US2134408A - Forming paper webs - Google Patents

Description

Oct. 25, 1938.

Y@ w@ Y@ Y@ n@ w R. KELLETT 2,134,408

FORMING'PAPER WEBS Filed Aug. e. 1935 4 Shets-Sheet l Oct. 25, 1938. w R, KELLETT 2,134,408

FORMING PAPER WEBS Filed Aug. 6. 1936 4 Sheets-Sheet 2 Oct. 25, 1938.

w. R. KELLET 2,134,408

FORMING PAPER WEBS Filed Aug. 6. 1936 4 Sheets-Sheet 3 Oct. 25, 1938.

W. R. KELLETT FORMING PAPER WEBS 4 Sheets-Sheet 4 Filed Aug. 6. 1936 Patented Oct. 25, 1938 UNITED STATES FORMING PAPER WEBS William It. Keilett, Mcnasha, Wis., assignor to Paper Patents Company, Neenah, Wis., a corporation of Wisconsin Application August 6, 1936, Serial No. 94,517

^ 7 Claims. (Cl. 92-44) The invention relatesto formation of paper webs and is of particular value in connection with paper machines equipped with F'ourdriniei` forming wires. It has its chief application in the manufacture of paper at relatively high speed, for example, speeds in excess of 600ifeet per minute, although the principles involved may be susceptible of utilization in the production of paper webs which are usually produced at'relatively low speeds.

In forming paper upon a Fourdrinier wire it has been, so far as I am aware, the almost universal practice to form the mat of fibres of which thel web is composed, by `applying to the upper surface of the Fourdrinier wire a layer of paper stock containing the required amount of fibre in an amount of water which is suiiicient to produce the proper distribution of the fibres in the stock supply, while at the same time being in an amount Within the drainage capacity of the machine, i. e. the ability ofthe wire and its associated instrumentalities such as doctors, table rolls and suction boxes, to eliminate the load of water which must be removed to produce a coherent web which iscapable of being couched cil the end of the wire.

In view of the fact that in the usual Fourdrinier machine, except in the suction box zone, there is no substantial pressure differential tending to force the water through the mat and the wire, it is necessary to allow a long period of time for proper drainage to occur and hence, the Fourdrinier wire must be made of great length, or the machine must be operated at slow speed, or both.

Also, so far as I am aware, in order to obtain a good formation of paper web, and one having cross-directional strength as well as longitudinal strength, it has generally been thought to be necessary to effect a felting of the fibre mat relatively slowly so as to give the bres a suiiicient length of time to assume their correct positions in the web, and to correct mal-adjustment of the fibres, and improve the felting, such expedients as side shaking of the Fourdrinier wire have been frequently employed.

I have discovered that by the use of suilicient pressure applied to a body of stock supported upon an exposed zone of the traveling Fourdrinier wire, I can effect the removal of practically all of the water load and produce an exceptionally well felted mat of fibres of the required basis weight during a few inches of travel of the Fourdrinier wire as compared with the travel of many feet in the ordinary case where natural drainage is depended upon for forming the mat, and this result can be obtained at a much higher speed than has heretofore been considered feasible in effecting an equally good formation. Furthermore, I have found that when 5 forming paper according to this invention, tremendous volumes of water may be removed at high speed so that the consistency of the stock may be lowered to a greater extent than has heretofore been considered practical with the 10 result that the formation is greatly improved.

I am aware that prior patentees have snown machines designed to remove a small percentage of Water through the wire before the wire has passed under the slice, but, so far as I am informed, with such machines it was Anever intended nor was it recognized, that it was desirable or possible to eiect the removal of the greater part of the water load before the wire passed under the slice or that a properly felted mat of fibre of substantially the ultimate basis weight required could be produced in that manner.

In all such prior machines which have been brought to my attention, the space between the lip of the slice and the upper surface of the wire cation to the wire of a layer of stock of the customary thickness and customary consistency by the aid of a slice having an opening of the usual height.

As distinguished from these prior devices, according to my invention, the spacing of the slice from the wire is not relied upon as a factor in the control of the volume of dilute stock which is to be handled by the wire. On the contrary, according to my invention, the purpose of the slice is to confine the stock in a pressure zone above an exposed area of the traveling wire and, so far as possible, to prevent anything but the formed mat from' flowing out of the pressure zone above the upper surface of the wire.

