JP2008290083A - Method and apparatus for lap laser welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for lap laser welding, by which method and apparatus, the generation of large weld cracks can be suppressed by suppressing the propagation of minute weld cracks, which are caused in a bead, in welding directions. <P>SOLUTION: A welding torch irradiates a two-plate overlapped workpiece W with a laser beam B. A welding operation is carried out while swinging the welding torch toward right and left with respect to welding direction F making the irradiation point of the workpiece W as a center. The bead 6 is varied so as to continuously change its tilting angle from a rightward tilting state 6A to a leftward tilting state 6C via a vertical state 6B in a plane perpendicular to the welding direction F, and further so as to change its tilting angle in the reversed order. Therefore, the bead 6 continues in the welding direction F while waving with a required cycle. As a result, even if minute weld cracks have been generated in the bead 6, the propagation of the weld cracks is suppressed halfway, and the minute weld cracks do not grow to large weld cracks. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an overlap laser welding method and apparatus for performing welding by irradiating a plurality of stacked workpieces with a laser beam.

  Conventionally, lap laser welding is generally performed by irradiating a circular beam perpendicularly to the plate surface of the workpiece, but recently, for the purpose of preventing the occurrence of welding defects such as weld cracks and blowholes, Irradiating a laser beam in an elliptical shape to a work is also performed (see, for example, Patent Document 1).

  By the way, the weld crack which generate | occur | produces in a bead often propagates to a bead longitudinal direction (welding direction), and the crack which generate | occur | produced in one place develops into a big crack, and becomes a fatal defect in many cases. In particular, when the overlapped portion of the workpiece flange portion is overlapped and welded along the edge (flange end), a large weld crack is likely to occur. This is presumed that deformation (strain) occurred on the edge end side due to insufficient rigidity and a large tensile stress was generated in the bead due to this, but an effective welding method for preventing such weld cracking is The current situation is still missing.

JP-A-6-190575 (FIG. 1, [0019])

  The present invention has been made in view of the technical background described above, and the problem is to suppress the propagation of minute weld cracks generated in the beads in the welding direction, thereby suppressing the occurrence of large weld cracks. It is an object of the present invention to provide a method and apparatus for lap laser welding that can be used.

  In order to solve the above-mentioned problems, the lap laser welding method according to the present invention provides a welding direction while vibrating a laser beam in a plane orthogonal to the welding direction when performing welding by irradiating a plurality of stacked workpieces with a laser beam. Scanning.

  By oscillating the laser beam in a plane perpendicular to the welding direction in this way, the bead is formed in a non-linear shape in the welding direction, and even if a minute weld crack occurs in the bead, its propagation is suppressed. , Does not develop into a big crack.

In the present invention, the number of stacked workpieces is arbitrary, and may be two or three. The material type of the workpiece is also arbitrary, and may be an iron-based material or a non-ferrous material such as an aluminum alloy. Further, the scanning of the laser beam in the welding direction may be performed by moving the welding torch while fixing the position of the workpiece or by moving the workpiece while fixing the position of the welding torch.
In the following, some aspects of the present invention will be illustrated and described.

  (1) In a lap laser welding method in which welding is performed by irradiating a plurality of stacked workpieces with a laser beam, the laser beam is scanned in the welding direction while vibrating in a plane orthogonal to the welding direction, and the beads are cycled. A method of laminating laser welding, characterized in that the laser beam is amplified with a laser beam.

  By amplifying the bead in a predetermined cycle as described in the item (1), even if a minute weld crack is generated in the bead, the propagation is suppressed in the middle, and it does not develop into a large crack. .

  (2) The lap laser welding method according to item (1), wherein the laser beam is scanned in the welding direction while swinging in the left-right direction around the irradiation point on the workpiece.

  (3) The lap laser welding method according to (1), wherein the laser beam is scanned in the welding direction while swinging in the left-right direction about a point above the workpiece.

