US2450900A

US2450900A - Machine for forming articles from a liquid slurry

Info

Publication number: US2450900A
Application number: US484220A
Authority: US
Inventors: John D Lyall
Original assignee: Armstrong Cork Co
Current assignee: Armstrong World Industries Inc
Priority date: 1943-04-23
Filing date: 1943-04-23
Publication date: 1948-10-12
Anticipated expiration: 1965-10-12

Description

ca. 12, 1948. I 1 J. D. mu; 2,450,900

' MACHINE FOR FORLIING ARTICLES FROM-A LI QUID SLURR'; Filed April 25, 1943 '.'\S

s to I; L

5|. Ill 20 II I!" i l I DISCHARGING STAT ION .VALVE cLosEs f v SCREEN CLEANING STATION PRESSING STATION FILLING BOOTH REMOVING I J ILLTING BOOTH APPLYING STATION L RRY' FILLING STATION Patented Oct. 12, 1948 OFFICE ARTICLES FROM A LIQUID SLURRY dohn D. Lyali, Lancaster Township, assignor to Armstrong pany, Lancaster, Pa'., a corporation County, Pa.,

vania Lancaster Cork Comoi' Pennsyl- Application-April 23, 1943, Serial No. 484,220

:Claims.

This invention relates toan apparatus for the manufacture of articles from liquid slurries, such as the formation of mineral wool insulating blocks from a slurry of mineral wool fibers, paper pulp fibers, and asphalt in water. This invention finds its most usefulness in machines of the rotary type in which a train of molds is intermittently moved in a closed path into a series of operating stations where various steps in the manufacture of the blocks are performed, such as charging the mold with slurry, draining, compressing, and discharging the completed blocks. I

In themanufacture of articles such as mineral wool insulating blocks, the slurry is relatively low in fiber content and to form a block 36 x 36 x 4 inches, for example, a large volume of slurry is required, weighing in the neighborhood of half a ton or more. 'The removal of water from a slurry of this character is normall relatively slow, particularly as the thickness of the fibers deposited on the screen builds up and constitutes a barrier to the free passage of the liquid. In some instances, the screen will be actually sealed and removal of the water will be impossible. In stationary molding, this can be overcome by the use of vacuum pumps effective for creating an area of reduced pressure below the screen. In

rotary machines, however, the problem of commutating the suction from a vacuum pumpto a series of rotating molds is difllcult and expensive. The primary object of this invention is to quickly and without complicated vacuum pump equipment remove liquid from a slurry in a mold while the mold is in motion or is intermittently, moved along a path of travel.

Another object is to provide an arrangement by means of which the density of the product to be produced on a forming machine may be varied in accordance with the speed of removal of liquid from the slurry.

According to this invention, the mold is provided with a discharge tube disposed below the mold;

' of air into the system screen in the mold. The tube is in substantially fluid-tight, open communication with the -mold below the screen; is sealed against the entrance of air from below; but is arranged to freely discharge water received from the slurry in the mold. The seal for the tube is preferably formed by a water bath into which the tube projects and this bath is in the path of travel of the molds so that a seal is effected as the molds move along the path and water is discharged from the'slurry. The eifective length of thetubehas an effect on the speed of removal of water 'from the slurry in the mold. By this arrangement, it is possible to vary elevation for sake of clarity;

Figure 2 is a schematic view of an arrangement for controlling the valve Figure 3 is a diagrammatic view indicating the location of various operating stations along a path of travel ofa rotary forming mold; and

Figure 4 is a sketch diagrammatically illustrating the manner in which rapid drainage is effected and showing a modified embodiment of my invention in which the speed of withdrawal of the slurry is controlled by permitting the entrance below the screen in the mold.

Referring to Figure 1, a part of a rotary mold arrangement is illustrated in'section. For a more complete disclosure of a modern rotary forming machine suitable for the manufacture of mineral wool insulating blocks and the like, reference is made to the copending application of Boyd R. Abbott, Serial No. 482,645, filed April 10, 1943, entitled "Forming machine. The device consists essentially of a mold 2 (the lower portion only being shown in Figure 1). The mold 2 is provided with a screen or similar perforate bottom 3 adapted to receive the solids of the slurry but pass the liquid. A fluid-tight-chamber 4 is disposed below the mold 2 and the mold is sealed against this chamber by a gasket 5. A filling booth may be disposed above the mold 2 to receive the slurry to be molded may be removable as shown in the Abbott application above referred to. The shape and structure of the mold and filling booth are not important insofar as the'present invention is concerned.

