A firm grip on non-rigid parts: KR CYBERTECH automates battery pack assembly

The future belongs to electric vehicles. They are quiet, increasingly powered using renewable energy sources, cause lower CO2 emissions and lead to lower repair and maintenance costs. Around the globe, more than 27 million plug-in hybrids and electric cars are on the roads already. That number will rise significantly between 2030 and 2035, when many major countries put the brakes on the production of internal combustion vehicles. KUKA recognized the potential of e-mobility early on. In 2014, the Augsburg automation specialist began optimizing its product portfolio for the specific requirements involved in production of electronic components for the automotive industry. Now, Liebherr-Verzahntechnik GmbH in Kempten also benefits from this optimization – and has developed a robot-powered application that offers greater safety and higher productivity for manufacturers of electric vehicles and their suppliers.

Today, most process steps in the production of batteries are already executed fully automatically to meet the automotive industry's requirements for cycle times, batch sizes, quality and production costs. The shortage of skilled workers also drives this strong trend toward automation. Increasingly, fewer skilled workers will take on such monotonous, physically strenuous and demanding tasks. KOSTAL Kontakt Systeme GmbH (Lüdenscheid), which has produced and sold plug-in connections for the vehicle industry since 1938, identified a gap in the market. It developed a connector that plugs in either manually or through automation. Martin Wolter, Group Leader for Development at KOSTAL, reported that “Safety plays a very important role here. Because these are high-voltage contacts, they must be protected against contact just as the contacts in an electric socket are protected from fingers. The difference is that the plug-in connection in the vehicle is subject to vibration stress and temperature extremes.”

Machine handling of non-rigid parts remains a major challenge in assembly. For example, elastic cables that can bend in any direction are difficult for robots to grip. Based on the KR CYBERTECH nano ARC HW Liebherr has developed a special gripper that removes the cables from a package. The cable is not pre-positioned accurately in the package, so a 2D camera helps determine the right gripping positions on the cable and position the module connector at the end of the cable exactly above the mating connector.

The plug must be handled carefully, so the plug-in process has been separated for a smooth sequence. A spring assembly controls the force transmitted to the connector and the Connector Position Assurance, or CPA. A pneumatic cylinder then presses the connector into the mating connector. This spring assembly compresses until it reaches a torque of 70 Newton meters, which triggers the end position sensor. At the same time, the spring-mounted locking pin presses the CPA downwards. Thus, the CPA locks, the connector plugs in correctly and the gripper can move back up again. In contrast to other automation experts, Liebherr deliberately avoids trial-and-error processes as a solution for the plug-in process of non-rigid cables. Every move must be just right for the technology to meet the cycle-time requirements of series production. The system has more than succeeded: It cut the allotted cycle time of 17 seconds by six seconds.