JP2008238211A - Method and apparatus of manufacturing spiral pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for manufacturing a spiral steel pipe having a sound weld zone by securing a proper welding gap when the spiral steel pipe is manufactured by using a steel strip, whose width is not necessarily uniform, as a base material. <P>SOLUTION: In the method of manufacturing the spiral steel pipe, a steel strip is trimmed on the side, formed into a spiral shape and abutted on the edges, with the inner face and then the outer face welded. The variance of the width of the steel strip is continuously measured on the upstream side at least by 2D portion (D is the outer diameter of the spiral pipe to be manufactured) from an inner face welding point. At the same time, guidance is provided so that a prescribed welding gap is obtained at the inner welding point in accordance with the variance of the steel strip width. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a spiral pipe, and more particularly to a method for manufacturing a spiral pipe when the plate width of a material hot-rolled steel strip varies.

  A spiral pipe is manufactured by forming a steel strip having a predetermined width in a spiral shape at a constant angle and welding a seam. In manufacturing this spiral steel pipe, the width and end face shape of the steel strip, which is the raw material, are kept constant, and the steel strip size (diameter) and welding are kept constant as much as possible during spiral forming. It is important in maintaining the quality of the department. In order to achieve such an object, for example, in Patent Document 1, when a displacement amount in the width direction of the coil due to the meandering of the coil or a change in the band width is detected by the position detection sensor, according to the displacement amount. A means is disclosed in which the bending roll is driven to swing and the roll angle is adjusted to return the coil to the normal position. Patent Document 2 discloses means for detecting the edge position of the steel strip one pitch upstream from the outer surface welding point and controlling the torch position according to this detection. Furthermore, in Patent Document 3, the lap amount and the penetration angle are measured immediately before the forming part of the spiral steel pipe, and the pretreatment cart is rotated or the left and right rolls of the feed roll are kept so as to keep these values at predetermined values. Means are disclosed for controlling the difference or steering of the forming roll.

Japanese Patent Laid-Open No. 9-192730 Japanese Patent Laid-Open No. 11-58002 JP-A-5-161915

  The means described in Patent Documents 1 to 3 are based on the premise that the width of the steel strip, which is a material for manufacturing the spiral steel pipe, is adjusted to a predetermined width. However, the material steel strip for the spiral steel pipe is not necessarily provided with a desired size, and may be inevitably used with an insufficient size and shape. For example, there are times when it is necessary to use a steel strip that does not partially have a predetermined width. In such a case, if the side slit is made on the basis of the smallest width part, and the end face processing is performed to produce the pipe, the production yield from the steel strip to the steel pipe is reduced, so the side trimming width is set to the end face of the steel strip. In some cases, the pipe is manufactured in a state where the width of the steel strip is limited to a certain value, for example, about 20 mm at the maximum. In such a case, when spiral forming is performed with the steel strip width being constant, there is a difference between the end surface of the preceding steel strip and the end surface of the following steel strip at the weld, and an appropriate welding gap is created. Since this cannot be ensured, poor welding may occur at the spiral weld.

  The present invention provides a means for producing a spiral steel pipe having a sound welded portion by securing an appropriate welding gap when a spiral steel pipe is produced using a steel band whose width is not necessarily constant as described above. For the purpose.

  The spiral steel pipe manufacturing method of the present invention is a spiral steel pipe manufacturing method in which a steel strip is side-trimmed and then formed into a spiral shape, the edges are butted and the inner surface and then the outer surface are welded. Is the outer diameter of the manufactured spiral steel pipe) Continuously measures the fluctuation of the steel strip width on the upstream side, and guides so that a predetermined welding gap is obtained at the inner surface welding point according to the fluctuation of the steel strip width. Is.

  Specifically, the steel strip is guided so that the weld gap on the inner side of the steel strip at the inner surface welding point includes a predetermined value at the inner surface welding point including the concave portion occurrence position. After the time when the outer side of the steel strip corresponding to the recess generation position reaches the inner surface welded part after the position where the concave part on the inner side of the steel band reaches the inner surface welded part, the outer side of the steel band The steel strip is guided so that the welding gap becomes a predetermined value.

