SHEET MANUFACTURING APPARATUS AND SHEET MANUFACTURING METHOD

Abstract

The sheet manufacturing apparatus includes a deposition portion configured to deposit a material containing a fiber to form a web, a web transport portion including a transport belt configured to hold and transport the web, a humidifier provided to face the transport belt and configured to apply moisture to the web, a sheet forming portion configured to perform at least one of heating and pressing on the web to which the moisture was applied, and a controller. The humidifier includes at least a first mist generation element and a second mist generation element, and the controller is configured to individually control the first mist generation element and the second mist generation element.

Description

The present application is based on, and claims priority from JP Application Serial Number 2023-086768, filed May 26, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a sheet manufacturing apparatus and a sheet manufacturing method.

2. Related Art

An apparatus that performs a heat treatment after applying moisture to a web as described in JP-A-2007-119943 has been known.

However, there is a possibility that moisture cannot appropriately be applied to the web in the above-described apparatus.

SUMMARY

A sheet manufacturing apparatus includes a deposition portion configured to deposit a material containing a fiber to form a web, a web transport portion including a transport belt configured to hold and transport the web, a humidifier provided to face the transport belt and configured to apply moisture to the web, a sheet forming portion configured to perform at least one of heating and pressing on the web to which the moisture was applied, and a controller. The humidifier includes at least a first mist generation element and a second mist generation element, and the controller is configured to individually control the first mist generation element and the second mist generation element.

A sheet manufacturing apparatus for manufacturing a sheet from a material containing a fiber includes a deposition portion configured to deposit a material containing the fiber to form a web, a web transport portion including a transport belt configured to hold and transport the web in a transport direction, a humidifier provided to face the transport belt and configured to apply moisture to the web, a sheet forming portion configured to perform at least one of heating and pressing on the web to which the moisture was applied, and a controller. The humidifier includes a plurality of mist generation elements arranged in line symmetry in a width direction of the web, and the controller is configured to individually control the plurality of mist generation elements in accordance with a condition corresponding to the line symmetry.

A sheet manufacturing method for a sheet manufacturing apparatus including at least a first mist generation element and a second mist generation element. The sheet manufacturing method includes depositing a material containing a fiber to form a web, transporting the web, applying moisture to the web by at least one of the first mist generation element and the second mist generation element configured to be individually controlled, and applying at least one of heating and pressing to the web to which the moisture was applied.

A sheet manufacturing method for a sheet manufacturing apparatus including a plurality of mist generation elements arranged in line symmetry in a width direction of a web. The sheet manufacturing method includes depositing a material containing a fiber to form the web, transporting the web, applying moisture to the web by individually controlling the plurality of mist generation elements in accordance with a condition corresponding to the line symmetry, and applying at least one of heating and pressing to the web to which the moisture was applied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a configuration of a sheet manufacturing apparatus.

FIG. 2 is a partially enlarged view illustrating a configuration around a humidifier.

FIG. 3 is a schematic view illustrating an arrangement of an odd number of mist generation elements.

FIG. 4 is a schematic view illustrating an arrangement of an even number of mist generation elements.

FIG. 5 is a flow chart illustrating a sheet manufacturing method of the sheet manufacturing apparatus.

FIG. 6 is a table illustrating a driving condition of the odd number of the mist generation elements.

FIG. 7 is a table illustrating a driving condition of the even number of the mist generation elements.

DESCRIPTION OF EMBODIMENTS

1. Configuration of Sheet Manufacturing Apparatus

A configuration of a sheet manufacturing apparatus 1 according to the present embodiment will be described with reference to FIGS. 1 to 4.

Directions in the drawings will be described using a three-dimensional coordinate system. For convenience of description, a positive direction of a Z-axis is referred to as an upward direction or simply an up side, a negative direction of the Z-axis is referred to as a downward direction or simply a down side, a positive direction of an X-axis is referred to as a rearward direction or simply a rear side, a negative direction of the X-axis is referred to as a forward direction or simply a front side, a positive direction of a Y-axis is referred to as a rightward direction or simply a right side, and a negative direction of the Y-axis is referred to as a leftward direction or simply a left side.

As illustrated in FIG. 1, a sheet manufacturing apparatus 1 according to the present embodiment is an apparatus that forms a web W from a raw material C which is a material including a fiber or the like in a so-called dry process, and manufactures a sheet S having a cut sheet shape. In the present embodiment, the term “dry process” refers to a process in which the sheet manufacturing is not performed in a liquid but is performed in a gas such as air. The sheet manufacturing apparatus 1 is not limited to using the dry process, and may use a so-called wet process.

In the following description, it is assumed that the raw material C moves from upstream to downstream in the sheet manufacturing apparatus 1 while sequentially changing the form from the web W to the sheet S.

The sheet manufacturing apparatus 1 includes a supply portion 5, a crusher 10, a defibrator 30, a mixer 60, a deposition portion 105, a web forming portion 70, a web transport portion 80, a temperature detector 41, a humidity detector 42, a thickness detector 43, a humidifier 90, a moisture meter 40, an air blower 150, a sheet forming portion 110, and a cutting portion 120 that are arranged from upstream to downstream in the sheet manufacturing apparatus 1. The humidifier 90 includes a water temperature detector 44 described later.

Furthermore, the sheet manufacturing apparatus 1 includes a controller 140 that integrally controls respective portions described above. The controller 140 includes a processor and a memory. The processor can control each portion of the sheet manufacturing apparatus 1 by reading and executing a program such as firmware stored in the memory.

The supply portion 5 supplies the raw material C to the crusher 10. The supply portion 5 includes an automatic feed mechanism 6, and continuously and automatically feeds the raw material C to the crusher 10. The raw material C includes various types of fibers or various types of fiber materials.

The various types of fibers are not particularly limited, and a wide variety of fibers can be used. Examples of the fibers include natural fibers (animal fibers and plant fibers) and chemical fibers (organic fibers, inorganic fibers, and organic-inorganic composite fibers). More specifically, fibers made of cellulose, silk, wool, cotton, hemp, kenaf, flax, ramie, jute, manila hemp, sisal hemp, coniferous trees, broadleaf trees, and the like are exemplified, and these may be used alone, may be appropriately mixed and used, or may be used as regenerated fibers subjected to purification or the like.

Examples of the fiber material include pulp, used paper, used cloth, and the like. Further, the fiber may be subjected to various surface treatments. The material of the fiber may be a pure substance, or may be a material containing a plurality of components such as impurities and other components. Further, defibrated material obtained by defibrating used paper, pulp sheets, or the like in a dry process may be used as the fiber.

A length of the fiber is not particularly limited, but the length in a longitudinal direction of one independent fiber is 1 μm or more and 5 mm or less, preferably 2 μm or more and 3 mm or less, and more preferably 3 μm or more and 2 mm or less.

In the sheet manufacturing apparatus 1, as will be described later, since moisture is applied to the web W at the humidifier 90, when a fiber capable of forming hydrogen bonds between fibrils is used, it is possible to increase the mechanical strength of the formed sheet S. Examples of such fiber include cellulose. In the following description, applying moisture to the web W by the humidifier 90 is also referred to as humidification.

