TECHNICAL FIELD
[0001] The present invention relates to a paper forming device of a paper machine in which
stock liquor is discharged from a headbox onto a wire to be dewatered, while being
transferred on the wire, by a dewatering equipment and to be further dewatered by
a suction box.
BACKGROUND ART
[0002] Fig. 3 shows a prior art example of a paper forming device in which stock liquor
of paper is discharged from a headbox onto a forming wire to be dewatered, while being
transferred on the wire, for forming a wet sheet.
[0003] In Fig. 3, numeral 1 designates a headbox that discharges stock liquor and numeral
2 designates a wire. The wire 2 is made in an endless loop form, as seen in Fig. 3,
and has its upper surface portion formed as a horizontal run portion (Fourdrinier
table portion) 3 for forming the wet sheet.
[0004] Below the wire 2 forming the horizontal run portion 3, in the order from the headbox
1 on the left hand side to the right hand side, a forming board 4, a dewatering equipment
5 and a suction box 6 are arranged.
[0005] Above the suction box 6, provided is a felt 7 that is constructed being belted between
a felt roll 8 and a pick-up roll 9 so as to run with the wire 2 sandwiched between
the felt 7 and an upper surface of the suction box 6.
[0006] Numeral 10 designates a frame and numeral 11 designates a save-all that is provided
on the frame 10 for receiving water dewatered of the stock liquor on the wire 2. Numeral
12 designates a breast roll that is provided below the headbox 1 for guiding the wire
2.
[0007] In the paper forming device shown in Fig. 3 having the construction as mentioned
above, stock liquor S is discharged from the headbox 1 onto the forming board 4 portion
of the horizontal run portion 3 of the wire 2. While being transferred on the wire
2, the stock liquor is dewatered by the dewatering equipment 5. As the stock is being
transferred on the wire 2, it reaches on the suction box 6 and is nipped between the
wire 2 and the felt 7. Thus, by a vacuum force acting through the suction box 6 and
by a compression force acting due to tension of the felt 7, dewatering is further
carried out, so that a wet sheet mat M is formed.
[0008] Then, the wet sheet mat M formed on the wire 2, together with the felt 7, is transferred
to a press part (not shown) as the next step by the pick-up roll 9.
[0009] The prior art paper forming device described above has a comparatively large length
of the horizontal run portion 3 and thus, in case of forming a thin paper at a high
velocity of 850m/minute or more, scattering or the like of the stock liquor, while
being transferred on the wire 2, is caused, so that there arises a problem that uniformity
of the paper forming is obstructed and operation of the machine becomes difficult.
[0010] In view of the abovementioned problem of the paper forming device in the prior art
paper machine, it is an object of the present invention to provide a paper forming
device of a paper machine that has a structure enabling to perform a change-over between
a thin paper high velocity forming and a thick paper forming.
DISCLOSURE OF THE INVENTION
[0011] In order to solve the abovementioned problem in the prior art, the present invention
provides a paper forming device of a paper machine in which stock liquor is discharged
from a headbox onto a wire so that the stock liquor, while being transferred on the
wire, is dewatered by a dewatering equipment and is further dewatered by a suction
box, characterized in being constructed such that a forming roll, wound with a felt,
is arranged movably up and down above the wire near the headbox and, when a thin paper
is to be formed, the forming roll is moved down so that a nip of the stock liquor
is formed between the wire and the felt.
[0012] According to the paper forming device of the present invention constructed as mentioned
above, when a thin paper of 35g/m
2 or less, for example, is to be formed, the forming roll is moved down to thereby
press down the wire. In this state, forming of a wet sheet is done. In this state,
the stock liquor discharged from the headbox onto the wire is immediately nipped between
the wire and the felt to receive a centrifugal force and a compression force due to
the tension of the wire. Hence, the most part of the water in the stock liquor is
dewatered and the wet sheet is rapidly formed.
[0013] On the other hand, when a thick paper of 35g/m
2 or more, for example, is to be formed, the forming roll is moved up and a wet sheet
is formed by the same construction as the prior art device shown in Fig. 3.
