How to choose spare parts for various parts of papermaking machinery?
Paper-making machinery covers pulping, papermaking, coating, rewinding and other links, and the working environment and performance requirements of different components are significantly different, so the purchase of spare parts needs to be accurately matched according to the function and working conditions of the components. The following are the key points of purchasing core components and targeted suggestions:
1. Spare parts for key components in pulping process
Core function: crushing and pulping raw materials (such as wood and waste paper), involving high-concentration pulp, chemical corrosion and mechanical wear.
1. Pulper/refiner components
Main spare parts: blades, grinding discs, sieve plates and rotors.
Key points of purchase:
Material:
Blade/grinding blade: high chromium cast iron (Cr12MoV) or cemented carbide (YG8, for example) is used, and the surface needs laser cladding treatment (hardness ≥HRC55), so the wear life is 3-5 times longer than that of ordinary steel.
Sieve plate: 316L stainless steel+polyurethane coating is selected, and the mesh accuracy error is ≤±0.1mm (which affects the qualified rate of sizing fiber).
Adaptability: Choose the grinding blade tooth type according to the type of pulp (such as chemical pulp and mechanical pulp). For example, chemical pulp needs the loosening type grinding blade (with shallow teeth) and mechanical pulp needs the cutting type grinding blade (with deep teeth).
2. Slurry pump/impurity separation equipment
Main spare parts: impeller, shaft sleeve, seal and slag remover.
Key points of purchase:
Anti-corrosion design: the impeller is made of duplex stainless steel (such as 2205), and the surface of the shaft sleeve is plated with nickel-phosphorus alloy (thickness ≥0.1mm), which is resistant to sulfide corrosion in the slurry.
Sealing performance: silicon carbide (SiC) moving ring and graphite static ring shall be selected for mechanical seal, with pressure resistance ≥1.6MPa and leakage ≤5ml/h (to avoid shutdown caused by slurry leakage).
Second, spare parts for key components in papermaking process
Core function: Making pulp into paper requires high-precision transmission, uniform dewatering and stable operation.
1. Wire section and press section
Main spare parts: chest roll, table roll, press roll, blanket (net) and vacuum box panel.
Key points of purchase:
Roller accuracy:
Chest roll/case roll: roundness error ≤0.01mm, dynamic balance grade G2.5 (G1.0 is required for high-speed paper machines), and the surface is plated with hard chromium (thickness ≥25μm) to prevent wear.
Press roll: steam or hot oil is introduced into the interior, and the wall thickness uniformity (tolerance 1 mm) and sealing performance of the roll body need to be tested (there is no leakage when the air pressure is tested at 0.3MPa).
Blanket (net): Choose the mesh number according to the paper type, such as 360 mesh polyester net for cultural paper and 200 mesh for wrapping paper. It is necessary to verify the dewatering efficiency (such as drainage time ≤8 seconds) and service life (≥3 months).
Step 2 bake cadres
Main spare parts: drying cylinder, shaft head, sealing device and scraper.
Key points of purchase:
Dryer quality:
Material: QT450-10 ductile iron, the inner wall is mirror polished (roughness Ra≤0.8μm) to ensure the smoothness of the paper.
Pressure test: the water pressure test is 0.8MPa (working pressure is 0.5MPa), and the pressure is kept for 30 minutes without deformation.
Scraper matching: choose scraper material according to the surface hardness of drying cylinder, such as ceramic scraper (suitable for hardened chrome-plated cylinder with hardness ≥HV1000) or polyurethane scraper (suitable for ordinary cylinder with hardness of Shore A85).
Third, coating and finishing parts
Core function: surface coating and calendering paper to improve smoothness and printing performance.
1. Coating head
Main spare parts: coating roller, measuring rod, nozzle and scraper.
Key points of purchase:
Accuracy of coating roller: the roller surface runout is ≤0.005mm (for high-speed coating machine, ≤0.003mm), and the surface is coated with * * Teflon (PTFE) to prevent paint adhesion.
Specification of measuring rod: the rod diameter is selected according to the coating amount (for example, the coating amount of 30# rod is about 5g/m), the material is stainless steel+ceramic coating, and the wear resistance is ≥ 500h/time.
2. Calender
Main spare parts: calendering roller, bearing and transmission gear.
Key points of purchase:
Roller surface treatment: the surface hardness of chilled cast iron roller is more than or equal to ≥HS90, coated with ultra-hard chromium (thickness ≥50μm) or tungsten carbide, and the wear-resistant life is more than or equal to 1 year.
