US3902961A

US3902961A - Adjustable slice lip for a headbox

Info

Publication number: US3902961A
Application number: US408087A
Authority: US
Inventors: Arnold J Roerig; Joseph D Parker
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1972-02-24
Filing date: 1973-10-19
Publication date: 1975-09-02
Anticipated expiration: 1992-09-02
Also published as: FR2173349B1; CA984196A; IT979417B; GB1417736A; JPS5257201Y2; JPS52108303U; DE2307968A1; BR7301364D0; AR200125A1; FR2173349A1

Abstract

A paper making machine having a substantially horizontal fourdrinier wire supported on a breast roll and a headbox includes a slice lip construction for shortening and controlling the trajectory of stock emerging from the headbox slice by deflecting the stock stream downwardly against the wire and changing the deflection with change in size of slice opening to maintain an optimum slice strain angle relative to the wire. One form of headbox has an elongate thin tapered slice chamber with the top wall and a bottom wall leading to a slice opening with the slice chamber inclined upwardly and the slice lip construction is positioned to direct the trajectory of stock onto the wire.

Description

United States Patent 1 1 Roerig et al.

[4 1 Sept. 2, 1975 ADJUSTABLE SLICE LIP FOR A HEADBOX [75] Inventors: Arnold J. Roerig, Beloit, Wis;

Joseph D. Parker, Roscoe, Ill.

Related US. Application Data [63] Continuation-impart of Ser. No. 228,814, Feb. 24.

1972, abandoned.

Hill et al. Means ct al.

Primary E.\uminerS. Leon Bashore Assistant ExaminerRichard V. Fisher Attorney, Agent. or FirmHi1l, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson 5 7 1 ABSTRACT A paper making machine having a substantially horizontal fourdrinier wire supported on a breast roll and a headbox includes a slice lip construction for shortening and controlling the trajectory of stock emerging from the headbox slice by deflecting the stock stream downwardly against the wire and changing the deflection with change in size of slice opening to maintain an optimum slice strain angle relative to the wire. One form of headbox has an elongate thin tapered slice chamber with the top wall and a bottom wall leading to a slice opening with the slice chamber inclined upwardly and the slice lip construction is positioned to direct the trajectory of stock onto the wire.

9 Claims, 5 Drawing Figures ADJUSTABLE SLICE LIP FOR A HEADBOX BACKGROUND OF THE lNVENTlON This application is a continuation-in-part of our copending application. Ser. No. 228.814 filed Feb. 24. 1972, now abandoned.

The invention relates to improvements in headboxes for use with fourdrinier type paper machines and particularly to obtaining more nearly homogeneous flow disturbances in the slice discharge jet than structures heretofore available by shortening the trajectory of stock emerging from the slice before it contacts the fourdrinier wire and controlling the trajectory angle to an optimum angle.

It has been a paramount objective in the design of headboxes to obtain a high degree of homogeneity of activity in the fibers suspended in the slurry throug out the headbox and particularly immediately ahead of the forming zone on the fourdrinier as the stock is discharged onto the wire. Various forms of headboxes have been designed to obtain this. Conventionally. turbulence was generated in the headbox by rectifier rolls. It has been discovered that the turbulence anddistribution of fibers can be maintained by the provision of flexible trailing members in the headbox which separate the flow of stock into a plurality of streams with the flexible trailing members being anchored at their upstream ends only and being self-positionable.

The stock should be subjected to controlled flow within the confines of the headbox as long as possible prior to discharge onto the traveling fourdrinier wire. Relatively long exposure of the trajectory of stock emerging from the headbox wil cause decay of the homogeneity present within the stock.

it has also been found that it is desirable in many constructions to position the headbox at an incline so that entrained air is self-purging. The slice extends upwardly at an angle on the uprunning side of the breast roll carrying the fourdrinier wire and discharges before the top dead center of the breast roll. Such a discharge will result in the emerging stock flowing through an arcuate path to drop onto the four-drinier wire immediately after the top dead center of the breast roll. However. this permits a relatively long flow of controlled stock no longer subjected to the confines of the trailing flexible members or any other headbox configuration for maintaining stock homogeneity. Consideration has been given to extending the thin slice further over the top of the breast roll. but this is disadvantageous in that it is space consuming because of the structure required between the point of discharge and the top of the breast roll to control deflection. It is also costly and impractical inasmuch as a curved extension must be provided at the discharge end of the slice.

it has been discovered that there is an optimum trajectory angle or slice stream approach angle relative to the wire. The stock stream emerging from the slice opening should under optimum circumstances engage the traveling wire relatively close after the wire leaves the surface of the breast roll. The stock stream cannot engage the wire at the point where the Wire lifts off the breast roll because severe pumping occurs at that area and at that point. the fibers would be pulled through the wire. The stock stream should. therefore. engage the wire immediately beyond the zone of severe pumping action.

