1328 Azalea Garden Rd.
Norfolk VA. 23502
Date: February 2002
Contact: (customerservice [at] bauercomp [dot] com)
This information bulletin affects - NCU2 2002
To put the NCU2 into operation, the following connections will have to be made:
1) Power_ the NCU 2 is available for 120-240 VAC power. As shipped from the factory, it will plug into a standard 120 VAC receptacle.
2) Pressure- The Inlet port should be connected to a source of Nitrogen at a pressure that is at least 500 psi higher than that to be programmed as a maximum outlet pressure not to exceed 6000 psi (input port 1/4 inch NPTF)
3) Outlet Connections the outlet of each channel to be used to a mold vent valve (bci part # VCV-0002) mounted to your injection machine. (outlet ports 1/4 NPTF)
4) Input signals Interface with the press through the 24 pin connector as per Interface info for new systems 2002
When the NCU is powered up, the first screen to be displayed will be the Channel 1 profile screen. This screen consists of the following:
Channel selection buttons - switch main screens from the Channel one to Channel two profile screens. The if the current screen is channel 1 then the channel 1 selection button will be iluminated
Monitor- Switches to monitor screen
Pressure Gage- indicates current actual pressure for channel displayed
Save/Load - Swithes to the Save and load screen
Input Status Indicators
Cycle Start- displays status of cycle start input (Channel 1 pin #'s 1+13), (Channel 2 pin #'s 6+18) note: this input will start a cycle by closing momentarily or by closing and keep it closed for the length of cycle
Cycle Kill- closing this input shuts down and depressurizes a cycle in progress or prevents a (channel1 pin #'s 2+14),(channel2 pin #'s 7+19).
Mold- indicates whether the mold switch is open or closed. It should be noted that the auto purge feature will allow gas to flow to the mold while open if set up. (channel 1 pin #'s 3+15) (channel 2 pin #'s 8+20)
Safeties - all press safety switches should be wired in series through this input. If this input is not on, no cycles or purging can take place (channel1 pin #'s 4+16) (Channel 2 pin #'s 9+21)
Cycle - This indicates whether a pressure profile is currently being run.
Dissabled/enabled- This text display indicates whether the enable/ dissable input is closed for each channel (channel1 pin #'s 5+17) (channel 2 pin #'s 10+22)
Profile pressure,time and ramp inputs-touching each one of the numerical displays will open the numerical keypad that can be used to enter a value. see creating a profile
Profile name - Touching this text input will give the user the cabability to name the profile (max. sixteen Characters). This name will be used to store or retrieve the profiles from storage.
Arm/Dissarm System- When power is cycled to the system, the controller will be placed in a dissarmed state ( will not supply gas on either channel). Touching this button will change the state of the controller. (Armed to Dissarmed or Dissarmed to Armed).
The automatic purge feature of the NCU2 provides for the periodic venting of the gas ports in the mold unit in order to blow out any contaminents. This proccess functions by counting the number of gas cycles the controller has performed and comparing that number to the purge counter setpoint. If these numbers match the system purge will be set. The controller will then monitor the status of the mold input. Once this input is turned of, and as long as the safety input remains on, the system will start the purge delay timer. This timer will run in order to give the part extraction system time to remove the product from the mold. After the purge delay timer has expired, the system will then increase the pressure on each channel to the preset pressure. (it should be noted that when the mold porting provides little restriction to flow, the preset pressure may not be achieved.) The rate of increase to the preset pressure is controllable via the purge ramp setting (0 to 100). The purge now button allows the user to bypass the purge counter and purge delay timer and initiate a purge.
During operation, the programmable logic controller(PLC) that controls the system runs by executing its internal program instruction by instruction until complete, at which point it procceds to the top of the program and loops through the program again. One loop in the program is commonly refered to as a program scan which on average takes between 10 and 15 milliseconds. During one program scan, the PLC measures the currrent outlet gas pressure, checks the status of the system inputs, and adjusts the outlet pressure accordingly. When the system changes from one pressure to the next, the PLC measures it current scan time, and using the inputed ramp in psi per second, and the scan time in seconds per scan, calculates the increase in output pressure per scan and subsequently adds this increase to the analog output module each scan. Since the system is an electro-pnumatic device, we must keep in mind that the pnumatic side of the system will have an inherant lag (takes time for the gas to flow into the part) we find we must stop increasing the outlet pressure a few scans prior to expected in order to minimize overshoot. We must also keep in mind that this overshoot is related to the ramp requested. The higher the ramp, the greater the overshoot, however the size of the mold cavity also has an effect.
