Parker 406LXR Series, Руководство по эксплуатации продукта

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Parker Hannifin Corporation
EMN Automation - Parker
Irwin, Pennsylvania
31
406LXR Series Product Manual Chapter 4 - Performance
Step 2: In this step, we first convert 1280 mm to 1.28 meters my dividing by 1000. Next we multiply by the
slope factor to calculate the slope error distance of this move (1.28 * 0.085) = 0.1088 mm.
Step 3: We subtract the error from the original distance (1280 – 0.1088) = 1279.8912 mm.
Step 4: Here we simply assign the new calculated distance as our current command distance.
This same program works if the slope error is negative. For example, if the slope error was – 0.085
instead of +0.085 the equation would work out like this:
VAR2 = (1280/1000)*( - 0.085) = - 0.1088
VAR3 = 1280 – ( - 0.1088) = 1280.1088
Thus correcting for the negative slope.
Note: Above are examples for incremental moves. The same program works if programming in
absolute coordinates.
Note: Each unit is shipped with both the non - slope corrected accuracy plot and a slope corrected plot.
These plots can be used to “ MAP ” the table, making positioning even more accurate. Mapping is
correcting for the error of the device at each location. This can be done by knowing the motion
positions and the error at each of these positions and setting up a matrix of variables in your motion
program. This method provides excellent accuracy but is time consuming to setup.
Attainable Accuracy with Slope Correction
Travel
(mm)
Accuracy
(µm)
Travel
(mm)
Accuracy
(µm)
50 12 750 36
150 12 850 36
250 12 950 40
350 16 1200 48
450 24 1550 64
550 24 1750 72
650 28 1950 84
Thermal Effects on Accuracy
All specifications for the 406LXR are taken at 20° C. Variation from this temperature will cause
additional positional errors. If the base of the 406LXR varies from this temperature the encoder scale
will expand or contract, thus changing its measuring length and thus encoder resolution.
The factor by which this thermal effect occurs is 0.000022mm/mm/° C. Although this sounds like a
very small number it can make significant accuracy and repeatability effects on your applications,
especially on longer travel applications. To understand this better let ’ s look at an example:
Example: A 406LXR with 950mm travel is being used. The accuracy over the entire travel is 40
microns at 20° C. If the base temperature increases by 5° C an additional error of 105 microns will be
added over the total travel (0.000022mm/mm/° C)*950mm*5° C. As you can see this error is
significant. However, this additional error can be compensated for since the error is linear.
Below is a graph of the accuracy of the 406LXR with respect to base temperature and travel. Each line
represents the additional error of the table caused by the elevated temperature.