Chengdu Qingya paper is engaged in Bamboo and Bagasse pulp raw materials to produce Bamboo Jumbo rolls, Bamboo toilet paper etc control with extraordinary efficiency.
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Chengdu Qingya paper is engaged in Bamboo and Bagasse pulp raw materials to produce Bamboo Jumbo rolls, Bamboo toilet paper etc control with extraordinary efficiency.
A Comprehensive Analysis of the Convex-Convex Mark Issues in Paper Machinery
Paper surface irregularities such as concave-convex marks, streaks, and ridges are frequent defects that adversely affect first-grade yield rates and lead to batch degradation. Based on production data, this paper systematically identifies the root causes of these irregularities and proposes actionable improvement measures, facilitating comprehensive learning and implementation by all frontline personnel.
I. Where Do Convex and Concave Markings Origin From? Six Major High-Frequency Causes
1. Equipment maintenance/Hardware issues
The lip plate repair quality fails to meet standards; the smoothing roller exhibits insufficient wear/hardness; the hydraulic cylinder seal leaks oil; sensors malfunction; the machine oscillates, deviates from path, or makes sudden stops; and the gluing machine leaks adhesive.
2. The banner is unstable.
The dilution water system exhibits misalignment/oscillation, significant deviation in banner quantification/water content, abnormal edge quantification, and failure of closed-loop control.
3. Production change/Speed-up disturbance
Significant variations in tap intensity across different paper types, fluctuations in water distribution caused by pulp blending adjustments, and uneven dewatering resulting from changes in machine speed and basis weight all contribute to these issues.
4. Abnormal dehydration in the web and pressure zones
During production by Gaoke Heavy Industry, the bottom layer dosage was excessively high, the cross-section dehydration of the mesh was uneven, and the vacuum/lip plate matching was improper.
5. Impact of the Coating Application Section
Paper breakage causes fluctuations in adhesive viscosity/solid content, premature wear of the sizing roller, uneven sizing application, and abnormal bar pressure/line pressure.
6. Process parameter deviation
Excessive pre-baking moisture content, pressure fluctuations in the calender line, pressure damage caused by soft pressing, and failure to meet residual screen particle control standards.
II. Immediately可用!标准改进措施合集
1. Device Category: First-Line Treatment
· Replace the pressing roller immediately when worn; perform scheduled roller replacements according to the cycle plan to enhance the roller surface hardness.
· Repair leakage points in seals, sensors, adhesive containers, and other areas; include these inspections as mandatory items during shutdowns.
· Optimize the screening drum and vibrating screen, strictly control residual material, and reduce slurry fluctuation.
2. Banner Control: Monitor the Data Closely
· DCS focuses on monitoring the 2-sigma deviation of banner measurements, with manual intervention required in case of anomalies.
· Calibrate promptly when the dilution water deviation is significant, and optimize the side flow in the slurry tank.
· The calender operates under closed-loop control during each shift, with increased operational frequency (higher inspection and adjustment rates) when switching production lines or adjusting grammage specifications.
· Perform manual detection when thickness is abnormal and fine-tune pressure by分区.
3. Accelerate production transition: Maintain a steady pace
· Strictly control the waterline, water content, and tap density before and after production modification to avoid significant fluctuations.
· During high-capacity production, rationally allocate the bottom layer dosage to minimize banner risk.
· After paper cutting or winding, stabilize the process before accelerating production without rushing.
4. Process Section: Follow the standard procedures
· The pre-drying moisture content must be strictly controlled within the specified process range.
· Do not rinse randomly when the adhesive layer breaks, to prevent moisture from entering the adhesive system.
· Maintain stable sizing amount, roller pressure, and wire pressure, and match them with the machine speed and weight per gram.
· Increase inspection frequency to detect and address abnormalities early.
Three: Remember these six principles: roll, water, press, modify, control, and patrol.
Rollers: The smoothing roller and sizing roller are worn out; report for replacement immediately without delay.
Water: Banner moisture content and pressurization moisture content; exceeding the limits will result in defects. Pressure: Line pressure, rod pressure, and vacuum level; fluctuations will trigger an alarm.
Amendment: After adjusting production, increasing speed, and addressing paper shortages, the process must be stabilized before proceeding.
Control: DCS monitors 2-sigma; manually adjust if anomalies occur; do not rely solely on automation.
Monitoring: Check the banner curve every hour to detect issues early.
Four: Summary in one sentence
The uneven marks are not "accidental issues"; they primarily result from equipment deterioration, loss of banner control, unstable production adjustments, or process deviations. By closely monitoring the banner status, stabilizing moisture levels, replacing defective rollers, and strictly managing production adjustments, the degradation rate can be significantly reduced while steadily improving the yield of first-grade products.
