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 P1. 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 265a for discharging humidified air. The second duct 220 faces the outlet 265a. A plurality of first suction holes 219a and 219b 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 219a and 219b.

Claims

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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a schematic view illustrating the configuration of a sheet manufacturing apparatus according to an embodiment.

[0007] FIG. 2 is a schematic view illustrating a detailed configuration of a suction unit.

[0008] FIG. 3 is a perspective view illustrating an arrangement of pipes connected to suction fans.

[0009] FIG. 4 is a plan view illustrating the configuration of a plate member.

[0010] FIG. 5 is a cross-sectional view taken along line V-V in FIG. 4, for explaining the functions of first suction holes and partition walls.

DESCRIPTION OF EMBODIMENTS

[0011] In the following embodiment, as an example of a sheet manufacturing apparatus of the present disclosure, a sheet manufacturing apparatus 1 that recycles waste paper or the like into sheets in a dry manner is shown. Hereinafter, the sheet manufacturing apparatus 1 will be described with reference to the drawings. The sheet manufacturing apparatus of the present disclosure is not limited to a dry type, and may be a wet type. In the present specification, the term dry type refers to recycling performed in air such as the atmosphere instead of in liquid.

[0012] In each of the following figures, X-, Y-, and Z-axes are indicated as coordinate axes orthogonal to each other. The direction indicated by each arrow is defined as the + direction, and the direction opposite to the + direction is defined as the direction. The Z-axis is an imaginary axis parallel to the vertical direction. The +Z direction is the upward direction, and the Z direction is the downward direction. The Z direction is the downward vertical direction. In the sheet manufacturing apparatus 1, the side in the transport direction of the material, a web, sheets, and the like is referred to as downstream, and the side in the direction opposite to the transport direction is referred to as upstream. For convenience of illustration, the size of each member is different from the actual size.

[0013] As illustrated in FIG. 1, the sheet manufacturing apparatus 1 according to the present embodiment includes a first unit group 101, a second unit group 102, and a third unit group 103. The first unit group 101, the second unit group 102, and the third unit group 103 are supported by a frame (not illustrated). In FIG. 1, the directions in which paper pieces C, sheets P3, slit pieces S, unnecessary scraps, and the like move are indicated by the white arrows. In the following description, aggregates of paper pieces C are also simply referred to as paper pieces C.

[0014] The sheet manufacturing apparatus 1 manufactures sheets P3 from paper pieces C that are a material containing fibers such as used paper. In the sheet manufacturing apparatus 1, the first unit group 101, the third unit group 103, and the second unit group 102 are arranged from the Y direction toward the +Y direction in side view from the X direction.

[0015] Paper pieces C are transported from the first unit group 101 to the second unit group 102 through a pipe 21 passing through the inside of the third unit group 103. The paper pieces C are then subjected to defibration and the like in the second unit group 102 and formed into a defibrated material, which is aggregates of fibers, and a binder or the like is added to the defibrated material. The defibrated material is transported to the third unit group 103 through a pipe 24. The defibrated material is formed into a web W in the third unit group 103, and then the web W is formed into a belt-shaped sheet P1. The belt-shaped sheet P1 is cut into sheets P3 in the first unit group 101.

[0016] The first unit group 101 includes a buffer tank 13, a fixed-quantity supply unit 15, a merging unit 17, and the pipe 21. In the first unit group 101, these components are arranged in this order from upstream to downstream. The first unit group 101 also includes a first cutting unit 81, a second cutting unit 82, a tray 84, and a shredding unit 86.

[0017] In addition, a sheet transport unit 63 is disposed to extend from the third unit group 103 to the first unit group 101. The sheet transport unit 63 transports the belt-shaped sheet P1, cut sheets P2, sheets P3, and slit pieces S. The first cutting unit 81 and the second cutting unit 82 cut the belt-shaped sheet P1 into the sheets P3 having a predetermined shape.

[0018] The first unit group 101 also includes a water supply tank 267. The water supply tank 267 is a water storage tank. The water supply tank 267 supplies water for humidification to each of a humidification unit 265 and a humidification device 266, which will be described later, through a hose or the like (not illustrated). Pure water, tap water, or the like can be used as the water stored in the water supply tank 267. The humidification device 266 is an example of a humidification device of the present disclosure.

[0019] Paper pieces C are input through a raw material input port 11 to the buffer tank 13. The paper pieces C contain fibers such as cellulose and are, for example, shredded used paper. Humidified air is supplied to the inside of the buffer tank 13 from the humidification device 266 provided in the third unit group 103. Thus, the paper pieces C are not easily charged, and adsorption between the paper pieces C can be reduced.

