JPS5841993A - Web forming method and apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a web forming method and a web forming machine in a so-called twin-wire set of web forming machines using a wireless web forming band or wire.

The reason why we say "wire" and "one band" here is because in the case of a hood linear type machine, we call it a wire. For various types of synthesis (fibers)
Includes textiles and felt.

The use of twin-wire complete formers has become much more advanced in recent years, especially in the production of paper such as newsprint.
Considerable advances have been made in improving web formation and thus productivity.

However, despite these advances in formers, fundamental problems remained that could not be resolved.

The present invention relates to an improved web forming machine, and it has been found that improvements in web forming that could not have been expected heretofore have been achieved.

When testing a modified hood linear machine as described above, it was found that in order to improve web formation, stock dewatering was temporarily interrupted and at least a portion of the web thickness was It has been found that the inside of the web can be formed by dewatering in the opposite direction.

A problem clearly specific to web formers using two wires is the lack of so-called Z-strength (of the product). All twin wire formers have so far shown a strong tendency to double layer due to a weak center of the web, and a tendency to result in separation due to low Z-axis strength.

Looking at the prior art, some have almost achieved the desired dewatering process, but in most cases this is probably due to the use of dewatering methods other than forming rolls, such as foils, table rolls, or curved-on-you. There is a major problem related to the yield of fine components. This is a problem in that there is a loss of fine components and fibers passing through the wire. This problem seems to be caused by a strong force being applied in a short period of time. Some of these machines have 19
B. on January 20, 1976. J, J ustus
These include those of the type shown in Canadian Patent No. 981,952, granted to

Therefore, the web forming machine which is the subject of the present invention comprises first and second web forming bands for receiving a stock which forms a web by dehydration so as to be sandwiched therebetween; A device for feeding two bands onto one of the first bands, which is tapered so that the first and second bands are bent over the arc of the roll, in the loop of the second band. A first web forming roll (forming roll) passes through in a jammed state, and an arc on the first forming roll is arranged so that the web formation only progresses halfway on this roll (
The center angle) is between 3o0 and 6o0, dewatering occurs in two directions in this part to form the outer surface of the web, and there is a second nib forming roll adjacent to the first forming roll. , this roll is in the loop of the second band and the first and second bands pass over this second forming roll bent in the opposite direction to that in the previous case, so that here the web An apparatus for stock dewatering characterized in that the direction of water flow inside is reversed at least in a part of the thickness of the web, and the formation of the web is completed here. It is something.

That is, the machine performs a first dewatering process on the first web forming roll to ensure that the outer surface of the web is formed but the formation is incomplete inside the web, and then The next stage of dewatering takes place in a second web forming roll in which the direction of water flow is opposite to the previous one over at least a significant part of the thickness of the web, and here the web interior is formed so that the web It is constructed and used in such a way that the formation is largely completed.

A web made on a machine operated in accordance with the teachings of the present invention will have significantly better retention of fines in the first bath than a corresponding food linear type machine. Furthermore, the machine according to the invention has a particularly good stability of sheet formation against changes in the consistency (density) of the stock. In other words, consistency at the entrance to the first webforming role is not important. However, it must not be so thick that the web formation is completed by the first forming roll.

In a preferred form, there is a path between which the band, and therefore the web, migrates generally tangentially to said two web-forming rolls, sandwiching the half-formed web therebetween. As such, these two forming rolls are placed at a predetermined distance. The relative threading of the knots due to the difference in instantaneous linear velocity between the two bands modifies the formation of flocs inside the web, which is still essentially unfinished in this area. Relaxation) Surno facilitates web rehoming.

At present, it is not easy to quantitatively demonstrate the effects of reverse dewatering and relative displacement of the web in the running direction, but these two effects work synergistically to completely reform floc formation. , which appears to improve web formation.

In one embodiment of the invention, there is a first section of a single-edged band in the first web forming zone, over which stock is fed from the headbox, and which band is sandwiched between another band and a single-edged band. A suitable guiding device is provided to facilitate the initial formation of the lower surface of the web on the band before it joins into a path that is part of the circumference of the first web-forming roll. It is designed to pass over the

It is believed that the good quality and two-way strength of webs made in accordance with the present invention is due to the special consideration given to the dewatering step before the web formation is fixed.

To clarify the meaning of the term here, the word "formation" generally refers to the distribution of fibers or fiber flocks in a finished sheet when viewed through light through the sheet, i.e. when viewed from the back. means. When the web is dewatered, the fibers are fixed in position with respect to each other, determining their position in the finished sheet.
Such fibers are formed [1] and are considered to have occurred instantaneously, and also fibers or fiber flocks that are suspended in a sufficient volume of water and have so much mobility that their relative position or orientation changes. It is defined as being in a "not yet formed" state.

