Control of the Machining Precision in Thread Cutting

Abstract

In research on thread cutting, the flaws inevitably arising in the first two and last two turns of the thread, when the process is unsteady, are analyzed. Specifically, insertion and removal of the tool from the workpiece are accompanied by abrupt change in thread diameter: abrupt decrease in the case of threads on shafts; and increase for threads in holes. That leads to the appearance of slots on assembly, thereby increasing the likelihood of accidents and other problems in thread operation. A method of eliminating such gaps is proposed and tested: control of the machining precision in the course of thread cutting. In particular, the thread diameter and pitch are controlled by compensation of the axial and radial elastic displacements of the tool, based on timely correction of the transverse and longitudinal supply during the unsteady stage of the process. Compensation of the machining errors improves the dimensional precision of the thread and decreases the systematic errors and spread in the thread dimensions.