Soft Calender for Paper Machines

The soft calender is typically installed at the end of the paper machine (PM) line before the reel. It is designed for one-sided or both-sided glazing of paper webs, suitable for producing fancy and graphic papers. A steam box is often installed before the calender to enhance the smoothness of the paper surface.

Design Features

Configurations:

• Four-Roll Two-NIP Press: Provides two NIPs for efficient glazing.
• Double-NIP with Three Rolls: Also provides two NIPs for effective glazing.

NIP Combinations:

• An oil-heated thermo roll paired with a swimming S-roll.
• The S-roll features continuously adjustable bending based on the applied load.

One-Sided Web Glazing:

• Both rolls are positioned either up or down, depending on the side being glazed.

Double-Sided Web Glazing:

• The thermo roll is placed up in the first NIP and down in the second NIP.

Roll Features:

• Each roll is equipped with a swinging doctor for cleaning.
• Swimming roll edges are monitored by thermocameras, providing signals for cooling surfaces to maintain constant temperatures and extend roll cover life.
• Spreader rolls before each pressing zone ensure optimal transverse tension of the paper web.

Main Parts

1. Supporting Structure (1):

   • Structural steel design to minimize operating vibrations.
   • Stands are bolted together and designed for safe handling during installation.

2. Thermo-Roll (2):

   • Can be heated up to 180°C.
   • Surface protected with a special cover for optimal paper web smoothness.
   • Bearings are lubricated through a central lubrication system.

3. S-Roll (Swimming Roll) (3):

   • Coated and powered by toothed belts.
   • Pinion bedded in a bearing body with spherical roller bearings.

4. Swinging Doctors (4):

   • For surface cleaning of thermo-rolls and floating rolls.
   • Provide oscillating motion to improve doctoring and prevent roll surface damage.

5. Roll Edge Cooling System (5):

   • Cools S-roll edges to maintain uniform temperatures.
   • Includes fans, water cooler, and distribution piping with air nozzles controlled by pneumatic cylinders.

6. Temperature Measuring Elements (6):

   • Thermo-cameras monitor the S-roll cover temperatures.

7. Spreader Roll (7):

   • Stretches the paper web in the cross direction before the pressing zone.
   • Deflection adjusted by a worm gear.

8. Web Guiding Roll with Bedding (8):

   • Guides the paper web from the first NIP to the spreader roll.
   • Chrome-plated surface with up to 80 μm thickness.

9. Web Tension Sensing System:

   • Tensometric sensors evaluate and adjust web tension.

10. Machine Covers (9):

    • Protect the machine components.

Accessories

• Air Distribution Elements with Fan for Roll Edge Cooling.
• Heating Station for Thermo Rolls.
• Soft Calender Drive and Steam Box.

Scope of Delivery

• Machine as per the main parts description.
• Optional accessories based on customer requirements.

Advantages

• Easy Installation and Assembly: Designed for straightforward setup.
• Simple Routine Maintenance: Facilitates regular maintenance with minimal downtime.

The soft calender ensures high-quality glazing of paper webs, enhancing the final product’s surface quality. It is designed for easy installation, reliable operation, and efficient maintenance, making it an essential component in the paper production process.