Sheet manufacturing device control method

Abstract

To provide a method for controlling a sheet manufacturing device, which prevents defects due to a thickness of a web tip from occurring.SOLUTION: A sheet manufacturing device 1 comprises: a defibration part 30; an accumulation part 50 which forms a web W; a second conveyance part 62 which has a conveyance belt 62a for conveying the web W; and a pressurization part 70 which has a pressurizing roller pair 700 consisting of a first roller 71 and a second roller 72 and forms a belt-like sheet P1 by pressurizing the web W. A control method of the sheet manufacturing device 1 has: a first step S1 of conveying the web W by the conveyance belt 62a; a second step S2 of peeling off a tip of the web W from the conveyance belt 62a; a third step S3 of rotating the first roller 71 in a rotation direction R1 to bend the tip of the web W; and a fourth step 4 of rotating the first roller 71 in a rotation direction R2 and making the web W pass through between the pressurizing roller pair 700, and folding down the tip of the web W.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, there have been known devices that manufacture sheets using fibers obtained by defibrating waste paper in air. Among such devices, there are devices that mold a sheet from a web containing fibers. For example, Patent Document 1 discloses a sheet manufacturing device that includes a pressure roller and a heating roller for molding a web into a sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-208923 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the device described in Patent Document 1, when the thickness of the web tip is thin, there is a possibility that the device may malfunction. In particular, in the process of forming a web by depositing materials such as fibers in the air, there is a problem that it is difficult to control the thickness of the web tip. When the thickness of the web tip becomes thin, the web may stick to the heating roller. In addition, the thickness of the tip of the sheet formed from the web also becomes thin, so that the mechanical strength of the sheet tip is insufficient and buckling is likely to occur. In other words, there is a possibility that the sheet tip may get caught on a member such as a conveying roller during the sheet conveying path, causing a paper jam. The following invention has been devised to solve such problems. [Means for solving the problem]

[0005] A control method for a sheet manufacturing apparatus of the present invention is a control method for a sheet manufacturing apparatus that manufactures a sheet from a fiber-containing material, the sheet manufacturing apparatus comprising: a defibrating unit that defibrates the fiber-containing material to produce defibrated material; a depositing unit that deposits the defibrated material to form a web; a web transport unit having a conveyor belt that contacts one side of the web to transport the web; and a pressurizing unit that has a pair of pressure rollers consisting of a first roller and a second roller and pressurizes the web to form the sheet, and the control method for the sheet manufacturing apparatus comprises a first step of transporting the web by the conveyor belt; a second step of peeling a leading end of the web from the conveyor belt; a third step of rotating the first roller in a first direction to fold the leading end of the web; and a fourth step of rotating the first roller in a second direction opposite to the first direction and passing the web between the pair of pressure rollers to fold the leading end of the web. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a sheet manufacturing apparatus according to an embodiment. [Diagram 2] FIG. 4 is a flow chart showing a control method of the sheet manufacturing apparatus. [Diagram 3] FIG. 2 is a schematic diagram showing a method of folding a web. [Figure 4] FIG. 2 is a schematic diagram showing a method of folding a web. [Diagram 5] FIG. 2 is a schematic diagram showing a method of folding a web. [Figure 6] FIG. 2 is a schematic diagram showing a method of folding a web. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] In the following embodiment, a sheet manufacturing apparatus 1 that recycles sheets from pieces of paper such as waste paper in a dry manner will be exemplified as a sheet manufacturing apparatus that manufactures sheets from a material containing fiber. Hereinafter, the sheet manufacturing apparatus 1 and a control method thereof will be described with reference to the drawings.

[0008] In addition, the sheet manufacturing apparatus of the present invention is not limited to a dry type and may be a wet type. In this specification, the dry type means that the operation is not performed in a liquid but in air such as the atmosphere.

[0009] In each of the following figures, XYZ axes are attached as mutually orthogonal coordinate axes, the direction indicated by each arrow is the + direction, and the direction opposite to the + direction is the - direction. The Z axis is an imaginary axis along the vertical direction, with the +Z direction being the upward direction and the -Z direction being the downward direction. The -Z direction is the direction in which gravity acts. In addition, in the sheet manufacturing apparatus 1, the side ahead in the conveying direction of the raw material, web, sheet, etc. is sometimes referred to as the downstream side, and the side going upstream in the conveying direction is sometimes referred to as the upstream side. For convenience of illustration, the sizes of each component are made different from the actual size.

