Dual‑Zone Controlled Crown Soft Calender for Paper Mill Machine
The paper mill machine finishing section is where sheet smoothness and gloss are perfected. Our dual‑zone calender is designed to deliver exceptional surface properties for writing paper, newsprint, and cultural grades. The first nip uses a bottom controlled‑crown soft roll paired with a top heated hard roll, while the second nip reverses the arrangement with a top soft roll and bottom hard roll. This configuration allows independent optimization of each side of the sheet, eliminating two‑sidedness.
The hard rolls are alloy‑forged with 35CrMo shafts, precision‑drilled with a two‑inlet one‑return spiral pattern for uniform thermal oil circulation, maintaining a surface temperature up to 180°C with a cross‑direction variation of less than 1°C. The large 700 mm diameter creates a wide nip with low specific pressure, preserving sheet bulk while increasing heat contact time to soften surface fibers. The controlled‑crown soft rolls feature high‑performance composite covers for consistent nip pressure across the full width. Hydraulic loading with imported ATOS or HAWE proportional valves provides precise line pressure adjustment, and the integrated control system manages both heating and hydraulics from a single HMI. Automatic nip opening upon sheet break and forced air cooling protect the soft roll covers, extending service life. This paper production equipment is compact, safe, and ideal for complete paper mill lines targeting premium quality.
Technical Specifications of Our Calender
| Parameter | Value |
|---|---|
| Configuration | Two nips, controlled crown soft rolls |
| First nip | Hard roll (top) + soft roll (bottom) |
| Second nip | Soft roll (top) + hard roll (bottom) |
| Hard roll diameter | Φ700 mm, alloy forged, 35CrMo shafts |
| Hard roll surface temperature | Up to 180°C, uniformity ≤ ±1°C |
| Hard roll hardness | HSD85 ± 1 |
| Soft roll diameter | Controlled crown, Φ620 mm |
| Soft roll cover | High‑performance composite, thickness 12.5 mm |
| Cover hardness | SHRD90 ± 2° |
| Line pressure range | 20 – 160 kN/m |
| Hydraulic system | 304 SS tank (1500×3000×750 mm), 3μ filtration, HAWE valves |
| Heating system | PID‑controlled thermal oil, 190 kW (2×90 kW) |
| Operating speed | 450 – 500 m/min (design 500 m/min) |
| Dynamic balance speed | 600 m/min |
| Safety features | Automatic nip opening, forced air cooling, dual safety system |
| Roll interchangeability | Bearing housings identical for hard and soft rolls |
Zhengzhou Leizhan Technology Paper Machinery Co., Ltd. provides a complete paper mill line including this advanced dual‑zone calender. Our design ensures superior smoothness, reduced two‑sidedness, and minimal bulk loss. With integrated heating and hydraulic controls, automatic safety features, and compact footprint, it is the ideal choice for cultural paper manufacturers. Contact us to upgrade your paper processing line with this high‑performance finishing technology.
Contact: leizhanworld@gmail.com