JPH10192963A - Manufacture of high energy beam welded tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent defective welds, to provide excellent and stable weld zones, to increase the equipment cost, and to prevent complicate setting and regulating works. SOLUTION: A metallic strip 2 is moved, longer sides 3, 4 are brought close to each other to successively form a cylinder, and the distances at a plurality of positions in the axial direction of the cylindrically formed metallic strip 2 are measured by an edge detecting means 17 provided in the convergence region which is on the upstream side of a rotary shaft of a squeeze side roll 7c, and in which the longer sides 3, 4 of the cylindrical metallic strip 2 are converged toward the V-converging point at which the longer sides 3, 4 are brought into contact with each other for the first time by the compressive force of the squeeze side roll 7c. The high energy beam is irradiated in the vicinity of the V-converging point detected through the function approximation based on the results of the distances at a plurality of positions measured by the edge detecting means 17, and the metallic strip 2 is successively joined with each other to manufacture a welded tube 1 by the compressive force of the squeeze side roll 7c on the downstream side of the position of irradiation of the high energy beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high energy beam welded pipe for manufacturing a welded pipe by welding with a high energy beam such as a laser.

[0002]

2. Description of the Related Art FIG. 6 is a process chart showing an example of a process for manufacturing a general welded pipe. Generally, the welded pipe 1 is formed into a cylindrical shape while sequentially moving a strip-shaped metal strip 2 in the longitudinal direction, and one long side (hereinafter, referred to as “edge”) 3 and the other long side opposing each other. 4 is manufactured by welding.

The manufacturing process of the welded pipe 1 shown in FIG. 6A includes a roll forming stand 5, a welder 6, and a squeeze stand 7.
It is composed of FIGS. 6B to 6D show changes in the metal strip 2 due to this manufacturing process.

The roll forming stand 5 includes, for example, a breakdown roll 8, a cluster roll 9, and a fin pass roll 10, as shown in FIG. FIG.
FIG. 3 is a view of these rolls as viewed from the moving direction of the metal band 2, that is, from the downstream.

[0005] The metal strip 2 passes between the upper roll 8 a and the lower roll 8 b of the breakdown roll 8, is formed to a shape close to the U-shape, passes through the cluster roll 9, and passes over the fin pass roll 10. While passing between the roll 10a and the lower roll 10b, it is sequentially formed into a cylindrical shape. At the same time, the edges 3, 4 are correctly guided by the fin plate 10c provided on the upper roll 10a, and the seam (hereinafter, referred to as a joint) is formed. , "Seams") are provided to the welding process in the form of narrow, substantially circular open tubes 11.

In the welding process, an upstream portion (hereinafter, referred to as a “V convergence point”) of a point where the edges 3 and 4 are joined (hereinafter referred to as “V convergence point”).
Welder 6 provided in “V-shaped part”)
However, welding is performed by high frequency electric resistance welding (electric welding) or the like.

That is, the welder 6 brings the edges 3, 4 of the V-shaped portion of the metal strip 2 into a molten or semi-molten state, butts the edges 3, 4 at the V convergence point, and applies a large compressive force by the squeeze stand 7. Thus, the welded pipe 1 is manufactured.

FIG. 8 is a configuration diagram showing an example of the squeeze stand 7. FIG. 8 is a view of the squeeze stand 7 as viewed from the downstream of the metal strip 2. The squeeze stand 7
Squeeze top roll 7a and squeeze bottom roll 7
b and a squeeze side roll 7c. In the squeeze side roll 7c, the value of the largest diameter is referred to as the flange outer diameter of the squeeze side roll 7c.

The manufactured welding pipe 1 has a pipe axis in the moving direction of the metal strip 2. The manufactured welded pipe 1 is also called an electric resistance welded pipe. Here, the cluster roll 9 is used as one element of the roll forming stand 5, but a cage roll 12 as shown in FIG. 9 can be used instead. The cage roll 12 is provided on the outer circumference of the open pipe 11, and its position can be changed by a cage roll driving device 14 based on information of a cage roll control unit 13. Generally, a cluster roll 9 is used for a small-sized tube, and a cage roll 12 is used for a large-sized tube.

Although the squeeze stand 7 composed of five rolls is used here, a squeeze stand 7 composed of only two squeeze side rolls 7c can be used. In general, a squeeze stand 7 composed of five rolls 7a to 7c is used for a large-sized pipe-making,
Two squeeze side rolls 7c for small size pipe making
Squeeze stand 7 is used.

