US2116168A - Method of and apparatus for forming a pulp web - Google Patents

Description

May 3, 1938. J. FISH T AL METHOD OF AND APPARATUS FOR FORMING A PULP WEB Filed July 11 1933 m dZfia/m Unkgbr,

Patented May 3, 1938 PATENT OFFICE METHOD OF AND APPARATUS FOR FORM- ING A PULP WEB James Fish, Bristol, Pa.

Berlin, Berlin,

and Arnold John Barea, N. H., assignors to Brown Company, N. H., a corporation of Maine Application July 11, 1933, Serial No. 679,906

6 Claims.

This invention relates to a method of and apparatus for improving the formation of a pulp web on a Fourdrinier wire of a paper-making machine.

Heretofore it has been common practice to impart a lateral shake to the portion of the Fourdrinier wire extending over the table rolls. Thus, the fibers in the pulp stock which flows over the breast roll onto the Fourdrinier wire, and which no tend to aline themselves withthe direction of flow, are agitated in such a way as to cause many of the fibers to assume crisscross positions in the web which is formed on the wire by the drainage of white water from the stock deposited M thereon. Under the best of conditions, however,

the paper sheet resulting from a web thus formed is subjected to ripples or non-uniformity of thickness of sheet, especially in the case of heavy sheets, or of free stock. This can readily be ob- 1served by holding the sheet of paper to the igh Y It is an object of the present invention to improve the uniformity of a heavy paper sheet by the particular kind of agitation of the web arranged to take place at the particular stage in its formation. According to the invention, a liquid sheet of pulp stock is run onto the Fourdrinier wire in the usual manner and may be subjected to the usual lateral shake. As the sheet of stock progresses with the movement of the wire, the lowermost portion of the sheet directly against the face of the wire loses its white water first so that an incipient layer or mat of fiber is formed against the face of the wire before the upper portion of the liquid sheet of stock has lost any appreciable amount of its white water.

At this stage in the formation of the web, the sheet is subjected to a vibration of such a nature as to set up a series of standing waves in the aqueous upper portion of the sheet. This particular type of agitation has the effect of offsetting the tendency on the part of the fibers in the liquid upper portion of the sheet to collect in soft bunches before they are deposited in the pulp web by the escape of the white water by which they are carried. Thus the. fiber distribution in the upper portion of the sheet is such as to result in a substantially uniform paper sheet.

Vibrations adaptedto attain these results may be set up by imparting to the shake rails and the table rolls supported thereby a rapid vertical oscillation of small amplitude, say a few hundredths of an inch. Furthermore, one or more of the table rolls may be omitted at the point where the sheet of stock has lost suflicient white water from its lowermost layer to form a pulp web against the wire While the upper layer of the stock still retains approximately its original consistency. The omission of a table roll leaves a substantial stretch of unsupported wire at this critical point in the formation of the pulp web. The unsupported stretch of wire magnifies the vibrations received through the shake rails and adjacent table rolls so that the stock on this portion-of the wire is strongly agitated in such a 10 manner as to form standing waves of a height many times the amplitude of the vibration. These waves effectively prevent the formation of fiber bunches in the liquid upper portion of the sheet, and break up any bunches of fiberswhich may have collected while traveling from the wet end of the wire to the point of agitation.

For a more complete understanding of the invention, reference may be had to the description thereof which follows and to the illustra- I tion of an embodiment thereof on the drawing, on which Figure l is a side elevation of the wet end of a Fourdrinier paper-making machine, many of the customary parts being omitted to avoid confusion of detail. l I

Figure 2 is an elevation of a portion of Figure 1 on a larger scale.

Figure 3 is a section on the line 3-3 of Figure 2.

Figure 4 is a section on the line li of Fig- 30 .ure 2.

Figure 5 is a section on the line 55 ure-4.

Figure 6 is a section on the line 6-43 of Fig-- ure 2.

As illustrated in Figure 1, the invention may be embodied in the wet end of aFourdrinier papermaking machine which includes afixed base ID from which a number of supporting standards H extend upwardly to support a pair of fixed side bars i2. These side bars support a pair of shake rails which, as indicated in Figure 1, may each consist of two separate parts l4, Ill. The part of Figll of each shake rail, which is nearer to the breast roll I6, is loosely supported for limited vertical movement. To this end, each of the side bars I2 is provided with a number of hangers 11. Each hanger is vertically slotted as at l8 so as to receive therethrough a bolt 20 having a head 50 2|. A spacer block 22 is provided next to the head 2|. This spacer block, if desired, may be integral with the bolt itself. The spacer, block rides in an aperture 23 in the shake rail l4 and cooperates with a nut 25 on. the bolt 20 to clamp supplied to the machine.

a limited free vertical movement on the part of the rail.

