the amount of bending of the pipe online.

[0002]

2. Description of the Related Art When making a UOE pipe, the pipe is expanded by a pipe expander in order to improve the shape and remove the residual stress caused by welding. At the time of this pipe expansion, it is important to know the bend before the pipe expansion from the viewpoint of the accuracy of the pipe expansion operation. There are very few proposals for this purpose, and a representative example thereof is that of Japanese Utility Model Laid-Open No. 61-107431. This means that the distance between the boom and the inner surface of the pipe on the downstream side of the pipe expanding head (which means the downstream side with respect to the direction in which the steel pipe is fed. The same applies hereinafter) is set in the circumferential direction using a plurality of measuring rolls. The amount of bending is detected by measuring at a point.

[0003]

However, in the method disclosed in the above publication, the means for bringing the measuring roll into contact with the inner surface of the steel pipe is mechanically complicated, and the measuring roll is repeatedly expanded and contracted at each pipe expanding step. Since it must be done, it takes time, and the detection accuracy is not high due to the influence of vibration and the like. When expanding the first half, the unexpanded part still has a warp due to the residual stress of the bead weld, and the axis of the steel pipe before and after the expanding head is not parallel to the boom. Therefore, the tilt information obtained by the reference position measurement and the displacement measurement after the pipe expansion includes the influence of the warp of the unexpanded portion, and there is a problem that the accurate bend measurement cannot be performed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for detecting bending of a steel pipe which can accurately detect bending in real time during pipe expansion.

[0005]

In order to achieve the above object, the method for detecting the bend of a steel pipe according to the present invention measures the bend by the reference position measurement after pipe expansion and the inclination information by the displacement measurement as described above. Rather than measuring the boom circumference, the distance from the boom circumference to the steel pipe inner surface is measured at least at two locations in the circumferential direction with a non-contact distance meter attached to the boom circumference. Then, the bending direction and the bending amount of the steel pipe are detected by calculating the measurement value obtained as a result.

In addition, the present invention uses an ultrasonic range finder as a non-contact type range finder and corrects the bending amount of a steel pipe by using a jig having support legs at both ends which come into contact with the peripheral surface of the boom. is there.

[0007]

[Operation] By arranging at least three non-contact distance meters at equal intervals in the downstream direction of the pipe expanding head and at least two places in the boom circumferential direction, to measure the distance from the boom peripheral surface to the steel pipe inner surface during pipe expanding. You can If the measured values of these rangefinders are calculated by the method described below, the bending direction and bending amount of the steel pipe can be detected in real time.

When it is attempted to detect the bending of the steel pipe by the ultrasonic range finder at a relatively short interval immediately after the pipe expanding head as in the present measuring method, a slight variation in the zero point of each range finder or the range finder. Since the bending information fluctuates greatly due to the asymmetry of the mounting seat surface of the robot with respect to the boom center axis, in order to calibrate these comprehensively and easily, use a jig that has support legs that contact the peripheral surface of the boom at both ends. hand,
By measuring the distance from the circumferential surface of the boom to the inner surface of the jig and correcting the bending amount of the steel pipe obtained above with these measured values, the bending of the steel pipe can be measured with high accuracy.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view showing an embodiment of a method for detecting bending of a steel pipe according to the present invention. In the drawing, 1 is a steel pipe to be treated (hereinafter simply referred to as steel pipe) while being expanded, and 2 is a pipe expanded at a tip thereof. A boom having a head 3 whose base end is fixedly held by a tube expander body (not shown). Reference numerals 4a to 4f are non-contact distance meters which are arranged at equal intervals on the peripheral surface of the boom 2 in the downstream direction of the pipe expanding head 3, and in this embodiment, for example, ultrasonic distance meters are used. These rangefinders 4a-
In order to measure the distance to the inner surfaces 5 and 6 of the steel pipe 1 in at least two directions with reference to the peripheral surface of the boom 2, 4f is distributed on the peripheral surface of the boom 2 at an appropriate angle, that is, the distance meters 4a to 4c. And the rangefinders 4d to 4f are arranged separately. The distance meters of each set are arranged in parallel with the central axis 7 of the boom 2 and on a substantially straight line. In the embodiment, two sets of rangefinders are arranged 180 ° apart.
Reference numeral 4g is a reference ultrasonic rangefinder for correcting the span variation of the ultrasonic rangefinders 4a to 4f due to sound velocity variation, and has a reflector 4h at the reference distance. The reference ultrasonic rangefinder 4g is attached to the boom 2. It will be installed and the sound velocity fluctuation due to temperature will be corrected.

