JP3593001B2 - Twin wire former - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique related to a twin wire former of a paper machine, and more particularly to a technique for dehydrating a paper raw material liquid sandwiched between wires.
[0002]
[Prior art]
A twin wire former is used as a paper layer forming device of a paper machine. In this twin-wire former, two wires (wire mesh) each form a loop, and a paper material liquid (fibrous suspension) is formed in a papermaking gap formed between these two wires.N), The water is removed from the paper raw material liquid by various dewatering devices, and a fiber mat (fibrous strip) is gradually formed, which grows to form a paper web. It has become.
[0003]
As a conventional twin wire former, as shown in the main part configuration diagram of FIG. 7, a suction roll 14 is installed in an initial dewatering section (an entrance of a papermaking gap) and is generally called a roll former or a roll blade former. Are known. In this conventional twin wire former, the paper raw material liquid 2 ejected from the head box 1 is sandwiched in a wedge-shaped gap formed by the two wires 3 and 4, and the suction rolls 14 wrap the wires 3 and 4, By applying a suction force to the area where the wires 3 and 4 are wrapped, dehydration from the paper raw material liquid 2 is advanced.
[0004]
A large number of dehydration holes are arranged at regular intervals on the outer peripheral surface of the suction roll 14. Each dewatering hole is bored with its center line oriented in the direction of the normal to the roll circumference, that is, perpendicular to the peripheral surface, and communicates with the internal space formed inside the suction roll 14. A suction box is provided in this internal space, and a suction force by a negative pressure is applied only to a range where the wires 3 and 4 are wrapped.
[0005]
[Problems to be solved by the invention]
However, the conventional twin wire former in which the suction roll 14 is applied to the initial dewatering section as described above has the following problems.
That is, in order to dewater the paper raw material liquid 2, it is sufficient to apply a suction force to the area where the wires 3 and 4 are wrapped. However, since the suction roll 14 rotates together with the traveling of the wires 3 and 4, It is necessary to make a dewatering hole on the entire peripheral surface. In addition, when the dewatering holes are formed on the entire peripheral surface in this way, the suction force is applied only to the area where the wires 3 and 4 are wrapped. Therefore, it is necessary to install the suction box inside the roll as described above. For this reason, the conventional twin-wire former required a great deal of labor and time to manufacture the suction roll 14, and increased the manufacturing cost.
[0006]
The present invention has been made in view of such a problem, and has been made to secure a high dehydrating power with a simple structure.TsuIt aims to provide an in-wire former.
[0007]
[Means for Solving the Problems]
To achieve the above object, the present invention according to claim 1 is provided.Twin wire formerIs a twin wire forging a fibrous suspension by sandwiching a fibrous suspension in a papermaking gap formed between two traveling wires.In maA dewatering surface that slides in contact with one of the two wires and is curved in the running direction of the wire; and a plurality of dewatering holes formed in the dewatering surface.Dewatering devices are alternately arranged on both sides of the two wires.The dewatering hole is formed so as to be inclined in the running direction of the wire with respect to the normal line of the dewatering surface at the entrance of the dewatering hole, and the running direction of the wire and the arrangement direction of the dewatering holes. Are arranged at regular intervals on the dewatering surface so thatFurthermore, the curvature of the dewatering surface of the dewatering device on the downstream side in the running direction of the wire is set to be larger than the curvature of the dewatering surface of the dewatering device on the upstream side in the running direction of the wire.It is characterized by:
[0008]
According to a second aspect of the present invention, there is provided the twin wire former according to the first aspect, wherein at least one of a wire contact length of the dewatering surface, a hole diameter of the dewatering hole, a tilt angle, and an opening ratio is set to a value of the wire. A different value is set for the dehydrator on the upstream side in the traveling direction and the dehydrator on the downstream side in the traveling direction of the wire.
[0009]
In the twin wire former according to the third aspect of the present invention, in the configuration according to the first or second aspect, the dewatering hole is communicated with a vacuum source, and the suction force from the vacuum source is applied to the dehydration hole. It is characterized in that the degree of vacuum of the vacuum source is set to be different between the dehydrator on the upstream side in the traveling direction of the wire and the dehydrator on the downstream side in the traveling direction of the wire.
