Convex Thread (G335, G336) - Siemens SINUMERIK 840D Function Manual

V1: Feedrates
5.2 Path feedrate F
5.2.3.6

Convex thread (G335, G336)

Function
The G commands G335 and G336 can be used to turn convex threads (= differing to the
cylindrical form). Application is the machining of extremely large components that sag in the
machine because of their self-weight. Paraxial thread would result in the thread being too small
in the middle of the component. This can be compensated with convex threads.
Figure 5-2
Programming
The turning of a convex thread is programmed with G335 or G336:
G335:
G336:
The programming is performed first as for a linear thread by specifying the axial block end
points and the pitch via parameters I, J and K.
An arc is also specified. As for G2/G3, this can be programmed via the center point, radius,
opening angle or intermediate point specification. When programming the convex thread with
center point programming, the following must be taken into account: Since I, J and K are used
for the pitch in thread cutting, the circle parameters in the center point programming must be
programmed with IR=..., JR=... and KR=....
IR=...:
JR=...:
KR=...:
Note
IR, JR and KR are the default values of the interpolation parameter names for a convex thread
that can be set via machine data MD10651 $MN_IPO_PARAM_THREAD_NAME_TAB.
Optionally, a starting point offset SF can also be specified.
146
Turning a convex thread
Turning of a convex thread on a circular tool path in a clockwise direction
Turning of a convex thread on a circular tool path in a counter-clockwise direction
Cartesian coordinate for the circle center point in the X direction
Cartesian coordinate for the circle center point in the Y direction
Cartesian coordinate for the circle center point in the Z direction
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA