U.S. patent application number 14/965047 was filed with the patent office on 2016-06-16 for sheet manufacturing apparatus and sheet manufacturing method.
The applicant listed for this patent is SEIKO EPSON CORPORATION. Invention is credited to Kiyoshi TSUJINO.
Application Number | 20160168794 14/965047 |
Document ID | / |
Family ID | 56110611 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160168794 |
Kind Code |
A1 |
TSUJINO; Kiyoshi |
June 16, 2016 |
SHEET MANUFACTURING APPARATUS AND SHEET MANUFACTURING METHOD
Abstract
A sheet manufacturing apparatus includes a forming unit
configured to form a continuous sheet. The forming unit includes a
deposition unit configured to deposit a material containing fiber,
a pressurizing unit configured to pressurize a deposited web, and a
heating unit configured to heat the web. The forming unit further
includes a detection unit. The detection unit may be an optical
sensor including a light source configured to emit light from a
side of one surface of the continuous sheet (or a single sheet) and
a light receiver configured to receive the light on a side of the
other surface. The texture may be detected by the optical sensor
over the entire surface of the continuous sheet.
Inventors: |
TSUJINO; Kiyoshi;
(Matsumoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEIKO EPSON CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
56110611 |
Appl. No.: |
14/965047 |
Filed: |
December 10, 2015 |
Current U.S.
Class: |
162/198 ;
162/263 |
Current CPC
Class: |
D21F 11/00 20130101;
D21F 7/06 20130101 |
International
Class: |
D21F 7/06 20060101
D21F007/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2014 |
JP |
2014-252769 |
Claims
1. A sheet manufacturing apparatus comprising: a forming unit
configured to form a sheet by depositing, pressurizing, and heating
a material containing fiber; and a detection unit configured to
detect a texture of the sheet.
2. The sheet manufacturing apparatus according to claim 1, wherein
the detection unit is an optical sensor configured to emit light
from a side of one surface of the sheet, receive the light on a
side of the other surface of the sheet, and detect the texture of
an entire surface of the sheet.
3. The sheet manufacturing apparatus according to claim 1, further
comprising: a stack unit on which the sheet is stacked when the
texture of the sheet is relatively good; and a path configured to
prevent the sheet from going to the stack unit when the texture of
the sheet is relatively bad.
4. The sheet manufacturing apparatus according to claim 1, further
comprising: an application unit configured to apply a marking on
the sheet when the texture of the sheet is relatively bad.
5. A sheet manufacturing method comprising: forming a sheet by
depositing, pressurizing, and heating a material containing fiber;
and detecting a texture of the sheet.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to a sheet manufacturing
apparatus and a sheet manufacturing method.
[0003] 2. Related Art
[0004] There has hitherto been known a sheet manufacturing
apparatus that manufactures sheets by using waste paper as a raw
material. JP-A-2012-144819 describes a paper recycling apparatus
that forms paper by defibrating pieces of paper into fibers by a
dry-type defibrating machine. The paper recycling apparatus
described in JP-A-2012-144819 manufactures sheets of a desired size
by cutting a formed web (recycled paper) in a direction
intersecting the transfer direction of the web by a cutting
machine.
[0005] However, when such a paper recycling apparatus manufactures
a sheet by using waste paper as the raw material, the sheet
sometimes partly becomes black. When the dry-type defibrating
machine is used, lumps of fibers are sometimes mixed in the sheet.
In not only the dry-type paper recycling apparatus but also a
wet-type paper recycling apparatus, a sheet is sometimes creased by
pressure and heat during manufacturing. Further, since fibers are
deposited on a mesh-like moving object, deposition on the sheet
sometimes becomes uneven.
SUMMARY
[0006] An advantage of some aspects of the invention is to provide
a sheet manufacturing apparatus that can detect the texture of a
sheet.
[0007] A sheet manufacturing apparatus according to an aspect of
the invention includes a forming unit that configured to form a
sheet by depositing, pressurizing, and heating a material
containing fiber, and a detection unit configured to detect a
texture of the sheet.
[0008] In this sheet manufacturing apparatus, the texture of a
sheet can be detected by the detection unit, and a defective sheet
can be detected by using the detection result.
[0009] It is preferable that the detection unit should be an
optical sensor configured to emit light from a side of one surface
of the sheet, receive the light on a side of the other surface of
the sheet, and detect the texture of an entire surface of the
sheet.
[0010] In this sheet manufacturing apparatus, even when there is a
defect in a part of the sheet, it can be detected by detecting the
entire surface of the sheet with the optical sensor.
[0011] It is preferable that the sheet manufacturing apparatus
should further include a stack unit on which the sheet is stacked
when the texture of the sheet is relatively good, and a path
configured to prevent the sheet from going to the stack unit when
the texture of the sheet is relatively bad.
