SHEET MANUFACTURING APPARATUS AND SHEET MANUFACTURING METHOD

Description

The present application is based on, and claims priority from JP Application Serial Number 2024-066611, filed Apr. 17, 2024, 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

In the related art, an apparatus for manufacturing a sheet from fibers has been known. For example, JP-A-2016-112740 discloses a sheet manufacturing apparatus in which fibers accumulate in air and are then formed into a sheet.

However, there has been a problem of how to deal with a material accumulating in an accumulation unit as a work-in-process when the apparatus is stopped.

SUMMARY

A sheet manufacturing apparatus for manufacturing a sheet from fibers includes an accumulation unit that accumulates fibers to form a web, a first transport unit that transports the web from the accumulation unit, a second transport unit that transports the web from the first transport unit, and a manufacturing unit that compresses the web transported by the second transport unit to manufacture a sheet, and in a case where manufacturing of the sheet is stopped, between the first transport unit and the second transport unit, the web is cut into an upstream web and a downstream web, the upstream web is collected, and the sheet is manufactured from the downstream web.

A sheet manufacturing method includes accumulating fibers to form a web and compressing the web to manufacture a sheet, in a case where manufacturing of the sheet is stopped, cutting the web before being compressed into an upstream web and a downstream web, collecting the upstream web without manufacturing the sheet from the upstream web, and compressing the downstream web to manufacture the sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 2 is a schematic diagram illustrating a detailed configuration of a transport unit.

FIG. 3 is a flowchart illustrating each step of stop operation in a sheet manufacturing method.

FIG. 4 is a schematic diagram illustrating stop operation of a sheet manufacturing apparatus.

FIG. 5 is a schematic diagram illustrating the stop operation of the sheet manufacturing apparatus.

FIG. 6 is a schematic diagram illustrating the stop operation of the sheet manufacturing apparatus.

FIG. 7 is a schematic diagram illustrating the stop operation of the sheet manufacturing apparatus.

DESCRIPTION OF EMBODIMENTS

In the following embodiment, a sheet manufacturing apparatus 1 that manufactures a sheet from a material containing fibers by a dry method and a sheet manufacturing method using the sheet manufacturing apparatus 1 will be described as examples 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. The material is not particularly limited as long as the material contains fibers and may be new paper, waste paper, scraps, or the like.

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 material, a web, a sheet, or the like is downstream, and a trailing side in the transport direction is upstream. For convenience of illustration, the size of each member is different from the actual size.

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 paper pieces C, a sheet P3, a slit piece S, unnecessary scraps, and the like move are indicated by white arrows. In the following description, it is assumed that paper pieces are used as the material. An aggregate of a plurality of paper pieces C is also simply referred to as a paper piece C.

The sheet manufacturing apparatus 1 manufactures the sheet P3 from the paper piece C. 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.

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

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

In addition, 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, 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.

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).

The paper piece C is input from a raw material input port 11 to the buffer tank 13. Humidified air is supplied to an inside of the buffer tank 13 from the second humidification unit 266 included in the third unit group 103.

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

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

Both a digital measuring mechanism and an analog measuring mechanism can be applied to the measuring device 15a. The predetermined mass for which the paper piece C is weighed by the measuring device 15a is, for example, approximately several grams to several tens of grams.

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

The weighing and supplying of the paper piece C in the fixed-quantity supply unit 15 is batch processing. That is, the paper piece C is 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 measuring devices 15a, and the plurality of measuring devices 15a may be operated at different times to improve the weighing efficiency.

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

The pipe 21 allows the paper piece C to transport therethrough from the first unit group 101 to the second unit group 102 using an airflow generated by a blower (not illustrated).

The second unit group 102 includes a defibrating unit 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 that are connected to the separator 41.

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

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

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 cause a decrease in 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.

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

Humidified air is supplied to an inside of the separator 41 from the second humidification unit 266 of the third unit group 103.

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.

