US1865049A - Process for producing felted mineral wool insulation - Google Patents

Description

June 28, 1932. G. D. SHAVER PROCESS FOR PRODUCING FELTED MINERAL WOOL INSULATION F iled Jan. 1, 1931 2 Sheets-Sheet 1 .m H V A. am w m5. W e .m M m e GM VI b June.2s,'1932.- G. D. SHAVER 1,865,049

PRCCESS FOR PRODUCING FELTED MINERAL WOOL INSULATION" Filed Jan. 7, 1951 2 Sheets-Sheet 2 Lu a \nvenTor. George D. Shaver by M M WW Afiys.

Patented June 28, 19 32 v UNITED ST TES GEORGE ID. SHAVER, OF KA LAMAZOO, MICHIGAN, ABSIGNOR TO TEERMINSUL OORPO- PATENT! OFFICE RATION OF AMERICA, 01 BOSTON, MASSACHUSETTS, A CORPORATION OF MASSA- PROCESS FOR PRODUCING FELTED MINERAL WOOL INSULATION I Applicationnled January 7, 1931. Serial No. 507,268.

This invention relates to improvements in felted mineral wool insulation and to processes andapparatus for producing the same.

The principal object of the invention is to provide a material having insulating properties against heat and cold, and wh1ch also desirably is effective insulation against the passage of electric currents, and which also possesses efiicient sound-absorbing properties.

More particularly the object of the invention is to provide an insulation composed wholly or mainly of mineral wool so felted as to produce an occluded cellular structure which will effectively prevent the circulation of air through the material and thereby offer a maximum resistance to the transmission of heat or cold therethrough.

The term mineral wool is used herein as including rock wool, slag wool, or other mineral wools. I

A further object of the invention is to provide a process .for producing mineral wool insulation, of the character above specified in the form of continuous sheets as distinguished from usual methods of producing as sent clean-cut edges, such blocks being selectively of uniform size or of different sizes as may be desired.

vide. suitable apparatus for performing the process necessary to produce the article above described.

-- These and other objects and features of the invention will more fully appear from cal pressure or by air pressure. The particular limitations of such blocks or bricks are in respect to size which is limited by the dimensions of the mould in which the material'is compressed and b the impossibility of satisfactorily controlllngthe densities and thicknesses of the product. By the present invention an improved insulation may be made of mineral wool, with or without the inclusion of other fibres, and with or without size or other binders.

. By the present process also the sheets or blocks are made of such a character as to be self-supporting without the use of fibres or other binders.

The fibres of commercial rock wool contain more or less shot which are attached to the ends of thefibres, or have been detached from the same, the presence of which is undesirable in the insulation. By the present process substantially all'of such shot are removed as are also other heavy foreign materials which are accidentally intermingled with the wool fibres, during the course of its manufacture.

The process of producing mineral wool insulation in'sheet form comprises broadly the mixing of masses of mineral wool with a relatively large quantity of liquid, preferably water, which may or may not contain a suitable binder, agitating the mixture to individu'alize the wool fibres and to disperse them uniformly throughout the liquid, and also to maintain the fibres in suspension therein, then gradually and progressively felting the fibres while beingheld in suspension to pro- .duce a continuous sheet. A further object of the invention is to pro- 'it is desirably caused'to flow preferablyin a sinuous course at: a velocity sufiicient to maintain the fibres in suspension in the liquid, but to permit the shot and. heavy impurities to settle therefrom.

The fibres may be progressively and continuously felted in any suitable manner, preferably by first causing the accumulation of a travelling mass of fibres in a direction counter to the direction of flow of the current of liquid, suspending the fibres so that additional fibres are gradually and progressively collected by the projecting ends of the previously felted fibres until a sheet is formed of a desirable thickness. Such a sheet may be continuously produced and cut in suitable lengths for use as insulation. However, the surface of the sheet thus produced may be more or less uneven and irregular. A further step in the process consists in surfacing and compressing the sheet formed as above described to present a smooth matted surface stratum. Such a stratum may be produced in any suitable manner as by carrying the sheet over a suitable support with a roller, or other device, spaced apart therefrom a predetermined distance sutlicient to determine the desired.

thickness of the sheet, the roller being driven either at substantially the same speed, or at a slightly greater speed than the speed of movement of the sheet, or the sheet may be surfaced and compressed by passing it beneath a suitable blade or between endless belts, or it may be similarly surfaced by suitable hand tools.

