- Common reasons for paper breaks and countermeasures
Paper breaks in the wet section (wire section/coaster)
Reasons:
Low wet strength of pulp (too high mechanical pulp ratio, insufficient chemical pulp); Poor dehydration of the couch roll (insufficient vacuum or blocked holes); Pulp speed does not match the wire speed (too low pulp speed leads to fiber disjointment); Anionic garbage (humic acid in clean water, fungicide residues, etc.) accumulates.
Solution: Increase the proportion of chemical pulp and optimize the beating degree; Check the sealing of the couch roll and clean the blocked holes; Adjust the head of the headbox to match the pulp speed with the wire speed; Strengthen the control of white water filtration and clean water addition.
Paper breaks in the press section
Reasons: Press roll/felt contamination (resin, glue adhesion); Poor dehydration of the felt or local wear; Insufficient vacuum or improper angle of the vacuum suction roller; Excessive moisture or uneven quantitative paper entering the press. Solution:
Clean the scraper of the press roller and replace the felt regularly;
Calibrate the parameters of the vacuum suction roller and adjust the angle of the vacuum chamber;
Control the moisture content of the paper before pressing (≤62%).
Tension control system failure
Cause:
Tension sensor failure or parameter drift;
Excessive fluctuation of the floating roller (wear of the brake friction pad/potentiometer failure);
Improper setting of the acceleration pressure when splicing.
Solution:
Calibrate the tension sensor and check the line stability;
Replace the brake friction pad and adjust the zero position of the potentiometer;
Optimize the acceleration pressure and clutch air pressure when splicing.
Paper roll quality problem
Cause:
Impact damage or internal cracks on the edge of the paper roll;
Sudden tension changes caused by wrinkled paper web.
Solution:
Strengthen the quality inspection of the base paper roll to avoid transportation damage;
Control the amount of printing ink to prevent the strength of the paper from decreasing.
II. Systematic improvement suggestions
Equipment maintenance
Clean the filter and white water recovery device regularly to ensure stable concentration;
Check the angle of the drive roller to prevent slipping and flying.
Operation specification
The damaged paper needs to be screened and measured before reuse to avoid concentration fluctuations;
Check the sensitivity of the photoelectric signal before splicing to ensure that the automatic splicing program is triggered.
Process optimization
Control the amount of clean water added to reduce the accumulation of anionic garbage;
Use a direct tension control system (applicable to high-speed paper machines) to adjust the paper tension in real time.
Key tips:
Continuous paper breaks: A single paper break may result in a production loss of 4.5 tons (at a speed of 230m/min), with a direct cost of nearly 7,000 yuan;
Priority inspection points: Tension control stability > Press roller/felt status > Pulp ratio and dehydration efficiency.
Appendix: Emergency processing flow: Paper break → Stop → Check transmission components/sensors → Clean key roller surfaces → Calibrate tension parameters → Gradually increase speed for verification.