  By oscillating the laser beam as described in this item (2) or (3), the bead is given undulation, and even if a minute weld crack occurs in the bead, its propagation is suppressed halfway. , It will not develop into a big crack. In addition, since the bead is formed to be inclined in a plane perpendicular to the welding direction, the tensile force acting on the final solidification line of the bead is relaxed, and the occurrence of the weld crack itself is suppressed. Become.

  (4) The lap laser welding method according to (1), wherein the laser beam is irradiated perpendicularly to the work plate surface and scanned in the welding direction while being translated in the left-right direction.

  By moving the laser beam in the left-right direction as described in this item (4), the bead can be formed into a waveform, and even if a minute weld crack is generated in the bead, its propagation is halfway. It will be suppressed and will not develop into a large crack. Further, since the laser beam is irradiated perpendicularly to the work plate surface, the movement of the laser beam becomes simple, and the mechanism for moving the laser beam can be simplified.

  (5) In a lap laser welding apparatus that performs welding by irradiating a plurality of stacked workpieces with a laser beam from a welding torch and moving the workpiece and the welding torch relative to each other, the welding torch is centered on an irradiation point for the workpiece A lap laser welding apparatus, wherein the welding torch is oscillated in accordance with the relative movement.

  (6) In a lap laser welding apparatus for performing welding by irradiating a plurality of stacked workpieces with a laser beam from a welding torch and moving the workpiece and the welding torch relative to each other, the welding torch is placed at one point above the workpiece. A lap laser welding apparatus, characterized in that it is arranged at the center so as to be swingable in the left-right direction and swings the welding torch according to the relative movement.

  The lap laser welding apparatus described in (5) is directed to the implementation of the method described in (2) above, and the lap laser welding apparatus described in (6) is directed to the implementation of the method described in (3) above. Thus, the bead can be easily given undulation by swinging the welding torch about the irradiation point or swinging about one point above the workpiece.

  (7) In a lap laser welding apparatus for performing welding by irradiating a plurality of stacked workpieces with a laser beam vertically from a welding torch and moving the workpiece and the welding torch relative to each other, the welding torch is moved in the horizontal direction with respect to the welding direction. A lap laser welding apparatus, wherein the welding torch is reciprocated in accordance with the relative movement.

  The overlap laser welding apparatus described in the item (7) is directed to the implementation of the method described in the item (4), and the bead can be formed into a waveform by reciprocating the welding torch in parallel.

  According to the lap laser welding method and apparatus according to the present invention, since the propagation of minute weld cracks generated in the bead in the welding direction is suppressed, it does not develop into a large weld crack, and particularly a weld crack occurs. It is useful for lap laser welding along the edges of easy workpieces.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a lap laser welding apparatus as a first embodiment of the present invention. In the figure, 1 is a clamp unit that supports two thin steel plates (workpieces) W in an overlapped state, and 2 is a swingable support for a welding torch 3 that irradiates a laser beam B toward the workpiece W. The torch support unit 2 is configured to linearly move (relatively move) in a direction perpendicular to the paper surface with respect to the workpiece W supported by the clamp unit 1 by a moving means (not shown).

  The torch support unit 2 is provided with a guide groove 5 for slidably guiding a guide member 4 attached to the base end portion of the welding torch 3. The bending radius of the guide groove 5 is set so that the welding torch 3 can be swung (vibrated) around the irradiation point P with respect to the workpiece W. The torch support unit 2 is provided with a turning drive means (not shown) for reciprocating the guide member 4 in the guide groove 5. The welding torch 3 stands upright with respect to the workpiece W by the turning drive means. With this posture as a neutral position, it can be swung in the left-right direction within a predetermined angle range around the irradiation point P. Here, the welding torch 3 is controlled to swing at a predetermined speed in synchronization with the linear movement of the torch support unit 2. In this case, the turning drive means may be feedback-controlled based on the linear moving speed of the torch support unit 2.

