Sheet manufacturing apparatus

Abstract

To provide a sheet manufacturing apparatus which reduces the frequency of maintenance work.SOLUTION: A depositing unit that forms a web W, a transport belt, a suction unit that is provided above the transport belt and causes the web to be adsorbed to the transport belt by air suction, a humidifying unit that is provided so as to face the transport belt and applies moisture from a lower side of the web, and a sheet forming unit that pressurizes the web and forms the web into a belt-shaped sheet, the humidifying unit includes a discharge port that discharges the humidified air, the second duct and the discharge port are disposed to face each other, a plurality of first sucking holes 219a and 219b that suck air are provided in the sucking region 213 of the first duct, a plurality of second sucking holes 229 that suck air are provided in the sucking region 223 of the second duct, and diameters of the second sucking holes 229 are larger than diameters of the first sucking holes 219a and 219b.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet manufacturing apparatus. [Background technology]

[0002] Conventionally, there have been known devices for manufacturing sheets from fibrous materials. For example, Patent Document 1 discloses a sheet manufacturing device that deposits fibers in the air to form a web and then molds the web into a sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-24818 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the device described in Patent Document 1 may require increased maintenance frequency. Specifically, the device humidifies a web formed in a deposition unit. The web is held on a conveyor belt by negative pressure generated by a suction unit, and moisture is added to the web by humidified air supplied from an outlet of the humidifier. The suction unit sucks air through the conveyor belt via the through-holes of multiple suction ports, adsorbing the web to the conveyor belt. Of the multiple suction ports, a first suction port is positioned opposite the outlet. Therefore, humidified air and fibers detached from the web pass through the through-holes of the first suction port. The fibers detached from the web are moistened by the humidified air and tend to adhere to the through-holes of the first suction port. When the adhesion of fibers to the through-holes becomes significant, the through-holes may become clogged, requiring maintenance. The following invention was devised to solve the above-mentioned problems. [Means for solving the problem]

[0005] The sheet manufacturing apparatus is a sheet manufacturing apparatus for manufacturing a sheet from a material containing fiber, and includes: a deposition unit that deposits the material by an airflow to form a web; a conveyor belt that contacts one side of the web to hold the web and conveys the web along a conveying direction; a suction unit that is provided above the conveyor belt and absorbs the web onto the conveyor belt by suction; a humidification unit that is provided opposite the conveyor belt and adds moisture to the other side of the web; and a sheet forming unit that pressurizes the web to form it into a sheet. The suction unit has a first duct, a second duct provided downstream in the conveying direction from the first duct, and a third duct provided downstream in the conveying direction from the second duct, the humidifying unit has an outlet for discharging humidified air, the second duct and the outlet are arranged opposite each other, the suction area of ​​the first duct has a plurality of first suction holes for sucking air, the suction area of ​​the second duct has a plurality of second suction holes for sucking air, and the diameter of the second suction holes is larger than the diameter of the first suction holes. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of a sheet manufacturing apparatus according to an embodiment. [Figure 2] FIG. 3 is a schematic diagram showing a detailed configuration of a suction unit. [Figure 3] FIG. 4 is a perspective view showing the arrangement of pipes connected to the suction fan. [Figure 4] FIG. [Figure 5] 5 is a cross-sectional view taken along the line A-A' in FIG. 4, illustrating the functions of the first suction hole and the partition wall. DETAILED DESCRIPTION OF THE INVENTION

[0007] In the following embodiments, a sheet manufacturing apparatus 1 that recycles waste paper or the like into sheets in a dry process is exemplified as the sheet manufacturing apparatus of the present invention. The sheet manufacturing apparatus 1 will be described below with reference to the drawings. The sheet manufacturing apparatus of the present invention is not limited to a dry process, and may be a wet process. In this specification, the term "dry process" refers to a process that is carried out in air, such as the atmosphere, rather than in a liquid.

[0008] In the following drawings, X, Y, and Z axes are assigned as mutually orthogonal coordinate axes, with the direction indicated by each arrow being the + direction and the direction opposite the + direction being the - direction. The Z axis is a virtual axis along the vertical direction, with the +Z direction being upward and the -Z direction being downward. The -Z direction is the vertical direction. In the sheet manufacturing apparatus 1, the end of the conveying direction of the material, web, sheet, etc. is downstream, and the side going backward in the conveying direction is upstream. For ease of illustration, the sizes of each component are different from the actual size.

[0009] As shown in Fig. 1, the sheet manufacturing apparatus 1 according to this 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 shown). In Fig. 1, the directions in which the pieces of paper C, the sheet P3, the slit pieces S, and unnecessary scraps move are indicated by white arrows. In the following description, a collection of multiple pieces of paper C will also be simply referred to as a piece of paper C.

