JP2004090054A - Method and apparatus for laser welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve welding quality by irradiating laser beam to a desired welding point while correcting a gap even when the gap is generated between overlapped workpieces to be jointed. <P>SOLUTION: The laser beam is irradiated along the edge portion of an upper sheet 9 which is one of the two overlapped sheets 7, 9. In the irradiation of laser beam 5, a processing head 3 supported by a robot 3 is moved along the edge portion of the sheet 9, while the overlapped portion of the sheets 7, 9 is pressed by a pressing roller 23 to correct the gap S between the sheets 7, 9. A laser sensor 37 supported by the robot 3 located ahead in the moving direction of the processing head 3 detects the edge portion of the sheet 9, and the processing head 3 is shifted by a linear motor 19 to the lateral direction rectangular to the moving direction so that the laser beam 5 irradiates the detected position as a welding position. The processing head 3 is shifted laterally taking account of the pressed amount by the pressing roller 23 when it corrects the gap S. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser welding method and laser welding in which two workpieces are overlapped with each other and laser welding is performed by irradiating a laser beam while moving a machining head along an edge portion of the overlapped upper side workpiece. Relates to the device.
[0002]
[Prior art]
Conventionally, as a welding method for performing welding while detecting a welding position of a workpiece, for example, there is one described in Japanese Patent Publication No. 6-30814.
[0003]
When detecting the above-mentioned welding position, when two plates are overlapped as a workpiece and laser welding is performed along the edge of the upper plate, the workpiece is particularly three-dimensional like an automotive panel material. When a complicated shape is provided, a gap is likely to be generated between the respective plate materials.
[0004]
[Problems to be solved by the invention]
When gaps are generated between the respective plate materials in this manner, even if the detected welding position is irradiated with laser light, the joint strength between the joint portions of the plate materials is reduced, leading to a reduction in welding quality.
[0005]
In view of the above, an object of the present invention is to improve a welding quality by correcting a gap even if a gap is generated between workpieces stacked on each other and irradiating a desired welding position with a laser beam.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention superimposes two workpieces on each other, and performs laser welding by irradiating a laser beam while moving the machining head along the edge of the upper workpiece. In the laser welding method, the workpiece overlap portion in front of the welding movement direction of the processing head is detected by a welding position detection means, and the workpiece overlap portion near the laser light irradiation position is pressed by a gap correction means. The gap between the workpieces is corrected, and based on the welding position detected by the welding position detection means, the machining head is moved in the lateral direction intersecting the welding movement direction, and this lateral movement is transferred to the gap correction means. This is performed in consideration of the pressing amount against the workpiece.
[0007]
【The invention's effect】
According to the present invention, when the machining head is moved in the lateral direction intersecting the welding movement direction based on the welding position detected by the welding position detection means, the gap between the workpieces superimposed on each other is corrected. Since the workpiece pressing amount is taken into consideration, even if a gap is generated between the workpieces, the gap can be corrected and the laser beam can be irradiated to a desired welding position, so that the welding quality can be improved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0009]
Fig.1 (a) is a side view of the laser welding apparatus which shows one Embodiment of this invention, FIG.1 (b) is a top view which shows the welding position by the laser welding apparatus of Fig.1 (a). The machining head 3 supported by the robot 1 as the moving means performs laser welding while irradiating the workpiece W with the laser beam 5 while moving leftward in FIG. That is, the left direction is the welding movement direction A. As shown in FIG. 2, the workpiece W is obtained by superimposing two plate materials 7 and 9, and laser welding is performed along the edge 9 a of the upper plate material 9 that is superimposed.
[0010]
The processing head 3 guides laser light oscillated from a laser oscillator (not shown) into the housing 13 through the optical fiber 11, and works as the laser light 5 described above through the optical lenses 15 and 17 provided in the housing 13. Irradiate toward.
[0011]
The machining head 3 described above can be moved in a direction orthogonal to the paper surface in FIG. 1 with respect to the bracket 21 supported by the robot 1 by a linear motor 19 as a lateral movement support means. That is, the machining head 3 is movable in the lateral direction intersecting with the welding movement direction A.
[0012]
The bracket 21 described above includes a roller support arm portion 21a that is bent so that the lower end protrudes toward the processing head 3 side. The downward convex portion 21b of the roller support arm portion 21a shown in FIG. A pressing roller 23 as means is rotatably supported via a support shaft 25. The pressing roller 23 presses the overlapping portion between the plate members 7 and 9 in the vicinity of the irradiation position of the laser beam 5 on the workpiece W.
[0013]
On the other hand, the robot 1 includes a support frame 27 that extends in the vertical direction in FIG. 1, and the bracket 21 is attached to the support frame 27 via a guide portion 29 serving as a pressing direction moving support means. 1 is supported so as to be movable in the vertical direction.