Hereinafter, the lap laser welding method by this apparatus is demonstrated with reference also to FIG.
At the time of welding, after the workpiece W is supported on the clamp unit 1 in a stacked state, the laser beam B is emitted from the welding torch 3, the torch support unit 2 is moved linearly, and the welding torch 3 is further swung. Then, a bead 6 penetrating up and down is formed in the overlapping portion of the upper and lower two workpieces W, and the upper and lower two workpieces 1 are continuously overlapped and welded via the bead 6. At this time, the welding torch 3 swings around the irradiation point P, so that the bead 6 moves from the right inclined state 6A through the vertical state 6B to the left inclined state 6C within the plane orthogonal to the welding direction F, The inclination angle is continuously changed in the reverse direction. In this case, since the irradiation point P is constant on the front surface side of the workpiece W, the bead 6 is formed in a substantially linear shape in the welding direction F. However, on the back surface side of the workpiece W, the inclination angle of the bead 6 is continuous. The bead 6 is formed in the waveform as shown in FIG.

  In other words, in the first embodiment, even if the bead 6 continues in the welding direction F while undulating (amplitude) in a predetermined cycle, even if a minute weld crack occurs in the bead 6, the propagation thereof Will be suppressed in the middle and will not develop into large cracks.

Particularly in the first embodiment, since most of the beads 6 are inclined in the plate thickness direction, as shown in FIG. 4, for example, deformation (distortion) occurs on the flange end side due to insufficient rigidity, Even if a large tensile stress F in the direction parallel to the mating surface is generated in the bead 6 by this deformation, the tensile force F _C acting perpendicularly to the final solidification line C becomes a vertical component of the tensile stress F. Therefore, the tensile force Fc acting on the final solidification line C is sufficiently smaller than the tensile stress F, and as a result, the occurrence of the weld crack itself in the bead 6 is suppressed. Therefore, the first embodiment is particularly useful for lap laser welding along the edge of a workpiece where weld cracking is likely to occur.

  FIG. 5 shows a lap laser welding apparatus as a second embodiment of the present invention. Since the overall configuration is the same as that of the first embodiment, the same parts as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. The feature of the second embodiment is that the welding torch 3 is supported by the torch support unit 2 so as to be swingable around a pin 10 attached to the base end portion thereof. The support point of the pin 10 is set on an axis L perpendicular to the plate surface of the workpiece W. The torch support unit 2 is provided with rotational drive means (not shown) for rotating the pin 10 in the left-right direction, and the welding torch 3 is placed in a neutral position with respect to the workpiece W by the rotational drive means. As described above, the pin 10 can swing in the left-right direction within a predetermined angle range.

  In the lap laser welding method using this apparatus, while the laser beam B is emitted from the welding torch 3, the torch support unit 2 is linearly moved and the welding torch 3 is further swung. Then, as in the first embodiment, the bead that continuously changes the inclination angle in the plane perpendicular to the welding direction F is provided in the overlapping portion of the upper and lower workpieces W in the same manner as shown in FIG. 6 (6A to C) are formed. Therefore, in this case as well, even if the bead 6 continues in the welding direction F while undulating (with amplitude) in the same manner as in the first embodiment, even if a minute weld crack occurs in the bead 6. , Its propagation is suppressed in the middle and it will not develop into a big crack. Further, the tensile force Fc acting on the final solidification line C is also reduced, and the occurrence of the weld crack itself in the bead 6 is suppressed. Particularly in the second embodiment, since the welding torch 3 swings about one point (pin 10) above the workpiece W, a corrugated bead 6 is formed on the upper surface side of the workpiece W, and the entire area of the workpiece W is Thus, the bead 6 is given swell and the propagation of the weld crack is more reliably suppressed.

  FIG. 6 shows a lap laser welding apparatus as a third embodiment of the present invention. Since the overall configuration is the same as that of the first embodiment, the same parts as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. The third embodiment is characterized in that the guide groove 5 provided in the torch support unit 2 is linear, and the guide member 4 attached to the base end portion of the welding torch 3 is the linear guide groove. 5 slidable along the shape. The torch support unit 2 is provided with linear drive means (not shown) for reciprocating the guide member 4 in the left-right direction, and the welding torch 3 is in an upright posture with respect to the workpiece W by the linear drive means. While maintaining, it can be translated in the left-right direction.

