JP2851734B2 - Threading equipment in spiral steel pipe manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a spiral steel pipe in which a steel strip is spirally wound to form a pipe, and then its joint is welded.

[0002]

2. Description of the Related Art As a method of manufacturing this spiral steel pipe,
In place of the conventional method of welding the end face of a tube-formed steel strip to the inner surface and then to the outer surface, Japanese Patent Laid-Open No.
There is a composite welding method described in US Pat.
In this method, as shown in FIG. 4, the steel strip coil C is unwound by the uncoiler 1, flattened by the leveler 2, and then guided by the side rollers 3 to guide the steel strip S by the side trimmer 4. After the side end surface of the strip S is beveled by the beveling machine 5, the delivery roll 6
To the molding machine 7. Then, the steel strip S fed into the forming machine 7 is wound and formed by a forming roll 8 to form a pipe P in which a groove portion on a side end face is overlapped.
Immediately after that, the lap portion is welded by the resistance welding machine 9, and then the overlay welding is performed by submerged welding in the order of the outer surface and the inner surface of the seam. .

[0003]

FIGS. 5 to 8 show the state of formation of a welded portion by the above-described composite welding method.
Is a steel strip S immediately after forming into a pipe P by a forming roll.
6 and 7 show a good example and a bad example of the state of the wrap portion R. FIG. FIG. 8 shows a state in which a weld overlay is formed on the groove gap at the joint portion.

As shown in FIG. 5, a forming roll 8 of a forming machine is used.
In the steel strip S fed into the part at a specific approach angle, the groove K on the side end surface of the steel strip S overlaps to form a lap part R, and AC current is applied to the lap part R. At this time, as shown in FIG. 6, the feeding of the steel strip S is performed properly, and the wrap portion R
If the overlap amount L is a predetermined amount, an appropriate welded portion W is formed. However, as shown in FIG. 7, when the overlapping amount L is small, the welding portions W ₁ yields a weld defects become insufficient. In order to obtain this proper wrap portion R, the allowable variation amount of the overlap amount L is ± 1 mm or less.

Further, in FIG. 8 showing a state in which a weld overlay is formed in a groove gap at a joint portion, the pipe-formed base materials P ₁ and P ₂ are shown.
Is formed by welding torch T arranged at a predetermined location in the space of groove K formed between the groove and K, whereby an appropriate welded portion WN is formed. However, when the position of the groove K with respect to the welding torch T is not properly adjusted, a displacement of a built-up portion occurs as shown by a broken line, resulting in a welding defect. The tolerance of this deviation is ± 1.5 mm or less.

In order to form the proper wrap portion R and the groove portion K in this manner, the groove formed at the side edge of the feed strip is appropriately formed, and the strip is fed to the processing machine. It is important not to cause deviation and blurring.

In order to prevent the displacement and the blur, conventionally, as shown in FIG.
As shown in (2), an edge position control was installed as the side roller 3 on the trimmer 4 entry side to suppress displacement and blur.

[0008] However, composite welding in which a groove lap is formed on the side edge of the tube-formed strip, resistance welding is performed on the groove, and then overlay welding is performed on the outer surface and the inner surface of the welded seam. In some cases, the groove wrap does not fall within the allowable range in manufacturing spiral steel pipes by the method.

An object of the present invention is to provide a means for keeping a groove wrap within a predetermined allowable range in the manufacture of a spiral steel pipe by such a composite welding method, and to enhance the reliability of a method of manufacturing a spiral steel pipe by a composite welding. It is in.

[0010]

SUMMARY OF THE INVENTION According to the present invention, after unwinding and flattening a steel strip coil, the steel strip is widened by a side trimmer, and a side edge is beveled by a beveling machine. In a method for manufacturing a spiral steel pipe having a step of forming a spirally formed pipe and forming a lap where side edges of the pipe-formed strip are overlapped with each other, a side guide is pressed immediately after the side trimmer. In addition to the installation, a pressing guide roll is provided immediately after the delivery roll on the rear surface of the side trimmer.

The pressing mechanism of the pressing guide roll is a pressing mechanism such as a hydraulic cylinder that presses only on the same side of the rolls disposed on both sides of the passing steel strip, in particular, only the side on the outside of the steel pipe pipe forming. A mechanism can be provided.

