US1881912A - Method of and apparatus for making multiply paper - Google Patents

Description

H. PARKER Oct. 11, I932.

METHOD OF AND APPARATUS FOR MAKING MULTIPLY PAPER Filed Oct. 28. 1930 Patented Oct. 11, 1932 UNITED STATES PATENT OFFICE HOWARD PARKER, OF BERLIN, NEW HAMPSHIRE, ASSIGNOR TO BROWN COMPANY, 01' BERLIN, NEW HAMPSHIRE, A CORPORATION OF MAINE METHOD OF AND APPARATUS FOR MAKING MULTIPLY PAPER Application filed October 28, 1980. Serial No. 481,781.

This invention relates to an improved method of and apparatus for makingl multiply paper. The apparatus, as a who e, is of the type illustrated and described in my Patent No. 808,614, issued December 26, 1905. The apparatus therein described consists of a pair of cylinder molds each having a couch roll and an endless felt on which the pulp web can be picked up from each mold as soon as it is formed. The two felts are brought together on a suction roll in such a manner as to bring the two pulp webs into interfacial contact. The united felts then pass between the suction roll and a press roll which bears thereon. This causes a firm interfelting of the two pulp webs into a single sheet which is thereafter dried to form a strong paper sheet.

In the patented apparatus the two felts are brought together on the suction roll at a point in advance of the nip between the suction roll and the press roll. Since the felts must be driven at equal linear speeds so as to pass between the suction and press rolls, and since the radius of curvature of the outer felt on the suction roll is greater than the radius of curvature of the inner felt against the surface of the suction roll, a certain amount of n ative longitudinal sliding motion inevitably takes place between the portions of the two felts against the suction roll so that wrinkles or unevenness result in the pulp web between the felts. In order to overcome this ditliculty, the outer felt is guided, according to the present invention, so that it reaches the suction roll at the nip between the suction roll and the press rol The two felts thus come together for the first time in the nip between the rolls. This obviates all longitudinal slipping of one felt on }t)he other and results in a uniform finished we In leading the felts together in such a way that they meet at the nip between the press rolls, certain difficulties may be encountered owing to the fact that the pulp web which is formed on the cylinder mold and which is picked up therefrom by felt, contains a high percentage of water. This may be in the neighborhood of eighty per cent of water to twenty per cent of pulp, although the percentage varies considerably with the nature of the pulp and the manner in which it is deposited on the mold. A pulp web with this percentage of moisture is exceedingly weak and heavy due to the presence of the water therein. Such a web when on the under face of a felt will not adhere to the felt unless the felt is at a suflicient angle to the horizontal. If, therefore, one of the two felts reaches the nip between the press rolls in a substantially horizontal position with the pulp web on its under face, either the pulp web must be exceedingly thin or a considerable portion of the water therein must first be removed before the felt reaches the horizontal stretch. As it is desirable to be able to form plies of substantial thickness, I remove a considerable pro ortion of the water from the pulp web be ore the web is supported on the under face of the horizontal stretch of the felt. To this end I may extend the felt from the couch roll on the mold upwardly at a steep angle to a hollow guide roll which is covered with the customary wire screen. The pressure between the felt and this roll is considerable as there is a heavy tension on the felt due to the drag of the cylinder mold and other portions of the apparatus which are driven by the felt. This results in a considerable pressure between the felt and the hollow roll which squeezes some of the water from the pulp web into the roll and through the felt. At the point where the felt and web leave this hollow roll, 1 place a suitable suction box on the upper face of the felt to pick up the water which has been squeezed throu h to that surface, to suck additional water rom the pulp web through the felt, and to prevent the web from leaving the felt and clinging to the roll. As the roll is wire covered and thus presents a rougher surface than the felt, the web would naturally cling to the felt rather than to the roll, but as the web still retains a fairly high percentage of moisture, it is safer to employ suction at the point where the felt leaves the roll in order to avoid the possibility of the web following the roll rather than the felt at this point.

