JP2002115194A - Twin wire former - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twin wire former which facilitates the adjustment of a raw material-landing point and controls the generation of paper defects caused by the landing of the raw material. SOLUTION: This twin wire former which comprises two wires 3, 4 for forming a space for making paper and a lead-in blade 21 disposed on the upstream end of the space for making the paper and brought into sliding contact with the wire 4 and is used for jetting a paper raw material liquid 2 in the mutual conversing portion of the wires 3, 4 in the neighborhood of the lead-in blade 21 to nip the paper raw material liquid 2 in the space, carrying the nipped paper raw material and simultaneously dehydrating the paper raw material, characterized by forming the upstream side portion of the wire-sliding surface 21b of the lead-in blade 21 in such an inclined curved shape as gradually expanding the space toward the upstream end, setting the landing point 11 of the jet-like paper raw material liquid 2 on the wire 4 to the wire-sliding surface 21b, and forming openings 21a for flowing out the water dehydrated from the side of the wire 4 on the wire-sliding surface 21b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-wire former for dewatering a paper raw material liquid while sandwiching and transferring a paper raw material liquid in a papermaking gap formed between two wires.

[0002]

2. Description of the Related Art As a paper layer forming apparatus of a paper machine, there is a twin wire former. This twin-wire former includes two mesh-shaped wires each formed in a loop shape, and while the paper raw material liquid runs while being sandwiched between the two wires, the paper is dewatered by various dewatering devices. As the water is removed from the raw material liquid, a fiber mat is gradually formed, which grows to form a paper web.

For example, FIG. 4 is a schematic configuration diagram showing an example of this twin-wire former, and the twin-wire former will be described with reference to this drawing. As shown in FIG. 4, the paper raw material liquid 2 from the inside of the head box 1 is supplied to the mesh wire of FIG. 5 by two mesh-shaped wires of a first wire (# 1 wire) 3 and a second wire (# 2 wire) 4. The jet is jetted toward a gap (papermaking gap) 15 formed as shown.

[0004] The first wire 3 is guided by a forming roll 16 and a guide roll 18 and the like.
The wire 4 is a breast roll 17 and a guide roll 19A
19C and the like, and a papermaking gap 15 is formed between the wires 3 and 4. The paper raw material liquid 2 forms a paper layer while traveling in the gap 15.

That is, the upper and lower wires 3 and 4 rotate so as to transfer the paper material liquid 2 in the gap 15 in a required direction (upward in FIG. 4). ,
4 moves in the gap 15 at almost the same speed. The gap 15
Are gradually narrowed toward the downstream in the traveling direction, and each loop of the wires 3 and 4 at the upstream part of the gap 15 is arranged in a curvature R shape. A first dehydrator 5, a second dehydrator 6, and a third dehydrator 7 are sequentially provided at an upstream portion of the gap 15, and a suction coach roll 8 and the like are provided at a downstream side thereof. Have been.

[0006] The first dewatering device 5 is provided with a curvature R of the second wire 4.
Is provided in the loop of As shown in FIG. 5, a plurality of dehydration blades 20a to 2
0e (when each blade is not distinguished, it is indicated by reference numeral 20)
Are provided at an interval from each other, and the bottom wire 4
Is in sliding contact with the top surface of each dewatering plate 20 to provide a curvature R
, And the top wire 3 also travels in a loop shape having a substantially curvature R across the paper raw material liquid 2.

The paper raw material liquid 2 is generated by bending along the curvature of the top wire 3 and the bottom wire 4 on each dewatering blade 20 while traveling along the curved gap approximate to the curvature R. Dehydration is performed on both sides (upper and lower wires 3 and 4) by the dehydration pressure (see the arrow marked with white water), and the fiber mat gradually grows in the gap 15. Each of the dewatering blades 20a to 20e is fixed to the base of the first dewatering device 5 through a key groove on the back surface, but can be inserted and removed in the width direction of the wire. It can be replaced every 20a-20e.

The second dehydrating device 6 is provided in a loop of the curvature R of the first wire 3 and includes a plurality of dehydration suppressing blades (not shown in detail). Dehydration to the side is suppressed, dehydration is performed only to the second wire 4 side, and paper webs are gradually formed. The third dehydrator 7 is also called a suction box, and is provided in a loop of the second wire 3. In the third dewatering device 7 and the suction couching roll 8, dewatering is performed by vacuum, and further, the formed web is transferred onto the second wire 4 via a transfer box (not shown), and is not shown. It is transferred to the next press part by the suction pickup roll.

[0009]

By the way, the jet-shaped paper raw material liquid (hereinafter, also referred to as a raw material jet) 2 jetted from the head box 1 forms a gap 15 between the wires 3 and 4.
In detail, as shown in FIG. 6, the first and second wires 3 and 4 near the upstream end of the first dewatering device 5 land near a portion where the wires 3 and 4 converge.

