US 3908745 A
Apparatus and method are described for continuously withdrawing filaments, wire and the like of uniform configuration from a bath of molten material, solid at ambient temperature, by immersion of the periphery of a rotating disc therein wherein the depth of immersion of the disc in the molten bath is automatically maintained substantially constant, continuously, irrespective of changes in the level of the bath.
Description (OCR text may contain errors)
United States Patent Caldwell et al.
1451 Sept. 30, 1975 METHOD AND MEANS FOR PRODUCING FILAMENTS OF UNIFORM CONFIGURATION Inventors: Thomas W. Caldwell, Hightstown;
Richard A. Garini, Howell Twp., both of NJ.
Assignee: NL Industries, lnc., New York, NY.
Filed: June 21, 1974 Appl. No.: 481,496
1m. c1. B221) 11/06 Field of Search 164/87, 276; 7 /309; 264/8, 215, 311, D16. 19; 65/8, 15
References Cited UNITED STATES PATENTS 2/1944 Rover 73/309 3,789,909 2/1974 Smith 164/87 3,812,901 5/1974 Stewart et al 164/87 3,838,185 9/1974 Maringer et al. 164/87 X 3,843,762 10/1974 Sleigh 164/87 X FOREIGN PATENTS OR APPLICATIONS 1,040,498 8/1966 United Kingdom 164/87 Primary Examiner-Francis S. Husar Assistant E.\-mn1'ner-John E. Roethel [5 7 ABSTRACT Apparatus and method are described for continuously withdrawing filaments, wire and the like of uniform configuration from a bath of molten material, solid at ambient temperature, by immersion of the periphery of a rotating disc therein wherein the depth of immersion of the disc in the molten bath is automatically maintained substantially constant, continuously, irrespective of changes in the level of the bath.
10 Claims, 7 Drawing Figures Vlbrollon Dumpener US. Patent Sheet 1 0f2 a mm Sept. 30,1975
US. Patent Sept. 30,1975 Sheet 2 of2 3,908,745
METHOD AND MEANS FOR PRODUCING FILAMENTS OF UNIFORM CONFIGURATION BACKGROUND OF INVENTION In general, the use of rotating discs for producing filaments, wire and the like of predetermined length directly from a reservoir of molten materials, normally solid at ambient temperatures, is well known in the art. The invention of French Pat. No. 2,139,020 is typical of the method and means used to produce solid filaments of predetermined length from a molten material, such as for example molten metals, metal alloys, inorganic or organic compositions and the like, wherein the periphery of a rotating disc is presented to the surface of the molten material and heat is continuously removed from the periphery of the disc to provoke solidification of the material thereon as a filament or wire which is continuously thrown from the periphery of the disc by centrifugal force. As illustrated in the aforesaid French patent a manually operated jack 45 is provided for adjusting the position of the rotating disc relatively to the level of the bath.
The configuration of the filaments formed on the disc depends on several factors including the speed of rotation of the disc, the temperature differential between the disc and bath, the shape of the periphery of the disc and the depth of immersion of the disc in the bath. However, despite careful control of these parameters the configuration of the filaments, i.e., thickness and width have been found to vary to such an extent as to be unacceptable for the purposes intended.
It has now been found that these variations in width and thickness are caused primarily by a change or changes in the depth of immersion of the disc in the melt during production of the filaments or wires. While the manually operated screw jack of the aforesaid French patent may suffice for an initial adjustment of the rotating disc relative to the level of the bath this form of manual control is not amenable to continuous adjustment of the disc relative to a changing bath level; is subject to individual error, nor does it provide the sensitivity and accuracy required in operations of this kind for continuously producing filaments of uniform configuration.
