Battery Cells Perfectly Welded with 3D Laser Triangulation

Three-dimensional measurements of the welding points on the battery cells are made using 3D laser triangulation with the protruding battery pole in the middle of the cell. (Source: Manz)

Three-dimensional measurements of the welding points on the battery cells are made using 3D laser triangulation with the protruding battery pole in the middle of the cell. (Source: Manz)

Batteries for electric cars are extremely heavy and consist of a large number of cells that are connected by metal strips and welded to a battery module to create the desired circuit. The metal connections are welded at lightning speed using sophisticated automation, with hundreds of welding points made per minute.

Because the height of the battery cells is subject to change due to production tolerances, and because the welding laser has a tight process window, it is necessary to adjust the laser’s focal point for each welding point.

Manz has developed laser welding equipment for this purpose that uses 3D laser triangulation to exactly determine the position and height of the cells in a battery module in all three spatial dimensions. The sensor directs fine lines of blue light onto the top of the cells, where the points for welding the connection strips are located. A camera positioned at an angle measures the reflected light. Height differences between the battery cells appear in the image as steps in the lines of reflected light.

Welding of battery cells with a laser process system. (Source: Manz)

Welding of battery cells with a laser process system. (Source: Manz)

Software from Manz uses all the lines recorded during a pass over the battery pack to create a height-encoded image. Prominent points are highlighted in color. At all points, the precision is finer than 20 µm. The combination of 3D laser triangulation and welding lasers currently achieves more than 500 welds a minute. This pace can even be increased if two or more sensors are used in parallel.

Manz has many years of experience with 3D laser triangulation. The company has previously used the method to determine the evenness of solar cells. Manz has even built several tools for one notebook manufacturer to determine the depth of the pocket in which the touchpad is “seamlessly” inserted. (Source: Manz)

Reference: B. Sattler: Eine heisse Angelegenheit – Batterien automatisiert und schnell verschweissen, Inspect 1/2016, p. 42

Link: Manz AG, Reutlingen, Germany

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