
A-78395E
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FANUC Series 16
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/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.
2.12 Smooth interpolation
2.12.1 Outline
Either of two types of machining can be selected, depending on the program command.
(1) For those portions where the accuracy of the figure is critical, such as at corners,
machining is performed exactly as specified by the program command.
(2) For those portions having a large radius of curvature where a smooth figure must be
created, points along the machining path are interpolated with a smooth curve,
calculated from the polygonal lines specified with the program command (smooth
interpolation).
This function can use only in the HPCC mode.
This function is an option.
2.12.2 Format
G05 P10000 ; : Starting of HPCC mode
G05.1 Q2 X0 Y0 Z0 ; : Starting of smooth interpolation mode
…
G05.1 Q0 ; : Ending of smooth interpolation mode
G05 P0 ; : Ending of HPCC mode
2.12.3 Explanations
To machine a part having sculptured surfaces a part program usually approximates the
sculptured surfaces with minute line segments. As shown in the following figure, a sculptured
curve is normally approximated using line segments with a tolerance of about 10 μm.
10μm
Enlarged
:Specified point
Fig. 2.12.3(a) Approximation with Line Segments
When a program approximates a sculptured curve with line segments, the length of each
segment differs between those portions that have mainly a small radius of curvature and those
that have mainly a large radius of curvature. The length of the line segments is short in those
portions having a small radius of curvature, while it is long in those portions having a large
radius of curvature. The high–precision contour control moves the tool along a programmed
path thus enabling highly precise machining. This means that the tool movement precisely
follows the line segments used to approximate a sculptured curve. This may result in a non–
smooth machined curve if control is applied to machining a curve where the radius of
curvature is large and changes only gradually. Although this effect is caused by high–
precision machining, which precisely follows a pre–programmed path, the uneven corners
that result will be judged unsatisfactory when smooth surfaces are required.