US1925305A - Process for applying metal lubricants - Google Patents

Description

Patented Sept. 5, 1933 UNITED STATES PATENT OFFICE PROCESS FOR APPLYING METAL LUBRICANTS No Drawing. Application May 13, 1929 Serial No. 362,867

15 Claims.

My invention relates to the art of applying metal lubricants to the surface of metals to be used in drawing operations and more particularly in the drawing of fine wire.

tion of lubricating coatings for all types of drawing operations, I shall describe my invention in reference to the drawing of fine wire where many of the advantages and benefits resulting from the invention are more, particularly utilized. I shall endeavor throughout the specification to set forth the broad principles involved, giving specific examples by way of illustration and freely stating what I believe to be the facts in the belief that the information thus given will best acquaint those skilled in the art with the invention in its broadest aspect, but I realize that differences of opinion may occur and I do not wish to limit 00 myself to the theories or opinions advanced.

uses as its raw material hot rolled steel rods'of suitable size and weight. The scale, formed on the rods during the hot rolling operation, is usually removed therefrom by immersing them in 5 a pickling solution of sulphuric acid or other suitable material. Before the first drawing operation the rods are given a treatment of lime or other suitable substance which will form a surface layer upon the metal and act as a lubricant between the die and the surface of the rod. Low

carbon steel wires of comparatively large diameter are usually drawn dry without the aid of further lubrication. After the first drawing the wire is annealed, coated with a lubricant as before, and again drawn. Thus, by successive drawing operations the metal is reduced in diameter until a wire of about 21 gauge. is reached.

This may be said to be the boundary between coarse and fine wire, drawing operations upon 40 wire finer than this generally requiring better lubrication than that previously employed.

In order to provide a better lubricant it has been customary in the prior art to develop a layer of copper upon the surface of the wire to act as a lubricant as does the lime in the coarser operations. Subsequent drawing operations have also usually been carried out in a soap solution or similar bath to further facilitate the passing of the wire through the dies. In producing the copper coating the wire has been first annealed in some suitable manner and then immersed in a sulphuric acid or other cleaning solution. The wire is then washed in water and immersed in a coating bath. The action of this bath has been highly erratic. The formulae have been. developed While the process is applicable to the produc- In the manufacture of fine wire the wire mill almost completely through experience and little has been known or understood of the exact functions of the different components of the bath. Because of this and the complexity of the bath, when the latter fails to function properly it is generally necessary to discard the old bath and prepare a new one. The preparation of .the bath has been surrounded by superstitution and secrecy with the resulting inefficiency and excessive loss of reagents due to frequent changes .of the bath containing unused and expensive reagents. It was necessary to dump the bath about every six to eight hours discarding all of the reagents therein and the labor of compound ing them. It has been prepared by rule of thumb methods and its action has been little understood. For example, one of the best of such baths is prepared in the following manner: Pig tin is flaked and added to a solution of copper sulphate and the mixture treated with steam. The tin replaces the copper to form stannic sulphate, the copper being precipitated. The stannic sulphate solution forms one of the reagents of the bath. Another reagent is formed by treating copper sulphate with steam. A third reagent is formed by fermenting rye flour. The fourth and final reagent is diluted sulphuric acid. These four reagents are mixed in varying proportions, according to the individual operator to form the coating bath. After the wire has been immersed in this bath for a suitable length of time it is withdrawn and washed in water. After the coating operation the wire is many times placed in vats containing water and rye flour or other reagents where it is permitted to stand for from two hours to two days before being drawn.

Operations involving the drawing of fine wire have, prior to this time, almost universally employed diamond dies for the purpose. Other materials such as alloys of tungsten carbide have been advocated by various manufacturers but none of these have been found satisfactory for the purpose. It will be seen that because of the excessive cost of these smaller dies it is highly desirable that a perfect lubricating coating be obtained upon the surface of the wire which will prevent the steel of the wire, during successive drawing operations, from coming in contact with the dies. The processes of the prior art.have failed to do this, the coating produced, at least partially breaking down before the wire has passed through the fourth die.

One of the principal objects, therefore, of my invention is the provision of a process for applying coatings of metallic lubricants upon the surface of metals to be acted upon. in. drawing operations.

I have also aimed to provide a method of applying metal lubricants in which the bath may be easily, uniformly,'and accurately prepared.

