2
Installation
2-20
6.3
Example of moment of inertia calculation
Let's discuss an example in which the chuck and workpiece are at a position offset by 10cm from the θ-axis by the stay,
as shown in the Fig. below. The moment of inertia is calculated with the following three factors, assuming that the load
material is steel and its density ρ is 0.0078kg/cm
3
.
Example of moment of inertia calculation
(The chuck and workpiece are at a position offset by 10cm from the θ-axis by the stay.)
10cm
2cm
2cm
θ-axis
1cm
1cm
2cm
2cm
4cm
6cm
4cm
Stay
Chuck
Workpiece
1. Moment of inertia of the stay
Moment of inertia of the stay
12cm
2cm
2cm
Center line
5cm
θ-axis
The weight of the stay (Ws) is given as follows:
Ws =
r
abc = 0.0078
× 12 × 2 ×
2 = 0.37 (kgf)
The moment of inertia of the stay (Js) is
then calculated from Eq. (7).
Js =
0.37
×
(12
2
+2
2
)
+
0.37
× 5
2
= 0.014 (kgfcmsec
2
)
12 ×
980
980