JP2008161936A - Laser welding method for surface treated steel sheet, fixing apparatus for bead-shaped gap material used therefor, and laser welding implement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser welding method for a surface treated steel sheet by which a required quantity of a bead-shaped gap material is designed to stay in a weld zone. <P>SOLUTION: On a lower base material W1 and near a position to be a weld line, there is applied the bead-shaped gap material 1 together with a rustproof oil 2 of high viscosity, with the bead-like gap material 1 fixedly held by the viscosity of the rustproof oil 2. On top of these, an upper base material W2 is superimposed and welded by emitting a laser beam L, with a gap G secured equivalent to the bead-like gap material 1. Since the bead-shaped gap material 1 is fixedly held with the rustproof oil 2, the bead-shaped gap material 1 is prevented from rolling even where the base materials W1, W2 show a complicated three-dimensional configuration. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser welding method of a surface-treated steel sheet and a fixing device for a bead-shaped gap material used therefor, in particular, when performing laser welding under a plate set in which plated steel sheets such as galvannealed steel sheets overlap. In order to prevent secondary problems due to evaporation of the plating layer, a predetermined gap is secured by sandwiching a bead-like gap material between the base materials to be welded, and the generated steam is evacuated so that entrainment in the molten part can occur. The present invention relates to a laser welding method of a surface-treated steel sheet that can prevent and perform sound welding, a fixing device for a bead-like gap material used therefor, and a laser welding jig.

  When laser welding is performed in the form of a so-called lap joint after stacking two or more base materials, if the surface of the lower base material is a plated steel plate, the plating layer will evaporate due to heat during welding and gas This remains as bubbles in the weld bead, resulting in a decrease in weld strength.

As a countermeasure, it is effective to provide a gap between the base materials to be welded to positively discharge the bubbles generated during welding to the outside. However, if the gap is too large, the base materials are welded to each other. Therefore, for example, as described in Patent Document 1, a bead-like gap material is interposed in the overlapping portion of the weld base materials, and in this state, the base materials including the bead-like gap material are added from above and below. A method of managing the size of the gap between the welded base materials by pressing is considered.
Japanese Patent Laid-Open No. 8-1411761

  However, in the technique described in the above-mentioned Patent Document 1, if a welding base material is overlapped after applying a solvent mixed with a bead-shaped gap material in advance, the solvent is evaporated in that state prior to actual welding ( A drying step that volatilizes) is essential, which increases the number of steps and increases the cost, which is not preferable.

  Moreover, in the technique described in Patent Document 1, the bead-shaped gap material itself is easy to roll, so the fixability of the bead-shaped gap material is poor. For example, when the welding base material is a complicated three-dimensional body panel, The bead-like gap material rolls between the application of the solvent mixed with the bead-like gap material and welding, and it is difficult to keep the required amount of the bead-like gap material in the required part, so that it has a sufficient effect. I can't expect.

  For example, if the fixing amount of the beaded gap material is small, a gap of the required size cannot be secured between the base materials, and porosity is still generated. The weld bead is perforated and defects such as irregularities occur, and the required welding strength cannot be ensured.

  The present invention has been made by paying attention to such a problem, and it is necessary to fix the bead-like gap material, that is, a necessary part, while assuming the use of a bead-like gap material that is easy to roll as in the prior art. It is an object of the present invention to provide a laser welding method for a surface-treated steel sheet and a fixing device for the bead-shaped gap material used therefor, which are considered so that a small amount of the bead-shaped gap material can be kept.

  The present invention is a method of performing laser welding in the form of a lap joint after superposing at least two base materials including the surface-treated steel sheet so that the surface-treated steel sheet is on the lower side. After fixing the material on the lower base material with the viscosity of the non-volatile viscous fluid, superimpose the upper base material from above and irradiate the laser beam from the upper base material side. Laser welding is performed.

  According to the present invention, since the bead-shaped gap member is fixed and held with the viscosity of the non-volatile viscous fluid, there is no need for a drying step as in the prior art, so there is no increase in the number of steps and an increase in cost. In addition, even if the base material has a complicated three-dimensional shape, it is possible to suppress the rolling of the bead-like gap material and keep the necessary amount of bead-like gap material in the necessary part, By using the bead-like gap material, the gap between the welded base materials can be surely secured, and the occurrence of porosity and the occurrence of insufficient weld strength can be prevented and the welding quality can be improved.

