WO2014129639A1

WO2014129639A1 - Laser welding apparatus

Info

Publication number: WO2014129639A1
Application number: PCT/JP2014/054392
Authority: WO
Inventors: 三郎八木; 繁松　孝; 佐藤　雅也; 伸弥児嶋
Original assignee: 古河電気工業株式会社; 古河As株式会社
Priority date: 2013-02-22
Filing date: 2014-02-24
Publication date: 2014-08-28
Also published as: JP5657181B1; JPWO2014129639A1

Abstract

This laser welding apparatus (10) is equipped with a galvanic scanner (33) for radiating a laser beam (LB) along the abutting interface (86) between workpieces (87), a laser output control system (60) for controlling the output from a laser beam source (20) in order to maintain a constant output (Wx) of the laser beam (LB), and a welding bead width measurement system (70) for measuring the width of welding beads formed along the abutting interface (86), and performs high quality laser welding of the abutting interface (86) of the workpieces (87) by controlling the sweep rate (v) of the laser beam (LB) by the galvanic scanner (33) on the basis of the measurement value from the welding bead width measurement system (70) and using the appropriate values for the output (Wx) and sweep rate (v) of the laser beam (LB).

Description

Laser welding equipment

The present invention relates to a laser welding apparatus for welding a butt interface of workpieces by laser irradiation.

Wire harnesses are often used for in-vehicle wiring. The wire harness is a set of a plurality of covered electric wires in a collective part according to the specifications of in-vehicle wiring. A terminal for connection (hereinafter referred to as a crimp terminal) is crimped to the end of each covered electric wire. When connecting the crimp terminal to the wire terminal of the wire harness, peel off the insulation coating layer of the wire terminal to expose the core wire, and crimp the core wire barrel of the crimp terminal to the core wire exposed part to crimp the wire terminal. Electrical connection with the terminal is made. And the connection part of a crimp terminal and an electric wire terminal is resin-sealed in order to prevent the corrosion of a core wire by the penetration | invasion of the water | moisture content from the connection part with a crimp terminal into the inside of an electric wire. (Patent Document 1, Patent Document 2)

Japanese Patent Laid-Open No. 2001-167821 JP 2012-069449 A

However, resin-sealing the connection between the crimp terminal and the wire terminal is a factor that increases the manufacturing cost of the wire harness. This is because the resin itself used is expensive, and it takes time for the resin to be poured and cured in the resin molding process or the coating process.

Therefore, the crimping part (wire connection part) of the crimping terminal is bent into a cylindrical shape by press molding, and the entire butt interface at both ends of the plate material formed in the cylindrically bent part is joined by laser welding to seal the crimping part. Attempts have been made to structure.

The joint strength of the welded part by laser welding depends on the output of the irradiated laser beam and the sweep speed. When laser welding is performed under the condition where the values of both parameters are out of the appropriate range, the weld strength against crimping becomes insufficient. This causes cracks in the welded portion when the crimp terminal is crimped to the wire end.

The problem to be solved by the present invention is to monitor the abnormality of the light source and optical system of the laser beam irradiated to the welded portion with a simple configuration, and to perform laser welding of the butt interface of the workpiece with high quality. The object is to provide a laser welding apparatus.

In order to solve the above problems, a laser welding apparatus of the present invention is a laser welding apparatus that welds a butt interface of a workpiece by laser irradiation while sequentially supplying a workpiece having a butt interface to a welding position. A laser beam sweep irradiation means for irradiating the laser beam outputted from the laser light source while sweeping along the abutting interface; and the laser light source for keeping the output of the laser beam emitted to the workpiece constant. Laser output control means for controlling the output of the laser beam, and a weld bead for measuring the width dimension of the weld bead (weld mark) formed along the butt interface (hereinafter, “width dimension” is referred to as “bead width”). Width measuring means.

The laser welding apparatus configured as described above can guarantee the quality of the workpiece after welding by measuring the width dimension of the weld bead formed along the butt interface. Here, the reason why quality can be assured by measuring the bead width is that the bead width has a corresponding relationship with the amount of heat input by welding. For example, if the laser output, sweep speed, focal position, terminal dimensional accuracy before welding, and terminal positioning accuracy before welding do not change, the welding quality is stable and the bead width at that time is also reproducible. Therefore, since the bead width when the welding quality is good is reproduced without change, the laser welding apparatus of the present invention confirms this reproducibility, and thereby the total number of workpieces welded by the laser welding apparatus. Quality inspection can be performed.

