US836558A - Apparatus for working fused silica or the like. - Google Patents

Description

No. 836,558. v PATENTED NOV. 20, 1906.. J. F. BOTTOMLEY & A. PAGET.

APPARATUS FOR WORKING FUSED SILICA OR THE LIKE.

APPLICATION FILED FEB-28.1906.

2 SHEETS-SHBET 1.

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6 we a W/ TN 5555. I wvmvrms No. 836,558. PATENTED NOV. 20, 1906.

J. F. BOTTOMLEY & A. PAGET.

APPARATUS FOR WORKING PUSED SILICA OR THE LIKE. APPLIGATION FILED FEB. 28. 1906.

2 SHEETSSHEET 2- p RQTJZ p dz: Q 5 2 6 f ,5 5 6 A /e i e figi a rain JAMES FRANCIS BOTTOMLEY, or WALLSEND,- AND ARTHUR mom,

or NORTH GRAY, ENGLAND. I

APPARATUS FUR WORKHING FUSED SlLlGA OR THE LIKE.

T0 at whom it may concern: Be it known that we, JAMES FRANCIS Bor- TOMLEY, a resident of Wallsend-on-Tyne, in

the county of Northumberland, and ARTHUR. PAGET, a resident of North Gray, in the county of Kent, England, subjects of His Majesty the King of Great Britain, have-invented a tic 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. Where silica and fused silica are hereinafter referred to, the words are intended to cover not only pure silica, but combinations of same or of other materials having melting-points above -1500 centi- -grade, at which theybecome plasticand vitreous.

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 and the heating-core withdrawn from the cylinder either before or after its removal from the furnace- The heating-core is preferably formed of carbon or graphite and may be either solid or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

In order to allow of theready Withdrawal .of the heating-core in the case of a carbon or graphite core, the heating'is continued sufficiently 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 quantify of gas on the surface of the core.

In case the product is to take the form of a true cylinder special precautions are necessary in. order to avoid the tendency to the formation of a D-section. may be met by inclosing the material to be heated in such a way as to give uniform support to the plastic cylinder by preventing Specification of Letters Patent. Application filed February 28. 1906. Serial No. 303,551.

This difliculty Patented. Nov. 20, 1906.

any displacement of the material round the core. The amount of current and length of heating may also be regulated so as to prevent the cylinder 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 mounted so as to be reversible. The cylinder, and in consequence the products formed therefrom by drawing or otherwise manipulating during plasticity, are usually rough on the exterior, owing to the imperfect fusion of the outer layer of silica. In order to produce an externallyglazed product, means may be provided either for limiting the amount of material.

surrounding the'core, so that the whole of it is fused, orthe rough cylinder may be subsequently treated in a separate furnace, as described hereinafter.

In order to limit the amount of material around the heated core, we may provide a jacket of carbon or other sufficiently-refractory materialas, for example, metals of the platinum grou -this jacket being further rotected on t e outside against heatlosses y additional sand or other heat-insulating material. The jacket ma be made in two parts, so as to be more easi y removable.

Where a cylindrical product is required and a jacket is employed, the vertical form of furnace is preferable, asit facilitates the feeding in of the sand or other form of silica to compensate for the shrinkage in volume during fusion. When the fusion is com lete, the plastic cylinder is ready for remova and subsequent treatment. For this urpose the terminals at either end of the eatingcore are drawn apart, so as to free the core from the furnace, and one or both ends of the sistance material fixed between two terminals and heated by the passage ,of an electric current. The tube is covered With a suitable insulating material to prevent heat losses. For some purposes this may conveniently be of sand, which, owing to the fact that it fuses external resistance due to external chilling.

"cording to the purpose for which it is required,

the vertical arrangement being preferable where a cylindrical product is required, so as to take advanta e of gravity. The rotation of the cylinder of plastic material may be employed to insure uniformity of heating and also to help in producing a cylindrical prodnet. The manipulation of the plastic cylin der varies with the product required but in every case in which expansion of the plastic mass is required it is necessary to apply sufficient initial force to overcome the Where the initial resistance has been overcome, the mass becomes more plastic, so as to be easily expanded.