[0010] 1.Sheet manufacturing equipment As shown in Fig. 1, the sheet manufacturing apparatus 1 according to this embodiment includes a first unit group 101, a second unit group 102, and a third unit group 103. The first unit group 101, the second unit group 102, and the third unit group 103 are supported by a frame (not shown). In Fig. 1, the directions in which waste paper C, sheets P3, slit pieces S, unnecessary scraps, etc. move are indicated by outlined arrows.

[0011] The sheet manufacturing apparatus 1 manufactures a sheet P3 from recycled paper C, which is a material containing fibers. In the sheet manufacturing apparatus 1, a first unit group 101, a third unit group 103, and a second unit group 102 are arranged from the -Y direction toward the +Y direction in a side view from the -X direction.

[0012] The waste paper C is transported from the first unit group 101 to the second unit group 102 via a pipe 21 that crosses inside the third unit group 103. The waste paper C is then defibrated and turned into fibers in the second unit group 102, and made into a mixture containing a binder and the like. The mixture is transported to the third unit group 103 via a pipe 24. The mixture is made into a web W in the third unit group 103, and is then formed into a belt-shaped sheet P1. The belt-shaped sheet P1 is cut in the first unit group 101 to become a sheet P3.

[0013] The first unit group 101 has a buffer tank 13, a constant quantity supply unit 15, a junction unit 17, and a pipe 21. In the first unit group 101, these components are arranged in the above order from upstream to downstream. The first unit group 101 also has a first cutting unit 81, a second cutting unit 82, a tray 84, and a shredding unit 86. The first cutting unit 81 and the second cutting unit 82 cut the strip-shaped sheet P1 into a sheet P3 of a predetermined shape. The first unit group 101 also has a water supply unit 67. The water supply unit 67 is a water storage tank. The water supply unit 67 supplies water for humidification to each of the first humidifying unit 65 and the second humidifying unit 66, which will be described later, through a water supply pipe (not shown).

[0014] Waste paper C is fed into the buffer tank 13 from the raw material feed port 11. The waste paper C contains fibers such as cellulose, and is, for example, pieces of shredded waste paper. Humidified air is supplied to the inside of the buffer tank 13 from the second humidifier 66 provided in the third unit group 103.

[0015] The waste paper C to be defibrated is temporarily stored in the buffer tank 13, and then transported to the fixed-quantity supply unit 15 in accordance with the operation of the sheet manufacturing apparatus 1. The sheet manufacturing apparatus 1 may be equipped with a shredder upstream of the buffer tank 13 that shreds the waste paper C and the like.

[0016] The fixed-quantity supply unit 15 has a weighing device 15a and a supply mechanism (not shown). The weighing device 15a weighs the mass of the waste paper C. The supply mechanism supplies the waste paper C weighed by the weighing device 15a to the downstream junction 17. That is, the fixed-quantity supply unit 15 weighs the waste paper C by a predetermined mass using the weighing device 15a, and supplies the waste paper C to the downstream junction 17 using the supply mechanism.

[0017] The weighing device 15a may be a digital or analog weighing mechanism. Specifically, the weighing device 15a may be a physical sensor such as a load cell, a spring scale, or a balance. In this embodiment, a load cell is used as the weighing device 15a. The predetermined mass of the waste paper C weighed by the weighing device 15a is, for example, several grams to several tens of grams.

[0018] The feeding mechanism may be a known technique such as a vibration feeder, etc. The feeding mechanism may be included in the weighing device 15a.

[0019] The weighing and supply of the waste paper C in the quantitative supply unit 15 is a batch process. That is, the supply of the waste paper C from the quantitative supply unit 15 to the junction 17 is performed intermittently. The quantitative supply unit 15 may have a plurality of weighing devices 15a, and the weighing efficiency may be improved by operating the plurality of weighing devices 15a at staggered times.

[0020] At the junction 17, the waste paper C supplied from the quantitative supply unit 15 is joined and mixed with the fine pieces of the slit pieces S supplied from the shredding unit 86. The slit pieces S and the shredding unit 86 will be described later. The waste paper C mixed with the fine pieces flows from the junction 17 into the pipe 21.

[0021] The pipe 21 conveys the waste paper C from the first unit group 101 to the second unit group 102 by an air current generated by a blower (not shown).

