JP2842164B2 - Method and apparatus for preventing rolling of welded pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing rolling of an open pipe which is produced when a welded pipe is manufactured by welding an open pipe formed of a metal strip, and an apparatus used for implementing the method.

[0002]

2. Description of the Related Art FIG. 9 is a schematic perspective view showing a process of manufacturing a conventional welded pipe, in which H is a metal band. The wound metal band H is sent from the uncoiler to the leveler 21, flattened by the leveler 21, and sent to the forming roll group.
The forming rolls consist of vertical rolls, enter guide rolls 23, and horizontal rolls, breakdown rolls 24, 24, 2
4, ... cluster rolls 25, 25, 25, ... which are vertical rolls and fin pass rolls 26, 26, 26, ... which are horizontal rolls. They are sequentially arranged in series. Here, the metal strip H is sequentially bent into a cylindrical open pipe OP so that both side edges E and E are opposed to each other. The open pipe OP is heated and melted at both edge portions E and E by a welding machine 28 for performing fusion welding or high-frequency welding and the like, and butted by a squeeze roll 27 to form a welded pipe P. .

In the production of such a welded pipe, a so-called camber occurs in which the metal band H is deformed in a meandering manner, and this causes the open pipe OP in the forming roll group to swing in the circumferential direction to cause rolling. There was a problem that the quality of the welded pipe deteriorated.

FIG. 10 is a schematic plan view of a metal strip in which camber has occurred. As is clear from FIG. 10, the metal strip H has a shape in which the center line C is partially curved due to uneven winding or the like. FIG. 11 is a vertical cross-sectional view of a metal strip formed in an arc shape, and illustrates rolling caused by a camber as shown in FIG. As is clear from FIG. 11, the metal band H formed into an arc shape by the forming roll group.
When the vehicle approaches the portion where the camber is generated, the position of the center line C swings in the circumferential direction by the angle θ in comparison with the portion where the camber is not generated, and rolling occurs.

FIG. 12 is a front view showing a state in which an open pipe is formed by a fin pass roll. Fin pass roll
The upper roll 26 is provided with two rolls, an upper roll 261 and a lower roll 262, which face each other in the vertical direction. A fin plate 263 protrudes from the center of the upper roll 261. Then, the metal strip H formed into an arc shape is formed into an open pipe OP having a substantially circular cross section by the upper roll 261 and the lower roll 262, and both side edges E and E of the open pipe OP are formed by the fin plate 263.
E is formed into a tapered shape.

FIG. 13 is an enlarged sectional view of the vicinity of the edge of the open pipe after passing through the fin pass roll. In the figure, E _L denotes an edge in the direction of rolling by the camber, and E _R denotes the opposite direction. The direction edge part is shown. Fin plate 263 as shown in Fig. 13 (see Fig. 12)
The two side edges E _L and E _{R of the} open pipe OP
The When molded in a tapered shape, since the edge portion E _L is strongly abut against the fin plate 263 by a rolling, machining amount of the edge portion E _L becomes extremely larger than the processing amount in the reverse direction of the edge portion E _R from that , As shown in FIG.
The thickness of _L increases.

FIG. 14 is a diagram showing the both-side edge portions E _L and E shown in FIG.
FIG. 14A is an enlarged sectional view of the vicinity of the welded portion of _R , and FIG. 14A shows a case where fusion welding is performed, and FIG. 14B shows a case where high frequency welding is performed. As shown in FIG. 14A, when fusion welding is performed, an undercut occurs at the position of the welded portion indicated by an arrow in the figure, and as shown in FIG. Protruding wraps are formed on the outside and inside of the welded pipe. Also, since this rolling cannot be completely removed by the fin pass roll,
In a method requiring high welding position accuracy such as laser welding, a welding position is deviated, and a portion where a welding surface is not welded occurs.

[0008] To prevent rolling of the open pipe by the camber, various methods have conventionally been proposed. For example, Japanese Patent Application Laid-Open No. Sho 62-156018 discloses a method of correcting a camber by horizontally moving a fin pass roll in a direction opposite to a predetermined amount according to the amount of camber generated, Also, JP-A-4-1279
No. 78 discloses a method of correcting a camber by horizontally moving an enter guide roll 23 (see FIG. 9) in a direction opposite to the direction in which the camber is generated by a predetermined amount according to the amount of camber generated.

