SHEET MANUFACTURING APPARATUS AND SHEET PRODUCTION METHOD

Abstract

A sheet manufacturing apparatus includes a defibrator that defibrates a paper piece to form a defibrated material, an accumulator that accumulates the defibrated material on a mesh belt to form an accumulating material, a forming machine that forms the transported accumulating material to produce a strip-shaped sheet, and a return mechanism that sends a residual accumulating material that is the defibrated material being accumulating to the defibrator on condition that the accumulator has stopped or is stopped during accumulation.

Claims

1. A sheet manufacturing apparatus comprising: a defibrator that defibrates a fiber material to form a defibrated material; an accumulator that accumulates the defibrated material on a transport body to form an accumulating material; a forming machine that forms the transported accumulating material to produce a sheet; and a return mechanism that sends a residual accumulating material that is the defibrated material being accumulating to the defibrator on condition that the accumulator has stopped or is stopped during accumulation.

2. The sheet manufacturing apparatus according to claim 1, wherein the return mechanism includes a box that stores the residual accumulating material.

3. The sheet manufacturing apparatus according to claim 1, wherein the return mechanism sucks air from a position of the accumulator and blows out the air at a position of the defibrator, and the residual accumulating material is sent to the defibrator by a wind force through an inside of a tube of the return mechanism.

4. The sheet manufacturing apparatus according to claim 3, wherein in the return mechanism, the tube has a circular cross section.

5. The sheet manufacturing apparatus according to claim 1, wherein the transport body transports the residual accumulating material toward the return mechanism in response to accumulation of the defibrated material being stopped.

6. The sheet manufacturing apparatus according to claim 1, wherein at a time of restart after a stop instruction is received during accumulation, the accumulator accumulates the defibrated material defibrated from the residual accumulating material at a time of previous stop before the accumulating material having a predetermined size.

7. The sheet manufacturing apparatus according to claim 6, wherein the forming machine discards an accumulating material derived from the residual accumulating material and then forms the accumulating material having the predetermined size to produce a sheet.

8. The sheet manufacturing apparatus according to claim 1, wherein when a stop instruction is given by a user, the residual accumulating material is sent to the defibrator, and then an operation is stopped.

9. The sheet manufacturing apparatus according to claim 2, wherein when a stop instruction is given by a user, the residual accumulating material is not sent to the defibrator but is stored in the box, and an operation is stopped.

10. The sheet manufacturing apparatus according to claim 1, wherein in the accumulator, an accumulation amount of the defibrated material immediately after start of accumulation has a large variation compared to an accumulation amount of the defibrated material after a predetermined time has elapsed from the start of accumulation.

11. The sheet manufacturing apparatus according to claim 10, wherein the accumulation amount of the defibrated material immediately after the start of accumulation includes a variation of 5% or more in thickness.

12. A sheet production method comprising: defibrating a fiber material to form a defibrated material; accumulating the defibrated material on a transport body to form an accumulating material; and forming the transported accumulating material to produce a sheet, wherein a residual accumulating material that is the defibrated material being accumulating is returned to a defibrator and accumulates on the transport body in response to an instruction to stop accumulation given during accumulation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a schematic diagram illustrating a configuration of a sheet manufacturing apparatus according to an embodiment.

[0008] FIG. 2 is a perspective view illustrating a form of a merging unit and the like.

[0009] FIG. 3 is a flowchart illustrating a sheet production method.

[0010] FIG. 4 is a schematic diagram illustrating a thickness of an accumulating material and a thickness of a residual accumulating material.

[0011] FIG. 5 is a schematic diagram illustrating a positional relationship or the like between the accumulating material and the residual accumulating material.

DESCRIPTION OF EMBODIMENTS

[0012] In the following embodiment, a sheet manufacturing apparatus 1 that produces a sheet by a dry process from a fiber material such as used paper containing fibers and a sheet production method using the sheet manufacturing apparatus 1 will be exemplified and described with reference to the drawings. The sheet manufacturing apparatus of the present disclosure is not limited to a dry type and may be a wet type. In the present specification, dry type means not to be performed in a liquid but to be performed in air such as the atmosphere.

[0013] In each of the following drawings, XYZ-axes are given as coordinate axes orthogonal to each other, a direction indicated by each arrow is set as a positive direction, and a direction opposite to the positive direction is set as a negative direction. The Z-axis is a virtual axis extending in a vertical direction, a +Z direction is an upward direction, and a Z direction is a downward direction. The Z direction is the vertical direction. In addition, in the sheet manufacturing apparatus 1, a leading side in a transport direction of a fiber material, an accumulating material, a sheet, or the like is downstream, and a going-back side in the transport direction is upstream. For convenience of illustration, the size of each member is different from the actual size.

[0014] As illustrated in FIG. 1, the sheet manufacturing apparatus 1 according to the present embodiment includes a first unit group 101, a second unit group 102, and a third unit group 103. The first unit group 101, the second unit group 102, and the third unit group 103 are supported by a frame (not illustrated). In FIG. 1, directions in which fiber materials such as paper pieces C, a sheet P3, waste paper P4, a slit piece S, scraps, and the like move are indicated by white arrows, and directions in which a residual accumulating material V moves are indicated by dashed arrows.

[0015] The sheet manufacturing apparatus 1 manufactures the sheet P3 from the paper pieces C which are fiber materials containing fibers such as used paper. In the sheet manufacturing apparatus 1, the first unit group 101, the third unit group 103, and the second unit group 102 are arranged from a Y direction to a +Y direction in side view in a X direction.