[0010]
In the twin wire former according to the present invention, the dewatering device on the upstream side in the traveling direction of the wire is directed toward the inlet of the papermaking gap. It is characterized by being arranged.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 show a twin-wire former according to a first embodiment of the present invention. First, the main configuration of the twin-wire former of the present embodiment will be described with reference to FIG. In FIG. 1, the same parts as those of the conventional twin wire former (FIG. 7) described above are denoted by the same reference numerals.
[0012]
The present embodiment is characterized in that a suction roll having a high manufacturing cost is not provided in the initial dewatering section, but a dehydrating device having the same dewatering power but having a low manufacturing cost is provided instead. That is, in the present embodiment, as shown in FIG. 1, the dewatering device 5 is disposed at the entrance of the papermaking gap (see FIG. 3) formed by the two endless wires 3 and 4, and The paper raw material liquid (fibrous suspension) 2 is ejected toward the dewatering device 5 at the entrance.
[0013]
The dewatering device 5 is a device for performing dewatering using negative pressure in the same manner as a suction roll. The water is sucked and dehydrated. The dehydrator 5 is connected to a suction blower (vacuum source) not shown, and the inside of the dehydrator 5 is maintained at a negative pressure by the suction blower. Then, a suction force acts between the paper raw material liquid 2 and the dewatering hole 51 due to a pressure difference between the atmospheric pressure and the inside of the dewatering device 5.
[0014]
The dewatering surface 50 is formed to be curved with a constant curvature, and the wires 3 and 4 are wound in the curved direction. By being wound around the dewatering surface 50 formed in such a curved surface, a normal surface pressure is applied to the wires 3 and 4, and this surface pressure is applied to the paper material liquid 2 together with the suction force from the dewatering hole 51. It is designed to encourage dehydration. The direction of entry of the wire 4 at the entrance to the dewatering surface 50 and the direction of exit of the wire 4 at the exit from the dehydration surface 50 are determined by the dehydration surface 50 at the entrance or the exit in order to ensure that the wire 4 is in close contact with the dehydration surface 50. Are set so as to form a predetermined angle inward from the tangent direction of. The curvature and the wire contact length of the dewatering surface 50 can be set to be substantially the same as the curvature and the wire contact length of a conventional suction roll.
[0015]
A plurality of dewatering holes 51 are formed on the dewatering surface 50. FIG. 2A is a diagram illustrating a cross-sectional shape of the dewatering hole 51. As shown in this figure, the present dewatering device 5 is characterized in that the dewatering holes 51 are formed by being inclined in the running direction of the wires 3 and 4. That is, the center line L of the dewatering hole 51_CIs the normal L of the dewatering surface 50 at the entrance of the dewatering hole 51._VAngle θ_ZD(0 ° <θ_ZD<90 °). By inclining the dewatering hole 51 in the running direction of the wires 3 and 4 as described above, it is possible to improve the dewatering ability by an operation described later. Note that the specific inclination angle θ_ZDIs the water content, suction power (degree of vacuum), wire, and the like of the paper raw material liquid 2 according to the required dewatering capacity (for example, the maximum dewatering capacity capable of removing only water without removing sand contained in the paper raw material liquid 2). The setting is made according to the traveling speeds of 3, 4 and the like.
[0016]
The arrangement of the dehydration holes 51 is arbitrary, but is preferably arranged at regular intervals as shown in FIG. 2A in consideration of making the suction force uniform. However, if the running direction of the wire 4 matches the arrangement direction of the dewatering holes 51 (that is, θ_MD= 0), a line having no dewatering holes 51 in the running direction of the wire 4 is formed, and due to the uneven dewatering state and the resulting non-uniform dispersion of fibers, streaks are formed in the finished product. There is a possibility that it will end. Therefore, at least the running direction of the wire 4 and the arrangement direction of the dewatering holes 51 are not matched (that is, θ_MD$ 0). The hole diameter and the opening ratio of the dewatering holes 51 can be set to be substantially the same as the hole diameter and the opening ratio of the dewatering holes in the conventional suction roll.