[0009]

However, Japanese Patent Application Laid-Open No. Sho 62
In the methods such as are disclosed in -156018 discloses, although rolling is corrected camber by the movement of the fin pass rolls is suppressed, one edge portion of the open pipe is strongly abut against the fin plate This increases the contact surface pressure. Therefore, as shown in FIG. 13 described above, there is a problem that the thickness of the edge portion increases. Further, in the method disclosed in Japanese Patent Application Laid-Open No. H4-127978, since the camber is corrected by the enter guide roll, there is a problem that the thickness of the edge portion is increased by the enter guide roll itself. Was.

[0010] The present invention was made in view of such circumstances, the respective both side edges of the flat or arcuate metal strip and it is an object of reduction amount of different simultaneously depending on the camber quantity By rolling down at
An object of the present invention is to provide a method for preventing rolling of a welded pipe for preventing the occurrence of rolling without increasing the thickness of a side edge portion , and an apparatus used for implementing the method.

[0011]

According to a first aspect of the present invention, there is provided a method for preventing rolling of a welded pipe, wherein a plurality of continuous forming rolls are used to move both side edges in the width direction while transferring a metal band in the longitudinal direction. When forming a welded pipe by molding into a cylindrical open pipe facing
In a method for preventing rolling in which the open pipe swings in the circumferential direction, the width of the side edges of the metal strip is
Direction displacement and measure based on the measured displacement.
It is characterized in that only the two side edges of the metal strip are lowered by a different roll pair in the thickness direction with different reduction amounts in the thickness direction on the downstream side in the transport direction of the metal strip from the fixed position .

A second aspect of the present invention is directed to an apparatus for preventing rolling of a welded pipe, wherein a plurality of continuous forming rolls are used to move a metal strip in the longitudinal direction, and a cylindrical open shape is formed in which both side edges in the width direction face each other. A device for preventing rolling in which the open pipe swings in the circumferential direction when manufacturing a welded pipe by forming a pipe and welding both side edges thereof, wherein the open pipe has a width in the width direction of both side edges of the metal strip . Measuring means for measuring the amount of displacement, based on the amount of displacement obtained by the measuring means;
Is located downstream of the measuring means in the direction of transport of the metal strip,
Only both side edge portions of the metal strip, different, each roll pair
And a control means for calculating the reduction amount based on the amount of displacement measured by the measurement means and controlling the reduction means. Features.

[0013]

According to the method and the apparatus for preventing rolling of a welded pipe according to the present invention, the width direction of a flat or arc-shaped metal band is provided.
Is measured, and based on this displacement,
Each both sides edges in remote downstream, by reduction at different since reduction rate, and both side edge portions of the metal strip
The distribution of friction between each of the edge portions and the corresponding pair of reduction rolls is uneven. Since such a friction distribution to generate a force for moving the metal strip in the width direction, the occurrence of rolling without which the thickness of the both side edge portions by the action so that the direction of canceling the rolling is increased To prevent.

FIG. 5 is a schematic plan view showing a case where loads are applied to both side edges of the metal strip so as to have different reduction amounts. The metal strip H transferred in the direction of a white arrow in FIG. Shows a case where the load on the right side is larger than that on the left side. The arrows in the figure indicate the action vector of the frictional force on the surface of the metal band H. As is clear from FIG. 5, when the load on the right edge portion of the metal band H is made larger than that on the left side, the frictional force on the right side increases, and a rotational moment 30 is generated counterclockwise by the forming reaction force of the metal band H. Then, due to the rotational moment 30, the metal band H moves to the right side, that is, in the direction in which the reduction amount is increased, with the deviation amount δ1.