[0020] The paper pieces C to be defibrated are temporarily stored in the buffer tank 13 and is then transported to the fixed-quantity supply unit 15 according to the operation of the sheet manufacturing apparatus 1. The sheet manufacturing apparatus 1 may include a shredder located upstream of the buffer tank 13 and configured to shred the paper pieces C and the like.

[0021] The fixed-quantity supply unit 15 includes a weighing device 15a and a supply mechanism (not illustrated). The weighing device 15a weighs the mass of paper pieces C. The supply mechanism supplies the paper pieces C weighed by the weighing device 15a to the merging unit 17 located downstream. Specifically, in the fixed-quantity supply unit 15, every time the weighing device 15a weighs out a specified mass of paper pieces C, the supply mechanism supplies it to the downstream merging unit 17.

[0022] Both digital and analog weighing mechanisms can be used as the weighing device 15a. Specific examples of the weighing device 15a include a physical sensor such as a load cell, a spring scale, and a balance. In the present embodiment, a load cell is used as the weighing device 15a. The predetermined mass of paper pieces C weighed by the weighing device 15a is, for example, approximately several grams to several tens of grams.

[0023] A known technique such as a vibration feeder can be used as the supply mechanism. The supply mechanism may be included in the weighing device 15a.

[0024] The weighing and supplying of paper pieces C in the fixed-quantity supply unit 15 are batch processes.

[0025] Specifically, the paper pieces C are intermittently supplied from the fixed-quantity supply unit 15 to the merging unit 17. The fixed-quantity supply unit 15 may include a plurality of weighing devices 15a, and the plurality of weighing devices 15a may be operated at different times to improve the weighing efficiency.

[0026] In the merging unit 17, shredded pieces of slit pieces S supplied from the shredding unit 86 are merged and mixed with the paper pieces C supplied from the fixed-quantity supply unit 15. The slit pieces S and the shredding unit 86 will be described later. The paper pieces C mixed with the above-described shredded pieces flow from the merging unit 17 into the pipe 21.

[0027] The pipe 21 transports the paper pieces C from the first unit group 101 to the second unit group 102 by airflow generated by a blower (not illustrated).

[0028] The second unit group 102 includes a defibrating unit 30, which is a dry defibrator, a separator 41, a pipe 23, a powder supply unit 43, a mixing unit 45, and the pipe 24. In the second unit group 102, these components are arranged in this order from upstream to downstream. The second unit group 102 also includes a control unit 5, a capturing unit 95, a compressor 97, a power supply unit 99, and a pipe 25 and an airflow pipe 29 connected to the separator 41.

[0029] The paper pieces C transported through the pipe 21 flow into the defibrating unit 30. The defibrating unit 30 defibrates the paper pieces C, which is a material containing fibers, by a dry method and generates a defibrated material containing fibers. A known defibrating mechanism can be used as the defibrating unit 30. In the present embodiment, a defibrating mechanism including a rotary blade is used as the defibrating unit 30. The defibrating mechanism generates fibers by shredding and defibrating the paper pieces C with the rotary blade.

[0030] Entangled fibers contained in the paper pieces C are untangled by the defibrating unit 30, and thus the paper pieces C become a defibrated material containing fibers, which is transported to the separator 41.

[0031] The separator 41 sorts the defibrated fibers. Specifically, the separator 41 removes components unnecessary for manufacturing the sheets P3, contained in the fibers. The separator 41 separates relatively long fibers and relatively short fibers. The relatively short fibers, which can degrade the strength of the sheets P3, are sorted out and removed by the separator 41. The separator 41 also removes impurities such as coloring materials and additives contained in the paper pieces C.

[0032] A known separation mechanism can be used as the separator 41. In the present embodiment, a disk-type separation mechanism including a separation filter is used as the separator 41. The separation mechanism sorts and separates relatively short fibers and impurities that pass through the separation filter from relatively long fibers that do not pass through the separation filter. The relatively long fibers are used as defibrated fibers for the material of the web W.

[0033] Humidified air is supplied from the humidification device 266 of the third unit group 103 to the inside of the separator 41. Thus, the defibrated fibers are not easily charged, and adsorption between fibers and adhesion of fibers to the separator 41 can be reduced.

[0034] Relatively short fibers and the like are removed from the defibrated fibers in the separator 41. The defibrated fibers are then transported to the mixing unit 45 through the pipe 23 by the airflow generated by a blower (not illustrated) disposed at a distal end of the airflow pipe 29. Unnecessary components such as relatively short fibers and impurities are sucked by a suction device (not illustrated) of the capturing unit 95 and are discharged through the pipe 25 to the capturing unit 95.

