The "V-LINE" injection is controlled by a closed loop system comparing actual
speed to set speed and maximum melt pressure. User selectable limits can be
easily input on the process monitor screen. Once the exact amount of material
is transferred into the injection chamber, the injection plunger that is
retracted via the melt is maintained to a set position. This design eliminates
the need for a check valve, a primary source of material degradation and shot
volume inconsistency. A linear encoder detects plunger position, and a pressure
sensor monitors injection pressure. The exceptional speed of the controller
provides real time response during injection. Melt cushion is recorded in
0.001" for accurate process stabilization.
| V-LINE TWO STAGE PLUNGER |
RECIPROCATING SCREW |
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| Metered material is pre-dose. Plunger injection is very reliable due to high
response, low mass, and low inertia plunger. High Speed, Low Speed, High
Pressure, Low Pressure, Strong Holding, quick response at VP switchover |
There is always speed and pressure loss at injection because of material
leaking. While leaking, the metered material is exposed to high shear heat, and
that generates degradation and gas. |
| High speed filling is achieved from initial stage of filling because of NO back
flow leak.
|
Material inside plasticizing barrel (Not yet metered!!) is moving along with
screw while injection. That leads to degradation of material and adding mass to
the screw injection movement.
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| INERTIA: Plunger system is inherently small and low inertia. Good at
acceleration and deceleration of speed and pressure. |
INERTIA: Reciprocating system is inherently bigger and high inertia. There is a
limit in acceleration and deceleration.
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| SPEED MONITORING: Sensor and encoder are attached to plunger, which enables
direct measurement and feedback to system. |
SPEED MONITORING: Usually data is measured from encoder at AC servomotor. Data
is indirect because there are connecting components such as ball screw and
belt.
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| PRESSURE MONITORING: Pressure sensor is attached to plunger, which enables to
detect real injection pressure and feedback to system.
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PRESSURE MONITORING: Usually data is measured from voltage of AC servomotor
(Monitoring torque at acceleration and deceleration). Injection pressure is not
equal to voltage.
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