US 3806453 A
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United States Patent 3,806,453 METAL WORKING LUBRICANT Ewell E. McDole, Danville, Calif., assignor to Kaiser Aluminum & Chemical Corporation, Oakland, Calif. No Drawing. Filed Feb. 23, 1973, Ser. No. 335,087 Int. Cl. Cm 3/34 US. Cl. 252-22 17 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a lubricant for metal Working, such as a forging, which contains a major portion of polybutene and minor portions of tin or lead soaps, a solid lubricant, such as graphite, and a dispersing agent. For hot forging, it is preferred to dilute the lubricant with kerosene or the like.
BACK-GROU ND This invention relates to the forging of metal products and, more specifically, is directed to a lubricant for the forging of light metal products.
Conventional press forging operations usually comprise at least two forging steps, namely, a blocking step which preforms the workpiece and provides the desired grain orientation and a finishing step which, as the name implies, provides the final desired finished shape. The finishing step may involve multiple forging strokes if the finished shape is complex. Generally, lubricant is applied to the dies and/ or workpiece before each forging stroke.
Heretofore, the forging lubricants were generally a mixture of graphite and a light oil carrier. Frequently, the mixture contained a metal soap to aid or assist in the lubrication. Although the conventional lubricants provided adequate lubrication for forging, they were characterized by the copious evolution of smoke and fumes. The emissions are a mixture primarily of thermal degradation products and unburned hydrocarbons. When forging complicated parts, where the die face has deep channels or complicated cavities, a large excess of lubricant was normally applied to insure that lubricant covered the entire die surface. However, this large excess of lubricant substantially increased the evolution of smoke and fumes which were already excessive. Attempts have been made to reduce the level of emissions by employing a lower viscosity oil carrier or to dilute the lubricant with kerosene or the like, in order to fiash off and burn the carrier rather than allowing the thermal degradation to occur with its resultant problem with emissions. However, this usually required employing a lower die temperature which increases the power requirements for the forging operations, aggravates the problem of the workpiece sticking to the die, and significantly reduces die life, particularly when complex die surfaces are involved.
Against this background, the present invention was developed.
DESCRIPTION OF THE INVENTION The lubricant of the present invention comprises a carrier fluid of polybutene, a solid lubricant, a tin or lead soap and a dispersing agent. Other additives can be included, such as antioxidants or additional lubricity agents. The base lubricant comprises from about 50-90%, preferably 65-90%, by weight polybutene, from about 230%, preferably 3-10%, by weight solid lubricant, from about 05-10%, preferably 2-10% by weight lead or tin soap and from about 05-10%, preferably 2-8%, by weight of a dispersing agent. The base lubricant can be applied directly to the die or workpiece surfaces, but preferably the lubricant is diluted with a light hydrocarbon liquid with a low flash point, such as kerosene, diesel oil or stove oil. Dilutions can be up to one part base lubricant to ten 3,806,453 Patented Apr. 23, 1974 parts diluent (by weight), but, preferably, the dilutions range from about 1:05 to 1:5 (by weight).
Except for the solid lubricant, the various components of the base lubricant must be soluble in the polybutene. In preparing the lubricant, the soluble components are first dissolved in the polybutene. The material may be heated slightly, e.g., up to 170 F., to facilitate the mixing and dissolving of the various components in the polybutene. The solid lubricant usually is not added until just before the lubricant is to be used because the solid lubri cant has a tendency to settle out. Conventional methods of applying the lubricant can be used, such as spraying or swabbing.
The lubricant of the present invention when applied to the hot surfaces of the workpiece or die readily wets and spreads on the hot metal surfaces even if residual lubricant is on the surfaces from prior operations. During forging operation, there is little or substantially no visible emissions or hydrocarbon emissions because the lubricant of the present invention flashes quickly and burns cleanly. Moreover, due to the excellent lubricating properties of the present invention, significantly less lubricant need be applied for metal working operations. No significant buildup in the die is noticeable because the lubricant tends to remove and disperse within the lubricant any residue left on the die surfaces.
