US3405031A - Apparatus and method for trimming and removing the edge of a pulp web - Google Patents

Description

3,405,031 VING Oct- 8, 1968 J. B. SISSON APPARATUS AND METHOD FOR TRIMMING AND REMO THE EDGE OF A PULP WEB Filed May 27, 1965 3 Sheets-Sheet 1 m w W James Bryon? Sisson ATTORNEY v J. SISSON 713.. 3,405,031., APPA RATUS AND METHOD FOR TRIMMING AND REMOVING I .5

THE EDGE OF A PULP WEB 3 Sheets-Sheet 2 Filed May 27) 1965 James Bryon! Siaon J. B. SISSON APPARATUS AND METHOD FOR TRIMMING AND REMOVING Oct. 8, 1968 THE EDGE OF A PULP WEB Filed May 27, 1965 3 Sheets-Sheet 5 INVENTOR. James Bryant Sisson ATTORNEY United States Patent O M 3,405,031 APPARATUS AND METHOD FOR TRIMMING AND REMOVING THE EDGE OF A PULP WEB James Bryant Sisson, Hamilton, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio Filed May 27, 1965, Ser. No. 459,209 5 Claims. (Cl. 162-195) ABSTRACT OF THE DISCLOSURE Apparatus and method for defining and removing a trim strip from a wet pulp web on a moving foraminous carrier by defining a trim strip using fluid means, elevating the strip by means of a low velocity water stream which issues from a slot of adjustable length and is directed through the carrier from the underside, collecting the elevated strip with a curviform scoop, and conveying the collected strip to a recycling system.

This invention relates to apparatus and a method for use in the manufacture of paper. More particularly, this invention relates to apparatus and a method for trimming and removing the edge of a web of wet pulp while the web is being transported on a moving, foraminous car ner.

In the manufacture of paper, a pulp-water slurry is evenly deposited on a moving, foraminous carrier or wire and when the excess water is removed the pulp fibers which remain form a fibrous web which is then dried further and calendered, coated or otherwise processed to suit the ultimate use to which the paper will be put. In being so formed, the edges of the web are generally thinner and therefore lighter in weight than the center of the web by reason of the distribution of the fibers transverse the web direction. In this connection, the depth of pulp fibers is relatively uniform across the major (central) portion of the web width but at each edge tapers irregularly outwardly to a complete absence of fibers. Thus, the edges are not only thin but also fail to form a straight line parallel to the direction of web travel.

Various means have been used in the past to trim the web to obtain the desired web width and edge. Among these methods is a so-called squirt, a small diameter, high velocity water jet which flushes away a line of pulp at each'side of the web and thereby severs the thinner, irregular edges from the balance of the web to obtain uniform and straight edges. When this technique is used alone, the severed edges on both sides of the remaining web frequently continue through the papermaking machine, being thereby subjected to further drying, creping, if the paper it to be so treated, calendering or other surface preparation and then is separated for subsequent repulping after which it once again is formed into a web.

As a result of undergoing these various steps in the papermaking process, the emerging edge fibers are oftentimes considerably weaker than virgin fibers by virtue ofhaving undergone the aforementioned processing. In addition, having the trim strips undergo the drying operation increases the cost of the paper so produced since a proportional increase in the amount of steam used to dry the fibers is required in the drying cylinders to provide the requisite drying capacity and also necessitates wider and more expensive processing equipment to accommodate the trim strips.

Removal of the severed edge of a pulp web in wet pulp form has been accomplished by the use of a shower, or large, low velocity stream of water to flush the entire pulp trim strip from the wire. However, this ap- 3,405,031 Patented Oct. 8, 1968 proach frequently results in incomplete edge removal at low water pressures and high water usage, wire edge damage, and undesirable water spray onto the remaining web at high water pressures.

Accordingly, it is a principal object of this invention to provide a pulp web edge trimming and removing method and apparatus wherein the pulp which is separated from the moving web is removed from the forming wire for subsequent redelivery to the white water system for reforming.

Another object of this invention is to provide compact, adjustable apparatus for trimming the edge of a pulp web to a given width and removing the excess pulp from the forming wire.

Still another object of this invention is to provide pulp edge trimming and removing apparatus which utilizes a minimum quantity of water.

Another object of this invention is to provide a method and apparatus for completely removing the separated edges of pulp web in such a way as to eliminate the necessity of drying, creping, or repulping the same and thereby avoid the attendant weakening of the fibers.

