Welding device and welding method

A welding device includes a laser irradiation unit that irradiates a workpiece with a laser light while scanning along an intended weld line of the workpiece, an upper jig arranged on a side of the laser irradiation unit with respect to the workpiece, and a lower jig arranged on an opposite side of the laser irradiation unit side. The upper jig includes an exposed portion that exposes the intended weld line of the workpiece to the laser irradiation unit side, an introduction path that is disposed in a downstream side in a scanning direction of the laser light and introduces an inert gas to the exposed portion, and a discharge path that is disposed in an upstream side in the scanning direction of the laser light and suctions the inert gas introduced to the exposed portion to discharge the inert gas to an outside.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese patent application JP 2018-242912 filed on Dec. 26, 2018, the content of which is hereby incorporated by reference into this application.

BACKGROUND

Technical Field

The present disclosure relates to a welding device and a welding method, in particular, relates to a welding device and a welding method for welding fuel cell separators.

Background Art

Conventionally, as a welding device that welds fuel cell separators (hereinafter simply referred to as “separators”), there has been known a welding device described in, for example, WO 2016/001992. In the welding device described in WO 2016/001992, two sheet-shaped separators in a stacked state are sandwiched between an upper sandwiching member and a lower sandwiching member, and an outer peripheral edge sandwiching member and an inner peripheral edge sandwiching member that constitute the upper sandwiching member have a clearance irradiated with a laser light, and thus, these separators are welded. The upper sandwiching member and the lower sandwiching member have respective exhaust holes. Injecting an inert gas to a weld portion via the exhaust hole removes fumes and dust generated during welding and reduces welding failure and the like caused by metal fumes and the dust.

SUMMARY

However, since the above-described welding device is insufficient in removing the fumes and the dust generated during welding, the fumes and the dust accumulate in the weld portion and its peripheral area, and thus, there remains a problem of adversely affecting a quality of laser welding.

The present disclosure has been made to solve such a technical problem, and the present disclosure provides a welding device and a welding method that reduce an accumulation of fumes and dust generated during welding to ensure an improved quality of laser welding.

A welding device according to the present disclosure includes a laser irradiation unit, a first jig, and a second jig. The laser irradiation unit irradiates a workpiece with a laser light while scanning along an intended weld line of the workpiece with the laser light. The first jig is arranged on a side of the laser irradiation unit with respect to the workpiece. The second jig is arranged on an opposite side of the laser irradiation unit side with respect to the workpiece. The second jig is capable of sandwiching the workpiece with the first jig. The first jig includes an exposed portion, an introduction path, and a discharge path. The exposed portion exposes the intended weld line of the workpiece to the laser irradiation unit side. The introduction path is disposed in a downstream side in a scanning direction of the laser light. The introduction path introduces an inert gas to the exposed portion. The discharge path is disposed in an upstream side in the scanning direction of the laser light. The discharge path suctions the inert gas introduced to the exposed portion to discharge the inert gas to an outside.

With the welding device according to the present disclosure, introducing the inert gas to the exposed portion via the introduction path of the first jig, and discharging the inert gas introduced to the exposed portion to the outside via the discharge path ensure removing fumes and dust generated during welding by pushing and flowing them to the outside, thereby ensuring a reduced accumulation of the fumes and the dust. Moreover, since the introduction path is disposed in the downstream side in the scanning direction of the laser light and the discharge path is disposed in the upstream side in the scanning direction of the laser light, interference by the fumes and the dust to the laser light can be further reduced compared with a case where the introduction path is disposed in the upstream side in the scanning direction of the laser light and the discharge path is disposed in the downstream side in the scanning direction of the laser light. As a result, the accumulation of the fumes and the dust can be surely reduced, thereby ensuring an improved quality of laser welding.

The welding device according to the present disclosure may further include a chamber mounted on the first jig so as to cover the exposed portion. The chamber communicates with the exposed portion. The chamber may include a lid body that transmits the laser light and an introduction hole formed on a sidewall to introduce the inert gas to an inside of the chamber. Accordingly, when the inert gas is introduced to the inside of the chamber via the introduction hole, the introduced inert gas flows into the inside of the exposed portion communicating with the chamber to ensure pushing and flowing an oxygen gas inside the exposed portion to the outside. This ensures lowering an oxygen concentration inside the exposed portion and ensures reducing an oxidation of a weld portion formed by welding, thereby ensuring further improved quality of laser welding. Mounting the chamber thus covering the exposed portion ensures reducing a foreign matter inclusion and the like into the exposed portion.

