
A-78395E
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FANUC Series 16
i
/18
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-TA/TB
Specifications of High-Precision Contour
Control forComplex Lathe
2001.02.14 A.Fukumoto
02 2001.10.04
Description of Cs axis and rotary axis are added.
2.17.3 Feedrate determination based on acceleration along each axis
As shown below, when a curve is formed by very short successive line segments, there is no
significant feedrate difference along each axis at each corner. Consequently, the tool need not
be decelerated to compensate for feedrate differences. When taken as a whole, however,
successive feedrate differences generate a large acceleration along each axis.
In this case, the tool must be decelerated to minimize the stress and strain imposed on the
machine, as well as the machining error that may result from such excessive acceleration.
The decelerating speed is a feedrate by which the acceleration of each axis of all axes
becomes below a permissible acceleration which is set by parameter No.8470..
The deceleration speed is determined at each corner. The deceleration speed is calculated
respectively of the starting point and the end point of the block, and the speed in the small
becomes an actual feedrate.
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••
•
Example
In the example shown below, the tool is accelerated too quickly from N2 to N4 and from N6
to N8 (as indicated by the dashed–line inclinations in the feedrate graphs) when automatic
feedrate control is not used. So, the tool is decelerated.
Fig. 2.17.3 (a) Example of feedrate determination based on acceleration
Feedrate along
the X–axis
N1
N2
Y
X
N3
N4
N6
N7
N8
Feedrate along
the Y–axis
Feedrate along
the tangent to
the path
N1 N5 N9
N1 N5 N9
N9
N5