Providing automatic, 100% validation that the correct material is being conveyed to the right destination, a new, patent-pending machine-vision proofing system has been developed for use with the Conair Resin Selection Station. This is believed to be the first time machine vision has been used in this type of application, although the technology is well accepted in many other manufacturing situations. Despite its “high-tech” appearance, this new Conair innovation is actually simpler and less costly than other approaches to eliminating operator error and preventing material contamination in automated material-handling systems.
Dubbed Material Vision Proofing (MVP), the new vision system includes a motorized camera installed on a track behind a standard Conair table-top manifold that supplies up to 6 different source materials to up to 36 destination outlets on top of the table. Flexible hoses, descending from above, provide the conduit for resin to be vacuum conveyed to any machine, blender, dryer or other destination that needs it. When setting up a job, an operator designates the source and destination in the material-handling system control and then manually connects the appropriate flexible hose to the proper outlet ports, via a push-fit connector.
“This is where mistakes can happen using a system without validation,” says Matthew Baker, Mechanical Engineer, Conair. “It is only as good and only as accurate as the operator making the manual connections. If the wrong connection is made, valuable material and production time is lost trying to purge contaminated resin from the conveying lines and destination equipment. With the new MVP system, however, these costly errors are eliminated. This system is ideal for companies who need 100% process validation. All the data generated by the system can be saved for recall any time.”
The various resin sources and destinations are programmed into the material-handling system control. Both Conair’s large-scale ELS system and the smaller, flexible FLX control are compatible and connect via Ethernet to the vision system. In operation, the control will indicate to the operator exactly where the hose connection needs to be made. Then, before any resin is conveyed, the machine-vision camera will traverse behind the selector table and position itself between the appropriate rows of ports, confirming to the material handling system control that the correct connections have been made. So it can operate effectively in low-light even lights-out plant conditions, the machine vision camera is tuned to the infrared spectrum. It includes an integral infrared light source and the barcode labels on the ports and hose connectors are infrared-sensitive.
When and only when the camera has verified the connections, the control will allow material to be conveyed. The entire validation process takes just seconds to complete. As long as the same program is being run, the camera then will periodically confirm that changes have not made.
Machine vision is well established technology, commonly used in such applications as robotic assembly, where vision will be used to confirm the presence and correct placement of various components. The camera “sees” the objects in front of it and the control system intelligence compares that image with a stored image corresponding to the situation that is supposed to exist – in the case of the Conair resin selector, that Source A is correctly connected to Destination X. If there is no mismatch, the material-handling system can begin conveying. If not, conveying will not start and an alarm is sounded so that the mismatch can be corrected.
“There have been attempts to use wireless and non-contact proofing before,” notes Conair’s Baker, “but with plastic pellets flowing through the various hoses, you have a significant static-electric build up that can disrupt communications. Other companies have tried to use bar-code and RFID systems but these require multiple readers and can be very expensive. The new Conair machine vision system is less costly and much easier to set up and operate.”
With the new Conair system, there is one camera, the motorized actuator, a small PLC control and a single Ethernet communications cable that connects the PLC to the material handling control system. With an optional extended, belt-driven actuator, one camera can monitor two full resin-selector stations positioned side by side to handle up to 12 sources and up to 72 destinations. The vision system is available as an option on new installations or it can be retrofit to selection stations already in the field.
The Conair Group (www.conairgroup.com) is the world’s leading supplier of auxiliary equipment for plastics processors, including resin drying systems, blenders, feeders and material-conveying systems, temperature-control equipment and granulators. Extrusion solutions include line-control systems, film and sheet scrap-reclaim systems and downstream equipment for pipe and profile extrusion. Over 450 individual products solve problems, save energy, cut waste and are easy to use. Conair is also an international company, with long-standing operations in Europe, Asia and South America. The industry’s most complete product line, top-flight engineering and unbeatable service, all combine to give processors the confidence they need to succeed in today’s competitive global marketplace.