The content of the fiber in the sheet S is, for example, 50 mass % or more and 99.9 mass % or less, preferably 60 mass % or more and 99 mass % or less, and more preferably 70 mass % or more and 99 mass % or less. As will be described later, such content can be obtained by performing predetermined blending when a mixture is formed in the mixer 60.

The crusher 10 cuts the raw material C supplied by the supply portion 5 into small pieces in a dry process in a gas such as air. The small piece is a few cm in size and a square in shape, for example. The crusher 10 includes a crushing blade 11, and can cut the fed raw material C by the crushing blade 11.

As the crusher 10, for example, a shredder can be used. The small pieces of the raw material C cut by the crusher 10 are transported to a fixed-quantity supply portion 15.

The fixed-quantity supply portion 15 measures the small pieces of the raw material C and supplies a fixed quantity thereof to a hopper 12. As the fixed-quantity supply portion 15, for example, a vibration feeder can be used. The small pieces of raw material C supplied to the hopper 12 are transported to an inlet 31 of the defibrator 30 through a pipe 20.

The defibrator 30 defibrates the small pieces of the raw material C in a dry process. The defibrator 30 includes the inlet 31, an outlet 32, a stator 33, and a rotor 34.

The stator 33 has a cylindrical shape. The rotor 34 rotates along a cylindrical inner surface of the stator 33. The stator 33 and the rotor 34 constitute a so-called impeller mill. The small pieces of the raw material C introduced from the inlet 31 rotate between the stator 33 and the rotor 34, and are defibrated by a shearing force generated therebetween. Entangled fibers are untangled by the defibrator 30, and a defibrated material is generated.

Further, the defibrator 30 can generate airflow which suctions the small pieces of the raw material C and discharges the defibrated material by the rotation of the rotor 34. As a result, the defibrator 30 can suck, from the inlet 31, the small pieces of the raw material C together with the airflow generated by the defibrator 30 itself, defibrate the small pieces, and discharge the defibrated material to the outlet 32.

The defibrated material that is defibrated by the defibrator 30 is transported from the outlet 32 to the mixer 60 through a pipe 67. Note that, the airflow generated by the defibrator 30 may be used as the airflow for transporting the defibrated material from the defibrator 30 to the deposition portion 105, or an airflow generation apparatus (not illustrated) such as a blower may separately be provided and the airflow thereof may be used.

The pipe 67 communicates with a pipe 68. The pipe 67 communicates with the inside of the defibrator 30, and the pipe 68 communicates with the inside of the deposition portion 105. The mixer 60 is disposed between the pipe 67 and the pipe 68, that is, between the defibrator 30 and the deposition portion 105.

The mixer 60 generates a mixture by mixing a binder or the like with defibrated material in a gas such as air. The mixer 60 includes hoppers 13 and 14, supply pipes 61 and 62, and valves 65 and 66.

The hoppers 13 and 14 may include a screw feeder (not illustrated), a disk feeder (not illustrated), and the like.

The hopper 13 communicates with the inside of the pipe 67 through the supply pipe 61. In the supply pipe 61, the valve 65 is provided between the hopper 13 and the pipe 67. The hopper 13 supplies the binder into the pipe 67. The valve 65 adjusts the weight of the binder supplied from the hopper 13 to the pipe 67. As a result, a mixing ratio of the defibrated material and the binder is adjusted.

The hopper 14 communicates with the inside of the pipe 67 through the supply pipe 62. In the supply pipe 62, the valve 66 is provided between the hopper 14 and the pipe 67. The hopper 14 supplies additives other than the binder into the pipe 67. The valve 66 adjusts the weight of the additives supplied from the hopper 14 to the pipe 67. As a result, a mixing ratio of the defibrated material and the additives is adjusted.

The binder and the additives are mixed with the defibrated material and become a mixture while being transported in the pipe 68 communicating with the pipe 67. The mixture is transported from the pipe 68 to the deposition portion 105.

An airflow generation apparatus (not illustrated) such as a blower may separately be provided, and the additives, the binder, and the defibrated material may be mixed in the pipe 68 by using the airflow thereof. Further, a mixing mechanism may separately be provided. For example, the mixing mechanism may be a mechanism for stirring with a blade rotating at high speed (not illustrated) or a mechanism using the rotation of a container such as a V-type mixer (not illustrated).

Here, the binder and the additives will be described. The binder is, for example, starch or dextrin. The starch is a polymer in which a plurality of a-glucose molecules are polymerized by glycosidic bonds. The starch may be linear or may include branching.

The starch derived from various plants can be used. Examples of raw materials of the starch include cereals such as corn, wheat, and rice, beans such as broad beans, mung beans, and adzuki beans, potatoes such as potatoes, sweet potatoes, and tapioca, wild grasses such as dogtooth violet, bracken, and kudzu, and palms such as sago palms.

Further, processed starch or modified starch may be used as the starch. Examples of the processed starch include acetylated distarch adipate, acetylated starch, oxidized starch, starch sodium octenyl succinate, hydroxypropyl starch, hydroxypropyl distarch phosphate, phosphorylated starch, phosphate esterified phosphate crosslinked starch, urea phosphate esterified starch, sodium starch glycolate, and high amylose corn starch. Furthermore, dextrin obtained by processing or modifying starch can be suitably used as the modified starch.

By using starch or dextrin as the binder in the sheet manufacturing apparatus 1, as will be described later, at least one of gelatinization of the binder and hydrogen bonds between the fibrils of the fiber occurs by pressing and heating the web W in the sheet forming portion 110 after moisture is applied to the web W in the humidifier 90, and it is possible to give sufficient strength to the sheet S to be manufactured.

On the other hand, when the sheet S can be provided with sufficient strength only by the hydrogen bonds between the fibrils of the fiber, the sheet S can be manufactured without using the binder. When the sheet S is manufactured without using the binder, the sheet manufacturing apparatus 1 need not be provided with the hopper 13 or the like.

The content of starch or dextrin in the sheet S is, for example, 0.1 mass % or more and 50 mass % or less, preferably 1 mass % or more and 40 mass % or less, and more preferably 1 mass % or more and 30 mass % or less. Such content can be obtained by adjusting the valve 65 of the mixer 60.

The additives supplied from the hopper 14 to the pipe 67 through the supply pipe 62 may include, depending on the type of the sheet S to be manufactured, agents such as a coloring agent for coloring the fiber, an aggregation inhibitor for inhibiting aggregation of the fiber and aggregation of the binder, and a flame retardant for making the fiber less likely to burn.

The additives are not an essential component. When the additives are not used, the hopper 14 or the like need not be provided.

Next, the deposition portion 105 includes, for example, a drum 106, a housing 107 that houses the drum 106, and the web forming portion 70.

The mixture mixed in the mixer 60 is transported to the deposition portion 105 through the pipe 68. The drum 106 introduces the mixture, untangles the entangled fibers and the like, and drops the mixture to the web forming portion 70 while dispersing the mixture in a gas such as air. As a result, the drum 106 can uniformly deposit the mixture on the web forming portion 70.

A rotatable cylindrical sieve is used as the drum 106, for example. The mixture is introduced from the pipe 68 to the inside of the cylindrical sieve of the drum 106.

The drum 106 has a net which is the cylindrical sieve. The drum 106 causes the fiber or a particle, contained in the mixture, smaller than the size of the openings of the net, to pass through from the inside to the outside of the cylindrical net rotated by a motor (not illustrated) and to fall onto the web forming portion 70.