The mixing unit 45 mixes a binding material 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 fibers are transported, a fan, a hopper, a supply pipe, and a valve.

The hopper is in communication with the flow path of the fibers through the supply pipe. The valve is provided in the supply pipe between the hopper and the flow path. The hopper supplies a binding material such as starch into the flow path. The valve adjusts the mass of the binding material supplied from the hopper to the flow path. As a result, the ratio at which the fibers and the binding material are mixed is adjusted.

The mixing unit 45 may include a similar configuration for supplying a coloring material, an additive, or the like, in addition to the above-described configurations for supplying the binding material.

The fan of the mixing unit 45 mixes the binding material 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.

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.

The compressor 97 generates compressed air. In the above-described filter, clogging may occur due to fine particles or the like of the unnecessary components. The filter can be cleaned through blowing of the compressed air generated by the compressor 97 onto the filter to blow off adhering particles.

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 an outside to each component of the sheet manufacturing apparatus 1.

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 in accordance with a computer program (software), one or more dedicated hardware circuits such as ASICs, or a circuit including a combination thereof.

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.

The third unit group 103 accumulates and compresses the defibrated material including a binding material and forms the defibrated material into the strip-shaped sheet P1. The third unit group 103 includes an accumulation unit 50, a transport unit 60, a collecting unit 96, the first humidification unit 265, the second humidification unit 266, a drainage unit 268, the forming unit 70, and the sheet transport unit 63. In the third unit group 103, the accumulation unit 50, the transport unit 60, and the forming unit 70 are arranged in this order from upstream to downstream. That is, the transport unit 60 is disposed between the accumulation unit 50 and the forming unit 70.

The transport unit 60 includes an accumulation transport unit 61 and a back surface transport unit 62. The accumulation transport unit 61 is also referred to as a first transport unit, and the back surface transport unit 62 is also referred to as a second transport unit. The transport unit 60 transports the web W formed in the accumulation unit 50 to the forming unit 70 located downstream. In the transport direction of the web 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 collecting unit 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.

The accumulation unit 50 forms the web W by accumulating the defibrated material containing a binding material and the like using an airflow and gravity. The accumulation unit 50 includes a drum member 53, a blade member 55 installed in the drum member 53, a housing 51 that accommodates the drum member 53, and a suction unit 59. The defibrated material is taken into the drum member 53 from the pipe 24.

The accumulation transport unit 61 is disposed below the accumulation unit 50. The accumulation transport unit 61 includes a mesh belt 611 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.

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 binding material, which are smaller than the size of mesh openings of the sieve, to pass through the mesh openings from the inside to the outside.

The defibrated material is discharged to the outside of the drum member 53 while being agitated 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.

The suction unit 59 is disposed below the drum member 53. The suction unit 59 sucks air in the housing 51 through a 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 of the mesh belt 611 allows air to pass therethrough but does not allow the fibers, the binding material, 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. The suction unit 59 is a known suction device such as a suction fan.

The defibrated material containing the binding material 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 web W.

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 web W is formed. The web W contains a relatively large amount of air and is soft and swollen. The accumulation transport unit 61 transports the formed web W downstream by the rotation of the mesh belt 611.

The back surface transport unit 62 transports the web W delivered from the accumulation transport unit 61 downstream of the accumulation transport unit 61. The back surface transport unit 62 peels the web W from the upper surface of the mesh belt 611 and transports the web W toward the forming unit 70. The back surface transport unit 62 is disposed above the transport path of the web 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.

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.

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

The attraction unit 623 is disposed above the belt portion 621 in the transport path of the web 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 web W is attracted to a lower surface of the belt portion 621. When the belt portion 621 rotates in this state, the web W is attracted to the belt portion 621 and transported downstream. In other words, the belt portion 621 transports the web W in contact with the upper surface of the web W. The attraction unit 623 is a known suction device such as a suction fan.

