NC Machining And Measurement Of Stone Art Products Based On Reverse Engineering

With the rapid development of architectural decoration industry and improvement of NC machining technology in China recent years, there is a growing demand for exquisite stone ornaments, which upgrades the digital design and machining techniques for stone products. Stone art products which weakening its dimensional precision in design and manufacture, and strengthening its aesthetic quality relatively, belongs to those products with complicated surface and a wide tolerance; most stone art products contain a large number of complicated free-form surface whose curvature change drastically, and its manufacturing materials belong to hard brittle materials, so there are certain difficulties in whatever digital design, processing or measurement, etc. In this paper, according to the characteristics of stone art products, reverse engineering technology was applied to three-dimensional stone art products in the design, manufacture and measurement, aimed at solving the CAD/CAM/CAI problems of traditional stone art products.Using reverse engineering technology, design difficulties have been solved, such as difficulties of digital design, high labor intensity for design staff, slow speed problem of the traditional stone art products. The preprocessing technology of reverse engineering was introduced, such as the noise removal, data reduction, multi-view cloud data alignment. The digital measurement techniques were studied. Data acquisition process and strategies for stone art products were introduced through the actual cases, the causes of error generation in the data collection process were analyzed. Surface reconstruction of the physical model for stone material artware has been realized, the reconstructing model quality was evaluated, and the error sources were analyzed using Geomagic Studio software.From digital measurement, 3D model creation to tool path generation and to virtual machining, the integration process were demonstrated by one case. In accordance with the hard brittle properties and features of the stone material art products, and the characteristics of the processing equipment, the machining methods of multi-axis milling for three-dimensional stone products based on HTM50200 special-shaped stone turning&milling machining center were studied. CAD/CAM thinking of mechanical processing was used in stone machining in this paper. The rough and finish machining strategies which suitable for solid stone material craft products based on CAM software were summarized by the simulation analysis of residual material model and tool paths as well as the processing efficiency comparison. The roughing, semi-finishing and finish machining tool paths were compiled using UG software, and the NC codes were simulated using VERICUT software to verify the correctness of the programs, on the basis of NC machining process analysis of the special-shaped stone crafts.The process of digitization comparison measurement based on reverse engineering was studied; the relevant theories of the coarse registration, fine registration, and deviation calculation between the point cloud data and CAD model were researched in this paper. Respectively selected the marbles relief machined through 3-axis machining process and the three-dimensional carved stone machined through 5-axis machining process for the object, combining with the machining process, using Geomagic Qualify software for 3D comparison and deviation calculation, the processing error causes of the experiment case were analyzed. Digital alignment technology can be used to reposition the workpiece, and correct processing deviation for some large relief; the concrete causes what may generate the machining errors had been analyzed for three-dimensional carved stone. Decomposition the measurement data of 3D deviation to analyze which axis of the machine tool exist error, and to find the error distribution law, combining with the machining process, we can judge what are the problems in the manufacturing processes. Had verified that this method is real and effective when applied to 3D contour machining precision measurement for stone crafts which exist a large number of complex curved surfaces.