JP2011224618A - Laser beam welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser welding method capable of performing the laser seam welding with excellent welding finish.SOLUTION: The CW laser beam of continuous oscillation as a laser beam is scanned along a weld part by using a galvanometer scanner. During that time, while the output of the CW laser beam is controlled to be constant, the scanning speed of the CW laser beam is variably controlled.

Description

  The present invention relates to a laser welding method, and more particularly to a laser welding method suitable for continuously welding workpieces.

  Conventionally, as a welding method using laser light, laser seam welding in which a metal workpiece is continuously welded by scanning laser light has been employed.

  Conventionally, in such laser seam welding, pulsed laser light has been used as laser light.

  For example, Patent Document 1 proposes a technique of welding a cover for sealing the opening to the opening of the electronic component package by using pulsed laser light.

Japanese Patent Laid-Open No. 2007-12752

  By the way, depending on the object to be welded, the material or thickness of the object to be welded may differ depending on the irradiation position of the laser beam, that is, the welding part. In such a case, welding at each welding part is appropriately performed. For this reason, it may be necessary to make the energy of the laser light applied to each welding site different from each other.

  In this regard, in laser seam welding using pulsed laser light, the scanning speed of the pulsed laser light remains constant, and can be easily handled by changing the number of repetitions (pps) and output of the pulsed laser light. .

  On the other hand, in seam welding, it is desired to shorten the tact time of welding, and it has been studied to use a continuous wave CW laser (Continuous wave laser) instead of a pulse laser. In recent years, a fiber laser device has been suitably used as a laser device that oscillates such a CW laser. However, in laser seam welding using CW laser light, it has been pointed out that the weldability is liable to be adversely affected by fluctuations in laser output, and the welding finish tends to be poor.

  Therefore, the present invention has been made in view of such points, and an object of the present invention is to provide a laser welding method capable of realizing seam welding with a good welding finish using a CW laser.

  In order to achieve the above-described object, the laser welding method according to the present invention sequentially irradiates a laser beam with a galvanometer scanner along the welding site to a continuous welding site on the workpiece. A laser welding method for continuously welding an object to be welded, wherein the laser beam is a continuous wave CW laser beam, and the scanning speed of the CW laser beam is controlled while controlling the output of the CW laser beam to be constant. It is characterized by variable control.

  According to such a method, when performing laser seam welding on the workpiece, the scanning speed of the CW laser beam is variably controlled while the output of the CW laser beam is controlled to be constant and the output stability is ensured. Therefore, it is possible to appropriately perform welding at each welding site, and as a result, it is possible to improve the overall welding finish of the workpiece.

  As the variable control of the scanning speed, the scanning speed at the welding site at the start of welding is controlled to be lower than the scanning speed at the welding site on the welding progress side with respect to the welding site at the start of welding. Also good.

  And according to such a method, the welding at the time of an irradiation start can be performed appropriately by controlling the scanning speed in the welding site | part at the time of the welding start to a low speed side.

  Further, as the variable control of the scanning speed, the scanning speed in the welding portion having a relatively thick thickness may be controlled to be lower than the scanning speed in the welding portion having a relatively thin thickness.

  And according to such a method, by controlling the scanning speed in the welding part with a thick thickness to the low speed side, the welding in the welding part can be appropriately performed, while the scanning speed in the welding part with a thin thickness is performed. By controlling the welding speed to the high speed side, welding at the welding site can be performed quickly and reliably, and the occurrence of poor welding due to excessive heat input to the welding site and the thermal effect on the periphery of the welding site Can be avoided.

  Furthermore, as the variable control of the scanning speed, the scanning speed at the welding portion where the spread in the plane direction orthogonal to the thickness direction of the workpiece is relatively large is set to the welding portion where the spread is relatively small. The scanning speed may be controlled to be lower than the scanning speed.