First. To draw the cylinder, (without blowing,) the cylinder is clasped at both ends by tongs and drawn out. Rotation of the cylmder durin drawing may be employed to maintaint e-cylindrical form, and, if desired, the external jacket, if any, need not be re moved 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 in 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 pointe. 9.. the pressing may be done by means of tongs which may be conveniently 1n one plece with the nozzle-and so constructed that 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 tongs, which may, if desired, be made to-shear off the irregular end roduced,

' or by the end pressure of a suitab y-formed die, or both. The cylinder is then removed from the melting-furnace and, where necessary, freed from the surrounding sand, and,

where desirable, glazed in' the tubular or second furnace before mentioned. Comressed air or other gas may be admitted into the plastic mass. whichmay' then be blown out either freely or into a surrounding mold. If desired, the plastic cylinder may be simultaneously drawn while gas-pressure is-admitted to the interior of the plastic mass,

so as to produce tubing of larger internal di a-meter or to insure its cylindrical form.

Third. The plastic cylinder ma further be compressed between suitable rol ers or dies,

so as entirely to weld up the interior cavity and produce a homogeneous mass of any desired form.

Referring now to the drawings, Figures 1' and 2 are ongitudinal elevation and plan, respectively, of a furnace in part section adapted for the production of a cylinder of plastic silica and means for separating the terminals and the heating-core fronr the product after completion of the fusion. Figs. 3 and 4 are longitudinal elevation and plan, respectively, of a furnace in part section capable of being rotated with means for sep-, arating the terminals from the fused material when required. Figs. 5 and 6 are longitucfinal 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 com pletely reversing, with means for separating the terminals from the fused material and also exemplifying themethod of limiting the amount of material by surrounding it with a jacket to produce fusion throughout. Fig. 7 is a longitudinal elevation showing the same furnace rotated into a vertical position.

In Figs. 1 and 2 the heating-core a consists of a rod of graphite or hard carbon which fits between the terminals 1) of graphite or carbon. In order to insure the heated core being removed at one end along with the terminal, the rod may be more securely at tached to one terminal than to the other. The terminals are held in metal holders 0, supported on metal stands, to which the current may be led by flexible leads. (Not shown.) The stands are made to slide in insulated transverse guides 11, while the transverse guides themselves can slide along longitudinal guides e. A trough f serves as a containing vessel for the material to be fused and may be of any convenient material. The ends 9 of the troughmay be made removable, so as to facilitate the manipulation of the plastic cylinder when required.

The followin is an example of a method of operation: graphite rod twenty-four inches long and one inch diameter is fixed between the terminals in the manner described and covered with glassmakers 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 and the terminals drawn back along the longitudinal guides, the graphite core coming out along with the terminal. When the terminals and core are conveniently clear of the furnace, they are pushed along the transverse guides d 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 approximation and would vary according to the material of which the heatingcore is composed. In order to effect the withdrawal of the heating-core, it is necessary, however, to carry ontheheating sufficiently long to effect the initial separation between the heating-core and fused material by internal generation of gasor to bring about this spear'ation by the introduction of as or air between the heating-core and the used material by somedevice-such as, for example, by usin a hollow and perforated core and passing t e requiredquantity of gas through it into the middle ofthe fused mass,

as described in specification No. 812,399 of February 13, 1906. In Fig. 3 the heating-core a, embedded in the material to be fused, is fixed between the terminals 1) in the manner described above. h represents metal sleeves through which the electrodes ass. The sleeves are made in two parts, wit insulating material i between. The flanges on the sleeves form the ends of the chamber f, in which the fusion is carried out and are held in position by the wedges k represents metal disks which dip 'into the mercury-troughs Z, to which the current is led by means of flexible leads (not shown) and convey the current to the terminals. m represents the bearings on which .the furnace rotates. By means of the longitudinal and transverse guides e the terminals can be drawn clear of the furnaces when required. The chamber f itself rotates in the bearings m, which support it when the terminals are drawn apart. It is fitted with a cover 0, which opens on hinges.

The method of operation is similar to that described above. For example, ,current is passed through a heating-core fixed between the terminals until a cylinder of plastic silica" of the re uired dimensions has been formed. During t e heating the furnace is kept in slow rotation or rotated from time to time, as desired. The fusion bein complete, the current is cut off and the we ges removed, so that the terminals are free. The terminals and heating-core are then separated from the fused material in the manner described above, and after 0 ening up the chamber the plastic silica is ready for further manipulation.

