Sheet Manufacturing Apparatus and Method for Manufacturing Sheet

The present application is based on, and claims priority from JP Application Serial Number 2024-088749, filed May 31, 2024, the disclosure of which is hereby incorporated by reference herein in its entirety.

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

JP-A-2022-156155 discloses a configuration of a fiber structure manufacturing apparatus in which a cleaning roller rotates while being in contact with a felt roller so that bristles of a brush of the cleaning roller can scrape out paper dust from a felt fabric to clean it. Furthermore, generally, the paper dust can be removed from the cleaning roller by inserting a plate-shaped blade into the cleaning roller, and the paper dust can be discharged to the outside.

However, in the above-described method, the brush of the cleaning roller is readily damaged by the insertion of the plate-shaped blade into the cleaning roller, resulting in a problem of easy deterioration of the cleaning performance.

A sheet manufacturing apparatus is a sheet manufacturing apparatus including an accumulation mechanism that accumulates a fiber material, a transport mechanism that transports the accumulated fiber material by using a transport belt, and a forming mechanism that forms the transported fiber material into a sheet. The transport mechanism includes a rotary brush that cleans a surface of the transport belt, a comb that has a front end inserted into the rotary brush and a base located outside the rotary brush, a paddle that is located on an opposite side of the comb from the rotary brush and sweeps a surface of the comb at a position where the paddle does not come in contact with the rotary brush.

A method for manufacturing a sheet includes accumulating a fiber material, transporting the accumulated fiber material by using a transport belt, and forming the transported fiber material into a sheet. The method uses a rotary brush that comes in contact with a surface of the transport belt, a comb that has a front end inserted into the rotary brush, and a paddle that is located on an opposite side of the comb from the rotary brush and sweeps a surface of the comb at a position where the paddle does not come in contact with the rotary brush. The method includes rotating the transport belt and the rotary brush to move a residual fiber attached to the transport belt to the comb via the rotary brush, and sweeping a surface of the comb with the paddle to remove the residual fiber from the comb.

The configuration of a sheet manufacturing apparatuswill be described below with reference to the drawings. In each of the following drawings, three axes orthogonal to each other are referred to as an X axis, a Y axis, and a Z axis. A direction along the X axis is referred to as an “X direction”, a direction along the Y axis is referred to as a “Y direction”, and a direction along the Z axis is referred to as a “Z direction”. An arrow direction is referred to as a + direction, and a direction opposite to the + direction is referred to as a—direction. A view from the +Z direction or the −Z direction is referred to as a plan view or planar. In addition, in the sheet manufacturing apparatus, a leading side in a transport direction of a raw material, a web, a sheet, and the like may be referred to as a downstream side, and a trailing side in the transport direction may be referred to as an upstream side.

First, a configuration of the sheet manufacturing apparatuswill be described with reference to. The sheet manufacturing apparatusmanufactures

sheets from a material containing a fiber (hereinafter referred to as a fiber material). In the following, used paper C will be described as an example of the fiber material, but the fiber material may be a mass of other kinds of fibers, such as cotton, wool, polyester, and a mixture thereof. The sheet manufacturing apparatusregenerates sheets from pieces of paper, such as used paper, in a dry process. The sheet manufacturing apparatusis not limited to a dry type apparatus and may be a wet type apparatus. In the present specification, the dry type means that the process is not performed in a liquid, but in air, such as the atmosphere.

As illustrated in, the sheet manufacturing apparatusincludes a first unit group, a second unit group, and a third unit group. The first unit group, the second unit group, and the third unit groupare supported by frames (not illustrated). In, directions in which the used paper C, sheets P, slit pieces S, unnecessary scrap pieces, and the like are transported are indicated by white arrows.

The sheet manufacturing apparatusmanufactures sheets Pfrom the used paper C, which is a fiber material. In the sheet manufacturing apparatus, the first unit group, the third unit group, and the second unit groupare arranged from the −Y direction to the +Y direction, in a side view from the −X direction.

The used paper C is transported from the first unit groupto the second unit groupthrough a pipethat extends across the third unit group. The used paper C is subjected to defibration or the like in the second unit groupto be separated into fibers and then is mixed with a binding material or the like to become a mixture.

