US3390570A - Method for applying lubricant - Google Patents

Description

3,390,570 METHOD FOR APPLYING LUBRICANT Dennis B. Freeman, Harrow, and Vernon P. Simpson,

Andover, England, assignors to Hooker Chemical Corg nration, Niagara Falls, N.Y., a corporation of New ork No Drawing. Filed Sept. 21, 1964, Ser. No. 398,095 Claims priority, application Great Britain, Sept. 23, 1963, 37,336/63 10 Claims. (Cl. 72-43) ABSTRACT F THE DISCLOSURE A method for applying a lubricant coating, suitable for use in metal deforming operations, to a metal surface, wherein a lubricant made up of an aqueous dispersion of a fatty acid and a nitrogenous base which is capable of forming a soap with the fatty acid is applied to the metal surface by immersing the surface in the aqueous dispersion and passing an electric current through the dispersion between a cathode and the surface to be coated until the desired lubricant coating is formed on the metal surface. Preferably, the nitrogenous base is ammonia, the fatty acid is stearic acid and the current density used is within the range of about 1 to 50 amperes per square foot.

This invention relates to an improved method for applying a lubricant composition to a metal surface and more particularly it relates to an improved process for the application of a soap-type lubricant to a metal surface which is to be deformed.

In the art of the cold forming of metals, e.g., metal deformation or metal drawing, it is customary to provide a lubricant coating on the metal surface which is to be deformed. Such lubricant coatings assist the passage of the metal through the apparatus in which it is being worked, as for example a wire drawing die, thus making it possible to achieve a greater deformation of the metal surface at higher rates of travel for the surface, with a minimum of wear on the drawing or forming dies, while still maintaining a relatively smooth metal surface after the deformation. Typical lubricants which have been used for this purpose are the various long chain fatty acid soaps and mineral oils. Additionally, in some instances, it is common to provide a chemical coating on the metal surface to be deformed such as a phosphate coating, an oxalate coating, a sulfide coating or the like, prior to the application of the soap or oil lubricating material.

Generally, the lubricant compositions may be applied in a variety of Ways, such as by immersion, flow coating, spraying, roller application, and the like. Additionally, in some applications, such as wire drawing, use has been made of so-called forced lubrication techniques Wherein the metal surfaces to be deformed are contacted with the lubricant material under pressure Within the deformation die itself. Although, for the most part, such applications have provided a lubricant coating on the surface to be deformed, the coatings produced have not always been sutficiently adherent to the metal surface to provide the desired lubrication in many metal deforming operations. This has been particularly true in those operations where it is desired to effect an extreme deformation of the metal surface in a relatively short period of time, as in high speed wire drawing operations. Because of this lack of adhesion of the lubricant composition to the metal surface, siezing or galling of the surface in the deforming dies has been common, thus causing a reduction in the speed at which the drawing operation is carried out and often resulting in greatly shortened die life.

It is, therefore, an object of the present invention to fit States Pat 0 Patented July 2, 1968 provide an improved method for applying lubricant compositions to metal surfaces to be deformed.

A further object of the present invention is to provide an improved method for the deformation of metal surfaces.

These and other objects will become apparent to those skilled in the art from the description of the invention which follows.

Pursuant to the above objects, the present invention includes a method for preparing a metal surface for a deforming operation, which method comprises forming an aqueous dispersion of a fatty acid and an excess of a nitrogeneous base capable of forming a soap with the fatty acid, the fatty acid being at least partially combined with the base, immersing the surface to be deformed in the thus-formed dispersion, effecting formation of a lubricant coating of the soap on the surface by passing an electric current through the dispersion between a cathode and the surface to be coated, and continuing the passage of the current until the desired coating is formed on the metal surface. In this manner, there is deposited, electrophoretically, a very adherent lubricant coating on the surface of the metal to be deformed, which coating has been found to provide improved lubrication during a subsequent metal deforming operation.

