US2904461A

US2904461A - Method and apparatus for controlling flow of stock through a slice jet

Info

Publication number: US2904461A
Application number: US679965A
Authority: US
Inventors: Robert S Washburn; Charles W E Walker
Original assignee: Beloit Iron Works Inc
Current assignee: Beloit Iron Works Inc
Priority date: 1957-08-23
Filing date: 1957-08-23
Publication date: 1959-09-15
Anticipated expiration: 1976-09-15

Description

p 1959 R. s. WASHBURN ETAL 2,904,461

METHOD AND APPARATUS FOR CONTROLLING FLOW OF STOCK THROUGH A SLICE JET Filed Aug. 23, 1957 3 Sheets-Sheet 1 w u N i 1 77217 [UP 5 PoBERr 8. Max/30,9 v CHARLES WKMAKER Sept. 15, 1959 R. s. WASHBURN EI'AL 2,904,461

METHOD AND APPARATUS FOR CONTROLLING FLOW OF STOCK THROUGH A SLICE JET Filed Aug. 23, 1957 3 Sheets-Sheet 2 [57: 5 .27 [UP 5 RoaERr S M's/ma? Cane/.58 W5 WILKER Sept. 15, 1959 R. SQWASHBURN ETAL 2,904,461

METHOD AND APPARATUS FOR CONTROLLING FLOW 0F STOCK THROUGH A SLICE JET Filed Aug. 23, 1957 s Sheets-Sheet s finite METHOD AND APPARATUS FOR CONTROLLING FLOW OF STOCK THROUGH A SLICE JET Application August 23, 1957, Serial No. 679,965

12 Claims. (Cl. Em -216) This invention relates to the control of the flow of stock in a paper machine onto the forming wire, and more particularly, to slice jet leveling control.

In a paper machine, the head box receives incoming stock from a main source of stock flowing into the head box (usually through the bottom) at one end and the stock flows out of the head box at the opposite or slice end. A stock pond of appreciable depth is maintained in the head box (and air pressure is often applied to the top surface of the stock pond) so that there is rather substantial hydraulic pressure at the slice opening which is relatively thin and extends laterally across the width of the head box. Nevertheless, various stock currents and other flow irregularities occur in the head box so that the pressure on the stock is not the same at all points laterally across the slice gate. The stock issues from the slice gate in the form of a jet or high speed flow of stock directly onto the wire. Attempts to maintain a uniform flow of stock at all points laterally along the stock jet (or slice jet) are termed leveling of the jet issuing from the slice. As will be appreciated, if the jet is not perfectly level there will he resulting irregularities in the paper web ultimately formed in the machine.

Innumerable efforts have been made to level the jet issuing from the slice in a paper machine and many improvements have been made, but in each head box there persists stable high and low streaks, or ridges and valleys, in the slice jet as it issues from the head box. These irregularities can usually be detected first at the so-called dry line, which is the generally laterally extending line at which the stock on the wire changes in appearance from the shiny, glossy appearance of stock of relatively high water content to a dull finish of stock of appreciably less water content. In the ideal machine, the dry line is a substantially straight line extending laterally across the machine. If there are irregularities with respect to the stock jet in the intermediate portions of the slice, such irregularities will be reflected in the dry line. The same is true along the edges of the stock flowing through the slice. In particular, it will be noted that the dry line tends to recede (in the direction of the head box) along the edges. One corrective measure which has been suggested for overconing this objectionable feature has been the use of stock bleed at the checking pieces of the slice which robs fairly important quantities of stock laterally from the edges of the slice so as to force the stock to flow toward the edges and overcome the natural thinness of the forming web on the wire -at the edges. This, in turn, always requires additional correction of the flexible slice lip. In modern machines, a flexible slice lip is provided so as to alter to a limited extent the thickness of the slice jet at various locations laterally across the slice. Because of the nature of the flexible slice lip, the adjustment obtained is limited and leaves something to be desired often in the operation of paper machines.

The instant invention provides means and method for 9 means shown in the head box embodiment of Figure 3; 7

rates atet Z correcting irregularities in the slice jet, and particularly, for overcoming the jet velocity suppression that occurs along the side walls of the head box which leads to thinness of the forming web along the edges. In essence, the instant invention involves the concept of flowing independently controlled streams of stock into the head box intermediate the stock inlet and slice gate for purposes of making adjustments in the slice jet laterally across the machine. In order to overcome the jet velocity Suppression along the side walls of the head box, the instant invention provides independently controlled stock flow means which feed additional stock along the edges of the head box intermediate the stock inlet and slice gate so as to compensate for the normal jet velocity suppression. In addition, the instant invention provides means for feeding stock at any location laterally across. the head box so as to compensate for irregularities in the slice jet at any point. It will be appreciated that: the instant invention contemplates the addition of only relatively small amounts of stock, perhaps 1 to 5% of the total stock passing through the head box. In this way the instant invention is concerned primarily with adjustments in stock velocity and does not disturb the: overall flow of stock through the head box or the maintenance of the desired level of stock in the head box.. The instant invention may require a slight amount of. additional pumping power to add the independently con-- trolled stock streams to the head box, but this power consumption is much less than the power loss resulting from, for example, withdrawal of appreciable quantities: of stock at the checking pieces.