  And according to such a method, it is possible to appropriately perform welding at the welding site by controlling the scanning speed at the welding site where the spread in the planar direction of the workpiece is large to the low speed side, By controlling the scanning speed at the welding site where the spread is small to the high speed side, welding at the welding site can be performed quickly and reliably, and the occurrence of poor welding due to excessive heat input to the welding site and the A thermal influence on the periphery of the welding site can be avoided.

  In addition, as the variable control of the scanning speed, the scanning speed in the scanning section in which the welding part is displaced in a curved line may be controlled to be higher than the scanning speed in the scanning section in which the welding part is linearly displaced. Good.

  According to such a method, by controlling the scanning speed in the scanning section in which the welding site is displaced in a curved shape to the high speed side, welding at the welding site can be performed quickly and reliably, and the welding is performed. It is possible to avoid the occurrence of poor welding due to excessive heat input to the part and the thermal effect on the periphery of the welded part, while the scanning speed in the scanning section where the welded part is displaced linearly is controlled to the low speed side. By doing, welding in the said welding part can be performed appropriately.

  Further, as a variable control of the scanning speed, it is arranged on the welding progress side with respect to the first welding site, and is arranged in the vicinity of the first welding site so as to sandwich a gap portion with the first welding site. The scanning speed at the second welded part may be controlled to be higher than the scanning speed at the welded part other than the second welded part.

  And according to such a method, while controlling the scanning speed in the 2nd welding part to the high-speed side, welding in the 2nd welding part can be performed quickly and reliably, and the 2nd welding part It is possible to avoid the occurrence of poor welding due to excessive heat input to the surface and the thermal effect on the periphery of the second welded part, while controlling the scanning speed at the welding part other than the second welded part to the low speed side. By doing, welding in the said welding part can be performed appropriately.

  According to the present invention, it is possible to realize laser seam welding with a good welding finish.

1 is a schematic configuration diagram showing a fiber laser device as an example of means for carrying out a laser welding method in an embodiment of a laser welding method according to the present invention. Part detailed drawing of the fiber laser device of FIG. The top view of the to-be-welded object used for description of a 1st specific example and a 2nd specific example in embodiment of the laser welding method which concerns on this invention AA sectional view of FIG. The top view of the to-be-welded object used for description of the 3rd example in embodiment of the laser welding method which concerns on this invention The top view of the to-be-welded object used for description of the 4th example in embodiment of the laser welding method which concerns on this invention In the embodiment of the laser welding method according to the present invention, a schematic plan view of an object to be welded used for explaining a fifth specific example.

  Hereinafter, an embodiment of a laser welding method according to the present invention will be described with reference to FIGS. 1 to 7.

  FIG. 1 shows a fiber laser device 1 as an example of means for performing a laser welding method in the present embodiment.

  As shown in FIG. 1, the fiber laser device 1 has a fiber laser oscillator 2. Although not shown, the fiber laser oscillator 2 includes a laser diode, an oscillation optical fiber, and reflection / transmission optical systems disposed on both ends of the optical fiber. The oscillation optical fiber is doped with rare earth ions in the core. This optical fiber may be a so-called double clad fiber. Further, the reflection / transmission optical system has a configuration in which a dielectric multilayer film is formed on the end face of an optical mirror system composed of a half mirror, a diffraction grating (FBG) embedded in both ends of a core, or an optical fiber. There may be. Furthermore, the fiber laser oscillator 2 may include an optical system such as a lens or a beam splitter as necessary.

  Here, in the fiber laser oscillator 2, an oscillation optical fiber functions as a laser medium. That is, when excitation light is emitted from the laser diode, the excitation light is transmitted through the incident-side reflection / transmission optical system, introduced into the core of the oscillation optical fiber, and then transmitted through the core. In the process, the rare earth element ions doped in the core are photoexcited. Thereafter, the excitation light is sequentially reflected by the reflection / transmission optical systems on the emission side and the incident side and reciprocates in the core, and light amplification is performed. A part of the amplified light is reflected on the emission side as fiber laser light. / The light is transmitted through the transmission optical system and emitted to the outside of the fiber laser oscillator 2.

