JP2007014974A - Laser welding method and laser welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser welding technology of a plated steel plate or the like capable of obtaining the excellent welding quality according to the condition of a gap attributable to the shape dispersion of individual steel plates, and eliminating the repair and corrective man-hour and the delay of the line tact which have been essential in a conventional practice. <P>SOLUTION: When panel components W1, W2 formed of galvanized steel plates overlap each other and are welded by irradiating laser beams L, a part in a vicinity of the laser beam irradiation position P is pressed and straightened by a pressurization pin 11 so as to ensure a very small gap between the components W1, W2. At the same time, the welding state is monitored on the real-time basis by the plasma monitoring system to determine presence/absence of any change of the welding state. According to the result of determination of the presence/absence, a deflecting plate 12 interposed in an optical system is adequately turned to change the offset quantity M formed between the laser beam irradiation position P as the welding condition and the pressurization and straightening position by the pressurization pin 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser welding method and a laser welding apparatus for a plate material surface-treated by a coating layer that generates gas by heating, particularly a plate material represented by a galvanized steel plate used as a vehicle body panel material of an automobile, and more Specifically, when applying continuous welding by laser beam irradiation with at least two plates stacked, pressurizing and correcting the vicinity of the laser beam irradiation position to ensure a minute gap between the plates as a measure against porosity Thus, the present invention relates to a laser welding method and a laser welding apparatus which monitor a welding state in real time.

  When two or more steel sheets including plated steel sheets are overlapped and continuous welding is performed by laser light irradiation, the plating layer on the steel sheet surface evaporates and becomes gas due to heat during welding, and this becomes a porosity (in the weld metal) in the beads. It is known that the strength of the welded portion is reduced by remaining as a small group of blowholes.

As a measure to suppress this porosity, it is also known that it is effective to positively provide a gap between the steel plates and discharge the bubbles generated during welding to the outside, but if the gap is too large Since the steel plates do not weld to each other and so-called unwelding occurs as a welding defect, for example, as described in Patent Document 1, a protrusion is formed on one of the steel plates in advance, while pressure correction treatment such as a pin or a roller is performed. The gap between the steel plates is managed to an appropriate size by using the tool together and bringing the protruding portion into contact with the other steel plate. In some cases, the welding quality is also managed by a welding quality inspection device as described in Patent Document 2.
JP 2001-162388 A Japanese Patent Laid-Open No. 10-6051

  However, for example, in the case of a complex three-dimensional panel component that will form a part of the body of an automobile, the same part may be different even in the same part due to variations in the shape of the panel component itself or shape changes due to accumulation during the assembly process. However, in order to maintain an appropriate gap size that does not cause porosity or unwelding, the size of the gap must be determined for each panel component and used with a pressure correction jig. It is necessary to adjust the correction force, which is not practical considering the complexity of the structure of the pressure correction jig or the complexity of the procedure.

  In particular, in a mass production line in which the welding operation itself is automated, it is impossible to grasp a minute gap each time. For example, a welding quality inspection device as described in Patent Document 2 or a visual inspection is used to detect a defective welding portion. In addition, it is also possible to correct (rework) a welding defect site by, for example, MIG welding in a subsequent process.

  However, rework correction work such as MIG welding is not only easy to cause a decrease in bead quality due to partial welding, but the cost is increased due to the increase in the total man-hours and the number of processes due to the occurrence of rework work. It is not preferable because productivity is lowered due to a delay in (tact time).

  The present invention has been made paying attention to such a problem, and in particular, it ensures that an appropriate gap is obtained according to the variation in the shape of each steel sheet, so that good welding quality can be obtained. It is an object of the present invention to provide a laser welding method and a laser welding apparatus capable of eliminating the rework correction man-hours and line tact delays.

  In the invention according to claim 1, when at least two plate materials including a plate material surface-treated with a coating layer that generates gas by heating are overlapped with each other and subjected to continuous welding by laser light irradiation, As a laser welding method in which the vicinity of the laser beam irradiation position is corrected and pressure is corrected in order to ensure a very small gap, the welding state is monitored in real time. The offset amount between the pressure correction position and the pressure correction position is changed.

