Radial angular orientation method and its error analysis for crankpin non-circular grinding

Abstract

In non-circular grinding, the motion model built in workpiece coordinate is used to control the rotation of workpiece and the transverse feed of grinding carriage to make the crankpin curve tangent with grinding wheel. It is essential to transform machine tool coordinate to workpiece coordinate accurately for the uniform distribution of grinding allowance to obtain the high machining precision of each crankpin's profile and phase angle. To find the optimal offset between the two coordinates, the on-line measurement device grounded on touch trigger probe with large measurement range is designed. Two radial angular orientation models are built respectively for two-point and multi-point measurement methods. Convergence speed, accuracy, as well as the initial selection of spectral scaling BFGS method is analyzed in solving this optimization problem. The effects on radial angular orientation accuracy of probe pre-travel and positioning error and its relationship to the measurement position are studied by simulation. The validity of two radial angular orientation methods are compared and verified by the experimental results. And the corresponding measures is put forward to improve the radial angular orientation accuracy. © 2014 Journal of Mechanical Engineering.