[0014]
Further, a support arm 31 protruding toward the processing head 3 is provided at the upper end of the support frame 27, and the above-mentioned bracket 21 is pressed downward on the lower surface of the support arm 31 in FIG. 33 is provided. The pressurizing means 33 may be any means that pressurizes the bracket 21 elastically, and may be an elastic means such as a spring, for example.
[0015]
When the bracket 21 is pressed by the pressurizing means 33 and moved downward along the guide portion 29, the machining head 3 is lowered and the pressure roller 23 is also lowered to press the workpiece W.
[0016]
A sensor support arm 35 is provided at the lower end of the support frame 27 of the robot 1 so as to project forward from the machining head 3 in the welding movement direction A, and a laser as a welding position detection means is provided at the tip of the sensor support arm 35. A sensor 37 is provided.
[0017]
As shown in FIG. 1B, the laser sensor 37 has a slit-like laser that is long in the lateral direction (vertical direction in FIG. 1B) intersecting the welding movement direction A, as shown in FIG. The light 41 is irradiated toward the overlapping portion of the workpiece W. By irradiation with the laser beam 41, the position of the edge portion 9a of the upper plate member 9, that is, the welding position, is detected. Based on the detected welding position, the controller 43 as a control means controls the linear motor 19 described above. It drives and controls so that the laser beam 5 is always irradiated to the welding position.
[0018]
A bent solid line P extending in the left-right direction in FIG. 1B indicates an end edge portion 9a of the plate 9, and the end edge portion 9a is detected by the laser sensor 37, and the detected welding position and The amount of deviation in the lateral direction (vertical direction in FIG. 1B) with respect to the linear welding reference line Q indicated by the alternate long and short dash line taught in advance to the robot 1 is calculated, and a linear motor is calculated based on the amount of deviation. 19 is driven to move the machining head 3 in the lateral direction so that the laser beam 5 is irradiated along the solid line P.
[0019]
Further, the guide portion 29 detects the pressing amount by the pressing means 33, that is, the pressing amount against the work W by the pressing roller 23, from the reference position in the vertical direction of the bracket 21 before pressing the bracket 21 by the pressing means 33. A sensor (not shown) is provided. The controller 43 takes in the pressing amount detected by this sensor, and controls the driving of the linear motor 19 described above. That is, the controller 43 performs the above-described lateral movement of the machining head 3 in consideration of the pressing amount of the pressing roller 23 against the workpiece W.
[0020]
Next, the operation will be described. The robot 1 provided with the machining head 3 moves in the welding movement direction A. At this time, two press rollers 23 attached to the bracket 21 are applied by the downward pressure applied to the bracket 21 by the pressing means 33. The plate members 7 and 9 move while rotating while being pressed against each other.
[0021]
Here, as shown in FIG. 1A, a gap S may be generated between the two plate members 7 and 9 when the workpiece is set before welding. The above-described gap S is corrected by the pressing operation. The pressing amount, that is, the downward movement amount of the bracket 21 is detected by a sensor (not shown), and the detected value is input to the controller 43.
[0022]
When the machining head 3 moves in the welding movement direction A, the laser sensor 37 detects the edge 9a of the upper plate 9 that is the welding position, and the laser beam 5 is detected at the detected welding position. The controller 43 drives and controls the linear motor 19 to move the machining head 3 in a direction orthogonal to the paper surface in FIG.
[0023]
Here, as shown in FIG. 3A, which is a cross-sectional view of the workpiece W along the slit length direction (vertical direction in FIG. 1B) of the slit-shaped laser light 41 in FIG. Consider a case where the direction (laser beam central axis T) is inclined to the left side in FIG. 3A by an angle θ with respect to the perpendicular R to the surface of the upper plate 9. By giving such a tilt to the laser beam 5, foreign matter generated during welding can be blown away from the welding position.
[0024]
At this time, since the upper plate 9 is pressed by the pressing roller 23 to correct the gap S, the plate 9 is deformed to the position of the two-dot chain line, and the position to be irradiated with the laser beam 5 is the position of the upper plate 9. This is a point P _B where the edge portion 9a and the surface of the lower plate 7 are in contact. Therefore, when the laser beam 5 is irradiated toward the edge portion 9a (the point P ₀ in FIG. 3A) of the plate 9 that is the welding position before pressing the workpiece detected by the laser sensor 37, the actual welding point P _With respect to _B , a shift occurs in the lateral direction by ε.
[0025]
Here, when the initial gap dimension including the plate thickness of the plate member 9 between the plate members 7 and 9 is D, the above-described deviation amount ε is DTanθ. If the initial gap dimension D varies between 0.5 and 1 mm and θ = 5 °, a target error (deviation amount ε) is 0.16 mm. This is about 40% of the target accuracy required when fillet welding is performed on the end of the joint with a laser, resulting in a decrease in welding quality.
