Complementing the PLC is a Galil (Mountain View, CA) motion controller that governs, among other things, the movement of the main conveyor and the infeed of the lidstock.
Further assisting in the overall controls scheme are servo motors throughout the system. For example, servo motors from Electro-Craft (Eden Prairie, MN) drive each product-dumping hopper, while both the main conveyor and the flexible lidding infeed are powered by servo motors from Kollmorgen (Radford, VA). In each case, the servo motor has an encoder that constantly tracks the position of the motors' shafts and communicates directly with the Galil motion controller. Armed with this information, the motion controller coordinates a complex sequence of actions so that, for example, bowl index and film feed are both precisely where they're supposed to be when the heat-seal tools come down to bond the lidding to the bowl.
The motion controller also signals the blow-on labeler when to fire. Should any adjustment in label positioning be desired, new instructions can be entered on the touchscreen of the O-I control panel. The control panel can also convey changes in product or bowl size. According to MAP Systems, it's a lot easier than having to enter data in multiple places for different devices.
Ink-jet coding, too, is governed by the motion controller. "We coupled the ink-jet printer directly to the motion controller so that the print head always knows the precise speed at which its target is moving," says Jim Sanfilippo, president of MAP Systems and son of the man who heads up John B. Sanfilippo & Sons. This allows the print head to account for the acceleration and deceleration in bowl speed and adjust the rate of ink flow accordingly. If it didn't, printing would become too elongated when the bowls move quickly and too condensed when they slow down.
Mounted inside an operator interface touchscreen panel supplied by CTC Parker Automation (Milford, OH), the motion controller is connected to the Allen-Bradley PLC. The PLC gives general commands to the motion controller. In turn, the motion controller converts them to a rapid series of instructions to the servo drives that control the servo motors.
