
B–63833EN–1/02
9. SPINDLE SPEED FUNCTION
468
With this function, an overheat alarm (No. 704) is raised and the spindle
speed fluctuation detection alarm signal SPAL is issued when the spindle
speed deviates from the specified speed due to machine conditions.
This function is useful, for example, for preventing the seizure of the
guide bushing.
G26 enables spindle speed fluctuation detection.
G25 disables spindle speed fluctuation detection.
The function for detecting spindle speed fluctuation checks whether the
actual speed varies for the specified speed or not. Sd or Sr, whichever is
greater, is taken as the allowable fluctuation speed (Sm). An alarm is
activated when the actual spindle speed varies for the commanded speed
(Sc) under the condition that the variation width exceeds the allowable
variation width (Sm).
Sd: The allowable constant variation width which is independent of the
specified spindle speed (Sd is set with parameter No. 4913.)
Sr: The allowable variation width which is obtained by multiplying Sc
(commanded spindle speed) by r (constant ratio). (r is set with
parameter No. 4912.)
Sm: Sd or Sr, whichever is greater
If the specified spindle speed Sc changes, spindle speed fluctuation
detection starts when one of the conditions below is met:
⋅ The actual spindle speed falls in a range of (Sc – Sq) to (Sc + Sq)
where Sq = Sc
q/100
q: Percent tolerance of the target spindle speed, specified in parameter
No. 4911. If the actual spindle speed is in a range of the specified
speed "q, it is assumed that the actual speed has reached the
specified speed.
⋅ When time p specified in parameter No. 4914 elapses after the specified
speed Sc changes.
Parameter No. 4914, 4911, and 4912 can be rewritten also by program
(G26 PpQqRr).
9.5
SPINDLE SPEED
FLUCTUATION
DETECTION
General
Detection of Spindle
Speed Fluctuation
Conditions to start
spindle speed
fluctuation detection