US2077614A - Paper making machine - Google Patents

Description

April 20, 1937.

w. B. CAMPBELL PAPER MAKING MACHINE Filed Nov. 21, 1935 2 Sheets-Sheet 1 April 20, 1937. w. B. CAMPBELL PAPER MAKING MACHINE I 2 Sheets-Sheet 2 Filed Nov. 21, 1935 Patented Apr. 20, 1937 UNITED STATES PATENT OFFICE PAPER MAKING MACHINE City, Quebec, Canada Application November 21, 1935, Serial No. 50,975

1 Claim.

This invention relates to paper making machines.

In the past it has been usual to form the initial paper web by flowing the suspended fibres onto the 5 travelling wire of a Fourdrinier machine, or to form the web by rotating a wire covered drum in a vat containing a pulp suspension which is deposited on the wire by means of suction,

Among the disadvantages involved in the former method are high wire cost and the necessity of providing considerable space to accommodate the machine, while the latter presents other serious disadvantages such as the deposit of the fibres on the screen with their lengths very largely in the direction-of motion, the limited speed of operation and the tendency of the water to be driven outward against the suction by the centrifugal force.

Latterly it has been proposed to substitute for these devices a drum carrying a forming wire onto which the pulp suspension is flowed, the arrangement involving the use of a plurality of radially disposed conduits within the drum such conduits extending from the wire to the central portion of the drum through which suction is applied to withdraw the water and to form the web on the drum. This type of structure has some effect towards overcoming the: disadvantages of former types of apparatus, bui is not adapted to form a high grade paper became of the tendency,

particularly when the machine is operating at high speeds, of the water unde 1' centrifugal force to remain in the sheet, or acc imulate under the screen, thus spoiling the paper, a further objection to this type of apparatus is the rather involved construction of the drum.

I have, however, devised a construction of this drum type of machine which eliminates the eifect of centrifugal force on the water drawn from the web and is of a simple construction permitting the machine to be manufactured and operated economically.

Furthermore, I have provided a construction wherein the pulp suspension is flowed onto the foraminous covering of the drum and the web is preliminarily formed and dewatered and then completely aired during its passage over a portion of the circumference of the drum so that the web, when removed from the drum, is ready for the conventional pressing rolls of a paper machine.

In other words, the invention includes an arrangement for the application of forming drainage efiect, suction box effect and suction couch effect, on the web in its short space of travel over a part of the circumference of the drum,

ings which form part of the disclosure.

In the drawings:-

Figure 1 is a side elevation of an embodiment of my invention illustrating the relative positions of the drum, the suction apparatus and the flow box.

Figure 2 is an elevation of the drum and flow box partly in section.

Figure 3 is a plan view of the apparatus illustrating clearly the arrangement of compartments around the periphery of the drum and showing the foraminous covering fragmentarily, and

Figure 4 is a section taken on the line 4-4 of Figure 3 to illustrate the water pockets and method of applying suction.

Referring more particularly to the drawings, A indicates the apparatus as a whole which includes the drum B and flow box C. The drum B is mounted for rotation on a suitable shaft l0, being formed with the spider supporting structure I I on which is mounted suitable annular drum wall supports l2. These may be of any desired construction and, as illustrated in Figure 4, they comprise the annular plates flanged as at l3. The drum wall, according to the present invention, is made up of a series of abutting compartments H, the partitions l5 separating the compartments being radially disposed around the periphery of the drum and extending from one side to the other. The base It of these compartments forms the drum wall. The compartments M are open at the top and are covered preferably by a foraminous covering such as perforated metal or screening material covered by a fine wire mesh H which provides the forming surface for the paper web.

At the end of each compartment, on both sides of the drum, a pocket or chamber I8 is formed which is generally defined on one side by the annular plate l2 and on the top and the other side by the walls I9 and 20 which may take the form of a single annular plate. This leaves an opening 2| between the pockets or chambers l8 and the compartments H to permit the water removed from the web into the compartments to be drawn into the pockets l8. The removal of the water'is, of course, effected by suction and suction is applied by means of ports or openings 22 spaced above the circumference of the plates l2 which communicate with each pocket and with the suction headers of the suction apparatus, later to be described.

The compartments M, it will be noted, are of comparatively small cross sectional dimensions so that they may be made of light material and still provide strength to withstand external air pressure while vacuum is maintained inside. In 2 view of this, only a thin foraminous layer, such as perforated metal or wire screen, is needed to support the fine forming wire covering and, it will be obvious that by forming the structure in such a manner it can be built economically while prowithout shock.

livered on the wire forming surface of the drum,

viding a practical apparatus, having regard to lightness and durability, as well as the avoidance of involved construction. Moreover, the structure is of a compact nature, since the bases of the compartments form the main wall of the drum, the forming wire constitutes the top of the compartments and the side wall projecting above the lever of the forming wire forms a deckle to restrain any tendency of the stock to move longitudinally.

