US1654910A - Process for treating articles in metallic baths - Google Patents

Description

Jan. 3, 1928. 1,654,910

Filed Oct. 28. 1925 2 Sheets- Sheet 1 in ven for; ,Noel Jean B t r- Jan. 3, 1928.

N. J. BARBIER PROCESS FOR TREATING ARTICLES IN METALLIC BATHS 2 Sheets-Sheet 2' Filed 001' 28- 1925 4 I I I l I 4 l1 l I I l l I l l jryenfor' JV'oe/ ea per Patented Jan. 3, 1928.

UNITED" STATES PATENT oFrIcs.

NOEL EAN IB-ARBIEB, or sn nrInm-Lomn, amon.

PROCESS FOR TREATING. ARTICLES III METALLIC BATES.

Application filed October 28, 1925, Serial No. 5,407, and in Irance October 31, 1824.

This invention relates to processes for ap-" plying metal to articles by treatment in a metallic bath. r i

The invention consists in the application to tinning, coppering, brazing, zincing, gilding, silvering and thelike, by immersion in a bath in fusion, as well as to electro-thermic operations generally, of the combination of two methods of electric heating, one'by the 10 direct introduction into the bath of calories emanating from an electric current of low voltage by means of one or more immersed pieces serving as electrodes electrically heated up to redheat on a small length above the level of the bath, in'order to prer vent at that point the solidification of the metal around said immersed pieces and to rectify the cooling of the bath following upon the immersion of the cold electrode 2, parts; the other, by'the rapid heating of the bath by means of' an induction or resistance electric oven,-the whole "arrangement being joined together to automatically improve during the period of working the thermic constancy andi yield in the effective part of the bath. The invention" also consists ina special arrangement intended, to realize in the induction ovens Qsaid automatic improvement in the thermic constancy and yield in 3 the efiective part of the bath, and "based upon the joining, at a point placed in the centre of the magnetic core, situated in a horizontal.

plan of the branches ofmultiple fusion baths placed in a vertical "plan, in order to form; at vsuch point of junction, an openworking chamber, whichmay be made narrower to ,raise the temperature and obtain heating 'from the bottom, which may be vertically extended to reduce the efiects of brazing and pinching, with a primitive bath cast and incorporated with the mason 'w'ork.

Furthermore the invention comprises a;

special arrangement to carryoutsuch ther mic improvement in resistanceelectric ovens, namely, the use of undulated heating surfaces; and the use of superimposedeleetrode' studs or contacts along the pieces for the,

purpose-of obtaining't-he progressive tempering electricallyta and v I The invention will now be described with 0 reference to 'theaccomp'anying drawings in which Figure 1 is a sectional elevation of a vat. 'Figure'2 is a plan view of afurther vat,

' Figure 3 is a sectional elevationshowing an improved form of heating surface forthe vat;

. A fire-proof vat, Figure-.1, Sheet 1, contains tin, brazing, soldering, copper etc., heated by no vany external gas, coal, oil or other furnace and kept at the lowest temperature of fusion to reduce the" oxidation of the molten bath to a minimum. I

' In order to prevent a sudden fall-of tem-" c5 perature and any solidification of the fused metal which would be caused by the immersion in the bath of cold metallic pieces, any two electrodes 2 and 3 are immersed in the bath and conduct thereto, during the immer- '76 ,sion, a low tension electric current which compensates and prevents the loss of heat by conveying thereto calories emanating from' the electric current of low voltage graduated according to the mass of the immersed cold pieces, soas to maintain the temperature of the bath constant. v

The period of the passage of the curren and its lntensity is regulated by the operator by means of an ordinar rheostat and inter- 8b ru tor operated by han or by a pedal.

he gas, oil or' other independent furnace may also be replaced by a current of low tem sion only andof a determined intensity to i.

maintain the fusion. In such case, at the moment of-immersion, an additional inten: sity of the current will prevent the cooling of the bath and keepit at a constant temperature during the whole eriod of the immersion, Thetwo electro es 2 and 3, may also 00 be replaced by' a metallic, vat. The latter, with the bath it'contains, serves as one elec-v trode, whilst the pieces 'to be immersed, serve as the other electrode. For instance, in order-to braze a frame dlas rection union 4 for bicycles, at its two tubes 5 and 6, the wholebeing prepared with borax. inthe ordinary way, the vat and thebath i form one electrode 7 and the two tubes which tubes.

