JP2008000764A - Method, device and equipment for laser beam welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method, a device and equipment for laser beam welding for performing the good welding of superposed metal plates by taking the size of the gap between the metal plates into consideration. <P>SOLUTION: The laser beam welding of two metal plates 2, 3 is performed by moving the laser beam 1 toward the large side from the small side of the gap 4 between the two superposed metal plates 2, 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser welding method, apparatus, and equipment for welding stacked plate materials in consideration of the size of a gap between them, and more particularly to a technique suitable for welding by a remote laser welding method. .

  The laser welding equipment used in the mass production process uses, for example, a multi-degree-of-freedom welding robot as a welding mother machine, and a laser processing head (welding torch) is provided at the tip of the welding robot, while a YAG laser that can be transmitted by an optical fiber cable. The mainstream is that the laser beam is irradiated from the machining head to the welded part using a laser beam or the like. However, for example, when welding points are scattered over a wide range, it takes time to move the machining head, and it is not possible to cope with welding at a site where the machining head interferes, such as a narrow groove.

  Therefore, in recent years, a relatively long-focus laser beam (laser beam) is reflected by an optical deflection optical system composed of a plurality of mirrors, and the angle of the mirror of the optical deflection optical system is variably controlled, so that the laser beam is controlled. A technique called a remote laser (scanner laser) welding method that has been moved to the next welding point instantaneously to perform the next welding, and also allows the focal length to be adjusted for each welding point (see below) (See Patent Documents 1 and 2).

  In general, when laser welding is performed on a galvanized steel sheet as a workpiece of an automobile body, the zinc layer between the workpieces is evaporated and scattered by the heat of the laser beam, resulting in welding defects. In order to prevent this, a technique of providing an appropriate gap between the steel plates and discharging the evaporated gas is used.

This gap is generally installed in the form of an emboss, but it is very difficult to obtain a necessary gap (for example, 0.2 mm) by always processing the height of the emboss to be constant. Therefore, the gap may not be created by embossing depending on the processing method. Also, the gap may be too wide, but even when there is such a wide gap, conventionally, welding was performed by adjusting only the welding position without considering the welding direction. There was a problem that welding was not welded.
Japanese Patent Laid-Open No. 10-216980 Japanese Patent Laying-Open No. 2003-145285 (FIG. 1)

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a laser welding method and apparatus for well welding stacked plate materials in consideration of the size of the gap between them. And to provide facilities.

  In order to achieve such an object, the laser welding method of the present invention comprises performing laser welding of a plate by moving a laser beam from a smaller gap to a larger gap between stacked metal plates. Features.

  The laser welding apparatus according to the present invention includes a clamping unit that overlaps and clamps plate materials so that a gap is formed, and a plate member that is overlapped and clamped by the clamping unit in a direction away from a position closer to the clamping point. And a laser device that emits a laser beam.

  Further, the laser welding equipment of the present invention includes a clamping unit that overlaps and clamps the plate materials so that a gap is formed, and a direction away from the side closer to the clamping point in order to weld the overlapped and clamped plate materials by the clamping unit. A laser device that irradiates a laser beam, and the laser device is connected to the laser oscillator by an optical fiber and includes an optical deflection optical system that deflects the emission direction of the laser beam And a robot hand equipped with the optical head.

  A metal plate for achieving such an object is a metal plate having a welding locus that is continuously laser-welded by forming a gap between stacked metal plates, and at least a welding start point is welded thereafter. The gap is smaller than the welding trajectory toward the end point.

  In the laser welding method, apparatus, and facility of the present invention, the plate material is laser welded by moving the laser beam from the smaller gap to the larger gap between the stacked plate members. Thereby, even if it is a location where a gap is large so that welding cannot be performed when the gap is welded from a large direction to a small direction, good welding is performed. Therefore, according to the present invention, it is possible to reduce unwelding caused by a large gap.

  Moreover, in this invention, since favorable welding is performed even at a location where the gap is large, it is not necessary to strictly manage the gap between the plate materials.

  Further, in the present invention, since there is a gap between the plate materials, no blowhole is generated in the welded portion when the surface-treated metal plate materials such as galvanizing are joined by laser welding.

