Intelligent components to boost machine tool productivity
Over the years, machine tools have evolved into complex systems of sensors and actuators for better dynamic control of cutting. However, the control mechanisms are often too far from the actual cutting location to adequately prevent self-excited vibrations. EU-funded scientists developed intelligent technologies to be placed very close to the machining point for better dynamic control. Intensive research on the DYNXPERTS (Plug and produce components for optimum dynamic performance manufacturing systems) project led to six new plug-and-produce components for demanding machine tool applications, the submission of four patents and a commercially available product. Enhancing dynamic control of the spindle head that holds the cutting tool in milling operations and the work piece for operations involving a lathe was a challenge. Two different active spindle heads were developed and tested, one exploiting inertial signals and one using magnetic bearings. By using this new spindle head exploiting inertial signals, dynamic stiffness was increased by 150 %, while the material removal rate was quadrupled. Regarding the other spindle head, the damping ratio increased by more than 40 %, whereas the material removal rate increased by 8 times. Smart fixturing devices to enhance damping capabilities consisted of three different active damping devices (exploiting magnetorheological fluids, magnetorheological elastomers and eddy currents) and two active clamping ones. The capability of these devices to adapt to the dynamics of different large and flexible work pieces was improved by more than 600 %. The team also produced two different dynamic calibrators with demonstrated potential to enhance machining performance through automatic measurement of machine tool dynamic behaviour. These devices generate the stability charts and provide automatically the best process parameters to guarantee optimal machining and chatter-free cutting conditions. The material removal rate was increased more than 3 times, and surface roughness decreased by over 50 %. To top it all, a generator assembly inside a spindle was used to harvest spindle vibration and provide energy to a wireless communication system that is capable of condition monitoring at a distance of up to 10 m. Project developments help stimulate innovation in the machine tool sector, paving the way for major market uptake and offering a welcome boost to the EU economy.
Keywords
Machine tool, productivity, manufacturing, plug-and-produce, dynamic control, DYNXPERTS
