US2518997A - Production of porous vitreous articles - Google Patents

Description

gp M. A. POWERS I 2,518,997

PRODUCTION OF POROUS VITREOUS ARTICLES Filed Sept. 28,1944 2 shets sheet 1 6" I 25 5 /0 e I a .25 57 e7 6 L if: /4 e7 k! "HT H P ll 6 I I 7 I l A? M i l @g INVENTORL -/V/Z m/vA. POM/5R6 Ina-.1. l

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5 A ron/9s y Aug. 15, 1950 M. A. POWERS PRODUCTION OF POROUS VITREOUS ARTICLES Filed Sept. 28, 1944 MMM/VAP C Patented Aug. 15, 1950 umreo TSTATES PATENT OFFICZE PRODUGTION F POROUS VITREOUS ARTICLES Milton A. Powers, Detroit, Mich.

Application September 28, 1944', Serial No. 556,215

Claims.

This invention relatestomethods and apparatus. tor making porous. products; of permanent shapeirom mineralwools such .as. thewell known glass; and rock wools.

In; my patent, No. 2,271,829, granted February 3., .1942; there. is. disclosedaa processior treating materials of this type by conveying: them. horizontally and flatwisre through a furnace, preferably between two metal. plates, the. upper. plate causing the. softened wool tcssettlev and form a much thinner sheet. of. greater density, When chilled; this sheet, was found to be hard. and somewhat. brittle. and ct -high porosity, yetquite strong. However, this patented process. is sub.- ject to. the. difficulty of maintaining .the plates atvery. accurate temperature. for proper rate of 'heattra-nsfer tothewool. In addition the plates add to operational. costs, and also stick sometimes toth'e. wool.

Temperature control and. heat flow are very importantin. obtaining. a product of adequate strength. and. the. requisite; porosity; The product has the. appearance. of caked: frostv to. the. naked eye, but actually is .fibrous, and. the fibres must be slightly fused and. welded; together uniformly throughout themass. in. order to have maximum strength, particularly where the. product takes the formv oftstoragabattery plate separators that are to be clamped together in assembly The .producthas other uses, as. wicksfor humidifiers,

plates; forfilters, and; in fact any use. wherea cheap. porous article. isdesired; that is resistant to. acids. and. heat.

By: the present invention a mass of wool in sheet or blanket former-preferably in elongated strips: when. obtainableris moved vertically through. a furnacewwith its..flat walls directly exposed to. radiant and? convected heat and. not in contact with any parts. of the furnace except where it enters and leaves. This; preferably is accomplished by pulling the strip. straight upwardiy: through the hot furnace chamber and then, eitherby the pulling. means or by auxiliary means, compressing the softened Wool: into final or semirfinal; shape. Surprisingly, this. pulling action does not tear or appreciably stretch the strip, apparently due tov the factthat the wool fibres, soften quickly and adhere. to one another to.v actually increase the tensile strength of the strip.

In my mp process, the strip is uniformly strong. from end, to. end, of the heating chamber, and thevertioal. movement prevents. any tendency for the strip to bend or weave laterally. The velocity is so; hi h-tour or more feet. per min- 2.. ute,-that;tl;1 e.=wool' instead of cooling toorapidly uponemergfince, is: QQmpressed; before excessive chilling.

Thereiora it is the primary objectv of the present invention. to convert ordinary glass wool or the like into; a hard porous, product that. has adequate strength. for numerous, commercial purposes.

It is a ajor object. of this invention to devise a method for successfullyv handling and. heat treating a blanketoi glass wool: or. the like while moving it vertically and, particularly, while pullinst upwardlyiki thelv major objectv resides in the provision of; a compact and eflicientiurnacethrough which a strip. of: glass, wool: or the like may pass vertically and, particularly, in. an-upward: direction.

The. foregoing and other importantobjects. of my invention will appear from a study ofthefollowing. detailed description when, taken in. conjunction withthe accompanying drawings and theappended claims. In. the drawings:

Fig. 1 is a, viewin perspective of a preferred form of; furnace for carrying out the invention, the. top insulation and' theupper guide plates-he'- 111 1% removed in this; view for clarity of illustra- Fig. 2 represents a vertical section taken substantially upon the plane of line 2+2 in Fig. 1, the guideplate; and: top insulationbeing added;

Fig; Bfrepresentsanother verticalsection, taken mainly alon theiplane of line; 3:- -3i'n. Fig. 2;

Fig. 4 isv a horizontal cross section taken on line 4.-4 of Fig. 3 and Fig. 5; is'a fragmentary detail-view; to enlarged scale, of a section of one. of the pulling and compressing: rolls.

With continued. referencev to; the: drawings, wherein like characters are employed to designatelike parts, the furnace comprises. a. rectangular metalabox 8 supported atits. four vertical corners. by upright legs 9.; and. having secured at two. of its opposedupper edges, from corner to corner, a pair offiat. parallel bars It. The. upper endoi the box is. open. except for added structure later described- Near the bottom of the box there isan internal shelf l2, welded or otherwise attached, shapedv to support tiers of refractory insulating bricks l,3.in,such manner, as shown, as to provide a vertical? heatingv chamber I4 that; is open from end to end and completely surrounded by; brickwork.

The-bottom. of: the box is: nearly closed: by attachment of a pair of parallel steel plates t5, curved, inwardly andrupwardlyi so: that they: are

spaced apart to provide a channel for guiding a strip of fluffy glass wool l6 upwardly into the heating chamber {4 with its side surfaces facing the two chamber walls that are closer together. These plates I5 also serve to direct hot gases upwardly into the chamber and to restrict downward escape of heat. The wool is fed from a table l1, preferably horizontal and disposed close to the plates [5 so'that a minimum of tension will be imposed by gravity upon the strip portion that is traveling within the furnace.

Projecting into the space between each plate 15 and the shelf l 2 there is a bank of gas burners l8, both banks connected to a common gas pipe l9 and individually controlled by valves 20 and supplied with air, as shown.

The heated strip of wool is compressed laterally and pulled upwardly by a pair of oppositely driven rolls 22 and 23 mounted, respectively, by shafts 2d and 25. The shaft 24 is journaled in stationary bearings 26 secured to one of the bars '10, while the shaft 25 is journaled in bearings 21 that are slidable longitudinally of the bars to vary the spacing between the rolls. The shaft 25 is driven by shafting 28 embodying two universal joints 29 that permit the adjustment just mentioned for the bearings 21. The shafting 28 is connected to a stationarily mounted shaft 39 carrying a gear 3! and a sprocket 32, the latter being driven by a chain 34 from any suitable source of power at any desired spee a The gear 3| is in mesh with a gear 35 secured to a shaft 36 that is connected to the shaft 24. The gear sizes, and the working diameters of the rolls 22 and 23, are so related that both side surfaces of the strip l6 are thrust upwardly at substantially equal speeds.

Adjustment of the roll 23 through the bearings 21 is accomplished by a pair of arms 31 (only one of which is completely shown in Fig. 1) that are pivoted on the furnace at 38 and that are apertured at their upper ends to freely surround the shaft 25. Each has an arcuately slotted integral segment 39 through which a clamping bolt 46 passes and extends into screw-threaded engagement with a wall of the furnace box. By loosening the bolts, the arms 37 can be swung to vary the roll spacing.

The previously disclosed gas heating is only auxiliary to an electrical heating system,'which comprises sections of refractory supported electrical heating elements, which are arranged to entirely cover each side of the furnace chamber 14 in fairly close proximity to the glass strip, but sufilciently distant to preclude any possibility of contact during operation. This construction is shown diagrammatically by the supporting posts 43 carrying the heated resistance wires 42 with terminals 44 designed for connection with a suitable source of heating current. Exact control of the temperature inside the furnace is provided by any well known type of temperature controller (not shown), which responds to a'thermocouple located within the furnace proper.

In the apparatus thus far disclosed, the edge portions of the glass strip receive heat from three directionswhereas the main body is heated only on its two sides. Therefore, unless it is desired to cause greater fusion of the edges, it may be desirable to add compensating cooling means, such as that best seen in Figs. 3 and 4. It comprises a pair of vertical pipes 45, capped at their upper ends and arranged adjacent the strip edges; and a pair of smaller tubes 46 disposed within the pipes and designed to discharge cool compressed 4 air into the capped ends of the latter. This air removes heat from the marginal regions of the strip and discharges it through the lower ends of the pipes.

To keep the rolls 22 and 23 at desirable high temperatures, and to minimize heat lost by hot gases escaping from the top of the furnace, a pair of shields 41 are mounted at opposite sides of the rolls and bent to hood the latter and to form an elongated slot, as shown in Fig. 2, through which the compressed glass can take exit. Insulating means may be added, such as masses 48 of glass wool heaped and fitted upon the shields A1.

A stationary fiat guide plate 49 is disposed at one side of the outgoing strip, being supported in that position by an arm 50. At the opposite side there is a complemental plate 52, pivotally connected to a downwardly inclined link 53 which in turn is pivotally connected to a stationary bracket 54. There thus is a tendency for the plate 52 to press the glass strip lightly against the plate 59. The product emerging from these plates is indicated at 55, and any suitable cutting means may be employed to divide this product into pieces of desired size and shape, after which the pieces can be conveyed away from the furnace.

As seen in Fig. 3, the strips outgoing marginal portions 56, which will lack uniformity unless a perfect initial blanket of wool is utilized and unless the process is perfectly controlled, may be cut away as waste material by a pair of circular cutting elements 51 formed integral with and circumferentially of the roll 22.

The product 55 issuing from the illustrated machine is intended to be used, when cut properly, as a substitute for conventional separators for storage battery plates. Therefore, as shown, the roll 22 also has a series of circumferential "grooves 58, which cause ribs 59 to be formed on the product. Of course the furnace chamber may be widened to handle a much wider strip of glass or the like, which later may be divided longitudinally into two or more parts or to handle several narrow strips simultaneously. Also, the shapes of the rolls may be altered, or other forming devices substituted to produce articles of other shapes and/or other densities and thicknesses.

