Research And Implementation On Graphic Simulation Of 5-axis NC Milling

Machining simulation is an effective means of verifying NC programs before actually machining. It is also an important field in CAD/CAM, CIMS and virtual manufacturing. Specially, many investigators have attached importance to 5-axis NC machining graphical simulation, because its prominent theoretical significance and actual demand. Some key technologies have been solved partly such as the construct of geometric model, the realization of the processing for removing material and high quality dynamic graphics display of machining simulation and so on. The main achievements are as follows:1. A geometric model suitable for 5-axis milling NC machining graphical simulation system is established. Based on the feature of the 5-axis milling NC machining, a Dexel method is introduce to represent the workpiece, the data structure of Dexel method is improved refering to the shortage of the methord of constructing the triditional Dexel model, which has reduced the complex degree in simulation greatly.2. Based on the movement characteristics of the cutter in 5-axis NC machining, and by compounding the method of discretizing tool motion and tool motion analysis and the method of explicit solution, we develop the explicit representation of the cutter swept surface in 5-axis NC machining, which make the complicated swept surface be consisted of a series of simple plane and oval cylinder.3. Based on the explicit representation of the cutter swept surface, the approach of finding intersecting points rapidly is used to construct Dexel model of the cutter swept volume; The approach of rapid location is used to determine the Dexel link refresh scope of workpiece, and in the refresh scope, one-dimensional bool subtraction of Dexel models can be used to refresh the model, which has increased the simulation speed of the processing for removing material.4. Based on the feature of data structure of Dexel model and the concept of visibility sphere, a method is proposed to construct triangle gridding models from Dexel models, this method has avoided the step effect of Dexel model and enhanced the quality of graphics; The light model and blanking algorithm of OpenGL can be used to enhance the effects of realistic graphics in simulation, the multi-thread technique and the OpenGL double buffer mechanism can be used to guarantee the smooth effect of animation in NC machining graphical simulation. Based on the research achievements of this paper, the software module of 5-axis NC machining graphical simulation was developed, which has been validated by some examples such as overall impeller and so on, and the results show that the research of this paper is effective.