Patterns of form error inheritance during machining

Abstract

The paper studies modeling of quality parameters formation during machining on metal cutting machines. It was demonstrated that operational properties of parts are created not only at finishing operations, but rather formed throughout the entire technological process. At the same time, some characteristics and properties are inherited from operation to operation, i. e. copying of workpiece form errors to the machined part in the form of the same errors. The nonlinearity of the workpiece corresponds to the nonlinearity of the part. The extent of operational copying of nonlinearity (shaft surface runout in the middle section) was studied. A mathematical model of such error inheritance was developed with consideration of the nonlinear approximation of depth of cut variation along the workpiece circumference (per one revolution of the part). For existing tool materials, the exponent x at the cutting depth in the formula of the cutting force P is in the range of 0.7-0.9. As the depth of cut decreases, the refinement coefficient decreases. Therefore, when switching from rough operations (large cutting depths) to finishing (small cutting depths), the refinement coefficient becomes smaller. © Published under licence by IOP Publishing Ltd.