Drop Out Gate Pusher (testing completed March 11, 2003)

This design originated out re-occuring problem in AMT's modus operendi. Almost every line produced by AMT included an offline storage system allowing the blow molder to continue to produce bottles even if there is a problem with something down the line. Usually, the line is designed so that a drop out gate is used to let bottles fall out of the line onto the offline system before bottles back up through the drop gate. However many customers would change the PLC so that bottles would in fact back up through the drop gate before the drop gate would activate. The problem with this is that there is so much pressure on the bottles against each other that even if the drop gate is opened while bottles are backed up through it, the bottles will remain suspended inside the gate thus negating its usefullness.

A problem downstream causes bottles to back up on the line through the drop out gate.
The PLC detects bottles backing up through a photoeye.
The dual drop out gates [see video below] open releasing the necks of the bottles inside the drop gate.
A matter of milliseconds later the pusher activates pushing on the tops of the bottles with enough force to break the tension between the bottles so they drop out.
Once the tension is broken the pusher retracts into the plenum.
The bottles trailing the drop gate are then pushed by the line through the drop gate onto the offline system.

I was constrained by the following:

  1. AMT already had a drop out gate assembly that they wished to continue using in this design
  2. the cylinder had to be the common 3" stroke cylinder used in many other designs for ease of inventory
  3. the stroke of the pusher had to be sufficient to push a two liter bottle out of a drop out gate
  4. the pusher still had to transmit the power of the air in the plenum when it is disengaged (ie the pusher couldn't be a dead spot as far as propelling the bottles)
  5. there had to be a way to access the internal components for servicing
This design also used the Cylinder Stroke Excel Sheet to properly align the cylinder in the plenum.

CAD drawing
Movie of pusher actuating (plenum is upside down)