[0017]
The above is the configuration of the dewatering device 5 which is a characteristic part of the present invention. The entire configuration of the twin-wire former when the dewatering device 5 is disposed in the initial dewatering unit is as shown in FIG. 3, for example. In FIG. 3, the same portions as those of the conventional twin wire former (FIG. 7) are denoted by the same reference numerals.
Here, as shown in FIG. 3, a plurality of devices 9 to 13 for dehydrating the paper raw material liquid 2 are disposed on the traveling lines of the wires 3 and 4. First, a first dewatering device 9 for performing initial dewatering is disposed at an entrance of a papermaking gap formed between the wires 3 and 4. The first dehydrator 9 corresponds to the above-described dehydrator 5. On the downstream side of the first dehydrator 9, a second dehydrator 10 and a third dehydrator 11, which apply a pulse-like dehydration pressure by a blade (not shown), are arranged alternately at different positions. Further on the downstream side, a suction couch roll 12 for performing dehydration by vacuum suction and a transfer box 13 for performing aeration dehydration are provided. Since the second and third dewatering devices 10 and 11, the suction couch roll 12 and the transfer box 13 are known, the detailed configuration and the like are omitted here.
[0018]
With the configuration described above, in the present twin-wire former, first, the paper raw material liquid 2 contained in the head box 1 is ejected from the head box 1 toward the wedge-shaped inlet of the papermaking gap. Then, after landing on the wire 3 or the wire 4, the vehicle starts running while being sandwiched by the papermaking gap between the wires 3 and 4. Dehydration is further performed from both sides of the wires 3 and 4 by the dehydration devices 10 and 11. Paper webs are gradually formed between the wires 3 and 4 by the action of the dewatering devices 9 to 11, and the formed paper webs are dewatered by the suction coach roll 12 at a higher degree of vacuum. Then, after aeration and dehydration are performed in the transfer box 13 that follows, the transfer box 13 is transferred to the next press part.
[0019]
Here, FIG. 4 shows the operation of the first dewatering device 9, that is, the dewatering device 5, which is a unique part of the present in-wire former. Hereinafter, the operation and effect of the dehydrating apparatus 5 will be described with reference to FIG.
As shown in FIG. 4, since the dewatering surface 50 of the dewatering device 5 is formed in a curved shape, when the wires 3 and 4 are wrapped on the curved dewatering surface 50, the wires 3 and 4 have normal directions. Surface pressure is applied. Due to this surface pressure, the papermaking gap 6 between the wires 3 and 4 is compressed, and an inertial force acts on the white water in the paper raw material liquid 2 toward the outside in the running direction of the wires 3 and 4. At this time, since the suction force from the dehydration hole 51 formed in the dehydration surface 50 also acts on the wire 4 side, the white water is dehydrated from the dehydration hole 51 by the action of the inertial force and the suction force.
[0020]
By the way, when a dehydration hole is formed in a fixed flat plate member as in the present dehydrator 5, the dehydration hole on the flat plate member does not rotate with the wires 3 and 4 like the dehydration hole of the suction roll. When the vehicle 4 runs, a large relative speed difference occurs between the dewatering hole and the wire 4. Therefore, for example, when the dewatering hole is formed perpendicularly to the peripheral surface (that is, in the normal direction of the peripheral surface) similarly to the dewatering hole of the suction roll, the direction in which the suction force acts and the inertia force of the white water Since the directions do not match, white water cannot be efficiently sucked into the dehydration holes. Further, if the suction degree is increased by increasing the degree of vacuum to compensate for the suction efficiency, the friction between the wire 4 and the dewatering surface increases, and excessive power is required to drive the wire 4. Will be done.