  In the present embodiment, the fiber laser oscillator 2 emits CW laser light as fiber laser light.

  As shown in FIG. 1, an incident unit 3 having a condenser lens (not shown) is disposed at a position on the emission side of the CW laser light with respect to the fiber laser oscillator 2. The CW laser beam emitted from the fiber laser oscillator 2 is made incident. The incident unit 3 condenses and emits the incident CW laser light. In addition, what is necessary is just to provide the incident unit 3 as needed.

  Further, as shown in FIG. 1, a transmission optical fiber 5 is connected to the exit end of the incident unit 3 via the incident end, and the incident end of the optical fiber 5 is connected to the incident unit 3. The emitted CW laser light is incident. The CW laser light incident on the optical fiber 5 is transmitted through the core toward the emission end of the optical fiber 5.

  As shown in FIG. 1, a galvanometer scanner 6 is connected to the emission end of the optical fiber 5.

  A specific configuration example of the galvanometer scanner 6 is shown in FIG.

  As shown in FIG. 2, the galvanometer scanner 6 rotates the X-axis scan mirror 8X and the Y-axis scan mirror 8Y respectively attached to the rotation axes 7X and 7Y orthogonal to each other, and both the mirrors 8X and 8Y. It has an X-axis galvanometer 10X and a Y-axis galvanometer 10Y to be swung. In FIG. 2, the positional relationship between the X-axis scan mirror 8X and the Y-axis scan mirror 8Y is such that the Y-axis scan mirror 8Y is on the traveling side of the CW laser light with respect to the X-axis scan mirror 8X. ing.

  Here, the X-axis galvanometer 10X includes, for example, a movable iron piece (rotor) coupled to the X-axis scan mirror 8X, a control spring connected to the movable iron piece, and a drive coil attached to the stator. The drive current corresponding to the X-direction scanning control signal is supplied to the drive coil via the electric cable 14X. Then, by supplying the drive current, the movable iron piece swings integrally with the X-axis scanning mirror 8X at an angle specified by the X-direction scanning control signal so as to resist the control spring.

  The Y-axis galvanometer 10Y has the same configuration, and a drive current corresponding to the Y-direction scanning control signal is supplied to the drive coil in the Y-axis galvanometer 10Y via the electric cable 14Y, and the Y-axis galvanometer 10Y The movable iron piece (rotor) can swing integrally with the Y-axis scanning mirror 8Y at an angle specified by the Y-direction scanning control signal.

  Further, as shown in FIG. 2, the fiber laser device 1 has a collimation lens 11 disposed on the optical path between the emission end of the optical fiber 5 and the X-axis scan mirror 8X, and the Y-axis scan mirror 8Y. And an fθ lens 12 disposed at a position on the traveling side of the CW laser light.

  In such a galvanometer scanner 6, the CW laser light emitted from the optical fiber 5 is collimated by the collimation lens 11 and then enters the X-axis scan mirror 8 </ b> X. Next, the CW laser light incident on the X-axis scan mirror 8X is totally reflected by the X-axis scan mirror 8X and enters the Y-axis scan mirror 8Y. Next, the CW laser light incident on the Y-axis scan mirror 8Y is totally reflected by the Y-axis scan mirror 8Y and enters the fθ lens 12. Next, the CW laser light incident on the fθ lens 12 is focused by the fθ lens 12 and then irradiated to a welding site (P in FIGS. 1 and 2) where welding is to be performed on the workpiece.

  At this time, the X-direction component of the position of the welding site is determined by the deflection angle of the X-axis scan mirror 8X, and the Y-direction component is determined by the deflection angle of the Y-axis scan mirror 8Y. Further, the displacement (movement) speed of the welded portion, that is, the scanning speed of the CW laser beam is determined by the rotational speed of the X-axis scan mirror 8X for the X-direction component, and the Y-axis scan mirror 8Y for the Y-direction component. It is determined by the rotation speed. In this way, the CW laser beam is scanned by the galvanometer scanner 6.