project beyond the level of the bath form the other elect-rode 8 and 8'. Y Y

This arrangement offers two advantages:

the first is to eifectthe" introduction of calories emanating from the electric current of low voltage into the bath direct by the contact of the pieces to be brazed, which are thus brought to red heat as soon as they'enter the bath, which prevents the solidification of the metal round the pieces; and the second is to permit the progressive tempering of the brazed tubes by a more or less deep 1mmersion without solidification round the trade.

. bath.

The first of said contacts 8 and 8 are fixed to the ieces at a short distance from the level 0 the bath; when they are used current of When the contacts 13 and 13, which are farthest from the bath, are employed, the current of the'weakest intensity. is supplied to the bath.

The intermediary, contacts 9 and- 9, 10-

I and 10, 11 and 11', 12 and 12, are adapt ed to supp'y the currents of progressively decreasing intensity. All these contacts which form the electrode terminal'may be mounted together or in roups on,the same clamping element to facllitate the mode of attachment.

The tubes 5 and 6 or any other pieces are also progressively ten pered'and decrease from the contact 13 and 1-3 up to the level of the bath.

In all the operations of renovation, tempering, annealing or recovering by immersion in salt baths in fusion, theapplication of heat as herein described offers all the advantages of regularity in the temperature as stated above. v In the foregoing description, it is provided that the external heating of the bath may be effected by any method of heating.

Amongst such methods of heating, it-is found that resistance or induction electric ovens are most suitable to the-variations of vantageousflimprovements both in regard to the heatin of the tinning, brazing, copper-v ing and ot er baths and to the various elec'; tr'o-the'rmic applications now in use.

The object. of these, improvements is to localize and concentrate rapidly the maximum amount of heat in theefl'ective part of the bath, where such concentration is to compensate and rectify the decrease of temperag'reatestintensity is supplied to the ture arising from the immersion of the cold pieces, scraps or other materlal under treatment, in order'to reduce the speed of cooling mg as an electrode, results in the association of two means ofelectric heating which simultaneously concur in producing in the same apparatus ,and automatically, during the period of Working or immersion, the maximum speed of heatingand the constant temperature in the effective part of the bath.

In order to carry into effect suchautomatic concentration in induction ovens, as

nowconstructed, serious'difliculties are encountered. i

This conce'tion based on the horizontal position of t e circulation fusion bath or baths, renders their workin defective, when it is desired to use more t an two of them together,- for instance, four or six, and as the points of contact form a square, af hexagon, etc., the result is that it is'impossible to concentrate. them on a single point. On the other hand, the upper branch of the magnetic core situated in this case in the vertical plane, passes exactly above the points of unction and becomes therefore a hindrance in utilizing them as a working chamber.

These disadvantages are reduced or avoidedby inverting the respective positions of both and of the core.

If around the core situated -inthe horizontal plane, several circular fusion baths are placed in the vertical plane, four for instance, around each branch of the core, the junction of thesegfo'ur baths becomes easy, owing to the parallelly tangential profile of the four surfaces in contact, which naturally become joined to ether intoa single bundle in the centre 0 the core, where the concentration of the induced current is most intense, and form at that point a common fusion or working chamber which assumes the form of a'cylinder or vertical pocket which performs the part of a crucible and the surface ofwhich is not interfered with by a bra h of the core.

In Figure 2, Sheet 2, drawn by way of guidance only, 1, lis a magnetic core, the branches of which arranged in the fire- proof mamnry work 2, 2 on a horizontal lane, are surrounded by 'four circular baths, 3, 4, 5 and 6,-arra'mged in a vertical plane. Around eachbath there is apair of bobbins ill) electro-thermic a 3 'sla is facilitated.

6n the other hand by giving to the point throttling effect" which, by

' parallel to th bath 7,2; 8, a; 9, 93 10, 10'! Each of the baths is enclosed in the masonry, and theyall (four in number or more-, as de-.

sired) terminate at the centre of the ap- 5 paratus in a working chamber 11 opened above and closed below.