[0016] The paper pieces C are transported from the first unit group 101 to the second unit group 102 through a pipe 21 that crosses the inside of the third unit group 103. The paper pieces C are defibrated in the second unit group 102 to form a defibrated material, which is an aggregate of fibers, and a binder and the like are added to the defibrated material. The defibrated material is transported to the third unit group 103 through a pipe 24. The defibrated material is formed into an accumulating material W in the third unit group 103 and is then formed into a strip-shaped sheet P1. The strip-shaped sheet P1 is cut into the sheet P3 in the first unit group 101.

[0017] The first unit group 101 includes a buffer tank 13, a fixed-quantity supply unit 15, a merging unit 17, and the pipe 21. In the first unit group 101, these components are arranged in this order from upstream to downstream. The first unit group 101 also includes a first cutting unit 81, a second cutting unit 82, a tray 84, a waste paper tray 85, and a shredding unit 86.

[0018] Moreover, a sheet transport unit 63 is disposed from the third unit group 103 to the first unit group 101. The sheet transport unit 63 transports the strip-shaped sheet P1, a single-cut sheet P2, the sheet P3, the waste paper P4, and the slit piece S. The first cutting unit 81 and the second cutting unit 82 cut the strip-shaped sheet P1 into the sheet P3 having a predetermined shape.

[0019] The sheet P3 that is produced is stacked in the tray 84. The waste paper P4 produced according to a stop operation of the sheet manufacturing apparatus 1 is stacked in the waste paper tray 85. Details of the waste paper P4 will be described later.

[0020] Moreover, the first unit group 101 includes a water supply unit 267. The water supply unit 267 is a water storage tank. The water supply unit 267 supplies water for humidification to each of a first humidification unit 265 and a second humidification unit 266, which will be described later, through a water supply pipe (not illustrated).

[0021] The paper pieces C are input from a raw material input port 11 to the buffer tank 13. The paper pieces C contain fibers such as cellulose and are, for example, pieces of shredded used paper. Humidified air is supplied to the inside of the buffer tank 13 from the second humidification unit 266 included in the third unit group 103.

[0022] The paper pieces C to be defibrated are temporarily stored in the buffer tank 13 and are then transported to the fixed-quantity supply unit 15 according to the operation of the sheet manufacturing apparatus 1. The sheet manufacturing apparatus 1 may include a shredder that shreds the paper pieces C and the like upstream of the buffer tank 13.

[0023] The fixed-quantity supply unit 15 includes a weighing device 15a and a supply mechanism (not illustrated). The weighing device 15a weighs a mass of the paper pieces C. The supply mechanism supplies the paper pieces C weighed by the weighing device 15a to the merging unit 17 located downstream. That is, the fixed-quantity supply unit 15 weighs the paper pieces C by each predetermined mass using the weighing device 15a and supplies the paper pieces C to the merging unit 17 located downstream by the supply mechanism.

[0024] Both digital and analog weighing mechanisms can be applied to the weighing device 15a. Specific examples of the weighing device 15a include a physical sensor such as a load cell, a spring scale, and a balance. In the present embodiment, a load cell is used as the weighing device 15a to weigh several grams to several tens of grams, but the present disclosure is not limited thereto.

[0025] A known technique such as a vibration feeder can be applied to the supply mechanism. The supply mechanism may be included in the weighing device 15a.

[0026] The weighing and supplying of the paper pieces C in the fixed-quantity supply unit 15 are batch processing. That is, the paper pieces C are intermittently supplied from the fixed-quantity supply unit 15 to the merging unit 17. The fixed-quantity supply unit 15 may include a plurality of weighing devices 15a, and the plurality of weighing devices 15a may be operated at different times to improve the weighing efficiency.

[0027] The sheet manufacturing apparatus 1 includes a return mechanism. The return mechanism includes a box 96, a tube 22, the merging unit 17, the pipe 21, and a suction blower (not illustrated) of a suction unit 59. In the return mechanism, the merging unit 17 is disposed in the first unit group 101, and the box 96 is disposed in the third unit group 103.

[0028] The pipe 21 is extended from the first unit group 101 to the second unit group 102 passing through the third unit group 103 and connects the merging unit 17 and the defibrator 30. The tube 22 is extended from the third unit group 103 to the first unit group 101 and connects the box 96 and the merging unit 17. The suction blower of the suction unit 59, which will be described later, is connected to the tube 22 through a pipe (not illustrated).

[0029] The return mechanism temporarily stores the residual accumulating material V in the box 96 and then transports the residual accumulating material V to the merging unit 17 through the tube 22. The return mechanism then merges the residual accumulating material V with the paper pieces C and the slit piece S in the merging unit 17 and sends them to the defibrator 30. The slit piece S is a scrap generated when the strip-shaped sheet P1 is cut into the sheet P3 having a predetermined shape. The slit piece S is shredded by the shredding unit 86 and supplied to the merging unit 17.

[0030] The residual accumulating material V is a defibrated material that is accumulating and produced when the operation of the sheet manufacturing apparatus 1 is stopped. The residual accumulating material V is not mixed with the paper pieces C during a normal operation of the sheet manufacturing apparatus 1, in which the sheet P3 is produced, and is mixed with the paper pieces C only when the sheet manufacturing apparatus 1 is stopped. That is, in the pipe 21, the paper pieces C and the slit piece S flow during the normal operation, and the residual accumulating material V flows in addition to the paper pieces C and the slit piece S during the stop operation. Details of the residual accumulating material V, the slit piece S, the shredding unit 86, and the like will be described later.

