US1944093A - Smoothing roll in paper machines - Google Patents

Description

Jan. 16, 1934. R, w MA GART 1,944,093-

SMOOTHING ROLL IN PAPER MACHINES Filed March 14, 1935 UUUIJDUEIEI IHJIJUDDDEI UUUIJUDDIII water.

Patented Jan. 16, 1934 UNITED STATES PATENT OFFICE This invention relates to smoothing rolls in paper machines; and it comprises certain improvements in machines for making paper or cardboard and having a set of cylinder molds and couch rolls adapted to form pulp into a composite web, a preliminary press section in which the web carried between coarse felts is lightly pressed between rolls, a pair of first press rolls through which the web is carried on a single coarse felt and which bear heavily on web and felt, and second press rolls through which the web is carried on a single, fine felt, said improvements being in means for removing felt marks from the web and comprising a pair of cooperating smoothing rolls located between the first and second press rolls and adapted to engage the bare web, said smooth ing rolls consisting of one roll having a fine reticulated surface engaging the felt marked side of the web, and a second, smooth-surfacedroll engaging the other side of the web; all as more fully hereinafter set forth and as claimed.

In the manufacture of paper or cardboard on cylinder machines, a web is continuously formed upon a series of wire cylinder molds having coacting couch rolls, the freshly formed web is carried between two coarse felts and is passed through a preliminary press section, which removes a considerable amount of water. Pressures in this press section are relatively low. After the preliminary pressing, one felt leaves the paper web while the other continues with and carries the web between a pair of larger press rolls, known as the first press, where the web and felt are subjected to heavy pressure to remove more In order to facilitate the drainage of water, felts of a coarse and open texture are employed. The high pressure used in the first press results in the felt side of the web passing through the first press being felt marked. This side is frequently so rough and irregular that subsequent pressings and calenderings fail to make the felt side as smooth as the wire side which has contacted with the cylinder molds. Ordinarily the paper is fed from the first press rolls to second press rolls which remove further water preparatory to the drying and calendering of the paper.

In the present invention I provide as a smoothing device for the felt side of the web, a special pair of rolls placed after the first press and before the second press. One -such roll has a reticulated surface and engages the felt-marked side of the web, and the other has a smooth surface and engages the other or wire side of the web. Both are advantageously idler rolls; but, if desired,

'it a uniformly reticulated surface.

they may be power driven. They engage the web under relatively light pressure; a pressure sufficient to smooth the felt-marked web and give I thereby obtain a web having the two sides substantially alike. There is the additional advantage that the first felt can be made very coarse, thus permitting ready drainage of water in the preliminary pressing step. This quicker and more efficient removal of water permits greater speed of operation of the paper-making machine.

In the accompanying drawing I have shown, more or less diagrammatically, several embodiments of my invention. In these showings:

Fig. 1 is a view in elevation of a portion of a cylinder machine provided with my smoothing rolls;

Fig. 2 is a view in elevation of a smoothing roll suitable for my purposes;

Fig. 3 is a view in section of a smoothing roll comprising a smooth surfaced roll provided with a wire cover;

Fig. 4 is a view of a modified design of smoothing roll having two layers ofwire;

Fig. 5 is a view of another modified design of smoothing roll having a different reticulated surface;

Fig. 6 is a view in elevation of the roll shown in Fig. 5. I

In these showings, in which like reference numerals indicate like parts throughout the several views, Fig. 1 shows a cylinder machine comprising a plurality of wire cylinder molds 1 revolvlng in vats 2 containing pulp mixture 3. Couch rolls 4 are mounted adjacent the molds. The newly formed web is carried by a coarse felt 5 passing between the couch rolls and the wire molds as shown. This felt may be coarser than that usually employed, since, in accordance with my invention, the felt marks on the web are subsequently removed, regardless of their coarseness. The felt and the web are reversed in direction by a roll 6. A second coarse felt '7 carried on rolls 8 engages the upper or wire side of the web, and the web is fed between these two felts to the first press. Between the couch rolls and the first press is a preliminary water extracting apparatus, which may be of any type, but is here shown, for sake of'illustration, as a series of baby press rolls 11 engaging the upper and lower felts between which the web is being fed.

The first press comprises a hard surface roll 10 and a soft surface roll 12 located at the end of the preliminary pressing apparatus and engaging the web and one felt, as shown, This press serves to express water, but it also leaves deep felt marks on the under side of the web. The free web goes to the second press comprising press rolls 14 and felt 15, guide rolls 13 supporting the web. This second felt is of a much finer and closer weave than the first. From the second press the bare web goes to other press rolls, dryers and calenders, not shown.

Between the first press and the second press is positioned my smoothing apparatus, as shown, comprising an upper roll 16 having a resilient surface such as a covering of soft rubber, and a lower roll 17 having a reticulated surface engaging the lower side of the web. Suitable usual bearings for the rolls and suitable pressure regulating devices for the upper roll are provided (not shown). The pressure of the rolls on the web is just enough to impress the reticulated surface of the lower roll on the web, obliterating the felt marks. The pressure used is relatively light; and the smoothing apparatus does not necessarily serve to remove any water at all.

Figs. 2 and 3 show a reticulated roll suitable for use in my apparatus, comprising a metal drum or shell 18 covered with a layer of fine wire cloth 19. The wire layer is wrapped tightly around the shell and the seam joined by sewing or other suitable method. There may be more than one layer of wire, in which case the layers are advantageously made of progressively coarser wire from the outer layer towards the shell. Such an embodiment is shown in Fig. 4, showing the shell 18 having a layer of coarse wire 20 and a layer of fine wire 19. The size of the meshes used depends on the character of the surface it is desired to give the felt marked web. For a certain cardboard, I found screens of 30 to 60 mesh suitable for the outer layer.

