JP2006231371A - Lap laser welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate laser welding while improving a welding quality by reducing an inter-flange gap for the flange part as a part to be welded and formed integrally with a formed part even if the formed part has a complicated shape. <P>SOLUTION: Three steel plates 10, 20, 30 are superposed having a first to third formed parts 11, 21, 31 and a first to third flange parts 12, 22, 32. In this case, in order for the first and second convex faces 13, 23 of the first and second curved parts 14, 24 provided in the first and second flange parts 12, 22 to become a face overlapped with the third flange part, the first and second convex faces 13, 23 are turned inward. By tack-welding the temporary welding spots as both load bearing points situated near both ends of the first curved part 14, and for the purpose of making the first and second convex faces 13, 23 to be a flat face, the first and second curved parts 14, 24 are deformed, and then, while the loaded state is maintained in which the overlapped faces are respectively pressurized, the flange parts are laser-welded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  More particularly, the present invention relates to a laser beam welding method, and more specifically, a plurality of flange parts of a plurality of members to be welded having a molded part having a predetermined shape and a flange part integrally formed on an edge of the molded part. And an overlapping laser welding method in which the flange portions are integrally joined by irradiating the overlapping portions with laser light.

  In recent years, laser welding using laser light has come to be adopted for lap welding of a plurality of steel sheet products. For example, in a vehicle such as an automobile, two or three panel members as steel plate components constituting the body are overlapped, and the overlapped portion is laser welded. In such laser welding of steel plate products, generally, a steel plate product in which a molded product portion having a predetermined shape and a flange portion formed integrally with the edge of the molded product portion are integrally formed by press working or the like is used. The overlapping portions of the flange portions that are the overlapping and joint portions are irradiated with laser light to integrally join the flange portions.

  In such superposition laser welding, if there is a large gap between the overlaid flange portions, poor welding such as underfill, burn-off, and separation beads occurs, and the required strength cannot be ensured, resulting in a quality problem.

  However, steel plate products such as panel materials that make up the body are difficult to form with high precision by press work, etc., because the shape of the molded product part is complex, and between the overlapping flange parts Irregular gaps are likely to occur.

  Then, the technique which laser-welds, pressing the overlapping flange part which is a to-be-welded part with a pressure roller is known (for example, refer patent document 1 and patent document 2).

In the technique of laser welding while pressing the welded portion with this pressure roller, a laser torch that is fixed and held on a robot arm or the like and irradiates a laser beam, and a pressure roller that is held up and down on the laser torch, A laser welding apparatus is used which is fixed and held on the laser torch and includes lifting means such as a hydraulic drive mechanism for raising and lowering the pressure roller. Then, while pressing the vicinity of the weld line of the welded portion with the pressure roller by the operation of the lifting means, the laser torch is moved along the welding line together with the pressure roller and the lifting means by the operation of the robot, thereby Laser welding is carried out while reducing the gap in the gap by the pressure applied by the pressure roller.
JP 2004-66268 A Japanese Patent Laid-Open No. 2004-90054

  However, the above-described conventional technique for correcting the gap with the pressure roller held by the laser torch has the following problems. That is, in the method in which the pressure roller and its lifting / lowering means are held by the laser torch that is moved by the operation of the robot as in the above prior art, the laser torch is moved together with the pressure roller and the lifting / lowering means due to the complicated shape of the molded part. There are cases in which it is very troublesome to move along the weld line, or the movement itself may be impossible.

  On the other hand, in the laser welding technique in which the laser torch is moved by the operation of the robot, for example, when laser welding is continuously performed at a plurality of locations (plurality of welding lines), There is a problem that the dead time until the welding is started, that is, the idle running time during which the laser torch moves between the end points of one weld line to the start point of the next weld line becomes long, and the workability is low.

