US 1864580 A
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Description (OCR text may contain errors)
June 28, 1932.
R. E. BRAWN 1,864,580
METHOD OF MAKING FIBER WEBS AND WET MACHINE THEREFOR Filed June 6, 1931 haw 72 757 @yJ/i (ZMJWZ weight on the forming wire.
Patented June 28, 1932 v UNITED STATES PATENT OFFICE BOY E. DRAW O1? BERLIN, NEW HAMPSHIRE, ASSIGNOB T0 BROWN GOD-ANY, 0F
BERLIN, NEW HAMPSHIRE, A CORPORATION 01? MAINE METHOD OF IAKING FIBER WEIBS AN D WET-MACNINE THEREFOR Application filed June 6, 1931. Serial No. 542,610.
This invention relates to a method of forming fiber webs from aqueous pulp suspensions and to a so-called wet-machine intended for handling the aqueous pulp suspensions and made up in its specific form, of a pulp vat operating in combination with a suction roll and an endless wire cloth passing about the roll and retaining pulp fibers from the aqueous suspension while water is passing into the roll.
In making narrow webs or ribbons of pulp such as are to be furled and compacted in damp condition into rovings, it is important to have the pulp ribbons of uniform texture or formation, in order to realize rovings of substantially invariable quality, including cross section, tensile strength, softness, etc., throughout their lengths. My invention affords a combination of instrumentalities, including a pulp vat, devised to effect a deposition of pulp fibers, such as wood pulp from aqueous suspension onto an endless traveling wire cloth in a state of formation or interfelted structure amenable to furling and compacting into high grade rovings such as are suitable for twisting and plying into yarns and twines. The pulp vat which I employ is constructed to handle an excess ofhighl v dilute aqueous pulp suspension,-far more than is actually necessary for depositing ribbons of pulp of the desired thickness and This excess avoids any tendency for fiber clumps or aggregates to deposit on the forming wire, and further eliminates as much as possible localized increase in pulp concentration even at the region where the pulp supply comes into contact with the forming wire and where water is being constantly removed therefrom. Highly important. too, is the fact that the approach of the dilute pulp suspension from my vat to the forming wire is such as to create eddies at the web-forming localities. lVhen the ribbons are made at high speed, there is a decided tendency for the fibers, as in the case of any high-speed cylinder mould, to arran e themselves so as to lie largely in the direction of the travel of the forming wire. With a static condition prevailing at the webforming localities, splits frequently result in the case of the ribbons, lengthwise of theribbons, because of the lack of sufficient crosslying fibers to give the necessary interfelt- 'ing. These splits result in frayed ends when the ribbons are furled, one end of a split generally breaking off to give two rovings, m-
stead of one; By creating an eddy atthe Web-forming localities so as to throw sufficient of the fibers in the across-direction of the forming wire, the foregoing difitculties are obviate With the foregoing and other features and objects in view, my invention will now be described in conjunction with the accompanying drawing, wherein Figure 1 represents a plan view of a machine embodying my invention.
Figure 2 is a side view, partly in section, of the machine.
While not limited thereto, my invention will be described where it has been found to have a most useful application, namely, in a machine for making 'pulp ribbons to be furled and compacted in damp condition into rovings. The complete machine is shown and described in application Ser. No. 542,649, filed June 6, 1931, by Milton 0. Schur and William B. Meglitz, but I have illustrated andshall describe that portion of the machine constituting my invention. As shown, the machine includes generally a suction roll 1. an endless wire cloth 2 passing tightly about the roll, and a pulp-vat- 3 supplying.