The function of the dispersing agent is to insure that the solid lubricant remains uniformly dispersed throughout the lubricant as the lubricant spreads and dries on the hot surface. This function is readily determined by placing a drop of the lubricant containing graphite as the solid lubricant on a hot metal surface (i.e., 500 F.). The color of the dried residue will be uniformly black if the function is properly performed. If the graphite is not properly dispersed, the color of the residue on the surface will not be uniformly black, and will have a multicolored ring around the edges of the dark residue. Suitable organic dispersing agents include polyamino alkenyl succinimide, calcium salts of an alkyl or alkene substituted salicyclic or succinic acid wherein the substituted portion has from 10-30 carbon atoms, and calcium and barium salts of naphthenic acids and long chain aliphatic sulfonic acids having from 10-30 carbon atoms.
The polybutene preferably has a viscosity from about to 100,000 SSU at 100 F. (an average molecular weight of about 300 to 1200). Generally, the higher the metal working temperatures, the higher the viscosity of the polybutene should be. In the hot forging of light metal products, such as aluminum, wherein the die temperature is about 500-650 F. and the workpiece temperature is from about 700-900 F., a polybutene having a viscosity from about 500-5000 SSU at 100 F. has been found adequate. With higher metal working temperatures, correspondingly higher viscosity polybutene should be used. Particularly suitable polybutenes include Polybutene Nos. 8 through 16 manufactured by the Chevron Chemical Company. Typical properties of suitable polybutenes are given in the table below.
Typical properties of polybutene Specific gravity 0.85-0.91 Viscosity at 100 F., SSU 100-100,000
Flash point F.) 250-480 Fire point F.) 290-560 Bromine number, g./100 g. 15-45 Neut. number, mg. KOH/g. 0.01 Carbon residue, percent None The solid lubricant is preferably graphite, although other solid lubricants, such as molybdenum disulfide and boron nitride can be employed with the present invention. The solid lubricant can be in powder or flake form but should have a particle size less than 200 mesh.
The lead and tin soaps of the present invention, which function as lubricity agents, preferably are the lead and tin salts of saturated or unsaturated fatty acids having from -30 carbon atoms and the lead and tin salts of naphthenic acids. The most useful soaps are lead naphthenate and stannous oleate. Other metallic soaps, such as aluminum, zinc and magnesium soap, were found detrimental to the forging operation.
In addition to the lead or tin soaps, other lubricity agents can be added, such as synthetic sperm oil and epoxidized soybean oil. Examples of the latter two are respectively P & G Continuous Casting Lubricant #6 manufactured by the Proctor and Gamble Corporation and Paraplex G-62 manufactured by the Rohm & Haas Company. Other lubricants include lanolin, fatty acids, fatty alcohols, fatty acid esters and the like. These additive lubricity agents must not, however, interfere with the spreading characteristics of the base lubricant, they should be thermally stable, and they should not significantly interfere with the ability of the base lubricant to remove and disperse within the lubricant any residue left on the die surface. Other additives, such as antioxidants, can also be used. As mentioned previously, the various components must be soluble in the polybutene.
The following examples are given to illustrate the lubricant of the present invention:
The above lubricants were diluted 1:1 (by weight) with kerosene and employed in the hot forging of aluminum automotive wheel hubs. Die temperature was about 650 F. and workpiece lay on temperature was about 800 F. The lubricant was sprayed onto the die surfaces for both blocking and finishing operations. Little or no build-up of residue was noticeable on the dies and no problems were found with the workpiece sticking to the dies. The lubricant was found to flash quickly and burn cleanly, resulting in little or no smoke and essentially no hydrocarbon emissions. In the finishing operations, which required two forging strokes, it was found that only one application of lubricant was needed. As a comparison, when using conventional lubricants in the aforesaid forging operation, the application of lubricant was necessary for each finishing stroke.
In the above examples, the dispersing agent was OLOA 1200 manufactured by the Chevron Chemical Company. The synthetic sperm oil was P & G Continuous Casting Lubricant #6 manufactured by the Proctor and Gamble Company. The antioxidant was Ethyl Antioxidant #702 manufactured by the Ethyl Corporation. The polybutene was Polybutene 12 manufactured by the Chevron Chemical Company. The epoxidized soybean oil was Paraplex G-62 manufactured by the Rohm & Haas Company. The graphite was an airspun graphite, #200-10 manufactured by The Joseph Dixon Crucible Co. (average particle size 2.5 microns, specific surface 11.5 m. /gb.).
