CA1086576A - Method and apparatus for applying lubricating materials to metallic substrates - Google Patents

Abstract

A B S T R A C T
A new article of manufacture formed by a new method and apparatus for generating and substantially uniformly electrostatically dispersing a very finely divided spheroidally shaped lubricating particles onto the moving surface of metal or other electrically con-ducting substrate. A lubricant material in its liquid state is drawn by airflow through a small venturi orifice where it is sheared into droplet of various sizes. Larger droplets are filtered out of the continuing post-venturi airflow by gravity, baffles, airflow forces and/or inertia effects, leaving only a mist cloud of extremely small spheroid particles which are then migrated within a charged plasma so as to transfer electrical charge thereto in sufficient quantities to achieve a desired uniform high charge/mass ratio and thus insure a uniform eventual electrostatic dispersion of substantially all the spheroids over the substrate surface. The mist cloud is controll-ably generated for each of a plurality of longitudinal sections of the substrate and permitted to drift or migrate relatively slowly between transversely positioned electrodes and the conducting substrate spaced therefrom in respectively corresponding longitudinally partitioned sections of a non-conducting enclosure. A corona discharge is maintained by a voltage differential between the electro-des and the substrate to form an electrically charged plasma within the non-conducting enclosure, which in turn, multiply bombards and charges the individual particles of the slowly migrating mist cloud. Thusly charged to uniform charged states, the particles are then uniformly dispersed substantially only by electrostatic forces onto the surface of the longitudinally moving substrate. The percentage coverage of the tiny lubricating spheres on the conducting substrate surface is dependent only upon the quantity of such particles migrating into the part-itioned enclosure and the relative velocity (and hence dwell time within the enclosure) of the conducting sub-strate. The coverage is substantially uniform because of substantially uniform charge/mass ratios provided; because of the controlled uniform supply of the particles across a transverse dimension of the substrate and because the longitudinally partitioned non-conducting enclosure prevents non-random movement of the tiny spheres as they enter the partitioned enclosure and prevents any tend-ency to deposit the charged particles on the enclosure surfaces rather than on the substrate, per se.

Description

~lO15 ~S76 The present invention relates to an improved method and apparatus for electrostatically uniformly dispersing tiny spheroids of a lubricatiny material onto a conducting substrate, and to the resulting product.
In the production of metal cans and other articles of manufacture, it is often necessary to provide slight amounts of lubrication material upon the surface of metal stock (e.g. sheets, strips, etc.) before storing the metal, ~ ;~subjecting the metal stock to further forming operations, such as passing the stock through various forming dies or for other reasons. Failure to apply lubrication prior to such forming operations results in severe scraping and ;
galling of the dies, rendering them useless for continued service. In addition, failure to apply lubrication often results in deformed and defective finished articles for other reasons as known in the art. Also, as metallic sur-~; faces are often processed with suitable ornamental effects, it is frequently desirable to provide the decorated metallic ~-surface with lubrication immediatley following the surface decroating process. Here again lubrication is required to enable the manufacturer to pass the decorated sheet or material through forming dies to punch and form the material without galling the dies or causing defective materials to -be produced, etc. In all cases it is necessary to apply a ~-fairly controlled amount of lubrication and to attempt to uniformly distribute it on the metal surfaces since exces~
sive and/or uneven lubrication can and often does give rise to its own attendant problems as is also well kno~n in the art. For instance, excessive wax lubrication nQt only wastes materials, it may accumulate on forming die surfaces ~86S~
and/or tend to "tack" or "weld" lubricated stock together upon mutual contact.
In the past the most conventional method of apply-ing lubrication upon common metallic surfaces in the form of flat sheets, strips, etc., was simply to pass the material through a solvent bath saturated with oryanic lubricating compositions. Upon emerging from the bath, the solvent is permitted to evaporate thus leaving the organic lubricating composition as a thin film upon the metallic surface. Major disadvantages of this conventional procedure are the apparent hazardous and often toxic situations due to solvent fumes in the vicinity of such an opexation as well as the considerable expense of supplying large quantities of solvent material, preparing and applying the solvent solution, as well as other related disadvantages as known in the art.
Accordingly, there have been repeated attempts to `
improve on the conventional solvent bath technique. However, for a great variety of reasons, æuch attempts have hereto-fore met with eventual failuxe when put to the practical --~ 20 test o~ actual- operating conditions with the result that -~ lubriaation of such metal substrates today is still~primarily achieved via the costly and hazardous solvent bath technique and/ox with other less aostly or less hazardous attempts which usually fail to provide the desired lubrication applica-tion.
Now, with the discovexy of this invention, it is possible to achieve a form of lubricated metal substrate not ~ ~
heretofore possible through method and apparatus which is ~ -cheap and inherently safe over prior techniques while at the same time providing superior lubrication results. Cleaner .

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die suraces are maintained, less lubrication material per unit area is required and the tack or weld or weld tendency of lubricated stock is reduced.
A great number of prior atte~ t~ have been made to S harness electrostatic deposltion techni(lu~s for applying the necessary lubricant to the metal substrate. Some metal manufacturing facilities are known to have made costly in-vestmentq in electrostatic apparatus purportedly designed for the purpose of applying lubrication to metal substrates only to abandon same in favor of the more conventional sol~
vent bath or direct spraying techniques and/or to conclude that the "electrostatic" lubricator appeared to work about as well with the electrostatics turned off as when the electrostatics was turned on.
Evaluating the known prior electrostatic lub-ricator attempts in light of our present discoveries it appears that quch prior attempts did not properly consider the detailed physical and electrical processes being attempt ed and have not properly provided a suitable method and apparatus aapable of fully facilitating same.
Of course, as is well known, the general object of electrostatic deposition or precipitation i8 to charge ~; moblle particles with an elctrical polarity opposite that of a conducting collector electrode to which the mobile particles are therefore attracted by the well known electro~
static forces of attraction between opposite electrical charges.
Many of the prior electrostatic lubrication ; attempts have generally tried to achieve this desired end -b~:
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(1) generating a 9upply of lubrication particles often of such large size that signi.ficant gravity forces influence particle movement and/or that ap~lication would result in local excesses of lubricant;

(2) physically propell.ing the particles at a significant velocity through an ionization zone between two charged electrodes such that not all particles became charged or at least not all became uniformly charged; -

(3) physically propelling the thus hopefully charged particles towards a vertically moving metal strip or the like in an enclosecl vertically rising metal housing (usually grounded to same potential as the metal strip) which may or may not include some electrical insulator there~
within in addition to an ambient air; and

(4) providing a secondary upwardly ~irected air :
flow .supply or depending upon so called "windage" effec~s, etc. to carry the still unattached hopefully charged par- -~ticles vertically upward into an extensive deposition zone where "repeller" electrodes charged to the same polarity as the particles create an electr~cal ~ield designed to force the particles ~if aharged) toward the metal strip~
Such prior apparatus has been characterized by it~
excessive height, its exces~ive weight and its inability to ~;
perform as anticipated in a practical manufacturing environ-ment. The present invention has proven capable of very successful practical performance in an actual manufacturing environment. While all the reasons for this noted sucaess may not yet be known or fully appreciated, it i9 presently believed that the following attribute~s of our invention are important in varying degrees to its noted improved