Disposed below the mold 2 and in substantially fluid-tight, open communication therewith is a tube 6, which is connected to the mold 2 below upon rotation of the and this filling booth adjusting the position of the outlet tube I i, the effective length of the tube 6 may be varied since, as is well known in hydraulics, the effective length of the tube for purposes of determining speed of flow is from the upper level of'the fluid therein to the level at which the fluid is affected by the atmosphere. which, in the present case, is the level of the liquid ill in the sump l.

The valve 1 is shown immediately below the chamber 4 in Figure 1 since in that position it may be conveniently controlled from above and is readily accessible. As shown diagrammatically in Figure 4, however, the valve may be positioned at the lower end of the tube and actuated by a similar control arrangement as there indicated. By the latter arrangement, the entire system will be filled with liquid when the valve is opened and the head effect will be immediately available as will be more fully described.

Referring now to Figures 1 and 3, the mold 2 is mounted upon a carriage I! for rotation in a closed path on tracks i3 and H. The valve 1 is controlled through an operating dog i8 which is secured to a shaft i1 attached to the stem l8 of valve 1. A bearing bracket i9 attached to the chamber 4 serves to support the shaft if. A control bar 20 is positioned in the path of travel of the molds and is adapted to engage the dog i8 to impart a motion of rotation thereto effective for opening the valve 1. A similar bar 2i is positioned at another point along the path of travel of the mold and this bar is effective for engaging the dog 18 to close the valve 1.

The operation of the valve control arrangement is shown in Figure 2 where the dog i8 attached to its mold is moving in the direction of the horizontal arrow. Upon engagement of the upper leg of dog IS with the control bar 20, dog l8 will be rotated in a counterclockwise direction as indicated by the arrow, the dog i8 passing under the horizontally directed flange of the control bar 20. When the mold is moved to the position where the valve I is to be closed, the lower leg of the dog it will come into engagement with the horizontally disposed flange of a control bar 2i and a clockwise motion of rotation will be imparted to the dog I! as shown in the righthand portion of Figure 2, resulting in closing of the valve 1. The dog I8 passes over the horizontal flange of control bar If as indicated in Figure 2.

The positions at which the control bars are located in a typical rotary forming machine are shown in Figure 3 where the control bar 20 is' positioned adjacent the slurry filling station and the control bar II, which is effective for closing the valve, is disposed between the stations at which the completed block is discharged and the mold screen is cleaned. The location-oi the control bars may be changed to suit the particular requirements of the article being formed and in some instances the valve may be found unneces- In Figure 3, a machine of the type disclosed in the Abbott application is schematically portrayed. Only one mold 2 is shown in order that the general arrangement of the tracks, sump, and overflow tube may be better indicated. In such a machine, the slurry is charged at the slurry filling station, the mold is moved intermittently along the tracks i3 and i4 and; as each mold moves past operating bar 20, its valve I is opened and drainage of liquid from the slurry commences. As the water flows from the slurry through the screen 3, it passes into the chamber 4, through the valve 1 and the tube 6 into the sump L There is no increase in the general level of the water ii in the sump. however. for as water is discharged through the tube l, a corresponding quantity of water flows through the overflow ll. Drainage is accomplished continuously as the mold moves about its path. The filling booth in then removed in advance of a station where pressing is accomplished, if this is found necessary.

The completed block is then discharged from the mold. As each mold moves from the discharging station to the screen cleaning station, its valve 1 is automatically closed. The screen is cleaned by showerheads which spray water onto the screen and remove any particles which may be embedded in the interstices. Since the valve I is closed when the mold is in this station, the water, which is used for cleaning, fills the chamber 4. After cleaning, a filling booth is applied to the mold and it then moves to a filling station and the operation is repeated.

