Aim

The prefabrication of ship segments requires the welding of stiffeners to the main panels. These panels can be up to 30m long and can consistent of several individual steel panels that are joined together by laser.

Creating a 30 m long hybrid fillet weld with a 12kW CO₂ laser and a 900A MSG power source is a challenge in itself. Ensuring that the weld is positioned with a tolerance of less then ±50 µm along the full 30m is an even bigger challenge.

Challenges

The main task was to develop a complete control solution for a new laser hybrid welding machine, based on an existing machine of the production line. General aspects of the control system, such as the interfaces to the master computer were to be maintained.

6 grippers are to  roughly position the stiffeners on the main panel. A guiding carriage is then to position the stiffener exactly along a marking on the panel. Once positioned correctly, the following welding carriage performs the welding operation.

Solution

2 IBH CNC control systems Macro 8000 NT were used for the solution. The first CNC is responsible for the welding process, while the second system controls the grippers and the positioning process.

To allow the exact positioning of the stiffeners with the guiding carriage the CNC-integrated distance control ensures a pre determined distance to the marking on the main panel.Each gripper consists of two linear axis and one round axis, requiring a customized kinematic transformation for the programming within the workpiece coordinate system.

The welding process is performed by a welding carriage. This is controlled by the CNC-integrated seam tracking function developed by ibs Automation in order to ensure the exact position of the weld in relation to the stiffener and the main panel.

A trailing sensor and the CNC-integrated inspection system inspects the resulting weld seam.