[0011]

However, in this manufacturing process, there is a problem that the toughness of the welded portion is reduced because the edge portion is oxidized by heat during welding and the rising angle of the metal flow is large.

On the other hand, in the above manufacturing process, the welding pipe 1
As a means for making the welded portion of the squeezed portion more excellent and stable, the compressive force applied by the squeeze stand 7 is reduced, and a high-energy beam such as a laser is irradiated near the V convergence point so that the edges 3 and 4 are formed. Melting and joining welding methods have been proposed.

However, in this welding method, since the allowable range when the laser beam irradiation position deviates from the center of the seam is narrow, unless the laser beam is accurately irradiated near a predetermined V convergence point, the laser beam cannot pass through. There is a disadvantage that welding failure occurs due to poor penetration of the edges 3 and 4 due to the above.

Further, the laser beam diameter is 0.5 to 0.7.
mm, and the position of the V convergence point can be easily moved both in the tube circumferential direction and in the tube axis direction due to poor edge shaping and slight edge waves. It is very difficult to always stably irradiate near the V convergence point.

A conventional technique relating to a method for solving such a problem is disclosed in Japanese Patent Application Laid-Open No. 8-52512. In this method, the edges 3, 4 are heated to a melting temperature or higher by high-frequency heating before laser beam irradiation, and welding is performed using a laser beam whose laser beam diameter is defocused to a large diameter of 1 mm or more. Here, the defocusing of the laser beam is performed in order to expand a stable welding region in which welding can be stably performed.

However, in this method, since the defocused laser beam is merely intended for auxiliary heating for maintaining the melting temperature of the edges 3 and 4, the quality of the welded portion in the conventional welding is reduced. Is not completely eliminated.

Another prior art is disclosed in Japanese Patent Laid-Open No.
No. 5084 discloses this. In this method, the seam torsion is restrained by providing a plate-type seam guide, and the deviation between the seam and the laser beam irradiation position is detected to control the laser beam irradiation position in the tube circumferential direction, thereby performing welding. Do.

However, in this method, in order to suppress the displacement of the seam portion in the circumferential direction of the tube, a plate-type seam guide is provided so as to coincide with the V shape portion in a relatively long range of the seam. Differs depending on the outer diameter, thickness and material of the pipe.If these conditions differ, plate-type seam guides corresponding to each type are required, increasing equipment costs and setting / adjusting. The operation becomes complicated.

Further, since the edges 3, 4 and the plate type seam guide are slid and worn at a high speed during passing, both edges and the plate type seam guide are easily damaged, which leads to deterioration of welding quality.

In addition, in this method, only the position of the laser beam irradiation position in the circumferential direction of the tube is handled. However, when actually manufacturing a welded tube, the V-shape generated by the edge wave or the roll rotation period is used. Due to the occurrence of the opening / closing phenomenon (breathing) of the portion, the V convergence point also moves in the tube axis direction, so that it is necessary to control the irradiation position of the laser beam in the tube axis direction.

Further, another prior art is disclosed in Japanese Patent Application Laid-Open No. 3-56.
No. 150 is disclosed. In this method,
By providing a plurality of squeeze stands 7, the variation of the seam gap is reduced, and the welding position is controlled by controlling the laser beam irradiation position by optically detecting the seam position. Squeeze stands 7 to reduce fluctuations in
Since the line length is significantly changed,
Existing equipment is practically impossible to implement, and introduction of new equipment increases capital investment and increases manufacturing costs.

Further, the seam position is detected and the laser beam irradiation position is controlled. However, a specific relationship showing how the seam position detection result is reflected on the laser beam irradiation position is not clarified.

The present invention has been made in consideration of such circumstances, and can produce a welded pipe having good and stable welding quality without causing welding defects, increasing equipment costs and increasing set-up and cost.
An object of the present invention is to provide a method for manufacturing a high-energy beam welded pipe that does not require complicated adjustment work.