In Fig. 5, f is a metalchamber made in two parts. The terminals 1) pass through metal sleeves h, which are madein two parts with insulating material '5 between. The flanges on the sleeves form the ends'of the chamber and are held in position by the clips'p. g

Y represents trunnlons on which the furnace I rotates. The sleeves have extension-pieces 1", which are arranged so that they can engage with the blocks .9, which run on the transverse guides 11. Longitudinal guides e are also proprovided, as before.-. Current is led to the sleeves by means of flexible leads, (not shown;) but if the furnace has to rotate completely brushes or some. similar device for conveying the current to the sleeve may be made to engage with the blocks.

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 h The clips 19, holding the sleeve-flanges at the end of the furnace-casing, are then opened and the terminals drawn apart.

If a material glazed throughout is required, a jacket of carbon or other sufficiently-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 attin Figs. 5 and 6. may be left unjacketed, if desired, as shown' on the right of Fig. 5, 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 jacket to (see Fig. 6) of slightly larger diameter, so that fusion of the outer layer of the contained material does not take lace during the main fusion, so that the en jackets are easily removed. One of the extension-jackets may be made funnel-shaped to enablefresh material to be fed in.- The jacket may be made in two halves to facilitate its removal afterward, in which case the material surrounding the jacket on the outside, which The ends of the heating-core serves as heat-insulator, may be of some refractory material which does not melt at the required temperature-as, for example, magnesia, carborundum, or the like. In using a jacket it may be advantageous to use a holow heating-core and terminal and to provide means for regulating the amount of gas given off during the heating. As an example of the method of limiting the 'amount of material around the heatingcore a graphite rod twenty-fourinches long and one inch diameter is fixed in position between terminals, with a cylinder of agglomerated carbon three inches internal diameter supported centrally round it, and .the whole-of the furnace filled with pure glassmakers sand. One thousand am eres at fifteen volts are passed through unti the sand on the exterior of the jacket begins to agglomerate, which occu ies about three-quarters of an hour. The rnace is then rotated into a horizontal position and connection made with the arrangement for separating the terminals. -The body of the furnace is opened, and after cutting off the current the terminals are separated, and

the 'lastic cylinder contained in the jacket is rea y for subsequent manipulation. 4

According to the alternative method of producing'a material glazed throughout the plastic'cylinder after removal from the furnace is immediately transferred to an electricallyheated chamber-as, for example,-the tubular furnace -before mentioned-wherefit is subjected to radiant heat suflicient to melt the exterior layer of agglomerated material. As soon as the glazing has been effected the plastic cylinder is ready for subsequent manipulation.

By this invention, therefore, We provide a means whereby fused silica, which on account of its high melting-point cannot be Worked by the usual processes common to glassmakingnamely, of melting in a receptacle and gathering portions of fused material on a blowing-tube-is brought to such a condition that it can be Worked into various articles with comparative ease and while still plastic. Further, the process is one of high thermal efficiency, because, in the first place, practically only the exact amount of material required need be fused and, secondly, because the heat is applied directly to the center of the material to be fused, so that (except in the subsidiary process of glazing) practically no heat is lost in heating the containing vessel.

What is claimed is- 1. In apparatus for Working fused silica or the like, a furnace, terminals therein, and a resistance-core so connected thereto as to permit of the removal of the core from the fused mass, so that the fused mass can be removed from the furnace during plasticity, substantially as and for the purposes set forth.

2. In apparatus for Working fused silica or the like, a furnace, a. jacket therein for limiting the amount of material to be fused, terminals in the furnace and a resistance-core so connected thereto as to permit of the removal of the core from the fused mass Within the jacket, and ofthe fused mass from the furnace during plasticity, substantially as described.

3. In apparatus for Working fused silica or the like, a furnace, terminals therein, a resista-ncecore"so connected thereto as to permit of the removal of the core from the fused mass, so that the fused mass can be removed from the furnace during plasticity, and

means for rotating the furnace, substantially as described In testimony whereof we have hereunto set our hands in the presence of two subscribing Witnesses.

JAMES FRANCIS BOTTOMLEY. ARTHUR IAGET.

Witnessesito the signature of James Francis Bottomley:

R. CLARK, WM. KENNEDY.

Witnesses to the signature of Arthur Paget:

H. D. JAMESON, A. N UTTING.

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