To prevent a water permeable sheet from shifting or developing wrinkles by a method wherein the water permeable sheet is gradually and wavily boarded along a suction surface from the middle part of the sheet to its side edge sides.
Three sets of roll groups 7a, 7b and 7c are provided so as to vertically pinch a water permeable sheet 2. The first roll group 7a consists of an upper side roll 71 having one ring-like boarding part 71a and a lower side roll 72 having two ring-like boarding parts 72a apart from each other at an interval of one pitch of the wave form of a suction surface so as to wavily board only the middle part of the water permeable sheet 2. Next, the second roll group 7b wavily boards the middle part and the left and the right part respectively apart from the middle part by one pitch of the water permeable sheet 2. Similarly, the third roll group 7c wavily boards the middle part and the left and the right parts respectively apart from the middle part by two pitches of the water permeable sheet 2. In other words, the boarding is executed from the middle part gradually toward outsides of the sheet, resulting in allowing to prevent the water permeable sheet from shifting or developing wrinkles.
KAWAGUCHI TAKESHI
YAMAOKA SHUJI
Next Patent: MANUFACTURE OF PC PANEL HAVING RIGHT-ANGLED CROSSING PART