[0031] The return mechanism sucks air from a position of an accumulator 50 by the above-described suction blower of the suction unit 59. Specifically, the above-described suction blower of the suction unit 59 promotes accumulation of the defibrated material by a generated airflow. The above-described airflow moves from the suction unit 59 to the merging unit 17 through the tube 22. The residual accumulating material V is transported from the box 96 to the merging unit 17 by the above-described airflow. In addition, the return mechanism blows out the air sucked by the above-described suction blower at a position of the defibrator 30. More specifically, the defibrator 30 generates an airflow from the merging unit 17 to the defibrator 30.

[0032] As described above, the residual accumulating material V, the paper pieces C, and the like pass through the inside of the tube 22 of the return mechanism and are sent to the defibrator 30 by a wind force. As a result, compared to a configuration in which the residual accumulating material V and the like are transported by a transport belt or the like, it is possible to avoid a decrease in transportability due to the thickness of the residual accumulating material V and the like.

[0033] As illustrated in FIG. 2, the shredded slit piece S and the residual accumulating material V supplied from the above-described box 96 are merged with the paper pieces C in the merging unit 17. In the return mechanism, the pipe 21 and the tube 22 each have a circular cross section. In FIG. 2, a portion of the tube 22 on the above-described box 96 side and a portion of the pipe 21 on the above-described defibrator 30 side are not illustrated.

[0034] During the normal operation of the sheet manufacturing apparatus 1, the paper pieces C and the slit piece S are mixed while being transported inside the pipe 21 by the above-described wind force. During the stop operation of the sheet manufacturing apparatus 1, the paper pieces C, the shredded slit piece S, and the residual accumulating material V are mixed while being transported inside the pipe 21 by the above-described wind force.

[0035] Returning to FIG. 1, the second unit group 102 includes the defibrator 30, which is a dry type defibrator, a separator 41, a pipe 23, a mixing unit 45, and the pipe 24. In the second unit group 102, these components are arranged in this order from upstream to downstream. The second unit group 102 also includes a control unit 5, a capturing unit 95, a compressor 97, a power supply unit 99, and a pipe 25 and an airflow pipe 29 connected to the separator 41.

[0036] The paper pieces C and the like transported through the pipe 21 flow into the defibrator 30. The defibrator 30 defibrates the paper pieces C, which are fiber materials containing fibers, and the like by a dry method and generates a defibrated material containing fibers. A known defibrating mechanism can be applied to the defibrator 30.

[0037] In the present embodiment, a defibrating mechanism including a rotary blade is used as the defibrator 30. The defibrating mechanism generates fibers by shredding and defibrating the paper pieces C with the rotary blade. In the description of the defibrator 30 to the accumulator 50, the paper pieces C, the shredded slit piece S, and the residual accumulating material V may be referred to as the paper piece C for convenience.

[0038] Tangled fibers contained in the paper piece C are untangled by the defibrator 30 to form a defibrated material containing fibers, and the defibrated material is transported to the separator 41.

[0039] The separator 41 sorts the defibrated fibers. Specifically, the separator 41 removes components contained in the fibers and unnecessary for manufacturing the sheet P3. The separator 41 separates relatively long fibers from relatively short fibers. The relatively short fibers, which may lower the strength of the sheet P3, are sorted and removed by the separator 41. The separator 41 also removes impurities such as coloring materials and additives contained in the paper piece C.

[0040] A known separation mechanism can be applied to the separator 41. In the present embodiment, a disk-type separation mechanism including a separation filter is used as the separator 41. The separation mechanism sorts and separates relatively short fibers and impurities that pass through the separation filter from relatively long fibers that do not pass through the separation filter. The relatively long fibers are used as the defibrated material for the material of the accumulating material W.

[0041] Humidified air is supplied to the inside of the separator 41 from the second humidification unit 266 of the third unit group 103. As a result, the defibrated fibers are not easily charged, and attachment of the fibers to each other and adhesion of the fibers to the separator 41 are suppressed.

[0042] Relatively short fibers and the like are removed from the defibrated fibers in the separator 41. The defibrated fibers are then transported to the mixing unit 45 through the pipe 23 by an airflow generated by a blower (not illustrated) disposed at a leading end of the airflow pipe 29. Unnecessary components such as relatively short fibers and impurities are sucked by a suction device (not illustrated) of the capturing unit 95 and are discharged from the pipe 25 to the capturing unit 95.

[0043] The capturing unit 95 includes a filter (not illustrated). The filter filters out unnecessary components such as relatively short fibers transported through the pipe 25 by an airflow.

[0044] The compressor 97 generates compressed air. The above-described filter may be clogged with fine particles or the like of the unnecessary components. The filter can be cleaned by blowing the compressed air generated by the compressor 97 onto the filter to blow off adhering particles.

[0045] The power supply unit 99 includes a power supply device (not illustrated) that supplies power to the sheet manufacturing apparatus 1 and the control unit 5. The power supply unit 99 distributes power supplied from the outside to each component of the sheet manufacturing apparatus 1.

[0046] A powder supply unit 43 supplies a binder, which is a powder, to the mixing unit 45. The mixing unit 45 mixes the defibrated material and the binder supplied from the powder supply unit 43 in air. The binder need only be able to bind fibers to each other in a forming machine 70, which will be described later. In the present embodiment, starch is used as the binder, but a thermoplastic resin or the like may also be used.

[0047] The powder supply unit 43 includes a powder storage unit and a powder transport unit (not illustrated). The powder storage unit is attachable to and detachable from a main body of the powder supply unit 43. The powder storage unit can be removed from the powder supply unit 43 to be filled with the binder or transported. The powder transport unit supplies a fixed amount of binder per unit time to the mixing unit 45 while transporting the binder.