  Returning to FIG. 1, the fiber laser apparatus 1 has a controller (control unit) 17, to which a fiber laser oscillator 2 and a galvanometer scanner 6 are connected. The controller 17 drives and controls the laser diode by applying an excitation current to the laser diode of the fiber laser oscillator 2 via a power supply unit (not shown). However, the controller 17 controls the current value and waveform of the excitation current so that the CW laser beam is emitted by the fiber laser oscillator 2. In addition, the controller 17 drives and controls the galvanometer scanner 6 by inputting the X direction scanning control signal and the Y direction scanning control signal to the galvanometer scanner 6 via the electric cables 14X and 14Y. ing. The controller 17 may be one in which the controller of the fiber laser oscillator 2 and the controller of the galvanometer scanner 6 are individually provided, or they may be integrally formed. Good.

  In the present embodiment, for example, by using such a fiber laser device 1, laser beams are sequentially irradiated onto the continuous welded parts (welded part group) on the work piece along the welded parts. By doing so, the workpieces are continuously welded (laser seam welding). The laser welding method in the present embodiment may be applied when welding a plurality of workpieces, or after bending a single workpiece for example, the single workpiece. You may apply when welding the site | parts from which a weldment differs.

  In this laser seam welding, a CW laser beam as a laser beam is scanned along the welding site using a galvanometer scanner 6.

  Further, at this time, the scanning speed of the CW laser light is variably controlled according to the displacement of the welding site and the difference in the welding conditions while controlling the output of the CW laser light constant. Specifically, differences in thermal conductivity due to differences in the pattern of the welded part group, differences in the thickness of the welded part, or differences in the flat area of the work piece in the vicinity of the welded part, and melting of the work piece at the start of welding The scanning speed is changed depending on the sex or the like. The thermal conductivity is synonymous with the ease of heat escape at the welding site. Further, as described above, the output of the CW laser light is controlled to be constant, but this control can be realized by controlling the current value and waveform of the excitation current by the controller 17. Furthermore, the variable control of the scanning speed of the CW laser light can be realized by appropriately changing the deflection angle and the rotation speed indicated by the X direction scanning control signal and the Y direction scanning control signal according to the welding site.

  The laser welding method according to the present embodiment can be suitably used for sealing welding of a container made of aluminum, for example. In this case, the fluctuation range of the scanning speed by the variable control can be set within a range of 100 to 300 mm / s, for example.

  The output of the CW laser light (that is, the output of the fiber laser device 1) can be set to 1 to 4 kW, for example, and is preferably controlled to the maximum output of the fiber laser device 1.

  Next, a specific example of such variable control of the scanning speed of the CW laser light will be described.

(First specific example)
In the first specific example, as a variable control of the scanning speed of the CW laser light, the scanning speed at the welding site at the start of welding is set lower than the scanning speed at the welding site on the welding progress side with respect to the welding site at the start of welding. Control.

  Here, for example, as shown in FIG. 3 and FIG. 4, as an example of a plurality of objects to be welded, a plate-like shape is formed in the opening 20 in the box-shaped first object 21 in which the opening 20 is formed. Consider a case where both the workpieces 21 and 22 are subjected to laser seam welding using a CW laser in a state in which the second workpiece 22 is inscribed through its peripheral end.

  In FIG. 3, a continuous (circumferential) group of welding sites are taken on the opening 20 of the first workpiece 21 and the peripheral end of the second workpiece 22. Become. The first workpiece 21 may be a battery outer can made of aluminum, and the second workpiece 22 may be a battery lid plate made of aluminum.

As shown in FIG. 3, in this example, starts the welding from the welding site at the welding start, it indicated at P _1, a CW laser beam in the welding direction shown by an arrow in FIG. 3 the welding site continuously Seam welding is performed by scanning.

When applying the present embodiment to both welded object 21 and 22 Rezashimu welding between 3 and 4, first, as shown in FIG. 3, the welded part P ₁ at the start of welding, CW laser The light scanning speed is controlled to a predetermined speed on the low speed side. Here, the welded part P ₁ at the start of welding, since it is difficult to be absorbed CW laser beam to the weld object 21 and 22, not immediately melted. For this reason, the CW laser beam is easily absorbed by reducing the scanning speed.