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performance:
(1) method and apparatus is provided for forming substantially uniform liquid lubrication particles, the majority of which are uniformly sized ~o have an average :
diameter on the order of one micron to insure that the re~
sulting mi~t cloud of particles (spheroids due to liquid : surface tension) i8 completely airborne with resulting particle movements that are substantially independent of any gravity forces acting thereon; :
~2) a completely non-electrically conducting ~
enclosure is provide,d to substantially eliminate any electro- ' ; static forces tending to attract lubrication paticles towards the enclosure walls rathe.r than towards the conducting 5ub-strate as desired;:
(3) a charged plasma of ambient gaseous molecules .
': if maintained within the non-conducting enclosure by impres-sing a high voltage difference between electrodes therein ~:~
and the conductive substrate of metal rather than between '~.
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two sets of electrodes;
(4) the airborne mist cloud of spheroids is ~ :
allowed to migrate or drift into'the plasma area where , multiple ion collisions charge the relatlvely larger spher~
` oids in a relatively slow charging process whiah, as it ~' '; approaches a steady state condition, vill eventually impart sub~tantially uniform maximum electrioal charges on all the available uniformly sized ~pheroids whiah are thereafter uniformly attracted towards and uniformly dispersed upon the ,~ metal substrate;
: ~S) since this process is substantially lO0~ effi-cient in s~eady statP, the percentage coverage of the metal :., .-~ , . .
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surface is determined primarily only by the quantity of spheroids supplied to the plasma and the rate of movement of the metal substrate (hence its dwell time within the non-conducting coating chamber);

(6) the non-conclucting coating chamber is dividsd into longitudinal sections to control the uniformity of coverage transversely across the metal substrate;

(7) individually controllable particle generators are associated with each such longitudinal section and special transversely extending channel conduits are utilized ~or communicating between the particle generators and the coating chamber sections; and

(8) complete lubricant film coverage of the metal substrate is not attempted but, rather, only a uniform dis-persement of lubricant spheroids thereover;
(9~ many other features as will be apparent rom the description hereinbelow.
There are, of course, still many further indica-tions of difference between our invention and the prior electrostatic lubrication attempts as will occur to those in the art. For example, all known prior electrostatic lubri-cation application attempts have been constrained to apply same with the metal strip in a vertical orientation. It appears that such vertical orientation was considered neces-sary, inter alia, because it was necessary to use gravity ~;
~orce~ to collect excess lubrication materials and to return same to the particle generator for reuse. However, with this invention, no special orientation of the metal strip is necessary. In fact, the present preferred exemplarly embodiment described below happens to utilize a horizontal '". ' ~U186576 orientation of the metal substrate!
None o~ the prior known attempts to lubricate a moving metal strip, sheet or the like using electrostatic precipitation are believed to have ac~ually achieved a uniform substantially random dispersion of minute lubricant particles to conductive substrates in a practical highly eEficient manner in actual production line environments. Nor have any of the prior attempts provided precipitating apparatus for this purpose of such simple and economical design as that to be described herein.
It therefore is an object of this invention to provide an improved method and apparatus for applying lubricating material uniformly and efficiently onto a metallic substrate such as sheets, strips, etc.
Accordingly, this invention relates to a method for uniformly electrostatically dispersing lubrication particles onto a conductive substrate.
` Thus according to the present invention, there is provided a method for electrostatically and uniformly dispersing particles of lubricating material upon an electrically conductive substrate comprising the steps of:
supplying to a confined space adjacent said substrate a quantity of small, randomly moving, substantially spheroidal particles of dielectric lubricating material to form a cloud of said particles; and electrostatically charging said particles by ioni~ation to form a quiescent cloud of charged particles which are disposited upon the substrate, the charged particles being in repelling relationship to one another.
In another aspect, the invention provides a new article of manufacture comprising: a metal substrate having at least one electrically conduc~ive surface; and substantially uniformly dispersed spaced discrete particles of dielectric lubricating material spaced apart and uniformly ; distributed over said at least one surface.
In an exemplarly embodiment, a lubricant, which is preferably solid at room temperature, is heated to form a liquid. The liquid lubricant is then sheared within an air fed orifice into an airborne mist of droplets directed - downwardly towards an underlying liquid supply. Larger droplets are filtered ~ - 8 -E ~

~lU8~;S~6 out of the air flow by gravity, baffles, air flow forces and inertia effects to leave only a mist cloud of extremely small, substantially uniformly sized, spheroid part;.cles, the majority of which have average diameters on the order of one micron and which are substantially independent of gravity forces. This mist cloud is then migrated or drifted toward a longitudinally partitioned enclosure and preferably a non-electrically conducting enclosure ;~

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~6S76 having a plurality of electrodes therein. Corona discharge from the electrodes produced by a voltage difference main-tained between the electrodes and the metal substrate causes the atmosphere within the enclosure to, in effect, be~ome a plasma of ions, i.e. charged molecules of the ambient ga~es.
The mist or cloud of lubricating spheres is introduced into the plasma as a migrating sheet cloud permitting each par-ticle to randomly move and collide with lons in the plasma thus acquiring a charge from the relatively smaller ions.
Due to the relatively slow random movement and the uniformly small size of particles, they will all eventually acquire a substantially uniform maximum electrical charge giving rise to electrostatic forces which uniformly disperse the parti-cles onto the conducting substrate pas~ing through the lS partitioned non-conducting chamber to form a unifo~m, sub-stantially randon d;stribution of lubricating spheres over at least one surface o the conductive substrate. In the preferred embodiment, the lubricant spheroids become frozen to a solid state before being dispersed onto the metallic surface. Uniformity of distrlbution of the spheres on the conductive substrate is insured because the particle~ are uniformly small and permitted to rather slowly migrate about thenon-conducting chamber long enough to acquire uniform maximum elebtrical charges sufficient to strongly adhere same to the conductive substrate while at the same time repelling one another to thereby prevent coalescing of the particles. Further, the longitudinal partitioning of the non-conductive enclosure inhibits non-random movement of the spheres with respect to the plane of the conductive substrate. Since this proce~s is substantially 100%