[0022] The second unit group 102 has a defibrator unit 30, which is a dry type defibrator, a separation unit 40, piping 23, a mixing unit 91, and piping 24. In the second unit group 102, these components are arranged in the above order from upstream to downstream. The second unit group 102 also has a collection unit 95, a compressor 97, a power supply unit 99, and piping 25 and air flow piping 29 connected to the separation unit 40.

[0023] The waste paper C transported through the piping 21 flows into the defibration unit 30. The defibration unit 30 defibrates the waste paper C, which is a material containing fibers, in a dry manner to generate defibrated material containing fibers. A known defibration mechanism can be applied to the defibration unit 30. In this embodiment, a defibration mechanism equipped with a rotary blade is used as the defibration unit 30. The defibration mechanism shreds and defibrates the waste paper C with the rotary blade to generate fibers.

[0024] The waste paper C has tangled fibers contained in the waste paper C untangled by the defibrating unit 30 to become defibrated material containing fibers, and is transported to the separating unit 40.

[0025] The separation unit 40 separates the defibrated fibers. More specifically, the separation unit 40 removes components contained in the fibers that are unnecessary for the production of the sheet P3. That is, the separation unit 40 separates relatively long fibers from relatively short fibers. Relatively short fibers may cause a decrease in the strength of the sheet P3, so they are selected and removed by the separation unit 40. The separation unit 40 also removes impurities such as coloring materials and additives contained in the waste paper C.

[0026] A known separation mechanism can be applied to the separation unit 40. In this embodiment, a disk-type separation mechanism equipped with a separation filter is used as the separation unit 40. The separation mechanism selects and separates relatively short fibers and impurities that pass through the separation filter from relatively long fibers that do not pass through the separation filter. The relatively long fibers are used as material for the web W as defibrated fibers.

[0027] Humidified air is supplied to the inside of separation section 40 from second humidifier section 66 of third unit group 103.

[0028] From the defibrated fibers, relatively short fibers and the like are removed in the separation section 40. Then, the defibrated fibers are transported to the mixing section 91 via the pipe 23 by an airflow generated by a blower (not shown) arranged at the tip of the airflow pipe 29. Unnecessary parts such as relatively short fibers and impurities are discharged from the pipe 25 to the recovery section 95.

[0029] The mixer 91 mixes the fibers with a binder and the like in the air to produce a mixture. Although not shown, the mixer 91 includes a flow path through which the fibers are transported, a fan, a hopper, a supply pipe, and a valve.

[0030] The hopper communicates with the fiber flow path via a supply pipe. A valve is provided in the supply pipe between the hopper and the flow path. The hopper supplies a binder such as starch into the flow path. The valve adjusts the mass of the binder supplied from the hopper to the flow path. This adjusts the mixture ratio of the fiber and the binder.

[0031] The mixing section 91 may have a similar configuration for supplying a coloring material, an additive, and the like, in addition to the above-mentioned configuration for supplying the binder.

[0032] The fan of the mixer 91 generates an air current that transports the fibers downstream while mixing the fibers with the binder and other materials in the air to form a mixture. The mixture flows from the mixer 91 into the pipe 24.

[0033] The collecting section 95 includes a filter (not shown) that filters out unnecessary materials such as relatively short fibers carried through the pipe 25 by the air current.

[0034] The compressor 97 generates compressed air. The filter may become clogged with fine particles of unwanted matter. The compressed air generated by the compressor 97 can be blown against the filter to blow away the particles adhering to the filter, thereby cleaning the filter.

[0035] The power supply unit 99 has a power supply device (not shown) that supplies power to the sheet manufacturing apparatus 1, and a control unit 5. The power supply unit 99 distributes power supplied from an external source to each component of the sheet manufacturing apparatus 1.

[0036] Although not shown, the control unit 5 includes a central processing unit (CPU) and a storage unit including a random access memory (RAM) and a read only memory (ROM). 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) for executing at least some of the various processes. In other words, the control unit 5 may be configured as a circuit including one or more processors that operate according to a computer program (software), one or more dedicated hardware circuits such as ASIC, or a combination of these.

[0037] The processor includes a CPU and memory, such as RAM and ROM. The memory stores program codes or instructions configured to cause the CPU to execute processes. Memory, i.e., computer-readable media, includes anything that can be accessed by a general-purpose or special-purpose computer.