Note that, the “sieve” of the drum 106 need not have a function of sorting a specific object. That is, the “sieve” used as the drum 106 refers to something including a net, and the drum 106 may cause all of the mixture introduced into the drum 106 to fall.

The web forming portion 70 forms the web W by depositing the mixture falling from the drum 106. The web forming portion 70 includes, for example, a first mesh belt 72, a plurality of tension rollers 74, and a first suction mechanism 76.

The mixture that has passed through the net of the drum 106 is deposited on the first mesh belt 72. The first mesh belt 72 is given tension by the tension rollers 74, and has a configuration in which it is difficult for the mixture to pass through and it is easy for air to pass through. The first mesh belt 72 is a so-called endless belt, and is circulated clockwise by the rotation of the tension rollers 74 driven by a motor (not illustrated). The mixture continuously falls from the drum 106 and deposits on the first mesh belt 72 while the first mesh belt 72 continuously moves, and thus the web W is formed on the first mesh belt 72.

The first suction mechanism 76 is provided below the first mesh belt 72. The first suction mechanism 76 can generate downward airflow. The mixture dispersed in the air by the drum 106 can be suctioned onto the first mesh belt 72 by the first suction mechanism 76. Further, discharge speed of the mixture from the deposition portion 105 can be increased by the first suction mechanism 76.

Furthermore, a downflow can be formed in a falling path of the mixture by the first suction mechanism 76, and this makes it possible to prevent the fiber, the binder, and the like from being entangled during falling.

In this way, the deposition portion 105 can form the web W by depositing the mixture containing the fiber by the airflow. By passing through the deposition portion 105, the binder or the like is further mixed with the fiber, and the web W in a soft and swollen state containing a large amount of air is formed.

The web transport portion 80 is disposed downstream of the web W on the first mesh belt 72. The web transport portion 80 transports the web W on the first mesh belt 72 in a transport direction T.

Specifically, the web transport portion 80 peels the web W from the first mesh belt 72 and transports the web W toward the sheet forming portion 110. In FIG. 1, the transport direction T is the rightward direction, and a direction opposite to the transport direction is the leftward direction.

Although the same configuration of the sheet manufacturing apparatus 1 is illustrated, the positive direction of the Y-axis is reversed in FIG. 2 with respect to FIG. 1 for convenience of description. That is, FIG. 1 is a front view of the sheet manufacturing apparatus 1, and FIG. 2 is a rear view of the humidifier 90 of the sheet manufacturing apparatus 1. For example, in FIG. 1, the transport direction T of the web W indicates the right side of the drawing, whereas in FIG. 2, the transport direction T indicates the left side of the drawing.

The web transport portion 80 and the humidifier 90 will be described with reference to FIG. 2. The web transport portion 80 includes a second mesh belt 81 which is a transport belt for transporting the web W, a plurality of rollers 82 for moving the second mesh belt 81, and a second suction mechanism 83 as a suction portion for sucking the web W.

The second mesh belt 81 is given tension by the plurality of rollers 82, and is configured to allow humidified air MA, which will be described later, to pass through. The second mesh belt 81 is an endless belt, and is configured to be able to circulate clockwise due to the rotation of the rollers 82 by a motor (not illustrated).

The second suction mechanism 83 is disposed at a position facing the web W from above with the second mesh belt 81 interposed therebetween. The second suction mechanism 83 is provided with a plurality of intake fans 86, and generates, by a suction force of the intake fans 86, upward airflow to the second mesh belt 81 in contact with the web W. The direction of the airflow is also a thickness direction of the web W. By this airflow, the web W is sucked from above through the second mesh belt 81, and the web W can be held below the second mesh belt 81.

More specifically, the second suction mechanism 83 has a plurality of suction ports 84 to suck the humidified air MA which will be described later. The second suction mechanism 83 has a suction duct 85 coupled to each of the plurality of suction ports 84.

The suction duct 85 is defined by a wall forming the suction port 84. A suction amount for the web W can be stabilized by the respective suction ducts 85 coupled to the plurality of suction ports 84.

By the web transport portion 80, the web W can be peeled from the first mesh belt 72, transferred to the second mesh belt 81, and transported in the transport direction T. One surface Wa is an upper surface of the web W and comes into contact with the second mesh belt 81, whereas the other surface Wb is a lower surface of the web W and does not come into contact with the second mesh belt 81.

That is, the one surface Wa of the web W is not in contact with the first mesh belt 72, but comes into contact with the second mesh belt 81. On the other hand, the other surface Wb of the web W is in contact with the first mesh belt 72, but does not come into contact with the second mesh belt 81.

As described above, when the web W is transported from the first mesh belt 72 to the second mesh belt 81, the other surface Wb is the surface in contact with the first mesh belt 72, but the one surface Wa is the surface in contact with the second mesh belt 81, and thus the surfaces of the web W in contact with the respective mesh belts are switched.

In the following description, an outer circumferential surface, which is an outer surface, of the second mesh belt 81 that is in contact with the one surface Wa of the web W is referred to as one surface, and an inner circumferential surface, which is an inner surface, of the second mesh belt 81 that is not in contact with the web W is referred to as the other surface.

When the one surface of the second mesh belt 81 faces downward, the web W is sucked by the second suction mechanism 83 and is attracted to the one surface of the second mesh belt 81. That is, the one surface of the second mesh belt 81 facing downward can hold the web W against gravity. Such second mesh belt 81 is also referred to as a back surface transport belt.

In this manner, the web W is transported in the transport direction T in a state that the one surface Wa is in contact with the one surface of the second mesh belt 81 below the second mesh belt 81.

At this time, the second suction mechanism 83 can stably suck the web W from the other surface of the second mesh belt 81. Although there is nothing supporting the web W from below, the web W is attracted to the second mesh belt 81 and does not fall off.

As illustrated in FIG. 2, the temperature detector 41, the humidity detector 42, the thickness detector 43, the humidifier 90, and the moisture meter 40 are arranged on the one surface side of the second mesh belt 81 of the web transport portion 80. Further, at least the thickness detector 43 and the humidifier 90 are arranged to face the second mesh belt 81 from below.

A lower portion of the humidifier 90 is covered with a case 99, and an upper portion thereof is covered with a duct 91. The humidifier 90 includes an air intake port 95a which is an air inlet, a tank 96 which is a water storage, a mist generation portion 97, and the duct 91. The duct 91 has an exhaust port 93a.

With reference to FIG. 2, a configuration of the humidifier 90 will be described from upstream to downstream in a flow path F. Flow of air A and the like along the flow path F in the humidifier 90 is generated based on a suction force of the second suction mechanism 83 positioned above the humidifier 90. Further, the flow path F includes an airflow path F1, a first flow path F2, a second flow path F3, and a third flow path F4 from upstream to downstream in the flow path F.

An air duct 95 takes the air A from the air intake port 95a, causes the air A to flow along the airflow path F1 in a direction opposite to the transport direction T of the web W, and exhausts the air A from an air exhaust port 95b.

The air intake port 95a is opened at a right surface of the case 99 so that the air A can smoothly flow toward the direction opposite to the transport direction T.

