JPS59110476A - Method for controlling automatically position of inside surface welding head for spiral pipe making machine - Google Patents

Abstract

PURPOSE:To control automatically an inside surface welding head so as to follow up exactly the weld line in the process for manufacturing a spiral welded steel pipe by controlling the position of said head in accordance with the correlation between the extent of the movement of the end faces of a steel strip in the forming angle thereof before the inside surface melding point and the extent of the movement of the welding head position in the axial direction of the pipe. CONSTITUTION:A spiral welded pipe 1 is produced by welding an inside surface welding point 6 with a welding core wire 4 fed to an inside surface welding head 3 from a weldong core wire feeder 2. The fluctuation in the position of the end face of a steel strip 5 in the forming angle direction thereof is detected near the point 6 by a device for detectong the rate of the fluctuation in the end face of the steel strip. The extent of the movement of the head 3 is calculated by the relation [ I ] between the extent of said movement and the extent B of the movement of the position of the head 3, which can follow up the fluctuation in the point 6 with high accuracy, in the axial direction of the pipe, in accordance with the detected extent A thereof. The head 3 is moved in the axial direction of the pipe in accordance with the calculated B, whereby the inside surface welding under the automatic control is exactly accomplished without posititional deviation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for automatically controlling the position of an internal welding head to follow changes in internal welding points in the manufacture of spiral welded steel pipes.

As is well known, spiral welded steel pipes are manufactured by forming a copper strip trimmed to a certain width into a spiral shape, and welding the inner and outer surfaces at the same time.In the above inner welding, the end surface of the copper strip is first welded during forming. This inner welding point is carried out at the butt part where it meets the steel strip, but this inner welding point constantly moves in the tube axis direction due to the influence of the camber of the copper strip and the swinging during feeding of the steel strip, causing positional deviation. There is. Therefore, if the inner welding point is misaligned in 4-1, welding will result in poor penetration.
Since welding defects such as blowholes and slag inclusions occur, it is essential to accurately locate the inner welding point when welding in order to maintain welding quality. In response to the positional deviation, a method has been used in which an operator moves the inner welding head using a motor or hydraulic pressure to follow the fluctuation of the inner welding point. However, since this method requires manual operation, it is impossible to accurately follow the position of the inner surface head against sudden fluctuations in the inner surface welding point caused by camber of the copper strip or the like.

In order to solve these problems, a detector detects the positional fluctuation of the steel strip end face, and the internal welding head is moved by hydraulic pressure or motor drive according to the detected amount, and the position of the internal welding head is automatically tracked. A device to perform this is being developed.

Such a welding position automatic tracking device is disclosed in, for example, Japanese Patent Publication No. 44-1
．． It is known from Publication No. 6968.

However, the automatic tracking devices of these conventional internal welding devices detect the amount of variation in the end face of the steel strip, for example, by the amount of movement in the tube axis direction, and automatically follow it by moving the position of the internal welding head using that amount of movement. However, in spiral pipe manufacturing where the steel strip has a complicated flow, the amount of variation of the end face of the copper strip and the amount of variation of the inner welding point on the same straight line do not necessarily match, so automatic tracking using the above device can detect high rust. The problem has been that automatic tracking of the internal welding head position is insufficient.

The present invention has been made to solve the above problems.In spiral pipe manufacturing, where the steel strip fluctuates in a rough flow due to camber, rocking, etc., and the internal contact resistance changes accordingly, the internal welding point An object of the present invention is to provide an automatic control method for the inner welding head position of a spiral pipe making machine, which enables automatic tracking of the inner welding head position with high accuracy in response to fluctuations.

The present inventors have conducted various experimental studies to develop a method that allows the position of the inner welding head to automatically follow the position of the inner welding head with high accuracy in response to variations in the inner welding point caused by variations in the position of the end face of the copper strip. As a result, there is a difference between the amount of variation in the forming angle direction of the end face of the copper strip in front of the inner welding point and the amount of movement of the inner welding head position in the tube axis direction, which can follow the variation of the inner welding point with high accuracy. We discovered a new fact that a certain correlation exists. Therefore, based on the above correlation, it has become possible to calculate with high accuracy the amount of movement of the inner welding head position corresponding to the variation of the inner welding point from the amount of variation of the steel strip end surface.

