JP2803571B2 - Laser welded 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 an improvement in a laser welding pipe manufacturing apparatus.

[0002]

2. Description of the Related Art Compared with other welding methods, laser welding has a high energy density of a heat source, so that it can be deeply penetrated and can be welded at high speed, and since the total heat input can be reduced, the performance of the welded portion is good. For this reason, it is attracting attention as a welding method for steel pipes, and its application is being promoted. Further, a technique for further increasing the speed by adding high-frequency preheating to the laser welding method has been proposed (Japanese Patent Application Laid-Open No. 56-168981, etc.). According to FIG. 3 of the publication, the fin pass rolls FR, FR, the work coil W, the TIG welding head (or laser torch) T, and the squeeze rolls SR, SR are arranged along the flow of the work. The unwelded pipe P is formed by FR and preheated by high frequency heating by the work coil W.
The squeeze rolls SR, SR butt the parts to be welded, TIG
The welding head (or a laser torch) T is used to weld a portion to be welded.

In the above example, the laser torch T is disposed at a position far away from the squeeze rolls SR, SR. However, the farther from the squeeze rolls SR, SR, the worse the butted state of the welded portions may be. Particularly, in laser welding with a high energy density, it is necessary to perform welding in a good butt state because a laser beam forms a through hole called a keyhole in a base material. Therefore, it is desired to arrange the laser torch between a pair of squeeze rolls.

FIG. 8 is a cross-sectional view of a conventional laser welded pipe manufacturing apparatus, in which a tubular band W formed in a tubular shape moves horizontally in the direction of the arrow, and a pair of squeeze rolls 102, 102 and welded by a laser torch 103. The laser torch 103 houses a bending mirror 105 and a condensing mirror 106 in a housing 104, and introduces a laser beam 107 emitted from a laser oscillator (not shown in FIG. 1) through an optical path tube 108. The light is inverted at 105, re-inverted by the condensing mirror 106, narrowed down, and irradiated to the welded portion.

The laser light is a carbon dioxide laser beam having a wavelength of 10.6 μm, and has a focal length f of the mirror and a spot diameter d.
And the following relationship holds.

[0006]

(Equation 1)

In order to maintain the optimum spot diameter d, π
It is important to keep (f / ω) constant because λ and λ are constant.

FIG. 9 is a front sectional view of FIG. 8, and a thick metal band W to be subjected to laser welding sometimes has a poor butted shape of a welded portion W1 due to insufficient bending. A method of increasing the diameter of the upper flange 102a of the squeeze rolls 102, 102 and extending the edge of the upper flange 102a to the vicinity of the welded portion W1 is also considered. However, when the metal band W is a large-diameter pipe, the width of the squeeze roll 102 is reduced. Direction peripheral speed difference (upper flange 102a / small diameter portion 102c / lower flange 1
02b), the metal band W tends to be flawed. Therefore, there is a method of providing a top roll for the purpose of reducing the load on the squeeze roll 102.

FIG. 10 is a principle view of a conventional apparatus for manufacturing a laser welded pipe with a top roll. The squeeze rolls 111, 111 having a small overhang (that is, the upper and lower flanges have a small diameter) are shown.
111, bottom roll 112, top roll 11
3 and 113 and the laser torch 103. Since the welded portion W1 can be suppressed from above by the top rolls 113, 113, the above problem can be solved.

[0010]

However, in order to avoid interference with the laser beam 107 in FIG. 10, it is necessary to arrange the top rolls 113, 113 in a V-shape.
Moreover, the top roll 11 is used to avoid the heat of laser welding.
3 and 113 must be moved to the squeeze rolls 111 and 111 to some extent from the welded portion W1, and the arrangement of the top rolls 113 and 113 is not easy. Alternatively, the laser torch 103 must be raised as shown in the figure in order to avoid interference with the top rolls 113, 113. If the laser torch 103 is raised, the focal length f of the mirror cannot be maintained, and as a result, the spot diameter d becomes larger than an appropriate value. Therefore, there is a problem that the energy density cannot be concentrated.