Therefore, to apply the present invention, the above-mentioned "unformed" portion must always exist inside the web after passing through the first web forming roll.

To further explain the present invention in detail, as described above, the direction of water passage in a part of the web is reversed at the second web forming roll. That is, the balance of water flow towards the two wires (bands) in the second roll is different from that in the first roll, so that at least some of the fibers inside the web are swept in the opposite direction. This will affect the final appearance of the finished sheet.

Since the two wires or web-forming bands are substantially parallel between these two rolls, this means that there is a section between the two rolls where little dewatering takes place, or where dewatering is interrupted. That means there is. In this section, as described above, there is a relative deviation between the two wires in the running direction, causing shearing to the web that is being formed.

A web forming machine of the construction shown in the accompanying drawings, in which the web forming rolls include oven-shaped rolls without suction, makes it possible to realize a substantially suction-free machine. Since there is no drag (running resistance), which is often a problem when suction boxes are widely used, it is possible to drive one hunt loop with the other without significantly increasing the required power. Power requirements are even reduced when compared to comparable hood linear machines. This improved machine still
This will extend the life of the hand.

In other words, in a typical hood linear machine using flat boxes, foils, etc., these things create a considerable amount of drag, and the unavoidable amount consumes 6% of the drive power. . The drag through such devices for dehydration is sensitive to speed and water content.

The seal between the band and the suction box surface is greatly influenced by the amount of moisture present in the band and web. In the present invention, even if a Zakunoyon box is used, due to the high degree of dryness of the second web 7, the dryness of the second web 7 after the dehydration in the t-mi7 roll is completed, the drag caused by it is prevented. The higher the degree of dryness, the lower the amount. Furthermore, when a suction box is used, it is possible to operate with less vacuum.

Compared to a comparable hood linear machine, for comparable dryness in the couch, it is possible to save approximately 25% in power consumption with the machine according to the invention.

In other words, the operating speed can be increased without increasing power consumption.

The present invention still includes a method of forming a web between first and second endless web-forming hands, the method including applying stock onto at least one of these hands. , the two bands carrying the stock pass in a tapered state through the arc portion of the first web forming roll located in the loop of the first band, and the first web forming roll Dewatering of the stock in two directions occurs in the rolls to form the outer surface of the web, and the first step is such that at least the center of the web remains unformed, resulting in only partway web formation. The arc of the first web forming roll is between 30° and 60° in terms of LAl, and the web is in the vicinity of the first web forming roll and of the second band. of the second web forming roll which is in the loop, the first and second bands bend that roll in the opposite direction than before, i.e. at this roll part of the thickness of the web. A dewatering operation characterized in that the water is passed through in such a way that the direction of the flow of water therein is reversed, thereby completing the formation of the unfinished portions in said web. It is.

Hereinafter, the present invention will be explained with reference to the drawings, which are given by way of example only.

1 and 2 show web forming machines 10 and 30, respectively, both of which include first and second porous web forming pans 1 - upper band loops 1;
4 and the lower punt loop 12 are both supported by a plurality of kite rollers. Bands 12 and 14, commonly referred to as hood linear wires, are of what is known as forming fabric and are arranged to receive stock thereon which is conditioned to form waves upon dewatering.

Slice part 1 of head hox (not shown)
8 is arranged to deposit a layer of the first section 2 of the first band 12, and this first section 20 is the first web-forming sawn. Once the first supply of stock is possible and the first dewatering takes place downwards, it is placed under tension over a plurality of drainage elements represented by foil sections 13. ing.

Hands 12 and 14 are web forming rolls 22
The web forming roll 22 is bent to converge, ie to compress the stock, and the web forming roll 22 is fitted with a porous wire sleeve in a shrink fit on the grooved roll to form one oven mold surface. It comes in rolls. Such a roll 22 should preferably have an opening i+J on its surface of the order of 680%, such that the band 12 together with this roll has sufficient empty space to receive the drained water. , shall support the hand.

There is a portion of said initial web forming zone where bands 12 and 14 sandwich (compact) the stock as they travel along a portion of the circumference of roll 22, where dewatering of the stock occurs primarily. The web is partially formed by the effects of band tension and centrifugal force.
I2.

It takes place through 14.