[0012] In this sheet manufacturing apparatus, since a sheet having
a relatively bad texture is transferred through a path different
from that for a sheet having a relatively good texture, it can be
separated from the sheet having the relatively good texture.
[0013] It is preferable that the sheet manufacturing apparatus
should further include an application unit configured to apply a
marking on the sheet when the texture of the sheet is relatively
bad.
[0014] In this sheet manufacturing apparatus, the texture can be
recognized as being relatively bad by applying the marking on the
sheet by the application unit.
[0015] A sheet manufacturing method according to another aspect of
the invention includes forming a sheet by depositing, pressurizing,
and heating a material containing fiber, and detecting a texture of
the sheet.
[0016] In this sheet manufacturing method, the texture of the sheet
can be detected, and a defective sheet can be detected by using the
detection result.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0018] FIG. 1 schematically illustrates a sheet manufacturing
apparatus according to an embodiment.
[0019] FIG. 2 is a side view schematically illustrating a detection
unit and a switch unit in the sheet manufacturing apparatus of the
embodiment.
[0020] FIG. 3 is a plan view schematically illustrating the
detection unit in the sheet manufacturing apparatus of the
embodiment.
[0021] FIG. 4A is a graph showing the intensity of transmitted
light in the widthwise direction of a sheet, and
[0022] FIG. 4B is a graph obtained by subjecting the graph of FIG.
4A to moving-averaging processing.
[0023] FIG. 5 is a histogram of the intensity of the transmitted
light in a sheet plane.
[0024] FIG. 6 is a side view schematically illustrating a detection
unit and an application unit in a first modification of the sheet
manufacturing apparatus of the embodiment.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0025] A preferred embodiment of the invention will be described in
detail below with reference to the drawings. The embodiment which
will be described hereinafter does not unduly limit the contents of
the invention described in the claims. All configurations which
will be described hereinafter are not essential constituent
elements of the invention.
1. Sheet Manufacturing Apparatus
1.1 Configuration
[0026] First, a sheet manufacturing apparatus according to an
embodiment will be described with reference to the drawings. FIG. 1
schematically illustrates a sheet manufacturing apparatus 100
according to the embodiment.
[0027] As illustrated in FIG. 1, the sheet manufacturing apparatus
100 includes a supplying unit 10, a manufacturing unit 102, and a
control unit 140. The manufacturing unit 102 manufactures a sheet.
The manufacturing unit 102 includes a crushing unit 12, a
defibrating unit 20, a classifying unit 30, a screening unit 40, a
mixing unit 50, a deposition unit 60, a web forming unit 70, a
sheet forming unit 80, and a cutting unit 90.
[0028] The supplying unit 10 supplies a raw material to the
crushing unit 12. For example, the supplying unit 10 is an
automatic feeding unit that continuously feeds the raw material to
the crushing unit 12.
[0029] The crushing unit 12 cuts the raw material supplied by the
supplying unit 10 into small pieces in the air. For example, the
small pieces are shaped to have a size of several centimeters
square. In the example of FIG. 1, the crushing unit 12 has a
crushing blade 14, and can cut the fed raw material with the
crushing blade 14. As the crushing unit 12, a shredder is used as
an example. The raw material cut by the crushing unit 12 is
received by a hopper 1 and then transferred (conveyed) to the
defibrating unit 20 through a pipe 2.
[0030] The defibrating unit 20 defibrates the raw material cut by
the crushing unit 12. Here, the term "defibrate" means to untangle
a raw material (defibration object) obtained by bonding a plurality
of fibers into discrete fibers. The defibrating unit 20 also has
the function of separating substances attached to the raw material,
such as resin grains, ink, toner, and a blur-preventing agent, from
the fibers.
[0031] The raw material having passed through the defibrating unit
20 is referred to as a "defibrated material." Besides untangled
defibrated material fibers, the "defibrated material" sometimes
includes grains of resin (resin for bonding a plurality of fibers),
coloring agents, such as ink and toner, and additive agents such as
a blur-preventing agent and a paper-force increasing agent, which
are separated from the fibers when the fibers are untangled. The
defibrated material is untangled in a string or ribbon shape. The
defibrated material may exist in a state in which it does not
tangle with other untangled fibers (an independent state), or may
exist in a state in which it tangles with other untangled
defibrated materials into a bundle (a state in which so-called
"lumps" are formed).
[0032] The defibrating unit 20 performs defibration in a dry method
in the atmosphere (air). Specifically, an impeller mill is used as
the defibrating unit 20. The defibrating unit 20 has the function
of generate an airflow for sucking the raw material and discharging
the defibrated material. By virtue of the generated airflow, the
defibrating unit 20 can suck the raw material together with the
airflow from an introduction port 22, defibrate the raw material,
and transfer the raw material to a discharge port 24. The
defibrated material having passed through the defibrating unit 20
is transferred to the classifying unit 30 through a pipe 3.