FIG. 6 is a schematic plan view showing a case where the rolling widths of both side edges of the metal band are different, and shows a case where the metal band H moves by the shift amount δ1 as described above. For simplicity of description, the unit load applied to both side edges is the same. The broken line in the figure is the center of the metal strip H, and the dashed line is the mill center. As is clear from FIG.
When the center moves to the right in the figure by a deviation amount δ1 from the mill center and the rolling width on the right side of the metal band H increases, a counterclockwise rotation moment 31 similar to the rotation moment 30 described above is generated. Then, due to the rotational moment 31, the metal band moves to the right side, that is, in the direction in which the rolling width is widened, with a shift amount δ2. Accordingly, the metal band H is shifted to the shift amount δ1 by the shift amount δ2.
Is moved by the shift amount (δ1 + δ2).

On the other hand, FIG. 7 is a schematic plan view showing a case where the metal band is reduced so as to have different reduction amounts in the width direction of the metal band in the vicinity of the center of the metal band. The case where the load applied near the center of the metal strip H is continuously increased from the left side to the right side is shown. FIG.
As is apparent from FIG. 5, a counterclockwise rotation moment 40 is generated in the same manner as described above, but since the arm of the rotation moment 40 is short, the moment is smaller than the rotation moment 30 shown in FIG. An attempt is made to move with a shift amount δ3 smaller than the amount δ1.

FIG. 8 is a schematic plan view showing a case where the rolling position near the center of the metal band is different, and shows a case where it is assumed that the metal band H has moved by the shift amount δ3 as described above.
The load applied to the metal strip H is not changed for the sake of simplicity. The broken line in the figure is the center of the metal strip H, and the dashed line is the mill center. As is clear from FIG. 8, when the center of the metal band H moves rightward in the figure by a shift amount δ3 from the mill center and the rolling width on the left side of the metal band H increases,
A rotational moment 41 is generated clockwise. Then, due to the rotational moment 41, the metal band H moves to the left, that is, in the direction opposite to the direction of the assumed shift amount δ3 with the shift amount δ4. Therefore, the metal band H hardly moves from the original position because the shift amount δ3 and the shift amount δ4 cancel each other.

When the metal strip is reduced so as to have different reduction amounts in the width direction of the metal band in the vicinity of the central portion of the metal band, the rotational moment acting on the metal band is canceled out, and the metal band is moved in the width direction. Since it cannot be moved, the camber cannot be corrected. However, when rolling down the side edges of the metal strip so as to have different rolling amounts, the metal band can be moved to the side with the larger rolling amount, so this force acts in a direction to cancel the rolling. the thickness of the both side edges is the occurrence of rolling is prevented without increasing the.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic perspective view showing a process for manufacturing a welded pipe according to the present invention, in which H is a metal band. The wound metal band H is sent from the uncoiler to the leveler 21, flattened by the leveler 21, and sent to the forming roll group. The forming rolls include vertical guide rolls 23,23, horizontal rolls breakdown rolls 24,24, ..., vertical roll cluster rolls 25,2.
5,25,… and the horizontal roll, the fin pass roll 26,2
6,26, ..., each roll is paired with metal band H
Are sequentially arranged in series in the carrying direction. Here, the metal strip H is sequentially bent into a cylindrical open pipe OP so that both side edges E and E are opposed to each other. Thereafter, the open pipe OP is heated and melted on both side edges E, E by a welding machine 28 for performing fusion welding or high-frequency welding, and is abutted and welded by a squeeze roll 27 to form a welded pipe P.

A straightening roll 1 for preventing rolling by the camber is arranged on the entrance side of the above-mentioned breakdown rolls 24, 24,..., And a camber amount is provided between the straightening roll 1 and the enter guide roll 23. In order to measure the displacement, the displacement meters 3 and 3 for measuring the displacement amount of the metal band H in the width direction are arranged with reference to the case where the center of the metal band H is the position of the mill center. The straightening roll 1 is attached to a pressing device 5 having a load meter, and a control device 4 for controlling the pressing device 5 is connected to the pressing device 5. Control device 4
Is connected to a displacement meter 3 for obtaining the amount of reduction of the reduction device 5 based on the measured amount of displacement. The displacement meter 3 has:
The contact type is preferable to the non-contact type because measurement errors due to disturbance are small and high-precision measurement is not required.

FIG. 2 is a partial sectional view taken along the line 2-2 in FIG. 1. In FIG. 2, reference numerals 11L and 11R denote upper rolls of the straightening roll 1 (see FIG. 1), and reference numerals 12L and 12R denote lower rolls. The upper roll 11L, the lower roll 12L, and the upper roll 11R and the lower roll 12R are paired so as to sandwich both side edges E and E of the metal band H,
The opposing surfaces of the upper rolls 11L, 11R and the lower rolls 12L, 12R are formed so as to have a required curvature so that both side edges E, E of the sandwiched metal band H are slightly upward. I have. Upper roll 11L, 11R and lower roll 12L, 12R
Can move in the width direction of the metal band H in accordance with the width of the metal band H, and the upper rolls 11L and 11R and / or the lower rolls 12L and 12R can be independently lowered. I have.

In such a device, when the displacement amount measured by the displacement meter 3 is given to the control device 4, the control device 4
Calculates a deviation from a reference value, and when the calculated deviation is equal to or more than a predetermined value, determines that camber has occurred and corrects the camber so as to correct the camber. Using the formula (1), the rolling force ΔP required to correct the camber is calculated by the following equation (1), and the calculated rolling force ΔP is given to the rolling device 5. ΔP = α · σ _y · t ² (1) where σ _y : yield stress of metal band (kgf / mm ² ) t: thickness of metal band (mm)

The upper roll 11L, the lower roll 12L, and the upper roll 11R and the lower roll 12R are used to form both side edges E of the metal band H,
While holding and bending E, the reduction amount on the opposite side is increased so that the reduction force on the side opposite to the side where the camber occurs is increased by ΔP, or the reduction amount on the side where the camber occurs is reduced. Alternatively, the camber is corrected by rolling down by combining the two to prevent rolling.

In FIG. 1, since the straightening roll 1 acts in the same manner as the breakdown roll, the opposing surfaces of the upper rolls 11L, 11R and the lower rolls 12L, 12R have the required curvature and curvature as shown in FIG. It is molded so that
It may be arranged upstream of the breakdown roll 24 and act only for correction, in which case the opposing surfaces of the upper roll and the lower roll are flat.

Next, the results of a comparative test will be described. FIG. 3 is a schematic view showing the dimensional specification of the straightening roll according to the present invention, and FIG. 4 is a schematic view showing the dimensional specification of a pair of upper and lower rolls used in the comparative test. In FIG. 3, R1 is the distance from the point O where the extended line connecting the lower end of the curved surface of the lower roll 12 and the center of R2, which will be described later, and the mill center perpendicular line intersect, and θ1 is the distance between the mill center and the lower roll 12. The angle formed by an arc of radius R1 with the lower end of the curved surface is R2
Is the radius of the lower roll 12 relative to the curved surface, and R3 is the upper roll 11
Indicates the radius of the arc of the radii R2 and R3 with respect to the curved surfaces of the upper roll 11 and the lower roll 12, respectively. In FIG. 4, R4 is a lower roll.
14 is the radius of the curved surface of the upper roll 13, R5 is the radius of the curved surface of the upper roll 13, θ3 is the angle formed by the arc of radius R5 between the mill center and the end of the curved surface of the upper roll 13, and θ4
Indicates an angle formed by an arc having a radius R4 between the mill center and the end of the curved surface of the lower roll 14, respectively. The respective values are listed in Tables 1 and 2 below.

[0026]

[Table 1]

[0027]

[Table 2]

The metal strip was cut every 10 m, shifted by 1 mm in the width direction, joined again by MIG welding, and then flattened at the welded portion. The dimensions and material strength of the metal strip are shown in Table 3 below, and the pipe making conditions are shown in Table 4.

[0029]

[Table 3]

[0030]

[Table 4]

In the example of the present invention, the welded pipe was manufactured 100 m at a time while controlling the amount of reduction appropriately in accordance with the displacement in the width direction of the metal strip, and in the comparative example, uniformly reducing the width in the width direction. Then, for both welded pipes, 10
Table 5 shows the results of eddy current inspection based on JIS G0583, which was made by cutting 0 mm into a sample material. The artificial defect to be used as a control was a drill hole of φ1.0 mm (ED-1).
0).

[0032]

[Table 5]

As apparent from Table 5, it is considered that the present invention has no defect and the occurrence of rolling is prevented, but in the comparative example, six defects are detected and rolling is considered to have occurred.

