Flexible XXL flow production

TASK

Transporting loads weighing up to 350 tons with mobile robots

Every workday, a Siemens Gamesa 8 MW offshore wind turbine nacelle weighing tons leaves the plant in Cuxhaven, Germany. Four heavy-duty mobile robots from Stäubli support internal transport from station to station in ultra-modern flow production.

In the production of offshore wind turbines, different dimensions than in “normal” production facilities apply. In the 8 MW class WTGs that Siemens Gamesa builds for offshore wind farms, the rotor blades are over 81 meters long and the nacelles weigh around 350 tons. The nacelles are built at the Cuxhaven plant, which was newly constructed in 2018 for this very purpose.

More than 250 nacelles are produced per year and loaded directly onto specially built ships. This means that each workday, the approximately 600 employees build a complete wind turbine nacelle. This is a XXL flow production.

SOLUTION

Four heavy-duty mobile robots with up to 450 tons of load capacity

The three main components—hub, nacelle and generator—are initially developed on three parallel production lines and finally assembled into the complete nacelle.

Assembly takes place at individual stations and the components, weighing many tons, are located on frames that allow them to be transported from station to station. This is done by cranes and mobile robotics solution from Stäubli. The mobile robots drive under the frames, lift them and move them to the next assembly station. Three heavy-duty mobile robot platform with 200-ton load capacities do the work. RFID tags mounted in the floor enable semi-automatic operation.

A fourth heavy-duty mobile robot takes over the final process step of transporting the finished nacelles to the test stand. At 450 metric tons, its load capacity is more than double, and with platform dimensions of 10.5 x 3.02 meters, it is also significantly larger. Here, 16 drive units provide mobility.

With loads of more than 500 tons, several vehicles can travel in coupled operation mode. And soon this will take place in Cuxhaven, as the plant will be commissioning a fifth heavy-duty mobile robot from Stäubli. Preparations are underway for production of the next generation of offshore wind turbines with a capacity of 11 MW. To do this, rotor diameters will be 200 meters, and nacelles will weigh a third more.

The nacelles of the new wind turbines will travel on the two 450-ton capacity vehicles in coupled operation from final assembly to the test stand.

CUSTOMER USAGE

A highly flexible material flow concept

The fact that Stäubli is technologically capable of synchronous operation of vehicles of this size is a major advantage. This allows the plant to use the vehicles individually or coupled with maximum flexibility.

Across the board, the principle of transport by crane and mobile robots has proven itself. Thus, the production change from 7 to 8 MW offshore wind turbines was accomplished with comparatively little effort. The mobile robots only had to be reprogrammed.

The company is also completely satisfied with the vehicles from Stäubli in day-to-day operation. The mobile robots work reliably and with high precision.