With changes in types of stock and changes in machine speed. the width of the slice opening is changed to increase or decrease the thickness of the stock flow stream. This is done usually by raising or lowering the upper slice lip or raising or lowering the upper roof of the slice chamber in order to change the height of the slice opening. This change has heretofore resulted in a change of the trajectory angle of the slice stream so that paper machine designers have had to compromise and construct the position of the slice chamber so that the optimum slice stream trajectory angle exists for only one adjustment size opening. However. with the structure of the present invention it is possible to obtain an optimum trajectory angle of all slice opening settings. This is accomplished as will later become more clear from the detailed description of the structural features of the invention. by changing the setting of the unique deflecting lip concurrently with the change in slice opening. In a preferred form. as the size of the slice opening is changed. the deflector lip at the top side of the slice opening is changed in position so that it moves along a line extending between the distal edge of the lower slice lip and the distal edge of the upper slice lip. Movement along this path is approximated. in one form of construction. by mounting the upper deflector lip on a pivotal mount positioned so that with pivotal movement of the deflector slice lip. its distal edge will generally move along the path defined by the line extending through the distal edges of the upper and lower slice lips.

Accordingly. it is an object of the present invention to provide an improved slice construction for a paper making machine which permits a change in size of the slice opening while maintaining an optimum slice jet stream trajectory angle.

A further object ofthe invention is to provide a paper machine slice construction which permits adjustment ofthe angle of the stock stream emerging from the slice opening to an optimum angle relative to the position of the forming surface for achieving the best results in paper web formation on the forming surface.

It is a further object of the present invention to provide a method and means for improving and shortening the path of the stock from the slice to the wire by deflecting and adjustably controlling the trajectory of stock issuing from the slice of a headbox with adjustment changes in the size of the slice opening.

It is another object of the present invention to provide a means for obtaining improved fiber distribution and improved web formation with an upwardly inclined headbox having a thin tapered slice chamber with a slice lip which deflects the trajectory of a stream of stock between the slice opening and the wire.

Other objects. advantages and features will become more apparent in connection with the teaching of the principles of the invention in the claims. description and drawings wherein variations and modifications of the invention will become apparent to those versed in the art.

IN THE DRAWINGS FIG. 1 is a side elevational view. shown in section and somewhat schematic for purposes of illustration. of one FIG. 3 is a plan view of the structure of FIG. 2;

FIG. 4 is a diagrammatic view illustrating the location of the slice lip; and

FIG. 5 is a somewhat schematic view ofan alternative arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a breast roll supports a traveling forming wire I1. Stock is fed onto the traveling forming wire from a headbox I2 and the trajectory of the stock steam is illustrated at 13. The stock stream flow onto the wire must occur at an optimum location immediately after the top dead center of the breast roll so that immediate dewatering can begin. The velocity of the flow of the stock is substantially at the speed of travel of the wire. If the flow impinges the portion of the wire supported on the breast roll. a phenomenon called pumping can occur as the water and stock are drawn through the wire. This is very undesirable because it disrupts the web formation on the wire as the wire leaves the breast roll.

The headbox 12. shown in FIG. I, is exemplary and in certain circumstances other forms of headboxes may be used. The headbox has a chamber 14 into which the stock is delivered under pressure from suitable equipment such as a fan pump arrangement. and the stock flows through a plurality of parallel tubes 15 arranged across the headbox. the stock then containing turbulence with the fibers random oriented flows into a mixing chamber 16 to permit mixing and uniformity of flow. The stock then flows through an upwardly inclined pre-slice chamber 17. It has been found desirable to provide the elongate tapered pre-slice chamber 17 in an upwardly angled position so that air entrained therein would be purged. An incline of 3 or more adequately satisfies this function.