[0048] The powder supplied from the powder supply unit 43 to the mixing unit 45 is not limited to the binder and may be other additives such as a coloring material, for example. In addition, the above-described powder may be a mixture of the binder and other additives. Moreover, the sheet manufacturing apparatus 1 may include a plurality of powder supply units 43.

[0049] The mixing unit 45 mixes a binder and the like with the defibrated material, which is fibers, in air. Although not illustrated, the mixing unit 45 includes a flow path through which the defibrated material is transported and a fan. The fan of the mixing unit 45 mixes the binder and the like in air while transporting the defibrated material downstream using a generated airflow. The defibrated material then flows into the pipe 24 from the mixing unit 45.

[0050] The control unit 5 is electrically connected to each component of the sheet manufacturing apparatus 1 and integrally controls the operation of the sheet manufacturing apparatus 1. Although not illustrated, the control unit 5 includes a central processing unit (CPU) and a storage unit including a random access memory (RAM), a read only memory (ROM), and the like. Various programs for controlling the sheet manufacturing apparatus 1 are stored in the storage unit. The control unit 5 may include dedicated hardware (application specific integrated circuit: ASIC) that executes at least some of various processes. That is, the control unit 5 may be configured as one or more processors that operate according to a computer program (software), one or more dedicated hardware circuits such as ASICs, or a circuit including a combination thereof.

[0051] The processor includes a CPU and a memory such as a RAM and a ROM. The memory stores program codes or instructions configured to cause the CPU to perform processes. The memory, that is, a computer-readable medium includes any medium that can be accessed by a general-purpose or dedicated computer.

[0052] The third unit group 103 accumulates and compresses the defibrated material containing the binder and forms the defibrated material into the strip-shaped sheet P1. The third unit group 103 includes the accumulator 50, the transport unit 60, the box 96, the first humidification unit 265, the second humidification unit 266, a drainage unit 268, the forming machine 70, and the sheet transport unit 63. In the third unit group 103, the accumulator 50, the transport unit 60, and the forming machine 70 are arranged in this order from upstream to downstream. That is, the transport unit 60 is disposed between the accumulator 50 and the forming machine 70.

[0053] The transport unit 60 includes an accumulation transport unit 61 and a back surface transport unit 62. The transport unit 60 transports the accumulating material W formed in the accumulator 50 to the forming machine 70 located downstream. In the transport direction of the accumulating material W, the accumulation transport unit 61 is disposed upstream of the back surface transport unit 62. A downstream portion of the accumulation transport unit 61 and an upstream portion of the back surface transport unit 62 partially face each other in the vertical direction. The box 96 is disposed corresponding to a downstream end portion of the accumulation transport unit 61. The first humidification unit 265 is disposed below the back surface transport unit 62.

[0054] The accumulator 50 accumulates the defibrated material containing the binder and the like using an airflow and gravity to form the accumulating material W. The accumulator 50 includes a drum member 53, a blade member 55 disposed in the drum member 53, a housing 51 that houses the drum member 53, and a suction unit 59. The defibrated material is taken into the drum member 53 from the pipe 24.

[0055] The accumulation transport unit 61 is disposed below the accumulator 50. The accumulation transport unit 61 includes a mesh belt 611, which is a transport body, and five tension rollers (not illustrated) for tensioning the mesh belt 611. The suction unit 59 faces the drum member 53 with the mesh belt 611 interposed therebetween in a direction along the Z-axis.

[0056] The blade member 55 is disposed inside the drum member 53 and is rotationally driven by an electric motor (not illustrated). The drum member 53 is a semicircular columnar sieve. A mesh having a function of a sieve is provided on a side surface of the drum member 53 facing downward. The drum member 53 allows particles such as the fibers of the defibrated material and the binder, which are smaller than the size of mesh openings of the sieve, to pass through the mesh openings from the inside to the outside.

[0057] The defibrated material is discharged to the outside of the drum member 53 while being stirred by the rotating blade member 55 in the drum member 53. Humidified air is supplied from the second humidification unit 266 to the inside of the drum member 53.

[0058] The suction unit 59 is disposed below the drum member 53. The suction blower (not illustrated) of the suction unit 59 sucks air in the housing 51 through the plurality of holes of the mesh belt 611. As a result, an airflow for causing the defibrated material to accumulate on the mesh belt 611 is generated. The plurality of holes in the mesh belt 611 allow air to pass therethrough but do not allow the fibers, the binder, and the like contained in the defibrated material to pass therethrough easily. As a result, the defibrated material discharged to the outside of the drum member 53 is sucked downward together with the air.

[0059] The defibrated material containing the binder and the like is dispersed in the air inside the housing 51 and accumulates on an upper surface of the mesh belt 611 by gravity and the airflow generated by the suction unit 59 to form the accumulating material W.

[0060] The mesh belt 611 of the accumulation transport unit 61 is an endless belt and is tensioned by the five tension rollers. The mesh belt 611 is rotated counterclockwise in FIG. 1 by the rotation of the tension rollers. As a result, the defibrated material continuously accumulates on the mesh belt 611, and the accumulating material W is formed. The accumulating material W contains a relatively large amount of air and is soft and swollen. The accumulation transport unit 61 transports the formed accumulating material W downstream by the rotation of the mesh belt 611.