[0021]
In this regard, in the present dewatering device 5, since the dewatering hole 51 is formed so as to be inclined toward the traveling direction of the wires 3 and 4, the direction of the suction force is the inertia force of the white water as shown in FIG. Approached in the direction. For this reason, in the dewatering hole 51 of the present dewatering device 5, the change in the direction of white water when dewatered from the wire 4 is smaller than in the dewatering hole drilled in the normal direction, and the white water is efficiently sucked into the dewatering hole 51. be able to. Therefore, according to the present dewatering device 5, it is not necessary to increase the degree of vacuum to increase the suction force, and it is possible to reduce the frictional resistance between the wire 4 and the dewatering surface 50 and reduce the required power. As a result, it becomes possible to obtain the same level of dewatering power with the same level of power as the conventional suction roll.
[0022]
In addition, when compared with the conventional suction roll, the suction roll rotates together with the traveling of the wire, so it is necessary to make a dewatering hole on the entire peripheral surface. However, since the dewatering surface 50 of the dewatering device 5 is fixed, The dewatering hole 51 may be formed only in the portion in contact with the wire 4. Accordingly, in the case of the present dewatering device 5, the total number of dewatering holes to be formed can be extremely small as compared with the suction roll if the curvature and the opening ratio are equal. In addition, in the case of the present dewatering device 5, it is not necessary to install a suction box inside the roll such that a suction force acts only on the surface that comes into contact with the wire like a suction roll. That is, according to the present dewatering device 5, it is possible to significantly reduce the labor and time required for the production as compared with the conventional suction roll.
[0023]
Therefore, according to the present twin wire former, by providing the dewatering device 5 having the above-described operation and effect in the initial dewatering unit, it is possible to achieve the same effect as the conventional twin wire former having the suction roll in the initial dewatering unit without requiring excessive power. This has the advantage that a high dewatering power can be secured and the production cost can be significantly reduced.
[0024]
In the present embodiment, the case where the dehydrator 5 is provided in the initial dehydrator is described, but the installation location of the dehydrator 5 is not limited to the initial dehydrator. For example, in the case shown in FIG. 3, the present dewatering device 5 may be applied to the second dewatering device 10 and the third dewatering device 11. Further, it is of course possible to use the main dewatering device 5 instead of the suction coach roll 12. However, since the water content of the paper raw material liquid 2 decreases toward the downstream side, the suction force required to promote the dehydration increases toward the downstream side. Therefore, when the main dewatering device 5 is provided on the downstream side, the frictional resistance between the dewatering surface 50 and the wire increases as the suction force increases, and the required power increases. Therefore, as the installation position of the present dewatering device 5, the initial dewatering section where the required suction force is relatively small, particularly the initial dewatering section where the water content of the paper raw material liquid 2 is the highest is preferable.
[0025]
Further, the number of the dehydrating devices 5 to be installed is not limited to one as in the present embodiment. That is, it is also possible to install a plurality as in the second embodiment and the third embodiment described below.
FIG. 5 is a schematic diagram showing a main configuration of a twin-wire former according to a second embodiment of the present invention. Here, as shown in FIG. 5, a dehydrator 5A is disposed on the wire 4 side of the initial dehydrator in the same manner as in the first embodiment, and a dehydrator 5B is disposed on the wire 3 downstream of the dehydrator 5A. Has been established. Each of the dehydrators 5A and 5B has the same configuration as the dehydrator 5 described in the first embodiment. That is, in each of the dewatering devices 5A and 5B, a plurality of dewatering holes 51A and 51B are formed in the dewatering surfaces 50A and 50B so as to be inclined in the running direction of the wires 3 and 4 with respect to the normal line of the dewatering surfaces 50A and 50B. Has been established. The design parameters [the curvatures and wire contact lengths of the dewatering surfaces 50A and 50B, the hole diameters of the dewatering holes 51A and 51B, the inclination angles and the opening ratios, and the suction power (degree of vacuum)] are different between the dewatering devices 5A and 5B. They are set to the same value.
[0026]
As described above, by alternately disposing the dehydrating devices 5A and 5B having the same configuration as the dehydrating device 5 described in the first embodiment on both sides of the wires 3 and 4, the same dehydrating action can be performed on both sides of the paper raw material liquid 2. Can be used, and paper with a small difference between the front and back sides can be manufactured. That is, according to the twin wire former, in addition to the advantage obtained in the first embodiment, there is also a unique advantage that paper having a small difference between front and back can be manufactured.
