Fanuc Series 15i/150i-MA (Programming) Operators Manual

13.FUNCTIONS TO SIMPLIFY PROGRAMMING PROGRAMMING B-63324EN/03
- 320 -
13.2 RIGID TAPPING
In tapping, an amount of travel per spindle revolution along the Z-axis
must match the screw pitch of the tapper. This means that the optimum
tapping must satisfy the following condition:
P = F/S, where
P: Tapper screw pitch (mm, inch)
F: Feedrate along the Z-axis (mm/min, inch/min)
S: Spindle speed (min
-1
)
In the tapping cycle (G84) and reverse tapping cycle (G74), spindle
speed control is exercised independently of Z-axis feed control. This
means that the above condition is not always satisfied. At a hole
bottom, particularly, both spindle rotation and Z-axis feed are stopped
after deceleration, then are restarted by acceleration in the opposite
direction. Acceleration/deceleration operations for these motions are
performed independently of each other, so that the above condition is
not usually satisfied. So, in general, feed compensation is performed
by installing a spring inside the tapper holder to improve the tapping
precision.
On the other hand, in the rigid tapping cycle (G84.2) and reverse rigid
tapping cycle (G84.3), spindle rotation and Z-axis feed are controlled
so that these two motions are synchronized with each other at all times.
That is, only speed-related control is applied to the spindle for normal
rotation. For rigid tapping, however, position control is applied to the
spindle rotation, so that spindle rotation and Z-axis feed are controlled
by two-axis linear interpolation. Thus, the condition P = F/S is
satisfied even upon decelerating/accelerating at a hole bottom to
achieve high-precision tapping.

Leave a Reply

Your email address will not be published. Required fields are marked *