A still further object or" my invention is the provision of a coating bath requiring no experienced help in mixing the solutions or treating the metal.

Another object of the invention is the provision of a process in which the solutions employed have little or no odor.

I have also aimed to provide a process for applying metal lubricants of, sufficient adherence and durability to permit the use of alloy dies instead of the customary diamond dies.

A 'still further and important object of the invention is to provide a highly simplified and economical means for applying a metal lubricant to articles to be drawn.

Other objects and attendant advantages will become apparent to those skilled in the art as the description proceeds.

After heavy wire rodding has been drawn to about 21 gauge by the usual method and annealed I subject the wire to a novel and simplified treatsolving ment whereby a highly improved metal coating is produced upon the surface thereof. Instead of cleaning in the usual five percent sulphuric acid solution I prefer to employ a solution of about seven percent hydrochloric acid. The concentration of acid may, however, be varied within wide limits and I do not wish to restrict myself to any specific concentration. The sulphuric acid bath of. the prior art may be used for cleaning but it is messy and I prefer to use the hydrochloric acid bath whereby the subsequent washing step is eliminated, the hydrochloric acid being carried over into the following bath to provide a continuing supply of acid to the subsequent bath. It will. also be seen that under certain circumstances other acids may be used in appropriate concentration, the acid depending upon its ability to clean the metal and upon the chemical composition of subsequent reagents presently to be described. The method of cleaning is not an essential part of the process, the only requirement being that the wire be cleaned by some appropriate means. The wire after being washed in the hydrochloric acid solution as described above, is immersed for about a minute directly in a treating solution made by diswhite arsenic or arsenous oxide in hydrochloric acid. The acid may be diluted if i. desired and an excess of arsenic should be added,

-. bination of these salts than with the copper salt alone, due, no doubt, to the repressing action of common ion. The specific gravity of the bath is about ties. The wire need only remain in this bath for about three minutes and is then removed and washed when it is ready for subse uuent drawing operations.

Iit will be found that very little care is required in the preparation of solutions, the arsenic bath being effective so long as an excess of acid and arsenic remain in the solution. I have found masses that the bath lasts indefinitely and that in operation the only attention it requires is periodic additions of arsenic and acid. While, no doubt, the bath acquires certain impurities from the metal passing through it, these do not appear to ever reach sumcient concentration to interfere with the normal functioning of the bath. The concentration of the copper bath does not appear to be important so long as it retains its blue-green color, in other words, so long as it retains appreciable quantities of copper ions. The bath never needs to be dumped or changed if additions of blue stone are made from time to time to maintain the concentration thereof. While I do not profess to know the theory of the reactions taking place in the process I am led to believe that the arsenic deposit acts as an inhibitor of the subsequent reaction between the iron' and the copper salts. The copper coating is believed to be formed by the replacement of copper in the copper salt by the iron of the metal, the copper precipitating upon the wire. If this reaction takes place rapidly the copper will be rapidly liberated and form upon the wire in comparatively loose powder. This deposit will be insecurely held to the wire. If, however, the rate at which this copper is liberated from its salt is materially decreased it will precipitate upon the wire in very fine crystals, whereby a highly adherent coating will be produced. The arsenic is believed to reduce the rate of this reaction and consequently increase the tenacity with which the surface film of copper is held. Its function is thought to be that of an inhibitor since only minute quantities are consumed in the process. It is also believed that any compound of arsenic may be usedfor this purpose which will furnish substantial quantities of arsenic ions. This means that any water soluble dissociated compound of arsenic may be used.-

According to this theory suflicient arsenic is absorbed by the wire and carried through the washing bath into the copper bath to effectively retard the rate at which the copper is deposited. While I have mentioned only arsenic, soluble salts of other metals, such as antimony, bismuth or lead, may be employed though I have found arsenic to be superior thereto for the purpose.

It will be seen that other compounds of copper than the sulphate may be employed. fact,

any copper compound may be used which is ca pable of yielding copper ions in solution. I have found the ammoniacal salts of copper to be satis factory. The soluble salt of any metal in which the iron will replace the metal of the salt and cause it to be thrown out of solution may be used such as gold, silver, or lead salts.