[0033] The classifying unit 30 classifies the defibrated material
that has passed through the defibrating unit 20. Specifically, the
classifying unit 30 separates and removes a material having a
relatively small size or low density (for example, resin grains, a
color agent, and an additive agent) from the defibrated material.
This can increase the ratio of fibers having a relatively large
size or high density to the defibrated material.
[0034] As the classifying unit 30, an airflow classifier is used.
The airflow classifier generates a swirling airflow and separates
the defibrated material by the difference in received centrifugal
force according to the size and density of the material to be
classified, and the classification point can be controlled by
adjusting the speed of the airflow and the centrifugal force.
Specifically, for example, a cyclone, an elbow jet, or an eddy
classifier is used as the classifying unit 30. In particular, the
illustrated cyclone can be suitably used as the classifying unit 30
because of its simple structure.
[0035] For example, the classifying unit 30 includes an
introduction port 31, a cylindrical part 32 to which the
introduction port 31 is connected, an inverted cone part 33 located
under the cylindrical part 32 and continuing from the cylindrical
part 32, a lower discharge port 34 provided in the center of a
lower portion of the inverted cone part 33, and an upper discharge
port 35 provided in the center of an upper portion of the
cylindrical part 32.
[0036] In the classifying unit 30, the motion of an airflow
carrying the defibrated material introduced from the introduction
port 31 is changed into a circumferential motion in the cylindrical
part 32. Thus, centrifugal force acts on the introduced defibrated
material, and the classifying unit 30 can separate the defibrated
material into fibers having a larger size and a higher density than
those of resin grains and ink grains (a first classified material)
and resin grains, a coloring agent, an additive agent, and so on
having a smaller size and a lower density than those of the fibers
(a second classified material). The first classified material is
discharged from the lower discharge port 34, and is introduced into
the screening unit 40 through a pipe 4. On the other hand, the
second classified material is discharged from the upper discharge
port 35 to a receiving unit 36 through a pipe 5.
[0037] The screening unit 40 introduces the first classified
material having passed through the classifying unit 30 from an
introduction port 42, and screens the first classified material
according to the fiber length. For example, a sieve is used as the
screening unit 40. The screening unit 40 includes a net (filter,
screen), and can separate the first classified material into fibers
or grains having a smaller size than the mesh size of the net (a
first screened material that can pass through the net) and fibers,
unfibrated pieces, and lumps having a larger size than the mesh
size of the net (a second screened material that does not pass
through the net). For example, the first screened material is
received by a hopper 6 and is transferred to the mixing unit 50
through a pipe 7. The second screened material is returned from a
discharge port 44 to the defibrating unit 20 through a pipe 8.
Specifically, the screening unit 40 is a cylindrical sieve that can
be rotated by a motor. For example, the net of the screening unit
40 is a metal net, an expanded metal formed by expanding a metal
plate having slits, or a punching metal formed by making holes in a
metal plate with a pressing machine.
[0038] The mixing unit 50 mixes the first screened material having
passed through the screening unit 40 and an additive agent
containing resin. The mixing unit 50 includes an additive-agent
supply unit 52 for supplying an additive agent, a pipe 54 for
transferring the first screened material and the additive agent,
and a blower 56. In the example of FIG. 1, the additive agent is
supplied from the additive-agent supply unit 52 to the pipe 54
through a hopper 9. The pipe 54 continues from the pipe 7.
[0039] In the mixing unit 50, an airflow can be generated by the
blower 56, and the first screened material and the additive agent
can be transferred while being mixed in the pipe 54. A mechanism
for mixing the first screened material and the additive agent is
not particularly limited. The mechanism may agitate the first
screened material and the additive agent by a blade rotating at
high speed, or may utilize the rotation of a container like a
V-shaped mixer.
[0040] As the additive-agent supply unit 52, a screw feeder
illustrated in FIG. 1 or a disc feeder (not illustrated) is used.
The additive agent supplied from the additive-agent supply unit 52
contains resin for bonding a plurality of fibers. At the time when
the resin is supplied, the plurality of fibers are not bonded. The
resin melts when passing through the sheet forming unit 80, and
thereby bonds the plurality of fibers.
[0041] The resin supplied from the additive-agent supply unit 52 is
thermoplastic resin or heat-curable resin, and examples of the
resin include AS resin, ABS resin, polypropylene, polyethylene,
polyvinyl chloride, polystyrene, acrylic resin, polyester resin,
polyethylene terephthalate, polyphenylene ether, polybutylene
terephthalate, nylon, polyamide, polycarbonate, polyacetal,
polyphenylenesulfide, and polyetheretherketone. These resins may be
used alone or may be appropriately mixed. The additive agent
supplied from the additive-agent supply unit 52 may be in the fiber
form or powder form.
