US1168050A - Wire-drawing. - Google Patents

Description

UNITED STATES PATENT OFFICE.

BURNIE BENBOW, F CLEVELANIO, OHIO, ASSIGNOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

WIRE-DRAWING.

Specification of Letters Patent. Patented J an, 11, 1916.

Applicationfiled December 7, 1912. Serial No. 735,551.

No Drawing. To all whom it may concern: been dried out) which is made quite shiny Be it known that I, BURNIELEE BENBOW, a citizen of the United States, residing at Cleveland, county of Cuyahoga, State of Ohio, have invented certain new and useful Improvements in Wire-Drawing, of which the following is a specification.

My invention relates to the art of wire drawing and the like, and particularly to the lubrication of wire in its passage tions, the wire may be drawn through a number of succeeding dies before this coatmg requires to be renewed.

I have found that by a mode of dealing with the material employed for lubricating purposes different from that hitherto practised a degree of lubrication may be obtained without the baking operation above set forth by the first die. Under favorable cond1-' 35 centigrade or higher.

45 effected, for example,

50 gives a smooth,

through the drawing dies. I have hereinafter described my invention more particularly with reference to its application to the hot drawing of metals, since it is adaptable -with peculiar advantage to the special conditions and difficulties of this mode of drawing. The invention is, moreover, of particular value in the hot drawing of tungsten wire for incandescent electric lamp filaments and for other purposes as described in British Patents 23,499 of 1909 and 8031 of 1910, in United States Patent 1,022,182 granted April 2, 1912 to John T. H. Dempster, and in United States Patent No. 1,082,933,

granted December 30, 1913, to William D.

Coolidge, and I have hereinafter referred to the wire as tungsten wire.

As described in the above mentioned patents and application, the tungsten wire is drawn through a diamond die or other suitable' die while at a temperature which may vary from below incipient redness to a bri ht red heat or higher, the die being also pre erably heated to a temperature of say 200 to 500 To lubricate the wire in its passage through the die, finely divided graphite carried by a vehicle such as water or oil has been applied to it, and (as more particularly set forth in the Demp- 40'ster patent above mentioned) the graphite has been made to adhere in a fairly even and more or less permanent coating by baking it on the wire or burning it into the wire before the latter enters the die,-this being by heating the wire to redness just prior to the application of the lubricant, or in a subsequent heating whereby thewire is brought to the drawing temperature. This bakin or burning operation blac adherent, graphitic lubricating coating (from which all the water, oil, or other liquid has, of course,

which while inferior to that resulting from this baking. operation is much superior to anything hitherto obtained without it. I have further found that by the employment of a heating or baking operation in connec tion with this mode of dealing with the lubricating material it is possible to secure a degree of lubrication superior to anything obtained by baking as hitherto employed, and that the ease of drawing can be enhanced and the die-wear reduced quite materially. In particular, the coating thus secured is more even and more adherent, and does not flake or scale off in the heating flame as the coating previously obtained was more or less liable to'do, nor scrape off as much at the die entrance, and it is therefore much more effective both as a lubricant and in protecting the tungsten wire from oxidation. This latter function of the coating is, perhaps, as important as its direct lubricating action; for the friction in the die of the tungsten oxids usually formed by the oxidation of the wire is very much greater than that of metallic tungsten, and the die-Wear is, therefore, also greater when oxidation of the wire occurs.

According to my invention, the material employed for lubricating purposes or to protect the wire from oxidation is associated, in a solution or suspension or the like in any suitable liquid vehicle, with material which will constitute or furnish a binder to make the fine particles of such lubricating material or those by which the lubrication or protection is ultimately efi'ected stick or adhere to the wire. Of course the character of the material thus employed for either lubricating or binding purposes will depend upon the character and properties of the material employed for the other of these purposes, and also upon whether the mode of procedure is such as to bring about any chemical or other change which will materially affect the roperties of either the lubricating or the Binding material. Thus, for example, if the lubrlcating liquid is applied and the wire drawn through the die without any heating of either the wire or the die, the.

binding material should ordinarily act as a binder from the very outset; while if a baking operation such as above described is emloyed, the binding material should act as a inder before the baking or afterward or both,-irrespective of any change that the baking may produce in itsaccording to the action required in order that the lubricating material may stick to the wire evenly in the first place and adhere to it as it passes through the die. Chemical changes in the binding material such as may be causedfby heat are indeed, generally favorable to the adhesion which it is desired to roduce, and serve, as it were, to fix the inding material and the coating even better than heat unaccompanied by any such change.