[0024]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 first forms a cylindrical shape while moving it in a direction parallel to the two long sides of the metal strip. The two long sides of the metal strip are melted by irradiating the high energy beam, and the two long sides of the metal strip are sequentially pressed by the compressive force of the squeeze side roll provided on the downstream side of the position irradiated with the high energy beam. In the high-energy beam welded pipe manufacturing method of manufacturing a welded pipe by joining, while moving the metal strip in a direction parallel to both long sides, the two long sides are gradually approached to form a cylindrical shape, and the squeeze side is formed. A convergence region is provided upstream of the rotation axis of the roll, and both long sides of the metal band formed into a cylindrical shape converge toward the V convergence point where the squeeze side roll comes into contact for the first time by the compressive force. The edge detecting means measures the distance between the two long sides at a plurality of positions in the tube axis direction of the metal strip formed into a cylindrical shape, and based on the distance results at the plurality of positions measured by the edge detecting means, V convergence is performed. The position of the point is detected by a calculation using a function approximation, and a high energy beam is irradiated near the V convergence point detected by the calculation, and compression of a squeeze side roll provided downstream of the position irradiated with the high energy beam is performed. This is a high-energy beam welded pipe manufacturing method for manufacturing a welded pipe by sequentially joining both long sides of a metal strip by force.

Therefore, in the method for manufacturing a high energy beam welded pipe according to the first aspect of the present invention, the position of the V convergence point is detected by calculation from the result measured by the edge detecting means, and the V convergence detected by this calculation is detected. Since the high energy beam is radiated to the vicinity of the point, stable high energy beam welding can be performed at an appropriate position, so that a welded pipe having good and stable welding quality can be manufactured without causing poor welding.

Further, since the equipment for manufacturing the welded pipe is not much different from the existing equipment, the welded pipe can be manufactured without increasing the equipment cost and complicating the setting / adjustment work. Next, according to a second aspect of the present invention, in the method of manufacturing a high energy beam welded pipe according to the first aspect, before irradiating the high energy beam, both long side portions of the metal strip are heated by the heating means provided in the convergence region. This is a method for manufacturing a high-energy beam welded pipe to which a step of heating the pipe is added.

Therefore, in the method for manufacturing a high energy beam welded pipe according to the second aspect of the present invention, since the preheating is performed by the heating means, a welded pipe having better and stable welding quality can be manufactured, and the welded pipe can be manufactured at a higher speed. Can be manufactured.

According to a third aspect of the present invention, in the method for manufacturing a high-energy beam welded pipe according to the first or second aspect, the edge detecting means is located in the converging region and the rotating shaft of the squeeze side roll is provided. This is a method for manufacturing a high-energy beam welded pipe in which the distance Lf from the position to the position of the edge detecting means is set to a value determined by equation (1).

Therefore, in the method of manufacturing a high-energy beam welded pipe according to the third aspect of the present invention, the position of the V convergence point can be determined more accurately by setting the edge detecting means at the position determined by the equation (1). .

Next, according to a fourth aspect of the present invention, there is provided a method of manufacturing a high energy beam welded pipe according to any one of the first to third aspects, wherein the pipe axis of the V convergence point detected by calculation is calculated. The position in the direction is obtained from a quadratic or higher order function obtained by function approximation based on the distance between the two long sides measured at a plurality of positions in the tube axis direction of the metal strip formed into a cylindrical shape, and detected by calculation. The position of the V convergence point in the circumferential direction of the tube is approximated by a function based on a plurality of midpoints at a distance between both long sides measured at a plurality of positions in the tube axis direction of the metal strip formed into a cylindrical shape. Is a method for manufacturing a high-energy beam welded pipe obtained by extending the straight line obtained by the above to a position in the pipe axis direction of the V convergence point detected by calculation.

Therefore, in the method for manufacturing a high-energy beam welded pipe according to the present invention, the position of the V convergence point in the pipe axis direction is set at a plurality of positions in the pipe axis direction of the cylindrical metal band. Based on the measured distance between the two long sides, the position of the V convergence point in the circumferential direction of the tube is obtained by calculation from a second or higher order function obtained by function approximation, and the tube of a metal band formed into a cylindrical shape is obtained. Based on a plurality of midpoints in the distance between both long sides measured at a plurality of positions in the axial direction,
A straight line obtained by function approximation was obtained, and the straight line was extended to the position in the tube axis direction of the V convergence point detected by the calculation. Can be irradiated.

Finally, a fifth aspect of the present invention is a method for manufacturing a high energy beam welded pipe according to any one of the first to fourth aspects, wherein a high energy beam irradiation position for irradiating a high energy beam is provided. Is a method for manufacturing a high-energy beam welded pipe that is automatically controlled to be located 0 to 30 mm upstream of the position of the V convergence point detected by calculation.

