
3.INTERPOLATION FUNCTION NC FUNCTIONS B-63322EN/03
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3.17.1 NURBS Interpolation Additional Functions
The functions below are added to the NURBS interpolation function of
the FANUC Series 15i.
- Parametric feedrate control
The maximum feedrate of each segment is determined by a specified
feedrate and acceleration value. For successive segments, a feedrate at
a segment start point and a feedrate at a segment end point are
determined as described below. Then, the feedrate changes
successively during movement from the start point to the end point.
This function is applicable only to NURBS interpolation when bit 5
(FDI) of parameter No. 8412 is set to 1.
- High-precision knot command
When bit 1 (HIK) of parameter No. 8412 is set to 1, a knot command
consisting of up to 12 integer digits and up to 12 fraction digits can be
specified. This function is applicable only to a knot command (address
K) including a decimal point during NURBS interpolation.
- Simple start command
When bit 0 (EST) of parameter No. 8412 is set to 1, a control point
command can be omitted at the first control point. The knot values of
the first block and the second block are the same, so that the knot
command can be omitted for the first block only.
- Maximum cutting feedrate along each axis
With the conventional specification, the specified feedrate F during
NURBS interpolation is clamped to the minimum value of the
maximum cutting feedrate (parameter No. 1422) of each axis as
indicated by the expression below.
))(),(),(),(),(Min(
maxmaxmaxmaxmax
BFAFZFYFXFF ≤
So, when the maximum cutting feedrate of a rotation axis F
max
is small,
the specified feedrate F during NURBS interpolation may be clamped
to F
max
of the rotation axis, resulting in an increase in machining time.
This function changes the method of clamping the specified feedrate F
as described below.
The specified feedrate F is clamped so that the component of F along
each axis does not exceed the maximum cutting feedrate (parameter No.
1422) of each corresponding axis (Fig. 3.17.1(a)).