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~86~76 efficient, the percentage coverage of the tiny lubricating spheres on the conducting substrate iB dependent only upon the quantity of particles supplied to the chamber and the relative velocity of the substrate (hence its dwell time in the enclosure~. -Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawings in which: .
FIGURE 1 is a side elevation view of presently preferred exemplary embodiment of the present invention;
FIGURE 2 is a plan view of the preferred exemplary lubricating apparatus illustrated in FIGURE 1 shown in partial section;
FIGURE 3 is an elevation view shown in partial ~ection of the upper mist forming exemplary apparatus of the present invention; ~ ~:
FIGURE 4 is a partial plan view of the upper mist forming exemplary apparatus illustrated in FIGURE 3;
FIGURE 5 is a section view of the lower mist forming exemplary apparatus of the present inYention;
: FIGURE 6 iB a partial plan view of the exemplary mist forming apparatus illustrated in FIGURE 57 FrGURE 7 is an entrance end view of .the lubricating . :
apparatus of the preferred exemplary embodiment of the pre- ;
sent invention;
FIGURE 8 is the exit end view of the lubricating apparatu~ of the preferred exemplary embodiment of the pre-sent invention;
PIGURE 9 is a schematic illustration of the , : . : .
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t;576 exemplary process of applying fine particles of lubricant to a conductive sub3trate, FIGURE 10 i~ a photo showing the density and sub-stantially uniform distribution of solid sphere~ of lubricant onto a tin plate conductive sub~trate formed while the tin plate wa3 moving through the lubricating apparatus at 300 feet per minute and when 50 cubic feet per hour of air is introduced into the mist generators of the apparatus of FIGU~E 1 to produce the mist cloud that is slowly migrated into the non-conducting precipitation enclosure; and : FIGURE 11 iS a photo showing solid spheres of lubricant deposited on a tin plate while the plate was moved through the lubricating apparatus at 45 feet per minute and when 50 cubic feet per hour of air was being introduced into the mist generators of the FIGURE 1 embodiment.
Refer now to FIGURE 1 which is a side elevation view of a presently preferred exemplary embodiment of the present inv~ntion. A~ illustrated, the lubricating apparatus includes a longitudinally partitioned, non-electrically ~. .
conducting precipitation chamber 51 whlch pre~erably is formed of a plastia material such a poiypropylene. The precipit~tion ohamber 51 haq an upper portion 53 which i9 above the plane 55 through which the aonductive ~ubstrate passe~ and includes a lower portion 57 which is positioned below the plane 55. A plurality of transversely extending electrodes or wires 59 forming a grid on each side of the substrate are charged to a common potential with respect to the conductive substrate and are positioned transversely ~ with respect to the direction of movement of the conducti~e ; 30 substrate through the lubricator. The electrodes are ~ . . 1 1 spaced with respect to the conductive substrate by a sultable distance, e.g., three inches, on each side of the substrate and are spaced with respect to one another. An ac voltage is preferably superimposed across the length of indiv~dual wires 59 to heat the wires and thus prevent an accumulation of lubricant deposits on the wires. A schematic showing of such a heating arrangement may be seen in FIGURE 9.
~n upper mist generator 61 i8 illustrated which in the preferred embodiment is sectioned into a plurality of transversely aligned mist generating units, one associated with each partitioned chamber within the precipitation chamber 51. Each section of the mist generator 61 includes a reservoir ~3 which contains ~he lubricant material to be dispersed onto the upper surface of the conductive substrate Preferably, the lubricant is solid at room temperature and accordingly, a heating element 65 is positioned within the reservoir in ordçr to heat the lubricant to a liquid state.
As will be explained more fully hereinbelow, air or another suitable gas supply is coupled to a venturi atomizer 67 which is positioned in the upper portion of the mist gener-ator. The passage of air under pressure into the venturi cause~ a pressure drop at the top of feedline 69, thereby causing the liquified lubricant to be sucked up into the venturi where the lubricant is sheared into individual droplets. The droplets then drop downwardly into the reservoir 63 where the larger droplets are returned to the bath of liquid lubricant. The remaining droplets in the mist migrate through a baffle filter arrangement ~see FIGURE
7) into the air flow outlet ~hamber in the upper portion of the mist generator and then through a channel 71 into the ;~

3l0~65~6 precipitation chamber 51. The baffle fllters out relatively large particles so that only particles of sufficiently small size, e.g. on the order of 10 microns in diameter or less and the majority on the order of one micron migrate into the precipitation chamber. The migration of the tiny spherical particles is so slow that during this migrating process, the particles solidify and become dry and accord-ingly under~ake the characteristics of hard, solid spheres.
The particles enter the precipitation chamber 51 in the form of a cloud which is substan~ially uni~ormly distributed across the width of each longitudinally partitioned section or portion o the chamber.
A ~econd series of transversely aligned mist generators 73 are positioned on the underside of the plane 55 along which the conductive substrate passes. The second set of mist generators each includes a reservoir 74 which contains t e lubricant to be applied to ~he underside of the conductive substrAte. A heater 75 is illuqtrated for main-taining the lubricant in its liquid state. A venturi atom-izer 77 is positioned at the top of the reservoir and in-cludes a venturi through which air under pressure passes.
As the air under pressure passes through the venturi, the liquified lubricant is sucked up through feedline 79 and is sheared into droplets by the air passing through the throat of the venturi. The larger droplets fall back downwardly into the liquid bath while smalIer particles nok affected ~j by gravity tend to flow through a zig-zag path 81 defined by ;
a set of baffle filters into the lower portion 57 of the precipitation chamber 51. These particles migrate quite slowly into the precipitation chamber 57 and accordingly, .
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~lO86~6 because of the low heat capacity thereof, solidify in the case oE the preferred lubricant which is a solid at room temperatures. Because of the migration of the particles into the chamber 57 and the small size of the particles, the particles each acquire a strong charge, i.e. a relatively large charge to mass ratio. Thus, the particles not only tend to be randomly dispersed before being charged but also are randomly and uniformly dispersed onto the conductive sheet passing ~hrough the chamber after being oharged. Thus, a substantially uniform distribution of the solid spheres on the conductive substrate is achieved.
Air supply for shearing the liquid lubricant in the throats of the venturis 67 and 77 is coupled to the -~ lubricator via an air filter 83. After the air has passed through ~he air filter 83, it passes through an air pres~ure reg~lating valve 85 and then into upper and lower air flow distxibutors 87 and 89, respectively. The air coupled to each of the flow distributors 87 and 89 is controlled by meter valves 91 and 93, respectively. ~hus, for example, the total air flowing into air flow distributor 87 si con-trolled by meter valve 91. The air passing into the dis-tributor 87 is coupled to each of six distributor conduits 95 via flow metering valves (not shown) os conventional design. Each of these conduits is coupled to an individual upper mist generator 61. In addition, the air flow coupled to the lower distributor 89 is controlled by meter valve 93 ~
with the distributor 89 coupling air to each of a plurality -~ ;
of distributor conduits 99 via 10w metering valves. Each of the flow metering valves is manually adjustable to con-trol the air flow into the conduits 95 (not shown). The ~l~86S76 conduits 99 couple the air under pressure to each of the plurality of individual mist generators 73 positioned on the underside of the substrate which passes through the lubricator.
The conductive substrate is fed into the lubrl-cator via a powered ~riction :roller drive and is then passed along the plane 55 within the lubricator by means of a belt drive 129. The substrate is passed out the exit end 103 of the lubricator and onto an output friction roller drive.
The substrate being lubricated may be in the form of in- -dividual sheets, a coil which is unravelled as it passes through the lubricator and is then wound up at the output end of the lubricator, an endless strip in a strip line manufacturing environment, or may be in any other suitable form as will be appreciated by those in the art. The lub-rica~or itself is of relatively small size and, as illu9-trated, can be easily moved from place to place by retract-ing the supports 107 so that the lubricator is supported by .
the rollers 109. As shown to approximate scale in the draw-ings, the FIGURE 1 lubricator has an overall width of about 68 inches, a height from the floor to the pass line of the sheet metal of about 45 inches and an overall length of about 8 feet, 2 inches.
In the case where no conductive sheets are being passed through the lubricator, a blower 111 positioned at the output end of the lubricator iB activated and is coupled to an outlet chamber 113 which is positioned at the outlet end of chamber 51 about the upper and lower portion o~ the plane 55 ~hrough which the substrate passes. The blower collects and filters out of the ambient air the lubricating ', .

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spheres which, of course, are not deposited on a substrate at such times since no substrate i9 then passing through the precipitation chamber 51. It should be understood, of course, that when a conductive substrate is passing through the pracipitation chamber 51, substantially all of the paxticles are electrostatically dispersed onto the substrate and accordingly, the blower 111 is not activated when the lubricator is in normal operation.
Refer now to FIGURE 2 which is a plan view of the lubricator of the present invention shown in partial cut-away~ The precipitation chamber 51 formed of a suitable plastic material i~ shown divided or partitioned longi-tudinally into a plurality o~ sections or chambers by means o~ longitudinally extending partitions 5Z. The electrodes or corona discharge wires 59 are illustrated extending transversely with respect to the longitudinally oriented chambers. At the inlet end of the precipitation chamber are a plurality o~ mist generators 61, each one associated - with an individual partition or chamber of the precipitation chamber 51. Each mist generator is illustrated ~see FIGU~E
3) having a separate air flow distributor conduit 95 coupled - thereto for supplying air to its respectively associated venturi atomizer 67 and for forcing the sheared lubricant droplets downwardly into the reservoir 63 positioned there-below. In the preferred embodiment, each mist generator actually has four controllable venturi atomizers 115-118 to which the air from the conauit 95 is coupled. Each venturi, as will be seen hereinbelow, generates fine lubricating spheres which are migrated into the precipitation chamber 51. By having the precipitation chamber 51 partitioned as '"....