[0042] The additive agent supplied from the additive-agent supply
unit 52 may contain a coloring agent for coloring the fibers, a
coagulation inhibitor for inhibiting coagulation of the fibers, and
a fire retardant agent for retarding firing of the fibers and the
like, besides the resin for bonding the fibers. A mixture (a
mixture of the first classified material and the additive agent)
that has passed through the mixing unit 50 is transferred to the
deposition unit 60 through the pipe 54.
[0043] In the deposition unit 60, the mixture having passed through
the mixing unit 50 is introduced from an introduction port 62, and
the tangled defibrated material (fibers) is untangled and dropped
while being dispersed in the air. Further, in the deposition unit
60, when the resin serving as the additive agent supplied from the
additive-agent supply unit 52 is in the fiber form, the resin is
untangled. Thus, the deposition unit 60 allows the mixture to be
uniformly deposited in the web forming unit 70.
[0044] As the deposition unit 60, a rotating cylindrical sieve is
used. The deposition unit 60 includes a net, and drops fibers or
grains having a size smaller than the mesh size of the net, which
are contained in the mixture having passed through the mixing unit
50, (fibers or grains that can pass through the net). For example,
the structure of the deposition unit 60 is the same as that of the
screening unit 40.
[0045] In the deposition unit 60, the "sieve" does not always need
to have the function of selecting a specific object. That is, the
"sieve" used as the deposition unit 60 refers to the one having a
net, and the deposition unit 60 may drop all of the mixture
introduced therein.
[0046] The web forming unit 70 forms a web W by depositing the the
passing-through material that has passed through the deposition
unit 60. For example, the web forming unit 70 includes a mesh belt
72, stretching rollers 74, and a suction mechanism 76.
[0047] The passing-through material having passed through apertures
of the deposition unit 60 (apertures of the net) is deposited on
the mesh belt 72 that is moving. The mesh belt 72 is stretched by
the stretching rollers 74. The mesh belt 72 hardly transmits the
passing-through material, but easily transmits air. The mesh belt
72 is moved by rotation of the stretching rollers 74. While the
mesh belt 72 continuously moves, the passing-through material
having passed through the deposition unit 60 continuously
accumulates, so that a web W is formed on the mesh belt 72. For
example, the mesh belt 72 is formed of metal, resin, cloth, or
nonwoven fabric.
[0048] The suction mechanism 76 is provided below the mesh belt 72
(on a side opposite from the deposition unit 60). The suction
mechanism 76 can generate a downward airflow (an airflow flowing
from the deposition unit 60 toward the mesh belt 72). By the
suction mechanism 76, the mixture dispersed in the air by the
deposition unit 60 can be sucked onto the mesh belt 72. This can
increase the discharge speed from the deposition unit 60. Further,
a downflow can be generated in a dropping path of the mixture by
the suction mechanism 76, and this can prevent the defibrated
material and the additive agent from tangling during dropping.
[0049] As described above, a soft and puffed web W containing much
air is formed via the deposition unit 60 and the web forming unit
70 (web forming process). The web W deposited on the mesh belt 72
is transferred to the sheet forming unit 80.
[0050] In the example of FIG. 1, a moisture-adjusting unit 78 is
provided to adjust the moisture in the web W. The
moisture-adjusting unit 78 can adjust the amount ratio of the web W
and water by adding water or vapor to the web W.
[0051] The sheet forming unit 80 forms a sheet S by pressurizing
and heating the web W deposited on the mesh belt 72. In the sheet
forming unit 80, the mixture of the defibrated material and the
additive agent mixed in the web W is heated, so that a plurality of
fibers in the mixture can be bonded with the additive agent (resin)
being disposed therebetween.
[0052] As the sheet forming unit 80, for example, a heating roller
(heater roller), a heat press forming apparatus, a hot plate, a
warm air blower, an infrared heater, or a flash fixing device is
used. In the example of FIG. 1, the sheet forming unit 80 includes
a first bonding unit 82 and a second bonding unit 84, and each of
the bonding units 82 and 84 has a pair of heating rollers 86. Since
the bonding units 82 and 84 are formed by the heating rollers 86, a
sheet S can be formed while continuously transferring the web W, in
contrast to a case in which the bonding units 82 and 84 are formed
by plate-like pressing devices (planar pressing devices). The
number of heating rollers 86 is not particularly limited.
[0053] The cutting unit 90 cuts the sheet S formed by the sheet
forming unit 80. In the example of FIG. 1, the cutting unit 90
includes a first cutting unit 92 for cutting the sheet S in a
direction intersecting the transfer direction of the sheet S, and a
second cutting unit 94 for cutting the sheet S in a direction
parallel to the transfer direction. For example, the second cutting
unit 94 cuts a sheet S that has passed through the first cutting
unit 92.
