Study On The Key Technology For Image On-Machine Measurement

Computer numerical control (CNC) milling machine, which is the core equipment in the advanced manufacturing process, has a large number of tasks to be inspected, including clamp and part fixed, alignment, NC programming origin measuring, first part inspection, inspection between the process sequences, finished part inspection, and so on. Therefore, carrying out the study of the on-machine measurement technology of CNC milling machines plays an important part in both the academic and practical application. This technology will be the important link to realize seamless connection between measurement and manufacture, and has been widespread concern at home and abroad.Image on-machine measurement technology is considered as moving image measuring instrument to CNC milling machines, and takes the advantages of image measurement to realize the non-contact, high accuracy and high efficiency geometric on-machine measurement, which makes up the shortage of the touch trigger probe. This study aims to pre-preview for establishing an image on-machine measurement system of CNC milling machines based on image probe. The key technologies of image on-machine measurement, including the building and accurate adjustment of the hardware system, the three-dimensional image measurement based on image focusing method, the computer-aided inspection planning, the full-screen target guidance based on image or CAD model, the image edge detection and the geometric measurement, are studied in depth based on the developed image on-machine measurement experimental system.1. An experimental system for image measurement is designed and developed, which is used to carry out the key research. The developed system mainly includes:three-dimensional stage, image probe, microscopic vision measurement software.2. The three-dimensional image measurement is studied based on the image focusing method of auto-focusing technology. Focusing search strategy on the basis of unequal step length is proposed. The relationship of measurement accuracy and surface roughness of the workpiece is discussed in accordance with the experimental results. In addition, the error separation technology is used for improving the accuracy of the height measurement.3. A computer-aided inspection planning (CAIP) system for image measurement is developed in accordance with the image on-machine measurement system. The function modules of the developed system are composed of the inspection information extraction, the sampling strategy, the inspection path planning, the inspection codes generation and the inspection procedure verification.4. Since the field of view of the image probe is limited and the full view of the measured object can not be observed, the full-screen target tracking function based on the mouse-click is developed. The function is mainly divided into the image method and the CAD model method, and can realize that what you see is what you get.5. The image edge detection method based on the mathematical morphology (MM) and the radial basis function (RDF) for the microscope image of the workpiece is studied, and the geometric method for image measurement is also investigated.