Forming paper webs

Oct. 25, 1938. w. r. kellett 2,134,408

FORMING.PAPER WEBS

Filed Aug. 6, 1936 4 Sheets-Sheet 1

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Oct. 25, 1938.

2,134,408

W. R. KELLETT

FORMING PAPER WEBS

Filed Aug. 6, 1936 4 Sheets-Sheet 2

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Oct. 25, 1938.

2,134,408

W. R. KELLETT

FORMING PAPER WEBS

Filed Aug. 6. 1936

Sheets-Sheet 3

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Oct. 25, 1938. w. r. kellett 2,134,408

FORMING PAPER WEBS Filed Aug. 6, 1936 4 Sheets-Sheet 4

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Patented Oct 25,1938

2,134,408

UNITED STATES PATENT OFFICE

2,134,408

FORMING PAPER WEBS

William R. Kellett, Menasha, Wis., assignor to Paper Patents Company, Neenah, Wis., a corporation of Wisconsin

Application August 6, 1936, Serial No. 94,517

Claims.

The Invention relates to formation of paper webs and is of particular value in connection with paper machines equipped with Fourdrinier forming wires. It has its chief application in the manufacture of paper at relatively high speed, for example, speeds in excess of 600 feet 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 the 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 sufficient 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 of the 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 is capable of being couched off 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 fibres a sufficient 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 sufficient 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 ease where (Cl. 92—44) 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 ⁵forming 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 ¹⁰result 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 in- ¹⁵formed, with such machines it was never intended nor was it recognized, that it was desirable or possible to effect the removal of the greater part of the water load before the wire passed under the slice or that a properly felted mat of ²⁰fibre 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 ²⁵has been about equal to the space required to lay upon the wire a layer of stock of customary consistency and of required thickness to form the web. Such patentees, so far as I am aware, made no departure from the prior practice except that ³⁰a small percentage of additional water was added to the stock, and this minor percentage of water was removed through the wire prior to the application to the wire of a layer of stock of the customary thickness and customary consistency ³⁵by 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 ⁴⁰the 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, ⁴⁵so 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 ⁵⁰is possible to do without exerting any drag upon the ends of the fibres sticking out from the top of the previously formed mat which is carried under the slice by the traveling wire. Such dilute stock as must necessarily pass under the ⁶⁸

2,184.408 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 that 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- _sterior of the inlet nozzle plate and associated parts, and

Fig. 6 is a section taken on the line 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 filled 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 orifice 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 closed by 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 off.

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 ₆which they may be rigidly clamped on the side frames 25. Secured in a liquid tight manner to and between walls 26 are curved upper and lower plates 31 and 32 which with the side walls 26 form a closed spout of a generally goose-neck io form. The cross section of this spout has been so designed that there are no hydraulic dead areas present where stock can clog or settle out. The design also provides for a high velocity flow through the inlet for the same reason. Prefer- 15 ably, 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 20 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 25 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 so 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 37, to the forward edge of which the forward edge of the lower spout 35 plate 32 is secured. Secured to and continuous with the rear portion of the plate 37 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 stiff- 40 ener for the depending portion of the spout.

To the lower end of the frame 38 are connected the stock supply conduits 39. Between the side walls 26 extends a hollow beam 44 to the lower side of which the forward terminal portion of 45 the upper spout plate 31 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 47 in the transverse vertical wall of the bracket. °”

Referring to Fig. 3, on the lower edge of bracket 46 is a rfb 48 to opposite sides of which are secured, as by clamp strips 49, a pair of fiber strips 51 that extend below the rib 48 and are formed _Soin 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 53» having a sharp edge or angle, as according to my experience with 30 the invention a rounded edge does not save 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 re- 35 leased, by a mechanism fully described in Letters 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 be observed that the lip 53» of the slice 70 is located at a point along a wire extending between the point where the wire leaves the breast roll and engages the first supporting roll i 66 and that between the forward edge of the slice 53, and the point where the wire is tangent to the breast 7*

2,134,408 roll, the upper surface of the wire is exposed to the full force of the pressure of the stock within the spout of the inlet.

The pressure of the stock supplied to the inlet 5 is closely regulated so that the pressure within the spout and under the slice 53 is such as to produce at the Up 53 a' spouting velocity approximately equal to the speed of the wire. The volume of stock which is to be handled by the wire 10 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 53» and the wire does not play any particular part in such control. In fact according to the inven15 tion, the Up 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. 20 In practice I And it advantageous to lower the Up 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 25 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 Up 53» 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 35 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 40 in connection with the production of heavier papers than have heretofore been commercially produced by the use of this invention.

The invention so far has had its chief commercial use in the manufacture of tissue paper 45 having a basis weight of about 10 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 50 ¹¹¹ 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, v equals the square root of 2gh, the pressure at the lip should be equal 55 to a head of about 75 inches of water. I find it also advantageous to employ a stock consistency of approximately A 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 80 wire before the latter passes under the lip, so 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 sur55 face of the wire 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 7Q 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 % of an inch in depth. Under the same stated conditions, and with the slice and wire arranged in accord75 ance with my invention, more than 90% 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 5 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 10 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 in- 15 vention 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 sup- 20 port 166 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 25 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 30 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 35 below a tangent extending between the upper peripheries of the breast roll 35 and the first supporting table roll 166. In fact, in the particular machine discussed, the wire runs uphill between the slice and the first table supporting roll and 40 does not begin to run downhill in the customary manner until it reaches the second or third table roll.

In the particular machine illustrated, the wire has about an inch of sag under the lip of the slice so that it is advisable to lose no time in elevating the slice 53 when the machine is running, if for any reason the stock supply fails or its pressure drops. This rapid raising is effected by an electric motor 81 through the slice _Kftcontrolling means heretofore referred to. Also, because of the fact that the outer margin of the wire is not subjected to pressure of the stock within the inlet, said margin would tend to extend in, a straight line between the breast _KSroll and the first table roll with resulting injury 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 «η m which 86 represents one οϊ the side plates secured to the slice 53 by screws 85, to which plate 86 there is secured a bolt 87 serving to compress a sponge rubber pad or block 88 under which is located a rubber shoe 92 which serves _rto 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, 87, 88 and 92 which are se- 70 cured 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. «

3,134,408

Although the stock inlet organized according to my invention may be very successfully operated with the distributing roll or cylinder 108, the fact that my invention may be practiced 5 with an extremely low stock consistency enables the stock inlet to be operated in certain cases without the distributing roll. _{χ Λ}

Such tests as I have made indicate that the invention is not restricted to any particular in10 clination of the nozzle plate 58. 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 15 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.

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 required or encountered In actual practice. Hence, 25 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.