US3207658A

US3207658A - Web transfer device for a papermaking machine

Info

Publication number: US3207658A
Application number: US282457A
Authority: US
Inventors: Charles A Lamb
Original assignee: Kimberly Clark Corp
Current assignee: Kimberly Clark Corp
Priority date: 1963-05-22
Filing date: 1963-05-22
Publication date: 1965-09-21
Anticipated expiration: 1982-09-21
Also published as: NL138862B; DE1295349B; GB1060113A; NL6405679A

Description

Sept. 21, 1965 c. A. LAMB 3,207,658

WEB TRANSFER DEVICE FOR A PAPERMAKING MACHINE Filed May 22, 1963 3 Sheets-Sheet l C. A LAMB Sept. 21, 1965 WEB TRANSFER DEVICE FOR A PAPERMAKING MACHINE Filed May 22, 1963 3 Sheets-Sheet 3 United States Patent 3,207,658 WEB TRANSFER DEVICE FOR A PAPERMAKING MACHINE Charles A. Lamb, Watertown, N.Y., assignor to Kimberly- Clark Corporation, Neenah, Wis., a corporation of Delaware Filed May 22, 1963, Ser. No. 282,457 9 Claims. (Cl. 162-306) The invention relates to papermaking machines, partic ularly of the Fourdrinier type, in which a slurry of fibers and Water is spread evenly upon the surface of a moving forming fabric or wire so that water drains from the slurry through the fabric to form a moist web thereon, and in which the moist web is picked up off or transferred from the fabric to a felt that carries the web to a drying section of the machine, preferably through a press section of the machine. More particularly, the invention relates to an improved pickup mechanism for picking up or transferring the moist web from the fabric to the felt.

Previously, two principal forms of pickup apparatus have been in general use for transferring the moist web from a Fourdrinier forming fabric to the associated felt. The more conventional one of these forms of pickup apparatus is the so-called solid pickup type which comprises a pickup roll having a nip with a couch roll. The couch roll is one of those rolls supporting the loop of F ourdrinier fabric, and the pickup roll is one of the supporting rolls for the felt, so that both the forming fabric and felt pass through the nip of these two rolls.

It is necessary to have pressure between the pickup and couch rolls in order to pick up the web from the Fourdrinier fabric and transfer it to the felt, such pressures being on the order of to pounds per square inch. With such pressures, reasonably good transfer of the moist web from the Fourdrinier fabric to the felt is obtained; however, this pickup arrangement has certain disadvantages, one of which concerns the crowning of the couch and pickup rolls. Unless the crowning is absolutely correct, there is crushing of the sheet either in the center of the web or on the edges of the web. Thus the crowning must correspond to the pressures being used between the two rolls, inasmuch as the rolls deflect more or less with the nip pressures between them. Also, it is necessary in order to obtain acceptable results that the couch roll have a drilled periphery, with a multitude of radially extending holes in its surface, or else be of the so-called Harper type having grooves in the roll surface. These drillings or grooves provide spaces in which water may migrate as the two rolls squeeze the web during the pickup process; however, due to the drillings or grooves, sheet marking is quite likely to occur; and, in addition, such drilled or grooved rolls are quite expensive. These drillings or grooves also tend to become plugged and thus change the sheet characteristics, and also the nip of the pickup roll with such a couch roll is more likely to damage the fabric or felt than if a smooth couch roll were used.

