US2007441A - Wire coating apparatus - Google Patents

Description

Jly 9, 1935. i A. CANDY, JR 2,007,441 I WIRE coATING APARATUs Filed No`v.`19, 1932 "s sheets-shear 1 July 9,1935.

A. T. CANDY, JR

Filed Nov. 19, 1932 3 Sheets-S1166@ 2 4 WIRE COATING APPARATUS l FnedNov. 19, 1932 A s sheets-sas# s 1o y applicable to Patented July 9, 1935 UNITED. vSTATES PATENT oFFlcE 2,007,441 wma cosmo 'APPARATUS Albert T. Candy, Jr., Oak Park, Ill., assignor to Candy & Company, Inc., Chicago, Ill., a corporation of Illinois` Application November 19, 1932, Serial No. 643,307

-5 Claims. (Cl. 91'3 2) 5 layer or impregnation of similar material. This is of advantage in making possible the production of colored wire without the expense of a thick impregnation or layer of material contain ing the costly pigments.

While certain features of my invention are impregnation of a continuous strand-like material, it is particularly concerned with the problem of coating where the material to be deposited is coated as a lm of substantially the' same or slightly larger coated diameter than the object being coated. Many featuresof my invention are applicable to continuous coating processes for strand-like objects-other than wire, vbut I here illustrate it particularly applied to insulated wire vfor electrical purposes.- As applied to insulated wire, my application is specifically concerned with coating an insulated wire, the

fabric braid of which has previously been impregnated.

In insulated wire, the fabric braid has customarily been impregnated with a weather proofing materialfrequently `a wax-like material such as parafn or a pitch such as asphaltum pitch-to protect the rubber insulation'beneath the braid. More recently stearin pitch, or some other ameretarding composition has been used either as the impregnation or as an auxiliary coating on the previously mentioned impregnation, to check the tendency of the braid to sustain combustion and carry flame along the Wire in the event of rire. When the impregnation or resulting surface has been pitch-like, the wire has. been given a nal coating of paraflin to restore the surface characteristics of the wire which were found desirable when the braid was treated only with a parain impregnation. The desirable characteristics of the parailin or other wax-like surface are its lubricating qualities, which enable the wire to be drawn through circuitous conduits without danger of abrasion, and a generally non-sticky sur- A face, which avoids danger of the convolutions of wire on a spool or coil sticking together in warm weather as would be the case with a pitchy surface.

. .A paran coating on pitch has certain objections, even apart from the 'difficulties of applying it properly, among them: the paraffin, while normally transparent, has a tendency to flake ofi -and also to form more or less vopaque regions where it has been subjected to incidental scraping action, with the result that the appearance is not uniform and toa greater or less extent `any color beneath the coating is dulled; the die or -wiper through which the 'paraffin coated wire is passed often acts unevenly leaving bared or even abraded regions on the braid; the coating may be contaminated with the'impregnation or other underlying material; the parailin is inflammable and therefore in any event a very objectionable feature, making it necessary to keep the paraffin lm at a minimum of thickness; and, considering the ultimate diameter of theA wire as the working limit, whatever thickness is taken up by the paraiiln lm is so much less thickness of nre-retarding material. It has also been proposed to'impregnate the braid with paran or a substitute wax and to coat this with a name-stop material such as stearin pitch, the theory being that the melted stearin pitch, being applied at a higher temperature than the melting point of the Y paraffin, will melt the paraffin and some of it will nd its way through thecoating of stearin pitch sufficiently to make the surface of the coating non-sticky without destroying its fire-retarding quality. This also has its objections: the dilculty of controlling the intermixture of the paraifln with the pitch; the inability to secure a unicoating which would destroy the name-retarding quality of the coating at such regions, and thereby cut down its total fire-retarding effectiveness; the braid is left, for the most part, wholly impregnated with the paraflin which constitutes virtually a candle the burning of which is checked only by a very thin lm of dre-retarding material which itself has, for the most part, too great a paraffin content to be eiective; and the inability to produce colored wire without greatly increased cost. V v

One object of my invention is, to provide and produce a wire which overcomes these objections in parafn-over-pitch and in pitch-over-paraflln wiresx but which will still give the desired-nonsticky, lubricated.v slick nished" surface while retaining a relatively fire-retarding character.