  1 and the following drawings are diagrams showing a more specific embodiment of the laser welding method according to the present invention, and particularly FIG. 1 schematically shows a laser welding procedure.

  Here, a case where two base materials W1 and W2 are continuously welded in the form of a lap joint using a surface-treated steel plate, for example, an alloyed hot-dip galvanized steel plate as a base material, is shown prior to actual welding. The means for securing a minute gap between the two base materials W1, W2 is characteristic.

  First, as shown in FIG. 2A, a glass bead or a steel bead having a uniform diameter of at least a predetermined range along the weld line is formed on the lower base material W1 prior to welding. In order to fix and hold the bead-shaped gap material 1, for example, a relatively high-viscosity viscous rust preventive oil 2 is uniformly applied as a non-volatile viscous fluid on the lower base material W 1 and applied. The bead-shaped gap material 1 is uniformly mixed in the rust preventive oil 2 and fixed and held.

  More specifically, as shown in FIG. 2, a rust preventive oil 2 mixed with a bead-shaped gap material 1 is stored in a tank 3 in advance, and is held by a robot arm 5 of a sealing robot (industrial robot) 4. The rust preventive oil 2 containing the bead-shaped gap material 1 is sprayed from the applied gun 6 to uniformly apply the rust preventive oil 2 including the bead-shaped gap material 1 on the lower base material W1. Alternatively, as shown in FIG. 3, the rust preventive oil 2 is applied on the lower base material W1 by the oil application roller 13 of the gap material fixing device 10, and then the applied rust preventive oil 2 is applied. The bead-shaped gap material 1 is uniformly spread by the gap material spreading roller 14. The details of the gap material fixing device 10 will be described later.

  By fixing and holding the bead-like gap material 1 with the viscosity of the rust preventive oil 2 in this way, even if the lower base material W1 has a complicated three-dimensional shape, for example, The rolling of the bead-shaped gap material 1 can be prevented in advance, and the necessary amount of the bead-shaped gap material 1 can be kept at a predetermined position until welding.

  When the bead-shaped gap material 1 is fixed and held on the lower base material W1, the upper base material W2 is overlaid from above, as shown in FIG. A large number of bead-shaped gap members 1 are interposed between the two base materials W1 and W2 together with the rust preventive oil 2. At this time, since a large number of bead-shaped gap materials 1 on the lower base material W1 are fixed and held at the viscosity of the rust preventive oil 2 in advance, even if the upper base material W2 is superposed, The bead-like gap material 1 is stationary, and the bead-like gap material 1 is directly interposed between the upper and lower base materials W1 and W2, so that a predetermined gap G corresponding to the diameter of the bead-like gap material 1 is vertically moved. Are secured between the base materials W1 and W2.

  In this state, as shown in FIG. 5C, if the base materials W1, W2 and the laser processing head 7 are relatively moved so that, for example, the base materials W1, W2 side is set to the fixed side, the laser processing head 7 is moved. By continuously moving at a predetermined speed and irradiating the laser beam L from the upper base material W2 side, the base materials W1 and W2 are welded together.

  More specifically, for example, as shown in FIG. 4, a pressurizing pin 9 is attached to a laser processing head 7 provided to a robot arm 8 of a welding robot in advance, and upper and lower base materials W1, W2 are added to each other. The base materials W1 and W2 are welded together by moving the laser beam L so as to follow the pressure position by applying pressure with the pressure pin 9. Note that the pressure pin 9 is not necessary when laser welding is performed in a state where the vicinity of the weld line is pressure-restrained by another clamping means.

  In this case, since the base materials W1 and W2 to be welded are alloyed hot-dip galvanized steel sheets, the plating layers on the surfaces of the base materials W1 and W2 are melted with the melting of the base materials W1 and W2 in the welded portion. As is well known, gas is generated by evaporation, but these gases are smoothly discharged to the outside through a gap G secured in advance between the base materials W1 and W2, so that the weld bead portion There will be no problems such as porosity and non-welding.

