JP2006315062A - Laser beam welding method and structure formed thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam welding method which easily controls the size of a clearance to be set up between base materials. <P>SOLUTION: In the invented laser beam welding method, an embossed portion 6 is preformed in a bracket 2 to be welded to a member 1. The embossed portion 6 is convexed toward the member 1, is shaped like a shallow saucer and has a spherical surface. The member 1 and the bracket 2 are welded on the inclined plane of the embossed portion 6 as a weld zone with a weld bead 4 which is concentric with the embossed portion 6 and has a nearly looped C shape. The clearance 7 is set up between the embossed portion 6 and the member 1. The clearance 7 gradually increases in size as the distance from the center of the embossed portion 6 increases. A ring-shaped proper welding region M in set up such that it is concentric with the weld bead 4 and is defined by the lower limit value G1 and upper limit value G10 of the clearance 7 required for attaining satisfactory welding quality. Welding is performed by irradiating a laser beam 5 to the proper welding region M. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser welding method and a laser welding structure, and more particularly to a laser welding method and a laser welding structure suitable for welding a surface treatment material such as a plated steel plate.

When laser welding is performed by superimposing a base material such as a steel plate, if the base material itself is a so-called surface-treated material such as a plated steel plate, the plating layer on the base material surface evaporates due to heat during welding and gas ( In some cases, defects such as bubbles (blow holes) or porosity remain in the weld bead, or welding defects such as holes may occur. As a countermeasure, based on the knowledge that the occurrence of blowholes can be suppressed if the base materials to be welded are not completely in close contact with each other, a gap serving as a guide path for discharging the gas during welding to the outside is provided. Techniques for securing between the base materials are proposed in Patent Documents 1-3. That is, in Patent Documents 1 to 3, etc., a protrusion is formed in advance on one base material in order to positively secure a gap between the base materials to be welded.
Japanese Patent Laid-Open No. 10-216974 JP 10-193149 A Japanese Examined Patent Publication No. 4-13077

  However, in the conventional techniques represented by Patent Documents 1 to 3, the gap as a guide path secured between the base materials depends on the height dimension of the protrusion, but the base during welding Considering pressure correction between materials, it is very difficult to strictly control or manage the size of the gap due to bending of the base material. For example, when the base metal plate thickness is about 1 mm, the optimum range of the gap that can satisfy the welding quality is about 0.1 to 0.3 mm, but the size of the gap is set to be within this range. It was difficult to manage.

  The present invention has been made paying attention to such a problem, and provides a laser welding method and a laser welding structure in which functions equivalent to those of the prior art can be obtained by a simpler method.

  The invention according to claim 1 is a shallow dish-like embossed portion that is convex toward the other base material and includes an inclined surface on one of two base materials that are to be overlapped with each other as a welding target. Is formed in advance, and welding is performed by irradiating a laser beam with the inclined surface of the embossed portion as a welded portion.

  More specifically, as described in claims 2 and 3, the shape of the shallow dish-shaped embossed portion is a spherical shape, a conical surface shape or a truncated cone shape that contacts the other base material at the center thereof. Thus, welding is performed in a state where a gap that gradually increases as the distance from the center of the embossed portion is set between the embossed portion and the other base material.

  Then, as described in claim 4, welding is performed with a loop-shaped welding line concentric with the embossed portion, and more specifically, welding quality is improved as described in claim 5. A ring-like welding proper area that is concentric with the loop-shaped welding line in a plan view is set with the lower and upper limits of the gap necessary for filling, and welding is performed by irradiating the appropriate welding area with laser light. Shall be applied.

  Further, the invention according to claim 7 captures the technique according to claim 1 as a welded structure, in which one of two base materials superimposed on each other as a welding target is added to the other base. A shallow dish-like embossed portion that is convex toward the material and includes an inclined surface is formed in advance, and laser welding is performed using the inclined surface of the embossed portion as a welded portion.

  Therefore, in at least the inventions of the first and seventh aspects, since a gap that gradually increases as the distance from the center of the embossed portion increases between the base materials, a part of the inclined surface of the embossed portion is excellent. If welding is performed by irradiating a laser beam after it is specified as a weldable portion, it is possible to perform good welding without the need for troublesome gap management as in the prior art.

