Research Of Dynamic Three-Dimensional Lathe-Simulation And Collision Technology

With many characteristics such as wide usage, high machining precision andproductivity, NC machine has been widely used in the field of machinemanufacturing. In the course of the usage of NC machine, the method of checkingNC program is one of important factors effecting on productivity. When NCprogram is being made, it is unavoidable for some errors to occur in program,because a lot of things have to be thought. These errors will result in waste ofcapital, manpower and time if they occur in the process of manufacturing. So NCprogram must be examined to assure it is right before it is used to production.In these days, global competition in manufacturing field has become so drastic,that how to reduce the cycle of product development and the cost of product hasbecome the most critical problem which confronts the modern manufacturers whenthey want to improve the comprehensive competence of their products. With thecontinuous development of computer technology and the far-reaching developmentof computer aided engineering, VM (Virtual Manufacturing) gradually come intobeing, which provides a new solution to this problem. The wide application of VMtechnology will radical change the current manufacturing mode and exalt anenormous influence on the relevant industry. We can say that the VM technologywill decide the future of the corporations. We must lay a strong emphasis on thestudy of VM technology and the establishment of its development strategy. Toimprove the VM technology, we must make some progresses with its supporttechnology, such as the virtual reality technology and simulation technology. So wemust put an emphasis on the study and development of computer simulation fromthe point of view of the virtual technology development. CS (Computer Simulation)which is the main reality method of VM is a technology that uses computersoftware to simulate the real system in science experiments. Its essence is toabstract the real physical system in a certain level to obtain a model which can bothreflect the essential features of real system and be tested easily. Compared with thereal system, these abstract models can provide the users with more efficiency,saving, flexibility, and safety. The numerical controlling simulation of process indicates a mapping of NCmachine tool in the virtual environment, and it includes the technique ofmanufacture, the theories of NC machine tool, CAD, CAM, and the technique ofmodeling and simulation. The people can apperceive the virtual environment of 3Dsimulated model developed by computers, carry the NC process of parts in virtualcondition before the true doing when we design of alter a project, inspect theexactitude and justification of NC program, evaluate and optimize the project ofprocess. Thereby the intention, abridging the time of developing products,depressing the cost of manufacture, advancing the quality of products andefficiency of production, can be finally achieved. Tape Tryouts (TTOS) is traditionally applied to check the NC program'svalidity and to avoid generating the interference and collision, which inspectsdifference between the mould and original design, repeat to edit and modify theprogram until getting a acceptable workpiece. Usually this course spends a longdebugging time and a high cost, and moreover, is prone to accidents. By graphicallysimulating the NC program, checking the machining path of a tool, imitating thewhole NC machining process even the process of removing the material on a part,Machining Process Simulation (MPS) greatly reduces machining expresses and theNC debugging time, brings preferable economic benefit. In addition, MPS packagecan optimize producing, train programmer and so on. This thesis discusses the whole technological course and implement programon the NC machining simulation system theoretically and practically, especially thekey points of system studies, so much as NC simulation model establishment, NCsimulating data disposing and interference check for the machining process anddiscussed in depth, and some new algorithms are put for ward. Based on these, withcomputer simulated technology and computer animated technology, applying themethod of simulation based on NC program, this thesis develops the machiningprocess 3D animated simulation system. This thesis has mainly accomplished contents as follows: The general structure of the machining process simulation system has beenproposed according to the function requirement of the machining processsimulation. And the relationships among the models in the system have beenpresented out. The key techniques about the machining process simulation havebeen studied. The technology of drawing 3D graphics has been lucubrated. The interfaceclass environment between OpenGL and visual C ++ has been designed by usingOOP technique. Friendly WINDOWS styles interface has been designed. User canconveniently simulate machining process. According to the characteristic of the machine tool, the simulation model ofthe NC machining simulation system has been established. The interpreting of NC program, creation and interpolation of data on toolposition has been realized. Research on the key algorithms of solid modeling and 3D graphical display formachining simulation of NC lathing has been carried out. Considering thecharacteristics of lathing machining, simplify the construction of cutter-swept body,and "subtract"it from the workpiece in Boolean Operation. After this, the surfaceof the workpiece is triangulated and dynamically updated on the screen. The flow structure of NC machining process simulation is analyzed. The 3Dsolid representation model and its data structure of machined part are presented.Upon the characteristics of this structure, the algorithm for detecting collisionsbetween the turret and the workpiece or between the tool and the jaw is studied. Through studying main methods about collision detection at the present andaccording to the features of simulation itself, models in virtual environment weremade by B-rep. Based on the concept of polygons, the method of collision detectionin three-dimension was converted into two-dimension, which made the process ofcalculation simple and improved the efficiency of simulation.