In the welding device according to the present disclosure, the introduction path may incline obliquely downward at an angle θ with respect to a horizontal direction from the downstream side in the scanning direction of the laser light toward the upstream side, the discharge path may incline obliquely upward at the angle θ with respect to the horizontal direction from the downstream side in the scanning direction of the laser light toward the upstream side, and the angle θ may be 0°<θ≤15°. Accordingly, a flow of the inert gas introduced to the exposed portion via the introduction path becomes a laminar flow, thereby ensuring efficiently suctioning the fumes and the dust via the discharge path without causing the fumes and the dust to attach to walls of the exposed portion, so as to discharge the fumes and the dust.

In the welding device according to the present disclosure, the introduction path and the discharge path may be oppositely disposed. This suppresses, for example, the attachment of the fumes and the dust to the walls of the exposed portion, thereby ensuring a further enhanced effect of reducing the accumulation of the fumes and the dust.

A welding method according to the present disclosure is a welding method for welding a workpiece by sandwiching the workpiece between a first jig that has an exposed portion exposing an intended weld line of the workpiece and a second jig, and irradiating the workpiece with a laser light while scanning along the intended weld line of the workpiece exposed from the exposed portion with the laser light. The welding method includes welding that includes irradiating the intended weld line of the workpiece with the laser light while introducing an inert gas to the exposed portion from a downstream side in a scanning direction of the laser light and suctioning the inert gas introduced to the exposed portion from an upstream side in the scanning direction of the laser light to discharge the inert gas to an outside.

In the welding method according to the present disclosure, since the inert gas is introduced to the exposed portion from the downstream side in the scanning direction of the laser light, and while suctioning the inert gas introduced to the exposed portion from the upstream side in the scanning direction of the laser light to discharge the inert gas to the outside, the intended weld line of the workpiece is irradiated with the laser light, the fumes and the dust generated during welding can be removed by pushing and flowing them to the outside, thereby ensuring the reduced accumulation of the fumes and the dust. Moreover, since the inert gas is introduced from the opposite direction with respect to the scanning direction of the laser light (that is, direction from downstream side toward upstream side) to push and flow the fumes and the dust, interference by the fumes and the dust to the laser light can be further reduced compared with a case where, for example, the inert gas is introduced along the scanning direction of the laser light (that is, direction from upstream side toward downstream side). As a result, the accumulation of the fumes and the dust can be reduced, thereby ensuring the improved quality of laser welding.

The welding method according to the present disclosure may further include preparing that includes sandwiching the workpiece by relatively bringing the second jig on which the workpiece is placed close to the first jig before the welding. The preparing may include introducing the inert gas to the exposed portion from the downstream side in the scanning direction of the laser light while relatively bringing the second jig close to the first jig and introducing the inert gas to an inside of a chamber that is mounted on the first jig and communicates with the exposed portion. Accordingly, when the inert gas is introduced to the inside of the chamber, the introduced inert gas flows into the inside of the exposed portion communicating with the chamber, thereby ensuring pushing and flowing the oxygen gas inside the exposed portion to the outside. Since this ensures lowering the oxygen concentration inside the exposed portion, the oxidation of the weld portion formed by welding can be reduced, thereby ensuring improved quality of laser welding. Since such a pushing and flowing operation of the oxygen gas can be performed simultaneously with the sandwiching operation of the workpiece, there is no cycle time lost in association with the pushing and flowing of the oxygen gas, thereby ensuring immediately executing the welding after sandwiching the workpiece between the first jig and the second jig. As a result, the efficiency of the welding operation can be enhanced, thereby easily achieving improved productivity.

In the welding method according to the present disclosure, the preparing may include suctioning the inert gas inside the exposed portion from the upstream side in the scanning direction of the laser light to discharge the inert gas to the outside after the workpiece is sandwiched between the first jig and the second jig. Accordingly, even if the oxygen gas remains inside the exposed portion, the remaining oxygen gas can be discharged, thereby ensuring the further enhanced effect of lowering the oxygen concentration. As a result, the improved quality of laser welding is ensured.

