
B–63523EN–1/03
7. FEEDRATE CONTROL/ACCELERATION
AND DECELERATION CONTROL
835
(2)Override near the basic circle
Near the basic circuit, the change in curvature of an involute curve is
relatively large. If such areas are cut at a programmed feedrate, a heavy
load may be placed on the cutter, preventing a smooth surface from
being produced.
When areas near the basic circuit where the change in curvature of an
involute curve is relatively large are cut, this function can reduce the
load on the cutter, thus enabling a smooth surface to be obtained by
automatically decelerating the tool movement according to the
parameter setting.
When the radius of curvature at the cutting point is in the range specified
by parameters (Rlmt1) to (Rlmt5), an override is applied as follows:
When Rlmt1 > Rcp " Rofs y Rlmt2
OVRb =
100 – OVR2
Rlmt1 – Rlmt2
(Rcp " Rofs – Rlmt2) + OVR2
When Rlmt2 > Rcp " Rofs y Rlmt3
OVRb =
OVR2 – OVR3
Rlmt2 – Rlmt3
(Rcp " Rofs – Rlmt3) + OVR3
When Rlmt3 > Rcp " Rofs y Rlmt4
OVRb =
OVR3 – OVR4
Rlmt3 – Rlmt4
(Rcp " Rofs – Rlmt4) + OVR4
When Rlmt4 > Rcp " Rofs y Rlmt5
OVRb =
OVR4 – OVR5
Rlmt4 – Rlmt5
(Rcp " Rofs – Rlmt5) + OVR5
Rlmt1 to Rlmt5 are set in parameters 5611 to 5615, and OVR2 to
OVR5 are set in parameters 5616 to 5619. OVRlo in the graph shown
below denotes the lower limit imposed on the override during involute
interpolation. It is set in parameter 5620.
Rcp "Rofs indicates Rcp + Rofs for an inside offset and Rcp – Rofs
for an outside offset.
100
OVR2
OVR3
OVR4
OVR5
OVRlo
0
Rlmt5 Rlmt4 Rlmt3 Rlmt2 Rlmt1
[%]
Override value
Change in
curvature
If the override calculation result is below the parameter–set lower
limit, the override is clamped to the lower limit.