Sheet manufacturing apparatus

Abstract

A sheet manufacturing apparatus 1 includes: a deposition unit 50 that forms a web W; a transport belt 621 that comes into contact with an upper surface of the web W to hold the web W and transports the web W in a transport direction; a suction unit 200 that is provided above the transport belt 621 and causes the web W to be attracted and attached to the transport belt 621 by suction; a humidification unit 265 that faces the transport belt 621 and adds moisture to the web W from below; and a sheet forming unit 70 that presses the web W to form the web W into a belt-shaped sheet P 1 . The suction unit 200 includes a first duct 210 , a second duct 220 provided downstream of the first duct 210 , and a third duct 230 provided downstream of the second duct 220 . The humidification unit 265 has an outlet 265 a for discharging humidified air. The second duct 220 faces the outlet 265 a . A plurality of first suction holes 219 a and 219 b for sucking air are provided in a suction region 213 of the first duct 210 . A plurality of second suction holes 229 for sucking air are provided in a suction region 223 of the second duct 220 . Diameters of the second suction holes 229 are larger than diameters of the first suction holes 219 a and 219 b.

What is claimed is: 
     
         1 . A sheet manufacturing apparatus for manufacturing sheets from a material containing fibers, the sheet manufacturing apparatus comprising:
 a deposition unit that deposits the material by airflow to form a web;   a transport belt that comes into contact with one surface of the web to hold the web and transports the web in a transport direction;   a suction unit that is provided above the transport belt and causes the web to be attracted and attached to the transport belt by suction;   a humidification unit that faces the transport belt and adds moisture to the other surface of the web; and   a sheet forming unit that presses the web to form the web into a sheet, wherein   the suction unit includes a first duct, a second duct provided downstream of the first duct in the transport direction, and a third duct provided downstream of the second duct in the transport direction,   the humidification unit has an outlet for discharging humidified air,   the second duct faces the outlet,   a plurality of first suction holes for sucking air are provided in a suction region of the first duct,   a plurality of second suction holes for sucking air are provided in a suction region of the second duct, and   diameters of the second suction holes are larger than diameters of the first suction holes.   
     
     
         2 . The sheet manufacturing apparatus according to  claim 1 , wherein
 the suction region of the first duct includes an upstream suction region and a downstream suction region located downstream of the upstream suction region in the transport direction, and   among the plurality of first suction holes, diameters of the first suction holes formed in the upstream suction region are larger than diameters of the first suction holes formed in the downstream suction region.   
     
     
         3 . The sheet manufacturing apparatus according to  claim 2 , wherein
 a partition wall is provided between the upstream suction region and the downstream suction region.