  In this case, as described in claim 2, a projection is formed in advance in the vicinity of the welded portion by laser light irradiation of any one of the material plates, and this projection contacts the other plate material. In addition, it is desirable to pressurize and correct the welding direction traveling side rather than the laser beam irradiation position. Further, the presence or absence of a change in the welding state during welding is preferably performed based on the result of monitoring the welding state at the laser light irradiation position in real time by a technique such as so-called plasma monitoring as described in claim 3. . More preferably, as described in claim 4, the welding state is monitored in real time to determine whether or not the welding quality is appropriate, while the presence or absence of a change in the welding state during welding is determined separately from the determination of whether or not the welding quality is appropriate. Shall.

  In addition, as described in claim 5, it is more desirable to change the focal position of the laser beam in the plate pressure direction simultaneously with changing the offset amount between the laser beam irradiation position and the pressure correction position.

  The invention according to claim 6 captures the technique according to claim 1 as a laser welding apparatus, and includes at least two plate materials including a plate material surface-treated by a coating layer that generates gas by heating. As a laser welding device that performs continuous welding by laser beam irradiation with overlapping, pressure correction means that pressurizes the vicinity of the laser beam irradiation position in order to ensure a minute gap between the plate materials, and during welding Weld quality inspection means that monitors the welding state in real time and determines whether there is a change in the welding state, and an offset that changes the offset amount between the laser light irradiation position and the pressure correction position according to the change in the welding state during welding And a quantity changing means.

  In particular, in the inventions described in claims 1 and 6, if welding is being performed, for example, plasma light generated when the laser beam melts the plate material or reflected light reflected without being absorbed by the welding quality inspection means. By monitoring, it is possible to determine the presence or absence of changes in the welding state during welding, and based on the knowledge that the state of the gap between the plate materials can be estimated from the result.

  For example, in the case of adopting a plasma monitoring type welding quality inspection means, it is possible to determine the presence or absence of a change in welding state in units of about 0.1 second. It is possible to determine whether or not there is a change in the individual welding state after subdividing. Specifically, it is possible to grasp the process of transition from a normal bead state to a state where non-welding is occurring and a state where porosity is occurring, so a change appears in the welding state. Then, it is possible to immediately change the welding conditions and maintain a normal state.

  Here, factors that can positively control the welding state during welding include the pressure applied by the pressure correction means, the distance between the laser beam irradiation position and the pressure correction position (offset amount), etc. Since an air cylinder or the like is used for pressurization by the pressurizing and correcting means, fine control of the pressurizing force is difficult in controlling the welding quality by adjusting the pressurizing force, and the response of the pressurizing pressure adjustment is poor. Therefore, in the present invention, the offset amount between the laser beam irradiation position and the pressure position by the pressure correction means is used for adjusting the welding conditions based on the change in the welding state.

  Therefore, in at least the first and sixth aspects of the invention, when the welding quality inspection means shows a tendency to determine whether or not there is a change in the welding state, this offset amount is reduced to generate porosity. On the contrary, if the offset amount is increased, if the offset amount is increased, it is possible to maintain a good welded state and hence a good bead quality.

  According to the first and sixth aspects of the invention, the amount of offset between the laser beam irradiation position and the pressure correction position is changed according to the result of the presence / absence determination of the change in the welding state during welding. Even if the gap size changes depending on the shape variation etc., the welding condition can be adjusted after predicting the state of the gap, and as a result, good welding quality is always obtained, and in the past it was essential It will be possible to eliminate rework and man-hours, delays in line tact, etc., and to improve productivity and reduce costs especially on mass production lines.

  FIG. 1 is a schematic explanatory view showing a more specific embodiment of a laser welding apparatus according to the present invention. In this embodiment, a plate material surface-treated with a coating layer that generates gas by heating is used for the body of an automobile. An example is shown in which the panel parts W1 and W2 made of galvanized steel sheets that constitute a part are superposed and then continuously welded as workpieces.

