© MOOG 2010
This document is subject to MOOG INTELLECTUAL AND PROPRIETARY INFORMATION LEGEND . The details are on page II.
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MRJ04410
This container will pass the drop test with less material as there are no heavy spots.
On average, the wall thickness will be less requiring shorter time to cool the container.
The container will have constant thickness walls.
This container will pass the drop test with less material as there are no heavy spots.
On average, the wall thickness will be less requiring shorter time to cool the container.
Programmed parison wall thickness control therefore results in higher container production rates using less
material per container and higher profits.
2-2-6.
WITH ACCUMULATOR BLOW MOLDING MACHINES
When used with accumulator machines, the DigiPackⅡcontrols the parison wall thickness relative to the
accumulator position as the plastic is being extruded. In this case the displays (LCD) vertical axis is ac-
cumulator position and the horizontal axis is die gap opening.
The total quantity or volume of plastic extruded is proportional to the accumulator position, then the re-
sulting parison wall thickness at any given point on the length f the container is related to the accumulator
position when that point on the parison was extruded through the die gap.
A potentiometer measures the accumulator position and controls the vertical axis of the program display.
The desired shape of the parison wall profile is commanded digitally by the operator using the display. The
size of the tooling opening or die gap, as measured by a die gap position transducer, is compared with the
operators commanded die gap opening as set on the DigiPackⅡdisplay.
The error between the operators commanded die gap opening and the actual position causes the ser-
vovalve to control the oil flow to the actuator and reduce the difference between the commanded and the
actual die gap opening (position error) to a very small value. This feedback process ensures that the actual
die gap opening follows the commanded die gap opening very accurately.
The operator can also set the accumulator working stroke, Shot Size, and the desired position at the end of
the accumulator push out, Cushion, the DigiPackⅡalso provides interfacing signals for these functions with
the machines PLC, which then controls the motions of the accumulator.
2-2-7.
WITH CONTINUOUS BLOW MOLDING MACHINES
When used with continuous blow molding machines, the DigiPackⅡcontrols the parison wall thickness
relative to time required for one complete machine cycle. The displays (LCD) vertical axis is time and the
horizontal axis is die gap opening. The cycle starts when the parison cut off knife cuts through the parison.
Cycle end may be determined by a) the end of a fixed, operator set cycle time, b)the end of a time, auto-
matic cycle time, calculate by repeated measurement of the times between parison knife cuts (the blow
molding machine controls the cycle time) or c) sensing the end of a fixed time cycle and initiating a machine
function such as closing the mold (the DigiPackⅡ controls the cycle time).