In the above invention, the guide on the inner side weld line side of the steel strip is desirably performed by adjusting the angle between the axis of the spiral steel pipe and the axis of the material steel strip.

  The present invention is effectively applied when the side trimming of the steel strip is performed while maintaining a constant value from the end portion of the raw steel strip.

  In the spiral steel pipe manufacturing method of the present invention, the steel strip is side-trimmed and then formed into a spiral shape, and the edge portion is butted to weld the inner surface and then the outer surface, and at least 2D minutes from the inner surface welding point. (D is the outer diameter of the manufactured spiral steel pipe) The steel strip width measuring device that measures the fluctuation of the steel strip width on the upstream side, and the steel strip width measurement result by the steel strip width continuous measuring device is compared with the reference steel strip width. Calculates the time when the steel strip width measurement position reaches the inner surface welding position based on the distance from the steel strip width measurement position to the inner surface welding position and the welding speed by the steel strip width continuous measuring device of the steel strip width measuring unit The welding gap at the time of inner surface welding becomes a predetermined value based on the calculation result of the steel strip width comparison calculation unit and the calculation result of the inner surface welding time calculation unit. Can be achieved by allowed to comprise a pipe-angle calculation and control unit for correcting control spiral pipe forming angle.

  According to the present invention, even when the width of the raw steel strip fluctuates due to unforeseen circumstances at the time of manufacturing the spiral steel pipe, the welding gap at the time of inner surface welding can always be maintained appropriately, thereby having a sound butt weld. It becomes possible to manufacture spiral steel pipes.

  FIG. 1 is a conceptual diagram of a spiral pipe making facility to which the present invention is applied. As shown here, the steel coil 1 is discharged as a steel strip 2 by an uncoiler 3. The steel strip 2 is straightened by the leveler 4 and adjusted to a predetermined width by the side slitter 5 as necessary, and a groove having a predetermined shape is formed by the groove processing machine 6 at the end of the steel strip. The groove processing by the groove processing machine 6 may be performed directly without cutting off the steel band ears by the side slitter 5.

  The grooved steel strip 2 is fed to the molding machine 11 side by the feed roll 7 in accordance with the welding speed v, formed into a spiral shape by the molding machine 11, and internally welded by the inner surface welding machine 12. Then, the outer surface is welded by the outer surface welding machine 14 to complete the spiral steel pipe 15. The adjustment between the diameter D of the spiral steel pipe and the width W of the steel strip is performed by rotating the spiral steel pipe 20 around the rotation axis O. The central axis O is the intersection of the axis of the steel strip and the axis of the steel pipe, and the angle formed is the pipe forming angle α.

  In the present invention, the width measuring device 10 of the steel strip 2 is installed on the rear side of the feed roll 7, and the width W of the steel strip 2 is measured. In the case of this invention, this assumes the case where the steel strip provided for pipe making must use the thing which does not have predetermined width partially. In such a case, when spiral forming is performed with the steel strip width being constant, a difference occurs between the end surface of the preceding steel strip and the end surface of the subsequent steel strip at the weld, and an appropriate welding gap cannot be secured. Therefore, poor welding may occur in the spiral weld. The reason why the steel strip width W is actually measured is to ensure an appropriate welding gap even when the steel strip as described above does not partially have a predetermined width.

  FIG. 2 is a schematic explanatory view showing a formation state on the inner surface weld line side according to the present invention. In this figure, a recess 8 is formed between L and M of the steel strip 2, and the steel strip width is narrowed by a maximum ΔW with respect to a predetermined value W. In such a case, when the steel strip is fed in accordance with a normal pipe making process, the welding gap ΔG of the inner surface welded portion is gradually increased from the time when the portion L of the steel strip 2 reaches the inner surface welding point, and gradually satisfying butt welding. Part is not obtained.