[0014] Thus, according to the paper forming device of the present invention, when a thin
paper is to be formed, by moving down the forming roll, the stock liquor discharged
from the headbox is immediately nipped between the wire and the felt. Thereby, forming
of the wet sheet can be done with the open portion being shortened, scattering or
the like of the stock liquor on the wire is suppressed and a high velocity forming
of the thin paper becomes possible.
[0015] Also, according to the paper forming device of the present invention, when the thin
paper is to be formed, the stock liquor discharged from the headbox is immediately
nipped between the wire and the felt wound around the forming roll, so that a shear
force is generated in the stock liquor and fibers are oriented in the running direction
of the wire. Thereby, a soft thin paper can be easily formed.
[0016] Thus, according to the device of the present invention, not only forming of a thick
paper but also a high velocity forming of a thin paper become possible.
[0017] In the paper forming device of the present invention, while the wire is pressed down
by the forming roll and a running direction of the wire changes, such a construction
that, when the forming roll is moved down to thereby press down the wire, the headbox
and the forming board arranged under the wire are inclined in the same direction as
the running direction of the wire so pressed down is preferably employed. Thus, the
position relation between the wire running direction and the headbox and/or the forming
board can be maintained.
[0018] Also, the paper forming device of the present invention can be constructed such that
a wire roll is arranged upwardly movably under the wire downstream of the forming
roll and, when the wire roll is moved up to thereby lift up the wire, the forming
roll is moved down so that a horizontal running direction of the wire near the headbox
is maintained. Thus, even when the forming roll is moved down, the horizontal running
direction of the wire between a breast roll and the forming roll can be maintained
and, in forming not only a thick paper but also a thin paper, displacement of the
headbox and the forming board becomes unnecessary.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
Fig. 1 is a side view showing a construction of a paper forming device of a first
embodiment according to the present invention.
Fig. 2 is a side view showing a construction of a paper forming device of a second
embodiment according to the present invention.
Fig. 3 is a side view showing a construction of a prior art paper forming device.
BEST MODE FOR CARRYING OUT THE INVENTION
[0020] Herebelow, the paper forming device of the present invention will be described more
concretely based on embodiments according to the present invention as shown in Figs.
1 and 2. It is to be noted that, in Figs. 1 and 2, the same parts and components as
those shown in Fig. 3 are denoted with the same reference numerals as in Fig. 3 and
repeated description thereon will be omitted.
(First Embodiment)
[0021] The paper forming device of a first embodiment shown in Fig. 1 will be first described.
[0022] In Fig. 1, numeral 13 designates a forming roll that is arranged movably up and down
above the wire 2 near the headbox 1. The felt 7 is elongated beyond the length of
the prior art felt that extends on the suction box 6, so that the felt 7 is belted
between the forming roll 13 and the pick-up roll 9. The forming roll 13 is constructed
so as to be supported either in a lower position A or in an upper position B in Fig.
1 by an appropriate mechanism that is not shown. Numeral 14 designates a curved blade
that is formed having a curvature on a surface of No. 1 blade. The No. 1 blade is
a blade of the first one of two units of the dewatering equipment 5.
[0023] Also, in the paper forming device shown in Fig. 1, the headbox 1 and the forming
board 4 are respectively constructed to be inclinedly movable from the horizontal
positions shown by dotted lines to the inclined positions shown by solid lines. As
the mechanism to support the headbox 1 and the forming board 4 in their horizontal
positions and inclined positions may be appropriately selected from the known art,
detailed construction thereof is not shown.
[0024] Other portions of the structure of the paper forming device shown in Fig. 1 are substantially
the same as those portions of the device shown in Fig. 3 and, by denoting them with
the same reference numerals, description thereon is omitted.
[0025] In the paper forming device of the first embodiment of Fig. 1 constructed as mentioned
above, when a thin paper of 35g/m
2 or less, for example, is to be formed, the forming roll 13 is moved down to the lower
position A, as shown by solid lines, so that the felt 7 and the wire 2 in this position
are pressed down by the forming roll 13.
[0026] Thereby, the stock liquor S discharged from the headbox 1 is nipped comparatively
immediately by and between the felt 7, that is wound around the forming roll 13, and
the wire 2, and the most part of the water contained in the stock liquor S is dewatered
by a centrifugal force and a compression force due to the tension of the wire 2 so
as to form a wet sheet.