Desirably completion of the surfacing may be performed by other means engaging both surfaces of the sheet and exerting a slight compression and frictional action thereupon such as will lay the fibres of the surface zone in substantially the same plane without materially affecting the cellular structure of the central portion of the sheet.

By the process above described a self-supporting sheet may be formed of mineral wool 4 fibres without the inclusion of any other ilbrous or other binding material.

A further step in the process comprises trimming the sheet and severing the same longitudinally hydraulically by small jets of water under high pressure projected upon the sheets in the desired line or lines of severance. Such jets may be held stationary while the continuously formed sheet is passmg beneath them and the, line of severance will present clean-cut sharp edges. Thus the sheet may be cut longitudinally into strips of any desired width.

Another step in the-process consists in severing the continuously produced sheet transversely. This may be accomplished hvdraulically by providing a small water jet of high pressure and moving the same transversely of the sheet either when the same is stationary or during the continuous progress thereof as it is being made in the manner above described. Thus the sheet may be cut into slabs or into blocks of any desired planar dimensions.

V The sheets or the blocks or slabs thus constructed may be subjected to any desirable drying operation which will evaporate the water contained in the interstices of the sheet.

The body of the sheet thus produced after the water has been evaporated therefrom is of such fine interstitially cellular construction that circulation of air through or within the sheet is practically inhibited.

Inasmuch as the insulation thus produced comprises fibrous material which itself is of high insulating properties, assembled as to prevent circulation of air through or within the sheet, practically ideal insulating properties are attained.

bviously insulation of this character is resistant to the passage of an electric current as the mineral wool, which is in effect glass, is an excellent dielectric and the dead air spaces of the cells are themselves excellent electrical insulators.

The insulating material thus formed is absorbent to sound waves and therefore is adapted for use in acoustical and sound-deadening uses.

The process above described may be performed manually or by suitable apparatus such as that illustrated in the accompanying drawings. J

In the drawings:

Fig. 1 is a diagrammatic view of suitable apparatus for making mineral wool insulation in accordance with the process above described;

Fig. 2 is a detail plan view of a preferred mechanism for completing the surfacing of the continuously produced sheet and for dividing the same into strips and/or blocks or slabs; and, I

Fig. 3 is a detail view of the inter-relation between the clutch operating the cut-off device and the gate which predetermines the length severed fromthe continuously travelling sheet;

The apparatus illustrated in the accompanying drawings comprises a separator 1 having a hopper into which the mineral wool is introduced, a downwardly inclined bottom 2, and a. reciprocable screen 3 which is adapted to agitate the wool fed into the separator and to separate the shot therefrom which passes through the screen into the chamber formed by the sloping bottom 2. This cleaner, which is particularly desirable for use with dirty wool, may, of course, be replaced by other devices which will perform the same service, or may be dispensed with entirely where clean wool is employed Without effecting the process.

The wool, which passes from the separator l, is delivered in masses of various sizes to a tank 4 containing a predetermined large quantity of liquid, preferably water, sulficient to produce a batch of mixture for further treatment. In practice, it is found that the relative proportions of six hundred fifty pounds of mineral wool to approximately twelve thousand pounds of water, (approximately one thousand five hundred gallons), produces a satisfactory mixture.- The liquid may be supplied to the tank 4 in any suit-able manner asfrom a storage tank 5 located at a I higher level than the tank. The tank is promaintained a sufiicient length of time to disperse the individualized fibres uniformly throughout the liquid when the batch is ready for further treatment.

