US2148613A - Head box for fourdrinier machines - Google Patents

Description

1939- o. w. FROST 2,148,513

HEAD BOX FOR FOURDRINIER MACHINES Filed March 23, 1936 Patented Feb. 28, 1939 A UNITED STATES PATENT OFFICE 2,148,613 HEAD BOX FOR- FOURDRINIER MACHINES Orcutt W. Frost, Cloquet, Minn., assignor to Wood Conversion Company, Cloquet, Minn., a corporation of Delaware Application March 23, .1936, Serial No. 70,332

2 Claims.

The present invention relates'to a head-box construction for low-speed Fourdrinier machines.

There are numerous types of head-box constructions which are more or less standard in the paper-making industry wherein high speeds are used for the Fourdrinier wire. The head-boxes are arranged to discharge the stock, which usually is a very thin slurry of fibers, at a high speed in keeping with the high speed of the wire, thus making a slow relative motion between the wire and the stock. Su'chhead-boxes are not suitable for low speed Fourdrinier machines, inasmuch as high speed in the stock as it runs onto the wire causes irregular formation or streaks. In

the stock maintains agitation, and at the same time to provide for depositing the stock on the wire so as to prevent any great amount of speed of the stock on the wire itself.

- Various other and ancillary objects and advantages of the invention will appear in the following description and explanation of the invention as it is set forth in the accompanying description of an exemplary embodiment of the invention shown in the accompanying drawing in which:

Fig. l is a longitudinal section of the head end of a Fourdrinier machine showing the construction of a head-box and its relation to the Fourother words, the stock should not flow extensively drinier wire.

on the wire itself. When it does, it usually flows Fig. 2 is a vertical cross-section of the strucfurther in the center of the wire than on the ture shown in Fig. 1 on the line 22 of Fig. 1. edges, producing bad formation, or thin orrag- In the drawing, the Fourdrinier wire it is of ged edges, and sometimes ripples in the sheet. the usual endless type, coming up from the lower This is especially true where thick sheets of felt stretch over idler roll II and breast roll 82, to a 2 are made, such as is necessary in forming insusubstantially horizontal plane, and preferably a lation board on a continuous Fourdrinier matrue horizontal plane, although it may slope upchine. wardly towards the right in Fig. 1. The upper Stock for thick and thin sheets of felt must be stretch is supported on a series of small rolls I3,

highly agitated and thin for uniformity in the beneath which there is a drain pan it for receiv- 25 felt. Relatively larger volumes are used per unit ing water which drains through the wire and bearea of wire, than in making papers, or cardtween the rolls. Near the point where the wire board stock, or other thinner types of felt. In leaves the breast roll l2 there is a sealing lip l5, high speed machines the high velocity of the stock as of rubber, attached to suitable dam-forming gives a suitable agitation. The volume of stock structure, to provide a pool above the wire for 30 per unit of time may be generally the same for a. receipt of the furnish. The sides of the wire may slow-speed board process, as for a high-speed be dammed off by customary means, such as deckpaper process. But the agitation by velocity of el straps or side-boards, the latter being shown at flow onto the wire in the direction of the wire, l6 extending back to form side walls for the headis not desirable because such velocity is too great box. 35 for the slower moving wire of the board machine. The head-box includes a part providing o According to the present invention, the advanhigh velocity in the direction of the wire to secure tages of high speed flow to maintain agitation agitation by flow, such part being shown as a flat are retained, and such velocity of flow is actually inclined spillway I1. Stock may reach the spillemployed in the direction of the ygire, but there way in numerous ways. A suitable structure in- 40 is disposed between the wire and the place of cludes a box l8 with a vertical baflle l9 under said high velocity flow, a baiile means which may which stock flows, to form a pool 20 which flows be a reversing structure, which causes the high over dam 2! directly into the spillway. Behind speed stream to be stopped or reversed and then baflie IS a head is built up to a suitable constant discharged onto the wire in a suitable manner. level such as 22, determined by a vertical baille 45 The invention also provides for dropping the 23, at the top level of which there is the bottom stock onto the wire. It may also provide a dam level of an overflow outlet 24, leading to overflow or covered sluice-way above the 'wire into and duct 25. Stock is forced into the resulting conthrpugh which the stock flows or is carried, the stant level chamber 26 through conduit 21; surcover of said sluice-way serving as a leveling deplus flows out the overflow 24, and the useful 50 vice to discharge a thickness.