  In order to deal with this problem, the present invention continuously measures the width of the steel strip 2 at least 2D upstream from the position of the inner surface welding point B (D is the outer diameter of the spiral steel pipe to be manufactured). As a result, even when the pipe forming angle α takes the maximum value of the equipment specification, the steel strip width measurement part does not show the influence of bending work on the steel strip, so that the fluctuation of the steel strip width can be measured accurately. Become. Then, the inner surface weld line side of the steel strip 2 is guided in accordance with the fluctuation of the steel strip width so that a predetermined welding gap is obtained at the inner surface welding point.

  In order to ensure the above-mentioned guide, as shown in FIG. 1, a steel strip for measuring the fluctuation of the strip width at least 2D upstream from the inner surface welding point (D is the outer diameter of the manufactured spiral steel pipe). The width measuring device 10 is placed, and the measurement result is input to the steel strip width comparison operation unit 23 that performs a comparison operation with the reference steel strip width W and is compared with the reference steel strip width W. At the same time, the steel strip feeding speed (which substantially coincides with the welding speed v) is obtained from the feeding roll, and this is input to the inner surface welding time calculation unit 24, where the steel strip part Q (recess 8) The time until the inner surface welding point B of the steel strip 2 in the width direction corresponding to the portion P where the maximum dent is generated is calculated.

The time T ₁ until the steel strip portion P reaches the inner surface welding point B is l ₁ / v where the welding speed is v and the distance between the PBs is l ₁ . On the other hand, the time T ₂ of the up region Q of the strip 2 to reach the inner surface weld point B, the distance from the inner surface weld point B site to the R (steel strip width direction portions corresponding to the inner surface weld point B) l ₂ The above becomes l ₁ / v + l ₂ / v. Since the distance from the inner surface welding point B to the part R substantially corresponds to one spiral length of the spiral steel pipe, the steel strip width W and the pipe forming angle α
sin α = W / πD, where D is the diameter of the spiral steel pipe.
Is calculated.

  The fluctuation information of the steel strip width W calculated in this way and the arrival time information of the fluctuation portion (concave portion 8) of the steel strip width to the inner surface welded portion B are input to the pipe forming angle control section 25. Based on the above information, the pipe forming angle control unit 25 controls the driving device 21 so that the welding gap ΔG at the inner surface welding point B becomes an appropriate value at the time when the steel strip portions P and Q reach the inner surface welding point B. To do.

  The pipe making method when the spiral steel pipe control system is configured as described above is as follows. First, the side of the steel strip 2 on the left side of the drawing (this side is referred to as an “inner side”) is always fed to the inner surface welding point B with a predetermined gap ΔG. It is also possible to provide the steel strip width measuring device 10 with the inner side end face detection device 17 and control the pipe making angle adjustment table 20 based on the detection result. As shown in FIG. 2, when the recess 8 is formed in the steel strip 2, the tube forming angle α is decreased from the steel strip portion L to P according to the shape of the recess 8, and then reaches the portion M. It is restored and then piped at the specified pipe making angle.

On the other hand, on the right side of the steel strip 2 in the drawing (this side is referred to as the “outside side”), in this example, there is no recess as seen on the inside side. However, the influence of the narrowing of the steel strip width W due to the concave portion 8 is that the inner side welding point B is welded on the inner side, the distance between B and R is l ₂ , and the outer side is converted into time after l ₂ / v. Appear as if the steel strip width is narrowed by a maximum ΔW. In the present invention, in order to compensate for this effect, the steel strip portion S on the outer side side (the portion corresponding to the width direction of the steel strip in the portion L where the concave portion 8 starts to appear) from the portion T (the steel strip in which the concave portion 8 has disappeared). The pipe forming angle α is adjusted so that the welding gap ΔG at the inner welding point B falls within an appropriate range between the upper part M and the width direction corresponding part of the steel strip. In the present invention, in order to perform the adjustment with the time difference, the time from the steel strip width measurement position to the inner surface welding position is determined by the distance l from the steel strip width measurement position to the inner surface welding position B and the welding speed v. An angle adjustment that is calculated by the welding time calculation unit 24 and compensates for the fluctuation of the steel strip width given by the steel strip width comparison calculation unit 23 after the calculated delay time is output from the pipe forming angle control unit, and the driving device 21 The tube forming angle adjustment table 20 is rotated.