When the high-energy beam irradiation position is located downstream of the position of the V convergence point, the abutting both long sides are subjected to a compressive force by the squeeze stand. The mill speed must be sufficiently reduced in order for the energy beam to collide and penetrate the thickened plate thickness, resulting in a significant decrease in productivity. Conversely, if it is larger than 30 mm on the upstream side of the V convergence point position, the seam width is too wide, and defects such as undercut and unfusion of both long sides may occur.

Therefore, in the method of manufacturing a high energy beam welded pipe according to the invention, the edge detection means provided at a position suitable for detecting the position of the V convergence point can be calculated by calculation. The position of the V convergence point is detected, and the high energy beam is automatically controlled and irradiated so as to be located 0 to 30 mm upstream of the position of the V convergence point detected by this calculation. Since beam welding can be performed, a welded pipe having good and stable welding quality can be manufactured without causing poor welding.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a process diagram showing an example of a process for manufacturing a welded pipe according to the present embodiment, and FIG.
9 are denoted by the same reference numerals and description thereof is omitted, and only different portions will be described here. Further, the squeeze stand 7 of the present embodiment uses a squeeze side roll 7c.

In the manufacturing process of this embodiment, the edge mirror 15, the roll forming stand 5, the seam guide roll 16, the edge detecting device 17, the high-frequency induction heating device (contact shoe) are arranged in order from the upstream in the moving direction of the metal strip 2.
18, a laser beam welding device 19, and a squeeze side roll 7c are arranged.

The edge mirror 15 is provided upstream of the roll forming stand 5 and is a grinding machine for correcting the shape of the end faces of the edges 3 and 4 of the metal strip 2. FIG. 2 is a sectional view showing the shape of the end face of one edge 3 of the metal strip 2.

FIG. 2A shows a case where the metal strip 2 is provided in a hot-rolled state, and a large rolling sag occurs at the end face of the edge 3. FIG. 2B shows a case where the metal strip 2 is provided in a slit state, and a large slit droop occurs on the end face of the edge 3.

FIG. 2C shows an end face of the edge 3 when the edge 3 is corrected by the edge mirror 15. In this manner, the edge mirror 15 corrects the end surface of the edge 3 by grinding, so that the edge detection device 17 described later can detect the edges 3 and 4 with high accuracy.

The seam guide roll 16 is provided between the fin path roll 10 installed at the most downstream position and the edge detecting device 1.
7 is arranged. This seam guide roll 1
6 is provided to the extent that the outer surface of the open pipe 11 follows the seam, and does not forcibly correct the position of the seam but supplementarily corrects it.

This is because such a seam guide roll 1
This is because even if an attempt is made to forcibly correct the displacement of the seam in the pipe circumferential direction by 6, the end faces of the edges 3 and 4 are simply damaged, and the displacement cannot be completely corrected, and the displacement is forcibly corrected. If the end faces of the edges 3 and 4 are deformed in such a manner, the edge detecting device 17 may erroneously recognize the positions of the edges 3 and 4 depending on the state of the deformation. This is to cause defects.

The edge detecting device 17 is installed in a convergence area where the edges 3 and 4 asymptotically join each other at the V convergence point due to the constraint of the squeeze side roll 7c. This convergence region is a region near the V convergence point in the V shape portion.

The edge detecting device 17 is, for example, a CCD
The seam is observed from the outer surface side of the tube or the inner surface side of the tube with a camera or the like, and the distance between the edges 3 and 4 when cut in the circumferential direction of the tube (hereinafter, referred to as “distance between edges”) is measured.

FIG. 3 is a top view showing the measurement of the distance between edges. In FIG. 3, the distance between the three edges is measured by the distance between the edges 3 and 4 when cut in the pipe circumferential direction.

A specific position where the edge detection device 17 performs seam observation, that is, a specific position where an edge is detected (hereinafter, referred to as an “edge detection position”) will be described.

The edge detection position is determined by the distance Lf from the rotation axis of the squeeze side roll 7c. This distance L
f is the outer diameter OD of the welded pipe 1 and the squeeze side roll 7
c is obtained from equation (1) from the flange outer diameter Df of c and the distance Bt obtained by subtracting the flange outer diameter of the squeeze side roll 7c from the distance between the rotation axes of the two squeeze side rolls 7c and dividing by 2.