  According to the first and seventh aspects of the present invention, since a gap that gradually increases as the distance from the center of the embossed portion increases between the base materials, a range that can be satisfied with the welding quality among the gaps. If welding is specified on an inclined surface, good laser welding can be performed without the need to strictly manage the size of the gap as in the prior art.

  FIGS. 1 to 3 are views showing a preferred embodiment of the present invention. In particular, as shown in FIG. 1, a channel-like member 1 as one base material is provided with a crank-like bracket 2 as the other base material. The example in the case of joining by laser welding is shown.

  As shown in FIG. 1, the member 1 is made of, for example, a plated steel plate, whereas the bracket 2 is made of a normal steel plate, and a flange portion 3 bent at one end of the bracket 2 is formed on the member 1. 2 and 3, with the flange portion 3 as a welded portion, a weld bead 4 as a substantially C-shaped loop-shaped weld line having a part opened is welded. That is, when the flange portion 3 is irradiated with the laser beam 5, the laser beam 5 is scanned by a remote laser welding method into a substantially C-loop shape to perform laser welding with a substantially C-shaped weld bead 4. .

  A spherical embossed portion 6 that is convex toward the member 1 side is bulged and formed in a so-called shallow dish shape at the center of the flange portion 3, and on the member 1 as shown in FIG. When the bracket 2 is erected with the flange portion 3 as a seating surface, the embossed portion 6 has a spherical inclined surface 6a. A gap 7 is set between the member 1 and the embossed portion 6 so as to be point-contacted and gradually increase as the distance from the center of the embossed portion 6 increases.

  Then, in consideration of the plate thickness of the member 1 or the bracket 2 or the radius of curvature R of the embossed portion 6 and the required welding strength, the minimum dimension G1 and the maximum dimension G10 of the gap 7 that can satisfy the welding quality after laser welding are set. On the other hand, a ring-shaped region that is surrounded by the circle having the minimum dimension G1 and the circle having the maximum dimension G10 and that is concentric with the embossed portion 6 is referred to as an appropriate welding region M. The laser beam 5 is scanned in a substantially C-shaped loop by the above-described remote laser welding method, and laser welding is performed with a substantially C-shaped weld bead 4.

  Here, for example, it is assumed that laser welding is performed by setting the diameter Db of the loop formed by the weld bead 4 to φ8, for example, and the variation in the diameter Db is Db ± 1.0. Considering the variation of the weld bead 4, it is necessary to set the proper welding region M in the range of φ6 to φ10.

  As described above, when the gap 7 that can satisfy the welding strength is 0.1 to 0.3 mm, the gap at the position of the circle D1 (= φ6) having the minimum dimension G1 is 0.1 mm or more and the circle having the maximum dimension G10. The gap at the position D2 (= φ10) needs to be 0.3 mm or less.

  Here, if the gap 7 at the position of the circle D2 (= φ10) of the maximum dimension G10 is 0.3 mm, the gap 7 at the center of the circle D2 is 0, so the radius of curvature of the spherical embossed portion 6 The magnitude of R is determined as R = 41.8 (≈42). Then, when the gap G1 at the position of the circle D1 (= φ6) of the minimum dimension G1 in the embossed portion 6 with the radius of curvature R = 41.8 is calculated, it is 0.11 mm, and the condition of 0.1 mm or more is seen This is a valid solution.

  Finally, the maximum diameter Dm of the embossed part 6 and the dimension Gn of the gap 7 at that position (gap in the general part other than the embossed part 6) are determined. Here, when the gap Gn in the general portion is 0.5 mm, the maximum diameter Dm of the embossed portion 6 is calculated as φ12.9 (≈13.0) when calculated backward from the radius of curvature R = 41.8 of the embossed portion 6. it can. In this way, the design shape is determined.

  Therefore, according to this embodiment, the gap 7 that gradually increases as the distance from the center of the embossed portion 6 is ensured between the member 1 that is the base material and the flange portion 3 on the bracket 2 side. Since the C-shaped loop-shaped weld bead 4 can satisfy the required welding quality as long as it is within at least the ring-shaped appropriate welding region M set in advance, the laser is arranged so as to fit within the appropriate ring-shaped welding region M. It is only necessary to form the weld bead 4 having a substantially C-shaped loop shape while scanning the beam 5, and strict management of the size of the gap 7 as in the prior art is not necessary.