To this end, carrying out my invention, I position the lip of the slice as close to the wire as 5 ydilute stock as must necessarily pass under the slice through the minute space between the slice and the mat serves mainly as a lubricant, and to avoid any disarrangement of the fibers in the mat as the wire leaves the zone of pressure.

In carrying out my invention, I find that it is desirable to employ such pressure thatv such dilute stock as does leak out on top of the mat under the lip will be ejected at a velocity closely approximating the speed of the wire.

The drawings accompanying this application show the invention as applied to a machine used in the manufacture of facial tissue paper. In said drawings Fig. 1 is a schematic view, partly in side elevation and partly in vertical section, of the wet end of the machine and accessory equipment therefor,

Fig. 2 is a vertical section through the inlet or means for supplying. stock to the wire,

Fig. 3 is an enlargement of a portion of Fig. 2, Fig. 4 is an elevation of certain parts shown in Fig. 3,

Fig. 5 is an elevation showing the enlarged ex-\ terior of the inlet nozzle plate and associated parts,'and

Fig. 6 is a section taken on theline 6-6 of Fig. 5.

General organization Fig. 1 of the drawings shows diagrammatically the machine proper and a number of accessory devices that are preferably employed therewith. A designates as an entirety the usual Fourdrinier wire, B a tray underlying the wire, -and C a mixing tank underlying the tray B. This mixing tank C is normally nearly illled with water that has passed through the wire A and out of the tray B, and this water, with fresh stock added thereto, is sent back to the inlet nozzle D by a circulating pump E in a flow line F, having a flow-regulating valve F on the discharge side of the pump. Fresh stock from the beater chest passes into a De Zurik consistency regulator G, whence the stock flows into a machine chest H. From the machine chest H the stock is moved by a pump K through a pipe line L, to a headregulating cone S within a cone M. A pump I in a pipe N maintains a circulation of stock in the chest H; and for convenience the intake of pump K may be connected to the circulation pipe N as shown. From the cone S stock flows through a pipe O having an orice control indicated at o into one end of the mixing tank C under a constant head maintained by the cone S. The overflow from cone S into cone M returns through a pipe T to the chest H. A portion of the stock in the stuff cone S may also be sent through a pipe P having an orifice control indicated at p to a Jordan engine Q from which it is delivered to the pipe O through a pipe R.

At the opposite end of the mixing tank C is a valve-controlled. pipe U through which fresh water may be added to the body of stock in the tank as required to maintain a constant level in the tank C. As will be later explained, the flow passage in the tank C is divided, and a minor portion of the stock in the tank is sent through a pipe line V, to sprays later described. Tapping the main flow line F is a branch pipe line W leading to a sump and normally closedby a' valve X. Also connected at the bottom of the tank C is a waste line Y directly in front of a low dam Z extending across the flow passage of the tank, by which dirt or other sediment collecting in front of the dam may be drained oif.

The inlet A pair of stationary side frames 25 support on their top horizontal edges a pair of vertical walls 26, formed on their lower edges with flanges by which they may be rigidly clamped on the side frames 26. Secured in a liquid tight manner to and between walls 28 are curved upperl and lower plates 3| and 32 which with the side walls 28 form a closed spout of a generally goose-neck form. 'Ihe cross section of this spout has been so designed that there are no hydraulic dead areas present where stock can clog or settle out. 'Ihe design also provides for a high velocity flow through the inlet for the same reason. Preferably, to avoid fouling, the interior of the spout is made of stainless steel.

Extending between and connecting the side frames 25 is a cross beam 33 formed with an integral top plate 34 the forward portion of which projects forwardly so as to partly overhang the breast roll 35. Secured to this forward portion of plate 34 is the stationary bottom lip or nozzle plate 36 of the spout, the forward portion 36' of this lip is inclined downwardly slightly and extends approximately to the center line of the breast roll so as to deliver the stock tangent to the latter.

Overlying the forward portion of the lip is an oilcloth apron 36", the forward free edge of which overlies the wire at substantially the center line of the breast roll. Slidable on the top plate 34 and the rear portion of the bottom nozzle plate 36 is a plate 3l, to the forward edge of which the forward edge of the lower spout plate 32 is secured. Secured to and continuous with the rear portion of the plate 31 is a depending frame structure 38 lying between and secured to depending portions of the side walls 26. The frame structure 38 constitutes a holder and stiffener for the depending portion of'the spout.

