Sheet Manufacturing Apparatus

The present application is based on, and claims priority from JP Application Serial Number 2024-061990, filed Apr. 8, 2024, the disclosure of which is hereby incorporated by reference herein in its entirety.

The present disclosure relates to a sheet manufacturing apparatus.

JP-A-2016-185622 discloses a configuration of a sheet manufacturing apparatus including an intermediate transport unit that transports a web to a downstream side while suctioning the web vertically upward, i.e., functions as a back transport belt. A mesh belt is disposed below the intermediate transport unit at the upstream side of the intermediate transport unit. That is, the web passes through the clearance between the intermediate transport unit and the mesh belt.

However, for example, although a smaller clearance is preferable when the web is suctioned to the intermediate transport unit and a larger clearance is preferable when the web is torn off, the method described in JP-A-2016-185622 does not have both functions. In other words, there is a demand for transporting the web with an appropriate clearance in the step of transporting the web.

A sheet manufacturing apparatus according to an aspect of the present disclosure is a sheet manufacturing apparatus for manufacturing a sheet from a material containing a fiber. The sheet manufacturing apparatus includes: an accumulation unit configured to accumulate the material by using airflow to form a web; a transport unit configured to transport the web; and a pressing unit configured to press the web to form the sheet. The accumulation unit includes: a drum member configured to stir the material; an accumulation belt on which the material discharged from the drum member is accumulated; a first suction unit disposed on an opposite side of the accumulation belt from the drum member and configured to perform suction to accumulate the material on the accumulation belt; and a first frame on which the accumulation belt and the first suction unit are installed. The transport unit includes: a transport belt configured to come into contact with a first surface of the web to hold the web; a second suction unit disposed above the transport belt and configured to perform suction to hold the web by suction; and a second frame on which the transport belt and the second suction unit are installed. An eccentric cam is disposed between the first frame and the second frame. A position of the second frame with respect to the first frame is changed by rotation of the eccentric cam.

The configuration of a sheet manufacturing apparatusis described below with reference to the drawings. In each of the following drawings, three axes orthogonal to each other are described 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 fibers. In addition, 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 process, and may perform a wet process. In the present specification, the term “dry process” refers to a process performed in air such as the atmosphere instead of being performed in a liquid.

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 used paper C, a sheet P, slit pieces S, unnecessary scrap pieces, and the like are transported are indicated by white arrows.

The sheet manufacturing apparatusmanufactures the sheet Pfrom the used paper C, which is a material containing fibers. In the sheet manufacturing apparatus, the first unit group, the third unit group, and the second unit groupare arranged from the −Y direction toward 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 groupvia a pipethat extends across the third unit group. The used paper C is subjected to defibration and the like in the second unit groupto become fibers and is then made into a mixture containing a binding material and the like.

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

The first unit groupincludes a buffer tank, a fixed-quantity supply unit, a merging section, and a pipe. In the first unit group, these components are arranged in the above order from the upstream side toward the downstream side. In addition, 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 a sheet Phaving a predetermined shape. Further, the first unit groupincludes a water supply unit. The water supply unitis a water storage tank. The water supply unitsupplies, through a water supply pipe (not illustrated), water for humidification 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 includes, for example, shredded pieces of used paper. Humidified air is fed 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 feeding mechanism (not illustrated). The measuring instrumentmeasures the weight of the used paper C. The feeding mechanism feeds the used paper C weighed by the measuring instrumentto the downstream merging section. That is, the fixed-quantity supply unitweighs the used paper C for each predetermined weight by using the measuring instrumentand feeds the used paper C to the downstream merging sectionby using the feeding mechanism.

In the merging section, shredded pieces of the slit pieces S fed from the shredding unitare merged and mixed with the used paper C fed 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 into the pipefrom the merging section. The pipetransports the used paper C from the first unit groupto the second unit groupusing airflow generated by a blower (not illustrated).