The present disclosure reduces the accumulation of fumes and dust generated during welding to ensure the improved quality of laser welding.

DETAILED DESCRIPTION

While the following describes an embodiment of a welding device and a welding method according to the present disclosure with reference to the drawings, before that, a structure of a workpiece to be welded is briefly described based onFIG. 1andFIG. 2.

FIG. 1is a plan view illustrating a workpiece.FIG. 2is a cross-sectional view taken along the line X-X inFIG. 1. As illustrated inFIG. 1andFIG. 2, a workpiece10according to this embodiment is two stacked separators11used for, for example, a fuel cell. The separator11is formed by press forming a metal plate material, such as stainless steel and titanium steel, such that protruding portions11aand recessed portions11bare alternately repeated. The two separators11are stacked such that the recessed portions11bof one separator11are brought into contact with the recessed portions11bof the other separator11. This forms spaces S between the protruding portions11aof one separator11and the protruding portions11aof the other separator11. This space S serves as a refrigerant flow channel for distributing a refrigerant to cool the fuel cell.

As illustrated inFIG. 1, the separator11has one end portion (right-side end portion inFIG. 1) in its longitudinal direction (that is, direction perpendicular to direction in which the protruding portions11aand the recessed portions11bare repeated) where a fuel gas inlet manifold111, a refrigerant outlet manifold112, and an oxidant gas outlet manifold113are disposed in this order. The separator11has the other end portion (left-side end portion inFIG. 1) in its longitudinal direction where an oxidant gas inlet manifold114, a refrigerant inlet manifold115, and a fuel gas outlet manifold116are disposed in this order.

The two stacked separators11are secured to one another by being welded on intended weld lines L1to L5illustrated inFIG. 1. More specifically, the intended outer periphery weld line L1is in a loop shape along a peripheral edge portion of the separator11so as to surround a portion where the protruding portions11aand the recessed portions11bare formed, the fuel gas inlet manifold111, the refrigerant outlet manifold112, the oxidant gas outlet manifold113, the oxidant gas inlet manifold114, the refrigerant inlet manifold115, and the fuel gas outlet manifold116. The intended fuel gas inlet weld line L2is formed into a loop shape so as to surround the fuel gas inlet manifold111, and the intended oxidant gas outlet weld line L3is formed into a loop shape so as to surround the oxidant gas outlet manifold113.

The intended oxidant gas inlet weld line L4is formed into a loop shape so as to surround the oxidant gas inlet manifold114, and the intended fuel gas outlet weld line L5is formed into a loop shape so as to surround the fuel gas outlet manifold116. On these intended weld lines L1to L5, weld portions (weld beads) B are formed by welding.

Welding Device

The following describes a welding device of this embodiment with reference toFIG. 3toFIG. 6.FIG. 3is a schematic diagram illustrating the welding device according to the embodiment. A welding device1of this embodiment includes a laser irradiation unit2that irradiates the workpiece10with a laser light to weld the workpiece10, an upper jig (first jig)3and a lower jig (second jig)4that sandwich the workpiece10from both upper and lower sides to secure the workpiece10, and a chamber5arranged on an upper side of the upper jig3.

The laser irradiation unit2at least includes a laser oscillator21that emits a laser light20, a lens unit23optically connected to the laser oscillator21via an optical fiber22, and a galvano scanner24that scans the laser light20. The lens unit23includes, for example, a collimator lens231and a condenser lens232.

The galvano scanner24is a device for scanning the laser light20at high speed and at an accurate position, and includes a pair of galvanometer mirrors241and242. The galvanometer mirror241and the galvanometer mirror242are supported by rotation shafts of respective motors (not illustrated). By adjusting respective reflection angles at high speed by driving of the motors ensures scanning the laser light20along the intended weld lines L1to L5at high speed.

The galvano scanner24has an output side where an Fθ lens25is arranged. The Fθ lens25is a lens to correct a scanrate of the laser light20to be constant. The lens unit23, the galvano scanner24, and the Fθ lens25are housed inside a housing26.

