A novel tool for pneumatic spindle design

Best Paper at the Conference. Pneumatic spindles have been introduced in a wide range of industrial applications. In fact, air motors offer a cost effective alternative to conventional electric devices and often remarkable functional improvements. In spite of their growing diffusion, air motor design is still performed mainly according to companies’ expertise, usually building a number of prototypes until the desired torque/speed (or power/speed) curve is obtained. The aim of this work is to provide a predictive model capable of estimating the characteristic curves by setting a set of air motor geometrical characteristics and inlet air pressure, in order to reduce the number of prototypes to be built. The presented study has been carried out with reference to vane motor, generally suitable for applications requiring high operating speeds. A statistical experimental approach (based on DoE technique) has been used in order to derive a mathematical-empirical model relating the geometrical and fluid-dynamic parameters with the system "response". The geometric parameters, defining the shape of the spindle, have been successively used to create a parametric CAD model with the corresponding technical drawings. The developed methodology, tested on a series of prototypes, proved to be effective in forecasting the characteristic curves of vane type air motor; moreover, due to the extremely low computational cost, it allows to assess a large number of design alternatives and to select the one best fitting the design target.