  Thus, the use of remote laser welding in which laser light is scanned along the welding line by mirror scanning can reduce the dead time. However, in such remote laser welding, since the laser beam moves at high speed between the hit points, it is difficult to move the pressure roller between the hit points according to the irradiation position of the laser beam. For this reason, when performing laser welding of a plurality of welding lines continuously, it becomes difficult to perform remote laser welding while pressing the vicinity of the welding line using a single pressure roller. Of course, if a pressure roller is prepared for each welding line and waiting in advance, it is possible to perform remote laser welding while pressing the vicinity of the welding line with each pressure roller, but this complicates the apparatus. Invite.

  The present invention has been made in view of the above circumstances, and even if the molded product portion has a complicated shape, the gap between the flange portions with respect to the flange portion as the welded portion formed integrally with the molded product portion. It is a technical problem to be solved to provide a superposition laser welding method capable of easily performing laser welding while reducing welding and improving welding quality.

  Further, the present invention improves the welding quality by reducing the gap between the flange portions as the welded portion integrally formed in the molded product portion even if the molded product portion has a complicated shape. It is a technical problem to be solved to provide a superposition laser welding method that can be easily laser-welded while applying a laser beam and that can also be applied to remote laser welding in which laser light is scanned by mirror scanning It is.

  The overlapping laser welding method of the present invention that solves the above-described problems includes a plurality of members to be welded having a molded product portion having a predetermined shape and a strip-shaped flange portion formed integrally with an edge of the molded product portion. And a plurality of the above-mentioned flanged parts are integrally joined to each other by irradiating the welded part with a laser beam. At least one of the welding members has a curved portion in the flange portion having an arcuate convex curved surface having a string extending in parallel with a longitudinal direction in which the flange portion extends, and the convex portion of the curved portion is formed. An overlapping step in which the flange portions are overlapped with each other while the convex curved surface is directed inward so that the curved surface becomes an overlapping surface with another flange portion, and the convex curved surface becomes a flat surface The curved part deforms in the direction A load is applied to both load points located in the vicinity of both ends of the curved portion, and the load between the load points is maintained while maintaining a load state in which a pressing force acts on the overlapping surfaces due to the deformation of the curved portion. A laser welding step of irradiating the welded portion in a predetermined range with the laser beam and integrally joining the overlapped flange portions in the predetermined range. .

  Here, “an arcuate convex curved surface having a string extending in parallel with the longitudinal direction in which the flange portion extends” means a direction perpendicular to the longitudinal direction of the flange portion extending in a strip shape (that is, the width direction of the flange portion). It is described with the intention of clarifying the direction or the like in which the curved portion is formed by eliminating an arcuate convex curved surface having a string extending in the direction, and the string extends exactly parallel to the longitudinal direction. It is not intended to limit that. Therefore, it includes the case of an arcuate convex curved surface part in which the string extends in a direction slightly deviated from the direction parallel to the longitudinal direction due to a molding error or the like when processing the curved part in the flange part. Even so, the effects of the present invention can be naturally obtained.

  In this superposition laser welding method, superposition laser welding is performed using a plurality of members to be welded such that at least one of the members to be welded has a curved portion having an arcuate convex curved surface in the flange portion. In the overlapping step, a plurality of members to be welded are overlapped and the flange portions are overlapped to form a welded portion. At this time, the convex curved surface of the curved portion provided on the flange portion of at least one member to be welded becomes an overlapping surface with the other flange portion (the other flange portion on which the flange portion having the curved portion is overlapped). The flange portions are overlapped with each other so that the convex curved surface faces inward.

  In the next laser welding process, both ends of the curved portion are deformed so that the curved portion is deformed in a direction in which the convex curved surface of the curved portion becomes a plane (a direction in which the degree of bending of the convex curved surface decreases, that is, a direction in which the curvature decreases). A load is applied to both load points located near (both ends of the string in the bow), and a load state in which a pressing force is applied to the overlapping surfaces by the deformation of the curved portion is maintained. If this load state is maintained, since the curved portion is deformed in the direction in which the convex curved surface becomes a flat surface, a pressing force is applied to the overlapping surfaces. The gap between the surfaces is reduced. For this reason, if a laser beam is irradiated to a welded portion in a predetermined range between both load points while maintaining this load state, a bridge is reliably formed between the overlapped flange portions, and the flange portions are connected to each other. Good integration can be achieved within the predetermined range.