[0027]
Note that FIG. 5 shows only the main configuration of the twin-wire former. However, the overall configuration is, for example, the configuration shown in FIG. What is necessary is just to comprise the dehydrating apparatus 10 as said dehydrating apparatus 5B. Furthermore, the third dewatering device 11 can also be configured as a dewatering device having the same configuration as the dewatering devices 5A and 5B.
[0028]
Next, a main configuration of a twin-wire former according to a third embodiment of the present invention will be described with reference to FIG. This embodiment also includes a plurality of dehydrators having the same operation and effect as the first embodiment as in the second embodiment, and here, as shown in FIG. A dehydrating device 5C is disposed on the wire 3 and a dehydrating device 5D is disposed downstream of the dehydrating device 5C on the wire 3 side.
[0029]
However, in the second embodiment, the design parameters of each dehydrating apparatus are made common, whereas in the present embodiment, each of the dehydrating apparatuses has a unique setting. By providing a plurality of dewatering devices as in the second embodiment and arranging at least one of them on a different side from the remaining dewatering devices, it is possible to manufacture paper with a small difference between front and back as described above. become. However, the water content and the arrangement of the fibers of the paper raw material liquid 2 gradually change as they go downstream in the running direction of the wires 3 and 4, that is, as the dewatering progresses. Therefore, in order to produce paper having a smaller difference between the front and back sides, it is preferable to change the degree of the dehydration action in each step.
[0030]
Here, as shown in FIG. 6, the curvature of the dewatering surfaces 50C and 50D and the contact length with the wire are different between the upstream dehydrating device 5C and the downstream dehydrating device 5D. The curvature of the dewatering surface 50D is increased, and the contact length with the wire is shortened. Here, the negative pressure in the downstream dehydrator 5D is set higher than the negative pressure in the upstream dehydrator 5C.
[0031]
Since the water content of the paper raw material liquid 2 decreases toward the downstream side, a larger suction force is required to further promote dewatering. However, in the twin wire former, the dewatering device 5D is used as described above. In addition to increasing the suction force by increasing the negative pressure inside, the surface pressure acting on the wires 3 and 4 is also increased by increasing the curvature of the dewatering surface 50D. Therefore, not only the suction force from the dewatering hole 51D but also the inertia force acting on the white water in the outward direction of the wires 3 and 4 is increased, so that the paper raw material liquid 2 having a reduced water content can be efficiently dewatered.
[0032]
Therefore, according to the twin wire former, it is possible to more appropriately maintain the degree of the dewatering force acting on the front and back of the paper raw material liquid 2, and it is possible to manufacture paper having a smaller difference between the front and back. There is. Further, as the suction force increases, the frictional resistance between the dewatering surface 50D and the wire 3 also increases. However, in this twin-wire former, the wire contact length of the dewatering surface 50D of the dehydrating device 5D is shortened. There is also an advantage that the increase can be suppressed and the increase in required power can be suppressed.
[0033]
In the present embodiment, the suction force (degree of vacuum), the curvature of the dewatering surfaces 50C and 50D, and the wire contact length among the design parameters of the dewatering devices 5C and 5D are set to be different, so that the front and back of the paper raw material liquid 2 are set. Although the aim is to optimize the degree of action of the dehydration force acting on the dehydration force, it is possible to bring the degree of action of the dehydration force closer to a more appropriate degree only by setting at least one of the above design parameters to a different value. is there. Furthermore, by setting at least one of the other design parameters, that is, at least one of the hole diameter, the inclination angle, and the opening ratio of the dewatering holes 51C and 51D, the degree of action of the dewatering force can be made closer to a more appropriate degree. Can be.
[0034]
FIG. 6 shows only the main configuration of the twin-wire former. However, the overall configuration is, for example, the configuration shown in FIG. What is necessary is just to comprise the dehydration apparatus 10 as said dehydration apparatus 5D. Further, the third dewatering device 11 can also have the same configuration as the dewatering devices 5C and 5D. In this case, each design parameter of the third dewatering device 11 may be common to the dewatering device 5C or the dewatering device 5D, but it is more preferable to appropriately set the parameters according to the required dewatering capacity.