That is, the two wires 3 and 4 are arranged such that the gap 15 between them is at a predetermined distance at the upstream end of the dewatering blade (hereinafter referred to as a lead-in blade) 20a on the most upstream side of the first dewatering device 5. The raw material jet 2 is jetted toward a portion where the two wires 3 and 4 converge with each other. As a result, the raw material jet 2 is, for example, a first wire 3
, And the second wire 4 lands at the landing point 11.

As shown in FIG. 6, the landing point 11 on the second wire 4 is provided upstream of the lead-in blade 20a. This is because the lead-in blade 20a has a solid (no hole) structure. Therefore, if the raw material jet 2 lands on the surface of the lead-in blade 20a, an air layer accompanying the surface of the raw material jet 2 is formed. This is because the air layer could not be removed, and this air layer disturbed the raw material jet 2 and hindered the formation of a paper layer, so that papermaking could not be performed.

Therefore, the landing point 11 on the second wire 4 is necessarily provided upstream of the lead-in blade 20a. When the raw material jet 2 is landed on the wire, if the angle β ₀ formed between the raw material jet 2 and the wire (here, the second wire 4) is increased, the landing reaction force of the raw material jet 2 is increased and the wire is bent. As a result, the flow on the surface of the material jet 2 opposite to the material jet 2, that is, the surface of the material jet on the wire 3 is disturbed, thereby preventing the formation of a paper layer. Therefore, the angle β ₀ between the material jet 2 and the wire is increased. I can't take it.

Therefore, it is necessary to reduce the convergence angle of the wires 3 and 4 to reduce the angle β ₀ between the raw material jet 2 and the wire. When the angle β ₀ is small, the direction of the raw material jet 2 is slightly changed, and the second wire 4
The position of the landing point 11 on the upper side will change greatly, and it will be very difficult to adjust the position of the landing point (particularly, 11 on the second wire 4) (that is, the landing adjustment).

[0014] Then, if the raw material jet 2 landing point 1
When 1 is on the surface of the lead-in blade 20a, the air layer accompanying the surface of the raw material jet 2 disturbs the raw material jet 2 and hinders the formation of the paper layer as described above.
For example, paper defects such as spotting (a phenomenon in which no fiber is formed on the surface of the paper due to the entrainment of air) are likely to occur.

In particular, the landing points 10, 11 of the raw material jet 2
Varies depending on the papermaking speed (speed of the wires 3 and 4), the thickness of the paper raw material liquid 2 (gap 15), the dehydration characteristics of the paper raw material liquid 2, and the like, and the landing adjustment is performed every time any of these changes. Therefore, the work load required for landing adjustment is extremely large, and there is a possibility that the landing point cannot be properly adjusted even if the work is performed carefully.

If the angle β ₀ formed between the raw material jet 2 and the second wire 4 is reduced, a fluid wedge effect occurs between the raw material jet 2 and the second wire 4. A static pressure builds up in the space between the raw material jet 2 and the second wire 4, causing turbulence of the surface of the raw material jet 2 (the interface between the raw material jet 2 and the air), thereby causing the above-described spotting and other paper defects. It is easy to occur.

Also, when the landing point 11 on the second wire 4 is provided upstream of the lead-in blade 20a, the landing point 10 on the first wire 3 is located at the upper end of the lead-in blade 20a where both wires converge. Therefore, the landing point 10 on the first wire 3 and the landing point 11 on the second wire 4 are displaced by the difference α in the flow direction of the raw material jet 2, and the second wire 4 from the landing point 11 on the first wire 3 to the landing point 10 (portion of the difference α ₀ ) cannot be simultaneously dehydrated. If simultaneous dehydration is not possible, the homogeneity of the surface of the paper layer cannot be ensured on both sides of the paper, making it difficult to ensure the required paper quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and makes it possible to easily adjust the landing of a raw material jet and to suppress the occurrence of paper defects caused by the landing of the raw material jet. It is an object of the present invention to provide a twin-wire former.

[0019]

Therefore, a twin wire former according to the present invention comprises two wires converging with each other to form a papermaking gap, and the two wires provided at the upstream end of the papermaking gap. And a lead-in blade to which one of the wires slides. The paper raw material liquid is jetted into the converging portion of the two wires near the lead-in blade in a jet shape, and the two wires are used to form a gap in the papermaking gap. A twin-wire former for dewatering while sandwiching and transporting the paper raw material liquid, wherein an upstream portion of the wire sliding surface of the lead-in blade in a moving direction of the paper raw material liquid gradually becomes closer to an upstream end. The jetting paper raw material liquid is configured to have a curved surface that is inclined so as to enlarge the gap, and the landing point of the jet-shaped paper raw material liquid on the one wire is set on the wire sliding contact surface, and the wire sliding contact surface is formed. At least 該着 point and the moving direction downstream side of the paper raw material liquid than 該着 point is characterized in that water outlet opening for discharging the water that has been dewatered from one wire side the is formed.