  As described above, in the superposition laser welding method of the present invention, the gap between the superposition surfaces can be reduced without using the pressure roller held by the laser torch and its lifting / lowering means. For this reason, even if the molded product part has a complicated shape, a load in which a load is applied between the two load points to the overlapping part (welded part) of the flange parts integrally formed in the molded product part It is possible to improve the welding quality by reducing the gap between the flange portions by a simple and easy method of irradiating the laser beam to a predetermined range between both load points while maintaining the state.

  In a preferred aspect, the overlay laser welding method of the present invention is a method in which, after the overlaying step, both the load points are tack-welded and overlapped so as to apply a load to both the load points to obtain the load state. A tack welding process is performed in which the flange portions thus formed are joined together at the load points.

  In this superposition laser welding method, in the tack welding process, both load points located in the vicinity of both ends of the curved portion are tack welded, and the overlapped flange portions as the welded portions are bonded to the load points. To be joined together. Thus, after the tack welding process is performed, a load is applied to both load points so that the curved portion is deformed in the direction in which the convex curved surface becomes a flat surface, and the pressing force is applied between the overlapping surfaces by the deformation of the curved portion. The load state in which is applied is maintained. For this reason, if laser light is irradiated to the to-be-welded part in the predetermined range between both load points after implementation of this tack welding process, laser beam irradiation can be easily performed while maintaining the load state. In other words, when irradiating the laser beam while moving the laser torch along the welding line by moving the laser torch by the operation of the robot, the load is applied to both load points without using any additional load adding means. It is possible to irradiate the welded portion with laser while easily maintaining the load state to which is added, and at this time, it is possible to reduce the gap between the overlapping surfaces without using a separate pressure roller. Therefore, the work in the laser welding process becomes extremely easy, and a good bonded state can be obtained with certainty.

  In a preferred aspect of the overlay laser welding method of the present invention, in the laser welding step, remote laser welding is performed in which laser light is scanned by mirror scanning.

  In this superposition laser welding method, the laser beam is irradiated using remote laser welding that scans the laser beam with a mirror scan. Therefore, the dead time (when one welding line is used) when laser welding is continuously performed at a plurality of locations. It is possible to shorten the idle running time during which the laser beam moves between the hit points from the end point to the start point of the next welding line, and it is possible to further improve workability.

  The superposition laser welding method of the present invention is a method in which a plurality of members to be welded having a predetermined-shaped molded product portion and a flange portion integrally formed on the edge of the molded product portion are superposed and laser-welded. . That is, the flange parts of a plurality of welded members having such a molded product part and a flange part are overlapped to form a welded part, and the welded part is irradiated with laser light, and the flange parts are Join together.

  The type of member to be welded by the method of the present invention is not particularly limited. For example, a plated steel plate in which a plating layer made of Zn or the like is coated on the surface of the base material, or a steel plate such as a bare steel plate in which the plating layer is not coated In addition to products, the present invention can be applied to aluminum alloy plates, copper alloy plates, stainless steel plates, and the like.

  The shape and size of the molded product part are not particularly limited and can be set as appropriate. The flange portion is formed integrally with the edge of the molded product portion. When a plurality of members to be welded are overlapped, the flange portions are similarly overlapped, and the overlapped portion between the flange portions becomes a welded portion to be laser welded. A member to be welded made of an integral part of the molded product portion and the flange portion can be formed into a predetermined shape by press molding or the like.