More specifically, in the practice of the method of the present invention, an aqueous dispersion is formed of a fatty acid. Typical of the fatty acids which may be used are those containing from about 8 to about 22 carbon atoms, with those containing about 12 to about 18 carbon atoms being preferred. Exemplary of specific preferred fatty acids are stearic acid, myristic acid, oleic acid and palmitic acid. Additional, mixture of fatty acids may also be used. To the aqueous dispersion of the fatty acid, there is added a nitrogenous base which is capable of forming a soap with the fatty acid. Exemplary of the nitrogenous bases which may be used are ammonia and amines, including alkyl amines having from one to about 10 carbon atoms, alkanol amines having from about one to about 10 carbon atoms, cyclic amines having from about 5 to about 12 carbon atoms, aryl and diaryl amines having from about 6 to about 15 carbon atoms, dialkyl and dialkanol amines having from about 2 to about 20 carbon atoms, trialkyl and trialkanol amines having from about 3 to about 30 carbon atoms, arylalkyl amines having from 7 to about 20 carbon atoms, diamines having from about 1 to about 10 carbon atoms, and the like. Typical specific amines withing these groups which may be used are ethylene diamine triethanolamine, triisopropylamine, diethylamine, tripropanolamine, tributylamine, lmethylamine, ethylamine, propylamine, octylamine, decylamine, ethanolamine, propanolamine, monoisopropanolamine, cyclopentylamine, cyclohexylamine, dimethylamine, di' ethylamine, dibutylamine, diamylamine, dioctylamine, didecylamine, methylethylamine, ethylbutylamine, morpholine, pipericline, cyclohexylmethylamine, cyclopentyl, ethylamine, diphenylamine, ditoluylamine, methylphenylamine, octylphenylamine, diethanolamine, di-butanolamine, dioctanolamine, dimethylethanolamine, isopropanolethanolamine, ethylethanolamine, butylethanolamine, octylethanolamine, methylisopropanolamine, ethylbutanolamine, phenylamine, toluylamine, naphthalamine, Z-amino-Z-methyl-l-propanol, 2-amino-2-methyl- 1,3-propanediol, Z-amino-Z-ethyl-l,3-propanediol and the like. As with the fatty acid, mixtures of amines or of ammonia and one or more amines may be used.

The relative amounts of the fatty acid and the nitrogenous base in the aqueous dispersion formed may vary over a wide range, although dispersions containing the fatty acid, either free or combined, in an amount of at least 20 grams per liter are preferred. It has been found that in order to obtain a satisfactory lubricant composition, it is desirable that the nitrogenous base be present in an amount at least equivalent to the stoichiometric amount required to react with all of the fatty acid, and preferably in excess of this amount. It has been found to be preferable that the aqueous dispersion formed contain the fatty acid and the nitrogenous base in amounts such that the resulting dispersion contains the resulting lubricant material in an amount within the range of about 2 to about 50 percent by weight of the dispersion, with amounts of lubricant material within the range of about to about 15 percent by weight of the dispersion being specifically preferred. Generally, it has been found to be desirable if the pH of the dispersion is at least 8. Additionally, in some instances, it has been found to be advantageous to include oxalic acid and/or a phosphate in the dispersions.

Once the aqueous dispersion of the lubricant material has been formed, the metal surface to be deformed is then immersed in the dispersion. Metal surfaces which may be coated are those which may be made the anode in the electrical system, such as iron, zinc, copper, aluminum, nickel and the like. Electrocoating of the lubricant material on this metal surface is effected by passing an electric current through the dispersion. In effecting this electrocoating, the surface to be deformed which is immersed in the lubricant dispersion is made the anode in the electrical system and the current is passed through the dispersion, between a cathode and this anode. Typically, the current density used is within the range of about 1 to about 50 amperes per square foot with current densities within the range of about 2 to about amperes per square foot being preferred. The potential difference between the anode and cathode in this system may also vary widely, with potential differences within the range of about 1 to about 50 volts being typical. The passage of the electric current through the dispersion between the cathode and the anode, which is the surface to be coated, is continued for a period of time which is sufficient to obtain the desired coating on the metal surface. Coating times within the range of about seconds to about 5 minutes have been found to be typical in many instances.