Thereafter, when the CW laser light is absorbed by the workpieces 21 and 22, the workpieces 21 and 22 begin to melt. Since it melts Hajimare CW laser light is easily absorbed, for example, in a welding portion P ₂ of the welding progress side with respect to the weld site P ₁ at the start of welding indicated at P ₂ in Figure 3, the scanning speed of the CW laser beam the controls speed of a predetermined speed than the scanning speed in the welded part P _1.

Incidentally, the welding site P ₂ of the welding progress side is displaced naturally with the progress of the welding, with the displacement of the welding site P _2, continuously or stepwise scanning speed corresponding to each weld site P ₂ You may increase it. It is desirable to switch the scanning speed between as high and low as possible.

  According to this specific example, since the scanning speed of the CW laser beam can be controlled to a low speed until the workpieces 21 and 22 start to melt, welding at the start of welding can be appropriately performed.

(Second specific example)
Next, in the second specific example, as a variable control of the scanning speed of the CW laser light, the scanning speed at the welded portion having a relatively thick thickness is made lower than the scanning speed at the welded portion having a relatively thin thickness. Control.

  Here, consider a case where the present specific example is applied in place of the first specific example to the laser seam welding of the first workpiece 21 and the second workpiece 22 shown in FIGS. 3 and 4.

However, in this example, the thickness of the second object to be welded 22 at the welded part P ₁ at the start of welding, thicker than a second thickness of the weld object 22 in the welded portion P ₂ of the welding progress side And

In this assumption, in the present embodiment, in the welded part P ₁ at the start of welding, the scanning speed of the CW laser light, corresponding to the thickness of the second object to be welded 22 at the welded part P ₁ low speed Control to a predetermined speed on the side.

In contrast, in the welded part P ₂ of the welding progress side, the scanning speed of the CW laser beam, the second object to be welded in the high-speed welding site P ₂ than the scanning speed in the welded part P ₁ at the start of welding The speed is controlled to a predetermined speed corresponding to the thickness of 22.

  Even when the thickness of the second workpiece 22 is more than three stages, the scanning speed of the CW laser beam at each welding site corresponding to the thickness of each stage is controlled to a predetermined speed corresponding to each thickness. That's fine. Also in this specific example, it is desirable to switch the scanning speed between as high and low as possible.

  According to this example, when irradiating a thick welded part with CW laser light, this welded part is a position where heat is likely to escape due to heat conduction and is not easily melted. Can be imparted with sufficient melting energy to the welded part by controlling to the low speed side so that the heat is easily escaped (thermal conductivity). Thereby, the welding in the said welding site | part can be performed appropriately.

  On the other hand, when irradiating a thin welded part with CW laser light, heat is difficult to escape at the scanning speed corresponding to this welded part because the welded part is in a position where heat does not easily escape due to heat conduction. By controlling to the high-speed side so as to conform to the thermal conductivity (thermal conductivity), welding can be performed quickly and reliably, the occurrence of poor welding due to excessive heat input to the welded part, and the welding part A thermal influence on the surroundings (for example, inside the battery) can be avoided.

(Third example)
Next, in the third specific example, as the variable control of the scanning speed of the CW laser beam, the scanning speed at the welding portion where the spreading in the plane direction orthogonal to the thickness direction of the workpiece is relatively large is set to the above-mentioned spreading speed. Is controlled to be lower than the scanning speed at a welding site where the welding angle is relatively small.

Here, as shown in FIG. 5, the welded part P ₃ taken on the short straight part in the opening 20 and the welded part P ₄ taken on the long straight part in the opening 20 are welded parts P _3. , P _{4 in} the vicinity (periphery) of the workpieces 21 and 22 are different in plane area. Specifically, the direction of the plane area at the weld site P _4, greater than the plane area of the welding site P _3. Therefore, it spread in the planar direction of the object to be welded 21 and 22 in the welded portion P ₄ is thus greater than the extent of the said planar direction in the welding site P _3.

