JP2001170784A - Laser welding method and equipment - Google Patents

Abstract

(57) [Summary] In a laser pipe welding method and apparatus for a steel pipe, welding is performed by improving the positional accuracy of a target position of a laser beam with respect to a welding groove, without impairing the advantage of one-pass welding using a laser. Improve quality. SOLUTION: Welding truck 1 arranged in steel pipes 11, 11
0, the rotation center line O of the rotary support 16 is fixed substantially in line with the center axis of the steel pipe, the rotary support is rotated, and the welding groove position P of the steel pipe is detected by the sensing device 35, and the detection is performed. The groove plane S including the entire circumference of the welding groove is calculated based on the result, and the laser welding nozzle (laser welding means) erected on the rotating support is rotated so that the rotation center point A reaches the groove plane S. After moving and adjusting to the position, the rotation support is rotated and the laser beam is irradiated to the welding groove position by the laser welding nozzle while controlling the tilt axis in the groove plane one-dimensionally using the calculation data of the groove plane. Welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method and apparatus for welding a peripheral joint of a large steel pipe such as a pipeline or a gas pipe using a laser beam capable of guiding light with an optical fiber. Belongs to.

[0002]

2. Description of the Related Art Conventionally, in a welding method for a pipeline or the like, as shown in FIG. There is a so-called manual welding multi-layer welding method in which beat welding 1 is performed, hot-pass welding 2 is performed, and filler welding 3 is performed last.

[0003] Among other welding methods, a welding device mounted on a ring-shaped rail is set on the outer periphery of a peripheral joint of a pipe at a groove position, and the same procedure as the above-mentioned manual welding is performed by using the welding device. There is a multi-layer welding method by so-called semi-automatic welding, which is welding from the outer surface.

[0004] However, in the case of manual welding, although welding is simple, all operations are manual, which requires time and effort. In addition, there is a large artificial difference in construction depending on the skill level, and the welding quality is significantly reduced. May be invited. On the other hand, in the case of semi-automatic welding, since it is semi-automatic, the work of welding work is somewhat improved accordingly, but it takes time to accurately set the welding device to the groove position, and it still takes time to work. .

[0005] Further, whether manual welding or semi-automatic welding is used, multi-pass welding is required, so that the number of passes is considerably large and the arc time is long, resulting in low productivity. Further, in each case, welding materials such as a welding rod and a welding wire are separately required, and there is a problem that a complicated slag removal operation is required for each bead.

Therefore, in the conventional welding method, the welding material is not used, and the base material is melted by using a laser beam.
A laser welding method for welding the entire circumference of a groove with a pass has been proposed. For example, a truck is set on a ring-shaped rail outside the pipe joint at the groove position, the laser welding head mounted on the truck is rotated together with the truck, and a laser beam is irradiated on the groove to weld the entire circumference of the groove. There is something to do.

[0007]

[Problems to be Solved by the Invention] In the laser welding method, although a molten material may be supplied, in principle, the base material is melted and welded. The butt appearance of the groove is a thin line shape, and in addition, since welding is performed in one pass, strict positional accuracy of the target position with respect to the entire circumference of the groove of the laser beam is required. However, in the conventional laser welding method described above, the reference position of the target position is set linearly over the entire circumference of the groove from the outside of the pipe. It is extremely difficult to accurately determine the linear target position reference.In practice, there is a problem that the target position with respect to the groove of the laser beam is likely to be shifted, which may result in a decrease in welding quality. there were.

Accordingly, an object of the present invention is to solve the conventional problems in the above-described method and apparatus for laser welding steel pipes, and to provide a welding groove without impairing the advantages of one-pass welding using a laser beam. The purpose of the present invention is to improve the position accuracy of the target position of the laser beam with respect to the welding to improve the welding quality.