The other principal form of pickup apparatus is the socalled free wire type pickup. This apparatus as ordinarily used includes a pickup roll which has a nip with a free stretch of the Fourdrinier fabric extending between two spaced rolls, such as a couch roll and a tail roll. The pickup roll, similar to the pickup roll used in connection with the solid type pickup apparatus, forms one of the supporting rolls for the felt loop; and, due to the relatively great widths of papermaking machines in general use of 150 to 200 inches, the pickup roll has had a diameter of at least 14 inches to have the necessary rigidity. This type of pickup apparatus has the advantage over the solid type that a relatively expensive drilled or Harper type couch roll need not be used, since the pickup iCe roll has no pressure nip with the couch roll; and the marking of the sheet due to such a couch roll does not occur. The performance of the free wire pickup apparatus .is thus better in these respects; however, it also has certain disadvantages. Inasmuh as the reach of forming fabric, with which the felt bearing pickup roll is in bearing relationship, is unsupported directly opposite the pickup roll, and the pickup roll has a relatively large diameter of 14 inches or more to overcome excessive bending, it is not possible to obtain the high unit nip pressures between the forming fabric, the felt, and the pickup roll that are obtained with the solid type pickup apparatus. I have found that the quality of pickup, more particularly, the proportion of the Web that is picked up by the felt from the forming fabric, is somewhat proportional to the nip pressures that are utilized and, therefore, this proportion is less than with the solid type pickup apparatus, so that the sheet tends to become more perforate, holey and nonuniform, and the general sheet quality is lower.

It is an object of the present invention to provide an improved free wire pickup apparatus for a papermaking machine by means of which higher unit pressures between the felt and the forming fabric are obtained than with prior pickups of this type, so that a higher proportion of the web is removed from the forming fabric and is transferred to the felt. More particularly, it is an object of the invention to provide a bearing member for holding the felt in contact with the forming fabric which has a radius of curvature substantially less than the pickup rolls previously used for thereby increasing the unit pressures between the felt and wire at the point of pickup and increasing the proportion of the fibers that are transferred to the felt. It is also an object of the invention to provide such a bearing member that is non-rotatable so that it may be easily designed to have above mentioned small radius of curvature.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects, and such other objects, as will be apparent from the follow ing description of preferred forms of the invention, illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a fragmentary diagrammatic illustration of a papermaking machine of the Fourdrinier type and, more particularly, of the portion of the machine including the terminal end of the forming fabric and the pickup end of the felt with a pickup cam being provided that is effective on the felt and fabric for holding them together with a pressure nip;

FIG. 2 is a side view of a modified type of pickup cam device;

FIG. 3 is an end view of the cam device illustrated in FIG. 2;

FIG. 4 is a side view of another, modified cam device in contact with the pickup felt and forming fabric;

FIG. 5 is a side view of still another form of pickup carn having a very small radius roller in its tip;

FIG. 6 is a cross sectional view on an enlarged scale of the cam illustrated in FIG. 5;

FIG. 7 is a plan view of the small radius roller cam device and mechanism for driving the roller;

FIG. 8 is a side view of the mechanism for driving the roller; and

FIG. 9 is a side elevational view on an enlarged scale showing the small radius roller effective on the felt and wire.

Like characters of reference designate like parts in the several views.

Referring now to the drawings and in particular to FIG. 1, the paperm ak-ing machine fragmentarily illustrated therein may be seen to comprise an endless Fourdrinier fabric belt or wire 16 that is supported in looped form by means of a plurality of rolls having parallel axes, the rolls including a couch roll 11 and a turning roll 12. At least one of the rolls supporting the fabric is driven, so that the fabric moves about the rolls as indicated by the arrow 13. A conventional stock supply system and stock inlet are provided in connection with the Fourdrinier wire for depositing a slurry of fibers and Water onto the fabric 10, so that the water drains through the openings in the fabric and provides a paper web 14 on the fabric 10 which is substantially continuous but is quite wet when it reaches the turning roll 12.

The papermaking machine also includes an endless pickup felt 15 held in the form of a loop by a plurality of supporting rolls including rolls 16, 1'7, and 18. The pickup felt passes between the rolls 19 and 20 of a main press 21, and a bottom felt 22, which is endless and which is sup-ported by means of a plurality of supporting rOlls (not shown), also passes through the nip between the rolls 19 and 20 along with the felt 15. The arrangement of the bottom felt, the press and the top felt are conventional, and, therefore, it is deemed that further illustration in the drawings is not necessary. The web 14 transfers from the fabric 10 onto the bottom surface of the felt 15 at a line of contact of the fabric and felt and passes through the main press to the drier section of the papermaking machine which also is conventional and is therefore not illustrated. The main press 21 is the principal part of the press section of the machine for effectively dewatering the web 14, and the web 14 is eventually dried by the drier section (not illustrated) of the machine.