  Here, if the amount of the bead-shaped gap material 1 interposed between the upper and lower base materials W1 and W2 is too small, a necessary gap G can be secured over the entire length of the weld bead between the base materials W1 and W2. However, if the amount of the bead-like gap material 1 is too large, the weld bead is similarly perforated and defects such as irregularities are generated to ensure the necessary welding strength. Since it may become impossible, the amount of the bead-like gap material 1 to be interposed between the upper and lower base materials W1 and W2 shall be quantitatively grasped in advance by performing a test or the like.

  Further, if the melting point of the bead-shaped gap material 1 used is extremely lower than that of the base materials W1 and W2, it may be scattered during welding to generate holes, and bubbles such as porosity may remain in the weld bead. On the other hand, if the melting point of the bead-like gap material 1 is too high compared to the base materials W1 and W2, the bead-like gap material 1 will not melt and remain in the form of particles in the weld bead. It causes a decrease. If the melting point of the bead-like gap material 1 is approximately the same as that of the base materials W1 and W2, the bead-like gap material 1 can be melted into the weld bead, thereby preventing a decrease in welding strength. For this reason, the bead-shaped gap material 1 to be used is desirably a material whose melting point is higher than that of iron as the base materials W1 and W2, and for example, glass beads (melting point is about 1700 ° C.) are used.

  Further, for example, in the case of an automobile body panel, if the size of the gap G secured between the upper and lower base materials W1 and W2 is about 0.1 to 0.3 mm (base material plate thickness × 0.4), the plating layer Therefore, the diameter of the glass beads used as the bead-shaped gap material 1 is, for example, about 0.1 to 0.3 mm and the variation is as much as possible. Use the one without.

  On the other hand, as the non-volatile viscous fluid used for fixing and holding the bead-shaped gap material 1 as described above, for example, even when the lower base material W1 has a complicated three-dimensional shape, the bead-shaped gap fluid is used. What is necessary is just to have a function of preventing the rolling of the material 1 and keeping it in a fixed position. For example, a viscous rust preventive oil 2 having a relatively high viscosity as exemplified above is used. The use of the rust preventive oil 2 has an advantage that the rust preventive properties of the base materials W1 and W2 can be secured even when the plating layer is scattered and disappears during welding. However, among viscous fluids, for example, an adhesive is excellent in fixing and retaining properties of the bead-like gap material 1, but it is burned by heat at the time of welding and gas is generated, which may cause a hole in the weld bead. Because there is, it is not preferable.

  Here, the gap material fixing device 10 shown in FIG. 3 will be described in detail. The gap material fixing device 10 is assumed to be provided on a robot arm 11 such as a sealing robot (industrial robot). An oil application roller 13 which is a fluid application roller (fluid application means) for applying the rust preventive oil 2 as a nonvolatile viscous fluid to the frame 12 as a support to be supported by 11. And a gap material spreading roller 14 as a gap material spreading means for spreading glass beads as the bead-like gap material 1 are supported together.

  The oil application roller 13 is rotatably supported at the lower portion of the frame 12, and a predetermined amount of the rust preventive oil 2 is stored in advance in the roller 13 itself, or is prevented from a rust preventive oil supply source (not shown). Rust oil is supplied, and by rolling on the lower base material W1, rust preventive oil is leached from the surface of the roller 13 and the rust preventive oil 2 is evenly distributed on the base material W1. It has the function to apply to.

  On the other hand, the gap material spreading roller 14 is supported at a position higher than the oil application roller 13 in the frame 12, and an endless winding transmission such as a chain spanned between the oil application roller 13 as will be described later. The oil application roller 13 is driven to rotate synchronously via the means 15.

  More specifically, the gap material spreading roller 14 includes a bottomed cylindrical outer cylinder 16 and a bead-like gap material 1 such as glass beads that can be inserted into the outer cylinder 16 as shown in FIGS. A cylindrical inner cylinder 17 that functions as a storage container and an end cap 18, and a bead-shaped gap material 1 such as a predetermined amount of glass beads is accommodated in the inner cylinder 17 in advance. The outer cylinder 16 is formed with a downward opening 19 along the longitudinal direction. On the cylindrical surface of the inner cylinder 17, a large number of holes 20 through which the bead-like gap material 1 can pass are randomly or regularly. The outer cylinder 16 is formed on the fixed side, and the inner cylinder 17 is rotationally driven with respect to the outer cylinder 16, so that the opening 19 on the outer cylinder 16 side and any hole 20 on the inner cylinder 17 side The bead-shaped gap material 1 flows out from the gap material spreading roller 14 on the condition that the above conditions are met.