[0038] The control unit 5 is electrically connected to each component of the sheet manufacturing apparatus 1 including the second conveying unit 62, the air ejection unit 200, and the pressurizing unit 70, and controls the overall operation of these components. In particular, the control unit 5 also controls the folding of the web W, which will be described later.

[0039] The third unit group 103 deposits and compresses the mixture containing fibers to form a belt-shaped sheet P1, which is recycled paper. The third unit group 103 includes a depositing section 50, a first conveying section 61, a second conveying section 62, a first humidifying section 65, an air ejecting section 200, a second humidifying section 66, a draining section 68, and a pressurizing section 70. The second conveying section 62 is an example of a web conveying section of the present invention.

[0040] In the third unit group 103, the deposition unit 50, the first conveying unit 61, the second conveying unit 62, the first humidifying unit 65, and the pressurizing unit 70 are arranged in the above order from upstream to downstream. The air injection unit 200 is located inside the second conveying unit 62 and is arranged at the downstream end of the conveying path of the web W in the second conveying unit 62. The second humidifying unit 66 is arranged below the first humidifying unit 65.

[0041] The deposition unit 50 deposits the mixture generated from the defibrated material by airflow and gravity to form a web W. The deposition unit 50 has 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 mixture is taken into the drum member 53 from the piping 24.

[0042] A first transport unit 61 is disposed below the deposition unit 50. The first transport unit 61 has a mesh belt 61a and five tension rollers (not shown) that tension the mesh belt 61a. The suction unit 59 faces the drum member 53 with the mesh belt 61a therebetween in the direction along the Z axis.

[0043] The blade member 55 is located inside the drum member 53 and is rotated by a motor (not shown). The drum member 53 is a semi-cylindrical sieve. A mesh functioning as a sieve is provided on the downward-facing side of the drum member 53. The drum member 53 allows particles such as fibers and mixtures that are smaller than the size of the mesh openings of the sieve to pass from the inside to the outside.

[0044] The mixture is discharged to the outside of the drum member 53 while being agitated by the rotating blade member 55 inside the drum member 53. Humidified air is supplied from a second humidifying section 66 to the inside of the drum member 53.

[0045] The suction unit 59 is disposed below the drum member 53. The suction unit 59 sucks air inside the housing 51 through a plurality of holes in the mesh belt 61a. This generates an airflow that deposits the mixture on the mesh belt 61a. The plurality of holes in the mesh belt 61a allow air to pass through but prevent fibers and binders contained in the mixture from passing through. As a result, the mixture 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.

[0046] The mixture is dispersed in the air within the housing 51 and is deposited on the upper surface of the mesh belt 61a by gravity and the air current generated by the suction section 59 to become the web W.

[0047] The mesh belt 61a is an endless belt that is stretched around five tension rollers. The mesh belt 61a rotates counterclockwise in FIG. 1 due to the rotation of the tension rollers. As a result, the mixture is continuously deposited on the mesh belt 61a, and a web W is formed. The web W contains a relatively large amount of air and is soft and inflated. The first conveying section 61 conveys the formed web W downstream by the rotation of the mesh belt 61a.

[0048] The second conveying section 62 is downstream of the first conveying section 61 and conveys the web W in place of the first conveying section 61. The second conveying section 62 peels the web W from the upper surface of the mesh belt 61a and conveys it toward the pressurizing section 70. The second conveying section 62 is disposed above the conveying path of the web W and slightly upstream of the starting point of the return side of the mesh belt 61a. The +Y direction of the second conveying section 62 and the -Y direction of the mesh belt 61a partially overlap in the vertical direction.

[0049] The second conveying section 62 has a conveying belt 62a, four tension rollers (not shown), and a suction section 62b. The conveying belt 62a has a plurality of holes for passing air. The conveying belt 62a is stretched by the four tension rollers, and rotates clockwise in FIG. 1 by the rotation of the tension rollers.

[0050] The suction unit 62b is disposed above the conveyor belt 62a on the conveying path of the web W in the second conveyor 62. The suction unit 62b sucks the air below upward through a plurality of holes in the conveyor belt 62a. As a result, one side of the web W, which is the upper side, is adsorbed to the lower side of the conveyor belt 62a. When the conveyor belt 62a rotates in this state, the web W is adsorbed to the conveyor belt 62a and conveyed downstream. In other words, the conveyor belt 62a contacts one side of the web W to convey the web W. The suction unit 62b is a known suction device such as a suction fan.

