US3000439A

US3000439A - Moving belt suction box assembly

Info

Publication number: US3000439A
Application number: US774995A
Authority: US
Inventors: Harry C Moore
Original assignee: Beloit Iron Works Inc
Current assignee: Beloit Iron Works Inc
Priority date: 1958-11-19
Filing date: 1958-11-19
Publication date: 1961-09-19
Anticipated expiration: 1978-09-19

Description

Sept. 19, 1961 H. c. MOORE 3,000,439

MOVING BELT SUCTION BOX ASSEMBLY Filed Nov. 19, 1958 2 Sheets-Sheet 1 1 EVE. 211T Harry 6. Moore Sept. 19, 1961 H. c. MOORE MOVING BELT sucnon BOX ASSEMBLY 2 Sheets-Sheet 2 Filed NOV. 19, 1958 Harry C. Moore United States Patent Ofifice 3,000,439 MOVING BELT SUCTION BOX ASSEMBLY Harry C. Moore,- Beloit, Wis, assignor to Beloit Iron Works, Beloit, Wis., a corporation of 'Wisconsin Filed Nov. 19, 1958; Ser. No. 774,995 7 Claims. (Cl. 162-314) The present invention relatesbroadly to paper machines, and is more particularly concerned with a new and improved apparatus comprising a suction box of the moving belt type and a roll. acting thereagainst to perform marking and compacting functions.

The purpose of a dandy roll on a Fourdrinier type paper making machine is to smooth and finish the forming sheet on the Fourdrinier wire. The dandy roll eliminates bubbles, foam and major inequalities in formation, and compacts the fibers and marks the web with a water mark pattern. Normally the dandy roll is mounted on bearing or rotatable means which carry the weight thereof, and said roll is preferably driven by means which cooperate with the means rotatably mounting the roll.

Even though the dandy roll is driven at speeds independent of machine speed, when the Fourdrinier paper making machine operates at higher speeds the dandy roll tends to create an obstruction to the layer of fiber and water, then forming the web moving on the wire, and this action of the dandy roll causes the surface of the web to rise in front of the roll as though a dam were present. This, of course, disrupts the formation which has already taken place in the web. Apparently this is caused by resistauce of the foraminous peripheral surface portion of the dandy roll through which the water in the web cannot pass as readily as it would in the absence of the dandy roll. In addition, on the off-running side of the dandy roll water and some fibers tend to be separated from the main web and carried partially or entirely around the dandy roll, so that ultimately they are thrown back onto the moving very loose web (or stream of moving fibers in water), thereby causing holes or bubbles. For this reason, the speed of operation of the conventional dandy roll for wire marking has been limited to approximately 800 feet per minute.

Present-day paper machine speeds are preferably greater than 800 feet per minute. The instant invention permits compacting and marking at these greater speeds Without the earlier noted disadvantages while additionally avoiding the heretofore required laborious, operation of frequent dandy roll cleaning. The structure of this invention comprises a plurality of suction boxes over which travels a movable perforated belt contacted by the traveling Fourdrinier wire. Positioned-in alignment with the vertical axis of one of the suction boxes is a pressure controlled dandy roll which may carry on its circumference a covering of relatively soft material to provide lumpbreaking functions. Accordingly,'an effective nip is provided oppositethe relatively flat suction box without the damaging effect of the friction of the Fourdrinier wire on the fiat box surface. The positive pressure nip is accomplished by introducing a fluid pressure lubrication into a pattern. of grooving surrounding the suction openings in the stationary suction box, this grooving permitting sufficient pressure to be provided to float the moving belt, and in accordance with the principles of this invention, the fluid pressure is adjusted to balance the nip applied by the dandy roll;

As will be brought out in further detail later, by utilization of a suction box in combination with a dandy roll, the available suction drains the expressed water and the fibrous sheet may be much more effectively compacted and/or marked. Further, the removal of the water from this nip permits the dandy roll to run cleaner, and there is avoided frequent'cleaning operations of the roll, wheth- Patented Sept. 19, 1961 er performed with the roll on the machine or removed therefrom. The suction elfect also tends to resist the back spray which is objectionable at high machine speeds when dandy rolls are employed in accordance with the prior art practices, and the utilization of suction boxes prevents the mat from being lifted by the dandy roll.

