JP2012228717A - Laser welding apparatus and laser welding method - Google Patents

Abstract

The present invention provides a laser welding apparatus and a laser welding method capable of welding without reducing the bonding strength even in a large plate gap.
A laser is oscillated from a laser oscillator, the laser is focused by a condenser lens, irradiated to a laminated upper plate and a lower plate, and the laminated upper plate and lower plate are welded. In the laser welding apparatus 10, the upper plate 101 and the lower plate 102 are irradiated with laser to form a molten pool Y on the laminated upper plate 101 and lower plate 102, and the outer edge E of the molten pool Y is formed. Laser irradiation is performed to melt the outer edge portion E, and the upper plate 101 and the lower plate 102 that are laminated are welded.
[Selection] Figure 1

Description

  The present invention relates to a technique of a laser welding apparatus and a laser welding method.

  Laser welding is a welding method in which a laser oscillated from a laser oscillator is focused by a condensing lens and irradiated to a laminated steel sheet for welding. However, in laser welding, when the gap between the steel plates to be laminated is large, the bonding strength is reduced. For example, when there is a plate gap of 0.3 mm or more, the weld bead surface may drop and the bonding strength may decrease. Further, when the plate gap is larger than 0.5 mm, perforation may occur and bonding strength may be reduced.

  In the welding of a three-dimensional shape such as an automobile body, it is difficult to properly manage the plate gap to be, for example, 0.3 mm or less. On the other hand, when manufacturing an automobile body or the like, a plate gap of about 1 mm is allowed in operation. Therefore, it has been a problem to weld a plate gap of about 1 mm without reducing the bonding strength. Currently, several countermeasures have been taken as measures for lowering the joint strength of laser welding of large plate gaps.

  Patent Document 1 discloses a method of welding by managing a plate gap using a shim roller. However, when welding an automobile body or the like, two or three steel plates may be welded. Therefore, in the welding method disclosed in Patent Document 1, it is necessary to perform shim replacement or the like at a high frequency, and productivity is reduced.

  Patent Document 2 discloses a method of performing laser tack welding alternately with a welding site using a clamp device. However, the welding method disclosed in Patent Document 2 requires a dedicated large clamp device when welding an automobile body or the like. Moreover, in the welding method disclosed in Patent Document 2, when welding a galvanized steel sheet, poor welding due to plating vapor blowing occurs by laser tack welding.

  In Patent Document 3, the first laser irradiation is performed in a defocused state, the upper plate is melted and protruded to the lower plate side to reduce the gap, and the welding that penetrated by the second laser irradiation is performed. Yes. However, in the welding method disclosed in Patent Document 3, since the first laser irradiation is low energy, the upper plate is melted by heat transfer instead of keyhole melting. Therefore, processing time becomes long and productivity falls.

JP 2004-025219 A JP 2005-131707 A JP 2010-023047 A

  The problem to be solved by the present invention is to provide a laser welding apparatus and a laser welding method capable of welding without reducing the bonding strength even in a large plate gap.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, the laser welding apparatus according to claim 1, wherein a laser is oscillated from a laser oscillator, the laser is focused by a condensing lens, irradiated to a plurality of stacked plates, and the stacked plurality of plates are welded. And irradiating a plurality of plates with the laser, forming a molten pool on the plurality of stacked plates, irradiating the outer edge of the molten pool with the laser to melt the outer edge, The plurality of laminated plates are welded.

  According to a second aspect of the present invention, there is provided a laser welding method in which a laser is oscillated from a laser oscillator, the laser is focused by a condensing lens, irradiated to a plurality of stacked plates, and the stacked plurality of plates are welded. The plurality of plates are irradiated with the laser, a molten pool is formed on the plurality of stacked plates, the laser is irradiated to the outer edge of the molten pool, and the outer edge is melted, Welding a plurality of plates.

  According to the laser welding apparatus and the laser welding method of the present invention, welding can be performed without a decrease in bonding strength even in a large plate gap.

The block diagram which showed the structure of the laser welding apparatus which concerns on embodiment of this invention. The flowchart which shows the flow of the welding method of embodiment of this invention. The schematic diagram which shows the effect | action of the welding method of embodiment of this invention. The schematic diagram which shows the effect of the welding method of embodiment of this invention.

The laser welding apparatus 10 will be described with reference to FIG.
The laser welding apparatus 10 is an embodiment of the laser welding apparatus of the present invention. The laser welding apparatus 10 is an apparatus that performs laser welding. Laser welding is a welding method in which laser light is applied to a metal as a heat source and irradiated to locally melt and solidify the metal.

  In the following embodiment, in order to constitute an automobile body by laser welding using the laser welding apparatus 10, the upper plate 101 and the lower plate 102, which are two laminated steel plates, are welded. Further, it is assumed that the plate gap between the laminated upper plate 101 and lower plate 102 is 1 mm.

The configuration of the laser welding apparatus 10 will be described.
The laser welding apparatus 10 includes a laser oscillator 11, an optical path 12, a laser irradiation head 13, and a condenser lens 14. The laser oscillator 11 oscillates a CO2 laser or a YAG laser as a heat source for welding. The optical path 12 guides the laser oscillated by the oscillator to the laser irradiation head 13. The optical path 12 transmits the laser by turning it back with a mirror, or transmits the laser by bending it with an optical fiber.

  The laser irradiation head 13 irradiates the upper plate 101 and the lower plate 102 with the laser beam transmitted through the optical path 12 from above the upper plate 101. The laser irradiation head 13 is moved to above the upper plate 101 by a robot (not shown). The condensing lens 14 condenses and irradiates the laser transmitted through the optical path 12 to an appropriate size, and scans the workpiece. The condenser lens 14 is housed inside the laser irradiation head 13.

The operation of the laser welding apparatus 10 will be described.
The laser welding apparatus 10 oscillates a laser from a laser oscillator 11, focuses the laser oscillated from the laser oscillator 11 by a condenser lens 14, and stacks the lasers focused by the condenser lens 14. The upper plate 101 and the lower plate 102 are welded to each other.

The laser welding method S100 will be described with reference to FIGS.
Laser welding method S100 is an embodiment of a laser welding method using the laser welding apparatus of the present invention. Each step in FIG. 2 corresponds to each step in FIG. FIG. 3B is a cross-sectional view taken along the line AA in FIG.

The flow of the laser welding method S100 will be described with reference to FIG.
In step S <b> 110, the laser welding apparatus 10 irradiates laser from above the laminated upper plate 101 and lower plate 102. At this time, the laser welding apparatus 10 scans the irradiated laser so that a rectangle is formed by the laser irradiation locus. In this embodiment, the rectangle is formed by the laser irradiation locus. However, other shapes such as a circular shape and an elliptical shape may be used.

  When laser irradiation is scanned so as to form a rectangle, in a plan view, the inside of the rectangle formed by the irradiated laser, and in a side cross-sectional view, the portion including the upper plate 101 and the lower plate 102 is melted. A pond Y is formed. Here, the molten pool Y refers to a pool of molten metal formed by melting the upper plate 101 or the lower plate 102 by arc heat, other heat, or the like during welding.

  In step S <b> 120, the laser welding apparatus 10 irradiates laser from above the laminated upper plate 101 and lower plate 102. At this time, the laser welding apparatus 10 scans the irradiated laser on the outer edge E of the molten pool Y formed by the upper plate 101 and the lower plate 102. Here, the outer edge portion E refers to the outer peripheral portion of the molten pool Y formed by the upper plate 101 and the lower plate 102.

The operation of the laser welding method S100 will be described with reference to FIG.
In step S110, laser irradiation is scanned by the laser welding apparatus 10 so that a rectangle is formed. At this time, the upper plate 101 and the lower plate 102 are melted. Then, a molten pool Y is formed in a rectangular interior formed by the irradiated laser in a plan view and in a portion including the upper plate 101 and the lower plate 102 in a side sectional view.

  In step S <b> 120, laser irradiation is scanned on the outer edge E of the formed weld pool Y by the laser welding apparatus 10. At this time, the surface layer portion of the outer edge portion E of the upper plate 101 is melted. When the surface layer portion of the outer edge portion E of the upper plate 101 is melted, the surface layer portion of the upper plate 101 around the molten pool Y flows into the central portion of the weld mark. When the surface layer portion of the upper plate 101 around the molten pool Y flows into the central portion of the weld trace, the weld trace becomes flat.

The effect of the laser welding method S100 will be described with reference to FIG.
4A shows a side sectional view before step S120 of the laser welding method S100, and FIG. 4B shows a side sectional view after step S120.

  Here, the shortest distance from the outer periphery of the welded portion on the lower surface of the upper plate 101 to the upper end of the central portion of the weld mark is defined as the thickness T of the welded portion (see FIGS. 4A and 4B). The welding strength increases as the thickness T of the welded portion increases, and the welding strength decreases as the thickness T of the welded portion decreases. Moreover, the depth of the dent of the welding trace (the distance from the upper end of the welding trace to the upper surface of the upper plate 101) is defined as the depth D of the welding trace (see FIGS. 4A and 4B). The welding strength increases as the depth D of the welding mark decreases, and the welding strength decreases as the depth D of the welding mark increases.

  In laser welding, when the plate gap between the upper plate 101 and the lower plate 102 is large, the depth D of the welding mark is increased and the thickness T of the welded portion is reduced, so that the bonding strength is reduced. However, in the laser welding method S100 of the present embodiment, the outer edge E of the weld pool Y is scanned with laser irradiation to flatten the weld trace, thereby increasing the thickness T of the weld and increasing the depth of the weld trace. D is reduced. Therefore, even when the plate gap between the upper plate 101 and the lower plate 102 is large, welding can be performed without reducing the bonding strength.

  Conventionally, in a three-dimensional welding of an automobile body or the like, it has been difficult to properly manage the plate gap to be, for example, 0.3 mm or less. On the other hand, when manufacturing an automobile body or the like, a plate gap of about 1 mm is allowed in operation. Therefore, it has been a problem to weld a plate gap of about 1 mm without reducing the bonding strength. According to the laser welding method S100 of this embodiment, the upper plate 101 and the lower plate 102 having a plate gap of 1 mm can be welded without reducing the bonding strength.

  In the laser welding method S100 of the present embodiment, the depth D of the welding trace is reduced by scanning the outer edge E of the molten pool Y with laser irradiation and flattening the welding trace. For this reason, post-processing of the weld mark can be easily performed.

  In the present embodiment, the laser is irradiated from above the laminated upper plate 101 and lower plate 102 (two steel plates), but the present invention is not limited to this. The same effect can be obtained even when the laser is irradiated from above three or more stacked steel plates.

  In the present embodiment, the steel plate is used as the workpiece, but the present invention is not limited to this. For example, the same effect can be obtained even when an aluminum plate is used as the workpiece.

DESCRIPTION OF SYMBOLS 10 Laser welding apparatus 11 Laser oscillator 12 Optical path 13 Laser irradiation head 14 Condensing lens 101 Upper board 102 Lower board D Depth E Outer edge part T Thickness Y Molten pool

Claims (2)

Oscillate laser from laser oscillator,
The laser is focused by a condenser lens and irradiated to a plurality of laminated plates,
A laser welding apparatus for welding the plurality of laminated plates,
Irradiating a plurality of plates with the laser to form a molten pool in the plurality of stacked plates,
Irradiating the outer edge of the molten pool with the laser to melt the outer edge,
Welding the plurality of laminated plates;
Laser welding equipment. Oscillate laser from laser oscillator,
The laser is focused by a condenser lens and irradiated to a plurality of laminated plates,
A laser welding method for welding the plurality of laminated plates,
Irradiating a plurality of plates with the laser to form a molten pool in the plurality of stacked plates,
Irradiating the outer edge of the molten pool with the laser to melt the outer edge,
Welding the plurality of laminated plates;
Laser welding method.

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