Green Line

Green Line

The energy saving Green Line machine is equipped with a variable speed synchron motor, controlled by an inverter, and with a internal gear pump with fixed displacement

The motor transmit the torque to the pump, that in this case is a single stage one and must be able to generate variable pressures and oil flows, depending from the requirements of each single working phase. Different pressure and oil flow values are obtained by variating the motor speed and the regulation is checked by a rotational encoder integrated in the system. A pressure sensor, in closed-loop connection, is monitoring the pressure value in the circuit and set the increase or reduction of speed in an iterative manner.

In the starting phase, the servomotor starts to make the internal gear pump rotating, which is building up pressure in the circuit. Being the oil flow rate fixed, the motor is able to maintain the line pressure at a preset value (in our case 140bar) even with a lower speed. At the very moment when an actuator starts to operate, a reduction of the pressure is detected and immediately the controlling of the system increase the speed of the pump to reinstate the line pressure. A controlling inverter allows to regulate the speed and the pressure depending from the instantaneous requirements of the running working cycle. In stand-by phases, the servomotor maintain a low rpm rate (40÷50 rpm) and therefore a limited energy consumption, on the other side during the operational phases the rotational speed increases and consequently the energy consumption rises. The new machine results, therefore, fast and immediate in using the resources available, but only when it is really necessary. At the same time, the use of an internal gear pump allows to increase the performances and limit the noise production.

The advantage of the internal gear pump, compare to the vane pump, is to have a practically stable oil flow rate when pressure varies. The energy absorption from the mains is discontinuous and happens only when the working cycle requires it, in this way making the costs drop. The new system allows to significantly reduce the noise production at average running level, making it necessary to put on the electrical cabinet a light signal to show that the machine is in function.

Supervising the function, at each single instant, of the motor and the energy consumption, a significant reduction of the thermal transfer to the fluid is obtained, and because of this a further reduction in the energy consumption by limiting the fluid cooling need.


• Energy saving higher than 80%
• Need of fluid cooling extremely reduced
• Sensible reduction of noise levels
• Simplification of the hydraulic circuit with removal of flow proportional valve and sequence valve
• Increase of speed of opening and closing
• All the movements of the machine are controlled in closed loop


Colosio srl - Die Casting Machines and Accessories2017-11-18
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