The NCU allows for fine tuning of this overshoot by allowing the seting of a system responce constant (1-10). The NCU calculates the product of this constant and the current psi per scan to produce a control deadband around the set pressure. Once the controller measures the outlet pressure to be within the control deaband, it will stop applying the ramp to the output pressure but instead change to the amount entered in the ramp deadband gain block.
Within the control deaband range, the controller calculates a second inner deadband called the setpoint deadband. The size of this deadband is dependant on the value entered in the setpoint deaband block.(note this is entered as a fraction of the main deadband from 1/1 to 1/10). When the actual outlet pressure is within the setpoint deadband, the pressure change is based on the setpoint gain value(default setting is 0 psi per scan). Entering a value into this block will cause the actual pressure inside the setpoint deaband to hunt around the setpoint. This feature should be used when the mold volume is variable during the cycle (uncommmon)
This screen alows the user to view the outlet pressure of both channels in a graphical format that shows both the main deadband and the setpoint deadbands (not shown in illustration). This screen also displays the current inlet pressure to the system and the current cycle counters (display the number of cycles since power was last cycled to the unit)
When creating a pressure profile, we must first note that every profile starts with the cycle start input closing (and the other inputs in operational state and the system armed). This action starts the start delay timer. After this timer has timed out, the system starts the first step timer and the output pressure procceeds to the set pressure listed in the pressure block of step one. How fast the system reaches this pressure is determined by the ramp in step one. Upon reaching the pressure listed in step one, the system will hold that pressure for the time remaining for step one. After the step one timer has timed out, the system will start the step two timer and procceed to the pressure listed in step two at the rate listed in the ramp for step two. This proccess will be continued until each step timer has timed out.
Using the cal-1 profile above we can see that 1.1 seconds after the cycle start is closed then system will start the step one timer and procceed to 1000 psi. It will take 1/2 second to reach this pressure at 2000 psi per second which will leave 7.5 seconds remaining on the step timer before starting the step two timer and procceding to 2000 psi. This will take one second (1000 to 2000 psi at 1000 psi per second) leaving 2.3 seconds on the step two timer before procceding to 2800 psi at 500 psi per second. After the step 3 timer (3.3 secs has timed out, the system wil then procceed to depressurize the outlet to 0 psi at 1000 psi per second which would take 2.8 seconds leaving .2 seconds before cycle end.
It should be noted that each profile should finish with a decreasing pressure down to 0 psi with the time and ramp set accordingly although not all steps must be used.
If insufficient time is alloted to reach the set pressure (at the ramp given) or insufficient ramp is given to reach the set pressure in the alloted time, the step will time out before reaching the set pressure and will go on to the next step. For example, if the first step is listed as 2500 psi 3 seconds and 500 psi per second ramp, after the 3 seconds has expired the actual pressure would have reached only 1500 psi (3 X 500) at which point the system will move on the the next step.
The system has been alloted ten slots for the saving of pressure profiles. Each slot can hold the profiles for channel one and channel two. When saving and loading profiles, the operator touches the button (1 through 10) to select the slot to be used. When a button is pressed, the "Selected Slot" indicator will confirm the selection.
Pressing the Save Profile button will open a window that will give the user the following choises:
Save Channel one Only-Saves Channel one settings to slot selected
Save Channel two Only-Saves Channel two settings to slot selected
Save both Channels-Saves both channel settings to slot selected
Pressing the Load Profile button will open a window that will give the user the following choises:
Load Channel one Only-Loads Channel one settings to slot selected
Load Channel two Only-Loads Channel two settings to slot selected
Load both Channels-Loads both Channel settings to slot selected
When using the controller to assist two molding units, the operator can save and load only the channel being used. It should be noted that saving or loading of profiles cannot take place wile a cycle is operating.