[0054] Through the above procedure, a single sheet S of a
predetermined size is formed. After cutting, the single sheet S is
discharged to a discharge unit 96.
1.2. Detection Unit
[0055] A detection unit 91 in the sheet manufacturing apparatus 100
will be described in detail with reference to
[0056] FIGS. 2 and 3. FIG. 2 is a side view schematically
illustrating a detection unit 91 and a switch unit 95 serving as a
part of a forming unit 106 in the sheet manufacturing apparatus 100
according to the embodiment. FIG. 3 is a schematic plan view of the
detection unit 91. In FIGS. 2 and 3, the deposition unit 60 and the
sheet forming unit 80 located on the upstream side of the forming
unit 106 in a transfer direction M are omitted, and the second
cutting unit 94 located on the downstream side in the transfer
direction M is omitted. In the following description, the terms
"upstream side" and "downstream side" refer to "upstream side in
the transfer direction M" and "downstream side in the transfer
direction M", respectively.
[0057] The forming unit 106 of the sheet manufacturing apparatus
100 illustrated in FIG. 2 includes the deposition unit 60, the web
forming unit 70, the sheet forming unit 80, the cutting unit 90,
and the discharge unit 96 that have been described with reference
to FIG. 1. In FIG. 2, the cutting unit 90 and the discharge unit 96
are illustrated. The forming unit 106 forms a continuous sheet S1
(a single sheet S2) by depositing, pressurizing, and heating a
material containing fibers. As illustrated in FIG. 2, the forming
unit 106 further includes a detection unit 91 and a switch unit 95
provided between the sheet forming unit 80 and the discharge unit
96 illustrated in FIG. 1.
[0058] The detection unit 91 detects the texture of a continuous
sheet S1. By detecting the texture of the continuous sheet S1 in
the detection unit 91, for example, a defective sheet that does not
meet a predetermined standard can be detected. When the detection
unit 91 is disposed on the downstream side of the first cutting
unit 92, it detects the texture of a single sheet S2.
[0059] Here, the term "texture (uniformity)" refers to the quality
(formation) of the continuous sheet S1 or the single sheet S2.
Specifically, the term "texture" refers to the degree (extent) of a
difference in shade that is seen when light is applied from one
surface of the continuous sheet S1, as shown in an experimental
example to be described later. That is, "a sheet having a
relatively good texture" refers to a continuous sheet S1 or a
single sheet S2 with which this difference in shade is small.
[0060] The detection unit 91 is an optical sensor that emits light
from one surface side of the continuous sheet S1 and receives the
light on the other surface side. In the detection unit 91 of FIG.
2, a light source unit 91a is disposed above the continuous sheet
S1, and a reading unit 91b is disposed at a position opposed to the
light source unit 91a with the continuous sheet S1 being disposed
therebetween. The reading unit 91b receives light having passed
through the continuous sheet S1, of the light emitted from the
light source unit 91a.
[0061] The light source unit 91a is a known light source used in an
optical sensor. As the light source unit 91a, for example, a light
emitting diode (LED) or a semiconductor laser diode (LD) can be
used.
[0062] The reading unit 91b can change the output according to the
intensity of received light (light having passed through the
continuous sheet S1), and can be formed by a known photodetector
used in the optical sensor. For example, such a photodetector can
be formed by a CCD line sensor capable of using the photoelectric
effect and composed of light receiving elements arranged in line or
an area sensor capable of performing two-dimensional detection and
composed of light receiving elements arranged in vertical and
horizontal directions.
[0063] The reading unit 91b can detect the texture over the entire
surface of the continuous sheet S1. That is, after the continuous
sheet S1 is cut in the first cutting unit 92, the reading unit 91b
detects the texture of the entire surface of a single sheet S2. By
detecting the entire surface of the continuous sheet S1 with the
reading unit 91b, even when a part of the continuous sheet 81 has a
defect, the defect can be detected.
[0064] Here, the term "entire surface" of the continuous sheet S1
may literally refer to the entire surface, or may refer to the
substantially entire surface. For example, the substantially entire
surface of the continuous sheet S1 may be a part of the continuous
sheet S1 to become a product (that is, the entire surface of the
single sheet S2).
[0065] As illustrated in FIG. 3, the detection unit 91 is disposed
all over the full width of the continuous sheet S1, or is disposed
to detect the texture at least over a full width SW of the single
sheet S2. When the reading unit 91b is a line sensor, the texture
of the entire surface of the continuous sheet S1 can be detected by
performing reading at a predetermined cycle in accordance with the
moving speed of the continuous sheet S1 in the transfer direction
M.
[0066] The reading unit 91b outputs information about the detected
light to the control unit 140. The control unit 140 can control the
downstream operation units on the basis of the information from the
reading unit 91b.