[0011]

Therefore, the present inventors have found that in a laser welded pipe manufacturing apparatus in which a laser torch is placed between left and right squeeze rolls, the top roll can be separated from the laser torch to some extent. After various experiments, we succeeded in installing the toe roll on the upstream side of the laser torch.

Specifically, a pair of left and right squeeze rolls, which are formed into a tubular shape and sandwich a metal band having a welded portion facing upward from right and left and abut the welded portion, and a downward facing squeeze roll between the squeeze rolls. And a laser torch for welding the welded portion and a top roll attached to a position that satisfies the following conditions to suppress the welded portion from above. Top roll position: A position upstream of the laser torch and at a position where the top roll does not interfere with the laser torch or laser beam. The distance from the center of the squeeze roll to the roll axis of the top roll is not more than the radius of the upper flange of the squeeze roll.

[0013]

[Function] A welded portion of a metal band formed into a tubular shape is held down by a top roll, the metal band is transferred to a squeeze roll in this state, and the upper flange of the squeeze roll holds the upper portion of the metal band while welding with a laser torch. Make

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a schematic view of a pipe rolling mill provided with a laser welded pipe manufacturing apparatus according to the present invention. The pipe rolling mill 1 is a facility for gradually bending a flat metal band W into a tubular shape, In order to use a lubricant. A laser welding pipe manufacturing apparatus 10 is arranged on the exit side of the pipe rolling mill 1.
11, a laser oscillator; and 12, an optical path tube.

FIG. 2 is a plan view of a laser welded pipe manufacturing apparatus (first embodiment) according to the present invention. The laser welded pipe manufacturing apparatus 10 is formed in a tubular shape, and a welded portion W1 is directed upward. A pair of left and right squeeze rolls 13, which hold the metal band W from the left and right and abut the welded portion W 1, and a laser torch 14 which is attached downward between the squeeze rolls 13 and welds the welded portion W 1. And top rolls 15, 15 attached upstream of the laser torch 14 to suppress the welded portion W1 from above.

Since the top roll 15 has no effect if it is too far from the squeeze roll 13, it is arranged in the following range. When the radius of the upper flange 13a of the squeeze roll 13 is Rt and the distance from the center of the squeeze roll 13 to the roll shaft 15a of the top roll 15 is L, 0 <L ≦ Rt and interference with the laser torch 14 or the laser beam. Top roll 1 in range not to
5 and 15 are arranged.

FIG. 3 is a front view of a laser welded pipe manufacturing apparatus (first embodiment) according to the present invention, showing the relative positions of left and right squeeze rolls 13, 13, top rolls 15, 15 and laser beam 16. Since there is no fear of interference with the laser beam 16 (and the laser torch 14), the top rolls 15, 15 can be sufficiently close to the welded portion W1.

The operation of the laser welding pipe manufacturing apparatus described above will now be described. FIG. 4 is an explanatory view of the operation of the squeeze roll and the top roll. The metal band W is fed in a state where the welded portion W1 is slightly opened as shown by the imaginary line, and firstly into the corner 13d of the largest diameter lower flange 13b. Then, the to-be-welded portion W1 is forcibly bent by the top rolls 15 and 15 as shown by the solid line, and subsequently abuts on the corner 13c of the upper flange 13a. Thereafter, the metal band W fills the small diameter portion 13e of the squeeze roll 13, and welding is performed in the state of FIG.

That is, while the pressing action by the top rolls 15 and 15 is effective, the corner 13c of the upper flange 13a is formed.
Thus, the roll shaft 15a of the top roll 15 is set within the radius R of the upper flange 13a as shown in FIG.

