JPH0588780U - Laser welding equipment for pipes - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the cost and improve the reliability of laser welding equipment that accurately welds the butt seam of pipes without any deviations in the weld. [Structure] A laser head unit 4 is installed right above a horizontally fed pipe 1 so as to be swingable in a lateral direction orthogonal to the pipe 1. The upper portion of the laser head portion 4 is rotatably supported by a head support portion 5 and swings like a pendulum, and the tip end of a connecting arm 6 attached to the lower portion and extending in a direction opposite to the pipe conveying direction is provided with a pipe butt position detecting means. A roller 7 is attached. The lower peripheral edge of the roller 7 is brought into contact with the butt seam portion 2 of the pipe 1 to cause the butt seam portion 2 to follow the movement.
When the butt seam portion 2 is displaced, the roller 7 follows it to move the laser head portion 4 laterally integrally, and the laser beam 3 always follows the butt seam portion 2 for welding.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a laser welding device for sequentially welding butt seams of pipes with a laser beam.

[0002]

[Prior Art]

Welding methods for pipes manufactured by sequentially welding butt seams on both end faces of the pipe material while bending the strip-shaped metal pipe material in a circular shape in the width direction include high-frequency induction heating and resistance heating. The high-speed pressure welding method and the TIG welding method are generally used, but in recent years, a laser welding method using a high-power CO ₂ laser beam has tended to be adopted.

Pipe welding with a laser beam has advantages such as excellent welding quality and good production efficiency. However, in this type of laser welding, the spot diameter of the laser beam is about 0.5 mm, which is extremely small. Therefore, if the beam spot irradiated on the pipe deviates from the welding line of the butt seam of the pipe even a little. However, welding defects may occur and welding defects may occur, resulting in poor weld quality. Therefore, conventionally, as a method for preventing the welding deviation, the laser beam scanning method shown in FIG. 7 and the image processing method using a CCD camera shown in FIG. 8 are adopted.

The laser welding apparatus shown in FIG. 7 is configured such that a strip-shaped pipe material 1 ′ is bent in a cylindrical shape by a plurality of forming rollers 10 and is fed in the longitudinal direction, and a butt seam of both end faces of the pipe material 1 ′ is provided. The portion 2 is welded with the laser beam 3 from the laser head portion 30. While the pipe material 1'is horizontally fed, both side portions are gradually bent upward by the forming roller 10, and both end surfaces are abutted at a predetermined position to form a butt seam portion 2. When the butt seam portion 2 reaches the welding point P directly below the laser head portion 30, it is welded by the laser beam 3 which scans sideways. The welded pipe 1 is sent backward by the forming roller 10. By doing so, the butt seam portion 2 of the pipe 1 is welded in a zigzag shape, and therefore, even if the butt seam portion 2 is slightly displaced laterally in the circumferential direction of the pipe, the butt seam portion 2 is scanned by the laser beam 3. It will be welded surely, and the weld gap is prevented.

The laser welding apparatus in FIG. 8 causes the laser beam 3 to follow the positional deviation of the butt seam portion 2 of the pipe material 1 ′ in the circumferential direction of the pipe, and welds the butt seam portion 2 with the laser beam 3. That is, the CCD camera 31 takes an image of the vicinity of the butt start point Q in front of the welding point P to be welded by the laser beam 3 of the butt seam portion 2, and from the image processing, the displacement direction of the butt seam portion 2 in the circumferential direction of the pipe. , The amount is detected, the laser head 32 is moved to follow this position, and automatically corrected so that the welding point P of the laser beam 3 is always on the welding line of the butt seam 2. Eyesight is prevented.