[0009]

The object of the present invention is to provide a laser welding method for welding a peripheral joint of a large steel pipe using a laser beam capable of guiding light with an optical fiber, wherein a laser welding means inserted into the steel pipe is mounted. The welded bogie is moved to stop at the approximate butt position of the steel pipe after skin matching, and the rotation center line of the rotary support that rotatably supports the laser welding means around the pipe axis of the steel pipe is substantially aligned with the center axis of the steel pipe. Align and fix, rotate the rotating support, detect the welding groove position of the steel pipe with the sensing device mounted on it, calculate the groove plane including the entire circumference of the welding groove based on the detection result, After adjusting the laser welding means along the rotation center line of the rotating support to the intersection of the rotation center line of the rotation support and the calculated groove plane, the center of rotation is adjusted using the calculation data of the groove plane. This is achieved by rotating the rotary support and irradiating a laser beam to the welding groove position by laser welding means while performing one-dimensional control of the tilt axis in the groove plane to perform welding.

[0010] The object of the present invention is to provide a laser welding method according to claim 1, wherein after the laser welding means is moved and adjusted along the rotation center line of the rotary support, the focal point of the laser beam is focused on the welding portion. The rotary support is rotated by laser welding means while controlling the position in the radial direction of the steel pipe so as to hit the steel pipe correctly, and one-dimensionally controlling the inclination axis in the groove plane using the calculation data of the groove plane. This is achieved by irradiating a beam to a welding groove position and performing welding.

An object of the present invention is to provide a laser welding apparatus for welding a peripheral joint of a large steel pipe by using a laser beam capable of guiding light with an optical fiber. After the joining, the welding cart stops at the approximate butting position, a rotating support body integrally erected such that the laser welding means is rotatable and movable in the tube axis direction and the inclination angle can be adjusted, and the rotation center of the rotating support body A fixing means for fixing the rotating support in the radial direction of the steel pipe by making the wire substantially coincide with the central axis of the steel pipe, and mounting the rotating support on the rotating support;
During welding, a sensing device for detecting the welding groove position of the steel pipe when rotating the rotating support, a linear moving means for moving the laser welding means along the rotation center line of the rotating support in the steel pipe, and a laser Tilting adjustment means for adjusting the tilting position of the rotating support with respect to the rotation center line with the rotation center as a fulcrum, and calculating a groove plane including the entire circumference of the welding groove based on the detection result by the sensing device; Then, by controlling the operation of the linear moving means and moving the laser welding means to the intersection of the calculated center plane and the center of rotation of the rotary support with the rotation center of the laser welding means, using the calculated data of the groove plane Control means for controlling the rotation driving means to rotate the rotary support while controlling the inclination axis in the groove plane one-dimensionally.

[0012] The object of the present invention is to provide a laser welding apparatus according to claim 3, wherein the laser welding means rotates the laser welding means so as to be position-controllable in the radial direction of the steel pipe so that the focal point of the laser beam is correctly focused on the welding part. This is achieved by standing upright on the support.

An object of the present invention is to provide a laser welding method for welding a peripheral joint of a large-sized steel pipe using a laser beam capable of guiding light with an optical fiber, in which a welding bogie equipped with laser welding means inserted into the steel pipe is run. The welding bogie is stopped by stopping at approximately the butt position of the steel pipe after the skin fitting, and making the rotation center line of the rotary support body that rotatably supports the laser welding means around the pipe axis of the steel pipe substantially coincide with the center axis line of the steel pipe. The welding groove position of the steel pipe is detected by the sensing device mounted on the rotating support, and the groove plane including the entire circumference of the welding groove is calculated based on the detection result. After the center is moved and adjusted along the rotation centerline of the rotary support to the intersection of the calculated groove plane with the rotation centerline of the rotary support, when rotating the rotary support, the welding groove position should not be detected. Et al., The data using a while one-dimensional control the tilt axis of the laser welding means, is achieved by performing welding by irradiating a laser beam to the welding groove position by laser welding means.

The object of the present invention is to provide a laser welding method according to claim 5, wherein after the laser welding means is moved and adjusted along the rotation center line of the rotary support, the focal point of the laser beam is focused on the welding portion. While controlling the position in the radial direction of the steel pipe so that it hits correctly, while rotating the rotating support, while detecting the welding groove position, using the data to control the tilt axis of the laser welding means one-dimensionally This is achieved by irradiating a laser beam to a welding groove position by laser welding means to perform welding.