[0035] The capturing unit 95 includes a filter (not illustrated). The filter filters out unnecessary components such as relatively short fibers transported through the pipe 25 by the airflow.

[0036] The compressor 97 generates compressed air. The above-described filter may be clogged with fine particles and the like of the unnecessary components. The filter can be cleaned by blowing the compressed air generated by the compressor 97 onto the filter to blow off adhering particles.

[0037] The power supply unit 99 includes a power supply device (not illustrated) that supplies power to the sheet manufacturing apparatus 1 and the control unit 5. The power supply unit 99 distributes power supplied from the outside to each component of the sheet manufacturing apparatus 1.

[0038] The powder supply unit 43 supplies a binder, which is a powder, to the mixing unit 45. The mixing unit 45 mixes the defibrated material and the binder supplied from the powder supply unit 43, in air. The binder binds fibers to one another in a sheet forming unit 70 described later. In the present embodiment, starch is used as the binder, but a thermoplastic resin or the like may also be used.

[0039] The powder supply unit 43 includes a powder storage unit (not illustrated) and a powder transport unit (not illustrated). The powder storage unit is attachable to and detachable from a main body of the powder supply unit 43. The powder storage unit can be removed from the powder supply unit 43 to be filled with the binder or transported. For example, an auger-type screw or a transport mechanism using airflow is used as the powder transport unit. The powder transport unit transports the binder so as to supply a fixed amount of binder per unit time to the mixing unit 45.

[0040] The powder supplied from the powder supply unit 43 to the mixing unit 45 is not limited to binders and may be other additives such as a coloring material, for example. In addition, the above-described powder may be a mixture of a binder and other additives. Moreover, the sheet manufacturing apparatus 1 may include a plurality of powder supply units 43.

[0041] The mixing unit 45 mixes the defibrated material, which is fibers, with a powder in air. The mixing unit 45 includes a flow path through which fibers are transported and a fan, although these components are not illustrated. The fan of the mixing unit 45 mixes the defibrated material with the binder and the like in air while transporting the defibrated material downstream using a generated airflow. The defibrated material then flows into the pipe 24 from the mixing unit 45.

[0042] The control unit 5 is electrically connected to each component of the sheet manufacturing apparatus 1 and controls the operation of the sheet manufacturing apparatus 1 in an integrated manner. The control unit 5 includes a central processing unit (CPU) and a storage unit including a random access memory (RAM), a read only memory (ROM), and the like, although these components are not illustrated. Various programs for controlling the sheet manufacturing apparatus 1 are stored in the storage unit. The control unit 5 may include dedicated hardware (an application specific integrated circuit: ASIC) that executes at least some of various processes. Specifically, the control unit 5 may be configured as a circuit including one or more processors that operate in accordance with a computer program (software), one or more dedicated hardware circuits such as ASICs, or a combination thereof.

[0043] The processor includes a CPU and memory such as RAM and ROM. The memory stores program codes or instructions configured to cause the CPU to perform processing. The memory, in other words, computer-readable media include any medium that can be accessed by a general-purpose or dedicated computer.

[0044] Although not illustrated, an operation panel is provided on the exterior of the sheet manufacturing apparatus 1. The control unit 5 is electrically connected to the operation panel. The user of the sheet manufacturing apparatus 1 operates the sheet manufacturing apparatus 1 through the operation panel. The operation panel includes, for example, a touch panel type liquid crystal display device and mechanical keys.

[0045] The third unit group 103 deposits and compresses the defibrated material including the binder, and forms it into the belt-shaped sheet P1. The third unit group 103 includes a deposition unit 50, a transport unit 60, a suction unit 200, the humidification unit 265, the humidification device 266, a drainage tank 268, the sheet forming unit 70, and the sheet transport unit 63. In the third unit group 103, the deposition unit 50, the transport unit 60, and the sheet forming unit 70 are arranged in this order from upstream to downstream. The suction unit 200 is disposed between the deposition unit 50 and the sheet forming unit 70 together with the transport unit 60.

[0046] The transport unit 60 includes a deposition transport unit 61 and a back-side transport unit 62. The transport unit 60 transports the web W formed in the deposition unit 50 to the downstream sheet forming unit 70. In the transport direction of the web W, the deposition transport unit 61 is disposed upstream of the back-side transport unit 62. A downstream portion of the deposition transport unit 61 and an upstream portion of the back-side transport unit 62 face each other in the vertical direction. The humidification unit 265 is disposed below the back-side transport unit 62.

[0047] The deposition unit 50 forms a web W by depositing the defibrated material, which is a material containing fibers, by airflow and gravity. The deposition unit 50 includes a drum member 53, a blade member 55 located in the drum member 53, a housing 51 that houses the drum member 53, and a suction device 59. The defibrated material is taken into the drum member 53 from the pipe 24.