From the second embodiment to be described later, actually, when the edge detection device 17 is provided at a position where the distance from the rotation axis of the squeeze side roll 7c is larger than 200 mm on the upstream side, the seam is observed. The error between the position of the V convergence point and the position of the V convergence point obtained from the calculation result becomes large, and a slight welding defect occurs.

Therefore, the distance between the edge detecting device 17 and the rotation axis of the squeeze side roll 7c is set to 200 mm on the upstream side.
By observing the seam for a position that will be within
Good observations can be made.

The number of inter-edge distances measured by the edge detecting device 17 is determined by measuring more
The laser beam irradiation position calculated in a later process can be obtained with higher accuracy. However, the longer the distance between edges is measured, the longer the calculation time for calculating the laser beam irradiation position is. Therefore, the accuracy of the laser beam irradiation position, the calculation time, and the speed at which the metal band 2 is moved (hereinafter, referred to as the moving speed).
It is necessary to measure an appropriate number of edge-to-edge distances in consideration of “mill speed”.

FIG. 4 is a block diagram showing a laser beam irradiation process according to the present embodiment. This edge detection device 1
Reference numeral 7 denotes a light projecting device 17a installed above the seam for irradiating light to the outer surface of the tube, a CCD camera 17b for photographing the seam irradiated by the light projecting device 17a, and C
Arithmetic unit 17c for processing video from CD camera 17b
It is composed of

The image from the CCD camera 17b is taken into the arithmetic unit 17c, the seam is binarized, and the
It is projected on the T screen. Note that this edge detection device 1
Although the measurement of the distance between edges by 7 is performed from the outer surface of the open tube 11, the measurement may be performed from the inner surface of the open tube 11, or from both the inner surface and the outer surface of the open tube 11.

The arithmetic unit 17c calculates the binarized CR
A plurality of distances between edges are measured based on the T screen. Also,
At the same time, the midpoint of the distance between edges is also obtained.

Based on the distance between edges obtained based on the above processing and the midpoint of the distance between edges, the arithmetic unit 17c
Detects the position of the V convergence point in the tube axis direction and the position of the V convergence point in the tube circumferential direction.

Here, in this embodiment, as a method of obtaining the position of the V convergence point in the tube axis direction, a method of approximating with a quadratic or higher-order curve function by the least square method or the like based on the measurement result of the distance between edges. Used. This is because the seam width decreases quadratically as it approaches the rotation axis of the squeeze side roll 7c. Therefore, if the edges 3 and 4 projected on the CRT screen are interpolated by a straight line detected by the least square method or the like, the position of the V convergence point in the tube axis direction becomes the actual position of the V convergence point in the tube axis direction. Much upstream.

It is to be noted that the position of the V convergence point can be detected with sufficient accuracy by using a quadratic function as the approximation function according to the first embodiment described later. On the other hand, in the present embodiment, V
The position of the convergence point in the circumferential direction of the tube is obtained by calculation based on the measurement result of the distance between edges and the measurement result of the midpoint of the distance between edges. The midpoint of the distance between edges is approximated to a straight line by the least squares method, etc., and this straight line is extended to the position in the pipe axis direction of the V convergence point obtained in the previous processing to detect the position of the V convergence point in the pipe circumferential direction. I do.

Then, the arithmetic unit 17c transmits the position of the detected V convergence point in the tube axis direction and the tube circumferential direction to the laser beam irradiation position control unit 20. The laser beam irradiation position control unit 20 automatically controls the irradiation position of the laser beam by the laser beam welding device 19 to a predetermined position based on the received V convergence point position, and performs welding so that the laser beam is always good and stable. The welding pipe 1 of welding quality is manufactured.

From the third embodiment to be described later, the laser beam irradiation position is set to a position within 0 to 30 mm on the upstream side of the V convergence point position, so that no welding defect occurs.
In addition, the welding pipe 1 having good and stable welding quality can be manufactured at high speed. If the laser beam irradiation position is located downstream of the V convergence point position, the abutted edges 3 and 4 receive a compressive force from the squeeze stand 7 composed of the squeeze side rolls 7c, so that the edges 3 and 4 increase. Productivity is severely reduced because the milling speed must be reduced sufficiently to produce meat and for the laser beam to abut this and through the increased thickness. Conversely, if it is larger than 30 mm on the upstream side of the V convergence point position, the width of the seam is too wide, and welding defects such as undercut and edge non-fusion are likely to occur.