[0035]
As described above, three embodiments have been described as embodiments of the present invention. However, the present invention is not limited to the above-described embodiments, and may be variously modified and implemented without departing from the spirit of the present invention. it can. For example, in the dehydrating apparatus according to each of the above-described embodiments, the curvature of the dehydrating surface is constant, and the hole diameter, the inclination angle, and the opening ratio of the dehydrating hole are also constant. The hole diameter, the inclination angle, and the opening ratio of the holes may be set to different values on the upstream side and the downstream side in the traveling direction of the wire.
[0036]
Since the dehydration conditions such as the water content of the paper raw material liquid 2 gradually change as going downstream, the degree of the dehydration force acting on the front and back of the paper raw material liquid 2 can be reduced by changing the design parameters. There is an advantage that it is possible to keep the paper properly, and it is possible to manufacture paper having a smaller difference between the front and back sides. At this time, it is not necessary to set all the parameters to different values, and it is also possible to set the at least one parameter among the curvature of the dewatering surface, the diameter of the dewatering hole, the inclination angle, and the opening ratio to different values. It is possible to bring the degree of force action closer to a more appropriate degree.
[0037]
Further, in each of the above-described embodiments, the dewatering hole is communicated with the vacuum source to apply a suction force to the dewatering hole to forcibly suction the dewatered white water. Even if it is not performed, as described above, the dewatered white water can be efficiently dewatered by simply inclining the drilling angle of the dewatering hole toward the running direction of the wire with respect to the normal of the dewatering surface at the entrance of the dewatering hole. It is possible to lead inside.
[0038]
【The invention's effect】
As described in detail above, the present invention according to claim 1Twin wire formerAccording to the above, a plurality of dewatering holes are drilled in the dewatering surface curved toward the running direction of the wire, and the drilling angles of these dewatering holes are set in the running direction of the wire with respect to the normal of the dewatering surface at the entrance of the dewatering hole. Tilt towardEquipped with dewatering equipmentTherefore, there is an advantage that dewatered white water can be efficiently guided into the dewatering hole, and dehydration can be promoted. In addition, dewatering holes are arranged at regular intervals on the dewatering surface so that the running direction of the wire and the arrangement direction of the dewatering holes do not match, preventing uneven dewatering and the resulting uneven distribution of fibers. Quality products can be manufactured.Further, such a dewatering device is alternately arranged on both sides of the two wires, and the curvature of the dewatering surface of the dewatering device on the downstream side in the running direction of the wire is adjusted to the curvature of the dewatering surface on the upstream side in the running direction of the wire. Since it is set to be larger than the curvature, the surface pressure acting on the wire can be made larger on the downstream side than on the upstream side, thereby efficiently dehydrating the paper raw material liquid having a reduced water content. Can do it.
In this way, while maintaining the same high dewatering power as a twin wire former equipped with a suction roll, the production cost can be significantly reduced, and it acts on the front and back of the fiber suspension interposed in the papermaking gap. This has the advantage that the degree of action of the dewatering force can be kept properly, and paper with a smaller difference between front and back can be manufactured.
[0039]
According to the twin wire former of the present invention, at least one of the wire contact length of the dewatering surface, the hole diameter of the dewatering hole, the inclination angle, and the opening ratio is dewatered on the upstream side in the running direction of the wire. Since different values are set for the device and the dewatering device on the downstream side in the traveling direction of the wire, the degree of dehydration acting on the front and back of the fibrous suspension interposed in the papermaking gap can be properly maintained. , It is possible to produce paper with less difference between front and back.
