US2934143A

US2934143A - Suction flat box cover perforation

Info

Publication number: US2934143A
Application number: US665919A
Authority: US
Inventors: Hornbostel Lloyd
Original assignee: Beloit Iron Works Inc
Current assignee: Beloit Iron Works Inc
Priority date: 1957-06-17
Filing date: 1957-06-17
Publication date: 1960-04-26
Anticipated expiration: 1977-04-26

Description

United States Patent SUCTION FLAT BOX COVER PERFORATION Lloyd Hornbostel, Beloit, Wis., assignor to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin Application June 17, 1957, Serial No. 665,919

2 Claims. (Cl. 162-351) The instant invention relates to suction boxes for use in paper machines, and more particularly, to an improved suction box cover structure for use in paper machines such as Fourdrinier machines or cylinder machines.

In Fourdrinier machines, the suction boxes are used to assist in the removal of water from a web carried on a travelling wire; and in cylinder machines suction boxes are used to assist in the removal of water from a web carried on a felt. In any case a permeable forming band is trained across the suction box top carrying the web thereon and suction through the suction box top is applied to the underside of the permeable band to assist in removal of water from the web through such permeable band.

Although the instant invention has application in either a cylinder or Fourdrinier machine, it will be described primarily in connection with a Fourdrinier machine.

In general, the suction box top or cover is an elongated plate having upper and lower faces and parallel longitudinal forward and rear edges for supporting a permeable forming band, such as a felt or wire, moving transversely across the top of the plate from the forward to the rear edge thereof. In Wadleigh US. Patent No. 2,487,202 it is suggested that it may be advantageous to provide the suction box cover with suction passages therein having substantial inclination from the upper to the lower face in the direction from the forward edge toward the rear edge, or in other terms, substantial inclination from the top to the bottom of the cover in the direction of travel of the wire passing thereover. Logical explanations are presented for superior dewatering using suction passages such as those described by Wadleigh. For example, it has been suggested that the incline downward and in the direction of travel of the wire permits the suction passages to function as scrapers to remove water from the bottom of the wire and to withdraw water therefrom more readily because the suction passages are inclined at least to some extent in the direction in which the momentum of the water tends to carry water adhering to the bottom of the wire.

The instant invention, in contrast, is based upon the discovery that inclination of the suction passages in exactly the opposite direction (to that proposed by Wadleigh) results in unusually and unexpectedly superior water removal. For example, using a suction box cover wherein the suction passages have substantial inclination from the upper to the lower face in the direction from the rear edge toward the forward edge or in the direction opposite to the direction of travel of the wire it is found that the rate of water removal, particularly at moderate paper machine speeds, is almost twice the rate of water removal that is obtained under otherwise identical operating conditions except for the inclination of the suction passages downwardly in the direction of wire travel (as taught by Wadleigh).

It is, therefore, an important object of the instant invention to provide an improved suction box cover for paper machines.

It is further object of the instant invention to provide an improved cover for a suction box of a paper machine comprising an elongated plate having upper and lower faces and parallel longitudinal farward and rear edges for supporting a permeable .forming band moving transversely across the top of the plate from the forward to the rear edge thereof, said plate having a plurality of suction passages therein having substantial inclination from the upper to the lower face in the direction from the rear edge and toward the forward edge.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

Figure 1 is an essentially diagrammatic elevational view of a paper machine forming section employing a suction box embodying the instant invention;

Figure 2 is a top plan view of a suction box'embodying the instant invention;

Figure 3 is an enlarged fragmentary top plan view of a suction box cover embodying the instant invention; and

Figure 4 is an enlarged detail sectional elevational view taken substantially along the line IV-IV of Figure 2.

