AUTOMATIC TOOL SELECTION FOR ROUGH TURNING

This paper describes a system which selects the optimum tools for rough turning operations performed on a CNC centre. For all the tools that are plausible, the system calculates the machining cost based on approximate cutting data for the first and last pass in a multi-pass situation. Determination of the cutting parameters takes into account the main process constraints such as power, work-holding, chip-breaking, workpiece deflection and tool breakage. The system presents several alternative solutions, arranged in increasing order of cost, to the user who then makes the final decision. For a non-re-entrant area, each solution consists of one tool. If the area to be machined contains a recess (or a shoulder), the system usually selects two tools but under certain circumstances, three tools are selected. In the latter case, the first tool machines the material outside the recess and the other two tools machine the material within the recess. This facility, called 'geometrical decoupling' helps the user to avoid a suboptimum solution which is forced upon him by the geometry of the component. Tools have been selected for two simple components one of which contains a recess; these examples demonstrate the considerable reduction in machining cost that is possible when compared with non-optimal solutions.