Also, the focus position and product positioning accuracy can be secured with a clamp jig, and the terminal dimension accuracy before welding is basically a press-fed product, so there is basically no short-term change. Further, the output of the laser can be monitored by receiving light on the PD. When the bead width deviates from the predetermined width under these conditions, the laser welding apparatus of the present invention can determine that there is an abnormality in the laser light source or the optical system.

In the laser welding apparatus of the present invention, it is desirable to further include laser light sweep speed control means for controlling the sweep speed of the laser light by the laser light sweep irradiation means based on the measurement value by the weld bead width measurement means.

The laser welding apparatus configured as described above keeps the output of the laser beam irradiated to the workpiece constant and performs irradiation while sweeping the laser beam along the butt interface of the workpiece. The butt interface of the workpiece is welded, and the bead width of the weld bead formed at the butt interface after the welding is measured. Based on the measured value, the laser beam sweep speed during the subsequent welding is controlled.

If the output of the laser beam irradiated to the workpiece is constant, it is possible to determine whether the welding quality is good or bad by using the bead width as a guide. Therefore, welding is performed with the laser beam irradiation output to the work piece kept constant within an appropriate range, the bead width of the weld bead formed at the butt interface after the welding is measured, and based on the measured value Then, by controlling the laser beam sweep speed during the subsequent welding, the laser beam sweep speed is controlled to an appropriate value in relation to the irradiation output that is kept constant within an appropriate range. The butt interface of the workpiece can be laser welded with high quality.

In the laser welding apparatus of the present invention, the laser beam sweep speed control means is configured to correlate the laser beam sweep speed and the bead width of the weld bead under a condition in which the output of the laser beam irradiated onto the workpiece is constant. Storage means for storing the correlation data indicating, and based on the measurement value by the weld bead width measurement means and the correlation data, the laser beam sweep speed by the laser beam sweep irradiation means is controlled. desirable.

The above correlation data indicates that the output of the laser beam irradiated to the workpiece is constant, welding is performed under a plurality of conditions with different sweep speeds, and the bead width of the weld bead of the weld where the weld quality is good. The laser beam sweep speed is recorded, and a curve (see FIG. 3) representing the correlation between the two is obtained from the recorded result (actual measurement value), and this is digitized. Therefore, if the output of the laser beam irradiated to the workpiece is constant, the sweep speed target that improves the welding quality is obtained by obtaining the value of the sweep speed corresponding to the target value of the bead width from this correlation data. The value can be determined. And good welding quality is realizable by controlling a sweep speed so that a bead width may become a target value.

In the laser welding apparatus of the present invention, the laser output control means includes a laser light branching means for branching a part of the laser light outputted from the laser light source, and an output of the laser light branched by the laser light branching means. And a laser beam output monitoring unit for detecting, and it is preferable to control the output of the laser light source based on the output of the laser beam detected by the laser beam output monitoring unit. The laser light output from the laser light source is controlled by branching a part of the laser light output from the laser light source, detecting the output, and controlling the laser light source so that the detected value is constant. Can be kept constant.

In the laser welding apparatus of the present invention, the weld bead width measuring means measures the bead width of the weld bead based on an imaging means for imaging the workpiece and an image captured by the imaging means. It is desirable to have the image processing means. According to this configuration, since the bead width of the weld bead can be measured from the appearance of the actual workpiece subjected to the welding process, the laser beam sweep speed is set to an appropriate value based on the actual welding result. Can be controlled.

Since the laser welding apparatus of the present invention can monitor the abnormality of the laser light source and the optical system irradiated to the butt interface of the workpiece with a simple configuration, the butt interface of the workpiece is laser-welded with high quality. be able to.

Device configuration diagram of the first embodiment of the present invention (A) Conceptual diagram illustrating the workpiece having a gap at the butt interface and the configuration of the clamping device in a state before the workpiece is sandwiched. (B) The workpiece in a state in which the workpiece is sandwiched by the clamping device. Conceptual diagram illustrating the state in which laser light is irradiated to the butt interface of the workpiece The graph which illustrated the correlation curve showing the correlation of sweep speed and bead width when the output of laser light is constant and the welding quality is good Explanatory drawing of the process which changes the target value of sweep speed using the correlation curve of FIG. The apparatus block diagram of the 3rd Embodiment of this invention The perspective view of the crimp terminal welded by the laser welding apparatus of this invention Process drawing which shows the outline of the manufacturing process of the crimp terminal of FIG.

