US2688276A

US2688276A - Head box for paper machines

Info

Publication number: US2688276A
Application number: US225857A
Authority: US
Inventors: Robert E Showers
Original assignee: Marathon Corp
Current assignee: Marathon Corp
Priority date: 1951-05-11
Filing date: 1951-05-11
Publication date: 1954-09-07
Anticipated expiration: 1971-09-07

Description

Sept. 7, 1954 Filed May 11, 195] R. E. SHOWERS 2,688,276

HEAD BOX FOR PAPER MACHINES 3 Sheets-Sheet l FIG. 1

I ZZJOJZ IN VE/V 1 o TURN Sept. 7, 1954 E. SHOWERS HEAD BOX FOR PAPER MACHINES a Sheets-Sheet 2 Filed May 11, 1951 M TTOR/VEY Sept. 7, 1954 R. E. SHOWERS HEAD BOX FOR PAPER MACHINES 3 Sheets-Sheet 3 Filed May 11, 1951 Patented Sept. 7, 1954 HEAD BOX FOR PAPER MACHINES Robert E. Showers, Green Bay, Wis., assignor, by mesne assignments, to Marathon Corporation, Menasha, Wis., a corporation of Wisconsin Application May 11, 1951, Serial No. 225,857

The present invention relates to paper making machines of the Fourdrinier type, and more particularly to head boxes or flow boxes for such machines.

An object of the invention is to provide a head box having an improved discharge or outlet portion by means of which a smooth stream of wellmixed stock will be delivered onto the forming surface of a Fourdrinier belt, whereby to obtain formation of a sheet of paper of uniform thickness and good quality at high speed.

Another object is to provide a head box with a discharge throat or passage having therein a grid section forming numerous longitudinal ducts to smooth and straighten the stock flow and to effect a mild mixing action on the stock, the walls of the ducts being so arranged as to avoid lodging of stock thereon and to prevent streakiness in the stock stream.

A further object is to provide a duct-forming grid section which is capable of simple installation in the head box discharge throat or passage, and which can be inexpensively manufactured.

The invention further consists in the several features hereinafter described and claimed.

In the accompanying drawings,

Fig. 1 is a vertical, sectional, elevational view of the head box end of a paper making machine embodying the present invention;

Fig. 2 is a fragmentary sectional elevation of a discharge throat or nozzle of the head box;

Fig. 3 is a transverse sectional view of the discharge throat, taken generally on the line 33 of Fig. 2; 1

Fig. 4 is an enlarged fragmentary sectional elevation of a portion of the discharge throat and a grid section therein;

Fig. 5 is a fragmentary sectional view taken generally on the line 5-5 of Fig. 2;

Fig. 6 is a fragmentary bottom view, with parts in section, of laterally adjacent grid section tubes;

Fig. '7 is a fragmentary detail sectional view of the upstream end of the grid section, and

Fig. 8 is a fragmentary detail sectional view of the upstream end of a modified form of grid section.

In the drawings, I ll designates a paper making machine head box having a discharge throat or channel ll terminating at a slice l2 with a slot-like orifice from which a flat stream of pulp stock flows onto the upper run of a Fourdrinier wire belt 13, the belt being trained around the usual breast roll I l.

The head box is here shown to be of the gravity 4 Claims. (Cl. 92-44) flow type and includes parallel side walls l5 (one being shown), a bottom wall 16, and upper and lower front walls I! and 18, the lower front wall being offset rearwardly from the upper front wall, and the discharge throat sloping downwardly and forwardly at an angle of the order of 25 /2" from a region between the front walls. The head box further includes a transversely extending vertical bafile wall or dam i9 spaced rearwardly from the lower front wall I8 and forming a pond chamber or delivery chamber with the front walls and Side walls, there being an up-pass 2| between the baffle wall and the lower front wall. The baflle wall [9 has a rounded lower edge spaced above the bottom wall to form a slot-like passage 22 extending across the width of the head box. A transversely extending vertical wall 23 is spaced rearwardly of the baffle wall I9 to form between them a down-pass 24, the passage 22 providing communication between the down-pass 24 and the up-pass 2|. The lower end of the vertical wall 23 joins the bottom wall along a curved surface 25 sloping forwardly to the passage 22, and the upper end of the wall 23 is higher than the entrance of the discharge throat ll but is normally submerged. The bottom passage 22 is considerably narrower than the width of the up-pass and down-pass and serves to increase the stock velocity at this region, so as to effect mixing of the stock shortly before it is discharged from the head box. However, the velocity should not be so high as to cause excessive disturbance of the stock when it enters the discharge throat. The optimum velocity can be provided by vertically adjusting the baffle wall I9. The lower end of the up-pass 2| has a normally closed drain opening 26 for-med in a side wall of the head box.

