JP5191117B2 - Laser welding method - Google Patents

Description

  The present invention relates to a laser welding method in which welded members such as galvanized steel sheets are overlapped and welded by laser.

  When laser welding is performed with two galvanized steel sheets stacked, spatter is generated violently because zinc vapor generated between the steel sheets blows away the molten metal, and pits and blow holes are generated in the weld bead. Since a weld bead cannot be obtained, it is known to perform laser welding in a state where an appropriate gap is formed between steel plates. As a method of forming such a gap, a forming bead is formed by a laser at a position parallel to the weld bead, one steel plate is warped, a gap is formed between the steel plates, and then a weld bead is formed by the laser. A laser welding method is known (see, for example, Patent Document 1).

Japanese Patent No. 3115456

  However, in the laser welding method disclosed in Patent Document 1, in order to form the forming bead at a position parallel to the weld bead, it is necessary to provide a clamping position on the opposite side of the welding bead with the forming bead interposed therebetween. The clamp position is limited, and there is a problem that the laser welding cannot be performed because the clamp position is not provided depending on the shape of the workpiece to be laser welded. Further, since the forming bead is formed only at a position parallel to the weld bead, there is a problem that a sufficient gap may not be formed.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a laser that can reliably form a necessary gap between overlapped members to be welded. It is intended to provide a welding method.

In order to solve the above problems, the present invention, when welding the overlapped galvanized steel sheet with a laser, after forming a bead with a laser to warp one member, after forming a gap between the galvanized steel sheet , In the method of welding by forming a weld bead with a laser, the formation of the weld bead is performed in a separate process from the formation of the forming bead, and the shape of the forming bead is the end of the galvanized steel sheet on which the forming bead is formed. A forming bead having a shape including a parallel straight portion and a straight portion extending from the straight portion toward the end portion of the member to be welded, or an arc shape in which both ends are bent in the end portion direction of the galvanized steel sheet. And at least most of the weld bead is surrounded by the end of the galvanized steel sheet.

  According to the present invention, since the clamp position is not limited, the shape of the workpiece to be laser welded is not limited. In addition, the necessary gap between the members can be reliably formed by the non-linear forming bead. Further, the clamping position is not limited, and a necessary gap can be secured between the members.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a schematic explanatory view of the laser welding method according to the present invention, and FIG. 2 is a plan view showing an embodiment of the positional relationship between the forming bead and the weld bead.

  In the laser welding method according to the present invention, as shown in FIG. 1 (a), first, the superposed welded members 1 and 2 are clamped by the clamp jigs 3 and 4, and the welding position (weld bead) and clamp position are set. In consideration, the upper welded member 1 is irradiated with the laser 5 and the forming bead 6 is formed only on the upper welded member 1. The forming bead 6 is a bead for thermally deforming the upper member 1 to be welded.

  As shown in FIG. 1C, the clamping position by the clamping jigs 3 and 4 is determined from the positional relationship between the end portion (edge) 1a of the member 1 to be welded and the welding bead 7, and firstly the welding position ( A position 8 that is substantially parallel to the weld bead 7) is desirable, but positions 9 and 10 that are substantially in the same direction as the weld position (weld bead 7) may be used. Instead of the clamp position 8, the welded members 1 and 2 can be clamped at the clamp positions 9 and 10.

  When the forming bead 6 is formed on the upper member to be welded 1, the end portion 1 a of the member to be welded 1 is warped due to thermal contraction caused by irradiation of the laser 5, and a gap 11 is formed between the member to be welded 2. . Here, as shown in FIG. 1 (c), the forming bead 6 is on the opposite side of the end portion 1 a of the member 1 to be welded with the welding position (weld bead 7) sandwiched between the clamping positions 8, 9, 10. And a welding position (weld bead 7) so as to surround the welding position (weld bead 7).

  Next, as shown in FIG. 1B, a welding bead 7 is formed on the welded members 1 and 2 by irradiating the welding position with the laser 5. At this time, if the members to be welded 1 and 2 are galvanized steel plates, zinc vapor generated between the members to be welded 1 and 2 escapes from the gap 11, so that no pits or blow holes are generated in the weld bead 7. Good welding quality can be obtained.