The angle at which band 12.14 wraps around roll 22 is roll 2
2 must be restricted so that web formation is not completed. Although a wrap angle of approximately 45° is shown in the drawings, this degree has been found to be effective. However, by adjusting the dilution of the stock Cf) >1. If you do it, the range of winding angle will be 6o.

to 30° with satisfactory results in that web formation remains semi-advanced. After this stage, the half-formed web-sandwiched stock moves away from the roll 22 in its transverse direction and passes through the next stage along the second web-forming roll 24 in the vicinity of the roll 22. Web forming 7” −
leading to Band 12.14 is from roll 22 to roll 2
4, the tension bearings tend to move away from each other. After passing the path along rolls 24, the web is sufficiently dewatered, the relative positions of the fibers are fixed, and the web is fully formed. Band 12.14 is roll 24
Turn in the opposite direction from before and pass. That is, the band 14 that was on the inner side of the roll 22 is now on the outside of the roll 24. Roll 24 thus causes a reversal of water flow therein, whereupon the water flow is reversed as described above through a portion of the thickness of the forming web to complete web formation. .

In the structure of FIG. 1, the 0-rules 22, 24 are each in loops 14.12, whereas in the structure of FIG. 2 they are each in loops 12.14.

Since the two bands reverse the inside-outside relationship between the two rolls 22 and 24, a difference in linear velocity naturally occurs between these two bands. causes displacement in the longitudinal direction relative to the It occurs within a band relative offset zone intermediate the first and next web forming zones, thereby causing a relative shift between the already formed web portions being carried oppositely by the respective bands. Considering the final web formation achieved by the machine, this will occur if shear is applied in a defined direction before the web formation is complete and the fibers are fixed in position. This longitudinal movement, as is well known in the art, can be used to modify the floc formation within the web before dewatering occurs to the extent that web formation is complete at roll 24. It is thought that it plays a part in the re-homing effect.

In the embodiment shown in FIGS. 1 and 2, the roll 24 is a plain roll, so dewatering is performed outward from the roll surface.

Band I'2 after passing through the roll 24 in the embodiment of FIG.
, 14 pass through a kite roll 26 to a table roll or guide roll 28, where the band 14 is pulled to a guide roll 29, but the hand 14 is gradually separated from the web and the hand 12 in the zone where the band separates. The angle between them is less than 10°, preferably in the range 2° to 6°. Table roll 28 helps hold the web on band 12 and feed it to suction couch roll 30, but it is not special. When the band 12 passes through the suction couch roll 30, the web is securely attached to the hand. In the embodiment of FIG. 2, only table roll 28 is required since bands 12, 14 emerge from the underside of roll 24.

(Roll 26 is not needed.) The second forming roll 24 has been confirmed to be sufficiently effective as a solid roll (plain roll), but it is used when obtaining a thicker grade product or when using stock that is difficult to dehydrate. If necessary, it would be better to use an open roll having a structure similar to the roll 22 for suction forming, that is, roll play for vacuuming. In the latter case, the roll 24 would be the surface of the oven to remove water from the web and into the interior of the roll.

In the embodiment of FIG. 2, the second web forming roll 2
Since dehydration is carried out downwards at location 4, water treatment is a good option. Therefore, this formation is suitable for cases where there is a large amount of water to be removed, such as in the case of pulp forming sections or when dealing with large slow craft classes.

FIG. 3 shows a further embodiment of the present invention, which is roughly similar to FIGS. 1 and 2, so a detailed explanation will be omitted, and similar parts will be given similar numbers. It is shown with .

In the intended embodiment shown in FIG.
is located near roll 22 and supplies stock to Norn before bands 12 and 14 become convergent. The abbreviated device shown in FIG. 3 may be based on FIG. 1 or on FIG. 2.

The performance of the web made with the improved fortwo according to the embodiment shown in FIG.
Although it has been proven that it has excellent axial strength,
This is particularly suited to the needs of many special purpose papers.

The present invention makes it possible to form a web using a substantially suction-free machine. In other words, there is no formin crawl to draw a vacuum, or something like satanyong foaming hooseok is virtually eliminated, or the number of boxes and the degree of vacuum are reduced to reduce drag and operate. It has the characteristic that it is possible to

Although band 14 is the second wire in this combination of bands (wires), it does not require a separate drive and is effectively driven by the first wire, band 12. The wire drive power is effectively reduced compared to comparable hood linear machines due to fewer suction boxes or the ability to operate at lower vacuum levels. This machine has a band 1
The life of the woven wire or fabric used in 2.14 will be extended. This advantage is also expected for twin-wire machines that use forming shoes to dewater the web.

In Figures 4A and B, the former is a photomicrograph of a cross-section of newsprint made on a machine according to the invention, and the latter is a paper of the same grade made from the same stock on an equivalent food linear type machine. This is a similar photo.

