US1751959A - Flow box for paper machines - Google Patents

Description

March 25, 1930. E. .1. TRIMBEY ET AL FLOW BOX FOR PAPER MACHINES Filed May l5, 1929 M @Mw if m Mm w n Y., BM 0f Patented. Mar. 2.5, 1930 UNITED STATES PATENT 4OFFICE EDWARD J. TRIMBEY ANZI)V GEORGE K. WALKER, OE GLENS FALLS, NEW YORK FLOW BOX FOR PAPER MACHINES Application led May 15,

This invention has to do with improvements in means for securing uniformity of iow as the liquid paper-making material flows out onto the moving wire of a Fourdrinier paper machine.

In the early days of paper making when the output of paper machines was relatively small it was comparatively easy to secure a smooth .even distribution of the flow of thin liquid pulp as it went to the paper machine wire due to the fact that the width of the wire was only a few feet and the volume of liquid to be distributed was small. With the increase in the width of the wires and the volumes of liquid pulp handled this became more of a problem and from time to time improvements were made in the design of head boxes containing various arrangements of baffles,

dams with openings cut through them, small revolving paddle wheels entirely submerged in the liquid, perforated revolving cylinders entirely submerged in the liquid, etc.

At the present time the accepted practice is to make use of a large rectangular head box whose width is approximately that of the wire and whose length and depth are from one third to two thirds the width. In these head boxes are generally located from three to five vertical baiiies or partitions extending alternately from the top to Within a short distance of the bottom and from the bottom to approximately the level of the breast roll or apron, thus introducing many square feet of surface for the accumulation of slime which sooneror later becomes loosened and, passing over the wire and presses, adheres to the press rolls or felts and causes frequent breaks of the sheet with consequent loss of production and deterioration of quality.

As mentioned before the purpose of these baiiies, etc. is to insure a smooth even flow of the liquid onto the wire so that the resulting sheet of paper will be of uniform thickness and will be uniformly dried. O-n accountof the high speeds employed, however, and the "per inch of Width 1929. Serial No. 363,120.

large volumes of liquid pulp handled, the flow is not uniform at all times across the entire width of the wire; cross currents and eddies are formed, and at a given instant there will be considerably more pulp passing out at one point on the Wire than at adjacent points, while afew seconds later these currents will have changed and likewise the uniformity and thickness of the sheet of paper being produced.

The object of the present invention is to overcome these difficulties and obtain a more uniform flow of pulp onto the wire with a resulting improvement in the quality of the paper produced. In attaining this object we very greatly reduce the area of surface in contact with the liquid pulp as it flows from the screens to the breast roll of the paper machine by substituting for the long and deep rectangular head box, with its several baffles or partitions, a short shallow spout containing a revoluble blade-carrying member extending horizontally across they width of the spout. The blades or plates o f'this member dip successively into the flowing pulp as they are moved forward by the pulp stream and in their passage extend across the path of flow. This at once eliminates the greater portion of the slime accumulating surface, and reduces the number of breaks with consequent increase in production and quality; at the same time it completely eliminates cross currents and eddies and allows the liquid pulp to flow out from .the slice hand onto the wire evenly and uniformly. distributed, thus further improving the quality of the paper and the safe running of -the machine.

In the accompanying drawings 1n wlnch we have illustrated a preferred embodiment of our invention, Figure l is a vertical section through the spout and wheel of the present invention, taken along the line of flow; and Figure 2 is a section taken along line 2-2 of Figure 1.

In these drawings 1 represents the short shallow flow box or spout located between the screens and the breast roll 2 and terminating adjacent the wire in a slice 3. In this spout is located a paddle wheel 4, mounted in suitable bearings 5, which are open at the top for the ready removal of the paddle wheel. This wheel consists o f a bronze or other suitable noncorrosive shaft 6 carrying spiders 7 to Which are attached arms 8 carrying radial blades or plates 9 of thin metal. Attached to the outer edge of these plates 9 are flexible rubber'st-rips 10. The bearings are bolted to the sides of the flow box or spout l at such a height that the outer edges of the flexible strips 10 just clear or drag slightly over the bottom of the spout. At a point directly beneath the bearings the bottom of the box is made in the form of a cylindrical section 11 concentric with the wheel, the chord of which is equal to or slightly greater than the chord across the tips of two adjacent blades as extended by the addition of the strips l0. Since the blades 9 extend entirely across the spout 1 and their width is such that they extend at least as high as the surface of the flowing stream of liquid pulp it is evident that except for a relatively small amount of leakage, the liquid pulp from the screens can pass to the slice and breast roll only as the paddle wheel revolves, and since the paddle wheel` is of light construction and freely mounted in the bearings the pressure of the flowing current will cause it to revolve at such a rate as to cause no objectionable hindrance to the flow of the liquid pulp. At the same time it is plainly evident that a swiftly moving current at one point across the width of the spout cannot pass directly to the slice but is held back by the blades 9, its energy distributed to the neighboring particles; andas the wheel revolves there is transferred from one end of the spout to the other a sectoral volume of liquid from which all cross currents have been completely smoothed out and eliminated. This liquid will then pass out quietly and uniformly from beneath the slice onto the moving wire and a uniform sheet of paper will be produced.

By the use of the cylindrical section 11, or

by lowering the center of the shaft to a point where the flexible strips 10 will bend and draw over the flat bottom surface, it follows that one of the blades is always in position to prevent the free flow of the disturbing currents; one blade and its flexible tip moving into position in conjunction with the vsection 11 or the bottom of the spout, before the preceding tip ceases to register.

As illustrated in Figure l the flexible strips 8 bend due totheir own weight so that as they leave the surface of the flowing stream of liquid pulp they are substantially normal to the surface, thus preventing the setting up of any wave or disturbance due to the emergence of the blades from the liquid. l -In the prising a plurality of plates movable in sucl cession across the path of the flowing pulp by the movement of the pulp itself.

2. A flow box for paper machines comprising a plurality of plates movable in succession across the path of the flowing pulp by the movement of the pulp ritself, the spacing between the plates being such that any given plate contacts with the bottom of the box before thenext preceding plate moves out of contact. j

3. In a flow box for paper machines the combination of a rotatable member extendin across the box, radial plates of a width equa to at least the depth of t-he pulp in the box carried by said member, and movable into and out of the pulp by the movement of the pulp stream.

4. In a flow box for paper machines the combination of a rotatable paddle wheel extending across the box transversely of the path of flow and journaled above the pulp level, radial plates of a width equal to at least the depth of thepulp in the box carried by the paddle wheel and contacting in succession with the bottom of the box as the wheel is rotated.Y

5. In a flow box for paper machines the combination of a rotatable paddle wheel extending across the box transversely of the path of flow and journaled above the pulp level, radial plates of a width equal to at least the depth of the pulpin the box carried by the paddle wheel and flexible edges on said plates the spacing between the plates being such that the flexible edge of any given plate contacts with the bottom of the box before the edge of the next preceding plate moves vided with plates which successively pass through the pulp stream as the wheel rotates, and a cylindrical section in the bottom of the box concentricwithand below the wheel and of such dimensions that as the wheel rotates, each plate contacts with the cylindricalsection before the next preceding plate moves out of contact therewith.

8. Means for eliminating cross currents...

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