US2493768A - Method of lead coating - Google Patents

Description

Jan. 10, 1950 J. MAGNIN 2,493,768

METHOD OF LEAD COATING Filed June 21, 1944. 3 Sheets-Sheet 1 Molten flax Molten Flux u M w flizforneys Jan. 10, 1950 J, MAGN|N 2,493,768

METHQD 0F LEAD COATING Filed June 21, 1944 3 Sheets-Sheet 2 Jan. 10, 1950 Filed June 21, 1944 J. MAGNIN METHOD OF LEAD COATING 3 Sheets-Sheet 5 Patented Jan. 10, 1959 METHOD OF LEAD COATING JacqucsMagnin, Chestnut Hill, Pa., assignor to Horace C. Knerr Application June 21, 1944, SeriaLNo. 541,318

6 Claims, I inv n ion relates o coatina" me al pa s with. lead. as alubri'cant. to. facilitate successive co1d;workingfoperatibns changing" the shape of the metalwithout. necessity for interme diateiannealings and/or. pickllngs. Commercially pure d is o dinarily used? The, main purposeot the. invention is to :produce a surface whichii's coated with lead and in which the. leadi'adheres even after numerous cold passes,

A .furtti r n mo eis. operform the lead o tings of metals. in, a single operation.

A. further. purpose. is to avoid the necessity o pre minars wet bath treatment bef re actual. leadcoetih andiito use a dry bat tr .ment o ly,

A f er nuro se. ist apply. ac tates o a chlorides or sulphates, of antimony; bismuth, cadmium or tinrfl'oat'ing. upon th surfac f a molten ba h. oflead. as a means ofprep r ngft surface r iron.anGLOILmetaI-aHQys gen ra s. fo a coeting,.or,ileadifor lubri ating purpos nd to use varioussaltfi ofir n. f r the sam purpos A. further purpose to apply tan us chl rid stannie chloride. cadmium ch r d or an im ny chlorid fluxes having; amni ybo h for n when t. ishe ns. lead" coated a dfo t lead. co tin andithus o facil e h ati operat on and" produce mo e p rmen n n i er results than could; othe w se b et a d A further purpose is't'o coatwithlead from a molt n bath of eed ...anc forpu po e br c tion with the aid of a molten.- fluxfloating on th sur ace Qf'the ead, and. c ng ch10- ides; ora e n sulph es f antimony; smuth cadmium or-tin", h ati g par s'to' be c ated within the molten 'fiux' and'ipassingthem through i nto e molte e di w e an uncoated surface of the lead-or through theflux as ay e p e rr d:

A further purpose" in lead'cqating for lubrication is to pass metal' objects to be lead coated through a bath containing zinc chloride and stannicr, or, stannous chloride; cadmium chloride .or' antimony chloride asan alloying flux, facilicoating with leadupon steel;- copper or brass, chrome-iron and nickel-chrome, for example, reducing the cost oi the coating; the time and handling required-and the spaceoccupied by the operation;

A; further pu PQSe is" to unitea lead coating tosteel; iron, copper; brass nickel-chrome; chrome-iron alloys and non-ferrous alloys generally-at a: lower--- cost and, in shorter time than previously-have been available;

A further purpose is to eliminate the use of mercury compounds in dipping operations for coating metals with lead.

A further purpose is to eliminate hydrousbaths other than suchas pickling in preparation: for ultimate dry bath" treatment coating leadupon various metals.

A further purposeis sul asta-ntially to elimimate the use of ammonium" compounds in a bath for dry treatment of metals tocoatthei'r sur faces with lead, using a trifling amount only to reduce the formation oifioxid'es' in the bath but permitting the use'cf much more where this is desired.

A further purpose is to dip-the metals to be coated through the flux inta t he lead; to move the articles to be coated back and forth within the lead and flux and" to advancethe articles along a pathfrom the position of flux covering to the position of ultimate withdrawal from the molten lead, passing them through the flux and bath repeatedly but finally withdrawing the articles which have been coated bythe lead.