After the desired lubricant film has been formed on the metal surface, the surface is removed from the lubricant dispersion and rinsed in water so as to remove any unbound lubricant from the surface. Thereafter, the lubricant film on the metal surface is dried and the surface is then subjected to any of the various metal deforming operations, such as cold forming, wire drawing, and the like. The details of such cold forming operation and the manner in which they are carried out are sufficiently well known to those in the art that a further description of them is not deemed to be necessary.

In carrying out the electrocoating of the metal surfaces with the aqueous lubricant dispersion various techniques may be used. Generally, it has been found that it is most convenient if the lubricant dispersion is maintained in a steel, or similarly conductive container, which container is then made the cathode in the electrical circuit. The coating process may be carried out as a batch process wherein the metal surfaces to be coated, such as sheets, rods, etc., are immersed in the lubricant composition and made the anode in the electrical circuit and are then withdrawn from the dispersion when the desired coating has been effected. Alternatively, in some instances, as for example in a wire drawing operation, the wire to be drawn may be passed continuously through the lubricant dispersion, the electrical contacts being made with the wire as it passed through the dispersion, so that the wire is continuously electrocoated with the lubricant and is then passed directly into the wire drawing die. It is believed that those in the art will be able to determine the best mode of effecting the electrocoa 'ng of the metal surface to be deformed with the lubricant material in each instance.

if desired, prior to the time the metal surface to be deformed is coated with the lubricant material, a chef ZiCZIl coating may first be placed on the surface, such as a phosphate coating, an oxalate coating, an oxide coating, a sulfide coating or the like. Such chemical coatings are conventional and are known to those in the art and may be applied to the metal surfaces to be deformed in any convenient manner, as for example by spraying, immersion, roll coating, and the like. It is to be appreciated that where reference has been made to forming an aqueous dispersion of a fatty acid and a nitrogenous base which is capable of forming a soap with the fatty acid, it is in tended to refer to such a dispersion which contains the fatty acid and the nitrogenous base as such, as well as one in which these materials have reacted to form a fatty acid soap. Similarly, where reference is made to effecting the coating of the surface to be deformed with the acidic and basic components of this dispersion, it is intended to include the case where these components, as such, are deposited on the metal surfaces as well as when the fatty acid soap which results from the reaction of these materials is deposited on the surface.

In order that those in the art may better understand the present invention and the manner in which it may be practiced, the following examples are given. In these examples, unless otherwise indicated, temperatures are in degrees centigrade and amounts are in grams.

Example 1 grams of stearic acid and 12 grams of an ammonia solution having a specific gravity of 0.88 were admixed with 918 grams of water, at a temperature of 50 degrees until a viscous opaque liquid is obtained. This aqueous lubricant dispersion was maintained in a steel container and steel panels were then immersed in the lubricant dispersion. The panels were made the anode and the steel container the cathode and an electrical current was passed through the lubricant dispersion at a current density of 4 amperes per square foot and a potential difference of 15 volts for a period of about 13 seconds. The steel panels were then removed from the lubricant dispersion and were found to be coated with an electrodeposited lubricant film. This film was then washed in water to remove any unbound lubricant, the electrodeposited portion of the film remaining tightly adherent and insoluble during this washing. The film was then dried in air, and there was obtained on the surface of the steel panel a substantially uniform lubricant coating which was suitable for protecting the metal during a relatively severe deforming operation.

Example 2 The procedure of the preceding example was repeated by passing a steel wire through the lubricant dispersion as the anode in the electrical system. After removing the wire with the electrodeposited film from the lubricant dis persion, and washing and drying the lubricant film as in the preceding example, the wire was passed through a drawing die. The lubricant film on the wire exhibited appreciably greater adhesion during the drawing operation than conventionally applied soap lubricants and the wire retained a dark even lubricant film throughout the drawing operation.

Example 3 The procedure of the preceding example was repeated using a panel of an alloy of percent nickel and 20 percent chromium as the anode in the electrocoating system. Here again there was formed on the panel a substantially uniform lubricant coating which was suitable for protecting the metal during relatively severe drawing operation.

