US2329553A - Suction cylinder mold for papermaking machines - Google Patents

Description

Sept. 14; 1943'. M. ca. R. NEWBOULD 2,329,553

SUCTION CYLINDER MOLD FOR PAPER MAKING MACHINES Filed March 7, 194;

/j a 'Iwwi/ Patented Sept. 14, 1943 r sUo'rrori'o YL NnER Motn ro'rt :JMaurice George Itobert Newbouldrllondon, Eng;

AKING MACHINES land, assignorf-to PapercreteL-imited, London,: 1

England Thisin've ntion relates to, the production ot felted fibrous material in sheetform and more particularly felted cellulosic fibrous material of the character employed in forming paper, paper Pulp and the like. i

plying suction to a predetermined area 'ofthe 1 pulp whichis aspirated against the surface of the foraminous member, "the suction operating to remove water therefrom. K I

In known apparatus bfthfl above'kind' both a watersuction-chamber and an airsuction cham her are employed. The object of th water 'suc' tion chamber is to draw the fibre against the submerged outer surface of the foraminous mem-' ber where the fibre is retained to form the sheet, and the water that carried the-fibre is separated fromit by passing through the foraminous memberand subsequently out ofthe machine. The air suction chamber operates to withdrawthe water and consolidate the deposited material after it has passed the-water suction area, that is to say, when the'fibrous sheet has emerged from the stuii tank. Under normalconditions the sheet is required in as dry and consolidated a condition as possible, andthe twovmain essentials for the air suction chamber arethus time and the highest degree of suction obtainable. The water suction chamber, however, rarely works above a suction value of 25 cm. of mercury, for above this vacuum the increase in thickness of deposit is slow and not worth the pumping expense, while the texture of the sheet on its outer side is not satisfactory. Hence When using a common air and water suction chamberwhere the vacuum is equal for both forming and drying, the air drying portion is usually adversely controlled by the conditions obtaining in the water suction portion.

In general a coarse or fast stuff will build up rapidly and with a' low .water suction, whil a slow stuff builds "up slowly and by clogging the.

web and the foraminous member builds up a'high suction without producing proportions to increase in the thickness of the sheet. There is thus .3

maximum and probablyuneconomic thickness which can be produced by any particular stuff with existing construction of apparatus, which can-only-be governed by variationsin speed. The I invention is directed to the provision of means whereby 'the'limitation set by existing apparatus may be overcome. Y According to the invention; within the foreminous member there is provideda normally stationary member capable of adjustment by rota tion about the 'axisof rotation of the foraminous member'andoon'sisting of a segmentofa cylinder spaced a convenient distance from'th'e inne r-surface ofthe cylinder forming part of the'fo'raminous membenjfurnished with flanges presenting bearing surfaces to the interior of the foraminous member and constituting partitions dividingfthe spacebetween the segment and-the cylinder forming part of the foraminous memberinto convenient siz'ed compartments, one at least of which is connected to means foraspirating air through the material deposited on the foraminous mombe'r toflefie'ct its de watering and-that within the cylinder segmentthere is provided a hollow centralshaft from which a suction channel descends toa point closeto the inner surface ofthe foraminous "member, "Sl.10h iSUCtlOIl channel being designed to 'bjCOllIlBCtCd with apump adapted to cause the pulp in which the foraminous mem ber.{ is submerged to be sucked against the idramin'o'us member and thus become deposited thereon, the segment ofa cylinder being capable of rotation about the hollow central shaft to adjust the area of the foraminous memberwhich'is subjected to suction, to secure the deposition on it of the 'fibrouspulp, and to vary the area'of the deposited pulp to efiect'its-dewatering before being carried into the position where the de-watered' material willbe brought into position against a compartment 1i communicating with the atmosphere or a-seurce-er air pressure to assist in the removal ofthe deposited material-fromthe foraminous member. I The foraminous member may consist of a hol-, low cylinder suitably mounted uponend plates which constitute the bearings upon which it re .volveson an inner stationary member. The inner edge to produce corrugated sheeting, or other desired profiles. Holes are provided between the slots in the wall of the cylinder to enable the sieve to be submitted to the various conditions required and which are produced by the foraminous member revolving over the chambers of the stationary inner member.

The normally stationary member consists of a segment of a cylinder spaced at a convenient distance from the inner surface of the cylinder forrning part of .the foraminous member, and is flanged v der secured to end plates 2 and 2a formed with at its extremities to present a bearing surface/co trunnions 3 and 3a on the latter of which is the interior of the foraminous member. The annular chamber so formed is subdivided into three or, if desired, four convenientsized compartments by axial partitions extending to the inner side of the foraminous member.

This cylinder segment is mounted on a hollow central shaft from which a suction channel descends vertically until close to the inner surfaceof the foraminousmember. It is upon the hollow shaft that the bearings of the end plates of. the foraminous member rotate- These three compartments provided'bythe normally'stationary membentogether with the continuously revolving. foraminousmember, constitute the aspirating suction chamberwhich is submergedin the stuif supply tank, the air drying and consolidating chamber and the normal air pressure chamber. In some case a fourth chem-- bersuppli'ed with super pressureair is desirable, and this would be situated between the consolidating chamber and the normal air pressure chamber. I Th aspiration in. the suction chamber is. operated by a centrifugal pump or the like drawing the water in whichthe fibrous material was suspended through the sieve and thence out of the machine by way of the vertical suction. channel and the hollow central shaft. The web so formed is carried by the revolving foraminous. member out of the stuff tank and across the first axial partition, of the stationary member to the air dryingand-consolidating chamber that is main.- tained at a suitable sub-atmospheric pressure by means of a vacuum pump or the like. Evacuation of water which would accumulate in this chamber is effected by agravitational by-pass. pipe extending between the higher and the lower two extremities of the chamber and by arranging a suction pipe at'the bottom. of the lower extremity of the chamber. Continuing its rotation, thev foraminous member carrying its now partially dried web passesover the second partition of the stationary member to theatmospheric pressure chamber, where the web is carried away from the foraminous support to the consolidating rolls.

The third axial partition forms the-separator between the atmospheric pressure chamber. and the aspirating suction chamber- When varying causes, such as fragility of the webor excessive adhesion of the web to the. foraminous member, necessitate assistance for its removal, a small. super pressure chamber supplied with compressed air is introduced between the consolidating-and atmospheric pressure chambers.

For rotating the adjustable stationary member about the shaft in order to vary-the area to which suction is applied tothe immersed. portiion of the foraminous support, any suitable: means may be provided. Thus, for instance, aprodeeting part of the hollow shaftextending through the bearing. on. one of the end plates of therotating foraminous support may he, formed with a worm gear meshing with a worm on a spindle provided with a hand wheel.

The invention will be described further in detail and by way of example with reference to the accompanying drawing, in which:

Figure 1 is a view insectional elevation of a rotatable foraminous member on a plane contalning theaxis of rotation thereof, and

Figure 2 is a view in section on a plane at right angles to the plane of section of Figure 1.

In the drawing, l is a foraminous hollow cylinshown secured a toothed wheel 4 whereby it may be rotated.

About the cylinder and in slots in the end plates there. are arranged a plurality of strips 5 which 'ifunction as a support for a metal wire gauze 6.

These strips as may be seen are tapered axially to facilitate the tightening up of the metal wire gauze. The strips are interchangeable and may have straight exterior edges for the production of plain sheeting or corrugated exterior edges to produce corrugated sheeting.

Within the cylinder in question. there is provided an adjustable segmental cylinder comprising a member 1. constituting the peripheral walls thereof and end plates 8, 8a.

v The segmental cylinder is. at each end furnished with flanges 9 and 9a tov present a bearing surface to the interior of theforaminous cylinder and the generally annular chamber between the inner and outer cylinders is subdivided in effect into three compartments by radial partitions 10. The wall, however, of the inner cylinder is cut away at the position indicated by H.

This cylinder is. integral with hollow trunnions or stub shafts l2 and 12a and it is upon these that the trunnions of the outer foraminous member rotate. One of the trunnions or stub shafts of the segmental cylindrical member is furnished with a worm wheel 13 in engagement with a worm M by which it may be rotated within limits about its axis. in order that the area of. aspirated pulp subjected to suction beneath the body of the pulp may be varied as desired.

