JP5000982B2 - Laser welding method for differential thickness materials - Google Patents

Description

  The present invention relates to a laser welding method for a differential thickness material that is preferably used for abutting flat plate-like thick plates and thin plates having different plate thicknesses and joining the abutting surfaces thereof by laser welding.

  In general, when welding a flat plate and a thin plate with different plate thicknesses butted together, in order to weld both while filling the uneven part (gap) generated on the butted surface of the thick plate and thin plate, A welding method is employed in which laser welding is performed along the abutting surface between a thick plate and a thin plate while melting a filler material such as a filler wire.

  Here, the gap between the abutting surfaces of the thick plate and the thin plate is caused by burrs when the thick plate or thin plate is cut, an oxide film when the thick plate or thin plate is melted, or the like. It is necessary to form a good weld bead free from underfill or the like that causes a decrease in weld strength by melting and filling the filler material in the gap.

  However, since the size of the gap generated on the abutting surface between the thick plate and the thin plate is not constant, for example, if the amount of filler added is set in accordance with the largest gap, the abutting surface between the thick plate and the thin plate Of these, the amount of filler material added is excessive at the site where the gap is small. As a result, the bead toe portion on the thin plate side protrudes in a convex shape toward the thin plate, and a steep step is formed between the bead toe portion on the thin plate side and the surface (upper surface) of the thin plate. End up.

  As described above, when a step is formed between the bead toe portion on the thin plate side and the surface of the thin plate, stress is applied to the bead toe portion on the thin plate side by repeatedly applying a load to the welded structure. Concentrate. As a result, there is a problem that a crack (crack) is generated starting from the bead toe portion on the thin plate side, and the welded structure is damaged.

  In contrast, in a welded joint formed by welding two metal plates using a filler metal, the toe portion of the weld bead formed between the metal plates is remelted by a heating means such as TIG welding. Thus, a method for manufacturing a welded joint has been proposed in which the bead toe is formed so as to be smoothly continuous from the surface of the metal plate, and stress is prevented from concentrating on the bead toe (for example, , See Patent Document 1).

JP-A-62-77177

  Further, as another prior art, the bead toe portion is formed by pressing a rotating body against the toe end portion of a weld bead formed between two metal plates and pressurizing the bead toe end portion with the rotating body. There has been proposed a method for pressurizing the weld toe so as to suppress the concentration of stress on the surface (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 10-296480

  However, although the above-described method for manufacturing a welded joint by TIG welding in Patent Document 1 is suitable for welding two metal plates having substantially the same thickness, the projection between a thick plate and a thin plate having different plate thicknesses. When welding the mating surfaces, even if an arc is generated aiming at the bead toe, the arc bends toward the plate material closer to the bead toe due to the magnetic blow, so TIG welding Thus, it is difficult to remelt the bead toe.

  On the other hand, the method for pressurizing the weld toe portion of Patent Document 2 described above requires a pressurizing device for pressurizing the toe end portion of the weld bead with the rotating body, and the cost for the pressurizing device increases. There is a problem of end.

  The present invention has been made in view of the above-described problems of the prior art, and among the weld beads formed on the abutting surfaces of the thick plate and the thin plate having different plate thicknesses, stress is concentrated on the bead toe portion on the thin plate side. It is an object of the present invention to provide a laser welding method for a differential thickness material that can suppress welding and increase welding strength.

  In order to solve the above-described problems, the present invention is applied to a laser welding method for a differential thickness material in which laser welding is performed by abutting a thick plate and a thin plate having different plate thicknesses.

The features of the welding method according to the invention of claim 1, and facilities the laser welding abutting surfaces of the thick plate and thin plate while melting the filler metal by a laser beam, welding between the thick plate and thin plate a first welding step of forming the bead, have a second welding step of melting again by the laser beam of the bead toe portion of the thin side of the first said weld bead formed by the welding process of In the first welding step, laser welding is performed from the start end position toward the end position along the abutting surface of the thick plate and the thin plate. In the second welding step, the first welding step It is to irradiate a laser beam to the bead toe portion on the thin plate side from the end position in the welding direction toward the start end position .