First among the numerous benefits derived from my improved process is the fact that wire carrying these coatings may be carried, in a soap solution, through an indeterminate number of dies without breaking the copper coating thereon. In a single operation I have carried wire so coated through nine to eleven dies increasing the length of the wire by eight times and reducing the wire from 21 gauge to 33 gauge without breaking this surface film. The resulting wire retains a distinctly copper color and upon examination has been found to have an unbroken continuous surface layer. When we contrast this with the fact that wire coated by the best method of the prior art is scarcely capable of being drawn through three dies without a break in this surface lubricating layer, the utility of my invention will be apparent. It will be seen that when the wire is coated with the metal lubricant according to my process the dies through which it is subsequently passed never come in direct surface contact with the steel wire. This results in a much longer die lire; for example, diamond dies drawing wire coated by the processes of the prior art from 21 to 33 gauge, will produce less than 1000 pounds of wire per finishing die. Artificial dies can not satisfactorily be used. On the other hand, diamond dies drawing substantially the same wire, treated by my process, to 33 gauge Wire will produce about 2000 pounds of wire per finishing die. Alloy dies may be used very satisfactorily with my invention and produce several thousand pounds of wire per finishing die. Because of the very high cost of 'these dies the increased production results in a very substantial saving, since a greatly increased quantity of wire is produced from each die and alloy dies of lower cost may be employed. I have found that by the use of my improved process the cost of drawing dies is reduced to about one-sixth of that where the old process is used.

Another very important advantage obtained from my improved process is the reduction in labor cost, plant space and plant equipment. When coating baths are prepared by the old method a number of mixing tanks, storage tanks and heating tanks are required to prepare the solutions. These are entirely eliminated by my process since the solutions are prepared directly in the treating tanks. Experienced workmen of some degree of skill are required to make the treatment according to the old process since much is left to the discretion of the workman. The treatment may be carried out by unskilled workmen where my process is employed because the baths are of indefinite duration and the operations of the workmen are purely mechanical.

another source of economy in my improved process is the elimination of the use of tin. Under the old process the cost of tin was about halt the cost of the materials used in treating the w re. This cost is entirely eliminated by my process. While a small amount of arsenic is employed my process which. was not employed in the prior the cost oi this material is negligible in comparison. with the cost of tin.

will he that the labor incident to the preparation oi": the coating solutions of the prior art is entirely eliminated. was necessary to dalre the tin, prepare the tin sulphate, ferment the flour coat: the rnirirture oi reagents. r any process the solutions are prepared in the cold and dissolved in the treating tanks the ocess being practically instantane-= ens, wiser by solutions be prepared with g the process.

ti'iough of less importance, the solutions used in my in" practically odorless. The as prior art, due to the fermented flour, have disagreeable odor, at times being almost un which clings to the workmen using the causing discomfort and embarrassnient.

i /"den wire is coated process it is ready to be drawn immediately as a result of which the coating and drawing operations may be continucue for mass production. I have thus eliminated the wide varieties of treatments formerly given to the wire between the coating and the drawing operations in the attempt to produce a more adherent and compact of copper or other metal upon the wire to protect the dies through which it is to pass.

While I have thus described a specific euibodiment of my invention I am. aware that numerous changes may be made therein without departing essentially from the spirit of the invention or the scope of the appended claims, in which- I claim:

i. The process of applying a metal lubricant to the surface of metal to be drawn comprising treating the metal with a solution containing an arsenic ion, and treating the metal with a second solution containing the ion of a metal. capable of precipitating upon the surface of the metal to be drawn, to form. a lubricating coating thereon.

2. The process of applying metal lubricants to the surface of metal to be drarm comprising cleaning the metal, treating the ferrous metal with a solution containing an arsenic ion, washing the metal, and treating the metal with a solution containing the ion of a metal capable oi being precipitated upon the surface of the metal, to be drawn to form a coating of improved lubricating properties.

3. The process of applying metal lubricants to the surface of ferrous wire to be drawn comprising cleaning the ferrous wire in a solution of hydrochloric acid, treating the ferrous wire with a solution containing a substantial concentration of chloride ions and an arsenic ion, washing the ferrous wire, and treating the ferrous wire with a solution containing ions of a metal softer than the metal to be drawn and capable of being replaced in solution by the iron of the ferrous wire, whereby the ions are precipitated upon the surface oi the ferrous wire to form a coating of improved lubricating properties.