In other words, in spiral pipe manufacturing, when there is a fluctuation in the flow of the copper strip due to camber, etc., it is assumed that the steel strip rotates along the side guide rolls (indicated by 7 in Figure 2), and the above fluctuations are avoided. An attempt was made to analyze the amount and amount of movement.

FIG. 1 is a plan view schematically showing a state in which the end face PP of the copper band is rotated along the side guide roll as shown by the broken line QQ around the rotation axis of the side guide roll based on the above assumption. In the figure, a: Detection position of variation in steel strip end face b = Position of inner welding head C: Weld seam detection position 0: Center of rotation of side guide roll a A: Amount of variation in forming angle (θ) direction of copper strip end face bG = Movement amount of the inner welding head position in the tube axis direction c c': Variation amount of the weld seam in the tube fi11 direction θ: Growth angle, θ□: PP
The distance oo between 0 in the forming angle direction and the end surface, which is the angle formed by Xt order θ, eo, +o, o2+
o2a+a b = 1020/cosθ, old+d
o2=oo1Xtan01, da=ola-o, d, and the following formula ■■■ is aa=daXtanθ□ ・
・・・・・・・・・・・・・・・・・・・・・・・・
...River・■1)l) = (aa4-ab)Xtan
θ, /cO8θ...Picture...■ca=(d
a+ab+bc)x tanθ, /c o sf-・-
(4) Established.

Also, since (o, a-old)Xtanθ-aa,
The following formula ■(0,a-3L O/2 t anθ1)Xta
nθ,=aa−・−・−・・−”■ holds, and if aa′ is arbitrarily determined, θ1 can be found.

Next, outer diameter 600+mX-9m thickness, outer diameter 81. Z 8
mmX 9mm thickness, outer diameter 1000+nmX t 2ra
Three types of spiral pipe making tests with n thickness were conducted, and in the test, the distances ab and bc were actually measured for each pipe size, and the
The theoretical value of each ratio of C/aa:cc/ba was compared between the actual measured value and the theoretical value. The above results are summarized in Table 1.

" [ " As shown in Table 1, the ratio of the weld seam variation (cc,) to the variation of the copper strip end face (aa) is almost the same as the theoretical value and the measured value, and the amount of movement of the inner welding head position is It was found that by operating the inner welding head using a value obtained by multiplying the amount of variation in the end face of the steel strip by a certain coefficient, it was possible to follow the variation in the inner welding point with high accuracy.

The present invention has been made based on the findings mentioned above, and its gist is to detect positional fluctuations in the forming angle direction of the steel strip end surface near the inner acid contact point in the manufacture of spiral welded steel pipes, Based on the detected amount (2), the following formula ■ αA-B=o ・・・・・・・・・・・・・・・・・・
...■Here, A: Amount of variation in the forming angle direction of the steel strip end surface B: Amount of movement of the inner surface welding head in the tube axis direction α: Amount of movement of the inner surface welding head according to a coefficient corresponding to the tube diameter and wall thickness Calculate the movement amount (
Based on item 2), there is provided an automatic control method for the position of the inner welding head of a spiral pipe making machine, characterized in that the inner welding head is moved in the axial direction of the tube to perform inner welding.

Next, the method of the present invention will be explained based on the drawings.

FIG. 2 is an explanatory diagram showing an example of an apparatus for carrying out the method of the present invention.

As shown in FIG. 2, the spiral welded pipe (1) is side guided by the welded core (4), which is sent from the welded core feeding device (2) and whose tip is supported by the inner welding head (3). The copper strip (5) is sent along the roll (7) and shaped.
It is manufactured by welding at the inner welding point (6). The device for carrying out the method of the present invention is ``In the illustrated example, a device for detecting the amount of variation in the end surface of the copper strip (5), which is provided to detect the variation in the end surface of the copper strip (5) at a position close to the inner welding point (6). 8) and the inner welding head (3).
2) and the inner welding head position detection device (9) attached to these devices (8) (9) and the welding core feeding device (2)
and an automatic control device (40) that automatically controls the operation.