The tank 96 can store water L for generating mist. The air A exhausted from the air exhaust port 95b flows toward a surface of the water L stored in the tank 96. The air exhaust port 95b is opened at the lower left of the air duct 95 so that the air A can smoothly flow toward the surface of the water L in the tank 96.

Further, the tank 96 is provided with the water temperature detector 44 configured to detect the temperature of the stored water L.

The mist generation portion 97 for generating mist M from the water L is disposed at a bottom of the tank 96. Here, the mist generation portion 97 will be described in detail with reference to FIGS. 3 and 4. As examples in which the mist generation portion 97 includes a plurality of mist generation elements, FIG. 3 illustrates an example in which the number of the mist generation elements is an odd number, and FIG. 4 illustrates an example in which the number of the mist generation elements is an even number.

In the example of FIG. 3, the mist generation portion 97 includes five mist generation elements, that is, a first mist generation element 97a, a second mist generation element 97b, a third mist generation element 97c, a fourth mist generation element 97d, and a fifth mist generation element 97e.

The first mist generation element 97a to the fifth mist generation element 97e are arranged side by side in a width direction of the web W, which is a direction intersecting the transport direction T of the web W.

The first mist generation element 97a to the fifth mist generation element 97e are arranged so as to have line symmetry with respect to a first symmetry axis H1. In FIG. 3, since the first mist generation element 97a to the fifth mist generation element 97e, which are the odd number of five mist generation elements, are arranged, the first symmetry axis H1 is positioned at the third mist generation element 97c, which is the center mist generation element. The first symmetry axis H1 extends parallel to the transport direction T and in a direction intersecting the width direction of the web W.

The web W can be humidified more uniformly in the width direction by the first mist generation element 97a to the fifth mist generation element 97e which are the plurality of mist generation elements arranged so as to have line symmetry in the width direction of the web W.

The first mist generation element 97a to the fifth mist generation element 97e are, for example, piezoelectric vibrators. The piezoelectric vibrator is driven to vibrate, ultrasonic waves are generated in the water L, and the mist M is generated from the water L. The generated mist M rises from the surface of the water L in the tank 96.

The controller 140 can individually drive the first mist generation element 97a to the fifth mist generation element 97e, which are piezoelectric vibrators, by pulse width modulation (PWM) control. Specifically, the controller 140 can individually adjust a generation amount of the mist M by changing a duty of the pulse width of a driving pulse applied to the first mist generation element 97a to the fifth mist generation element 97e.

The duty of the pulse width refers to a ratio between a width of a High level which is ON and a width of a Low level which is OFF in a cycle of the driving pulse. Hereinafter, the duty of the pulse width of the driving pulse is referred to as a drive duty.

The mist generation element of the mist generation portion 97 need not be an element using ultrasonic waves such as a piezoelectric vibrator, and may be an element using, for example, steam, vaporization, or hot air vaporization. In these cases, the controller 140 can also individually control each element, and can adjust the generation amount of the mist M.

The mist M rising from the water surface of the water L in the tank 96 by the mist generation portion 97 flows with the air A flowing from the air exhaust port 95b toward the water surface of the water L, and the air A contains the mist M. Hereinafter, the air A containing the mist M is referred to as the humidified air MA.

In the example of FIG. 4, the mist generation portion 97 includes four mist generation elements, that is, the first mist generation element 97a, the second mist generation element 97b, the third mist generation element 97c, and the fourth mist generation element 97d.

The first mist generation element 97a to the fourth mist generation element 97d are arranged side by side in the width direction of the web W, which is the direction intersecting the transport direction T of the web W.

The first mist generation element 97a to the fourth mist generation element 97d are arranged so as to have line symmetry with respect to a second symmetry axis H2. In FIG. 4, since the first mist generation element 97a to the fourth mist generation element 97d, which are an even number of four mist generation elements, are arranged, the second symmetry axis H2 is positioned at a center between the second mist generation element 97b and the third mist generation element 97c, which are two mist generation elements adjacent to each other. The second symmetry axis H2 extends parallel to the transport direction T and in the direction intersecting the width direction of the web W.

The web W can be humidified more uniformly in the width direction by the plurality of mist generation elements from the first mist generation element 97a to the fourth mist generation element 97d arranged so as to have line symmetry in the width direction of the web W.

In the following description, it is assumed that the mist generation portion 97 includes five mist generation elements, that is, the first mist generation element 97a to the fifth mist generation element 97e, unless otherwise specified.

As described above, the mist generation portion 97 of the humidifier 90 includes the plurality of mist generation elements. That is, the mist generation portion 97 may include at least the first mist generation element 97a and the second mist generation element 97b. The controller 140 can individually control the first mist generation element 97a and the second mist generation element 97b, and can adjust the generation amount of the mist M of each of the mist generation elements.

With reference to FIG. 2 again, the description will be continued. The duct 91 through which the humidified air MA passes is provided between the tank 96 and the exhaust port 93a. The duct 91 includes a first duct 92 forming the first flow path F2, a second duct 93 forming the second flow path F3, and a third duct 94 forming the third flow path F4.

The first duct 92 is provided above the tank 96, and the second duct 93 extends in the transport direction T of the web W. The third duct 94 is provided between the second duct 93 and the exhaust port 93a, and extends in the direction intersecting the transport direction T of the web W. The transport direction T of the web W and the direction opposite to the transport direction T are, for example, a horizontal direction. The direction intersecting the transport direction T of the web W is, for example, a vertical direction.

The first duct 92 has a shape that swells above the tank 96 upstream of the first flow path F2, and that extends toward the second duct 93 in the transport direction T of the web W downstream of the first flow path F2. The first duct 92 has a shape in which the height decreases toward the second duct 93. With such shape, the first duct 92 forms a chamber C above the tank 96.

The humidified air MA flows upward along the wall of the first duct 92 from the surface of the water L in the tank 96, then bends while swirling in the chamber C of the first duct 92, and flows along the first flow path F2 toward the transport direction T. When the humidified air MA is swirled in the chamber C, flow velocity of the humidified air MA is particularly increased.

As a result, the air A and the mist M of the humidified air MA are mixed more uniformly. The humidified air MA can more uniformly humidify the web W.

As described above, the direction of at least part of the first flow path F2 of the first duct 92 is the transport direction T and is opposite to the direction of the airflow path F1.

Next, the humidified air MA is caused to flow along the second flow path F3 toward the transport direction T by the second duct 93 which communicates with the first duct 92. Then, the humidified air MA is caused to flow from the second flow path F3 along the third flow path F4 toward the upper side, which is the direction intersecting the transport direction T, while changing the direction thereof by the third duct 94 communicating with the second duct 93.

The humidified air MA is exhausted toward the web W above from the exhaust port 93a formed above the third duct 94.

The humidifier 90 is disposed so as to face the web transport portion 80 from below. Specifically, the exhaust port 93a of the humidifier 90 is disposed so as to face the one surface of the second mesh belt 81 of the web transport portion 80. The one surface Wa, which is the upper surface of the web W, comes into contact with the one surface of the second mesh belt 81.

The humidifier 90 can exhaust the humidified air MA from the exhaust port 93a toward the other surface Wb which is the lower surface of the web W in contact with the one surface of the second mesh belt 81, and can humidify the web W.