In this assumption, in the present embodiment, the predetermined speed of the scanning speed of the CW laser beam in the welding site P _4, the low-speed side in accordance with the spread in the planar direction of the object to be welded 21 and 22 in the welded portions P ₄ To control.

Predetermined contrast, the scanning speed of the CW laser beam in the welding site P _3, depending on the extent of the planar direction of the object to be welded 21 and 22 in high-speed welding site P ₃ than the scanning speed in the welding site P ₄ Control to speed.

  According to this specific example, in the welded part where the spread of the work piece in the plane direction is large, the welded part is a position where heat is easily escaped by heat conduction and is not easily melted. Is controlled to the low speed side so as to be adapted to heat being easily escaped, sufficient melting energy can be imparted to the welding site. As a result, it is possible to appropriately perform welding at the welding site.

  On the other hand, when irradiating a welded part with a small spread in the plane direction of the workpiece to be welded with CW laser light, since this welded part is a position where heat is difficult to escape due to heat conduction, it corresponds to this welded part. By controlling the scanning speed to the high speed side so that the heat is difficult to escape, welding can be performed quickly and reliably, and the occurrence of poor welding due to excessive heat input to the welding site or the A thermal influence on the periphery of the welding site can be avoided.

(Fourth specific example)
Next, in the fourth specific example, as the variable control of the scanning speed of the CW laser beam, the scanning speed in the scanning section where the welding site is displaced in a curved line is used, and the scanning speed in the scanning section where the welding site is displaced in a straight line. Control faster.

Here, as shown in FIG. 6, in the welded part P ₅ corresponding to the corner portion of the opening portion 20 and the second object to be welded 22, since the planar shape of the welded part is in an arc shape, the welding site P ₅ belongs to the scanning section welded part is displaced in a curved shape. On the other hand, as shown, the welding portion P ₆ which does not correspond to the corners, belong to a scanning section welded part is displaced linearly.

In this assumption, in the present embodiment, in the welded part P ₆ not corresponding to the corner portion, the scanning speed of the CW laser beam is controlled to a predetermined speed of the low speed side.

In contrast, in the welded part P ₅ corresponding to the corner portion, the scanning speed of the CW laser light is controlled at a high speed of a predetermined speed than the scanning speed in the welded part P ₆ which does not correspond to the corners.

  According to this specific example, the scanning speed is controlled to the high speed side in the scanning section where the welding site is displaced in a curved line. A welded part belonging to such a scanning section is a part that is not easily escaped from heat and is easily affected by heat due to welding at the immediately preceding welded part. Therefore, by controlling the scanning speed at the welding site to the high speed side, welding can be performed quickly and reliably, and the occurrence of poor welding due to excessive heat input to the welding site or around the welding site. Thermal effects can be avoided.

  On the other hand, in the scanning section in which the welding site is displaced linearly, the scanning speed is controlled to the low speed side. Since the welded part belonging to such a scanning section is a part where heat easily escapes and is not easily affected by the heat of the previous welded part, welding is performed by controlling the scanning speed corresponding to this welded part to the low speed side. Can be done appropriately.

(Fifth example)
Next, in the fifth specific example, as a variable control of the scanning speed of the CW laser light, it is arranged on the welding progress side with respect to the first welding site, and a gap (for example, between the first welding site and the like) 7, the scanning speed at the second welding site arranged in the vicinity of the first welding site so as to sandwich the symbol G) in FIG. 7 is controlled to be higher than the scanning speed at the welding site other than the second welding site. However, the first welding part is an arbitrary welding part.

  Here, although different from those shown in FIGS. 3 and 4, in this specific example, as shown in FIG. 7, for example, a part 22 a of the outer peripheral end portion of the second workpiece 22 is the first one. It can be applied to the case where the part to be welded 21 protrudes toward the opening 20 and the part on the opening 20 corresponding to the protrusion 22a is recessed.

