Research On The Methods Of Self-growing Modeling, Self-reference Measuring And Self-guided Machining

Based on the thought of self-organization, modeling, measuring and machining of curves are studied, three concepts (including self-growing modeling, self-reference measuring and self-guided machining) are presented in this thesis, relative techniques are also studied. Simulation and actual experiments are made for self-reference measuring and self-guided machining.Several major curve and surface modeling methods are analyzed in this thesis, the process of biological cell division and individual growth is used for reference, data unit that includes arc-length, curvature, torsion and etc is used as basic cell of curve and surface. And modeling of free-form curve is achieved by designing growth-rules of cell. The cells and grow rules of some curves including parabola, Corun-Euler curve, Archimedes curve, fractal curve and spiral line are extracted, some simulation experiment are made for self-growing modeling of the above curves. By designing the grow rules, some characteristic planar curves and space curves are created.How to extract cells and grow-rules from a known curve and surface, which is positive issue of self-growing modeling. And how to generate the curve and surface by designing and controlling the grow rules, which is inverse issue of self-growing modeling. Studying the positive issue is for machining, it is applied in self-guided machining. Studying the inverse issue is for modeling, it is applied in self-reference measuring.The methods of geometric measurement are analyzed at present, a method of self-reference measurement is first presented. It uses known part of measured object as the reference for continuing to measure, so the large-size workpiece can be measured by use of small-size measuring instrument. Three implementation projects for self-reference measuring are designed, which are superposition-type self-reference measurement, roller-preposed self-reference measurement and prope-preposed self-reference measurement. The feasibility of superposition-type measurement method is checked through many simulation experiment. The device for roller-preposed self-reference measurement is developed. The shape of circle, ellipse, cam and skate-arc are measured by using the device, and the shapes are reconstructed. The idea of self-reference measurement is achieved through these above experiment.The trajectory controlling methods in current NC systems are all based on coordinates, not baseded on geometrical shape. There are not geometrical shape models of parts in control loops of NC systems. The concept of self-guided machining is presented in this thesis. It make the machining profile matching instruction profile, use the part processed to guide the next process. It is direct feedback for geometrical shape. The corresponding effective algorithm is presented for the self-guided machining of the consecutive small blocks and arc, respectively. The profile matching and error prediction of self-guided machining are studied, and relevant simulation experiments are made.Self-guided machining is preliminary applied to actual machining. For specimens of wave surface shape and massif shape, when their machining paths are described by use of consecutive linear blocks, they need 128212 and 184954 linear blocks, respectively. When their machining paths are described by use of arc-cells, they need 15838 and 21669 arc-cells, respectively. It's more important that these arc-cells have information of curvatures and arc-lengths to control acceleration and deceleration. When the above two specimens are machined by means of the consecutive linear blocks, the average machining velocity are 10.83mm/s and 11.35mm/s, respectively. And the surface roughness values Ra are 1.93 um and 1.86 um. But when their machining paths are described by arc-cells and are machined, their average machining velocity are 39.01 mm/s and 40.12mm/s, respectively. And the surface roughness values Ra are 1.38 um and 1.34 um. Therefor, the machining velocity and surface quality of specimens are improved when their machining paths are described by means of arc-cells.