| Most of the previous work in the area of verification systems has concentrated on aspects such as gouging during the cutting operation, tool-fixture collisions and detection of excess material that may have been left behind. The prediction of chatter which plays a very important role in reducing machining overheads and in increasing metal removal rates has not been substantially considered in currently available commercial systems. This dissertation outlines the development of a verification system to examine Numerical Control (NC) programs and to predict the occurrence of chatter in common milling operations such as pocketing.;This system plays the role of an off-line tool to ensure chatter-free machining and increased metal removal rates. The NC program, which contains a list of the various tool movements, does not provide explicit information about cutting parameters such as the radial and axial depths of cut, feed directions, or the mode of milling (up or down milling), which are needed for chatter prediction. It is therefore necessary to extract these parameters from models which utilize the tool trajectories contained in the NC program.;Algorithms are presented which refer to previously established databases of the limiting values of axial and radial depths for chatter avoidance. Additionally, certain corrective actions that are undertaken when the extracted values exceed these limit values are outlined. The pockets considered are restricted to simple 2 1/2 dimensional geometries and may include internal islands. Several examples are used to illustrate the application of the above system using pocketing NC programs generated using commercial NC packages and using some special algorithms. |