  In the lap laser welding by this apparatus, while the laser beam B is emitted from the welding torch 3, the torch support unit 2 is linearly moved, and the welding torch 3 is reciprocated (translated). Then, as shown in FIG. 7, the bead 6 is formed in a zigzag shape (tooth shape) in the overlapped portion of the upper and lower two workpieces W, thereby causing minute weld cracks in the bead 6. However, the propagation is suppressed in the middle and it does not develop into a large crack. In the third embodiment, since the welding torch 3 is merely moved in parallel, the mechanism for moving the welding torch 3 becomes simple, and simplification of the torch support unit 2 can be achieved.

  Here, in the third embodiment, when the moving means of the torch support unit 2 is controlled and the torch support unit 2, that is, the welding torch 3 is intermittently moved relative to the workpiece W, it is shown in FIG. Thus, the bead 6 is formed in a crank shape, and also in this case, propagation of weld cracks is suppressed.

  In the present invention, the welding torch 3 is moved relative to the workpiece W without vibrating in a plane perpendicular to the welding direction F, and the laser beam B is intermittently emitted from the welding torch 3 during the relative movement. It may be made to let it be. In this case, as shown in FIG. 9, the bead 6 is formed in a short stitch shape, but even in this case, there is an effect in suppressing propagation of weld cracks.

It is a schematic diagram which shows the structure of the overlap laser welding apparatus as the 1st Embodiment of this invention. It is a schematic diagram which shows the implementation condition of the overlap laser welding by the apparatus as the 1st embodiment. It is sectional drawing which shows the formation state of the bead on the back surface side of the workpiece | work by the 1st embodiment. It is explanatory drawing which shows the magnitude | size of the tensile force which acts on the bead by the 1st embodiment. It is a schematic diagram which shows the structure of the overlap laser welding apparatus as the 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the overlap laser welding apparatus as the 3rd Embodiment of this invention. It is a top view which shows the formation state of the bead by the apparatus as a 3rd embodiment. It is a top view which shows the formation state of another bead by the apparatus as the 3rd embodiment. It is a top view which shows the formation state of the bead by the deformation | transformation embodiment of this invention.

Explanation of symbols

1 Clamp Unit 2 Torch Support Unit 3 Welding Torch 4 Guide Member 5 Guide Groove 6 Bead 10 Pin (Oscillation Center)
B Laser beam F Welding direction P Irradiation point

Claims (7)

  In a lap laser welding method in which welding is performed by irradiating a plurality of workpieces with a laser beam, the laser beam is scanned in the welding direction while vibrating in a plane orthogonal to the welding direction, and the beads are oscillated in a predetermined cycle. A lap laser welding method characterized by the above.   The lap laser welding method according to claim 1, wherein the laser beam is scanned in the welding direction while swinging in the left-right direction about the irradiation point on the workpiece.   The lap laser welding method according to claim 1, wherein the laser beam is scanned in the welding direction while swinging in the left-right direction about a point above the workpiece.   The lap laser welding method according to claim 1, wherein the laser beam is irradiated perpendicularly to the work plate surface and scanned in the welding direction while being translated in the left-right direction.   In a multi-layer laser welding apparatus that performs welding by irradiating a plurality of stacked workpieces with a laser beam from a welding torch and moving the workpiece and the welding torch relative to each other, the welding torch is moved in a horizontal direction around an irradiation point with respect to the workpiece. A lap laser welding apparatus, wherein the welding torch is rocked in accordance with the relative movement.   In a lap laser welding apparatus for performing welding by irradiating a plurality of stacked workpieces with a laser beam from a welding torch and moving the workpiece and the welding torch relative to each other, the welding torch is moved left and right around a point above the workpiece. A lap laser welding apparatus, wherein the welding torch is oscillated in accordance with the relative movement.   In a multi-layer laser welding apparatus that performs welding by irradiating a plurality of stacked workpieces with a laser beam vertically from a welding torch and moving the workpiece and the welding torch relative to each other, the welding torch is translated in the horizontal direction with respect to the welding direction. A lap laser welding apparatus, which is arranged so as to reciprocate the welding torch according to the relative movement.