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Publication numberUS822424 A
Publication typeGrant
Publication dateJun 5, 1906
Filing dateJun 9, 1905
Priority dateJun 9, 1905
Publication numberUS 822424 A, US 822424A, US-A-822424, US822424 A, US822424A
InventorsJames Francis Bottomley, Arthur Paget
Original AssigneeJames Francis Bottomley, Arthur Paget
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Process for fusing silica and for shaping the mass while plastic.
US 822424 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)









I E- EIII [/Wf/VTORS w/ M555 is im Tl/aw No. 822,424. PATENTBD JUNE 5, 1906.




F296. Fig.9.



Specification of Letters Patent.

Latented June 5, 19060 Applicatien filed June 9,1905, Serial No. 264,429.

To all whom it; mag concern.-

Be it known that we, J AMES FRANCIS Bor- TOMLEY, residing at Wellsend on Tyne, in

the county of N orthurnberland, and ARTHUR PAGET, residing at North Gray, in the county of Kent, England, subjects of His Majesty the King-of Great Britain, have invented a o'ertain new and useful Improved Process for Fusing Silica and for Shaping the Mass While Plastic, of which the following is a specification.

This invention relates to im rovements in and connected with a the wor ing of fused silica by drawing, blowing, or pressing a plastic cylinder of fused silica formed by fusion of sand or other suitable form of silica round a central core heated by the passage of .an electric current. I

To form the cylinder of plastic silica, we make use of a furnace so constructed as to allow of a separation of the electrodes from theheating-core after the completion of the fusion, so that the plastic silica may be removed and the heating-core withdrawn from the cylinder either before or after its removal from the furnace. The heating-core is preferably formed of carbon or graphite and may be either solid orhollow and of any desired cross-section, according to the size and nature of the product required.

n order to allow of the ready Withdrawal of he heating-core in the case of a carbon or graphite .core, the heating is continued sufliciently to allow of an initial" separation between the core and the inner surface of the plastic cylinder, which takes place on account of the formation of a small quantity of gas on the surface of the core.

7 In case the product is to-take the formation of a true cylinder special precautions are necessary in order to avoid the tendency to the formation of a D-section. This difficulty may be met. by inclosing the, material to be heated in such a way as to give uniform support to the plastic cylmder by preventing any displacementof the material round the core. The amount of current and length of heating ma also be regulated so as to prevent the cy inder from becoming too plastic, or the furnace may be rotated on a horizontal axis during fusion.

In the alternative the heating-core may be placed vertically and the furnace may be mountedso'as to be reversible. The cylinder material.

and, in consequence, the products formed therefrom are usuall rough on the-exterior, owing to the .im er ect fusion of the outer layer of silica. n order to produce an externally-glazed roduct, means maybe provided'either for imiting the amount of material surrounding the core,so that the whole ofit is fused, or the rough cylinder maybe subsequently treated in a separate furnace, as described hereinafter. In order to limit the amount of material around the heated core, we may rovide a 'jacket of carbon orother sufiicient y refractory materialas, for example, metals of the platinum groulp this jacket being further protected on t e outsideagainst 'heatlos'ses y additional sand or other heat-insulating The jacket may be made-in two parts, so as-to be more easily removable.

Where a cylindrical product is required and a acket is employed, the vertical form of furnace is referable, as it facilitates the feedcompensate for the shrinkage in volume during fusion. When the fusion is complete, the plastic cylinder is ready for removal and subsequent treatment. For this purpose the electrodes at either end of the heating-core are drawn apart, so'as to free the core from the furnace, and one or both ends of the cylinder are clasped by tongs, so that the cylinder may be drawn out and released (if desired) from the jacket or freed from the surround ing sand, the heating-core *bein withdrawn either beforeor after the rel-nova of the plastic c linder from the furnace. I

T 1e secondfurnace may consist, for exam ple, of a tube of carbon or other'suitable resistance material fixed between two electrodes and heated by the passage of an 8186-, tric current. The tube is covered with a suitable insulating material "to prevent-heat losses. For some purposes this may conveniently be of sand, which owin to the fact that it fuses round the tube an forms a gastight covering for it affords a ood rotection against corrosion of the outside the heating-tube through contact with the air. Nitrogen or other inert gas may be ledinto the interior of the furnaces for the same purpose.