The upper jig3is arranged on a side of the laser irradiation unit2with respect to the workpiece10(in this embodiment, upper side of the workpiece10), and is secured to a welding workbench6, for example, by screwing in a state of being fitted in an opening of the welding workbench6. The upper jig3presents a rectangular plate shape, and has a plurality of exposed portions31that expose the intended weld lines L1to L5of the workpiece10to the laser irradiation unit2side. The exposed portions31are formed at positions, corresponding to the intended weld lines L1to L5of the workpiece10, in the upper jig3, and are formed of through grooves extending along the corresponding intended weld lines L1to L5. While in this embodiment, the exposed portions31are formed to have constant widths (that is, equal width) toward the upper side, which is the laser irradiation unit2side, the exposed portions31may be formed into taper shapes (that is, widening width) that increase widths toward the upper side.

Such an upper jig3, for example as illustrated inFIG. 4, includes a first upper jig3aand a second upper jig3b.FIG. 4is a plan view that illustrates the first upper jig and the second upper jig. InFIG. 4, the intended weld lines L1to L5of the workpiece10are indicated by two-dot chain lines in order to make correspondence relationships between the respective exposed portions31and the intended weld lines L1to L5easier to see. The first upper jig3aand the second upper jig3bare each formed into a rectangular shape, but are different in positions of the exposed portions31that expose the intended weld lines L1to L5. More specifically, the exposed portions31that expose the intended weld lines L1to L5are not formed into loop shapes similarly to the respective corresponding intended weld lines L1to L5, but the respective exposed portions31form exposed portions that expose a part of the loop-shaped intended weld lines L1to L5to the first upper jig3aand exposed portions that expose the remaining portions of the loop-shaped intended weld lines L1to L5to the second upper jig3b.

As illustrated inFIG. 3, the upper jig3has an introduction path32that introduces an inert gas to the exposed portions31, and a discharge path33that suctions the inert gas introduced to the exposed portions31to discharge the inert gas to an outside. The introduction path32is arranged in a downstream side (left side inFIG. 3) in a scanning direction F1of the laser light20with respect to the exposed portions31, and is formed of an elongate hole provided inside the upper jig3. This introduction path32has one end that communicates with a supply passage (not illustrated) that supplies the inert gas, and the other end that communicates with the exposed portions31. The inert gas here is a gas chemically stable with respect to the weld portions B formed by welding, and, for example, an argon gas, a nitrogen gas, a helium gas, a carbon dioxide gas, and a mixed gas of these gases can be included.

The discharge path33is arranged in an upstream side in the scanning direction F1of the laser light20with respect to the exposed portions31, and is formed of an elongate hole provided inside the upper jig3. The discharge path33has one end that communicates with the exposed portions31, and the other end that communicates with an outside (for example, atmosphere). In some embodiments, the introduction path32and the discharge path33are arranged oppositely one another, and are formed to be in positions at an approximately same height.

FIG. 5is an enlarged view illustrating the introduction path and the discharge path of the upper jig. As illustrated inFIG. 5, the introduction path32inclines obliquely downward at an angle θ with respect to the horizontal direction from the downstream side in the scanning direction F1of the laser light20toward the upstream side. Meanwhile, the discharge path33inclines obliquely upward at the angle θ with respect to the horizontal direction from the downstream side in the scanning direction F1of the laser light20toward the upstream side. The angle θ here means an angle formed by a center axis of the introduction path32or the discharge path33and the horizontal direction, and in some embodiments, it is 0°<θ≤15°.

The introduction path32and the discharge path33of such an inert gas are disposed for each of the exposed portions31that expose the intended weld lines L1to L5in the upper jig3. For example, as illustrated inFIG. 6, on the first upper jig3aand the second upper jig3b, an introduction path (see “In” inFIG. 6) and a discharge path (see “Out” inFIG. 6) are each formed for each of the exposed portions31. The introduction path is positioned in the downstream side in the scanning direction of the laser light to introduce the inert gas to the exposed portion31. The discharge path is positioned in the upstream side in the scanning direction of the laser light to suction the inert gas introduced to the exposed portion31to discharge the inert gas to the outside.

Meanwhile, the lower jig4is arranged in an opposite side (lower side of the workpiece10in this embodiment) of the laser irradiation unit side with respect to the workpiece10, and is constituted to be able to sandwich the workpiece10with the upper jig3. Specifically, the lower jig4is formed into a rectangular plate shape, is arranged at a position opposite to the upper jig3secured to the welding workbench6, and is constituted such that the lower jig4is brought close and move away with respect to the upper jig3by an elevating device7.