The procedure of the preceding examples are repeated using other fatty acids, including palmitic acid, myristic acid. olcic acid, and the like; other nitrogenous bases, including tricthanolaminc, cthyluminc, cyclohexylamine, morpholine, phcnylamine, decylamine, and the like; in

forming the lubricant dispersion; and applying the lubricant over a chemical coating, to obtain similar results.

Example 4 By way of comparison, a percent solution of sodium stearate was placed in a stainless steel container and connected as the cathode to a source of direct current. Panels of mild steel were immersed in the solution and connected as the anode. Under a potential difference of 3 volts and using a current density of 9 amps/square foot, a gray to gray-black soap film was produced on the steel surface in one minute. These panels were stored with panels produced as in the preceding examples and it was found that in a short time the coating on the panels of this example were oxidized to a fine rust while the coatings on the panels of the other examples retained their initial appearance.

While there have been described various embodiments of the invention, the compositions and methods described are not intended to be understood as limiting the scope of the invention as it is to be understood that changes therewithin are possible and it is intended that each element recited in any of the following claims is understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same manner, it being intended to cover the invention broadly in whatever form its principle may be utilized.

What is claimed is:

'1. A method of preparing a metal surface for a deforming operation which comprises forming an aqueous dispersion of a fatty acid and an excess of a nitrogenous base capable of forming a soap with the fatty acid, the fatty acid being at least partially combined with the base, and being present in an amount of at least grams per liter, the resulting dispersion having a pH of at least 8, immersing the surface to be deformed in the thus-formed dispersion, effecting formation of a lubricant coating on said surface by passing an electric current through the dispersion between a cathode and the surface to be coated, the current density used being within the range of about 1 to 50 amperes per square foot, continuing passage of said current until the desired coating is formed on the metal surface and thereafter, drying the thus-formed coating on the metal surface.

2. The method as claimed in claim 1 wherein the fatty acid contains from about 8 to about 22 carbon atoms and the nitrogenous base is selected from the group consisting of ammonia and amines capable of forming a soap with the fatty acid.

3. The method as claimed in claim 2 wtherein the nitrogenous base is ammonia.

4. The method as claimed in claim 3 wherein the fatty acid is stearic acid.

5. A method of deforming a metal surface which comprises forming an aqueous dispersion of a fatty acid and an excess of a nitrogenous base capable of forming a soap with the fatty acid, the fatty acid being at least partially combined with the base, and being present in an amount of at least 20 grams per liter, the resulting dispersion having a pH of at least 8, immersing the surface to be deformed in the thus-formed dispersion, effecting formation of a lubricant coating on said surface by passing an electric current through the dispersion between a cathode and the surface to be coated, the current density used being within the range of about 1 to amperes per square foot, continuing passage of said current until the desired coating is formed on the metal surface, drying the coating thus-obtained and, there-after, deforming the thuscoated metal surface.

'6. The method as claimed in claim 5 wherein the fatty acid contains from about 8 to about 22 carbon atoms and the nitrogenous base is selected from the group consisting of ammonia and amines capable of forming a soap with the fatty acid.

7. The method as claimed in claim 6 wherein the nitrogenous base is ammonia.

8. The method as claimed in claim 7 wherein the fatty acid is stearic acid.

'9. The method as claimed in claim 8 wherein prior to immersing the surface to be deformed in the dispersion of the fatty acid and nitrogenous base, a chemical coating is applied to the metal surface.

'10. A metal surface having a lubricant coating thereon produced in accordance with the method of claim 1.

References Cited UNITED STATES PATENTS 1,995,528 3/1932 Williams 72-43 2,763,054 9/ 1956 'Wojtowicz 29-424 2,825,693 3/l958 Beaubien et al. 252493 2,966,391 12/1960 Kubie 72-42 CHARLES W. LANHA-M, Primary Examiner.

E. M. COMBS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,390,570 July 2, 1968 Dennis B. Freeman et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 48, an oxalate," should read an oxide, an oxalate, Column 2, line 13, "nitrogeneous" should read nitrogenous line 34, "Additional, mixture" should read Additionally, mixtures line 49, "withing" should read within Signed and sealed this 10th day of March 1970.

(SEAL) fittest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer