Packaging machine for resealable food
Source: CAN Newsletter Motion Control 2005
A linear motor system is powering Supreme Plastics’ 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 Reseal 460X machine to achieve throughputs of up to 120 pouches/minute. Reseal 460X applies Supreme Plastics 7-mm 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.
To support continuous manufacturing, the machine uses a zip feed mechanism driven by a rotary servo motor, which is mounted on a 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, 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 in readiness for the next application cycle.
The machine’s four axes of motion – two rotary servomotors and two forcers on the linear stage – are controlled by a motion controller and four servo drives. This controller also incorporates the I/O for the sensing and actuation functions associated with the process, such as registration mark detection and zip position sensor. Using CANopen communication, the motion control system links to an operator panel, which allows the operator to define zip length, pouch size, etc.