An object of the present invention is to provide a laser welding apparatus for welding a peripheral joint of a large-sized steel pipe using a laser beam capable of guiding light with an optical fiber. After the joining, the welding cart stops at the approximate butt position, a rotating support body integrally erected so that the laser welding means can rotate and move in the pipe axis direction and adjust the inclination angle, and the rotation center line of the rotating support body To
Fixing means for fixing the rotary support in the radial direction of the steel pipe substantially in line with the central axis of the steel pipe, and mounting the rotary support on the rotary support so that the welding groove position of the steel pipe can be adjusted when rotating the rotary support during welding. A sensing device for detecting, a linear moving means for moving the laser welding means along the rotation center line of the rotary support in the steel pipe, and an inclination of the laser welding means with respect to the rotation center line of the rotary support with the rotation center as a fulcrum. The inclination movement adjusting means for adjusting the position and the groove plane including the entire circumference of the welding groove are calculated based on the detection result by the sensing device, and the rotation center of the laser welding means is rotated by controlling the operation of the linear movement means. After moving the laser welding means to the intersection of the rotation center line of the support and the calculated groove plane,
Controlling the rotation drive means to rotate the rotating support, and performing one-dimensional control of the tilt axis in the groove plane using the data while detecting the welding groove when the rotating support is rotating. Means.

The above object is achieved by the laser welding apparatus according to claim 7, wherein the laser welding means is capable of controlling the position of the laser beam in the radial direction of the steel pipe so that the laser beam can be properly focused on a welding portion. This is achieved by standing upright on the support.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an outline of a laser welding apparatus according to the present invention. In the drawing, reference numeral 10 denotes a steel pipe 1 after skin fitting.
1 is a welding cart of a laser welding apparatus according to the present invention, which is inserted and arranged in 1, 1; The welding trolley 10 includes a first trolley 13 having a drive wheel 12 pivotally supported on the outer periphery thereof, and a second trolley 15 having a driven wheel 14 pivotally supported on the outer periphery thereof. The carriages 13 and 15 are connected by a rotation support 16, and the rotation support 16 is rotatably supported about a rotation center line O via a bearing 17.

The first bogie 13 has a second
A rotation drive motor (rotation drive means) 18 is attached so as to protrude toward the cart 15. The first bogie 13 and the second bogie 15 are provided with a tension mechanism 19 having a structure that expands and contracts in the radial direction on the sides facing each other on the outer periphery, with an interval of a screening angle of, for example, 120 degrees in the outer periphery. It is attached to open.

The rotary support 16 has a substantially cylindrical shape, the central portion of which is formed to have a larger diameter by one step, and is accommodated inside the large diameter portion 16a to support the welding mechanism mounting frame 20. The large-diameter portion 16a is provided with an opening 16b on the upper side for exposing the welding mechanism mounting frame 20 to the outside, and a tooth portion 16 meshing with the motor gear 18a of the rotary drive motor 18 is provided on the outer periphery of the left edge in the figure.
c is provided.

As shown in FIGS. 3 and 4, the welding mechanism mounting frame 20 includes a welding mechanism indicated by reference numeral 21 in the figure. The welding mechanism 21 is provided with a laser welding nozzle (laser welding means) 23 on a nozzle mounting base 22 having a built-in welding operation part and the like. To adjust the tilt position. Then, the LM guide 2 that provides the nozzle mounting base 22 on the bottom of the welding mechanism mounting frame 20 in parallel with the rotation center line O of the rotary support 16.
5 and connected so as to be guided by an LM guide 25 so as to be linearly movable. The entire LM guide 25 is protected by a long cylindrical bellows (not shown).

An optical fiber and a control / power cable 24 are connected to the laser welding nozzle 23. The position of the laser welding nozzle 23 is controlled in the radial direction of the steel pipe so that the focal point of the laser beam is correctly applied to the welding portion. The laser used for welding with the laser welding nozzle 23 is a so-called Y capable of conducting light with an optical fiber.
AG laser, iodine laser and the like are preferable.