The mixture is transported to the third unit groupthrough a pipe. The mixture is made into a web W in the third unit groupand then is formed into a strip-shaped sheet P. The strip-shaped sheet Pis cut into the sheets Pin the first unit group.

The first unit groupincludes a buffer tank, a fixed-quantity supply unit, a merging section, and the pipe. In the first unit group, these components are arranged in the above order from the upstream side toward the downstream side. The first unit groupalso includes a first cutting unit, a second cutting unit, a tray, and a shredding unit.

The first cutting unitand the second cutting unitcut the strip-shaped sheet Pinto the sheets Phaving a predetermined shape. Furthermore, the first unit groupincludes a water supply unit. The water supply unitis a water storage tank. The water supply unitsupplies water for humidification through a water supply pipe (not illustrated) to each of a first humidifying unitand a second humidifying unit, which are humidifying units (described later).

The used paper C is put into the buffer tankthrough a raw material charging port. The used paper C contains fibers such as cellulose and is, for example, a piece of shredded used paper. Humidified air is supplied into the buffer tankfrom the second humidifying unitof the third unit group.

The used paper C to be defibrated is temporarily stored in the buffer tankand is then transported to the fixed-quantity supply unitaccording to the operation of the sheet manufacturing apparatus. The sheet manufacturing apparatusmay include a shredder for shredding the used paper C or the like on the upstream side of the buffer tank.

The fixed-quantity supply unitincludes a measuring instrumentand a supply mechanism (not illustrated). The measuring instrumentmeasures the weight of the used paper C. The supply mechanism supplies the used paper C weighed by the measuring instrumentto the downstream merging section. That is, the fixed-quantity supply unitweighs a predetermined mass of the used paper C each time by using the measuring instrumentand supplies the used paper C to the downstream merging sectionby using the supply mechanism.

In the merging section, shredded pieces of the slit pieces S supplied from the shredding unitare merged and mixed with the used paper C supplied from the fixed-quantity supply unit. The slit pieces S and the shredding unitwill be described later. The used paper C mixed with the shredded pieces flows from the merging sectioninto the pipe. Through the pipe, the used paper C is transported from the first unit groupto the second unit groupusing airflow generated by a blower (not illustrated).

The second unit groupincludes a defibrating unit, which is a dry defibrator, a separation unit, a pipe, a mixing unit, and a pipe. In the second unit group, these components are arranged in the above order from the upstream side to the downstream side. The second unit groupalso includes a collection unit, a compressor, a power supply unit, a pipeconnected to the separation unit, and an airflow pipe.

The used paper C transported through the pipeflows into the defibrating unit. The defibrating unitdefibrates the used paper C, which is a fiber material, in a dry process to generate a defibrated material containing fibers. A known defibrating mechanism is applicable as the defibrating unit. In the present embodiment, a defibrating mechanism including a rotary blade is used as the defibrating unit. The defibrating mechanism generates fibers by shredding and defibrating the used paper C by using the rotary blade. The used paper C becomes a defibrated material containing fibers when the entangled fibers included in the used paper C are untangled by the defibrating unit, and then is transported to the separation unit.

The separation unitsorts the defibrated fibers. Specifically, the separation unitremoves components contained in the fibers that are unnecessary for the manufacture of the sheet P. That is, the separation unitsorts the fibers into relatively long fibers and relatively short fibers. The relatively short fibers, which may lower the strength of the sheet P, are selected and removed by the separation unit. The separation unitalso removes impurities, such as coloring materials and additives contained in the used paper C.

In the present embodiment, a disc-type separation mechanism including a separation filter is used as the separation unit. The separation mechanism sorts out and separates relatively short fibers and impurities that can pass through the separation filter from relatively long fibers that cannot pass through the separation filter. The relatively long fibers, which are defibrated fibers, are used as the material of the web W. Humidified air is supplied into the separation unitfrom the second humidifying unitof the third unit group.

The relatively short fibers and the like are removed from the defibrated fibers at the separation unit. Then, the defibrated fibers are transported to the mixing unitthrough the pipeby airflow generated by a blower (not illustrated) located at the distal end of the airflow pipe. Unnecessary components such as relatively short fibers and impurities are discharged from the pipeto the collection unit.

