Prediction and experimental verification of the cutting forces in gear form milling

Abstract

In this paper, a mathematical model is presented by which the cutting forces in gear form milling process are predicted using the mechanistic approach. To use this approach, a detailed description of the chip geometry is needed. Eccentricity and run-out tool errors are considered, which is of great importance as the chip thickness will by these errors vary for the subsequent cuts. The chip geometry is determined by comparing the path of the cutting edge with already removed material. The boundary of the chips is determinable from the cutting edge geometry, which is here derived in parametric form so spur and helical gears are manufactured correctly. Locally on the cutting edge, the cutting forces are resolved from orthogonal cutting data and on the basis that these forces are proportional to the instantaneous chip thickness. The load each individual cutting tooth experience in operation, as well as the complete load on the tool, are resolved by summing the forces along the cutting edge. In the model, all cut chips are determined for each machined gear tooth gap, with the gear blank boundaries considered. The paper ends with experimental validation using indexable insert milling cutters. It is shown that the model predicts the force shape well and the peak force levels within 12 %.