Rockwell Automation 8510 Hi-Res Feedback Instructions - Manual (Page 5)

High Resolution Magnetic Feedback
Instructions
5
Detecting Gear Mounting Requirements
The accuracy of the feedback system is directly affected by the accuracy
with which the feedback gear is mounted to the spindle shaft. Using very
tight tolerances, the gear must be mounted to a surface that is perpendicular
to the spindle axis of rotation and must be mounted concentric with the
axis of rotation. Any wobble or eccentricity induces errors in the output
signal and reduces the absolute accuracy of the feedback system.
With the standard gear accuracy class, it is usually possible to meet the
gear installation accuracy requirements by simply mounting the gear to
carefully machined, low tolerance mounting surfaces on the spindle shaft.
With the precision gear accuracy class, it will be necessary to adjust the
gear during the mounting and alignment process to achieve the required
installation accuracy requirements. With this class of gear, the spindle shaft
should be turned slightly undersize to allow for concentricity adjustments.
Table A defines the general tolerances for the gear mounting surfaces for
the two classes of gears.
Table A
Mounting Tolerance (in millimeters)
Mounting Accuracy Characteristic
Squareness of mounting face relative
to spindle shaft center of rotation
Flatness of the gear mounting face
Dimensional tolerance of centering
shaft
Concentricity of centering shaft rela-
tive to spindle shaft center of rotation
Standard Accura-
cy
Less than 0.02
Less than 0.02
h5
(see Table B)
Less than 0.02
T.I.R.
Precision Accura-
cy
Less than 0.005
Less than 0.005
–0.05 / –0.10
Less than 0.02
T.I.R.
The Detecting Gear can be bolted directly to the mounting flange on the
spindle shaft or a clamping ring can be used to clamp it to the mounting
flange. The mounting flange and clamping ring diameters must be small
enough so they do not extend into the area of the gear teeth. This would
interfere with proper gear tooth signal pickup by the Sensor Head. Table B
and Figure 3 show the dimensions required for the mounting surfaces and
the gear mounting layout.
Figure 3 also shows the various ways the gear can be mounted to the
spindle shaft. Tolerances are shown for both the standard class and the
precision class gears.
After the gear has been mounted, the mounting concentricity relative to the
center of rotation must be verified. Use a dial indicator to determine the
runout and adjust the gear mounting until the T.I.R. is less than the
amounts specified below.
Standard Class Gear: Less than 0.02 mm T.I.R.
Precision Class Gear: Less than 0.005 mm T.I.R.