As described above, the mist generation portion 97 of the humidifier 90 may include at least the first mist generation element 97a and the second mist generation element 97b. The humidifier 90 can exhaust the humidified air MA containing the mist M generated by at least one of the first mist generation element 97a and the second mist generation element 97b to the web W from the exhaust port 93a through the duct 91, and can humidify the web W.

The exhaust port 93a has a rectangular shape. The side of the exhaust port 93a in the direction intersecting the transport direction T is longer than the width of the web W, and the humidified air MA can be exhausted to the entire width of the web W being transported. The exhaust port 93a is covered with a mesh surface formed of a metal net made of aluminum or the like. The mesh surface of the exhaust port 93a allows the humidified air MA to pass through the exhaust port 93a while reducing foreign matter such as a fiber entering the exhaust port 93a.

The humidifier 90 has a tray 98 positioned below the third duct 94. Foreign matter such as a fiber falling from the exhaust port 93a and entering the humidifier 90 passes through the third duct 94, and can be received and captured by the tray 98.

As described above, the humidifier 90 positioned below the web transport portion 80 can exhaust the humidified air MA from below the web W and humidify the web W, through the exhaust port 93a formed at an upper end of the third duct 94. Therefore, even when dew condensation occurs in the humidifier 90 or in the vicinity thereof, water droplets do not fall onto the web W.

As a result, uneven humidification of the web W can be reduced, and effects on the quality of the sheet S can be reduced.

Here, a configuration of the second suction mechanism 83 and the configuration of the humidifier 90 will be described in more detail.

The second suction mechanism 83 is disposed at a position facing the humidifier 90 with the second mesh belt 81 interposed therebetween, the position being on the other surface side of the second mesh belt 81. Specifically, the suction port 84 of the second suction mechanism 83 and the exhaust port 93a of the humidifier 90 are arranged so as to face each other with the second mesh belt 81 interposed therebetween.

The humidified air MA exhausted from the exhaust port 93a of the humidifier 90 can be sucked in the thickness direction of the web W by the suction duct 85.

In this way, the humidified air MA exhausted from the exhaust port 93a is sucked, via the second mesh belt 81, from the suction port 84 facing the exhaust port 93a through the suction duct 85. Then, the humidified air MA can pass through toward the thickness direction of the web W in contact with the one surface of the second mesh belt 81.

As a result, the humidified air MA can humidify the web W so that a moisture amount in the thickness direction of the web W becomes more uniform.

The plurality of suction ports 84 are coupled to the corresponding suction ducts 85 respectively and can function independently. The second suction mechanism 83 can make air volume of the humidified air MA passing through the web W directly above the exhaust port 93a constant. As a result, the amount of moisture applied to the web W being transported is made more uniform, variation in the strength of the sheet S can be reduced, and the quality of the sheet S can be ensured.

As described above, the suction duct 85 of the second suction mechanism 83 can make the web W be attracted to the second mesh belt 81 by suction.

Therefore, when the web W is transferred from the first mesh belt 72 of the web forming portion 70 to the second mesh belt 81 of the web transport portion 80, the second suction mechanism 83 can peel the web W from the first mesh belt 72 and make the web W be attracted to the second mesh belt 81.

Here, the temperature detector 41, the humidity detector 42, the thickness detector 43, and the moisture meter 40 which constitute a sensor group will be described. The sensor group also includes the water temperature detector 44 provided in the tank 96 of the humidifier 90.

The temperature detector 41, the humidity detector 42, and the thickness detector 43 are arranged adjacent to the humidifier 90 at upstream positions in the transport direction T with respect to the humidifier 90. The moisture meter 40 is disposed adjacent to the humidifier 90 at a downstream position in the transport direction T with respect to the humidifier 90. It should be noted that the position of the humidifier 90 here specifically indicates the position of the exhaust port 93a.

As will be described later, the controller 140 can control, based on the measurement result of at least one of the sensors in the sensor group, the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 of the humidifier 90 to humidify the web W.

In the following description, measurement by the temperature detector 41, the humidity detector 42, the thickness detector 43, the moisture meter 40, and the water temperature detector 44, which constitute the sensor group, is also referred to as detection.

The temperature detector 41 can detect the temperature around the humidifier 90. As the temperature detector 41, for example, any one of a resistance temperature detector, a linear resistor, and a thermistor can be used.

Further, the water temperature detector 44 may also use the same as the above. The water temperature detector 44 can detect the temperature of the water L in the tank 96.

The humidity detector 42 can detect the humidity around the humidifier 90. The humidity detector 42 may be, for example, either of a resistance change type or a capacitance change type.

The thickness detector 43 can detect the height of the web W from the second mesh belt 81. The thickness detector 43 can detect the thickness of the web W by using, for example, a non-contact displacement gauge.

As the displacement gauge, for example, one of an optical displacement gauge, an eddy current displacement gauge, an ultrasonic displacement gauge, a laser displacement gauge, and a contact displacement gauge can be used.

The moisture meter 40 can detect moisture contained in the web W. The moisture meter 40 is, for example, an infrared moisture meter configured to detect moisture in a non-contact manner. In this case, the moisture meter 40 can detect moisture contained in the web W by irradiating the other surface Wb of the web W with an infrared ray and receiving the returned infrared ray. The moisture meter 40 can use, for example, microwaves other than the infrared ray.

The thickness detector 43 and the moisture meter 40 are arranged at positions where nothing is interposed between the web W and the thickness detector 43 and moisture meter 40 so that the infrared ray or the like for detection is not affected. Specifically, these are arranged below the web W so that the second mesh belt 81 and the like are not interposed.

The controller 140 acquires the moisture content of the web W by the moisture meter 40, controls the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 of the humidifier 90 so that the web W has a prescribed moisture content, and can adjust the generation amount of the mist M included in the humidified air MA.

Specifically, the memory of the controller 140 stores the drive duty of the first mist generation element 97a to the fifth mist generation element 97e corresponding to the moisture content of the web W acquired by the moisture meter 40. The controller 140 can individually control the first mist generation element 97a to the fifth mist generation element 97e based on the drive duty corresponding to the acquired moisture content of the web W, and can humidify the web W to have the prescribed moisture content.

The moisture meter 40 can detect, downstream of the humidifier 90, moisture contained in the web W humidified by the humidifier 90. When the web transport portion 80 starts transporting the web W in the transport direction T, a leading end portion of the web W reaches the position of the exhaust port 93a of the humidifier 90 in the upstream position, then reaches the position of the moisture meter 40 in the downstream position.

That is, when the humidification is started by the humidifier 90, the leading end portion of the web W has not yet reached the position of the moisture meter 40.

Therefore, when starting the humidification by the humidifier 90, the controller 140 controls the mist generation portion 97 of the humidifier 90 by using the detection result of at least one of the temperature detector 41, the humidity detector 42, the thickness detector 43, and the water temperature detector 44 except the moisture meter 40, and starts the humidification of the web W.

Further, the controller 140 may control the mist generation portion 97 of the humidifier 90 by using any combination of these detection results.

As an example, the controller 140 can control the mist generation portion 97 to humidify the web W based on the temperature detected by the temperature detector 41.

For example, the controller 140 can individually control the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 such that the generation amount of the mist M is increased when the temperature is low compared to a case when the temperature is high.

