Robot-assisted assembly of high-voltage connectors for electric vehicles
The assembly of five million high-voltage connectors annually for electric and hybrid vehicles places high demands on automated systems. This is especially true when retooling is needed on a daily basis based on variants. A trend-setting system ensures highly flexible production.
Electro-mobility is on everyone's lips. It is also spurring demand for assembly solutions for electric components from specialty machine producers such as Eberhard AG. An international automotive supplier with a challenging project turned to the company, which is headquartered in Schlierbach.
Specifically, the project involved the planning and implementation of an assembly system capable of handling 5,000,000 high-voltage connectors per year. The system should handle not only the actual assembly, but also optical inspection of all assembly steps, leakage tests on the connectors, and finally, their packaging in trays.
Masterpiece of automation in a compact design
Upon first looking at the system, a question arises: How can an assembly system that comprises 13 stations, six robots, and 13 vision systems be implemented in such a compact space? The answer: Arranging the robots so that they are suspended above the stations significantly improves space efficiency.
All six robots are highly precise Stäubli six-axis TX2-60L models, the version with extended reach. The robots were selected not only for their dynamics, but also for their compact design, interface between feeders and cameras, and their unmatched reliability. Four of the six robots are equipped with cameras to capture parts of the feeder system.
The connector assembly follows a clear concept: A quality test takes place after each step. For example, at Station 1: Here, the first TX2-60L takes a connector housing from a feed conveyor and places it into a workpiece carrier, which will carry it through all stations within the system. At Station 2 there is an immediate optical quality control where encoding and color are checked.
Assembly immediately followed by inspection – following this principle, the connector housing goes through all subsequent stations until it is completed. Before the last of the six Stäubli robots transfers the fully assembled high-voltage connector to the palletizing system, another leakage test is performed. To maintain cycle time, Eberhard relies on a rotary table with four stations and a quadruple test fixture. Thanks to this solution, testing does not cause a bottleneck.
Retooling within 10 minutes
Initially, only three versions are running on the system, but their number will soon increase significantly. Thanks to the highly flexible design of the system, this development will be no trouble for the user. From the last part of the current product to the first part of the next, the changeover can be carried out within 10 minutes.
Even during the pre-startup phase, the system was able to beat the required cycle time of three seconds. At present, the cycle time is around 2.7 seconds per high-voltage connector, corresponding exactly to the simulation previously carried out in close cooperation with Stäubli Robotics. The fact that the result of the simulation fully matches reality underscores how precisely processes can be simulated today when the right tools are used. Additionally, Eberhard sees the potential for further cycle time optimization through on-site fine tuning.