Research On The Three-dimensional Reconstruction Of Small Size Cavity Of Mold

With a global market increasingly competitive, each company is developing their own technology, but also focusing on the introduction of technologies from other countries. Reverse engineering technology provides a good method for learning and absorbing the imported technology. Particularly in the mold industry, reverse engineering technology is widely used. Product designers can get the CAD model from end products by reverse engineering technology, and then modify it for innovation, and finally manufacture new product through the CNC machine tools.Nowadays there are many ways to measure the three-dimensional data of mold, but it's hard to find a method which is economical and fast for the measurement of small size cavity. In order to solve this problem, this paper proposes a novel method which is based on liquid tomography. This method has the advantages of low cost and high efficiency. This paper will research and prove its feasibility in industrial applications form three areas: Data Acquisition, Image Processing, 3D Reconstruction.After analyzing existing data acquisition methods, the paper give a new method to obtain three-dimensional point cloud data of small size cavity, and select CCD camera combined with digital image acquisition card. Then introduce the basic principle of the method and the whole hardware framework of this system.In order to deal with the image acquired, image processing system calls the function of the open-source computer vision library OpenCV. After studying the image, we select the appropriate algorithm for image grayscale, image denoising, image segmentation and contour extraction. The contour of small size cavity in different level will be acquired at last. Preparing for the three-dimensional reconstruction, theory of spline curves and surfaces has been studied. This paper uses the computer-aided design software CATIA which is developed by French company Dassault System to deal with the collected point cloud data, and introduces detailed steps of surface fitting.Finally, by experiment and analysis of error, the paper prove that the reconstructed three-dimensional model by using this method can satisfy industrial requirements.