[0048] The deposition transport unit 61 is disposed below the deposition unit 50. The deposition transport unit 61 includes a mesh belt 611 and four tension rollers (not illustrated) around which the mesh belt 611 is stretched. The suction device 59 faces the drum member 53 with the mesh belt 611 interposed therebetween in the Z-axis direction.

[0049] The blade member 55 is disposed inside the drum member 53 and is rotationally driven by an electric motor (not illustrated). The drum member 53 is a semicircular columnar sieve. A mesh having a function of a sieve is provided on a side surface of the drum member 53 facing downward. The drum member 53 allows the fibers of the defibrated material and particles such as the binder, which are smaller than the size of the mesh openings of the sieve, to pass through the mesh openings from the inside to the outside.

[0050] The defibrated material is discharged to the outside of the drum member 53 while being stirred by the rotating blade member 55 in the drum member 53. Humidified air is supplied from the humidification device 266 to the inside of the drum member 53. Thus, the fibers, the binder, and the like are not easily charged, and adsorption between the fibers and adhesion of the fibers to the drum member 53, the blade member 55, and the like can be reduced.

[0051] The suction device 59 is disposed below the drum member 53. The suction device 59 sucks air from inside the housing 51 through a plurality of holes of the mesh belt 611. Thus, an airflow for depositing the defibrated material onto the mesh belt 611 is generated. The plurality of holes of the mesh belt 611 allow air to pass therethrough, but it is difficult for the fibers, the binder, and the like contained in the defibrated material to pass through the holes. Thus, the defibrated material discharged to the outside of the drum member 53 is sucked downward together with air. The suction device 59 is a known suction device such as a suction blower.

[0052] The defibrated material containing the binder and the like is dispersed in the air inside the housing 51 and deposited onto the upper surface of the mesh belt 611 by gravity and the airflow generated by the suction device 59 and is formed into a web W.

[0053] The mesh belt 611 of the deposition transport unit 61 is an endless belt, and is stretched around the four tension rollers. The mesh belt 611 is rotated counterclockwise in FIG. 1 by the rotation of the tension rollers. Thus, the defibrated material is continuously deposited onto the mesh belt 611 and formed into a web W. The web W contains a relatively large amount of air and is soft and swollen. The deposition transport unit 61 transports the formed web W downstream by the rotation of the mesh belt 611.

[0054] The back-side transport unit 62 is disposed downstream of the deposition transport unit 61 and transports the web W transferred from the deposition transport unit 61. The back-side transport unit 62 peels the web W from the upper surface of the mesh belt 611 and transports the web W toward the sheet forming unit 70. The back-side transport unit 62 is disposed above the transport path of the web W and slightly upstream of a starting point on a return side, in other words, an end portion in the Y direction of the mesh belt 611. The +Y direction side of the back-side transport unit 62 and the Y direction side of the mesh belt 611 partially overlap each other in the vertical direction.

[0055] The back-side transport unit 62 includes a transport belt 621 and four tension rollers (not illustrated). The transport belt 621 has a plurality of holes through which air passes. The transport belt 621 holds the web W by being in contact with the surface of the web W facing upward, which is one surface of the web W, and transports the web W in the transport direction which is the Y direction.

[0056] The transport belt 621 is stretched around the four tension rollers, and is rotated clockwise in FIG. 1 by the rotation of the tension rollers. The suction unit 200 is disposed on the inner side of the transport belt 621 stretched around the four tension rollers. The transport belt 621 holds the web W by a suction force generated by the suction unit 200.

[0057] The suction unit 200 causes the upper surface of the web W, which is the back side, to be attracted and attached to the transport belt 621 by suction through the plurality of holes of the transport belt 621. The transport belt 621 transports the web W in a state in which the upper surface of the web W is attracted and attached to the transport belt 621.

[0058] The suction unit 200 is provided on the transport path of the web W in the back-side transport unit 62 and above the region of the transport belt 621 that comes into contact with the web W. The suction unit 200 sucks air from below in the upward direction through the plurality of holes of the transport belt 621. Thus, the upper surface of the web W is attracted and attached to the lower surface of the transport belt 621. When the transport belt 621 rotates in this state, the web W attracted and attached to the transport belt 621 is transported downstream. The suction unit 200 includes known suction devices such as suction fans which are not illustrated. The suction unit 200 will be described in detail later.