[0006]

[Problems to be solved by the device]

 By the way, in the laser welding apparatus of FIG. 7, not only the butt seam portion 2 of the pipe 1 but also the pipe material 1 ′ itself is welded by the laser beam 3. Therefore, as the plate thickness of the pipe material 1 ′ increases, the laser beam It becomes difficult to satisfactorily weld due to the insufficient power of 3. In fact, the device in FIG. 7 cannot be applied to pipe welding with a plate thickness of several mm or more, and lacks versatility. Further, since the butt seam portion 2 of the pipe 1 and its vicinity are welded in a zigzag shape, there is a problem that a large amount of thermal strain occurs in the vicinity of the butt seam portion 2.

The laser welding apparatus shown in FIG. 8 can perform high-quality pipe welding regardless of the plate thickness of the pipe 1. However, the CCD camera 31 and the auxiliary device for image processing are expensive, and there is a problem that the total equipment cost is high. Further, when taking an image with the pipe 1 and the CCD camera 31, it may be affected by noise of external light, and there is a problem of lack of reliability.

Therefore, it is an object of the present invention to provide a laser welding apparatus that is inexpensive and can perform high quality pipe welding regardless of the plate thickness of the pipe.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention irradiates a laser beam from directly above a predetermined position on a butt seam portion of an upper portion of a pipe conveyed in the axial direction, and sequentially welds the butt seam portion. And a head support that supports the laser head so that it can swing in a lateral direction orthogonal to the pipe, and a tip of a connecting arm that extends from the laser head in the direction opposite to the pipe transport direction. Pipe butt position detection means that follows the butt seam portion to move in the displacement direction of the butt seam portion, and at the same time moves the laser head portion laterally along the connecting arm with the same amount of movement. It is characterized by having.

[0010]

[Action]

 When welding the butt seam part of the pipe with the laser beam from the laser head part, if the butt seam part is displaced in the circumferential direction of the pipe, the pipe butt position detection means moves laterally following this displacement. At the same time, the laser head is moved laterally with the same amount of movement, and this movement causes the laser beam to weld the butt seam portion of the pipe from the correct direction at all times, thus preventing the weld from deviating. As the pipe butt position detecting means, a roller having a simple structure and a low cost, such as a roller which comes into contact with the butt seam portion of the pipe and mechanically follows the butt seam portion, is used.

[0011]

【Example】

 An embodiment of the present invention will be described with reference to FIGS. Further, in order to clarify the technical contents of the present invention, a prerequisite technique which is not a publicly known technique but has been examined by the present inventor will be described with reference to FIGS. 5 and 6 prior to the present invention.

The laser welding apparatus shown in FIGS. 5 and 6 welds the butt seam portion 2 of the pipe 1 with the laser beam 3 from the laser head portion 4 ′. The laser head unit 4 ′ has a built-in optical system 12 that reflects the laser beam 3 projected from the beam generation source 11 and focuses it on the butt seam unit 2. The optical system 12 reflects the laser beam 3a projected from the beam generation source 11 in a direction parallel to the pipe 1 downward by 90 ° by the upper reflection mirror 13 and directs it to the condenser mirror 15 by the lower reflection mirror 14. reflect. The focusing mirror 15 focuses the laser beam 3 on the butt seam portion 2 from directly above. The laser head portion 4'is supported rotatably laterally with the optical axis of the laser beam 3b between the upper and lower reflection mirrors 13 and 14 as the rotation center line A. A connecting arm 16 extending from the lower front surface of the laser head portion 4'in the direction opposite to the conveying direction of the pipe 1 is fixed. A roller 7 is rotatably attached to a tip portion of the connecting arm 16 bent downward. The roller 7 detects the position of the butt seam portion 2 of the pipe 1, and corresponds to the pipe butt position detecting means of the present invention described later. The roller 7 is located at the butt start point Q 1 of the butt seam portion 2, and the lower peripheral edge of the roller 7 is fitted and inserted into the gap g of the butt start point Q formed by both end faces of the pipe material 1 ′, and the state is maintained. ..

