AbstractThis thesis details research relating to the design, manufacture and testing of a novel device that can be retrofitted to CNC machining centres to provide a flow of a cryogenic coolant – in this case liquid nitrogen to the cutting zone. A literature survey was undertaken in two parts, the first to review the advantages of using cryogenic coolants and the second to investigate the current state-of-the-art in both academia and industry. A gap was identified for a solution that could be retrofitted onto existing machine tools, avoiding the need for expensive modifications and allowing existing machine tools and tooling to be used. By following an adapted design methodology, requirements were generated into a product design specifications (PDS) and suitable concepts were generated. Through weighted methods it was decided upon an arrangement that used a rotational union as a coupling to guide liquid nitrogen into a shank for through tool cooling. A cryogenic coolant inducer was designed and manufactured. Labyrinth seals were developed to create a rotational union between the rotating central tool shank and the incoming vacuum line of liquid nitrogen. The initial design was tested on a Bridgeport CNC machining centre. It was found in the first instance that the sealing arrangement was unsatisfactory leading to large leaks that increased proportionally with spindle rotational speed. Through an iterative design and testing process the design of the labyrinth seals was refined to work at higher spindle speeds. An axial impeller was also developed to pump the liquid nitrogen inwards and down towards the cutting tool. The final iteration was used to machine a titanium (Ti-6AL-4V) workpiece. The results were analysed to inform future improvements.
|Date of Award||13 Mar 2018|
|Supervisor||Alborz Shokrani Chaharsooghi (Supervisor) & Vimal Dhokia (Supervisor)|
Design of a Cryogenic Coolant Inducer
Whitton, D. (Author). 13 Mar 2018
Student thesis: Doctoral Thesis › MPhil