In the invention of claim 2 , the optical axis of the laser beam in the second welding step is set to a range in which ½ or more of the irradiation area of the beam front end is irradiated to the bead toe end on the thin plate side. There is.

According to a third aspect of the present invention, in the second welding step, the amount of heat of the laser beam irradiated to the bead toe portion on the thin plate side is applied to the butt surface between the thick plate and the thin plate in the first welding step. That is, it is set lower than the amount of heat of the irradiated laser beam.

  According to the first aspect of the present invention, in the first welding step using the filler metal, the bead toe portion on the thin plate side of the weld bead formed on the abutting surface of the thick plate and the thin plate is made of a thin plate. Even if a step is formed between the surface and the surface of the thin plate, in the second welding step, the bead toe portion on the thin plate side is melted again by the laser beam, thereby forming a step between the bead toe portion and the surface of the thin plate. Alternatively, the bead toe can be formed so as to be smoothly continuous with the surface of the thin plate.

  Thereby, it can suppress that stress concentrates on the bead toe part by the side of a thin plate, and can improve the welding strength of a thickness difference material. In addition, the welding of the thick plate and the thin plate using the filler material in the first welding step and the remelting of the bead toe portion on the thin plate side in the second welding step can both be performed by laser welding. Therefore, for example, by performing the first and second welding processes using a single laser welding machine, the manufacturing cost of the differential thickness material can be reduced.

Here, the welding direction when laser welding the butted surfaces of the thick plate and the thin plate in the first welding step, and the welding when irradiating the laser beam to the bead toe portion on the thin plate side in the second welding step. The directions are opposite to each other. In this case, laser welding proceeds to the end position while flowing the molten metal to the rear side (start end position side) in the welding direction by irradiating the laser beam from the start end position to the end position of the welding operation. The weld bead rises at the start position of laser welding and becomes depressed at the end position.

  On the other hand, by making the welding directions opposite in the first welding process and the second welding process, the end position of welding in the first welding process is the start position of welding in the second welding process. Overlap, the welding start end position in the first welding process overlaps with the welding end position in the second welding process. For this reason, the shape of the weld bead formed on the abutting surface of the thick plate and the thin plate can be made uniform in the length direction (welding direction), and the welding strength of the differential thickness material can be further increased. .

  Furthermore, since the terminal position in the first welding process is the starting position in the second welding process, the first welding process and the second welding process can be executed continuously, And the workability when laser welding the thin plate.

According to the invention of claim 2 , the bead toe on the thin plate side is irradiated to the bead toe portion on the thin plate side formed in the first welding step by ½ or more of the irradiation area of the beam front end. The laser beam can be irradiated to the part and its surroundings without waste. Thereby, the bead toe portion on the thin plate side can be efficiently melted, and the periphery of the bead toe portion can be heated to improve the wettability of the molten metal.

  As a result, the bead toe portion on the thin plate side that forms a steep step with the surface of the thin plate can be melted, and this molten metal can be guided to the thin plate side. It can be made to continue smoothly on the surface, and the welding strength of the differential thickness material can be increased.

According to the invention of claim 3 , in the second welding process, the amount of heat of the laser beam irradiated to the bead toe portion on the thin plate side is irradiated to the butt surface between the thick plate and the thin plate in the first welding step. By setting it lower than the amount of heat of the beam, the bead toe on the thin plate side will not melt more than necessary, and welding distortion and deformation can be suppressed. Can be manufactured.

  Hereinafter, an embodiment of a laser welding method for a differential thickness material according to the present invention will be described in detail with reference to FIGS.

  In the figure, 1 indicates a thick plate made of a metal plate, and the thick plate 1 constitutes a differential thickness material 11 together with a thin plate 2 described later. Here, the thick plate 1 is formed in a rectangular flat plate shape having a thickness dimension T by cutting a thick metal plate using means such as laser cutting or gas cutting. And the end surface which faces the below-mentioned thin plate 2 among the thick plates 1 serves as a butting surface 1A that comes into contact with the butting surface 2A of the below-described thin plate 2.