As shown in FIG. 3, a nozzle mounting base 22 is provided on the upper side of the welding mechanism mounting frame 20.
Is linearly moved integrally with the laser welding nozzle 23.

The linear moving means 26 has a servomotor 27 mounted on the upper left side of the welding mechanism mounting frame 20, and has a motor shaft of the servomotor 27 connected to a feed shaft 29 via a rotation transmitting coupling 28a and a servo unit 28b. One end is connected. The other end of the feed shaft 29 is supported on the upper right side of the welding mechanism mounting frame 20 via an angular ball bearing 30. The nozzle mounting base 22 is connected to the feed shaft 29 via a ball screw 31 engaged with the feed shaft 29.

The rotating support 16 described above is equipped with a sensing device, described later, for detecting the welding groove position of the steel pipes 11, 11 when the rotating support 16 is rotated during welding, which will be described later. As the sensing device, an optical detection type, a mechanical detection type, and the like can be considered.

Further, as shown in FIG. 5, the rotary support 16 has a nozzle mounting base 22 of a welding mechanism mounting frame 20 and a laser welding nozzle 23 with its rotation center A as a fulcrum. A tilt movement adjusting means 32 for adjusting the tilt position is mounted.

The tilt movement adjusting means 32 is provided on the rotating support 16.
Nozzle mounting base 2 in a direction orthogonal to the rotation center line O of
2, a rotation support shaft 33 rotatably supported at both ends,
The laser welding nozzle 23 is supported by a mounting arm 34 erected integrally with the rotation support shaft 33. In addition, the rotation support shaft 33
The bevel gear 35 is mounted on the upper
And the worm gear 36 is mounted on the feed shaft 29. Then, the rotation of the feed shaft 29 driven by the servomotor 27 is transmitted to the rotation support shaft 33 via the engagement between the bevel gear 35 and the worm gear 36, and the laser welding nozzle 23 is rotated to adjust the tilt position. I have.

Although not shown, the illustrated laser welding apparatus includes a moving vehicle equipped with a power supply, a laser light oscillator, a cooling system supply unit, a control panel (control unit), and the like. The entire operation can be controlled by the control panel.

The bearing 17 and the servo unit 28 used in the laser welding apparatus shown in FIG.
b, the ball screw 31 and the like are configured to have a preload structure so as to absorb backlash and mounting errors.

Next, a description will be given of a method for welding the steel pipes 11, 11 using the laser welding apparatus having the above-described configuration.

In laser welding, the steel pipes 11, 11
It is desirable that the root gap of the welding groove is 0.2 mm or less, for example. However, after the steel pipes 11 and 11 are skinned, the welding carriage 10 is inserted and arranged therein. And
As shown in FIG. 1 (a), the welding carriage 10 travels, and the operator detects the position using a CCD camera or the like, and detects the approximate butting position B of the steel pipes 11 (for example, within a range of about 25 mm before and after the butting position). To stop.

Next, the tensioning mechanism 19 is operated, and as shown in FIG.
Are substantially coincident with the central axes of the steel pipes 11, 11, and the welding cart 10 is fixed at the stop position.

Thereafter, the rotary support 16 is rotated by the rotary drive motor 18, and as shown in FIG. 1 (c), the welding groove position P of the steel pipes 11, 11 is detected by the sensing device 35. A groove plane S including the entire circumference of the welding groove P is calculated based on the groove.

Then, the servo motor 27 of the linear moving means 26 is operated to rotate the feed shaft 29, and the nozzle mounting base 22 is linearly integrated with the laser welding nozzle 23 as shown in FIG. Then, as shown in FIG. 6, the rotation center A of the laser welding nozzle 23 is moved and adjusted to a position where the rotation center A reaches the calculated groove plane S.