Table 6 shows the results of measuring the maximum thickness difference by cutting the MIG-welded portion.

[0035]

[Table 6]

As is clear from Table 6, there is almost no difference in thickness in the example of the present invention, and the increase in thickness at the edge of the metal band is prevented. More than doubled, and the increase in meat thickness has occurred.

[0037]

As described above in detail, in the method and the apparatus for preventing rolling of a welded pipe according to the present invention, it
After measuring the amount of displacement in the width direction of both side edges, this displacement
Only the edges on both sides of the metal strip based on the
The roll force is reduced by the roll pair of
Range, and the metal strip
After measuring the amount of displacement in the width direction of the
Accurate reduction for displacement measurement site because reduction is applied
It is possible to make adjustments and control of the rolling reduction is easy.
The edges of the metal strip are accurately joined
The present invention has excellent effects, such as being able to reduce welding defects.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a step of manufacturing a welded pipe according to the present invention.

FIG. 2 is a partial cross-sectional view taken along line 2-2 of FIG.

FIG. 3 is a schematic view showing a dimension regulation of a straightening roll according to the present invention.

FIG. 4 is a schematic view showing a dimensional rule of a roll used in a comparative test instead of the straightening roll according to the present invention.

FIG. 5 is a schematic plan view showing a case where loads are applied to both side edges of the metal strip so as to have different reduction amounts.

FIG. 6 is a schematic plan view in the case where the rolling widths of both side edges of the metal band are different.

FIG. 7 is a schematic plan view showing a case where the metal band is reduced so as to have different reduction amounts in the width direction of the metal band in the vicinity of the center of the metal band.

FIG. 8 is a schematic plan view showing a case where a rolling position near a central portion of a metal strip is different.

FIG. 9 is a schematic perspective view showing a process for manufacturing a conventional welded pipe.

FIG. 10 is a plan view of a metal strip in which camber has occurred.

FIG. 11 is a longitudinal sectional view of a metal band in a process of being formed into an open pipe from the metal band.

FIG. 12 is a front view showing a state in which an open pipe is formed by a fin pass roll.

FIG. 13 is an enlarged sectional view of the vicinity of an edge of the open pipe after passing through a fin pass roll.

FIG. 14 is a side edge portion E _L , E _R shown in FIG. 13 _;
3 is an enlarged cross-sectional view of the vicinity of the welded part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Straightening roll 3 Displacement meter 4 Control device 5 Press-down device 21 Leveler 23 Entering guide roll 24 Breakdown roll 25 Cluster roll 26 Fin pass roll 27 Squeeze roll 28 Welding machine H Metal strip OP Open pipe P Welded pipe E Edge

Claims (2)

(57) [Claims] 1. While transferring a metal strip in the longitudinal direction, a plurality of continuous forming rolls are used to form a cylindrical open pipe having both side edges in the width direction opposed to each other, and both side edges are welded. when manufacturing a welded pipe Te, a method for preventing rolling of the open pipe to swing in the circumferential direction, by measuring the displacement amount in the width direction of both side edge portions of the metal strip, this
Movement of metal band from measured position based on measured displacement
Only both side edge portions of the metal strip in the downstream direction, respectively
A method for preventing rolling of a welded pipe, characterized in that a different roll pair is used to reduce the thickness of the welded pipe in a thickness direction by a different amount. 2. While transferring the metal strip in the longitudinal direction, a continuous plurality of forming rolls are used to form a cylindrical open pipe with both side edges in the width direction facing each other, and the both side edges are welded. A device for preventing rolling in which the open pipe swings in the circumferential direction when manufacturing a welded pipe, comprising: a measuring means for measuring a widthwise displacement of both side edges of the metal strip; and Measurement based on the amount of displacement obtained by
Located downstream of the transfer direction of the metal strip than the stage, a pressure means for pressure only both side edge portions of the metal strip at reduction rate of different in the thickness direction at different, the roll pairs, respectively, Control means for calculating the reduction amount based on the displacement amount measured by the measurement means and controlling the reduction means, wherein a rolling prevention device for a welded pipe is provided.