The present invention further provides what may be termed a slow nip, this being provided by operating the roll of this invention against a flat surface which is the equivalent of a pair of much larger rolls, and thereby provides a more gradual closure of the web into the nip as the wire travels therethrough. In addition, the operation of the roll against the relatively rigid structure of the suction box tends to minimize flutter or'vibration due to possible unbalance in the system. As willalso be noted nip pressure is controlled by either loadingor relieving mechanisms.

A further feature of the invention which will be specifically disclosed hereinafter is the utilization of rolls Within the loop of the traveling belt carrying on their circumferences either a waflled, knurled or grooved configuration to permit the belt to be guided by therolls and effectively controlled, whereby there is eliminated the earlier problem of the water film between the rolls and belt causing the belt to run ashore due to the lack of friction between the belt surface and the rolls. The knurled or other roll surface functions effectively to re lease the water film from the inner surface of the belt.

It is accordingly a primary aim of the present invention to provide a new and improved marking and/or compacting apparatus comprised essentially of the combination of a suction box of the moving belt type and a pressure controlled dandy roll positioned above the suction box in opposed relation therewith.

It is another object of the instant invention to provide a moving belt suction box assembly comprising a plurality of suction boxes at least one of which is of relatively greater depth than the other boxes, a movable perforate belt trained about a pair of rolls provided with friction inducing surfaces, and a dandy roll which may or may not be covered with a relatively soft material positioned above the relatively deeper suction box and applying to the fibrous sheet formed on the traveling Fourdr'mier wire a controllable nip to compact and/ or mark the sheet being formed thereon with resulting new and improved results.

Other objects and advantages of the invention will become apparent during the course of the following description, particularly when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

FIGURE 1 is an essentially diagrammatic elevational View of a paper machine having a suction box and roll assembly constructed in accordance with the principles of this invention;

FIGURE 2 is an enlarged view of the suction box and roll assembly shown in FIGURE' 1;

FIGURES 3, 4 and 5 are elevational views of various forms of main rolls which may be employed to form the loop of the movable belt of FIGURES 1 and 2;

FIGURES 6 is an enlarged sectional fragmentary detail view of the movable belt and relatively deeper suction box structure of FIGURE 2;

FIGURE 7 is a vertical sectional View taken substantially along the line VII-VII of FIGURE 6; and

FIGURE 8 is a fragmentary detail top plan view of a suction box cover which may be employed in connection with the instant invention.

Referring now to FIGURES l and 2, there is shown a paper machine indicated generally. by the reference numeral 10 and comprising a looped forming wire 11 trained over a breast roll 12, table'rolls 13, suction boxes 14, a

couch roll 15, a turning roll 16, and return rolls 17. Stock is deposited on the upper wire run 11a from a head box 18 in the region of the breast roll 12, and the stock is dewatered during its travel on the upper wire run 11a to form a web W which is removed from the wire 11 by a pickup felt 19 urged against the web W by a suction pickup roll 20. A rotary belt 21 mounted on

rolls

22 and 23 of this invention, as well as on roll 24, is interposed between the suction boxes 14 and the Wire run 11a.

As best shown in FIGURE 2, the wire 11a travels in the direction indicated by the arrow with the web W thereon. The traveling endless belt 21 engages the bottom side of the wire and is mounted for traveling on a roll 22 closely spaced from the oncoming side of the suction boxes 14 and on a roll 23 closely spaced from the offrunning side of the suction boxes, with a third guide roll 24. While in many cases the wire run 11a is suflicient to drive the belt 21 over the suction boxes 14, in certain circumstances it may be necessary to drive either or both of the

rolls

22 and 23, and for this purpose suitable drive means 25 (shown diagrammatically) may be connected with the roll 23.

