Sterling 600 Benutzerhandbuch

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Continuous Loss-in-Weight Blenders 
Chapter 4: Operation 
48 
The blender will blend at a maximum rate when the lower mass flow weigh hopper has a very 
low weight of material.  As the weight of material increases in the mass flow weigh hopper, the 
controller will adjust the blender feeders output to match the calculated processing machine 
rate.   The blender will adjust in so that it is running a very closely matched rate to the extruder 
and readjust the ingredient hopper outputs accordingly. 
The processing rate and the blending rate displayed on the blender control will not match 
exactly for any extended period of time as the dynamics of the extrusion process produces a 
continuously changing rate for the extruder.  The blender will follow this dynamic changing 
rate very closely.  The learned processing rate is accurate enough for mono-layer extrusion 
yield control or co-extrusion layer thickness control. 
If the extruder is slowed or stopped suddenly, the blender will reach the high weight point in 
the lower mass flow hopper, slow down, and stop the metering devices so the weigh hopper 
will not overfill.  
Manual Backup Control System 
Every continuous blender is equipped with a secondary manual backup control system.  This 
allows the blender to be switched over to manual operation.  In this mode, the feeder speeds are 
adjusted manually, and the blender will run, blending volumetrically.  The lower mass flow 
weigh hopper is equipped with a proximity sensor mounted on the upper level of the hopper.  
This is for the manual operation to cycle the metering augers if the level of material in the 
weigh hopper reaches a high level. 
This secondary control will allow the blender to be operated to provide production in the event 
of a control failure.  After correction, the blender can be switched back into automatic 
operation. 
When the blender is running in steady automatic mode, simply check the motor voltages (or) 
frequency readouts and record them.  Then the drives can simply be “dialed in” for emergency 
volumetric operation.