  Here, as shown in FIG. 2, an embossed portion E is formed as a protruding portion at a predetermined pitch in the vicinity of the welded portion in the upper panel component W1 in advance, and prior to laser welding as will be described later. By correcting the pressure so that these embossed portions E are in contact with the lower panel component W2, a gap G having a predetermined size is secured between the two panel components W1 and W2. The size of the gap G is, for example, about 0.4 t when the plate pressure of the panel component W1 is t, and the gap G is 0 in the case of a general automotive body panel component. Set to about 1 to 0.3 mm.

  As shown in FIG. 1, a laser welding machining head 4 is mounted on the tip of a robot arm 1 of a welding robot (not shown) that functions as a welding mother machine via a bracket 2 and a linear slide mechanism 3. Separately, a monitoring device 5 is attached as a welding quality inspection means for determining whether or not there is a change in the welding state during welding as well as determining whether or not the welding state and the bead state immediately after welding are appropriate. Further, the machining head 4 is connected to the piston rod 6a of the pressure cylinder 6 so that the whole machining head 4 is moved in the vertical direction in FIG. Slide displacement is possible.

  The head body 7 of the processing head 4 has a laser optical system including a collimation lens 8 and a focus lens 9 therein, and introduces a laser beam L output from a laser oscillator (not shown) through an optical fiber cable 10. After that, the welding part P on the panel component W1 is irradiated as a focal position. Further, a pressure pin 11 as a pressure correction means is provided at the lower outer periphery of the head body 7. The pressurizing pin 11 is set in advance so as to pressurize and restrain a position offset by a predetermined amount M from the irradiation position P of the laser beam L to the front side in the welding progress direction. Therefore, as shown in FIG. While the pressure pin 11 restrains the pressure so that the gap G formed between the panel parts W1 and W2 has a predetermined size, the irradiation position P of the laser beam L follows the pressure position. It moves and laser welding is performed. As a pressure correction means, it is of course possible to use a pressure roller that is a rotating body instead of the pressure pin 11 described above.

  Between the collimation lens 8 and the focus lens 9 constituting the laser optical system in the head body 7, there is an offset amount M between the irradiation position P of the laser light L and the pressure correction position by the pressure pin 11. A deflection plate 12 is arranged as an offset amount changing means for actively changing the size. As shown in FIG. 3, the deflection plate 12 is rotatably supported by the head body 7 via a shaft 13 and is rotated by a deflection plate driving motor 16 via a pair of gears 14 and 15. It is like that. In the state where the deflecting plate 12 is in a horizontal neutral position as shown in FIG. 1, the incident light beam and the outgoing light beam on the deflecting plate 12 coincide with each other, while the deflecting plate 12 is placed in the horizontal neutral position as shown in FIG. When rotated by a predetermined angle in the counterclockwise direction from the posture, the outgoing light beam L2 is on the traveling side in the welding direction with respect to the incoming light beam L1 on the deflection plate 12 while maintaining the parallel state of the incident light beam L1 and the outgoing light beam L2. Similarly, as shown in FIG. 6, when the deflecting plate 12 is rotated from the horizontal neutral position by a predetermined angle in the clockwise direction, the outgoing light beam L2 with respect to the incident light beam L1 on the deflecting plate 12 is moved in the direction opposite to the welding direction. As a result, the offset amount M between the irradiation position P of the laser beam L and the pressure correction position by the pressure pin 11 is set to change on the panel component W1. The magnitude of the offset amount of the irradiation position P itself of the laser light L changes according to the rotation angle of the deflection plate 12.

  Further, a focusing mechanism 17 is attached to the focus lens 9 in the head body 7 as a focal position changing means. As shown in FIG. 4, the focusing mechanism 17 is configured to screw a lens fixing housing 20 having a screw portion 19 on the outer periphery thereof with a female screw portion 18 on the lower portion of the head body 7 and to fix the lens fixing housing 20. The focus lens 9 is supported on the body 20. A ring gear 21 that functions as a driven gear is fixed to the lens fixing housing 20, and a drive gear 23 on the lens driving motor 22 side fixed to the lens fixing housing 20 is meshed with the ring gear 21. . Thereby, the focus lens 9 is displaced in the optical axis direction according to the forward / reverse operation of the lens fixing housing 20 based on the start of the motor 22, and as a result, as shown in FIG. It changes in the plate pressure direction of W2.

