There is a set of heat roll (hard roll) and a set of rubber roll with controllable crown in each nip. Through the hot pressing 

ironing effect in the pressure area, the smoothness where the paper sheet contacts the heat roller increases greatly, meanwhile 

the tiny impurities in the paper sheet is not easy to be crushed, which effectively guarantee the quality of paper sheet. Through 

the controllable crown roller, the line pressure in full width direction of the paper can stay the same.