The UOE steel pipe 1 is intermittently fitted and inserted into the pipe expanding head 3 of the boom 2 by a predetermined length, and the pipe is expanded by the expanding operation of the pipe expanding head 3 at this time. Therefore, next, the bending detection method of this embodiment will be described with reference to FIG. FIG. 2 is a diagram showing the measurement principle of this measurement method. If the measured value of each distance meter 4a to 4f at the position where the steel pipe 1 is inserted with an arbitrary length is xi, the boom center shaft 7
The deviation yi of the central axis 8 of the steel pipe 1 from the above is y1 = x1 -x4 y2 = x2 -x5 y3 = x3 -x6, and the amount M representing the bending of the central axis 8 is M = (y1 + y3) / 2-y2 ( 1) Therefore, if the value of M in equation (1) is positive or negative, the steel pipe 1
The bending direction can be determined, and the amount of bending can be determined by the magnitude of the M value.

Next, a method of calibrating the bending amount M of the steel pipe obtained by the equation (1) will be described. This is because when the bending of the steel pipe is to be detected by the ultrasonic distance meters 4a to 4f at a relatively short interval immediately after the pipe expanding head as described above, there are slight variations in the zero points of the distance meters 4a to 4f. This is because the bending information greatly changes due to the asymmetry of the mounting surface of the rangefinder with respect to the boom center axis 7.
Therefore, in order to calibrate these comprehensively and easily, the bending amount M is calibrated using a jig 10 as shown in FIG. The jig 10 is a straight line having a certain degree of straightness and rigidity, and the ends of the jig 10 come into contact with the circumferential surface of the boom 2 and the boom 2
Has support legs 10a and 10b that are held substantially concentrically with. The calibration with the jig 10 may be performed twice in total in the two directions of the distance meter mounting portion before or after the tube expanding operation.

As shown in FIG. 3, a supporting leg 10 of the jig 10 is provided.
The lengths of a and 10b are respectively l1 and l2, the straightness at the central portion of the jig 10 is Δ with the outer direction being a positive sign, and the distance meters 4a to 4f are measured when the jig 10 is brought into contact with the boom 2. Value is xi1, each distance meter 4a-4f when steel pipe 1 is inserted
Where xi is the measured value of each distance meter 4a to 4f and the distance to the boom center axis 7 of the seat surface of each distance meter 4a-4f is ai, the distance from the peripheral surface of the boom 2 to the steel pipe inner surfaces 5 and 6 at the seat surface position of the distance meter. Is x1 + (l1-x11) x3 + (l2-x31) x4 + (l1-x41) x6 + (l2-x61) For the central rangefinders 4b and 4e, from the intermediate surface of both seats to the inner surface of the steel pipe 5, The distance to 6 is x2 + ([l1 + l2] / 2 + [Delta] -x21) x5 + ([l1 + l2] / 2 + [Delta] -x51). Assuming that the distance between the intermediate position of the seats on both ends and the boom center axis 7 is a2, a5, then a2 = (a1 + a3) / 2 a5 = (a4 + a6) / 2. Therefore, the deviation yi of the central axis 8 of the steel pipe 1 from the boom central axis 7 is y1 = {x1 + [l1-x11] + a1- (x4 + [l1-x41] + a4)} / 2 = (x1-x4) / 2- (x11-x41) / 2 + (a1-a4) / 2y2 = {x2 + [l1 + l2] /2+.DELTA.-x21+a2-(x5 + [l1 + l2] /2+.DELTA.-x51+a5)} / 2 = (x2-x5 ) / 2- (x21-x51) / 2 + (a2-a5) / 2y3 = {x3 + [l2-x31] + a3-(x6 + [l2-x61] + a6)} / 2 = (x3-x6) / 2- (x31-x61) / 2 + (a3-a6) / 2. Therefore, the amount M representing the bending of the central axis 8 of the steel pipe 1 of the formula (1) is M = (y1 + y3) / 2-y2 = {(x1-x4) / 2- (x11-x41) / 2 + (a1- a4) / 2 + (x3-x6) / 2- (x31-x61) / 2 + (a3-a6) / 2} / 2-{(x2-x5) / 2- (x21-x51) / 2 + (a2- a5) / 2} = {(x1-x4) / 2 + (x3-x6) / 2} / 2- (x2-x5) / 2-{(x11-x41) / 2 + (x31-x61) / 2} / It becomes 2+ (x21-x51) / 2 (2). Here, since the distance between the intermediate surface of the two end bearing surfaces and the boom center axis is a2, a5, the relationship of a2 = (a1 + a3) / 2a5 = (a4 + a6) / 2 is used. Therefore, from the formula (2), each distance meter 4a when the jig 10 is brought into contact with the peripheral surface of the boom 2
The correction value of the bending amount can be obtained by using only the measured values x11, x21, x31, x41, x51, x61 of 4f.