Y 1 achieve'this solution to the problem by using' -an impregnation and a coating, the compositions of which in general are substantially the same or at least wherein the impregnation is as nonthe impregnation and coating compositions which I use preferably contain both stearin pitch, or a substitute, and paramn, or a substitute. there being enough wax-like material to make the composition non-sticky and slippery and to impart a slick finish" and enough stearin pitch or a substitute to make the composition nevertheless sufficiently ilame-retarding. Apart from the aspect of coloring the wire (which I shall presently discuss), the advantages of using a coating composition having substantially the formula or characteristics of the impregnation, as compared with a coating of parafiin or substitute wax-like material.- include: The greaterV flexibility of the coating; more fire repellent protection; elimination of ble surface film; better binding of the coating to the impregnation; and rendering immaterial the possibility of contamination between the coating and impregnation.

Referring now to the problem of code wire in the assortment of colors required by the trade, where the impregnation composition includes pitchand stearin pitch is most frequently used to give a iiame-retarding character to the wirethe color given the wire is black, -or at least very dark. Pigments are too expensive to make it feasible to add suillcient quantities to the impregnation composition. Hence it has been proposed to paint the impregnated wire before adding the transparent parailin coating. This has numerous objections: the added, expense lof another process; the cost of the-paint itself; the cost of the additional apparatus necessary for the paint dipping; the dulling eifect of the parafiln, even though normally transparent. over a bright color; the increased tendency toward white ilakey superilcial appearance of the paraffin coating and its tendency to ilake olf-due to the poor binding with the smooth surface of the paint: and, in some instances,l crumbling of the paint itself.

Thus another objectof my invention is the provision and production of a wire which is colored, wherein these objections are avoided and where-the additional expense of coloring the wire is minimized and the color ismade of lasting brightness without danger of streaking by superficial abrasion. To this end, I use, in so far as practicable; the same base composition or formula for the imtion'that I do for the coat ingandIaddthepigmenttothecoatingonly. This gives an ampie thicknessof colored nim. butastheamolmtofcoatingcompositionused per thousand feet of wire is considerably less than the amount of impregnation used per thou- -sand feet. a great saving in the cost of pigment claimed in my Patent Number 1,891,501 of December 20, 1932, of which this application is a continuation in part. 'I'he usual method of coatingawirehasbeentopassaconsiderable length of the wire back and forth over sheaves through a sizeable vat containing the melted coating material,passthestrandorwirethroughadie, wiper or similar device to remove the excess material and to control the thickness of the coating,andthentodryitbyairthewire over sheaves-for a distance of some thirty to seventy-ve feet. Some of the objections to coating by dipping are: the wire remains in the melted coating composition long enough to permit heat to be imparted to the impregnation to 5 a point of injuring it; the coating material may be contaminated by the impregnation; the excess coating must be removed down to the desired diameter or thickness of film; the die or other means of removing the excess coating may cut 10 through the coating and bare the impregnation; the resulting finish must be a dull, wiped surface whether or not that kind of a finish is desired; and, because the wires pass back and forth through the vat containing the coating mate- 15 rial, it is difilcult to provide proper agitators to keep the material uniform without interfering with the wire, and therefore the composition as coated often varies due to the settling out of solids. 20

Another method of treating, somewhat difierent from the dipping process, has been to pass the strand through a vat or receptacle containing the melted coating material and then-instead ofpassingwireupthroughthesurface ofthe25 liquid and to the die orscraper-to pass the wire directly through a discharge die in the side wall of the vat or receptacle. From the discharge die, the wire emerges directly into cooling water or passes through a longreach $0 through cool air to a sheave. Such methods havebeen used principally for impregnations. If used for coatings, they'would be subject to numerous objections: To keep the melted material from running out through the discharge 35 bore as the wire is pulled through, the bore has to be small enough to compress or squeeze the immersed wire suiiiciently tb scour the bore of thedie. Unlessthewireissqueezedsothatthe braidorsolidpartofthewirescoursthebore of the die. the relatively cooler die ,will cause the material to congeal and deposit within its bore. Thisinternaldepositontheborebuildsupuntil the scouring action again takes place against the braid. Thus no control is had for the thickness 45 ofthenlmofmaterialbeyondthediameterofthe tension necessary to draw the wire through the die. Thesemethodswouid notoperate eifectively forcoatingevenifthediameteroftheboreofw the discharge die were greater than that of the braid, for the following reason: The hot impregnation material-whether applied simultaneously with. or immediately preceding, the coating layer-would be absorbed in so great an amount per 55 foot of wire that the resulting temperatures at the outer regions of the wire at the braid would be too high to congeal the material being applied. The die would be relatively colder. As a result the fluidity, through a cross section of the bore of the die, would be greatest-not at the surface of the bore-but at a region radially inwardly of the surface of the bore. The rapidly moving wire and the stationary parts of the die would part at the region of greatest fluidity. Since this would not be at the surface of the bore, but rather at the surface of the braid, the material could not be applied to a substantially greater diameter than the thickness of the braid, and in am event it would not be accurately controlled.

