NCT Group NCT 990T - Manual (Page 80)

7.2.3 Automatic Tool Length Offset Measurement
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7.2.3 Automatic Tool Length Offset Measurement
Tool length offsets can also be measured automatically, provided the machine is mounted
with a tool offset sensor. Select screen
F4 T LENG MEASURE (tool length measurement) in
screen menu of F5 OFFSETS.
Switch control to JOG mode, than change the tool to be measured.
Move the tool tip near to the tool sensor by the use of jog buttons.
The length offset register in which the size of the tool is to be stored must be specified after
the action menu button is pressed. Press softkey
F3
OFS NO SEARCH (offset number search).
The number of the offset register to be used for the tool measurement must be written at
address N in the data input line than the data input must be terminated by means of button
or . In case parameter 1353 OFFSNL is set to 1 the cursor moves automatically to
the offset register the number of which corresponds to the number of tool activated.
Press softkey
F3 AUTO MEAS after the action menu is pressed.
Touch the tool sensor by moving axis with the appropriate jog button. In this case the speed
of movement is always the value defined at parameter 8022 G37FD independent of the
override switch state. Even 0% state of the override switch is ineffective, the jog button must
be released in order to stop.
As the tool tip touches the appropriate button of the tool offset sensor, the movement stops
and only movement in the contrary direction is possible. The control calculates the tool length
offset value automatically at the moment when the sensor has been pressed.
The tool offset sensor enables
measurement in all four directions
(X+, X–, Z+, Z–). It has buttons in all
four directions, their positions must be
calibrated and stored at parameters
previously. The parameters are:
8081 CONTACTX+,
8082 CONTACTX–,
8083 CONTACTZ+,
8084 CONTACTZ–.
The control subtracts value of the ap-
propriate CONTACT parameter from
the current position related to the ref-
erence point and the difference is re-
ferred to as tool length offset at the
moment of touch. On the diagram the
position of the Z– button of the sensor is defined to chuck’s plane. The control calculates the
z-direction length offset with the help of the equation below:
z
k
= z – CONTACTZ–
where: z
c
: the calculated tool length offset
z: position of the tool holder base point according to the reference point
CONTACTZ–: position of Z– button of sensor registered at parameter
Warning!
The work zero point offset must always be measured after the use of automatic length offset!