... make a paper sheet into one corrugated paper, the Equipped with outer vacuum structure. There is a pair of corrugated rollers ... make a paper sheet into one corrugated paper, then, agglutinated with another paper sheet into one single Face cardboard. Different flutes ... is Φ260mm,made of material 48CrMo alloy metal,heat treatment with high frequency,precise grinding, surface rigidity is over HRC55-60 ...