Then, the tilt movement adjusting means 32 is operated to adjust the tilt position of the laser welding nozzle 23 with respect to the rotary support 16 with the rotation center A as a fulcrum by using the calculation data of the groove plane S. While the tilt axis L in the front plane S is one-dimensionally controlled, the rotary support 16 is rotated, and a laser beam is irradiated from a laser welding nozzle 23 to a welding groove position to perform welding. At this time, the laser welding nozzle 23
Is controlled in the radial direction of the steel pipe so that the laser beam is properly focused on the welding site.

In the strict sense, the circumferential joint of the steel pipes 11, ie, the groove surface, is seldom perpendicular to the rotation center line O of the rotary support 16 in practice. It does not always completely coincide with the central axis of the steel pipes 11,11. Therefore, as shown in FIG. 7, when the rotation center of the laser welding nozzle 23 is at the point B shifted from the groove plane S, and the laser light and the groove plane S are not parallel, welding is performed around the point B. In this case, the tilt angle of the laser welding nozzle 23 is complicated at the rotation angle position, and the tilt axis control of the laser beam becomes two-dimensional or more.
There is a possibility that the target position with respect to the groove of the laser beam is shifted and the welding quality is reduced.

However, in the present invention, since the center of rotation A of the laser welding nozzle 23 is moved and adjusted so as to be within the groove plane S, when welding is performed around the point A, the tilt axis L
Is only one-dimensional control that provides a simple SINE curve, and the target position with respect to the groove of the laser beam can be made more accurate.

In the above-described embodiment, the welding is performed by rotating the rotary support 16 once each time the operation of detecting the groove position by the sensing device 35 and the operation of laser irradiation welding by the laser welding nozzle 23 are performed. Was. However, the present invention can also be configured to perform groove detection and laser irradiation welding with one rotation of the rotary support 16.

Also in this case, welding is performed using a laser welding apparatus having the same structure as the laser welding apparatus in the above embodiment. Then, during laser welding, after the laser welding nozzle 23 as a laser welding means is moved and adjusted to a position where the rotation center A reaches the calculated groove plane S, especially when the rotation support 16 is rotated, sensing is performed. While detecting the welding groove position by the device 35, the laser beam is irradiated to the welding groove position by the laser welding nozzle 23 to perform welding while the tilt axis L is one-dimensionally controlled using the data.

That is, when the rotating support 16 makes one rotation, the welding groove position is detected immediately before the irradiation of the laser beam, and while the groove position is detected in real time, the welding groove position is detected immediately thereafter. Control to perform welding by irradiating laser beam. In addition, similarly, the laser welding nozzle 2
The position of 3 is controlled in the radial direction of the steel pipe so that the laser beam is properly focused on the welding site.

[0041]

According to the present invention configured as described above,
The following effects can be obtained.

According to the laser welding method and apparatus of the present invention, the groove position is detected by being installed in a steel pipe and rotating from the inside with the rotation center axis of the rotary support of the laser welding means as the sole rotation reference. Since the target position of the laser beam with respect to the entire circumference of the groove is set with reference to one point in the plane including the entire circumference of the groove calculated based on the detection result, as in the conventional case, Unlike in the case of performing automatic welding with a groove on the basis of a ring-shaped rail, the target position of the laser beam with respect to the groove is less likely to shift,
The strict setting of the target position of the laser beam with respect to the welding groove at the welding site is remarkably facilitated, and the accuracy of the target position is improved to improve the welding quality.

Further, the rotary support mounted on the welding carriage is fixed so that the rotation center line of the rotary support substantially coincides with the center axis of the steel pipe, and the rotation center of the laser welding means is set within a groove plane calculated in advance. While the laser welding means is moved and adjusted to the position where it reaches, the one-dimensional control of only the inclined axis is performed using the computation data of the groove plane, and the welding is performed. Even if it is not a right angle but inclined, it follows exactly this and matches the target position of the laser beam without error to the welding groove, thereby minimizing the mechanical error element during field welding. Welding quality can be improved.

Of course, the present invention is a laser welding method and apparatus for welding using a laser capable of guiding light through an optical fiber, so that there is no great difference in the work depending on the skill level. In addition, since it is one-pass welding on a flat groove (I groove) peculiar to beam welding such as laser welding instead of multi-layer welding as in the conventional case, the arc time can be remarkably reduced and the productivity can be increased. . Further, since welding can be performed by melting into the base material, a welding material can be made unnecessary, and quality control can be simplified without troublesome slag removal work.