Gear transmission: helical hard tooth surface gear (accuracy grade 6) is adopted, the tooth surface is carburized and quenched (hardness ≥HRC58), and the noise is ≤85dB(A).
Four, transmission and power system components
Core function: provide power transmission for equipment to ensure stable operation.
1. Reducer and motor
Main spare parts: gearbox, coupling and motor bearing.
Key points of purchase:
Gear reducer matching: calculate the torque according to the speed of the paper machine (if the speed of the paper machine is 1000m/min, the output torque of the gear reducer is ≥ 5000 nm), and choose * * planetary gear reducer (transmission efficiency ≥96%)** or helical gear reducer.
Motor energy efficiency: IE4-class high-efficiency motor is preferred, with power factor ≥0.9 and temperature rise ≤80K(F-class insulation), and the energy-saving effect is improved by more than 15% compared with ordinary motor.
2. Bearing and seal
Main spare parts: rolling bearings (such as self-aligning roller bearings), sliding bearings (bearing shells) and oil seals.
Key points of purchase:
Bearing life: Select the bearing according to L10 life (90% reliability) ≥ 40,000 hours. For example, SKF 22232CC/W33 is selected for the bearing of the press roll, with sealing structure to prevent slurry from invading.
Material of bearing bush: babbitt alloy (such as ZSnSb11Cu6) or copper alloy (such as ZCuSn10Pb10), and the fit clearance between bearing bush and journal is 0.15-0.25mm (adjusted according to shaft diameter).
Five, consumable parts and common parts selection points
1. Seal (O-ring, lip seal)
Material: fluororubber (FKM) for corrosion-resistant environment, with temperature resistance of-20℃ ~ 200℃; Nitrile-butadiene rubber (NBR) used in general environment has excellent oil resistance.
Specification: the tolerance of inner diameter is ±0.3mm, and the tolerance of section diameter is ±0.05mm, which needs to be accurately matched with shaft diameter and cavity.
2. Filter screen and filter element
Type: Wedge stainless steel wire screen (seam width 0.1-0.3mm) and polyurethane screen for centrifugal screening (opening rate ≥35%) are selected for pressure screen.
Testing: A test report on flow capacity is required (e.g. pressure drop ≤0.05MPa when the flow rate is ≥ 100 m/h).
3. Bolts and fasteners
Strength grade: 12.9-grade high-strength bolts are used for key parts (such as dryer end cover bolts), the surface is galvanized to prevent corrosion, and the torque needs to be calibrated according to the design requirements (such as M30 bolt torque ≥ 2,500 nm).
Sixth, buy practical advice
1. Create a component life file.
Record the actual service life of each component (for example, the average replacement cycle of the pulper blade of a paper machine is 45 days), which provides data support for the spare parts procurement cycle.
2. Dual sources of key spare parts
For components with high downtime loss (such as dryers and reducers), we should sign framework agreements with the original factory and high-quality third parties to avoid the risk of single supplier.
3. Adopt predictive maintenance technology
Through vibration monitoring and temperature sensing, spare parts wear can be found in advance (such as early warning replacement when bearing vibration speed is ≥4.5mm/s), so as to reduce sudden failures.
Summary: Comparison of core dimensions of spare parts purchase in each link
Core performance requirements of component categories Typical material/process key inspection indicators
Wear-resistant and corrosion-resistant high chromium cast iron for pulping blade+hardness HRC and wear-resistant test of laser cladding (weight loss ≤5g/100h).
High-precision, static pressure-resistant QT450 nodular cast iron with chrome-plated surface, roundness, dynamic balance and air tightness
Coating uniformity of coated measuring rod, rod diameter tolerance of anti-adhesion stainless steel+ceramic coating, surface roughness
The transmission gear has low noise and high load. The hardness and contact accuracy of carburized and quenched tooth surface of 20CrMnTi are ≥85%.
The seal is leak-proof, resistant to dielectric fluororubber+skeleton-reinforced compression permanent deformation ≤15%, and withstand voltage test.
Through the accurate selection of parts and components, combined with supplier qualification audit and field test, the reliability of spare parts can be significantly improved, and the downtime cost and maintenance pressure of paper enterprises can be reduced. It is suggested to regularly participate in trade exhibitions (such as China International Paper Science and Technology Exhibition), track the application trend of new materials and new processes (such as the popularization of ceramic matrix composites in wear-resistant parts), and continuously optimize the spare parts procurement strategy.