[0059] The humidification unit 265 moistens the web W by adding moisture to the surface of the web W facing downward, which is the other surface side. The humidification unit 265 supplies mist M as moisture from below the web W being transported by the back-side transport unit 62. The humidification unit 265 is provided below the back-side transport unit 62 so as to face the transport belt 621 and the web W being transported by the transport belt 621, in the vertical direction. For example, a known device such as an ultrasonic humidifier can be used as the humidification unit 265.

[0060] When the web W is moistened by the mist M, the function of starch, which is the binder contained in the web W, is promoted, and the strength of the sheets P3 is improved. In addition, since the web W is moistened from below, droplets derived from the mist M are less likely to fall onto the web W. Furthermore, since the web W is moistened from the side opposite to the upper surface of the web W which is in contact with the transport belt 621, the adhesion of the web W to the transport belt 621 is reduced.

[0061] The sheet forming unit 70 presses and compresses the web W to form a belt-shaped sheet P1. The sheet forming unit 70 includes a pair of first and second rollers 71 and 72. The sheet forming unit 70 forms the belt-shaped sheet P1 from the web W by passing the web W between the first roller 71 and the second roller 72.

[0062] Each of the first roller 71 and the second roller 72 is a substantially cylindrical member. The rotation axis of the first roller 71 and the rotation axis of the second roller 72 are parallel to the X-axis. The first roller 71 is disposed substantially below the transport path of the web W, and the second roller 72 is disposed substantially above the transport path of the web W. The first roller 71 and the second roller 72 rotate in close proximity to each other when the belt-shaped sheet P1 is formed from the web W.

[0063] In the X-axis direction, the length of the first roller 71 and the length of the second roller 72 are greater than the length of the web W, that is, the width of the web W. Thus, the web W is reliably pinched between the first roller 71 and the second roller 72.

[0064] The diameter of the first roller 71 is larger than the diameter of the second roller 72. For example, the diameter of the first roller 71 is 110 mm or more and 150 mm or less, and the diameter of the second roller 72 is 80 mm or more and 110 mm or less.

[0065] The first roller 71 includes, for example, a metal core shaft and a surface layer covering the metal core shaft. Examples of the metal core shaft include a hollow structure made of aluminum, iron, stainless steel, or the like. Examples of the material of the surface layer include fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (ETFE), and silicone resins. This improves the release properties of the first roller 71 from the web W. In addition, the abrasion and damage of the metal core shaft are mitigated.

[0066] The second roller 72 includes, for example, a metal core shaft, an intermediate layer, and a surface layer. Examples of the metal core shaft include a hollow structure made of aluminum, iron, stainless steel, or the like. The intermediate layer covers the metal core shaft and is covered with the surface layer. In other words, the intermediate layer is interposed between the metal core shaft and the surface layer.

[0067] Examples of the material of the intermediate layer include elastic materials such as silicone rubber and urethane rubber. The elastic materials preferably have a hardness of 30 or more and 70 or less, more preferably 40 or more and 60 or less when measured with an Asker C hardness tester. The thickness of the intermediate layer is preferably 1 mm or more and 10 mm or less, more preferably 1 mm or more and 5 mm or less.

[0068] Examples of the material of the surface layer include fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (ETFE). Since the second roller 72 has the above-described configuration, the release properties of the second roller 72 from the web W are high. In addition, the abrasion and damage of the intermediate layer are mitigated.

[0069] The web W is pressed when passing between the first roller 71 and the second roller 72. The pressure applied to the web W by the first roller 71 and the second roller 72 is preferably 0.1 MPa or more and 15.0 MPa or less, more preferably 0.2 MPa or more and 10.0 MPa or less, still more preferably 0.4 MPa or more and 8.0 MPa or less. Thus, the deterioration of the fibers in the web W is mitigated.

[0070] The first roller 71 contains an electric heater and has a function of increasing the temperature of the roller surface. Similarly to the first roller 71, the second roller 72 preferably has a function of increasing the temperature of the roller surface by using an electric heater.

[0071] The surface temperature of the first roller 71, that is, the temperature of the surface layer of the first roller 71 which is in contact with the web W is preferably 100 C. or more and 130 C. or less. The surface temperature of the second roller 72, that is, the temperature of the surface layer of the second roller 72 which is in contact with the web W is preferably 80 C. or more and 100 C. or less.

[0072] The first roller 71 is driven by a stepping motor (not illustrated) and rotates counterclockwise when viewed from the X direction. The second roller 72 is a driven roller that is not driven by an electric motor or the like but rotates with the rotation of the first roller 71. Hence, the second roller 72 rotates clockwise when viewed from the X direction.

[0073] The web W, pinched between the first roller 71 and the second roller 72, is sent downstream while being heated and pressed. In other words, the web W continuously passes through the sheet forming unit 70 and is press-formed while being heated. The use of the first roller 71 and the second roller 72 as a pair of forming members enables the web W to be efficiently heated and pressed.