The collecting unit 96 collects a portion of the web W in process when the operation of the sheet manufacturing apparatus 1 is stopped. Details of the collecting unit 96, the back surface transport unit 62 including the attraction unit 623, and the like will be described later.

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

When the web W is humidified with the mist M, the function of the binding material contained in the web W is promoted, and the strength of the sheet P3 is improved. In addition, since the web W is humidified from below, droplets derived from the mist M do not easily fall onto the web W. Furthermore, since the web W is humidified from a side opposite to the upper surface of the web W in contact with the belt portion 621, sticking of the web W onto the belt portion 621 is reduced.

The forming unit 70 compresses the web W and forms the web W into the strip-shaped sheet P1. The forming unit 70 includes a pair of a first roller 71 and a second roller 72. The forming unit 70 forms the strip-shaped sheet P1 from the web W by causing the web W to pass between the first roller 71 and the second roller 72.

Each of the first roller 71 and the second roller 72 is a substantially columnar member. A rotation axis of the first roller 71 and a 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 web W, and the second roller 72 is disposed substantially above the transport path of the web W. The first roller 71 and the second roller 72 rotate in proximity to each other while the strip-shaped sheet P1 is formed from the web W.

In a direction along the X-axis, a length of the first roller 71 and a length of the second roller 72 are longer than a length of the web W, that is, a width of the web W. Therefore, the web W is reliably pinched between the first roller 71 and the second roller 72.

A diameter of the first roller 71 is larger than a 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.

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 a 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, release properties of the first roller 71 from the web W are improved. In addition, abrasion and damage of the core bar are suppressed.

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.

Examples of a 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. A 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.

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

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

The web W is pressurized while passing between the first roller 71 and the second roller 72. The pressure applied to the web W by the first roller 71 and the second roller 72 is preferably 0.1 MPa or more and 15.0 MPa or less, more preferably 0.2 MPa or more and 10.0 MPa or less, and still more preferably 0.4 MPa or more and 8.0 MPa or less. As a result, deterioration of the fibers in the web W is suppressed.

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

A surface temperature of the first roller 71, that is, a temperature of the surface layer of the first roller 71 in contact with the web W is preferably 100° C. or more and 130° C. or less. A surface temperature of the second roller 72, that is, a temperature of the surface layer of the second roller 72 in contact with the web W is preferably 80° C. or more and 100° C. or less.

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. For that reason, the second roller 72 rotates in a direction opposite to the first roller 71 in side view in the −X direction.

The web W is fed downstream while being pinched between the first roller 71 and the second roller 72, and being heated and pressurized. That is, the web W continuously passes through the forming unit 70 and is press-formed while being heated. The use of the first roller 71 and the second roller 72 as a pair of forming members enables the web W to be efficiently heated and pressurized.

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

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.

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 accumulation unit 50. Specifically, the humidified air is supplied from the second humidification unit 266 to the above-described region through a plurality of pipes (not illustrated). The humidified air suppresses charging of the paper piece C and fibers in each of the above-described components. As a result, the paper piece C, the fibers, and the like do not easily adhere to the components.

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 water having accumulated can be discarded.

The strip-shaped sheet P1 transported from the forming unit 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 a 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.

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 of the single-cut sheet P2 in the direction along the X-axis. As a result, the single-cut sheet P2 becomes the sheet P3 having a predetermined shape such as an A4 size or an A3 size.

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 piece, 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 installed between the shredding unit 86 and the merging unit 17.

The sheet P3 is transported substantially upward and stacked in the tray 84. As described above, 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.

As illustrated in FIG. 2, the attraction unit 623 of the transport unit 60 includes a first attraction unit 623a, a second attraction unit 623b, and a third attraction unit 623c. In the attraction unit 623, the first attraction unit 623a, the second attraction unit 623b, and the third attraction unit 623c are arranged in this order in the −Y direction, which is the transport direction of the web W. Each of the first attraction unit 623a, the second attraction unit 623b, and the third attraction unit 623c has an independent suction device and can be individually switched between operation and stop.