The second furnace may be either vertical or horizontaland open at one or .both ends, according to the purpose for which it is required, the vertical arrangement being prefing in oft e sand. or other form of silica to reg der durin seas-ac erable where a cylindrical product is required, so as to take advantage of gravity. The rotation of the cylinder of plastic material may be em loyed to insure uniformity of heatin and a so to help in producing a cylindrica product. The manipulation of the plastic cylinder varies with the product required; but in every case in which expansion ,ofthe plastic mass is required it is necessary to apply sufficient initial force toovercome the external resistance due to external chilling. Where the initial resistance has been overcome, the mass becomes more plastic, so as to be easily expanded.

First. To draw thecylinder, (without blowing,) the cylinder is clasped at both ends by' tongs and drawn out. Rotation ofthe, cylindrawing may be em l0 ed to maintaillt e cylindrical form and, if esired,

the external jacket, if any, neednotbe removed prior to the drawing operation.

Second. For blowing the cylinder a nozzle constructed of a material capable of withstanding the-high temperature or cooled by some device is inserted 1n one end of the plastic cylinder after withdrawing the heated core and the plastic mass pressed round this nozzle by some suitable means, so as to make a gas-tight joint at this point e. g., the pressing may be doneby means of tongs which may be conveniently in one piece with the nozzleand so cons'tructedthat by closing the jaws a uniform pressure is exerted on the plastic cylinder round the nozzle. The opposite open end of the cylinder is simultaneously closed by pressure, either by suitablyconstructed ton s which may, ifdesired, be made to shear off the irregular end produced or by the-end ressure of a suitably-formed die, or both. ihe cylinderis' then removed from the melting-furnace and wherenecessary freed from the surrounding sand and where desirable glazed in, the tubular or second furnace before mentioned. Compressed air, or other gas may be admitted into the.

plastic mass, which may then be blown out eitherfreely or intoa surroundin mold. If desired, the plastic cylinder maybe simulta neously drawn while gas-pressure. is admitted tothe interior of the plastic mass, so as to produce tubin oflarger internal diameter or to insure its cy indrical. form.

hird; The plastic cylindsrma further be compressed between suitable rol em or. dies,

so ais,entirely to Weld up the interior cavity and produce a homogeneous mass of any desired form.

Referrin now to the'drawings, which illustrate an e ective construction of apparatus and which formthe subject-matter of a di-' visional application, Serial No. 303,551, Figures 1 .andfiZ are longitudinalelevation and plan, respectively, of afurnace in part section, exemplifying a ,method of forming the cylinder of plastic silica and means for separating theelectrodes and the heating-core from the product after completion of t e fusion. Figs. 3 and d are longitudinalelevation and plan, respectively, of a furnace in part section capable of being rotated, with means for separating the electrodes from the fused material when required. Figs. .5 and'6 are longitudinal elevation and plan, respectively, of a furnace in part section capable of being rotated on a horizontal transverse axis into a vertical or horizontal position or of completely reversing, with means for separatin the electrodes from the fused material and a so exemplifying the method of limiting the amount of materialby surrounding it with a jacketto produce fusion throughout,

Fig. 7 is a longitudinal elevation showing the same furnace rotated into a vertical osition. Figs. 8 and 9 exemplify the metho of manipulating .a cylinder of plastic silica, so as to shape it by blowing" in a mold. Fig. '10

shows the molded article after it has been finished off.

in Figs. 1 and 2. the heating-core 0i consists of a rod of graphite or hard carbon which fits between the terminals or electrodes 1), of graphite or carbon. In order to insure the eated core bein removed-at oneend along with the electro e, the rod may be screwed into the electrode at that end and mortised into the other. The electrodes are held in metal holders 0, supported on metal stands, to which the current may be led loyfiexible leads. (Not shown. The stands are made to slidein insulatedtransverse uides 01, while the transverse guides themselves can slide along longitudinal guides e. A- trough f serves as 2, containing vessel for the material to be fused and may be ofany convenient material. The ends 9 of the trough may be made removable, so as to facilitate the manipulation of the plastic cylinder when required.