Further, it is preferable that a plurality of grooves are provided on the wire sliding contact surface along the moving direction of the paper raw material liquid so that the grooves function as the water outflow openings. . It is preferable that each of the above-mentioned grooves is formed from the middle of the upstream end side of the wire sliding contact surface to the downstream end, except for the upstream end portion of the wire sliding contact surface.

Further, it is preferable that the depth of each of the above grooves is gradually increased in the moving direction of the paper raw material liquid.
Preferably, each of the grooves is inclined with respect to the moving direction of the paper raw material liquid.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described. FIG. 1 shows a twin-wire former according to a first embodiment of the present invention, in which (a) is a schematic view of a main part showing a landing point of the jet-shaped paper raw material liquid. Side view, (b)
FIG. 3 is a schematic side view of the lead-in blade, and FIG. 3C is a schematic front view of the lead-in blade.

The twin wire former of the present embodiment is characterized by its lead-in blade and the periphery of the lead-in blade, and the other parts are configured in the same manner as the conventional example. That is, the overall configuration of the twin wire former is shown in FIG.
As shown in FIG. 5, a gap (papermaking gap) formed as shown in FIG. 5 by two mesh-shaped wires of a first wire (# 1 wire) 3 and a second wire (# 2 wire) 4
15, the paper raw material liquid 2 from inside the head box 1 is jetted in a jet shape.
Forms a paper layer while traveling in the gap 15.

The first wire 3 is guided by a forming roll 16 and a guide roll 18 and the like.
The wire 4 is a breast roll 17 and a guide roll 19A
19C and the like, each of which rotates so as to transfer the paper raw material liquid 2 in the gap 15 in a required direction, and the paper raw material liquid 2 moves in the gap 15 at substantially the same speed as the wires 3 and 4. The gap 15 is gradually narrowed toward the downstream in the traveling direction. A first dehydrator 5, a second dehydrator 6, and a third dehydrator 7 are sequentially provided upstream of the gap 15, and a suction coach roll 8 and the like are provided downstream thereof.

The first dehydrating device 5 has a curvature R of the second wire 4.
, A plurality of dewatering blades (see FIG. 5) are provided at intervals from each other, and the bottom wire 4 slides on the top surface (sliding contact surface) of these dewatering blades, so that the curvature R is reduced. The top wire 3 travels in a loop shape with the curvature R approximately. The paper raw material liquid 2 is driven by the dewatering pressure generated by the bending along the curvature of the top wire 3 and the bottom wire 4 on each dewatering blade 20 while traveling along the curved gap approximate to the curvature R. Then, dehydration is performed on both wires 3 and 4 side, and the fiber mat gradually grows in the gap 15.

The second dehydrating device 6 is provided in a loop of the curvature R of the first wire 3 and includes a plurality of dehydration suppressing blades. And dehydration is performed only on the second wire 4 side. The third dehydrator 7 is also called a suction box, and is provided in a loop of the second wire 3. The third dehydrator 7 and the suction coach roll 8 perform dehydration by vacuum. (Not shown), a paper web is formed.

The two wires 3 and 4 are arranged such that a gap 15 therebetween is a predetermined distance near the upstream end of the most upstream dehydrating blade of the first dehydrating device 5 (this is referred to as a lead-in blade). The raw material jet 2 is converged so that the raw material jet 2 lands on a portion where the two wires 3 and 4 converge. Here, the lead-in blade with which the second wire (# 2 wire) 4 slides in the present twin-wire former will be described with reference to FIG. 1. As shown, the wire sliding contact surface 21b, which is the top surface, is formed in a curved shape that is gently convex toward the wire 4 side. In other words, if attention is paid to the upstream portion in the moving direction of the raw material jet 2 on the wire sliding contact surface 21b, the papermaking gap is gradually enlarged toward the upstream end (in other words, gradually from the wire 4 toward the upstream end. If attention is paid to the downstream side of the wire sliding contact surface 21b in the moving direction of the raw material jet 2, the curved surface is inclined so as to be gradually separated from the wire 4 toward the downstream end. Is configured. As a matter of course, the curvature of this curved surface is smaller than the curvature R of the second wire 4 in the first dewatering device 5.