It is, therefore, an important object of the instant in-- vention to provide an improved slice jet leveling control. method and apparatus.

It is a further object of the instant invention to pro-- vide an improved method of controlling the flow of stock through slice onto the forming wire in a paper machine, which comprises maintaining a predetermined level of stock in pond in the head box to flow stock rapidly in: a thin jet through the slice, feeding stock into said pond. at an end thereof opposite the slice to maintain said level, and feeding laterally aligned independently ad-- justed streams of stock into the bottom of said pond intermediate the slice and said opposite end to control the flow laterally that passes through the stock.

Yet another object of the instant invention is to pro-- vide an improved head box for a paper machine com-- prising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, and conduit means having laterally spaced independently adjustable flow control means feeding stock into said head box intermediate the inlet opening and the outlet opening.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description thereof and the drawings attached hereto and made a part hereof.

On the drawings:

Figure 1 is a top plan view, with parts shown diagrammatically, of a paper machine forming Wire and a head box embodying the instant invention;

Figure 2 is an essentially diagrammatic view in elevation of the head box of Figure 1;

Figure 3 is also an essentially diagrammatic view in elevation of another head box embodying the instant invention;

Figure 4 is an enlarged detail view of the flow control Figure 5 is another essentially diagrammatic elevational view of a head box embodying the instant invention; and

Figure 6 is an essentially diagrammatic top plan view showing a portion of the head box of Figure 5.

As shown on the drawings:

In Figures 1 and 2, there is shown a head box indicated generally by the reference numeral 10 which comprises a front side wall (or slice gate) 11, a rear wall 12, side walls 13 and '14, and a generally horizontal bottom 15 (terminating with an apron 15a at the slice 16). As shown in Figure 2, there is also a top wall 17, sothat this is a closed head box 10 wherein the level L of stock in a pond within the head box 10 is maintained by the use in combination or" a blow hole 18 in the side Wall 13 and a source of air 19 under pressure, which maintains air pressure on the level L of stock. As will be appreciated, an increase in the level L of the stock will cover the blow hole 18 and cause an increase in air pressure from the source 19 so as to urge the stock level back to the blow hole 18, and a reduction in the level of stock appreciably below the blow hole 18 will result in a loss of pressure in the head box It), so that the stock level L will move back up to the blow hole 18. This arrangement is well known in the art and need not be described in further detail.

The stock feeds into the head box 16 via a stock inlet 20 through the bottom or floor 15 at one end of the head box 19 and then flows out through the slice gate 16 at the opposite end onto a forming wire 21 wound around a breast roll 22. Stock flow control means in the form of a pair of stacked

rectifier rolls

23, 24 is provided intermediate the inlet 20 and the slice gate 16 in the head box 16. The

rectifier rolls

23 and 24 are suitably mounted on bearings 24a, 24b (which are the only ones shown for the top roll 24).

The stock flows onto the wire 21 through the slice gate 16, as shown in Figure 1, to approximately the first suction fiat box 25, whereat the dry line, indicated in dash lines at 26, appears. In the preferred operation the dry line appears as indicated in the dash lines to extend in a substantially straight line laterally across the wire 21. However, in prior art machines, there is a tendency for the dry line to curve up at the edges 26a as indicated in dotted lines. This receding portion 260 of the dry line 26 is caused by the fact that the stock flow velocity is apparently slowed down along the edges of the head box 16 at the side walls 13 and 14, and a thinner stock flows onto the wire 21. This is overcome in the practice of the instant invention by the use of conduit means '27 and 28 along each side wall 13 and 14, respectively, intermediate the inlet 29 and the slice gate 16 for increasing the stock flow speed within the head box 10 along the side walls 13 and 14. The conduit means 27 and 28 are shown essentially diagrammatically, although they are presented in the drawing of Figure 1 to show a stock flow path through one or more right angles to eifect uniform flow of stock within the conduits 27 and 28, and particularly at the conduit openings 27a and 28a whereat the stock enters into the pond of stock within the head box 10. As will be appreciated, stock from a suitable source, indicated diagrammatically at 29 flows through a control valve 30 into the uprunning pipe 27b of the conduit means 27. The valve 3th controls accurately the relatively small amount of stock that flows through the conduit means 27. A similar arrangement is provided for the conduit means 28 on the opposite side of the machine. The stock source 29 may be a separate pump, or it may be merely a conduit leading from the main fan pump. The stock flows upwardly through the pipe 27 b and then through the right angle turns indicated in Figure l and out through the outlet 27a, whereat the stock flow imparts additional velocity to the stock within the pond along the wall 13. By increasing the stock velocity along the walls 13 and 14 in accordance with the instant invention, it is possible to eliminate the receding

portions

26a, 26a of the dry line 26 and obtain a substantially straight dry line.