The operation should now be fairly clear. When the furnace has been brought to running temperature a blanket of wool, or a very elongated strip if available, is baited and drawn upwardly through the chamber and thence through the rolls. When only relatively short blankets are obtainable they are spliced together at their ends by wire laces to form a continuous strip. The rolls are adjusted and set into operation to produce a linear speed for the strip of from two to eight feet per minute, depending upon the type of wool and upon the temperatures. Likewise, the chamber length may vary within the approximate range of three to ten feet.

The fibres of the initial wool preferably are long, as much as six inches being desirable; and the fibres, though necessarily somewhat crisscrossed, preferably are arranged generally lengthwise of the strip. This is especially true where, as later explained, the strip is passed vertically downward through a furnace.

In the illustrated example, where the final product is to be battery plates separators, the entering material is glass wool about 2 /2 inches thick. H

The furnace temperature is approximately 1300-1400 degrees F., and the roll temperature about 800-1200 degrees F.

If the rolls are too cold they will chill the material too quickly, and if too hot they will cause sticking. The hot gases penetrate the wool, and a great amount of heat is radiated directly into the sides of the blanket by the electrical units, with the result that the wool gradually softens throughout its entire mass as it rises, gaining tensile strength due to cohesion of the interwelded fibres. Fusion takes place, but not in the sense of fluidity or liquid flow. During its passage to the rolls the wool thickness is reduced by heat, cohesion and tension to about 1 inch. The rolls are set to impart a final thickness, between the ribs 59, of about 0.04 inch to 0.08 inch.

When the wool reaches the rolls it is red hot and somewhat plastic, but after squeezing with simultaneous loss of heat it is nearly self-supporting as it passes through the guide plates 49 and 52. When it emerges from these plates it is substantially hard, and when cooled to atmospheric temperature it is hard and porous throughout. The final product looks white and frosty, but the microscope reveals a mass of clear glass fibers that are criss-crossed, looped and interlocked by fusion welding.

As the strip was approaching the rolls its width naturally decreased. Due to mass uniformity of temperature, and compression at relatively high roll temperature, the grooves 58 were completely filled to produce well formed ribs 59. As previously stated, the product is out into pieces of desired size. This preferably is done while the material is still hot and not yet hard so as to form edges that are smooth and strong.

As a further modification or, rather, a reversal of the illustrated furnace and its operation, the strip of wool might be fed vertically downward through the furnace, the compressing rolls of course then being at the bottom. In such event a set of gripping rolls or their equivalent would be necessary at the top of the furnace to feed the strip and to keep it in tension, and perhaps an intermediate set would be needed to prevent excessive and destructive pull upon the upper end of the hot strip. Unless, however, wool of long fibre and high strength is used, this modifled method can not'produee the excellent results obtained by the preferred, illustrated embodiment.

What is claimed is:

l. A process for converting glass wool or the like into a hard porous product, comprising the steps of moving a substantially self-sustaining blanket of the wool substantially vertically and freely straight while under tension through a hot chamber that is substantially closed everywhere except at the bottom, applying heat to the blanket solely by radiation and convection to cause the wool fibres to become thoroughly interwelded, and cooling the wool to rigidity upon emergence from the chamber.

2. In the process defined in claim 1, said blanket being flat and wide, and its edges being subjected to a cooling medium during travel to prevent them from overheating.

3. The method of converting a preformed blanket of fluffy glass wool or the like into hard porous products, consisting in pulling the blanket upwardly and freely through space under sufficient tension and sufficient temperature to thoroughly interweld its fibres and to simultaneously reduce it gradually in width, and thereafter pressing it while soft into sections of predetermined shapes.

4. Apparatus of the class described, comprising a furnace designed to heat a flexible sheet of material such as glass wool, means affording a substantially horizontal surface adjacent the furnace bottom for supporting and guiding the sheet, means adjacent said bottom for guiding the sheet upwardly into the furnace, and means adjacent the top of the furnace for pulling the sheet upwardly and discharging it outwardly.

5. In the apparatus of claim 4, a pair of guide plates mounted to receive the discharged sheet between them and to slidably engage the side surfaces of said sheet.

MILTON A. POWERS.

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

UNITED STATES PATENTS Number Name Date 683,983 Reeves Oct. 8, 1901 890,252 Thompson June 9, 1908 1,480,625 Miller Jan. 15, 1924 1,769,181 Jackson July 1, 1930 1,940,975 Shaver Dec. 26, 1933 2,926,781 Geer Jan. 7, 1936 2,172,153 McClure Sept. 5, 1939 2,195,310 Hotchkiss Mar. 26, 1940 2,271,829 Powers Feb. 3, 1942 2,328,078 Kugler Aug. 31, 1943 2,344,601 Collins Mar. 21, 1944 2,373,077 Kleist Apr. 3, 1945 2,382,290 Callander Aug. 14, 1945 2,417,094 Spinasse Mar. 11, 1947

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