While any materials and any solvent or vehicle liquid which meet the needs of the case as above indicated and are not injurious to the wire or the die may be employed, for the hot drawing of tungsten carbonaceous materials are especially suitable, both on account of their action in reducing the oxids of tungsten and for other reasons. As binding agents, indeed, carbonaceous or organic. materials unite efiicacy before and after heating or baking to an extent nearly if not position of this character commerciallyknown as aqua-dag with 2% pints 'of water and adding either 70 cubic centimeters of the glucose solution marketed under thename ofvKaro Kern syrup or the same amount of solution made by adding a minimum of water to cane sugar and boiling down to molasses, about one cubic centimeter of a 2 per cent. mercury bichlorid solution or a proper amount of some other suitable preservative being preferably added to each .pint of the total mixture. It may be observed that commercial aqua-dag itself apears to contain organic matter designed to keep in suspension the relatively coarser particles of graphite that might otherwise tend to settle out, and that such organic matter has in some slight degree a binding action similar to that of the glucose and the cane sugar just mentioned. The amount of ove stated are be applied to the wire by drawing the latter through a vessel containing the liquid or 'througha body of cotton waste to which. 7 V.

the llquidhas been apphed in excess, as de-,

scribed in the aforesaid-Dempster patent, or bypassing-the wire over a deep grooved revolving pulley partially immersed in a body of the liquid, asdescribed in the appllicatlon of James W. MacKenzie, Serial 0. 722,000, filed in the United States Patent Ofiice, September 23, 1912, under the title Wire lubrication .and the like, and assigned to the assignee of this ap lication, or in any other suitable manner. he coating thus formed will be found to adhere to the wire without any baking or heating, especially if the liquid is got rid of by allowing it to dry before the wire enters the die. Superior results can, however, be obtained by heating the wire so as to firmly fix the coating as well as get rid of the liquid, and as it were, bake the residual coating on the wire in a. smooth, close, firmly adhesive 'condition-the very best results, indeed,

usually being secured when the binding material has been entirely carbonized. The heating or baking may be accomplished by passing the wire to which the liquid lubricant has beenapplied through a zone of gas flame of suitable length to heat it to a bright red heat for to Whatever-temperature is preferred for the drawing operation, the wire passing from the flame right into the die, or, for example,- in any of the other ways described in the above mentioned Dempster patent. y J

What I claim as new and desire to secure by Letters Patent of the United States, is

1. A lubricant consisting of finely divided graphite in suspension and a binder composed of material which maybe carbonized by heating, the roportion of the said binder being considera ly'l'in'exc'ess of that necessary'to keep the said graphiteinsuspens1on.

2. A liquid lubricant comprising finely divided graphite in suspension and a sugar syrup, the proportion of the latter being 7 considerably in excess of that necessary to keep the graphite in suspension.

3. A lubricant consisting of deflocculated graphite and a binder therefor composed of material which may be carbonized by heating, the proportion of the said binder being considerably in excess of that necessary to keep the said graphite in the deflocculated In witness whereof, Ihave hereunto set sta lteA 1 d 1 b d fl my hand this third day of December, 1912;

lqui u ricant comprising e occulated graphite and a carbonizable syrup, the BURNIE LEE Q proportion of the latter being considerably Witnesses: in excess of that necessary to keep the HARRY J. Veer, graphite in the defiocculated state. WILLIAM Enw. KOHN.