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s76 illustrated, swirling of the air and lubricating particles from one side of the chambex to the other is prevented and accordingly, a random uniform distribution of the lubxicat-ing spheres on the conductive substrate is in~ured. Further, because the entire chamber housing is non-conductive, the charged lubricant particles move freely within the cha~ber without becoming attracted to the housing. Because of this the particleq within the chc~mber continue to acquire charge until the particles acquire sufficient charge to become accelerated toward the substrate.
At the input side of the lubricator the conductive substrate is fed into the precipitation chamber 51 via fric-tion rollers 121 which are driven by a motor ll9 via a chain drive assembly 123. At the outlet side of the lubricator, a second set of friction drive rollers 125 driven by motor 127 pulls the conductive substrate away from the lubricator.
Preferably, the friction rollers 125 are driven at a faster rate than the input friction rollers 121 in order to give the substrates passing through the lubricator added momentum for ease of stackability in the case where individual sheets of metal are being lubricated. As the conductive substrate passes through the lubricator and particularly through the precipitation chamber 51, the substrate is supported and guided by means of a plurality of belts 129 which are driven by the motor 127 via a chain dxive assembly 131. Bach of the belts 129 is relatively thin so that only a small por-tion of the total surface of the conductive substrate pass-~; ing through the lubricator will be contacted by the belts 129 and accordingly, only a small portion of the total sur-face area of the substrate will not have a lubricant ~l516~ 6 dispersed thereon.
Refer now to PIGURES 3 and 4 which illustrate in greater detail the individual upper mist generators 61 illustrated in FIGURES 1 and 2. With specific reference to FIGURE 3, the individual mist generators each include a reservoir portion 63 at the bottom thereof. The reservoir contains a lubricant which preferably is a solid at room temperature. Accordingly, a heater 65 of conventional design ~ -is positioned within the reservoir 63 proximate the bottom thereof. The heat generator is appropriately energized in ~ ?
j a conven~ional manner to maintain the lubricant in a liquid state during operation of the lubricator. At the top of the reservoir is positioned a plurality of venturi atomizers 67. Air or any other suitable gas under pressure is coupled ~i i to each of the venturi atomizers from the associated dls- i tributor conduit 95 via distributor passages 96. In addi-tion, a plurality of feed lines 69 are provided through which the liquefied lubricant is drawn upwardly and into the venturi atomizers. In the preferred embodiment there are four venturi atomizers and two feed lines in each mist generator with each feed line supplying liquid lubricant to two of the venturi atomizers as illustrated in FIGURE 4.
The venturi atomizers may be of conventional design. A
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coarse air flow control 88 is provided for each venturi atomizer for shutting off th0 air flow therethrough if ~
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desired. As aforementioned, the lubricant is preferably ` solid at room temperature and accordingly, a heating element ;., . ~
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~6S~i 66 is provided in the upper portion 65 of the mist generator 61 in ord~r to maintain the lubricant in a liquified state as it passes upwardly through the feed line 69 and into the venturi atomizer.
The exemplary venturi atomizer air passage or oxi-fice has a diameter on the order of 0.05 inch and accord-îngly, even though the relative volume of air flowing into the mist generator 61 is small, the velocity of the air passing through the nozzle and into the throat of the ven-turi atomizer is quite high. Hence, the pressure at the throat of the venturi nozzle is sufficiently reduced to draw upqardly ln the feed line 69 a sufficient amount of lubri-cant to cause a continuous shearing of the lubricant into fine droplets. For larger size venturis it may be desirable to actually force pump liquid lubricant to the oxifice to obtain an increased production quantity of particles thexe-from. The droplets are then forced downwardly into the reservoir 63 under the force of the air flowing through the ~i throat of the venturi and undex the force of gravity. The ~;
; 20 larger droplets whiçh are still in the liquified state drop into the bath of lubricant in the reservoir while finer droplets having a diameter on the order to 20 microns or less and preferably much less than lO microns form a cloud or mist of particles in ~he uppex portion of the reservoir 63. These fine droplets migrate about a first baffle 68 and a second baffle 70 into an air flow outlet box 72 po~itioned in the upper portion 65 of the mist generator. The baffles 68 and 70 tend to dispexse the air flow and the fine lubri-cating droplets ~o that theix distribution across the width of the mist generator is substantially uniform and random ' . 19 :

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~86S76 in nature. In addition the baffles 68 and 70 filter out : relatively large droplets which having a greater momentum than smaller particles can not negotiate the tortuous path through tha baffles and instead strike the baffles and fall back into the bath. The fine small diameter droplets which pass upwaxdly into the box 72 have such a small size that they move upwardly substant~ally independently of the force of gravity. Applicants have found that only about 5 to 10%
o the droplets formed by the venturi atomizers 67 ha~e sufficiently small size to migrate upwardly paYt the baffl~s and into the box 72 with the remaining droplets falling back : into the liquid lubricant bath. After the particles have moved into the box 72, the migrate downwardly through pas- ~ , sage 71 which exits into the upper portion 53 of the pre-cipitation chamber 51. The droplets as they migrate through passage 71 are still substantially in liquid fo~m. However, in the case of the preferred lubricant which is solid at room temperature, because of their low heat capacity, as ::~
they pass into the preciptation chamber the droplets solidify and dry, thereby taking on the characteris*ics of round, solid bearlngs. The droplets pass into the chamber 51 and `.~ -form therein a cloud of randomly dispersed lubricating spheres which are not attracted to the metal substrate pas~
; sing therethrough until the droplets acquire a sufflciently ; ~
gxeat charge. The migration of the cloud of lubricating : .
spheres into the chamber 51 is assisted by the relatively low volume air flow passing through the venturi 67 and into .-the upper portion of the reservoir 63. As aforementioned, the electrodes or corona discharge wires 59 positioned with~
in the chamber 51 ionize the atmosphere therein due to a .

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voltage maintained between the electrodes and the metal substrate, thereby creating a plasma of ionized ambient gaseous molecules about the electrodes 59. This ionized atmosphere in turn multiply collides with and thus imparts a substantially uniform maximum charge to the fine but rela-tively larger spherical lubricating particles migrating into the chamber to thereby cause the charged lubricating par-ticles to be attracted to and uniformly and randomly dis-persed unto the conductive substrate passing therethrough.

Refer now to FIGURES 5 and 6 which illustrate one of the mist generators positioned on the underside of the ~conductive substrate passing through the lubricator. As illustrated, the lower mist yenerators each includes a reservoir 74 which contains a lubricant which is liquified by means of a heating element 75 of conventional design. -~
Positioned above the reservoir 74 is a mist forming portion ; 78 having a plurality of venturi atomizers 77 positioned therein. Air under pressure is coupled to each of the venturi atomizers 77 via distributor conduit 99 as illus-trated in FGIURE 6. In addition, a pair of feed lines 79 are provided which extend downwardly into the bath of lub-ricant at one end and which are coupled to a passageway ; leading to the throat of two venturi associated therewith at the other end. A second heating element 80 is positioned within the upper portion of the mist generator for maintain-ing the lubricant in a liquid state as it passes into and out of the venturi atomizer 77.
In operation as air under pressure is forced into the throats of the venturi atomizers, lubricant is drawn upwardly through the feed lines 79 and into each of the ; , . .

