Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set User Manual
Page 448
Axis Motion
Chapter 12
12-76
To avoid this feedrate limitation, the short block Acc/Dec clamp can be
disabled by programming a G36.1. In this mode, the control assumes that
no rapid decelerations are required and allows axis velocities to go higher
than they otherwise would. Activate G36.1 mode only when:
no sudden changes in programmed feedrate within consecutive short
motion blocks exists (this includes requesting a feedhold or cycle stop)
no drastic change in programmed direction is present within the short
blocks
If any of the above conditions are not met during the G36.1 mode, the
control can overshoot positions since the axes do not have time to
decelerate. For example, consider the following position and velocity plots
if a drastic change in direction is requested after the move from Z5.0 to
Z5.1 when in G36.1 mode (see Figure 12.38) . The position Z5.1 is
overshot and the axis would have to reverse direction to reach proper
position.
Figure 12.38
Drastic Change in Direction while in Short Block Mode (G36.1)
Z5.1
Programmed Feedrate
Z-axis is traveling too
fast to stop when end of
move is reached.
Z
F
E
E
D
R
A
T
E
Z5.0
Z-axis overshoots endpoint of
move because of drastic change in
programmed direction.
D I S T A N C E
Series
of
short
move blocks.
Z4.9
Z4.8
X1.8
X1.9
X
Z
Z5.1
Z5.0
Series
of
short
move blocks.
Z4.9
Z4.8
Deceleration
Acceleration
12164-I
ATTENTION: The programmer must consider the direction
and feedrate transitions from block to block when the short
block acc/dec check is disabled (G36.1 mode). If the transition
exceeds the deceleration ramp of the axis, damage to the part or
equipment can occur.