aqueous pulp suspension to the wire cloth. The roll shown in Figure 1 has a solid peripheral wall in which spaced peripheral grooves 4 are formed, with apertures 5 through their bottoms so as to communicate with the roll hollow and thus to permit the deposition of pulp fibers as spaced, con- .tinuous ribbons when an aqueous pulp suspension is run onto the roll from the vat 3. It is, of course, possible to use another type of suction roll Whose periphery permits water to pass over spaced peripheral zones thereinto. The vat is made up of a bottom 6 and sidewalls 7 whose front edges terminate in close proximity to the roll periphery so as to direct a flow of the pulp suspension onto the wire, the. front edges 7 a of the side walls bein of an arcuate shape to conform to that portlon of theroll periphery presented thereto. The roll proper is' supported near its ends in suitable bearings afforded by brackets 8, and is rotated by suitable means (not shown), thereby serving to propel the wire in the direction indicated by arrow. The vat receives a supply of pulp suspension of suitable consistency from a pipe 9 entering the vat-bottom 6 at a point somewhat removed from the rear wall 10. The pulp suspension flows under a baflie plate or false bottom 11 provided with a downwardly projecting rear wall or dam portion 12 forming a chamber to receive the pulp suspension and acting to confine the flow frontwardly. The pulp sus pension flows onto thew-ire and the water passes through the wire into the roll only over those areas or zones in back of the spaced peripheral grooves 4, as a result of which spaced ribbons of pulp are progressively deposited on the wire. In order that a uniformly textured deposit of pulp be made, a large excess of highly dilute pulp suspension is delivered into the vat, this excess taking the course indicated past the clearance or throat space 13 between the baflle and the roll, and thence over the baflie and dam to the rear of the vat in back of the dam. The excess pulp suspension may leave the vat through a pipe 14 entering into the bottom of the vat near its rear wall and discharging into a supply tank 15, which is constantly being -charged with pulp suspension of the proper consistency. The supply tank 15 may be one from which thepulp suspension is drawn bya variable speed pump 16 and fed through the supply pipe 9 into the vat. The clearance 13 between the bafile and the roll may be varied as by constructing the bafiie in two pieces, .as shown, with the front piece 17 being longitudinally adjustable on the rear piece 11. The front piece may overlap and be normally fixed to the rear piece by bolts 18 passing through longitudinal slots 19 in the front piece and fixed to the rear piece, a loosenin of the bolts permitting the front piece to e shifted frontwardly or rearwardly as desired. The head of suspension in the vat may be controlled as by a vertically adustable gate 20 arranged above the bafiie 11 and immediately in front of the dam 12. The adjustment may be made as by a pair of hand-wheels 21 outside of the vat, each of Wl'llCll is fixed to a vertical screw shaft 22 chamber 24: occupying a sector somewhat greater than the periphery portion of the roll in'contact with the pulp suspension, may be arranged inside of the roll so as to accelerate withdrawal of the water from the pulp suspension and thus to promote the formation of pulp ribbons on the wire. The wire carrying the pulp ribbons out of the pulp suspension may then pass over a smaller second suction chamber 25 adjacent to the chamber 24. In depositing on the wire, the pulp fibers assume a preponderantly longitudinal lay, particularly when the wire is traveling at such speeds as 500 feet per minute, or greater. A certain amount of cross-laying and random-laying of the fibers inevitably the adjustment of the movable plate 17 so as to throw a sufiicient proportion of the fibers in the across-direction of the wire to eliminate splitting without undue loss of strength in the machine direction. In this connection, it is to be observed that a paper web made on a cylinder mould is always characterized by a very marked difierence in physical characteristics in the machine direction, so called, and in the across-direction. This kind of lack of homogeneity is of advantage and is availed of in making pulp ribbons to be fur-led into rovings, but, in accordance with my invention, it is not carried to such a point where there are insufiicient fibers lying in the across-direction to hold the ribbons together. and to give rise to frayed ends during the subsequent furling operation.
The wire carrying deposits of pulp rib- I bons .proceeds horizontally from the roll 1 over the desired number of suction boxes 26 maintained under sufficient suction to dewater the ribbons to a water content of about 250% to 300%, more or less, based on the weight of fiber, as at this water content the ribbons are amenable to ready furling and subsequent accumulation of the rovings does not enter into my invention, it is unessential an aqueous pulp suspension may pass, such,
for example, as a so-called cylinder papermaking machine, in which a so-called cylinder mould serves as the instrumentality on which a continuous web of pulp is deposited and from which the web is picked up by a carrier belt. As already observed, however, its most" useful application, so far as I am aware, resides in the combination of instrumentalities described, wherein an endless wire serves as the forming means on which uniformly textured pulp ribbons are deposited, the pulp ribbons being partially dewatered on the wire to the desired water content without the use of pressure devices such as would disrupt or destroy the uniform interfelting previously attained.
