Multi-degree of freedom machining

This paper introduces a mechatronic system for improving surface waviness quality of machined timber products. The work presented examines the simulation of a piezo-electric actuator rolling element bearing spindle system. This system supports a rotating cutterhead in which two cutters are located for machining timber. The simulation model is based on classical second order vibration equations with the piezo-actuator modelled as a pusher of infinite stiffness serially linked to the spindle bearing housing via a spring of equal stiffness to the piezo-stack. Simulation results show that commercially available piezo-ceramic stacks can be used to generate 8 μm radial cutterhead displacements over a time period of 200 μsec. This allows the knife path loci through the timber to be modified and hence change the form of the surface wave from a circular arc to a trough, producing a corresponding reduction in wave height and an improvement in surface smoothness. Newly developed surface simulation software for analysing the effect of knife path loci modification is used to show a 57% improvement in surface waviness for low cutting speed conditions.