  In the present invention, the welding start point uses a metal plate whose gap is smaller than the welding trajectory toward the welding end point thereafter, so that unwelding caused by the large gap can be reduced.

Embodiments according to the present invention will be described below with reference to the drawings.
<First Embodiment>
The laser welding method according to the first embodiment of the present invention is shown in FIGS.

  As shown in FIG. 1, the laser welding equipment includes a robot hand 11 driven by a six-axis motor, an optical head 12 attached to the tip of the robot hand 11, and a laser oscillator 10 of a YAG laser. 12 is connected to the laser oscillator 10 by an optical fiber cable, and has a structure in which a long-focus laser beam 1 is emitted from the optical head 12. Further, an optical deflection optical system 13 (scanner) for deflecting the emitting direction of the laser beam 1 is provided inside the optical head 12, whereby the laser beam 1 is scanned along a predetermined welding locus and welded. The pattern is drawn. Moreover, the laser welding equipment includes a clamping means 14 that clamps two metal steel plates as workpieces so that a gap is formed.

  The type of laser used here is a YAG laser, but it may be a carbon dioxide laser. An inert gas such as Ar or He can also be used as the assist gas. Further, as a basic welding method, a remote laser welding method capable of instantaneously moving the laser beam 1 will be described below, but the present invention is not necessarily limited to the remote laser welding method.

  FIG. 2 shows laser welding by irradiating a workpiece obtained by superimposing and clamping the steel plates 2 and 3 galvanized as two metal plates with the clamping means 14 with the laser beam 1. It shows how they are doing.

  Further, FIG. 2 shows that when two steel plates 2 and 3 to be welded are overlapped and clamped, one steel plate 2 comes into contact with the other steel plate 3 and gradually increases from the contact portion 5. 4 shows a state generated between the steel plates 2 and 3. The laser beam 1 moves (scans) a portion where the gap 4 is generated from the two steel plates 2 and 3 overlapped in this way from the smaller one of the gaps 4 to the larger one. Thus, the steel plates 2 and 3 are laser welded. In FIG. 2, the laser beam 1 is always scanned from the smaller one of the gaps 4 to the larger one to create a weld bead having a linear welding locus 6.

  Here, the condition of moving the laser beam 1 from the smaller one of the gaps 4 between the two steel plates 2 and 3 toward the larger one is that the welding direction at the time of starting laser welding (the welding start point 6a). After laser welding is started, the gap 4 may be welded in a direction from small to large as a whole. In laser welding, since there is no melted portion at the welding start point 6a, cracks are likely to occur, and since there is no melted portion at the welding end point 6b, depressions and defects are likely to occur. However, in the course from the welding start point 6a to the welding end point 6b, there is a melted part around the laser irradiation position, and this promotes the melting of the adjacent part while flowing out. Is done. Therefore, after the laser welding is started, the laser beam 1 passes through a path (gap 4 is large to small) in the middle of the welding trajectory 6, for example, where the magnitude relationship of the gap 4 is locally reversed. Even so, good quality welding is ensured.

  Therefore, when there is a size relationship between the gaps 4 between the steel plates in the part to be laser welded, a welding start point is set at the smaller one of the gaps 4 between the steel plates, and the gap 4 is small as a whole. Welding is performed by scanning the laser beam 1 toward the larger side. In FIG. 1, laser welding is performed by linearly scanning the laser beam 1 with the gap 4 from small to large. Thereby, for example, when the laser beam 1 is scanned from the large to the small gap 4, good welding is performed even at a location of the large gap 4 where welding cannot be performed.

  Specifically, in the case of a steel plate, laser welding can be performed satisfactorily in a range where the gap 4 is as small as 0.3 mm or less, but if the gap 4 exceeds 0.3 mm, it is not welded even if the laser beam 1 is irradiated. Thus, laser welding cannot be performed. However, according to the present invention, when the laser beam 1 is scanned from the small gap 4 toward the large gap, welding occurs even if the gap 4 is a portion where there is a large gap 4 of more than 0.3 mm to 1 mm. Thus, it was confirmed that good laser welding was performed.

