Fully Automated Co-Extruder With Modern Controls
April 1, 2009 by Canadian Plastics
Newly opened Plastics Process Technology Group (PPTG), of Brampton, Ont., services the plastics industry by building new machinery with modern controls — and the company is turning to Omron Canada Inc. to provide innovative control platforms.
One of the key innovations in retrofitting any piece of processing machinery is to have a controller that encompasses all of the machine operations in a central control panel, and for this PPTG chose Omron’s CP1H micro PLC. In order for the operator to “see” all of the machine dynamics, a touch screen is used as a “window” into the PLC memory map. The PLC memory contains all of the I/O status as well as data communicated from VFDs, thermocouples, pressure sensors and encoders. The touch screen is able to represent the data graphically so that it is not overly complicated for the operator. One of the benefits of communicating all of the peripheral parts of the machine to the PLC is the recipe function. With recipes the operator makes one selection from a spread sheet object that automatically downloads set points, timer values, production targets and on/off selections used for various parts being manufactured.
PPTG was able to deliver a fully automated co-extruder to the market by offering the features contained in the new Omron control products, and by demonstrating the paybacks to their end customers. This particular co-extruder uses an Omron 3G3 high performance micro inverter to turn the screw. The 3G3 offers DeviceNet communications to the PLC, which provides vital information. The current that runs in the motor is monitored in real time and gives detailed information of the health of the machine (too much current at a set speed may mean a blown phase, improper plastic viscosity, etc.). The 3G3 also comes standard with an interlock device, preventing the 3G3 drive from rotating the screw until all of the temperature zones are at a minimum level.
PPTG also selected Omron’s E5ZN din rail temperature control unit, mounted to save panel space and labour. It has an advanced PID algorithm that supports auto tune and heat/cool loops. Finally, the unit offers a single DeviceNet adapter module for up to 32 zones that communicates all of the temperature data to the PLC without programming. The touch screen is thus able to report any alarms, heater burnouts instantly in addition to the recipe setting of set points and alarm set points.
The cutter/puller section of the extrusion line uses the micro PLC from Omron, CP1H. This is a low cost PLC with built in analog I/O for speed control of the puller, and a built in high-speed counter used from product measurement in the cut to length section.
THE END RESULT
The Omron team worked together to provide PPTG with the modern control system needed to automate the co-extruder, and to allow PPTG to differentiate themselves in a tough market. As a result, PPTG has gained new business at a Woodbridge, Ont. extrusion shop, outfitting all 44 lines with cutter/puller machines, and most with co-extruders.
Omron Canada Inc. (Toronto);