[0026]
At this time, as shown in FIG. 3 (b), from the shape of the workpiece W detected by the laser sensor 37, the point on the surface of the joint end portion P ₀ at the end edge portion 9 a of the upper plate member 9 and the upper plate member 9. P ₃ and points P ₁ and P ₂ on the lower plate 7 are extracted, respectively. Note that the point P ₁ is an intersection between the extension line of the central axis of the laser beam 5 and the surface of the plate member 7.
[0027]
On the other hand, the generated gap S is corrected by being pressed by the pressing roller 23 in the vicinity of the laser welding point in the direction perpendicular to the surface of the plate member 9 as described above. For this reason, among the feature points of the extracted shape, the surface direction of the plate material 9 is calculated from P ₀ -P _3, and the intersection point P _B between the perpendicular R of the surface and the extension line of the P ₁ -P ₂ straight line is calculated. The target position of the laser beam 5 is set. That is, the controller 43 drives and controls the linear motor 19 so that the machining head 3 moves leftward in FIG.
[0028]
That is, the controller 43 determines the plate material 9 based on the pressing amount (corresponding to the dimension D of the gap S) of the work W by the pressing roller 23, the plate thickness of the upper plate material 9, and the welding position detected by the laser sensor 37. edge 9a calculates the deformed position P _B by being pressed by the pressing roller 23 of the, the deformed position P _B of the calculated edge 9a, so as to irradiate the laser beam 5, the processing head 3 that It is moved in a direction orthogonal to the welding movement direction A.
[0029]
Thereby, even if the clearance gap S arises between each board | plate materials 7 and 9, this clearance gap S is correct | amended and the laser beam 5 can be irradiated to a desired welding position, and welding quality can be improved.
[Brief description of the drawings]
FIG. 1A is a side view of a laser welding apparatus showing an embodiment of the present invention, and FIG. 1B is a plan view showing a welding position by the laser welding apparatus of FIG.
2 is a perspective view showing a state in which laser welding is performed by the laser welding apparatus of FIG. 1; FIG.
3A is a cross-sectional view of a workpiece along the slit length direction of the slit-shaped laser sensor in FIG. 2, and FIG. 3B is a diagram illustrating an operation for correcting a welding position shift caused by a gap. FIG.
[Explanation of symbols]
3 Processing head 5 Laser light 7, 9 Plate material (workpiece)
9a Edge 19 of upper plate material Linear motor (lateral movement support means)
23 Pressure roller (clearance correction means)
29 Guide part (pressing direction moving support means)
33 Pressurizing means 37 Laser sensor (welding position detecting means)
43 Controller (control means)
S Gap between sheet materials (gap between workpieces)

Claims (5)

In a laser welding method in which two workpieces are overlapped with each other and laser welding is performed by irradiating a laser beam while moving the machining head along the edge of the upper workpiece, the welding movement direction of the machining head The workpiece overlap portion in front is detected by the welding position detection means, and the workpiece overlap portion near the laser light irradiation position is pressed by the gap correction means to correct the gap between the workpieces, thereby detecting the welding position. Based on the welding position detected by the means, the machining head is moved in the lateral direction intersecting the welding movement direction, and the lateral movement is performed in consideration of the pressing amount against the workpiece by the gap correction means. A characteristic laser welding method. Based on the pressing amount to the workpiece by the gap correction means, the plate thickness of the upper workpiece, and the welding position detected by the welding position detection means, the gap correction means at the edge of the upper workpiece is pressed against the gap correction means. 2. The deformation position according to claim 1 is calculated, and based on the calculated deformation position of the edge portion, the machining head is moved in a lateral direction intersecting the welding movement direction. Laser welding method. In a laser welding apparatus for performing laser welding by irradiating a laser beam while superimposing two workpieces on each other and moving along the edge of the upper workpiece, the workpiece being supported by a moving means, Welding position detecting means for detecting the workpiece overlapping portion in front of the machining head in the welding movement direction, gap correcting means for pressing the workpiece overlapping portion in the vicinity of the irradiation position of the laser beam, and the processing head and gap correction A pressing direction movement supporting means for supporting the means movably in the workpiece pressing direction by the gap correction means, and a lateral movement supporting means for supporting the processing head movably in the lateral direction intersecting the welding movement direction. , Based on the welding position detected by the welding position detection means, the operation of moving the processing head in the transverse direction intersecting the welding movement direction, Serial laser welding apparatus characterized by a control means for performing in consideration of the pressing amount for the workpiece by the gap straightening means. The control means is based on the pressing amount of the work by the gap correction means, the plate thickness of the upper work, and the welding position detected by the welding position detection means. A deformation position caused by being pressed by the gap correction means is calculated, and the processing head is moved in a lateral direction intersecting the welding movement direction based on the calculated deformation position of the edge portion. The laser welding apparatus according to claim 3. The welding position detecting means is supported by the moving means, and the processing head is supported by the moving means via the lateral movement supporting means and the pressing direction moving supporting means, and the moving means has the gap correction. 5. A laser welding apparatus according to claim 4, further comprising a pressing means for pressing the means together with the machining head in the pressing direction of the gap correction means.

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