Referring now to Figure 3, it will be seen that there is shown a head box comprising a front or slice wall 41, a rear wall 42, side walls 43 and 44 (only the wall 43 being shown), a bottom wall 45 and a top wall 45a. The bottom wall 45 and the front wall 41 define therebetween a slice 46 from which stock flows onto a forming wire 51 trained around a breast roll 52. A stock inlet indicated generally at flows stock through the bottom :5 at the end thereof opposite to the slice gate 46, so that stock flows longitudinally through the head box 40.

A blow hole 48 maintains the desired stock level L1 in the manner hereinbefore described. A stack of rectifier rolls 53, 54 is mounted intermediate the inlet 50 and the slice gate 46 in the usual manner, so as to afford means for reducing eddy currents and cross currents in the stock. Also, additional rectifier rolls 55 and 56 are provided immediately adjacent the slice gate 46, but still between the inlet 58) and the slice 46. Intermediate the

rectifier roll stack

53, 54 and the bridging rectifier rolls' 55 and 56, there is provided along the bottom 45 an elongated slot-like opening 47. The opening 47 extendsthe full width of the head box 40 in substantial lateral alignment therewith, and this opening is provided for flowing laterally aligned but independently controlled streams of stock into the stock pond in the head box 40.

As shown in Figure 4, the conduit means 47 is defined by a substantially rigid wall Sh (defining the rear edge of the opening 47) and a flexible wall 60. The flexible wall 60 defining the front edge of the opening 47 and extending the full width thereof. A plurality of laterally spaced arcuate brackets 61 extend the full width of the bottom floor 45 and are suitably connected thereto, so as to resist flexing movement. Adjustable means 62 in the form of wing nuts are used to flex the wall 66 so as to control the flow of stock laterally at various points through the conduit 47. Only one such adjusting means 62 is shown, but it will be appreciated that a plurality of relatively closely spaced

wing nut assemblies

62, 62, etc. are mounted across the bottom wall 45 to control flow of stock through the conduit 47. As is indicated the conduit 47 is connected to a suitable source of stock 63, which in this case is a main conduit extending the full width of the head box 46 (connected to a fan pump or other suitable source of stock, not shown).

In Figures 5 and 6, there is shown another embodi gate 71, a rear wall 72, side walls 73 and 74, a generally horizontal bottom 75 terminating with an apron 75a defining the slice 76 with the front wall 71, and a top wall 77. The stock is maintained at a level L2 by the operation of a blow hole 78 in the manner hereinbefore described.

The stock feeds into the head box via a stock inlet 8% through the bottom floor at the rear end of the head box 70 and then flows out through the slice gate 76 at the opposite end onto a forming wire 81 wound around a breast roll 82 in the usual manner. Stock flow means in the form of a pair of stacked rectifier rolls 83 and 84 is provided intermediate the inlet and the slice gate '7 6 in the head box '70. The rectifier rolls 83 and 84 are suitably mounted on bearings (only the top bearing 84a being shown in the view of Figure 6), in the customary manner.

Intermediate the

rectifier roll stack

83, 84 and the slice 76, there is provided along the bottom 75 a plurality of through each opening 87a, 87b, etc. in order to contro stock velocities at the slice jet 76.

As indicated in Figure 5 (wherein the flow control means are shown only for the first opening 87a) the opening 87a is fed by a conduit 88a leading from a main header 89 extending the full Width of the head box 70'. The header 89 fceds through a right angle turn at 90a into the conduit 88a and a valve 91a controls the precise amount of stock which flows out the opening 87a. For each opening 87a, 87b, 87c, etc. there is provided a corresponding conduit 88a, 88b, 88c, respectively, and a control valve 91a, 91b, 91c, respectively, mounted therein. All of these conduits 88a, 88b, etc. are fed by a main conduit 89 which extends the full width of the machine and which in turn is fed stock from a stock source 92 (indicated diagrammatically in Figure 6) and through a stock header 93. A predetermined pressure of stock is maintained in the header 89 and the valves 91a, 915, etc. control individually the amount of stock which flows out of each opening 87a, 87b, etc. Here again, the total amount of stock fed through all of the openings 87g, 87b, etc. need only be within the range of about 1 to 5% of the total stock flowing through the head box 70, and this relatively small amount of stock is fed intermediate the inlet 80 and slice gate 76 for the purpose of making adjustments primarily in stock flow speed in given regions. These adjustments are made in order to reduce irregularities in the slice jet at the slice 76. The valves 91a, 91b, 910, etc. are thus independently adjustable for purposes of leveling the slice je The inlets 87a, 87b, 87c, etc. may be used alone to make the desired adjustments in the slice jet; or they may be used in combination with another series of laterally spaced

