Smart tool system optimises machining procedures for plane engine shafts
One of the main changes to engine configuration and operation involves incorporating a gearbox to decouple jet engine fan and turbine rotation, and also minimising the main shaft diameter. Doing so will lead to new requirements for turbines with higher rotational speeds and higher torque density. As a result, new requirements will be created concerning the size and shape of the main turbine shaft itself. This will pose new challenges for existing manufacturing technologies, especially for the internal geometry of the bottle-shaped shaft in the case of shafts characterised by high length-diameter ratios. “We developed a high-performance, novel, intelligent tool system to machine future engine shafts with the required precision and quality,” comments Oscar Gonzalo, coordinator of the EU-funded BBT project.
Delicately balancing tool performance and complexity
To enable the manufacturing of bottle bore shafts, project partners developed a boring bar and related motion, sensor and control subsystems. They selected suitable technologies for the subsystems and for the design of the boring bar solution. The BBT team integrated all these different subsystems into the boring bar before testing the tool concept. “This was a challenge because of the large number of subsystems to be integrated into the tool concept design and the reduced space available,” explains Gonzalo. Patents are being prepared to commercially exploit the boring bar and its key subsystems. The boring bar machines hollow bottle-shaped shafts on jet engines to control the manufacturing process better and improve the end quality of components. The development process applied to the tool features several subsystems that allow shaft machining to be performed properly and incorporates electromechanical drives for motion. It has also been equipped with smart components fitted with sensors that can be used to monitor vibration, surface finish and the shape of machining chips. “Integrating these systems will make it possible to increase manufacturing capabilities and optimise processes,” notes Gonzalo. “They will also help to develop Industry 4.0 technologies.”
Future engines that are clean, green and efficient
The aeronautics sector is facing the challenge of delivering smart, ecological and integrated transport, as laid down by the EU’s Horizon 2020 Research and Innovation programme. The industry is also tasked with reducing CO2, gas emissions and noise levels as part of Europe’s vision for aviation and the Clean Sky 2 Joint Undertaking that co-funded BBT. “Ultimately, BBT will reduce the environmental impact of air transport and manufacturing methods by using next-gen engines,” concludes Gonzalo. The smart boring bar will allow the manufacturing of turbine shafts with the required specifications for tomorrow’s aircraft engines, thus contributing to the improvement of process efficiency. “End users will achieve higher performance in their manufacturing procedures, resulting in increased efficiency, reduced lead time and cost savings.”
Keywords
BBT, shaft, engine, boring bar, engine shaft, turbine shaft, bottle bore shaft