I The followin is an example of a method of operation: graphite rod twenty-four inches long and one inch in diameter is fixed between tne electrodes in the manner describedand covered with glass-makers sand. About one thousand amperes at fifteen volts are passed through the rod for half an hour, when a cylinder of fused silica forms round the core. The fusion being effected, the current is cut off andthe electrodes. drawn back along the longitudinal guides,- the graphite core coming out along with the electrode into which it had been screwed. When the electrodes and core are conveniently clear of the furnace, they are pushed along the transverse guides, and the plastic cylinder is ready for subsequent manipulation. The above figures for current, voltage, and length of heating can only be taken as a rough approxi-- Ill chamber f itself rotates in also mg-c'ore, it is necessary, the heating sufiicfently long to effect the initial separation between the heating-core and electrodes bin the manner described above.

h represents metal sleeves through which the electrodes pass. The sleeves are made in two parts with insulating material i between. The flanges on the sleeves form the ends of the chamber f, in which the fusionis carried out, and are held in position by the wed es 7: represents metal disks, which dip into t e mercuryg-troughs l, to which the current is led by means of flexible leads, (not shown,) and convey the current to the electrodes. m repressents the bearings on which the furnace rotates. By means of the longitudinal and transverse guides e the electrodes can be drawn clear of the furnaces when required. The the bearings m, which support it when the electrodes are drawn apart. It is fitted with a cover 0, which opens on hinges.

The method of operation is similar to that describedabove. For example, current is passedthrough a heating-core fixed between the electrodes until a cylinder of plastic silica of the required dimensions has been formed. During the heating th'efurnace is kept in slow rotation or rotated from time to time, as desired. The fusion being complete, the current is cut off and the wed es 1' removed, so that the electrodes are ee. The electrodes and heating-core are then separated from the fused material in the manner described above, and after opening up the chamber the plastic silica is ready for further manipulation.

In Fig. 5 f is a metal chamber made in two parts. The electrodes 6 pass through metal sleeves h, which are made in two arts with i sulating material 11 between. T e flan cs 11 the sleeves form the ends of the cham er and are held in position by the clips 1). 9 represents trunnions on which the furnace rotates. The sleeves have extension-pieces 1', which are arranged so thatthey can engage with the blocks 8, which run on the transverse guides (1. Longitudinal guides e are rovided as before. Current is led to the s feeves by means of flexible leads, (not shown;) but if the furnace has to rotate completely brushes or some similar device for conveyin the current to the sleeve may be employe however, to carry on The method of operation is similar to that described above. The heating is carried out with the furnace in the vertical position, and when complete the furnace is rotated to the horizontal and the extension on the sleeves it made to en age with the blocks. .The'chps holding t e sleeve-flanges at the end of the filrnace-casing, are then opened and the electrodes drawn apart If a material glazed throughout is required,

a jacket of carbon or other sufliciently refractory material may be made to surround the core, so as to limit the amount of material to be fused. The jacket'may be used with any of the types of furnace and is shown at t in Figs. 5 and 6. The ends of the heat1ng core may be left un'acketed, if desired, as shown on the right 0 Figs. 5 and 6, in order to facilitate the manipulation of the plastic cylinder, or in order to prevent the material within the jacket from being. blown out at the unjacketed ends the ends of the core may be surrounded with a acket of slightly larger diameter, so that fusion of the outer layer of the contained material does not take place during the main fusion, so that the end jackets are easilyremoveil. Une of the extension-jackets may be made funnel-shaped to enab e fresh material to be fed in. The jacket may be made in two halves to fac1l1- tate its removal afterward, in which case the material surrounding the jacket on the outside, which servesas heat-insulator, may be of some refractory -material which does not melt at the required temperatureas, forexample, magnesia, carborundum, or the like. In using a jacket it may be advantageous to use a hollow heating-core and electrode and to provide means for regulating the amount of gas given oif during the. heating. As an example of the method of limiting the amount of material around the heating-core a graphite rod twenty-four inches long and one inch diameter is trodes with a cylinder of'agglomerated carbon three inches internal diameter supported centrally. round'itand the whole of the furnace filled with pure glass-makers sand. One thousand amperes' at fifteen volts are passed through until the sand on the exterior of the jacket begins to agglomierate, which occuples about three-quarters of an hour. The furnace is then rotated into a horizontal position and connection made with the arrangement for separating the electrodes. The body of the furnace is opened, and after cutting off the current the electrodes are separated and the plastic cylinder contained in the acket is ready for subsequent manipulation. I

According to the alternative method of producing a material glazed throughout the plastic cylinder after removal from the furnace is immediately transferred to an electrica'lly-heated chamberas, for example,

ed. in position between elec- A The cylinder is lifted into the moldas, for

.itis subjectedto radiant heat suficient to melt the exterior layer of agglomerated ma- .suitable pair of tongs. removed from the furnace and drawn out,

done, the mass becomes much more plastic sandto pass through.

may be shaped by pressing it between dies of the tubular furnace before mentionedwhere terial.. As soon as the glazing has been effected the plastic cylinder is ready for subsequent manipulation.