Similarly, the controller 140 can humidify the web W by controlling the mist generation portion 97 based on the water temperature of the water L detected by the water temperature detector 44.

For example, the controller 140 can individually control the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 so that the generation amount of the mist M is increased when the water temperature is low compared to a case when the water temperature is high.

Further, the controller 140 can humidify the web W by controlling the mist generation portion 97 based on the humidity detected by the humidity detector 42.

For example, the controller 140 can individually control the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 so that the generation amount of the mist M is increased when the humidity is low compared to a case when the humidity is high.

Further, the controller 140 can humidify the web W by controlling the mist generation portion 97 based on the thickness of the web W detected by the thickness detector 43.

For example, the controller 140 can individually control the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 so that the generation amount of the mist M is increased when the web W is thick compared to a case when the web W is thin.

The memory of the controller 140 stores the drive duties of the first mist generation element 97a to the fifth mist generation element 97e corresponding to each of the temperature, the humidity, the thickness of the web W, and the water temperature of the water L. Further, the memory of the controller 140 may store the drive duties of the first mist generation element 97a to the fifth mist generation element 97e corresponding to any combination thereof.

When starting the humidification of the web W, the controller 140 can individually control the first mist generation element 97a to the fifth mist generation element 97e based on the drive duty corresponding to at least one of the detected values. The controller 140 can appropriately generate the mist M regardless of the detection result of the moisture meter 40, and can start the humidification of the web W.

The leading end of the web W reaches the position of the moisture meter 40, then, the moisture meter 40 can detect the moisture of the humidified web W. After that, the controller 140 switches control to humidify the web W by controlling the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 based on the moisture content of the web W acquired by the moisture meter 40.

At this time, the controller 140 may control the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 by using any combination of the temperature, the humidity, the thickness of the web W, and the water temperature of the water L, in addition to the moisture content of the web W.

The sheet manufacturing apparatus 1 may include at least one or more sensors of the sensor group described above. That is, at least one of the temperature detector 41, the humidity detector 42, the thickness detector 43, the water temperature detector 44, and the moisture meter 40, which are sensors, may be included.

As described above, the mist generation portion 97 of the humidifier 90 may include at least the first mist generation element 97a and the second mist generation element 97b.

In this case, the controller 140 can individually control the first mist generation element 97a and the second mist generation element 97b based on the detection result of at least one of the sensors. Specifically, the controller 140 can perform control to apply a drive duty to at least one of the first mist generation element 97a and the second mist generation element 97b.

The moisture content of the web W is preferably 12 mass % or more and 40 mass % or less. The controller 140 controls the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 so that the moisture content of the web W is in the prescribed range described above.

As a result, the controller 140 can effectively form hydrogen bonds between the fibrils of the fiber of the web W, and can increase the strength of the sheet S.

Next, as illustrated in FIGS. 1 and 2, the sheet forming portion 110 is disposed downstream of the web transport portion 80 and the humidifier 90 in the transport direction T. The humidified web W is transported to the sheet forming portion 110.

The web W that is peeled off from the second mesh belt 81 is continuous with the upstream web W. Since the upstream web W is transported by the second mesh belt 81, the peeled web W also is pushed by the upstream web W, and is continuously transported in the transport direction T. Thus, the web W peeled off from the second mesh belt 81 can reach the sheet forming portion 110.

For example, the sheet forming portion 110 is configured to heat the web W at the same time as pressing the web W. By the sheet forming portion 110, the moisture contained in the humidified web W evaporates after the temperature rises and the thickness of the web W reduces, and thus fiber density can be increased.

The temperature of the moisture and the binder is increased by heat, and the fiber density is increased by pressure, whereby the binder is gelatinized, and thereafter, the moisture is evaporated, whereby the fibers are bonded to each other via the gelatinized binder. Further, moisture is evaporated by heat, and the fiber density is increased by pressure, whereby the fibers are bonded by hydrogen bonds between the fibrils. With this, the sheet S having high mechanical strength and preferable quality can be formed.

In this case, the sheet forming portion 110 specifically includes a pressing and heating portion 114 that presses and heats the web W. The pressing and heating portion 114 can be configured by using, for example, a heating roller or a heat press molding machine. Here, the pressing and heating portion 114 is constituted by a heating roller pair 116.

The heating of the web W by the heating roller pair 116 is preferably performed so that the temperature of the web W is 60° C. or more and 100° C. or less.

The pressure applied to the web W by the heating roller pair 116 is preferably 0.1 MPa or more and 15 MPa or less, more preferably 0.2 MPa or more and 10 MPa or less, and still more preferably 0.4 MPa or more and 8 MPa or less.

When the pressure is in the range described above, deterioration of the fiber can be reduced, and the sheet S with appropriate strength can be manufactured again by using defibrated material obtained by defibrating the manufactured sheet S as a raw material.

The sheet forming portion 110 may be configured to perform at least one of heating and pressing. The sheet forming portion 110 can form the sheet S by performing at least one of heating and pressing.

The sheet forming portion 110 can bind the fibers to each other through the binder and form the sheet S compressed in a sheet shape by performing at least one of heating and pressing.

Further, two or more heating roller pairs 116 may be provided, and the number thereof is not particularly limited. The heating roller pair 116 may apply pressure and heat to the web W at the same time, or may apply only one of the pressure and heat to the web W.

Further, the sheet forming portion 110 may be configured to include a pressure roller and a transport belt (for example, a mesh belt).

The sheet S that is formed by the sheet forming portion 110 has a continuous sheet shape. As illustrated in FIG. 1, the cutting portion 120 cuts the sheet S in the continuous sheet shape.

The cutting portion 120 includes a first cutting portion 122 that cuts the sheet S in the width direction which is the direction intersecting the transport direction T of the sheet S, and a second cutting portion 124 that cuts the sheet S in a length direction which is a direction parallel to the transport direction T. After the first cutting portion 122 cuts the sheet S in the width direction, the second cutting portion 124 cuts the sheet S in the length direction.

The sheet S in the cut sheet shape, which has been cut, is discharged to a discharge receiving portion 130. In this way, the sheet S in the cut sheet shape having a predetermined size is manufactured.

2. Sheet Manufacturing Method

Next, a sheet manufacturing method using the sheet manufacturing apparatus 1 according to the present embodiment will be described with reference to the steps illustrated in the flowchart of FIG. 5. The configuration of the sheet manufacturing apparatus 1 that performs the sheet manufacturing method is as described above with reference to FIGS. 1 to 4. The controller 140 controls each portion to execute each step.

In the sheet manufacturing apparatus 1, a raw material C such as a fiber is supplied by the supply portion 5 (S110). In the sheet manufacturing apparatus 1, the supplied raw material C is cut by the crusher 10, defibrated by the defibrator 30, and mixed with a binder or the like by the mixer 60, the mixture is deposited using the airflow of the first suction mechanism 76 of the deposition portion 105, and a web W is formed in the web forming portion 70 (S111).

The web transport portion 80 transports the web W in the transport direction T by the plurality of rollers 82 while sucking the web W from above by the second suction mechanism 83 through the second mesh belt 81 (S112).

The moisture meter 40 detects moisture contained in the web W (S113). Specifically, the controller 140 acquires the moisture content of the web W by the moisture meter 40.

