Research On The Sawing Process And Algorithm In Special Shape Stone

With the development of stone machining industry and improvement of people's material and cultural lives,the stone industry is developing rapidly and there is a growing demand for stone.Meanwhile,the competition is becoming increasingly fierce among stone enterprises.Besides,there are higher and higher requirements for efficient manufacturing and machining in these enterprises.According to current development of stone machining in China,it may be observed that irregular stones play a critically important role in the industry of stone decoration.The demands for irregular stone products,especially the stone products with rather complicated surface are constantly increasing.Furthermore,enterprises and scholars pay more and more attention to the efficiency of machining irregular stones.Although irregular stones are mostly machined by machines,the machining techniques are relatively monotonic,so it is necessary to diversify the machining techniques for stone products and increase the stone machining efficiency.Widely used in mechanical manufacturing at present,sawing technology has become very mature in the stone machining industry,whereas it has just been applied in machining irregular stones.While there is such a blank in China,foreign scholars have begun to use this technology for three-axis machining of irregular stones.Sawing is widely utilized for stone machining with fairly high efficiency,but many scholars have only examined its performances in machining and haven't paid due importance to the application of this technique in machining irregular stones.Aiming at this blank in China,this paper analyzes processes of sawing used for three-axis machining and studies corresponding algorithms.By exploring the traditional sawing processes,it examines three-axis sawing processes according to characteristics of three-axis machining.In machining irregular stones,models are generally constructed based on the real objects available by three-dimensional scanning of point cloud and grey-scale images,etc.It is relatively difficult for one to construct a model independently.Therefore,the acquisition of complex surface models is studied and a model is constructed by scanning original real objects with methods like reverse engineering to obtain its three-dimensional point cloud data.Additionally,the scanned three-dimensional point cloud data are analyzed and preprocessed.For irregular stone products like stone sculptures,stones are usually machined by milling and abrasion to guarantee high precision.Nonetheless,it shall cost much time in nmachining due to machining and working methods of milling tools.Therefore,a tool path generation algorithm is proposed for sawing based on HTM50200 irregular stone milling and machining center,so as to roughly machine stones with irregular surface by sawing.After digitalizing the three-dimensional surface of irregular stones,a range of two-dimensional curves are obtained.Then,the intersection between the section plane and the three-dimensional curve is determined with section curve expanding method to obtain the contact path of the tool.Meanwhile,the cutting path planning,calculation of location points and handling of interferences on tool path for special sawing process are described.In addition,this paper introduces proper selection of step length and path interval for sawing in detail.Tools shall be reasonably selected for sawing by considering the interferences and over-cutting.By analyzing point cloud data of characteristic surface of irregular stones,the author designs programmes with MATLAB,generates a curve of orderly point cloud data through interpolation,plans tool path and processes the path by interference and over-cutting.Finally,the interpolation results of the tool path are simulated.Besides,an experiment is carried out according to milling strategies and the algorithm proposed in this paper to compare the length and machining efficiency of the tool path.The results suggest that the algorithm for three-axis sawing is correct and feasible,which effectively increases the machining efficiency.