  There is no particular limitation on the size of the band plate-like flange portion or the like. In the present invention, at least one of the plurality of members to be welded has a curved portion having an arcuate convex curved surface with a string extending in parallel with the longitudinal direction in which the strip-shaped flange portion extends. Have. That is, at least one member to be welded is a curved portion having an arcuate convex curved surface in which at least a part of the strip-shaped flange portion is curved in a bow shape. This bending portion can be provided in the flange portion by bending all or part of the longitudinal direction of the strip plate-like flange portion into an arcuate shape, or can be provided in the longitudinal direction of the strip plate-like flange portion. It is also possible to provide a plurality of flanges by bending them in a bow shape a plurality of times intermittently in the direction. Moreover, the number of the members to be welded is not particularly limited, and may be two or three or more. And the number of the to-be-welded members which provide the said curved part in a flange part among the several to-be-welded members piled up is not specifically limited. For example, when two members to be welded are overlapped and laser-welded, the curved portion may be provided on only one of the flange portions, or the curved portion may be provided on both flange portions. Further, when three members to be welded are overlapped and laser-welded, the bending portion may be provided on the flange portion of only one member to be welded, or the bending portion may be provided on the flange portion of two members to be welded. A part may be provided, and the curved part may be provided in the flange part of all three members to be welded.

  The shape and size of the curved portion provided in the flange portion can be appropriately set according to the size of the gap between the overlapping flange portions. The arcuate convex curved surface in the curved portion can be a convex curved surface having a minute curvature. Specifically, the height of the convex curved surface (the height of the apex from the bow-shaped string) is preferably equal to or greater than the size of the gap, and is 1.0 to 2.0 times the size of the gap. It is more preferable to make it higher. If the convex curved surface is a curved portion having a height equal to or greater than the size of the gap, the gap between the flange portions to be superimposed can be effectively corrected.

  In addition, for the welded member in which the curved portion is provided in the flange portion, the edge shape of the molded product portion of the welded member, that is, the shape at the boundary line (ridge) between the molded product portion and the flange portion, The shape of the product portion is as designed, and the curved portion is provided in the flange portion, so that the shape is not different from the desired design shape.

  The overlay laser welding method of the present invention includes an overlay process and a laser welding process.

  In the overlapping step, the flange portions are overlapped with each other to form a welded portion while the convex curved surface is directed inward so that the convex curved surface of the curved portion becomes an overlapping surface with another flange portion. That is, when a plurality of members to be welded are overlapped, the convex curved surface is placed on the inside so that the convex curved surface of the curved portion provided on the flange portion of at least one member to be welded faces the overlapping surface of the other flange portion. The flanges are overlapped with each other. For example, when two members to be welded are overlapped, the convex curved surface of the curved portion provided on the flange portion of at least one member to be welded is opposed to the overlapping surface of the other flange portion (both members to be welded). When the curved portion is provided in the flange portion of the welding member, the flange portions are overlapped with each other so that both convex curved surfaces face each other). Moreover, when providing the said bending part in the flange part of the two to-be-welded members of the three to-be-welded members, the to-be-welded member which has the flange part which does not provide the bending part becomes the middle, The three members to be welded are overlapped so that the two members to be welded having flange portions provided with curved portions are arranged so that each convex curved surface faces inward.

  In the laser welding process, loads are applied to both load points located in the vicinity of both ends of the bending portion so that the bending portion is deformed in a direction in which the convex curved surface becomes a plane, and the overlapping is performed by the deformation of the bending portion. While maintaining the load state in which the pressing force is applied between the surfaces, the laser beam is irradiated to the welded portion in a predetermined range between the load points, and the overlapped flange portions are within the predetermined range. Join together.

  The vicinity of both ends of the bending portion may be the vicinity of both ends of the bending portion itself within the range of the bending portion, or provided partially when the bending portion is partially provided in the flange portion. It means that it may be in the vicinity of both ends of the bending portion in the flat portion on both outer sides of the bending portion. That is, a load may be applied to both load points located in the vicinity of both ends of the curved portion itself within the range of the curved portion provided entirely or partially on the flange portion, or partially provided on the flange portion. A load may be applied to both load points located in the vicinity of both end portions of the curved portion in the flat portion on both outer sides of the curved portion.

