JP2012228716A - 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. A laser welding apparatus 10 that irradiates the upper plate 101 with laser, scans the laser irradiated on the upper plate 101, forms a molten pool Y on the upper plate 101, and irradiates the molten pool Y with laser. The upper plate 101 and the lower plate 102 are welded to each other by forming a molten pool Y in the upper plate 101 and the lower plate 102 that are stacked.
[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, according to the first aspect of the present invention, a laser is oscillated from a laser oscillator, the laser is focused by a condensing lens, irradiated to the laminated upper and lower plates, and the laminated upper and lower plates are welded. A laser welding apparatus that irradiates the upper plate with the laser, scans the laser irradiated on the upper plate, forms a molten pool on the upper plate, and irradiates the laser on the molten pool The laminated upper and lower plates are welded by forming a molten pool in the laminated upper and lower plates.

  3. The laser according to claim 2, wherein a laser is oscillated from a laser oscillator, the laser is focused by a condenser lens, irradiated to the laminated upper and lower plates, and the laminated upper and lower plates are welded. In the welding method, the upper plate is irradiated with the laser, the molten laser is formed on the upper plate while scanning the laser irradiated on the upper plate, the laser is irradiated on the molten pool, The laminated upper plate and the lower plate are welded to each other by forming a molten pool in the laminated upper plate and the lower plate.

  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 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 circular shape is formed in a plan view by a laser irradiation locus. In the present embodiment, the laser irradiation trajectory is formed in a circular shape, but may have other shapes such as a rectangular shape or an elliptical shape.

  Further, the laser welding apparatus 10 scans the irradiated laser over a wide range of the upper plate 101 so that the molten pool Y is formed only on the upper plate 101. 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. At this time, the irradiated laser is scanned over a wide range of the upper plate 101 while suppressing the melt-down to the lower plate 102. Here, “melting down” means that the molten metal of the upper plate 101 is melted down to the lower plate 102.

  In other words, in step S110, the welding conditions for laser irradiation are such that if the irradiation is performed in a narrow range of the upper plate 101, the lower plate 102 is melted down. Here, the welding conditions refer to laser output, laser operation speed, and laser focused diameter. However, in step S110, since the irradiated laser is scanned over a wide range of the upper plate 101, the melting of the lower plate 102 is suppressed.

  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 irradiates the molten pool Y formed only on the upper plate 101 with laser. More specifically, the laser welding apparatus 10 irradiates the center of the molten pool Y formed in a circular shape in plan view with a laser. Furthermore, in step S120, the laser is irradiated under welding conditions having energy stronger than the welding conditions in step S110.

The operation of the laser welding method S100 will be described with reference to FIG.
In step S110, the laser welding apparatus 10 irradiates the laminated upper plate 101 and lower plate 102 with laser from above. At this time, since the irradiated laser is scanned over a wide range of the upper plate 101, the entire upper plate 101 and a part of the lower plate 102 are melted in a side sectional view. And the molten pool Y is formed in the upper board 101 which the whole fuse | melts by side surface sectional view. At this time, the upper plate 101 is melted by keyhole melting. Here, the keyhole melting means that the heat source penetrates to the back side of the base material and melts at the tip of the molten pool Y.

  In step S120, the laser welding apparatus 10 irradiates the laminated upper plate 101 and lower plate 102 with laser from above. At this time, since the laser is irradiated to a narrow range of the molten pool Y, the entire molten pool Y of the upper plate 101 and the entire molten pool Y of the lower plate 102 are melted in a side sectional view. And the molten pool Y is formed in the whole upper board 101 and the whole lower board 102 by side surface sectional view. The molten pool Y that is integrated into one becomes a joint portion without drilling or separation beads.

The effect of the laser welding method S100 will be described.
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, the upper plate 101 and the lower plate 102 having a plate gap of 1 mm can be welded without lowering the bonding strength.

  Conventionally, 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 welding that has been penetrated by the second laser irradiation has been performed. . However, in this welding method, since the first laser irradiation is low energy, the upper plate was melted by heat transfer instead of keyhole melting. For this reason, the processing time is increased and the productivity is reduced. According to the laser welding method S100, since the upper plate 101 is melted by keyhole from the first laser irradiation (step S110), the processing time is shortened and the productivity is improved.

  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. However, it is necessary to irradiate the laser according to the welding conditions of strong energy that melts even the lowest steel plate.

  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 plate 102 Lower plate Y Molten pool

Claims (2)

Oscillate laser from laser oscillator,
Focusing the laser with a condenser lens, irradiating the laminated upper and lower plates,
A laser welding apparatus for welding the laminated upper and lower plates,
While irradiating the upper plate with the laser and scanning the laser irradiated on the upper plate, forming a molten pool on the upper plate,
Irradiating the molten pool with the laser and welding the laminated upper and lower plates by forming a molten pool in the laminated upper and lower plates;
Laser welding equipment. Oscillate laser from laser oscillator,
Focusing the laser with a condenser lens, irradiating the laminated upper and lower plates,
A laser welding method for welding the laminated upper and lower plates,
While irradiating the upper plate with the laser and scanning the laser irradiated on the upper plate, forming a molten pool on the upper plate,
Irradiating the molten pool with the laser and welding the laminated upper and lower plates by forming a molten pool in the laminated upper and lower plates;
Laser welding method.

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