Another objection to the use of these'treating processes for coating relates to the problem of cooling or setting the coated material. It is n that the coated material set before it touchesthesheaveorothermetaipart. Ifthe76` i 2,Q07,441 wire is to be cooled by air after it emerges from the die, a very large amount of floorspace must be taken up with one straight reach of wire some thirty to seventy-five feet long before it comes to its first sheave. In `those methods where the wire emerges from the die directly into a bath of cooling water, the water further chills the discharge end of the die, building up a restrictive neck within the end of the bore of the die, due to its increased congealing action with the result, already explained, of scraping the material to be ,deposited down to the surface of the braid. Another objection to these -processes is that it is necessary to have acoating material which melts at a lower temperature than the impregnation material. i

A further object of vmy invention is an improved method of coating which eliminates these objections. `More specifically the objects include: a uniform controlled thickness of coating film; less tension for pullingg the wire through the apparat'us; greater permissible speed; permitting the use of a coating material with the same or higher melting point than that of the impregnation;- the use of -a tempering bath of water without chilling the die with its consequent objections and before touching any metal parts such as a sheave; a slick name finish for the coated wire; less dribble from the die; practically no scrapings to be returned for remelting; and adaptability to oblique or vertical positions .for the traveling wire. i

In the method by which I achieved these objects, I preferably pass a wire, the braid of Which'has been previously impregnated and cooled, a short distance through a melted body of the coating composition and thence discharge the wire through a bore of substantially the diameter desired on the finished product, through a short intervening air gap, down through the 'surface of, and into the body .of, atank of tempering water where it passes over sheaves and on to the winding spool. The bore of the discharge die is kept at a temperature higher than the melting point of the coating material. -No cooling water comes in contact with the discharge end of the die. Hence its temperature throughout is in excess of thel wire exposed at any one moment to the melted coating material is too short and the speed at which the wire passes is too great, to permit the body of the wire andA its impregnation to be heated to-any appreciable extent by the momentary submersion in the' melted coating composition. Therefore, as the wire passes through the coating apparatus, the body of the wire and the impregnation do not rise in temperature enough to relinquish, by melting, the layer of coating material which has deposited upon it, but continues to accumulate a congealed layer of the material. Should this congealed layer be of greater diameter than the bore of the hot die, the layer is either scraped or melted down to the bore of the die and passes through the die with the dividing or parting at the surface of thel bore.

. material has not built up to the diameter of the bore, 4but leaves a substantial nlm of liquid melted material therebetween',v which nlm is preferably the diameter.

longitudinal verticalsection:

lessened toward the discharge end of the bore bythe continued accumulation or increase of the layer of congealed material. The melted material immediately adjacent the surface makes an effective lubricant for the easy and rapid pwage of the wire.

For commercial code wire the diameter of the bore of the die may be .012 inches greater than the diameter of the impregnated braid as it enters the apparatus. 'I'his provides a coating film of approximately .006 inches thick. As the wire emerges from the discharge end of the bore the greater portion of the thickness of the coating is in congealed form. The remaining portion is so thin a film that it also congeals so quickly that there is no opportunity for it to accomulate eccentrically of the Wire or to drop from the wire. However, it is not necessary that the .bore of the die be larger than that of the incoming wire to be coated. In fact I prefer, as herein after disclosed, in applying a very thin coating to use a discharge die of a bore of the same size or even a trie smaller than the incoming wire. 'I'his may be done when the incoming wire is compressible. In code wire where there is a braided jacket over' rubber insulation, the wire is permanently .ensmalled by forcing, the braid into the rubber insulation. Thus I am enabled to'take an impregnated or coated wire of a given diameter and apply to it an additional coat without increasing And this coating may be a color coating of a wax-like compound like that of the l undercoat or the impregnation.