The pickup felt 15 is maintained in forceful contact with the forming fabric 10, on a free run or stretch of the fabric 115 between the rolls 11 and 12, by means of a pickup cam 23 that bears on the felt 15 and also bears on the fabric 11) through the intermediary of the felt 15 and web 14. The cam 23 extends across the machine and is in contact with the felt 15 for its complete width. The cam 23 is supported by means of a pair of opposite journals 24 that fit in a pair of suitable side supports (not shown) that are fixed with respect to the machine frame, and the cam 23 is fixed in a selected rotated position by any suitable fastening mechanism (not shown).

The cam 23 has a plurality of curved peripheral portions (1, b, and c which have different radii. The peripheral portions a, b, and c (the port-ion b being illustrated in contact with the felt 15) may respectively have 3", 1 /2, and /4 radii, for example. Alternatively, the surface of the cam 23 in cross section may be in the shape of a spiral with continuously varying surface radii, such spiral surface including the illustrated portions a and b, for example. The cam 23 may selectively be rotated and fixed so that any of its curved peripheral portions may be disposed in contact with the felt 15 and hold it forcefully against the fabric 10.

The cam device 25 illustrated in FIG. 2 may be utilized in lieu of the cam 23 for holding the felt 15 forcefully in contact with the fabric 11). The device 25 comprises four

rods

26, 27, 28, and 29 fixed on four corners of a boxlike structure 30. The

rods

26, 27, 28, and 29 may have diameters of 1 /2 inch, 1 inch, /2 inch and 4 inch, respectively. The structure 30 comprises 4

plates

31, 32, 33, and 34, a pair of square ends and 36 and a plurality of spaced square ribs 37. The parts 31 to 37 may be Welded together to form the structure 39. A shaft 38 passes through the structure 313 and into a pair of standards 39 located on opposite ends of the structure 31) for supporting the structure 30 with respect to the frame of the machine. The structure 31) is selectively fixed in any one of four positions so as to have any one of the shafts 26 to 29 in contact with the felt 15 for holding it forcefully against the fabric 10, being held in such different positions, for example, by means of pins 40 that extend through the standards 39 and into the

adjacent end plates

35 and 36.

The cam 41 illustrated in FIG. 4 may be substituted for the cam 23 and is held by any suitable mechanism in proper position to hold the felt 15 forcefully against the fabric 10 along a line across the fabric between the rolls 11 and 12. The end of the cam 41 effective on the felt has two portions d and e of curvatures which are different and have radii of 3 inches or less. The portions d and e contact and are effective on the felt for providing a nonuniform pressure of the felt 15 on the fabric 10 as will be subsequently described.

The pickup cam device 42 illustrated in FIG. 5 may be substituted for the cam 23 and comprises a rod or roller 43 that bears on the felt 15 and holds it forcefully against the fabric 10. The rod 43 may have a diameter of /2 inch, for example. The roller 43 extends for the complete width of the felt 15 and is rotatably disposed in a roller holder 44 of substantial cross sect-ion. The holder 44 is provided with a pair of journals 45 on opposite ends by means of which the holder 44 is held in position.

The roller 43 is preferably rotated during operation of the machine so that the roller surface in contact with the felt 15 moves in the same direction as the felt, and this may be done by means of the driving apparatus illustrated in FIGS. 7 and 8. The driving apparatus comprises a motor 46 having a pulley 47 mounted on its output shaft. A pulley 48 is mounted on the end of the roller 43, and a belt 49 drivingly connects the

pulleys

47 and 43.

