| Verification of multi-axis numerically controlled (NC) machining programs is a costly procedure in the manufacturing process, especially when one uses the side of the cutter to do milling operations. A new object-space-based (surface-based) verification system has been developed for multi-axis NC milling of sculptured surfaces. The dissertation describes an algorithm which discretizes the nominal sculptured surfaces and directly computes the possible interference between these surface points and the moving tool without explicitly creating the bounding surface of the tool motion (the tool swept volume). The geometric model uses the ruled surface defined by the axis of the cutting tool to define the center of the tool envelope. This result requires far less computation under typical conditions than would the use of direct solid modeling. In contrast to image-based methods, the algorithm is view independent (except for final graphical display), which means that displaying another view of the part does not require a rerun of the program, and, within broad limits, accurate displays of resulting gouging and undercutting with altered tolerances are possible without rerunning the verification algorithm. The approach utilizes positional (true position) tolerances on the desired part surfaces, and outputs a colored-coded display of the as-designed surfaces which depicts regions within tolerance, gouged, and undercut. |