Referring to Figure 4, there is diagrammatically shown the action that takes place in the removal of water from the slurry 8. As the water is drained from the slurry S, the fibers or other solids suspended therein tend to accumulate in a mass 22 above the screen 3, which mass impedes the free flow of water through the screen. The velocity of movement of the water through the mass 22 is accelerated, however, by reason of the head of water H lying within the tube 6. This may be explained as follows. The force of the atmosphere is pressing on the mass of water ill in the sump 8 and a similar force is being applied to the top of slurry S which is also exposed to the atmosphere. When the flow of liquid from the slurry S into the sump B is unimpeded, the pressure across the screen is substantially zero. However, as the fibers 22 above the screens i tend to form a seal and impede the flow of water therethrough, there results a reduction in pressure immediately below the screen 3. This reduction is equal to the difference between atmospheric pressure on the mass of water Ill and a pressure determined by subtracting the pressure of the head H from the atmospheric pressure. The pressure in the tube 8 gradually diminishes from a point at the level of the liquid i0 toward the upper end of the tube and would approach zero absolute pressure at about 33 feet (depending upon atmospheric pressure). Thus, there is a difference in pressure between that of the atmosphere which is tending to force water through the mass of fibers 22 and the pressure of the liquid immediately below the screen I which, as previously stated, is less than atmosphere, approaching zero, depending upon the length of the head H. This pressure diflerential results in movement of the water from the slurry through the barrier 22, into the chamber 4 and through the tube 0.

With a mold for the formation of mineral wool blocks 36 x 36 x 4 inches, a four-inch diameter discharge tube has been used and the effective length has been variable from a few inches to a total of about 6 feet. The difference in the speed of water removal between a head of about a foot and a six-foot head is manifold with a relatively dilute slurry of mineral wool and paper pulp fibers which tend to mass on the screen aud quickly foi'm a barrier.

-I have also found that the difference in pressure determines to a considerable extent the density of the product. If the water is withdrawn rapidly by the use of a tube having a relatively extensive effective length and consequently a sizable difference n pressure from the line of sealing to a point below the screen, the product will be much denser than where a tubehaving a relatively shorter larly at the discharge opening 9, the water bath l should be maintained above the level of the outlet opening 9.

If a further adjustment of the speed of withdrawal-of the water is desired it can be eifected by the use of an air inlet valve 23 below the screen as diagrammatically shown in Figure 4. By the use of such an arrangement, air maybe introduced into the system below the screen 3 and as the water moves down the exhaust tube '6, air will flow into the chamber through the inlet valve 23. This valve 23 maybe so arranged that air is admitted only upon the creation of an area of reduced pressure below the screen 3. permitting the force of ambient atmosphere to open the valve 23. The control valve 23 is preferably of the type which opens at a predetermined pressure for then the amount of pressure applied to the fibers being formed may be nicely controlled, the valve 23 automatically opening when a predetermined pressure reduction is effected below the screen, closing when equilibrium has been reached. Thus, the density of the final product may be generally" controlled by the effective length of. the discharge tube and-more minute control of density effected by control of the supply of air to the zone below the screen.

While I have illustrated and described a pre-.

ferred embodiment of'my invention, it will be understood that the same may be otherwise embodied and practiced within the scope of the following claims.

I claim: Y

1. In a machine for the manufacture of mineral wool board and the like in which molds are moved along a'path' of travel into various operating stat'.ons, a closed tube extending below the mold and movable therewith, said tube having 1 its outlet sealed in a water bath, and means for maintainin 'a predetermined level of water in said bath.

2. In a machine for the manufacture of mineral wool board and the like from a liquid slurry in which a mold is moved along a path of -travel into various operating stations and in which the mold has a perforate member upon which the solids of the slurry are deposited and tend to prevent the free passage of liquid from the slurry, particularly when the solids build up on the perforate member, a discharge tube extending from said mold below'said perforate member and movable with said mold, a liquid seal for sealing the outlet of said discharge tube, preventing the passage of air upwardly therethrough, and means for changing the level at which said liquid seal is efiective on said tube to thereby change the effective length of the tube.