Hereinafter, the best mode for carrying out the present invention will be described.

In this embodiment, an apparatus configuration for manufacturing the crimp terminal 80 illustrated in FIG. 6 will be described. As shown in FIG. 7, the crimp terminal 80 has (a) a belt-shaped metal plate 81 that is fed forward at a constant pitch in the longitudinal direction (direction of arrow A), and (b) the carrier portion 82 and the unfolded state. (C) A plate material that can be formed into a crimping portion 85 by integrally molding the box-shaped connector portion 84 and the cylindrical crimping portion 85 by punching and bending the terminal material 83. It is manufactured through a series of processes in which the butt interface 86 at both ends and the overlapping portion 100 are joined by laser welding. Here, the abutting interface refers to a portion where one end surface in the bending direction of the plate material constituting the crimping portion and the other end surface are abutted and brought into contact with each other.

[First Embodiment]
FIG. 1 is a system configuration diagram showing a first embodiment of a laser welding apparatus of the present invention. The laser welding apparatus 10 is an apparatus that sequentially supplies unwelded crimp terminals 87 as workpieces to a welding position P and welds a butt interface 86 of a crimping portion 85 of the crimp terminals 87 by laser irradiation. As shown in FIG. 7C, the crimp terminals 87 are sequentially fed to the welding position P in the form of chain terminals 88 that are cantilevered by the carrier portion 82 at regular intervals, and are subjected to welding by laser irradiation. Is done.

The laser welding apparatus 10 includes a laser light source 20, a laser irradiation optical system 30, a feeding device 40, a clamping device 50, a laser output control system 60, a weld bead width measurement system 70, and a control device 90. is doing.

The laser light source 20 is a known fiber laser, and oscillates laser light having a wavelength in the near-infrared region using a silica optical fiber doped with a rare earth element as a laser medium.

The laser irradiation optical system 30 is an optical system for guiding the laser beam output from the laser light source 20 to the welding processing position P. The laser irradiation optical system 30 includes an optical path axis shift optical system 31, a galvano scanner 32, and a condenser lens 33.

The optical path axis shift optical system 31 is an optical system that reflects the laser light output from the laser light source 20 in the horizontal direction at right angles a plurality of times and shifts the optical path axis of the laser light upward in parallel. In this example, it is composed of two dielectric multilayer flat mirrors 31A and 31B which are arranged in parallel with each other and vertically spaced from each other with an incident angle of 45 °.

The galvano scanner 32 is a two-axis (XY) type galvano scanner, and the laser beam from the optical path axis shift optical system 31 is driven at high speed and with high accuracy by driving the two mirrors 32X and 32Y attached to the rotation axis, respectively. By sequentially reflecting, the laser light LB is swept to the butt interface 86 and the overlapping portion 100 of the crimp terminal 87 stopped at the welding position P. The irradiation position of the laser beam LB in the horizontal plane can be adjusted by controlling the angles of the mirrors 32X and 32Y, and the sweep speed of the laser beam LB can be adjusted by controlling the rotation speed of the mirrors 32X and 32Y. .

The condensing lens 33 is an optical coupling system that condenses the laser light from the galvano scanner 32 at the position of the butt interface 86 of the crimp terminal 87. As the condenser lens 33, a telecentric lens or an fθ lens is used.

The feeding device 40 is a device that sequentially supplies the crimp terminals 87 to the welding position P by intermittently feeding the chain terminals 88 at a constant pitch corresponding to the interval L where the crimp terminals 87 are arranged. The feeding device 40 has

twin rollers

41 and 42 that rotate while sandwiching the carrier portion 82 of the chain terminal 88 from above and below in the vicinity of the upstream side and the downstream side of the welding position P in the feed direction of the chain terminal 88. Yes. The

twin rollers

41 and 42 include a feed roller 43 that contacts the lower surface of the carrier portion 82 and a pressing roller 44 that contacts the upper surface. The pressing roller 44 is driven to rotate while pressing the carrier portion 82 from above. The feed roller 43 is rotationally driven at a constant speed by a drive mechanism (not shown). On the outer peripheral surface of the feed roller 43, feed claws 45 are projected at equal intervals in the circumferential direction. The feed claw 45 engages with a feed hole 89 (see FIG. 7) of the carrier portion 82. Each time the feed roller 43 rotates by a certain angle, the feed claw 45 engaged with the feed hole 89 of the carrier portion 82 moves the chain terminal 88 by an interval L where the crimp terminals 87 are arranged.