I have found that if the felt 15 is made to bear on a free run of the fabric 10, as between the rolls 11 and 12, with greater unit pressures than are obtainable with the 14-inch pickup roll previously used, more complete and better pickup of the sheet 14 from the wire 10 is obtained. I have also found that such high unit pressures with the better resultant pickup may be obtained by using the relatively sharply curved cam sections a, b, and c, illustrated in FIG. 1, which have relatively short radii compared to the 7-inch radius of the conventional 14-inch pickup roll. These sharply curved surfaces may be provided effective on the felt 15 due to the fact that the cam 23 is a solid member and it, therefore, has the necessary rigidity which will not allow substantial flexing of it even though it may be to 200 inches long. The small diameter rods 26 to 29 in the FIG. 2 cam mechanism, the small diameter rod 43 in the FIG. 5 pickup mechanism, and the sharply curved FIG. 4 cam device also have this advantageous function of providing more complete pickup from the Fourdrinier fabric to the felt for the same reasons, and each of these cam devices is supported with rigid structure so that there is no substantial flexing.

Mathematical calculations show that the pressure of any of these cam surfaces or of a conventional large diameter pickup roll on the felt 15 and fabric 10 in a free wire pickup arrangement varies directly with the wire tension and inversely as the diameter of the pickup roll or cam surface holding the felt and wire in contact. It is undesirable, of course, to unduly increase the Wire tension since this would cause undue wire wear and breakage; and so, therefore, in order to increase the unit pressure of the felt on the forming fabric, which I have found to cause a higher degree of pickup, I have provided the relatively sharp cam or roller surfaces effective on the felt. The pressure of a solid pickup roll acting directly on a couch roll in a conventional solid pickup may be on the order of 5 to 15 pounds per square inch. On the other hand, due to the limitation on wire tension that should be observed, a conventional free wire pickup roll may provide a pressure of only approximately two pounds per square inch. With the sharply curved cam surfaces or roller above described, the high unit pressures of 5 to 15 pounds per square inch may be provided with a free wire pickup arrangement to increase the amount of pickup without, however, the resulting disadvantages of conventional solid pickup arrangements.

I have mentioned the relatively sharp cam surfaces of 4 inch, 1 inches and 3 inches radius in connection with the cam 23 in the FIG. 1 form of free wire pickup arrangement and have described the Ar-inch diameter to 1 /2 inch diameter rods 26 to 29 in connection with the FIG. 2 pickup mechanism, thus illustrating that curved cam surfaces having radii of /8 inch to 3 inches are satisfactory for providing the more complete free Wire pickup in accordance with the invention. Curved cam surfaces having radii smaller than A; inch are also contemplated; however, it is apparent that the cam surfaces shall not be so sharp as to sever the felt 15 or to break the fibers in it causing rupture. Theoretically, a knife edge would provide the highest unit pressures and the most complete pickup in a free wire pickup arrangement in accordance with the principles of the invention; however, a compromise curved surface of inch radius is contemplated in lieu of an actual knife edge which would cause felt rupture.

A number of different hypotheses may be advanced to explain the fact that more complete pickup of the sheet from the fabric to the felt is obtained using the small radii cam surfaces that are herein proposed. It is known that in using a 14-inch diameter pickup roll in a conventional free wire pickup arrangement, there is approximately a 4-inch wide bead or band of water existing beneath the wire at the line of pickup. The bead of water is directly underneath the line at which the felt and forming fabric come together. Using a cam according to the invention with a 3-inch radius, this band of water decreases to /z-inch width and it further decreaes to A1- inch width using a 1 /2 inch radius cam surface. With a 4-inch radius cam surface, approximately a /s-inch wide band of water exists.