This is of especial advantage in making the two color coded wire disclosed in my copending application Serial No. 642,378 led November 12, 1932. My present applicationis also a division thereof as to the apparatus. In said copending application I have shown a series of wires for code work wherein the different colors used may be confined to only a few readily distinguished colors but still provide for a large number of readily distinguished wires. This I do preferably by theluse of two color coatingsan under coating of one color and an outer coating of a different color-which are combined in different coinbinations. Fully to identify a given wire, a small region of the outer coating is scraped away to re` veal the color of the under coating.y Using eight primary colors, this gives some sixty-four di'ierent combinations. By using three .color coatings, some iive hundred dierent combinations are possible. As an alternative, instead off a full outer color coating, a colored streak may be applied. l

The present'application is concerned primarily with apparatus for carrying out the previously described methods and for making the above described wire products. 'I'he apparatus herein disclosed is not however necessarily limited to such specific method or product.

The foregoing with further objects, features and advantages of my invention are set forth in the following description of a specific preferred embodimentthereof reference being made to the accompanying drawings wherein:

Fig. 1 is a side elevation of the coating appara- Y tus of my invention with its associated supply reel,

tempering tank and winding reel;

Fig. 2 is a plan view thereof;

' Fig. 3 is a detail view of a portion of the apparatus shown in Fig. 1 but on an enlarged scale, the coating material reservoir being broken into Fig. 4 is a longitudinal vertical section of the applicator itself;

Fig. 5 is a transverse section taken on the line 5-5 of Fig. 3 through the applicator and showing the control valve;

Fig. 6 is a detail elevation of the valve taken on the line 6-6 of Fig. 5;

Fig. '7 is more or less a diagrammatic longitudinal section through the bore 26h of the discharge die 26 and upon a greatly enlarged scale;

Fig. 8 is a side elevation of a portion of the finished wire product with the several layers progressively removed;

Fig. 9 is similar to Fig. 8, but shows a modified form of wire wherein an outer colored streak rather than .a full color coating is applied to the surface of the wire; and

Fig. l0 is a cross section similar .to-Fig. 5, but including only the chamber of the applicator and showing a modified construction adapted to the application of an outer streak such as shown in Fig. 9.

The apparatus shown in Fig. l comprises a supply reel of wire III to be coated, the reel Il being, mounted to unwind as lt rotates against the retarding influence of the usual friction brake I2,which may be a weighted rope wrapped one or two turns about the shaft of the reel. From the reel the wire I0 is led over a sheave I3 mounted on a suitable frame i4 and through the applicator i5 down into a tempering tank I6, entering the body of tempering water I1 obliquely through its surface, thence over sheaves Il and I9 within the vat, over a final sheave 2li and to the winding reel 2| which is driven by a pulley 22i` and belt 23 from a convenient source of power. The applicator l5, referringl to Fig. 4. comprises a body, which may be of steel, penetrated bya longitudinal hole 24. One end of the hole 24 is closely fitted or plugged by a cylindrical anterior die 25 and the other end by a posterior or discharge die 26. A cylindrical chamber 21 is left between the two dies. As shown in the transverse section oi' Fig. 5 the applicator body may be split on a plane along the axis of the dies leaving lower and upper body members 2l and 2l' held together by cap screws 29 and alined by suitable dowels. The purpose in halving the body is to facilitate cleaning and the removal or substitution of the dies.

'Ihe dies have alined central bores 25h and 26h respectively. The diameter of the discharge bore 2lb is substantially that ot the desired overall diameter of the coated wire. The diameter of the discharge bore 2Gb may be that of the incoming wire plus the coating to be deposited on it, as illustrated in my said patent; but it is also possible and in some instances preferable, as here illustrated, to have the discharge bore 2Gb of the same diameter as the incoming wire. In that case a shorter bore is more satisfactory.