  As shown in FIG. 3, a diffusion plate 21 is attached below the gap material spreading roller 14 in the frame 12, and the bead-like gap material 1 immediately after flowing out from the gap material spreading roller 14 is used as the diffusion plate. 21, the bead-like gap material 1 can be spread and spread on the lower side of the gap material spreading roller 14.

  Therefore, as shown in FIG. 3, the oil application roller 13 is placed on the lower side while the frame 12 is inclined so that the gap material spreading roller 14 is located above the oil application roller 13 and on the rear side in the traveling direction. The base material W1 is lightly pressed to roll on the lower base material W1, and the antirust oil 2 is applied continuously and uniformly to the lower base material W1.

  As the oil application roller 13 rolls, the gap material spreading roller 14 rotates synchronously, that is, the inner cylinder 17 rotates synchronously with the outer cylinder 16 of the gap material spreading roller 14. The internal bead-shaped gap material 1 flows out by a predetermined amount. The bead-shaped gap material 1 that has flowed out of the gap material spreading roller 14 spreads by contacting the diffusion plate 21, and is randomly spread on the rust preventive oil 2 that has been previously applied. It is fixed and held on the lower base material W1 with viscosity.

  In this case, by adjusting the speed ratio between the oil application roller 13 and the gap material spreading roller 14, the amount of flow of the bead-like gap material 1 and thus the quantity of the bead-like gap material 1 spread to the lower base material W1 is controlled. Is possible.

  Here, in the example of FIG. 2, a rust preventive oil 2 as a non-volatile viscous fluid mixed with a bead-shaped gap material 1 is stored in a tank 3 in advance and applied to the robot arm 5 of the sealing robot 4. The rust preventive oil 2 containing the bead-shaped gap material 1 is sprayed from the gun 6 and the rust preventive oil 2 including the bead-shaped gap material 1 is applied to the lower base material W1. As explained in

  On the other hand, the rust preventive oil 2 is precipitated and separated in the tank 3 due to the difference in specific gravity with the bead-like gap material 1 depending on the type, particularly the viscosity, and is stirred by the stirring means. You may have to do that.

  Therefore, as the non-volatile viscous fluid, instead of the rust preventive oil 2, it is more preferable to use a gel-like organic material or oil and fat, such as oil and fat having a large viscosity and heat capacity such as petrolatum, paraffin wax and glycerin. desirable. The reason is that the larger the viscosity and the heat capacity, the more advantageous in suppressing the generation of steam from the plating layer in the weld zone.

  FIG. 7 shows a specific example of the second embodiment, in which a gel-like oil and fat 22 mixed with a bead-like gap material 1 such as glass beads is stored in a tank 3. The gel-like oil / fat 22 mixed with the bead-like gap material 1 is put into the gel-like oil / fat 22 having a large viscosity and heat capacity such as petrolatum, paraffin wax, glycerin and the like described above. Then, the bead-shaped gap material 1 is uniformly dispersed as a whole by stirring or kneading and emulsifying. When the gel-like oil / fat 22 is used as the non-volatile viscous fluid in this manner, the viscosity of the oil / fat 22 itself is large as shown in FIG. Thus, the bead-like gap material 1 does not settle and separate, and it is possible to maintain an even dispersion state.

  More specifically, as shown in FIG. 7, the application gun 26 is supported via the bracket 23 simultaneously on the robot arm 5 that supports the laser processing head 7 similar to that shown in FIG. The nozzle 24 is configured to be extendable and contractible. Reference numeral 25 denotes an air nozzle for scattering and removing products generated during welding by laser beam irradiation.