[0040]
According to the twin wire former of the third aspect of the present invention, the dewatering hole is communicated with the vacuum source, and the suction force from the vacuum source is applied to the dewatering hole. There is an advantage that power can be secured. Also, the total number of dewatering holes to be drilled can be extremely small compared to a suction roll if the curvature and the opening ratio are equal, and the inside of the roll such that a suction force acts only on the surface that contacts the wire like a suction roll. Since there is no need to install a suction box, there is also an advantage that the labor and time required for production can be greatly reduced as compared with the suction roll, and the production cost can be reduced. Furthermore, since the degree of vacuum of the vacuum source is set to a different value for the dehydrator on the upstream side in the traveling direction of the wire and the dehydrator on the downstream side in the traveling direction of the wire, the front and back of the fiber suspension interposed between the papermaking gaps. The degree of action of the dewatering force acting on the paper can be kept at an appropriate level, and it is possible to produce paper having a smaller difference between front and back.
[0044]
ContractRequest4According to the described twin-wire former of the invention,On the upstream side in the wire running directionBy arranging the dewatering device toward the entrance of the papermaking gap, the production cost can be secured while maintaining the same high dewatering power as a twin wire former equipped with a suction roll.ToIn addition to the fact that the inlet section has a high water content of the fibrous suspension, the required suction force is relatively small, so the frictional force between the dewatering surface and the wire is reduced by the small suction force. And the power required to drive the wire can be reduced..
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of a main part of a twin-wire former as a first embodiment of the present invention.
FIGS. 2A and 2B are diagrams showing a configuration of a dehydrating hole of the dehydrating apparatus according to the first embodiment of the present invention, wherein FIG. 2A is a partial cross-sectional view showing a drilling angle of the dewatering hole, and FIG. FIG.
FIG. 3 is a schematic diagram illustrating an example of an entire configuration of a twin-wire former as a first embodiment of the present invention.
FIG. 4 is a schematic diagram for explaining the operation and effect of the dehydrating apparatus according to the first embodiment of the present invention.
FIG. 5 is a schematic diagram illustrating a main configuration of a twin-wire former according to a second embodiment of the present invention.
FIG. 6 is a schematic diagram showing a configuration of a main part of a twin-wire former as a third embodiment of the present invention.
FIG. 7 is a schematic diagram showing a configuration of a main part of a conventional twin-wire former having a suction roll in an initial dewatering unit.
[Explanation of symbols]
1 Headbox
2 Paper raw material liquid (fibrous suspension)
3,4 wire
5,5A-5D dehydrator
6 Papermaking gap
9 First dewatering equipment
10 Second dehydration equipment
11 Third dehydration equipment
12 Suction coach rolls
13 Transfer box
14 Suction roll
50A-50D Dehydration surface
51A-51D Dehydration hole

Claims (4)

A twin-wire forma forming a fibrous strip sandwich the fibrous suspension to papermaking gap formed between the traveling two wires,
A dewatering surface that is in sliding contact with either one of the two wires and that is curved toward the running direction of the wires;
Dewatering devices having a plurality of dewatering holes formed in the dewatering surface are alternately arranged on both sides of the two wires ,
The dehydration hole,
At the entrance of the dewatering hole, a hole is formed so as to be inclined toward the running direction of the wire with respect to the normal line of the dewatering surface, and the running direction of the wire does not coincide with the arrangement direction of the dewatering holes. It is arranged and pierced at regular intervals on the dewatering surface ,
A twin wire former , wherein the curvature of the dewatering surface of the dewatering device on the downstream side in the running direction of the wire is set larger than the curvature of the dewatering surface of the dewatering device on the upstream side in the running direction of the wire. . At least one of the wire contact length of the dewatering surface, the hole diameter of the dewatering hole, the inclination angle, and the opening ratio differs between the dehydrator on the upstream side in the running direction of the wire and the dewatering device on the downstream side in the running direction of the wire. Set to a value
The twin-wire former according to claim 1, wherein: The dewatering hole is communicated with a vacuum source, and a suction force from the vacuum source is applied to the dewatering hole. Set different value with the dehydrator on the side
The twin wire former according to claim 1, wherein: The dewatering device on the upstream side in the traveling direction of the wire was disposed toward the entrance of the papermaking gap.
The twin wire former according to any one of claims 1 to 3, wherein:

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