  FIG. 3 illustrates the shape of the steel strip 2 to which the present invention is applied. In the case of FIG. 3 (a), there is a recess 8 on the outer side, and in the case of FIG. The case where the recessed part 8 exists in both the circumference side and the outside circumference side is shown. The specific operation method of the present invention in these cases can be basically designed according to the case where the concave portion 8 is provided on the inner side.

  The steel strip width comparison calculation unit 23, the inner surface welding time calculation unit 24, and the pipe making angle control unit 25 are integrated into one process computer of one calculation / control device, forming the calculation / control device 22 as a whole. ing.

It is a conceptual diagram of the spiral pipe making equipment to which the present invention is applied. It is typical explanatory drawing which shows the guidance state by the side of the inner surface weld line by this invention. It is typical explanatory drawing which shows the side end shape of the steel strip to which this invention is applied.

Explanation of symbols

1: Steel coil
2: Steel strip
3: Uncoiler
4: Leveler
5: Side slitter
6: Groove processing machine
7: Sending roll
8: Recess
10: Width measuring device
11: Molding machine
12: Internal welding equipment
14: Outer surface welding equipment
15: Spiral steel pipe
16: Travel cutting machine
17: Inner side edge detection device
20: Pipe making angle adjustment table
21: Drive unit
22: Arithmetic / control equipment
23: Steel strip width comparison calculation section
24: Internal welding time calculator
25: Pipe making angle controller

Claims (5)

In the method of manufacturing a spiral steel pipe, the steel strip is side-trimmed and then formed into a spiral shape, the edges are butted against the inner surface, and then the outer surface.
Continuously measure the fluctuation of the steel strip width at least 2D from the inner welding point (D is the outer diameter of the manufactured spiral steel pipe), and the inner welding point of the steel strip according to the fluctuation of the steel strip width A method of manufacturing a spiral steel pipe, wherein the steel strip is guided so as to obtain a predetermined welding gap.   Detecting the recess occurrence position of the steel strip, guiding the steel strip so that the weld gap on the inner side of the steel strip at the inner surface welding point including the recess occurrence position becomes a predetermined value, The weld gap on the outer side of the steel strip is predetermined after a lapse of time until the outer side of the steel strip corresponding to the concave portion occurrence position reaches the inner weld after the side recess generation position has reached the inner surface weld. The method of manufacturing a spiral steel pipe according to claim 1, wherein the steel strip is guided so as to have a value.   2. The method for producing a spiral steel pipe according to claim 1, wherein the guide on the inner surface weld line side of the steel strip is performed by adjusting an angle between the axis of the spiral steel pipe and the axis of the raw steel strip.   The method for manufacturing a spiral steel pipe according to claim 1 or 2, wherein the side trimming of the steel strip is performed while maintaining a constant value from the end of the raw steel strip. In a spiral steel pipe manufacturing device that forms a spiral after side trimming the steel strip, butts the edges and welds the inner surface and then the outer surface,
The steel strip width measurement device for measuring the fluctuation of the steel strip width on the upstream side of at least 2D (D is the outer diameter of the spiral steel pipe to be manufactured) from the inner surface welding point, the steel strip width measurement result by the continuous steel strip width measuring device. The steel strip width measurement position is compared with the standard steel strip width and the steel strip width measurement position is measured by the distance from the steel strip width measurement position to the inner welding position and the welding speed of the spiral steel pipe by the continuous steel strip width measuring device. It has an inner surface welding time calculation unit that calculates the time to reach the position, and the welding gap during inner surface welding becomes a predetermined value based on the calculation result of the steel strip width comparison calculation unit and the calculation result of the inner surface welding time calculation unit An apparatus for manufacturing a spiral steel pipe, comprising a pipe forming angle calculation / control device for correcting and controlling a spiral pipe forming angle.

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