Method of Laser Welding

Abstract

A method of joining a first and a second object, each object having a substantially flat surface. The method includes the steps of: placing the objects with their surfaces in a contacting relationship along an interface, with their surfaces substantially parallel, the interface having a peripheral edge, irradiating a laser beam with a focal point onto the peripheral edge in the direction of the interface while the plates are in a contacting relationship, and moving the focal point of the laser beam along the interface in a direction transversely to the edge, to a position at a distance from the edge.

Claims

1. A method of joining a first object and a second object, each object having a substantially flat surface, the method comprising the steps of: placing the objects with their surfaces in a contacting relationship along an interface, with their surfaces substantially parallel, the interface extending to a peripheral edge, irradiating a laser beam with a focal point onto the peripheral edge in a direction of the interface while the objects are in a contacting parallel relationship, and moving the focal point of the laser beam along the interface in a direction transverse to the peripheral edge, to a position at a distance from D the peripheral edge.

2. The method according to claim 1, wherein the first object comprises aluminum, and the second object comprises copper.

3. The method according to claim 1, wherein a dimension of the focal point of the laser beam is between 0.01 mm and 0.5 mm and the distance D from the peripheral edge is between 0.5 mm and 50 mm.

4. The method according to claim 1, wherein the power of the laser bream is at least 2500 W.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] An embodiment of the laser welding method will, by way of non-limiting example, be described in detail with reference to the accompanying drawings. In the drawings:

[0013] FIG. 1 shows a schematic lay-out of the laser welding method according to the disclosure,

[0014] FIG. 2 shows a side view of a laser weld formed between an aluminum and a copper strip, and

[0015] FIG. 3 shows a view of a cross-section of the weld of FIG. 2 on an enlarged scale, in a vertical orientation.

DESCRIPTION OF EMBODIMENTS

[0016] FIG. 1 shows an aluminum plate 1 and a copper plate 2, each with a substantially flat contact surface 3, 4. The surfaces 3, 4 are placed in a contacting relationship along the interface 5.

[0017] The plates 1,2 may have a thickness T of for instance 1 mm-10 mm and may be of larger thickness such as up to 20 mm and more.

[0018] A laser source 10 generates a laser beam 8 that is focused through optics 12 in a focal point 9 onto a perimeter 7 of the plates 3, 4 at the position of the interface 5. In a test set up, a copper and aluminum plate were placed, according to the disclosure, with their flat surfaces in a contacting relationship, each plate having a thickness of 3 mm. Using a Trudisk 6001 laser welding device, marketed by the Trumpf GmbH, Germany, at a Laser power of 3000 W and a focal spot diameter of 0,17 mm, the laser was irradiated onto the perimeter 7 of the stacked plates, to melt the metal surfaces on each side of the interface 5.

[0019] The focal point 9 of the laser penetrated a distance D of over 5 mm between the plates 1,2, and as long as several cm, along the interface 5, away from the perimeter 7.

[0020] FIG. 2 shows an example of the weld 15 formed along the interface 5 of an aluminum plate 1 and copper plate 15 along a length D that may be up to several cm, or longer.

[0021] FIG. 3 shows an enlarged cross-section of the weld 15, in a vertical orientation, along which a homogeneous alloy of the copper and aluminum is formed over a large surface area and a strong bond is achieved.