In order to produce tubing, the nozzle 1) of the tongs i1 ..(shown in Fig. 9) may be inserted in one end of the plastic cylinder {1 and the plastic material pressed round it by means of thejaws. The other end ofthe cylinder is simultaneously closed 'by the pressure of a The cylindervis then compressed air being admitted through the pipe w, so as to produce cylindrical tubing of any desired diameter. When the cylinder is removed from the furnace, the outside is hard, and before it can be drawn'consider-. able force has to be em loyed to overcome the external chilling. When this has'been and can be easily drawn out. For example, in drawing tubing from a plastic cylinder unglazed on the outside to overcome the initial resistance a pull of fifty-five pounds was required, which fell as soon as the material began to draw to twentyfive pounds.

If the plastic cylinder has to be molded, the manipulation is similar; but the nozzle of the tongsis inserted in one end of the cylinder and the plastic material pressed round it as before. The other end may be closed by means of asuitable pair of tongs which ma simultaneousl shear off the irregular en exam le, that shown at x in Fig. 9-which may e ofany'suitable material capable of withstanding 'thetemperature of the exterior of the fusion. Compressed air is then admitted, so as to force the plastic material y to take the shape of the mold. i I

When the material to be molded is rough on the outside, the mold may be pierced with a number of perforations -to allow the loose Instead of the above the plastic cylinder an% desired shape. y this invention, therefore, We provide a 7 means whereby fused silica, which on account of its high melting-point cannot be worked by the usual processes common to glassmaking, (namely, of melting in a receptacle and ]gathering portions of fused material on a lowing-tube,) is brought-to such a condition that it can be worked into various articles l eeaeea with comparative ease by the methods indicated. Further, the processisone of high thermalefiiciency, because, in the first place, practically plied directly to the center of the 'matcria to be fused, so that (except in the subsidiary process of glazing) practically no heat is lost in heating the containing vessel. i

What is claimed isl I j 1. In the working of s1lica,'fusi-ng-same*by means of an internal-resistance core, then initially separating the fused material from the core byalayer'of gas and then removing the corefrom the plastic massfor the purposes described.

p 2. In the working of silica, fusing same by means of an internal-resistance core,-heatin thecore sufficiently to effect the formation 0 a small quantity of gas on the surface thereof,

separating the fused material from the core by means of such gas and then withdrawing only the exact amount of mate "rial required need be fused, and, secondly, because the heat is a the core while the mass is still plastic, substantially as and for the 'urposes described. 3. In the working of si ica, fusing same by means of an internal-resistance core, separating the core from one of the electrodes, withdrawing the core from the lastic mass and shaping such mass while stil plastic,substantially as and for the purposes described.

4. In the working of sllica, fusing same by means of an internal-resistance core, separating the core from one of the electrodes, withdrawing the core from the plastic mass, removing said plastic mass from the furnace,

further heating same within an electricallyheated chamber so as to'glaze theexterior of the mass and shaping said mass during plasticity, substantially as and for the purposes. described:

5. In the working of silica, fusing same by means of an internalresistance core, withdrawing the core from the plastlc mass, closing one end of the mass, pressing the other end around a nozzle and then introducin air under pressure therethrough, substantial y as and for the purposes described.

In testimony whereof we have hereunto set our hands in the presence of two subscribing witnesses.


Witnesses: v



Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4772302 *Feb 9, 1987Sep 20, 1988Northern Telecom LimitedOptical waveguide manufacture
US4941905 *Mar 4, 1988Jul 17, 1990American Telephone And Telegraph Company, At&T Technologies, Inc.Methods of soot overcladding an optical preform
Cooperative ClassificationC03B19/1423