Movacolor MC-BALANCE, Руководство пользователя

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MC-Balance manual 38
8. System performance
System performance can be characterized by the time it takes the unit to reach the desired set
point, the accuracy of the set point and the regularity of the material output.
The algorithm is self-adjusting to the conditions and because the conditions vary, it cannot be
predicted how long it will take the unit to adjust itself and reach a set point with certain accuracy.
The following variables influence system performance:
Material properties. Easy flowing, non-sticky and non-static material that comes in the form of small
granules or powder can be dosed very accurate and regular. The accuracy and regularity of
material output drops with increased granule size. However this is only a problem with extreme low
outputs.
Periodical cleaning of the dosing cylinder and seals is necessary for proper operation.
Extreme vibrations and shocks influence system performance noticeably. Normally the system will
be able to compensate for vibrations and shocks.
The MC-Balance algorithm needs a certain time to weigh material loss and adjust the RPM
accordingly. This time depends largely on the set point and the above mentioned two variables.
The system constantly adjusts itself to reach the best possible accuracy for current conditions.
Over time it can reach an accuracy within
±
1%.
Under “normal” circumstances the unit will be more accurate than 10% after the first adjustment of
the RPM.
Before the unit makes its first RPM adjustment it might be running already very close to the desired
set point because it uses a cylinder and material reference system to determine the first RPM
setting. This accuracy however can not be guaranteed because material properties can vary
substantially from material to material.
With injection molding the shot to shot accuracy depends, besides the variables mentioned so far,
on the shot time. If big and heavy granules have to be dosed in a very short time this will influence
the shot accuracy and repeatability because one granule can make a difference of a few percent to
the shot weight.
An unstable relay or tacho signal has a negative effect on the accuracy, repeatability and speed of
the system because it will adjust to these parameter changes.
A long cycle time combined with low dosage per shot can result in a slow system.
8.1 Reset regulation
•
Changing one parameter during production will cause the balance to adjust to the changes
but it will not reset the regulation totally.
•
Changing more production parameters during production within 10 seconds after each
other will cause the Balance regulation to reset. This is necessary for the system to adjust
quickly to these big changes in the settings.
•
Switching the power OFF and ON again will also cause the regulation to reset.
•
Motor OFF and ON again will only cause the regulation to pause. The start up RPM will be
the same as the last RPM before the stop.
•
Changing one parameter with motor OFF causes total reset of the regulation.
•
With auto start = ON (CONFIGURATION <menu>) the motor follows the last status (motor
Standby or motor Stop status) and causes total reset of the regulation.