4. The process of applying metal lubricants to the surface of ferrous metal to be drawn comprising cleaning the ferrous metal, treating the ferrous metal with a solution containing arsenic ions, washing the ferrous metal, and treating the ferrous metal with a solution containing ions of a metal softer than the metal to be drawn and of the ferrous metal whereby t" ns pare cipitated upon the suriace oi the .:cus metal. to form a coating of improved lubricatinF properties.

5. The process oi? applying metal lubricants to the surface of ferrous to be drawn comprising cleaning the ferrous wire in an acid solution. treating the famous with. a solution con taining arsenic ions, washing the "circus wire, and treating the ferrous wire with solution containing ions of a metal capable of being replaced in solution by the iron of the ferrous wire to form a coating or" improved lubricating prop erties.

6. The process of lubricutts to the surface of ferrous wire to d twn cor; 1d

of hydrochloric acid, treating the ferrous wire with a solution prepared by dissolving white arsenic in hydrochloric acid, washing the ferrous wire with water, and treating the ferrous wire with a water solution containing ions of a metal which is softer than the ferrous wire and capable of being replaced in solution by the iron of the ferrous wire whereby the ions are precipitated upon the surface of the ferrous wire to form a coating of improved lubricating properties.

8. The process of applying metal lubricants to the surface of ferrous metal to be drawn comprising cleaning the ferrous metal in an acid solution, treating the ferrous metal with a solution containing the negative ion of the cleaning solution and an ion which inhibits the replacement of copper by the iron of the ferrous metalfrom a solution containing a copper ion, washing the ferrous metal, and treating the ferrous metal with a solution containing ions of copper capable of being replaced in solution by the iron of the ferrous metal whereby copper ions are precipitated upon the surface of the ferrous metal to form a coating of improved lubricating properties.

9. The process of applying metal lubricants to the surface of ferrous metal to be drawn com- .prising cleaning the ferrous metal in a solution of hydrochloric acid, treating the ferrous metal with a solution containing a substantial concentration of chloride ions and ions which inhibits the replacement of copper by the-iron of the ferrous metal from a solution containing a copper ion, washing the ferrous metal, and treating the ferrous metal with a solution containing ions of copper capable of being replaced in solution by the ferrous metal whereby copperions are precipitated upon the surface of the ferrous metal to form a coating of improved lubricating properties.

10. The process of applying metal lubricants to the surface of ferrous metal to be drawn, comprising cleaning the ferrous metal, treating the ferrous metal with a solution containing arsenic ions, washing the ferrous metal, and treating the ferrous metal with a solution containing ions of copper capable of being replaced in solution by the iron of the ferrous metal whereby copper is precipitated upon the surface of the ferrous metal toiorm a coating of improved lubricating properties.

11. The process of applying metal lubricants to the surface of ferrous metal to be drawn comprising cleaning the ferrous metal in a water solution of hydrochloric acid, treating the ferrous metal with a solution prepared by dissolving white arsenic in hydrochloric acid; washing the ferrous metal with water, and treating the ferrous metal with a solution containing ions of copper capable of being replaced in solution by the iron of the ferrous metal whereby copper is precipitated upon the surface of the ferrous metal to form a coating of improved lubricating properties.

12. The process of applying metal lubricants to the surface of ferrous wire to be drawn comprising cleaning the wire in a water solution of hydrochloric acid, treating the wire with a solution prepared by dissolving white arsenic in hydrochloric acid, washing the wire, and treating the wire with a water solution of copper sulphate whereby the copper is replaced in its combination by the iron of the wire to precipitate copper upon the wire to form a coating of. improved lubricating properties.

13. The process of applying metal lubricants to the surface of metal to be drawn comprising treating the metal to be drawn with a solution containing the ion of antimony to precipitate this ion on the metal to drawn, and subsequently containing a copper ion capable of being replaced by the metallic constituent of the metal to be drawn, whereby the copper ion is precipitated upoon the surface of the metal to form a coating of improved lubricating properties.

15. The process of applying metal lubricants to the surface of metal to be drawn, comprising treating the metal to be drawn with a solution containing an ion of a metal taken from the group comprising arsenic, bismuth and antimony, and subsequently treating the metal to be drawn with 'a solution containing a copper ion capable of being replaced by the metallic constituent of the metal to be drawn whereby the copper ion is precipitated upon the surface of the .metal to be drawn to form a coating of improved lubricating properties.

RALPH F. COW.

res

Mill