The first attraction unit 623a substantially faces the starting point on the return side of the mesh belt 611 of the accumulation transport unit 61 in the vertical direction. The first attraction unit 623a attracts the web W transported by the accumulation transport unit 61 to the belt portion 621 and receives the web W from the accumulation transport unit 61.

The second attraction unit 623b is disposed above the first humidification unit 265. The second attraction unit 623b attracts the web W to the belt portion 621 similarly to the first attraction unit 623a. In addition, the second attraction unit 623b upwardly sucks the mist M generated by the first humidification unit 265 through the web W and the belt portion 621. Accordingly, the web W is impregnated with the mist M.

Similarly to the first attraction unit 623a, the third attraction unit 623c attracts the web W to the belt portion 621 and transports the web W to the forming unit 70 located downstream.

Each of the first attraction unit 623a, the second attraction unit 623b, and the third attraction unit 623c continues the suction operation during normal operation in which the sheet manufacturing apparatus 1 manufactures the sheet P3. The air sucked by the first attraction unit 623a, the second attraction unit 623b, and the third attraction unit 623c is introduced into the above-described capturing unit 95 through a pipe (not illustrated). In the following description, an operation in which the sheet manufacturing apparatus 1 manufactures the sheet P3 may be simply referred to as a normal operation.

Although not illustrated, the back surface transport unit 62 includes a lifting mechanism that moves the transport path of the web W in the back surface transport unit 62 up and down. Specifically, the lifting mechanism lifts and lowers the belt portion 621, the four tension rollers (not illustrated), and the attraction unit 623 in the vertical direction. FIG. 2 illustrates a state during normal operation in the sheet manufacturing apparatus 1. During normal operation, the lifting mechanism is in a state in which the respective components of the back surface transport unit 62 are most lowered.

During normal operation, the transport path of the web W from the accumulation transport unit 61 to the back surface transport unit 62 is continuous along the Y-axis and is substantially planar. On the other hand, when the lifting mechanism lifts the respective components of the back surface transport unit 62, the transport path of the web W becomes different in level between the accumulation transport unit 61 and the back surface transport unit 62 and becomes discontinuous. The action when the lifting mechanism lifts the respective components of the back surface transport unit 62 will be described later. As a driving source of the lifting mechanism, a known device such as an electric motor or various actuators can be applied.

The collecting unit 96 is disposed below a region including the starting point on the return side of the mesh belt 611 of the accumulation transport unit 61, that is, the end portion in the −Y direction. When the normal operation of the sheet manufacturing apparatus 1 is stopped, a portion of the web W drops and is collected in the collecting unit 96 as indicated by a dashed arrow. A portion of the collected web W is accommodated in a collection container (not illustrated).

The above-described control unit 5 includes a sensor 91. The sensor 91 includes a first sensor 91a, a second sensor 91b, and a third sensor 91c. Each of the first sensor 91a and the second sensor 91b is disposed in the transport path of the web W and detects the presence or absence of the web W in a detection region. The third sensor 91c is disposed in a transport path of the strip-shaped sheet P1 and detects the presence or absence of the strip-shaped sheet P1 in a corresponding region. The first sensor 91a is an example of a sensor unit of the present disclosure.

The first sensor 91a is disposed above the transport path of the web W and upstream of the back surface transport unit 62 in the transport direction of the web W. The second sensor 91b is disposed below the transport path of the web W and downstream of the third attraction unit 623c in the transport direction of the web W. The third sensor 91c is disposed above the transport path of the strip-shaped sheet P1 and downstream of the forming unit 70 in the transport path of the strip-shaped sheet P1.

The first sensor 91a, the second sensor 91b, and the third sensor 91c are not particularly limited as long as the first sensor 91a, the second sensor 91b, and the third sensor 91c can detect the presence or absence of the web W or the strip-shaped sheet P1. As the first sensor 91a, the second sensor 91b, and the third sensor 91c, for example, known sensors such as a photo sensor can be applied.