  When a load is applied to both load points in this way, the curved portion is deformed in a direction in which the convex curved surface becomes a flat surface, and the overlapping surfaces of the flange portions (the two flange portions overlapped with each other) The pressing force acts on the convex surface of the curved portion provided on at least one of the flange portions and the overlapping surface of the other flange portion superimposed on the convex curved surface. In the laser welding process according to the present invention, a laser beam is irradiated to a welded portion in a predetermined range between both load points while maintaining a load state where such a pressing force is applied.

  In this way, a load is applied to both load points, and the curved portion is deformed in a direction in which the convex curved surface becomes a flat surface. By laser welding, laser welding can be performed in a state where the gap between the overlapping surfaces of the overlapped flange portions is reduced, so that welding defects caused by the gap are suppressed and welding quality is improved. Is possible.

  There is no particular limitation on the method of applying a load to both load points and maintaining the load state. For example, it may be sandwiched by pressure rollers or the like at both load points from both sides in the overlapping direction of the overlapped flange portions. However, even if the molded part has a complicated shape, both load points are temporarily set from the viewpoint of facilitating the work in the laser welding process, such as being able to easily irradiate laser light, and improving workability. It is preferable to perform welding.

  That is, in the laser welding method for welding members to be welded according to the present invention, after the superimposing step, both the load points are tack welded so as to apply a load to both the load points to obtain the load state. It is preferable to perform a tack welding process in which the overlapped flange portions are joined together at the load point. When tack welding is performed in this way, a load is applied to both load points so that the curved portion is deformed in a direction in which the convex curved surface becomes a flat surface, and a pressing force acts on the overlapping surfaces due to the deformation of the curved portion. The load state can be easily maintained. For this reason, if laser light is irradiated to the overlapping portion in a predetermined range between both load points after the tack welding process is performed, it is possible to easily perform laser light irradiation while maintaining the load state. Become. In other words, when irradiating the laser beam while moving the laser torch along the welding line by moving the laser torch by the operation of the robot, the load is applied to both load points without using any additional load adding means. Since the gap between the overlapping surfaces can be reduced without using a separate pressure roller, the work in the laser welding process is facilitated.

  The method of the tack welding is not particularly limited as long as it is a method capable of integrally joining the overlapped flange portions. For example, it is possible to suitably use spot welding in which electricity is applied while pressing both load points with a spot gun.

  This tack welding process is preferably performed in a state where the members to be welded are overlapped while accurately positioned. After the tack welding process is performed in this way, each member to be welded accurately can be handled integrally, and the workability can be improved in the laser welding process performed thereafter.

  There are no particular limitations on the laser light irradiation method, irradiation conditions, and the like in the laser welding process. For example, the laser torch held by the robot arm may be moved along the weld line of the welded portion by the operation of the robot to irradiate the laser beam onto the weld line. However, in consideration of workability and productivity in the laser welding process, it is preferable to use remote laser welding in which laser light is scanned by mirror scanning.

  In remote laser welding, laser light introduced from a laser oscillator via an optical system is reflected by a reflecting mirror in a predetermined direction, thereby scanning the laser light along the welding line. That is, with respect to the reflection mirror that can be rotated about the X axis and the Y axis as the rotation center, the laser beam is reflected in a predetermined direction by controlling the rotation in each axis direction, thereby along the weld line. To scan with laser light. By using remote laser welding in which laser light is scanned by mirror scanning in this way, it is possible to reduce the dead time when laser welding is continuously performed at a plurality of locations, and the workability of the laser welding process is improved. It becomes possible to make it.

The type of laser light used in the laser welding process is not particularly limited, and a YAG laser, a CO ₂ laser, a semiconductor laser, or the like can be suitably used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

  In the present embodiment, three steel plate products, ie, a first steel plate product 10, a second steel plate product 20, and a third steel plate product 30 as members to be welded are overlapped and laser-welded using remote laser welding. .

