How to solve the problem of unstable heating temperature of bottle blowing machine caused by abnormal bottle preform transmission system?

Abnormal preform transmission system will lead to inconsistent residence time of preforms in the heating zone and uneven heating, which will cause temperature fluctuations and blow molding quality problems. The following are the troubleshooting steps and solutions for common faults in the transmission system, combined with mechanical principles and practical details:
1. Loose or worn transmission chain
Fault manifestation
The chain sag exceeds 15mm, teeth jump and jam occur during operation, and the deviation of the residence time of the preform in the heating zone is greater than 5%.
When different preforms pass through the same heating zone, the temperature difference detected by the infrared thermometer is greater than 8℃.
Troubleshooting method
Sag detection: Use a steel ruler to measure the sag distance in the middle of the chain (standard value ≤10mm).
Monitoring abnormal noise during operation: Use a stethoscope close to the sprocket bearing to determine whether there is a "click" sound (possibly chain wear or poor sprocket meshing).
Tension test: Pull the chain manually. If it is easy to pull more than 20mm, it means that the tension is insufficient.
Solution
Adjust the tensioning device:
Loosen the fixing bolts of the driven sprocket and adjust the chain tension by the tensioning screw or counterweight (refer to the figure below).
After adjustment, re-measure the droop to ensure that it is within the range of 8-10mm, and turn the sprocket by hand to check the smoothness of operation.

Replace worn parts:
If the chain elongation exceeds 3% (measure 1m chain length>1030mm) or the chain wear depth>1mm, the chain needs to be replaced as a whole. At the same time, check the wear of the sprocket tooth surface. If the tooth top becomes pointed (the standard tooth shape is an involute, which is an arc after wear), the sprocket needs to be replaced synchronously.
2. Transmission track offset or jamming
Fault manifestation
The preform tilts when running in the track, and the distance from the heating lamp is sometimes far and sometimes close, resulting in local overheating or insufficient heating.
The track entrance is misaligned with the heating box entrance, and the preform hits the heating box baffle, causing the transmission to stop.
Troubleshooting method
Track straightness detection: Use a laser collimator to scan along the entire length of the track, and the deviation should be <0.5mm/m.
Bottle blank passability test: Randomly select 5 bottle blanks and push them through the track manually. The resistance should be uniform and without jamming.
Entrance alignment check: Hang a plumb line vertically at the entrance of the heating box to observe whether the center of the bottle blank coincides with the plumb line (deviation > 2mm needs to be adjusted).
Solution
Correction of track bracket:
Loosen the track bracket fixing bolts and use gaskets to adjust the track height and levelness (set an adjustment point every 500mm).
Use a level to detect the track surface, the horizontal levelness is ≤0.2mm/m, and the vertical straightness is ≤0.5mm/m.
Optimize the track interface:
If there is a step at the track segment connection (height difference > 0.3mm), it needs to be polished smooth with fine sandpaper, or a transition guide rail (the material is selected from polytetrafluoroethylene to reduce friction resistance) needs to be installed. 3. Transmission motor and reducer failure
Failure manifestation
The motor generates abnormal heat during operation (temperature > 70°C), and the speed fluctuation causes the transmission speed to fluctuate.
The reducer makes abnormal noise (such as gear meshing noise > 85dB), the output shaft torque is insufficient, and the machine stops when the load is large.
Troubleshooting method
Speed ​​monitoring: Use a non-contact tachometer to measure the actual speed of the motor, and the deviation from the set value should be <±2%.
Vibration detection: Use a vibration meter to measure the vibration value of the motor bearing seat (axial ≤2.3mm/s, radial ≤4.5mm/s).
Torque test: Connect the torque sensor through the output shaft of the reducer, the no-load torque should be ≤10% of the rated value, and the load torque must meet the requirements of the equipment manual.
Solutions
Motor maintenance:
Clean the dust accumulated on the motor cooling fan to ensure smooth ventilation; check the wear of the carbon brush (replace when the remaining length is <1/3).
If it is a variable frequency motor, it is necessary to verify the inverter parameters (if the acceleration and deceleration time is set too short, it will cause start-stop impact), and it is recommended to set it to 5-8 seconds.
Reducer maintenance:
Replace the gear oil (use viscosity grade ISO VG 220), and the oil level should be kept at the center line of the window.
Disassemble and check the gear wear. If pitting (pit diameter > 1mm) or broken teeth occur, the gear set needs to be replaced.
IV. Abnormal bottle blank positioning fixture
Fault manifestation
The clamping force is insufficient, and the bottle blank shakes during transmission, resulting in a rotation angle deviation of > 15° during heating.
The clamp spacing is inconsistent (deviation > 2mm), and adjacent bottle blanks collide with each other, affecting the transmission stability.
Troubleshooting method
Clamping force test: Use a spring dynamometer to measure the tension when the clamp is closed, which should reach the specified value of the equipment (such as 80-100N).
Spacing measurement: Use a vernier caliper to detect the center distance of adjacent clamps, and the error must be controlled within the range of ±0.5mm.
Rotation flexibility check: Manually rotate the clamp, and it should be able to rotate 360° freely without sticking.
Solution
Adjust the clamp pressure:
Increase the clamping force by adjusting the screw or spring compression on the back of the clamp (adjust 0.5 turns each time, and test gradually until qualified).
Calibrate the clamp spacing:
Use the first tooth of the active sprocket as the reference, adjust the subsequent clamp positions in sequence, and use special positioning tooling (such as spacing templates) to ensure consistency.
Replace worn parts:
If the clamp shaft wears and causes the gap to be too large (shaking amount > 0.3mm), the wear-resistant bushing needs to be replaced (tin bronze is recommended).
V. System linkage control optimization
Synchronization problem
The transmission speed and heating power are not linked. When the transmission speed fluctuates, the heating zone does not adjust the output power in time.
The multi-stage heating zone does not set "follow-up compensation", and the front-stage transmission jams, resulting in overheating of the bottle blanks in the back stage.
Optimization plan
Speed-power linkage programming:
Add a logic module to the PLC program to associate the transmission motor speed signal (4-20mA) with the heating power output, for example:
When the speed decreases by 10%, the heating power automatically decreases by 15% to prevent the preforms from staying too long and absorbing too much heat.
Partition buffer control:
Install photoelectric sensors at the entrance and exit of the heating box. When the preform spacing is detected to be less than the set value (such as 50mm), an alarm is triggered and the transmission speed is reduced to prevent accumulation.
Maintenance cycle and record
Maintenance items Cycle Operation points
Chain tension check Daily Manually pull the chain before starting the machine to observe the change in droop
Track straightness calibration Weekly Use a laser collimator to detect and adjust the bracket
Motor bearing lubrication Monthly Add lithium-based grease (the amount of oil injection is 1/3 of the cavity)
Clamp holding force test Quarterly Randomly check 10% of the clamps, record the tension value and create a file
Transmission speed-temperature curve Annually Use a data recorder to draw a curve and analyze the correlation
Through the above mechanical adjustment, component replacement and control logic optimization, the problem of unstable heating temperature caused by abnormal transmission system can be effectively solved. In actual operation, it should be noted that after adjustment, a continuous operation test of at least 30 minutes is required to collect temperature data of more than 50 preforms (batch detection using an infrared thermal imager) to ensure that the temperature fluctuation range is controlled within ±3℃ and the circumferential temperature difference of the preform is less than 5℃ before the fault can be determined to be eliminated.