  Reference numeral 2 denotes a thin plate made of a metal plate, and the thin plate 2 is butt welded to the thick plate 1 by laser welding. Here, the thin plate 2 is formed in a rectangular flat plate shape having a thickness dimension t smaller than that of the thick plate 1 by cutting a thin metal plate using means such as laser cutting or gas cutting. . And the end surface which faces the thick plate 1 among the thin plates 2 is a butting surface 2A which abuts on the butting surface 1A of the thick plate material 1.

  The thick plate 1 and the thin plate 2 are arranged on a surface plate (not shown) with the butted surfaces 1A and 2A butted together, and the upper side of the butted surface 1A of the thick plate 1 is the thin plate 2 It protrudes upward from the butting surface 2A. Also, one end side in the longitudinal direction of the thick plate 1 and the thin plate 2 that face each other is a starting end position 3 where laser welding is started in a first welding step described later, and the other end side in the longitudinal direction is the first end side. The end position 4 is where the laser welding ends in the welding process.

  Reference numeral 5 denotes an intersecting portion where the butting surface 1A of the thick plate 1 and the butting surface 2A of the thin plate 2 intersect. The intersecting portion 5 is formed between the butting surface 1A of the thick plate 1 and the butting surface 2A of the thin plate 2. Along the longitudinal direction. And this intersection part 5 guides the front-end | tip of this melt material 6 by abutting the front-end | tip of the melt material 6 mentioned later.

  6 is a filler material supplied to the intersection 5 between the butting surface 1A of the thick plate 1 and the butting surface 2A of the thin plate 2, and the filler material 6 is called filler wire or the like as shown in FIG. It is made of an elongated linear metal material. And this filler material 6 is continuously supplied to the crossing part 5 between the thick plate 1 and the thin plate 2 by the supply apparatus (not shown) for melt materials, and from the laser welding machine 7 mentioned later. The laser beam 8 is irradiated.

  Reference numeral 7 denotes a laser welding machine. The laser welding machine 7 irradiates laser light emitted from a laser oscillator (not shown) into a very small area range by a condensing device (not shown) such as a lens and a reflecting mirror. The condensed laser beam 8 is irradiated toward the object to be welded.

  And the laser welding machine 7 is arrange | positioned above the cross | intersection part 5 of the thick plate 1 and the thin plate 2, and the arrow A direction in FIG. 2 along the longitudinal direction of this cross | intersection part 5 or the arrow in FIG. It is configured to move in the direction indicated by B.

  Next, a laser welding method for welding the thick plate 1 and the thin plate 2 using the laser welding machine 7 will be described.

  First, as shown in FIG. 1, the thick plate 1 and the thin plate 2 are arranged on a surface plate (not shown) in a state where the butted surfaces 1A and 2A are butted. At this time, between the thick plate 1 and the thin plate 2, the cross | intersection part 5 extended in a longitudinal direction is formed along mutual butting surfaces 1A and 2A. A gap is formed between the butted surfaces 1A and 2A due to burrs or the like during cutting.

  Next, as shown in FIG. 2, the filler material 6 is supplied to the intersecting portion 5 formed between the thick plate 1 and the thin plate 2, and the laser beam 8 from the laser welding machine 7 is applied to the filler material 6. While irradiating the tip, the laser welding machine 7 is moved in the arrow A direction from the start position 3 in the longitudinal direction of the thick plate 1 and the thin plate 2 toward the end position 4 (first welding process).

  Thus, the abutting surface 1A of the thick plate 1 and the abutting surface 2A of the thin plate 2 can be welded by melting the thick plate 1 and the thin plate 2 while melting the filler material 6 by the laser beam 7. it can. As a result, between the thick plate 1 and the thin plate 2, as shown in FIGS. 3 to 5, there are a start end portion 9 A and a terminal end portion 9 B in the longitudinal direction, and a bead stop end portion 9 C on the thick plate 1 side. And a weld bead 9 having a bead toe 9D on the thin plate 2 side is formed.