Byextending said chamber vertically in a cylindrical or splay form above the upper level of the circular bath, in most cases of pplications, a high working chamber is obtained in which the well-known effect of metal brazing is all the more reduced, as said chamber is higher whereby the separation of the melted metal from its of junction of the circular baths, a-sec tion smaller than the'added sections of thewhole of the bath, there is produced, at that spot, a

increasing the resistance of the circuit at that point, re sults in an increase of temperature. Thus all the advantages of intensive heating, at

the bottom and in the centre of the ap-' i paratus, .are secured.

The eflect of pinching which has a tendency to occur at the overheated and constricted point, is successfully prevented in this vertical arrangement of the bath by the pressure of'the column of metal contained in the working chamber placed above the con stricted part. The tapping is effected through an aperture '12 or a furnace-openvided in the masonry, between each bath, in-

magnetic core Anoptional but practical method to easily executing, inone body, all the circu-f sure the cooling of the bobbins and of the lar baths with their working chamber within the masonry, consists in previously ;cast ing themetallic-form of the same, filled to the requisite points, and then to incorporate 1 said form with the body of masonry, when .it is constructed. Such moulded form in one or more pieces and roughly soldered to- 'gether, forms the first-working bath intended to melt under the influenceof the induced current. 4 -By adding to this veii'ect of the "superheat ing by theconstriction or joining of the baths, the special superheating elfect bythe direct introduction of heat by means ofan immersed piece servinv as an electrode," there is obtained in a single apparatus the com bination of these two means of electric super-- heating, which automatically concentrates, during the working period, the maximum amount of heat in the eifective part ofthe bath, in order; to oppose the cooling caused by the immersion of the cold pieces of materials to be treated. In such case, the tensionof this additional current must at lealst'be'equal to thatof the 'inducedcurrent of the oven and the new circuit must be closed by a second electrode dipped in theworking chainbei"at.a-distance from the first. l These two electrodes may also act by forming arcs at'the level. ofthe bath.

In order to realize-such efi'ect of therm-ic concentration with resistance ovens, the surfaceof the vat '18 Figure 3, Sheet 2, instead of being flat, is fundulated, especially below and at the bottom, and that of the, resistance is alsoundulated, especiallyif use is. /-ma-d e of semi-conductive materials to obtain said resistance 19. The heat is thus concentrated at the bottom of the bath 20, owing to. the

increase ofthe heating surface for thesame volume. l

The undulation, may be placed in any part of. the vat according to requirements.

'The introduction into the bath of calories emanating. from an electric current of low voltage by'the immersed ,piece- 21 forming an electrode, gives to the semi-conductiveresistance, by the intermedium of the metallie vat 18, the benefit 10f. the current brought by the electrode piece, which raises accordingly the temperature of the resistance and thus automatically heats the bath during the period of immersion or working by the-combination of these two methods of f electric heatingapplied together in a single apparatus.

Where thepiece undert-reatment byimmersion may be a bad conductor, said result ing the additional superheating current through the vatitself by an interrupter con-.

nected with the vat. and immersion motion.

What I claim and deslre to secure ters Patent of theUnited States is:

operated by the by Let- 1. The method of applying metal toan' article comprising immersing the article in of super-heating can be obtained by send} a bath 0 the molten metal, and heating that portion-of the molten metal immediate- 1 1y surrounding the immersed article to a temperature not less than that of the remainder of the molten metal by passing an electric current through the immersed article, used as one electrode, and ,the' molten metal, used as. the other electrode.

2.'The methodof applying metal .to an article comprising-immersing'tlie article in a bath of the molten metal, and heating that portion of the molten metal immediately surrounding the immersed article to a temperature not less than that f theremainder of one electrode, and the molten metal, used as the other electrode, and heating the immersed article to a red heat to a point just above the surface of the. molten metah 3, The method'of applying metal to an article comprising immersin the article in 10 a bath of the molten -meta, heating that portion of the molten metal immediately surrounding the immersed article to a temperature not less than that of the remainder of the molten metal by passing an electric current throu h the immersed article, used as one electro e, and the molten metal, used as the other electrode, and regulating the heating by varying the intensity of the cur-- rent passing through the article.

NOEL BARBIER. '[L 8.]

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