The inclined discharge throat or channel II is formed between upper and

lower cross plates

21 and 28 and vertical side plates 29, all formed of metal, the

cross plates

21 and 28 having smoothly curved rear end portions attached to the respective upper and lower front walls of the head box, and the side plates 29 being parallel to each other and being attached to the parallel side walls of the head box. The

plates

21 and 28, which include inclined parallel portions, are supported by a suitable frame work having sets of laterally spaced top and bottom frame members 30 and 3| extending forwardly from the front walls of the head box, each set of frame members being secured to separator bars 32, and the endmost frame members being also secured to the side plates 29. The lower frame members 3| are suitably supported at their rear portions,

the upper frame members 30.

springs 51 surrounding bolts 58 as by a cross beam 33 carried on columns 34, one of the latter being shown. The cross-sectional area of the throat or channel I I is of horizontally elongated rectangular shape, as indicated in Fig. 3. The throat has mounted therein a flow-smoothing and stock-mixing grid section 35 hereinafter more fully described.

The slice'IZ comprises a forwardly sloping top plate or lip 36 spaced above a bottom plate 3'1, the sides of the slice orifice being defined by vertical side plates 38 between which the top plate slidably fits. The slice plate 33 ishingedlycarried at its rear portion, as hereinafter described. The bottom plate 3'! is a part'of a ribbed'tbeamforming base 39 which is suitably supported'as by columns 49 (one being shown). The ends'o'f the base carry upstanding endcastings 4| which together with the frame members 30 mount sliceadjusting means 42 of any suitable type. The

plates

36 and 31 are provided with respective -

liners

43 and 44, Fig. 2, which form continuations :of the throat plates 2'! and 28. The various plates idefining the. interior surfaces of the discharge .throat are of corrosion-resistant and slime in- 'hibiting metal. such as copper, and are suitably "fastened in place, as by bolts 45. The lower plate 31 has an approximately horizontal front portion "-46,the. liner of which lies slightly above the plane of the upper run of the Fourdrinier wire belt and terminates a short distance rearward of the veratical central plane of the breast roll I 4. The rear portion of the plate 31 is curved upwardly and has a transverse bottom flange 41 which is rigidly bolted to the front ends of the frame members .3] for the lower throat plate 28. The slice plate 36 has a forwardly and downwardly inclined front portion 36 which has a lesser slope than the main portion of the throat and has its front end spaced a short distance above and rearward of the horizontal front end 46 of the plate 31 to form therewith the slice orifice or outlet. By way of example, the slot-like slice orifice may be about 4;" high in the case of a tissue making machine. The

plates

36 and 31 form a forwardly converging front portion of the discharge passage II, the slope of the front portion 36' of the slice plate 36 being of the order of 13 front end of the slice plate 36 is vertically adjustable, as by a series of suspension rods 48 (one being shown) forming a part of the slice adjusting means 42. The rear end of the slice plate 36 is upwardly curved and has a transverse top flange 49 which is slightly spaced from a transverse angle bar 50 secured to the front ends of A number of spaced studs 51 (one being shown) are threaded into the upper edge of the rear flange 49 of the slice plate 36 and extend upwardly therefrom through the forwardly projecting top flange of the angle bar 59. At their upper ends the studs have nuts 52 resting on segmental rockers 53 (one being shown) saddled in apertured bearing members 54 which are secured to the angle bar top flange, the studs passing through the rockers and the bearing members. Upward displacement of the slice plate flange 49 is resisted by et screws 55 (one being shown) carried by the angle bar 50. A yieldable rubber sealing strip 56 is'interposed between the slice plate flange 49 and the angle bar 50 and is held under pressure by coiled which pass through the flange and angle bar.