[0061] The back surface transport unit 62 transports the accumulating material W delivered from the accumulation transport unit 61 downstream of the accumulation transport unit 61. The back surface transport unit 62 peels the accumulating material W from the upper surface of the mesh belt 611 and transports the accumulating material W toward the forming machine 70. The back surface transport unit 62 is disposed above the transport path of the accumulating material W and slightly upstream of a starting point on a return side of the mesh belt 611, that is, an end portion in the Y direction. The +Y direction of the back surface transport unit 62 and the Y direction of the mesh belt 611 partially overlap each other in the vertical direction.

[0062] The back surface transport unit 62 includes a belt portion 621, four tension rollers (not illustrated), and an attraction unit 623. The belt portion 621 is provided with a plurality of holes through which air passes. The belt portion 621 is tensioned by the four tension rollers and rotates clockwise in FIG. 1 by the rotation of the tension rollers.

[0063] The attraction unit 623 sucks air through the plurality of holes of the belt portion 621 so as to attract the accumulating material W to the belt portion 621. The accumulating material W is transported while being attracted to the belt portion 621.

[0064] The attraction unit 623 is disposed above the belt portion 621 in the transport path of the accumulating material W in the back surface transport unit 62. The attraction unit 623 sucks air from a lower side to an upper side through the plurality of holes of the belt portion 621. As a result, an upper surface of the accumulating material W is attracted to a lower surface of the belt portion 621. When the belt portion 621 in this state rotates, the accumulating material W is attracted to the belt portion 621 and transported downstream. In other words, the belt portion 621 transports the accumulating material W while being in contact with the upper surface of the accumulating material W. The attraction unit 623 is a known suction device such as a suction fan. In the present embodiment, the attraction unit 623 includes three suction fans.

[0065] When the operation of the sheet manufacturing apparatus 1 is stopped, the residual accumulating material V, in other words, a portion of the accumulating material W in process is collected and temporarily stored in the box 96. A lower portion of the inside of the box 96 is in communication with the inside of the tube 22.

[0066] Although not illustrated, the box 96 is provided with a valve mechanism capable of opening and closing. Collection and flow of the residual accumulating material V in the box 96 are switched by the valve mechanism. When the inside of the box 96 and the tube 22 are closed by the valve mechanism, the residual accumulating material V does not flow into the tube 22. When the valve mechanism is opened, the inside of the box 96 and the tube 22 are in communication with each other, and the residual accumulating material V flows into the tube 22 and is sent to the merging unit 17.

[0067] The first humidification unit 265 humidifies the accumulating material W. The first humidification unit 265 is, for example, a mist humidifier. The first humidification unit 265 supplies mist M from below the accumulating material W transported by the back surface transport unit 62 to humidify the accumulating material W. The first humidification unit 265 is disposed below the back surface transport unit 62 and faces the accumulating material W transported by the back surface transport unit 62 in the vertical direction. For example, a known humidifier such as an ultrasonic humidifier can be applied to the first humidification unit 265.

[0068] By humidifying the accumulating material W with the mist M, a function of starch contained in the accumulating material W as a binder is promoted, and the strength of the sheet P3 is improved. If the function as a binder can be sufficiently exhibited without humidification, the first humidification unit 265 is unnecessary. In addition, since the accumulating material W is humidified from below, droplets derived from the mist M do not easily fall onto the accumulating material W. Moreover, since the accumulating material W is humidified from a side opposite to the upper surface of the accumulating material W in contact with the belt portion 621, sticking of the accumulating material W onto the belt portion 621 is reduced.

[0069] The forming machine 70 compresses and forms the transported accumulating material W to produce the strip-shaped sheet P1. The forming machine 70 includes a pair of a first roller 71 and a second roller 72. The forming machine 70 forms the strip-shaped sheet P1 from the accumulating material W by causing the accumulating material W to pass between the first roller 71 and the second roller 72.

[0070] Each of the first roller 71 and the second roller 72 is a substantially columnar member. The rotation axis of the first roller 71 and the rotation axis of the second roller 72 extend along the X-axis. The first roller 71 is disposed substantially below the transport path of the accumulating material W, and the second roller 72 is disposed substantially above the transport path of the accumulating material W. The first roller 71 and the second roller 72 rotate close to each other while the strip-shaped sheet P1 is formed from the accumulating material W.

[0071] In a direction along the X-axis, the length of the first roller 71 and the length of the second roller 72 are greater than the accumulating material W, that is, the width of the accumulating material W. Therefore, the accumulating material W is reliably pinched between the first roller 71 and the second roller 72.

[0072] The diameter of the first roller 71 is larger than the diameter of the second roller 72. For example, the diameter of the first roller 71 is 110 mm or more and 150 mm or less, and the diameter of the second roller 72 is 80 mm or more and 110 mm or less.

[0073] The first roller 71 includes, for example, a core bar and a surface layer covering the core bar. Examples of the core bar include a hollow structure made of aluminum, iron, stainless steel, or the like. Examples of the material of the surface layer include fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (ETFE), and silicone resins. As a result, the release properties of the first roller 71 from the accumulating material W are improved. In addition, abrasion and damage of the core bar are suppressed.

[0074] The second roller 72 includes, for example, a core bar, an intermediate layer, and a surface layer. Examples of the core bar include a hollow structure made of aluminum, iron, stainless steel, or the like. The intermediate layer covers the core bar and is covered with the surface layer. In other words, the intermediate layer is interposed between the core bar and the surface layer.

[0075] Examples of the material of the intermediate layer include elastic bodies such as silicone rubber and urethane rubber. The above-described elastic bodies preferably have a hardness of 30 or more and 70 or less, more preferably 40 or more and 60 or less when measured with an Asker C hardness tester. The thickness of the intermediate layer is preferably 1 mm or more and 10 mm or less, and more preferably 1 mm or more and 5 mm or less.