  Moreover, even if metal gas is generated from the member 1 which is a plated steel plate as a result of welding, the metal gas can be discharged smoothly from the gap 7, so that the blow by confining the metal gas into the molten metal is possible. Of course, the occurrence of holes and porosity can also be prevented.

  In particular, the ring-shaped proper welding region M is a circular belt having a certain distance from the center of the spherical embossed portion 6, so that it is a very efficient permissible region for welding with the loop-shaped welding bead 4. Can be set.

  Moreover, the center of the embossed portion 6 is point-contacted with the counterpart member 1 so that a minute gap can be easily and reliably secured between the two. The gap 7 ((G1 to G10 = 0.1 to 0.3 mm in the example of FIG. 2) having a dimension (0.5 mm in the example of FIG. 2) that is slightly smaller than that and can be managed can be managed. It becomes very easy.

  In addition, since the embossed part 6 itself has high rigidity, even if the member 1 and the bracket 2 that are the base materials are pressure-corrected with a straightening device during welding, for example, it is possible to reliably secure the appropriate welding region M. It becomes possible.

  FIG. 4 shows a second embodiment of the present invention in which an elliptical spherical embossed portion 16 is used instead of the spherical embossed portion 6 shown in FIG.

  FIG. 5 shows a third embodiment of the present invention, and the same reference numerals are given to the portions common to FIG. In the second embodiment, a flat conical embossed portion 26 is used in place of the spherical embossed portion 6, and the top of the embossed portion 26 is in point contact with the member 1 on the other side. Welded. In the case of the embossed portion 26 having a flat conical shape, it is possible to reliably make point contact with the counterpart member 1, so that the appropriate welding region M is not reduced.

  More specifically, as shown in FIG. 5, assuming that the diameter Db formed by the loop of the weld bead 4 is φ8 and the variation is φ8 ± 1.0, the appropriate welding region M is φ6 to φ10 as a range of D1 to D2. Since the gap 7 within the same range is 0.18 to 0.3 mm and satisfies the required conditions (G1 to G10 = 0.1 to 0.3 mm), the appropriate welding region M is determined. become. Furthermore, even if the variation in the diameter Db of the weld bead 4 is φ8 ± 2.0, the gap 7 in the proper welding region M satisfies G1 to G10 0.1 to 0.3 mm and satisfies the requirements. In particular, the conical embossed portion 26 is more advantageous against variations in the diameter Db of the weld bead 4.

  6 and 7 show a fourth embodiment of the present invention, in which a truncated cone shaped embossed portion 36 is adopted as an embossed portion, and its top flat surface 36a is brought into surface contact with the member 1 on the other side. It is. In this case, the bracket 2 is stable with respect to the member 1 and can be easily positioned.

  8 and 9 show a fifth embodiment of the present invention. In this embodiment, when the bracket 12 having a so-called hat-shaped cross section is welded to the member 11 using the flange portion 13 as a welded portion, a plurality of embossed portions 6 independent from each other along the longitudinal direction of the flange portion 13 are provided. It is set and laser welding is applied to each.

  FIG. 10 shows a sixth embodiment of the present invention, in which a plurality of embossed portions 6 are provided in a staggered manner on a flange portion 13 to be welded as shown, and the flange portion 13 is a long bracket. Also, a stable state can be taken at the time of welding, and the management of the gap becomes easier.

  Further, FIG. 11 shows a seventh embodiment of the present invention. When welding the so-called bag-structure bracket 14 to the member 10 which is the other side with the flange portion 15 as a welding portion, A plurality of embossed portions 6 are set.

  In this structure, even if the bracket 14 itself has a bag structure, a predetermined gap 17 is ensured between the flange portion 15 and the member 10 after welding. Even when the coating is applied, the liquid can be surely drained, and so-called air accumulation and liquid accumulation can be prevented in advance.