  On the other hand, the monitoring device 5 as welding quality inspection means includes a light receiving part (light receiving sensor) 24 for receiving plasma light generated from the welding part P during welding by laser light irradiation, and a light receiving signal captured by the light receiving part 24, for example. And an analysis device (analysis personal computer) 26 for determining whether or not the welding state has changed, as well as determining whether the welding quality is appropriate from the correlation between the intensity of the plasma light and the welding state. . The light receiving unit 24 is fixedly supported by the head body 7 via the bracket 27 so as to be directed to the irradiation position P of the laser light L on the panel component W1. Then, as will be described later, the deflection plate driving motor 16 or the lens driving motor 22 is driven via the motor control panel 28 in accordance with the result of the presence / absence determination of the change in the welding state in the analysis device 26, resulting in FIG. In addition to the offset amount M, the focal position P1 in FIG. 7 is variably controlled.

  Therefore, according to the laser welding apparatus configured as described above, the laser beam L is irradiated to the welding site P on the panel component W1 as shown in FIG. 1, while the pressure pin 11 is pressed against the panel component W1 to form the panel. The gap G between the parts W1 and W2 is pressure-corrected, and the entire processing head 4 is moved at a predetermined speed while keeping the gap G at an appropriate level. Laser welding is performed while moving the laser beam L so as to follow the correction position. In this case, the pressure correction force exerted by the pressure pin 11 on the panel component W1 is adjusted by the output of the pressure cylinder 6, and the deflection plate 12 of the laser optical system is in a horizontal neutral position as shown in FIG.

  At the same time, the light receiving unit 24 of the monitoring device 5 directed to the irradiation position (welding site) P of the laser beam L continuously detects plasma light generated as welding progresses and reflected light reflected without being absorbed. In addition, the analysis device 26 of the monitoring device 5 determines whether or not the welding quality is appropriate, that is, whether or not the bead state immediately after welding is appropriate according to the intensity of the plasma light captured by the light receiving unit 24, and changes in the welding state during welding. Presence / absence judgment is performed in real time.

  Specifically, in the analysis device 26, it is possible to determine the suitability of the welding quality, for example, in units of about 0.1 seconds as real-time processing, and the bead Be immediately after welding is elongated as shown in FIG. A plurality of areas of about 3 mm in the direction are subdivided into 01 area, 02 area, 03 area, etc., and the suitability of the welding quality for each area is determined. Then, the determination result is visually displayed in the form shown in FIG. 10 on the display unit 29 of the analysis device 26 in real time. Then, if the result of suitability determination is in, for example, “Unwelded & Underfill NG Area” or “Porosity NG Area” in FIG. 10, an alarm is issued, or marking or the like is applied to the corresponding part to cause a welding failure A part is specified and reworked in a later process.

  Apart from this, even if the welded state does not enter, for example, “Unwelded & Underfill NG Area” or “Porosity NG Area” in FIG. 10, unwelded or underfill occurs from the normal bead state (good area). If it is possible to confirm that the welding state or porosity is occurring, that is, if a change different from the actual welding state appears, change the welding conditions to maintain the normal state. Then, as the welding condition, the offset amount M between the irradiation position P of the laser beam L and the pressure correction position by the pressure pin 11 is changed. It should be noted that the state in which unwelding or underfill as described above is occurring or the state in which porosity is being generated can be determined by setting a plurality of thresholds for determining suitability in the analyzer 26.

