RoKtoLas - Robot guided, scanner based Optical Coherence Tomography for remote laser beam welding to increase the flexibility of process chains in car body construction

Using an innovative sensor concept, remote laser beam welding is to be qualified for large-area use in automotive body construction. For this purpose, the joint project RoKtoLas is researching highly flexible production systems for the use in car body construction.

Innovative leap in automotive body construction

In order to be able to control the rising number of variants due to an increasing electrification as well as the ever faster innovation and product life cycles, RoKtoLas aims to achieve an innovative leap in automotive body construction. This is to be realized by a technology substitution in the field of joining technology, whereby conventional resistance spot welding is to be replaced by remote laser beam welding.

The project focuses on an optical sensor unit, which for the first time will enable an holistic and universal process monitoring in real time. In addition, an adapted component design and robot-based clamping technology form the core components for the construction of highly flexible production systems in body construction.

Optical coherence tomography - a universal and innovative sensor concept for remote laser beam welding

The sensor system based on optical coherence tomography (OCT) forms the core of the solution approach for making automotive bodywork production more flexible. The OCT system allows a comprehensive generation of process data in the area of the joining zone. Due to the measuring principle, which is based on an interferometer design, the seam position, the welding depth and the seam topography can be determined largely independently of process emissions. This allows dynamic seam tracking, real-time process control and comprehensive quality assurance to be combined in one system.

Remote laser beam welding for flexible production in electromobility

Conventional joining processes in car body construction severely limit the component design due to the rigid geometry of the clamping devices used. Remote laser beam welding, on the other hand, places much lower demands on the accessibility of the joint and thus permits a component design more suited to the load. In addition, a fixture-free joining can be made possible by an adapted component design. To this end, a robot-based clamping technology is being designed and developed as part of the project. The clamping situation can be assessed on the basis of the data from the optical sensor and adjusted using active grippers. In order to control tolerances and make efficient use of the large number of degrees of freedom of the new clamping technology, an intelligent positioning of components is to be developed by methods of machine learning.

In summary, the new optical sensor concept enables a comprehensive process data generation in the sense of a networked production and thus represents the prerequisite for the implementation of a highly flexible production. At the end of the project, the findings will be combined by a functional demonstrator of a flexible production cell.

Acknowledgement

The project presented is funded by the Federal Ministry of Education and Research (BMBF) under the funding code 13N14555 and supervised by the VDI Technology Center (VDI TZ). We thank the BMBF and the VDI TZ for their support and the good and trusting cooperation.