A further purpose is topassthe-articles to be coated through the flux into the molten lead, to expose the articles todifferent parts ofthe lead bath while shifting them within it and finally to withdraw the articles through a lead surface free from flux coating.

A further purpose is -to dip the articles by a mechanical dipping device such as a conveyor chain, to heat the device so that' it"will not chill the lead and to reciprocate theaarticles withinthe molten lead during their progress from a point at which they lie below the flux to a point at which they are withdrawn from thelead.

Further purposes will appear: in the. specification and in the claims.

Figure 1 is a sectional view of-ratreating pot showing a simple applicationofthe? preferred form of my inventions.

Figure 2 is a sectional view: showing a second form of my invention.-- Withdrawingz the; metal coated through thBtfllllEi'i'S" objectionable according to the salts usedii'n theaflux Itreducesc but does not destroy the lubricantriunction of the lead.

Figure 3 is a vcrtloahsection" showing a form of the invention; corresponding generally with Figure 1 but in? which. a mechan c l ipp mechanism is used. The; section is taken upon the line 3-3 of Figure:

Figure 4 is a fragmentarwsectioniot the str uc ture of Figuren'i takero atright angles-to that of Figure 3.

ing, Serial No. 466,195, filed November 19, 1942,

now abandoned.- Related subject matter to the present-application appears in my copending applications Serial No. 541,347, filed June 21, 1944, for Metallic lubrication; Serial No. 544,072, filed July 8, 1944, for Method and machine for lead coating; and Serial No. 544,073, filed July 8, 1944, now abandoned for Coating method.

In cold working of metals in order tobring them to the required shape and dimensions the metals usually have to be annealed, pickled and lubricated between each two succeeding cold working operations.

Ductile metals are hardened by cold work, and this is true notwithstanding diiferences in lubricants.

The degree of hardness produced in the initial stages of cold work is such that ordinary lubricants are inadequate toovercome the frictional resistance between the die, etc., and the metal. In suchjcases reannealing becomes a necessary operation. This ordinarily involves another pickling operation to remove the oxides produced by annealing.

Under this invention the coating of lead applied to the surface of the; metal functions as a so much superior lubricant that frictional resistance is greatly reduced even after many suc- .cessive cold passes.

With various metals initial cold work causes a great increase in hardness over that in the annealed condition but continued cold work does not correspondingly increase the hardness.

It has been found that coating certain metals such as iron, steel, copper, brass, chrome-iron, nickel-chrome alloys and non-ferrous alloys with lead generally acts as a lubricant in drawing tubing, or wire drawing, deep drawing, stamping, etc. by reason of which after the first annealing and pickling it is not necessary to repeat these operations after a considerable series of mechanical distortions during which the lead coating flows along with the metal but is not eliminated, with the result that even after as many as six or seven successive reductions or distortions the metal still shows a lubricating coating of lead.

A coating of lead upon the metal can be produced in various ways.

Another feature of importance is the fact that the lead adheres to .the metal to such an extent that even when in the course of cold drawing operations the hardness of the metal becomes too great tocarry on the cold work it is still possible to reanneal this metal (provided this is done in a controlled atmosphere) without destroyingthe lead coating. Therefore with the original lead coating from the start further cold drawing operations can still be performed with the original lead coating as lubricant. In retort annealing (or controlled atmosphere) the lead coating is not destroyed and does not form oxides and still retains its lubricating properties.

' Pure lead can be electroplated upon the iron, by electrolytic means but the adhesive qualities of this coating are not satisfactory. The deposite is pulverulent and crystalline and is rather easily removed. It isuneconomical as it requires an expensive plant and careful and constant supervision. It has the one advantage of unsual purity of the lead which is desirable in order that the.

full malleability may be attained; but the lead is not incorporated into the surface of the metal coated. Full retension of the lead requires a hold of the lead upon the metal similar to that secured by impregnation, by which the lead permeates the surface of the metal.