  From the tank 3 to the coating gun 26, the gel-like oil / fat 22 in which the bead-like gap material 1 is mixed in advance is pumped by the pump 27, while prior to welding by the laser processing head 7, the lower mother On the material W1, the gel-like fats and oils 22 are discharged and applied from the nozzle 24 of the application gun 26 along the weld line. In this case, it is desirable to extend the nozzle 24 and apply the nozzle 24 closer to the lower base material W1 in order to accurately apply the gel-like oil 22 along the weld line.

  Thus, even if the lower base material W1 exhibits a complicated three-dimensional shape by fixing and holding the bead-shaped gap material 1 on the lower base material W1 with the gel-like oils and fats 22, for example. Needless to say, it is possible to prevent the rolling of the bead-shaped gap material 1 on the base material W1, and to keep the necessary amount of the bead-shaped gap material 1 at a predetermined position until welding. .

  Here, when the welding line W · L is linear as shown in FIG. 8, the application locus of the gel-like oil / fat 22 applied on the lower base material W1 is the welding line W · L. It is desirable to substantially match L. The reason for this is that when the upper base material W2 is overlaid and pressed on the lower base material W1 coated with the gel-like oil and fat 22, as shown in FIG. Then, the bead-like gap material 1 contained in the gel-like oil 22 is also spread around the weld line W · L in order to spread around the circumference. As a result, a uniform gap can be secured around the weld lines W and L by dispersing the bead-like gap material 1.

  For the same reason, when the weld line W · L is arcuate as shown in FIG. 9, the bead-like gap material 1 is premixed in the center of the portion surrounded by the weld line W · L. When the upper base material W2 is superimposed on the lower base material W1 and pressed, the gel-like fat and oil 22 including the bead-like gap material 1 is welded to the weld line W. It is desirable to expand substantially concentrically with L.

  FIG. 10 shows a modification of the coating gun 26 as a third embodiment, and a coating gun as a coating means for a laser welding jig 30 for pressurizing and clamping the upper and lower base materials W1, W2. 36 is incorporated.

  In the case of this laser welding jig 30, the lower base material W <b> 1 and the upper base material W <b> 2 are superposed on each other as a set of two sheets and are put into the jig 30 from the previous step. The base materials W1 and W2 are placed on the work base 31 which is the base of the jig 30 and positioned.

  The work base 31 is provided with clamp mechanisms 32 on the left and right sides as clamping means for pressing the upper base material W2 against the lower base material W1. The clamp mechanism 32 is a mechanism in which a substantially L-shaped clamp arm 34 supported by the work base 31 via a link 33 swings and displaces according to the expansion and contraction operation of the clamp cylinder 35 to perform clamping and unclamping operations. A clamp 37 is attached to the tip of the clamp arm 34 via a spherical joint 38, and an electromagnet is embedded in the clamp 37. The stopper 37 has a spherical joint 38, so that a so-called swinging operation or swinging operation is possible.

  On the work base 31, as will be described later, an application gun 36 that can enter and retreat into a gap formed between the upper and lower base materials W1 and W2 is disposed. The coating gun 36 can be moved into and out of the gap between the upper and lower base materials W1 and W2 as described above, for example, with a swing motion around the vertical axis, and the nozzle 39 itself can telescopically expand and contract. It has become. In addition, the supply form of the gel-like fats and oils 22 containing the bead-like gap material 1 to the coating gun 36 is the same as in the case of FIG.

  In the example of the laser welding jig 30, the clamp base 34 of the clamp mechanism 32 is unclamped and retracted to a position where it does not hinder the insertion of the base materials W1 and W2, The base materials W1 and W2 in a set of two pieces are put in and positioned by handling means (not shown). At this time, the application nozzle 36 is also retracted to a position where it does not become an obstacle to the introduction of the base materials W1 and W2.

  When the base materials W1 and W2 are positioned on the work base 31, the clamp mechanism 32 performs a clamping operation, and only the upper base material W2 is attracted and supported by the attracting force of the electromagnet by the metal pad 37 at the tip of the clamp arm 34. After that, it is slightly displaced again in the unclamping direction, lifted up by a predetermined amount to stop the upper base material W2, and then stops. As a result, the upper base material W2 is separated from the lower base material W1, and a predetermined gap is secured between them. It should be noted that the size of the gap may be a size that allows the nozzle 39 of the previous application gun 36 to enter.