In addition, according to the laser welding method and apparatus according to the fifth and seventh aspects, when the rotating support is rotated, the detection of the welding groove position is started immediately before the irradiation of the laser beam, While detecting the groove position, immediately irradiate the laser beam to the welding groove position and perform the groove detection and laser welding with one rotation of the rotating support, so the construction time is shortened accordingly Efficiency can be increased.

In addition, claims 2, 4, 6, and 8
According to the method and apparatus for laser welding, the position of the laser welding means is controlled in the radial direction of the steel pipe so that the focus of the laser beam is correctly focused on the welding area, thereby further improving welding accuracy Can be done.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing a construction process of a laser welding construction method performed by using a laser welding construction device according to the present invention.

FIG. 2 is a schematic vertical sectional view showing a laser welding apparatus according to the present invention disposed at a welding groove position in a steel pipe.

FIG. 3 is a schematic longitudinal sectional view showing a welding mechanism mounted on a welding mechanism mounting frame of the laser welding apparatus.

FIG. 4 is a schematic configuration diagram showing the welding mechanism as viewed from the front side.

FIG. 5 is a schematic vertical sectional view showing a tilt movement adjusting means provided in the laser welding apparatus.

FIG. 6 is an explanatory diagram illustrating a one-dimensional control state of an inclined axis on a groove plane at a welding groove position.

FIG. 7 is an explanatory diagram for comparing and explaining position adjustment control when the rotation center of the laser welding nozzle is at a groove plane and at a position deviated therefrom.

FIG. 8 is a state explanatory view showing a multi-layer welding state performed without using conventional laser welding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Welding trolley 11 Steel pipe 16 Rotary support body 18 Rotation drive motor (Rotation drive means) 19 Stretching mechanism (Fixing means) 23 Laser welding nozzle (Laser welding means) 26 Linear movement means 32 Tilt movement adjustment means 35 Sensing device A, B Laser Rotation center of welding nozzle O Rotation center line of rotating support P Weld groove position S Groove plane

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 101: 06 B23K 101: 06 101: 10 101: 10 103: 04 103: 04

Claims (8)

