Research On Rapid Reverse Engineering Technology Based On Industrial CT

With the development of advanced manufacture technology, reverse engineering is becoming more and more emphasized and the demand to reverse engineering is higher and higher. Three dimensions measurement is the key of reverse engineering. Nowadays, through common means of measurement, the interior surfaces of close parts can't be caught without destruction but only the exterior surfaces. In order to solve the problem, industrial computed tomography (ICT) system is introduced into reverse engineering. The system has the ability to rapidly and non-destructively produce images of both exterior and interior surfaces and regions. Because ICT images are densitometrically accurate, complete morphological and part characterization information can be obtained without need of physical sectioning. ICT data can be processed to create computer-aided design (CAD) representations of the part, to extract dimensional measurement, or to detect, size and locate defects. The rapid reverse engineering system based on industrial CT benefits to shorten the period of product design and production, decrease the production cost and accelerate the speed which our country catches up with and even goes beyond other developed industrial states. Some key technologies related to the system are studied at length in this paper. In fact, the process of scan by industrial CT is just a reverse process of rapid prototype manufacture (RPM). The data driving the RP are layer contour data. Meanwhile, the data measured by industrial tomography are the same. So the layer contour data measured by industrial CT can drive the RP machine directly after disposed to complete manufacture. Therefore, how to make the industrial CT data drive the RP machine directly has been studied in this paper. This means have the advantages of high precision, fast speed and small quantity of data. In addition, the process of perplexing data conversion is eliminated without disadvantages of STL format. The most importance of this means is to reduce error leaded by conversion. Based on the image data of industrial computed tomography, in order to increase quality of the image, firstly, noise in the gray image should be eliminated by noise filters and by sharpening. Secondly, the image is processed with binary, which can make the later operation of image processing more easily. The optimal threshold of image binary can be obtained through iterative arithmetic. According to compare with some methods of contour detection, an easy morphological method is taken aimed at the industrial CT image. That is erosion image is subtracted by original image, then the result is the contour image and realize the contour detection. An improved arithmetic of contour tracing is brought forward based on the contour detection mentioned above. Considering the system of reverse engineering needed only character points of contour, redundant points are eliminated when 8-oriean-tracing. So the final quantity of data is greatly reduced. It can speed up the reverse process and increase accuracy of reverse engineering.