To eliminate the earlier problem of the endless belt 21 slipping axially or running ashore on the previously used smooth finished rolls, there is herein provided on the surfaces of the rolls 22 and 23 a friction inducing configuration which further functions to release the normal water film lying between the inner surface of the belt 21 and the belt contacting surface of the main rolls. Roll configurations which are suitable to accomplish these functions are shown in FIGURES 3, 4 and 5, and it is to be appreciated that either of the roll surfaces disclosed, or variations thereof, may be used on either or both of the

rolls

22 and 23. As appears in FIGURE 3, a roll 22a supported upon a shaft 26 may have a knurled belt contacting surface 27a formed in a perpendicularly grooved pattern, or as shown in FIGURE 5, a roll 22b carried by a shaft 26 may have a knurled belt engaging surface 27b provided by a diagonally intersecting grooved pattern. On the other hand, effective results are obtained by the arrangement of FIGURE 4, comprising a roll 22c on a shaft '26, the roll having a circumferentially grooved belt engaging surface 27c. By utilization of either of the roll configurations shown, and variations thereof falling within the purview of this invention, the belt 21 is guided and controlled, and water on the inner surface of the belt received from the suction boxes 14 is released and good frictional contact obtained between the rolls 22-23 and the belt 21.

In the form of the invention shown essentially diagrammatically in FIGURES l and 2, six suction boxes 14 are employed, and in FIGURE 2 the suction boxes are identifled in series by the numerals 14 with the exception of the relatively deeper intermediate suction box which is identified by the legend 14. The suction box 14 difiers from the other boxes 14 essentially in its relatively greater depth and the provision of a separate water supply line thereto. Accordingly, in the description to follow of the suction boxes it is to be understood that the boxes 14 and 14' have common structural features.

While various forms of suction boxes and movable V perforate belts may be employed in the practice of this invention, there is shown in FIGURES 6, 7 and 8 a structural arrangement which has proven quite effective in practice, In the illustrative structure of FIGURES 6, 7 and 8 it is to be seen that the

suction boxes

14 or 14 are equipped with a generally fiat top 14a having perforations 14b therein which open into the interior 14c. Exhaust means in the form of a pump 28 (shown diagrammatically) connect todrop lines 14d of each of the suction boxes for the purpose of exhausting the interiors 14cv to eife ct dewatering of the web through the perforations14b. f

" As indicated, the perforations 14b in the suction box 4 top 14a are spaced longitudinally in the direction of wire travel, and said perforations are also spaced laterally and there are land areas 14e on the generally fiat upper face of the cover 14a. Such land areas 14e are intermediate the perforations 14b and actually provide the supporting surface for the cover 14a that supports the traveling belt moving over the cover. In the practice of the instant invention, it will be seen that the land areas He are provided with shallow grooves 14 which face the belt 21 traveling thereover. These shallow grooves are closed oif from the interior of the suction boxes.

As here shown, the land areas 14e mounting the grooves 14 and the grooves 14] themselves extend longitudinally of the direction of wire travel. The machine direction is indicated in FIGURES 2 and 6 by arrows. The grooves 14 extend from near the ofi-running edge 14g (FIGURE 2) of the suction box covers 14a to near the oncoming edge 14h.

As indicated diagrammatically in FIGURES 2 and 7, means connected to a source of liquid under pressure communicate with the grooves 14 for flowing liquid between the bottom side of the belt 21 and the suction box top 14a to lubricate the same. Such means indicated generally at 29 in FIGURE 2 are shown diagrammatically and they include a pump 30 connecting with a main line 31 from which is taken a branch line 31a leading to the grooves 14 in the relatively deeper suction box 14', and a branch line 31b connecting with the grooves 141 in the relatively more shallow suction boxes 14. It is to be seen that valve means 32 is provided in the branch line 31b in order to control the pressure to the boxes 14 and thereby permit a relatively higher water pressure to be delivered to the suction box 14'. The water pressure delivered to the relatively more shallow boxes 14 is only suflicient to carry the belt alone against the vacuum pressure, while the relatively higher pressure to the suction box 14' serves to oppose the nip pressure of roll R to thereby permit relatively higher nip pressures to be employed.