In operation of paper making machines of constructions heretofore available. a number of variables came into play during operation with these variables being adjusted by the paper maker to accommodate different types and grades of paper and stock and different speeds of the machine. These variables included change of the speed of the travel of the wire. change in the type and size of the wire openings. change in pressure in the headbox. change in the consistency ofstock. change in type of fibers of the stock and change in size of the slice opening. and possibly change in the overall angle or position of the headbox relative to the position of the breast roll and wire. Each of these variable factors may have an effect on the angle of the trajectory of the stock stream which should be used and also may change the resulting trajectory angle with any given slice lip setting. By utilizing features of the present invention. the paper maker can accommodate each of these variable factors by changing the deflecting slice lip to a position to obtain an optimum stock stream trajectory angle.

ken up into a plurality of layered flow strata by divider plates 18 in the preslice chamber 17 supported at their upstream end only in a plate 16a having a plurality of openings aligned with the spaces between the plates. These divider plates are preferably of polished stainless steel. The plates 18 are in the upstream portion of this prcslice chamber 17 in the headbox which tapers somewhat down to a narrower portion where trailing flexible members 19 are supported at their upstream ends only, being self-positionable downstream due to forces of the flowing stock.

The trailing flexible elements 19 are anchored at their upstream ends only to the plates. as shown at 20, with their downstream ends 19a extending to near the slice opening 23.

The elongate trailing members 19 are preferably in the form of continuous plastic sheets extending across the headbox parallel to the slice opening 23. It has been found that the sheets cannot be divided into gaps of any appreciable width along their lengths (in the crossmachine direction) without creating ridges or crossmachine direction defects in the paper web. However, an alternative form which may be used is to provide a plurality of substantially abutting or contiguous strands in the slice chamber instead of the sheets. The strands are preferably in the form of thin plastic trailing elements separated from each other and either aligned in rows in a crossmachine direction or arranged in random fashion with the strands each anchored at their upstream ends. The gap between adjacent elements in the cross-machine direction can be about equal to the plastic sheet thickness. However, it should never be so wide as to create streaks or ridges in the web.

The trailing elements extend substantially to the slice opening so that the homogeneity and random orientation ofthe fibers which has been achieved by the turbulence of the stock entering the headbox is maintained. The homogeneity retention has been found to be superior in directing the flow of stock through a relatively narrow elongate thin tapered slice and dividing the slice into a plurality of strata by the trailing flexible elements. The homogeneity will tend to begin to decay if the stock is permitted to be unconfined and uncontrolled when directed through a relatively long are of trajectory. Accordingly. in accordance With the principles of the present invention. the trajectory of the stock traveling upwardly through slice chamber 17a is immediately deflected downwardly upon exiting the slice lip, thereby reducing the length of time that the stock stream is uncontrolled.

For deflecting the trajectory of the stock emerging from the slice opening. an adjustable slice lip of unique design and unique positional movement is provided. The adjustable slice lip assembly 24 is shown in detail in FIG. 2.

With reference to FIG. 4, the principle of location and path of movement of the slice lip will be described. The general requirements include the slice chamber angled upwardly relative to the horizontal forming surface and the lower slice lip positioned in advance of the upper slice lip relative to the direction of stock flow. Further. the upper lip moves generally along a path dcfined by a line passing through the distal edges of the lower and upper slice lips. An optimum form of construction which achieves various advantages and which causes the distal edge of the upper slice lip to move up proximately along this path is the pivotal mount for the upper slice lip.

The schematic showing of a slice chamber 46 includes a bottom slice chamber wall 40 and a top slice chamber wall 41, The slice opening 47 is provided between the distal edge 42 of the bottom wall. and a slice lip 43 which has a distal edge 44.

An imaginary line AA is drawn connecting the edge 44 of the slice lip and the edge 42 of the bottom wall. For optimum performance. the slice lip 43 must be adjusted so that its edge 44 moves along line AA. With this construction. the slice opening can be adjusted without affecting the angle of discharge significantly. That is. as the slice opening is changed by upward or downward movement of the upper roof of the slice chamber. about the pivot knuckle 2211 in FIG. 1. The slice lip 34 in FIGS. 2 and 3 (43 in FIG. 4) can be adjusted to maintain the predetermined trajectory of the stock stream. It is essential that this be accomplished without varying the angle of discharge inasmuch as the location of the deposit of the stock on the traveling fourdrinier wire and the angle at which the stock stream approaches the wire is critical.

It has been known that the angle ofjet discharge [3 is a function of both ML and [1/8. When the ratio b/B remains roughly constant as it does with the arrangement shown in FIG. 4. it is necessary only to keep the ratio h/L constant to maintain constant jet angle [3 as the slice opening 47 is changed. To do this. the edge 44 of the slice lip should move along line AA.