The hypotheses that explain the more complete pickup obtained with the small radii cam surfaces concern this bead of water that exists beneath the wire along the line of separation of the formed web from the forming fabric. According to one hypothesis, this bead of water is sucked up into the felt by capillary action, as the felt separates from the forming fabric substantially along the line of pickup, and pulls the paper web along with the water. Thus, with this hypothesis, the Water is first pushed out of the felt by compression by the small radius cam surface, and the water is then reabsorbed into the felt as soon as the compression is released to pull the web onto the felt. Assuming the same lineal loading of the cam 23 or rods 26 to 29 in all cases, that is, assuming the same total forces are used in all cases on the pickup cam or roller, obviously the pressure of the felt 15 on the forming fabric 10 is more intense using smaller radii cam or roller surfaces in contact with the felt. With these higher pressures developed with the small radii cam or roller surfaces, more water is squeezed from the felt 15 at the exact point of pickup, and thus there is a greater effect of the water in providing a complete transfer of the sheet to the felt, this improved action being obtained without adding Water to the felt as a whole so that water consumption insofar as the felt 15 is concerned is less. Incidentally, it is well recognized that with either the conventional solid pickup or the conventional free wire pickup, improved sheet pickup is more easily achieved if a relatively wet paper sheet or a relatively wet felt is used. One of the expedients used by experienced papermaking machine tenders, if trouble with pickup is being bad, is to add water on the pickup felt making it wetter. Utilizing the small radius cam or rollers of the invention, this expedient need not be resorted to. It is also reasoned that the felt is compressed by the high unit loading of the small radius cam or roller; and, as the felt moves out on the trailing side of the line of contact of the felt and fabric, the felt instantaneously expands. Obviously the higher the loading on the felt by the small radii cam surfaces, the more the felt will expand. In expanding, the felt draws the bead of water into the felt by capillary action and pulls the web, along with the water up into tight contact with the felt and maintains it on the felt.

Another hypothesis advanced also concerns the greater amount of water at the line of pickup. It is hypothesized that there is a tendency to develop a vacuum at the outgoing side of the nip between the felt and wire, the vacuum being between the sheet and the felt or between the sheet and the Wire. Since atmospheric pressure is present on the bottom side of the forming fabric and the fabric is porous, air flows through the fabric so that the vacuum effect is relieved between the sheet and fabric. The vacuum between the sheet and felt on the other hand is not readily relieved, since air does not pass easily through the felt, it being understood that the felt is much denser than the forming fabric. The sheet thus is pulled from the forming fabric and onto the felt and tends to adhere to the felt. The density of the felt is greater when the felt is wet, and the bead of water at the line of separation of felt and wire keeps the felt wetter at exactly the place increased felt density is desired to decrease the air flow through the felt, so that the vacuum between the felt and web is increased to provide a more complete pickup of the web.

FIG. 9 may be referred to for a showing of a small radius roller or cam surface, such as the roller 43 or the cam surfaces a, b, and c, for example, forcefully holding the belt 15 against the wire 10. It will be observed that the roller or cam surface materially compresses the felt and decreases it in thickness between the cam surface and fabric 10 and that a water head A is formed beneath the fabric 10. The water bead has its greatest thickness at the point of maximum compression of the felt, which is actually the line of transfer of the sheet 14 to the felt.

The unit pressure of the felt 15 on the fabric 10 may be easily varied by rotating the cam 23 so that any of the relatively sharp, short radius, cam surfaces a, b, and c bear on the felt. The cam device 25 illustrated in FIG. 2 may be similarly adjusted, so that any of its different diameter rods 26 to 29 may be made to bear on the felt. The FIG. 4 form of cam 41 may be utilized in the event that it is desired to cause the unit pressures to increase relatively slowly as the web travels over the relatively long radius surface d and thence over the sharper surface e.

The form of cam 42 illustrated in FIGS. 5 to 8 may be utilized for the purpose of reducing the amount of felt wear by the relatively small radius cam surface taught by the invention. It will be understood that the small radius roller 43 is actually effective on the felt 15 in the same manner as are the

small radius rods

26 and 29, for example; and, in this case, flexing of the roller 43, which itself is flexible, is avoided due to the relatively massive backing part 44 provided for the roller 43.

The free wire pickup utilizing the small radius roller 43, the small radius cam portions a, b, and c, the small diameter rods 26 to 29, or the part 41 in the FIG. 4 embodiment, provide all of the advantages above mentioned for free wire pickups as contrasted to solid pickups, such as the lack of necessity for the use of a drilled or Harper couch roll which is quite likely to mark the sheet, to plug causing pickup problems, and to damage the forming fabric or felt. The small radius cam surfaces or roller 43, in addition, provide improved sheet quality, less fiber losses and better appearance of the sheet, since the small radius cams or roller provide higher unit pressures between the felt and fabric. The small radius surfaces also allow less stream pollution in View of the fact that a greater proportion of the fibers are taken from the forming fabric and transferred to the felt. With conventional pickup apparatus, either of the solid type or free wire type, the top felt ordinarily is saturated with water in order that a high proportion of the fibers is transferred to the felt at the line of pickup;

