31
4-3 Heat-Cool Control
An injection mold is required to be controlled at 120 °C to ensure a consistent quality for the parts. An oil pipe is buried in the mold.
Since plastics are injected at higher temperatures (e.g. 250 °C), the circulation oil needs to be cooled as its temperature rises.
Here is an example:
Plastics
Oil
Pump
Oil
Pump
Oil Tank
Heater
Supply
Heater
Supply
Freezer
RTD
INPT
Figure 4.3
Heat-Cool Control Example
Injection Mold
120 C
Injection Mold
120 C
The PID Heat-Cool is used for the above example. In order to achieve this, set the following parameters in the Setup
Menu:
Adjustment of CPB is related to the cooling media used. If water is used as cooling media instead of oil, the CPB is
set at 250 (%). If air is used as cooling media instead of oil, the CPB is set at 100 (%).
Adjustment of DB is dependent on the system requirements. More positive value of DB will prevent unwanted cooling
action, but will increase the temperature overshoot, while more negative value of DB will achieve less temperature
overshoot, but will increase unwanted cooling action.
Adjust SV at 120.0°C , CPB at 125 (%) and DB at -4.0 (%).
Apply Auto-tuning at 120 °C for a new system to get an optimal PID values. See Section 3-11.
INPT=PT.DN
UNIT= °C
DP= 1-DP
OUT1=REVR
O1TY=RELY
CYC1=18.0 (sec)
O1FT=BPLS
OUT2=COOL
O2TY=4-20
O2FT=BPLS
OUT2
OUT1
ETR-8100
R
OP1 OP2
OP2 ALM
MAN
AT
C
F
5,6
3
20
19
18
4
