Development Of A Numerical Control Lathe And Research On Processing Error Compensation Caused By Feeding System Stiffness

The ball screw is the main part of the feeding system in a numerical control lathe.The structure characteristics and installation forms of the ball screw are determiningfactors in the low stiffness of feeding system, which can affect the lathe accuracy to acertain extent. For lacking position detection device such as a linear encoder, the causedby the feeding system stiffness is clearer in a half closed loop lathe. Research into themechanism how the feeding system stiffness cause a processing error has an importantsignificance for improving the processing accuracy of the numerical lathe with halfclosed loop control system. In this paper, a multi-function numerical control lathe isindependently built as the study platform. According to the inner sphere processing, amechanics model taking the affection of stiffness into consideration is built. Theinfluence caused by the stiffness is simulated and analyzed At last, a compensation planis put forward and the theory is verified by an experiment.According to the experiment need, the mechanical strucure of the lathe is designeddetailedly. Both the industrial PC and traditional numerical control system are necessaryconfiguration for the control system. As the key components configuration and wiringintroduced, a control cabinet is designed which is convenient for the two system tochange. The debugging and assembly of the whole machine is finished. Feeding systemmathematical models considering the affection of stiffness are bulit.The inner sphereprocessing is analyzed from the process route and process parameters. The stress anddeformation models of the feeding system under the action of cutting force are built.Though simulation for the mathematical models above, related laws about how theprocess parameters work on the stress of the feeding system and how the blankmaterials and bus bar shape work on the feeding system deformation are got, which is abase for the automatic processing program and experimental work. Finally a processingmethod named subsection arc interpolation and certain-point error compensation isoffered. The inner sphere automatic processing program, including a finishingprocessing program with compensation, is written. The processing experiment isfinished on the lathe. With measurement of the two inner sphere surface,one processedin an ordinary way and the other processed in error-compensation way,it is clear that thefeeding system stiffness has an influence on the inner sphere surface and the processingaccuracy can be improved by the compensation to a certain extent.