[0074] When the web W passes through the sheet forming unit 70, the amount of air contained in the web W reduces from a state in which the web contains a relatively large amount of air and is soft, and the density of the web W increases. The fibers are bound to one another by the binder and formed into the belt-shaped sheet P1. The belt-shaped sheet P1 is transported to the first unit group 101 by a plurality of rollers (not illustrated) of the sheet transport unit 63.

[0075] The humidification device 266 is disposed below the humidification unit 265. The humidification device 266 supplies humidified air through a plurality of pipes (not illustrated) and humidifies the above-described regions of the sheet manufacturing apparatus 1. A known evaporative humidification device can be used as the humidification device 266. Examples of evaporative humidification devices include one that generates humidified air by blowing air to a moistened non-woven fabric or the like to evaporate moisture.

[0076] The drainage tank 268 is a tank for drainage. The drainage tank 268 is used to collect and store the water that was used in the humidification unit 265, the humidification device 266, and the like and became waste water. The drainage tank 268 can be removed from the sheet manufacturing apparatus 1 as necessary, and the collected water can be disposed.

[0077] The belt-shaped sheet P1 transported from the sheet forming unit 70 to the first unit group 101 reaches the first cutting unit 81. The first cutting unit 81 cuts the belt-shaped sheet P1 in a direction intersecting the transport direction, for example, in the X-axis direction. The belt-shaped sheet P1 is cut into cut sheets P2 by the first cutting unit 81. The cut sheet P2 is transported from the first cutting unit 81 to the second cutting unit 82 by the sheet transport unit 63.

[0078] The second cutting unit 82 cuts the cut sheet P2 in the transport direction, for example, in the Y-axis direction. Specifically, the second cutting unit 82 cuts both end portions of the cut sheet P2 in the X-axis direction. Thus, the cut sheet P2 is shaped into a sheet P3 having a predetermined shape such as A4 size or A3 size.

[0079] When the cut sheet P2 is cut into the sheet P3 in the second cutting unit 82, scrap slit pieces S are produced. The slit pieces S are transported substantially in the Y direction and reach the shredding unit 86 which is a shredder. The shredding unit 86 shreds the slit pieces S into shredded pieces and supplies the shredded pieces to the merging unit 17. A mechanism for weighing the shredded pieces of the slit pieces S and supplying the shredded pieces to the merging unit 17 may be provided between the shredding unit 86 and the merging unit 17.

[0080] The sheets P3 are transported substantially upward and collected in the tray 84. In this manner, the sheets P3 are manufactured by the sheet manufacturing apparatus 1. The sheets P3 can be used as a substitute for, for example, copy paper or the like.

[0081] As illustrated in FIG. 2, the suction unit 200 includes a first duct 210, a second duct 220, and a third duct 230. The first duct 210, the second duct 220, and the third duct 230 are arranged in this order in the Y direction, which is the transport direction of the web W. In other words, the second duct 220 is provided downstream of the first duct 210 in the transport direction, and the third duct 230 is provided downstream of the second duct 220 in the transport direction. The second duct 220 has a bulky shape in the +Z direction as compared with the first duct 210 and the third duct 230.

[0082] The suction unit 200 includes three suction fans which are not illustrated. One suction fan is connected to each of the first duct 210, the second duct 220, and the third duct 230. The first duct 210 includes therein a suction chamber 211 in which a negative pressure is generated by its suction fan. The second duct 220 includes therein a suction chamber 221 in which a negative pressure is generated by its suction fan. The third duct 230 includes therein a suction chamber 231 in which a negative pressure is generated by its suction fan. Known mechanisms can be used as the suction fans.

[0083] A plate member 240 is disposed in a region corresponding to the lower surfaces of the suction chambers 211, 221, and 231. The plate member 240 has a substantially flat plate shape when viewed from the Z direction, and a main surface thereof is disposed to be parallel to the XY plane. The plate member 240 has a plurality of suction holes described later, and separates the inside and outside of the suction chambers 211, 221, and 231 in regions other than the suction holes. The first duct 210, the second duct 220, and the third duct 230 suck air through the plurality of suction holes of the plate member 240. The plate member 240 is, for example, a perforated metal made of aluminum or stainless steel.

[0084] In the plate member 240, the region corresponding to the lower face of the suction chamber 211 is a suction region 213 of the first duct 210, the region corresponding to the lower face of the suction chamber 221 is a suction region 223 of the second duct 220, and the region corresponding to the lower surface of the suction chamber 231 is a suction region 233 of the third duct 230.