[0012]

The displacement or blurring of the wrap portion at the side edge of the formed strip is caused by the movement of the strip in the width direction called a walk after trimming or the waving called a camber. . These walks and cambers can be effectively prevented by suppressing movement after passing through the side trimmer, especially by pressing the strip against one side.

[0013]

FIG. 1 shows an example in which the present invention is applied to the conventional spiral steel pipe manufacturing equipment shown in FIG. 4, and the same parts are denoted by the same reference numerals.

In FIG. 1, reference numerals 10 to 13 denote one-side pressing guide rolls disposed before the leveler 2 and immediately after the feed roller 6, including before and after the trimmer 4, and only one side of the passing steel strip S is used. It is composed of a pressing roll 15 pressed by a hydraulic cylinder 14 and a fixed roll 16 on the other side. After being tentered by the trimmer 4 and beveled by the beveling device 5, the steel strip S is fed into the forming machine 7.

FIG. 2 shows the run-out of the strip after trimming in the strip passing apparatus shown in FIG. 1, that is, the so-called walk amount, in comparison with the walk amount without the pressing roll mechanism. 4A shows the case of the present invention, and FIG. 4B shows the case of the conventional example shown in FIG.

FIG. 3 shows the amount of run-out of the tail portion of the leveler and the amount of run-out of the trimmer in both devices. In the figure, the solid line shows the case of the present invention, and the broken line shows the case of the conventional example. From the figure, even if the steel strip sways in the width direction at the leveler section, the installation of the pressing roll 15 and the fixed roll 16 reduces the sway in the width direction of the strip on the side of the side trimmer as compared to the case without these. It is possible to straighten the strip at the side trimmer part, which reduces camber and reduces walk.

From these figures, it was found that the provision of the one-side pressing guide roll can suppress the deformation of the steel strip and reduce the amount of run-out on the side of the side trimmer.

Therefore, according to the present invention, the lap portion of the tube-making steel strip is formed accurately, and no displacement of the weld metal is generated.

[0019]

According to the present invention, the following effects can be obtained.

(1) Feeding to the molding machine is performed without generating camber or walk.

(2) The equipment for eliminating the occurrence of camber and walk is also simple.

(3) Since the lap shape of the groove at the side edge of the formed steel strip can always be formed in a stable state, welding defects do not occur.

(4) Since the strip can be widened in a straight line by the trimmer, the coil base plate may have a small camber.

(5) The camber shape of the steel strip can be corrected.

[Brief description of the drawings]

FIG. 1 shows an outline of a spiral steel pipe manufacturing facility to which the present invention is applied.

FIG. 2 shows the effect of reducing the amount of walk by the device of the present invention.

FIG. 3 shows the effect of reducing the amount of runout on the trimmer exit side by the apparatus of the present invention.

FIG. 4 shows an outline of a conventional spiral steel pipe manufacturing facility.

FIG. 5 shows a formation state of a lap portion in the composite welding method.

FIG. 6 shows an appropriate example of a formed wrap portion.

FIG. 7 shows an unfavorable example of a formed wrap.

FIG. 8 shows an aspect of welding overlay after resistance welding of a lap portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Uncoiler 2 Leveler 3 Side roller 4 Side trimmer 5 Edge processing machine 6 Feeding roll 7 Forming machine 8 Forming roll 9 Resistance welding machine 10-13 One side pressing guide roll 14 Hydraulic cylinder 15 Pressing roll 16 Fixed roll

Claims (2)

(57) [Claims] After unwinding and flattening the strip steel coil, the strip steel is widened by a side trimmer, and the side edge is grooved by a beveling machine into a spiral shape. In a spiral steel pipe manufacturing facility for forming and forming pipes to form a lap in which the side edges of the tube-forming steel strip overlap with each other, a pressing side guide roll is installed immediately after the side trimmer, and the rear side of the side trimmer is fed. A strip passing device with a side guide roll that is pressed immediately after the roll. 2. The strip passing apparatus according to claim 1, wherein pressing side guide rolls provided immediately after the side trimmer and immediately after the delivery roll have a pressing mechanism for pressing only the same side of the strip.