The point where the raw material jet 2 comes into contact with the wire 4 is set at a portion where the wire 4 slides on the wire sliding contact surface 21b. As described above, since the wire sliding contact surface 21b of the lead-in blade 21 is configured to have a curved surface inclined so as to gradually increase the papermaking gap toward the upstream end, the wire sliding contact surface 21b is provided on the upstream side of the lead-in blade 21. The distance between the two wires 3 and 4 can be increased. Therefore, the material jet 2 is placed at a position where the wire 4 slides on the wire sliding surface 21b of the lead-in blade 21.
Can be controlled without difficulty.

Further, when the landing point of the raw material jet 2 (the # 2 wire side raw material landing point) 11 is set to a portion of the wire 4 whose back surface is supported by the lead-in blade 21, the wire is distorted by the landing of the raw material jet 2. Therefore, the raw material jet 2 and the wire 4 near the landing point 11
Is relatively large, and from this point also, the position adjustment of the landing point 11 of the raw material jet 2 becomes easy.

The wire sliding contact surface 21b has
As shown in (c), a plurality of grooves 21a are arranged in parallel along the moving direction of the raw material jet 2. These grooves 2
1a is formed from the middle of the upstream end side of the wire sliding contact surface 21b to the downstream end except for the upstream end portion of the wire sliding contact surface 21b, and is included in the paper raw material liquid 2 dehydrated from the wire 4 side. It functions as a water outflow opening through which water (white water) flows out as shown by an arrow in FIG.

Although the groove 21a is not formed at the upstream end portion of the wire sliding contact surface 21b, the wire sliding contact surface 21b surely guides the running of the wire 4 and causes the wire 4 to bend. This is intended to suppress the occurrence of paper defects due to the bending of the wire 4 in such a manner. The groove depth of each groove 21a is gradually increased in the moving direction of the paper raw material liquid 2, and the groove 21a is formed in a so-called foil shape. That is, each groove 21a is formed so as to gradually increase in depth from the base point on the upstream side to the downstream side. However, in this embodiment, the wire sliding contact surface 21
The wire 4 is separated from the wire 4 at the downstream end of the groove b, and the bottom of each groove 21a is gradually separated from the wire 4 in this portion even if the groove depth does not gradually increase in the moving direction of the paper raw material liquid 2. Is enough.

The reason for gradually increasing the depth of each groove 21a from the upstream side to the downstream side is that a space is formed outside the wire 4 by the groove 21a. Then, a negative pressure is generated in the groove 21a. This negative pressure is suitable for causing the water in the paper raw material liquid 2 to flow out. However, if the negative pressure is applied suddenly, the surface (interface with air) of the paper raw material liquid 2 is disturbed and the paper defects are generated. Invite. Therefore, the groove depth is gradually increased from the upstream side to the downstream side.

Each groove 21a functions as a flow path for water dewatered from the paper material liquid 2, but the flow cross-sectional area of each groove 21a gradually increases in the moving direction of the paper material liquid. The flow cross-sectional area of each groove can be made to correspond to the amount of the outflow moisture that increases as going downstream. In particular, when the inside of the groove 21a dries, dirt easily adheres to the inside of the groove 21a, but this can be prevented if the inside of each groove 21a is always filled with outflow moisture. The setting of the groove depth as described above also takes this point into consideration.

In order to prevent a sudden change in negative pressure, the groove 2
The angle ξ between the bottom surface of the groove 21a and the wire sliding contact surface 21b at the base point of 1a (upstream end) must be set to a small value, and the angle ξ is preferably 10 ° or less, more preferably 5 °. The following is assumed. As described above, the angle ξ should be small if only the sudden change in the negative pressure is considered, but the angle ξ should be set in consideration of these factors because it is necessary to secure the flow cross-sectional area.

Further, in the present embodiment, as shown in FIG. 1C, the direction of each groove 21a is inclined in the width direction by a required inclination θ with respect to the moving direction of the paper raw material liquid 2. This is to enable the water outflow of the paper raw material liquid 2 to be performed uniformly in the width direction. Here, while the wire 4 is running while contacting the wire sliding contact surface 21b,
It is set so that the water can flow out at any point of each groove 21a over the entire width of the paper raw material liquid 2 in the wire 4.

Specifically, in this embodiment, each groove 2
1a the width W ₁ of the width W ₂ between the grooves 21a is set to be approximately equal in size (for example, about 3-4 mm), the inclination θ is in the groove between the width W ₂ and the wire 4 wire sliding contact surface 21b The relationship of the upward sliding contact length L ₁ ′ is set as in the following equation (1). tan θ ≧ W ₂ / L ₁ ′ (1) If the inclination θ is large, the friction between one edge of each groove 21a and the wire 4 that slides on the edge increases, and the inclination from this surface is increased. It is better that θ is small, and in order to allow the paper material liquid 2 to contact the groove 21a at any position in the longitudinal direction of the groove 21a over its entire width while making the inclination θ smaller, tan θ = W ₂ / L ₁ ′ may be used.