[0076] Examples of the material of the surface layer include fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (ETFE).

[0077] Since the second roller 72 has the above-described configuration, the release properties of the second roller 72 from the accumulating material W are improved. In addition, abrasion and damage of the intermediate layer are suppressed.

[0078] The accumulating material W is pressurized while passing between the first roller 71 and the second roller 72. The pressure applied to the accumulating material 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 still more preferably 0.4 MPa or more and 8.0 MPa or less. As a result, deterioration of the fibers in the accumulating material W is suppressed.

[0079] The first roller 71 has a built-in electric heater and has a function of increasing the temperature of a roller surface. Similarly to the first roller 71, the second roller 72 preferably has the function of increasing the temperature of a roller surface by an electric heater.

[0080] The surface temperature of the first roller 71, that is, the temperature of the surface layer of the first roller 71 in contact with the accumulating material W is preferably 100 C. or more and 130 C. or less. The surface temperature of the second roller 72, that is, the temperature of the surface layer of the second roller 72 in contact with the accumulating material W is preferably 80 C. or more and 100 C. or less.

[0081] The first roller 71 is rotationally driven by a stepping motor (not illustrated). The second roller 72 is a driven roller that is not driven by an electric motor or the like but rotates with the rotation of the first roller 71. Therefore, the second roller 72 rotates in the opposite direction to the first roller 71 in side view in the X direction.

[0082] The accumulating material W is sent downstream while being pinched between the first roller 71 and the second roller 72, and being heated and pressurized. That is, the accumulating material W continuously passes through the forming machine 70 and is press-formed while being heated. The use of the first roller 71 and the second roller 72 as a pair of forming members enables the accumulating material W to be efficiently heated and pressurized.

[0083] When the accumulating material W, which is in a state where it contains a relatively large amount of air and is soft, passes through the forming machine 70, the amount of air contained in the accumulating material W is reduced, and the density is increased. Then, the fibers are bound to each other by the binder and formed into the strip-shaped sheet P1. The strip-shaped sheet Pl is transported to the first unit group 101 by a plurality of rollers (not illustrated) of the sheet transport unit 63.

[0084] The second humidification unit 266 is disposed below the first humidification unit 265. A known vaporization type humidifier can be applied to the second humidification unit 266.

[0085] The second humidification unit 266 humidifies a predetermined region of the sheet manufacturing apparatus 1. The predetermined region is one or more of the buffer tank 13, the separator 41, and the inside of the drum member 53 of the accumulator 50. Specifically, the humidified air is supplied from the second humidification unit 266 to the above-described regions through a plurality of pipes (not illustrated). The humidified air suppresses charging of the paper piece C and the defibrated material in each of the above-described components. As a result, the paper piece C, the defibrated material, and the like do not easily adhere to the components.

[0086] The drainage unit 268 is a drainage tank. The drainage unit 268 collects and stores old moisture that is used in the first humidification unit 265, the second humidification unit 266, and the like. The drainage unit 268 can be removed from the sheet manufacturing apparatus 1 as necessary, and the collected water can be discarded.

[0087] The strip-shaped sheet Pl transported from the forming machine 70 to the first unit group 101 reaches the first cutting unit 81. The first cutting unit 81 cuts the strip-shaped sheet P1 in a direction intersecting the transport direction, for example, in the direction along the X-axis. The strip-shaped sheet P1 is cut into the single-cut sheet P2 by the first cutting unit 81. The single-cut sheet P2 is transported from the first cutting unit 81 to the second cutting unit 82 by the sheet transport unit 63.

[0088] The second cutting unit 82 cuts the single-cut sheet P2 in the transport direction, for example, in a direction along the Y-axis. Specifically, the second cutting unit 82 cuts both end portions in the direction along the X-axis of the single-cut sheet P2. As a result, the single-cut sheet P2 is formed into the sheet P3 having a predetermined shape such as an A4 size or an A3 size, for example.

[0089] When the single-cut sheet P2 is cut into the sheet P3 in the second cutting unit 82, the slit piece S, which is a scrap, is generated. The slit piece S is transported substantially in the Y direction and reaches the shredding unit 86 which is a shredder. The shredding unit 86 shreds the slit piece S into shredded pieces and supplies the shredded pieces to the merging unit 17. A mechanism for weighing the shredded pieces of the slit piece S and supplying the shredded pieces to the merging unit 17 may be provided between the shredding unit 86 and the merging unit 17.

[0090] The sheet P3 is transported substantially upward and collected in 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 or the like.

[0091] The waste paper tray 85 is disposed above the tray 84. The waste paper P4 is transported in the same manner as the sheet P3 and is collected in the waste paper tray 85. Although the details will be described later, the waste paper P4 is generated according to the stop operation of the sheet manufacturing apparatus 1.

[0092] Next, a sheet production method according to the present embodiment will be described. The sheet manufacturing apparatus 1 is used in the sheet production method of the present embodiment. As described above, the sheet manufacturing apparatus 1 forms the paper piece C into the defibrated material, accumulates the defibrated material on the mesh belt 611 to form the accumulating material W, and forms the transported accumulating material W to produce the sheet P3.

[0093] When the apparatus is stopped, with the accumulating material W left as it is, and then is restarted, it is conceivable that the apparatus starts manufacturing using the residual accumulating material V, which is the accumulating material W in process that has been left earlier. However, the residual accumulating material V is not subjected to processing such as pressurization, and there is a tendency for deterioration in quality such as becoming physically fragile to occur when time elapses from the formation. Therefore, handling of the residual accumulating material V becomes a problem.