SUMMARY OF THE INVENTION The instant invention relates in general to the continuous production of filaments or wires of uniform configuration by automatically and continuously maintaining the depth of immersion of a rotating disc in a bath of molten material substantially constant concomitantly with changes in the level of the bath. More particularly, the constant depth of immersion of the disc in the molten bath is maintained continuously and automatically by adjusting the effective density of the disc according to the physical laws of buoyancy. Specifically, the invention provides novel supporting means for the rotating disc, including the disc drive means and accessory equipment, said supporting means being capable of adjustment for affecting changes in the effective density of the disc corresponding to the buoyant forces acting on the disc due to immersion of the disc in the bath. Thus, having made an initial adjustment of the disc supporting means for supporting the disc at a predetermined depth in the molten bath the depth of immersion of the disc will remain constant irrespective of any change in the level of the bath, i.e., either while justments thereof; and dampening means for absorbing any vibration attending rotation of the disc thereby precluding even slight variations in depth of immersion in the bath.
While the foregoing description makes reference to the use of a single disc it will be understood that the invention contemplates the use of one disc or a plurality or gang of discs on a single shaft as illustrated below.
DESCRIPTION OF DRAWING FIG. 1 is a schematic perspective view of one embodiment of the filament-forming means of this invention;
FIG. 2 is a schematic side elevation of one form of disc used in the apparatus of FIG. 1;
FIG. 3 is a vertical elevation on section line 33 of FIG. 2 showing the hollow construction of the hub which supports the disc;
FIG. 4 is a side elevation of a modification of the wheel of FIG. 2;
FIG. 5 is a side elevation of a further modification of the disc of FIG. 2;
FIG. 6 is an elevation in section of a further modification in which a plurality or gang of discs are mounted on a single axle; and
FIG. 7 is a fragmentary view of the disc supporting means of FIG. 1 showing the use of a float associated therewith.
PREFERRED EMBODIMENT OF INVENTION Referring to the drawings, the reservoir or tank for holding the molten material is schematically indicated at 10 mounted on a suitable support 11. A suitable heat source (not shown) is adapted to supply heat to the tank 10 to maintain the material therein molten. The material 12 forming the bath may be supplied to the tank 10 in any suitable way, as for example as a liquid fed into the tank 10 by feed pipe 13; or by introducing solid material in the form of metal pigs, discrete particles, wire and the like which melt upon entering the bath, typical materials suitable for forming filaments or fibers according to the improved process of this invention being materials which are solid at ambient temperature, and which include metals and metal alloys, latex (for forming rubber filaments) and certain fusible salts as for example stearate ammonium nitrate for use as fertilizer.
One embodiment of the film forming disc is shown at 14 in FIGS. 1 and 2. This is a relatively thin metal disc having a central aperture 15 (see especially FIG. 3); and is assembled between integral hollow hub portions 16--l6 which form a chamber housing the central portion of the disc. The periphery of the disc projects beyond the chamber and may be a relatively narrow surface such as a knife edge but is preferably a narrow but substantially flat surface, as indicated at 17, for producing substantially flat filaments of consistently uniform width. The wheel 14 and in particular its periphery is cooled by a liquid coolant such as for example water arranged to be circulated through the hollow hub portions l616 and central aperture of the disc and to this end a hollow axle or drive shaft 18 is welded or otherwise secured to each hub portion in communication with the interior thereof said hollow drive shafts being in axial alignment. One of said shafts constitutes the inlet for supplying a coolant from a source (not shown) to the hollow hub portions of the disc and the other an outlet for discharging the coolant therefrom. As will be understood by those versed in the art by circulating a coolant through the chamber formed by the hub portions of the disc, during rotation of the latter in the molten bath, the temperature of the periphery 17 of the disc is maintained relatively low as compared to the temperature of the bath as a consequence of which molten material from the bath solidifies on the periphery of the disc in the form of an elongated filament or wire which, upon leaving the bath is thrown or otherwise remove from the rotating disc.