To the lower end of the frame 33 are connected the stock supply conduits 38. Between the side walls 26 extends a hollow beam 44 to the lower side of which the forward terminal portion of the upper spout plate 3| is welded or otherwise secured. To the front wall of the beam 44 is attached, by screw bolts 45, a vertically adjustable bracket 46, the screw bolts 45 extending through slots 41 in the transverse vertical wall of the bracket.

Referring to Fig. 3, on the lower edge of bracket 46 is a rib 48 to opposite sides of which are secured, as by clamp strips 49, a pair of ber strips 5| that extend below the rib 48 and are formed in their opposed faces with bearings for the brass pintle rod 52 of the brass upper nozzle plate 53. Preferably,`the lower end of the nozzle plate or slice 53 terminates in a lip 53a having a sharp edge or angle, as according to my experience with the invention a rounded edge does not give the best results.

The bracket 46, to the lower end of which the top nozzle plate 53 is pivoted, may be adjusted vertically, after the clamp bolts 45 have been released, by a mechanism fully described inLetters Patent to Kellett and Ostertag, No. 2,060,808, November 17, 1936, which has been assigned to the assignee of the instant application.

It will beobserved that the lip 53a of the slice is located at a point along a wire extending between the point .where the wire leaves the breast roll and engages the ilrst supporting roll |66 and that between the forward edge of the slice 53, and the point where the wire is tangent to the breast roll, the upper surface of the wire is exposed to the full force ofthe pressure of the stock within the spout of the inlet.

Y The pressure of the stock supplied to the inlet is closely regulated so that the pressure within the spout and under the slice 53 is such as to produce at the lip 53' a' spouting velocity approxi-` mately equal to the speed of the wire. The volume of stock which is to be handled by the wire is controlled almost altogether by the amount of such inlet pressure and the area of wire exposed to such pressure. -The space between the lip .538L and the Wire does not play any particular part in such control. In fact according to the invention, the lip 53 is lowered until it is so close as to appear to be in contact with the Wire so that it functions as a means for preventing the dilute stock from flowing onto the wire rather than as a means for distributing the stock on the wire. In practice I find it advantageous to lower the lip 53 until it is so close as to drag out the fibers longitudinally and then raise it slightly so as to provide a very minute clearance between the mat of fibers formed on the wire, the small amount of stock which must necessarily pass out of the inlet with the mat serving mainly as a lubricant. In other words, according to my invention the lip 53e functions mainly as a gland for the wire and mat as they emerge from the inlet.

The invention has been very successfully used in the production of tissue papers of various kinds, having a basis weight of from 6 to 14 pounds per ream. Although, because of the immense cost of building these high speed paper machines and their associated equipment, it has not been possible to make commercial tests of the invention on machines suitable for making papers of much heavier basis weight such as book papers, my experiments indicate that the invention is of value in connection with the production of heavier papers than have heretofore been commercially produced by the use of this invention.

'I'he invention so far has had its chief commercial use in the manufacture of tissue paper having a basis weight of about l0 pounds per ream. In making such papers it is feasible to operate the machine at a speed of 1250 feet per.

minute while making paper having excellent formation and other necessary characteristics. In operating the machine at such speed and upon such paper, I find that for a spouting velocity of 1200 feet per minute at the lip according to the well-known formula, u equals the square root of 29h, the pressure at the lip should be equal to a head of about 75 inches of Water. I find itv also advantageous to employ a stock consistency of approximately #6 of 1%. At such consistency and with a speed of 1200 feet per minute, virtually all of the water load is drained out through the wire before the latter passes under the lip, 4so that by the time the wire passes under the lip the mat of fibres which are to form the sheet, is substantially completely formed. This water drainage takes place through the exposed surface of thewire extending between a tangent to the breast roll and the edge of the slice, which distance is only a few inches.

If all of the stock to be handled by the wire had to be distributed by the slice, i. e. if it had to pass under the lip of the slice, it would be necessary, under the conditions stated, to have the slice adjusted to deliver a jet about 1% ofl an inch in depth. Under the same stated conditions, and with the slice and wire arranged in accordance with my invention,` more than 80% of the drainage may be effected within the inlet so that the combined thickness or depth of the mat and the superjacent stock film need not be more than about .04 inch to .09 inch in thickness. Hence, the natural drainage through the wire between the slice and the suction box is not required to handle more than a very small fraction, say less than 10%, of the total load of water in the stock so that, if desired, the wire can be made very much shorter than in the case of the ordinary Fourdrinier wire machine where the slice serves to distribute the major volume of the stock upon the wire and the main water load must be removed by natural drainage through the wire.