The controller 140, then, controls the first mist generation element 97a to the fifth mist generation element 97e of the mist generation portion 97 of the humidifier 90 so that the web W has a prescribed moisture content (S114). The controller 140 humidifies the web W by adjusting the generation amount of the mist M included in the humidified air MA by the humidifier 90 (S115).

As described above, when the leading end portion of the web W has not yet reached the position of the moisture meter 40, the controller 140 can control the first mist generation element 97a to the fifth mist generation element 97e by using the detection result of at least one sensor in the sensor group excluding the moisture meter 40 to humidify the web W.

When the leading end portion of the humidified web W reaches the position of the moisture meter 40, the controller 140 switches control to control using the detection result of the moisture meter 40.

Here, a specific example in which the controller 140 controls each mist generation element will be described with reference to FIGS. 6 and 7.

FIGS. 6 and 7 each illustrate an example of the drive duty, which is a drive condition for each mist generation element, applied by the controller 140. FIG. 6 is an example of a driving condition corresponding to the odd number of the first mist generation element 97a to the fifth mist generation element 97e illustrated in FIG. 3, and FIG. 7 is an example of a driving condition corresponding to the even number of the first mist generation element 97a to the fourth mist generation element 97d illustrated in FIG. 4.

The drive duty of each mist generation element illustrated in FIGS. 6 and 7 is an example of a value corresponding to a predetermined moisture content of the web W acquired by the controller 140 using the moisture meter 40. Further, the drive duty may be an example of a value corresponding to a detection result by at least one sensor in the sensor group excluding the moisture meter 40.

Further, the drive duty applied to each mist generation element can be corresponding to each generation amount of the mist M. The mist generation element can generate a larger amount of the mist M as the value of the drive duty increases.

As illustrated in FIG. 6, in combination 1, the drive duties for the first mist generation element 97a, the second mist generation element 97b, the third mist generation element 97c, the fourth mist generation element 97d, and the fifth mist generation element 97e are 33%, OFF, 33%, OFF, and 33%, respectively.

In combination 2, the drive duties for the first mist generation element 97a, the second mist generation element 97b, the third mist generation element 97c, the fourth mist generation element 97d, and the fifth mist generation element 97e are OFF, 50%, OFF, 50%, and OFF, respectively.

In this manner, in the combination 1 and the combination 2, the values of the respective drive duties of the first mist generation element 97a to the fifth mist generation element 97e are set to have the same relationship as the line symmetry with respect to the first symmetry axis H1 illustrated in FIG. 3.

That is, in the combination 1, the drive duty of the third mist generation element 97c positioned at the center of the line symmetry with respect to the first symmetry axis H1 illustrated in FIG. 3 is 33%, and both the second mist generation element 97b and the fourth mist generation element 97d adjacent to the third mist generation element 97c are OFF. The first mist generation element 97a and the fifth mist generation element 97e at both ends each have the same value as that of the third mist generation element 97c, that is 33%.

In the combination 2 as well, 33% and OFF are interchanged with respect to the combination 1, but the relationship of the line symmetry is the same as in the combination 1.

The controller 140 can individually adjust the generation amount of the mist M by applying the drive duties as illustrated in the combination 1 or the combination 2 to the first mist generation element 97a to the fifth mist generation element 97e, respectively.

Further, the drive duties illustrated in the combination 1 and the combination 2 for the first mist generation element 97a to the fifth mist generation element 97e have values having the same relationship as the line symmetry with respect to the first symmetry axis H1.

In other words, the controller 140 can individually control each of the first mist generation element 97a to the fifth mist generation element 97e under the condition of the drive duties corresponding to the line symmetry with respect to the first symmetry axis H1.

Specifically, in the combination 1, the drive duty of each of the first mist generation element 97a, the third mist generation element 97c, and the fifth mist generation element 97e is 33%. Each of the first mist generation element 97a, the third mist generation element 97c, and the fifth mist generation element 97e can generate an amount of the mist M corresponding to 33%. On the other hand, the second mist generation element 97b and the fourth mist generation element 97d each are OFF and do not generate the mist M.

Further, the mist generation portion 97 can generate, by the first mist generation element 97a to the fifth mist generation element 97e, an amount of the mist M corresponding to 99%, which is the summed drive duty obtained by summing the drive duties of the first mist generation element 97a to the fifth mist generation element 97e.

In the combination 2, the drive duty of each of the second mist generation element 97b and the fourth mist generation element 97d is 50%. Each of the second mist generation element 97b and the fourth mist generation element 97d can generate an amount of the mist M corresponding to 50%. On the other hand, the first mist generation element 97a, the third mist generation element 97c, and the fifth mist generation element 97e each are OFF and do not generate the mist M.

Further, the mist generation portion 97 can generate, by the first mist generation element 97a to the fifth mist generation element 97e, an amount of the mist M corresponding to 100%, which is the drive duty obtained by summing the drive duties of the first mist generation element 97a to the fifth mist generation element 97e.

Since the summed drive duty at the time of the combination 1 is 99%, the mist generation portion 97 can generate substantially the same amount of the mist M in the combination 1 and the combination 2.

As illustrated in FIG. 3, the first mist generation element 97a to the fifth mist generation element 97e are arranged side by side in the width direction of the web W. Further, the values of the respective drive duties are set to have the same relationship as the line symmetry. The mist generation portion 97 can generate the mist M more uniformly in the width direction of the web W to humidify the web W.

Next, as illustrated in FIG. 7, in combination 3, the drive duties for the first mist generation element 97a, the second mist generation element 97b, the third mist generation element 97c, and the fourth mist generation element 97d are 50%, OFF, OFF, and 50%, respectively.

In combination 4, the drive duties for the first mist generation element 97a, the second mist generation element 97b, the third mist generation element 97c, and the fourth mist generation element 97d are OFF, 50%, 50%, and OFF, respectively.

In this manner, in the combination 3 and the combination 4, the values of the respective drive duties of the first mist generation element 97a to the fourth mist generation element 97d are set to have the same relationship as the line symmetry with respect to the second symmetry axis H2 illustrated in FIG. 4.

That is, in the combination 3, both the second mist generation element 97b and the third mist generation element 97c adjacent to each other at a center of the line symmetry with respect to the second symmetry axis H2 illustrated in FIG. 4 are OFF. The drive duties for both the first mist generation element 97a and the fourth mist generation element 97d at both ends are 50%.

In the combination 4 as well, 50% and OFF are interchanged with respect to the combination 3, but the relationship of the line symmetry is the same as in the combination 3.

The controller 140 can individually adjust the generation amount of the mist M by applying the drive duties as illustrated in the combination 3 or the combination 4 to the first mist generation element 97a to the fourth mist generation element 97d, respectively.

Further, the drive duties illustrated in the combination 3 and the combination 4 for the first mist generation element 97a to the fourth mist generation element 97d have values having the same relationship as the line symmetry with respect to the second symmetry axis H2.

In other words, the controller 140 can individually control each of the first mist generation element 97a to the fourth mist generation element 97d under the condition of the drive duties corresponding to the line symmetry with respect to the second symmetry axis H2.