  Here, in the first welding step, the butting surfaces 1A and 2A of the thick plate 1 and the thin plate 2 are laser-welded while the filler material 6 is being melted, so that the butting surface 1A and the thin plate 2 of the thick plate 1 are projected. Even when there is a large gap between the mating surfaces 2A, the cap can be filled with the melted filler material 6 and underfill or the like can be prevented from occurring in the weld bead 9.

  On the other hand, when there is no large gap between the abutting surface 1A of the thick plate 1 and the abutting surface 2A of the thin plate 2, the amount of the filler material 6 added becomes excessive, and as shown in FIG. 9, the bead stop end portion 9D on the thin plate 2 side protrudes in a convex shape toward the thin plate 2 side, so that a steep step is formed at the boundary between the surface 2B of the thin plate 2 and the bead stop end portion 9D.

  In the first welding step, as shown in FIG. 2, the laser welding machine 7 is moved in the direction indicated by the arrow A from the longitudinal end position 3 to the terminal position 4 of the thick plate 1 and the thin plate 2. Laser welding is performed. At this time, the molten metal melted by the laser beam 8 from the laser welding machine 7 is rearward (starting end 9A side) with respect to the moving direction A of the laser welding machine 7, as indicated by an arrow a in FIG. It gradually solidifies while flowing. For this reason, as shown in FIG. 5, the weld bead 9 formed in the first welding step becomes a raised portion 9E that is raised in a mountain shape on the start end portion 9A side, and becomes a hollow portion 9F on the end portion 9B side. These swelled portions 9E and recessed portions 9F are factors that reduce the strength of the entire weld bead 9.

  Next, as shown in FIGS. 6 and 7, the laser beam 8 from the laser welding machine 7 is irradiated to the bead toe portion 9 </ b> D on the thin plate 2 side of the weld bead 9 formed in the first welding process. To do. Then, by moving the laser welding machine 7 from the end position 4 in the longitudinal direction of the thick plate 1 and the thin plate 2 to the start end position 3 in the direction indicated by the arrow B in FIG. 9D is melted again (second welding step).

  Here, as shown in FIGS. 7 and 8, the optical axis OO of the laser beam 8 irradiated from the laser welding machine 7 to the bead stop end 9D on the thin plate 2 side in the second welding step is a bead stop. One half or more of the irradiation area of the beam tip (beam spot) 8A, which is offset to the thick plate 1 side with respect to the end 9D and forms a circle with a diameter D, is set to a range in which the bead stop 9D is irradiated. ing. Thereby, the laser beam 8 can be irradiated to the bead toe portion 9D on the thin plate 2 side, the surrounding weld bead 9, the thin plate 2 and the like without waste.

  Further, in the second welding process, the amount of heat of the laser beam 8 irradiated from the laser welding machine 7 to the bead toe portion 9D on the thin plate 2 side is changed to the butt surface between the thick plate 1 and the thin plate 2 in the first welding process. It is set lower than the amount of heat of the laser beam 8 irradiated to 1A and 2A. In this case, in the present embodiment, the amount of heat of the laser beam 8 in the second welding process is set lower than the amount of heat of the laser beam 8 in the first welding process, for example, by controlling the output of the laser welding machine 7. In addition, it is possible to prevent the bead toe portion 9D on the thin plate 2 side from being melted more than necessary.

  In this way, the laser welding machine 7 in the second welding step is applied to the stop end portion 9D on the thin plate 2 side protruding in a convex shape on the thin plate 2 side among the weld beads 9 formed in the first welding step. By irradiating the laser beam 8 from, the toe portion 9D on the thin plate 2 side can be melted again. As a result, as shown in FIG. 9, it is possible to manufacture a differential thickness material 11 in which a new weld bead 10 is formed between the thick plate 1 and the thin plate 2.

