Effects of kinematic parameters on electric discharge truing of small ball-end diamond wheels for small concave surfaces grinding

To meet the strict requirements for processing quality, the metal-bonded small ball-end diamond wheel (SBDW) has become a promising choice to process the hard and brittle materials with small concave surface. Unlike conventional diamond wheels, the profile accuracy of SBDW would so greatly affect the form accuracy of ground small concave surfaces that a truing system must be adopted to insure the accuracy of SBDW. Hence, the effects of kinematic parameters of the truing system on the on-machine electric discharge truing (EDT) of SBDW are investigated. The effects of the errors from kinematics, electrode geometry and relative position on truing are analyzed by establishing the mathematical model through screw theory. In the experiments, the effects of spindle speeds of SBDW and tool electrode on truing are investigated and the complex component with small concave surfaces is ground by the optimally trued SBDW. The results indicate that there are more factors affecting the dimension accuracy than profile accuracy of the trued SBDW. Each factor affects dimension accuracy equally, while the radial run-out error of grinding wheel spindle influences profile accuracy more significantly than others. The spindle speed of SBDW affects the profile accuracy more remarkably than that of tool electrode, and the relative speed between them affects the truing efficiency and surface quality of SBDW. The final profile error (PV) and surface roughness (Ra) of the practically ground component are 0.328 μm and 50.2 nm, respectively.