In the present embodiment, the wire 4 is connected to the wire sliding contact surface 2 at the downstream end of the lead-in blade 21.
1b, the wire 4 may contact the wire sliding contact surface 21b from the landing point 11 to the downstream end of the lead-in blade 21. In this case,
The sliding length of the wire 4 on the wire sliding contact surface 21b is shown in FIG.
As shown in (c), L ₁ is obtained, and the inclination θ may be set to the relationship shown in the following equation (1).

Tanθ ≧ W ₂ / L ₁ (2) A key groove for fixing to the base of the first dehydrating device 5 is formed on the back surface of the lead-in blade 21 in the same manner as in the related art. 21 c is formed, and can be attached to and detached from the base of the first dewatering device 5 by inserting and removing in the width direction.
Of course, the wire 4 is securely fixed in the running direction at the time of mounting.

The twin-wire former according to the first embodiment of the present invention is configured as described above, and functions as follows. That is, since the upstream portion of the wire sliding contact surface 21b in the moving direction of the raw material jet 2 is formed into a curved surface inclined so as to gradually increase the papermaking gap toward the upstream end, the lead-in blade 21 On the upstream side, the distance between the two wires 3 and 4 can be increased, and the landing point 11 of the raw material jet 2 is set at a position where the wire 4 slides on the wire sliding surface 21 b of the lead-in blade 21. Becomes easier.

When the landing point (# 2 wire side raw material landing point) 11 of the raw material jet 2 is set on the lead-in blade 21, the landing point 11 and the landing point of the raw material jet 2 to the wire 3 (# 1 wire side) The difference α in the flow direction of the raw material jet 2 from the raw material jet 2 can be easily reduced, and the raw material jet 2 can be simultaneously dewatered from the landing position. And the required paper quality can be ensured.

When the landing point 11 of the raw material jet 2 is set to a portion of the wire 4 where the back surface is supported by the lead-in blade 21, the wire is unlikely to be bent by the landing of the raw material jet 2. The angle β between the raw material jet 2 and the wire 4 can be made relatively large, and the position adjustment of the landing point 11 of the raw material jet 2 becomes easy.

In particular, the landing points 10, 11 of the raw material jet 2
Varies depending on the papermaking speed (the speed of the wires 3 and 4), the thickness of the paper raw material liquid 2 (gap 15), the dehydration characteristics of the paper raw material liquid 2, and the like. However, since the position adjustment (landing adjustment) of the landing point 11 is easy, If any one of these changes, it is possible to easily cope with the change, the work load required for the landing adjustment is reduced, the work time required for the adjustment is shortened, and the landing point can be appropriately adjusted. .

Further, if the angle β between the material jet 2 and the wire 4 is relatively large, the material jet 2 and the second
The fluid wedge effect is less likely to be generated between the material jet 2 and the wire 4, and the static pressure generated in the space between the material jet 2 and the second wire 4 is also weakened due to the fluid wedge effect. 2) and turbulence of the air
Paper defects such as spotting are less likely to occur.

When the landing point 11 of the raw material jet 2 is on the wire sliding contact surface 21b of the lead-in blade 21,
The air layer entrained on the surface of the raw material jet 2 disturbs the raw material jet 2 between the raw material jet 2 and the wire sliding contact surface 21b, thereby preventing the paper layer from being formed. Since the plurality of grooves 21a are arranged side by side in the moving direction, the air layer entrained on the surface of the raw material jet 2 flows out from the wire 4 side together with the moisture in the paper raw material liquid 2 dehydrated through the grooves 21a. As a result, the raw material jet 2 forms a paper layer appropriately without being disturbed.

In particular, if the groove 21a is formed on the wire sliding contact surface 21b, the wire 4 loses its support at the groove 21a and the wire 4 is easily bent, but in this embodiment,
Since the groove 21a is not formed at the upstream end portion of the wire sliding contact surface 21b, the wire 4 is securely supported by the upstream end portion of the wire sliding contact surface 21b so that the wire 4 is not bent. That is, it is possible to suppress the occurrence of paper defects due to the bending of the wire 4.

The groove depth of each groove 21a is set to
And the angle す between the bottom surface of the groove 21a and the wire sliding surface 21b at the base point (upstream end) of the groove 21a is set to be small. Therefore, when the wire 4 and the paper raw material liquid 2 move, an appropriate negative pressure is generated in the groove 21a, and a rapid pressure fluctuation on the surface (interface with air) of the paper raw material liquid 2 is suppressed. In addition, turbulence occurs on the surface of the paper raw material liquid 2 so that the content can be changed, and generation of paper defects can be suppressed.

Further, the flow cross-sectional area of each groove 21a gradually increases in the moving direction of the paper raw material liquid. The cross-sectional area can be made to correspond, and it becomes easy to always fill the inside of each groove 21a with the outflow moisture. When the inside of the groove 21a dries, dirt easily adheres to the inside of the groove 21a. However, this can be prevented by always filling the inside of each groove 21a with outflow moisture.