For improved strength and mechanical performance in accordance with the present invention. the slice lip is pivotally mounted so that the arc shown by the broken line 59. FIG. 4. followed by the edge 44 follows the line AA faily closely. Thus. as the slice opening 47 is changed. the relationship above described will remain substantially the same. i.e.. the trajectory angle of the emerging stock stream will be unaffected by a change in slice openingv The paper maker may make the adjustments by changing the pivotal position of the slice lip each time he changes the position of the roof to thereby change the slice opening. In sophisticated automatic operating constructions. mechanical linkages will interconnect the operation of the mechanism for positioning the slice roof and for positioning the slice lip. and this can be accomplished by mechanically inter-. connected cam linkages or by simple computer mechanisms which has been programmed to provide correct slice lip positioning for each position of the slice roof. In other words. the distal edge 44 of the slice lip is changed in position each time the slice roof is moved about pivot 22a. i.e.. the slice lip is adjusted as a function of the position of the slice roof.

In the construction employed to pivotally adjust the slice lip in such a manner so as to affect the trajectory angle by controlling it to keep it constant with shift in position of the slice wall. as illustrated in FIGS. 2 and 3. a slice lip 34 is secured to a cylindrical bar 33. The bar is mounted in seat 32 on a slice lip support 31 carried on the top wall 22 of the slice chamber. The cylindrical bar 33 is supported in its pivotal location by clamping members 38, FIG. 3. which are secured on the plate 3] by bolts 39.

The pivotal position of the slice lip 34 is changed by tilting operating arms 35. The operating arms are tilted by adjusting tilting bolts 36. Changing the angle of the tilting arms 35 will change the angle of the slice lip 34 thus changing the size of the slice opening. that is. the distance between the slice lip 34 and the distal edge 30 of the bottom wall 21 of the slice chamber. These units. including arms 35, are positioned at intervals across the machine to make cross-machine profile corrections.

While the preferred form of mounting the slice lip is with a pivotal mount such as illustrated in the drawings. other types of mechanical mounts may be employed which will move the distal edge of the upper slice lip along the path defined by line AA as shown. i.e.. the line connecting the distal edges of the lower and upper slice lips.

Another form of changing the trajectory of the stock emerging from the slice opening is illustrated in FIG. 5. The construction of FIG. 5 does not meet all of the objectives of the foregoing described invention and structure. but achieves related objectives. The tip of the upper slice lip does not move along the path required for the objectives of the structure of FIGS. 1 through 4. and the construction of FIG. 5 is generally useful for one setting of the slice opening. and is useful in certain circumstances only. but does not provide the dexterity and wide range of control of the structure of FIGS. 1 through 4.

In the structure of FIG. 5. a breast roll carries a traveling fourdrinier wire 51. A headbox has a lower slice wall 52 and atop slice wall 53. with a slice opening 56. Trailing flexible elements 57 extend substantially to the slice opening. The slice opening size is controlled by a slice lip 54. To help change the trajectory of flow of the stock stream. the lower wall 52 is provided with a planar portion 55 which forms an approximately parallel surface relative to the plane of wire 51. The jet of stock is thereby quickly set onto the wire without distorting the shape of the lower slice chamber wall 52 by requiring it to extend up and over breast roll 50. In all of the arrangements illustrated in the drawings. the flow stream must undergo an abrupt change in direction at the opening. However. due to the controlling infiuence of flexible elements such as within the slice chamber 170. there is no apparent deterioration of the homogeneous condition of the fibers due to this deflection of trajectory within the short span that the stock stream must travel from the slice opening to the wire.

The principles of slice discharge deflection a'rc particularly useful with an elongate thin upwardly inclined tapered slice with the flow within the slice confined to relatively thin layers of stock between flexible trailing members so that a superior degree of homogeneity of activity in fiber suspension is attained. More uniform delivery of the stock onto the traveling forming wire and more uniform random orientation of the fibers is the result ofthis arrangement. This has been provcn by the various tests known to paper makers which show the degree of superiority of the paper product obtained. The superiority of the product clearly shows the improved jet stability has resulted as well as more uniform fiber distribution. Both in a cross-machine and in a machine direction. the variation in basis weight pro file has been significantly less with the employment of the principles of the present invention than with stock turbulence devices heretofore employed such as rectifier rolls. Also. the resulting paper has been found to have superior small scale uniformity and improved formation particularly with longer fiber furnish. An improved random orientation of the fibers generally results. Other tests indicating improved fiber distribution include splitting the resultant sheet into layers and dctermining the filtration resistance of the layers. Also. tensile and tear tests show uniformity in machine direction and cross-machine direction. The formation tests indicate a provision of a paper sheet having better coatability and better printability. In other words. basis weight, caliper. tensile tear. Mullen strength. Sheffield smoothness, Gurley densometer. QNS/M formation. Z-direction tensile strength and 7ero span tensile strength tests indicate the resultant more uniform fiber distribution with an elongate relatively narrow upwardly inclined slice chamber having trailing selfpositionable members and a slice lip of the type described above.

