Specialized Concentrated Focused
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52
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Operation
clearance between the screws of last direction that the spindle needs to finish after reversing its moving
direction.
Measuring Method and Compensation Method
Backlash can be measured by a specialized gauge. Firstly, fix the instrument nearby the spindle.
Secondly, make the watch hand at th
e zero point position (machine origin). Thirdly, manually move “a”
millimeter, then move back “a” millimeter, and then see the actual moving distance of watch hand “b”
millimeter. Therefore, the backlash is measured, namely (a-b) millimeter.
If one axis mo
ves from positive to negative, “+Q” pulse will be output before reversal; conversely, from
negative to positive, “-Q” pulse will be output before reversal (Q is backlash, preset by the program).
3.11.1.2 Screw Error Compensation Operation
Actually the system has already combined the above two errors (screw pitch error and backlash) to deal
with and will execute error compensation automatically based on the error data in the file after the
backward error and forward error of the corresponding nominal coordinate of each coordinate axis are
listed into the screw error compensation file.
The detailed operation is: save the measured value of compensation in file
“axeserr.dat” in directory of
USB disk which is sticked into NK200 system. The system will execute compensation as the file
described immediately.
Screw Error Compensation File
“axeserr.dat”
The name of the screw error compensation file is “axeserr.dat”, found under the installation directory.
Modification to the data in the screw error compensation file will become valid after the software is
restarted.
The file format is:
1) Firstly specify length unit, currently the supported length unit is mm and the style of writing is: unit =
mm
2) Then specify error sequence of each axis. To work properly, the contents in this sequence must be
in the ascending order of nominal machine coordinate value. Refer to Table 3-1 for details.
3) Annotation: it must be in a separate line and started with a semicolon. Its syntax is:
;<Annotation contents>
Note that a semicolon must be the first character of the separate line, that is, no other character should
be in front of the semicolon, even blank space.
Table 3-1 Explanation about Axis Error Sequence
Item
Specification
Axis Name
X, Y, Z, (Case-insensitive)
Nominal
Machine
Coordinate
It is the machine coordinate with a sign with respect to reference point, which is
calculated by the given pitch and pulse equivalent (i.e. the length calculated
based on the nominal pitch, not on the actual physical one), arranged in
ascending order. Nominal machine coordinate must be within the stroke range,