That is, in FIG. 7, the welding parts corresponding to the upstream end and the downstream end in the welding progress direction of the protrusion 22a are the first welding part P _1st and the second welding part P _2nd , respectively. 7, in the weld portion other than the second welding portion P _2nd, to control the scanning speed of the CW laser beam at a predetermined speed of the low speed side, in the second welding portion P _2nd, scanning the CW laser beam The speed may be controlled to a predetermined speed on the high speed side.

According to this specific example, when the CW laser beam is irradiated to the second welding site P _2nd , the welding site P _2nd is affected by the heat caused by the irradiation of the CW laser beam to the _first welding site P _1st . Since it is a position where it is easy to be melted and easily melted, welding can be performed quickly and reliably by controlling the scanning speed corresponding to the second welding site P _2nd to the high speed side so as to match the high temperature. together, it is possible to avoid thermal influence on periphery of the second welding portion welded part of generation of the second welding defects due to excessive heat input to the P _2nd.

On the other hand, when the CW laser light is irradiated to a welding part other than the second welding part P _2nd , the welding part is relatively low in temperature as compared with the second welding part P _2nd, and therefore corresponds to the welding part. It is possible to perform welding appropriately by controlling the scanning speed to be low so as to match the low temperature.

  In addition, a suitable value can be set according to a concept about the upper limit of the separation distance from the 1st welding site | part used as the judgment reference | standard of whether a welding site | part corresponds to a 2nd welding site | part.

  Although the embodiments of the present invention have been described in the above first to fifth specific examples, in the present invention, by combining the first to fifth specific examples as necessary, under various conditions. Appropriate seam welding can be performed.

  For example, in the fourth specific example, the scanning speed is controlled at a high speed in the scanning section (corner portion) in which the welding part is displaced in a curved line with respect to the scanning section in which the welding part is linearly displaced. As in the example, when the thickness of the workpiece is different between the straight part and the curved part, the scanning speed condition may change. Specifically, when the thickness of the curved portion is larger than the thickness of the straight portion, the scanning section in which the welded part is displaced in a curved line with respect to the scanning section in which the welded part is linearly displaced, contrary to the fourth specific example. It is conceivable to control the scanning speed at the (corner) to be low.

  In addition, this invention is not limited to embodiment mentioned above, A various change can be made as needed.

6 Galvanometer scanner 21 First work piece 22 Second work piece

Claims (6)

A laser welding method for continuously welding the workpiece by sequentially irradiating a laser beam along a portion of the workpiece to be welded with a galvanometer scanner along the welding portion.
The laser beam is a continuous wave CW laser beam, and the scanning speed of the CW laser beam is variably controlled while the output of the CW laser beam is controlled to be constant. As the variable control of the scanning speed, the scanning speed at the welding site at the start of welding is controlled to be lower than the scanning speed at the welding site on the welding progress side with respect to the welding site at the start of welding. The laser welding method according to claim 1. 2. The variable control of the scanning speed is performed by controlling the scanning speed at the welding portion having a relatively large thickness to be lower than the scanning speed at the welding portion having a relatively thin thickness. The laser welding method described in 1. As the variable control of the scanning speed, the scanning speed at the welding portion where the spread in the plane direction orthogonal to the thickness direction of the workpiece is relatively large is used, and the scanning at the welding portion where the spread is relatively small. The laser welding method according to claim 1, wherein the laser welding method is controlled to be lower than the speed. As the variable control of the scanning speed, the scanning speed in a scanning section in which the welding part is displaced in a curved line is controlled at a higher speed than the scanning speed in a scanning section in which the welding part is displaced in a linear form. The laser welding method according to claim 1. As the variable control of the scanning speed, it is arranged on the welding progress side with respect to the first welding site, and is arranged in the vicinity of the first welding site so as to sandwich a gap portion with the first welding site. 2. The laser welding method according to claim 1, wherein the scanning speed at the second welding site is controlled to be higher than the scanning speed at the welding site other than the second welding site.

Images