The pipe 1 is conveyed in the axial direction, the butt seam portion 2 is sequentially fed to the welding point P of the laser beam 3, and laser welding is performed. At this time, the roller 7 follows the butt start point Q. Therefore, when the butt seam portion 2 of the conveyed pipe 1 is displaced in the circumferential direction of the pipe, the displacement follows and the roller 7 moves laterally around the rotation center line A as shown by the chain double-dashed line in FIG. Moving. The lateral movement of the roller 7 causes the laser head portion 4'to rotate about the rotation center line A via the connecting arm 16, so that the welding point P of the butt seam portion 2 by the laser beam 3 is displaced in the direction of displacement of the butt seam portion 2. To move sideways. By moving the welding point P by following the positional deviation of the butt seam portion 2 in this manner, the weld seam of the butt seam portion 2 is prevented from being displaced, and the welding quality is improved.

The above-described prerequisite technique of the present invention is to minimize the difference between the distance L1 from the rotation center line A of the laser head 4'to the welding point P and the distance L2 from the rotation center line A to the roller 7. However, it is required to reduce the deviation of the welded seam of the butt seam portion 2. That is, as shown in FIG. 6, the distance that the roller 7 laterally moves due to the displacement of the butt seam portion 2 and the moving distance of the welding point A at this time do not match, and the ratio of the distances L1 and L2 ( There is an amount of error corresponding to L1 / L2). This error appears as an error in the weld seam of the butt seam portion 2 as it is, and may cause welding failure depending on the type of pipe.

The inventor of the present invention has studied to eliminate such an error in the welding stitches and developed a laser welding apparatus shown in the embodiments of FIGS. 1 to 4. Embodiments of the present invention will be described below. The same or corresponding parts of the devices of FIGS. 1 to 4 as those of FIGS. 5 and 6 are designated by the same reference numerals and description thereof will be omitted.

As shown in FIGS. 1 and 2, a laser head portion 4 is installed right above a pipe 1 that is horizontally fed so as to be swingable in a lateral direction orthogonal to the pipe 1. The upper portion of the laser head portion 4 is rotatably supported by the head support portion 5 so that the laser head portion 4 swings like a pendulum. A connecting arm 6 extending forward, which is opposite to the pipe conveying direction, is attached to the lower part of the laser head portion 4, and a pipe abutting position detecting means such as a roller 7 is rotatably attached to a tip end portion of the connecting arm 6. The lower peripheral edge of the roller 7 is inserted into the abutment start point Q of the abutment seam portion 2 of the pipe 1 so that the roller 7 is operated following the abutment seam portion 2. The welding point P at the butt seam portion 2 by the laser beam 3 from the laser head portion 4 and the roller 7 are aligned on a straight line parallel to the pipe axis direction.

The laser head unit 4 has a horizontal L-shaped upper box 17 having an upper reflection mirror 13 built-in, and a lower box 18 having a lower reflection mirror 14 and a condenser mirror 15 built-in. A horizontal cylindrical portion 17a of the upper box 17 is axially slidably connected to the beam generation source 11, and a vertical cylindrical portion 17b of the upper box 17 is axially slidably connected to the lower box 18. The horizontal cylindrical portion 17a of the upper box 17 is rotatably supported by the head supporting portion 5 via a bearing 19. The head supporting portion 5 supports the horizontal cylindrical portion 17a of the upper box 17 with a bearing member 21 supported on the lower surface of the fixed frame 20 so as to be movable in the pipe axial direction. The rotation center line B of the horizontal cylindrical portion 17a is aligned with the optical axis of the laser beam 3a parallel to the pipe 1 projected from the beam generation source 11 toward the upper reflection mirror 13, and this rotation center line B The laser head unit 4 swings in a pendulum manner around. One end of the connecting arm 6 is rotatably connected to the lower surface of the lower box 18 only in the vertical direction so that the roller 7 follows the vertical movement of the pipe 1. Reference numeral 22 in FIG. 1 is a rocking frame that rocks integrally with the laser head unit 4, and serves as a guide for holding the lower box 18 and moving it up and down.

