Chocolate bar flow-wrapping machine

Source: CAN Newsletter March 2002

Cadbury uses the flow-wrapping machine from Premier Packaging for packaging Dairy Milk bars. The project was extremely time sensitive, and Premier Packaging refurbished the machines in around four months, and imposed an even tighter schedule on its sub-contractors Baldor supplying CAN-connectable motion controllers. The motion control subsystem transfers and cartons the flow-wrapped chocolate bars. Three servo motor axes are employed for this. One controls a 'paddle' which sweeps bars through 90° into a flighted conveyor. Two further axes collate bars into groups on a feed-chain, and then actuate paddles, which transfer the group into a 'lowerator' – simultaneously moving the lowerator on a step for depositing the group into a carton. NextMove-BX motion controllers control the system. Development time was greatly reduced by means of Mint's multi-tasking capability. Baldor used this feature to divide the transfer and cartoning process into five separate tasks: start and stop paddles (for rejects), feed conveyor belts, decrease lowerator, and manage the human machine interface. Several application engineers working in parallel implemented a software prototype in less than a week. This design was then optimized and integrated with the hardware - including three brush-less AC servo motors, three Flex drives, a motion controller and various sensors - and delivered to Premier Packaging for commissioning.

"Mint's multi-tasking trimmed several weeks development time off this project," said Stuart Bratton, Project Engineer for Baldor. "The asynchronous aspects of the axes on this process would have made it quite a complex problem to deal with using traditional software techniques. This kind of software advance is key to reducing the time to market for complex projects, as OEMs build more and more features into their machinery." He also noted that the motion controller's built in I/O and CAN communication allowed the device to provide a complete solution, including the user interface and the inputs and outputs needed for the various sensing tasks. In this instance, one of the controller's dual CAN ports is used to interface to a remote man-machine interface panel using the CANopen protocol.