Further, in the present embodiment, since the direction of each groove 21a is inclined in the width direction by a required inclination θ with respect to the moving direction of the paper material liquid 2, the water outflow of the paper material liquid 2 is reduced in the width direction. Can be performed uniformly. In particular, the inclination θ
Is set in accordance with the above formula (1) with respect to the groove width W ₂ and the sliding length L ₁ ′ of the wire 4 on the wire sliding surface 21b, whereby the paper raw material liquid in the wire 4 is set. 2, water can be discharged at any point of each groove 21a over the entire width of the groove 2, and the water can be discharged more uniformly in the width direction to improve the paper quality.

The present applicant has already applied for an invention relating to a dewatering shoe (dewatering blade) having a shape similar to the lead-in blade 21 of the present embodiment (Japanese Patent Application No. 3-2).
No. 50257). Like the lead-in blade 21 of the present embodiment, a plurality of grooves inclined with respect to the traveling direction of the paper raw material liquid are provided on the surface of the dehydration shoe in parallel, but these grooves are formed in the machine width direction. A material pressure profile difference is generated between adjacent parts, and the pressure in the machine width direction is applied to the fibers in the material by the pressure in the machine width direction to reduce the degree of orientation of the fibers in the machine direction. The purpose and function are completely different from those of the lead-in blade 21 of the present embodiment.

In the first embodiment, the direction of each groove 21a is inclined in the width direction by a required inclination θ with respect to the moving direction of the paper raw material liquid 2. Further, since the drying is also performed by the dewatering blade on the downstream side (see reference numerals 20b to 20e in FIG. 5), it is not always necessary to uniformly dehydrate the paper raw material liquid 2 in the width direction by the lead-in blade 21. Depending on the required paper quality, the dewatering conditions in the lead-in blade 21 may not be uniform in the width direction of the paper raw material liquid 2 in some cases. The following second embodiment is applicable to such a case.

Here, the second embodiment will be described. FIG. 2 shows a twin-wire former according to a second embodiment of the present invention. FIG. 2 (a) is a schematic side view of the lead-in blade. (b) is a schematic front view of the lead-in blade. As shown in FIG. 2, similarly to the lead-in blade 21 of the first embodiment, the lead-in blade 22 of the present embodiment is formed on the wire sliding contact surface 22b formed on the top surface side and the wire sliding contact surface 22b. A plurality of grooves 22a and a key groove 22c formed on the back surface side. The plurality of grooves 22a are parallel to the moving direction of the paper raw material liquid 2 and have a tilt θ as in the first embodiment. Do not have.

In the twin wire former according to the second embodiment of the present invention, the dewatering conditions in the lead-in blade 22 are not uniform in the width direction of the paper raw material liquid 2 due to such a configuration. The same operation and effect as in the first embodiment can be obtained while making the lead-in blade 22 simpler and easier to process than in the first embodiment.

In the first and second embodiments, the grooves 21a and 22a are not formed in the upstream end portions of the lead-in blades 21 and 22, but the wire 4 is not formed in the grooves 21a and 2a.
If bending does not easily occur at the portion 2a, or if there is no problem even if the wire 4 bends at the grooves 21a and 22a, a groove may be provided from the upstream end to the downstream end of the lead-in blade. . In this case, even if the groove depth is set to a certain value from the base end of the groove (upstream end of the lead-in blade), the sudden change of the negative pressure is small, and a configuration as in the following third embodiment can be considered.

Here, the third embodiment will be described. FIG. 3 shows a twin-wire former according to a third embodiment of the present invention. FIG. FIG. 5B is a schematic side view of the lead-in blade, and FIG. 5C is a schematic front view of the lead-in blade. As shown in FIG. 3, similarly to the lead-in blade 21 of the first embodiment, the lead-in blade 23 of the present embodiment is also formed on the wire sliding contact surface 23b formed on the top surface side and the wire sliding contact surface 23b. Groove 23a, key groove 2 formed on the back side
3c, the plurality of grooves 23a are provided over the entire length from the upstream end to the downstream end of the lead-in blade,
Moreover, the depth is substantially uniform over the entire length. Here, the plurality of grooves 23a are parallel to the moving direction of the paper raw material liquid 2 and do not have the inclination θ as in the first embodiment, but have the inclination θ as in the first embodiment. θ
May be set.