however, using the small radius cam surfaces of the invention, only as much water now is required for the felt as is necessary for maintaining the felt clean. There is thus less water consumption using the invention. Another advantage of the present invention lies in the fact that the tension of the forming fabric may be decreased providing an increased fabric life while still obtaining a more thorough pickup and transfer of the sheet to the felt. By selectively using the different radius cam surfaces a, b, and c or the different diameter bars 26 to 29, the unit pressure between the felt and the wire may be varied as desired, in order to obtain the desired pickup or transfer of the sheet to the felt.

The small radii cam surfaces of the invention are useful in connection with many various weights of sheet. In particular, the invention is useful in all cases in which a contact type pickup arrangement is ordinarily used, that is, a free wire pickup or a solid pickup as contrasted to an open draw. Contact type pickups are very often used in connection with tissue weight sheets of 5 to pounds per 2880 square feet although they are sometimes used for thicker webs, and the invention is useful for all such basis weights.

Actual trials have indicated that as the radius of the pickup cam is decreased, a greater proportion of the fibers is transferred from the forming fabric to the felt. For example, using a inch radius cam surface, it was found in a certain trial that 3.08 percent of the sheet was lost at the line of pickup; with a 1 /2 inch radius cam surface, 3.25 percent of the sheet was lost; and with a 3-inch radius cam surface, 3.45 percent of the sheet was lost. The tension of the wire is important, of course, since it determines, along with the radius of the pickup cam, the unit pressure applied by the pickup cam; but it is not desirable to unduly increase the wire tension since this results in short wire life. A wire tension of pounds per lineal inch is considered about normal. With such a wire tension, using a small radius cam surface according to the invention, it has been found only necessary to simply kiss the wire with the felt, depressing the wire only about .0087 or .010 inch from its normal travel intermediate its supporting rolls, such as the rolls 11 and 12.

Incidentally it has been found that the angles at which the felt 15 and fabric 10 separate from each other, either at the incoming or outgoing side of the nip of the felt I5 and fabric 10 at the line of pickup beneath the small radius cam surface, are not critical and may be varied, with the same high percentage of pickup existing and while providing a uniform sheet. Also, it has been found unimportant to have a large area of contact of the felt and wire at the line of pickup; in fact, reducing the radius of curvature of the cam surface holding the felt and wire in contact with less such area may be expected to produce a more perfect pickup utilizing the same wire tension, since the unit pressure between the felt and wire at the line of pickup is thereby increased.

I wish it to be understood that the invention is not to be limited to the specific constructions, arrangements and devices shown and described, except only insofar as the claims may be so limited, as it will be apparent to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1. In a papermaking machine, an endless perforate belt for draining a slurry of fibers and water deposited on the belt to form a moist paper web on the belt, a plurality of rolls for rnovably supporting said belt, an endless felt, a plurality of rolls for movably supporting said felt, and a guide member extending transversely across said felt and having a curved peripheral surface which has a radius of curvature of less than 3 inches and is in contact with the felt and holds the felt in contact with said perforate belt so that the moist web is picked up by the felt from the perforate belt and transfers to the felt.

2. In a papermaking machine, an endless perforate belt for draining a slurry of fibers and water deposited on the belt to form a moist paper web on the belt, a plurality of rolls for movably supporting the belt and including a pair of rolls providing an unsupported stretch of the belt between them, an endless felt, a plurality of rolls for movably supporting the felt, and a guide member extending transversely across the felt and holding the felt in a line of contact with said unsupported stretch of said perforate belt, said guide member having a curved peripheral surface with a radius of less than 3 inches in contact with the felt whereby the moist web is relatively cleanly picked up by the felt from the perforate belt and transfers at said line of contact to the felt.

