INTRODUCTION

The AS machine is a uniform, automatic carton sealer. It plays an important role in automation.  

OPERATION

• Purpose: The A-series (AS/AQ) facilitates smooth cycling in high-volume production lines with irregular flow patterns. Automatic Jam Detection is crucial to minimize waste and initiate speedy fault recovery after carton Jam by providing a break between boxes to allow easier carton removal. Jam Faults can be triggered several different ways.

OBSERVATION

Jam Fault Detection is a function of the BP-PLC as it monitors the sensor inputs, specifically the zone photo eyes (PH1, PH2, and PH3) which initiate Kicking/folding, taping bottom, and taping top.

• The jam fault occurs as the box is exiting.
  • If box takes too long to exit, a jam fault is triggered. A box that enters the machine (Leading edge of PH1) has approximately 3 seconds to exit the machine (trailing edge of PH3).
    • Jam fault timer maybe adjusted differently for different belt speeds and box weights.
    • Generally, 3-5 seconds is sufficient.
    • A box exiting event should reset the jam timer. 
• The jam fault is seemingly random.
  • If more boxes 'enter' then 'exit', the jam timer doesn't reset, because the PLC thinks the machine is active. . The program logic tracks the number of boxes (and each one's current activity) in the machine, which can be up to 3 instances. Each leading-edge transition increments a counter for the current zone and decrements the counter for the previous zone. For example, a box entering Top Seal Zone (leading edge of PH3) increments the top sealing zone while decrementing the bottom sealing zone. 
  • If more state changes are generated by PH2 than by PH3 (maybe a wobbly sensor bracket or poorly aligned PH2), the PLC will count 2 or 3 boxes in the machine, but only one is registered exiting (or exited) by the exit sensor PH3.
• Jam fault on box entry.
  • Blocked zone photo eye will trigger a jam fault when a box enters. The Program Logic expects the zone photo eyes (PH1, PH2, and PH3) to be normally clear when there is no box in the machine. The sensor indicators should be solid green LED - NO Amber LED.
    • If the machine starts and one of the zone photo eyes is blocked, the machine will attempt to clear the box (or boxes) before tape monitoring begins. So, the belts will turn on for a few seconds before the green light on the Stack light illuminates, which indicates that tape monitoring is active.
      
    • Noticing this behavior can indicate if a sensor is bad or out of adjustment.  If there is a delay (1-3 seconds) between starting the machine and the Green Light turning ON (Upstream interlock will also be delayed), then there is probably a blocked or misaligned sensor. 

PROCEDURE

1. Clear the machine, then Stop the machine. 
   
   ***IMPORTANT NOTES***
   * Use small screwdriver to make sensor adjustments,
   * Only use very, gentle force to turn the dials
   * The dials only turn about 270* - DO NOT TRY to SPIN a 360, or they will be damaged. 
   
   
2. Check for Sensor alignment and mounting for zone sensors- PH1, PH2, PH3.  (Sensor indicator LEDs should be solid GREEN, no amber)
   * Sensor should be securely mounted to bracket.
   * Bracket should be securely mounted to the frame. 
   * Sensor must be aligned with reflector (Reflector must be intact) and adjusted to within range of detection.
   * Flag the sensor to verify that it registers an object has blocked the beam. The AMBER output LED indicator should turn ON when the sensor is flagged or blocked.
3. Verify sensor mode is functioning as expected for the program logic to work correctly.
   * If the sensor is output is ON when the sensor is clear and OFF when blocked, try changing Light-ON/Dark-ON mode. Normally the sensor should be set to Light-ON or 'L'. If Sensor works correctly in Dark-ON, consider replacing the sensor. 
4. Using a Voltmeter, test the output of the sensor to verify it functions correctly.
   * Sensor is NPN.
   * Sensor Output should measure HIGH (~24VDC), when the sensor is clear. 
   * Output should measure LOW (~0VDC), when blocked.
5. If the sensor's Green AND Amber LEDs are both flashing, then the sensor is either wired incorrectly or the output is overloaded with a short- CHECK wiring. 

CONCLUSION

Blocked, misaligned, poorly mounted, or incorrectly adjusted zone sensors are the most frequent causes of nuisance Jam faults. Damaged sensors or pinched wiring can also be the cause but generally occur less frequently.