The second unit groupincludes a defibrating unitwhich 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. In addition, the second unit groupalso includes a recovery 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 material containing fibers, in a dry process and generates a defibrated material containing fibers. A known defibrating mechanism is applicable to 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 unitseparates relatively long fibers from relatively short fibers. The relatively short fibers, which may lower the strength of the sheet P, are sorted 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 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 are used as defibrated fibers for the material of the web W. Humidified air is fed 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) disposed at the distal end of the airflow pipe. Unnecessary components such as relatively short fibers and impurities are discharged from the pipeto the recovery 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 the 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 unitgenerates airflow that transports the fibers downstream and allows the binding material and the like to be mixed with the fibers in air to form a mixture. The recovery 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 filter can be cleaned by blowing the compressed air generated by the compressoronto the filter to blow off adhering particles.

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 the outside to each of the components of the sheet manufacturing apparatus.

The control unitincludes a central processing unit (CPU) and a storage unit including a random access memory (RAM), a read only memory (ROM), and the like. The storage unit 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 unit, a second transport unitas a transport unit, a first humidifying unit, an air ejection unit, a second humidifying unit, a drainage unit, and a pressing unit.

In the third unit group, the accumulation unit, the first transport unit, the second transport unit, the first humidifying unit, and the pressing unitare arranged in the above order from the upstream side to the downstream side. The air ejection unitis disposed inside the second transport unitand at the downstream end of the transport path of the web W in the second transport unit. The second humidifying unitis disposed below the first humidifying unit.

The accumulation unitforms the web W by accumulating the mixture generated from the defibrated material by using airflow and gravity. The accumulation unitincludes a drum member, an impeller memberinstalled in the drum member, a housingaccommodating the drum member, and a first suction unit. The mixture is taken into the drum memberthrough the pipe.

The first transport unitis disposed below the accumulation unit. 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 impeller memberis disposed inside the drum member. The impeller 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 size of 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 impeller memberrotating in the drum member. Humidified air is fed into the drum memberfrom the second humidifying unit.

The first suction unitis disposed below the drum member. The first suction unitsuctions air from the housingthrough multiple holes in the accumulation beltThis 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 the rotation of the rollers. As a result, 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 the rotation of the accumulation belt

The second transport unittransports the web W, instead of the first transport unit, on the downstream side of the first transport unit. The second transport unitseparates the web W from the upper surface of the accumulation beltand transports the web W toward the pressing unit. The second transport unitis disposed above the transport path of the web W and slightly upstream of the starting point of the return side of the accumulation beltThe +Y direction side of the second transport unitand the −Y direction side of the accumulation beltpartially overlap each other in the vertical direction.

The second transport unitincludes a transport beltfour rollers(see), and a second suction unitThe transport belthas multiple holes through which air passes. The transport beltis supported by the four rollersin a tensioned state and is rotated clockwise inby the rotation of the rollers.

The second suction unitis positioned along the transport path of the web W in the second transport unitand is positioned above the transport beltThe second suction unitsuctions air upward through the multiple holes in the transport beltAccordingly, a first surface which is an upper surface of the web W is held by suction on a lower surface of the transport beltWhen the transport beltin this state is rotated, the web W is transported downstream while being held by suction on the transport beltIn 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 unitof the third unit group. Specifically, the first humidifying unitis, for example, a mist humidifier and supplies mist M from below to the web W, which is transported by the second transport unit, to humidify the web W. The first humidifying unitis disposed below the second transport unitand faces the web W, which is transported by the second transport unit, in 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, improving 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 into contact with the transport beltreducing the possibility that the web W will adhere to the transport beltThe second transport unittransports the web W toward the pressing unit.

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

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 beltin 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 beltAt 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 beltThe 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 beltbending of the end of the web W and folding of the end of the web W are performed. Then, the web W is transported from the second transport unitto the pressing unit.

The pressing unitincludes a pressing roller pairincluding a first rollerand a second roller. The pressing unitallows 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 disposed substantially below the transport path of the web W, and the second rolleris disposed 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 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.

The web W is pressed when passing between the first rollerand the second roller. The first rollerhas a built-in electric heater and has the function of increasing the temperature of the roller surface. Like the first roller, the second rollerpreferably has the function of increasing the temperature of the roller surface with an electric heater.

The first rolleris rotationally driven by a stepping motor (not illustrated). The second rolleris a driven roller which is not driven by a motor but is rotated by the rotation of the first roller. Thus, the second rollerrotates in the opposite direction to the first rollerin a side view from the −X direction.