\

3.2.3)

\

Maximum input P_max = 2.5 kW

\

Speed N = 1500 rpm

\

At maximum power the machine efficiency η = 85 %

\

Maximum Speed N_max = 3500 rpm

\

Minimum Speed N_min= 30 rpm

\

The torque at the driving spindle of the lathe at minimum speed T = ?

\

P = 2πNT/60

\

At spindle power losses included.So 85 % of total power is remained.

\

Power at spindle P_s = ηP_max

\

P_s = 0.85×2.5×10³

\

P_s = 2125 W

\

But at minimum speed , torque is maximum.So T = T_max

\

P_s = 2πN_minT_max/60

\

T_max = P_s×60/(2πN_min)

\

Substitute N_min = 30 , P_s = 2125

\

T_max = 2125×60/(2π×30)

\

T_max = 795.775 N-m

\

The torque at the driving spindle of the lathe at minimum speed is 795.775 N-m

\