Paper calendar rolls

An impactor can crush the muscle tissues or any part of the human anatomy. Sometimes two rotating objects can cause crushing of body parts when they are moving toward each other. Common examples include meshing gears, belts running over pulleys, cables on drums, chains on sprockets, rollers on manual type washing machines, and rolls on rubber mills or paper calendars. 

Calendar rolls—Highly polished metal rollers used to compact paper after it has dried. 

The first fully commercial continuous press was the Bison Mende calendar press (Figure 12.18.). This adopted the large diameter heated calendar rolls used in the paper industry to dry tissue papers. The heated calendar roll provided one platen . The mat was formed on a continuous steel belt that carried the mat to the calendar roll and then around the roll. Additional heated rolls applied pressure and heat to the mat at points where maximum pressure was needed. The resin cured as the mat was heated and the finished panel left the calendar roll as a continuous strip that was taken to a sawing station. The steel belt returned to the forming station. In the Mende press the panel is formed and the resin cured in contact with a curved surface. The panel is straightened by inducing a reverse curve in the panel as it leaves the press, but this limits the thickness of the panel that can be produced. Calendar diameters of 3, 4 and 5 m are used. It is claimed that 12 mm thick panel can be produced on the 5 m diameter calendar roll. In practice this type of press is rarely used to manufacture panel above 6 mm in thickness. 

After the surface-sizing section, the paper is dried again by an array of steam-heated rolls (after-drying section) to a moisture content of 6-8%. After an additional smoothing step calendar grades like e.g. office papers and packaging papers are ready for use. 

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