Research On Whole-close-loop Control System Of Numerical Control Turning Machine

With the development of industry, the traditional machine tools can hardly respond to the request of modern production. Fortunately, because of their special characteristics, computer numerical control (CNC) machine tools can suit these requirements. The dissertation analyses foreign and domestic CNC research and production and the current, then to dissolve the remonstration of the numeric machine tool, introduce the search important and necessary.The dissertation introduces the present status and application development of NC machine tools, combining on-line detetion technology with NC technology to design whole-close-loop economical NC turning machine system: Based on modern detection technology, applying CCD sensor to detect the shaft diameter on-line, then feed back the shaft diameter, continue the nest turning when the diameter is less than the theoretical value. The detection technology makes detection device, turning machine, cutter and workpiece into one whole-close-loop system. Adjust the feed of cutter baded on the detection diameter, thereby realize whole-close-loop system. The segment of close loop extend to workpiece can contain abrasion of cutter, thus can improve machine accuracy. The author set up mathematic model based on control theory, and analyse the dynamic and steady-state proformance of system. The research and analyse of system provide theoretical base for exploitation of high accuracy NC machines.Then research and design the detection and feedback device, analyse the present status and application development in home and overseas, discuss the merits and faults of contact and non-contact measurement, elect the suitable detection means. Discuss the vested detection means of shaft diameter, detection theory and key technology in the detection of shaft diameter, point out the improvement accuracy futher of shaft diameter on research method and means. Alone with the development of the technology, in particular the development of the latter-day's electronics, the measuring technique of geometrical sense demand high precision, high efficiency, automatization, dynamic detection, adaptive control, etc. The measuring system with CCD has an advantage on the geometrical sense meterage, such as high precision, high efficiency, automatization, noncontact, etc. It adapts to measure minisize especially.In the end, introduce the image processing and several edge detection operator, do image pre-process from CCD and edge detection, then extract the dimension of shaft diameter, feed back the diameter real-time, format whole-close-loop control system include workpiece. The edge detection is important in image processing. This thesis puts forward a new sub-pixel measuring method, which confirms the approximate position of edge by conventional template arithmetic, and then gets the precise position of edge by least squares fit theory. This method can obtain sub-pixelloc and acing precision without the sacrifice of the needed speed by the coarse precise location.The reseach of NC technology is later in our country, economical NC turning machine is in big proportion. The research and design of the device will initiate profound influence and important significance for retrofit of economical NC turning machine, at the same time, have better push effect and enlightenment effect for development of NC machine tools.