GUHRING - Резьбофрезы - 2015 EN
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Technical Information
Thread milling process and technology
Machining combinations (reverse rotation/synchr. milling) Interference and feed ratio
As the thread milling cutters are designed for right hand If the milling cutter diameter to the nominal thread diameter
cutting, the direction of rotation is generally clockwise. ratio of 70° is adhered to, a profile distortion, irrespective of
By altering the axial direction of feed, reverse rotation the profile depth of the thread, should not occur. This factor
or synchronous milling, all thread combinations can be is well proven.
produced.
The application conditions, such as blind or through hole, This drawing illustrates that the diameter of the thread
horizontal or vertical machining methods as well as the type milling cutter and the profile depth determine the pressure
of lubrication and chip removal determine the correct choice angle to the thread diameter.
of milling procedure.
For thread milling, synchronous milling should be applied The feed at the cutting edge of the thread milling cutter is
whenever possible, in order to achieve lower cutting forces, calculated by the cutting speed revolutions) and the feed
improved chip formation, a better tool life and surface rate per tooth.
quality.
Synchronous milling can be identified when the cutting With linear movement, the feed rate at the cutting edge
edge emerges with chip thickness h = 0. is identical to that at the tool center. However, the helical
interpolation follows the path of a circle in the plane. As
reverse rotation synchronous the machine tool always calculates to the tool center, a
milling milling command must be programmed for converting the cutting
speed (contour related program). If such a command does
not exist or the central point is programmed, the feed rate
must be first converted.
A AA The interactive control at the control panel always indicates
the speed at the center point of the tool. When running with
Synchronous thread milling no load this is simple to check. If disregarded, the milling
can be identified wh=h0 en theh=0 h=0 cutter runs at a speed many times faster than the feed which
generally leads to tool breakages.
cutting edge emergehs=mwith a h=m h=m
chip thickness h=0
pre ssure angle of thread milling cutte
Technicalnom. of
thread
rmilling cutter
RH cutting in through hole: RH cutting in blind hole: core of internal thread
reverse rotation clockwise synchronous rotation nom.-
circle, downward pitch anticlockwise circle,
upward pitch Formula of calculation
LH cutting in blind hole: LH cutting in through hole:
reverse rotation clockwise synchronous rotation contour feed (vf) vc = d. .n [m/min]
circle, upward pitch anticlockwise circle, path center point feed (vm) 1000
downward pitch nom. (D)
thread milling cutter direction of rotation n= vcd. 10 00 [min-1]
axial direction of feed milling .
pitch cutter (d)
vf = n . z . fz [mm/min]
vm = vf . (D - d) [mm/min]
D
vb = n . fb [mm/min]
vvnvcfm = cutting speed feed
= contour feed
= center point path
= revolutions
z = number of teeth
vDffzbb = feed per tooth
= feed for drill per revolution*
= drill feed rate*
= nom. of thread [mm]
d = milling cutter nom. [mm]
* for drill/thread milling
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