JPH02269892A - Shoe blade of paper-making machine twin wire former - Google Patents

Abstract

PURPOSE:To rationalize the level of a dehydration pressure and improve the interlaminar strength and yield of prepared paper by disposing a flat portion for supporting a wire and a tilted portion for forming a wedge-shaped space together with the surface of the wire on the inlet side of the wire on a shoe blade. CONSTITUTION:A flat portion 40a for supporting a wire and a tilted portion 40b are disposed on a shoe blade 40 so that the tilted portion 40b may be placed on the upstream side of the running direction of the wire. White water once released on the wire side is pressed back on the side of the raw material in wedge-shaped space formed between the tilted portion 40b of the shoe blade 40 and the surface of the wire, thereby carrying out only one side dehydration on the side of the other wire.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a shoe blade for a twin wire former of a paper machine having a plurality of shoe blades for dewatering that sandwich a raw material between pairs of wires and contact the surface of one of the wires. Regarding improvements.

[Conventional technology]

FIG. 8 shows a shoe blade for a twin-wire former of paper machines that is currently widely used, and FIG. 9 shows an example of a conventional twin-wire former in which this shoe blade is arranged.

In the above apparatus, the raw material 1 ejected from the head box 5 is guided by the prestrol 7 and the homing roll 6, and is sandwiched between two curved wires 3.4, and the convex shape of one of the wires 4 It runs at the same speed as the wire 3.4 over a plurality of shave blades 2 arranged on a certain curvature R' so as to form a surface.

The raw material liquid 1 is coated on both sides by the energy of colliding with the wires 3 and 4, the squeezing effect caused by the wire tension when it is sandwiched between the converging wires 3 and 4, the pressure pulses generated when scraping with the shave blade 2, and dehydration pressure such as centrifugal force. At the same time, approximately the same amount of dehydration takes place. Furthermore, suction box 10
, vacuum dehydration is performed by a succinct couch roll 11, etc., and the wire is separated from the wire 4 by a pick-up roll 12 and transferred to a press part.

In addition, in the figure, 8 is a water deflector, and 9 is a vacuum deflector.

[Problem to be solved by the invention]

The shave blade shown in FIGS. 8 and 9 generates pressure pulses during dewatering, so that fibers are sequentially dispersed while dewatering. For this reason, the paper has good texture and is used in many wet paper forming units.

However, when dehydrating with this shave blade, it is almost equal to both sides at the same time! As a result, the yield tends to be low due to dehydration, and a part with few fiber bonds is formed in the center of the paper thickness where the mat is formed at the end, making it difficult for the press to reach that part. This has the disadvantage that the bonding strength in the paper thickness direction (hereinafter referred to as interlaminar strength) is low.

For this purpose, the shoe blade is attached so as to support the wire at its terminal end, with the main purpose of improving yield.
A method has been proposed (Japanese Patent Application Laid-Open No. 89399/1989) in which a wedge-shaped space is formed between the wire and the wire support, and the white water that has seeped out onto the wire surface is pushed back toward the raw material. It has been suggested that since dehydration occurs on one side, the interlaminar strength also improves. however,
The device disclosed in JP-A No. 61-89399 has the problem that since the wire and the wire support make point contact, the peak value of the dewatering pressure acting on the raw material becomes extremely high, which impairs the formation. there were. Further, when the speed per second, basis weight, and raw material concentration differ depending on the type of papermaking, it is necessary to adjust the dehydration pressure, but this apparatus has a problem in that the dehydration pressure cannot be adjusted to an appropriate level.

The present invention aims to solve the problems of the conventional twin wire former dewatering device described above.

[Means to solve the problem]

The present invention provides a shoe blade for a twin wire former of a paper machine that comes into contact with one wire of a pair of wires that run while sandwiching a raw material between them. It is provided with an inclined part that is provided on the side and forms a wedge-shaped space that expands toward the upstream side in the wire running direction with respect to the wire surface.