For a more complete understanding of the invention reference may be had to the description thereof which follows and to the drawing of which,

Figure 1 is a diagrammatic view of mechanism embodying the invention.

Figure 2 is a sectional view on a larger scale showing certain details of structure of ,the guide roll and suction box illustrated in Fi re 1.

eferring to the drawing in detail, 10 re resents a pulp vat which may include apa1r of compartments 11 and 12. In these res ective compartments a pair of cylinder mol s 13 and 14 are mounted. On the mold-13 a couch roll 15 ma be provided, a similar r0ll'16 being rovi ed for the mold 14. Between the mol 13 and its couch roll 15 an endless felt 20' is passed so as to pick up the pulp web which has been formed on the mold 13. In like manner a second felt 21 passes between the mold 14 and the couch roll 16. As shown, the felt 21 passes directly from the couch roll 16 to a suitable suction roll 22, the specific construction of such rolls being well known in the art. The felt 21 passes about a considerable arc of the suction roll 22 and through the nip between this roll and a press roll 23 which bears upon the suction roll. According to the invention, a guide roll 24 is provided for the felt 20 so that this felt, upon caving the couch roll 15, passes over the guide roll 24, the latter being arranged so that the felt 20 enters the nip between the rolls 22 and 23 substantially in the direction of the common tangent to the two rolls, so that the initial point of contact between the two felts is in the nip between the suction and press rolls. This avoids any possibility of longitudinal slipping between the two felts. The final product is thus of uniform thickness and is free from the wrinkles or irregular thickness which characterized a multi-pl sheet in which the original plies were carrie together felts having relative longitudinal slip.

b Since the web of pulp carried upwardly from the couch roll 15 by the felt 20 contains a high percentage of water, this portion of the felt must be steepl pitched as otherwise the pulp would fall rom its face. Since the portion of the web 20 between the roll 24 and the rolls 22 and 23 is substantially horizontal, a considerable portion of the water content of the web must be removed before it can be carried successfully on the under face of this portion of the felt. T 0 this end the roll 24 is preferably made hollow and is covered with the customary wire screen used on cylinder molds. As the web is passed between the felt 20 and the roll 24 in passing around the latter, a portion of its water is squeezed into the roll through the wire screen on its surface, and is drained off. The amount of wa ter thus removed may be sufiicient to enable comparatively thin webs of pulp to adhere to the under side of the horizontal stretch of felt. By removing more of the water content of the web a much heavier web may be carried by the felt. To this end I may apply a suction box 30 to the upper surface 0 the felt 20 as it leaves the roll 24. This removes a considerable portion of the water in the web and also holds the web to the felt as it leaves the surface of the roll.

When the web on the felt 20 reaches the nip of the rolls 22, 23, it is then considerably drier than the web on the felt 21 which it then joins. The wetter web which is nearest to the suction roll 22 thus has at the moment a looser structure than the drier web upon it. As water in the webs is sucked downwardly therethrough, fiber ends of the upper web are washed into interfelting relationship with the looser web beneath so that the two webs are more strongly interfelted than they would have been had the water been sucked therethrough 1n the direction from the wetter web to the drier and more compact web. The interfelting of the two webs is also promoted by the tween the rolls 22 and 23. T e resulting single pulp sheet is carried from the rolls 22 and 23 by the felt 21 for further treatment. The latter may comprise further pressing and drying by suitable rolls 25, after which the pulp sheet may be separated from its felt and subjected to further drying and finishing operations.