Figs. 5 and 6 show a roll suitable for use in my apparatus, having reticulations 21 formed directly in the shell, by engraving or in any other suitable way. The fineness of these reticulations is of the same order as the fineness of the wire mesh in wire covered rolls. This form of reticulated roll has its advantages but it is rather costly. I generally use wire covered rolls.

It will be seen from Fig. 1 that in the first press the underside of the web is in contact with the first felt. As stated above, this felt is of. a very coarse open weave, in order to provide rapid drainage of the water from the paper. Inasmuch as there is considerable pressure used on the first press, the under side of the paper carries deep impressions from the coarse felt, while the upper side is comparatively smooth. If my apparatus were omitted from the machine, the Web would pass directly from the first press to the second press where one side of the paper would contact with a smooth roll and the other with a felt 15 which is more smoothly and closely woven than the first felt. Attempts to obliterate felt marks by pressing the bare web at this point between two smooth surfaced rolls without the use of a felt have invariably failed due to blowing; the disruptive expansion of air in the web as the web emerges from the nip of the press rolls. According to the present invention, I advantageously interpose my smoothing press device between the first and second press without the use of a felt. The felt marked side of the paper comes in contact with the screen faced roll 1'7. The wire comprising this screen passes into the soft plastic web exerting higher pressures on the raised portions of the paper and generally evening out the gross surface irregularities imposed by the first felt. There is thus obtained a light embossing effect leaving the paper with a fine wire mark, the intensity of which is governed by the amount of pressure exerted. This pressure is ordinarily such that there is substantially no water removed by the press. The fine wire mark thus impressed on the felt side resembles the wire marking on the opposite side of the web received from the cylinder molds; the two sides of the web are made alike. The apparatus replaces the gross roughnesses and irregularities of the coarse felt impressions with substantially uniformly fine wire marks. Blowing does not occur, since the air in the web readily escapes through the reticulations as the web passes through the nip.

Smoothing apparatus under the present invention by removing felt marks and smoothing the surface of the web, permits the use of extremely coarse first felts, and thereby allows ready and thorough removal of water by the preliminary pressing means and the first press. In the past, the first felt could not be used as coarse as desired, because of the inevitable result of coarse felt marks. A finer felt than was desirable for water draining was necessary, in order not to have a too one-sided product. With the present apparatus, allowing the use of coarse, open-textured felts and. the removal of a larger proportion of water from the newly formed web in the first stages of paper making, the paper making machine can be run at higher speeds. The finished web is substantially evensided; that is, one side is like the other.

While I have shown the preliminary pressing means as comprising a series of so-called baby rolls between which the felts are fed, it is to be understood that any usual or conventional preliminary pressing apparatus may be employed and that, if desired, when the baby rolls are employed they may be preceded by an extractor press. Between the cylinder molds and the apparatus of this press section is sometimes placed an extractor press for removing some or much of the remaining water; this press comprising a soft surfaced roll and a suction roll engaging the web and felts. The invention is not to be considered as limited to the use of any special type of couch rolls, preliminary press, first press or second press, nor is it to be limited to the use of any special reticulated surface on the rollers of the smoothing device, but consists generally in the combination with a cylinder paper making machine having couch rolls operating in combination with felt and delivering marked paper to a second press, of a smoothing device therebetween for converting the felt marks on one side of the web into marks simulating the wire marks on the other side.

What I claim is:

1. In a machine for making paper having two similar surfaces, the combination with an ordinary cylinder paper making machine having means in series for forming a composite web, a first press for extracting water comprising two cooperating rolls exerting high pressure on the web through an intervening coarse felt thereby impressing felt marks and a second press engaging the web with an interposed fine felt, of a pair of rolls directly engaging the web and located between the first mentioned and the second mentioned press, one of said rolls having a reticulated surface and serving to replace the felt marks left on the web by a reticulated pattern.

2. In a machine for making paper having two similar surfaces, the combination with an ordinary paper machine having a set of cylinder molds adapted to form pulp into webs, waterremoving first press rolls through which the web is carried on a single felt after leaving the baby press, and which bear heavily on the web and felt, thereby felt-marking the web, and second press rolls through which the web is carried on a second felt, of a pair of cooperating, smoothing rolls located between the first and the second press rolls and adapted to engage the bare web, and obliterate said felt marks, said smoothing rolls consisting of one roll having. a fine reticulated surface engaging the felt-marked side of the web, and a second, smooth-surfaced roll engaging the other side of the web.

3. In a machine for making paper having two similar surfaces, the combination with an ordinary cylinder paper making machine having means in series for forming a web upon moving wire surfaces, and a press acting on the web through a coarse felt and comprising two rolls engaging the felt-carried web under heavy pressure impressing felt marks on the web, of a pair of rolls engaging the bare web and located after the press, oner of said rolls having a reticulated surface and serving to replace the felt marks left on the web by a line reticulated pattern.

4. The combination with a cylinder paper making machine having wire cylinder molds and including felts between which the paper web is carried and subjected to pressure at one place, thereby impressing felt marks on one side of the web and including a press for extracting moisture from the formed web, of reticulating means operating between the web-carryingfelts and the press and arranged to act upon the web of paper to convert the felt marks thereon into reticulated marks of a fineness similar to that of marks left on the web by the wire cylinder molds, prior to operation of the press on such web.

5. In a cylinder paper making machine having wire cylinder molds upon which a paper web is formed and having press rolls engaging the paper web carried on a coarse felt leaving felt marks on one side of the web, a roll adjacent the press rolls having a fine reticulated surface and contacting the side of the web which has been in contact with the felt to eliminate the felt marks and substitute therefor a fine pattern similar to marks left on the web by the wire cylinder molds.

ROY W. MAGGART.

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