[0051] The first humidifying section 65 humidifies the web W including fibers deposited in the depositing section 50 of the third unit group 103. In detail, the first humidifying section 65 is, for example, a mist type humidifier, and humidifies the web W transported by the second transport section 62 by supplying mist M from below. The first humidifying section 65 is disposed below the second transport section 62 and faces the web W transported by the second transport section 62 in the direction along the Z axis. A known humidifying device, for example, an ultrasonic type, can be used as the first humidifying section 65.

[0052] By humidifying the web W with the mist M, the function of the binder contained in the web W is promoted, and the strength of the sheet P3 is improved. In addition, since the web W is humidified from below, drops from the mist M are prevented from falling onto the web W. Furthermore, since the web W is humidified from the side opposite to the one side that contacts the conveyor belt 62a, sticking of the web W to the conveyor belt 62a is reduced. The second conveyor unit 62 conveys the web W toward the pressurizing unit 70.

[0053] The air injection unit 200 is located in the second conveying unit 62, downstream of the suction unit 62b. Although not shown, the air injection unit 200 has a compressed air tank and an injection nozzle. The compressed air tank supplies compressed air to the injection nozzle. The air injection unit 200 injects compressed air downward from the injection nozzle toward the web W. Compressed air is supplied to and stored in the compressed air tank, for example, from a compressor (not shown) for the air injection unit 200.

[0054] The injection nozzle is a long and narrow opening extending in the direction along the X-axis. The injection nozzle faces the web W transported on the conveyor belt 62a in the direction along the Z-axis. The compressed air injected from the air injection unit 200 passes through the conveyor belt 62a and hits one side of the web W adsorbed to the lower surface of the conveyor belt 62a. At this time, since the length of the injection nozzle is longer than the length of the web W in the direction along the X-axis, the compressed air injected from the injection nozzle is sprayed across the entire width of the web W.

[0055] As a result, the web W is peeled off from the conveyor belt 62a. The compressed air is injected by the air injection unit 200 when the downstream leading end of the web W reaches the area facing the air injection unit 200. Then, after the leading end of the web W is peeled off from the conveyor belt 62a, the leading end of the web W is bent and folded. Thereafter, the web W is transferred from the second conveyor unit 62 to the pressurizing unit 70. The bending and folding of the web W will be described in detail later.

[0056] The pressing unit 70 has a pair of pressing rollers 700 consisting of a first roller 71 and a second roller 72. The pressing unit 70 passes the web W between the pair of pressing rollers 700, and forms a belt-shaped sheet P1 from the web W.

[0057] The first roller 71 and the second roller 72 form a pair and are each a substantially cylindrical member. The rotation axis of the first roller 71 and the rotation axis of the second roller 72 are arranged along the X-axis. With respect to the transport path of the web W, the first roller 71 is arranged substantially below and the second roller 72 is arranged substantially above. The first roller 71 and the second roller 72 rotate close to each other while the band-shaped sheet P1 is formed from the web W.

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

[0059] The diameter of the first roller 71 is larger than the diameter of the second roller 72. For example, the diameter of the first roller 71 is not less than 110 mm and not more than 150 mm, and the diameter of the second roller 72 is not less than 80 mm and not more than 110 mm.

[0060] The first roller 71 includes, for example, a core metal and a surface layer covering the core metal. The core metal may be a hollow structure made of aluminum, iron, stainless steel, or the like. The surface layer may be made of fluororesins such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkylvinylether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), and ETFE (tetrafluoroethylene-ethylene copolymer), and silicone resin. This improves the releasability of the first roller 71 with respect to the web W. In addition, wear and damage to the core metal are suppressed.

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

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

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

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

[0065] The web W is pressurized by passing between the first roller 71 and the second roller 72. The pressure applied to the web W by the first roller 71 and the second roller 72 is preferably 0.1 MPa or more and 15.0 MPa or less, more preferably 0.2 MPa or more and 10.0 MPa or less, and even more preferably 0.4 MPa or more and 8.0 MPa or less. This suppresses deterioration of the fibers in the web W.