After the fibres have been thus individualized and suspended in the liquid, the mixture is dropped through a valve 6 into a storage tank 7 also containing agitators 8 which are driven at a suflicient speed to maintain the individualized fibres in suspension in the liquid. When the agitating tank 4 has been emptied, it is ready for a new batch ofmineral wool fibres and liquid as above described.

From the tank 7 the mixture is forced by a pump 9 to a control box 10 from which it passes'through a pipe having a valve 11 to a rifiie trough 12. The excess of mixture de livered by the pump 9 to the box 10 flows overa partition in said box and is. returned there i from the storage tank, thi's'additional liquid from through a suitable pipe to the storage tank 7. The valve 11 is in'eifect a submerged orifice subject to a constant head, and passes a constant quantity of the mixture from the flow box to the'riflle trough '12. per unit of time. y

The mixture entering the rifile trough 12 is further diluted by additional liquid delivered serving to provide a further dispersion of the individualized fibres. 1

The riflie trough 12, which is slightly inclined, is provided with a suitable series of riffle boards 13 which cause the mixture to flow in an undulated path at a uniform velocity sufficient to maintain the fibres in suspension, but to permit the shot and heavy impurities to settle from the'mixture, but, at a velocity insuflicient to carry the shot and heavy impurities over the baflles, so that the shot and impurities will settle to the bottom of the riflle trough from which they can be removed when convenient in any suitable manner.

The action taking place in therifile trough 12, with the additional water supplied thereto, is an important factor in making a clean 3:18? of mineral felt almost entirely. free of s o The mixture then passes from the rifile trough 12 into ahead box 12-0 of considerably greater width than that of the rifile trough, from which it is delivered in a stream of substantially uniform depth across the width of the head box into the tank 14 of a continuous filter. v I

The .filterdrum comprises a cylinder 15 having a screen surface and divided into a serles of peripheral hollow sections forming suction boxes connected by pipes to the hollow shaft of the filter drum. Suitable valves are provided to apply suction to the sections during their submergence and until just after the boxes pass across the vertical axial plane of the filter.

Suction is applied to the commutating valves'through a pipe 16 which communicates with a separating tank 17 the upper portion of which is connected to a suitable air pump 18. A pipeleads from the bottom of the separating tank to a pump 19 from which the water, which is deposited in a separator tank,

is pumped through a suitable pipe preferably through an intermediate tank to the storage tank 5 which desirably is provided with a valve pipe 21 for delivering water to the agitating tank 4, as above described.

The additional water supplied to the rifile trough is controlled by a valve 20 in a pipe leading through the intermediate tank, so that a desirable solution mixture may 'be maintained in the filter tank 14.

In the operation of the filter the sheet begins to form upon the filter screen. as soon as the suction boxes are released to the suction of the pipe 16 through the commutating valves. The fibres next to .the screen are drawn tightly thereto, while fibres further out from the screen remain fuzzed out in a loose formation in all directions in the mixture. The beginnings of the sheet, together with the drum, and supported upon the surface of' the drum, are travelling at this time in an upward direction.

The'stock or mixture from the head box 12 a is continuously fallingdownwardly into the filter tank 14 and the fibres in this incomward current of water continuously passing through the sheet cause later fibresto be continuously interwoven, felted, and commingled in all directions before in turn being laid down' upon the growing face of the sheet by water passage through the sheet and the sure of continuously addative wool. As shown in Fig. 1 of the drawings, the

pres-- felting begins at approximately the lowest portion of the filter drum and increases in thickness as the suction box of the drum passes upwardly through the mixture, finally emerging from the level thereof as a very looselywoven felted sheet 22. This sheet 22, due to the process of formation above described, and the practically ideal interweaving of its fibres, is the improved mineral wool felt.

Desirably means are provided to compress the sheet to approximately the desired thickness. This is accomplished in the construction illustrated by providing a roller 23, which may be adjustably mounted and located a predetermined distance from the periphery'of the filter drum. The roller 23 exerts a slight squeezing action upon the sheet, thus strengthening and stiffening it before it leaves the filter drum, so that the sheet may be removed from the drum without the use of a doctor blade or usual air pressure means for disengaging it from the drum, thus enabling it to be delivered upon a series of rolls 24 to suitable surfacing rolls 25.