As a method of forming the gap 4, FIG. 2 has been described as a case where the gap 4 is unintentionally formed as a result of overlapping and clamping the two steel plates 2 and 3. It may be a case where two steel plates 2 and 3 are overlapped and clamped so that a gap 4 is formed therebetween. That is, a structure in which an interfering portion (contact portion) and a gap 4 are generated at the same time in the overlapped portion of the two steel plates 2 and 3 to be laser welded, and the portion where the gap 4 is generated is defined as the gap 4. Even if laser welding is performed from the smaller one to the larger one, the same effect as described above can be obtained.
<Second Embodiment>
FIG. 3 shows a laser welding method according to the second embodiment of the present invention. This is a case where laser welding is performed by irradiating the laser beam 1 along a welding locus that is in a loop shape from the welding start point to the welding end point and where the welding start point and the welding end point do not overlap. Examples of welding trajectories that are loop-shaped and in which the welding start point and the welding end point do not overlap are welding trajectories such as a C shape, an S shape, and a round shape. Form a weld bead. The reason why the welding start point and the welding end point are not overlapped is that if they overlap, they may melt and open holes. Then, when forming such a weld bead, the orientation of the welding locus within the welding surface is set so that the welding start point of the welding locus always starts from the smaller gap 4 between the steel plates.

  This will be specifically described. FIG. 3A shows an example in which a weld bead having a C-shaped welding locus 7 is formed. In FIG. 3A, the C-shaped opening 7 A of the gap 4 is formed so that the welding start point 7 a of the C-shaped welding locus 7 starts from the smaller gap 4 between the two steel plates 2 and 3. The direction of the C-shaped welding locus 7 in the welding surface is set so as to face the smaller side (left side of FIG. 3A). The second half of the C-shaped welding locus 7 is directed from the larger gap 4 to the smaller one, and the welding end point 7b is located at substantially the same level as the welding start point 7a. Since there is a melted part around, a good quality weld bead is formed. Therefore, even when the C-shaped crown portion 7B is located in a place where the gap 4 is large, welding is performed satisfactorily.

  FIG. 3B shows an example in which a weld bead having an S-shaped welding locus 8 is formed. In FIG. 3 (b), one rounded portion 8 A of the S-shaped welding locus 8 has the smaller gap 4 so that the welding start point 8 a of the S-shaped welding locus 8 starts from the smaller gap 4. (On the left side of FIG. 3 (b)), and the other rounded portion 8B is located on the welding surface of the S-shaped welding locus 8 so that the other rounded portion 8B is positioned on the larger gap 4 (right side of FIG. 3 (b)) Set the orientation at. In this case, the welding start point 8a of the S-shaped welding trajectory 8 is microscopically directed toward the smaller gap 4, but when viewed from the entire S-shape, the S is directed from the smaller gap 4 toward the larger one. It will be understood that the letter-shaped welding trajectory 8 has changed. In addition, the welding end point 8b of the S-shaped welding locus 8 is located on the larger side of the gap 4.

According to this embodiment, even if it is difficult to move the welding position due to the shape relationship between the optical head 12 and the part, it is possible to weld a portion having a more optimal steel plate gap.
<Third Embodiment>
FIG. 4 shows a specific example as the third embodiment of the present invention. First, as shown in FIG. 4 (a) or FIG. 4 (b), the gap 4a or the gap 4b is formed between the two steel plates 2 and 3 having the bent portion 20 with a step height of 0.5 mm to 0.1 mm. Overlay as much as possible. 4 (a) and 4 (b), the difference in level between the two steel plates 2 and the bent portion 20 of the steel plate 3 is different. In FIG. 4 (a), there is a gap 4a on the lower side of the bent portion 20. As a result, a gap 4b is formed on the upper side of the bent portion 20 in FIG. After that, when both ends of the part to be welded are clamped from above and below with the gauge 21 and the clamp member 22 which are the clamping means 14, the state shown in FIG. FIG. 5 is an enlarged view of a part of FIG. 4C. Two pieces are obtained by clamping from above and below with the main gauge 21a, the sub gauge 21b, and the clamp member 22 driven by the air cylinder 23. Between the steel plates 2 and 3, there is a gap 4 that extends from the vicinity of the clamp location to the space 24 by the bent portion 20.