The rotating cooled disc should be selected from metals which are used normally in other moulding processes. For example, a copper metal disc may be employed successfully when metal fibers of lead, zinc, tin, magnesium and aluminum are produced. Metal fibers having higher melting points such as iron and nickel alloys may also be produced using copper or bronze discs. Further, the invention contemplates treating the vertical sides of the disc with suitable materials, as for example an oxide coating, which treatment has been found to prevent molten bath material from adhering to the sides of the disc thereby ensuring flat filaments of substantially uniform width. It is also within the purview of the invention to employ, if necessary, a scraping device or air jet (not shown) to supplement centrifugal forces in dislodging the filaments from the periphery of the rotating disc.
Turning now to the disc supporting means, one embodiment of the latter is illustrated in the drawings and indicated generally by the numeral 20. This comprises, in part, a rockable plate provided with a cut-out 21 in its front edge located immediately above the vessel 10 for accommodating the disc 14. The disc is assembled on the rockable plate by mounting its hollow shafts 1818 in suitable bearings 1919 secured to the top size of the plate at opposite sides, respectively, of the cut-out 21. As shown especially well in FIG. 1 the rockable plate 20 is supported for rocking movement in a plane substantially perpendicular to the plane of the molten bath 12 by a pair of pins 22-22 of knife-edges fixedly secured on the underside of the plate 20 intermediate its front and rear edges and at opposite ends thereof, respectively, each pin being fulcrumed on a hardened metal block 23 or equivalent support means mounted on the table 11. As shown schematically in FIG. 1 drive means for the disc 14 comprises a motor or equivalent power source 24 mounted on the top side of the rockable plate 20 and connected to shaft 18 of the disc 14 by belt and pulley. Consistent with the concept or adjusting the effective density of the rotating disc to correspond to the buoyant forces acting of the disc when immersed in the molten bath the combined weight of the rockable plate 20, the disc 14 and its drive means is adapted to be substantially balanced by counterbalancing means indicated generally at 25. In the embodiment of the invention shown herein this may comprise an arm 26 suitably secured at its forward end to the rear edge of the plate 20 and provided at its rear extremity with an adjustable weight 27 threadedly mounted thereon whereby adjustment of the latter may be made simply by moving the weight forwardly or rearwardly as the case may be.
The above described counterbalance means is of relatively simple and inexpensive construction and wholly satisfactory as means for adjusting the effective density of the rotating disc. It will be understood, however, that other equivalent counterbalancing means are contemplated with the scope of the invention.
Using the adjustable counterbalancing means described above, the disc supporting means, i.e., the plate 20 may be rocked into position such that the periphery of the disc 14 will be completely clear of the molten material in the vessel 10; or by suitable adjustment of the weight 27 the plate 20 may be rocked into position such that the periphery of the disc is immersed in the molten bath to any selected depth. Upon entering the molten bath the disc will be subject to the physical laws of buoyancy as a consequence of which further adjustment of the weight 27 may be required in order to hold the disc in the molten bath as the preselected depth. Having thus made an adjustment of the weight 27 in accordance with the effective density of the disc 14 the latter will be maintained, by the counterbalance means, automatically and consistently at the preselected depth in the molten bath irrespective of changes in the level of the bath. Hence, in a continuing operation of the disc the filaments or wire thrown off its periphery will be of substantially uniform configuration despite constant lowering of the level of the bath. In this connection, it has been observed that the rockable plate 20 may be subject to vibration at high rotational speeds of the disc. Hence, to preclude this tendency and hence possible variation in configuration of the filament or fiber it is within the purview of the invention to equip the rockable plate 20 with viscous or magnetic damping means, or the equivalent as illustrated by shock absorbers 28-28 connected to the forward edge of the plate 20 and to the table or platform 11.