It will be recognized that in practicing my, invention with a nozzle pressure of 75 inches of water, a relatively heavy load is imposed upon the wire under the nozzle plate 53. No attempt is made to stretch the wire horizontally between the breast roll and the first table roll support |66 as any such attempt might result in excessive wire tension. According to the practice which I have followed, the wire tension is adjusted so as not to exceed the amount which can safely be imposed upon the wire'in practice, and the wire under the slice is permitted to sag under the imposed pressure or load. The apparent difficulty of adjusting ,the nozzle plate to the required minute opening, notwithstanding the sag in the wire, is overcome by the special means employed for effecting a quick bodily vertical movement of the entire nozzle plate 53. It will be observed that the lower edge or lip 53 of the /nozzle plate or slice under the conditions illustrated, is positioned at a point very substantially below a tangent extending between the upper peripheries of the breast roll 35 and the rst supporting table roll |66. In fact, in the particular machine discussed, thev wire runs uphill between the slice and the first table supporting roll and does not begin to runldownhill in the customary manner until it reaches the second or third table roll.

In the particular machine illustrated, the wire v because of the fact that the outer margin of the wire is not subjected to pressure of the stock within the inlet, said marginwould tend to extend in;av straight line between the breast 'roll and the 'rst table roll with resulting in-` jury to the wire at the point where it extended laterally from the side of the nozzle. Such possibility of .damage is overcome by the arrangement shown in Figs. 5 and 6 of the drawings in which 86 represents one of the side plates secured to the slice 53 by screws 85, to which plate 86 there is secured a bolt 81 serving to compress asponge rubber pad or block 88 under which is located a rubber shoe 92 which serves to hold down the projecting margin of the wire, thereby to maintain the same in horizontal alignment with the main working part of the wire under the slice. It will be readily understood that the parts 86, 81, 88 and 92 which are secured to the side edge of the nozzle plate .53, move up and down' as a unit with' the nozzle plate when the latter itself is moved up and down by the quick action raising and lowering means previously referred to.

Although the stock inlet organized according to my invention may be very successfully operated with the distributing roll or cylinder |08, the fact that my invention may be practiced with an extremely low stock consistency enables the stock inlet to be operated in certain cases without the distributing roll.

Such tests as I have made indicate that the invention is not restricted to any particular inclination of the nozzle plate 53. In fact, I have successfully used a nozzle plate the lower end of which was approximately vertical.

A more detailed description of the structure and operation of the various parts or elements described herein or illustrated in the drawings is given in the application of Kellett and Ostertag, Serial No. 94,516, filed simultaneously herewith, which has been assigned to the assignee of this application. Y

Other variations or modifications of the general principles above outlined will naturally occur to those skilled in the art in adapting such principles to various uses and conditions re quired or encountered in actual practice. Hence, the scope oi the invention herein described should be determined by reference to the appended claims, which it is my intention should be construed as broadly as possible, consistent with the state of the art.

I claim as my invention:

1. The method of continuously forming a paper web on a Fourdrinier wire, which includes: confining a body of dilute paper stock under pressure over an exposed zone of the upper surface of a traveling Fourdrinier wire in advance of a slice, the length of said exposed zone in the direction of wire travel being suflicient to eiect the drainage'of most of the water fr om the stock before it reaches said slice and to form on said wire, in said pressure zone, a mat containing approximately all of the fiber required for the weight of web desired, said pressure being such as to produce a spouting velocity at the lip of said slice substantially equal to the speed of said wire; and spouting a relatively thin layer of dilute paper stock directly from said body onto said mat as it passes under said slice.

2. A method of continuously forming a paper web on a traveling Fourdrinier wire, which includes: conning a body of dilute paper stock over an exposed zone of the upper surface of a traveling Fourdrinier wire in advance of a slice; and maintaining said dilute paper stock under such pressure and so adjusting such slice as to produce at the lip of the slice a spouting velocity substantially equal to the speed of the wire, the length of said exposed zone in the direction of Wire travel being sufiicient to effect the drainage of most of the water from the stock and to form on the Wire, before the wire passes out of the zone of pressure, a mat of approximately the fiber content desired in the final web, the adjustment of said slice also being such as to permit the spoutingvof a relatively thin layer of dilute stock directly from said body onto said mat as said mat passes under said slice.