  These three steel plate products constitute a center pillar member for automobiles, and are all integrally formed products that are press-formed from a plate material into a cross-sectional hat shape. The first steel plate product 10 is an outer panel having a thickness of about 0.6 to 1 mm, the second steel plate product 20 is an inner panel having a thickness of about 0.8 to 1 mm, and the third steel plate product 30 is phosphorus having a thickness of about 2 to 3 mm. Force. In addition, all of these 1st, 2nd and 3rd steel plate articles 10, 20, and 30 are long members about 30-120 cm. 1 to 5, parts of the first, second and third steel plate products 10, 20 and 30 are partially shown, and the remaining parts not shown are also shown in FIGS. 1 to 5. The configuration is the same as that shown.

  The first steel plate product 10 is integrated with the first molded product part 11 having a cup-shaped or substantially U-shaped cross section and part of the edge of the first molded product part 11 (both ends in the U-shaped cross section). It is comprised from a pair of 1st flange parts 12 and 12 which make | form the substantially strip | plate shape formed in this.

  Similarly, the second steel plate product 20 includes a second molded product portion 21 having a cup-shaped or substantially U-shaped cross section, and a part of an edge of the second molded product portion 21 (both end portions in the U-shaped cross section ) And a pair of second flange portions 22 and 22 formed in a substantially strip shape.

  The third steel sheet product 30 includes a third molded product part 31 having a cup-shaped or substantially U-shaped cross section, and a part of an edge of the third molded product part 31 (both end portions in a U-shaped cross section). It is comprised from a pair of 3rd flange parts 32 and 32 which make | forms the band plate shape formed integrally.

  The first steel plate product 10 and the second steel plate product 20 both have a plurality of curved portions in the flange portion having an arcuate convex curved surface having a string extending parallel to the longitudinal direction in which the flange portion extends. Yes.

  In other words, the first bent portion 12 of the first steel plate product 10 has an arcuate first convex curved surface 13 (see FIG. 2) having a string extending parallel to the longitudinal direction in which the flange portion extends. 14 and a pair of first flat portions 15, 15 integrally connected to the vicinity of both end portions of the first bending portion 14, specifically, to both outer sides (both outer sides in the longitudinal direction) of the first bending portion 14. Is formed. The first curved portion 14 and the first flat portions 15 and 15 are repeatedly formed in the longitudinal direction of the first flange portion 12. Further, the edge shape of the first molded product part 11 of the first steel plate product 10, that is, the shape at the boundary line (ridge) between the first molded product part 11 and the first flange part 12 is the same as that of the first molded product part 11. The shape is as designed.

  Similarly, the second bent portion 22 of the second steel plate product 20 has a second curve having an arcuate second convex curved surface 23 (see FIG. 2) having a string extending parallel to the longitudinal direction in which the flange portion extends. Part 24 and a pair of second flat parts 25, 25 integrally connected to the vicinity of both ends of the second bending part 24, specifically to both outer sides (both outer sides in the longitudinal direction) of the second bending part 24, Is formed. The second bending portion 24 and the second flat portions 25 and 25 are repeatedly formed in the longitudinal direction of the second flange portion 22. Further, the edge shape of the second molded product portion 21 of the second steel plate product 20, that is, the shape at the boundary line (ridge) between the second molded product portion 21 and the second flange portion 22 is the shape of the second molded product portion 21. The shape is as designed.

  Here, the shape and size of the first bending portion 14 and the second bending portion 24 are set according to the size of the gap between the overlapping surfaces in the welded portion to be described later. Specifically, since the size of the gap is about 1 mm at the maximum, the heights of the first convex curved surface 13 of the first curved portion 14 and the second convex curved surface 23 of the second curved portion 24 are both It is about 1 to 2 mm, which is about 1 to 2 times higher than the size of the gap. The lengths of the first bending portion 14 and the second bending portion 24 (the length of the bending portion in the longitudinal direction of the flange portion) are both about 300 mm.