  Thus, when a predetermined gap is secured between the upper and lower base materials W1 and W2, the nozzle 39 of the application gun 36 enters the gap and forms a weld line on the lower base material W1. In accordance with the expansion and contraction operation of the nozzle 39, the gel-like oil and fat 22 containing the bead-shaped gap material 1 is applied.

  When the gel-like oil / fat 22 is applied, the application gun 36 is retracted, and the clamp arm 34 is again clamped to press the upper side of the base material W2 on the lower side of the base material W1. As a result, the clamping of the upper and lower base materials W1, W2 is completed, and the gel-like oil and fat 22 containing the bead-like gap material 1 interposed between the upper and lower base materials W1, W2 is expanded. Is welded by the laser processing head 7.

  As described above, in the case of the laser welding jig 30 shown in FIG. 10, the clamp mechanism 32 also serves as a mechanism for substantially lifting only the upper base material W2, and particularly the upper side by the clamp arm 34. The lift-up and lift-down operations of the base material W2 can be easily handled by using, for example, a multistage cylinder as the clamp cylinder 35.

  In addition to using an electromagnet embedded in the metal pad 37 at the tip of the clamp arm 34 to lift and support the upper base material W2, it is possible to use a vacuum cup or the like. For example, the lift-up means by the vacuum cup may be independent from the clamping mechanism. For example, if the upper base material W2 is lifted up by a predetermined amount by a vacuum cup independent from the clamp mechanism, the upper base material W2 is lifted down by the clamping operation of the clamp arm 34. Also good.

  In each of the embodiments described above, an alloyed hot-dip galvanized steel sheet has been described as an example of the surface-treated steel sheet. However, in addition to the plated steel sheet, the present invention is also applied to a surface-treated steel sheet that has been subjected to various coatings, coatings, and the like. Is possible.

  Furthermore, the present invention can also be applied to a so-called hybrid welding method using both laser welding and MIG welding.

It is a figure which shows the 1st Embodiment of this invention, and is process explanatory drawing which shows the procedure of laser welding. Structure explanatory drawing which shows an example of the apparatus for apply | coating the antirust oil containing the bead-like gap material used by (A) of FIG. The structure explanatory drawing of the gap | interval material fixing apparatus used for application | coating of the antirust oil similarly used for FIG. 1 (A), and dispersion | distribution of a bead-like gap material. Explanatory drawing which shows the detail of the laser processing head used by (C) of FIG. FIG. 4 is an exploded perspective view of a gap material spreading roller in the gap material fixing apparatus shown in FIG. 3. Sectional explanatory drawing of the gap | interval material dispersion | distribution roller in the gap | interval material fixing apparatus similarly shown in FIG. It is a figure which shows the 2nd Embodiment of this invention, and is a structure explanatory drawing of the application | coating gun for apply | coating the gel-like fats and oils containing a bead-like gap material. Explanatory drawing which shows an example of the application form of the gel-like fats and oils containing bead-like gap material. Explanatory drawing which shows another example of the application form of the gel-like fats and oils containing bead-like gap material. It is a figure which shows the 3rd Embodiment of this invention, and is explanatory drawing which shows an example of the jig | tool for laser welding incorporating the coating gun for apply | coating the gel-like fats and oils containing a bead-like gap material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bead-like gap material 2 ... Rust prevention oil as a non-volatile viscous fluid 4 ... Sealing robot 5 ... Robot arm 6 ... Coating gun 7 ... Laser processing head 8 ... Robot arm 10 ... Gap material fixing device 11 ... Robot arm 12 ... Frame as support 13 ... Oil application roller as fluid application roller (fluid application means) 14 ... Gap material spreading roller (gap material application means)
DESCRIPTION OF SYMBOLS 16 ... Outer cylinder 17 ... Inner cylinder 21 ... Diffusion plate 22 ... Gel-like oil and fat 24 ... Nozzle 26 ... Application gun 30 ... Jig for laser welding 31 ... Work base 32 ... Clamp mechanism (clamp means also serving as lift-up means)
34 ... Clamp arm 36 ... Application gun (application means)
39 ... Nozzle G ... Gap L ... Laser beam W1 ... Lower base material (alloyed hot-dip galvanized steel sheet as surface-treated steel sheet)
W2 ... Upper base material (alloyed hot-dip galvanized steel sheet as surface-treated steel sheet)