In FIG. 4 and FIG. 5, the distance mounting pitch l = 1
Here, an example is shown in which the bending in the left-right direction is measured with m as the mounting direction and the mounting directions have an angle of 180 ° with each other. In the figure, “expanding” indicates that the tube expanding head 3 is expanding, and “contracting” in the figure indicates that the tube expanding head 3 is contracting, indicating “feeding” in the figure. There is
This shows that the steel pipe 1 is being inserted into the pipe expanding machine (hereinafter, abbreviated as "feeding"). The fifth time in FIG. 4,
In FIG. 5, at the time of the fourth feeding operation 11, the six total distance meters 4a to 4f entered the inside of the steel pipe 1 and the measurement was started. Other than the timing of 12 during feeding, that is, during the stop 13 of the steel pipe 1 including during expansion and contraction, although the deviation yi of the central axis 8 of the steel pipe 1 greatly changes, the value of the stable bend M is Has been obtained. FIG. 4 shows a steel pipe having a relatively small bend, and FIG. 5 shows that it is convex in the mounting direction of the distance meter 4e.

Here, for simplification, the case where measurement is performed at three points in the axial direction and two points in the circumferential direction has been described. This is a case where only the bending of the steel pipe in the left-right direction or the vertical direction is measured.
However, in the case of measuring at four points in the circumferential direction, it is possible to simultaneously measure the bending in both the left and right directions and the up and down directions, and the present invention does not exclude such a case. Needless to say, the number of measurement points in the axial direction can be three or more.

A case will be described below in which the measurement is performed at four points in the circumferential direction and the bendings in both the left and right directions and the up and down directions are simultaneously measured. FIG. 6 is a layout view of a non-contact distance meter in the case of simultaneously measuring the bending in the vertical and horizontal directions. The same parts as those in FIG. 1 are designated by the same reference numerals. As shown in FIG. 6, since the weld bead portion 14 is generally inserted vertically upward during pipe expansion, the distance meter mounting axis is set vertically so that the target surface of the non-contact distance meter does not overlap the bead portion 14. It has an angle to the axis. And rangefinders 4a-4f
Fig. 7 (a) shows the measurement state in the plane including
FIG. 7B shows a measurement state in the plane including i to 4n. The deviation between the tube center axis 8 and the boom center axis 7 in the former plane is Xi (i = 1 to 3), and the bending amount is Mx. The deviation between the tube center axis 8 and the boom center axis 7 in the latter plane is Y
Let i (i = 1 to 3) and the amount of bending be My. Where X
i and Yi are as follows using x1 to x6 and x7 to x12, respectively. X1 = x4 -x1 X2 = x5 -x2 X3 = x6 -x3 Y1 = x10 -x7 Y2 = x11 -x8 Y3 = x12 -x9