  The lengths of the first flat portions 15 and 15 and the second flat portions 25 and 25 (the length of the flat portion in the longitudinal direction of the flange portion) are all about 20 mm. Then, as will be described later, a substantially center position of the first flat portions 15 and 15 and the second flat portions 25 and 25 becomes a tack welding point 40 (see FIG. 5) as a load point.

  As shown below, the three steel plates having such a configuration were subjected to overlap laser welding by an overlap laser welding method including an overlap step, a tack welding step, and a laser welding step.

<Overlay process>
As shown in FIGS. 1 and 2, the third steel plate product 30 having the third flange portion 32 not provided with the curved portion is set in the middle, and the first steel plate product 10 and the second steel plate product 20 are arranged on both sides thereof. The three steel plate products were stacked one above the other. At this time, while aligning so that the vertices of the first convex curved surface 13 and the vertices of the second convex curved surface 23 face each other (the first flat portions 15, 15 and the second flat portions 25, 25 also face each other) The first convex curved surface 13 provided on the first flange portion 12 of the first steel plate product 10 and the second convex curved surface 23 provided on the second flange portion 22 of the second steel plate product 20 are directed inward, respectively. The first convex curved surface 13 of the flange portion 12 and the upper surface of the third flange portion 32 opposite to the first convex curved surface 13 become an overlapping surface, and the second convex curved surface 23 of the second flange portion 22 and the third flange portion opposite thereto. The overlapping parts were used as welded parts.

<Tack welding process>
Next, as shown in FIGS. 3 and 4, the first flat portions 15, 15 and the second flat portions 25, 25 are energized while being pressurized with a spot gun 41 with the temporary welding spot 40 as the substantially central portion. Spot welding is performed, and the first flange portion 12, the second flange portion 22, and the third flange portion 23 that are overlapped are integrally joined at a tack welding point 40 as a load point to form a tack weld portion 42. .

  As a result, the first curved portion 14 and the second curved portion 24 are deformed so that the first convex curved surface 13 of the first flange portion 12 and the second convex curved surface 23 of the second flange portion 22 are flat. A load is applied to the tack welding spot 40 as both load points located near both ends of the first bending portion 14 and the second bending portion 24, and the first bending portion 14 and the second bending portion 24 bending portion. The load state in which a pressing force was applied between the overlapping surfaces by the deformation was maintained.

<Laser welding process>
Finally, in this example, laser welding was performed using remote laser welding under the following conditions.

Laser: CO ₂ laser Laser output: 3.5 kW
Welding speed: 1.0 to 4.0 m / min
In this remote laser welding, as shown in FIG. 5, a laser oscillator 51 and a laser oscillator that can be rotated around two axes of the X axis and the Y axis are rotated via an optical system 52 composed of a plurality of mirrors and lenses. A laser beam 53 oscillated from 51 is introduced, and a reflection mirror (scan mirror) 54 that reflects the laser beam 53 in a predetermined direction and rotation of the reflection mirror 54 in the X-axis and Y-axis directions are controlled. Thus, the remote laser welding apparatus provided with the control means 55 for scanning the laser beam 53 in a predetermined position and in a predetermined direction and controlling the oscillation of the laser beam 53 from the laser oscillator 51 was used.

  Then, the control means 55 controls the on / off of the laser oscillator 51 and the rotation of the reflection mirror 54 to control a predetermined range between the load points (in the present embodiment, the first and second bending portions 14 and 24). The first flange portion 12 and the second flange portion that are overlapped by irradiating the welded portion in a range corresponding to almost the entire length in the longitudinal direction so that the laser beam 53 scans along the longitudinal direction of the flange portion. 22 and the 3rd flange part 32 were integrally joined in this predetermined range. In this embodiment, the first flat portions 15 and 15 and the second flat portions 25 and 25 are not laser welded by turning off the oscillation of the laser beam 53 from the laser oscillator 51. It is not limited to.