The anterior bore 25h is conveniently and preferably slightly greater than the diameter of the entering wire. The applicator is mounted obuquely on theframe u in such position that the center line of the bores coincides with the center line of the straight region of wire determined by the sheave i2 and the water vat sheave As shown in Fig. 5 there is a communication between the chamber 21 of the applicator and the bottom oi' hopper-like reservoir I0 by means of the pipe connections 2| and 32 and a cut-o valve 22. YThe reservoir 2l is either round, or as here shown, square in cross section, the lower part being of inverted truncated pyramidical form. The reservoir 20 is divided into an inner chamber lili and an outer chamber 30o by a partition 34 of perforated sheet metal. The partition 34 -is of square perimeter with its lower edges contacting the sloping sides of the hopper portion of the reservoir 20l and the upper edges extending to the top of the reservoir. 'I'he reservoir ls heated to keep the coating material well above its melting point by any suitable heating means4 such as a steam jacket, or, as here shown, electric heating elements 35 mounted on the exteriors of the sloping sides of the reservoir.

, The coating composition, or its ingredients, are -from time to time put into the outer chamber 300' through the top of the reservoir in solid or powdered form. The partition. acts as a screen to prevent the passage of the composition into the inner chamber until the composition has been melted and lumps eliminated. I prefer to employ an agitator 36. It may be carried by a shaft 31 depending from a bevel gear box Il at the driven by a motor 38.

When there is no wire in the applicator Il the.

melted composition would run out through the bores 25h and 2Gb. To avoid this I provide an automatic control for the valve to shut it ofi when the wire has run out. This control preferably is a sheave 4l riding on the wire Il and carried at one end of a lever 4| which is pivoted at 42 on a bracket from the frame I4. The other end of the lever 4i is pivotally connected to the slotted end 43 of a link 44 connected to the end of the valve lever 45. The slot 42 in the link 44, as shown in dotted lines in Fig. l, permits a certain up and down movement of the rider sheave 40 tocompensate for the different elevations of the wire Il between the full and empty positions of the supply reel Il, without actuating the valve. However when' the wire runs of! the supply reel Il, the rider lever 4l drops down to a vertical position and pulls the valve lever 45 over to closed position. This immediately cuts olf further supply of coating composition to the applicator chamber 21 and leaves but a relatively small amount to run out of the bores of the dies. 'I'his slight loss may be caught by drip pans not shown. In threading wire from a new supply reel, the rider sheave is not lifted up to position on the wire until the threading has been completed and the wire is ready to be pull through the applicator. y

The body of the applicator .and the dies are maintained at a temperature well above the melting point of the coating composition by electric cartridge unit heaters 4l inserted in holes drilled transversely through the body. As shown in Fig. 4 these heat units are disposed close to the dies. 'Ihe dies fit the opening 24 in the bod'y snugly so there is a good heat transfer from the body to them. One pair of cartridges is disposed opposite-the anterior die 25, one opposite the chamber 21 to keep the contents hot and two pairs are disposed opposite the discharge die 26. It is particularly advisable in my method to keep the surface of the discharge bore 2Gb hot enough throughout its length to melt the coating composition.

I the embodiment oi.'v my invention here disclosed, the wire supplied to the applicator by the.

supply reel Il consists (see Fig. 8) of the usual copper conductor Il, layer of rubber insulation 5j, fabric braid 52 and impregnation i2. Manyl Among other impregnation materials which may be used, is the usual stearin' pitch with little or no other ingredients added. My coating need not be applied directly over the impregnation. For example, as previously mentioned, a water proofing impregnation of asphalt land pitch is sometimes used with, a coating of stearin pitch over it. Many features of my invention are applicable to the application of the final coating over this intermediate coating of stearin pitch. However one feature of my invention is concerned with the composition used as the impregnation. The material with which the wire may V have been impregnated before being passed through the coating apparatus of ,my invention nated and of course cooled to room temperature.

Should wire be fedlto my coating apparatus directly from the impregnating apparatus, the wire should, for the fullest advantages of my 'apparatus and method, be properly cooled for reasons heretofore and later explained.

The coating composition employed is preferably of the same composition, except for the addition of .pigment if the wire is to be colored. For'certain colors, the filler oi' the composition may be replaced by pigments of such bulk that they themselves form fillers.

