Numerical control device for predicting a machining termination time

A numerical control device for controlling a machine tool for repeatedly executing a number of machining stages from rough machining to finish machining by using one machining program, capable of predicting a machining termination time, comprising:

• stage average speed estimating means for estimating an average machining speed from the start to end of each machining state in accordance with machining conditions previously set for each machining stage;
• stage path length computing means for computing a machining path length for each machining stage in accordance with said machining program and said machining conditions;
• stage required time estimating means for estimating a required machining time for each machining state in accordance with the values computed by said average speed estimating means and path length computing means;
• executed machining path length calculating means for calculating the length of a machining path from a starting position of the currently executed machining stage to the current position;
• elapsed machining time clocking means for calculating elapsed machining time, said elapsed machining time clocking means adapted to be reset synchronously with the start of each machining stage and start clocking on elapsed machining time;
• actual average machining speed computing means for computing an actual average machining speed for the machining path from the machining starting position of the currently executed machining state to the current position based on the elapsed machining time given by said elapsed machine time clocking means and the executed machining path length computed by said executed machining path length calculating means;
• remaining machining path estimating means for estimating a required machining time for machining an unexecuted portion of the currently executed machining stage based on a value obtained by subtracting the executed machining path length, calculated by said executed machining path length calculating means, from the machining path length for the currently executed machining stage, computed by said stage path length computing means, and the average machining speed computed by said actual average machining speed computing means;
• total remaining machining stage estimating means for adding up required times estimated for the individual machining stages from the machining stage next to the currently executed machining stage to the final machining stage by means of said stage required time estimating means;
• expected machining termination time computing means for obtaining, after the current time, the point of the lapse of a time period equal to the sum of the remaining machining path estimated by means of said remaining machining path estimating means and the required machining time estimated by means of said total remaining machining stage estimating means;
• and
• expected machining termination time display displaying the expected machining termination time obtained by means of said expected machining termination time computing means.