The flow-smoothing and stock-mixing grid section 35 is here shown to comprise a number of rows of parallel metal tubes 59, preferably of cop- The -of some of the ducts. of the tube walls at the upper portion of the clumping of .stock thereon.

at the slice.

oppositeends and all extending in the "direction of the line of flow, all the ducts being parallel to the planes of the vertical side plates 29 and of the inclined parallel portions of the upper and

lower throat plates

21 and 28. The upper and lower throat'plates 2'1 and 28 and the slice plates .36 and'3l are recessed at 60 to correspond with the thickness of the tube walls so that the inner surfaces .oftheuppermost and lowermost tube walls will be flush with the throat walls. As best seenin Fig. 4, the uppermost tube walls bridge the joint between the cross plate 21 and the slice plate liner 43, and the lowermost tube "walls bridge the joint betweenithe cross plate '28 and the liner 44 of the lower plate 31. At the opposite sides of the grid assembly the vertical tube walls are'cut awayzso' that theinner flat vertical surfaces of the throat side walls-will define'walls vIn some instances, some throat may terminate short of the side walls; as seen in Fig. 5. 'The lengthof the grid section in the directionof flow'isseveralxtimes as greatas .its top-to-bottom transversefdimension, and the length of each tubeis: many timeszits'transverse dimension, as shown irrFig. 2. The tubesiniver- .tically adjacent. rows are staggered,*as shown'in .Figsp'd and5, thus avoiding any'streakiness Lin the stock stream. The upstream ends of the tubes are cut square and have 'smoothlyirounded and polished edges 6| so as to prevent. lodging or The downstream end of the grid section extends'for some distance .into the forwardly converging front portion of .the discharge throat, and'this end of the grid section is Wedge-shaped and has ibias-cut edges 62, as seen in Fig. .2, so that the uppennost tubes extend farther forward .th'anthe other tubes, thus exerting a slightly greater retarding effect on the :upper portion of the "stream than on the lower portion so as to compensate for the difference in :the length of the stream pathsalong the upper and lower portions of'the curved front endof the discharge throat. At their downstream ends-the uppermost and lowermost walls of the tube assembly are cut square to fit in the recesses 60.

Except for these-uppermost and lowermostwalls,

the downstream ends of the top and bottom walls of the tubes have deep serrations or V-cuts 6'3 and sharpened edges '64, as seenin'Fig. 6, to minimize disturbance of the forwardly'flowin'g stock-as it leaves the ducts ofthe grid section and approaches the slice orifice. This'arrangement also avoids a sudden reduction of pressure which might causeformationor enlargement of air bubbles in the stock. The sharpenedbias-cut edges of the vertical walls of the tubes at the downstream ends of the tubes 'alsoserve to'minimize disturbance of the stock as it leavesthe tubes.

In the operation of the machine the pulp stock is supplied to the head box delivery chamber or pond chamber 20 through the up-pass"2l and is maintained at .asuitable level in this'chamber in accordance with the speed of thelFourdriner belt, this level determining the spouting've'locity The stock flows :downwardly 'and forwardly through the inclined discharge throat I I, and for a considerable distance passes through the numerous parallel ducts or channels formed by the tubes 59 of the grid section 35, thus effectively breaking up any large vortices and straightening the flow so that the stock stream issuing from the slice will have a smooth glassy appearance, free of streakiness and cross currents, and the paper formed will be of uniform thickness and quality. In its passage through the grid section tubes, the stock, by its frictional contact with the extended surface of the tube walls, will be subjected to a mild mixing action which will have a beneficial effect on the texture of the paper. The construction of the grid section is such that it is self-cleaning, avoiding any lodging or clumping of the stock. As the stock flows through the forwardly converging front portion of the discharge throat, the velocity of the stock gradually increases. However, the included angle of this portion of the throat is such as to maintain a non-turbulent flow while avoiding an excessive distance between the slice orifice and the front end of the grid section. The stock stream issues from the slice orifice substantially parallel to the top run of the wire belt and in the direction of travel of this top run.