Next, the measured value X on the mounting surface of the rangefinder
A method of obtaining the amount of bending in the vertical or horizontal direction from i, Yi will be described with reference to FIG. The angle formed by the mounting surfaces of the rangefinders 4a to 4f in the horizontal direction is α, the angle formed by the mounting planes of the rangefinders 4i to 4n in the horizontal direction is β, and the intersection point between each rangefinder mounting surface and the pipe central axis 8 is Oi. Then, measured values Xi, Yi, horizontal displacement ξi, vertical displacement ηi
The relationship is as shown in FIG. a1i = Xi * sinα + Xi * cosα / k1 a2i = Yi * sinβ + Yi * cosβ / k2 and a1i and a2i are defined. Here, k1 and k2 are k1 = tan α k2 = tan β. At this time, ξi and ηi are ξi = k1 * k2 * (a1i-a2i) / (k2-k1) ηi = (k1 * a1i-k2 * a2i) / (k1-k2). Therefore, if the horizontal bending amount M _ξ is M _ξ = (ξ 1 + ξ 3) / 2-ξ 2 and the vertical bending amount M _η is M _η = ( _η 1 + η 3) / 2- _η 2, the horizontal and vertical bending amounts Can be calculated.

[0017]

As described above, according to the present invention, by disposing the non-contact distance meters at least at three positions at equal intervals in the downstream direction of the pipe expanding head and at least two positions in the boom circumferential direction, the steel pipe is expanded during pipe expansion. The bending direction and the bending amount of can be measured in real time. In addition, by correcting the bending amount of the steel pipe by using a jig, the bending amount due to slight variations in the zero point of the ultrasonic rangefinder and asymmetry of the distance seat mounting surface with respect to the boom center axis It eliminates errors and enables highly accurate bending measurement of steel pipes.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a principle of measuring a bend.

FIG. 3 is an explanatory diagram showing a calibration method using a jig.

FIG. 4 is an explanatory diagram showing an example of measurement results in an example.

FIG. 5 is an explanatory diagram showing another example of the measurement result in the example.

FIG. 6 is an explanatory diagram showing another embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a measurement state in the embodiment of FIG.

FIG. 8 is a coordinate relationship diagram for obtaining a bending amount in the embodiment of FIG.

[Explanation of symbols]

 1 Steel Pipe 2 Boom 3 Pipe Expansion Head 4a-4f Non-contact Distance Meter (Ultrasonic Distance Meter) 5,6 Steel Pipe Inner Surface 7 Boom Center Axis 8 Steel Pipe Center Axis 10 Jigs 10a, 10b Jig Support Leg 11 Measurement Start 12 Feed Medium 13 Steel pipe stopped

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[Procedure amendment]

[Submission date] September 28, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Further, according to the present invention, the bending amount of the steel pipe is corrected by using a jig having support legs at both ends which are in contact with the peripheral surface of the boom.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Sawa Marunouchi 1-2-2, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Lawyer Mifune Mitsuo 1-2-Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (2)

[Claims] 1. When expanding a pipe by fixing and holding a base end of a boom having a pipe expanding head at a tip thereof, and performing a pipe-expansion of the steel pipe to be processed by intermittently fitting the pipe to be processed to the pipe expanding head by a predetermined length. At least three locations at equal intervals in the downstream direction from the head, with reference to the circumferential surface of the boom,
Bending of the steel pipe is measured by measuring the distance to the inner surface of the steel pipe at least at two positions in the circumferential direction by a non-contact distance meter arranged on the peripheral surface of the boom, and calculating the resulting measurement value. A method for detecting bending of a steel pipe, characterized by detecting a direction and a bending amount. 2. An ultrasonic range finder is used as the non-contact type range finder, and a bending amount of the steel pipe is corrected by using a jig having support legs at both ends that contact the peripheral surface of the boom. The method for detecting bending of a steel pipe according to claim 1.