[0085] The transport belt 621 is stretched around four tension rollers 623. The transport belt 621 is stretched in a substantially trapezoidal shape when viewed from the X direction, and the suction unit 200 is disposed on the inner side of the transport belt 621, along the region corresponding to the lower base of the trapezoidal shape. The transport belt 621 and the plate member 240 are spaced from each other. The plate member 240 and the suction regions 213, 223, and 233 face the transport belt 621 in the vertical direction. The suction unit 200 sucks air below the transport belt 621 through the transport belt 621. Thus, the upper surface of the web W (not illustrated) is attracted and attached to the lower side of the transport belt 621.

[0086] The humidification unit 265 has an outlet 265a. The humidification unit 265 discharges humidified air containing mist M upward. The outlet 265a and the second duct 220 face each other. Specifically, the outlet 265a faces the suction region 223 of the plate member 240 in the vertical direction. In a transparent view from above, the suction region 223 and the outlet 265a have substantially the same shape.

[0087] The web W contains a relatively large number of voids, and its internal structure is in a relatively sparse state. Hence, when the second duct 220 causes the web W to be attracted and attached to the transport belt 621, the second duct 220 also sucks the humidified air discharged from the humidification unit 265 through the web W. The humidified air adds moisture to the web W, and a part of the humidified air reaches the suction chamber 221 of the second duct 220.

[0088] In the related art, when humidified air and fibers of the web W pass through the through-holes in the suction region, the fibers and the like adhere to the through-holes, and clogging easily occurs. However, because the sheet manufacturing apparatus 1 according to the present embodiment has suction holes in the plate member 240 in the form and arrangement described below, clogging of the suction holes can be reduced.

[0089] As illustrated in FIG. 3, the suction unit 200 includes pipes 215, 225, and 235. Each of the pipes 215, 225, and 235 is a tubular member bent in a substantially L shape when viewed from the +Y direction, and its cross section substantially orthogonal to the movement direction of the air flowing inside is substantially circular. One end portion of each of the pipes 215, 225, and 235 is connected to the corresponding suction fan (not illustrated) provided individually. In FIG. 3, the suction fan side of each of the pipes 215, 225, and 235 is not illustrated.

[0090] The other end of the pipe 215 communicates with and is connected to a side surface of the suction chamber 211 in the X direction. The other end of the pipe 225 communicates with and is connected to an upper portion of a side surface of the suction chamber 221 in the X direction. The other end of the pipe 235 communicates with and is connected to a side surface of the suction chamber 231 in the X direction. Each of the suction chambers 211, 221, and 231 is subjected to suction by the corresponding suction fan from the side surface in the X direction.

[0091] As illustrated in FIG. 4, the plate member 240 has a substantially rectangular shape when viewed from the Z direction, and its long sides are parallel to the X-axis. The transport direction of the web W with respect to the plate member 240 is the Y direction. In the following description of FIG. 4, a state as viewed from the Z direction will be described unless otherwise specified.

[0092] The suction region 213 of the first duct 210, the suction region 223 of the second duct 220, and the suction region 233 of the third duct 230, mentioned above, each have a substantially rectangular shape, and their long sides are parallel to the X-axis. In the plate member 240, the suction region 213, the suction region 223, and the suction region 233 are arranged in this order in the transport direction of the web W.

[0093] Partition walls 241, 242, 243, 244, and 245 are attached to the plate member 240. Each of the partition walls 241, 242, 243, 244, and 245 is an elongated member parallel to the X-axis and has a dimension in the X-axis direction substantially equal to the dimension of the suction regions 213, 223, and 233. Each of the partition walls 241, 242, 243, 244, and 245 protrudes in the Z direction from the surface of the plate member 240 facing the Z direction. Each of the partition walls 241, 242, 243, 244, and 245 is disposed so as to close a gap between the plate member 240 and the transport belt 621 spaced from the plate member 240. Here, the partition wall 242 is an example of a partition wall of the present disclosure.

[0094] Each of the partition walls 241, 242, 243, 244, and 245 is formed of a material such as a resin. The material may be any material that can close the gap between the plate member 240 and the transport belt 621, and a fabric such as moquette may be used instead of resin.

[0095] The suction region 213 includes an upstream suction region 213a and a downstream suction region 213b. The partition wall 242 is provided between the upstream suction region 213a and the downstream suction region 213b and substantially in the middle of the suction region 213 in the Y-axis direction. In other words, the partition wall 242 divides the suction region 213 into the upstream suction region 213a and the downstream suction region 213b. The downstream suction region 213b is located downstream of the upstream suction region 213a in the transport direction of the web W.

