
B-65302EN/01 SPECIFICATIONS FOR THE βiS SERIES 3.SELECTING A MOTOR
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3.2.6 Calculating the Percentage Duty Cycle and ON Time with the
Maximum Cutting Torque
Confirm that the time (duty percentage and ON time) during which
the maximum cutting torque can be applied for cutting is shorter than
the desired cutting time.
First, calculate the load torque applied when the cutting thrust (F
c
) is
applied to the motor shaft (T
ms
). When this load torque is smaller than
the product of the motor stall torque (T
s
) and thermal efficiency (α),
the motor can be used in continuous cutting. If the value is greater
than the product, follow the procedure below to calculate the ON time
during which the maximum cutting load torque (T
ms
) can be applied to
the motor (t
ON
) and the percentage ratio (percentage duty cycle with
the maximum cutting torque) of the ON time to the total time of a
single cutting cycle (t).
α is assumed to be 0.9. Calculate the percentage considering the
specifications of the machine.
Determining whether continuous operation can be performed with the
maximum cutting torque
Calculate the percentage duty cycle, according to the following figure
and expressions.
T
ms
<T
s
×α
Operation can be continued with the maximum cutting torque.
(The percentage duty cycle with the maximum cutting torque is
100%.)
T
ms
>T
s
×α
Calculate the percentage duty cycle, according to the following
figure and expressions.
[Example of calculation for condition 6-1]
Percentage duty cycle and ON time with the maximum cutting torque
The load torque in cutting is calculated as follows:
F=F
c
+µ(W+F
g
+F
cf
)
F=980+0.05×(2940+490+294)=1166[N]=119[kgf]
T
m
=(1166×20×10
-3
×1)÷(2×π×0.9)+0.8=4.9[N⋅m]=50[kgf⋅cm]
The stall torque of the β12/3000is (T
s
) is 11 [N⋅m].
T
s
×α= 11×0.9 = 9.9[N⋅m]=101.0[kgf⋅cm]>T
ms
= 4.9[N⋅m]
=50[kgf⋅cm]
No problems will occur in continuous cutting.