[0010] The sheet manufacturing apparatus 1 manufactures a sheet P3 from paper pieces C, which are a material containing fibers such as recycled paper. In the sheet manufacturing apparatus 1, a first unit group 101, a third unit group 103, and a second unit group 102 are arranged from the -Y direction to the +Y direction in a side view from the -X direction.

[0011] The paper pieces C are transported from the first unit group 101 to the second unit group 102 via a pipe 21 that traverses the third unit group 103. The paper pieces C are then subjected to defibration and other processes in the second unit group 102 to become a defibrated material, which is an aggregate of fibers, and a binder and other materials are added. The defibrated material is transported to the third unit group 103 via a pipe 24. The defibrated material is made into a web W in the third unit group 103 and then formed into a belt-shaped sheet P1. The belt-shaped sheet P1 is cut in the first unit group 101 to become a sheet P3.

[0012] The first unit group 101 has a buffer tank 13, a constant volume supply unit 15, a junction unit 17, and a pipe 21. In the first unit group 101, these components are arranged in the above order from upstream to downstream. The first unit group 101 also has a first cutting unit 81, a second cutting unit 82, a tray 84, and a shredding unit 86.

[0013] Furthermore, a sheet conveying section 63 is disposed across the third unit group 103 and the first unit group 101. The sheet conveying section 63 conveys a strip-shaped sheet P1, a cut sheet P2, a sheet P3, and a slit piece S. The first cutting section 81 and the second cutting section 82 cut the strip-shaped sheet P1 into a sheet P3 having a predetermined shape.

[0014] Furthermore, first unit group 101 has water supply tank 267. Water supply tank 267 is a water storage tank. Water supply tank 267 supplies water for humidification to humidifying section 265 (described later) and humidifying device 266 via a hose (not shown). Pure water, tap water, etc. can be used as the water stored in water supply tank 267. Note that humidifying device 266 is an example of a humidifying device of the present invention.

[0015] The pieces of paper C are fed into the buffer tank 13 from the raw material inlet 11. The pieces of paper C contain fibers such as cellulose, and are, for example, shredded waste paper. Humidified air is supplied into the buffer tank 13 from the humidifier 266 provided in the third unit group 103. This makes it difficult for the pieces of paper C to become electrically charged, and prevents the pieces of paper C from sticking to each other.

[0016] The paper pieces C to be defibrated are temporarily stored in the buffer tank 13, and then transported to the constant quantity supply unit 15 in accordance with the operation of the sheet manufacturing apparatus 1. The sheet manufacturing apparatus 1 may be provided with a shredder upstream of the buffer tank 13 that shreds the paper pieces C and the like.

[0017] The constant-quantity supply unit 15 has a weighing device 15a and a supply mechanism (not shown). The weighing device 15a measures the mass of the pieces of paper C. The supply mechanism supplies the pieces of paper C weighed by the weighing device 15a to the downstream junction 17. That is, the constant-quantity supply unit 15 measures the pieces of paper C by predetermined mass using the weighing device 15a, and supplies them to the downstream junction 17 using the supply mechanism.

[0018] The weighing device 15a may be either a digital or analog weighing mechanism. Specifically, the weighing device 15a may be a physical sensor such as a load cell, a spring balance, or a balance. In this embodiment, a load cell is used as the weighing device 15a. The predetermined mass at which the weighing device 15a weighs the piece of paper C is, for example, several grams to several tens of grams.

[0019] The feeding mechanism may be a known technique such as a vibrating feeder, etc. The feeding mechanism may be included in the weighing device 15a.

[0020] The weighing and supply of the pieces of paper C in the constant quantity supply unit 15 is a batch process. That is, the supply of the pieces of paper C from the constant quantity supply unit 15 to the junction 17 is carried out intermittently. The constant quantity supply unit 15 may have multiple weighing devices 15a, and the multiple weighing devices 15a may be operated at staggered times to improve weighing efficiency.

[0021] At the confluence 17, the pieces of paper C supplied from the constant quantity supply unit 15 are combined with the fine fragments of the slit pieces S supplied from the shredding unit 86 and mixed together. The slit pieces S and the shredding unit 86 will be described later. The pieces of paper C mixed with the fine fragments flow from the confluence 17 into the pipe 21.

[0022] The pipe 21 transports the paper pieces C from the first unit group 101 to the second unit group 102 by an air current generated by a blower (not shown).

[0023] The second unit group 102 includes a defibrating unit 30, which is a dry type defibrator, a separating unit 41, piping 23, a powder supplying unit 43, a mixing unit 45, and piping 24. In the second unit group 102, these components are arranged in the above order from upstream to downstream. The second unit group 102 also includes a control unit 5, a collecting unit 95, a compressor 97, a power supply unit 99, and piping 25 and airflow piping 29 connected to the separating unit 41.