3. The combination in a machine for the manufaeture of mineral wool board and the like from a slurry of fibers in water in which a'mold havin a perforate member upon which the fibers of the slurry are deposited is moved along'a path of travel into various operating stations of means for accelerating the removal of water from the slurry comprising a discharge tube extending from the mold below the perforate member, a

, free entrance of air therelnto bath of liquid positioned in the path of travel of said discharge tube andinto which said. discharge tube depends to seal the outlet of said tube against the passage of air upwardly therethrough;

water, a mold movable along a pathoi travel into various operating stations, a screen in said mold upon which the fibers of the slurry may be deposited, a discharge tube extending from said mold below said screen, and means positioned in the path of travel oi said mold and tube for receiving a water bath, said tube extending into said bath and being sealed thereby during movement of said mold and tube along the path of travel.

5. In a machine for the manufacture of mineral wool board and the like from a slurry of fibers in water, a mold movable along a path of travel into variousoperating stations, a screen in said mold I upon which the fibers of the slurry may be depos lted, a chamber in substantially fluid-tight relationship with said mold and disposed therebelow, a discharge tube extending from said chamber in substantially fiuid tight open communication therewith, said discharge tube being movable with said mold, means for forming a liquid seal in said tube below the upper end thereof to prevent the iromany point below said screen, and means for changing the level at which said liquid seal is eii'ective on said tube to thereby change the effective length of the tube.

6. In a machine for the manufacture of mineral wool board and the like from a slurry of fibers in water, a mold movable along a path of travel into various operating stations, a screen in the bottom ,of said mold upon which the fibers of the slurry may be deposited, an arrangement for creating a zone of reduced pressure below the screen in the mold as the mold is in movement comprising a discharge tube disposed below said screen in substantially fluid-tight open communication therewith and movable with. the mold. and means for forming a liquid seal in said'tube below the upper end thereof to prevent the free entrance of air therelnto from any point below said screen.

7. In a machine for the manufacture of mineral wool board and the like from a liquid slurry in which a mold is moved along a-closed path into various operating stations, a sump disposed along said path and open to atmosphere, a discharge tube extending from said mold into said sump, said discharge tube being movable with said mold, and means for maintaining a predetermined level of water in said sump above the outlet end of said discharge tube.

8. In a machine for the manufacture of mineral wool board and the like from a liquid slurry in which a mold is moved along a path of travel into various operating stations, an arrangement for accelerating the withdrawal of water from said mold as it is moved along its path of travel comprising a tube extending from said mold into a liquid seal open to atmosphere, and means for moving said mold and tube along said path with which a mold is moved along a path into'various operating stations, a sump for receiving liquid discharged from the slurry, an overflow disposed assa aoo 1 8 let of said tube against the passage of air upwardly therethrou h during movement with said tube through the liquid in said sump during I movement of the mold along its path of travel, a rforate member in the bottom of the mold upon hioh the fibers of the slurry may be deposited, a alve responsive to a predetermined reduction in pressure positioned below said screen to open automatically when a predetermined pressure reduction is effected below the screen to admit air.

below the screen and prevent further reduction in pressure whereby the density of the product formed in the mold may be controlled.

10. In a machine for the manufacture of mineral wool boardand the like from a liquid slurry, a mold movable along a path of travel into a plurality of operating stations, perforate means forming the bottom of said mold to receive the solids from said slurry to be molded and forming a barrier to the free passage of water from said slurry. a chamber secured to said mold below said perforate member, a tube secured to and extending from said chamber, means for sealing the outmold and its associated chamber, said chamber and tube constituting a closed system below the perforate plate in the mold for the suction of liquid from the slurry deposited in the mold above the perforate member during movement.

JOHN D. LYALL.

REFERENCES CITED The following references are of record in the file of this patent:

uiwrmn s'ra'rns PATENTS 15 Number Name Date 1,706,874 De Journos, Mar. 26, 1929 1,962,477 Broughton June 12, 1934 1,995,586 schopper et a1. Mar. 26, 1935 2,101,921 Shaver Dec. 14, 1937 20 2,352,991 Vlckery July 4, 1944 FOREIGN PATENTS Number Country Date 760,653 France Dec. 14, 1933 25 322,575 Germany July 3, 1920 495,841 Germany Nov. 14, 1930 ea2,a 94

Germany Oct. 26, 1939