The clamp device 50 is a device for accurately positioning the crimp terminal 87 supplied to the welding position P. The clamp device 50 has an upper clamp jig 51 and a lower clamp jig 52, and is clamped from above and below so that the clamp jigs 51 and 52 are in contact with the crimping portion 85 of the crimp terminal 87 at least at three points. For this reason, the clamp jig 51 is formed with, for example, a substantially C-shaped portion 51 a that abuts and presses against the crimping portion 85 at two points. On the other hand, the clamp jig 52 is formed with a substantially flat contact surface 52a that contacts the crimping portion 85 at one point. By sandwiching the crimping portion 85 of the crimping terminal 87 from above and below by the clamp jigs 51 and 52, the butt interface 86 of the crimping portion 85 is placed at a position where the laser beam LB can be irradiated as shown in FIG. Can be positioned. Further, the upper clamp jig 51 is formed with a slit 51b so as not to obstruct the irradiation of the laser beam LB to the butt interface 86.

The laser output control system 60 is an optical-electric composite system for controlling the output of the laser light source 20 so as to keep the output of the laser light LB irradiated to the crimping portion 85 of the crimp terminal 87 constant. In other words, the laser output control system 60 has a laser beam branching optical system 61 for branching a part of the laser beam LB output from the laser light source 20 and a laser beam LB (pd) branched by the laser beam branching optical system 61. And a laser beam output monitor device 62 for detecting the output of In this example, two dielectric multilayer flat mirrors 31 </ b> A and 31 </ b> B of the optical path axis shift optical system 31 are used as the laser beam branching optical system 61. Most of the laser beam LB output from the laser light source 20 is sequentially reflected by the two dielectric multilayer film plane mirrors 31A and 31B and guided to the galvano scanner 32. A part of the laser beam LB is planar on the upper dielectric multilayer film plane. The light passes through the mirror 31 </ b> A and enters the light receiving unit of the laser light output monitor device 62. A condensing lens 102 is provided between the laser light output monitoring device 62 and the dielectric multilayer flat mirror 31A. The laser light output monitoring device 62 includes a photodiode (PD) as a light receiving element, and outputs an electrical signal proportional to the amount of light received. The output signal of the laser light output monitor device 62 is input to the control device 90. The output of the laser light source 20 is W ₁ , the reflectance of the mirror 31B is R _31B , the transmittance of the condenser lens 102 is T _LPD , the transmittance of the dielectric multilayer flat mirror 31A is T ₁ , and the mirror 32X in the galvano scanner 32 , _{R g} reflectivity per one 32Y, when the transmittance of the condenser lens 33 and _{T L,} the output _{W pd} and crimp terminals of the laser beam LB which is measured by a laser beam output monitor unit 62 (pd) 87 The output Wx of the laser beam LB irradiated to is expressed by the following equations (1) and (2).

W _pd = W ₁ × R _31B × T ₁ × T _LPD (1)
Wx = {(1−T ₁ ) × R _g ² × T _L } W _pd / (T ₁ × T _LPD ) (2)
Here, when it is necessary to further attenuate the incident light to the PD, it is preferable to insert an optical filter between the PD and the condensing lens 102 or between the mirror 31A and the condensing lens 102.

Assuming that the transmittance of the filter is T ₂ , the output W _{pd of} the laser beam LB (pd) and the output Wx of the laser beam LB irradiated to the crimp terminal 87 are expressed by the following equations (3) and (4).

W _pd = W ₁ × R _31B × T ₁ × T ₂ × T _LPD (3)
Wx = {(1−T ₁ ) × R _g ² × T _L } W _pd / (T ₁ × T ₂ × T _LPD ) (4)
The output W _pd of the laser beam LB (pd) is constantly monitored using a photodiode (PD), and the output W _{1 of the} laser light source 20 is set so that W ₁ obtained from the formula (1) or (3) falls within the allowable output value. To control.