[0067] Since the detection unit 91 is disposed on the upstream side
of the first cutting unit 92, the continuous sheet S1 is an object
in the detection unit 91. However, the position of the detection
unit 91 is not limited thereto. For example, when the detection
unit 91 is disposed on the downstream side of the second cutting
unit 94, the object may be a cut single sheet S2.
1.3. First Cutting Unit
[0068] The first cutting unit 92 includes a blade unit 92b having,
at its lower end, a blade for cutting the continuous sheet S1, and
a cutting drive unit 92a for moving the blade unit 92b up and down
relative to the continuous sheet S1. The blade unit 92b has a blade
extending over the full width of the continuous sheet S1 in the
direction intersecting the transfer direction M. While the first
cutting unit 92 will be described as a so-called guillotine cutter
as an example, a known paper cutting mechanism, such as a rotary
cutter using a rotating disc-like blade, can be adopted.
[0069] The first cutting unit 92 is disposed on the downstream side
of the detection unit 91. The first cutting unit 92 is disposed
between rollers 93a that continuously rotate to send out a
continuous sheet S1 and rollers 93b that continuously or
intermittently rotate to send out a single sheet S2. On the
downstream side of the first cutting unit 92, the unillustrated
second cutting unit 94 is disposed to perform cutting along the
transfer direction M of the continuous sheet S1. The second cutting
unit 94 cuts both widthwise ends of the single sheet S2, and is
different from the first cutting unit 92 only in the cutting
direction. Hence, the second cutting unit 94 can adopt a mechanism
similar to that of the first cutting unit 92.
1.4. Switch Unit
[0070] As illustrated in FIG. 2, the switch unit 95 is provided
between the detection unit 91 and the discharge unit 96 and on the
downstream side of the cutting unit 90. For example, the switch
unit 95 is disposed at a position on the downstream side of the
rollers 93b that push out single sheets S2 cut by the first cutting
unit 92 in the direction orthogonal to the transfer direction
M.
[0071] The switch unit 95 includes a guide plate 95a for guiding
lower surfaces of the cut single sheets S2. In FIG. 2, the guide
plate 95a in a state shown by a solid line forms at least a part of
a first path 95b serving as a transfer path for the single sheets
S2, and the guide plate 95a in a state shown by a broken line forms
at least a part of a second path 97a serving as a transfer path for
the single sheets S2.
[0072] The first path 95b guides the single sheets S2 to the
discharge unit 96 via the rollers 93c. The discharge unit 96
includes a stack unit 96a on which the single sheets S2 are to be
stacked.
[0073] The second path 97a guides the single sheets S2 to a
collecting unit 97. The collecting unit 97 may be a box that can
accommodate the single sheets S2.
[0074] The switch unit 95 can distribute the single sheets S2 to
the first path 95b or the second path 97a by swinging the guide
plate 95a up and down according to a command from the control unit
140, as illustrated in FIG. 2. The control unit 140 gives the
command to the switch unit 95 by determining, on the output from
the reading unit 91b of the detection unit 91, whether or not the
texture of a single sheet S2 detected in the control unit 140 is
good.
[0075] For example, when the texture of a single sheet S2 is
relatively good, the control unit 140 sets the guide plate 95a to
the first path 95b to guide the single sheet S2 to the stack unit
96a. When the texture of the single sheet S2 is relatively bad, the
control unit 140 turns the guide plate 95a to the second path 97a
to guide the single sheet S2 to the second path 97a so that the
single sheet S2 does not reach the stack unit 96a. Since the single
sheet S2 having a relatively bad texture is guided to the path
different from the path for the single sheet S2 having a relatively
good texture, it can be separated from the single sheet S2 having
the relatively good texture.
[0076] Although not illustrated, the control unit 140 includes an
operating unit to be operated by the user, an output unit that
displays, for example, processing results of the operation units, a
storage unit that stores data on the texture as the criterion for
quality judgment and programs for the units, a storage medium that
stores various application programs and data and that can be read
by a computer, and a processing unit that performs various control
operations according to the programs stored in the storage unit and
the storage medium. For example, the processing unit can be
implemented as hardware, such as various processors (for example, a
CPU and a DSP) and an ASIC (for example, a gate array), or as
programs.
[0077] While the collecting unit 97 is provided in the second path
97a, the structure is not limited thereto. A transfer path may be
provided to return a single sheet S2 having a relatively bad
texture to the crushing unit 12 illustrated in FIG. 1.
[0078] The switch unit 95 may be disposed on the upstream side of
the second cutting unit 94 that is not illustrated in FIG. 2. This
is because such cutting with the second cutting unit 94 is
unnecessary for a defective single sheet S2 that does not become a
product and the lifetime of the cutter of the second cutting unit
94 is increased by omitting cutting of the single sheet S2 judged
defective.