Briefly stated, in accordance with one aspect of this invention, apparatus is provided for trimming a wet pulp web to a predetermined width and removing the pulp trim strip before the drying, creping, or repulping operations. The trim strip is separated from the main web by means of a small diameter, high velocity water jet which defines a line of separation between the remaining web and the trim strip. Immediately downstream of the high pressure jet is a low pressure water stream which is directed at the trim strip from beneath the wire on which the pulp fibers are carried and which causes the severed trim strip to be elevated with respect to the wire. A scoop positioned above the wire intercepts the elevated trim strip and directs it laterally from the wire for subsequent collection and recirculation to the pulp slurry reservoir.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter regarded as forming the present invention, it is believed the invention will be better understood from the following description taken in connection with the accompanying drawings in which:

FIGURE 1 is a plan view of the apparatus showing the principal elements thereof in operative relationship;

FIGURE 2 is an end view taken on line 2-2 of FIG- URE 1 and in the direction of web travel;

FIGURE 3 is an isometric, exploded view of the header .for the low pressureelevating stream;

FIGURE 4 is an end cross-sectional view of the collecting scoops taken along line 4-4 of FIGURE 1; and

FIGURE 5 is a perspective view of the scoop assembly with the diverting shield mount partially broken away to show the internal scoop arrangement.

Referring now to the drawings and particularly to FIGURES 1 and 2, there is shown a part of a papermaking machine having a foraminous carrier or wire 10 which supports and transports a web 11 of relatively evenly distributed wet pulp fibers on the uppermost surface thereof. Incorporated on the machine and disposed on either side thereof overlying the outer edges of web 11 is the apparatus of the instant invention, which apparatus is supported by primary water distributing pipes -12 arranged to communicate with a source of water. Since the subject apparatus on each side of the web is the mirror image of the other side, only one side of the apparatus will be described and it is to be understood that this description applies to the remaining side also.

The primary water distributing pipe 12 divides into two branches, one of which, branch 13, forms a header or enclosure from which a low velocity lifting stream issues and the other, branch 14, forms a header or enclosure from which a high velocity severing or separating stream issues. A valve is positioned in branch 13 to regulate the flow therethrough. There is nothing critical about the pipe sizes and those required for particular application of the present invention can be readily determined by one of ordinary skill in the art. The pressure in water distributing pipe 12 is preferably from about 80 to 100 pounds per square inch gage (p.s.i.g.) to provide the high velocity necessary for the severing stream. The pressure downstream of valve 15 is preferably from about 2 to about 10 p.s.i.g.

Emanating from branch 14 is a pipe 16 terminating in a nozzle 17 adapted to provide a relatively thin, substantially circular high velocity stream of water 18. The nozzle 17 overlies the web 11 and is adjustable so that the direction of the water jet 18 issuing therefrom may be changed as desired. Any water flow rate and velocity through the nozzle which will result in a stream of water 18 capable of cleanly severing the web 11 along the desired line of separation will prove satisfactory. The preferred velocity range for severing stream 18 is from about 50 to about 150 feet per second.

Branch 13 underlies the wire 10 and web 11 and its terminal portion 19 is disposed obliquely to the direction of web travel in such a manner that its outer edge is downstream of its inner edge. Terminal portion 19 of branch 13 has a flat section 20 rigidly attached thereto, as by welding, with a slot or aperture 21 extending through the flat section 20 and radially through the terminal portion 19 to provide communication between the interior of terminal portion 19 and the exterior thereof, as is shown in FIG- URES 3 and 4. The upper face of flat section 20 underlies wire 10 and is parallel and immediately adjacent thereto, preferably being in contact with the lower surface of the wire 10. Aperture 21 is parallel to the axis of terminal portion 19 and is disposed directly beneath the edge to be removed from web 11. The lengthwise edges of flat section 20 are sharp and preferably each side is inclined inwardly so as to present an acute angle with the upper face of fiat section 20. The construction precludes the possibility of inducing a hydrofoil effect which could result if the edges were rounded or the sides inclined outwardly. Such a hydrofoil effect is undesirable for this element of the apparatus as it would draw the water and fibers at the edge of the web 11 downwardly, thereby tending to dry that portion of the web and set it more firmly against the wire.

