Geometrical Error Identification and Compensation for Grinding Machine by Crankshaft Roundness Measuring

Abstract

Tangential point tracing grinding method has many advantages in the precise machining for eccentric parts such as crankshaft pin grinding. But its machining accuracy is based on a very precise geometrical model, which means the geometrical error of the machine tool can induce big outline error. By analysing the motion model of the tangential point tracing grinding, the roundness influence functions are established which respectively indicates the roundness errors caused by grinding-wheel centre height error, grinding-wheel radius error and grinding-wheel feeding error. Then the influence of them on crankpin roundness error are simulated. Now that the geometrical errors of the machining tool are quite difficult to measure, an innovative geometrical error identification and correction methodology is put forward, which identifies the geometrical errors by measuring the roundness of a grinding sample, then corrects the geometrical errors by NC compensating. Moreover, the correction methodology is practically applied in the crankshaft pin grinding in laboratory. The validity and feasibility of the presented geometrical correction methodology is proved by theoretical calculations and off-line roundness measurements. It is indicated that the proposed geometrical error identification and correction methodology emerges good prospect in precise grinding machines.