[0024] The paper pieces C transported through the pipe 21 flow into the defibrating unit 30. The defibrating unit 30 dry-defibrates the paper pieces C, which are a material containing fibers, to generate defibrated material containing fibers. A known defibrating mechanism can be applied to the defibrating unit 30. In this embodiment, a defibrating mechanism equipped with rotary blades is used as the defibrating unit 30. The defibrating mechanism shreds and defibrates the paper pieces C with the rotary blades to generate fibers.

[0025] The defibrating unit 30 untangles the tangled fibers contained in the paper pieces C, turning them into defibrated material containing fibers, and the defibrated material is transported to the separating unit 41.

[0026] The separation unit 41 separates the defibrated fibers. More specifically, the separation unit 41 removes components contained in the fibers that are unnecessary for manufacturing the sheet P3. The separation unit 41 separates relatively long fibers from relatively short fibers. Relatively short fibers may reduce the strength of the sheet P3, so they are selected and removed by the separation unit 41. The separation unit 41 also removes impurities such as coloring materials and additives contained in the pieces of paper C.

[0027] A known separation mechanism can be applied to the separation unit 41. In this embodiment, a disk-type separation mechanism equipped with a separation filter is used as the separation unit 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 material for the web W as defibrated fibers.

[0028] Humidified air is supplied to the inside of the separation section 41 from the humidifier 266 of the third unit group 103. This makes it difficult for the defibrated fibers to become electrically charged, and prevents the fibers from adhering to each other and to the separation section 41.

[0029] The defibrated fibers are removed from the separating section 41 by relatively short fibers. Then, the fibers are transported to the mixing section 45 via the piping 23 by an airflow generated by a blower (not shown) located at the tip of the airflow piping 29. Unwanted materials such as relatively short fibers and impurities are sucked into a suction device (not shown) of the collecting section 95 and discharged from the piping 25 to the collecting section 95.

[0030] The collection unit 95 includes a filter (not shown) that filters out unnecessary particles such as relatively short fibers carried through the pipe 25 by the air current.

[0031] The compressor 97 generates compressed air. The filter may become clogged with fine particles from unwanted matter. The compressed air generated by the compressor 97 can be blown onto the filter to blow away any particles adhering to the filter, cleaning the filter.

[0032] The power supply unit 99 has a power supply device (not shown) that supplies power to the sheet manufacturing apparatus 1, and a control unit 5. The power supply unit 99 distributes power supplied from an external source to each component of the sheet manufacturing apparatus 1.

[0033] The powder supply unit 43 supplies the binder, which is a powder, to the mixer 45. The mixer 45 mixes the defibrated material and the binder supplied from the powder supply unit 43 in the air. The binder binds the fibers together in the sheet forming unit 70, which will be described later. In this embodiment, starch is used as the binder, but a thermoplastic resin or the like may also be used.

[0034] The powder supply unit 43 includes a powder storage unit and a powder conveying unit, both of which are not shown. The powder storage unit is detachable from the main body of the powder supply unit 43. The powder storage unit can be removed from the powder supply unit 43 to fill or convey the binder. The powder conveying unit may be, for example, an auger-type screw or a conveying mechanism that uses wind power. The powder conveying unit supplies a fixed amount of binder per hour to the mixing unit 45 while conveying the binder.

[0035] The powder supplied to the mixing unit 45 by the powder supply unit 43 is not limited to a binder, and may be other additives such as a colorant. The powder may also be a mixture of a binder and other additives. Furthermore, the sheet manufacturing apparatus 1 may include a plurality of powder supply units 43.

[0036] The mixer 45 mixes powder into the defibrated material, which is fiber, in the air. Although not shown, the mixer 45 is equipped with a flow path for transporting the fiber and a fan. The fan of the mixer 45 generates an airflow that mixes in binders and the like in the air while transporting the defibrated material downstream. The defibrated material then flows from the mixer 45 into the piping 24.

[0037] The control unit 5 is electrically connected to each component of the sheet manufacturing apparatus 1 and comprehensively controls the operation of the sheet manufacturing apparatus 1. Although not shown, the control unit 5 includes a central processing unit (CPU) and a storage unit including a random access memory (RAM) and a read-only memory (ROM). The storage unit stores various programs for controlling the sheet manufacturing apparatus 1. The control unit 5 may include dedicated hardware (application-specific integrated circuit: ASIC) that executes at least some of the various processes. In other words, the control unit 5 may be configured as a circuit including one or more processors that operate according to a computer program (software), one or more dedicated hardware circuits such as ASIC, or a combination of these.

[0038] A processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform processes. Memory, i.e., computer-readable media, includes anything that can be accessed by a general-purpose or special-purpose computer.