The improved method which is practised with my machine, but which might be practised with other machines, consists generical- -ly in forming a continuous pulp, web on a traveling endless wire cloth, a portion of which constitutes a pulp-depositing station, by progressively flowing an excess of aqueous pulp suspension into contact with that por-' tion of the wire cloth under conditions to create eddies at the region where the pulp fibers are being deposited on the cloth while progressively directing the excess pulp sus pension away from that portion. More specifically, my improved method is practised with a travelingendless wire cloth, the pulpdepositing station or portion of which is operated in combination with a suction roll through the periphery of-which water may pass over spaced parallel zones so as to permit pulp ribbons or narrow webs to be deposited progressively on the cloth.
What I claim is:
1.v The combination with a roll through the periphery of which water from an aqueous pulp suspension may pass, of a pulp-vat having a bottom and side walls terminating in close proximity to the periphery of said roll,
5 false bottom arranged above said vat-bottom and having a rear dam portion removed from the rear wall of said vat and a front edge spaced sufliciently from the periphery ,of said roll to permit excess pulp suspension pass over spaced peripheral zones and an endless cloth traveling over said roll and on which pulp may be deposited from aqueous suspension, of a pulp-vat having a bottom and side walls terminating in close proximity to the periphery of said roll, a false bottom arranged above said vat-bottom and having a rear dam portion somewhat removed from the rear wall of said vat and a front edge spaced sufliciently from the periphery of said roll to permit excess pulp suspension to flow freely thereover and thence in back of said dam, means for supplying excess aqueous pulp suspension into said vat under said false bottom, and means for removing the excess pulp suspension in back of said dam.
3. In the production of a continuous pulp web on a traveling endless wire cloth a portion of which. constitutes a pulp-depositing station, that improvement which consists in progressively flowing an excess of an aqueous pulp suspension into contact with said portion under conditions to create eddies at the region where the pulp fibers deposit on the cloth while progressively directing said excess away from said portion.
4. In the. production of continuous pulp ribbons on a traveling endless wire cloth a portion of which passes over a suction roll through the periphery of which water may pass over spaced peripheral zones to permit said ribbons to be deposited on said portion from aqueous suspension, that improvement which consists in progressively flowing an.
excess of the aqueous pulp suspension into contact with said portion under conditions to create eddies at the localities where the pulp fibers deposit on the cloth while progressively directing said excess away from said portionl 5. The combination with a roll through the periphery of which water from an aqueous pulp suspension may pass off a pulp-vat having a bottom and side walls terminating in close proximity to the periphery of said roll, a false bottom arranged above said vat-bottom and having a rear wall to form a chamber to receive pulp suspension and a front edge spaced sufliciently from the periphery of said roll to permit excess pulp suspension to flow freely and rearwardly thereover, means for supplying'excess aqueous pulp suspension into said chamber undersaid false bottom, and means for removing the excess pulp suspension flowing rearwardly over said false bottom. 6. The combination with a suction roll through the periphery of which water may pass over spaced peripheral zones and an endless cloth traveling over said roll and on which pulp may be deposited from aqueous suspension, of a pulp-vat having a bottom and side walls terminating in close proximity to the periphery of said roll, a false bottom arranged above said vat-bottom and having a rear wall to form a chamber to receive pulp susprension' and'a front edge spaced suflicient- 1y om the periphery of said roll-to permit excess pulp suspension to flow freely and rearwardly thereovemmeans'for supplying excess aqueous pulp suspension mto said chamber under' said faIse bottom, and means for removing the excess pulp suspension flowing rearwardly over said false bottom.
In testimony whereof I have aflixed my signature. I v