Nabtesco Corporation Industrial Equipment Case Study

• Analytics & Modeling - Digital Twin / Simulation

• Renewable Energy
• Equipment & Machinery

• Product Research & Development
• Discrete Manufacturing

• Predictive Maintenance
• Digital Twin

• Software Design & Engineering Services

Nabtesco Corporation, a Japanese company known for its unique technology in robotic reduction gears, faced a challenge when expanding into energy harvesting equipment such as wind turbines and solar energy collector trackers. The company needed to ensure sufficient gear strength and long-term endurance in gusty conditions for their wind turbines. The yaw and pitch drives in a wind turbine engage with a pinion gear, which transmits power from the drive to the nacelle or blade. The rotation angle between drive and pinion gear teeth is particularly small, so repeated contact over time, particularly under the stresses of high winds and tower vibration, has the potential to damage tooth surfaces and cause assembly breakdowns. The engineers at Nabtesco needed to balance the contact between ring and pinion teeth to reduce the 'normal' stress of rotation and the sheer stress of the teeth against each other. Decreasing the stress on teeth improves their durability and that of the entire assembly as well.

Nabtesco Corporation is a Japanese company known worldwide for its unique technology that allows robotic reduction gears to be smaller and lighter than many conventional robotic drives. The company specializes in precision yaw and pitch drives for robotic reduction gears. However, when the company expanded into energy harvesting equipment, such as wind turbines and solar energy collector trackers, they realized that 'smaller and lighter' have their limits in large industrial structures. Particularly in the wind industry, their biggest challenges are ensuring sufficient gear strength and long-term endurance in gusty conditions. Their reduction gears are made up of a lot of very complicated assemblies, with many parts that come in contact with one another. For each wind turbine configuration, they have to provide their customers with the best possible design that minimizes overall stress while maintaining durability.

The engineers at Nabtesco used Abaqus finite element analysis (FEA) software to calculate the contact area and stress of various pinion gear designs. With the help of their own subroutine, the engineers were able to model both contact area and stress history for easier design evaluation. Isight was also utilized for post-processing automation and design optimization. The engineers started from a global Abaqus/CAE model based on imported CAD geometries of rig, drive, and pinion. The bottom surface of the test apparatus was modeled as fixed. Resistance was applied to the reduction gear shaft, and the pinion was rotated at a prescribed angle. This allowed the team to see when and where the opposing teeth engaged as the gears rotated, and what the resulting stresses were. For a deeper understanding of what happens when the teeth interact, the engineers created a sub model that contained only those areas of acute interest. When compared against the painted gear rig tests, the FEA results showed good agreement.

• Abaqus allowed the Nabtesco engineers to maximize gear contact area, while minimizing average stress contact. This resulted in a significantly more durable gear design that led to decreased maintenance and cost without requiring numerous physical experiments.
• With Isight, the design time was reduced drastically.
• The engineers were able to model both contact area and stress history for easier design evaluation.

• Significant improvement in durability of the gears.
• Dramatic reduction in design times.