  Here, the weld bead 10 of the differential thickness member 11 manufactured through the first and second welding steps has a longitudinal start end 10A and a termination end 10B, as shown in FIGS. The thick plate 1 side bead toe 10C and the thin plate 2 side bead toe 10D. In this case, the bead toe 10D on the thin plate 2 side has a shape that is recessed smoothly from the surface 2B of the thin plate 2 toward the thick plate 1 side. For this reason, it is possible to eliminate the step between the bead toe 10D on the thin plate 2 side and the surface 2B of the thin plate 2 and to suppress the concentration of stress on the bead toe 10D on the thin plate 2 side. 1 and the thin plate 2 can be increased in welding strength, and the reliability of the differential thickness material 11 can be increased.

  In this case, in the second welding process, as shown in FIG. 6, the laser welding machine 7 is moved from the terminal position 4 in the longitudinal direction of the thick plate 1 and the thin plate 2 to the starting position 3, while the first welding process. The laser beam 8 is irradiated to the bead toe portion 9D on the thin plate 2 side formed in (1). That is, the moving direction of the laser welding machine 7 in the second welding process (the direction indicated by arrow B in FIG. 6) is changed to the moving direction of the laser welding machine 7 in the first welding process (the direction indicated by arrow A in FIG. 2). Is set in the opposite direction.

  At this time, the molten metal formed by melting the weld bead 9 flows toward the rear side (starting end portion 10A side) with respect to the moving direction B of the laser welding machine 7, as indicated by an arrow b in FIG. It gradually solidifies. Therefore, the swelled portion 9E of the weld bead 9 indicated by a two-dot chain line in FIG. 11 is smoothed by the molten metal of the weld bead 9 flowing in the direction of the arrow b, and the recess 9F of the weld bead 9 is Smoothing is achieved by filling the inside with molten metal. As a result, the shape of the weld bead 10 formed by the second welding process can be made substantially uniform from the start end 10A to the end end 10B in the longitudinal direction, and the weld strength of the differential thickness material 11 can be increased. .

  In addition, a first welding step of welding the thick plate 1 and the thin plate 2 using the filler material 6 and a second toe end portion 9D on the thin plate 2 side formed in the first welding step are melted again. Since the single welding process can be performed using the single laser welding machine 7, the manufacturing cost of the differential thickness material 11 can be reduced.

  Further, the laser welder 7 moves from the start position 3 in the longitudinal direction of the thick plate 1 and the thin plate 2 to the end position 4 in the first welding process, and from the end position 4 to the start position 3 in the second welding process. Therefore, the first welding process and the second welding process can be performed continuously, and the workability when laser welding the thick plate 1 and the thin plate 2 can be improved.

  Further, according to the present embodiment, the optical axis OO of the laser beam 8 in the second welding process is set to a diameter D with respect to the bead toe 9D on the thin plate 2 side formed in the first welding process. The bead stop end portion 9D on the thin plate 2 side, the weld bead 9 on the periphery thereof, and the thin plate 2 are set to a range in which a half or more of the irradiation area of the beam tip (beam spot) 8A forming a circular shape is irradiated. Etc., the laser beam 8 can be irradiated without waste.

  For this reason, while the bead toe part 9D by the side of the thin plate 2 can be efficiently melted, the periphery of the bead toe part 9D can be heated to enhance the wettability of the molten metal. As a result, the bead toe 9D that forms a steep step with the surface 2B of the thin plate 2 can be melted, and this molten metal can be guided to the thin plate 2 side. Among them, the shape of the bead toe portion 10D on the thin plate 2 side can be smoothly continued to the surface 2B of the thin plate 2, and the welding strength of the differential thickness material 11 can be increased.

  Further, according to the present embodiment, the amount of heat of the laser beam 8 irradiated from the laser welding machine 7 to the bead toe 9D on the thin plate 2 side is matched between the thick plate 1 and the thin plate 2 in the first welding process. The amount of heat of the laser beam 8 applied to the surfaces 1A and 2A is set lower. As a result, it is possible to suppress the bead toe portion 9D on the thin plate 2 side from being melted more than necessary, and to suppress welding distortion, deformation, and the like, so that a highly reliable differential thickness material 11 is manufactured. be able to.