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

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

[0068] The first roller 71 has fine irregularities on its surface. The irregularities on the surface are indicated by the surface roughness measured by a surface roughness meter. The surface roughness of the surface of the first roller 71 is preferably 2 μm to 8 μm, more preferably 3 μm to 6 μm, in arithmetic mean roughness (Ra). Also, the maximum height (Rz) is preferably 15 μm to 70 μm, more preferably 25 μm to 50 μm. The irregularities on the surface of the first roller 71 may originate from the surface of the core metal, or may originate from the surface of the surface layer. These irregularities are formed, for example, by blasting or thermal spraying.

[0069] Since the second roller 72 has an elastic intermediate layer as described above, when the web W is sandwiched between the first roller 71 and the second roller 72 and molded, the surface of the strip-shaped sheet P1 that comes into contact with the second roller 72 is likely to become uneven. On the other hand, if the surface of the first roller 71 is made smooth, the surface of the strip-shaped sheet P1 that comes into contact with the first roller 71 is likely to become smooth. In this case, a difference in surface quality, which is the difference in unevenness, is likely to occur between the front and back surfaces of the strip-shaped sheet P1. Such a difference in surface quality becomes a difference in smoothness between the front and back of the sheet P3, and when the sheet P3 is used as copy paper or the like, it may be necessary to use the front and back sides separately.

[0070] In contrast, the fine irregularities on the surface of the first roller 71 reduce the difference in surface quality between the front and back of the belt-like sheet P1, making it possible to use the front and back of the sheet P3 without distinguishing between them. Also, in folding the web W, which will be described later, the ability of the web W to follow the first roller 71 is improved, making folding easier.

[0071] The first roller 71 is rotated by a stepping motor (not shown). The second roller 72 is not driven by a motor, but is a driven roller that rotates in conjunction with the rotation of the first roller 71. Therefore, the second roller 72 rotates in the opposite direction to the first roller 71 when viewed from the side in the -X direction.

[0072] The web W is sandwiched between the first roller 71 and the second roller 72 and sent downstream while being heated and pressurized. That is, the web W passes continuously through the pressurizing section 70 and is press-molded while being heated. By using the first roller 71 and the second roller 72 as a pair of molding members, the web W is efficiently heated and pressurized.

[0073] The web W, which is in a soft state containing a relatively large amount of air, is reduced in air and its density increases as the web W passes through the pressurizing unit 70. Then, the fibers are bound together by the binder, and the web W is formed into a belt-shaped sheet P1. The belt-shaped sheet P1 is transported to the first unit group 101 by a transport roller (not shown).

[0074] Here, since the web W is formed by accumulating the mixture, the thickness of the web W is not stable in the initial stage of the formation of the web W, that is, in the region of the leading end of the web W. In general, the thickness of the leading end of the web W tends to be thinner than the thickness of the rear part. When the thickness is thin, there is a possibility that problems such as sticking to the first roller 71 or the second roller 72 or clogging of the belt-shaped sheet P1 in the path may occur. In response to this, in the sheet manufacturing apparatus 1, the leading end is doubled and the thickness is increased by a control method described later, thereby preventing the occurrence of the above problems. In the following description, the leading end of the web W on the downstream side in the conveying direction may be simply referred to as the leading end of the web W.

[0075] The second humidifier 66 is disposed below the first humidifier 65. A known evaporation type humidifier can be used for the second humidifier 66.

[0076] The second humidifying section 66 humidifies a predetermined area of ​​the sheet manufacturing apparatus 1. The predetermined area is one or more of the buffer tank 13, the separating section 40, and the inside of the drum member 53 of the stacking section 50. Specifically, humidified air is supplied to the above-mentioned area from the second humidifying section 66 through a plurality of pipes (not shown). In each of the above-mentioned configurations, the humidified air suppresses electrostatic charge on the waste paper C, fibers, etc., and suppresses adhesion of these materials to members due to static electricity.

[0077] The drainage unit 68 is a drainage tank. The drainage unit 68 is used in the first humidifying unit 65 and the second humidifying unit 66, etc., and collects and stores old moisture. The drainage unit 68 can be removed from the sheet manufacturing apparatus 1 as necessary, and the stored water can be discarded.

[0078] The strip-shaped sheet P1 transported to the first unit group 101 reaches the first cutting section 81. The first cutting section 81 cuts the strip-shaped sheet P1 in a direction intersecting the transport direction, for example, along the X-axis. The strip-shaped sheet P1 is cut into single sheets P2 at the first cutting section 81. The single sheets P2 are transported from the first cutting section 81 to the second cutting section 82.