The stock-mixing action in the grid section is caused by a rolling or vortex action in the layers of the stock along the surfaces of the top, bottom, and side walls of the numerous duct-forming tubes, thus providing a random orientation of the stock fibres in the issuing stock stream so as to improve the felting of the fibres during formation of the sheet. The mutually perpendicular transverse dimensions of each tube are of the same order of size, thereby avoiding any major disturbances in the stock flow, and each tube is of suflicient length to provide adequate flow-straightening and stock-mixing action. By way of example, each tube may have a length of the order of 20 times its width. While the ducts formed by the tubes are preferably of square cross-section, as shown, they may have various other cross-sectional shapes, such as rectangular, hexagonal, trapezoidal, and triangular.

The construction of the present invention enables a smooth, high-velocity flow of well-mixed stock to be delivered to the forming surface of a Fourdrim'er wire, so as to secure the formation of a strong sheet of paper of uniform thickness and good quality at higher operating speeds.

The modified form of grid section 35' shown in Fig. 8 is similar to that of Fig. 2 except that rounded and polished beads 6 I are secured, as by brazing or welding, to the edges of the upstream. ends of duct-forming grid section tubes 59 to form the margins of the duct entrances, the width of the rounded beads being greater than the thickness of the duct walls. The rounded beads prevent lodging of stock thereon and initiate a rolling or vortex action of the stock along the duct walls to effect mixing of the stock. The grid section 35' provides a smooth, high-velocity flow of well-mixed stock, as in the construction of Fig. 2.

What I claim is:

1. In a paper making machine, a flow passage for supplying stock to a web-forming surface and having a discharge orifice, said passage including a portion with parallel upper and lower walls, and a grid section in said passage having vertical walls and having other walls parallel to said parallel passage walls, said grid section walls forming a plurality of rows of parallel flow-smoothing ducts extending longitudinally of said passage in the direction of the line of fiow in said passage, the downstream. edges of said vertical grid section walls extending angularly of the ducts, and the downstream edges of the other grid section walls being serrated.

2. In a paper making machine, a head box having an outflow passage communicating therewith for supplying stock to a web-forming surface, said passage having a forwardly and downwardly inclined portion extending from. said head box and provided with parallel upper and lower walls, and said passage further having an exit portion with forwardly converging upper and lower walls. and with a discharge orifice, the front portion of said last-named upper wall having a lesser slope than the inclined portion of the passage, and the front portion of said last-named lower wall being substantially horizontal, and a grid section in said inclined portion of the passage having walls forming a plurality of rows of flow-smoothing ducts all parallel to each other and extending longitudinally of said passage in the direction of the line of flow in said passage.

3. In a paper making machine, a flow passage for supplying stock to a web-forming surface and having a discharge orifice, and a grid section in said passage having walls forming a plurality of rows of parallel flow-smoothing ducts extending longitudinally in said passage, all of said ducts being in parallel relation to each other and extending in the direction of the line of flow in said passage, the upstream ends of said walls having edges with rounded beads thereon defining the entrances of said ducts, and said beads being thicker than the walls of said ducts.

4. In a paper making machine, a iiow passage for supplying stock to a web-forming surface and. having a discharge orifice, said passage including a portion with parallel upper and lower walls, and a grid section in said passage having vertical walls and having other walls parallel to said parallel passage walls, said grid section walls: forming a plurality of rows of parallel flowsmoothing ducts extending longitudinally of said passage in the direction of the line of flow in said passage and the downstream edges of said other grid section walls being serrated.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 417,546 Cushman Dec. 17, 1889 1,152,747 Metcalf Sept. 7, 1915 1,552,629 Mason, et al Sept. 8, 1925 1,610,742 Bucking Dec. 14, 1926 1,667,755 Valentine May 1, 1928 1,890,634 Wenzel Dec. 13, 1932 2,202,890 Berry June 4, 1940 2,284,098 Lang May 26; 1942 2,347,130 Seaborne Apr. 18, 1944 2,394,509 Boettinger Feb. 5, 1946