[Claims] 1. A laser welding method for welding a peripheral joint of a large steel pipe using a laser beam capable of guiding light with an optical fiber. Stops at the approximated abutting position of the steel pipe after joining, and fixes the rotation center line of the rotating support that supports the laser welding means so that it can rotate around the pipe axis of the steel pipe so that it substantially matches the center axis of the steel pipe. The body is rotated, the welding groove position of the steel pipe is detected by the sensing device mounted on the body, the groove plane including the entire circumference of the welding groove is calculated based on the detection result, and the laser welding means is set to the rotation center. After moving and adjusting along the rotation center line of the rotary support to the intersection of the calculated groove plane and the rotation center line of the rotation support, the inclination axis in the groove plane is calculated using the calculation data of the groove plane. once While controlling a laser welding method and performing welding by irradiating a laser beam to the welding groove position rotated laser welding means rotating supports. 2. The laser welding method according to claim 1, wherein after the laser welding means is moved and adjusted along the rotation center line of the rotary support, the focal point of the laser beam is correctly adjusted with respect to the welding portion. In addition to controlling the position of the steel pipe in the radial direction so as to hit it, while controlling the tilt axis in the groove plane one-dimensionally using the calculation data of the groove plane, the rotating support is rotated and the laser beam is irradiated by the laser welding means. A laser welding method characterized by irradiating a welding groove position to perform welding. 3. A laser welding apparatus for welding a peripheral joint of a large-sized steel pipe using a laser beam capable of guiding light with an optical fiber. Is a welding trolley that stops at the approximate abutment position, a rotating support that integrally mounts the laser welding means so as to be rotatable, movable in the pipe axis direction, and is capable of adjusting the inclination angle, and a rotation center line of the rotating support. A fixing means for fixing the rotary support in the radial direction of the steel pipe so as to substantially coincide with the central axis of the steel pipe, and a welding groove position for the steel pipe when the rotary support is rotated when the rotary support is mounted on the rotary support during welding. A linear sensing device that moves the laser welding means in the steel pipe along the rotation center line of the rotating support, and the laser welding means is rotated about the rotation center. A tilt movement adjusting means for adjusting the tilt position of the body with respect to the rotation center line, and a groove plane including the entire circumference of the welding groove based on the detection result by the sensing device, and controlling the operation of the linear moving means to control the laser. After moving the laser welding means to the intersection of the rotation center line of the rotating support and the calculated groove plane with the rotation center of the welding means, the tilt axis in the groove plane is one-dimensionally calculated using the calculation data of the groove plane. Control means for controlling the rotation drive means to rotate the rotary support while controlling the laser support means. 4. A laser welding apparatus according to claim 3, wherein said laser welding means is capable of controlling a position of said laser welding means in a radial direction of a steel pipe so that a laser beam is correctly focused on a welding portion. Laser welding equipment characterized by being installed upright in a building. 5. A laser welding method for welding a peripheral joint of a large-sized steel pipe using a laser beam capable of guiding light with an optical fiber, the method comprising: The welding carriage is stopped by stopping at approximately the butted position of the steel pipes after the joining, and making the rotation center line of the rotary support body that rotatably supports the laser welding means around the pipe axis of the steel pipe substantially coincide with the center axis line of the steel pipe. The sensing device mounted on the rotating support detects the welding groove position of the steel pipe, calculates the groove plane including the entire circumference of the welding groove based on the detection result, and determines the laser welding means and the rotation center. After adjusting the movement along the rotation center line of the rotating support to the intersection of the calculated center plane and the rotation center line of the rotating support, when rotating the rotating support, the welding groove position is detected while detecting the welding groove position. While one-dimensional control the tilt axis of the laser welding means using the data, laser welding method and performing welding by irradiating a laser beam to the welding groove position by laser welding means. 6. The laser welding method according to claim 5, wherein after the laser welding means is moved and adjusted along the rotation center line of the rotary support, the focal point of the laser beam is correctly adjusted with respect to the welding portion. While controlling the position of the steel pipe in the radial direction so as to hit it, and detecting the welding groove position when rotating the rotary support, using the data to control the tilt axis of the laser welding means one-dimensionally, A laser welding method characterized by irradiating a laser beam to a welding groove position by welding means to perform welding. 7. A laser welding apparatus for welding a peripheral joint of a large-sized steel pipe using a laser beam capable of guiding light with an optical fiber. Is a welding cart that stops at the approximate abutment position, a rotary support that integrally mounts the laser welding means so that it can rotate and move in the pipe axis direction and adjust the tilt angle, and a rotation center line of the rotary support, Fixing means for fixing the rotary support in the radial direction of the steel pipe so as to substantially coincide with the central axis of the steel pipe; and mounting the rotary support on the rotary support so that the welding groove position of the steel pipe can be adjusted when the rotary support is rotated during welding. A sensing device for detecting, a linear moving means for moving the laser welding means along the rotation center line of the rotary support in the steel pipe, and a laser welding means for rotating the laser support means with the rotation center as a fulcrum. A tilt movement adjusting means for adjusting a tilt position with respect to a rotation center line; a laser welding means for calculating a groove plane including a whole circumference of a welding groove based on a detection result by a sensing device, and controlling an operation of the linear moving means. After moving the laser welding means to the intersection of the rotation center line of the rotation support and the calculated rotation center line in the groove plane, the rotation support is rotated by controlling the rotation drive means, and the rotation of the rotation support is performed. Control means for one-dimensionally controlling the tilt axis in the groove plane using the data while detecting the welding groove. 8. The rotary support according to claim 7, wherein the laser welding means is capable of controlling the position of the laser welding means in the radial direction of the steel pipe so that the focus of the laser beam is correctly applied to the welding portion. Laser welding equipment characterized by being installed upright in a building.