[0079] The second cutting section 82 cuts the single-cut sheet P2 in the conveying direction, for example, in the direction along the Y axis. More specifically, the second cutting section 82 cuts both ends of the single-cut sheet P2 in the X axis direction. As a result, the single-cut sheet P2 becomes a sheet P3 of a predetermined shape, for example, A4 size or A3 size.

[0080] When the second cutting section 82 cuts the single-cut sheets P2 into sheets P3, slit pieces S, which are scraps, are generated. The slit pieces S are transported in the approximately -Y direction to reach the shredding section 86, which is a shredder. The shredding section 86 shreds the slit pieces S into small pieces and supplies them to the junction 17. A mechanism for weighing the small pieces of the slit pieces S and supplying them to the junction 17 may be provided between the shredding section 86 and the junction 17.

[0081] The sheet P3 is conveyed substantially upward and accumulated on the tray 84. In this manner, the sheet P3 is manufactured by the sheet manufacturing apparatus 1. The sheet P3 can be used as a substitute for, for example, copy paper.

[0082] 2. Method for controlling sheet manufacturing equipment As shown in Fig. 2, the control method for the sheet manufacturing apparatus 1 according to this embodiment includes a first step S1, a second step S2, a third step S3, a fourth step S4, and a fifth step S5. These steps are executed in the above order under the control of the controller 5. Each of the steps will be described below with reference to Figs. 3 to 6. In the description of Figs. 3 to 6, a state viewed from the side from the -X direction will be described unless otherwise specified.

[0083] As shown in FIG. 3, in a first step S1, the second transport section 62 transports the web W downstream in the −Y direction.

[0084] In the normal forming operation in which the web W is passed between the first roller 71 and the second roller 72, the first roller 71 rotates in a counterclockwise rotation direction R2, and the second roller 72 rotates in a clockwise rotation direction R1. In the first step S1, since the web W has not yet reached between the first roller 71 and the second roller 72, the rotation of the first roller 71 and the second roller 72 may be stopped, or each of them may be rotated in the above-mentioned direction as shown in FIG.

[0085] Then, when the leading edge of the web W passes the area facing the air injection unit 200, the process proceeds to the second step S2. Whether or not the leading edge of the web W has reached the area facing the air injection unit 200 can be determined by detecting the position of the leading edge of the web W using an optical sensor. Alternatively, a method can be applied in which the time from when the deposition unit 50 starts to drive until when the leading edge of the web W reaches the position facing the air injection unit 200 is measured in advance, and the timing control is performed by presetting the time.

[0086] 4, in the second step S2, the leading end of the web W is peeled off from the conveyor belt 62a. More specifically, in the second step S2, the leading end of the web W is peeled off from the conveyor belt 62a by the injection of compressed air from the air injection unit 200. During this time, the conveyor belt 62a continues to convey the web W, so that the leading end of the web W hangs down and comes into contact with the first roller 71.

[0087] At this time, it is preferable to rotate the first roller 71 in a clockwise rotation direction R1, which is the first direction, before proceeding to the subsequent third step S3, as shown in Fig. 4. In this case, the second roller 72 rotates in a counterclockwise rotation direction R2 following the first roller 71.

[0088] In the second step S2, the leading end of the web W is peeled off from the conveyor belt 62a by the compressed air, and the direction of the leading end of the web W is changed to approximately downward. This makes it easier to bend the leading end of the web W in the subsequent third step S3. Then, the process proceeds to the third step S3.

[0089] 5, in a third step S3, the first roller 71 is rotated in a rotation direction R1, which is a first direction, with the leading end of the web W touching the side surface of the first roller 71. The leading end of the web W is pulled by the rotation of the first roller 71 and bent in approximately the +Y direction. At this time, the second roller 72 rotates in a counterclockwise rotation direction R2 following the first roller 71.

[0090] In the third step S3, the first roller 71 rotates in the rotation direction R1 for a predetermined time. The distance by which the leading end of the web W is bent in the approximately +Y direction is adjusted by the diameter, rotation speed, and rotation time of the first roller 71. For example, the time for rotating the first roller 71 in the rotation direction R1 is set to 3 seconds from the start of the injection of compressed air by the air injection unit 200. As a result, the leading end of the web W is bent in the +Y direction by approximately 60 mm. Then, the process proceeds to the fourth step S4.