  Various examples showing the positional relationship between the forming bead 6 and the weld bead 7 are shown in FIG. FIG. 2A shows a forming bead 6 comprising a straight portion 6a parallel to the weld bead 7 and two straight portions 6b and 6c non-parallel to the straight portion 6a. The weld bead together with the end 1a of the member 1 to be welded is shown in FIG. 7 is enclosed. FIG. 2 (b) shows a forming bead 6 comprising a straight portion 6a parallel to the weld bead 7 and two straight portions 6b and 6c non-parallel to the straight portion 6a, and welding of a portion facing the end 1a. This is a case of surrounding the bead 7. FIG. 2 (c) shows a forming bead 6 composed of a straight portion 6a parallel to the weld bead 7 and two straight portions 6b and 6c non-parallel to the straight portion 6a, and welding of the portion facing the end 1a. This is a case where most of the bead 7 is surrounded.

  FIG. 2 (d) shows a forming bead 6 comprising a straight portion 6a parallel to the weld bead 7 and two straight portions 6b and 6c which are not parallel to the straight portion 6a and intersect the weld bead 7, and welded together with the end portion 1a. This is a case where most of the bead 7 is surrounded. FIG. 2E shows a case where the welding bead 7 is surrounded by a forming bead 6 including a straight line portion 6a parallel to the weld bead 7 and a single straight line portion 6b non-parallel to the straight line portion 6a. FIG. 2 (f) shows a case where the welding bead 7 is formed together with the end portion 1a by a forming bead 6 including a straight portion 6a parallel to the weld bead 7 and two straight portions 6b and 6c orthogonal to the straight portion 6a. .

  FIG. 2G shows a case where the forming bead 6 has a substantially arc shape and surrounds the weld bead 7 together with the end 1a. FIG. 2 (h) shows a case where the forming bead 6 is composed of two straight portions 6d and 6e that are non-parallel to and intersect with the weld bead 7 and surround the portion of the weld bead 7 facing the end 1a. .

  As shown in FIG. 2, the forming bead 6 is welded in a case where the forming bead 6 is non-linearly formed by a plurality of linear portions 6 a to 6 e or curved portions as shown in FIG. 2. The required gap 11 between the members 1 and 2 can be reliably formed. The reason is that in the case of the forming bead 6 composed of a plurality of straight portions 6a to 6e, the influence range of the straight portions 6a to 6e overlaps around the welding position (weld bead 7). It is because it can earn more.

The positional relationship between the forming bead 6 and the weld bead 7 is not limited to the above-described embodiment (FIGS. 2A to 2H ), and when the forming bead 6 is formed on the upper welded member 1, It is sufficient if the gap 11 required between the members to be welded 1 and 2 is formed.

  The laser welding method according to the present invention can reliably form a required gap between members without being affected by the shape of a member (workpiece) to be laser welded. Contributes to expanding the range.

It is outline | summary explanatory drawing of the laser welding method which concerns on this invention, (a) is sectional drawing of the state in which the forming bead was formed, (b) is sectional drawing in the state in which the welding bead was formed, (c) is a forming bead and a welding bead. View showing the positional relationship between the clamp position The top view which shows the Example ((a)-(i)) about the positional relationship of a forming bead and a welding bead.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Member to be welded, 1a ... End part, 3, 4 ... Clamp jig, 5 ... Laser, 6 ... Forming bead, 7 ... Weld bead, 8, 9, 10 ... Clamp position, 11 ... Gap.

Claims (1)

When welding the overlapped galvanized steel sheets with a laser, a forming bead is formed with a laser to warp one member, and after forming a gap between the galvanized steel sheets , a weld bead is formed with a laser and welded. In the method, the formation of the weld bead is performed in a separate process from the formation of the forming bead, and the shape of the forming bead is a straight portion parallel to an end of the galvanized steel sheet on which the forming bead is formed, and the straight portion from the straight portion. A shape composed of a linear portion extending in the direction of the end of the member to be welded, or an arc shape in which both ends are bent in the direction of the end of the galvanized steel plate, and the forming bead of this shape and the end of the galvanized steel plate A laser welding method characterized in that at least a majority of the weld bead is surrounded . "

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