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
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.
Continuous | Chapter 4: Operation | 48 |