Means is provided to adjust the effective length of opening of aperture 21. As shown in FIGURE 3, one suitable arrangement comprises a hollow sleeve 22, closed at one end and open at the other, which is adapted to slidably fitwithin terminal portion 19 of branch 13 in such a manner as to permit rotation of sleeve 22 with respect to terminal portion 19 but to substantially preclude the passage of water therebetween. Sleeve 22 is of greater length than aperture 21 and is cut axially for about half its length to form a hollow half cylinder. The remaining length comprises a continuous series of steps 23 which form are sections of differing length arranged in helical relationship around the circumference of sleeve 22 and which, collectively, complete the cylinder. An externally threaded rod 24 provided with a squared end 25 is rigidly attached to the closed end of sleeve 22. A plug 26 having an internal thread adapted to mate with corresponding internal threads in terminal portion 19 of branch 13, serves to prevent discharge of water through the end of terminal portion 19. A square nut 27 is afiixed to plug 26 and provides a means for tightening or removing the plug v 4 with the aperture 21 in accordance with the angular position of the sleeve. Thus, the outermost end of the aperture 21 in the interior of the portion 19 will be blocked off by the step 23 in registry therewith and by adjacent solid portions of the sleeve. The length along which the aperture is blocked, and consequently the effectivewidth of the aperture 21, may be varied within a range by adjusting the angular position of the sleeve 22 and the range may be extended by screwing rod 24 out or in so that the effect of registering a specific step is altered by increments equal to the pitch of the thread on the rod.

Cantilevered from branch 14 downstream from aperture 21 and parallel thereto in scoop or collector assembly 28. As shown in FIGURE 4 the scoop assembly 28 comprises a primary scoop 29 of a generally spiral conformation behind which is located secondary scoop 30. The leading edges of the scoops 29 and 30 are preferably about of an inch from the top surface of the wire 10 and the leading edge of primary scoop 29 is immediately downstream of and parallel to aperture 21. The axes of scoops 29 and 30 are parallel to each other and the spacing between the leading edges thereof is preferably between about one to about 6 inches. As is shown in FIG- URE 5, primary scoop 29 has inset portions 34 and 35 therein while secondary scoop 30 has an inset portion 36. These inset portions provide a means of egress for the material collected by the scoops 29 and 30.

Scoops 29 and 30 are rigidly alfixed to outer end plate 31 and inner end plate 32 as by welding. As is shown in FIGURES 1 and 2, end plate 32is approximately vertical and preferably parallel to the direction of web travel shown by the arrow. Scoops 29 and 30 are disposed obliquely to the direction of web travel and parallel to aperture 21. Outer end plate 31 of scoop assembly 28 extends downwardly and outwardly from top to bottom, the inclined surface thereof being adapted to deflect water and fibers impinging thereon in a downward direction.

Branch 14 has scoop support plate 33 welded thereto in such a manner that plate 33 is positioned perpendicularly to wire 10 and is preferably parallel to the directionof travel of web 11. Inner end plate 32 of scoop assembly 28 is attached to scoop support plate 33 as by bolting or other attachment means.

Attached to outer end plate 31 of scoop assembly 28, as by bolts, is diverting shield 37 which is larger in area than end plate 31. Shield 37 is comprised of a pair of rectangular panels which are of equal length but unequal width. The two panels are joined along one of the long edges as by welding, with the two plates forming an obtuse angle with each other. The larger portion mounts to end plate 31 as by the use of bolts and when so mounted, the distal end of the smaller portion projects downwardly and inwardly below the plane of the wire. A further shield 38 interconnects shield 37 with scoop support plate 33 and extends substantially vertically from a point just above the wire 10 to approximately the upper edge of scoop support plate 33.

Flushing nozzles 39 and 40, see FIGURE 1, are mounted to branch 14. Suitable holes are provided in plates 32 and 33 to permit nozzles 39 and 40 to project therethrough so that the nozzles are disposed substantially axially within scoops 29 and 30, respectively. The flushing nozzles are preferred from the standpoint of fiber recovery but are not essential.

Although scoop 29 is shown to have a generally spiral cross-section, this is but the preferred configuration and it is not necessary that this particular shape be used. It is also preferred that the primary scoop 29 be configured and disposed so as to intercept and collect the lifted trim strip and so that the moving wire will generate a reduced static pressure field behind the scoop in order that fibers remaining on the wire may be lifted therefrom.

In the operation of the apparatus, a pulp-water slurry is deposited on the moving wire 10 to form a'web 11 which moves in the direction indicated in FIGURE 1. Downstream of the point where the pulp-water slurry is deposited on the wire is a pair of trimmers of the instant invention disposed on either side of the moving web.