My coating method and the operationof my apparatus is as follows: A previously impregnated and cooled wire I0 is unwound from the supply reel l I, passed over the sheave I3, through the alined bores 25h and 2Gb of the. dies of the applicator I5, through the water tank I6; around the sheaves I8 and I9, over the' sheave 20 and to the winding reel 2 I.` Then the rider sheave 40 is liftedfon to the wire I Il. 'I'his opens the valve 33 and permits the melteld wax to run downinto the chamber 21 of th'e applicator. 'I'he bore 25h being somewhat larger than the wire I0, air is displaced throughv the bore 25h by the melted coating composition entering the chamber 21 until the level of the liquid seals o the lower edge of the bore 2517. The head of liquid conrposition in the reservoir 30 compresses the .trapped air to raise the liquid level to a slightly higher level. I have not found it necessary to provide a vent from the top of the chamber 21 to the `height of theuquid level in the reservoir an to f remove the trapped air.

The winding reel -2I is then set-in operation pulling the wire rapidly through the applicator I5. Once the wire is in motion, there is no leakage of coating composition through the anterior bore 25h, despite. the clearance between the bore and the incoming wire. 'I'his is because the wire,l being cold immediately starts to con-V geal Asome of the melted composition onto its surface, thereby restricting the amount of clearance. The factor of surface friction between the melted composition and the congealed composition-in so small an annular-region. together with the speed of the 'incoming wire, preclude the melted' composition flowing back all of the way through the length of the bore 25h..

Unless some means be provided for maintaining a constant speed (the expense of which I have not found necessary), the speed of the wirev will vary because of the increasing diameter of the coil as the wire is wound. I nd however that the speedused in wire treatingpractice is satisfactory, ranging from two hundred to three hundred feet per minute at the start,

and four hundred to iive hundred'feet per minute l at the end, of the conventional five thousand foot run, with my method, this speed may also be substantially increased.

will range between 150 and 180 F. 'I'he reservoir is preferably maintained at a temperature of about 250 and the applicator at about 300.

The melting point of the composition described The incoming wire -being relatively cool-at room temperaturea layer of the melted coating 'composition will, as previously described, be con gealed upon the surface of the wire as it passes through the chamber 21. In Fig. 8 this congealed layer is illustrated somewhat diagrammatically. The wire passes through the relatively short chamber 21 so quickly that the lcongealed layer, I believe, continues to accumulate throughout -the length of the discharge bore 26h. The

wire is not in the chamber 21 or in contact with y the melted composition long enough for the coldV wirev toy be heated even at its surface lto any surface of the discharge bore 2lb, then the melt--P ing point of the coating composition, a free uidity of the composition will vbe insured at the surfacev of the bore, despite the congealing action.

.This prevents the layer of congealed coating material building up to the full diameter of the bore while the wire is in the. bore. No deposit can build up on the surface of the bore tending to restrict its effective size. By maintainingan outer region of melted iiuid coating compound throughout 'the length of the discharge bore 2Gb, 'the wire is insured an excellent lubrication in its passage through the bore, with the result that greater speed can be obtained and less tension is required on the wire.

As suggested by the. diagram of Fig. 8, the va.- rious factors-the temperature of the incoming wire, the temperature of the die 26, the consistency of the coating material, the speed of the wire, the length of the die 28, etc.-`are so controlled that, by the time a given section of wire reaches the discharge end ofthe borel 2Gb.. the layer of congealed coating material has built up to such a diameter as to leave only. a minimum clearance from the surfacesof the bore 2Gb for the outer film of fluid material. 'Thus as the wire emerges from the discharge end of the bore 26h it comprises the core of impregnated wire, a coating of congealed material and a surface fllm of liquid melted material. Thevsurface lm is preferably of considerablelesser thickness than the coating of congealed material.- 'I'he emerging iilm of melted-material is so thin and evenlv distributed that in the short interval of time available the force of gravity does not have an opportunity to --concentrate the melted material on the underside' of the wire to. any appreciable extent. Ihe emerging iilrnA of melted coating congeals before such aberration can take place to any appreciable extent. The rapid congealing of the emerging liquid film is due to three factors: First, the continued absorption of heat by the relatively cool body of the wire, second, the chilling effect of the air about the emerging liquid film and third, the slightly subsequent immersion in the tempered water bath I1.