[0027] Also, it is so constructed that, when the forming roll 13 is moved down to thereby
press down the wire 2 for forming the thin paper, both of the headbox 1 and the forming
board 4 are correspondingly inclined, as shown by solid lines in Fig. 1, so that the
position relation between the running direction of the wire 2, so pressed down, and
the headbox 1 and/or the forming board 4 is maintained in the same way as in the structure
in which all of the wire 2, the headbox 1 and the forming board 4 are horizontally
arranged.
[0028] Further, the curved blade 14 as the No. 1 blade of the first unit of the dewatering
equipment 5 has its surface formed in the curvature, the wire 2, the wet sheet and
the felt 7 can smoothly run on the curved blade 1.
[0029] Thus, according to the paper forming device shown in Fig. 1, even when the thin paper
is formed at a high velocity, scattering or the like of the stock liquor is suppressed
and a high quality thin paper can be stably formed.
[0030] On the other hand, when a thick paper of 35g/m
2 or more, for example, is to be formed, if the forming roll 13 is kept in the abovementioned
lower position, a smooth nipping of the stock liquor becomes difficult at the nip
portion between the felt 7 and the wire 2 so that so-called a backflow of the stock
liquor arises and a serious defect in the paper may be brought about. Hence, the forming
roll 13 is moved up to the upper position B, as shown by dotted lines in Fig. 1.
[0031] At the same time, the headbox 1 and the forming board 4 are arranged in the horizontal
position, as shown by dotted lines in Fig. 1, so as to be in line with the running
direction of the wire 2 near the headbox 1. Thus, in case of forming the thick paper,
the paper forming device of the first embodiment is operated as a device to form the
wet sheet in the same way as the prior art paper forming device shown in Fig. 3.
[0032] As mentioned above, the paper forming device of the first embodiment of Fig. 1 enables
to stably form a high quality paper both of a thin paper and a thick paper by a single
unit of the machine.
(Second embodiment)
[0033] The paper forming device of a second embodiment shown in Fig. 2 will be described.
[0034] In Fig. 2, numeral 15 designates a wire roll that is arranged under the wire 2 between
two units of the dewatering equipment 5 and is constructed so as to be supported either
in an upper position A' shown by solid lines in Fig. 2 or in a lower position B' shown
by dotted lines. In the paper forming device of the present second embodiment, the
headbox 1 and the forming board 4 are arranged in the horizontal positions as shown
in Fig. 2 unlike the structure of the first embodiment in which they are inclinedly
movable. Other portions of the structure of the second embodiment shown in Fig. 2
are substantially the same as those portions of the paper forming device of the first
embodiment shown in Fig. 1 and description thereon will be omitted.
[0035] As understood by the above description, in the paper forming device of the second
embodiment shown in Fig. 2, it is so constructed that, when the forming roll 13 is
moved down to thereby press down the felt 7, in order to maintain the position relation
between the running direction of the wire 2 and the headbox 1 and/or the forming board
4, neither the headbox 1 nor the forming board 4 is inclined but the wire roll 15
is moved up to thereby lift up the wire 2.
[0036] When a thin paper is to be formed by the paper forming device of the second embodiment
of Fig. 2, the forming roll 13 is moved down to position A, as shown by solid lines
in Fig. 2, that makes contact with the wire 2 and the wire roll 15 is moved up to
the upper position A', so that a predetermined wire holding angle of the forming roll
13 is obtained. Thus, in the present second embodiment, even when the forming roll
13 is moved down, the horizontal position relation between the breast roll 12 and
the forming roll 13 is maintained and such a construction as to arrange the headbox
1 and the forming board 4 inclinedly movably is not necessary.
[0037] Also, in the present second embodiment, for the reason as mentioned above, such a
curved blade as that 14 provided in the paper forming device of the first embodiment
of Fig. 1 is not necessary.
[0038] When a thick paper is to be formed by the paper forming device of the second embodiment
of Fig. 2, the forming roll 13 is moved up to position B, as shown by dotted lines
in Fig. 2, and the wire roll 15 is moved down to the lower position B', as shown by
dotted lines, that is, the wire roll 15 is moved down until the horizontal running
direction of the wire 2 is realized. In this state, the wire roll 15 is used as a
table roll. Otherwise, the wire roll 15 may be constructed so as to be positionable
slightly below the wire 2.