openings

93a, 93b, 93c, etc.; or the second series of

openings

93a, 93b, 930, etc. may be used alone without the openings 87a, 87b, 87c. But the best results are obtained using the openings 87a, 87b, etc. and 93a, 93b, etc. in combination. As is apparent, the

openings

93a, 93b, 930, etc. are spaced in substantially the same manner that the openings 87a, 87b, 87c are spaced, except that they are mounted in the front wall 71 and they feed into the stock pond immediately adjacent the slice 76. The opening 93a (which is on the extreme side) feeds immediately adjacent and above the slice 76. As will be appreciated the opening 93a can be formed by the tube element 94a therefor mounted along the inside surface of the slice gate 71, although the tube element 94a is here shown mounted Within the wall. Each

tube element

94a, 94b, etc. is fed from a main cross header 95 (also connected to the stock source 92 via the stock header 93). The actual flow of stock in any

individual conduit

94a, 94b, etc., and thus the actual flow of stock out of any of the openings 9311,9312, etc. is controlled by independently adjustable valves 96a, 96b, etc.

It will be understood that modifications and variations may be effected Without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, and conduit means connected to said source of stock having laterally spaced independently adjustable flow control means feeding stock into said head box intermediate the inlet opening and the outlet opening.

2. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, and conduit means connected to said source of stock having laterally spaced independently adjustable flow control means feeding stock into said head box along each side wall intermediate th inlet opening and the outlet opening.

3. A head box for a paper machine comprising front,

side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, and conduit means connected to said source of stock having laterally spaced independently adjustable flow control means feeding stock into said head box laterally across the bottom intermediate the inlet opening and the outlet opening.

4. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, and conduit means connected to said source of stock having laterally spaced independently adjustable flow control means feeding stock into said head box laterally across the front wall just before the outlet opening.

5. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming Wire of the paper machine, and conduit means connected to said source of stock having laterally spaced independently adjustable flow control means feeding stock into said head box laterally across the bottom intermediate the inlet opening and the outlet opening and laterally across the front wall just before the outlet opening.

6. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming Wire of the paper machine, means connected to said source of stock defining a thin conduit extending laterally of the head box and feeding through the bottom intermediate the inlet opening and the outlet opening and laterally spaced independently adjustable means in control of the thinness of said conduit across the lateral dimension thereof to control the stock flow rate into the head box.

7. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, means connected to said source of stock defining a plurality of spaced conduits. extending laterally of the head box and feeding through the bottom intermediate the inlet opening and the outlet opening, and independently adjustable means in control of each of said spaced conduits to control the stock flow rate into the head box.

8. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, means connected to said source of stock defining a plurality of spaced conduits extending laterally across the front Wall just before the outlet opening, and independently adjustable means in control of each of said spaced conduits to control the stock flow rate into the head box.

9. A head box for a paper machine comprising front, side and rear walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, means connected to said source of stock defining a plurality of spaced conduits extending laterally of the head box and feeding through the bottom and extending laterally across the front wall just before the outlet opening, and independently adjustable means in control of each of said spaced conduits.

10. A head box for a paper machine comprising front, side and rear Walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end for flowing stock onto a forming wire of the paper machine, stacked rectifier rolls intermediate the inlet and outlet, and conduit means connected to said SOUICG of stock having laterally spaced independently adjustable flow control means feeding stock into said head box intermediate the rectifier rolls and the outlet.

11. A head box for a paper machine comprising front, side and rear Walls and a bottom extending longitudinally from an inlet opening at one end for receiving stock from a source thereof to an outlet opening at the other end of flowing stock onto a forming Wire of the paper machine, stacked rectifier rolls intermediate the inlet and outlet, and conduit means connected to said source of stock having laterally spaced independently adjustable flow control means feeding stock into said head box 8 laterally across the bottom intermediate the rectifier rolls and the outlet.

12. A method of controlling the flow of stock through slice onto the forming Wire in a paper machine, Which comprises maintaining a predetermined level of stock in pond in the head box to flow stock rapidly in a thin jet through the slice, feeding stock into said pond at an end thereof opposite the slice to maintain said level, and

feeding laterally aligned independently adjusted streams of stock into the bottom of said pond intermediate the slice and said opposite end to control the flow laterally that passes through the stock.

References Cited in the file of this patent UNITED STATES PATENTS Witham Mar. 13, 1928