US2471531A

US2471531A - Electrode

Info

Publication number: US2471531A
Application number: US706616A
Authority: US
Inventors: Glenn H Mcintyre; Robert E Skinner
Original assignee: Ferro Enamel Corp
Current assignee: Ferro Corp
Priority date: 1946-10-30
Filing date: 1946-10-30
Publication date: 1949-05-31
Anticipated expiration: 1966-05-31

Description

May 31, 1949. e. H. MOINTYRE EI'AL ELECTRODE Filed Oct. 30, 1946 INVENTOR5 GLENNHMINTYRE AND BY WO-BERT E 5K/NN&72

Patented May 31, 1949 ELECTRODE Glenn H. McIntyre, Cleveland Heights, and Robert E. Skinner, Lakewood, Ohio, Ferro Enamel Corporation,

corporation of Ohio assignors to Cleveland, Ohio, a,

Application October so, 1946, Serial No. 706,618

The present invention relates generally to e1ectrodes of the type adapted to be buried in a furnace charge to be fused by passage of electric current therethrough, the electrodes being good conductors of electricity and the charge being a poor conductor whereby the resistance to flow of current through the latter effects heating and melting thereof, and more especially to electrodes adapted to so fuse materials such as glass, porcelain enamel, and the like.

Electric furnaces using graphite electrodes such as are herein disclosed are, of course, in general use in many diversified industries encompassing both the metal and non-metal fields. However, the fusing of porcelain enamel and like materials has heretofore been largely accomplished by heat radiation from combustion of hydrocarbon gases especially in localities where such gases are readily available and inexpensive. Nevertheless, even in localities where electric power is plentiful, the peculiar properties of porcelain enamel and like materials and their eiTect on known electrode materials has made it impracticable and undesirable to utilize electric current for heating and fusing such materials.

Typical ingredients of porcelain enamel, for example, are feldspar, borax, silica, cryolite, soda ash, fluorspar, sodium nitrate, antimony oxide and zinc oxide. It is thus apparent that when a charge comprising such ingredients is fused, both the fused mass andthe fumes therefrom will be highly corrosive to most metals. Furthermore, such fused mass is so highly erosive when flowed that it quickly erodes away the furnace linings and openings and the electrodes therein. The electrodes immersed in such furnace charge must, therefore, in addition to being good conductors of electricity, be of such form and material that corrosion and erosion either within the melt or in the atmosphere above is minimized or avoided altogether and also be of such material or so treated as not to contaminate the charge and thus discolor it and/or change its physical properties. v

Accordingly, it is one principal object of this invention to provide a new and improved electrode which overcomes the deficiencies of those presently available and incorporates therein features which render the same efiectively usable for fusing materials of the character indicated.

. 1 Claim. (Cl. 13-18) Other objects and advantages of the invention will become apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claim, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In the drawing:

Fig. 1 is a fragmentary central vertical cross section view of one form of electrode; and

Figs, 2 and 3 are views similar to that of Fig. 1 but showing only portions of other forms of the invention.

The electrode illustrated in Fig. 1 comprises a graphite body I formed with an internally threaded recess into which is threaded the lower end of a tubular conductor 2 of copper or brass or like high electricity conducting material. The lower end of the conductor 2 is closed as by a. copper or brass plug 3 threaded thereinto and good electrical-contact between the body and the conductor is established by engagement of the plug with the body and the use of carbon paste at least in the threaded joint between the body and the conductor. The conductor 2 near its upper end has secured thereabout a laterally projecting copper strap 4 which is adapted to be connected to a suitable source of electric current. Also, near the upper end of conductor 2 is a laterally projecting pipe 5 having communication with the interior of the conductor.

Within conductor 2 and spaced therefrom is an inner hollow member 6 which is preferably of electrical conducting material and the lower end of which is heated in a recess in plug 3, so as to make good electrical contact therewith and thus with the conductor 2 and body I. The inner conductor 6 is retained in place relative to conductor 2 by means of the nut l secured thereto and having threaded engagement with the threads formed at the upper end of conductor 2, such threaded joint establishing further electrical contact between the

conductors

2 and 6. Nut 1 has the further function of closing the annular space defined between

conductors

2 and 6. A plurality of openings 8 through the wall the same as that of Fig. 1 exceptthat However, as to attack of the exposed 'conductor 2 by the fumes and vapors from the of conductor 6 adjacent its lower end establishes fluid communication between the interior thereof and the annular space between the conductors whereby the upper projecting end of conductor t can be connected to a coolant supply source such as cold water and the pipe 5 connected to a suitable discharge line leading to a sewer or the like. Thus, cold water will flow downwardly through conductor 8, laterally through openings 8, and thence upwardly through the space between

conductors

2 and 6 and finally out through pipe 5. In this way the walls of the conductors 2 and B will be maintained at a relatively low temperature for the hereinafter to be disclosed purposes.