The detection results of the first sensor 91a, the second sensor 91b, and the third sensor 91c are transmitted to the CPU of the control unit 5 and are reflected in the various types of control of the sheet manufacturing apparatus 1. In particular, the detection results of the first sensor 91a are used for control when the operation of the sheet manufacturing apparatus 1 to be described later is stopped.

As illustrated in FIG. 3, a sheet manufacturing method according to the present embodiment includes step S1 to step S6. The sheet manufacturing method of the present embodiment relates to a method for stopping the normal operation of the sheet manufacturing apparatus 1 in a method for manufacturing the sheet P3 using the sheet manufacturing apparatus 1. As a method other than the above-described method, a known manufacturing method can be applied. The sheet manufacturing method of the present embodiment is an example, and the present disclosure is not limited thereto. When an error such as a sheet jam occurs during normal operation of the sheet manufacturing apparatus 1, or when a stop instruction is received from a user, the normal operation of the sheet manufacturing apparatus 1 is stopped.

When the normal operation of the sheet manufacturing apparatus 1 is stopped, first, step S1 is performed. In step S1, supply of the defibrated material, which is the material of the web W, is stopped. In step S2, the web W is cut into an upstream web W1 and a downstream web W2, which will be described later. In step S3, it is determined whether or not a cut region of the web W has passed the first sensor 91a. When the above-described cut region has passed the first sensor 91a, the process proceeds to step S4. In step S4, the above-described lifting mechanism is lifted. In step S5, the sheet P3 is manufactured from the downstream web W2. In step S6, the upstream web W1 is collected to the collecting unit 96.

Next, details of step S1 to step S6 will be described with reference to FIGS. 4 to 7. In step S1, the control unit 5 stops the transport from the buffer tank 13 to the fixed-quantity supply unit 15 and stops the operation of each device in order in accordance with the flow of the material from the fixed-quantity supply unit 15 downstream. As a result, the supply of the defibrated material from the pipe 24 to the accumulation unit 50 is also stopped. The accumulation unit 50 continues operating until the defibrated material in the drum member 53 runs out. For example, the accumulation unit 50 stops after a predetermined time elapses from the stop of the supply of the defibrated material. Then, the process proceeds to step S2.

In step S2, the control unit 5 controls the accumulation transport unit 61 of the transport unit 60 to cut the web W into the upstream web W1 and the downstream web W2 between the accumulation transport unit 61 and the back surface transport unit 62. Specifically, the control unit 5 stops driving of the mesh belt 611 and stops the transport of the web W by the accumulation transport unit 61. At the same time, the control unit 5 continues causing the back surface transport unit 62 to transport the web W.

At this time, a force of being held on the stopped mesh belt 611 and a force of being pulled in the −Y direction by the back surface transport unit 62 act on the web W. By such forces, the web W is cut into the upstream web W1 and the downstream web W2. FIG. 4 is a view illustrating the above-described state. Then, the process proceeds to step S3.

In step S3, the control unit 5 determines whether or not the cut region of the web W has passed the first sensor 91a. Specifically, the first sensor 91a detects a space between the upstream web W1 and the downstream web W2, which is the cut region of the web W. In other words, when the downstream web W2 is transported to the back surface transport unit 62 and is transported in the −Y direction, and an end portion of the downstream web W2 in the +Y direction passes, the first sensor 91a detects the absence of the web W. The back surface transport unit 62 continues transporting the downstream web W2.

When the end portion of the downstream web W2 in +Y direction passes below the first sensor 91a, as illustrated in FIG. 5, the process proceeds to step S4.

In step S4, the control unit 5 lifts the above-described lifting mechanism of the back surface transport unit 62. The back surface transport unit 62 is lifted, for example, by several millimeters from a position during normal operation. As a result, a step is formed in the transport path of the web W between the accumulation transport unit 61 and the back surface transport unit 62. At the same time, the control unit 5 continues causing the back surface transport unit 62 to transport the web W. FIG. 6 is a diagram illustrating the above-described state. Step S4 is performed after step S3 of cutting the web W and before step S6 of collecting the upstream web W1. The suction device of the capturing unit 95 described above continues suction until the sheet manufacturing apparatus 1 completely stops. Then, the process proceeds to step S5.