  The laser beam 1 is irradiated to a portion where the gap 4 between the clamped two steel plates 2 and 3 is generated, and the laser beam 1 is moved in a direction away from the side closer to the clamped portion to perform laser welding. Thereby, the unwelding produced | generated by the clearance gap 4 being large can be reduced.

  Therefore, the following advantages can be obtained. (1) A small amount of gap can be made relatively stable by rough parts management. (2) Since the parts management is rough, the management cost can be reduced. (3) A gap can be created in the same way regardless of the height difference between the upper and lower plates.

Further, although there is always a variation in dimensional accuracy in the steel plate panel, an appropriate gap can always be secured by clamping the portion where the height of the bent portion 20 varies using the variation. Further, by providing the bent portion 20 having a high variation element, it is possible to always interfere with only a part of the overlapping portion and avoid interference of the entire surface. Furthermore, as a method of creating the gap 4, the conventional method of providing embossment only on one side in the vicinity of the welding point may not allow the gap 4 to be produced with good height, but according to the present embodiment, without such difficulty. A gap 4 can be created.
<Fourth Embodiment>
A specific fourth embodiment of the present invention is shown in FIG. here,
First, the two steel plates 2 and 3 with the standing flange 26 are overlapped so that a gap 4 is formed as shown in FIG. As a premise, in order to obtain a part shape for forming the gap 4 in advance, the curved surface 28 is formed at an angle of about 2 to 5 degrees at the corner from the flat part 27 to the standing flange 26 in a single part state. And it is comprised so that the front-end | tips of the standing flange 26 may mutually contact and be adapted by the elasticity of the steel plates 2 and 3 in the state which overlapped and positioned as shown to Fig.6 (a). In this example, the curvature of the curved surface 28 is different between the two steel plates 2 and 3, and the gap 4 formed by being sandwiched between the curved surface 28 and the curved surface 28 extends from the maximum space portion 25 to the end of the standing flange 26. It is formed in a shape that gradually decreases toward the flat portion 27 and the flat portion.

  After that, when the standing flange 26 is clamped from the outside and the inside by the gauge 21 and the clamp member 22 which are the clamping means 14, the state shown in FIG.

  The laser beam 1 is irradiated to the portion where the gap 4 between the clamped two steel plates 2 and 3 is generated, and the laser beam 1 is directed away from the side closer to the clamped portion as described in FIG. It is moved to form a weld bead with a welding locus such as a C shape, an S shape, or a round shape. FIG. 6A shows a state in which a weld bead is formed by a C-shaped welding locus 7.

According to this laser welding method, it is possible to reduce unwelding caused by the large gap 4. Further, it is possible to easily form at least one or more stable gaps 4 required for welding on the cross section.
<Fifth Embodiment>
FIG. 7 shows a fifth embodiment of the present invention. This is because the lower gauge 30 and the upper clamp member 32 driven by the air cylinder 31 clamp the two steel plates 2 and 3 as workpieces from above and below, and the two clamped steel plates An example is shown in which laser beam 1 is irradiated to a portion where gaps 4 and 3 are generated, and laser welding is performed by moving laser beam 1 in a direction away from a portion closer to the clamped portion.

  The laser beam 1 used for remote laser welding has a long focal length of 600 to 1000 mm, for example. For this reason, when a laser beam leaks, it damages by irradiating the gauge 21 of a jig | tool, a post | mailbox, and peripheral equipment.

  Therefore, in this embodiment, as viewed in the irradiation direction of the laser beam 1, a light shielding plate for blocking the leaked laser light on the back side of the two steel plates 2, 3 as the workpiece, that is, on the back side of the welded part. 33 is provided. By providing the light shielding plate 33 in this way, it is possible to avoid the inconvenience that the laser light leaked from the back side of the welded part is irradiated and damaged on the gauges, posts and peripheral devices of the jig.

  Although the case where two steel plates are laser-welded has been described in the above embodiment, the present invention can be applied to the case where three or more steel plates are laser-welded.

  The present invention can be used for laser welding.