Next, the pipe welding operation according to the above embodiment will be described. The laser head portion 4 is set at an appropriate height position according to the pipe 1, and the butt seam portion 2 of the pipe 1 is welded by the laser beam 3 from the laser head portion 4. At this time, the roller 7 is inserted into the gap g of the abutment start point Q of the abutment seam portion 2 and follows the abutment seam portion 2. When the pipe 1 is conveyed by the forming roller 10 without displacement of the butt seam portion 2 of the pipe 1, the welding point P of the pipe 1 by the laser beam 3 is on the welding line of the butt seam portion 2, Normal welding continues. When the butt seam portion 2 is displaced in the circumferential direction of the pipe, the roller 7 laterally moves following this positional displacement, and this movement causes the roller 7 to move laterally to the lower portion of the laser head portion 4 via the connecting arm 6. An external force acts on the laser head portion 4 and the laser head portion 4 swings around a horizontal rotation center line B. The lateral movement of the welding point P and the lateral movement of the roller 7 due to the swinging of the laser head portion 4 are carried out in parallel in the same direction and in the same amount, as indicated by the arrows in FIGS. Therefore, the roller 7 and the welding point P both accurately follow the positional deviation of the butt seam portion 2, and the laser beam 3 irradiating the welding point P welds the butt seam portion 2 without any misalignment. It

It should be noted that the laser beam 3 from the laser head portion 4 may obliquely weld the butt seam portion 2 by the rotation around the rotation center line B of the laser head portion 4. However, compared with the distance from the rotation center line B to the pipe 1, the displacement amount of the butt seam portion 2 is very small. Therefore, even if the laser head portion 4 rotates a little, the laser beam 3 abuts the seam portion 2. Since welding is performed from almost orthogonal directions, the amount of diagonal penetration due to diagonal welding can be ignored and normal welding is always performed.

[0020]

[Effect of the device]

 According to the present invention, when the butt seam portion of the pipe is displaced in the circumferential direction of the pipe, the pipe butt position detection means moves laterally following this positional displacement, and at the same time, the laser head portion also laterally moves with the same movement amount. As a result, the laser beam always accurately follows the butt seam of the pipe to prevent the weld from deviating, and it is possible to easily weld the butt seam of the pipe with high quality. In addition, as the pipe butt position detection means that detects the position shift of the butt seam part of the pipe and corrects the position of the laser beam, a simple and inexpensive structure like a roller that contacts the butt seam part of the pipe and follows it is applied. It is possible to provide a laser welding apparatus that is advantageous in terms of cost and equipment.

[Brief description of drawings]

FIG. 1 is a front view including a partial cross section showing an embodiment of the present invention.

FIG. 2 is a right side view of the apparatus shown in FIG.

FIG. 3 is an enlarged perspective view of a part of the apparatus shown in FIG.

FIG. 4 is a plan view of a pipe in the apparatus shown in FIG.

FIG. 5 is a front view of a main part of a laser welding device which is a premise of the present invention.

FIG. 6 is a plan view of a pipe in the apparatus shown in FIG.

FIG. 7 is a perspective view of a main part of a conventional laser welding device.

FIG. 8 is a perspective view of a main part of another conventional laser welding apparatus.

[Explanation of symbols]

 1 Pipe 2 Butt Seam Section 3 Laser Beam 4 Laser Head Section 5 Head Support Section 6 Connecting Arm 7 Pipe Butt Position Detection Means (Roller)

Claims (1)

[Scope of utility model registration request] 1. A laser head part for irradiating a laser beam to a butt seam part on an upper portion of a pipe conveyed in an axial direction from directly above a predetermined position to sequentially weld the butt seam part, and a laser head part. A head support part that swings in the lateral direction orthogonal to the pipe and a tip of a connecting arm that extends forward from the laser head part in the direction opposite to the pipe transport direction and is supported by the butt seam part of the pipe before welding. A pipe butt position detecting means for moving the butt seam portion in the direction of positional deviation and at the same time moving the laser head portion in the lateral direction by the same amount of movement through the connecting arm. Laser welding equipment.