While the water line connection of FIGURES 6 and 7 is shown as made to the grooves 14f in the suction box 14', it will be appreciated that similar connections are made to the corresponding grooves in the relatively more shallow boxes 14. Accordingly, connecting with the branch line or header 31a is a plurality of conduits 33 terminating at one end in the grooves 14 As is indicated by arrows in light lines in FIGURE 8, the water flows from the groove 14 along the land areas 14e and ultimately to the perforations 14b in the cover 14a. In the case of the suction boxes 14, the flow indicated in FIGURE 8 is very slight and is controlled largely by the pressure of the belt 21 against the land areas 14e, but the flow is suflicient to lubricate the rubber belt 21 and prevent its sagging over the land areas 14e. As earlier noted, a higher pressure flow is provided from the grooves 14 in the cover of the suction box 14' in order to more effectively oppose the nip pressure of the roll R.

The belt 21 is, of course, provided with perforations or drainage holes, indicated at 21a in FIGURES 6 and 7. The drainage holes 21a are so mounted in the travelling belt 21 that they do not align themselves with the grooves 141 in the suction box cover 14a. In this way water is not forced back up through the drainage holes 21a. Instead, the drainage'holes periodically align themselves with the perforations 14b in the suction box cover 1411. The bottom side of the belt 21 has, of course, a number of openings formed therein by the drainage holes 2111. Intermediate the drainage holes 21a there are land areas 21b on the bottom side of the belt 21. These land areas normally cover the grooves 14] in the land areas '14e on the top side of the suction box cover 14a. The belt land areas 21b are urged downwardly against the suction box land areas Me by the pressure differential created by the suction boxes 14 or 14'. For this reason water is urged into the grooves 14 under slight pressure to effect continuous seepage of water between the faces of the land areas 14e and 21b. Water seepage at this interface 14e, 21b is necessary to prevent the rubber belt 21 from wiping the land areas 142 dry and thereby increasing the frictional drag. Preferably the seepage of water is very slight, so as not to overload the water removal system for the suction boxes 14 and 14'.

The top side of .the belt 21 is preferably provided with a plurality of longitudinally spaced laterally extending grooves or channels 210. Each such groove 210 is provided with one or more drainage holes 21a, and as shown in FIGURE 7, thegroove 21c is provided with a plurality of drainage holes 21a. The same structure is employed for each of the other grooves 210 shown in cross-section in FIGURE 6.

Functioning in cooperation with the described suction box and belt arrangement, or a suitable equivalent thereof, is the roll R. This roll extends substantially entirely across the width of the wire W and traveling belt 21, and as is shown in FIGURES 1 and 2, the radial center of the roll is essentially in alignment with the vertical axis of the suction box 14. This assures that the nip pressure applied by the roll R will be properly correlated with the groove pattern of the suction box in directly opposed relation thereto. The roll R may be supported for vertical adjustability in a number of different ways, and as illustrated, a supporting arm 34 connecting at one end with shaft 35 of the roll R and mounted for pivotal movement about pivot point 36 carried by supporting structure may be effectively utilized. Any suitable loading or relieving mechanism may be employed to control the'nip pressure, in the manner well known in the art. Further, as earliernoted, the water pressure applied to the groove pattern of the suction box 14' can be adjusted to properly oppose a particular nip pressure applied by the roll R.