The mixing unitmixes the fibers with a binding material and the like in air to form a mixture. Although not illustrated, the mixing unitincludes a flow path through which fibers are transported, a fan, a hopper, a feeding pipe, and a valve. The mixture flows from the mixing unitinto the pipe.

The fan of the mixing unitmixes the binder and the like in the air to form a mixture while transporting the fibers downstream by the generated airflow. The collection unitincludes a filter (not illustrated). The filter filters out unnecessary components, such as relatively short fibers transported through the pipeby the airflow.

The compressorgenerates compressed air. The filter may be clogged with fine particles or the like of the unnecessary components. The compressed air generated by the compressorcan be blown onto the filter to blow off attached particles and clean the filter.

The power supply unitincludes a power supply device (not illustrated) that supplies electric power to the sheet manufacturing apparatusand a control unit. The power supply unitdistributes electric power supplied from an external source to each of the components of the sheet manufacturing apparatus.

The control unitincludes a central processing unit (CPU) and a memory including a random-access memory (RAM), a read only memory (ROM), and the like. The memory stores various programs for controlling the sheet manufacturing apparatus. The control unitmay include dedicated hardware (application specific integrated circuit: ASIC) that executes at least one of various processes. That is, the control unitmay be configured as one or more processors that operate in accordance with a computer program (software), one or more dedicated hardware circuits, such as an ASIC, or a circuit including a combination thereof.

The third unit groupaccumulates and compresses the mixture containing fibers to form the strip-shaped sheet P, which is recycled paper. The third unit groupincludes an accumulation mechanism, a transport mechanism, a first humidifying unit, an air ejection unit, a second humidifying unit, a drainage unit, and a forming mechanism.

In the third unit group, the accumulation mechanism, the first transport unit, the transport mechanism, the first humidifying unit, and the forming mechanismare arranged in this order from the upstream side to the downstream side. The air ejection unitis located in the transport mechanismand located at the downstream end of the transport path of the web W in the transport mechanism. The second humidifying unitis located below the first humidifying unit.

The accumulation mechanismforms the web W by accumulating the mixture, which was generated from the defibrated material, by using airflow and gravity. The accumulation mechanismincludes a drum member, a blade memberinstalled in the drum member, a housingthat houses the drum member, and a first suction unit. The mixture is taken into the drum memberthrough the pipe.

The first transport unitis located below the accumulation mechanism. The first transport unitincludes an accumulation beltand five rollers on which the accumulation beltis supported in a tensioned state. The first suction unitfaces the drum memberwith the accumulation beltinterposed therebetween in the direction along the Z axis.

The blade memberis located inside the drum member. The blade memberis rotationally driven by a motor (not illustrated). The drum memberis a semi-cylindrical sieve. The drum memberhas a mesh having the function of a sieve on a side surface facing downward. The drum memberallows particles such as the fibers or the mixture smaller than the mesh openings of the sieve to pass therethrough from the inside to the outside.

The mixture is discharged to the outside of the drum memberwhile being stirred by the rotating blade memberin the drum member. Humidified air is supplied to the inside of the drum memberfrom the second humidifying unit.

The first suction unitis located below the drum member. The first suction unitsuctions air from the housingthrough multiple holes in the accumulation belt. This generates airflow which accumulates the mixture on the accumulation belt

The multiple holes in the accumulation beltallow air to pass therethrough but do not easily allow the fibers, the binding material, and the like contained in the mixture to pass therethrough. Accordingly, the mixture discharged to the outside of the drum memberis suctioned downward together with the air. The first suction unitis a known suction device such as a suction fan. The mixture is dispersed in the air inside the housingand is accumulated on the upper surface of the accumulation beltby gravity and the airflow generated by the first suction unitto form the web W.

The accumulation beltis an endless belt and is supported by five rollers in a tensioned state. The accumulation beltis rotated counterclockwise inby rotation of the rollers. Accordingly, the mixture is continuously accumulated on the accumulation beltto form the web W. The web W contains a relatively large amount of air and is soft and swollen. The first transport unittransports the formed web W downstream by rotation of the accumulation belt

The transport mechanismtransports the web W on the downstream side of the first transport unit, instead of the first transport unit. The transport mechanismseparates the web W from the upper surface of the accumulation beltand transports the web W toward the forming mechanism. The transport mechanismis located above the transport path of the web W and slightly upstream of the starting point of the return side of the accumulation belt. The +Y direction portion of the transport mechanismand the −Y direction portion of the accumulation beltpartially overlap each other in the vertical direction.