1~)86~
venturl at~miæers. The lubricant is then sheared into droplets which are forced downwaxdly into the upper portion of the reservoir 74 by the Force of the air acting there-against and under the force of gravity. The larger droplets which typically constitute 90 to 95~ of the total droplets Eormed, drop back into the bath of lubricant while the re-maining droplets, preferably having a diameter of less than 10 microns, migrate past baffle 82 and about a second baffle 84 into a passageway 86. The baffles 82 and 84 cause the droplets to become randomly distributed across the width of the mist generator and at the same time reduces the speed of movement of the droplets as they move out of the reservoir 74. In addition, the baffles filter the larger particles out of the mist to thereby reduce the average size of the `
paxticles migrating into the chamber 51. The passage 86 has a large exit area in order to further reduce the speed of the droplets so that as the droplets enter the lower portion 57 of the precipitation chamber 51, the movement thereof is migratory in nature with the droplets forming a slow moving cloud of randomly dispersed solid spheres of lubricant.
These small dry spheres of lubricant are subsequently ionized and randomly dispersed onto the substrate moving through ~;
the precipitation chamber.
A course control 88 is provided for controlling the air flow through the throat of each o~ the venturi atomizers 77. Thus, for example, if it is desired to shut off one or more of the atomizers, a simple turning of the contoll 88 will shut off the flow of air through the ven-turi. This control is provided in addition to a fine control for each individual mist yenerator. It is contemplated that these and/or similar controls will be either manually or automatically manipulated to control the air supply, i.e., pressure or volume metering, etc., to the orifices and/or the number of such orifices in operation to thereby control the quantity of lubricating spheroids produced per unit time and delivered to the coating chamber.
Refer now to FIGURE 7 which is a view of the en-trance end of the lubricator of the present invention. As illustrated, a motor ll9 is fixedly secured to the side of the lubricator and drives a plurality of friction rollers 121 via a chain drive system 123. The friction rollers 123 pull the conductive substrate into the lubricator for apply-ing the solid lubricating particles to the surfaces thereof.
A belt drive arrangement is provided having a plurality of belts 129 which are driven by the motor 127 at the opposite end of the lubricator. ~hus, the belts 129 support the con-ductive substrate as it passes through the lubricator and in addition assist in conveying the substrate as it passes through the precipitation chamber 51. The belts each pass under the lubricator and then upwardly in the direction illustrated by the arrows and then into and throu~h the pre-cipitation chamber 51. At the top o~ the lubricator is - positioned a plurality of individual mist generators posi-tioned alongside one another for generating the tiny solid spherical droplets which are dispersed onto the conductive substrate. A plurality of distributor conduits 95 conduct air under pressure from a distributor box 87 to each o~ the individual mist generators 61. The air flow into the dis tributor box 87 is controlled by means of a meter valve 91.
The air filter 83 for filtering the air coupled to each of the venturi atomizers is also illustrated.
Refer now to FIGURE 8 which i9 an exit end view of the lubricator of the present invention. As illustrated, a motor :L27 drives a plurality o~ fric-tion rollers 125 which pull the metal substrate out of the precipitation chamber Sl. In addition, motor 127 drives a plurality of drive belts 129 via a chain drive assembly 131 and an axle 132.
The drive belts pass outwardly from the precipitation cham-ber 51 and downwardly as illustrated by the arrows and then under the lubricator to the fxont end thereof as illustrated in FIGURE 7. As a~orementioned, these belts guide the con-ductive substrate through the precipitation chamber.
Additionally, in case no conductive substrate is being passed through the lubricator, the lubricating spheres passing into the precipitation chamber Sl wili not be attracted to any surface because of the non-conducting make-up of the precipitation chamber 51. Accordingly, a blower 111 is provided ~or drawing the spherical lubricating parti-cles out of the chamber Sl through an exhaus~ conduit 112 and into an appropriate recovery vessel. It should be under- ~
stood that the blower 111 is not used when a conductive ~ -subtxate is being passed through the precipitation chamber 51 since substantially all of the fine spherical particles o~ lubricant formed are randomly dispersed onto the sub~
strate as it passes therethrough. Accoxdingly, such a blower is not required during normal operation of the lubricator.
The operation of the lubricator of the present invention will now be described in conjunction with FIGURE

9 which is a simplified schematic illustration of a portion o~ the lubricating apparatus of the present invention. A
' .

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6~

conductive substr~te S0, which may be of any suit~ble mate-riaL such as, for example, alumin~, iron, steel, copper, tln and various alloys -thereof, is guided through the lub-ricator and in paxticular the precipitation chamber 51 by means of a plurality of belts 129 spaced across the width of the lubricato'r. The substrate is passed through the lubri~
cator at any appropriate speed such as, for example, 45 feet per minute upwards to 300 feet per minute or more, As the substrate passes into the precipitation chamber 51, the slot therethrough for receiving the belts 129 and the substrate 50 i~ relatively small in order to contain the desired spherical particles of lubricant substantially totally within .
the precipitation chamber 51. At the same time as the sub-strate is moving through the lubricator, air under pressure - 15 is coupled to each of the distributor conduits'95 and 99 associated with the upper and lower mist generators 61 and 73, respectively. The pressurized air is then conducted through the venturi atomizers 67 in the upper mist generators ; which ln turn causes liquid or liquified lubricant to be 2'0 drawn upward into feed lines 69 and into the ~hroats of the ~' venturi 67. The resulting droplets thus formed are forced ' downwardly into the upper portion of the reservoirs 63 with the great majority of the droplets falling back into the lubricant bath. However, a ~mall portion of the droplets, on the order of 5 to 10% thereof, migrate past a baffle filter arrangement including baffles 68 and 70 (see FIGURE
3) and upward into an outlet air flow box 72 positioned in the upper portion of'the mist generator. The baffles act as a filter which eliminates the relatively large droplet~
but which permits passage of the relatively small droplets ~' ~5 s~ :
into the box 72. In addition, the baffles and the air flow outlet box 72 slow down the movement of the tiny particleq of lubricant and cause the particles to be uniformly and randomly distributed across the width of the mist generator.
Th~ mist then passes ~rom the outlet box 72 into a passage 71 with the droplets still being substantially in liquid form. As the droplets migxate into the chamber 53 above the substrate 50, the droplets, i~ solid at room temperature, solidify into tiny hard spherical lubricant particles having diameters which range between 1 micron and lO microns (most may be on the order of one micron) and which slowly move into and about the chamber 53 to form a cloud o~ particles substantially uniformly spread across the width of each partition chamber within the upper portion of the precipita-tion chamber 51.
At thP same time, the grid o~ interconnectedelectrodes is appropriately charged with respect to the substrate so that a sufficient corona current is provided to ionize the surrounding atmosphere and to overcome space charge ef~ects which might be imposed by the relative con-centration of the particles passing into the chamber and any previously implanted coating on the substrate. The charging of the atmosphere surrounding the electrodes 59 results in the ~ormation of a plasma which in turn multiply collides with and charges tha relatively larger lubricant particles as within the chamber. The particles continue to randomly migrate about the chamber as they continue to acquire charge. When the particles are su~iciently charged, i.e., the particles have a relatively large maximum charge to mas~ ratio, they are attracted to the surface of the , .

substrate 50 and are dispersed thereon in substantially a uniform random distribution. Because the particles are small and hence have little momemtum, they tend to repell one another as they move within the chamber. Acordingly, coalescing of the particles does not occur and the particles tend to be spaced from one another after being attracted to the substrate. This insures a substantially random distri-bution of particles on the substrate.
In the underside of the substrate 50 is a second series of mist generators 73 which, as aforementioned, gen-erate a plurality of lubricant droplets, the great majority of which drop back into the lubricant bath in the reservoir 74. However, those droplets of lubricant which have suf-ficiently small size, that is, a diameter ranging between 1 micron and 10 microns (most on the order of one micron) are not affected by gravity and have a tendency to migrate about the filter baffles 82 and 84 (see FIGURE 5) and into an outlet chamber 86 which is of sufficiently large size to slow down the movement of the particles while the baffles 82 and 84 cause the particles to become randomly distributed `` across the width of the mist generator. The resulting cloud of spherical lubricant particles migrating into the lower j portion 57 of the precipitation chamber 51 form a cloud of particles which are substantially uniformly distributed - 25 across the transverse width of each of the partition chambers within the precipitation chamber 51. These particles, after collisions with the plasma cxeated by the electrode grid 59 become charged to the same polarity as the grid in the upper portion 53 o~ the chamber and thus cause the spheroid~ to be attracted ~o the substrate 50. The particles are -~:

.
.