The portion of conductor 2 between the strap 4 and the upper surface of body I is preferably coated with porcelain enamel as indicated by the numeral 9 in order to protect the exposed portion, that is the portion not immersed in the furnace charge, from attack by the fumes and vapors rising from the fused material. As will be seen later, such coating may in some cases be omitted.

The electrode illustrated in Fig. 2 is the same as that of Fig. 1 except that a glass tube ID has been substituted for the fired porcelain enamel coating 9.

The electrode illustrated in Fig. 3 is essentially conductor 2 and plug 3 are of graphite and are integral with body I. With said conductor 2 made of graphite, no protective coating thereabout is required.

The furnace with which any of these electrodes are usable is usually rectangular in shape and has at least one electrode at each end thereof. The electrodes are simply buried in the charge and are usually supported so as to be vertically adjustable. In use, the present electrodes are buried so that the entire body l and a portion of conductor 2 are immersed in the furnace charge, All that remains to be done is to connect the electrodes to a coolant supply and to an electric current source and properly regulate v the flow of coolant and electric current.

As previously indicated, the charge in the case of porcelain enamel, for example, is highly corrosive and erosive when fused but is non-corrosive when solid. Assuming now that the electrode of Fig. 1, without the coating 9, is immersed into the charge, it can be seen that the fused material thereabout will be chilled and will collect on the immersed portion of conductor 2 by reason of the cooling action of the coolant flowing therethrough. Such chilled material collected at the joint between the conductor 2 and body 1 forms a protective coating to prevent any attack of the copper or brass conductor 2 by the fused material. Body I will, of course, reach a temperature substantially equaling that of the fused material but such temperature is not harmful thereto because it is entirely submerged and thereby free of oxidation. In addition, because body I is made of graphite, the fused material thereabout will not corrode or erode the same.

From the above, it can thus be seen that the charge itself is utilized in effecting complete corrosion and erosion resistance of conductor 2. portion of fused material, it is preferred that said conductor be coated with porcelain enamel, as shown in Fig. 1. The cooling of conductor 2 assures that the coating on the exposed portion thereof will remain intact. With such an arrangement, conductor 2 may be made of metal having good heat and electric conductin properties, whereby the necessary electric currents maybe passed therethrough without causing excessive heating.

The operation of the electrode disclosed in Fig. 2 I

material at the lower end of the glass tube, the

collection of chilled material at such lower end being effective to form a seal with body I and thus prevent contact of the fused material with conductor 2;

The electrode of Fig. 3 is uniquein that no protective coatin is required on conductor 2 or on body I, inasmuch as the graphite is immune to attack either by the fused material or by the fumes therefrom. The cooling of the electrode prevents oxidation of the exposed portion.

One noteworthy feature of the present electrode is that adequate current carrying capacity is provided by nesting two conductors and utilizing the spaces therein and therebetween as coolant passages.

The water hoses or the like, not shown, which are connected to the

conductors

2 and 6 must be of sufficient length to develop a high resistance in the length of the water column so that the power loss will be a minimum.

While particular reference has been made to porcelain enamel, it is to be understood that the present electrodes may be used with equal facility to fuse many other materials of like or different properties. In the present case, the fused material referred to is drawn off into water to produce a friable product known in the art as frit from which the enamel slip is made for firingonto various articles for corrosion-resisting and decorative purposes. One particular advantage in using an electric furnace for fusing the material is that the heat is uniformly distributed throughout the mass of fused material inasmuch as such heat is effected by flow of current through the entire mass.

tinctly claim as our invention:

An electrode, comprising coaxial inner and outer tubular conductors forming an annular space therebetween, an exteriorly threaded imperforate plug having threaded engagementin one end of said outer conductor and formed with a central recess bearing a close telescopic fit over and thus coaxially locating the corresponding end of said inner conductor with respect to said outer conductor, a nut surrounding said inner conductor having threaded engagement with the other end of said outer conductor, said inner conductor being formed with a lateral opening adjacent said plug affording communication between the interior of said inner conductor and the annular threaded electric conducting body threaded onto said outer conductor formed with a recess including bottom and side walls respectively in electrical contact with the outer end face of said plug arm' with the sides of said plug and outer eonductor, such recess in said body being of depth such that said body extends along said outer conductor at least to a point opposite the lateral Number opening insald inner conductor and the annular 916,548 space defined between said conductors. 961,139 GLENN H. McINTYRE. 1,223,986 ROBERT E. SKINNER. 5 1,259,842 1,912,560 REFERENCES CITED 2,370 4 7 The following references are of record in the file of this patent:

10 Number UNITED STATES PATENTS 13,241 Number Name Date 507,374 Lyte Oct. 24, 1893 896,429 Becket Aug. 18, 1908 Name Date Gorrell Mar. 30, 1909 Keller June 14, 1910 King Apr. 24, 1917 Fischer Mar. 19, 1918 Wiles June 6, 1933 Hopkins -1 Feb. 2'7, 1945 FOREIGN PATENTS Country Date Switzerland Oct. 13, 1896