The twin wire former according to the third embodiment of the present invention is configured as described above.
Almost the same effects as in the second embodiment can be obtained. That is, since the upstream portion of the wire sliding contact surface 23b in the moving direction of the raw material jet 2 is formed into a curved surface inclined so as to gradually increase the papermaking gap toward the upstream end, the lead-in blade 23 On the upstream side, the distance between the two wires 3 and 4 can be increased, and by setting the landing point 11 of the raw material jet 2 on the lead-in blade 23, the landing point 11 and the wire 3 of the raw material jet 2 can be increased. , The difference α in the flow direction of the raw material jet 2 from the landing point 10 can be easily reduced, the raw material jet 2 can be simultaneously dewatered from the landing point, and the homogeneity of the paper layer surface on both sides of the paper And the required paper quality can be ensured.

Further, by setting the landing point 11 of the raw material jet 2 at a portion supported by the lead-in blade 21 in which the wire 4 is unlikely to be distorted, the angle formed between the raw material jet 2 and the wire 4 near the landing point 11 β can be set relatively large, and the position of the landing point 11 of the raw material jet 2 can be easily adjusted. By making the angle β between the raw material jet 2 and the wire 4 relatively large, a fluid wedge effect is less likely to be generated between the raw material jet 2 and the second wire 4, and due to this fluid wedge effect, The static pressure generated in the space between the raw material jet 2 and the second wire 4 is also weakened, and the turbulence of the surface of the raw material jet 2 is suppressed, so that paper defects such as spotting are less likely to occur.

Further, since a plurality of grooves 23a are arranged in the wire sliding contact surface 23b along the moving direction of the raw material jet 2, the air layer accompanying the surface of the raw material jet 2 is The water flows out together with the water in the paper raw material liquid 2 that has been dehydrated from the side through the groove 23a, and the raw material jet 2 can appropriately form the paper layer without being disturbed.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and can be variously modified and implemented without departing from the gist of the present invention. For example, each lead-in blade 21, 22,
The wire sliding contact surfaces 21b, 22b, 23b of 23 are formed in a curved shape in a side view, but this curvature may be uniform from the upstream end to the downstream end, and at the upstream end side where the landing point 11 is set. The curvature is reduced to make it easier to increase the distance between the two wires, and the curvature is increased at the downstream end (the downstream end may be flat), so that the wire 4 is brought into contact with the wire sliding surfaces 21b, 21b.
The sliding contact may be made to the vicinity of the downstream end of 22b and 23b.

Each of the lead-in blades 21, 22, 22
The shape of the wire sliding contact surface of the dehydrating plate (see reference numerals 20b to 20e in FIG.
Wire sliding contact surfaces 21b, 22b, 23b of 1, 22, 23
By forming a curved surface in a side view in the same manner as described above, and / or providing grooves such as the grooves 21a, 22a, and 23a on the respective sliding surfaces of the wires, the dewatering property is improved, and in particular, an upstream portion having a large amount of water. Since the effect of the groove is higher in the dewatering plate on the side (dewatering plate closer to the lead-in blade), such a configuration is preferably applied.

[0060]

As described in detail above, according to the twin wire former of the present invention, the upstream side of the wire sliding surface of the lead-in blade in the moving direction of the paper raw material liquid gradually becomes closer to the upstream end. The distance between the two wires can be increased on the upstream side of the lead-in blade because one of the wires slides on the wire sliding contact surface. It becomes easy to land the jet-shaped paper raw material liquid at the contacting point. And, by setting the landing point of the jet-shaped paper raw material liquid to one wire on the wire sliding contact surface, even if the angle between the jet-shaped paper raw material liquid and the wire is relatively large, The paper layer can be formed without any trouble, and the occurrence of the fluid wedge effect between the jet-shaped paper raw material liquid and the wire can be suppressed, and the occurrence of paper defects such as spotting can be suppressed. Can be.

Further, at least at the landing point of the wire sliding contact surface and at the downstream side in the moving direction of the paper raw material liquid from the landing point, a water outflow opening through which dehydrated water flows out from one wire side is formed. Therefore, it is possible to remove an air layer accompanying the surface of the jet-form raw material liquid while allowing water to flow out through the water outflow opening, so that the formation of the paper layer by this air layer is prevented, and paper defects such as spotting are prevented. Occurrence is suppressed, and papermaking with desired paper quality can be performed reliably.

Further, a plurality of grooves are provided in parallel on the sliding surface of the wire along the moving direction of the paper raw material liquid, and the grooves function as the water outflow openings. In addition, it is possible to smoothly remove the entrained air layer on the surface of the jet-form raw material liquid, to prevent the formation of the paper layer, to more reliably suppress the occurrence of paper defects such as spotting, and to improve the paper quality. It is possible to further improve.

By forming each of the above-mentioned grooves from midway on the upstream end side to the downstream end of the wire sliding contact surface except for the upstream end portion of the wire sliding contact surface, the upstream end of the wire sliding contact surface is formed. In the portion where the groove of the portion is not formed, the above one wire is reliably guided to avoid bending of the wire and to suppress the occurrence of paper defects caused by the bending of the wire, while the above-mentioned water outflow and entrainment of the entrained air layer are suppressed. Removal can be performed smoothly.