Another-way in which attempt has been made to incorporate the lead to fasten the lead upon the surface of the metal is by alloying the lead with a small percent of tin or of antimony. Each of these alloying metals hardens the lead to such an extent as, in large measure, to defeat the lubricant effect of the lead upon the surface in subsequent mechanical operations performed upon the metal coated. Coating of metals with lead alloys has been proposed in a series of patents in which the coating was planned for protective purposes but in which there seems to have been no thought of use as a lubricant and in which there is no such teaching. The character of coating planned was prohibitory for such a purpose inasmuch as the coating bath contained at least two percentof tin and two percent of antimony; Onedisclosure proposes ten percent of antimony and five percent of tin. In one of the patents a final passage of the coated material through a stannous .chloride flux was contemplated for the express purpose of giving a thin coating of tin. Though the proportions of the bath were not given the ma.- terial was constantly referred to as asolder. It evidently contained a large percentage of tin.

The purpose of the antimony and tin in these several disclosures was evidently to use the alloy with tin as a means of making the coating adhere to the surface of the metal to be'coated.

Another method which has proved to be successful to a certain extent, after annealing and pickling, clips the metal to be coated in an aqueous solution (i. e. a wet bath) of bichloride of mercury saturated with zinc chloride as a preparatory step in the method, and subsequently passes the metal to be coated through a non-aqueous (dry) molten flux floating on a molten lead bath. The fiux contains zinc chloride and a considerable quantity of ammonium chloride.

The mercury process entails an additional operation and the cost of bichloride of mercury for the wet step of the process olfsets a great part of the savings. v n

One of the difficulties with the bichloride of mercury treatmentis that the slightest trace of a. grease before amalgamation prevents amalgamation, and if on the amalgamated surface (for in.- stance from the handling of the metal with greasy gloves) prevents the leadfrom adhering. Furthermore the bichloride of mercury is a poison and is a dangerous chemical with which to deal.

I have discovered that excellent results can be attained by a dry dipping process without any preliminary wet process .step such'as, for example, a bichloride of mercury step. I use a salt derived from a metal which has affinity for (i. 'e.

tends to alloy with) both the; lead and the metal which is to be coated with the lead. I pickle in the usual Way. r l v The salts preferably usedarethe chlorides, acetates, borates and sulphates.

Considering the price as well as the desirability, either molten stannic'or molten stannous chloride floating on the molten lead gives good results, better than secured from others of the salts named. Either cadmium or antimony chloride and iron have the same another way of stating form molten fluxes also gives good results. All three-use separately or permissibly together-give better results when used with zinc chloride than without it but will operate to lead coat the surface of the metal for lubrication purposes if used without zinc chloride. On the other hand zinc chloride will not lead coat the surface when used alone nor when used with ammonium chloride. The sulphates and borates of bismuth, antimony, cadmium, tin

chloride, will operate without zinc chloride-but better with it-and are improved by the presence of sodium chloride.

In my dipping operation I dip through a flux which may cover a part only of the surface of the lead bath, so that the dipped metal may be withdrawn from a clear lead surface beyond a partition as in Figure 1; or the metal may be dipped into a completely flux-covered lead bath and withdrawn through the floating flux of the same bath, as in Figure 2.

In Figure l the tank is shown at with a content of molten lead 6 and a partition I. The flux salts are shown at 8 on the entrance side of the partition and may comprise various salts in the alternative, including stannous or stannic chloride or cadmium chloride or antimony chloride, or a borate or sulphate of cadmium, of bismuth, of antimony or of iron. Here again the operation is improved by the use of sodium chloride and of zinc chloride. The clear surface of the bath beyond the partition is shown at 9.

In Figure 2 the pot is shown at 5 holding a molten lead 6 upon which a molten flux 8' floats,

spreading over the entire lead bath. The form of Figure 2 has a disadvantage for lubricating purposes, made worse, of course, where the flux contains tin or any other metal which has a definite hardening effect, that where there is a definite layer of the flux left on the surface of the coating of lead, it reduces the lubricant quality of the coating of lead.

Because each of the metals, tin, cadmium and antimony, etc. has an afiln'ty for (this may be but will form an alloy with) the metal to be coated and with lead, its salts bywhich the surface of the metal can be covered with lead. This is true of metals generally, that they can be lead coated by dipping into a molten bath of commercially pure lead through a molten flux if the flux tend to alloy with the metal to be coated, and also with the lead.