3. In a papermaking machine, an endless perforate belt for draining a slurry of fibers and water deposited on the belt to form a moist paper web on the belt, a plurality of rolls for movably supporting the belt and including a pair of rolls providing an unsupported stretch of the belt between them, an endless felt, a plurality of rolls for movably supporting the felt, and a rigid stationary cam member extending transversely across the felt and holding the felt in a line of contact with said unsupported stretch of perforate belt, said cam member having a stationary curved peripheral surface in contact with the felt and holding it in contact with said perforate belt, said curved per-ipheral surface having a radius of curvature of three inches or less for providing a relatively clean pickup and transfer of the moist Web from the perforate belt to said felt at said line of contact.

4. In a papermaking machine, an endless perforate belt for draining a slurry of fibers and water deposited on the belt to form a moist paper web on the belt, a plurality of rolls for movably supporting the belt and including a pair of rolls providing an unsupported stretch of the belt between them, .an endless felt, a plurality of rolls for movably supporting the felt, and a guide member having a plurality of peripheral curved surfaces of different radii of curvature for holding the felt in a line of contact with said perforate belt so that the moist web is picked up by the felt from the perforate belt, said guide member being selectively adjustable to position said different curvature surfaces in contact with the felt, said curved surfaces having radii of curvature which are between Ms inch and 3 inches.

5. In a papermaking machine, an endless perforate belt for draining a slurry of fibers and water deposited on the belt to form a moist paper web on the belt, a plurality of rolls for rnovably supporting the belt, an endless felt, a plurality of rolls for movably supporting the felt, and a guide member extending transversely across the felt and holding the felt in a line of contact with said perforate belt so that the moist web is picked up by the felt from the perforate belt and transfers at said line of contact to the felt, said guide member comprising a stationary rigid backing member and a small diameter roller disposed in the tip of said backing member and in contact with the felt for holding the felt and perforate belt together at said line of contact.

6. In a papermaking machine, as set forth in claim 5, said roller having a diameter between inch and inch.

'7. In a papermaking machine as set forth in claim 5, and driving mechanism for rotating said roller to have a peripheral movement in the same direction as the felt in contact with the roller.

'8. In a apermaking machine, an endless perforate belt for draining a slurry of fibers and water deposited on the belt to form a moist paper web on the belt, a plurality of rolls for rnovably supporting the belt and including a pair of rolls providing an unsupported stretch of the belt between them, and endless felt, a plurality of rolls for rnovably supporting the felt, and a stationary guide member extending transversely across said felt and holding the felt in a line of contact with said perforate belt so that the moist web is picked up and transfers, to the felt from 9 10 the belt, said guide member having a tip which is in con- References Cited by the Examiner tact with the felt and holds the latter in contact with said perforate belt and which has two substantially different UNITED STATES PATENTS radii of curvature in contact with the felt along said lin 334,072 1/86 Edwards 162306 of contact. 5 1,352,611 9/20 Ladd et a1 162-358 9. In a papermaking mac-hlne as set forth in clalm 2,694,346 11/54 Goodwillie 1 62-306 each of said different radii of curvature being less than 3 inches. DONALL H. SYLVESTER, Primary Examiner.

Claims

1. IN A PAPERMAKING MACHINE, AN ENDLESS PERFORATE BELT FOR DRAINING A SLURRY OF FIBERS AND WATER DEPOSITED ON THE BELT TO FORM A MOIST PAPER WEB ON THE BELT, A PLURALITY OF ROLLS FOR MOVABLY SUPPORTING SAID BELT, AN ENDLESS FELT, A PLURALITY OF ROLLS FOR MOVABLY SUPPORTING SAID FELT, AND A GUIDE MEMBER EXTENDING TRANSVERSELY ACROSS SAID FELT AND HAVING A CURVED PERIPHERAL SURFACE WHICH HAS A RADIUS OF CURVATURE OF LESS THAN 3 INCHES AND IS IN CONTACT WITH THE FELT AND HOLDS THE FELT IN CONTACT WITH SAID PERFORATE BELT SO THAT THE MOIST WEB IS PICKED UP BY THE FELT FROM THE PERFORATE BELT AND TRANSFERS TO THE BELT.