[0039] In the paper forming device of the present second embodiment, as compared with the
first embodiment, there is needed no such a mechanism, that requires a high mounting
accuracy, to incline the headbox 1 and the forming board 4 corresponding to the inclination
of the running direction of the wire 2. Hence, there is obtained an advantage that
no loss time is caused for a position adjustment of the equipment and devices, a change-over
of the stock liquor pipings, etc.
[0040] In forming the thin paper by the device of the present second embodiment also, stock
liquor S discharged from the headbox 1 is nipped comparatively immediately by and
between the felt 7 and the wire 2 and occurrence of scattering or the like of the
stock liquor S can be suppressed even in the high velocity paper forming. Moreover,
in the thin paper forming, contact of the wire 2 to the dewatering equipment 5 and
the suction box 6 is minimized. Thereby, the necessary drive force of the wire is
reduced and the life of the wire can be elongated.
[0041] While the invention has been described concretely based on the embodiments as illustrated,
the invention is not limited to the embodiments but, as a matter of course, may be
added with various modifications within the scope of the invention as defined by the
appended claims.
[0042] For example, while the felt 7 wound around the forming roll 13 has been described
as the elongated one of the felt on the suction box 6, the felt to be wound around
the forming roll 13 may be constructed as a loop of felt that runs between other rolls
independently of the felt on the suction box 6.
[0043] Also, while the No. 1 blade of the first unit of the dewatering equipment 5 has been
described as the curved blade 14, not necessarily the curved blade 14, such one as
enables a smooth running of the wire 2, the wet sheet and the felt 7 on the dewatering
equipment may be provided. For example, a roll may be provided immediately before
the dewatering equipment instead of the curved blade 14.
INDUSTRIAL APPLICABILITY
[0044] As described above, the present invention provides a paper forming device of a paper
machine in which stock liquor is discharged from a headbox onto a wire so that the
stock liquor, while being transferred on the wire, is dewatered by a dewatering equipment
and is further dewatered by a suction box, characterized in being constructed such
that a forming roll, wound with a felt, is arranged movably up and down above the
wire near the headbox and, when a thin paper is to be formed, the forming roll is
moved down so that a nip of the stock liquor is formed between the wire and the felt.
[0045] According to the paper forming device of the present invention constructed as mentioned
above, when a thin paper is to be formed, the forming roll is moved down to thereby
press down the wire. In this state, forming of the wet sheet is done. In this state,
the stock liquor discharged from the headbox onto the wire is immediately nipped between
the wire and the felt to receive a centrifugal force and a compression force due to
the tension of the wire. Hence, the most part of the water in the stock liquor is
dewatered and the wet sheet is rapidly formed.
[0046] Thus, according to the paper forming device of the present invention, when a thin
paper is to be formed, by moving down the forming roll, the stock liquor discharged
from the headbox is immediately nipped between the wire and the felt. Thereby, scattering
or the like of the stock liquor on the wire is suppressed and a high velocity forming
of the thin paper becomes possible. Also, a shear force is generated in the stock
liquor and fibers are oriented in the running direction of the wire. Thereby, a soft
thin paper can be easily formed. Thus, according to the device of the present invention,
a high velocity forming of the thin paper becomes possible.
[0047] On the other hand, when a thick paper is to be formed, the forming roll is moved
up and the wet sheet is formed by the same construction as a prior art device.
[0048] In the paper forming device of the present invention that is preferably constructed
such that, when the forming roll is moved down to thereby press down the wire, the
headbox and the forming board arranged under the wire are inclined in the same direction
as the running direction of the wire so pressed down, the position relation between
the wire running direction and the headbox and/or the forming board can be maintained.
[0049] Also, the paper forming device of the present invention can be constructed such that
a wire roll is arranged upwardly movably under the wire downstream of the forming
roll and, when the wire roll is moved up to thereby lift up the wire, the forming
roll is moved down so that the horizontal running direction of the wire near the headbox
is maintained. Then, even when the forming roll is moved down, the horizontal running
direction of the wire between the breast roll and the forming roll can be maintained
and, in forming not only a thick paper but also a thin paper, displacement of the
headbox and the forming board becomes unnecessary.