As described above, in the method of manufacturing a high-energy beam welded pipe using a laser beam or the like according to the present invention, the edge detecting device 17 provided at a position suitable for detecting the position of the V convergence point is calculated. Since the laser beam irradiation position control unit 20 detects the position of the V convergence point and automatically performs welding so as to irradiate a high energy beam such as a laser beam to the vicinity of the V convergence point detected by calculation, welding is performed. Since high-energy beam welding using a laser beam or the like can be performed at a stable position, a welded pipe 1 having good and stable welding quality can be manufactured without causing welding defects.

Further, by using welding with a welder together, a welded pipe 1 having better and more stable welding quality can be manufactured. Further, since the equipment for manufacturing the welded pipe 1 is not much different from the existing equipment, the welded pipe 1 can be manufactured without increasing the equipment cost and complicating the setting / adjustment work.

Although the cluster roll 9 is used as one element of the roll forming stand 5 here, the cage roll 12 can be used as described above. Although the squeeze stand 7 including only the squeeze side rolls 7c is used here, a squeeze stand 7 including five rolls may be used.

[0061]

【Example】

(Embodiment 1) FIG. 5 is a comparison diagram between the actual V convergence point and the V convergence point obtained by calculation. Here, the vertical axis in FIG. 5 indicates the distance between edges. In addition, the horizontal axis indicates that the distance from the rotation axis of the squeeze side roll 7c becomes more negative as the distance increases toward the upstream side. Further, the data in FIG. 5 shows that the tube outer diameter is 508 mm, the wall thickness is 8.88 mm, and the material is SKK4
00 is measured in the open pipe 11.

Points a1 and a2 are data points detected by the CCD camera 17b from the outer tube side at a position where the distance from the rotation axis of the squeeze side roll 7c is -240 to -230 mm.

The distance between the point b1 and the point b2 from the rotation axis of the squeeze side roll 7c is -150 to -140 mm.
At the position shown in FIG.
The data point detected by b.

The point c is a data point indicating the actual V convergence point. The approximate straight line L1 is an approximate straight line obtained by approximation from the points a1 and a2. In the approximate straight line L1, the distance from the rotation axis of the squeeze side roll 7c is -107 mm.
It is detected that the distance between edges is 0 mm, that is, a V convergence point at a nearby position. Since the actual V convergence point is near the distance of -10 mm from the rotation axis of the squeeze side roll 7c, this detection is not good.

The approximate straight line L2 is an approximate straight line obtained by approximation from the points b1 and b2. In the approximate straight line L2, the distance from the rotation axis of the squeeze side roll 7c is −
At a position near 51 mm, the distance between edges is detected as 0 mm, that is, a V convergence point. Since the actual V convergence point is close to -10 mm from the rotation axis of the squeeze side roll 7c, this detection is not good. The quadratic approximation curve L3 is a quadratic curve obtained by approximation from the points a1, a2, b1, and b2, and is actually represented by the following equation.

[0066]

(Equation 2)

In this secondary approximation curve L3, the point detected as the V convergence point substantially overlaps with the actual V convergence point, so it can be said that the V convergence point is detected with high accuracy. 3
The next approximation curve L4 is a cubic curve obtained by approximation from the points a1, a2, b1, and b2, and is actually represented by the following equation.

[0068]

(Equation 3)

In this cubic approximation curve L3, the point detected as the V convergence point substantially overlaps the actual V convergence point, so it can be said that the V convergence point is detected with high accuracy. Therefore, the V convergence point can be detected with high accuracy by approximating the function to a quadratic function or higher. In addition, since the secondary approximation curve and the tertiary approximation curve almost overlap each other, sufficient accuracy can be detected by approximating the quadratic function. (Example 2) Table 1 shows a welding defect occurrence rate in a conventional method for manufacturing a welded pipe.

[0070]

[Table 1]

In Table 1, the laser beam is 25 k
A w laser is used. In addition, welding is performed by irradiating a laser beam from the upper surface on the tube outer surface side. The welding defect occurrence rate was obtained by using the manufactured welded pipe 1 as a sample, polishing the cross-section of any 50 welding points from the sample, and observing the sample.
The ratio of the presence of a welding defect among the 50 welding points is shown.