For example, when the output W ₁ of the laser light source 20 is 400 W, the allowable output value is set to 392 to 408 W of ± 2%. That is, by controlling so that the output W _{pd of} the laser beam LB (pd) and W ₁ obtained from the expression (1) or (3) do not deviate from the output allowable value, it is guaranteed that Wx is always stable. it can. If it is outside the allowable output range, an output error is issued.

The weld bead width measurement system 70 is an optical-electric composite system that performs a process of measuring the bead width of a weld bead (weld mark) formed along the butt interface 86 of the crimp terminal 87. The weld bead width measurement system 70 includes an imaging device 71 for imaging the crimping portion 85 of the crimp terminal 87 and an image processing system 72 for measuring the width dimension of the weld bead based on an image captured by the imaging device 71. And have.

The imaging device 71 is disposed at a predetermined position downstream of the welding position P so as to face the passing region of the crimping terminal 80 that has been subjected to the welding process. In this example, it is provided facing the downstream position by a distance corresponding to 4 pitches (L × 4) from the welding position P. For the imaging device 71, an image sensor using a solid-state imaging device such as a CCD (Charge Coupled Dice) or a CMOS (Complementary Metal Oxide Semiconductor) is used. The imaging device 71 images the crimping portion 85 of the crimp terminal 80 and outputs the obtained image data. The image data output from the imaging device 71 is input to the image processing system 72. The image processing system 72 performs image processing such as edge detection processing on the input image data, and outputs the processed data. Data output from the image processing system 72 is input to the control device 90.

The laser welding apparatus 10 configured as described above keeps the output Wx of the laser beam LB irradiated to the butt interface 86 of the crimp terminal 87 constant, and sweeps the laser beam LB along the butt interface 86 of the crimp terminal 87. By irradiating, the butt interface 86 of the crimp terminal 87 is welded, and the bead width of the weld bead formed on the butt interface 86 after the welding is measured. Thereby, not only the butt interface of the workpiece is laser welded with high quality, but also when the optical system (for example, the galvano scanner 32 and the condenser lens 33) after the dielectric multilayer flat mirror 31A is abnormal. An error can be issued. In other words, if the control system using the photodiode (PD) is normal but the bead width deviates from the predetermined width, it can be determined that the optical system such as the galvano scanner 32 is abnormal.

Subsequently, a case where the control device 90 is added will be described. The control device 90 is a computer system that performs overall control of the overall operation of the laser welding apparatus 1 and functions as laser output control means and welding bead width measurement means. That is, the control device 90 controls the output of the laser light source 20 to be constant based on the output signal from the laser light output monitor device 62, and the image processing system 72 based on the image data from the image processing system 71. Measure the width of the weld bead. Further, the control device 90 functions as a laser beam sweep speed control means. That is, the control device 90 generates correlation data indicating the correlation between the sweep speed of the laser beam LB and the width of the weld bead under the condition that the output of the laser beam LB irradiated to the butt interface 86 of the crimp terminal 87 is constant. The sweep speed of the laser beam LB by the galvano scanner 32 is controlled based on the measured value of the bead width of the weld bead and the correlation data.

Correlation data shows that welding was performed under a plurality of conditions with different sweep speeds of the laser beam LB while keeping the output of the laser beam LB irradiated to the butt interface 86 of the crimp terminal 87 constant, and the welding quality was good. The bead width of the weld bead and the sweep speed of the laser beam LB are recorded, and a correlation curve (see FIG. 3) representing the correlation between the two is obtained from the recorded result (actual measurement value), and this is quantified. It is. The correlation data is stored in the storage unit of the control device 90 as a data table in which the output Wx of the laser beam LB is constant and the value of the sweep speed is associated with the value of the width dimension of the weld bead. The data table is measured data obtained from an experiment in which welding is performed under a plurality of conditions with different laser beam sweep rates while keeping the laser beam output constant, and the sweep rate value and welding quality are good. It is comprised by the data which matched the value of the width dimension of the weld bead of the weld part which was. As this parameter, the temporal change of the shape of the press die used for manufacture of the crimp terminal 80 can be mentioned. For example, the gap of the butt interface 86 may be widened.

