Calibrating the Photoelectric Tracking System (Photo Eye) of Bag Making Machine
Calibrating the photoelectric tracking system (commonly known as "photo eye") is a key step to ensure accurate pattern alignment and precise bag length.
The process mainly includes three core steps: mechanical position adjustment, sensitivity calibration, and system parameter setting.
For safe operation, always start with the machine powered off or in emergency stop status, and make sure the film has been properly threaded.
Step 1: Mechanical Position Adjustment
This step ensures the photo eye can "see" clearly.
1. Clean the lens
Wipe the lens of the photo eye gently with a clean soft cloth to remove dust, oil, or film debris.
2. Adjust height and distance
◦ Adjust the height of the photo eye to keep a proper distance from the film (recommended: 7–8 mm), ensuring the light spot projected on the film is a clear solid circle.
◦ If too high, the photo eye may fail to detect the color mark; if too low, it may scratch or damage the film.
3. Align with the color mark
Move the photo eye horizontally so the light spot is precisely aimed at the center of the color mark on the film.
Step 2: Sensitivity Calibration (Core Step)
This is the most critical part, aiming to help the photo eye accurately distinguish areas with and without color marks, usually by adjusting a potentiometer knob.
Recommended AB Midpoint Calibration Method:
1. Locate Point A (Background Area)
◦ Move the film so the light spot is on the background area outside the color mark (usually light-colored or white base).
◦ Turn the sensitivity knob fully counterclockwise (indicator usually off), then slowly clockwise until the indicator just turns on. Mark this position as Point A.
2. Locate Point B (Color Mark Area)
◦ Move the film so the light spot is on the center of the color mark (usually dark-colored).
◦ The indicator should be on. Slowly turn the knob counterclockwise until the indicator just turns off. Mark this position as Point B.
3. Set Working Point C
◦ Adjust the knob to the midpoint between A and B.
◦ Criterion: The larger the distance between A and B, the greater the color contrast and the more stable the detection.
4. Verification
Pull the film repeatedly to let the color mark pass the light spot multiple times.
The indicator should flash on–off–on–off regularly, meaning sensitivity is properly calibrated.
Simple Method:
If the above procedure is complex, use this simplified way:
Aim the light spot at the non-mark area, turn counterclockwise until the red light is off, then clockwise slightly until it turns on, and turn an extra half to one full division clockwise for better stability.
Step 3: System Parameters and Phase Fine-Tuning
After hardware setup, configure software settings on the control panel.
1. Select mode
On the interface, select "Color Mark Length Setting Mode" (usually set to 1 or 2).
2. Set bag length
The set bag length should be slightly longer than the actual color mark distance (recommended extra: 2–15 mm)
to compensate errors caused by roller slippage or material stretching.
3. Phase fine-tuning (knife alignment)
◦ Run the machine at low speed and observe the cutting position.
◦ If the knife cuts above the color mark, move the photo eye upward (or adjust phase parameters in the system).
If it cuts below, move downward.
◦ Continue until the knife cuts precisely in the middle of the color mark.
