US2289430A

US2289430A - Papermaking machine

Info

Publication number: US2289430A
Application number: US78704A
Authority: US
Inventors: Irving C Jennings
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-05-08
Filing date: 1936-05-08
Publication date: 1942-07-14
Anticipated expiration: 1959-07-14

Description

July 14 1942- l. c. JENNINGs 2,289,430

. lAPER MAKING MACHINE Filed uy s, 195s s sheets-sheet 1 iii s@ 4 im Y i 'v 1 D22/azz t0: Xg) [as Fw/779 (TMW/755s, w

July 14,194?"v Y l. c. JENNeNGs 2,289,430.

- PAER MAKING MACHINE 4"Filed may a, 195s 3 seets-sneet 2 *LC-SMM Patented July 1.4, 1942 n UNITEDl PAPERMAKING MACHINE Irving C. Jennings, South Norwalk, Conn. Application May s, 1936, serial No. 78,704

`(ol. :i2- 53) 11 claims.

IThis invention relates to paper making machinery and more particularly to improved suction roll apparatus therefor.

'I'he suction roll as applied to paper machines comprises a perforated cylinder supported on bearings, and suitably driven, such cylinder being interposed inthe machine beneath the wet pulp, for the purpose of extracting moisture from the pulp. This is accomplished by providing a stationary box inside the roll and creating suction within the box whereby to draw air through the wet pulp, thereby extracting moisture, and drying the sheet yto increase its tensile strength suiciently to run on the felts and over to the steam heated driers. v

These suction rolls may be applied to the couch of Fourdriniermachmes `or used under the first and secondpresses, or on a board machine.

Prior art practice of paper makers required maintenance of a vacuum approximating ten inches of mercury in the interior of the suction roll box. As the speeds of paper machinery increased,`with developments in the art, it became necessaryy to raise the vacuum on the suction rolls, often as high aseighteen to twenty inches of vacuum being maintained. It is now being proposedto increase the vacuum on the'rolls to as high as twenty-five inches. It also was customary in the past to use a single box in the suction roll, later developments; however, including the installation in a few instances of dual-acting boxes. f

With the higher. vacuums has come a greatly increased problem of leakage, as obviously any air that leaks into a suction box has tobe expanded from atmosphereup to the final vacuum.

the amount of air carried in by the holes in the suction roll, and third, leakage between Vthe packing and the shell. So far as'known, no successful device, has heretofore been made to seal the packing, and an object of this invention is to provide adequate sealing of the suction box.

To this end the customary suction roll box is completely surrounded by an outer box, in

vwhich an intermediate vacuum is maintained. A

mediate vacuum in the outer box; or stated in other words, an absolute pressure of five incheson the inner box, and an absolute pressure of With this problem has come that of pump capacity limits. w

The required pump capacity for a twenty-five inch vacuum as against that for a twenty inch I 4vacuum would be in the ratio of the absolute pressures, or ten to five, thatk is the capacity of the vacuum pump will have to 'be twice as big to create and `maintain a twenty-five inch vacuum as would be the case for twenty inches. It will thus be seen that it' is very important to keep the leakage down to a minimum, especially whereI high vacuumsv are to be maintained, and a primary object ,f the present invention relates to an arrangement and means for effecting this purpose.

The air to be taken from the suction box, or suction roll; gets into the suction roll .box from vthree principal sources; first, the amount of air passing through the sheet or paper web; second,

ten inches on the outer b'ox.

The leakage past` the packing may be regarded as an orifc'ewhere a fluid is flowing from high pressure on one side to a low pressure on the other. The flow through such an orifice will be in proportion to the square root of the density, and to the square root of the difference of pressure between the two sides of the orifice, up to a ,critical ratio, which inf the case of a vacuum pump occurs at about fifteen or sixteen inches of vacuum.

If a single box were used, in the example given, where twenty-five inches is to be maintained, the leakage past the packing would be at a differential of twenty-five inches and the density would be that of atmosphere.4 But in the case of the double box, where twenty-five inches is maintained in the inner chamber and 'twenty inches in the outer or sealing chamber, the differential Aacross the inner chamber, will be from twenty to twenty-five inches, o r a differential of ve inches, and the density will be that of the twenty inch vacuum. Thus the comparative leakage will be,iirst, as the square root of the densities 30/10, or the square root of 3, and as the square root of 15/5, the ratio of the differential pressures, which in the case of the 4single box is taken at fifteen inches, as no more be possible in the case of highy vacuums in av single box, as heretofore known.

While double or two-stage boxes have been utilized, as above stated, to assist in the creation and maintenance of high vacuum. so far as is known, no one has yattempted to seal both sides of a suction box with an intermediate vacuum, and, accordingly, it is still another object of the present invention to supply such a seal, regardless ofthe number oflstages lused.