Next, the results of a comparison experiment between the apparatus of the present invention and the conventional apparatus will be described. Table 1 shows the common conditions,
In this experiment, a carbon steel having an outer diameter of 101.6 mm was used as a test material (sample) because an experiment on a large-diameter pipe could not be performed due to facilities.

[0021]

[Table 1]

Table 2 shows Examples 1 to 4 (FIG. 2 according to the present invention).
FIG. 11 summarizes the experimental conditions and results of Comparative Examples 1 to 4 (the conventional apparatus in FIG. 8) and Comparative Examples 5 to 7 (the conventional apparatus in FIG. 10).

[0023]

[Table 2]

Example 1 In the equipment shown in FIG. 2 provided with the top rolls 15,
mm, the welding speed was 1 m / min, and the output was 4 kW. As a result, the laser beam satisfactorily “penetrated”, and the shape (finished shape) of the welded portion and tube after welding was good “O”.
Therefore, the evaluation is “○”. Examples 2, 3, 4;
When the experiment was conducted at 5.7 m / min and an output of 10, 17, and 25 kW, the laser beam satisfactorily “penetrated”, and the shape of the welded portion and tube after welding (finished shape) was good “O”. The evaluation is “○”. In Examples 1 to 4, the radius of the upper flange of the squeeze roll was 150 mm, and the distance from the center of the squeeze roll to the roll axis of the top roll was 125 mm.
mm.

Comparative Example 1 A conventional facility without a top roll, with a focal length of 400 mm and a welding speed of 1 m /
When the experiment was carried out at a power of 4 kW at min, the laser beam "penetrated" well. However, the shape (finished shape) of the welded portion and the tube after welding was poor "x" because the welded portion was raised upward, and the evaluation was "x". Comparative Examples 2, 3, 4;
When the experiment was performed at 5.7 m / min and an output of 10, 17, 25 kW, the laser beam “penetrated” well. However, the shape (finished shape) of the welded portion and the tube after welding was poor "x" because the welded portion was raised upward, and the evaluation was "x".

Comparative Example 5: Conventional equipment provided with a top roll, and a focal length of 80 in order to avoid interference with the top roll.
An experiment was performed using a 0 mm millet at a welding speed of 1 m / min and an output of 25 kW. As a result, the laser beam penetrated, but the shape of the weld after welding was somewhat poor, and the output was used effectively. Evaluation is "x" because it is not
And Comparative Examples 6 and 7: Compared with Comparative Example 5, the welding speed was 3.5 m.
When the experiment was conducted at a power limit of 25 kW / min, the laser beam did not penetrate, and the evaluation was "x".

[0027]

[Table 3]

Table 3 shows an experimental example in which the position of the top roll was changed. Example 2 Same as Example 2 in Table 2. Example 5: In comparison with Example 2, the distance between the center of the squeeze roll and the axis of the top roll was increased to 150 mm, and this 150 mm matched the radius of the upper flange.
Even in this case, the evaluation was ○.

Comparative Example 11: The distance between the center of the squeeze roll and the axis of the top roll is increased to 160 mm as compared with Example 2, and this 160 mm exceeds the radius of the upper flange. In this case, although the laser beam satisfactorily penetrated, the shape of the welded portion was slightly poor (△) because the welded portion was slightly raised before welding, and the evaluation was “×”. Comparative Example 12: Same result as Comparative Example 11, evaluation was "x"
It is.

Hereinafter, other embodiments (second embodiment and third embodiment) of the apparatus of the present invention will be described. FIG. 5 is a plan view of a laser welded pipe manufacturing apparatus (second embodiment) according to the present invention. The laser welded pipe manufacturing apparatus 20 is characterized in that a drum-shaped top roll 25 is employed. The other parts are the same as in the first embodiment of FIG. Since one drum-shaped top roll 25 can function as two top rolls (see FIG. 3), it is preferable to reduce the number of parts.