As can be seen from Table 1, when there is no laser beam irradiation position control or when welding is performed by the conventional laser beam irradiation position control, the rate of occurrence of welding defects is high, and good and stable quality is obtained. No welding is performed.
On the other hand, Table 2 shows the welding defect occurrence rate of the welded pipe manufacturing method according to the present invention under the same conditions.

[0073]

[Table 2]

In Table 2, the welding defect occurrence rate is suppressed as compared with the conventional method. Therefore, it can be said that high quality welding is performed. In the method for manufacturing a welded pipe according to the present invention, when the edge detection position is set such that the distance from the rotation axis of the squeeze side roll 7c is larger than 200 mm on the upstream side, the detection result of the V convergence point position and the actual Since the error from the position of the V convergence point increases, a welding defect is slightly generated. However, when the distance from the rotation axis of the squeeze side roll 7c is set to be within 200 mm on the upstream side, the welding defect occurrence rate is 0%. % And no welding defects were present.

(Embodiment 3) Table 3 shows that the mill having optimum heat input conditions when the laser beam irradiation position was changed in the tube axis direction with respect to the V convergence point in the conventional method of manufacturing a welded pipe. The speed and the welding defect occurrence rate are shown.

[0076]

[Table 3]

In Table 3, the laser beam is 25 k
A w laser is used. In addition, welding is performed by irradiating a laser beam from the upper surface on the tube outer surface side. As can be seen from Table 3, when welding is performed with the conventional laser beam irradiation position control, the mill speed, which is the optimum heat input condition at the laser beam irradiation position, is low, and the welding defect occurrence rate is high. The case exists.

On the other hand, Table 4 shows that when the laser beam irradiation position is changed in the tube axis direction with respect to the V convergence point in the method for manufacturing a welded tube according to the present invention under the same conditions.
The figure shows the mill speed and the welding defect occurrence rate under the optimum heat input condition.

[0079]

[Table 4]

As can be seen from Table 4, when welding is performed by the laser beam irradiation position control of the present invention, for example, the laser beam irradiation position is set to 0 to 30 mm upstream of the V convergence point.
Within this range, the mill speed at the optimum heat input condition at the laser beam irradiation position is higher than in the conventional case, and the occurrence of welding defects can be suppressed. Therefore, by the method for manufacturing a welded pipe according to the present invention, a welded pipe 1 having good and stable welding quality can be manufactured at high speed.

[0081]

As described above, according to the first aspect of the present invention, the position of the V convergence point is detected by calculation from the result measured by the edge detecting means, and the position of the V convergence point detected near this V convergence point is calculated. Since the energy beam is irradiated, stable high-energy beam welding can be performed at an appropriate position, so that a welded pipe with good and stable welding quality can be manufactured without poor welding.

Further, since the equipment for manufacturing the welded pipe is not significantly different from the existing equipment, the welded pipe can be manufactured without increasing the equipment cost and complicating the setting / adjustment work. In the invention of claim 2, since the preheating is performed by the heating means, a welded pipe having better and stable welding quality can be manufactured,
Welding pipes can be manufactured at higher speed.

According to the third aspect of the present invention, by setting the edge detecting means at the position determined by the equation (1), V
Since the edge detecting means is provided at a position suitable for detecting the position of the convergence point, the position of the V convergence point can be determined more accurately.

In the invention of claim 4, the position of the V convergence point in the tube axis direction is determined based on the distance between the two long sides measured at a plurality of positions in the tube axis direction of the metal strip formed into a cylindrical shape. , The position of the V convergence point in the circumferential direction of the tube measured at a plurality of positions in the tube axial direction of the metal strip formed into a cylindrical shape at two or more positions in the tube axial direction. Based on multiple midpoints in the distance between,
A straight line obtained by function approximation was obtained, and the straight line was extended to the position in the tube axis direction of the V convergence point detected by the calculation. Can be irradiated.

According to the fifth aspect of the present invention, the position of the V convergence point is detected by calculation from the result of measurement by the edge detection means provided at a position suitable for detecting the position of the V convergence point, and is detected by this calculation. Since the high-energy beam is automatically controlled and irradiated so that it is located 0 to 30 mm upstream of the position of the V convergence point, the stable high-energy beam welding can be performed at an appropriate position, resulting in poor welding. In addition, it is possible to manufacture a welded pipe having good and stable welding quality.