The chamber5is arranged in an upper side of the upper jig3so as to cover the exposed portions31and communicates with the exposed portions31. This chamber5includes a hollow tubular body51and a lid body52that transmits the laser light20. The hollow tubular body51is formed of, for example, a resin material, and is mounted on the upper jig3by, for example, screwing. The lid body52is formed of, for example, a transparent glass plate, and is secured to the hollow tubular body51by, for example, screwing. The hollow tubular body51has a sidewall where an introduction hole53that introduces the inert gas to an inside of the chamber5is formed. The introduction hole53is arranged in the downstream side in the scanning direction F1of the laser light20and at a position close to the lid body52on the sidewall of the hollow tubular body51.

In the welding device1constituted as described above, the upper jig3includes the exposed portions31that expose the intended weld lines L1to L5of the workpiece10to the laser irradiation unit2side, the introduction path32that is disposed in the downstream side in the scanning direction F1of the laser light20and introduces the inert gas to the exposed portion31, and the discharge path33that is disposed in the upstream side in the scanning direction F1of the laser light20and suctions the inert gas introduced to the exposed portion31to discharge the inert gas to the outside. Thus, the inert gas can be introduced to the exposed portion31via the introduction path32, and further, the inert gas introduced to the exposed portion31can be suctioned to be discharged to the outside as indicated by an arrow F2inFIG. 3. This ensures removing fumes and dust generated during welding by pushing and flowing the fumes and the dust to the outside, thereby ensuring reduced accumulation of the fumes and the dust in the exposed portion31.

Moreover, the introduction path32is disposed in the downstream side in the scanning direction F1of the laser light20, and the discharge path33is disposed in the upstream side. Thus, the inert gas can be introduced to the exposed portion31from the opposite direction in the scanning direction F1of the laser light20, and the fumes and the dust generated during welding can be pushed and flown. This ensures further reduced interference by the fumes and the dust to the laser light compared with a case where, for example, the introduction path is disposed in the upstream side in the scanning direction F1of the laser light20and the discharge path is disposed in the downstream side in the scanning direction of the laser light. As a result, the accumulation of the fumes and the dust can be surely reduced, thereby ensuring an improved quality of laser welding.

The introduction path32inclines obliquely downward at the angle θ with respect to the horizontal direction from the downstream side in the scanning direction F1of the laser light20toward the upstream side, the discharge path33inclines obliquely upward at the angle θ with respect to the horizontal direction from the downstream side in the scanning direction F1of the laser light20toward the upstream side, and the angle θ is 0°<θ≤15°. This causes the flow of the inert gas introduced to the exposed portion31via the introduction path32to become a laminar flow, thereby ensuring efficiently suctioning the fumes and the dust to discharge the fumes and the dust to the outside via the discharge path33without allowing the fumes and the dust to attach to walls of the exposed portion31.

Furthermore, the introduction path32and the discharge path33are arranged oppositely one another. Thus, for example, the attachment of the fumes and the dust to the walls of the exposed portion31is suppressed, thereby ensuring a further enhanced effect of reducing the accumulation of the fumes and the dust.

Furthermore, the chamber5that communicates with the exposed portions31is mounted on the upper side of the exposed portions31. Thus, a foreign matter inclusion and the like into the exposed portions31can be reduced. The introduction hole53that introduces the inert gas to the inside of the chamber5is formed on the sidewall of the hollow tubular body51in the chamber5. Thus, for example, when the inert gas is introduced to the inside of the chamber5via the introduction hole53, the introduced inert gas flows into the exposed portions31that communicate with the chamber5, thereby ensuring pushing and flowing the oxygen gas inside the exposed portions31to the outside. As a result, an oxygen concentration inside the exposed portions31can be lowered and the oxidation of the weld portion formed by welding can be reduced, thereby ensuring the improved quality of laser welding.

Welding Method

The following describes a welding method according to this embodiment with reference toFIG. 7andFIG. 8. InFIG. 7andFIG. 8, the laser irradiation unit2is omitted. The welding method in this embodiment at least includes a preparation step and a welding step.

