Fort Smith, AR, May 11, 2005 --- An advanced linear motor system from Baldor Electric Company (NYSE:BEZ) is powering Supreme Plastics' revolutionary new zipper applicator for continuous vertical form-fill-seal and horizontal flow-wrapping equipment. Two zip attachment heads running along the same magnet track allow the new Reseal 460X machine to achieve throughputs of up to 120 pouches/minute, providing a breakthrough in food packaging technology. Reseal 460X applies Supreme Plastics 7mm zippers across the web - typically the shortest edge of the pouch - saving material and allowing a higher fill ratio. The technique also eliminates "leakers" at critical points because the zipper closure does not form part of a side weld. The system can be retrofitted to existing equipment, or built into new form-fill-seal machinery, providing an easy means of upgrading food packaging processes to new consumer-friendly resealable formats.To support continuous manufacturing, the machine uses a zip feed mechanism driven by a rotary servo motor, which is mounted on a fast-accelerating linear motor axis that tracks the speed of the plastic web. It then seals the zipper into place using a heating element. For high throughput, two of these attachment heads travel - a pouch length apart - on the same linear magnet track. The track itself is around a meter in length, to provide great flexibility of pouch size. In operation, the linear stage, which is based on a cog-free brushless motor for smooth operation, carries two forcers - each with a zip feeder and heating element. The forcers sit on a home position until the controller senses the next registration mark. They then accelerate rapidly, and when synchronized with the web, the heating element is switched on to seal the zips into place. The forcers then accelerate back to the home position at over 1G in readiness for the next application cycle. The machine's four axes of motion (two rotary BSM servomotors and two forcers on the LSS linear stage) are controlled by a Baldor NextMove BX motion controller and four FlexDrive servo drives. This controller also incorporates the I/O required for the various sensing and actuation functions associated with the process, such as registration mark detection and zip position sensor. Using CANopen fieldbus communications, the motion control system links to a Baldor operator panel which allows the operator to define zip length, pouch size, etc. Baldor provides all motion, I/O and human-machine interface system components required for the new machine, and wrote the application software using the popular Mint motion language. Development time was greatly reduced by means of Mint's built-in multi-tasking operating system. Baldor used this feature to divide the major control functions of the machine - controlling the zip feed, linear motor and man-machine interface as separate tasks. The availability of application-level software in the form of 'keywords' within the Mint language contributed significantly to fast software creation. For example, a single keyword allowed Baldor to correlate the linear motor heating element axis to the web material - so that the applicator automatically tracks the web. The motion control element of the new machinery was developed for Supreme Plastics by Baldor's Applications Engineer Stuart Bratton who notes: "The use of a multiple forcer arrangement on a single linear motor platen means that this machine has very simple mechanics, greatly aiding reliability and maintainability. It also provides an architecture that can be easily upgraded if higher speeds are required. Another zip attach head may be added simply by lengthening the track and running another forcer element, which would increase throughput with minimal impact on the mechanical system". For more information visit www.baldor.com.
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