Although the above invention has been more specifically described in terms of hot working and, in particular, hot
forging of light metal products, such as aluminum, the base lubricant can also be used in cold forging operations, in which case, it may be desirable to use water as the diluent material. If water is used, the addition of an emulsifier may be required so as to emulsify the oil base constituents in the water. Suitable emulsifiers include water-miscible soaps, such as triethanolamineoleate, sodium soaps of tallow and/ or one or more of the commonly used nonionic emulsifiers useful for making oil-in-water emulsions. Moreover, the lubricant can be used in other metal working operations where relatively viscous, solid lubricant containing lubricants are employed, such as in tube and rod drawing.
It is obvious that various improvements and modifications can be made to the present invention without departing from the spirit of the invention or the scope of the appended claims.
What is claimed is:
1. A metal working lubricant comprising from about 50-90% by weight polybutene having a molecular weight from about 300 to about 1200, from about 2-30% by weight solid lubricant selected from the group consisting of graphite, molybdenum disulfide and boron nitride, from about 05-10% by weight of a metallic soap selected from the group consisting of lead soaps and tin soaps and from about 05-10% of an organic dispersing agent.
2. The lubricant of claim 1 wherein said polybutene has a viscosity from about IOU-100,000 SSU at F.
3. The lubricant of claim 1 wherein said polybutene has a viscosity from about 500-5000 SSU at 100 F.
4. The lubricant of claim 1 wherein said solid lubricant is graphite having a particle size less than 200 mesh.
5. The lubricant of claim 1 wherein said lead soap is selected from the group consisting of lead salts of fatty acids having from 10-30 carbon atoms and lead salts of naphthenic acids.
6. The lubricant of claim 1 wherein said tin soap is selected from the group consisting of tin salts of fatty acids having from 1-0-30 carbon atoms and tin salts of naphthenic acid.
7. The lubricant of claim 1 wherein said soap is selected from the group consisting of lead naphthenate and stannous oleate.
8. The lubricant of claim 1 containing a minor amount of a lubricity agent selected from the group consisting of synthetic sperm oil and epoxidized soybean oil.
9. The lubricant of claim 1 diluted with a diluent selected from the group consisting of kerosene, stove oil and diesel oil in amounts up to 1 part lubricant to 10 parts diluent by weight.
10. The lubricant of claim 1 comprising from about 65-90% by weight polybutene, from about 3-10% by weight solid lubricant, from about 2-10% by weight metallic soap and from about 2-8% by weight dispersing agent.
11. The lubricant of claim 1 wherein the lubricant is diluted with said diluent in amounts from about 1:05 to 1:5 by weight.
12. The lubricant of claim 1 wherein said dispersing agent is selected from the group consisting of a polyamino alkenyl succinimide, calcium salts of an alkyl or alkene substituted salicylic acid wherein said alkyl or alkene group has from 10-30 carbon atoms, calcium salts of an alkyl or alkene substituted succinic acid, calcium salts of naphthenic acid, calcium salts of long chain sulfonic acids having from 10-30 carbon atoms, barium salts of naphthenic acids and barium salts of long chain sulfonic acids having from 10-30 carbon atoms.
13. The lubricant of claim 1 containing an emulsifier selected from the group consisting of water miscible soaps and nonionic emulsifiers and emulsified in water.
14. In the method of forging metal products wherein a workpiece is placed on a die surface and pressure is applied to said workpiece so as to deform same into the die cavity, the improvement comprising applying to the surfaces of said workpiece or said die a lubricant comprising from about 50-90% by weight polybutene having a molecular weight from 300 to about 1200, from about 230% by weight solid lubricant selected from the group consisting of graphite, molybdenum disulfide and boron nitride, from about 05-10% by weight of a metallic soap selected from the group consisting of lead soaps and tin soaps and from about 05-10% of an organic dispersing agent.
15. The method of claim 14 wherein said lubricant is diluted with a diluent selected from the group consisting of kerosene, stove oil and diesel oil in amounts up to 1 part lubricant to 10 parts diluent by weight.
16. The method of claim 15 wherein the lubricant is diluted with said diluent in amounts from about 1:0.5 to 1:5 by weight.
17. The method of claim 14 wherein said metal is aluminum.
References Cited UNITED STATES PATENTS DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner US. Cl. X.R.