It is the schematic which showed the relationship between the laser welding equipment in this invention, and the two steel plates piled up as a workpiece | work. It is a figure which shows the laser welding method which concerns on the 1st Embodiment of this invention. The laser welding method which concerns on the 2nd Embodiment of this invention is shown, (a) is a figure which shows a C-shaped welding locus | trajectory, (b) is a figure which shows an S-shaped welding locus | trajectory. The laser welding method which concerns on the 3rd Embodiment of this invention is shown, (a) is the figure which shows the state which piled up the two steel plates which have a bending part on one side, and (b) on the other side. And (c) is a diagram showing a state after clamping. It is the figure which expanded and showed a part of FIG.4 (c). The laser welding method which concerns on the 4th Embodiment of this invention is shown, (a) is a figure which shows a superposition state, (b) is a figure which shows a clamp state. It is a perspective view which shows the laser welding method which concerns on the 5th Embodiment of this invention.

Explanation of symbols

1 laser beam,
2, 3 steel plate,
4, 4a, 4b gap,
5 contact points,
6 Linear welding trajectory,
6a Welding start point,
6b Welding end point,
7 C-shaped welding trajectory,
7A opening,
7B Crown part,
7a Welding start point,
7b Welding end point,
8 S-shaped welding trajectory,
8A One round part,
8B The other round part,
8a Welding start point,
10 Laser oscillator,
11 Robot hand,
12 optical heads,
13 Optical deflection optical system,
14 Clamping means,
20 bent part,
21 gauge,
21a Main gauge,
21b sub-gauge,
22 Clamp member,
23 Air cylinder,
24 space part,
25 maximum space,
26 Standing flange,
27 flat part,
28 curved surface,
30 gauge,
31 air cylinder,
32 Clamp member,
33 Shading plate.

Claims (11)

  A laser welding method, wherein a laser beam is moved from a smaller gap to a larger gap between stacked metal plate members to laser weld the plate members.   The plate material is overlapped so that a gap between both plate materials gradually increases from a contact point where one plate material contacts the other plate material, and the laser beam is irradiated to a portion where the gap is generated, and the gap is generated. 2. The laser welding method according to claim 1, wherein laser welding is performed by moving the laser beam from a smaller one to a larger one. The plate material having a bent portion with a step as the plate material is overlapped and clamped so that a gap is formed,
2. The laser welding method according to claim 1, wherein the laser beam is moved by moving the laser beam in a direction away from a portion closer to the clamped portion in a portion where a gap between the clamped plate materials is generated. . The laser welding is performed by welding by irradiating a laser beam along a welding locus that is in a loop shape from a welding start point to a welding end point and the welding start point and the welding end point do not overlap,
4. The laser welding method according to claim 1, wherein the laser beam is guided so that a welding start point of the welding locus always starts from a smaller gap between the plate members.   The laser welding method according to claim 4, wherein the welding locus that is loop-shaped and does not overlap the welding start point and the welding end point is a welding locus such as a C shape, an S shape, or a round shape. .   6. The laser welding according to claim 1, wherein the laser welding is remote laser welding in which a long-focus laser beam is deflected by an optical deflection optical system and guided along the welding locus. Method. Clamping means for clamping the metal plate material so as to create a gap;
A laser device for irradiating a laser beam in a direction away from a side closer to the clamped location in order to weld the plate material that is superimposed and clamped by the clamping means;
A laser welding apparatus comprising: Clamp means that clamps metal plate materials so that there is a gap between them,
A laser device for irradiating a laser beam in a direction away from a side closer to the clamp location in order to weld the plate material that is superimposed and clamped by the clamp means;
The laser device includes a laser oscillator, an optical head connected to the laser oscillator by an optical fiber and having a built-in optical deflection optical system for deflecting a laser beam emission direction, and a robot hand equipped with the optical head;
The laser welding equipment characterized by having.   A metal plate having a welding locus that is continuously laser-welded by forming a gap between the stacked metal plates, and at least the welding start point is smaller than the welding locus toward the welding end point thereafter. The metal plate characterized by becoming.   The metal plate according to claim 9, wherein the continuous laser welded welding locus has a loop shape from a welding start point to a welding end point and a shape in which the welding start point and the welding end point do not overlap.   11. The metal plate according to claim 10, wherein a welding locus in which the loop shape and the welding start point and the welding completion point do not overlap is a welding miracle such as a C shape, an S shape, or a round shape.

Images