For the purpose of markingv and/or compacting the fibrous sheet formed on the upper run 11a of the wire, the roll R is normally employed in direct metal contact with the Fourdrinier wire. However, when it is desired to utilize the apparatus of FIGURES 1 and 2 to disintegrate or break apart relatively hard fibrous masses known in the art as lumps, the circumference of the roll R may carry thereon a covering 37 of felt or the like. Lump breaker rolls heretofore used have not been completely successful in breaking apart these fibrous masses, however, by utilization of a roll R in direct opposition to a vacuum box, particularly when a relatively high water pressure is applied to the groove pattern of that box, the lump formation is more effectively broken.

It may now be seen that by the apparatus and process of this invention expressed water is effectively removed from the forming sheet thereby permitting said sheet to be marked and/ or compacted in a much improved manner, and further, by removing the water from the nip the dandy roll runs more clean for longer periods of time and the cleaning thereof is rendered much less frequent. The suction provided by the apparatus disclosed further resists the back spray from the dandy roll, particularly at relatively high speeds, and the earlier problem of the mat being lifted by the dandy roll is essentially entirely eliminated. In addition, since the dandy roll operates against the relatively flat surface provided by the suction box top, a more gradual closure of the web into the nip is provided as the wire travels through said nip. Also, flutter and vibration problems associated with earlier dandy roll arrangements are avoided. And by utilization of main rolls having belt engaging surfaces substantially as shown in FIGURES 3, 4 and 5, the water film which earlier gave rise to belt slippage problems is released and the belt more effectively guided during its travel about the main rolls. Various other roll surface configurations may, of course, be employed to accomplish these purposes.

It is to be understood that other modifications and variationsmay also be effected in the structures herein discloses without departing from the novel concepts of the present invention.

I claim as my invention:

1. In a paper machine, a traveling forming wire carrying a paper web thereon, a traveling endless perforate belt engaging the bottom side of the wire, a suction box having a generally fiat top and relatively shallow grooves therein, means'furnishing liquid under pressure to said grooves to lubricate the bottom side'of the'belt essentially entirely therealong and thereacross during travel over the box, and a cylindrical member positioned in rolling contact with the paper web above the grooves in the suction box and compacting the web while over said suction box top to remove undersirable fibrous formations therein.

2. In a paper machine, a traveling forming wire carrying a paper web thereon, a traveling endless perforate belt engaging the bottom side of the wire, a suction box having a generally flat top provided with drainage passages and relatively shallow grooves therein, means furnishing liquid under pressure to said grooves to lubricate the bottom side of the belt essentially entirely therealong and thereacross during travel overthe'box, means connecting with the drainage passages for removing expressed water from 'the web, and a roll positioned above the drainage passages in thesuction box compacting the web against the wire during travel over the suction box essentially simultaneously with removal of expressed water from the web through the drainage passages.

3. In a paper machine, a traveling forming wire carrying a'paper web thereon, a traveling endless perforate belt engaging the bottom side of the wire, a plurality of suc tion boxes arranged in a series and each having a generally fiat top provided with. drainage passages and relatively shallow grooves therein, means furnishing liquid at a relatively low pressure to the grooves in certain of the suction boxes and at a relatively greater pressure to the grooves in at least one of the boxes, said liquid lubricating the'bottom side of the belt essentially entirely thereacross and therealong during travel upon the tops of said suction boxes to provide a liquid cushion between said belt and said box tops, means connecting with the drainage passages for removing water from the web, and a roll positioned above the relatively greater liquid pressure grooves compacting the web against the wire during travel over said one of the suction boxes essentially simultaneously with removal of expressed water from the web through the drainage passages.

