Investigation of the diameter error when turning thin walled workpieces

摘要

Every manufacturing process undergoes geometrical deviations from the defined geometry. In order to produce workpieces within the specified quality, a downstream quality assurance is carried out. This quality assurance is expensive and time consuming. If the geometrical error could be estimated during and after the manufacturing process this quality assurance can be reduced. The geometrical error emerges due to different causes. One of these causes is the deflection of tool and workpiece. This alters the depth of cut and therefore causes a radial error on the machined workpiece. An additional cause is the progressing tool wear during continuous machining, also influencing the depth of cut.This paper presents a method to determine the radial error after turning. The method is based on finite difference calculations, suitable for the investigation of the local error of multi-diameter workpieces. Within the developed model the deflection due to shearing and bending of the workpiece and the tool are examined. Furthermore, the tool wear is considered. Additionally, the calculation for a locally varying depth of cut is presented. The results show that by taking the tool wear into account the model error was decreased from 63.08 % to an absolute error of 5.72 %. Using the proposed model, it is possible to generate relevant data about the geometrical manufacturing error immediately after every machining process.