The lead coated articles are then withdrawn from the lead bath and allowed to cool when they are ready for such operations as drawing, wire drawing, rolling or deep stamping without intermediate annealing, pickling and again lubricating.

Because other materials than lead, whether definitely hardening the surface of the lead or forming an alloy with lead of inferior lubricant quality or not, act as impurities to reduce the effectiveness of the lead as a lubricant, it is quite desirable to have pure lead. It is difficult, or at least expensive to get chemically pure lead but I have secured excellent results with a bath of what is known as commercially pure lead.

The principal benefit of my invention lies in the fact that the union of the lead with the outer part of the metal coated includes a permeation of the metal surface by the lead much like impregnation and possibly designated as impregnation. It may be a case of alloying with both metals.

characteristics as the The chlorides of the different metals used have been found to be the most suitable salts and at the same time the cheapest.

Some of the fluxes used successfully by me in lead coating have been as follows:

' Parts Stannous chloride l Zinc chloride 3 with a small addition from time to time of ammonium chloride to reduce oxidation Parts Cadmium chloride 1 to 2 Zinc chloride 8'to 9 with a smal addition from time to time of ammonium chloride 7 V Parts Ferric chloride 2 Zinc chloride 4 Sodium chloride 2 Ammonimum chloride l Ferrous chloride 2 Zinc chloride 4 Sodium chloride 2 Ammonium chloride l Iron sulphate (ous) 2 Zinc chloride 4 Sodium chloride 2 Ammonium chloride 1 Zinc acetate 2 Zinc chloride 4 Sodium chloride 2 Ammonium chloride 1 Zinc borate 2 Zinc chloride 4 Sodium chloride 2 Ammonium chloride l Antimony trichloride 2 Zinc chloride 4 Sodium chloride 2 Ammonium chloride 1 The reasons back of the action which takes of forming alloy with each of the metals to be coated and the lead, the action being similar to an alloying action but the flux not entering into actual alloy with either to an extent which would deplete it seriously, or whether there be some other reason for the action. At any rate by whatever flux used the lead coating persists through cold-working with amazing tenacity, so much so that I have been required to remove it after complete cold-working, in order that government inspectors can make sure of the surface under the lead.

Another measure of the unusual persistence of the lead coating is the fact that in the rare cases of reannealing, during cold working where my invention has been used, reannealing in a controlled atmosphere (such, for example, as an atmosphere of disassociated anhydrous ammonia) does not disturb the lead coating and continued cold working does not require additional coating.

I have had great success in cold working of V of the lead which 7 gports amotor l3.connected by Jnetals which have been coated by my invention, which is -a:-tribut e:to the comparative purity I :have used, and particularly :tothe fact that-the lead has :been substantially free from alloying tin-or'alloying other metals :WhiCh would have a hardening effect.

I have found that a better vcoatingoi lead is :secured where the metal to be coated, herein referred to generally as the work, is passed through the flux and then'is reciprocated or therwise moved back'an'd forward in the flux and lead. In order that the work may engage different parts of the bath and stir the bath, the

work'is'advanced from one range of reciprocation tolanother, progressively :toward the point of withdrawal from the lead. The work is with- :drawn preferably through a clean lead surface ;:since in this way, the flux is .not. given opportunity vi to forma final wcoatingupon the lead. The reciprocation is not suggested in Figure '1 but the withdrawal throughaclean lead surface Mechanism is not necessary forthe freciproca- 'tionff as "I refer to any movement of the metals ito'be coated, as any such desired mov'ement of "the work articles 'nipulation, dipping the articles into the bath .lin .any suitable container, preferably in the form of 'a cageor-basket, closed to retain the work pieces butpermitting free flow of bath through it. The .basket and work piece content are moved about in the bath as desired. However, ,an effective movement can be secured by mechanism. For this reason a suitable machine has been illustrated in Figures v3, 4 and 5 and will now be described.