[0091] 6, in the fourth step S4, the first roller 71 is rotated in a rotation direction R2, which is a second direction opposite to the first direction, and the second roller 72 is rotated in the rotation direction R1 accordingly. At the same time, the web W is passed between the pressure roller pair 700, which is the first roller 71 and the second roller 72. As a result, the leading end of the web W is pressurized and folded. Then, the process proceeds to the fifth step S5.

[0092] In the fifth step S5, following the fourth step S4, the first roller 71 continues to rotate in the rotation direction R2, and the second roller 72 continues to rotate in the rotation direction R1. As a result, the web W is pressed while passing between the pair of pressure rollers 700, and is heated by the first roller 71 and the second roller 72. As a result, a belt-shaped sheet P1 is continuously formed. The transport path of the belt-shaped sheet P1 is indicated by a dashed line in FIG. 6. Thereafter, the belt-shaped sheet P1 is transported toward the first cutting section 81 described above.

[0093] The folding distance at the downstream end of the belt-shaped sheet P1 in the conveying direction, i.e., the distance by which the web W is folded over, may be, for example, 20 mm or more in the conveying direction. The above distance is adjusted by the distance by which the leading end of the web W is folded in the third step S3.

[0094] The leading end of the web W is not limited to being folded twice. The third step S3 and the fourth step S4 described above may be repeated to fold the leading end of the web W three or more times. This further increases the thickness and strength of the leading end of the web W.

[0095] In the second step S2, the leading end of the web W may be curled and folded in a spiral shape by adjusting the transport speed of the web W after the leading end is peeled off and the rotation speed of the first roller 71. This increases the thickness of the leading end of the web W, further increasing the strength of the leading end of the web W.

[0096] According to this embodiment, the following effects can be obtained.

[0097] Even if the leading end of the web W is thin, the occurrence of defects can be prevented. More specifically, as the leading end of the web W is folded, the web W is overlapped twice at the leading end of the web W. Therefore, even if the leading end of the web W before folding is thin, the thickness and strength of the web W that are unlikely to cause defects can be ensured. Therefore, it is possible to provide a control method for the sheet manufacturing apparatus 1 that prevents the occurrence of defects even if the leading end of the web W is thin. [Explanation of symbols]

[0098] 1...sheet manufacturing apparatus, 30...defibration section, 50...deposition section, 62...second conveying section as web conveying section, 62a...conveyor belt, 70...pressurizing section, 71...first roller, 72...second roller, 200...air injection section, 700...pressurizing roller pair, P1...belt-shaped sheet, P3...sheet, R1...rotation direction as first direction, R2...rotation direction as second direction, S1...first step, S2...second step, S3...third step, S4...fourth step, S5...fifth step, W...web.

Claims

1. A method for controlling a sheet manufacturing apparatus for producing a sheet from a material containing fibers, comprising the steps of: The sheet manufacturing apparatus includes: a defibration unit that defibrates the fiber-containing material to generate a defibrated material; a depositing section for depositing the defibrated material to form a web; a web transport section having a transport belt that contacts one side of the web to transport the web; a pressurizing section having a pair of pressurizing rollers consisting of a first roller and a second roller, and pressing the web to form the sheet; The control method for the sheet manufacturing apparatus includes: a first step of conveying the web by the conveyor belt; a second step of peeling the leading edge of the web from the conveyor belt; a third step of rotating the first roller in a first direction to fold the leading edge of the web; and a fourth step of rotating the first roller in a second direction opposite to the first direction and passing the web between the pair of pressure rollers to fold the leading end of the web.

2. The sheet manufacturing apparatus includes an air injection unit that injects compressed air, The method for controlling a sheet manufacturing apparatus according to claim 1 , wherein in the second step, the leading end of the web is peeled off from the conveyor belt and contacts the first roller by the jet of compressed air.

3. The method of controlling a sheet manufacturing apparatus according to claim 1 , wherein in the third step, the first roller is rotated in the first direction for a predetermined time to bend the leading end of the web.

4. A fifth step following the fourth step, The method for controlling a sheet manufacturing apparatus according to claim 1 , wherein in the fifth step, the web is pressed while passing between the pair of pressure rollers and is heated and shaped by the first roller.

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