The transport mechanismincludes the accumulation belt, a transport belt, four rollers(see), a second suction unit, and a motor and a gear for driving a belt (not illustrated). The accumulation beltis included in both the accumulation mechanismand the transport mechanism. The transport belthas multiple holes through which air passes. The transport beltis supported by the four rollersin a tensioned state and is rotated in a clockwise direction, which is a first direction, inby rotation of the rollers.

The second suction unitis located along the transport path of the web W in the transport mechanismand is located above the transport belt. The second suction unitsuctions air upward through the multiple holes in the transport belt. Accordingly, a first surface, which is an upper surface, of the web W is held by suction on a lower surface of the transport belt. When the transport beltin this state is rotated, the web W is transported downstream while being held by suction on the transport belt. In other words, the transport belttransports the web W while being in contact with the first surface of the web W. The second suction unitis a known suction device, such as a suction fan.

The first humidifying unithumidifies the web W containing fibers accumulated at the accumulation mechanismof the third unit group. Specifically, the first humidifying unitis, for example, a mist humidifier, and humidifies the web W transported by the transport mechanismby supplying the mist M from below the web W. The first humidifying unitis located below the transport mechanismand faces the web W transported by the transport mechanismin the direction along the Z axis. For example, a known humidifier such as an ultrasonic humidifier can be used as the first humidifying unit.

When the web W is humidified with the mist M, the function of the binding material contained in the web W is promoted, increasing the strength of the sheet P. Furthermore, since the web W is humidified from below, droplets derived from the mist M do not fall onto the web W. Furthermore, since the web W is humidified from the opposite side from the first surface of the web W, which comes in contact with the transport belt, adhesion of the web to the transport beltcan be reduced. The transport mechanismtransports the web W toward the forming mechanism.

The air ejection unitis included in the transport mechanismand located downstream of the second suction unit. Although not illustrated, the air ejection unitincludes a compressed air tank and an ejection nozzle. The compressed air tank supplies compressed air to the ejection nozzle. The air ejection unitejects compressed air downward through the ejection nozzle to the web W. The compressed air tank stores compressed air supplied from, for example, a compressor for the air ejection unit(not illustrated).

The ejection nozzle is an elongated opening extending in the direction along the X axis. The ejection nozzle faces the web W, which is transported by the transport belt, in the direction along the Z axis. The compressed air ejected from the air ejection unitpasses through the transport beltand hits the first surface of the web W that is held by suction on the lower surface of the transport belt. At this time, since the ejection nozzle is longer than the web W in the direction along the X axis, the compressed air ejected from the ejection nozzle is blown to the entire widthwise area of the web W.

In this way, the web W is separated from the transport belt. The compressed air is ejected by the air ejection unitwhen the downstream end of the web W reaches a region facing the air ejection unit. Then, after the end of the web W is separated from the transport belt, the end of the web W is bent, or the end of the web W is folded. Then, the web W is transported from the transport mechanismto the forming mechanism.

A collection unit(see) for collecting residual fibers PP (see) attached to the transport beltis located next to the transport belt. Specifically, as described above, the transport belthas the multiple holes through which air is suctioned by the second suction unit, and thus the remaining residual fibers PP are attached to the transport belt. This may cause defects, such as failing to vacuum, and to avoid such defects, the residual fibers PP attached to the transport beltare removed. Specific configurations and methods will be described later.

The forming mechanismincludes a pressing roller pairincluding a first rollerand a second roller. The forming mechanismallows the web W to pass between the rollers of the pressing roller pairto form a strip-shaped sheet Pfrom the web W.

The first rollerand the second rollerare paired and each have a substantially cylindrical shape. The rotation axis of the first rollerand the rotation axis of the second rollerextend along the X axis. The first rolleris located substantially below the transport path of the web W, and the second rolleris located substantially above the transport path of the web W. The first rollerand the second rollerrotate in proximity to each other while the strip-shaped sheet Pis being formed from the web W.

In the direction along the X axis, the first rollerand the second rollerare longer than the web W, that is, the width of the web W. Thus, the web W is reliably pinched between the first rollerand the second roller.