  More specifically, as shown in FIG. 1, when the deflecting plate 12 is in a horizontal neutral posture and the incident light beam L1 and the outgoing light beam L2 on the deflecting plate 12 coincide with each other, the outgoing light beam L2 With reference to the offset amount M formed between the optical axis and the pressure correction position by the pressure pin 11, it is determined that unwelding or underfill is occurring as a result of the presence / absence determination of the welding state change in the analysis device 26. In this case, the deflecting plate 12 is driven to rotate counterclockwise as shown in FIG. 5 via the motor control board 28 in response to a command from the analyzing device 26, and is emitted with respect to the incident light beam L1 of the deflecting plate 12. By deflecting the light beam L2, the offset amount M is reduced. On the contrary, when it is determined that the porosity is being generated as a result of the presence / absence determination of the welding state change in the analysis device 26, the deflection plate is similarly transmitted via the motor control panel 28 according to a command from the analysis device 26. 12 is rotated in the clockwise direction as shown in FIG. 6 to increase the offset amount M.

  In this way, by actively changing the welding conditions with the offset amount M during the welding operation, it is possible to always maintain the welding state and thus the bead quality appropriately.

  Here, when the laser beam L is deflected by the deflector plate 12 as shown in FIGS. 5 and 6 in order to change the offset amount M as described above, the welding speed is temporarily changed accordingly. There are secondary problems. For example, as shown in FIG. 5, when the irradiation position P of the laser beam L is brought closer to the pressing pin 11 on the front side in the welding progress direction so as to make the offset amount M smaller than the initial amount in FIG. Is temporarily increased, and conversely, as shown in FIG. 6, the pressure pin located on the front side in the welding progress direction of the irradiation position P of the laser beam L in order to make the offset amount M larger than the initial one in FIG. When it is away from 11, the welding speed is temporarily reduced. When the welding speed changes during the welding operation, for example, the panel penetration ability due to the irradiation of the laser beam L also changes, which tends to cause new problems such as panel non-welding.

  FIG. 8 shows the correlation between the welding speed, the focal position, and the panel penetrating ability, and at any welding speed that is appropriate in the state of each focal position P1 in FIGS. In this case, the laser beam L penetrates at least the upper panel component W1, whereas if the welding speed is increased, a welding failure such as partial penetration or non-penetration will occur in any case. ing.

  On the premise of this relationship, for example, if the offset amount M is reduced in the state where unwelding tends to occur as described above, the welding speed is further increased and the panel penetration ability (penetration ability) is lowered. This further promotes the degree of welding. On the other hand, if the offset amount M is increased in a state where the porosity tends to be generated, the welding speed is further decreased and the panel penetration capability (penetration capability) is excessively increased. As a result, the generation of porosity is further promoted. Become.

  Therefore, in order to maintain good welding quality with the state of FIG. 7B as a standard state, the laser beam L is deflected and the offset amount M is changed as described above. In the situation where the welding speed increases in accordance with the change in the offset amount M, the focal position P1 of the laser beam L is shifted downward as shown in FIG. Under such circumstances that the welding speed becomes slow, it is necessary to shift the focal position P1 of the laser beam L upward as shown in FIG.

  Therefore, along with the change of the offset amount M due to the rotation of the deflection plate 12 as described above, the focus position P1 of the laser light L is changed by the focusing mechanism 17 attached to the processing head 4.

  For example, as described above, when it is determined as a result of the presence / absence of a change in the welding state in the analysis device 26 that unwelding or underfill is occurring, motor control is performed according to a command from the analysis device 26. By rotating the deflecting plate 12 counterclockwise as shown in FIG. 5 through the board 28 and deflecting the outgoing light beam 12 with respect to the incident light beam L1 of the deflecting plate 12, the previous offset amount M is reduced. To do. At that time, since the welding speed is temporarily increased with the change in the offset amount M and the panel penetration capability of the laser beam L is reduced, a command is given to the lens driving motor 22 via the motor control panel 28, As shown in FIG. 7, the housing 20 supporting the focus lens 9 is rotationally driven so that the focal position P1 of the laser light L is below the upper surface of the upper panel component W1. Then, when the deflection of the laser beam L by the deflecting plate 12 is finished and the welding speed returns to the original speed, the housing 20 is rotated again, and the focal position P1 of the laser beam L is set to the standard of FIG. Return to the state.

  Since the welding quality is maintained in a good state by changing the focal position P1 in conjunction with such a temporary change of the offset amount M, the presence or absence of a change in the welding state by the analysis device 26 of the monitoring device 5 is determined. As a result, the unwelded state or underfill in FIG. 10 is returned to the good state corresponding to the state in the good area in FIG. 10, and the deflecting plate 12 is returned to the neutral posture in FIG. 1 in this state. .