First, the detection device (8) for detecting the amount of variation in the end face of the copper strip consists of a flow port holder 0υ, a slide shaft (6) that is held movably forward and backward by a rack mechanism, and the main body of the detection device provided at the tip of this slide shaft. α [Yes], and the flow port holder (1
The base of 0 is rotatably mounted on a slide base 04) movably provided on a rail laid toward the copper strip (5). The detection device main body u3 includes a detection roller u0 that contacts the end face of the copper strip in the forming angle (θ) direction, and this roller 00.
It consists of a detection base QQ that detects the movement of the steel strip end surface in conjunction with the detection base α→, and a magnetscale α force that measures the detected amount of the detection base QO in contact with the detection base α→ and converts this detected amount into an electric signal. has been done.

-1- Operate the slide base μ→ and the flow port holder μυ to set the slide shaft (1) parallel to the traveling direction (a) of the steel strip (5), and move the detection roller tJO to the detection point of the amount of variation on the end face of the steel strip. When the detection device main body α is set, the detection roller μ rotates as the copper band (5) advances.
When a change occurs in the end face of the copper strip, the amount of change in the forming angle ψ) direction is transmitted to the Magnescale θη via the detection base uQ, and the amount of change is measured using the Magnescale α force.

Next, the inner welding head position adjustment device (9) will be explained.

Prior to the above explanation, the mechanism of a commonly used welding core feeding device (2) will be briefly explained.

In the illustrated example, the welding core feeding device (2) installed to feed two welding cores (4×4) is the inner beam α8).
The support base (l) is fixedly supported by the core wires (4) (4)
A slide base Q0 is equipped with feed motors (A) and (E) for feeding and is slidably placed thereon, and an annular ring (2) connected to this slide base (2◇ by a connecting rod (A)
3 is screwed together (J is protruded from the rotating shaft, and the screw tube (
A motor (c) that moves the slide base (2]) forward and backward by rotation of the slide base (c); a push rod (a) protruding from the slide base (21);
(To) Internal welding head support device installed at the tip (C)
It is composed of. In addition, as shown in the side view of FIG. 3, this internal welding head support device V) has a slide base (c) attached to the tip of the bushing rod that is movably placed on the pedestal. , an inner welding head (3) protruding downward from the slide base (c);
(3) holds the tip of the weld core wire (4) (4).

In other words, the slide base (2]) advances and retreats in the direction of the tube axis (b) due to the rotation of the motor (c), and the bushing rod (a) advances and retreats accordingly, causing the inner welding head (3) to move forward and backward.
The position (3) is moved forward and backward in the direction of the tube axis (b).

The inner welding head position detection device (9) has a limit fitting (
7), and a Magnescale (32) that measures the amount of movement of the detection base (31) and converts it into an electrical signal. As shown in the side view of FIG. 3, the limit fitting (7) to which the detection base (31) is attached is erected on the slide base Qp of the welding core feeding device, and the detection base (31) is A Magnescale (32), which measures the amount of movement of the detection base (3 pieces) and converts it into an electric signal, is mounted on a stand (
33). (341) is the forward limit, and (342) is the backward limit, which limits the moving range of the limit metal (7) or Magnescale (32) in order to prevent it from going outside the measurable area and becoming impossible to measure. It is set up to limit.

Next, the automatic control device uo that implements the present invention performs necessary calculations based on the electrical signals from the aforementioned Magnescale Uη, (32) J-, and Magnescale α force (32), and controls the welding core feed. A controller (3) that automatically controls the position of the welding head by giving necessary instructions to the motor (C) of the feeding device (2).
5), and the above Magnescale Qη(32)
A circuit (3) is connected between the motor (c) and the controller (35).
6) is formed. Still (37x37) are D/A converters of electrical signals from Magnescale tl17) (32), respectively.

Next, the operation of the method of the present invention using the apparatus configured as described above will be explained.

When fluctuations occur in the steel strip (5) due to camber, etc., the amount of fluctuation (2) in the forming angle direction is determined by Magnescale (17).
and is input to the controller (35) via the I)/A converter (37). The controller (35) immediately commands the motor (to) to start rotating, and moves the inner welding head based on αA-B=o in equation (2). ([
3) Calculate. On the other hand, the amount of movement of the detection base (31) due to the rotation of the motor (c) is calculated using the magnescale (32).
At the same time, the amount of movement is continuously measured by a controller (3
5). When the amount of movement of the detection base (31) matches the above (5), the rotation of the motor (A) is stopped, and internal welding is performed at the position of the internal welding head.