[0094] On the other hand, in the sheet production method of the present embodiment, the residual accumulating material V is returned to the defibrator 30 and accumulates on the mesh belt 611 in response to an instruction to stop accumulation during the accumulation of the accumulating material W.

[0095] FIG. 3 is a flowchart illustrating the sheet production method. The flowchart illustrated in FIG. 3 starts in a state where the sheet P3 is already being produced. The flowchart of FIG. 3 relates to a method for producing the sheet P3 using the sheet manufacturing apparatus 1. Known production methods can be applied to portions that are not described. The following sheet production method is merely an example, and the present disclosure is not limited thereto. In the following description, FIG. 1 and the like are also referred to.

[0096] In step S1, a user gives a stop instruction. The user gives an instruction to stop the normal operation through an operation panel of the sheet manufacturing apparatus 1. The stop instruction is transmitted from the operation panel to the control unit 5. Then, the process proceeds to step S2.

[0097] In step S2, the residual accumulating material V that is accumulating in the accumulator 50 is collected and stored in the box 96. The collection of the residual accumulating material V will be described in detail later. Then, the process proceeds to step S3.

[0098] In step S3, the operation of the sheet manufacturing apparatus 1 is stopped in a state where the residual accumulating material V is collected in the box 96. That is, when the stop instruction is given from the user, the residual accumulating material V is not sent from the return mechanism to the defibrator 30 but is stored in the box 96, and the operation of the sheet manufacturing apparatus 1 is stopped. As a result, the time required to stop the operation is shortened compared to a case where the residual accumulating material V is returned to the defibrator 30 and consumed. Then, when the sheet manufacturing apparatus 1 is operated again, the process proceeds to step S4.

[0099] In step S4, the user gives an instruction to resume the production of the sheet P3. The user gives an instruction to start the normal operation through the operation panel of the sheet manufacturing apparatus 1. The start instruction is transmitted from the operation panel to the control unit 5. Then, the process proceeds to step S6.

[0100] In step S6, the residual accumulating material V collected and stored in the box 96 at the time of the previous stop, that is, in step S2, is returned to the defibrator 30. At this time, a new paper piece C is not input to the defibrator 30, and the components between the defibrator 30 and the accumulator 50 continue normal operation. In addition, the control unit 5 may send the residual accumulating material V to the defibrator 30 on condition that the accumulator 50 is stopped, that is, in step S2. The residual accumulating material V is formed into the defibrated material in the defibrator 30 and is transported to the accumulator 50. Then, the process proceeds to step S7.

[0101] After the residual accumulating material V is input to the defibrator 30, the new paper piece C is input.

[0102] In step S7, the defibrated material derived from the residual accumulating material V first accumulates, and then the defibrated material derived from the new paper piece C accumulates. Accordingly, the defibrated material derived from the residual accumulating material V accumulates upstream of the accumulating material W that accumulates during the normal operation. Boundaries between the defibrated material derived from the residual accumulating material V and the accumulating material W are not clear and are gradually switched.

[0103] Here, as illustrated in FIG. 4, the thickness, which is the dimension in the Z direction, is different between the accumulating material W and the residual accumulating material V, which are formed when the normal operation of the sheet manufacturing apparatus 1 is stopped.

[0104] In the accumulator 50, the accumulation amount of the defibrated material on the mesh belt 611 immediately after the operation of the sheet manufacturing apparatus 1, in other words, immediately after the start of accumulation, has a large variation compared to the accumulation amount of the defibrated material after a predetermined time has elapsed from the start of accumulation. The above-described accumulation amount immediately after the accumulation may include, for example, a variation of 5% or more in the mass of the defibrated material per unit area.

[0105] The thickness of the accumulating material W affects the quality of the sheet P3. Accordingly, it is difficult to ensure the quality of the sheet P3 formed from the accumulating material immediately after the start of accumulation. Therefore, the sheet immediately after the start of accumulation is classified as the waste paper P4 and is distinguished from the sheet P3, which is a non-defective sheet, to be formed later. As described above, in step S7, the defibrated material derived from the residual accumulating material V accumulates first, and then the defibrated material derived from the new paper piece C accumulates. Therefore, a sheet including the defibrated material derived from the residual accumulating material V is classified as the waste paper P4, and a sheet not including the defibrated material derived from the residual accumulating material V and made of the defibrated material derived from the new paper piece C is classified as the non-defective sheet P3. As a result, the defibrated material derived from the residual accumulating material V whose quality is deteriorated after staying in the box 96 for a long period of time is not formed into the non-defective sheet P3, but is used as the material of the waste paper P4, which is inevitably generated, so that the residual accumulating material V can be effectively utilized without being wasted.

[0106] When the accumulation is stopped, the supply of the defibrated material is also stopped, and thus the thickness becomes thinner than L. It is also difficult to ensure the quality of the residual accumulating material V remaining when the accumulation is stopped. In addition, a thin portion may be torn, and clogging may occur during transport by the transport unit 60. Therefore, the residual accumulating material V remaining when the accumulation is stopped is started to accumulate and is collected in the box 96, so that the residual accumulating material V is not used for forming the sheet P3.

[0107] In the accumulating material W, a portion to be formed into the sheet P3 and a portion to be formed into the waste paper P4 are separated by time management in the present embodiment. There is a time lag until the residual accumulating material V is formed into the defibrated material in the defibrator 30 and accumulates in the accumulator 50. Therefore, the accumulating material W that is formed from the start of the transport of the residual accumulating material V from the box 96 to the elapse of a fixed time is classified as the sheet P3, and the accumulating material W that is formed after the elapse of the fixed time is classified as the waste paper P4. The above-described classification may be performed based on, for example, a measurement result of a sensor that measures the thickness of the accumulating material W or the residual accumulating material V, in addition to the time management.