Further, by gradually increasing the groove depth of each groove in the direction of movement of the paper raw material liquid, it is possible to suppress a sudden change in negative pressure caused by the groove and to suppress the occurrence of paper defects. Can be. In addition, the flow cross-sectional area of each groove gradually increases in the moving direction of the paper raw material liquid, so that the flow cross-sectional area of each groove can correspond to the amount of outflow moisture that increases toward the downstream side. Become like For this reason, it becomes easy to always fill the inside of each groove with the outflow moisture, and it is possible to prevent the adhesion of dirt into each groove, which is likely to occur when the inside of each groove dries, and to further improve the paper quality. become.

Further, by inclining each of the grooves with respect to the moving direction of the paper raw material liquid, the grooves cooperate with each other so that the water outflow of the paper raw material liquid can be performed more uniformly in the width direction. Paper quality can be further improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a twin-wire former as a first embodiment of the present invention, in which (a) is a schematic side view of the main part showing a landing point of the jet paper raw material liquid, b)
FIG. 3 is a schematic side view of the lead-in blade, and FIG. 3C is a schematic front view of the lead-in blade.

FIGS. 2A and 2B are diagrams showing a main part of a twin-wire former as a second embodiment of the present invention, wherein FIG. 2A is a schematic side view of the lead-in blade, and FIG. It is a schematic front view.

FIG. 3 is a diagram showing a main part of a twin-wire former according to a third embodiment of the present invention, wherein (a) is a schematic side view of the main part showing a landing point of the jet-shaped paper raw material liquid, b)
FIG. 3 is a schematic side view of the lead-in blade, and FIG. 3C is a schematic front view of the lead-in blade.

FIG. 4 is a schematic side view showing a configuration of a conventional twin wire former.

FIG. 5 is a schematic side view showing a first dewatering device in a conventional twin-wire former.

FIG. 6 is a schematic side view of a main part showing a landing point of a jet-shaped paper raw material liquid in a conventional twin-wire former.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head box 2 Paper raw material liquid (raw material jet) 3 1st wire (# 1 wire) 4 2nd wire (# 2 wire) 5 1st dehydration equipment 6 2nd dehydration equipment 7 3rd dehydration equipment 8 Suction couch roll 10 Wear Point (# 1 wire-side raw material landing point) 11 Landing point (# 2 wire-side raw material landing point) 15 Gap (gap for paper making) 16 Forming roll 17 Breast roll 18, 19A to 19C Guide roll 20a (Dewatering plate) 20b to 20e Dehydration blade 21, 22, 23 Lead-in blade 21a, 22a, 23a Groove 21b, 22b, 23b Wire sliding contact surface 21c, 22c, 23c Key groove

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanobu Matsumoto 5007 Itozakicho, Mihara City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Paper and Printing Machinery Division F-term (Reference) 4L055 CD08 CE50 FA09 FA11

Claims (5)

[Claims] 1. Convergence with each other to form a papermaking gap 2
And two wires arranged at the upstream end of the papermaking gap.
A lead-in blade on which one of the two wires slides, and jets a paper raw material jet into a converging portion of the two wires in the vicinity of the lead-in blade to form a paper-forming liquid by the two wires. A twin-wire former for dewatering while sandwiching and transporting the paper raw material liquid in a gap, wherein an upstream portion of the wire sliding surface of the lead-in blade in a moving direction of the paper raw material liquid gradually moves toward an upstream end. The jetting paper raw material liquid is configured to have a curved surface that is inclined so as to enlarge the papermaking gap, and a landing point of the jet-shaped paper raw material liquid on the one wire is set on the wire sliding contact surface, and the wire sliding contact surface is formed. At least at the landing point and at a downstream side of the paper feed liquid in the moving direction of the paper raw material liquid from the landing point, a water outflow opening for discharging dehydrated water from the one wire side is formed. To, twin wire former. 2. A plurality of grooves are provided on the wire sliding contact surface along the moving direction of the paper raw material liquid, and the grooves function as the water outflow openings. Item 2. The twin wire former according to Item 1. 3. The method according to claim 1, wherein each of the grooves is formed from a portion on the upstream end side of the wire sliding contact surface to a downstream end thereof, except for an upstream end portion of the wire sliding contact surface. Item 2. The twin wire former according to Item 2. 4. The twin-wire former according to claim 2, wherein a depth of each of the grooves is gradually increased in a moving direction of the paper raw material liquid. 5. The twin-wire former according to claim 2, wherein each of the grooves is inclined with respect to a moving direction of the paper raw material liquid.