In the preparation step, first, the upper jig3is secured to the welding workbench6, the chamber5is installed on the upper side of the upper jig3so as to cover the exposed portions31of the upper jig3, and the chamber5is mounted on and secured to the upper jig3by, for example, screwing. Subsequently, two separators11are placed in sequence on an upper surface of the lower jig4to position the two separators11, thus preparing the workpiece10. Here, the preparation operation of the workpiece10may be performed prior to the securing operation of the upper jig3.

Next, while relatively bringing the lower jig4close to the upper jig3and introducing the inert gas to the inside of the chamber5that is mounted on the upper jig3and communicates with the exposed portions31, the inert gas is introduced to the exposed portions31from the downstream side in the scanning direction F1of the laser light20. Specifically, as illustrated inFIG. 7, elevating the lower jig4by the elevating device7brings the lower jig4close to the upper jig3. Simultaneously with this, while introducing the inert gas to the inside of the chamber5via the introduction hole53of the chamber5, the inert gas is introduced to the exposed portions31via the introduction path32of the upper jig3.

When the inert gas is introduced to each of the inside of the chamber5via the introduction hole53of the chamber5and the exposed portions31via the introduction paths32of the upper jig3, the suction of the inert gas via the discharge paths33is not performed. Specifically, covering the discharge path33using, for example, a blocking member blocks the inert gas from flowing outside via the discharge path33.

With this, the inert gas introduced to the inside of the exposed portion31via the introduction path32of the upper jig3does not flow to the discharge path33as indicated by the arrow F2inFIG. 7, but flows outside passing through a clearance between the upper jig3and the workpiece10placed on the lower jig4. Meanwhile, the inert gas introduced to the inside of the chamber5via the introduction hole53flows into the exposed portions31of the upper jig3communicating with the chamber5as indicated by an arrow F3inFIG. 7, and furthermore, flows outside passing through the clearance between the upper jig3and the workpiece10placed on the lower jig4. Such a flow of the inert gas causes the oxygen gas inside the chamber5and the exposed portions31to be pushed and flown to the outside by the inert gas.

When the workpiece10placed on the lower jig4is brought into contact with a bottom surface of the upper jig3, and is pressurized by the upper jig3and the lower jig4at a predetermined value, the elevation of the elevating device7stops. This sandwiches the workpiece10between the upper jig3and the lower jig4.

In the preparation step, after sandwiching the workpiece10between the upper jig3and the lower jig4, furthermore, the inert gas inside the exposed portions31is suctioned from the upstream side in the scanning direction F1of the laser light20to be discharged to the outside.

That is, as illustrated inFIG. 8, when the workpiece10is sandwiched by the upper jig3and the lower jig4, the suctioning operation via the discharge path33is performed. This discharges the inert gas introduced to the inside of the exposed portions31via the introduction path32of the upper jig3to the outside via the discharge path33as indicated by the arrow F2inFIG. 8. Meanwhile, the inert gas introduced to the inside of the chamber5via the introduction hole53flows into the exposed portions31of the upper jig3communicating with the chamber5as indicated by the arrow F3inFIG. 8, and furthermore, is discharged to the outside via the discharge path33.

In the welding step continuous with the preparation step, the inert gas is introduced to the exposed portions31of the upper jig3from the downstream side in the scanning direction F1of the laser light20, and while suctioning the inert gas introduced to the exposed portions31from the upstream side in the scanning direction F1of the laser light20to discharge the inert gas to the outside, the intended weld lines L1to L5of the workpiece10is irradiated with the laser light20. That is, as illustrated inFIG. 3, while introducing the inert gas to the inside of the exposed portion31via the introduction path32and discharging the introduced inert gas to the outside via the discharge path33, the workpiece10is scanned to be irradiated with the laser light20along the intended weld lines L1to L5of the workpiece10exposed from the exposed portions31of the upper jig3, thereby welding the workpiece10. This forms the weld portions (weld beads) B on the workpiece10, and thus, the separators11that constitute the workpiece10are secured to one another.

In this welding step, the introducing operation of the inert gas into the chamber5performed in the preparation step may be executed or may be stopped. When the introducing operation of the inert gas into the chamber5via the introduction hole53is executed, the effect (details will be described below) that lowers the oxygen concentration inside the exposed portions31can be further enhanced. Furthermore, in some embodiments, the introducing operation of the inert gas into the chamber5via the introduction hole53is executed until the lower jig4descends after the termination of the welding step. Accordingly, the oxygen concentration in the peripheral area of the weld portion can be maintained to a determined standard value, thereby ensuring suppressing the oxidation of the weld portion immediately after welding.