As shown on the drawings:

In Figure 1, a paper machine indicated generally by the reference numeral 10 is shown comprising an endless forming wire 11 trained about a breast roll 12, a couch roll 13 and lower return rolls 14, 15 and 16. Stock flows from a head box 17 onto the top run of the wire 11 whereat dewatering is initially carried out during the run of the wire 11 over table rolls 18, 18, etc. After partial dewatering of the web W on the wire 11 passing over the table rolls 1'8, 18; the wire 11 with the web W thereon pass over a plurality of suction boxes 19, 20 and 21. The suction boxes are provided with a

perforate cover

19a, 20a, 21a, respectively, which supports the wire 11 from beneath while suction is applied thereto through the covers 19a,

20a, 21a from within the suction boxes 19, 20 and 21, respectively. The instant invention resides in an improved structure for a suction box cover such as the suction box cover 1% shown in Figure 2.

In Figure 2, a top plan View of the suction box cover 19a is shown and the suction box cover 19a comprises an elongated plate having an upper face 30 shown in Figure 2 and a lower face 31 (shown only in Figure 4). The cover 19 has parallel longitudinal forward (32) and rear (33) edges and the permeable forming band or wire 11 moving in Figures 2, 3 and 4 in the direction indicated by the arrows moves across the top 30 of the cover 19a from the forward edge 32 to the rear edge 33.

The details of the suction passages are not shown in Figure 2, but they are shown in Figures 3 and 4. As will be seen from Figures 3 and 4 suction passages in the form of holes of

circular cross-section

34, 35 and 36 are shown in top plan view in Figure 3 and it will be noted that they have substantially uniform cross-section throughout their length, but these holes or

suction passages

34, 35 and 36 are inclined downwardly from the top 30 opposite to the direction of travel of the wire 11. In Figure 4,

additional suction passages

37, 38, 39 and 40 are shown in a sectional elevational view, so it can be readily appreciated thatthe holes 37, etc. are inclined substantially from the upper face 30 to the lower face 31 in the direction from the rear edge 33 toward the forward edge 32. For the sake of simplicity the views 2, 3 and 4 are not made strictly to scale. In actual practice a suction box cover has a thickness of about 1 to 1% inches and holes drilled therein have diameters within the range of about A to inch. In order to demonstrate the instant invention, a forming wire at a tension of 25 pounds per inch is drawn over a suction box wherein a vacuum of 6 inches is maintained thereon. A fibrous web is carried on the wire. For the purposes of the instant demonstration, the fibrous web employed is a felt which is supplied with water at a rate of 10 gallons per minute. The wire with the moist fibrous web thereon is drawn acrosssuction box covers having difierent structures at a speed of 1500 feet per minute. Identical operating conditions are used employing a suction box cover having holes drilled at an incline downwardly in the direction of wire travel and holes drilled at an incline downwardly in the direction opposite to wire travel. The angle of incline in each case being 45 and the hole sizes being inch in diameter, with the same total amount of open area in each suction box. It was found that the rate of removal of water (as measured coming from the suction box) for the suction box cover wherein the holes are inclined downwardly opposite to the di-' rection of wire travel was 4.5 gallons per minute, Whereas the rate of removal of water for the suction box cover wherein the holes were inclined downwardly in the direction of'wire travel was 2.4 gallons per minute.

The angle of incline of the holes (from the horizontal plane of the top surface 30 of the cover) may range from 30 to 75 or 80 but is preferably 45 to 60 .It will be understood that modifications and variations may be eifected without departing fromthe spirit and scope a suction box beneath same for the removal of water from aweb of paper being" formed on the wire, the improvement which consists of a stationary cover for said box, which cover is perforated with suction passages each of which is of substantially uniform cross-section throughout its length and substantially all of which passages have substantial inclination from top to bottom of the cover in the 1 direction opposite to the direction of travel of the wire.

2.' In a paper making machine, a cover for a suction box, and a permeable forming band in contact with said cover, said cover comprising an elongated plate having upper and lower faces and parallel longitudinal forward and rear edges for supporting the permeable forming band moving transversely across the top of the plate from the forward to the rear edge thereof, said plate having a plurality of suction passages therein substantially all of which have substantial inclination from the upper to the lower face in the direction from the rear edge and toward the forward edge in the direction of travel of the forming band moving thereover.

References Cited in the file of this patent UNITED STATES PATENTS