Yaskawa Sigma II Indexer - Manual (Page 85)

Sigma II Indexer User’s Manual Setting up the Reference Units
5-30
3. Determine the reference unit used.
A reference unit is the minimum position data unit (positioning resolution) used to
move a load.
• Reference unit can be 0.1in., or 0.01in., or 0.01mm, or 0.001mm, etc.
• When the reference unit is 1µm
If a reference of 50000 units is input, the load moves 50mm (1.97in.)
(50000
u 0.00mm = 50mm).
4. Determine the load travel distance per load shaft revolution in reference units.
• When the ball screw pitch is 0.20in. (5mm) and the reference unit is 0.00004in.
(0.001mm),
5. Electronic gear ratio is given as:
If the gear ratio of the motor and the load shaft is given as:
where N
2
is the rotation of the motor and N
1
is the rotation of the load shaft,
Ball Screw Disc Table Belt and Pulley
Reference unit: 0.001mm
Determine the reference unit according to
equipment specifications and positioning accuracy.
To move a table in 0.001mm units
Travel distance per load shaft revolution [reference units] =
Reference Unit
Travel distance per load shaft revolution
[in, mm, degrees, etc.]
= 5000 (reference units)
0.20 in
0.00004 in
Load shaft
P
1 revolution =
P
reference unit
P: Pitch
L d h ft Load shaft
1 revolution =
360°
reference unit 1 revolution =
SD
reference unit
D: Pulley
B
A
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© ¹
§ ·
N 2
N 1
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