In FIG. 4A, it can be seen that the fibers are clearly longer than in FIG. 4B in the case of the hood linear type, as they cross the center plane of the sheet. This shows that the present invention can produce a material with excellent strength in the Z-axis direction with respect to the increased force S of the interlayer bonding.

To further illustrate the expected effects when a machine made in accordance with the present invention is operated in the manner described herein, a comparison is made below with a sheet made on an equivalent hood linear type machine. The table shows the results of several tests carried out at the Motel Test Department, which was able to operate in a hood linear type.

The numbers in the [Tess)NnJ column of the above table showing the test results are the serial numbers of the tests; those with an F are hood linear type machines, and those with a moat are twin wires of the type shown in Figure 1. machine is shown. ``Weight'' is the basis weight of the seat (reference weight) and ``Speed'' is the operating speed of the machine.

1 Stock concentration % is the solid content percentage in the stock supplied from the headbox 1 Specific volume is the specific volume of the stock supplied.

``Permeability rate s//rr11.J'' indicates the time, in seconds, for 11 nl of air to permeate through the thickness of the web under normal conditions, as determined by the porosity test of paper in a bone dry condition.

"The breaking length (vertical) ml indicates the tensile strength of the sheet in the longitudinal direction, and m is the limit length at which the sheet can break under its own weight, and MD indicates the machine direction (vertical direction). means.

"The breaking length (transverse) ml is the tensile strength in the direction of lateral force determined in the same way, that is, the maximum sheet length that can be broken under its own weight, and CD means the cross direction (lateral direction).

[Break length ratio (vertical/horizontal)] is the ratio of the tensile strength in the MD direction of the web to the tensile strength in the CD direction.

[Thea index mN, tr? /f J is the tear strength in the longitudinal (MD) direction of the web expressed in mN per basis weight.If the basis weight is expressed as 9 layers, it is entered as the reciprocal, so mNrr? /
y is the degree.

“The tear index mN, rr?//l J similarly indicates the tear strength in the transverse (CD) direction of the web.

[Tear Index Ratio (Vertical/Horizontal)] This is the ratio of the tear strength in the vertical and horizontal directions.

"Thickness cms" is the thickness of the web in cm.

1 Bond strength KJ/, J is the pound strength inside the web (
The value of the BIC test indicating the strength in the Z-axis direction is expressed in KJ.

From the comparison of the test results shown in the table above for rotary seams 1-thickness and operating speed, the following can be concluded.

Looking at the test numbers for the first and second tests, IF and 3T/W, the speed for both is 610 layers m/, l, te, 17w.
Although the stock is a little thinner, there is a difference in weight.

That is, the porosity of the web is substantially reduced.

Approximately 40% have low porosity.

The tensile strength was increased by 34% in the longitudinal direction and 23% in the transverse direction, and the internal pound strength was increased by 20%.

It can be seen that most of the test results show a similar consistent trend in that sheets made with this soil earer outperform sheets made with hood linear type machines. Tatami, test with thin paper, 7F (!: 15T/
The comparison of w is an exception, and only in this case the twin wire sheet is more porous. (In this case, the reason may be that the concentration of the supplied stock was 46:60 and TAr was thinner.) Sea 1: of the year is 8% larger.

It has also been found that the hood linear sheet made by the machine according to the invention is significantly superior to sheets made by other known twin-wire formers in a consistent manner in pound strength. It is sure to be eye-catching, and when compared with other machines, the advantages of the present invention will become even more apparent.

[Brief explanation of the drawing]

FIG. 1 is an elevational view showing the outline of a first embodiment of a web forming machine according to the present invention. FIG. 2 is a similar elevational view of a second embodiment of the web forming machine according to Honmenmei. FIG. 3 is a similar elevational view of a third embodiment of a web forming machine according to the invention. - Figure 4A and Figure 4B respectively show micrographs of paper produced by a machine according to the invention and a paper produced by a similar food linear type machine. l2: First band 13: Foil device 14: Second band 18 Ni slice nozzle 20: First section of the first band 22: First forming roll 24: Second forming roll 26: Forming roll 28 Ni Guide roll (table roll) 29: Guy 1-
Roll 30: Couchyrol patent applicant) Mionic worker ＞ ° 2 Alin Q 'Tsukusa 1 flea 〒, L -”FIG, 1 FIG, 4a. FIG, 4b. Display Showa Pre-Year ml#?x No. 137F?3'7 No. 2
, Name of the invention Sea 1' 7 to 7... M'A' 1 move (
3.Relationship with the case of the person making the amendment Applicant L Mishiwashi〉=7Socraft゛Sonn~'nomite 4, agent left, fee chi light 1 (Drawing Otsurai City゛correct) Sodai + Figure △ Ayo lA MqmBl Chi 11th handout period Sone city ゛ Rusu 3゜

