Research On Several Key Technologies Of Reverse Engineering Based On CMM

Reverse engineering , one branch of advanced manufacturing technologies, is always the hot issue in the years. In home electrical appliance, car and astronavigation, it has been used broadly. Reverse engineering is a design according to the prototype. When there is no blueprint but the prototype, we can obtain the three-dimensional data of the prototype, making use of the equipment which can measure the prototype. And then, the geometric model can be generated through the software of tri-dimensional reconstruction. At last, the NC program, based on the geometric model, was used to control the NC machine to process the prototype.In this paper, the problem in reverse engineering with the CMM, such as, acquisition of tri-dimensional data, data conversion among the systems, data splice from different views and system error, are analyzed, based on the complete summary of the existing condition and open questions within the domestic and international scope.To analyze the difference between the reverse engineering and the traditional design methodology, the key technologies of reverse engineering and its present state in domestic and international range.To analyze the ways of tri-dimensional data acquisition and the software and hardware composition of the CMM-LK G90CS; discuss the factors mat affect the accuracy of CMM and put forward the measure of canceling interference; advance the means of measure planning which are applicable to different prototype; taking a mouse's measure process as an example, the preparation before measure, choice of the probe and its correction, coordinate definition, measure boundary definition, path division of measure and data output are discussed.To work out data interface on the basis of analyzing kinds of data format of CMM and the format of IGES, realize the conversion from the format of CMM to the format of IGES ,and then the data are put in different layers according to its color.To solve the problem of multiple bearing in measure. Making use of the rigidity transformation matrix, the data of different coordinate systems can be spliced into the first coordinate in response to the 3 points localization principle. According to the naming rule of the files, the optimum splice path is haunted and the data's multi-views splice is completed automatically.To respectively analyze the error in different parts of reverse engineering and put forward handling strategy to corresponding error and the critical technique.