Siemens sinumerik 840D sl Function Manual page 137

Brief description
Gantry axes
Gantry axes are mechanically grouped machine axes. Because of this mechanical coupling,
gantry axes are always traversed in unison. The control occurs through the "gantry axes"
function.
The machine axis that is directly traversed is called the leading axis. The machine axis that
is traversed in conjunction with the leading axis is called the synchronized axis. The leading
axis and the synchronized axes together form a gantry axis grouping.
The difference between the actual positions of the leading axis and the synchronized axes is
monitored continuously. When the actual position values of the synchronized axes deviate
too much from that of the master axis, the control automatically shuts down all axes in the
gantry grouping to prevent any damage to the machines.
Application
Two feed drives are required to traverse the gantry on large gantry-type milling machines,
i.e. one drive with its own position measuring system on each side. Owing to the mechanical
forced coupling, both drives must be operated in absolute synchronism to prevent canting of
mechanical components.
Configurations
In total, eight gantry connections can be defined.
One gantry grouping consists of a master axis and up to two synchronized axes.
Special functions: Gantry Axes (G1)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0
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