A,p1atformBissupported uponlegs and 11, resting upon any suitable base, here shown as the 'upper rim 12 of thepot .5 The platform supbelt M with a pulley I 5. The speed of rotation is reduced through -anysuitablegearbox16 so that the rate of ro- -'tationof-shaft 'l'! willbe low'enough for present purposes. The shaft-carries a crank arm [8 connected "by apin 19 with a connecting rod 20. The throw of the crank arm maybe adjusted by connecting the pin I9 with the crank arm at otherpoints, such as at 2|, for example.

A ratchet wheel 22 is mounted upon a shaft 23 supported by bearings upon struts 24. The shaft carries also spaced sprocket wheels 25 upon whicheoperate the chains 26 of a chain conveyor 'having conveyor .bars21 across from chain to chain constituting flights 28. The bars 21 are merely supports connected with the chain at convenient pointsby attachment to tabs 29.

.A partition or division plate 30 suitably sup- ;portedfrom theside structure 3| and brackets .32, dips down into the lead bath 6 to prevent the flux 8 from distributing over the surface of the bath. The flux is otherwise confined by box v33. The conveyor bars on their downward lstrokes pass through the flux into the bath.

.The connecting rod ispivoted to a rocker arm '34 at a distance (rocker arm length or throw) from shaft 23 large enough so that rotation of the crank arm I 8 will cause oscillation ,only of the arm 34. The arm 34 carries a holder .35 for a ratchet plunger 36. The plunger is drawn toward engagement with the teeth of the ratchet wheel by spring 31, capable of being with- A drawn therefrom byhandle38 so-that the ratchet disc and sprocket wheels can be rotated by hand to any extent desired when the ratchet plunger 36 has been withdrawn from the teeth of the ratchet wheel. This makes it possible to turn can be effected by hand Ina--- .carry the basket The reciprocation seems :to 'have ya scrubbing action and if the metalto :be coated :be finally taken out-of thesleadat a lead surfacetfree from flux there seems to be no film of flux-onthe coating. .Even where 1 out through flux there is little trace of flux and the metal-coated comes the fluxcan be lselectedtmbe aslittle objectionable :as possible.

As seen in Figure 4 the preferably'closed work :cages or baskets for .the articles to be coated .are hung .by hooks 1-40 from barsor flights 22:1.

The hooks are-connected with thebars orrfiights .111. a position slightlyto-the right of that shown in Figure '4, after,

which the baskets and the ihooksare :slid to the left so that the 'hooks 1001116 beneath guards! I, holding the baskets :in

position upon theflightsa-even when the'baskets are turned upside-:down, astakes'pIace-When the sprocket chains: are-moving upwardly to 'ther'left -(Figure.3) of the partition:30.

The lower parts .of the .sprocket achains pass about wheels 42 down in the ;bath, which-wheels need not besprocket wheels :but maybe pulleys -merely. Bearings 'for the :pulley shaft '43 are supported by stays 'extendingldownrfrom the partition :30. It has :notbeen considered necessary to show thesupportssinzdetail other than to indicate them at45f-in Figure The -pot 5 is conventionally shownas seated in a concrete bed-dfizhaving-airim 411upon'which the flange '48 of the, pot may 1 be rested. In order that-the metalofthe conveyor,-such as-the chains and the:flights,;may not-chillthe lead bath, a heater is supplied, including .a gas pipe 49 controlled by alves50. It dischargesgas through a burner nozzle :15 52 maybe fed through an I-so :that hot air at upright pipe-53 and a manifold 54. The manifold distributes thehot products of combustion -.against the :chain, ipreferably onthe downside of the conveyor, :heating {the "conveyor sufiiciently so that there is no chilling of the molten:lead. The bath mayalso be heated separately'asby an'eleotrical heating unit within'the bath. 'Heater-55-is conventional and is supplied with :current through wires 56 :protected by'conduitf51.