As indicated in Figure 2, the hollow guide roll 24 is preferably built with a rugged structure to withstand the heavy stresses thereon resulting from the tension of the felt 20. The ends of this roll maybe suitablyjournaled in a pair of standards, one of which is indicated at 31 in Figure 2. The suction box 30 may also be supported on the same standards, this box being preferably swivelly mounted on a pair of trunnions 32 so as to be capable of being swung back clear of the roll 24 when it is desired to repair or replace the felt 20. As shown the suction box 30 may be provided at its outer end with a back plate 33 of any suitable material such as hard rubber, this plate having one or more longitudinal slots or perforations 34 cut therethrough to suck the water from the felt 20. The suction end of the box 30 may be adjustably supported as by a pair of bolts 35 which are hung from pivoted arms 36, the latter being mounted on suitable brackets 37 attached to the standards 31. The arms 36 may be slotted at their free ends to receive the bolts 35 so that when it is desired to swing the suction box 30 away from the roll 24, the adjusting nuts on the bolts 35 need not be disturbed. The pair of trunnions 32 which carry the suction box 30 may be suitably carried by a pair of brackets 40 which may be adjustably shifted toward or away from the roll 24 as by an adjustin screw 41. The suction box 30 may commumressure be-' cate through a suitable fitting 43 with a. suction hose in a manner well known in the art.

I claim:

1. Apparatus of the class described comprising a pair of endless felts, means for depositing continuous webs of pulp on said felts, a suction roll, a press roll on said suction roll, and means for guiding said felts to the nip of said rolls so that the felts with their webs meet at said nip.

2. Apparatus of the class described comprising a pair of endless felts, means for depositing continuous webs of pulp on said felts, a suction roll, a press roll on said suction roll, means for guiding one of said felts into engagement with said suction roll at a point in advance of the nip between the suction and press rolls, and means for guiding the other felt to the nip of said rolls in a direction substantially tangent to both said rolls.

3. Apparatus of the class described comprising a pair of cylinder molds, a couch roll for each mold, a suction roll, a press roll on said suction roll, a pair of endless felts passing respectively between their corresponding molds and couch rolls and passing together between said suction roll and its press roll, and means for guiding said felts so as to meet at the nip of said suction and press rolls.

4. Apparatus of the glass described comprising a cylinder mold, an endless felt having aportion against said mold to receive a web of wet pulp therefrom, a. couch roll on said mold to press said felt against the mold so as to pick up said web, a hollow foraminous guide roll for said felt higher than said couch roll positioned to guide the felt from the couch roll at a steep angle, means for leading the felt approximately horizontally from said hollow roll with the pulp web on its under face, and means for applying suction to the upper face of the felt as it leaves said hollow roll.

5. Apparatus of the class described comprising a pair of cylinder molds, a couch roll on each mold, a pair of press rolls above said mold, the lower of said press rolls having 'means therein for applying suction to a sheet in engagement therewith, a hollow foraminous guide roll approximately on a level with the nip of said press rolls, an endless felt engaging a portion of one of said molds to pick up a pulp web therefrom, said felt extending upwardly at a steep angle from said couch roll to and between said press rolls, a second endless felt engaging the other said mold to receive a Web of pulp therefrom,

said second felt extending upwardly at a steep angle to and over said hollow guide roll and thence approximately horizontally to the nip of said press rolls, and means for applyin g suction to said second felt where it leaves said hollow roll.

6. A method of uniting a pair of wet pulp webs, which comprises removing a substantially greater portion of the water from one of said webs than from the other, superim osing said one web on the other wetter web and applying suction to the free face of the wetter web, whereby water is sucked from the drier web through the wetter web.

7. A method of uniting apair of travelling wet pulp webs, which comprises bringing the webs together face to face and applying simultaneous pressure and suction to the joined webs at the line of junction thereof.

8. A method of uniting a pair of travelling wet pulp webs, which comprises removing a portion of the moisture of one said Web to make it drier than the other, bringing the webs together face to face, squeezing the joined webs together at the line of junction, and applying suction to the free face of the wetter web at said line of junction.

9. A method of making multi-ply paper, which comprises forming a pair of wet pulp sheets, transferring said sheets to a pair of travelling felts, leading the felts upwardly at steep angles with the Web carrying faces thereof toward each other, removing some of the water from one of said webs whereby it is made drier than the other, leading the felt with the drier web over and upon the felt with the wetter web to join the webs together, and applying pressure and suction to the joined webs at the line of junction, the direction of the suction through the webs beilpg from the drier web toward the wetter we In testimony whereof I have afiixed my signature.

HOWARD PARKER.

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