The primary object of the invention is to provide large volumes ofa thin slurry to a slow moving wire in such a way that high velocity in smooth watery felt of uniform stock fills chamber 28 to a constant level to discharge into pool 20. By such an arrangement a high velocity in a thin stream is maintained for agitation by flow. This readily breaks up agglomerates or lumps of fiber.

At the lower end of the spillway l1 there is a stop means, such as a vertical baflle or stop plate 30, arranged to arrest the flow in the direction of wire movement. The stock at this point might be dropped directly down onto the wire near the seal l5, but such construction would necessitate either damming off the wire area to the rear, or otherwise the entire head-box as shown would need to be set further back on the machine. Therefore, in order to shorten the machine the spillway H is placed over the wire and the stock is carried backward to the vicinity of the breast roll I2.

A rearward shelf 3| lies under the spillway i1,

and it has a vertical mid-web or dam 32 and a vertical edge-damor web 33. These serve to slow down the stock, to agitate it, and to provide a collecting place for any heavy pieces such as metal that may get into the stock. The stock discharges over the dam 33, onto the wire by a downward and rearwardly slanting drop. A dam or back baflie 35, which carries the seal I5, would prevent rearward motion of the stock on the wire, should the breast roll be further back than shown.

At this stage the stock is very mobile and fluid, and remains so until considerable water has been drained off through the wire. By placing the shelf 3| close to the wire, a slight head may be built up between the dams 33 and 35, causing flow into space 36 between the shelf 3| and the wire. Since water is draining from the screen along this zone the flow compresses the stock slightly lengthwise of the wire as the stock is thickened by dewatering. The space 36 may be lengthened, as by an extension plate 38 to any point desired, such for example that a smooth level felt F, still highly watered, is discharged at the point 39, the felt F being static on the wire at this point. By this arrangement a uniformly felted thick sheet may be formed with a very level surface.

There is no critical relation between the speed of the wire and the stock flowing onto it. The speed of the wire could be increased without change in the construction except perhaps adjustment of the space 36. The construction minimizes flow of stock on the wire after the stock is deposited. Friction is introduced at the top of the felt over the entire width of the wire so that any movement of stock, such as in the space 36, is under the same frictional force, with resulting regularity in formation over the width of the wire. The space 36 operates against variations in thickness of the stock on the wire by eddy currents or splashing.

Various other arrangements may be made to secure these advantageous features of construction and operation without departing from the spirit and scope of the invention as expressed in the appended claims.

I claim: 7

1. A head-box for a Fourdrinier type of fiberfelting machine comprising a constant level sup- I ply device for stock furnish, means providing a spillway for discharging stock from said supply device in the direction of the Fourdrinier wire movement, stop means at the bottom of said spillway, a flow shelf leading under the spillway for reversing flow of said stock backwardly on said shelf, said shelf being arranged to discharge the stock for downward motion onto the Fourdrinier wire, and a dam in advance of the stock leaving said shelf in sealed relation with the Fourdrinier wire, whereby to form a pool area on the wire for receiving the stock from said shelf.

2. A head-box for a Fourdrinier type of fiberfelting machine comprising a constant level supply device for stock furnish, means providing a spillway for discharging stock from said supply device in the direction of the Fourdrinier wire movement, stop means at the bottom of said spillway, a flow shelf leading under the spillway for reversing flow of said stock backwardly on said shelf, said shelf being arranged to discharge the stock for downward motion onto the Fourdrinier wire, and a dam in advance of said shelf in sealed relation with said wire at the breast roll for said wire, whereby to form a pool area on the wire at the breast roll for receiving the stock from said shelf. ORCU I'I W. FROST.

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