1.5. Sheet Manufacturing Method
[0079] A sheet manufacturing method forms a continuous sheet S1 (a
single sheet S2) by depositing, pressurizing, and heating a
material containing fibers, and detects the texture of the
continuous sheet S1 (single sheet S2).
[0080] The sheet manufacturing method can be carried out by the
sheet manufacturing apparatus 100.
[0081] First, when the user requests an operation for manufacturing
a sheet S through the use of the unillustrated operating unit in
the control unit 140, the control unit 140 starts operations of the
operation units.
[0082] The control unit 140 receives an output signal from the
detection unit 91, and determines whether the texture of a
continuous sheet S1 is relatively good or relatively bad. When the
control unit 140 determines that the continuous sheet S1 is "a
relatively good sheet", it operates the guide plate 95a of the
switch unit 95 to discharge single sheets S2, which are obtained by
cutting the continuous sheet S1, to the stack unit 96a of the
discharge unit 96 in the first path 95b. Further, when the control
unit 140 determines that the continuous sheet S1 is "a relatively
bad sheet", it operates the guide plate 95a of the switch unit 95
to guide single sheets S2, which are obtained by cutting the
continuous sheet S1, to the second path 97a.
[0083] In this way, according to this sheet manufacturing method,
the texture of the continuous sheet S1 (single sheet S2) can be
detected, and a defective sheet can be detected by using the
detection result.
[0084] As illustrated in FIG. 3, the detection unit 91 detects the
texture in the width SW serving as the full width of the single
sheet S2 (a width except for diagonally shaded areas in FIG. 3 to
be cut and removed). Since the diagonally shaded areas are not
production parts, they do not need to be used for quality judgment
of the texture. Further, since deposition of the raw material in
the defibrating unit 20 (see FIG. 1) is relatively likely to become
uneven in the diagonally shaded areas, the diagonally shaded areas
are preferably not used for quality judgment of the texture.
[0085] Next, a texture quality judging method will be
described.
1.6. Quality Judging Method
[0086] FIG. 4A is a graph showing the intensity of transmitted
light in the widthwise direction of the continuous sheet S1, which
is detected by the reading unit 91b of the detection unit 91. The
horizontal axis shows the width SW of the continuous sheet S1, and
the vertical axis shows the intensity of transmitted light detected
by the reading unit 91b.
[0087] Although the graph of FIG. 4A can be used for quality
judgment of the texture as it is, since it sometimes includes
noise, noise is preferably removed to some extent by applying a
known noise removing method.
[0088] The graph of FIG. 4B is obtained by subjecting the graph of
FIG. 4A to moving-averaging processing. The horizontal axis and the
vertical axis are the same as those of FIG. 4A. In the graph of
FIG. 4B, more noise is removed than in the graph of FIG. 4A.
[0089] The control unit 140 prestores data serving as the criterion
for quality judgment of the texture. In FIG. 4B, the upper limit
and the lower limit are set at a predetermined reference ratio to
the average value of measured intensities of transmitted light, and
are shown by broken lines. When transmitted light out of the range
between the upper limit and the lower limit is detected, the
control unit 140 determines that a defect DF exists in a portion
corresponding to the transmitted light, and determines that a
single sheet S2 including the defect DF is "a relatively bad
sheet."
[0090] For example, such a defect DF appears as a block dot on the
single sheet S2 illustrated in FIG. 3.
[0091] By measuring such linear data in accordance with the moving
speed of the continuous sheet S1, the texture of the entire surface
of the continuous sheet S1 can be measured and judged without any
gap.
[0092] Alternatively, when the control unit 140 calculates a
standard deviation of the sheet by using the data of FIG. 4B and
the standard deviation is larger than a standard deviation serving
as an acceptabililty criterion for determining that the sheet is "a
relatively good sheet", which is prestored in the control unit 140,
it may be determined that the sheet is "a relatively bad
sheet."
[0093] While the control unit 140 makes determination on the basis
of the linear data in the direction orthogonal to the transfer
direction M of the continuous sheet S1 herein, determination may be
made on the basis of data on a sheet plane of a predetermined
length in the transfer direction M of the continuous sheet S1 (for
example, the length of a single sheet S2) instead. For example, a
histogram of the intensity of transmitted light in the sheet plane
of the single sheet S2 can be obtained by adding the data of FIG.
4A, as illustrated in FIG. 5. In FIG. 5, the horizontal axis shows
the intensity of transmitted light, and the vertical axis shows the
frequency.
[0094] FIG. 5 shows that the standard deviation shown by a solid
line more greatly varies than the standard deviation shown by a
broken line and the transmitted light in the sheet plane is uneven.