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dispersed randomly and uni~ormly across the wldth of the substrate 50 as it passes through the precipitation chamber 51 .
With reference to FIGURE 10, a photograph i8 shown of a portion of a substrate a~ter having the solid lubricant spheres dispersed thereon with the portion of tha substrate ~ ;
photographed magnified 1000 times. ~s can be seen, the solid droplets are randonly distributed over the surface of the substrate and have not coalesced together particularly because of the like charge each particle acquires as it i~
attracted to the substrate S0. The substrate illustrated in the photograph is a tin plate which was passed through the precipitation chamber 51 at 300 feet p~x minute. In addi-tion, 50 cubic feet per hour of mist-producing air was passed into each of the mist generators and consequently into the precipitation chamber 51.
FIGURE 11 is a photograph of a portion of a tin substrate ~urface magnified 1000 times illustrating the solid, dry, ~pherical lubricank particle6 substantially randomly distributed thereacross. To obtain the article of manufacture shown in this photograph, ~he tin substrate wa~
; moved through the pxecipitation chamber 51 at only 45 feet per minute as opposed to the 300 feet per minute rate used for the photograph of FIGURE 10. Accordingly, the di~tri-bution of the solid spheres on the surface of the substrate is ~ubstantially denser. However, in each ca~e it is not~d that no coalescing of the particles occurs and that the particles are substantially randomly and uniformly dis-tributed over the surface area photographed. The 6mall particles illustrated (the majority of all partiales) are ~V~6~7~;
on the order of l micron in diameter while it is estimated that the few largest particles shown have a diameter on the order of 4 or 5 micron~.
While the number of particles per unit area dis-persed onto the surface of the substrate i8 dependent pri-marily only upon the number of fine solid particles migrat-ing into the chamber 51 and the relative velocity (and hence dwell time) of the substrate through the precipitation cham~
ber, it should also be understood that the percent of the substrate area covered i5 also related to the size of the particles and/or to the weight in milligrams of the parti- -~
cles deposited on a unit area of the substrate. Thus for the same given weight of lubricant deposited on a unit area -of the substrate, particles having a diameter of one micron will cover twice the area of particles having à diameter of two microns and four times the area covered by particles having a diameter of four microns, and so on. Accordingly, it can be seen that by reducing the size oE the solid par-ticles deposited on the substrate, substantial quantities of lubricant can be conserved for a given desired percentage coverage of the substrate. This is an additional reason why the size o the spherical droplets is controlled by the baffles in the misk generators and by the design of the venturi atomizer so that only the very tiny particles having a diameter of less than ten microns and the majority being on the order of one micron are permitted to pass into the precipitation chamber 51.
While the present invention has been disclosed in connection with only a single exemplary embodiment thereof, it should be understood by those in the art that there may ;
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~.ll 86S7~Ei be other variations of the preferred embodiment which fall th.;.n th~ scope of the appended claims.

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Claims (61)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A new article of manufacture comprising: a metal substrate having at least one electrically conductive surface; and substantially uniformly dispersed spaced discrete particles of dielectric lubricating material spaced apart and uniformly distributed over said at least one surface.

2. A new article of manufacture as in claim 1, wherein the particles are substantially spheroidally shaped.

3. A new article of manufacture as in claim 2, wherein the average diameter of said particles is less than 10 microns in size.

4. A new article of manufacture as in claim 3, wherein a substantial majority of said particles have diameters on the order of one micron in size.

5. A new article of manufacture as in claim 4, wherein said particles are in the solid material phase.

6. A new article of manufacture as in claim 5, wherein said particles are similarly distributed over both said metallic surfaces.

7. A metallic substrate having a surface thereof coated with lubricating particles of a dielectric hydrocarbon material deposited while said particles are electrically charged to the degree necessary to repel one another, said particles being substantially laterally displaced from one another on said surface.

8. A metallic substrate as defined in claim 7, wherein said lubricating particles are substantially spheroidal in shape and are non-fluidic at room temperature.

9. A metallic substrate as defined in claim 8, wherein a major portion of said lubricating particles have diameters less than about 10 microns in diameter and the majority of particles in said major portions have an average diameter on the order of one micron.

10. A metallic substrate having a surface thereon coated with a distribution of lubricating particles which are non-fluidic at room temperature, said lubricating particles being substantially spheroidal in shape and spaced from one another by mutual electrostatic repulsion while being deposited electrostatically to form minute air pockets there-between.

11. A metallic substrate as defined in claim 10, wherein a major portion of said particles have diameters less than about 10 microns and a majority of the particles in said major portions have diameters on the order of one micron.

12. A metallic substrate as defined in claim 11, wherein less than about 10 percent of the surface area is covered by lubricant.

13. A metallic sheet in coil form, said sheet having both major surfaces thereof having distribution of lubricating particles which are non-fluidic at room temperature, said lubricating particles being substantially spheroidal in shape and substantially spaced from one another, the majority of said particles having diameters less than about 10 microns.

14. A metal substrate having a surface thereof coated with a distribution of discrete lubricating particles deposited while said particles are electrically charged so as to repel one another whereby said particles are substantially laterally displaced from one another on said surface, said particles being non-fluidic at room temperature and substant-ially spheroidal in shape, said particles being substantially uniformly dispersed over said surfaes a major portion of said particles having average diameters less than 10 microns, and a majority of said particles in said major portions having average diameters on the order of one micron.

15. A metallic substrate as defined in claim 11, wherein the particles of lubricating material are present on the surface in an amount between 4 milligrams per square foot and 24 milligrams per square foot.

16. A lubricated metal sheet adapted for manufact-uring operations comprising:
a flat metal sheet having two opposed surfaces; and a uniform distribution of spaced spheroid-shaped particles of solid dielectric hydrocarbon lubricating material adhering to at least one of said surfaces.

17. A metal sheet adapted for handling, stamping and forming operations comprising a thin metal substrate having on at least one surface thereof a uniform distribution of spaced spheroids having a diameter of less than 10 microns wherein the spheroids are formed from a hydrocarbon taken from a group consisting of paraffin wax, microcrystalline wax and petrolatum.

18. A metallic substrate having a surface thereof distributed with solid particles of a dielectric lubricating material laterally displaced from one another, said lubricating material being selected from the group consisting of hydrocarbons and ethylenic polymers.

19. A metallic substrate of claim 18, wherein said hydrocarbons are selected from the group consisting of paraffin wax, petrolatum, and microcrystalline wax.

20. A metallic substrate of claim 19, wherein said hydrocarbons are paraffinic wax.

21. A metallic substrate of claim 19, wherein said hydrocarbon is petrolatum.

22. A metallic substrate of claim 18, wherein the ethylenic polymers are selected from the group consisting of polyethylene glycols, methoxypolyethylene glycols, chlorinated naphthalenes and hydrocarbons produced by the Fischer-Tropsch process.