In this way, automatic control is performed so that the position of the inner welding head (3) moves by B in accordance with the amount of variation (5) of the steel strip (5), and the center of the inner weld seam is precisely aligned. Since the internal welding head captures the internal welding point and performs internal welding, welding quality is improved.

Next, the present invention will be described in detail with reference to Examples.

Example 1 Using the apparatus for implementing the present invention shown in FIG.
Width 1305mm, outer diameter 600mm, plate thickness 90mm x width 155mm
Outer diameter 800wφ between 5 and board thickness 120mm x width 1555mm
Is it a spiral welded pipe with an outer diameter of 1000ffφ? Prototypes of each were made and used as test materials. In the above prototype, the formula ■αA
A value predetermined for α of −B=o based on actual measurement data was used, and the distance between the detection position of the variation amount of the steel strip and the inner welding head position was predetermined. These numbers are shown in Table 2.

Table 2 [In the above prototype, the automatic tracking state of the internal finishing liquid head with respect to the internal welding beam center (which can be confirmed by burns on the steel) was visually investigated, and the welding quality of the test materials was also investigated.

According to the results of the above investigation, the maximum operation amount of the inner welding head is about ±10 degrees, and the inner welding head position is 01×
The inner weld seam center was tracked with high accuracy, with a tracking error of α. However, the quality of the inner weld beads of the above sample materials was extremely good, with no welding defects such as poor penetration, blowholes, or slag inclusions observed.

Since it is not yet possible to make a comparison, a spiral welded pipe with the same dimensions as above was prototyped using the conventional method of manually following the internal welding head, and the yield and manufacturing cost were compared with that made using the method of the present invention described above. 0 As a result, the method of the present invention has a yield of 0.05% compared to that of the conventional method.
, a reduction in o, o3qII was shown in cost.

As is clear from the above description, the method of the present invention makes it possible to automatically follow the position of the inner welding head with high accuracy in response to variations in the inner welding point due to variations in the steel strip in spiral pipe manufacturing, and Since the occurrence of defects can be effectively prevented, it is showing great effects in improving the quality of spiral welded steel pipes and reducing manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is a plan view schematically showing the state of variation in the end face of the steel strip, Fig. 2 is an explanatory view showing an example of an apparatus for carrying out the method of the present invention, and Fig. 3 is a mechanism of an internal welding head support device. FIG. 4 is a side view illustrating the mechanism of the inner welding head position detection device. 1: Spiral welded pipe, 2: Welded core wire feeding device, 3: Internal welding head, 4: Welded core, 5: Copper strip, 6: Internal welded point, 7: Side guide roll, 8: Copper strip end face change IJ amount detection device, 9: Internal welding head position detection device, 10; Automatic control device, 11: Swivel holder, 12 Ni-Ride axis,
13: Detection device main body, 14.21.28 Nishlide base, 15: Detection roller, 16.31: Detection base, 17
．． 32: Magnescale, 18: Inner beam, 19
: Support stand, 20: Feed motor, 22: Connection rod, 2
3: Annular ring, 24: Screw tube, 25: Motor, 26
:Push rod, 27:Inner welding head support device, 2
9: pedestal, 30: limit fitting, 33: pedestal, 34I:
Forward limit limit, 34□: Backward limit limit, 35: Controller, 36 two circuits, 37: D/A converter. Yorito Ide Shoki Large Diameter Steel Pipe Co., Ltd.

Claims (1)

[Claims] (1) In the manufacture of spiral welded steel pipes, the positional fluctuation of the steel strip end face in the forming angle direction is detected near the inner welding point, and based on the detected amount (3), the following formula ■αA-B=o...・
......■Here, A: Amount of positional variation in the forming angle direction of the end face of the copper strip B: Amount of movement of the inner welding head in the tube axis direction α: Amount of variation in the position of the inner welding head in the direction of the tube axis according to a coefficient corresponding to the tube diameter and wall thickness A method for automatically controlling the position of an inner welding head of a spiral pipe making machine, characterized in that the movement, t (B), is calculated, and the inward welding head is moved in the axial direction of the tube to perform inner welding based on the movement amount (1). b