It can be considered that unevenness of the transmitted light
corresponds to the variation in thickness of the single sheet S2
and to the variation in deposition of the raw material.
[0095] Here, an acceptabililty reference standard deviation for "a
relatively bad sheet" is obtained beforehand by actual measurement,
and is stored in the control unit 140. The standard deviation
obtained as shown in FIG. 5 is compared with the reference standard
deviation. When the standard deviation is larger than the reference
standard deviation, it is determined that the sheet is "a
relatively bad sheet." For example, the standard deviation .sigma.
is 6.9 in the graph shown by the broken line in FIG. 5, and the
standard deviation .sigma. is 9.3 in the graph shown by the solid
line. When the reference standard deviation .sigma. serving as the
acceptabililty criterion is set at 7.0 or less, a single sheet S2
shown by the graph of the broken line is judged as "a relatively
good sheet", and a single sheet S2 shown by the graph of the solid
line is judged as "a relatively bad sheet."
2. First Modification of Sheet Manufacturing Apparatus
[0096] FIG. 6 is a side view schematically illustrating a detection
unit 91 and an application unit 98 in a first modification of the
sheet manufacturing apparatus 100 of the embodiment. In FIG. 6, a
deposition unit 60, a sheet forming unit 80, and so on located on
the upstream side of the detection unit 91 are not illustrated.
[0097] The sheet manufacturing apparatus 100 includes an
application unit 98 for applying a marking on a continuous sheet S1
having a relatively bad texture. The application unit 98 is
disposed on the downstream side of the detection unit 91 and
rollers 93a provided downstream of the detection unit 91 to convey
the continuous sheet S1. On the downstream side of the application
unit 98, a take-up unit 96b is provided to take up the continuous
sheet S1 around a take-up roller 96c.
[0098] When the control unit 140 determines that the continuous
sheet S1 is "a sheet having a relatively bad texture", according to
a command from the control unit 140, for example, the application
unit 98 applies a marking near a position on the continuous sheet
S1 where a defect is judged as being present, or applies a marking
on a predetermined position on "a relatively bad sheet" including
the defect when the continuous sheet S1 is cut into a single sheet
S2. By such marking with the application unit 98, it can be
recognized that the texture is bad.
[0099] A known method can be used for marking in the application
unit 98, and a marking may be not only a character for representing
a defective product but also a sign or a symbol, such as a bar
code, as long as the marking is to be printed. Instead of a printed
marking, embossing or hole machining may be used.
[0100] Instead of the take-up unit 96b, a cutting unit 90, a switch
unit 95, a discharge unit 96, and a collecting unit 97 illustrated
in FIGS. 1 and 2 may be adopted. In this case, single sheets S2
collected in the collecting unit 97 are sheets marked as "a
relatively bad sheet."
[0101] While the dry method is used in the above-described
embodiment, the sheet manufacturing apparatus of the invention may
adopt a wet method. For example, a disaggregating unit (pulper) may
be used instead of the defibrating unit 20, a deinking unit may be
used as the classifying unit 30, and a papermaking unit may be used
as the sheet forming unit 80.
[0102] Sheets S1, S1, and S2 manufactured by the sheet
manufacturing apparatus of the invention mainly refer to sheet-like
materials. However, the sheets are not limited to sheet-like
materials, and may be board-like or web-like materials. In this
specification, sheets are classified into paper and nonwoven
fabric. Paper includes a thin sheet formed using pulp or waste
paper as a raw material, and examples of paper include recording
paper for writing and printing, wall paper, wrapping paper, colored
paper, drawing paper, and Kent paper. Nonwoven fabric has a larger
thickness and a lower strength than paper, and examples of nonwoven
fabric include popular nonwoven fabric, a fiber board, tissue paper
(cleaning tissue paper), kitchen paper, a cleaner, a filter, a
liquid (waste ink and oil) absorbing material, a sound absorbing
material, a thermal insulating material, a cushioning material, and
a mat. The raw material may be plant fiber, such as cellulose,
chemical fiber, such as PET (polyethylene terephthalate) or
polyester, and animal fiber such as wool or silk.
[0103] In the invention, it is possible to partly omit the
configuration and to combine the embodiments and the modifications
within the scope including the features and advantages described in
the application.
[0104] The invention includes substantially the same configuration
as the configuration described in the embodiment (for example, a
configuration having the same functions, methods, and results, or a
configuration having the same object and effects). The invention
includes a configuration obtained by replacing the non-essential
parts of the configuration described in the embodiment. The
invention includes a configuration for realizing the same operation
results or a configuration for obtaining the same object as that of
the configuration described in the embodiment. The invention
includes a configuration obtained by adding the known art to the
configuration described in the embodiment.
[0105] The entire disclosure of Japanese Patent Application No.
2014-252769, filed Dec. 15, 2014 is expressly incorporated by
reference herein.
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