Computerised grinding procedure for large scale crankshaft machining

Abstract

The paper describes sequence of machining operations that leads to the desired quality of the produced crankshaft, as well as in-situ inspection, correction and compensation procedures performed and controlled by computer. The form deviation values after correction are being compared with those obtained before. In case of crank pins, values of form deviations, and hence those of corrections, are much larger than for main journals. During the measurement, the probe collects data from 3600 points per revolution, and then averaging procedure reduces data down to 360 points. There are several algorithms for data processing available, so the operator may choose the one most appropriate. Substantial difference between out-of-roundness values of main journals and crank pivot was registered. Before form compensation, the former was between 0.01 and 0.02 mm, while the latter were in range 0.07-0.09 mm. Program of grinding is parametric, i.e. at each stage of the process all values responsible for the tool movement undergo correction. The applied computer monitoring enabled to achieve the demanded quality of grinded surface, as well as dimensions and form deviations in the tolerances set by the product specifications. Form compensation procedure enabled to reduce peak-to-peak deviation from 30.37 μm down to 8.14 μm.