US 3357881 A
Description (OCR text may contain errors)
Dec. 12, 1967 w. N. BENNETT 3,357,881
WIRE SUPPORT FOR PAPERMAKING MACHINES Filed Oct. 15, 1964 WZZzdm l ffierzrz 'zf 3 M? W United States Patent 3,357,881 WIRE SUPPORT FOR PAPERMAKING MACHINES William N. Bennett, Fitchburg, Mass., assignor to Fitchburg Paper Company, Fitchburg, Mass., a corporation of Delaware Filed Oct. 15, 1964, Ser. No. 404,141
6 Claims. (Cl. 162-354) This invention relates to new and improved methods and devices for the supporting of the wire (and the apron) in papermaking machines and furthermore relates to table rolls, foils, aprons, and similar devices. The principal object of the invention resides in the provision of means for holding the apron and the wire accurately level, particularly adjacent the breast roll, and for keeping the wire horizontal as it travels through the papermaking machine and until the paper is formed.
It has been found that regardless of how the apron and wire are mounted or suspended, due to gravity, they bow downwardly slightly towards the center, thus making a thicker paper formation in the center area and a thinner paper formation near the deckle. Table rolls and foils supporting the wire areused but the trouble is that the rolls and the foils themselves tend to sag centrally because of the fact. that all of these devices must be supported from the ends thereof at the sides of the machine. Papermaking machines clearly lack a positive supporting means for maintaining the parts at an accurate level to produce a uniform paper formation. It should be clear that even a very slight variation from a true horizontal level will affect the stock while still in a flu-id state. This obviously adversely affects the paper formation and the paper thus formed is thicker in the center of the web than at the edges thereof.
Even if the pulp can be applied to the wire in a completely horizontal, even, uniform layer across the machine, since the stock has a high percentage of water, it is quite clear that the water is going to tend to move downhill, i.e., toward'the lowermost part, or sag in the middle of the wire and it is the general purpose of this invention to obviate this sag so that an even, uniform layer of stock can be applied to the wire, and so that this even and uniform layer of stock can be carried along on the wire to the point of formation of the paper.
Another object of the invention resides in the provision of a new and improved foil or table surface material which, in combination with the passing wire, provides automatically for a vibration of the wire and consequently improved paper formation. This surface material comprises a composite material preferably including a long wearing, relatively smooth top layer over which the wire passes and is in contact therewith, and a contiguous underlayer of yielding, resilient material, preferably in the form of expanded cellular latex or plastic material. It has been found that this imparts an automatic or built-in vibratory action to the wire that increases the movement of the water from the stock while still adequately supporting the wire and improving the uniformity of the paper formation.
Other objects and advantages of the invention will appear hereinafter.
Reference is to be had to the accompanying drawings in which:
FIG. 1 is a diagram illustrating the sagging wire in the usual papermaking machine and emphasizing the problem involved;
FIG. 2 is a view in elevation, taken transversely of the machine, and with means for measuring the deflection thereof across the machine, and means for overcoming this deflection, the wire being shown in section;
Patented Dec. 12, 1967 FIG. 3 is a view in elevation on an enlarged scale, taken on line 3-3 in FIG. 2;
FIG. 4 is a view similar to FIG. 2 but illustrating a table roll supported at points along its length for proper adjustment thereof;
FIG. 5 is a view in elevation taken on line 5-5 in FIG. 4; and
. FIG. 6 is an enlarged cross sectional view showing the construction of the material which the present invention utilizes to provide for the vibration of the wire.
Regardless of the strength or heaviness of a support, the fact is that if it is supported only at its ends, it sags somewhat in the central area thereof. In making paper which is a few thousandths inch thick, it will be appreciated that but a very slight sag is needed in the central area of the paper forming wire to considerably increase the thickness of the paper from the deckle to the center of the web. This is illustrated in FIG. 1 wherein the line at 10 indicates a hypothetical perfectly horizontal Fourdrinier wire or the like. Unfortunately this wire must be supported by rolls or foils in turn supported only at the ends thereof as is indicated by the arrows at 12. This therefore provides an unavoidable sag 14 generally in the central area of the wire, in which case the fluid paper pulp stock tends to flow toward the center, as at 16, thus making the paper formation thick in the center and gradually thinner out toward the edges of the web.
Many devices have been utilized to try to compensate for this including the use of crown rolls or the like but none of thesedevices really obviate the unevenness of the paper, and the only solution would appear therefore to be to provide that the Fourdrinier wire as shown at 10 should be kept level so that the optimum uniformity of thickness of paper stock as at 18 can be maintained.
The invention therefore contemplates the use of any kind of support as for instance the kind of foil which is illustrated at 20 and which is usually provided with a curved convex upper edge as shown in order to suctionally remove water from the pulp at its trailing edge. This foil may take many different forms and may have a support such as the upright transverse supporting member 24 shown.
