Method for calendering a paper or an equivalent web material and a calender that makes use of the method

A method for calendering a web in a calender, comprising the steps of:

• arranging a variable-crown upper roll and a variable-crown lower roll in a vertical plane, each of said upper and lower rolls having a stationary roll axle, a revolving mantle spaced therefrom and loading members coupled to said roll axle for deflecting said mantle to load said roll,
• arranging intermediate rolls in a stack between said upper roll and said lower roll to form calendering nips, said intermediate rolls having auxiliary equipment connected thereto,
• passing a web to be calendered through the calendering nips,
• applying an adjustable load to the calendering nips by means of at least one of said loading members of said upper roll, said loading members of said lower roll, an externally applied load to said upper roll and an externally applied load to said lower roll, and
• relieving the load in the calendering nips produced by the mass of said intermediate rolls and auxiliary equipment connected thereto by utilizing, as said intermediate rolls, rolls in which the form of a natural deflection line produced by the weight of said rolls is substantially equal.

Calender for a web, comprising

• a frame,
• a variable-crown upper roll arranged on said frame, said upper roll having a stationary roll axle, a revolving mantle spaced therefrom and loading members connected to said roll axle for deflecting said mantle to load said upper roll,
• a variable-crown lower roll arranged on said frame, said lower roll having a stationary roll axle, a revolving mantle spaced therefrom and loading members coupled to said roll axle for deflecting said mantle to load said lower roll,
• at least two intermediate rolls arranged on said frame between said upper roll and said lower roll, said intermediate rolls having auxiliary equipment connected thereto,
• said upper roll, said lower roll and said intermediate rolls being arranged as a substantially vertical stack of rolls placed one above the other to form calendering nips with one another through which the web is passed, said intermediate rolls having substantially equal natural deflection lines produced by their own gravity,
• suspension means for suspending said intermediate rolls in the stack, said suspension means comprising relief means for relieving loads in the calendering nips produced by the mass of said intermediate rolls and the auxiliary equipment, and
• loading means for adjustably loading the calendering nips, said loading means being selected from the group consisting of a load produced by said loading members of said upper roll, a load produced by said loading members of said lower roll, an external load applied to said upper roll and an external load applied to said lower roll.