US Patent No. 9,256,213

NUMERICAL CONTROL UNIT HAVING FUNCTION TO SMOOTHLY CHANGE FEED SPEED WHEN OVERRIDE IS CHANGED


Patent No. 9,256,213
Issue Date February 09, 2016 
Title Numerical Control Unit Having Function To Smoothly Change Feed Speed When Override Is Changed
Inventorship Iwao Makino, Minamitsuru-gun (JP)
Assignee FANUC Corporation, Minamitsuru-gun, Yamanashi (JP)

Claim of US Patent No. 9,256,213

1. A numerical control unit to control a machine tool that machines work mounted on a table by relatively moving a tool at
a feed speed instructed by a machining program, including a command program analysis unit configured to analyze a commanded
speed of the machining program, a speed operation unit configured to operate a feed speed for each interpolation cycle based
on the commanded speed, an interpolation unit configured to perform interpolation based on the feed speed, an acceleration/deceleration
after interpolation unit configured to implement acceleration/deceleration to an output from the interpolation unit, a servo
motor controller configured to drive a servo motor based on an output from the acceleration/deceleration after interpolation
unit, the numerical control unit comprising:
a high speed cycle machining data acquisition unit configured to acquire high speed cycle machining data;
an override input unit configured to input an override as a multiplying factor of the commanded speed; and
a stepwise override change unit configured to output the override as an actual override after changing in steps the override
before input by the override input unit to the override that is input by a predetermined amount for each interpolation cycle;
wherein

the command program analysis unit is configured to acquire high speed cycle machining data from a high speed cycle machining
data acquisition unit;

the speed operation unit is configured to calculate the feed speed by multiplying the commanded speed by the actual override,
and multiply the high speed cycle machining data acquired by the high speed cycle machining data acquisition unit by the feed
speed; and

the numerical control unit is configured to output the high speed cycle machining data multiplied by the feed speed to the
servo motor controller that drives and controls the servo motor, without using the interpolation unit and the acceleration/deceleration
after interpolation unit.