Machining time predicting apparatus of numerically controlled machine tool

A machining time predicting apparatus that calculates a time taken for a tool to move on a designated tool path according to an NC command, comprising:

• a unit that divides the tool path into a plurality of segments;
• a speed calculating unit that acquires a speed in a tangential direction of each of the segments;
• a segment moving time calculating unit that calculates a time taken for the tool to move on each segment based upon the speed in the tangential direction acquired by the speed calculating unit;
• and
• a tool moving time calculating unit that acquires the total of the times taken for the tool to move on the respective segments, calculated by the segment moving time calculating unit, as tool moving time, wherein
• said calculating unit calculates the speed in the tangential direction of the segment from a starting point to a terminal of the segment, based on a predetermined restriction condition, in which the speed in the tangential direction is expressed by a first-degree equation with respect to time for each sections, regardless of time dependency of the speed in a tangential direction calculated by a numerical controller in actual machining control;
• and
• said segment moving time calculating unit calculates the tool moving time by identifying a value obtained by integrating a speed in a tangential direction as a length of the segment.