V&T TS-I Series, User Manual, Page: 75 / 79

TS − I Special servo drive for hybrid electro-hydraulic system of injection molding machine User Manual
Chapter 6 Debugging, selection and function application 63
6.2 Method of selecting the main components of the injection molding
machine electrolytic mixing system
According to the manufacturer’s parameters, the available information: System flow is Q (L/min
）
; System
pressure is Pe (kgf/cm2
）
; and Max motor speed is Vmax (rpm).
6.2.1 Selection of oil pump
Selection of oil pump pressure: Max pressure of oil pump Pmax ≥ Pe
Selection of oil pump flow: L=Q × 1000/Vmax (cc/rev)
Oil pump type selection: Select the oil pump type according to the different requirements of the injection
molding machine.
Oil pump Price Efficiency Stability Noise Reliability Single Rotating
Gear pump Low Low Medium Medium High Low Medium
Plunger Medium High Low High Low Medium Low
Screw rod High Medium High Low Medium High High
6.2.2 Motor selection
Selection of rated speed of servo motor: According to the feature of the servo motor, the motor torque is
decreased gradually as its speed is increasing. When the motor torque reaches the 150% rated speed, the
internal magnetic field of the servo motor will be saturated and the torque will be decreased sharply, so this
speed shall not be used as the working speed of the motor in the mixing system, so we select the following
parameters:
Vmax ≤ 140%Ve
To ensure the better control effect and safe operation of the motor, the rated speed of the servo motor is:
Ve=Vmax/1.3
（
rpm
）
Selection of the rated torque of the servo motor: According to the energy conservation law, the max
output power of the molding injection machine is:
P2max=1.02PeQ/600
（
kw
）
Since the mechanical and hydraulic conversion efficiency between the motor and pump should be
considered, the max output power of the servo motor is:
Pdjmax=1.1P2max
（
kw
）
Max output torque of the servo motor is:
Tmax=9550Pdjmax/Ve(N.m)
According to the characteristic, control requirement and safety and reliability of the servo motor, the max
output torque should not exceed the 180% rated torque of the servo motor:
So, the rated torque of the motor:
Te=Tmax/
（
1.65
～
1.8
）