[0096] The partition wall 241 is disposed in the upstream suction region 213a to be adjacent to the upstream long side of the upstream suction region 213a in the transport direction of the web W. The partition wall 243 is disposed between the suction region 213 and the suction region 223. The partition wall 244 is disposed between the suction region 223 and the suction region 233. The partition wall 245 is disposed in the suction region 233 to be adjacent to the downstream long side of the suction region 233 in the transport direction of the web W.

[0097] The suction region 213 is provided with a plurality of first suction holes 219a and 219b for sucking air. The suction region 223 is provided with a plurality of second suction holes 229 for sucking air. The suction region 233 is provided with a plurality of third suction holes 239a and 239b for sucking air. In each group of the first suction holes 219a and 219b, the second suction holes 229, and the third suction holes 239a and 239b, the holes are arranged in a staggered manner in the X-axis direction. Note that the arrangement of these holes is not limited to the above example.

[0098] The diameters of the second suction holes 229 are larger than the diameters of the first suction holes 219a and 219b and the diameters of the third suction holes 239a and 239b. Thus, when fibers derived from the web W and humidified air pass through the second suction holes 229, wet fibers are less likely to adhere to the second suction holes 229 and the periphery thereof. Of the plurality of first suction holes 219a and 219b, the first suction holes 219a are provided in the upstream suction region 213a, and the first suction holes 219b are provided in the downstream suction region 213b. The diameters of the first suction holes 219a are larger than the diameters of the first suction holes 219b.

[0099] Although not particularly limited, for example, the diameters of the first suction holes 219a are about 5 mm, the diameters of the first suction holes 219b are about 3 mm, the diameters of the second suction holes 229 are about 9 mm to about 10 mm, the diameters of the third suction holes 239a are about 5 mm, and the diameters of the third suction holes 239b are about 6 mm.

[0100] As described above, in the suction chamber 221 corresponding to the suction region 223, air is sucked through the pipe 225 on the side surface of the suction chamber 221 in the X direction. In the present embodiment, in the suction region 223, the diameters of the second suction holes 229 on the +X direction side are set to about 10 mm, and the diameters of the second suction holes 229 on the X direction side are set to about 9 mm. In other words, the diameters of the second suction holes 229 at positions relatively close to the suction fan (not illustrated) are set smaller than the diameters of the second suction holes 229 at positions relatively far from the suction fan.

[0101] Thus, in the suction chamber 221, the air speed of the sucked air is well balanced, and the variation in the suction force of the plurality of second suction holes 229 is reduced. In addition, since the variation in the suction force is reduced, the humidified air relatively uniformly passes through the web W being transported, and it is possible to moisten the web W while preventing an uneven distribution of moisture. The diameters of the second suction holes 229 may be adjusted according to the distance to the suction fan. Specifically, for example, in the case of a configuration in which suction is performed from above the center of the suction region 223, the diameters of the second suction holes 229 in a middle region in the X-axis direction are set small in the suction region 223.

[0102] As illustrated in FIG. 5, since the diameters of the first suction holes 219a are larger than the diameters of the first suction holes 219b, the flow rate of the air Fa sucked into the first suction hole 219a is higher than the flow rate of the air Fb sucked into the first suction hole 219b. Accordingly, the suction force in the upstream suction region 213a is larger than in the downstream suction region 213b. Hence, the web W can be reliably attracted from the mesh belt 611 of the deposition transport unit 61 and can be attached to the transport belt 621.

[0103] The upstream suction region 213a and the downstream suction region 213b are separated by the partition wall 242. Hence, the first suction holes 219a suck the air Fa through the transport belt 621 in the range facing the upstream suction region 213a, and the first suction holes 219b suck the air Fb through the transport belt 621 in the range facing the downstream suction region 213b. Specifically, the first suction holes 219a is less likely to suck air from the range corresponding to the downstream suction region 213b. This improves the suction force in each of the upstream suction region 213a and the downstream suction region 213b.

[0104] In particular, when the downstream leading end of the web W reaches the upstream suction region 213a, the first suction holes 219a do not suck air from the range corresponding to the downstream suction region 213b. Hence, the suction force of the first suction holes 219a is less likely to decrease, so that the web W can be more reliably attracted and attached to the transport belt 621.

[0105] According to the present embodiment, the following effects can be obtained.

[0106] The frequency of maintenance work can be reduced. Specifically, the second suction holes 229 have diameters larger than those of the first suction holes 219a and 219b and the third suction holes 239a and 239b. Hence, when fibers derived from the web W and containing moisture pass through the second suction holes 229, the fibers are less likely to adhere to the second suction holes 229, and the occurrence of clogging in the second suction holes 229 is reduced. Hence, it is possible to provide the sheet manufacturing apparatus 1 that reduces the frequency of maintenance work.