[0039] Although not shown in the figures, 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. A user of the sheet manufacturing apparatus 1 operates the sheet manufacturing apparatus 1 via the operation panel. The operation panel includes, for example, a touch panel type liquid crystal display device and mechanical keys.

[0040] The third unit group 103 deposits and compresses the defibrated material containing a binder, and forms it into a band-shaped sheet P1. The third unit group 103 includes a depositing unit 50, a conveying unit 60, a suction unit 200, a humidifying unit 265, a humidifying device 266, a drainage tank 268, a sheet forming unit 70, and a sheet conveying unit 63. In the third unit group 103, the depositing unit 50, the conveying unit 60, and the sheet forming unit 70 are arranged in the above order from upstream to downstream. The suction unit 200, together with the conveying unit 60, is arranged between the depositing unit 50 and the sheet forming unit 70.

[0041] The conveying section 60 has a deposition conveying section 61 and a back surface conveying section 62. The conveying section 60 conveys the web W formed in the deposition section 50 to the downstream sheet forming section 70. In the conveying direction of the web W, the deposition conveying section 61 is disposed upstream of the back surface conveying section 62. A downstream portion of the deposition conveying section 61 and an upstream portion of the back surface conveying section 62 face each other in the vertical direction. The humidifying section 265 is disposed below the back surface conveying section 62.

[0042] The deposition unit 50 deposits the defibrated material, which is a material containing fibers, by airflow and gravity to form a web W. The deposition unit 50 has a drum member 53, blade members 55 installed inside 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 piping 24.

[0043] The deposition and transfer unit 61 is disposed below the deposition unit 50. The deposition and transfer unit 61 has a mesh belt 611 and four tension rollers (not shown) that tension the mesh belt 611. The suction device 59 faces the drum member 53 in the direction along the Z axis, with the mesh belt 611 sandwiched therebetween.

[0044] The blade members 55 are located inside the drum member 53 and are driven to rotate by an electric motor (not shown). The drum member 53 is a semi-cylindrical sieve. A mesh functioning as a sieve is provided on the downward-facing side of the drum member 53. The drum member 53 allows particles such as defibrated material fibers and binders that are smaller than the mesh size of the sieve to pass from the inside to the outside.

[0045] The defibrated material is agitated by the rotating blade members 55 inside the drum member 53 and then released to the outside of the drum member 53. Humidified air is supplied from the humidifier 266 to the inside of the drum member 53. This makes it difficult for the fibers and binder to become electrically charged, and suppresses the fibers from adhering to each other and the drum member 53, blade members 55, etc.

[0046] The suction device 59 is disposed below the drum member 53. The suction device 59 sucks air inside the housing 51 through multiple holes in the mesh belt 611. This generates an air current that deposits the defibrated material on the mesh belt 611. The multiple holes in the mesh belt 611 allow air to pass through but do not allow fibers and binders contained in the defibrated material to pass through easily. As a result, the defibrated material released to the outside of the drum member 53 is sucked downward together with the air. The suction device 59 is a known suction device such as a suction blower.

[0047] The defibrated material containing the binder and the like is dispersed in the air inside the housing 51 and is deposited on the upper surface of the mesh belt 611 by gravity and the airflow generated by the suction device 59 to become the web W.

[0048] The mesh belt 611 of the deposition and transport unit 61 is an endless belt that is stretched over four tension rollers. The mesh belt 611 rotates counterclockwise in FIG. 1 due to the rotation of the tension rollers. As a result, the defibrated material is continuously deposited on the mesh belt 611, and a web W is formed. The web W contains a relatively large amount of air and is soft and inflated. The deposition and transport unit 61 transports the formed web W downstream by the rotation of the mesh belt 611.

[0049] The back conveying unit 62 is disposed downstream of the accumulation conveying unit 61 and conveys the web W handed over from the accumulation conveying unit 61. The back conveying unit 62 peels the web W from the upper surface of the mesh belt 611 and conveys the web W toward the sheet forming unit 70. The back conveying unit 62 is disposed above the conveyance path of the web W and is slightly upstream of the starting point of the return side of the mesh belt 611, i.e., the end in the -Y direction. The +Y direction of the back conveying unit 62 and the -Y direction of the mesh belt 611 partially overlap in the vertical direction.

[0050] The rear conveying section 62 has a conveying belt 621 and four tension rollers (not shown). The conveying belt 621 has a plurality of holes for allowing air to pass through. The conveying belt 621 contacts one surface of the web W, which faces upward, to hold the web W and conveys the web W along the conveying direction in the -Y direction.

[0051] The conveyor belt 621 is stretched over four tension rollers and rotates clockwise in Fig. 1 as the tension rollers rotate. A suction unit 200 is disposed inside the conveyor belt 621 stretched over the four tension rollers. The conveyor belt 621 holds the web W by the suction force generated by the suction unit 200.