4. In a paper machine, a traveling forming wire carrying a paper web thereon, a traveling endless perforate belt engaging the bottom side of the wire, a plurality of suction boxes arranged in a series and each having a generally fiat top provided with drainage passages and relatively shallow grooves therein, one of said boxes being of relatively greater depth than the other of said boxes, means connected to a source of liquid under pressure and directing said liquid at a relatively greater pressure to the grooves in the relatively deeper suction box than to the grooves in the other boxes, said liquid lubricating the bottom side of the belt essentially entirely thereacross and therealong during travel upon the tops of said suction boxes to provide a liquid cushion between said belt and said box top, a roll positioned with its radial center in general alignment with the vertical axis of the relatively deeper suction box compacting the web against the wire during travel over said suction box essentially simultaneously with removal of expressed water from the web through the drainage passages, and means for controlling the pressure of the liquid applied to the grooves in the relatively deeper suction box so as to essentially balance the pressure applied by said roll.

5. In a paper machine, a traveling forming wire carrying a paper web thereon, a traveling endless perforate belt engaging the bottom side of the wire, a pair of rolls forming the loop of said belt, at least one of said rolls having raised surfaces thereon frictionally engaging the belt to release liquid and guide the belt during travel thereon, a suction box having a generally flat top and relatively shallow grooves therein, means furnishing liquid under pressure to said grooves to lubricate the bottom side of the belt essentially entirely therealong and thereacross during travel over the box, and a cylindrical member positioned in rolling contact with the paper web above the grooves in the suction box and compacting the web while over said suction box top to remove undesirable fibrous formations therein.

6. In a paper machine, a traveling forming wire carrying a paper web thereon, a traveling endless perforate belt engaging the bottom side of the wire, a plurality of ,suction boxes arranged in a series and each having a generally fiat top provided with drainage passages and relatively shallow grooves therein, one of said boxes being of relatively greater'depth than the other of said boxes, means connected to a source of liquid under pressure communicating with the grooves for flowing liquid between the bottom side of the belt and the suction box to lubricate the same, said liquid lubricating the bottom side of the belt essentially entirely thereacross and therealong during travel upon the tops of said suction boxes to provide a liquid cushion between said belt and said box tops, a roll positioned with its radial center in general alignment with the vertical axis of the relatively deeper suction box compacting the web against the wire during travel over said suction box essentially simultaneously with removal of expressed water from the Web through the drainage passages, means for controlling the pressure applied by said roll, means for controlling the pressure of the liquid to the grooves in the relatively deeper suction box to essentially balance the nip applied by the roll, and means connecting with the roll for increasing and decreasing the load applied thereby.

7. In a paper machine, a traveling forming wire carryiug a paper web thereon, a traveling endless perforate belt engaging the bottom side of the wire, a' plurality of suction boxes arranged in a series and each having a generally flat top provided with drainage passages and relatively shallow grooves therein, one of said boxes being of relatively greater depth than the other of said boxes, means connected to a source of liquid under pressure communicating with the grooves for flowing liquid between the bottom side of the belt and the suction box to lubricate the same, said liquid lubricating the bottom side of the belt essentially entirely thereacross and therealong during travel upon the tops of said suction boxes to provide a liquid cushion between said belt and said box tops, a roll positioned with its radial center in general alignment with the vertical axis of the relatively deeper suction box compacting the web against the wire during travel over said suction box essentially simultaneously with removal of expressed water from the web through the drainage passages, means for controlling the pressure applied by said roll, means for controlling the pressure of the liquid to the grooves in the relatively deeper suction box to essentially balance the nip applied by the roll, means connecting with the roll for increasing and decreasing the load applied thereby, and a pair of rolls forming the loop of said belt, at least one of said rolls having raised surfaces thereon frictionally engaging the belt to release liquid and guide the belt during travel thereon.

References Cited in the file of this patent UNITED STATES PATENTS 762,431 McGrath June 14, 1904 1,025,822 Millspaugh May 7, 1912 1,474,259 Heess Nov. 13, 1923 1,522,579 Ek Ian. 13, 1925 1,928,286 Germanson Sept. 26, 1933 2,503,436 Clark Apr. 11, 1950 2,601,378 Evans June 24, 1952 2,756,649 Lee July 31, 1956