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Installation manual
CNC 8055
CNC 8055i
7.
CONCEPTS
SOFT: V02.2X
Additive coupling between axes
7.14 Additive coupling between axes
The additive coupling may be applied on any pair of axes, but only one pair of axes may be defined
in an additive coupling. An additive coupling is not possible with the spindle.
A typical application of additive coupling is on milling machines where the Z axis has a second axis
W coupled to it that moves by hand. This allows operating manually on the Z component through
that axis.
In this case, the Z axis movements are defined by two axes. One motorized, whose parameters are
defined in the Z axis parameters and the other one (dro) whose parameters are defined in the W axis.
The CNC screen shows, in the Z axis coordinates, the sum of both feedbacks Z+W. The coordinates
of the W axis may be displayed either as a separate axis or may be set to be hidden (not displayed).
Likewise, the Z graphics represent the sum of Z+W.
Operation in jog mode
When displaying the coordinates of the Z axis, it shows the sum of both axes. The W axis may be
moved manually without affecting the Z axis. When moving the Z axis, it moves up to the software
limits of the Z axis taking into account the W axis position at the time.
Operation in the other modes (execution, etc.)
The CNC always monitors the software limits of both axes separately. If any of the limits is exceeded,
it will issue the corresponding error on the Z or W axis. It also monitors the software limits of the
Z axis when programming a movement either in execution or in JOG mode.
Machine reference (home) search
To carry out a full home search, do a home search on both axes separately.
• Z axis home search.
When detecting the marker pulse, the Z axis display shows the "REVALUE" of the Z axis plus
the position of the W axis. The PLCFZ variable is set to zero. The W axis is not involved in the
home search.
• W axis home search.
When detecting the marker pulse, the W axis display shows the "REVALUE" of the W axis. The
Z axis display shows the Z axis position plus the "REVALUE" of the W axis plus W axis position.
Configuration
The two axes have separate machine parameters. The additive coupling is configured with the axis
machine parameters "SWITCHAX" and "SWINBACK" of the DRO axis. The SWITCH* mark is not
involved in the additive coupling.
Likewise, we recommend to set general machine parameter "DIPLCOF=2" so the motorized axis
position display shows the PLCOF* component.
SWITCHAX (P65)
This DRO axis parameter indicates which is the main axis it is associated with.
SWINBACK (P66)
This DRO axis parameter indicates that an additive coupling is to be carried out on the axis indicated
by parameter "SWITCHAX". For additive slaving (coupling), this parameter is set to ·10·.
PLC Program
The W axis movements may be compensated on the Z axis via PLC. This is done by adding, in the
PLC, the feedback increments of the W axis to the PLCOFZ variable. We recommend to manage
the compensation through PLCOFZ with a periodic subroutine whose period is the same as the time
set in LOOPTIME.
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