[0052] The suction unit 200 sucks the upper surface, which is the back surface of the web W, onto the conveyor belt 621 by sucking air through a plurality of holes in the conveyor belt 621. The conveyor belt 621 sucks the upper surface of the web W and conveys the web W.

[0053] The suction unit 200 is provided on the transport path of the web W in the rear transport unit 62 above the area of ​​the transport belt 621 that comes into contact with the web W. The suction unit 200 sucks air upward through multiple holes in the transport belt 621. As a result, the upper surface of the web W is adsorbed to the lower surface of the transport belt 621. When the transport belt 621 rotates in this state, the web W is adsorbed to the transport belt 621 and transported downstream. Although not shown, the suction unit 200 has a known suction device such as a suction fan. Details of the suction unit 200 will be described later.

[0054] The humidifying unit 265 humidifies the web W by applying moisture to the other side of the web W, that is, the downward-facing side. The humidifying unit 265 supplies mist M as moisture from below the web W transported by the rear surface conveying unit 62. The humidifying unit 265 is located below the rear surface conveying unit 62 and is provided so as to vertically face the conveying belt 621 and the web W transported by the conveying belt 621. A known device such as an ultrasonic humidifier can be used as the humidifying unit 265.

[0055] By humidifying the web W with the mist M, the function of starch, which is a binder contained in the web W, is promoted, and the strength of the sheet P3 is improved. In addition, since the web W is humidified from below, droplets from the mist M are less likely to fall onto the web W. Furthermore, since the web W is humidified from the opposite side of the upper surface that contacts the conveyor belt 621, sticking of the web W to the conveyor belt 621 is reduced.

[0056] The sheet forming unit 70 applies pressure and compresses the web W to form it into a strip-shaped sheet P1. The sheet forming unit 70 has a pair of a first roller 71 and a second roller 72. The sheet forming unit 70 passes the web W between the first roller 71 and the second roller 72 to form the strip-shaped sheet P1 from the web W.

[0057] 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 aligned along 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 it. The first roller 71 and the second roller 72 rotate close to each other while the strip-shaped sheet P1 is being formed from the web W.

[0058] In the direction along the X-axis, the length of the first roller 71 and the length of the second roller 72 are longer than the length of the web W, i.e., the width of the web W. Therefore, the web W is firmly sandwiched between the first roller 71 and the second roller 72.

[0059] 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 not less than 110 mm and not more than 150 mm, and the diameter of the second roller 72 is not less than 80 mm and not more than 110 mm.

[0060] The first roller 71 includes, for example, a core and a surface layer covering the core. The core may have a hollow structure made of aluminum, iron, stainless steel, or the like. Materials for the surface layer include fluororesins such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), and ETFE (tetrafluoroethylene-ethylene copolymer), as well as silicone resin. This improves the releasability of the first roller 71 from the web W. It also reduces wear and damage to the core.

[0061] The second roller 72 includes, for example, a core, an intermediate layer, and a surface layer. The core may have a hollow structure made of aluminum, iron, stainless steel, or the like. The intermediate layer covers the core and is also covered by the surface layer. In other words, the intermediate layer is interposed between the core and the surface layer.

[0062] Materials for the intermediate layer include elastomers such as silicone rubber and urethane rubber. The hardness of the elastomer, as measured by an Asker C hardness tester, is preferably 30 to 70, more preferably 40 to 60. The thickness of the intermediate layer is preferably 1 mm to 10 mm, more preferably 1 mm to 5 mm.

[0063] Examples of materials for the surface layer include fluororesins such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), and ETFE (tetrafluoroethylene-ethylene copolymer).

[0064] The second roller 72 having the above-described configuration improves the releasability of the second roller 72 from the web W. In addition, wear and damage to the intermediate layer are suppressed.

[0065] The web W is pressed while 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, and even more preferably 0.4 MPa or more and 8.0 MPa or less. This suppresses deterioration of the fibers in the web W.

[0066] The first roller 71 has a built-in electric heater and has the function of raising the temperature of the roller surface. Similarly to the first roller 71, the second roller 72 also preferably has a function of raising the temperature of the roller surface by an electric heater.

[0067] The surface temperature of the first roller 71, i.e., the temperature of the surface layer of the first roller 71 that comes into contact with the web W, is preferably 100°C or higher and 130°C or lower. The surface temperature of the second roller 72, i.e., the temperature of the surface layer of the second roller 72 that comes into contact with the web W, is preferably 80°C or higher and 100°C or lower.

[0068] The first roller 71 is driven by a stepping motor (not shown) and rotates counterclockwise when viewed from the -X direction. The second roller 72 is not driven by an electric motor or the like, but is a driven roller that rotates in conjunction with the rotation of the first roller 71. Therefore, the second roller 72 rotates clockwise when viewed from the -X direction.

[0069] The web W is sandwiched between the first roller 71 and the second roller 72 and sent downstream while being heated and pressurized. That is, the web W is continuously passed through the sheet forming unit 70 and press-formed while being heated. By using the first roller 71 and the second roller 72 as a pair of forming members, the web W is efficiently heated and pressurized.

[0070] As the web W passes through the sheet forming unit 70, it is converted from a soft state containing a relatively large amount of air into a reduced amount of air and an increased density. Then, the fibers are bound together by a binder, and the web W is formed into a belt-shaped sheet P1. The belt-shaped sheet P1 is transported to the first unit group 101 by a plurality of rollers (not shown) of the sheet transport unit 63.

[0071] The humidifier 266 is disposed below the humidifying section 265. The humidifier 266 supplies humidified air through a plurality of pipes (not shown) to humidify the above-mentioned area of ​​the sheet manufacturing apparatus 1. A known evaporative humidifier can be used as the humidifier 266. An example of an evaporative humidifier is one that blows air onto a moistened nonwoven fabric or the like to evaporate the moisture and generate humidified air.

[0072] The drainage tank 268 is a drainage tank. The drainage tank 268 is used in the humidifying section 265, the humidifying device 266, etc., and collects and stores old water. The drainage tank 268 can be removed from the sheet manufacturing apparatus 1 as needed, allowing the accumulated water to be discarded.

[0073] The strip-shaped sheet P1 transported from the sheet forming section 70 to the first unit group 101 reaches the first cutting section 81. The first cutting section 81 cuts the strip-shaped sheet P1 in a direction intersecting the transport direction, for example, along the X-axis. The strip-shaped sheet P1 is cut into single sheets P2 at the first cutting section 81. The single sheets P2 are transported from the first cutting section 81 to the second cutting section 82 by the sheet transport section 63.

[0074] The second cutting section 82 cuts the single sheet P2 in the conveying direction, for example, along the Y axis. More specifically, the second cutting section 82 cuts both ends of the single sheet P2 in the direction along the X axis. As a result, the single sheet P2 becomes a sheet P3 of a predetermined shape, for example, A4 size or A3 size.

[0075] When the second cutting section 82 cuts the single sheets P2 into sheets P3, slit pieces S, which are scraps, are generated. The slit pieces S are transported in the approximately -Y direction to the shredding section 86, which is a shredder. The shredding section 86 shreds the slit pieces S into small pieces and supplies them to the junction 17. A mechanism may be installed between the shredding section 86 and the junction 17 to weigh the small pieces of the slit pieces S and supply them to the junction 17.

[0076] The sheet P3 is conveyed substantially upward and accumulated on the tray 84. In this manner, the sheet P3 is manufactured by the sheet manufacturing apparatus 1. The sheet P3 can be used as a substitute for, for example, copy paper.

[0077] 2, the suction unit 200 has 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 the above order in the -Y direction, which is the transport direction of the web W. That is, 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 shape that is bulkier in the +Z direction than the first duct 210 and the third duct 230.

[0078] Although not shown, the suction unit 200 has three suction fans. 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 has an internal suction chamber 211 in which negative pressure is generated by the suction fan. The second duct 220 has an internal suction chamber 221 in which negative pressure is generated by the suction fan. The third duct 230 has an internal suction chamber 231 in which negative pressure is generated by the suction fan. Known mechanisms can be applied to the suction fans.

[0079] A plate-shaped member 240 is disposed in a region corresponding to the lower surfaces of the suction chambers 211, 221, and 231. The plate-shaped member 240 is substantially flat when viewed from the -Z direction, and its main surface is disposed along the XY plane. The plate-shaped member 240 has a plurality of suction holes, which will be 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 in the plate-shaped member 240. The plate-shaped member 240 is, for example, a punched metal made of aluminum or stainless steel.

[0080] In the plate-shaped member 240, the area corresponding to the lower surface of the suction chamber 211 is the suction area 213 of the first duct 210, the area corresponding to the lower surface of the suction chamber 221 is the suction area 223 of the second duct 220, and the area corresponding to the lower surface of the suction chamber 231 is the suction area 233 of the third duct 230.

[0081] The conveyor belt 621 is stretched over four tension rollers 623. The suction unit 200 is disposed inside the conveyor belt 621, which is stretched in a substantially trapezoidal shape when viewed from the -X direction, along a region corresponding to the bottom of the trapezoid. The conveyor belt 621 and the plate-like member 240 are disposed at a distance from each other. The plate-like member 240 and the suction regions 213, 223, and 233 face the conveyor belt 621 in the vertical direction. The suction unit 200 sucks air below the conveyor belt 621 via the conveyor belt 621. As a result, the upper surface of the web W (not shown) is sucked below the conveyor belt 621.