[Effect]

FIG. 5 shows a pressure cover turn of the shave blade according to the present invention. As shown in FIG.
When the flat part 30a supporting the wire and the inclined part 30b forming a wedge-shaped space expanding toward the upstream side in the wire running direction with respect to the wire surface are provided on the wire entry side of the same flat part 30a, the wire is first dehydrated. When the white water is pushed back toward the raw material side in the wedge space formed by the wire and the main sheath, a pressure pulse having a pressure peak value P is generated at the point where the inclined portion 3b and the flat portion 3a intersect. P□ is the pressure generated by the wire tension run (T) on the plane portion 30a. The pressure P becomes smaller, for example, when the length of the flat portion becomes longer and the length (S-L) of the space in which no wire is supported becomes shorter, because the amount of water entering the wedge space decreases. Moreover, since the pressure P is a value obtained by dividing the resultant force of the wire tensile force by the length (L) of the flat part, it becomes a function of the length of the flat part when the wire tensile strength is constant.

Therefore, in the case of the device disclosed in Japanese Patent Application Laid-Open No. 61-89399, which has no flat surface and has point contact between the wire and the blade, the pressure becomes very large and it is impossible to adjust the pressure.

On the other hand, in the present invention in which a flat portion is provided, the dewatering pressure by the pressure pulse can be adjusted to suit each papermaking condition by changing the length of the flat portion.

In the present invention, water discharged from the wire on the side where the shoe blade is provided enters the wedge-shaped space formed by the sloped portion of the shoe blade, and is conversely pushed back toward the raw material side by the pressure pulse. This action is repeated for each of a plurality of shoe blades, thereby suppressing dewatering to the shave blade side. On the other hand, on the opposite side, since there is no device to suppress dehydration, dehydration is freely carried out by the squeezing action of the wire tension and the pressure pulses generated at the sloped portion of the shoe blade. In this way, unilateral dehydration is achieved. Furthermore, the peak value P+ due to this pressure pulse is adjusted by the length of the flat portion, as described above, and an appropriate dewatering pressure can be set.

By carrying out one-sided dewatering using such appropriate dewatering pressure, the present invention can improve the yield and produce paper with high glabellar strength.

Furthermore, in the present invention, due to the flat portion, the pressing pressure caused by the wire tension is reduced, and wear of the shoe blade and the wire is reduced.

〔Example〕

Shave blades according to first to fourth embodiments of the present invention are shown in FIGS. 1 to 4, respectively.

The shoe blade 40 according to the first embodiment shown in FIG. 1 is provided on the wire entry side of the flat part 40a that supports the wire and the flat part 40a, and lowers in a straight line and moves upstream in the wire running direction with respect to the wire surface. It includes an inclined portion 40b that forms a wedge-shaped space that widens toward the side.

The shoe blades 41, 42 according to the second and third embodiments shown in FIGS.
a, 42a, and the radius of curvature is not linear but concave or convex with respect to the wire surface.

The plane portion 41a curves at R5 and descends in an arc shape.

Inclined portions 41b and 42 are provided on the wire entry side of 42a.
b.

The shave blades of the first to third embodiments are made of materials with excellent wear resistance such as ceramics and ultra-high molecular weight polyethylene, and have T-shaped grooves 40c and 4 in the lower part thereof.
1c and 42c are provided, respectively, so that each blade can be inserted and removed individually.

The shoe blade 43 according to the fourth embodiment shown in FIG.
b, and a separate removable groove portion 45 made of fiber reinforced plastic (FRP) or ultra-high molecular polyethylene is provided.

The shoe blades according to each of the above embodiments are shown in FIGS. 6 and 7.
As shown in the figures (in these drawings, for convenience, the first
A shoe blade 40 according to an embodiment is shown)
, a plurality of wires 3.4 are arranged side by side so as to be in contact with one wire 3 of the two wires 3.4 that sandwich the raw material ejected from the head box 5 of the wine former, and the wires 3 are curved convexly with a curvature R. It is arranged to run and forms a dewatering device. In this case, each shave blade is installed such that the inclined portion is on the upstream side in the direction of wire travel. In addition, in FIG. 6, the same parts as those of the conventional twin wire former shown in FIG. 9 are indicated by the same reference numerals. In addition, in order to improve the strength of the glabella, a suction box 10 is installed on the other wire 4 side so that single-sided dehydration can be continued after the shave blade. Saxirank-Tyrol 11.30, Transfer Box 5
0 etc. are arranged.