During the operation of the drum, the effect of centrifugal force will tend to carry the removed water back against the under side of the sheet. This water must be removed before suction is released or it will promptly flow back into the sheet and destroy it. This difilculty must be overcome and cannot be overcome by the haphazard application of suction. This difficulty, however, is overcome by the present invention since the water forced away from the cylinder axis and tending to lie against the under side of the wire is quite free to move parallel to the axis of the drum and consequently, by subjecting the compartments H to suction from each side of the drum at its periphery, this water will flow under considerable force into the pockets or chambers l8 where it is free to move by centrifugal force radially to the extent of the pocket and will be removed through the port or opening 22 under influence of the suction apparatus. In this way the detrimental effect of centrifugal force in an apparatus of this character is immediately obviated.

The pulp stock is delivered from the flow box B which is provided with a suitable nozzle 23 and may be of any desired construction. The nozzle, however, is so placed in relation to the drum that the trajectory of the stream of stock meets the surface of the drum substantially at a tangent to the latter and close to the nozzle. The velocity of the stock is made substantially equal to the surface speed of the drum or at some desired differential from that speed. In this way the dilute stock is delivered to the drum surface Immediately the stock is dethe web is formed by suction.

The application of suction, according to the present invention, is effected through a plurality of suction headers 24, 25 and 26. As clearly illustrated in Figure 4, each suction header is open at one side and is arranged to abut the annular plate l2 so as to fit over the openings or ports 22. The contact between the header 24 and plate l2 will tend to be a fairly tight sliding fit since the general internal pressure at the ports is less than atmospheric and the external air pressure will tend to hold the sliding ports together. A suction pipe line such as 21, 28 and 29, is connected to each header, each pipe line communicating with a vacuum pump or the like, thus to establish a desired degree of vacuum within the compartments l4 registering with each header.

The degree of suction will, of course, determine the rapidity of formation of the web and according to the present invention I provide an arrangement whereby, in one stage, the web is preliminarily formed and dewatered and then, in two succeeding stages, is subjected to different degrees of suction so as to complete the preparation of the web very quickly ready for the pressing rolls.

On referring to Figures 1 and 2, and particularly to Figure 2, it will be seen that the suction headers 24, 25, and 26 are arranged adjacent to each other over a given are of the circumference of the drum, the arrangement being such in the present showing, that the suction will remove the water at such a rate that when the stock delivered to the foraminous cover moves on the drum between the radial lines DE (see Fig. 2) or in other words, when stock has moved through a 60 angle of rotation from the first point of contact, the web is formed and dewatered, the suction effect in this stage, removing only the water.

When the stock passes on through a further 60 angle of rotation or between the lines E and F, it is subjected to a greater degree of suction and provision is made to take care of air drawn through the web in the same manner as in the case of ordinary suction boxes. During the final travel of the web on the drum, that is, between the lines F and G, a travel of approximately 30, still greater suction is applied and more air is drawn through the web so that the web at this point is completed ready for the pressing rolls and is removed from the drum preferably by means of air pressure to be transported to the pressing rolls by means of the conveyor 30. In other words, the suction headers 24, 25 and 26 are positioned and operated to provide forming drainage, which is accomplished through the suction header 24; suction box effect, accomplished through the suction header 25; and suction couch effect through suction header 26.

Through this arrangement, therefore, I provide a compact practical structure, which overcomes the detrimental effect of centrifugal force and provides for the complete formation of a paper web ready for pressing. It is apparent from the foregoing that I have provided a practical, compact, light and durable rotary drum construction for paper making which will function to form the complete paper web very quickly and which eliminates various disadvantages occurring in prior proposals.

Various modifications may be made in this invention without departing from the spirit thereof or the scope of the claim, and therefore the exact forms shown are to be taken as illustrative only and not in a limiting sense, and it is desired that only such limitations shall be placed thereon as are disclosed in the prior art or are set forth in the accompanying claim.

I claim:-

A paper web forming apparatus comprising a rotatable drum, the central portion of the drums periphery including a foraminous covering adapted to have pulp suspension placed thereon, shallow compartments adjacent to one another and immediately underlying the foraminous covering, terminal chambers disposed along the drum surface at the edge of said drum and communieating with the compartments disposed below the foraminous covering, the peripheral wall of each terminal chamber being radially further from the centre of the drum than the foraminous covering, at least one suction header positioned at an end of the drum and communicating with the terminal chambers, whereby upon the application of suction through said header the liquid constituent of the deposited pulp suspension may be withdrawn therefrom through said compartments, chambers and suction headers.

W. BOYD CAMPBELL.

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