In the combination 3, the drive duty of each of the first mist generation element 97a and the fourth mist generation element 97d is 50%. Each of the first mist generation element 97a and the fourth mist generation element 97d can generate an amount of the mist M corresponding to 50%. On the other hand, the second mist generation element 97b and the third mist generation element 97c each are OFF and do not generate the mist M.

The mist generation portion 97 can generate an amount of the mist M corresponding to 100%, which is the summed drive duty, by the first mist generation element 97a to the fourth mist generation element 97d.

In the combination 4, the drive duty of each of the second mist generation element 97b and the third mist generation element 97c is 50%. Each of the second mist generation element 97b and the third mist generation element 97c can generate an amount of the mist M corresponding to 50%. On the other hand, the first mist generation element 97a and the fourth mist generation element 97d each are OFF and do not generate the mist M.

The mist generation portion 97 can generate, by the first mist generation element 97a to the fourth mist generation element 97d, an amount of the mist M corresponding to 100%, which is the summed drive duty obtained by summing the drive duties of the first mist generation element 97a to the fourth mist generation element 97d.

Since the summed drive duty at the time of the combination 3 is also 100%, the mist generation portion 97 can generate substantially the same amount of the mist M in the combination 3 and the combination 4.

As illustrated in FIG. 4, the first mist generation element 97a to the fourth mist generation element 97d are arranged side by side in the width direction of the web W. Further, the values of the respective drive duties are set to have the same relationship as the line symmetry. The mist generation portion 97 can generate the mist M more uniformly in the width direction of the web W to humidify the web W.

As described above, the mist generation portion 97 of the humidifier 90 may include at least the first mist generation element 97a and the second mist generation element 97b. The controller 140 can individually control the first mist generation element 97a and the second mist generation element 97b, and can adjust the generation amount of the mist M of each of the mist generation elements.

The moisture content of the web W is preferably 12 mass % or more and 40 mass % or less. The controller 140 can perform control such that the moisture content of the web W is in the prescribed range described above by applying each drive duty to the first mist generation element 97a to the fifth mist generation element 97e or the first mist generation element 97a to the fourth mist generation element 97d of the mist generation portion 97.

As a result, the controller 140 can more uniformly humidify the web W so that the moisture content of the web W falls within the prescribed range.

Next, the controller 140 causes the sheet forming portion 110 to perform heating and pressing on the web W humidified by the humidifier 90 (S116) to form the sheet S. The sheet forming portion 110 may perform at least one of heating and pressing on the web W to form the sheet S. At this time, the sheet S is formed in a continuous sheet shape.

The controller 140 cuts the sheet Sin the continuous sheet shape by the cutting portion 120 to manufacture the sheet S in a cut sheet shape having a predetermined size (S117).

In this way, the sheet manufacturing apparatus 1 can more uniformly humidify the web W by the humidifier 90, and can set the moisture content of the web W within the prescribed range. As a result, the sheet manufacturing apparatus 1 can effectively form hydrogen bonds between the fibrils of the fiber of the web W and manufacture the sheet S with high strength.

Although these embodiments have been described in detail with reference to the drawings, specific configurations are not limited to these embodiments, and changes, substitutions, deletions, and the like may be made without departing from the gist of the present disclosure.

For example, although FIG. 3 illustrates an example in which the number of mist generation elements constituting the mist generation portion 97 is five as an odd number, the number may be another odd number except one, and although FIG. 4 illustrates an example in which the number is four as an even number, the number may be another even number.

In addition to the moisture meter 40, the sensor group may include at least one of the temperature detector 41, the humidity detector 42, the thickness detector 43, and the water temperature detector 44.

Further, in any of the combinations 1 to 4 of FIGS. 6 and 7, the drive duties of respective mist generation elements may have the same value. Further, each drive duty can be set to any value and need not be OFF.

Claims

1. A sheet manufacturing apparatus, comprising:

a deposition portion configured to deposit a material containing a fiber to form a web;

a web transport portion including a transport belt configured to hold and transport the web;

a humidifier provided to face the transport belt and configured to apply moisture to the web;

a sheet forming portion configured to perform at least one of heating and pressing on the web to which the moisture was applied; and

a controller, wherein

the humidifier includes at least a first mist generation element and a second mist generation element, and

the controller is configured to individually control the first mist generation element and the second mist generation element.

2. The sheet manufacturing apparatus according to claim 1, wherein

the humidifier includes

a duct and an exhaust port, and

mist generated by at least one of the first mist generation element and the second mist generation element is exhausted from the exhaust port to the web through the duct.

3. The sheet manufacturing apparatus according to claim 1, further comprising

one or more sensors, wherein

the controller is configured to control at least one of the first mist generation element and the second mist generation element based on a result measured by the sensors.

4. The sheet manufacturing apparatus according to claim 1, further comprising

a moisture meter configured to measure moisture of the web, wherein

the controller is configured to individually control the first mist generation element and the second mist generation element based on the moisture of the web measured by the moisture meter.

5. The sheet manufacturing apparatus according to claim 1, further comprising

a temperature detector configured to measure temperature, wherein

the controller is configured to individually control the first mist generation element and the second mist generation element based on the temperature measured by the temperature detector.

6. The sheet manufacturing apparatus according to claim 1, further comprising

a humidity detector configured to measure humidity, wherein

the controller is configured to individually control the first mist generation element and the second mist generation element based on the humidity measured by the humidity detector.

7. The sheet manufacturing apparatus according to claim 1, further comprising

a thickness detector configured to measure a thickness of the web, wherein

the controller is configured to individually control the first mist generation element and the second mist generation element based on the thickness of the web measured by the thickness detector.

8. The sheet manufacturing apparatus according to claim 1, further comprising

a water temperature detector configured to measure water temperature of water stored in the humidifier and used for generating mist, wherein

the controller is configured to individually control the first mist generation element and the second mist generation element based on the water temperature measured by the water temperature detector.

9. A sheet manufacturing apparatus for manufacturing a sheet from a material containing a fiber, the sheet manufacturing apparatus comprising:

a deposition portion configured to deposit a material containing the fiber to form a web;

a web transport portion including a transport belt configured to hold and transport the web in a transport direction;

a humidifier provided to face the transport belt and configured to apply moisture to the web;

a sheet forming portion configured to perform at least one of heating and pressing on the web to which the moisture was applied; and

a controller, wherein

the humidifier includes a plurality of mist generation elements arranged in line symmetry in a width direction of the web, and

the controller is configured to individually control the plurality of mist generation elements in accordance with a condition corresponding to the line symmetry.

10. A sheet manufacturing method for a sheet manufacturing apparatus including at least a first mist generation element and a second mist generation element, the sheet manufacturing method comprising:

depositing a material containing a fiber to form a web;

transporting the web;

applying moisture to the web by at least one of the first mist generation element and the second mist generation element configured to be individually controlled; and

applying at least one of heating and pressing to the web to which the moisture was applied.

11. A sheet manufacturing method for a sheet manufacturing apparatus including a plurality of mist generation elements arranged in line symmetry in a width direction of a web, the sheet manufacturing method comprising:

depositing a material containing a fiber to form the web;

transporting the web;

applying moisture to the web by individually controlling the plurality of mist generation elements in accordance with a condition corresponding to the line symmetry; and

applying at least one of heating and pressing to the web to which the moisture was applied.