While FIGS. 1 and 2 depict a disc 14 having a substantially flat continuous peripheral edge for forming flat filaments or wires of substantially continuous length modifications of the disc are contemplated within the scope of the invention. Thus, FIG. 4 illustrates a disc 29 similar to that shown in FIG. 1 except that the periphery of the disc is provided with a plurality of substantially equally spaced notches 30 the effect of which is to cast off relatively short lengths of filament or wire; while the filament-forming disc 31 of FIG. 5 has a knife-edge periphery 32 and one notch 33 the effect of which is to produce discontinuous but relatively long filaments or wires. In this connection it should be mentioned that where surface of the filaments is critical that for a given change in depth of immersion in the fiat edge of a filament-forming disc produces substantially less variation in surface area of the filaments formed therein, than a disc having a knife edge. A still further modification of the filamentforming disc is shown in FIG. 6. In this embodiment a plurality or gang of discs 34 are assembled in substantially parallel planes between hollow hubs 3838. FIG. 6 also illustrates an alternative arrangement for cooling the discs wherein each hub 38 is provided with a sleeveportion 39, each disc is provided with apertures 40 adjacent its periphery and a one-piece tubular drive shaft .onplug 43 is inserted in the tubu r sh its wall adjacent theouter faces of firstand last discs, respectively of the .gang of discs and-a core h ir ss a apertures 42 whereby a coolantpassing into one end of the shaft is deflected outwardly throughv said apertures 42, through the apertures 40 of the first and successive discs. thereby cooling the. peripheries,- thereof the coolant passing from the last disc into the apertures 42 at the opposite end of the tubular shaftandthence out therefrom. .7
A modification of the counterbalancemeans of this invention is shown in FIG. .7. The effective density of the disc 14, as determined by. the laws of buoyancy,,is dependent onseveral parameters including the specific gravity of the molten material of the bath and-the density of'the disc. There may, of course, be'circumstances in which the specific gravity of the bathand density of the disc including the rocking'plate, are-such that relatively large andhence insensitive adjustments of the counterweight 27 'a're-"required. For these conditions lh invention contemplates supplementingtlie counter-- balance means by providing the rockable plate with afloat 44 supported inthe'molt'en bath 12 by an arm or equivalent support means 45 extending forwardly from the leading edge of the base-plate 20. The float is made of a suitable material, such as cast iron, to with-' stand the heat of the molten bath, and may take any suitable shape as for example a sphere. Preferably, however, the float is in the form of a cast iron cup to which shot may be added or from which shot may be removed to compensate for large differences between the density of the disc and the specific gravity of the melt and thus making possible relatively sensitive adjustments of the counterweight 27.
The following examples will further illustrate the invention hereinabove described. 0
EXAMPLE 1 A gang-type disc assembly was used comprising five water-cooled discs 14 each 6 inches in diameter and having a plurality of notches in its periphery spaced circumferentially to form filaments about 1.25 inches long. The molten material in the tank 10 was molten lead at temperature of about 690F. By adjustment of the counterweight the gang-type disc assembly was utes about 1.5 pounds of lead fibers were produced.-
During the run the level of the bath was lowered about 0.35 inches. A careful measure of the configuration of EXAMPLE2 A second experiment was run similar to the foregoing excepti tha't no water cooling was used and a float was attached to the rockable'plate. vThe float was an iron crucible of dimensions such as to displace about 0.3
cubicinch'e s of molten lead thereby increasing the total volurjne of lead displacement at a given depth of disc immersion. The float plus the dampening means thus served to minimize any variations in depth of the disc a assembly due tosmall vibrations of the rockable plate. The bath material was molten lead at temperature about 690F anda gang-type disc assembly was rotated at say 600 rpm. At the endof 2 minutesabout 2 pounds of fiber were formed. During the run thelevel of the bath was lowered by about 0.45 inches and upon measuring thefibers it was found that the geometries of fibers were substantially. identical each fiber being about 1.25 inches long about 0.06 inches wide and about 0.014 inches thick which showed that the counterweigheddisc supporting means was effective inautomatically holding the discs consistently at afuniform .depth in the melt despite a drop in m'elt level. Inasmuch asthe wheel wasnot water-cooled theternperature differential between the disc and the bath began to diminishthus precluding an extended run,
each fiber showed that each fiber was about 1.25
inches long about 0.06 inches wide and about 0.017 inches thick thus indicating that the counterbalance means had automatically lowered that gang-type disc assembly continuously and substantially uniformly concomitantly with the decrease in level of the bath.
