Selected Functions
5-12
5.5 Cavity Pressure
The
cavity pressure function reads the pressure of the plastic material as it
fills the mold cavities.
5.5.1
A pressure sensor must be installed in one of the mold cavities and wired to
the appropriate T
urboPlastic module channel to provide the input signal
value. Y
ou can observe the cavity pressure value at any time by monitoring
variable 34 in the upload table.
5.5.2
Y
ou can use cavity pressure to determine the length of time to fill a cavity
.
The cavity-fill time is defined as the time it takes for the cavity pressure to
reach the cavity-fill pressure setpoint entered into the download table. Since
the fill pressure may be reached in either inject or pack-and-hold, depending
on how the profiles are programmed, the capability to make this
measurement is provided for both profiles. The cavity-fill pressure setpoint
for inject is table variable 49, and for pack is 93 in the download table.
When this value is entered, the length of time to fill a cavity during inject
can then be read from the upload table variable 30, and during
pack-and-hold from variable 31 in the upload table.
5.5.3
Also available for both inject and pack-and-hold is the peak cavity pressure
that occurred during the profile, and the cavity reading at the end of each of
the profiles. These can be read from variables 32 and 20, in the upload
table, respectively
, for inject, and variables 33 and 25, respectively
, for
pack-and-hold. Both of these values are useful in determining where to set
the transition and fill pressure setpoints.
NOTE:
A spill or surge in the system could enter as a peak value in these
locations if it is a greater value than the current value.
Bits are provided to determine whether the maximum cavity pressure to
transition is causing a profile to complete. By testing for bit 5 in words 13
and 14 of the upload table at the completion of a profile, you can determine
if the inject (word 13) or pack-and-hold (word 14) profiles completed on
cavity pressure. These bits stay in place until the next time that profile is
completed.
Y
ou can use the cavity pressure to end both the inject and pack-and-hold
cycles. The maximum cavity pressure to transition for inject is entered into
download table variable 48, and for pack-and-hold variable 91. T
o disable
this function in either profile, enter the value 32767 into the table.
Cavity Pr
essure
Sensor
Cavity Fill T
ime
Peak Cavity
Pressur
e
To Next Page
Loading...
