Prediction of the insensitivity zone in the design of the feed drive CNC lathe

The processing on CNC machines of parts of a complex profile with multipass shaping schemes is accompanied by multiple changes in the direction of movement of the working bodies (reverse) during the cutting process and at idle running. When reverse, loss of information is possible due to the presence of gaps in the chain of feed drive and elastic deformations determined by constant loads overcome by the drive. Permanent loads consist of cutting forces and friction in the feed drive chain. Information loss is defined as a position insensitive zone at a position. To determine the insensitive zone, a technique is proposed that takes into account the differential accounting of friction losses in the mechanical feed drive chain. To estimate the elastic deformations in the drive chain, design schemes are proposed and analytical dependencies obtained. Differentiated consideration of friction in determining the insensitive zone allows you to outline the main ways to improve feed drives. It is shown that the magnitude of the preload on the thrust bearings and the tensile forces of the lead screw during assembly do not have a significant effect on the size of the insensitive zone. Even less impact on the dead zone has a preload change in the transfer screw-nut rolling. It was determined that the main ways to reduce the insensitivity zone is to increase the rigidity of the screw-and-nut rolling transmission anchor to the machine carriage and reduce friction in the guides. In addition, an analysis of the layout decisions of the lead screw assembly (one-sided and two-sided termination) according to the insensitive zone criterion showed that the use of one-sided termination of the lead screw is more rational.