In performing the trimming of the web, the first step involves the severing of trim strips from the balance of the web whereby the resulting web width corresponds to that desired. This definition of the new web width and edge and the severing of the outer edge or trim strip is accomplished by means of high velocity water jet 18 issuing from nozzle 17, which jet serves to wash away the pulp fibers in a thin line, the width of which corresponds to the diameter of the stream. In the embodiment shown, the high velocity stream 18 intercepts the wire 10 at a point immediately above the innermost end of aperture 21. This orientation is merely illustrative since stream 18 may be oriented to sever the web at any convenient point upstream of aperture 21. Nozzle 17 is preferably arranged to direct the web severing jet outwardly to avoid spraying water onto the remaining web.

After being severed from the remaining web, the trim strip is physically separated from the wire by a low velocity stream of water issuing upwardly from aperture 21, which underlies the trim strip, and through wire 10. The effective length of opening of aperture 21 and, therefore, the length of the low velocity stream issuing therefrom is adjustable as described above, to correspond to the width of the trim strip by rotating threaded rod 24 until the desired stream length is obtained. The preferred velocity range for the low velocity lifting stream is from about to about 50 feet per second. To insure the removal of the entire trim strip up to the edge of the remaining web, the innermost edge of aperture 21 should underlie the line of separation between the remaining web and the trim strip. Additionally, although it is possible to space fiat section 20 at a distance from wire 10, the water usage would be increased thereby and the edges of the water stream would not be as sharply defined with the possible result that some edge fibers may not be lifted above the wire.

When the wire is stationary the water stream will pass through the wire virtually unaffected; when the wire is moving, however, the fact that the cells of the wire are continually carrying some of the water away tends to reduce the height of the stream to a point just above the surface of the wire. To the oncoming pulp trim strip, therefore, instead of the stream presenting a wall of water which would block its path, the water forms a pool on the surface of the wire, which pool is positioned in the path of the trim strip and acts as a stationary obstruction thereby causing the pulp to be elevated.

The elevated trim strip is then intercepted by primary scoop 29 which by being disposed obliquely to the web direction as hereinbefore described, permits .the pulp fibers to maintain a velocity component in the direction of web travel, as a result of which they tend to move along the axes of the scoops and away from the web. In the embodiment shown in FIGURES 1 and 2 the acute angle formed by the scoop axes and the direction of web travel is 45 although other angles less than 90 would also be suitable, the angle is preferably in the range of from about 25 to about 90.

A secondary scoop 30 is provided to catch those trim strip fibers that are not intercepted by primary scoop 29. The elevation of the fibers in this case is not by means of a pool of water but by the hydrofoil action of scoop 29. The inclination of the rear surface of scoop 29 induces the moving fibers not intercepted thereby to follow the contour thereof and be caught by scoop 30. This hydrofoil action results in the formation of a reduced static pressure field behind scoop 29 and therefore the higher pressure under wire 10 causes the fibers thereon to be pushed upwardly and onto scoop 30. Shield 38 prevents any water lifted by the hydrofoil action of scoop 30 from splashing onto the web 11. Although preferred from the standpoint of complete recovery of the trim strip fibers, scoop 30 is not absolutely necessary since a majority of the fibers will be intercepted by primary scoop 29.

After entering the scoops the fibers travel generally axially therealong with some spiral motion because of the velocity component in the direction of web travel. They eventually reach the ends of the scoops and either drop through cutouts 34, 35 and 36 therein directly to a collecting chamber (not shown) beneath the wire or are thrown against outer end plate 31 which then directs the fiber-water slurry beneath the wire to the collecting chamber whereupon the slurry is conveyed to a recycling system wherein the recovered fibers are mixed with white water to form a pulp-water slurry suitable for reprocessing. The nozzles 39 and 40 disposed within scoops 29 and 30, respectively, provide a conical spray pattern to aid in flushing any fibers axially along the scoops to outer end plate 31.

Although the apparatus is described as being located immediately downstream of the point where the fiberwater slurry is deposited on the wire, it may be located at any convenient place downstream thereof. The preferred location permits the removal of the fibers before extensive drying of the web has occurred, thereby minimizing the tendency for the fibers to intertwine to a great extent or to form lumps which may not be readily disintegrated and which may form lumps of pulp in the web subsequently formed using such fibers.

