
B–64113EN–1/01
9. SPINDLE SPEED FUNCTION
615
Changing gears during rigid tapping requires a different process from that
for gear changes during normal machining. As described above, changing
gears conforms to the gear change specifications mentioned in section 9.3
when the M type gear selection method has been selected. With the T type
gear selection method, changing gears conforms to the logic programmed
in the PMC.
Regardless of the option’s selection, if the range in which the spindle
speed specified by the S function code does not correspond to the
currently selected gear, the gears are changed.
The following tables list the spindle speed ranges for each gear during
normal machining (assuming no machine restrictions) and rigid tapping:
Spindle speed range (normal machining)
Lower limit Upper limit
Low–
speed
gear
1 revolution Maximum low–speed gear speed =
Maximum spindle motor speed L%
Low–speed gear ratio
Medium
speed
gear
Maximum low–speed
gear speed + 1 revo-
lution
Maximum medium–speed gear speed =
Maximum spindle motor speed L%
Medium speed gear ratio
High–
speed
gear
Maximum medium–
speed gear speed +1
revolution
Maximum high–speed gear speed =
Maximum spindle motor speed L%
High–speed gear ratio
NOTE
This table shows an example of three gears. L% indicates
a spindle motor protection constant (up to 100). L can be
specified for each gear using method B for changing in M
type gear selection method (bit 2 (SGB) of parameter No.
3705 =1).
Spindle speed range (during rigid tapping)
Lower limit Upper limit
Low–
speed
gear
1 revolution Maximum low–speed gear speed
Basic spindle motor speed +α
=
Low–speed gear ratio
Medium
speed
gear
Maximum low–speed
gear speed + 1 revo-
lution
Maximum medium–speed gear speed
Basic spindle motor speed +α
=
Medium–speed gear ratio
High–
speed
gear
Maximum medium–
speed gear speed +1
revolution
Maximum high–speed gear speed
Basic spindle motor speed +α
=
High–speed gear ratio