FIG. 6 is a plan view of a laser welding pipe manufacturing apparatus (third embodiment) according to the present invention, and FIG. 7 is a front view of the laser welding pipe manufacturing apparatus 30. The laser welding pipe manufacturing apparatus 30 includes left and right squeeze rolls 33, 3.
3, bottom roll 34, upstream top roll 35,3
5. Laser torch 36 and downstream top roll 37, 3
7 Since the bottom roll 34 is employed, the diameter of the lower flange 33b of the squeeze roll 33 can be reduced. If the lower flange 33b has a diameter as small as the upper flange 33a, it is possible to suppress the occurrence of flaws due to the difference in peripheral speed. In addition, the upstream and downstream top rolls 3
By suppressing the portion to be welded W1 at 5, 35, 37, and 37, more preferable welding can be performed. In addition, since the downstream side top rolls 37 and 37 have almost no fear of the swelling of the welded portion W1, the position can be freely determined, and the upper flange 33a is provided.
Can be deviated from the radius Rt of the upper flange 33a, but is preferably arranged within the radius Rt of the upper flange 33a.

[0032]

According to the present invention, the following effects are exhibited by the above configuration. The laser welded pipe manufacturing apparatus according to claim 1 is positioned at a pair of left and right squeeze rolls, a laser torch mounted downward between the squeeze rolls, and a position upstream of the laser torch and not interfering with the laser torch or the laser beam. A top roll whose roll axis is located within the radius of the upper flange of the squeeze roll,
The welded portion of the metal band formed into a tubular shape is held down by a top roll, and the metal band is transferred to a squeeze roll in this state. Can be manufactured. In addition, since the laser torch and the top roll are arranged so as not to interfere with the flow direction of the metal strip, the top roll can be freely arranged regardless of the laser torch, and as a result, the top roll can be brought sufficiently close to the welded part. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic view of a pipe rolling mill provided with a laser welded pipe manufacturing apparatus according to the present invention.

FIG. 2 is a plan view of a laser welded pipe manufacturing apparatus (first embodiment) according to the present invention.

FIG. 3 is a front view of a laser welded pipe manufacturing apparatus (first embodiment) according to the present invention.

FIG. 4 is an explanatory view of the operation of the squeeze roll and the top roll according to the present invention.

FIG. 5 is a plan view of a laser welded pipe manufacturing apparatus (second embodiment) according to the present invention.

FIG. 6 is a plan view of a laser welded pipe manufacturing apparatus (third embodiment) according to the present invention.

FIG. 7 is a front view of a laser welded pipe manufacturing apparatus (third embodiment) according to the present invention.

FIG. 8 is a sectional view of a conventional laser welded pipe manufacturing apparatus.

9 is a front sectional view of FIG. 8;

FIG. 10 is a principle diagram of a conventional laser welded pipe manufacturing apparatus with a top roll.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pipe rolling machine, 10, 20, 30 ... Laser welding pipe manufacturing apparatus, 11 ... Laser oscillator, 12 ... Optical path, 13, 33
... Squeeze rolls, 13a, 33a ... Top flange, 1
4, 36: laser torch, 15, 25, 35, 37: top roll, 15a: roll axis, 16: laser beam,
L: distance between the roll axis of the top roll and the center of the squeeze roll, Rt: radius of the upper flange of the squeeze roll, W: metal strip, W1: welded part.

Claims (1)

(57) [Claims] 1. A pair of left and right squeeze rolls, which are formed into a tubular shape and sandwich a metal band having a welded portion facing upward from right and left and abut the welded portion, and are mounted downward between the squeeze rolls. A laser torch for welding the portion to be welded, and a top roll attached to a position satisfying the following conditions, and a top roll for suppressing the portion to be welded from above. Top roll position: A position upstream of the laser torch and at a position where the top roll does not interfere with the laser torch or laser beam. The distance from the center of the squeeze roll to the roll axis of the top roll is not more than the radius of the upper flange of the squeeze roll.