In each of the embodiments having the above configuration, as described in detail in the "Function" column, the slopes 40b, 41b, 42b, 43b of the shoe blades 40, 41, 42, 43 are connected to the surface of the wire 3. In the wedge-shaped space formed in , the white water that has been dehydrated from the raw material toward the wire 3 side is pushed back toward the raw material side by a pressure pulse generated in the same space, and is pushed back to the wire 4 side by the tensilan of the wire 4 and this pressure pulse. Unilateral dehydration is performed. The peak value of the pressure pulse at this time can be determined by preparing shave blades with different lengths of the flat parts and replacing them by inserting and removing them.

This can be adjusted by changing the length of 43a to change the length of the space in which the wire is not supported, so that an appropriate dewatering pressure can be obtained. Furthermore, as in the above embodiments, the shape of the pressure pulse can be changed as appropriate by changing the shape of the slope, that is, by making it straight or curved.

As mentioned above, the paper stock that has been dewatered on one side toward the wire 4 side by the shoe blade is further transferred to the suction box IO,
After being dehydrated on one side to the wire 4 side using a Succilanc-Tyrol 11.30 and a transfer box, it is sent to the following wire part by a pick-up roll 12.

In each of the above embodiments, as described above, the yield of paper stock can be improved by dewatering one side toward the wire 4 side with an appropriate dewatering pressure using the shoe blade,
Moreover, paper with high glabellar strength can be produced.

Furthermore, connect the wire to the flat part of the shoe blade.

By supporting the shaver blade 1, the pressure applied to the wire tension run is reduced, and wear of the shaver blade and wire 1 can be reduced.

(Effects of the Invention) According to the present invention, a shoe blade of a paper machine twin wire former is provided with a flat part for supporting the wire and an inclined part forming a wedge space with the wire surface on the wire entry side of the circular part. By doing so, the following effects can be achieved.

(1) The dewatering pressure level can be optimized, and the material can be properly dehydrated.

(2) By adjusting the length of the flat part that supports the wire, it is possible to adjust the dewatering pressure to suit the papermaking conditions.

(3) Pressing with a wire tensile lamp causes less wear on the blade and wire because the pressure is low.

(4) It is now possible to perform unilateral dehydration at the initial stage of dehydration, which was difficult, and it is possible to improve glabella strength and current collection, which have been problems in the past.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 are side views of shoe blades according to first to fourth embodiments of the present invention, and FIG. 5 is a pressure buttern of a shoe blade according to the present invention. FIG. 6 is a diagram showing the arrangement of twin wire bows installed with the sea blades according to the first to fourth embodiments, and FIG. 7 is a detailed diagram of the shoe blade section of FIG. 8 is an explanatory diagram of a conventional dewatering shave blade, and FIG. 9 is a layout diagram of a conventional L twin ear lumer. ? , 4... wire, 5 river headbox. 40.41, 42.43...Dehydration shoe blade 14
0a, 41a+42a, 43a ++ Plane section. 40b, 41b, 42b, 43b... Slope portion. 40c, 41c, 42c, 43c...grooves. :45...Groove. Agent: Patent Attorney Akigai Sakama (2 people)Figure 6Figure 7

Claims (1)

[Claims] In a shoe blade of a paper machine twin wire former that comes into contact with one wire of a pair of wires that run while sandwiching the raw material, the shoe blade is provided on a flat part that supports the wire and on the wire entry side of the flat part. 1. A shoe blade for a twin-wire former of a paper machine, characterized by comprising an inclined part forming a wedge-shaped space expanding toward the upstream side in a wire running direction with respect to a wire surface.