The laser welding apparatus 10 configured as described above keeps the output Wx of the laser beam LB irradiated to the butt interface 86 of the crimp terminal 87 constant, and sweeps the laser beam LB along the butt interface 86 of the crimp terminal 87. By irradiating, the butt interface 86 of the crimp terminal 87 is welded, and the bead width of the weld bead formed on the butt interface 86 after the welding is measured. When the measured value deviates from the target value, the sweep speed of the laser beam LB during the subsequent welding is controlled based on the measured value and the correlation data (see FIG. 3).

For example, it is assumed that the target value of the bead width is ± 5% of 200 μm, that is, 190 to 210 μm, the bead width upper limit acceptable value is 220 μm, and the lower limit acceptable value is 180 μm. The operation of the laser welding apparatus 10 was started, and the average value of the bead width was obtained for every 100 terminals. The average value of the bead width of the crimp terminals 80 of 1 to 50000 was all 200 μm, When the average value of the bead width of the 50001 to 50101 crimp terminals 80 is 180 μm, a signal having a difference of 10 μm from the target value is fed back to the control system of the galvano scanner 32, and the bead width is the target value of 200 μm ± 5 Control is performed so that the sweep speed of the laser beam LB is shifted toward the lower limit sweep speed side so as to be within the range of%. The routine operation is repeated until the bead width reaches the target value by a series of operations. When the bead width comes out of the upper limit or lower limit pass value, it is judged as NG and the whole system is stopped.

In this way, welding is performed while keeping the LB irradiation output Wx of the laser beam to the butt interface 86 of the crimp terminal 87 constant, and the bead width of the weld bead formed on the butt interface 86 after the welding is measured. Based on the measurement value, the sweep speed v of the laser beam LB at the time of subsequent welding is controlled, so that the sweep speed v of the laser beam LB is kept constant within an appropriate range. The butt interface 86 of the crimp terminal 87 can be laser-welded with high quality by controlling to an appropriate value.

[Second Embodiment]
A sweep speed control method different from the control method described with reference to FIG. 3 will be described with reference to FIG. FIG. 4 shows curves C1, C2, and C3 representing changes in bead width according to the sweep speed. For example, C1, C2, and C3 can be curves when the butt gap is 0 μm, 10 μm, and 20 μm.

First, when the bead width deviates from the target value of 200 μm and becomes 190 μm, a curve C2 where the bead width becomes 190 μm at the sweep speed V1 is found from the data table. The sweep speed V2 (v1> v2) ± 20 mm / sec at the point where the curve C2 intersects the target value 200 μm of the bead width is set. The sweep speed is increased or decreased so that the target value of the bead width becomes 200 μm within the set sweep speed, and the sweep speed that has become the target value of the bead width is set as a new sweep speed v. By changing the sweep speed v of the laser beam LB from the initial sweep speed v1 to a slower sweep speed v2, the bead width is controlled to a target value of 200 μm in the subsequent welding. In the above, a data table associated with a plurality of matching gaps is used. However, for example, a data table in which a deviation due to rolling of a butt interface or a matching gap and rolling is created and stored in the control device 90 is stored. More preferably, it is stored in the part.

[Third Embodiment]
FIG. 5 is a system configuration diagram showing a third embodiment of the laser welding apparatus of the present invention. Here, constituent elements common to the first embodiment are denoted by the same reference numerals in the drawing, and description thereof will be omitted as appropriate. In the first embodiment, the galvano scanner 32 is provided, and the laser light LB from the laser light source 20 is shaken in the XY direction (horizontal direction) by the two mirrors 32X and 32Y in the galvano scanner 32, thereby matching the crimp terminal 87. Although the configuration in which the laser beam LB is swept along the interface 86 is adopted, the third embodiment shown in FIG. 5 includes a laser processing head 90, and the laser processing head 90 itself is XY direction (horizontal direction). The laser beam LB is swept by moving to. In the laser processing head 90, a dielectric multilayer flat mirror 91 that reflects the laser beam LB from the laser light source 20 downward at right angles and falls on the welding processing position P, and a laser from the dielectric multilayer flat mirror 91. A condensing lens 92 that condenses the light LB at the position of the butt interface 86 of the crimp terminal 87 is provided. Further, the laser processing head 90 is provided with a laser light output monitoring device 62. The laser beam LB from the laser light source 20 passes through the dielectric multilayer flat mirror 91 and enters the light receiving unit of the laser beam output monitor device 62.