This support and also the foil sag in the center as shown in FIG. 1 because of the necessary outboard supports for the foil, and in order to counteract this sag it is necessary to measure it. For this reason there are provided outboard supports 26, a cross beam 28, and a series of dial indicators 30, 30, as many as may be needed, and extending across the machine contacting the lower edge of the upright member 20 at 32, in order that the deviation at any reasonably spaced point across the machine shall be ascertained. It does not matter that the support 28 itself may sag as a clear horizontal measurement may be taken by the dial indicators which are then placed on zero, so that any deviation from zero is easily seen and the degree or measurement of the sag is thereby determined.
Of course the dial indicators may be provided with remote control dials, not shown, so that the operator of the machine may read the same at the side of the machine.
Either another cross support or the same beam or other support 28 may serve to mount means for creating pressure at the underside of the foil. Cam means may be used or hydraulic cylinders 34 with rams or some other means. These means are all conveniently remote controlled by conventional means at the sides of the machine, so that all that is necessary for the operator to do is to determine the deviation of the foil and to apply such pressure thereto at spaced points, which will cause the dial indi- 0 cators to return to the zero reading, at which time it is 3 held accurately level. As many foils as needed may be installed along the wire, indicated at 36.
FIGS. 4 and 5 show a similar device applied to a table roll at 40. In this case the roll 40 can be held in yoke bearings 42 mounted on any kind of support desired such as beam 38 supported at its ends as at 46, 46. Dial indicators 30 and hydraulic or other means at 34 for returning the dial indicators to the zero position may be used generally as before.
It has been found that it is not only the weight of the rolls or foils, wire, etc. that causes the same to sag, but even variations in liquid depths from one grade of stock to another or changes in the process of producing a web of paper in attempting to get a basis weight or formation of a particular kind, result in unevennesses. The effect of course is exaggerated when flowing liquid over a concave surface, because the weight of the liquid naturally seeks the center of the wire by means of the currents in flow as well as the weight. These irregularities are obviated by the present invention.
In order to provide for an improved suction by the rolls or foils, it has been found that a slight vibratory act-ion applied to the wire accomplishes this and accelerates the paper formation. This vibratory action can be built into the rolls or foils while still maintaining smooth surfaces thereon by the use of a novel covering material shown in section in FIG. 6. This material comprises a relatively hard, smooth, long-wearing wire contact outer layer or skin at 48 and an underlayer of spongy material 50. These layers are preferably secured together and cause the elements of the Fourdrinier wire to vibrate slightly as it passes over this material in contact therewith. This is due to the fact that a slight indentation is momentarily applied by the wire elements to the layer 48, as layer 50 can be depressed, but this immediately snaps back and impinges on the succeeding wire elements, vibrating the wire as a whole. It is believed clear that this vibration will help the passage of water through the wire and help to shorten the period needed for the formation of the paper.
The skin or outer layer 48 is conveniently of nylon, Teflon, or similar plastic, while the layer 50 is preferably made of expanded cellular latex or soft cellular plastic.
Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:
1. A papermaking machine: comprising (a) a Fourdrinier wire;
(b) an elongated wire supporting means extending across and under said Fourdrinier wire to support same;
(c) support means for supporting said wire supporting means at the ends thereof;
(d) pressure applying means coacting with the underside of said wire supporting means for exerting pressure thereupon to move the central portion of said wire supporting means to a substantially full level condition to thus counteract any sags in said Fourdrinier wire; and
(e) sag indicating means for indicating the degree of sag in said Fourdrinier wire when said Fourdrinier wire sags.
2. The papermaking machine of claim 1: wherein said wire supporting means comprises a foil.
3. The papermaking machine of claim 1: wherein said wire supporting means comprises a table roll.
4. The papermaking machine of claim 1: wherein said sag indicating means comprises dial means supported for coaction with said wire supporting means and responsive to movement thereof from a level condition.
5. The papermaking machine of claim 4: wherein said dial means includes a plurality of individual dial indicators disposed for cooperation with said wire supporting means at selected locations along the length thereof and responsive to movement of a selected area from the horizontal.
6. The papermaking machine of claim 1: wherein said pressure applying means includes a plurality of pressure elements disposed at locations spaced along the length of said wire supporting means to exert pressure at said locations.
References Cited UNITED STATES PATENTS 1,691,336 11/1928 Casto.
1,939,948 12/1933 Berlow 29-130 2,111,833 3/1938 Berry 162-354X 2,263,285 11/1941 Bolog 29l30 X 3,201,308 8/1965 Goddard et a1 162--352 3,105,789 10/1963 Goddard l62352 S. LEON BASHORE, Primary Examiner.
DONALL H. SYLVESTER, Examiner.
J. H. NEWSOME, Assistant Examiner.