:individual shown and the drawthe extent Notwithstanding that "there is that this mechanism will be claimed, ,ing 'is intended to 'be conventional to that it represents .one :mechanism by which :the baskets "for the metal to :be coated may :be moved back and'forward within the lead" bat and across the fluid line. and -it isthedntention to claim the method as well as the mechanism by which this function is secured. 7 7

Whether the articles-to be coated (work) "be moved by hand or by'mechanism for the purpose, such, for example, asthe'one illustrated,

the present invention oifers considerable advantage in uniformity and completeness of coating to be secured by this movement. T V

In operation, :articles .tolbe coated and subsequently to be cold-processed :are .placed within the basket and the basketis-attachedto a'flight .of the conveyor, af.ter which theratchet plunger is withdrawn from -theteeth-of the ratchet wheel while the sprockets and chains are turned to through the flux and into the lead bath and back again so that with reciprocation due ltQ the, mechanism the basket will re.- .ciprocatehack and forward past the flux :line.

=The'rratchet 'tooth .-is .zreset within :the .ratchet wheel-.atisuchia pointiinithe revolution of-rcrank arm l8 that the reciprocation Will take place initially premthe desired range in t d pt of the molten pool of lead. The revolution of the crank arm l8 will causeoscillation of the arm 34 with corresponding oscillation of the ratchet wheel and the sprocket wheels, and with successive reversals of limited movements of the sprocket chains.

When there has been sufficient reciprocation p t e baske for the ar cle i erlr t b tas es; e ratchet p n er wi aws fro the ratchet wheel, the sprocket vchainsare ad- ;vanced-a distance sufficient to .carry the basket through thelead and out to a part of the bath at which reciprocation is withn the lead alone the ,articles are withdrawn. The ,ratchet plungeris ,allowed to enter a ,diiferentnotch ,in the ratchet wheel. Reciprocation of new basket is begun while other baskets along the conveyor are reciprocated where they may be.

While the movement of the basket has been called reciprocation, because during a considerable part of the distance travelled the container will move in a straight line and back again, as seen in Figure 3, there may also be oscillatory movement of the basket where it travels about the curved portion of the wheel at the bottom of the bath. Adjoining the straight stretches of the sprocket chains there will be movements which will be partially reciprocations and partially oscillations. It is my intention to use reciprocation to cover these various movements.

When there has been sufficient reciprocation of the baskets within the molten bath and flux the ratchet tooth is withdrawn from the ratchet wheel and the sprocket chains are turned to bring the baskets out from the bath, the container is drained in a trough 58 or other resting place and is subsequently cooled.

The coating is followed by cold-process working in dies or by other tools securing the lubricant advantages.

The invention has been quite successful in making cartridge casings from a cupped or fiat blank which is first cupped and then successively drawn to the final size of the casing needed. With the lead coating I have performed five successive drawing operations before annealing and then, with a controlled atmosphere I have been able to anneal without losing the lead coating nor the lubricant quality of the lead coating, continuing to perform other successive drawing operations.

The lead coating forms a basis for continuing cold processing without annealing and these operations are contemplated in connection with the coating.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such in so far as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. The method of coating a metal cold working blank preparatory to cold working with at least commercially pure the coating during cold working, which comprises forming a bath of at least commercially pure molten lead, floating upon the molten lead a flux comprising a metallic salt which iszfusible and relatively stable at a temperature. corresponding substantially .with that of the molten lead, the salt :being selected from the group consisting of acetates, borates, chlorides and sulphates of the metals antimony, bismuth, cadmium and tin, passing the metal cold working blank to be coated repeatedly back and forth across the flux-molten lead interface into the molten lead, and withdrawing the metal cold working blank coated from the molten lead.

' 2. Themethodofrcoating a steel cold working blank preparatory to cold working .with at least commercially pure lead for lubricating by the coatingduring' cold working, w hich comprises forming a bath of at :least commercially pure .molten lead, floatin'gupon the molten lead a-flux comprising a metallic salt which is fusible and relatively stable ata temperature cor-respond.- ing substantially with that of the molten lead, the salt being selected from the group consisting of acetates, borates, chlorides and sulphates of the metals antimony, bismuth, cadmium and tin, advancing the steel cold Working blank through the fiux into the molten lead by a back and forth motion which causes an individual point on the blank to move repeatedly across the interface between the flux and the molten lead, and withdrawing the steel cold working blank coated from the molten lead.