Thus. it has been made possible to position the slice opening behind and below the top dead center of the breast roll and yet the jet is received on the wire at a different. more favorable angle than it emerges from the upwardly inclined slice chamber. The relative slope of the headbox lessens the possibility of air being entrapped in the headbox and also makes possible a symmetrical distribution of the thin channels that form between the trailing flexible members 19.

It will be understood that the principles of the invention are not necessarily limited to use with a horizontal forming surface such as provided with a traveling fourdrinier wire. For example. the angle of the stock jet which enters the throat formed between a pair of traveling forming wires in a twin wire machine is critical. The principles of the present invention may be employed to control the angle of stock jet in such a twin wire machine so that the jet engages the wires. and enters the throat of the twin wire machine at the optimum angle. That is. with changes in slice opening. the optimum angle of the stock stream relative to the twin wires can be obtained by adjustment of the slice lip which is constructed in the manner shown in FIG. 1 through 4. Thus. the recitation of the forming surface in the claims is with reference to one of the forming wires when the invention is embodied in a twin wire machine.

We claim: 1. The method of controlling the trajectory angle of stock stream flow through a slice opening in a headbox for delivering stock to a forming surface with the headbox having a first wall and a second wall movable relative to the first forming a slice chamber with a slice opening with the slice chamber being angled relative to the direction of a forming surface and a first slice lip on the first wall and a second slice lip on the second wall and the second lip movably mounted on the second wall. the method comprising:

positioning the second wall from the first wall a dis tance B:

positioning the second slice lip a distance from the first wall a distance I);

positioning the distal edge of the second slice lip a distance downstream toward the forming surface of the distal edge ofthe first slice lip a distance L with the stock jet emitting from between the lips at an angle [3 to the forming surface;

and moving the distal edge of the upper slice lip relative to the first slice lip along line A-A interconnecting the distal edges of said lips with the jet angle [3 remaining substantially constant with the ratio of [2/8 remains constant with the relationship 8 /l. remaining constant to maintain angle B constant.

2. The method of controlling the trajectory of a stock stream in accordance with claim I:

wherein the distal edge of the movable slice lip is moved along an arcuate path.

3. A paper making machine comprising:

a forming surface:

a headbox having opposed first and second slice walls forming a slice chamber with a slice opening for delivering a stock stream to said forming surface;

means supporting said second wall for movement toward or away from the first wall;

a first slice lip at the distal edge of said first wall;

a second movable slice lip at the distal edge of the second wall at the slice opening extending further in the direction of the forming surface than the first lip a distance L;

the distance between said walls at said slice opening being B;

the distal edge of said second slice lip positioned a distance from the first wall a distance I):

the stock flowing through the slice opening at an angle [3 relative to the forming surface with said angle [3 remaining constant while the ratio h/B remains constant;

and support means mounting said second movable slice lip on the downstream edge of the second wall so that it moves with its distal edge moving substantially along a straight line AA defined by a straight line drawn through the distal edges of said lips with the relationship b/L remaining constant to maintain angle ,8 constant.

4. ln a paper making machine constructed in accordance with claim 3:

wherein said forming surface extends substantially horizontal and the slice chamber is inclined upwardly to purge air from the chamber during operation.

5. ln a paper making machine constructed in accordance with claim 3:

wherein said second slice lip is pivotally supported at a pivotal location upstream of the distal edge of said lip.

6. In a paper making machine constructed in accordance with claim 5:

wherein the pivotal support includes a cylindrical member in a seat with means for clamping the cylindrical member in said seat.

7. In a paper making machine constructed in accordance with claim'3:

and including a plurality of trailing flexible members within the slice chamber anchored at their upstream ends with their downstream ends free and self-positionable by the forces of the stock flowing through the slice chamber.