The perspective view which shows the shape of the base material used as welding object as more concrete embodiment of this invention. The expanded sectional view which follows the AA line of FIG. Plane explanatory drawing of the embossed part in FIG. The principal part perspective view which shows another example of an embossing part as the 2nd Embodiment of this invention. Sectional drawing of the welding part which shows the 3rd Embodiment of this invention. The perspective view which shows the shape of the preform | base_material used as welding object as the 4th Embodiment of this invention. Sectional drawing which follows the BB line of FIG. The principal part perspective view which shows the shape of the preform | base_material used as welding object as the 5th Embodiment of this invention. Sectional drawing in alignment with CC line of FIG. The principal part perspective view which shows the 6th Embodiment of this invention. The principal part perspective view which shows the 7th Embodiment of this invention.

Explanation of symbols

1 ... Member (base material)
2 ... Bracket (base material)
3 ... Flange 4 ... Weld bead (welding line)
5 ... Laser beam 6 ... Embossed portion 6a ... Inclined surface 7 ... Gap 10 ... Member (base material)
11 ... Member (base material)
12 ... Bracket (base material)
13 ... Flange part 14 ... Bracket (base material)
DESCRIPTION OF SYMBOLS 15 ... Flange part 16 ... Embossed part 17 ... Gap 26 ... Embossed part 36 ... Embossed part 36a ... Top part plane M ... Proper welding area

Claims (12)

A shallow dish-shaped embossed portion that is convex toward the other base material and includes an inclined surface is formed in advance on either one of the two base materials that are to be overlapped with each other as a welding target,
A laser welding method comprising performing welding by irradiating a laser beam with the inclined surface of the embossed portion as a welded portion.   The shape of the shallow dish-like embossed portion is spherical or conical in contact with the other base material at the center, and is away from the center of the embossed portion between the embossed portion and the other base material. Therefore, the laser welding method according to claim 1, wherein welding is performed in a state where a gradually increasing gap is set.   The shape of the shallow dish-shaped embossed portion is a truncated cone shape that comes into contact with the other base material at the center thereof, and gradually increases from the center of the embossed portion between the embossed portion and the other base material. The laser welding method according to claim 1, wherein welding is performed in a state in which a gap that becomes large is set.   The laser welding method according to claim 2 or 3, wherein welding is performed with a loop-shaped welding line concentric with the embossed portion.   A ring-shaped appropriate welding area that is concentric with the loop-shaped welding line in plan view is set with the lower and upper clearance limits necessary to satisfy the welding quality, and laser light is irradiated to this appropriate welding area. The laser welding method according to claim 4, wherein welding is performed.   A plurality of shallow dish-shaped embossed portions that are convex toward the other base material and include an inclined surface are formed in advance on one of the two base materials that are to be overlapped with each other as a welding target. The laser welding method according to claim 1, wherein: In either one of the two base materials superimposed on each other as the object to be welded, a shallow dish-shaped embossed portion that is convex toward the other base material and includes an inclined surface is formed in advance.
A laser welding structure characterized in that laser welding is performed using the inclined surface of the embossed portion as a welded portion.   The shape of the shallow dish-like embossed portion is spherical or conical in contact with the other base material at the center, and is away from the center of the embossed portion between the embossed portion and the other base material. Therefore, the laser welding structure according to claim 7, wherein welding is performed in a state where a gradually increasing gap is set.   The shape of the shallow dish-shaped embossed portion is a truncated cone shape that contacts the other base material at the center, and gradually increases as the distance from the center of the embossed portion increases between the embossed portion and the other base material. The laser welding structure according to claim 7, wherein welding is performed in a state in which a gap is set.   The laser welding structure according to claim 8 or 9, wherein welding is performed with a loop-shaped welding line concentric with the embossed portion.   A ring-shaped appropriate welding area that is concentric with the loop-shaped welding line in a plan view is set in advance with the lower limit and upper limit of the gap necessary to satisfy the welding quality. The laser welding structure according to claim 10, wherein welding is performed by irradiating light.   A plurality of shallow dish-shaped embossed portions that are convex toward the other base material and include an inclined surface are formed in advance on one of the two base materials that are to be overlapped with each other as a welding target. The laser welded structure according to any one of claims 6 to 11.

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