[Brief description of the drawings]

FIG. 1 is a process diagram showing an example of a process for manufacturing a welded pipe according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a shape of an end face of one edge of a metal strip.

FIG. 3 is a top view showing measurement of a distance between edges.

FIG. 4 is an exemplary block diagram showing laser beam irradiation processing according to the embodiment;

FIG. 5 is a diagram illustrating a comparison between an actual V convergence point and a calculated V convergence point.

FIG. 6 is a process chart showing an example of a general welding pipe manufacturing process.

FIG. 7 is a configuration diagram showing an example of a roll forming stand.

FIG. 8 is a configuration diagram showing an example of a squeeze stand.

FIG. 9 is a configuration diagram showing an example of a cage roll.

[Description of Signs] 1 ... Welded pipe 2 ... Metal band 3, 4 ... Long side (edge) 5 ... Roll forming stand 6 ... Welder 7 ... Squeeze stand 8 ... Break down roll 9 ... Cluster roll 10 ... Fin pass roll 11 ... Open pipe 12 ... Cage roll 13 ... Cage roll control unit 14 ... Cage roll driving device 15 ... Edge mirror 16 ... Seam guide roll 17 ... Edge detection device 17a ... Light projection device 17b ... CCD camera 17c ... Calculation device 18 ... High frequency induction Heating device 19: Laser beam welding device 20: Laser beam irradiation position control unit

Claims (5)

[Claims] 1. A metal band is sequentially formed into a cylindrical shape while moving in a direction parallel to two long sides of the metal band, and both long sides of the metal band are melted by irradiation with a high energy beam. A high-energy beam welded pipe manufacturing method for manufacturing a welded pipe by sequentially joining both long sides of the metal strip by a compressive force of a squeeze side roll provided downstream of the irradiation position, While moving in a direction parallel to the long sides, the two long sides are gradually approached to form a cylindrical shape sequentially, and the upstream side of the rotation axis of the squeeze side roll,
The edge detecting means provided in a convergence area where both long sides of the metal band formed into a cylindrical shape converge toward a V convergence point where the squeeze side roll comes into contact for the first time due to the compressive force of the squeeze side roll. The distance between the two long sides at a plurality of positions in the tube axis direction of the metal strip molded into a shape is measured, and the position of the V convergence point is approximated by a function based on the distance results at the plurality of positions measured by the edge detecting means. Irradiates a high energy beam near the V convergence point detected by the above calculation, and by the compression force of a squeeze side roll provided downstream of the position where the high energy beam is irradiated, the metal A method for manufacturing a high-energy beam welded pipe, comprising sequentially welding both long sides of a band to manufacture a welded pipe. 2. A method for manufacturing a high energy beam welded pipe according to claim 1, wherein a step of heating both long sides of the metal strip by a heating means provided in the convergence region before irradiating the high energy beam. A method for manufacturing a high-energy beam welded pipe, characterized by being added. 3. The method for manufacturing a high-energy beam welded pipe according to claim 1, wherein said edge detecting means is located in said convergence area and a position of said edge detecting means from a rotation axis of said squeeze side roll. A high energy beam welded pipe manufacturing method characterized in that the distance Lf is set to a value determined by the equation (1). (Equation 1) 4. The method for manufacturing a high-energy beam welded pipe according to claim 1, wherein the position of the V convergence point detected by the calculation in the pipe axis direction is the cylindrical shape. Based on the distance between the two long sides measured at a plurality of positions in the tube axis direction of the formed metal band, the tube of the V convergence point detected by the above calculation is obtained from a quadratic or higher order function obtained by function approximation. The position in the circumferential direction is a straight line obtained by function approximation, based on a plurality of midpoints in the distance between the two long sides measured at a plurality of positions in the tube axis direction of the cylindrical metal band, A method for manufacturing a high-energy beam welded pipe, which is obtained by extending the position of the V convergence point detected by the calculation to a position in the pipe axis direction. 5. The high energy beam welding pipe manufacturing method according to claim 1, wherein the high energy beam irradiation position for irradiating the high energy beam is a V convergence point detected by the calculation. A method for manufacturing a high-energy beam welded pipe, characterized in that the pipe is automatically controlled so as to be located 0 to 30 mm upstream of the position.