8. In a paper making machine constructed in accordance with claim 3, the combination:

wherein the slice chamber is inclined relative to the forming surface at an angle not less than 3.

9. In a paper making machine constructed in accordance with claim 3:

wherein the angle between said opposed walls of the slice chamber is between 3 and l5.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,902,961 DATED September 2 1975 1 Arnold J. Roerig and Joseph D. Parker It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, line 51, please delete "and" and insert with;

please insert slice between "second" d n ipu 7 line 65, please delete "with" and insert -while-.

Signed and Scaled this twentieth D of January 19 6 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofParents and Trademarks

Claims

1. THE METHOD OF CONTROLLING THE TRAJECTORY ANGLE OF STOCK STREAM FLOW THROUGH A SLICE OPENING IN A HEADBOX FOR DELIVERING STOCK TO A FORMING SURFACE WITH THE HEADBOX HAVING A FIRST WALL AND A SECOND WALL MOVABLE RELATIVE TO THE FIRST FORMING A SLICE CHAMBER WITH A SLICE OPENING WITH THE SLICE CHAMBER BEING ANGLED RELATIVE TO THE DIRECTION OF A FORMING SURFACE AND A FIRST SLICE LIP ON THE FIRST WALL AND A SECOND SLICE LIP ON THE SECOND WALLAND THE SECOND LIP MOVABLE MOUNTED ON THE SECOND WALL, THE METHOD COMPRISING: POSITIONING THE SECOND WALL FROM THE FIRST WALL A DISTANCE B: POSITIONING THE SECOND SLICE LIP A DISTANCE FROM THE FIRST WALL A DISTANCE B: POSITIONING THE DISTAL EDGE OF THE SECOND SLICE LIP DISTANCE DOWNSTREAM TOWARD THE FORMING SURFACE OF THE DISTAL EDGE OF THE FIRST SLICE LIP A DISTANCE L WITH THE STOCK JET EMITTING FROM BETWEEN THE LIPS AT AN ANGLE B TO THE FORMING SURFACE: AND MOVING THE DISTAL EDGE OF THE UPPER SLICE LIP RELATIVE TO THE FIRST SLICE LIP ALONG LINE A-A INTERCONNECTING THE DISTAL EDGES OF SAID LIP WITH THE JET ANGLE B REMAINING SUBSTANTIALLY CONSTANT WITH THE RATIO OF B/B REMAINS CONSTANT WITH THE RELATIONSHIP B/L REMAINING CONSTANT TO MAINTAIN ANGLE B CONSTANT.

2. The method of controlling the trajectory of a stock stream in accordance with claim 1: wherein the distal edge of the movable slice lip is moved along an arcuate path.

3. A paper making machine comprising: a forming surface; a headbox having opposed first and second slice walls forming a slice chamber with a slice opening for delivering a stock stream to said forming surface; means supporting said second wall for movement toward or away from the first wall; a first slice lip at the distal edge of said first wall; a second movable slice lip at the distal edge of the second wall at the slice opening extending further in the direction of the forming surface than the first lip a distance L; the distance between said walls at said slice opening being B; the distal edge of said second slice lip positioned a distance from the first wall a distance b; the stock flowing through the slice opening at an angle Beta relative to the forming surface with said angle Beta remaining constant while the ratio b/B remains constant; and support means mounting said second movable slice lip on the downstream edge of the second wall so that it moves with its distal edge moving substantially along a straight line A-A defined by a straight line drawn through the distal edges of said lips with the relationship b/L remaining constant to maintain angle Beta constant.

4. In a paper making machine constructed in accordance with claim 3: wherein said forming surface extends substantially horizontal and the slice chamber is inclined upwardly to purge air from the chamber during operation.

5. In a paper making machine constructed in accordance with claim 3: wherein said second slice lip is pivotally supported at a pivotal location upstream of the distal edge of said lip.

6. In a paper making machine constructed in accordance with claim 5: wherein the pivotal support includes a cylindrical member in a seat with means for clamping the cylindrical member in said seat.

7. In a paper making machine constructed in accordance with claim 3: and including a plurality of trailing flexible members within the slice chamber anchored at their upstream ends with their downstream ends free and self-posItionable by the forces of the stock flowing through the slice chamber.

8. In a paper making machine constructed in accordance with claim 3, the combination: wherein the slice chamber is inclined relative to the forming surface at an angle not less than 3*.

9. In a paper making machine constructed in accordance with claim 3: wherein the angle between said opposed walls of the slice chamber is between 3* and 15*.