Claims (15)

A method of performing laser welding in the form of a lap joint after overlapping at least two base materials including the surface-treated steel sheet so that the surface-treated steel sheet is on the lower side,
After fixing the bead-like gap material on the lower base material with the viscosity of the non-volatile viscous fluid, the upper base material is overlaid from above,
A laser welding method for a surface-treated steel sheet, wherein laser welding is performed by irradiating a laser beam from the upper base metal side.   By applying a non-volatile viscous fluid mixed with the bead-shaped gap material in advance onto the lower base material, the bead-shaped gap material can be fixedly held on the lower base material. The laser welding method for a surface-treated steel sheet according to claim 1, wherein   The method of laser welding a surface-treated steel sheet according to claim 2, wherein the application of the non-volatile viscous fluid mixed with the bead-shaped gap material in advance is performed by an application gun provided to an industrial robot.   The laser of the surface-treated steel sheet according to claim 2, wherein the application of the non-volatile viscous fluid mixed with the bead-shaped gap material in advance is performed by a coating gun provided to the industrial robot together with the laser processing head. Welding method.   Applying a non-volatile viscous fluid on the lower base material and sprinkling the bead-like gap material on the base material to fix the bead-like gap material on the lower base material. The method of laser welding a surface-treated steel sheet according to claim 1.   6. The method of laser welding a surface-treated steel sheet according to claim 1, wherein the bead-shaped gap material is a glass bead.   The method for laser welding a surface-treated steel sheet according to any one of claims 1 to 6, wherein the non-volatile viscous fluid is a rust preventive oil.   The laser welding method for a surface-treated steel sheet according to any one of claims 1 to 6, wherein the non-volatile viscous fluid is a gel. A fixing device for bead-like gap materials used in the laser welding method of the surface-treated steel sheet according to claim 5,
The fluid application means for applying the non-volatile viscous fluid on the lower base material and the gap material application means for applying the bead-like gap material from the applied non-volatile viscous fluid have a common support. A fixing device for a bead-shaped gap material, which is supported by a body.   A fluid application roller that applies a non-volatile viscous fluid by rolling on the lower base material, and a bead shape from above the non-volatile viscous fluid previously applied while rotating synchronously with this fluid application roller The fixing device for bead-shaped gap material according to claim 9, wherein a gap material spreading roller for spreading the gap material is supported by a common support.   The interstitial material spreading roller disperses the bead-like interstices previously stored in the inner cylinder by the relative rotation of the inner cylinder and the outer cylinder, both of which allow passage of the bead-like gap material. The fixing device for a bead-shaped gap material according to claim 10, wherein   The fixing device for a bead-shaped gap material according to any one of claims 9 to 11, wherein the support is supported on an arm tip of an industrial robot. A laser welding jig used in the laser welding method of the surface-treated steel sheet according to claim 2,
A work base that is placed and positioned in a state in which at least two base materials to be welded are superimposed,
Among the at least two base materials positioned on the work base, it has a function of lifting at least the upper base material, and a non-volatile viscous fluid mixed with a bead-shaped gap material in advance is used for the lower base material. Prior to application on the top, lift up means for lifting the upper base material to ensure a gap between the upper and lower base materials,
An application means that can enter and retreat with respect to the gap between the upper and lower base materials, and applies a non-volatile viscous fluid mixed with a bead-like gap material in advance onto the lower base material; ,
With the upper base material superimposed on the lower base material coated with a non-volatile viscous fluid mixed with bead-shaped gap material in advance, the upper base material is placed against the lower base material. Clamping means for pressing,
A laser welding jig comprising:   14. The laser welding jig according to claim 13, wherein the clamp means also serves as a lift-up means. The clamp means has a function of lifting the base material after adsorbing and supporting the upper base material,
Wait until the non-volatile viscous fluid mixed with the bead-shaped gap material in advance is applied onto the lower base material, and press the upper base material against the lower base material while overlapping it. The laser welding jig according to claim 14, which is configured as described above.

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