[0082] The humidifier 265 has an outlet 265a. The humidifier 265 discharges humidified air containing mist M upward. The outlet 265a and the second duct 220 are disposed opposite to each other. That is, the outlet 265a faces the suction region 223 of the plate-shaped member 240 in the vertical direction. When seen through from above, the suction region 223 and the outlet 265a have approximately the same shape.

[0083] The web W has a relatively large number of gaps inside, and its internal structure is relatively loose. Therefore, the second duct 220 not only adsorbs the web W onto the conveyor belt 621 but also sucks in the humidified air discharged by the humidifier 265 through the web W. The humidified air imparts moisture to the web W, and some of the humidified air reaches the suction chamber 221 of the second duct 220.

[0084] Conventionally, when humidified air and fibers of the web W pass through the through holes in the suction region, the fibers tend to adhere to the through holes, causing clogging. In contrast, the sheet manufacturing apparatus 1 of the present embodiment has suction holes in the plate-like member 240 with the shape and arrangement described below, which prevents the suction holes from becoming clogged.

[0085] As shown 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 into a substantially L-shape when viewed from the +Y direction, and has a substantially circular cross section that is substantially perpendicular to the direction of movement of the airflow circulating therethrough. One end of each of the pipes 215, 225, and 235 is connected to a corresponding suction fan (not shown). In Fig. 3, the suction fan side of each of the pipes 215, 225, and 235 is not shown.

[0086] The other end of the pipe 215 is connected to and communicates with the side surface of the suction chamber 211 in the -X direction. The other end of the pipe 225 is connected to and communicates with the upper part of the side surface of the suction chamber 221 in the -X direction. The other end of the pipe 235 is connected to and communicates with the side surface of the suction chamber 231 in the -X direction. Air is sucked into each of the suction chambers 211, 221, and 231 from the side surface in the -X direction by the corresponding suction fan.

[0087] As shown in Fig. 4, the plate-shaped member 240 is substantially rectangular when viewed from the -Z direction, with its long side aligned with the X axis. The conveyance direction of the web W is the -Y direction relative to the plate-shaped member 240. In the following description of Fig. 4, the state viewed from the -Z direction will be described unless otherwise specified.

[0088] The suction area 213 of the first duct 210, the suction area 223 of the second duct 220, and the suction area 233 of the third duct 230 are each substantially rectangular, with their long sides aligned along the X-axis. On the plate-like member 240, the suction area 213, the suction area 223, and the suction area 233 are arranged in this order along the transport direction of the web W.

[0089] Partition walls 241, 242, 243, 244, and 245 are attached to the plate-shaped member 240. Each of the partition walls 241, 242, 243, 244, and 245 is an elongated member extending along the X-axis, and the length along the X-axis is approximately equal to the length 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 a surface of the plate-shaped 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-shaped member 240 and the conveyor belt 621 spaced apart from it. Here, the partition wall 242 is an example of a partition wall of the present invention.

[0090] Each of the partition walls 241, 242, 243, 244, and 245 is made of a material such as resin. The material may be any material that can close the gap between the plate-like member 240 and the conveyor belt 621, and fabric such as moquette may be used instead of resin.

[0091] 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, approximately in the middle of the suction region 213 in the direction along the Y axis. 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 conveying direction of the web W.

[0092] The partition wall 241 is disposed in the upstream suction region 213a adjacent to the long side on the upstream side in the conveying 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 adjacent to the long side on the downstream side in the conveying direction of the web W.

[0093] Suction region 213 is provided with a plurality of first suction holes 219a, 219b that suck in air. Suction region 223 is provided with a plurality of second suction holes 229 that suck in air. Suction region 233 is provided with a plurality of third suction holes 239a, 239b that suck in air. First suction holes 219a, 219b, second suction hole 229, and third suction holes 239a, 239b are arranged alternately in a staggered pattern along the X-axis. Note that the arrangement of these holes is not limited to the above.

[0094] The diameter of the second suction hole 229 is larger than the diameter of the first suction holes 219a and 219b and the diameter of the third suction holes 239a and 239b. Even if fibers derived from the web W and humid air pass through the second suction hole 229, the moist fibers are less likely to adhere to the second suction hole 229 or its surroundings. Of the multiple first suction holes 219a and 219b, the first suction hole 219a is provided in the upstream suction region 213a, and the first suction hole 219b is provided in the downstream suction region 213b. The diameter of the first suction hole 219a is larger than the diameter of the first suction hole 219b.