The portions ii of the shake rails, remote from the breast roll l6, may be suitably fixed to hangers IT. The shake rails are provided with bearing members 30 for table rolls 3| over which a wire screen 32 extends. The apparatus may be provided with the usual head box 33 and with one or more slices 34. Vertical shaking. movement is imparted to the loosely mounted portions H of the shake rails by any suitable apparatus. As shown, a block 35 is fixed to each shake rail portion l4. Each block contains a socket 36 which cooperates with the upper end 31 of a pitman 38 7 to form a ball and socket joint so as to permit the customary lateral shake. The pitman 38 extends upwardly from an eccentric strap 40 which is mounted on an eccentric member 4|. The eccentric member II is mounted on an eccentric sleeve 42, which in turn is mounted on a drive shaft 43. Since both the members 4| and 42 are eccentric, the amplitude of vibration may be altered by adjusting the angular relation between the two eccentric members so that their eccentricities will either augment or neutralize each other to a greater or less extent according to the angular relation. As indicated in Figures 1 and 2, one or more of the table rolls may be omitted. The particular roll or rolls to be omitted will, in any particular case, depend upon the amount and characteristics of the pulp stock It is desirable to omit a roll at the point where the lowermost stratum of the'stock on-the wire has lost enough of its white waterto form a web on the screen, but the upper stratum of stock is still liquid but is at the point of depositing its fiber on the web which is forming The location of the gap between successive table rolls will depend upon the nature of-the stock employed, a web being formed more rapidly from pulps of somekinds than from pulps of other kinds. In operating the mechanism, the usual horizontal shake may be imparted to the pulp stock by means well known in the art but not herein illustrated. In addition to the customary lateral shake, a vertical shake may be imparted by the eccentric mechanism shown and described, the amplitude of such vibrations being -on either side of the gap- This wire screen is under considerable longitudinal tension, and the vibrations, which are imparted to the screen through the shake rails and table rolls, become considerably amplified in the unsupported stretch of wire over the gap. The vibration of this stretch sets up a train of standing waves in the watery upper layer of the stock on the wire. The resulting agitation of the stock has the effect of uniformly distributing the individual fibers through the upper layer of the stock immediately before they are deposited in the pulp web. Thus heavy sheets can be made of free stock with a high degree of uniformity of distribution of fibers through the entire thickness of the sheet.

Various modifications and changes may be made in the particular embodiment of the invention herein shown and described without departing from the spirit or scope thereof as defined by the following claims.

We claim:

1. In 'a paper-making machine, a breast roll, a pair of shake rails, a series of table rolls journaled on said rails, said rolls being arranged with a substantial gap in the series near the breast roll, and means for vertically oscillating the rails and table rolls in the vicinity of said gap.

2. In a paper-making machine, a Fourdrinier wire adapted to receive dilute pulp stock thereon,

a pair of shake rails, a series of table rolls on said rails supporting said wire, said rolls being arranged with a substantially greater than customary gap in the series near the breast roll at a point where a substantial fraction of the pulp stock on the wire, when the machine is in operation, has drained sufliciently to form a web next to the wire while the upper stratum of stock comprising a substantial fraction of the pulp is liquid, and means for imparting a rapid vertical oscillation to the rails.

3. In a paper-making machine, a supporting frame, a pair of side rails mounted on said frame for limited vertical movement, a series of table rolls j-ournaled on said rails and arranged with a gap in the series near the breast roll at least twice as wide as the usual space between successive rolls at the same place, and means for imparting a vertical oscillation to saidrails and to the table rolls carried thereby.

4. Ina paper-making machine having a breast roll,a stationary support frame, a pair of shake rails supported in said frame, each said rail having two separate parts, the parts remote fromthe breast roll being adjustably fixed to said frame, the parts near the breast roll being loosely supported by said frame for limited vertical movement, table rolls carried by said shake rails, the rolls on the loosely mounted portions of the rails being arranged with a substantial gap between two of the rolls, and means for imparting to said loosely mounted rail portions a vertical vibration of small amplitude.

5. In a paper-making machine, a series of table rolls, a pair of shake rails carrying said rolls and loosely mounted for limited vertical movement. said rolls being arranged with a substantial gap between two of the rolls, and means for imparting vertical oscillation to said shake rails and the.

rolls thereon, said means including a rotatable shaft, an eccentric mounted on said shaft, an eccentric strap on said eccentric, and a pitman connecting said strap and a shake rail.

6. A method of forming a relatively thick pulp web, which comprises removing from a Fourdrinier machine one of the table rolls at a point where a substantial fraction of the stock on the wire has formed a mat and a substantial fraction of the stock still retains its original consistency, operating the machine in the usual manner, and imparting rapid vertical vibrations of small amplitude to the side rails of the machine during such operation.

. JAMES FISH.

ARNOLD JOHN BAREA.

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