Secured within the inner chamber there is arranged a. tubular shaft l5 from which a suction channel It descends vertically, the end of it being brought close to the inner surface of the foraminous member, the tubular shaft being arranged in communication with a pump. 7 In order'to permit the escape of water from the suction space II intervening between twoadiacent radial partitions, whatever may be the posl-. tion into which the member I has been rotated relative to the channel N, there are provided av gravitational by-Dass pipe or pipes l8 extending from one side to the other of the air suction space which is in communication by way of the pipe l9v with the pipe '20. I

With the. above-described arrangement, if the foraminous support is revolved at a constant speed in a constant stuff, assuming that the water suction is constant, a sheet will be delivered of a constant thickness. For example, let it be sup-' posed that the sheet is 50% too thick, then by increasing the speed by 56% or more the right thickness will be secured, the drying time will be cut down, and delivery will be increased. If, on the other hand, the speed is left constant and the adjustable stationary member is displaced in the same direction as that in which the foraminous support revolves, for instance through an are representing 33 /3% or more of the length of the suction chamber, then the time of submersion in the stuff tank is reduced in the required proportion. With such an arrangement the end of the suction chamber remote from the first felting may be raised above the stuff level but no air leak can take place here on'account of the sheet formed on the revolving foraminous support when that portion was previously submerged. If desirable the stuff level may be reduced by a weir on the stuff tank although this is not essential.

Having now arranged to produce a wet web of the best economic thickness and at a constant speed, multiples of this thickness can be produced by a series of similar machines situated in line with, but higher and behind, each preceding machine, so that the web produced by each machine lies upon that produced by the preceding machine, thereby partially consolidating the webs together by suction.

Alternatively, with such a bank of machines all revolving at the same rate, an ultimate composite web could be produced of different thicknesses of diflerent or the same fibre by adjusting the individual aspirating suction chambers. In certain instances it may be desirable to employ a construction in which the previously mentioned adjustable stationary member consists of a permanently fixed vertical suction channel and hollow horizontal shaft, while the air drying and consolidating chamber, together with the atmospheric air pressure chamber, are constructed as a saddle member pivoting upon the fixed hollow shaft, the saddle being displaceable by means similar to those previously described. By maintaining the suction channel in the vertical position the minimum of dead water is left in the aspirating suction chamber. 1

The adjustment of the stationary member may be effected either when the machine is running or when it is stationary.

Similarly a reduction in the aspirating suction chamber may be effected by constructing the saddle member of two sections separated in the vertical axial plane by a mechanical device capable of widening or narrowing the space between them, and so altering the are subtending the suction area or by other like mechanical devices.

At this point it may be mentioned that so-called suction rollers have been used in connection with apparatus of the kind in which a web of fibrous pulp is deposited upon a flexible carrier the suction roller being employed for extracting water from the material so deposited, and that in apparatus of the general type to. which the invention relates, that is to say of the kind including a rotatable foraminous member adapted to be partially submerged in a body of fibrous pulp and, in association with the foraminous member, means for applying suction to apredetermined area of the pulp which is aspirated against the surface of the foraminous member, the suction operating to remove water therefrom, means has been provided for varying the area of a foraminous member actually immersed in or in contact with the body of fibrous pulp, and which is subjected to suction in order to cause the fibrous component to be deposited on the foraminous member.

I claim: Q

Apparatus for the production of felted fibrous material in sheet form comprising an outer hollow cylinder having a foraminous peripheral wall secured to end plates formed with hollow trunnions, a tubular shaft extending through one of said trunnions and terminating within a drum in a suction channel descending substantially downward, the open end of which suction channel is adjacent to the foraminous wall, the said tubular shaft being designed to be connected with a pump by which the liquid component of the fibrous pulp may be aspirated through the foraminous wall and the fibrous component of the pulp directly-deposited thereon, a segmental cylinder within the drum comprising a member constituting the peripheral walls thereof and flanges on the segmental cylinder at each end presenting a bearingsurface to the interior of the outer cylinder having a foraminous peripheral wall, partition members extending radially from the segmental cylinder to the foraminous peripheral wall of the hollow cylinder and dividing the space between the inner and outer cylinders into a plurality of chambers each of which is a segment of an annulus, trunnions on the end plate of the inner segmental cylinder rotatable within the hollow trunnions of the outer. cylinder and on the tubular shaft at one end and at the other end on a tubular member adapted to be connected to an air pump for securing a further extraction of water and thus the drying of the deposited fibrous material and furnished with at least one connection extending from it to one of the chambers between the outer cylinder and the inner segmental cylinder.

MAURICE GEORGE ROBERT NEWBOULD.

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