[0095] Although not particularly limited, for example, the diameter of the first suction hole 219a is approximately 5 mm, the diameter of the first suction hole 219b is approximately 3 mm, the diameter of the second suction hole 229 is approximately 9 mm to approximately 10 mm, the diameter of the third suction hole 239a is approximately 5 mm, and the diameter of the third suction hole 239b is approximately 6 mm.

[0096] As described above, air is sucked into the suction chamber 221 corresponding to the suction region 223 via the piping 225 on the side surface in the -X direction. In this embodiment, in the suction region 223, the diameter of the second suction holes 229 closer to the +X direction is approximately 10 mm, and the diameter of the second suction holes 229 closer to the -X direction is approximately 9 mm. In other words, the diameter of the second suction holes 229 located relatively close to the suction fan (not shown) is smaller than the diameter of the second suction holes 229 located relatively far from the suction fan (not shown).

[0097] This balances the wind speed of the air being sucked in the suction chamber 221, reducing variations in the suction force of the multiple second suction holes 229. Furthermore, because variations in suction force are reduced, the humidified air passes through the transported web W relatively evenly, making it possible to humidify the web W while suppressing uneven distribution of moisture. The diameter 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 diameter of the second suction holes 229 in the middle region of the suction region 223 in the direction along the X axis is reduced.

[0098] 5, because the diameter of the first suction holes 219a is larger than the diameter of the first suction holes 219b, the volume of air Fa sucked into the first suction holes 219a is greater than the volume of air Fb sucked into the first suction holes 219b. As a result, the suction force in the upstream suction region 213a is greater than that in the downstream suction region 213b. Therefore, the web W can be steadily sucked from the mesh belt 611 of the accumulation and conveyance unit 61 onto the conveyance belt 621.

[0099] The partition wall 242 separates the upstream suction region 213a and the downstream suction region 213b. Therefore, the first suction holes 219a suck air Fa through the conveyor belt 621 in the range facing the upstream suction region 213a, and the first suction holes 219b suck air Fb through the conveyor belt 621 in the range facing the downstream suction region 213b. In other words, the first suction holes 219a have difficulty sucking 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.

[0100] In particular, when the downstream leading edge of the web W reaches the upstream suction region 213a, the first suction holes 219a stop sucking air from the range corresponding to the downstream suction region 213b. Therefore, the suction force of the first suction holes 219a is less likely to decrease, and the web W can be more reliably attracted to the conveyor belt 621.

[0101] According to this embodiment, the following effects can be obtained.

[0102] The frequency of maintenance work can be reduced. Specifically, the second suction holes 229 have a larger diameter than the first suction holes 219a, 219b and the third suction holes 239a, 239b. Therefore, even if moist fibers from the web W pass through, the fibers are less likely to adhere to the second suction holes 229, and clogging of the second suction holes 229 is suppressed. Therefore, it is possible to provide a sheet manufacturing apparatus 1 that reduces the frequency of maintenance work. [Explanation of symbols]

[0103] 1...sheet manufacturing apparatus, 50...deposition section, 70...sheet forming section, 200...suction section, 210...first duct, 213...suction area of ​​first duct, 213a...upstream suction area, 213b...downstream suction area, 219a, 219b...first suction hole, 220...second duct, 223...suction area of ​​second duct, 229...second suction hole, 230...third duct, 242...partition wall, 265...humidification section, 265a...discharge outlet, 621...conveyor belt, C...paper piece, P1...strip-shaped sheet, P3...sheet, W...web.

Claims

1. A sheet manufacturing apparatus for manufacturing a sheet from a material containing fiber, a deposition section for depositing the material by airflow to form a web; a conveyor belt that contacts one side of the web to hold the web and conveys the web along a conveyance direction; a suction unit provided above the conveyor belt and configured to suck the web onto the conveyor belt by suction; a humidifying unit provided opposite the conveyor belt and configured to add moisture to the other surface of the web; a sheet forming unit that pressurizes the web to form it into a sheet, the suction unit includes a first duct, a second duct provided downstream of the first duct in the conveying direction, and a third duct provided downstream of the second duct in the conveying direction, The humidifying unit has an outlet for discharging humidified air, The second duct and the exhaust port are disposed opposite to each other, a plurality of first suction holes for sucking air are provided in the suction region of the first duct; a plurality of second suction holes for sucking air are provided in the suction region of the second duct; The sheet manufacturing apparatus, wherein the diameter of the second suction hole is larger than the diameter of the first suction hole.

2. 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 conveying direction, 2. The sheet manufacturing apparatus according to claim 1, wherein, of the plurality of first suction holes, a diameter of the first suction hole provided in the upstream suction region is larger than a diameter of the first suction hole provided in the downstream suction region.

3. The sheet manufacturing apparatus according to claim 2 , further comprising a partition wall provided between the upstream suction region and the downstream suction region.

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