In step S5, the control unit 5 transports the downstream web W2 to the forming unit 70, and the forming unit 70 continues forming the strip-shaped sheet P1 using the downstream web W2. At this time, the first attraction unit 623a, the second attraction unit 623b, and the third attraction unit 623c sequentially stop suction in response to the downstream web W2 passing therethrough. Moreover, the control unit 5 stops the operation of the back surface transport unit 62 after an upstream end portion of the downstream web W2 passes the second sensor 91b and passes through the back surface transport unit 62. In addition, the first cutting unit 81 and the second cutting unit 82 cut the downstream web W2 into the sheet P3 having a predetermined shape. When all of the downstream web W2 is cut, the control unit 5 stops the operation of the first cutting unit 81 and the second cutting unit 82. Thereafter, the sheet P3 is transported substantially upward and stacked on the tray 84, and the operation of the sheet transport unit 63 is also stopped. In addition, the control unit 5 stops the operation of the forming unit 70 after an upstream end portion of the strip-shaped sheet P1 formed from the downstream web W2 passes the third sensor 91c. Then, the process proceeds to step S6.

In step S6, the accumulation transport unit 61 is operated again, and the upstream web W1 is collected in the collecting unit 96. Specifically, the upstream web W1 is transported in the −Y direction. Since the transport path of the web W is lifted in step S4, and suction by the first attraction unit 623a is stopped in step S5, the upstream web W1 is not delivered from the accumulation transport unit 61 to the back surface transport unit 62. A downstream end portion of the upstream web W1 hangs down due to gravity, is further transported by the accumulation transport unit 61, and falls into the collecting unit 96.

In step S6, when the upstream web W1 is transported, the first sensor 91a detects the downstream end portion of the upstream web W1. When the collection of the upstream web W1 to the collecting unit 96 further progresses, an upstream end portion of the upstream web W1, that is, an end portion in the +Y direction passes through a detection range of the first sensor 91a. Thereafter, the mesh belt 611 moves the upstream web W1 from the detection range of the first sensor 91a to the starting point on the return side of the mesh belt 611. As a result, the control unit 5 determines that the upstream web W1 does not exist in the accumulation transport unit 61 and has been completely collected in the collecting unit 96. The control unit 5 stops the operation of the accumulation transport unit 61 in response to the upstream web W1 of the first sensor 91a being completely collected.

The control unit 5 is not limited to stopping the normal operation of the sheet manufacturing apparatus 1 based on the detection results of the first sensor 91a, the second sensor 91b, and the third sensor 91c. The control unit 5 may cause each of the above-described steps to proceed by timer management without using a sensor. As described above, the control unit 5 stops the operation of the accumulation unit 50, the accumulation transport unit 61 and the back surface transport unit 62 of the transport unit 60, and the forming unit 70.

In addition, portions of step S5 and step S6 may be performed in parallel. FIG. 7 is a diagram illustrating a state in which portions of step S5 and step S6 are performed in parallel.

In addition, in step S2, the web W may be cut into the upstream web W1 and the downstream web W2 through making of the transport by the mesh belt 611 slower than the transport by the back surface transport unit 62, instead of stopping the driving of the mesh belt 611.

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

The web W does not remain when the normal operation is stopped. In addition, when the operation is stopped, the web W is cut, the upstream web W1 is collected in the collecting unit 96, and the downstream web W2 is sent and processed into the sheet P3. As a result, a time required for the sheet manufacturing apparatus 1 to completely stop is shortened compared to a case where the web W in process while the operation is stopped, including a portion of the web W collected in the collecting unit 96 as the upstream web W1, is all processed into the sheet P3.