23. Method for electrostatically and uniformly dispersing particles of lubricating material upon a moving length of electrically conductive substrate, said method comprising the steps of:

providing apparatus including a housing having transverse dimensions sufficient to encompass the transverse dimensions of said substrate, having a longitudinal dimension sufficient to encompass at least a predetermined portion of said moving length of substrate and having a predetermined depth over at least one side of the intended travel path of the substrate, said housing having ingress and egress openings which permit the conductive substrate to be moved therethrough along the longitudinal axis of said housing and having a plurality of longitudinal partitions disposed within said housing on said at least one side dividing the interior of this side of the housing into a plurality of longitudinally extending sections, and including electrodes disposed within said longitudinal sections of the housing and spaced from said intended travel path of the substrate;
impressing a voltage difference between said electrodes and said substrate as it passes through said housing so as to maintain a corona discharge and charged plasma atmosphere within said longitudinal sections while a substrate is passing therethrough; and supplying a predetermined quantity of particles of lubricating material to each longitudinal section.

24, Method as in claim 23, wherein said supplying step comprises:
supplying mists of lubricating material from a plurality of separately controllable mist generating sources, each respectively associated with one of said longitudinal sections.

25. Method as in claim 24, wherein a plurality of individually controllable gas-fed orifices are utilized in said supplying mists from separately controllable mist gener-ating sources step for individually producing said particles of lubricating material from said orifices into the respectively corresponding longitudinal sections.

26. Method as in claim 25, wherein said supplying mists from a plurality of separately controllable mist generating sources step includes passing the mist of lubricating material through an output port on each such generating source connecting the source to its respectively associated longitud-inal section via a conduit having at least one internal dimension substantially extending over the entire transverse dimension of at least its respectively associated longitudinal section.

27. Method as in claim 26, wherein each of said output ports has at least one internal dimension substantially extending over at least the transverse dimension of its respectively associated longitudinal section.

28. Method as in claim 27, wherein said step of supplying mists from a plurality of separately controllable mist generating sources comprises:
maintaining a liquid supply of said lubricating material within a substantially closed container in the lower portion thereof; supplying a stream of liquid to an orifice disposed in the top portion of said container having a controllable gas inlet and a gas outlet directed downwardly toward said liquid supply whereby particles of the liquid are sheared therefrom and propelled downwardly toward the underlying liquid supply; and passing the thus formed smaller sized particles of liquid through an opening disposed along one side of the container at an upper edge portion as said output port past a baffle means extending internally of said container along said output port so as to form an obstruction to undesired larger sized particles thereby tending to limit the size of particles carried through said output port.

29. Method as in claim 28 including:
passing the mist of particles from a first portion of said separately controllable mist generating sources while said sources are disposed in a transversely aligned bank along one end of said housing with the lower portion of the containers being disposed above the intended travel path of the substrate and wherein said conduit is a transversely and vertically extending channel connecting said output ports with a lower end portion of said at least one side of the housing adjacent one of the ingress and egress openings therein.

30. Method as in claim 23, wherein said housing is provided with an enclosed chamber within said housing having a predetermined depth over the remaining side of the intended travel path of the substrate opposite said at least one side;
the interior of the remaining side of the housing being divided into a plurality of further longitudinally extending sections with a further plurality of longitudinal partitions disposed within said housing on said remaining side; and further electrodes also being connected to said voltage means and disposed within said further longitudinal sections of the housing and spaced from said intended travel path of the substrate; said method further comprising:
maintaining a corona discharge and charged plasma atmos-phere within said further longitudinal sections while a substrate ?s passing therethrough; and supplying a predetermined quantity of particles of lubricating material to each further longitudinal section.

31. Method as in claim 30, wherein said supplying steps comprise:
supplying mists of lubricating material from a plurality of separately controllable mist generating sources, each respectively associated with one of said longitudinal sections and said further longitudinal sections.

32. Method as in claim 31, including supplying a liquid supply of said lubricating material to a plurality of individually controllable gas-fed orifices as each of said separately controllable mist generating sources for producing said particles of lubricating material.

33. Method as in claim 31, including passing the mist of lubricating material through an output port of each of said separately controllable mist generating sources connecting the source to its respectively associated longitudinal section or further longitudinal section via a conduit having at least one internal dimension substantially extending over the transverse dimension of at least its respectively associated longitudinal section whereby said particles are substantially uniformly supplied to each longitudinal section or further longitudinal section over its entire transverse dimension.

34. Method as in claim 33, wherein said steps of supplying separately controllable mist generating sources comprise:

maintaining a liquid supply of said lubricating material within a substantially closed container in the lower portion thereof, supplying a stream of the liquid to an orifice disposed in the top portion of said container having a controllable gas inlet and a gas outlet directed downwardly toward said liquid supply whereby particles of the liquid are sheared therefrom and propelled downwardly toward the underlying liquid supply;
passing the mist of smaller sized particles of liquid through an opening disposed along one side of the container at an upper edge portion as said output port past a baffle means extending internally of said container along said output port so as to form an obstruction to undesired larger sized particles thereby tending to limit the size of particles carried through said output port.

35. Method as in claim 34 including passing the mist from the separately controllable mist generating sources while such sources are disposed in a transversely aligned bank along one end of said housing with the lower portion of the containers being disposed above the intended travel path of the substrate and wherein said conduit comprises a transversely and downwardly extending channel connecting said output ports thereof with a lower end portion of said at least one side of the housing adjacent one or the ingress and egress openings therein; and passing the mist of particles from a second portion of said separately controllable mist generating sources while such sources are disposed in a transversely aligned bank along one end of said housing with the upper portion of the containers being disposed below the intended travel path of the substrate and wherein said conduit comprises a transversely extending channel connecting said output ports thereof with an upper end portion of said remaining side of the housing adjacent one of the ingress and egress openings therein.

36. Method as in claim 35, wherein the mist of lubricating material passing into each section is passed through an output port having at least one internal dimension substan-tially extending over at least the transverse dimension of its respectively associated longitudinal section or further longi-tudinal section.

37. Method as in claim 23, wherein said housing and said longitudinal partitions are formed of non-electrically conducting material.

38. Method for uniformly dispersing particles of lubricating material upon a moving electrically conductive substrate comprising:
dividing the lubricating material into a supply of small particles and into a plurality of clouds of such particles arranged across the width of the moving substrate by confining the small particles for random movement in such clouds; and electrostatically charging the randomly moving particles in each of the plurality of clouds by ionizing the atmosphere adjacent the electrically conductive substrate to deposit the small particles of lubricating material upon the substrate from the plurality of clouds substantially entirely under the influence of electrostatic force.

39. The method of claim 38, wherein a non-fluid lubricating material is disposed and said step of dividing the lubricating material into a supply of small particles comprises the steps of heating the non-fluid lubricating material to liquefy it, atomizing the liquefied lubricating material into a spray including said particles, removing the larger particles from said spray and allowing the remaining small particles to return to their normal non-fluid state prior to being deposited upon the substrate.

40. The method of claim 39, wherein said step of atomizing the liquefied lubricating material includes releasing a flow of compressed air and subjecting the lubricating material to forces generated by the release of compressed air, and said step of removing the larger particles from said spray and allowing the remaining small particles to return to the normal non-fluid state includes using residual flow of the released compressed air to carry the spray over such a path that the larger particles are removed from the spray and the remaining particles are small enough to be substantially independent of gravity but subject to the residual flow of compressed air, such residual flow carrying the remaining small particles past baffling to distribute the smaller particles uniformly within said plurality of clouds.

41. A method of coating a surface of a metallic substrate to form a lubricous coating thereon, comprising:
forming a plurality of finely divided particles of lubricant, said particles having a diameter to weight ratio such that they will remain suspended in a substantially quiescent atmosphere;
physically transporting said suspended particles from the location of particle formation to the general location of said metallic substrate;
confining said suspended and transported particles in a non-electrically conductive housing adjacent the metallic substrate to be coated in a substantially quiescent atmosphere;
electrically charging said particles while so confined to the degree necessary to enable them to repel one another while they are suspended; and electrostatically depositing said particles on the metal surface while said particles are in a repelling relationship with respect to one another by establishing in attracting electrical field between said confined charged particles and said metallic substrate whereby said particles are deposited on the substrate in a laterally displaced relationship with respect to one another.