It may also be found more eicient to use twoo and 22.

stage pumping means, and the double box'makes staging commercially practical. another and very important object includesv a pumping arrangement in which the pumps are vstaged in such a manner that one pump may be used both for producing the intermediate vacuum in a low vacuum chamber, and as a second stage pump, for the hig'h vacuum chamber.-

To the attainment of the foregoing and other objects which will appear as the description proceeds, reference may be made to the accompanying sheets of drawings, ln which- Fig. 1 is a longitudinal section through the suction roll, taken on the line I-I of Fig. 3, and Jillustrating an arrangement of pumping equipment, with-certain elements removed for clarification;

Fig. 2 is an end elevation ofthe suction roll, partly in section on the line 2-2 of Fig. 1, with certain elements removed for clarication;

Fig. 3 is a cross section through the suction roll taken on,the line 3--3 of Fig. l, and showing the double sealed box, with certain elements removed for clarification;

Fig. 4 is a top plan view of the suction boxes, with the suction roll removed;

Fig. 5 is a section on the line 5'-5 of Fig. 4;

Fig. 6 is a section on the line 6-6 of Fig. 4; and

Fig. 'I is an enlarged fragmentary view of the upper left portion of Fig. 1 showing detail of end seal structure. 4

lReferring now to-the drawings, in which like reference-numerals designate like parts, the suction roll comprises the metal shell or drum I0, preferably of bronze, and perforated throughout,A as indicated at II. The drum may y be mounted in bearings I2 and driven by a suitable gearing I3 in a conventional manner. A wire or felt (not shown) in the form of an endless belt runs` on the drum I0, carrying the wet paper pulp web or board. Within the suction roll is mounted a stationary suction box I4, supported on suitable trunnions, and held in contact with the operating surfaceof the suction roll by springs I5, and the vacuum. The roll and box will, of

` course, be mounted `in the usual supporting frame IB.

Suitable packing strips I'I and I8 aid in reducing leakage between the suction roll I0 and Accordingly,

packing strips I8 to the other.

the interior of the box I4, and screws I9 provide an adjustment to prevent excessive wear on the packing strips. Adjustable plugs 20 may be provided as a means of accommodating the working surface of the box to the width of the paper web running through the machine.

The box I4 is divided into two chambers 2| The chamber 22V which surrounds the chamber 2|, is connected to a vacuum pump by a suitable pipe or conduit 24, and the pump 23 will serve tomaintain an intermediate vacuum, for example, of twenty inches, in the box 22.

vThe chamber 2l is connected to a vacuum pump 25 by a conduit 26, and this pump is operated to produce a considerably higher vacuum than pump 23, and will be eective to create and maintain, for example, twenty-ve inches of vacuum. The discharge of pump 25 may be either to atmosphere through

conduits

21 and 28, orinto the pipe orconduit 24 to the intake` of pump 23. Suitable controlling valves 2S and 30 may be regulated to determine the discharge. The pump 23 discharges to the atmosphere through an exhaustv conduit 3l, and may utilize y a separating tank 32, as show in Fig. 1, whereby the bulk of the liquid brought over from the sucl-A tion roll can be removed under a vacuum, either by a pump 33, or bya suitable water leg.

revolving suction roll carries the web of wet pulp, or partially formed paper on the Fourdrinier wires, or felts, over the chambers 2l and 22 in the suction box I4, and the vacuum in these chambers removes the water, and partially dries the. web, after which the web passes over to the driers. With the double box as described, it is possible to carry a higher vacuum than heretofore. The paper is subjected to av longer contact and greater air pressure' than would be possible with a single box. This makes a. harder, drier sheet, which will be .less liable to break. The paper machine can be run faster, and less steam will be required for drying.

Smaller pumping equipment can lbe used, due

to the dual vacuum conditions within the roll, with attendant minimum leakage, and the pumping mechanism can'be staged,- utilizing the pump 23 to produce the vacuum in the chamber 22 and as a second stage pump for the' high vacuum pump 25. l

It is quite clear from the foregoing that the primary purpose of the invention is to seal the main suction box against leakage at all points where same might occur, regardless of whether there be one, two, or more of such points, and to do this by vacuum means. Since the points may be different with different structures, and may l vary in number as well as location, it will be evident that many variations and modifications in structure effective to produce the desired result will readily occur to thoseskilled in the art.

For example, if it is desired to seal the ends of the chamber 2I by vacuum from within the chamber 22, the adjustable plugs 20 may be cut away to provide channels or recesses 36 (Figs. 4, 5 and 6), and tapped or formed with conduits 31 extending from one side of the respective Obviously then, any leakage past the packing strips I1 into the recess or cut-out channel 36 will be carried into the region of` lower vacuum in the chamber 22, thus sealing the main chamber 2|.

as limiting except as defined in the appended claims.