While this invention has been described and illustrated by the eitamples shown it is not intended to be strictly limited thereto and other variations and modifications may be employed within the scope of the following claims.
1. In a process for producing filaments of substantially uniform configuration from a bath of molten material solid at ambient temperature wherein the periphery of a rotating disc is immersed in said molten bath and a temperature gradient is maintained between the periphery of the disc and the molten bath such that material is solidified on the peripheral portion of said disc immersed in said bath to form a filament thereon substantially equal in length to the immersed peripheral portion of said disc, which filament is thereafter removed therefrom the improvement comprising: forming filaments of consistently uniform configuration by immersing said disc in said molten bath to a predetermined depth, rotating said disc in said bath to continuously form and remove filaments therefrom and automatically maintaining the depth of immersion of said disc in said bath substantially constant, continuously, concomitantly with a change in the level of the bath by adjusting the effective density of said rotating disc such that said disc is suspended in said bath at predetermined depth by the buoyancy thereof.
2. In a process for the production of solid filaments of uniform configuration from a bath of molten material according to claim 1 wherein the effective density of said disc is adjusted by counterbalancing the weight of said disc when immersed in said bath at said predetermined depth.
3. In a process for the production of solid filaments of uniform configuration from a bath of molten material according to claim 1 wherein any untoward vibration of said disc in said melt is dampened.
4. Apparatus for the production of filaments of uniform configuration from a bath of molten material solid at ambient temperatures comprising: a containermeans for holding said molten material, a filament disc,
means arranged to support said disc above said bath with a portion of the periphery of said disc immersed in said bath, means arranged to maintain a temperature gradient between the periphery of said disc and said bath whereby said molten material is formed as a filament on the peripheral portion of said disc immersed in said bath, and means mounted on said disc supporting means arranged to rotate said disc thereby to continuously form filaments thereon from the molten material in said bath, said disc supporting means comprising a rockable member arranged to rock in a plain substantially perpendicular to the plane of said bath of molten material thereby to automatically maintain said disc at a predetermined depth in said bath consistently and concomitantly with the lowering of the level of the bath.
5. Apparatus for the production of filaments of substantially uniform configuration from a bath of molten material according to claim 4 wherein said rockable member is provided with counterbalance means arranged to adjust the effective density of said disc such that said disc is suspended in said bath at said predetermined level by the buoyancy thereof.
6. Apparatus for the production of filaments of substantially uniform configuration from a bath of molten material according to claim 5 wherein said rockable member is provided with dampening means arranged to minimize vibrations of the rockable member due to rotation of the disc.
7. Apparatus for the production of filaments of substantially uniform configuration from a bath of molten material according to claim 5 wherein said counterbalance means comprises an arm arranged to extend from the side of said rockable member opposite said disc, said arm having an adjustable counterweight at its rear extremity.
8. Apparatus for the production of filaments of substantially uniform configuration from a bath of molten material according to claim 7 wherein said counterbalance means comprises, in combination, an adjustable counterweight and a float said float secured to the side of said rockable member adjacent said disc and arranged to engage in said bath.
9. Apparatus for the production of filaments of substantially uniform configuration from a bath of molten material according to claim 8 wherein said float comprises a substantially cup-shaped member.
10. Apparatus for the production of filaments of uniform configuration from a bath of molten material according to claim 4 wherein said disc is substantially solid and said temperature gradient means comprises a chamber constructed and arranged to enclose substantially all but a peripheral portion of said disc, and a tubular, disc-supporting and rotating drive shaft arranged to circulate a coolant through said chamber.