  At this time, returning the deflecting plate 12 to the neutral position means that the welding speed is temporarily reduced with the change in the offset amount M, and the panel component penetrating ability of the laser beam L is increased. As shown in (c), the housing 20 to which the focus lens 9 is fixed is rotated in the same manner as described above so that the focal position P1 of the laser light L is further above the upper surface of the upper panel component W1. When the deflecting plate 12 returns to the initial neutral posture and the welding speed returns to the initial state, the casing 20 to which the focus lens 9 is fixed is rotated again, and the focal position P1 of the laser light L is rotated. Is returned to the standard state as shown in FIG.

  On the other hand, as described above, when it is determined that the porosity is being generated as a result of the presence / absence determination of the welding state change in the analysis device 26, the motor control panel 28 is passed through a command from the analysis device 26. Then, the deflection plate 12 is rotated in the clockwise direction as shown in FIG. 6 to deflect the outgoing light beam L2 with respect to the incident light beam L1 of the deflection plate 12, thereby increasing the offset amount M. At that time, as the offset amount M changes, the welding speed is temporarily reduced and the panel component penetration capability of the laser light L is increased, so a command is given to the lens driving motor 22 via the motor control panel 28. As shown in FIG. 7C, the housing 20 supporting the focus lens 9 is rotationally driven so that the focal position P1 of the laser light L is above the upper surface of the upper panel component W1. When the deflection of the laser beam L by the deflecting plate 12 is finished and the welding speed returns to the original speed, the housing 20 is rotated again, and the focal position P1 of the laser beam l is set to the standard of FIG. Return to the state.

  Since the welding quality is maintained in a good state by changing the focal position P1 in conjunction with such a temporary change of the offset amount M, the presence or absence of a change in the welding state by the analysis device 26 of the monitoring device 5 is determined. As a result, the porosity shown in FIG. 10 is returned to the good state corresponding to the state in the good area shown in FIG. 10. In this state, the deflecting plate 12 is returned to the neutral posture shown in FIG.

  At this time, returning the deflecting plate 12 to the neutral position means that the welding speed is temporarily increased with the change in the offset amount M and the panel component penetration ability of the laser beam L is lowered. As in (a), the casing 20 to which the focus lens 9 is fixed is rotated in the same manner as described above so that the focal position P1 of the laser light L is further below the upper surface of the upper panel component W1. When the deflecting plate 12 returns to the initial neutral posture and the welding speed returns to the initial state, the casing 20 to which the focus lens 9 is fixed is rotated again, and the focal position P1 of the laser light L is rotated. Is returned to the standard state as shown in FIG.

  As described above, according to the present embodiment, the irradiation position P of the laser beam L on the panel component W1 and the pressure correction position by the pressure pin 11 are determined according to the result of the presence or absence of a change in the welding state by the monitoring device 5. By making the offset amount M to be positively changed and simultaneously changing the focal position P1 of the laser light L in the plate pressure direction, it is possible to always maintain a good welding state.

  Here, although the galvanized steel sheet has been described in the embodiments so far, the present invention can be applied generally to laser welding of a plate material in which a coating layer that generates a gas causing porosity by heating is formed. Of course.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows more concrete embodiment of the laser welding apparatus which concerns on this invention. The A section enlarged view of the panel components in FIG. FIG. 2 is a vertical sectional view centering on a deflection plate in FIG. 1. FIG. 2 is a vertical sectional view centering on a focusing mechanism in FIG. 1. Explanatory drawing which shows the behavior at the time of making small the offset amount in FIG. Explanatory drawing which shows the behavior at the time of enlarging the amount of offsets in FIG. Explanatory drawing at the time of changing the focus position of a laser beam by the plate | board pressure direction of panel components. The characteristic view which shows the correlation with a welding speed, the focus position of a laser beam, and panel component penetration capability. Explanatory drawing at the time of subdividing the bead immediately after welding in a longitudinal direction and determining the suitability. Explanatory drawing which shows the example of a display of the determination result by the monitoring apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Robot arm 4 ... Processing head 5 ... Monitoring apparatus (welding quality inspection means)
7 ... Head body 8 ... Collimation lens 9 ... Focus lens 11 ... Pressure pin (Pressure correction means)
12 ... Deflection plate (deflection means or offset amount change means)
16 ... Deflection plate driving motor 17 ... Focusing mechanism (focal position changing means)
DESCRIPTION OF SYMBOLS 22 ... Lens drive motor 24 ... Light-receiving part 26 ... Analysis apparatus E ... Embossing part (projection part)
G ... Gap L ... Laser beam M ... Offset amount P ... Laser beam irradiation position (welded part)
P1 ... Focus position W1, W2 ... Panel parts (galvanized steel sheet)