I claim:

1. A suction box for the suction roll of a paper making machine comprising a chamber effective to maintain a predetermined vvacuum on the roll,

and means to seal said chamber against leakage comprising a second- `chamber surrounding said rst chamber and effective to maintain andplace a sealing. vacuum 4for said ilrst chamber on the roll independently of said first chamber. and means for independently creating a vacuum Iwithin each of said chambers.

2. A suction box for the suction roll of a paper making machine comprising a chamber eiiective to maintain a predetermined vacuum on the roll, and means to seal said chamber against leakage comprising a second chamber surrounding said iirst chamber and eiTective to maintain and place a sealing vacuum for said rst chamber on the roll independently of said first chamber. means to create a vacuum of predetermined degree in said rst chamber, and means to create a vacuum of a diii'erent predetermined degree in said second chamber.

3. A suction box for the suction roll of a paper making machine comprising a. chamber eiTective to maintain a predetermined vacuum on the roll, and a second chamber surrounding said ilrst chamber and eiective to maintain and place a vacuum on the roll independently of said first chamber, means to create a vacuum or predetermined degree-in -said ilrst chamber, Vmeans to create'a vacuum of a dinerent predetermined degree in said second chamber, and selective means to operatively `connect said vacuum creatpumping means whereby one of said pumping means in addition to its normal operation will supplement the pumping action of the other of said pumping means.

6. The combination'with a suction roll, of a suction box having a low vacuum chamber and a high vacuum chamber, each eiective to maintain and place a vacuum on the roll, independently ofv the other a pump for creating and maintaining a vacuum in said high vacuum chamber, and a second pump for producing a lower vacuum in the low vacuum chamber, said low vacuum chamber being so positioned relative to said high vacuum .chamber as to seal said vacuum chamber at all points of leakage. .i

'7. The combination with a suction roll, of a suction box having a low vacuum chamber and a high vacuum chamber, each effective to maintain and place a vacuum on the roll, independently of the'other a pump for creating and `maintaining a vacuum in said high vacuum chamber, and means to seal said high vacuum chamber at all points of y leakage including a second pump for producing a lower, sealing vacuum in the low vacuum chamber, said second, pump being connected to said iirst pump as a second stage pump therefor.

8. In a paper making machine, the combination with a. suction roll, of a suction box effective ,to maintain a vacuum on that .portion of the roll over which the paper web passes, and a second suction box independent of said tlrst suction box and disposed relative to said nrst box as to seal said rst suction box at all points of leakage, and

'e separate means to exhaust said suction boxes independently of each other. 9. In a paper making machine, the combination with a suction roll, of a suction box effective to maintain a vacuum on that portion oi the roll ing means together, whereby said second vacuum creating 'means will operate as asecond stage to said first vacuum creating means.

4. In a paper making machine, the combination of a suction roll, a double suction box therefor comprising two separated, non-communicating chambers each communicating independently with said roll, pumping means connected to one of said chambersand effective to produce and .maintain a vacuum therein, a second pump- Aing means connected to said second chamber and over which the paper web passes', and a second suction box independent of said iirst suction box and disposed relative to said rst box as to seal said nrst suction box at all points of leakage, and means to maintain a lesser degree of vacuum in said second suction box than that maintained inv the first suction box, independently of said ilrst suction box.

10. A suction box for the suction roll of a paper .making machine comprising a chamber effective f a sealing vacuum for said ilrst chamber on the roll independently .of said rst chamber, means to create a vacuum of predetermined degree in -said ilrsi.v chamber, means to create a vacuum ota different predeterminedl degree in said second chamber, and selective means to operatively con- .nect said vacuum creating means together,

for comprising two separated, non-communicating chambers each communicating independently with said roll, pumping means connected to one of'said chambers and en'ective to produce and maintain a vacuum therein, a second pumping means connected to said second chamber and effective independently to produce and maintain a vacuum therein, said `chambers being so ,disposed relative to each other that the vacuum in one of saidchambers will seal ,the other atall points of leakage and means to interconnect said whereby said second vacuum creating means will operate as a second stage to said ilrst vacuum creating means.

11. The method of sealing the suction box of a suction roll in a paper making machine against leakage, which comprises creating and maintaining a vacuum of lesser degree than that' within said suction box, independently and separately of the vacuum within said suction box, applying the vacuum so produced to all points oi.' leakage ex- Ateriorly of said box, and maintaining relative incommunicativeness between said vacuums.

IRVING C. JENNINGS.