  Thus, in the overlap laser welding method of the present embodiment, the first and second convex curved surfaces 13 and 23 of the first and second curved portions 14 and 24 provided on the first and second flange portions 12 and 22 are formed. Temporary welding as temporary load points located near both ends of the first and second curved portions 14 and 24 in the tack welding process so that the first and second curved portions 14 and 24 are deformed so as to be flat. The spot welding point 40 is joined by spot welding. As a result, a load is applied to both the load points, and the load state in which a pressing force is applied to the respective overlapping surfaces due to the deformation of the first and second bending portions 14 and 24 is maintained. The gap between the overlapping surfaces is reduced by approaching. In the subsequent laser welding process, the predetermined range is laser-welded using remote laser welding while maintaining the load state, so that a bridge is reliably formed between the superimposed surfaces. The flange portions can be joined together well within the predetermined range.

  Further, in this embodiment, since the three steel plate products are spot-welded while positioning the three steel plate products in the tack welding process, the three steel plate products are handled integrally. In addition, the load state can be easily maintained. In addition, in the laser welding process, laser welding is performed using remote laser welding with less dead time. Therefore, according to the lap laser welding method of the present embodiment, workability and productivity can be remarkably improved regardless of the shape of the molded part, and a good bonded state can be reliably obtained. It becomes.

FIG. 6 is a partial perspective view schematically showing a state of an overlaying process in the overlay laser welding method according to an embodiment of the present invention. FIG. 4 is a partial cross-sectional view schematically showing a state of an overlaying process in the overlay laser welding method according to an embodiment of the present invention. It is a fragmentary perspective view which shows typically the mode of the tack welding process in the overlap laser welding method concerning the Example of this invention. It is a fragmentary sectional view showing an appearance of a tack welding process in an overlap laser welding method typically concerning an example of the present invention. It is a fragmentary perspective view which shows the mode of the laser welding process in the overlap laser welding method concerning the Example of this invention typically.

Explanation of symbols

10, 20, 30 ... 1st, 2nd, 3rd steel plate products (members to be welded)
11, 12, 13 ... 1st, 2nd, 3rd molded product part 12, 22, 32 ... 1st, 2nd, 3rd flange part 13, 23 ... 1st, 2nd convex curve 14, 24 ... 1st , Second bending portion 15, 25 ... first, second flat portion 40 ... tack welding point (load point)
DESCRIPTION OF SYMBOLS 51 ... Laser oscillator 52 ... Optical system 53 ... Laser beam 54 ... Reflection mirror 55 ... Control means

Claims (3)

The flange parts of a plurality of members to be welded having a molded product part of a predetermined shape and a strip-like flange part integrally formed on the edge of the molded product part are overlapped to form a welded part, An overlapping laser welding method in which the flange portions are integrally joined to each other by irradiating the welded portions with laser light,
At least one of the plurality of members to be welded has a curved portion in the flange portion having an arcuate convex curved surface having a string extending parallel to a longitudinal direction in which the flange portion extends,
A superimposing step of superimposing the flange portions on the inner side with the convex curved surface facing inward so that the convex curved surface of the curved portion becomes a superposed surface with another flange portion;
A load is applied to both load points located in the vicinity of both ends of the curved portion so that the curved portion is deformed in the direction in which the convex curved surface becomes a plane, and the overlapping surfaces are pressed by the deformation of the curved portion. The laser beam is irradiated to the welded portion in a predetermined range between the two load points while maintaining the load state in which the load acts, and the overlapped flange portions are joined together in the predetermined range. A superposition laser welding method comprising: a laser welding process.   After the superimposing step, in order to apply a load to both the load points so as to be in the load state, the flange portions that are superimposed by welding the load points are temporarily joined together at the load points. The overlay laser welding method according to claim 1, wherein a tack welding process is performed.   3. The superposition laser welding method according to claim 1, wherein in the laser welding step, remote laser welding is performed in which the laser beam is scanned by mirror scanning.

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