  In the above-described embodiment, the amount of heat of the laser beam 8 applied to the bead toe portion 9D on the thin plate 2 side in the second welding step is matched between the thick plate 1 and the thin plate 2 in the first welding step. The case where the output of the laser welding machine 7 is controlled in order to set lower than the amount of heat of the laser beam 8 irradiated to the surfaces 1A and 2A is illustrated.

  However, the present invention is not limited to this. For example, by keeping the output of the laser welding machine 7 constant and increasing the moving speed of the laser welding machine 7 in the second welding process, the bead toe portion on the thin plate 2 side is increased. You may reduce the calorie | heat amount of the laser beam 8 irradiated to 9D.

  Further, for example, by changing the height position of the laser welding machine 7 with respect to the bead toe 9D on the thin plate 2 side, the laser beam 8 irradiated to the bead toe 9D is defocused to defocus. The amount of heat of 8 may be reduced.

  Further, in the above-described embodiment, it is assumed that the beam tip 8A of the laser beam 8 irradiated from the laser welder 7 to the toe portion 9D on the thin plate 2 side in the second welding process forms a circle having a diameter D. is doing. However, the present invention is not limited to this, and for example, a laser beam having a non-circular shape such as an elliptical shape or a rectangular shape may be used.

It is a perspective view which shows the state which the thick plate and thin plate which are used for embodiment of the laser welding which concerns on this invention face each other. It is a perspective view which shows a 1st welding process. It is a perspective view which shows the weld bead, the thick plate, and the thin plate which were formed at the 1st welding process. FIG. 4 is a cross-sectional view of a weld bead and the like when viewed from the direction of arrows IV-IV in FIG. It is sectional drawing which looked at the welding bead from the arrow VV direction in FIG. It is a perspective view which shows a 2nd welding process. It is an expanded sectional view which expands and shows the state which irradiated the laser beam to the bead toe part by the side of a thin plate. It is sectional drawing which looked at the positional relationship of the bead toe part and beam front-end | tip by the side of a thin plate from the arrow VIII-VIII direction in FIG. It is a perspective view which shows the difference thickness material manufactured by the laser welding based on this invention. It is sectional drawing which looked at the welding bead of the differential thickness material from the arrow XX direction in FIG. It is sectional drawing which looked at the welding bead of the differential thickness material from the arrow XI-XI direction in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thick plate 1A Butting surface 2 Thin plate 2A Butting surface 2B Surface 3 Starting position 4 Ending position 5 Intersection 6 Filling material 7 Laser welding machine 8 Laser beam 8A Beam tip 9, 10 Welding bead 9A, 10A Starting end 9B, 10B Terminal part 9C, 10C Thick board side toe part 9D, 10D Thin board side toe part

Claims (3)

In the laser welding method for differential thickness materials in which laser welding is performed by abutting a thick plate and a thin plate having different thicknesses,
A first welding process and facilities the laser welding, to form a weld bead between the thick plate and thin plate abutting surfaces of the thick plate and thin plate while melting the filler metal by a laser beam,
The bead toe portion of the thin side of the weld bead formed by the first welding step to have a second welding step of melting again by the laser beam,
In the first welding step, laser welding is performed from the start end position toward the end position along the abutting surface of the thick plate and the thin plate, and in the second welding step, welding in the first welding step is performed. A laser welding method for a differential thickness material, comprising: irradiating a laser beam to a bead toe end portion on the thin plate side from an end position in a direction toward a start end position . The optical axis of the laser beam in the second welding step, according to claim 1 comprising setting a range of 1/2 or more of the irradiation area of the beam tip is irradiated to the bead toe portion of the thin side Laser welding method for different thickness materials. In the second welding step, the amount of heat of the laser beam applied to the bead toe portion on the thin plate side is determined by the amount of heat of the laser beam applied to the abutting surface of the thick plate and the thin plate in the first welding step. The laser welding method for a differential thickness material according to claim 1 or 2 , wherein the difference is set to be low.

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