Claims (1)

[Scope of Claims] (11) A method of forming a web between first and second endless web forming bands 12.14, including the step of supplying stock to at least one hat;
The stock is sandwiched between these bands, and the bands 12,14 carrying the stock are placed over the arc of the first web forming roll 22 placed in the loop of the first hat 12 or 14. The step of dewatering the stock by passing it through this point in such a way that it tapers to a point, and its arc above the first web forming 22 substantially so that only a partial dewatering of the web takes place there. In the web forming roll 22, dewatering is performed in two directions to form the outer surface of the web and leave the inner part unformed. during which the dewatering is substantially interrupted by running in parallel to the first web-forming roll; The web is conveyed to a second web forming roll 24 at which the first and second bands are arranged so that the direction of dewatering through part of the thickness of the interior of the web is reversed. A method of forming a web comprising the step of passing the roll 24 in a reverse direction to complete the formation of previously unformed portions of the web. (2) first and second endless web-forming bands 12, 14, said bands 12.1, receiving between them the stock which is to be formed into a web by dewatering;
a source device 18 for supplying stock to at least one of the first and second bands 12.1, in the loop of the first band 12 or 14, over the arc of its roll;
The first web forming roll 22 passes through the web in a tapered state because it is bent by the circular arc, and the circular arc on the first forming roll 22 allows the web to be formed only halfway in this roll 22. The first forming roll is an oven non-suction roll in which dewatering occurs in two directions to form the outer surface of the web. the web is formed in at least a portion of the web, and there is a second forming zone formed by a second forming roll 24, which roll 24 is in close proximity to the first forming roll 22. , second band 14
Or within the loop of 12, the first and second pans F12, 14 are in this second web forming roll 2.
4 in a curved manner opposite to the previous case, so that here the direction of the water flow in that part of the web in its thickness is reversed and here the previously still formed part of the web is reversed. 1. A web forming machine equipped with a device for stock dewatering, characterized in that forming of a portion that has been left untreated is completed. (3) Between the first web forming zone and the second web forming zone, there is a zone where bands are shifted relative to each other and dehydration is interrupted, and in this zone, one bunt is vertically dislocated with respect to the other band. 3. A web forming machine according to claim 2, characterized in that the two bands are substantially parallel. or (1) characterized in that the initial web-forming zone has a section 20 of said first band 12 above which said stock is received and drains downwardly through said band; or The machine described in paragraph 3. (5) At the point where said stock is fed to said wire, a plurality of foils 13 are arranged so that dewatering takes place from said band 12 advancing to a first roll 22. The machine according to any one of items 2 to 1, characterized in that: (6) The machine according to any one of items 2 to y, wherein the arc extends substantially over a range of 45°. (Force) The machine according to any one of paragraphs 2 to 6 except paragraph 4, characterized in that the first band 12 rests on the second hand. (81 The machine according to any one of clauses i2 to 6, characterized in that the first band 12 is located below the second band 14. (9) The second roll 24 has a substantially impermeable surface, and as said web passes around said roll 24 05 inwardly or to the side of the roll 24;
The machine according to any one of paragraphs 2 to 8, in which dehydration is not performed. (10) Said second roll 24 has an oven-type surface for receiving water dewatered from said web inwardly with respect to the surface of said roll 24. Machine described in any of paragraph 2. (11; The second forming roll 24 is
3. Machine according to claim 2, characterized in that it is a roll that draws a vacuum to assist in dewatering said stock. (12) Following said second web-forming zone is a kite device 28,29 of the hat, which is hand-held so that said bands 12,14 are in divergent relation to each other at a 10° terminal angle. 12. The device according to any one of items 2 to 11, characterized in that the device guides a user. (+31) The angle of said divergence is substantially 2°, and said web and one of the bands on which it rests reach a suction device 30 to ensure close contact of the web to said band 12. (141) The machine according to paragraph 1z, characterized in that said suction device comprises a couch roll 30. (15) A foot linear mold in said first web forming zone. A section of the forming wire of the machine section is included, and the first web forming roll 22 is placed over this, and the second forming roll 24 is of the hood linear type. a second characterized in that it is within the loop of the mechanical section;
The machine described in any of paragraphs 6 to 6. (16) said stock source 18 is located adjacent said first forming roll 22 and supplies said stock to the zone where said band 12.14 tapers; The machine according to any one of Items 2 to 15. θ7) One band 14 is connected to the other node 12.
The second term to the first term are characterized in that they are driven by
Machine according to any of paragraph 6.