Claims (13)

In order to secure a minute gap between the plate materials when performing continuous welding by irradiating the laser beam by superimposing at least two plate materials including the plate material surface-treated by the coating layer that generates gas by heating A laser welding method in which the vicinity of the laser light irradiation position is pressure corrected and the welding state is monitored in real time,
A laser welding method, wherein an offset amount between a laser beam irradiation position and a pressure correction position is changed according to a change in a welding state during welding.   Protrusion is formed in the vicinity of the welded part by laser light irradiation in either one of the plate materials, and the welding direction progression side is pressed from the laser light irradiation position so that this protrusion contacts the other plate material. The laser welding method according to claim 1, wherein correction is performed.   3. The laser welding method according to claim 1, wherein the welding state at the laser beam irradiation position is monitored in real time to determine whether or not the welding state has changed.   4. The laser according to claim 3, wherein the welding state is monitored in real time to determine whether or not the welding quality is appropriate, and the presence or absence of a change in the welding state during welding is determined separately from the determination of whether or not the welding quality is appropriate. Welding method.   The laser welding method according to any one of claims 1 to 4, wherein the focal position of the laser beam is changed in the plate pressure direction simultaneously with changing the offset amount between the laser beam irradiation position and the pressure correction position. . A laser welding apparatus that performs continuous welding by laser beam irradiation by superimposing at least two plate materials including a plate material surface-treated by a coating layer that generates gas by heating,
A pressure correcting means for correcting pressure in the vicinity of the laser light irradiation position in order to secure a minute gap between the plate members;
A welding quality inspection means for monitoring the welding state in real time during welding and determining the presence or absence of a change in the welding state;
An offset amount changing means for changing an offset amount between the laser beam irradiation position and the pressure correction position according to a change in a welding state during welding;
A laser welding apparatus comprising:   Protrusion is formed in the vicinity of the welded part by laser light irradiation in any one of the plate materials, and the pressure correction means has a welding direction more than the laser light irradiation position so that this protrusion is in contact with the other plate material. The laser welding apparatus according to claim 6, wherein the traveling side is pressure-corrected.   The laser welding apparatus according to claim 6 or 7, wherein the welding quality inspection unit is configured to monitor the laser light irradiation position in real time to determine whether or not the welding state has changed.   The welding quality inspection means monitors the welding state in real time to determine whether or not the welding quality is appropriate, and determines whether or not there is a change in the welding state during welding separately from the appropriateness determination of the welding quality. Item 9. A laser welding apparatus according to Item 8.   A focus position changing means is provided for changing the focal position of the laser light in the plate pressure direction in conjunction with changing the offset amount between the laser light irradiation position and the pressure correction position by the offset amount changing means. The laser welding apparatus according to any one of claims 6 to 9.   10. The laser welding apparatus according to claim 6, wherein the offset amount changing means is a deflecting means provided in a part of the laser optical system. 12. The laser welding apparatus according to claim 11, wherein the deflection means is variably controlled in response to the presence or absence of a change in welding state by the welding quality inspection means.   11. The laser welding according to claim 10, wherein the focal position changing means is a motor-driven focusing mechanism that variably controls the focal position in response to the presence / absence of a change in welding state by the welding quality inspection means. apparatus.

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