42. A method as defined in claim 41, wherein the lubricant particles are spheroidal in shape and are initially formed by melting a lubricant which is a solid at room temperature forming the molten lubricant into substantially spheroidal shaped particles, and cooling said particles prior to depositing on the metallic substrate whereby said particles retain their spheroidal shape when deposited on the metallic substrate.

43. A method as in claim 42, wherein the suspended spheroidal particles are confined adjacent the surface of a metallic substrate prior to being electrically charged.

44. A method for electrostatically dispersing tiny spheroids of lubricating material onto a moving electrically conductive substrate, said method comprising the steps of:
providing a supply of lubricating material in a liquid phase;

forming a mist of finely divided spheroids from said supply of liquid lubricating material, a majority of said spheroids having an average diameter less than 10 microns in size such that said mist is airborne and substantially independent of gravity forces;
providing a housing through which said conductive substrate is passable longitudinally thereof, the housing having electrodes extending therewithin, said electrodes being spaced from said moving substrate;
producing an electrical corona discharge within said housing by applying a voltage differential between said moving substrate and said electrodes to thereby produce a plasma therewithin of electrically charged ambient gaseous molecules electrically charged to the same polarity as the electrical polarity existing on said electrodes;
drifting said airborne mist into said plasma to produce multiple collisions between said charged ambient gaseous molecules and said relatively larger spheroids, thereby accumulating a like electrical charge on said spheroids;
said drifting step being carried forth so as to cause substantially all of said spheroids to attain a substantially uniform maximum charged state whereupon substantially all of the thusly charged spheroids to move toward the oppositely charged substrate surface and to substantially uniformly disperse thereover whereby substantially all the spheroids drifted into said plasma are eventually uniformly dispersed onto the substrate surface to produce a uniform steady state percentage coverage of the substrate that is defined primarily only by the steady state quantity of spheroids drifted into the plasma and by the steady state speed of the substrate moving through said housing.

45. A method as in claim 44, wherein said housing through which passes said substrate is a non-electrically conductive housing.

46. A method as in claim 44 wherein said drifting step comprises average spheroid movements of distance per unit time towards and into said plasma which are less than the average substrate movements of distance per unit time through said housing.

47. A method as in claim 44, wherein said step of forming a mist comprises:
providing a substantially closed container housing said supply of liquid lubricating material and having an air inlet orifice and an outlet port both at the upper portion thereof, passing a supply of compressed gas through said inlet orifice downwardly toward said supply of liquid lubricating material and generally directed away from said outlet port;
drawing a stream of said liquid lubricating material through said orifice and downwardly out through said output port with said supply of gas thereby shearing said stream into liquid spheroids of various sizes which spheroids are thus propelled downwardly towards said supply of liquid lubricating material and away from said outlet port whereby only airborne spheroids substantially independent of gravity forces are passed out through said outlet port.

48. A method as in claim 44, further comprising the step of heating said elongated electrodes to prevent any accumulation of said lubricating material thereon.

49. A method as in claim 48, wherein said heating step comprises passing AC electrical current through said electrodes.

50. A method for applying a lubricating material upon a metallic substrate comprising:
forming a mist of finely divided particles of said lubricating material from a plurality of mist sources, the particles of said material having an average size of less than 10 microns diameter;
passing the particles from said plurality of mist sources into a first containing means extending along the width of said metallic substrate and having a substantially quiescent atmosphere therein and permitting said particles from the different sources to diffuse together therein and form a substantially uniformly distributed mist of said particles along the entire width of the substrate;
passing the particles from said first containing means into a second containing means having an electrostatic field therewithin while maintaining the particles within a closely confined spaced within the electrostatic field whereby said particles are charged therein; and conveying the metallic substrate through said second containing means while establishing an attracting electrical field between said confined charged particles and said metallic substrate so as to electrostatically deposit the lubricating material upon said substrate.

51. The method of claim 50, wherein forming the mist includes dispersing fluid droplets and depositing said droplets in the form of solid particles upon the surface of said substrate.

52. A method of dispensing small lubricating particles substantially uniformly and randomly across at least one surface of a moving conductive substrate comprising the steps of:
forming in an atomizer a plurality of droplets of a lubricant, filtering said droplets to form a mist of finely divided droplets having an average size of less than about ten microns diameter, slowly migrating said droplets into a non conductive precipitating chamber, distributing said droplets substantially uniformly about said chamber, moving said droplets substantially randomly within said chamber, moving a conductive substrate through said chamber, and continually charging said droplets with respect to said conductive substrate until said droplets are accelerated toward said substrate to form a substantially uniform and random distribution of said droplets on at least one surface of said substrate.

53. A method of forming a lubricous surface on a metallic substrate, comprising forming a plurality of finely divided particles of a lubricant taken from a group consisting of hydrocarbons and ethylenic polymers, said particles having a diameter to weight ratio such that the particles will remain substantially suspended in atmosphere, transporting said particles to a location adjacent the metallic substrate, electrically charging said particles of lubricant to the degree necessary to enable them to repel one another, and depositing said particles of lubricant on the metal surface in a repelling relationship with respect to one another whereby said particles are laterally displaced with respect to one another.

54. A method as set forth in claim 53, wherein the lubricant is a hydrocarbon selected from the group consisting of paraffin wax, microcrystalline wax and petrolatum and said particles are spheroidal in shape and are initially formed by liquefying said lubricant by heat, forming the liquefied lubricant into substantially spheroidal shaped particles, and cooling said particles prior to depositing on the metallic substrate whereby said particles retain their spheroidal shape when deposited on the metallic substrate.

55. A method as set forth in claim 54, wherein the non-liquid spheroidal particles are confined in a suspension at the location adjacent the surface of a metallic substrate.

56. A method of forming a lubricous surface on a metallic substrate, comprising providing a liquid supply of a normally non-fluid dielectric lubricating material, forming a plurality of finely divided spheroidal particles, a majority of which have a diameter less than 10 microns, transporting the finely divided particles to a location adjacent the metallic substrate while returning the particles to their normally non-fluid state, electrostatically charging said particles of dielectric lubricating material to such a degree that they mutually repel one another and are deposited on the metallic substrate while so charged.

57. A method as set forth in claim 563 wherein said lubricating material is a hydrocarbon wax.

58. A method as set forth in claim 56, wherein said lubricating material is petrolatum.

59. A method as set forth in claim 56, wherein the lubricating material is a synthetic wax selected from the group consisting of poly-ethylene glycols, methoxypolyethylene glycols, and chlorinated naphthalenes.

60. A method of forming a lubricous surface on a metallic substrate, comprising forming a plurality of finely divided particles of a dielectric lubricating material, said particles having a diameter to weight ratio such that the particles will remain substantially suspended in atmosphere, providing a quiescent cloud of said particles adjacent the surface of the metallic substrate to be coated, electrostatically charging said particles so that the charged particles mutually repel one another and are deposited and distributed on said substrate surface while so charged substantially entirely by electrostatic forces.

61. A method for electrostatically and uniformly dispersing particles of lubricating material upon an electrically conductive substrate comprising the steps of:
supplying to a confined space adjacent said substrate a quantity of small, randomly moving, substantially spheroidal particles of dielectric lubricating material to form a cloud of said particles; and electrostatically charging said particles by ionization to form a quiescent cloud of charged particles which are deposited upon the substrate, the charged particles being in repelling relationship to one another.