3. The method of coating a metal cold working blank preparatory to cold working with at least commercially pure lead for lubricating by the coating during cold working, which comprises forming a bath of at least commercially pure molten lead, floating upon the molten lead a flux comprising a metallic chloride which is fusible and relatively stable at a temperature corresponding substantially with that of the molten lead, the chloride being selected from the group consisting of cadmium chloride and tin chloride, the flux containing at least 10% of cadmium chloride or at least 25% of tin chloride, passing the metal cold working blank to be coated repeatedly back and forth across the flux-molten lead interface into the molten lead, and withdrawing the metal cold working blank coated from the molten lead.

4. The method of coating a metal cold working blank preparatory to cold working with at least commercially pure lead for lubricating by the coating during cold working, which comprises forming a bath of at least commercially pure molten lead, floating upon the molten lead a.

flux comprising a metallic salt which is fusible and relatively stable at a temperature corre--;. sponding substantially with that of the molten lead, the salt being selected from the group consisting of acetates, borates, chlorides and sulphates of the metals antimony, bismuth, cadmium and tin, and at least one chloride of the class consisting of zinc, sodium and ammonium chloride, passing the metal cold working blank to be coated repeatedly back and forth across the flux-molten lead interface into the molten lead, and withdrawing the metal cold working blank coated from the molten lead.

5. The method of coating a metal cold working blank preparatory to cold working with at least commercially pure lead for lubricating by the coating during cold working, which comprises lead for lubr t y 76 forming a bath of at least commercially pure molten lead, floating upon'the molten lead a flux comprising a metallic salt which is fusible and relatively stable at a temperature corresponding substantially with that of the molten lead, the salt being selected from the group consisting of acetates, borates, chlorides and sulphates of the metals antimony, bismuth, cadmium and tin, and at least two chlorides of the class consisting of zinc, sodium and ammonium chloride, passing the metal cold working blank to be coated repeatedly back and forth across the flux-molten lead interface into the molten lead, and withdrawing the metal cold working blank coated from the molten lead.

6. The method of coating steel with lead for lubrication purposes for cold working, which comprises forming a bath of at least commercially pure molten lead, covering the molten lead bath with a molten flux comprising a sulphate selected from a group consisting oftin sulphate, cadmium sulphate and antimony sulphate, dippinga wrought steel cold working blank repeatsteel cold working blank the lead bath at a point 5 from flux.

coated with lead from where the bath is free JACQUES L REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Date Kalil Dec. 4, 1945

Claims (1)

1. 5. THE METHOD OF COATING A METAL COLD WORKING BLANK PREPARATORY TO COLD WORKING WITH AT LEAST COMMERCIALLY PURE LEAD FOR LUBRICATING BY THE COATING DURING COLD WORKING, WHICH COMPRISES FORMING A BATH OF AT LEAST COMMERCIALLY PURE MOLTEN LEAD, FLOATING UPON THE MOLTEN LEAD A FLUX COMPRISING A METALLIC SALT WHICH IS FUSIBLE AND RELATIVELY STABLE AT A TEMPERATURE CORRESPONDING SUBSTANTIALLY WITH THAT OF THE MOLTEN LEAD, THE SALT BEING SELECTED FROM THE GROUP CONSISTING OF ACETATES, BORATES, CHLORIDES AND SULPHATES OF THE METALS ANTIMONY, BISMUTH, CADMIUM AND TIN, AND AT LEAST TWO CHLORIDES OF THE CLASS CONSISTING OF ZINC, SODIUM AND AMMONIUM CHLORIDE, PASSING THE METAL COLD WORKING BLANK TO BE COATED REPEATEDLY BACK AND FORTH ACROSS THE FLUX-MOLTEN LEAD INTERFACE INTO THE MOLTEN LEAD, AND WITHDRAWING THE METAL COLD WORKING BLANK COATED FROM THE MOLTEN LEAD.

Images