Also in the third embodiment, by monitoring a part of the laser beam LB (pd) of the laser beam LB output from the laser light source 20, the output of the laser beam LB irradiated to the butt interface 86 of the crimp terminal 87. By keeping Wx constant and irradiating the butt interface 86 of the crimp terminal 87 while sweeping the laser beam LB, the butt interface 86 of the crimp terminal 87 is welded and formed at the butt interface 86 after the welding. Measure the bead width of the weld bead. When the measured value deviates from the target value, the moving speed of the laser machining head 90 in the sweep direction is controlled based on the measured value and the correlation data (see FIG. 3), thereby The butt interface 86 can be laser welded with high quality.

[Other Embodiments]
The configuration of the present invention is not limited to the configuration of the above embodiment. For example, the arrangement of various mirrors and lenses, the number of mirrors between the welding processing position P and the PD can be appropriately changed. However, the installation position of the PD 62 should not be a position where reflected light (laser scattered light, that is, return light) from the welding position P is transmitted from the mirror. This is because the return light component may be erroneously detected as the output of the laser and added to the output to be measured. The PD 62 only needs to detect the output of the laser beam irradiated to the workpiece. For example, the installation position of the PD 62 may be set immediately before the workpiece, that is, immediately before the welding position P. Also in this case, for example, a mirror or the like is disposed immediately before the welding position P so that the PD 62 does not receive the reflected light from the welding position P.

Also, the workpiece is not limited to the crimp terminal. That is, the present invention can be applied to a laser welding apparatus for all workpieces having a butt interface between metal sheets. In the above example, the case where a fiber laser is used as the laser light source 20 has been described. However, the laser light source 20 is not limited to a fiber laser. Further, when the surface of the workpiece is plated, the width of the portion where there is no plating at the butt interface after welding may be measured as the bead width. In addition, the width dimension of the weld bead may be measured by measuring a change in the outer diameter or inner diameter of the welded part using, for example, a laser distance meter, without being limited to the captured image. Further, when any abnormality is detected from the measurement result of the weld bead width, the molding process by the press machine and the welding process by the laser welding apparatus may be stopped simultaneously.

DESCRIPTION OF SYMBOLS 10 Laser welding apparatus 20 Laser light source 30 Laser irradiation optical system 32 Galvano scanner (laser sweep irradiation means)
40 Feeding device 50 Clamping device 60 Laser output control system 61 Laser beam branching optical system 71 Imaging device 80 Control device (laser output control means, weld bead width measuring means, laser light sweep speed control means)
85 Crimping part 86 Butt interface 87 Crimp terminal (workpiece)
LB Laser beam P Welding position

Claims

A laser welding apparatus that welds the butt interface of the workpiece by laser irradiation while sequentially supplying the workpiece having the butt interface to the welding position,
Laser light sweep irradiation means for irradiating laser light output from a laser light source while sweeping along the butt interface;
Laser output control means for controlling the output of the laser light source so as to keep the output of the laser light applied to the workpiece constant;
And a welding bead width measuring means for measuring a width dimension of a weld bead formed along the butt interface.
The laser welding apparatus according to claim 1, further comprising laser light sweep speed control means for controlling a laser light sweep speed by the laser light sweep irradiation means based on a measurement value obtained by the weld bead width measurement means.
The laser light sweep speed control means is
Storage means for storing correlation data indicating a correlation between the sweep speed of the laser beam and the width dimension of the weld bead under a condition in which the output of the laser beam irradiated to the workpiece is constant;
The laser welding apparatus according to claim 2, wherein a laser beam sweep speed by the laser beam sweep irradiation unit is controlled based on a measurement value by the weld bead width measurement unit and the correlation data.
The laser output control means includes
Laser beam branching means for branching a part of the laser beam output from the laser light source;
Laser light output monitoring means for detecting the output of the laser light branched by the laser light branching means,
The laser welding apparatus according to any one of claims 1 to 3, wherein an output of the laser light source is controlled based on an output of the laser light detected by the laser light output monitoring means.
The weld bead width measuring means is
Imaging means for imaging the workpiece;
5. The laser welding apparatus according to claim 1, further comprising an image processing unit configured to measure a width dimension of the welding bead based on an image captured by the imaging unit.