The surfacing rolls 25 are arranged in pairs and adjustably. spaced apart.

Suitable means are provided for driving the rolls at selected dilferent speeds, as, for example, by a countershaft 26 suitably geared to the shafts of the lower set of rolls and driven by a belt through a cone pulley 27.

The density and thickness of the sheet may be controlled by the setting of the rolls 25, the speed of the filter drum, which likewise may be driven at different desirable speeds through a cone pulley 28 or other suitable mechanism, and by regulation of the valve 11 which controls the supply of mixture to the ritlle trough and from it to the filter tank.

It is obvious that if the filter drum is driven continuously at a predetermined speed, and the valve opened to deliver stock at a predetermined rate, a greater pressure of the rolls, caused by adjusting the same toward each other, would produce a thinner and more dense sheet. 1

It is also obvious that-in the absence of the pressure rolls 25, regulation of the flow of the mixture may be made to produce sheets of predetermined different thicknesses. If the valve 11 is set to provide for a predetermined delivery of mixture or stock, regulation in the speed of the filter may be made to produce sheets of different. predetermined thickness. A more accurate regulation of the thickness may be produced by correlating the rate of flow of the mixture and the rate of felting to produce sheets of different predetermined thickness. By providing a desired setting for the rolls to produce a sheet of predetermined thickness, and varying the rate of flow of the mixture, sheets of different predetermined densities may be produced. Furthermore, the density of the sheet may be determined by providing a uniform flow of the mixture or stock from the flow boxes and varying the speed of the filter drum. Thus by correlating the adjustment of the rolls, the speed of the rolls, the speed of the felting drum, and the rate of flow, the thickness and density of the sheet of insulation may be accurately controlled to produce a sheet of a desired uniform thickness and uniform density.

The sheet delivered from the pressure rolls is carried by supporting rolls 29, preferably into the field of mechanism for trimming the sheet, and for cutting the same longitudinally into strips and/or transversely int-o slabs or blocks. In the preferred con-v struction illustrated, (Fig. 2) the cutting mechanism comprises a stand 30 which carries a pipe 31 supplied with water under high pressure. Flexible pipes 32, branching from the pipe 31', lead to nozzles 33 adjustably supported upon a transverse bar 34. The nozz cs 33 may be adjusted to any desired position transversely of the direction of movement of the sheet and project fine cutting jets of water directly upon the sheet. The outermost of these jets may be employed to trim't-he sheets, while intermediate jets will serve to cut the continuously travelling sheet longitudinally into strips.

Suitable means may be provided for cutting the sheet or strips transversely. In the construction illustrateda frame is provided comprising tracks 35 and 36 extending transverscly of the sheet and downwardly extend ing legs 37 and 38 provided with rolls which engage the upper and lower edges of tracks 39- extending longitudinally of the machine adjacent the edges of the sheet. A carriage 40 is reciprocably mounted upon the frame and carries a water jet, or preferably a plurality of water jets 41 which are suitably connected to the pipe 31 by a flexible hose 42.

Preferably two jets are provided, one located at the end of the carriage which passes over the edge of the sheet, and the other jet at the opposite end of the carriage and approximately in the vertical plane of the longitudinal axis of the sheet, so that when the carriage is moved across the sheet, the sheet will be severed throughout its entire width.

The frame may be reciprocated in any suitable manner in synchronism with the movement of the sheet. In the preferred construction a bar 43, which is connected to the carriage, is provided with a rack 44 which engages a suitable pinion 45 upon a clutch 46 one of the members of which is fixed to one of the lower compression roll shafts. The extent of movement of the carriage may be determined by suitable clutch-controlling means. In the preferred construction illus trated such controlling means comprises a bar 47 which is adjustably mounted upon the rear track 37 of the frame and having at its end a pivotally mounted switch member 48 adapted to control an electric circuit 49 leading to a magnetic clutch-operating device 50.

Any suitable means, such as a counterweight, not shown, may be provided for re- 7 turning thevframe after disengagement of the clutch members.

In operation, therefore, when the switch member 48 is engaged by the end of the sheet, the switch of the electric circuit 49 Will be closed, thereby actuating the magnetic clutch-operating device to cause engagement of the clutch members, thus causing the gear 45 to drive the rack bar 43 and advance the travelling frame in synchronism with the movement of the sheet.

Any suitable means may be provided to limit the movement of the travelling frame,

when engaged by a member of the travelling frame to open the electric circuit 49, thereby disen aging the clutch-members and permitting t e travelling frame to be returned by In operation, therefore, the frame will travel longitudinally in synchronism with.

the direction of movement of the sheet.

Suitable valves are provided for controllin the jets 41.

he cutting of the sheet, therefore, into 85 longitudinal strips is produced by the jets pro ected from the nozzles '33 and the trans verse cuttingof the sheet or strips into slabs or blocks is producedflby the reciprocation of the jets supported upon the carriage transversely of the direction of movement of the sheet, as the sheet travels upon its supporting rolls. 'By thus hydraulically cutting the sheet, smooth edges are produced the margins of which are not distortedor condensed as in usual methods of cutting sheets by knives, saws, or otherwise. 1 4 l The narrow edge zones of the blocks when thus hydraulically severed from the sheet are of relatively greater flexibility than the body of the block so that when the blocks are laid edge to ed e and forced toward each other the edge fi res of theblocks will become interlaced and will produce a finel cellular structure having an insulating va ue which compares quite favorably with that of the body of the adjacent blocks. Where a binder, which is soluble in water, such as starch, is employed, the actionof the hydraulic jets in cutting. the sheet into slabs or blocksdissolves and carries away-the majority'o f-the binder along a narrow zone adjacentlto theout, thereby makin the edges of the sheet more flexible than thehody thereof after the drying operation, so pressuch as aswitch 51 in the circuit 49, adapted the. action of the counterweight, not shown.

mechanism for traversing it transversely ofsure applied to the sheets inassembling them edge to edge, causes the fibres of the contacting relatively flexible zone to interlace and embed with each other, so that the assembled sheet presents uniform insulating qualities throughout. Where binders insoluble in water are employed, a similar flexibility may be'imparted to the edges of the sheet by cutting the sheet by jets of, or containing a sufficient quantity of a liquid solvent of the hinder, to remove a substantial portion of the coating of the fibres in the narrow zone adjacent to the cut and thereby reduce the bonding action of the coating.

When the transverse cutting of the sheet 80 has been completed by the jets 41, the cut-ofl", portion of the sheet is removed and the travelling frame is returned in the manner above described to its initial position where it remains until the new end of the sheet strikes the switch 48, when the cycle is repeated.

The slabs or blocks, after having been'cut olf, are removed'and dried in any conventional manner as on rack cars placed in ovens, T or continuously driven rollers or travelling belts passing through the ovens, the ovens being heated in any desired manner.

- By reason of the present invention, therefore, continuous sheets of rock wool insulation of indeterminate length may be produced, or blocks or slabs of any desired size may be made. The sheets thus produced may be of any desired uniform thickness and ofany desired densityd V The action of the pressure rolls 25 upon the sheet, when driven at a slightly greater speed than the sheets, serves to lay-down the .fibres upon the surface zones of the sheets in such a manner as to produce a comparatively smooth and condensed surface which lends rigidity to the sheet and makes it selfsustaining.

By introducing into the mixture a suitable binder, such as starch or asphaltum, adapted to coat the individual fibres before they are assembled in the felting operation, sheets of a vdesired stifiness may be produced without substantially affecting the occluded cellular structure thereof. a

Having thus described the invention, what is claimed as new, and desired to besecured by Letters Patent, is: e V l. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the 7 mixture to individualize the wool fibres,to disperse the'fibres pniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to'flow at a uniform rate sufiiciently rapid tomaintain the fibres in suspensiomand gradually and progressivel felting thefibres while held in suspension y the flowing liquid to produce a continuous sheet of substantially uniform thickness.

2. The process of producing mineral woolsuspension, but to permit the shot and heavy impurities to settle therefrom, and thereafter progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet of substantially uniform thickness.

3. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniform rate sufficient to maintain the fibres in suspension thereafter gradually and progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, and regulating the rate of flow of the mixture to produce a sheet of substantially a predetermined uniform thickness.

4.. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniform rate while maintaining the fibres in suspension, thereafter gradually and progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, and regulating the rate of felting to produce a sheet of substantially a predetermined uniform thickness.

5. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniform rate sufficient to maintain the fibres in suspensi0n,'thereafter gradually and progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, and correlating the rate of flow of the mixture and the rate of felting to produce a sheet of substantially a predetermined uniform thickness.

6. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniformly throughout the liquid and to maintain the fibres in-suspension therein, causing the mixture to flow at a uniform rate sufficient to maintain the fibres in suspension, thereafter gradually and pro gressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, and surfacing the wet felted sheet by friction and pressure and compressing it to a predetermined thickness.

7. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniform rate sufiicient to maintain the fibres in suspension, thereafter gradually and pro gressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, correlating the rate of flow of the mixture to the predetermined thickness to produce a sheet of predetermined density and surfacing the wet felted sheet and compressing it to a predetermined thickness.

8. The process of producing mineral Wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniform rate suflicient to maintain the fibres in suspension, thereafter gradually and progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, correlating the rate of felting to the predetermined thickness to produce a sheet of uniform density, surfacing the wet felted sheet by friction and compressing it to a predetermined thickness.

9. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral Wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniform rate sufficient to maintain the fibres in suspension, thereafter gradually and progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, surfacing the wet felted sheet by friction and compressing it to a predetermined thickness, and correlating the rate of flow of the mixture, the rate of felt- 7 ing, and the degree of compression to tinuous sheet, sur acing the wet felted sheet by friction and compressing it to a p edetermined thickness, and hydraulically trimming the edges of the wet sheet.

11. The process of producing mineral wool insulation in sheet form which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the 7 mixture to individualize the wool fibres, to

disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniform rate suflicient to maintain the fibres in suspension, gradually and progressively felting the fibres while held in suspension by-the flowin liquid to produce a continuous sheet, sur acing the wet felted sheet by friction and compressing it to a predetermined thickness, hydraulically trimming the edges of the wet sheet, and hydraulically cutting the wet sheets longitudinally, as continuously produced, into strips.

, 12. The process of producing insulation blocks of mineral wool which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to. individualize the wool fibres,'to disperse the fibres uniformly throughout the liquid and to maintain the fibres in suspension therein, causing the mixture to flow at a uniformv rate suflicient to maintain the fibres in suspension, gradually and progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, surfacing the wet felted sheet by friction and compressing it to a predetermined thickness, and hydraulically severing the sheet transversely at predetermined desired intervals to produce slabs or blocks.

13. The process of producing mineral wool insulation which comprises mixing masses of mineral wool with a relatively large quantity of liquid, agitating the mixture to individualize the wool fibres, to disperse the fibres uniforml throughout the liquid and to maintain the bres in suspension therein, causing the mixture to flow at a uniform rate suflicient to maintain the fibres in suspension, gradually and progressively felting the fibres while held in suspension by the flowing liquid to produce a continuous sheet, surfacing the wet felted sheet by friction and compressing it to a predetermined thickness, hydraulically trimming the edges of the wet sheet, hydraulically cutting the wet sheets longitudinally, 'as continuously produced, into strips, and hydraulically severing the sheet-s transversely at predetermined desired intervals to produce slabs or blocks. I

In testimony whereof, I'have signed my name to this specification.

GEORGE .D. SHAVER.

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