[0108] Returning to FIG. 3, in step S8, the accumulating material W is humidified by the first humidification unit 265 and is heated and pressurized between the first roller 71 and the second roller 72. Then, the accumulating material W derived from the residual accumulating material V is cut off by the first cutting unit 81 and is discharged to the waste paper tray 85 as the waste paper P4. In addition, the sheet P3 having a desired size is produced from the accumulating material W not derived from the residual accumulating material V.

[0109] Next, a flow of collecting the residual accumulating material V will be described. In step S9, all the residual accumulating material V stored in the box 96 in step S2 is sent to the defibrator 30 and consumed. The consumption of the residual accumulating material V may be, for example, managed by time since the residual accumulating material V is started being taken out to the defibrator 30 or may be determined based on a detection result of a sensor provided in the box 96.

[0110] Next, in step S10, the mesh belt 611 is stopped, and the accumulating material W and the residual accumulating material V are cut. More specifically, as illustrated in FIG. 5, the supply of the defibrated material to the accumulator 50 and the driving of the mesh belt 611 are stopped by the control unit 5.

[0111] As a result, the accumulation of the defibrated material on the mesh belt 611 is stopped. Moreover, the transport of the accumulating material W by the belt portion 621 is continued, whereas the mesh belt 611 is stopped.

[0112] Therefore, tension is applied to the accumulating material W in the direction along the Y-axis, and the accumulating material W is cut into the accumulating material W downstream and the residual accumulating material V upstream between the accumulator 50 and the transport unit 60. The accumulating material W is a portion in which a necessary amount of the defibrated material accumulates during the normal operation. The residual accumulating material V is a portion in which the necessary amount of the defibrated material does not accumulate due to the supply of the defibrated material being stopped.

[0113] Next, the control unit 5 restarts the driving of the mesh belt 611 and transports the residual accumulating material V downstream. That is, the mesh belt 611 transports the residual accumulating material V toward the box 96 of the return mechanism in response to the accumulating material W and the residual accumulating material V being cut and the accumulation of the defibrated material in the accumulator 50 being stopped. At this time, the control unit 5 stops one or more of the three suction fans of the attraction unit 623 so that the residual accumulating material V is not attracted to the belt portion 621. Then, the process proceeds to step S11.

[0114] Returning to FIG. 3, in step S11, the residual accumulating material V does not move to the belt portion 621, but falls into the box 96 and starts to be collected. The residual accumulating material V collected in step S11 is the residual accumulating material V at the time of the current stop. Then, the process proceeds to step S12.

[0115] In step S12, when the defibrated material is completely consumed in the drum member 53 of the accumulator 50, the control unit 5 stops rotation driving of the blade member 55. This ends the accumulation of the defibrated material on the mesh belt 611. Step S12 is started after a fixed time elapses by time management. The fixed time in step S12 is a period of time during which the defibrated material in the drum member 53 is consumed. Step S12 may be started according to a detection result of a sensor that detects the defibrated material in the drum member 53, instead of time management.

[0116] Next, the control unit 5 stops driving of the mesh belt 611. The driving of the mesh belt 611 is stopped after a fixed time elapses by time management. The fixed time is a time during which all the residual accumulating material V on the mesh belt 611 is collected in the box 96. The stop of driving described above may be performed according to a detection result of a sensor that detects the residual accumulating material V on the mesh belt 611, instead of time management. Then, the process proceeds to step S13.

[0117] In step S13, the control unit 5 stops the operation of the defibrator 30. Step S13 is performed by time management after a fixed time elapses from the stop of the driving of the mesh belt 611. In this manner, the defibrated material, the accumulating material W, and the residual accumulating material V do not remain at least between the accumulator 50 and the transport unit 60, and preparation for stopping the sheet manufacturing apparatus 1 is completed.

[0118] Here, the timing at which the residual accumulating material V being accumulating is sent to the defibrator 30 is not limited. That is, when the stop instruction is given, the residual accumulating material V collected at the time of the current stop may be stored in the box 96 until the operation is restarted, or the residual accumulating material V may be sent to the defibrator 30 at the time of stop and stored in the defibrator 30 until the restart of the operation.

[0119] In addition, when the stop instruction is received during the accumulation of the defibrated material, the accumulator 50 may leave the residual accumulating material V as it is until the operation is restarted and may input the residual accumulating material V into the box 96 when the operation is restarted. In this case, when the operation is restarted, first, a residual accumulating material V1 that has been input to and stored in the box 96 at the time of the previous stop is sent to the defibrator 30 and defibrated. The accumulator 50 inputs the residual accumulating material V to the box 96 that is empty and then starts accumulation of the defibrated material derived from the residual accumulating material V1.

[0120] A stop trigger is not limited to an instruction from the user, and the operation may be stopped by a stop instruction from a processor due to occurrence of an error or the like.

[0121] According to the present embodiment, the following effects can be obtained.

[0122] The residual accumulating material V being accumulating can be returned. In detail, it is possible to return the residual accumulating material V to the defibrator 30 and use the residual accumulating material V as the defibrated material again. As a result, handling of the residual accumulating material V generated according to the stop of the sheet manufacturing apparatus 1 becomes clear, and hindering the restart of the apparatus by the residual accumulating material V remaining in the accumulator 50 or the like is suppressed.