The above-described welding operation is performed along all the intended weld lines L1to L5. As described above, when the upper jig3has two jigs (the first upper jig3aand the second upper jig3b), the welding operation is divided into a first welding operation that uses the first upper jig3aand a second welding operation that uses the second upper jig3b. In this case, for example, after the first welding operation is terminated, the lower jig4is once caused to descend, and a replacement of the upper jig3(that is, replacing to the second upper jig3bfrom the first upper jig3a) is performed. Then, it is only necessary to repeatedly execute the above-described preparation step and the welding step.

According to the welding method according to this embodiment, in the preparation step, while relatively bringing the lower jig4on which the workpiece10is placed close to the upper jig3, the inert gas is introduced to the inside of the chamber5via the introduction hole53and the inert gas is introduced into the exposed portion31from the downstream side in the scanning direction F1of the laser light20via the introduction path32. When the inert gas is introduced to the inside of the chamber5, the introduced inert gas flows into the inside of the exposed portions31communicating with the chamber5, thus ensuring pushing and flowing the oxygen gas inside the exposed portions31to the outside. This ensures lowering the oxygen concentration inside the exposed portions31, thereby ensuring a reduced oxidation of weld portion B formed by welding and ensuring the improved quality of laser welding.

Also, the pushing and flowing operation of the oxygen gas can be thus performed simultaneously with the sandwiching operation of the workpiece10, therefore, there is no cycle time lost in association with the pushing and flowing of the oxygen gas, thereby ensuring immediately executing the welding step after sandwiching the workpiece10between the upper jig3and the lower jig4. As a result, the efficiency of the welding operation can be enhanced, thereby easily achieving improved productivity.

Furthermore, in the preparation step, after sandwiching the workpiece10between the upper jig3and the lower jig4, an operation that suctions the inert gas inside the exposed portions31from the upstream side in the scanning direction F1of the laser light20to discharge the inert gas to the outside is further performed. Accordingly, if the oxygen gas remains inside the exposed portions31or if the oxygen gas remains inside the discharge paths33, the remaining oxygen gas is pushed and flown to the outside by the inert gas. Therefore, the effect of lowering the oxygen concentration can be further enhanced.

Also, in the welding step, the inert gas is introduced to the exposed portion31from the introduction path32disposed in the downstream side in the scanning direction F1of the laser light20, and while suctioning the inert gas introduced to the exposed portion31from the discharge path33disposed in the upstream side in the scanning direction of the laser light20to discharge the inert gas to the outside, the intended weld lines L1to L5of the workpiece are irradiated with the laser light20, thereby pushing and flowing the fumes and the dust generated during welding to ensure removing them. Therefore, the accumulation of the fumes and the dust can be reduced.

Moreover, since the fumes and the dust are pushed and flown by introducing the inert gas from the opposite direction with respect to the scanning direction F1of the laser light20, interference by the fumes and the dust to the laser light can be further reduced compared with a case where, for example, the inert gas is introduced along the scanning direction of the laser light. As a result, the accumulation of the fumes and the dust can be surely reduced, thereby ensuring the improved quality of laser welding.

While the embodiment of the present disclosure has been described in detail above, the present disclosure is not limited thereto, and can be subjected to various kinds of changes in design without departing from the spirit and scope of the present disclosure described in the claims. For example, while in the above-described embodiment, the description has been made with an example of the separator as the workpiece, the present disclosure is applied to welding of a workpiece other than the separator. While in the above-described embodiment, the description has been made of the welding of two separators in a stacked state, that is, stack welding, the present disclosure is also applied to butt welding, fillet welding, and the like.

Furthermore, while in the above-described embodiment, the description has been made with an example where the first jig is arranged on the upper side of the workpiece, and the second jig is arranged on the lower side of the workpiece, the first jig and the second jig are not limited to be arranged on both the upper and lower sides of the workpiece, but, for example, they may be arranged on both right and left sides with respect to the workpiece. As a method for relatively bringing the lower jig on which the workpiece is placed close to the upper jig, the upper jig may be caused to descend, besides the elevation of the lower jig by the above-described elevating device.

DESCRIPTION OF SYMBOLS