It will be apparent that the apparatus described herein is particularly advantageous in high speed paper forming operations since the higher web speeds improve the operation of the collecting scoops. This apparatus has been successfully employed at web speeds up to and including 1750 feet per minute,

Since the entire assembly is cantilevered from Water distributing pipe 12, the width of the trimmed web may be readily varied by moving the assembly transverse the web direction until the desired Web width is obtained. To make small changes in web width, the entire apparatus may be rotated inwardly or outwardly around the axis of pipe 12.

While particular embodiments of the invention have been illustrated and described, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention and it is intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

What is claimed as new is:

1. Apparatus for defining and removing a trim strip from a wet pulp web on a moving foraminous carrier, said apparatus comprising:

(A) fluid means forsevering a trim strip from the pulp web;

(B) an enclosure communicating with a source of water, said enclosure underlying said carrier and including means defining an upwardly directed aperture therein and adjustable means for varying the length of the aperture, said aperture defining means being disposed beneath the trim strip and adjacent to said carrier whereby to permit water issuing therefrom to lift said trim strip from said carrier; and

(C) at least one curviform scoop overlying said carrier and extending across the path of travel of said trim strip, said scoop having its concave surface facing upstream and its leading edge adjacent said carrier immediately downstream of said enclosure.

2. Apparatus for removing a previously defined trim strip from a pulp web on a moving foraminous carrier comprising:

(A) an enclosure communicating with a source of water, said enclosure underlying said carrier and including means defining an upwardly directed aperture disposed beneath the trim strip and adjustable means for varying the length of the aperture, said aperture defining means being adjacent to said carrier to permit water issuing therefrom to pass through said carrier to lift said trim strip therefrom; and

(B) at least one curviform collector downstream of said aperture defining means for receiving said lifted trim strip, said collector overlying said carrier and having an edge immediately adjacent thereto extending across the path of travel of said trim strip.

3. In apparatus for trimming and removing the edge of a pulp web supported by a moving foraminous carrier, including means for severing a trim strip from a main portion of the web and means for collecting said trim strip, the improvement which comprises a water distributing pipe for providing a stream of water of elongated cross-section for elevating said trim strip from said carrier, said pipe underlying said carrier and comprising a cylindrical outer member having an elongated, upwardly directed aperture therein, and an inner member coaxial and rotatable with respect to said outer member, said inner member being a hollow cylinder at one end and having its opposite end of circular conformation but less than a complete hollow cylinder, the portion of said inner member intermediate said ends having a step-like configuration formed by a plurality of arc sections of progressively increasing arc length, as the location thereof approaches said cylindrical end.

4. In apparatus for trimming and removing the edge of a pulp web supported by a moving foraminous carrier, including means for severing a trim strip from a main portion of the web and means for elevating said severed trim strip from said carrier, the improvement which comprises a collecting device for receiving said elevated trim strip, said device having at least One curviform scoop overlying a portion of said carrier and extending across the path of travel of said trim strip, said scoop having its concave surface facing upstream and its leading edge adjacent said carrier and having its axis oriented obliquely to the direction of movement of said carrier with the innermost portion thereof upstream of the outermost portion whereby the collected trim strip travels along said collecting device in a downstream and outwardly direction.

5. A method of trimming and removing the edge of a wet pulp web from the upwardly facing surface of a moving foraminous carrier, said method comprising the following steps:

(A) continuously severing a trim strip from said web along a line parallel to the direction of movement of said carrier;

(B) elevating said severed trim strip from said carrier,

while the balance of the web remains on said carrier, by forming a substantially stationary obstruction comprising a pool of water on the upwardly facing surface of said carrier in the path of said trim strip to lift said trim strip therefrom;

(C) intercepting said elevated trim strip by interposing a stationary collecting member in its path immediately after elevation and while it is moving in substantially the same direction as said wet pulp web; and

(D) conveying the intercepted trim strip to a recycling system wherein said strip is incorporated in a pulpwater slurry.

References Cited UNITED STATES PATENTS 1,945,118 1/1934 McVicker et al 162191 2,727,788 12/1955 Baker 162-275 X 2,954,082 9/1960 Moore 162-191 X 3,232,825 2/1966 Robinson 162203 3,361,620 1/1968 Gedemer 162353 FOREIGN PATENTS 583,482 9/1959 Canada. 500,956 7/ 1930 Germany.

S. LEON BASHORE, Primary Examiner.

Images