3. The method of continuously forming a paper web on a traveling Fourdrinier wire,'which includes: delivering a supply of dilute paper stock to a chamber over an exposed zone of the upper surface of a traveling Fourdrinier wire in advance of a slice, confining said supply of dilute paper stock under such pressure as to produce, at' the lip of the slice, a spouting velocity substantially equal to the speed of the wire, the

aisance length of said exposed zone in the direction of wire travel being sumcient to effect drainage of most of the water from the stock and to form on the wire. ,before the wirepasses out of the zone of pressure and under said slice, a mat containing approximately the full amount of fiber required in the desired web; spouting a thin layer oi dilute paper stock directly from said supply onto said mat as said mat passes under the slice, the volume of stock spouted onto said mat beyond said exposed zone being approximately 10% of the total volume of stock delivered onto said exposed zone.

4. The method of continuously forming a paper web on a traveling Fourdrinier wire, which includes: delivering a supply of dilute paper stock to a chamber over an exposed zone of the upper surface of a traveling Fourdrinier wire in advance .of a slice, confining said supply of dilute papery stock under such pressure as to produce, at the lip of the slice, a spouting velocity substantially equal to the speed of the wire, the length of said -exposed zone and the direction of Wire travel being suillcient to eiect the drainage of most of the water from the stock and to form on the wire, before the wire passes out of the zone of pressure and under said slice, a mat containing, approximately the full amount of ber required in the desired web; spouting a relatively thin layer of dilute paper stock directly from said supply onto said mat as said mat passes under said slice; and maintaining the Volume of stock so spouted along the wire at a minimum while avoiding any substantial disarrangement of the fibers in the mat as the mat passes under said slice to leave the zone of pressure.

5. The herein described method of forming a paper web on a Fourdrinier wire traveling at a speed of approximately 1200 ft. per minute, which includes: confining a body of dilute paper stock over an exposed zone of the upper surface of a and under a pressure approximately equal to that of a head of 75 inches, whereby there is produced, at the lip of the slice, a spouting velocity substantially equal to the speed of the wire, the length of said exposed -zone in the direction oflwire travel being sufficient to effect the drainage of approximatelyv 90% of the water from the stock and to formA on the wire, before said wire passes out of the zone of pressure and under the slice, a mat of fibers containing substantially the full amount of fiber desired inthe ultimate web; and spouting a relatively thin layer` of dilute stock onto said mat directly from said body-as said mat passes under said slice.

6. The herein described method of forming a paper we b on a Fourdrinier wire traveling at a speed of approximately 1200 ft. per minute, which includes: conilning a dilute body of paper stock over an exposed zone of the upper surfacev of a traveling Fourdrinier wire in advance of the slice and under a pressure approximately equal to that of a head of 75 inches, whereby there is produced, at the lip of the slice, a spouting velocity substantially equal to the speed of the wire, the length of said exposed zone in the direction of wire travel being suflicient to effect the drainage of .approximately 90% of the water from the stock and whereby there is formed on the wire, before the wire passes out of the zone of pressure, a fiber mat of substantially the basis weight of the final web; and spouting a relatively thin ,layer of dilute stock onto said mat directly from said body as said mat passes under said slice, the volume -travelingFourdrinier wire in advance of a slice of stock spouted onto said mat beyond said exposed zone containing approximately 10% of the total volume of water delivered onto said exposed zone.

7. The method of continuously forming a paper web on a Fourdrinier wire traveling at a speed of at least 1200 feet per minute, which includes: conning a body of dilute paper stock under pressure over an exposed zone of the upper surface of said traveling Fourdrinier wire in advance of a slice, the length of said exposed zone in the direction of wire travel being suflicient to effect the drainage of nearly all of the water from the stock before it reaches said slice and to form on said wire, in said pressure zone, a mat containing approximately all of the liber required for the weight of web desired, said pressure being such as to produce a spouting veloctiy at the lip of said slice substantially equal to the speedA of said wire; and spouting a. relatively thin layer of dilute paper stock directly from said body onto said mat as it passes under said slice.

WILLIAMR.KEILETI.

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