General Description - gefran ADP200 User Manual

2 General description

In conventional hydraulic Injection Molding Machines (IMM) all movements (Mould Closing - Charge - Injection
- Ejection) are controlled by hydraulic actuators. The oil pump determines an output pressure and flow rate in
excess of those actually required by each single machine actuator. Proportional solenoid valves then discharge
the oil in excess to achieve the correct levels.
The aim of hybrid machines is to regulate the flow and pressure of the oil generated by a fixed-displacement
gear pump (P1) driven by a brushless motor (M1) controlled by a drive, as shown in the diagram below, without
the need for a proportional valve.
The pressure in the hydraulic circuit is measured by a transducer (T1) and regulated according to a user-
defined value by means of a specific PID controller.
The flow rate is proportional to the rotational speed and displacement of the pump.
Figure 1 General Scheme of an hybrid IMM with servo pump
The flow rate and pressure settings are mutually exclusive, i.e. if the pressure generated is below
requested value the motor is driven at the requested speed, otherwise speed is modulated to limit the pressure
to the set value.
The advantage of hybrid machines is that they save energy. The oil flow and pressure can be adjusted exactly
as required by the machine rather than at higher levels, without having to discharge oil as in conventional
hydraulic machines.
That is why hybrid machines are also referred to as "Servo Energy-Saving IMMs".
Some manufacturers estimated the energy saved by these machines as:
Energy-Saving vs Conventional fixed-pump IMM = saving of 55%
Energy-Saving vs Variable-pump IMM = saving of 17%.
The drive thus receives Flow and Pressure references and the Pressure feedback, as shown in picture below.
ADP200 Application PID-IMM User Manual Pag. 5 of 80