As here illustrated, the discharge bore 2Gb is of slightly less diameter than that desired for the wire after coating.` Preferably it is the same as that of the uncoated wire. In such case the thin lm 55 of the meltedl coating material is definitely drawn into the discharge bc/re 2Gb be`- tween the wire and the bore. The thickness of this film is not added to the radius `of the resulting wire but is absorbed by the material of the wire assembly. This is chieiiy by the impression of the braid into the rubber insulation. Thus the emerging wire as soon as the liquid coating has set after it leaves the hot discharge bore 2Gb, is of the same diameter as the incoming wire. To a certain extent, depending upon the characteristics of the rubber insulation and of the braid, the diameter of the dischargebore 2Gb may be even less than that of the incoming wire.

. Ordinarily it is of no object to have it less, except and set.

it may be necessary to offset the tendency of the wire assembly toome back toward its normal ,size after compression.

By inclining the direction of travel of the wire through the applicator, the wire may continue on down through the surface of the 'water and through the body of the water so that before it reaches the sheave I8 the coatingis tempered By that time the contact with the sheave will not destroy the slick flame finish given the wire. Itis important to a proper finish of the wire that the coating be set before contacting a sheave or other part. 'I'his has presented a serious problem in the past, which has often been met by running the coated wire from a discharge die through a long air space before it touches a sheave or other part. This has required a considerable amount of factory space. It has also involved-along length of wire in the coating apparatus asa wholeat any given instant. The length of wire required to thread a new reel of wire in the coating apparatus is generally of an unworkmanlike appearance both 'at the beginning and the end of the run of a reel of wire. One feature of my invention is that this threading length, which may be imperfect, is greatly reduced. ,A

If desired, the wire may be polished by the usual leather or rope wiper after the initial immersion in the water. Preferably, as shown in Figs. 1 and 2, I use a hot die I8 arranged between the sheaves Il'and I9,A so that the wire is im- ;nerseid again following the action of the nish- H The inclination of the wire as it passes through the applicator may be increased or decreased as desired-even being increased to the vertical. ,As it approaches the vertical, the anterior die becomes unnecessary if the chamber 21 is placed at such a heightor made of such a length that the head of melted material in the reservoir l0 does not cause'the meltedlmaterial to overflow the chamber-B..

The ultimate over-all diameter ofv the coating is substantially, but not wholly, determined by the diameter' of che discharge bore.` .within the' length ofthe discharge bore there is a certain.

frictional lag between the nlm of melted and the walls of the bore. This tends to hold back some of the liquidfllm, with the result that the liquid nlm, when it emerged from the end of the discharge bore, would be a trifle less than the diameter of the bore. This tendency however is largely offset by the pressure of the head `of liquid composition in the reservoir which substituted. Slight variations in the thickness of the coatings on a given size of wire may be produced by varying whichever of the previously mentioned factors is most convenient.

While I prefer wherever feasible to use substantially the same composition (except for pigment) in the impregnation as in the coating, it is expedient, when the coating is to be of certain colors, to substitute a coating composition where the active ilame-retarding ingredient is something other than a very dark pitch such as stearin pitch. The expediency of this substitution is particularly true of a white wire, and to some extent with blue and yellow wires if it is essential that the colors be bright. In such instances a base may be substituted which has a characteristically light color. Such substitution however should still preserve for the coating the characteristics of ame-retarding, non-'stickiness; sumcient slipperiness and slick" finish. The advisability or expediency of such a substitution may be determined by balancing, on the one hand, the added cost of the substitute as compared ,with the pitch-and-wax composition previously described, against, on the other hand, the increased cost of the relatively expensive blue, yellow or white pigments in the quantities which would be required satisfactorily to overcome the blackness of the pitch. Where substitutes are used for the coating composition, waxes, resins or other ingredients may be added t o control the viscosityl and melting point preferably to the same melting point as that of the impregnation.

I have previously mentioned that one of the advantages in treating the braided wire in two processes-an impregnation and a coating-even though the impregnation composition and the coating composition be the same except for pigment, is the saving in the cost of relatively expensive pigment. This however is not the only advantage. An important advantage, apart from the phase of color, is this: If the impregnation and coating were combined into a single operation, the relatively large mass of hot melted material absorbed by the braid would so raise the temperature of the wire at the region of the braid .as to preclude an effective congealing of the material toward the region of the ultimate diameter or the nnisned tres/cedwire. 'rms wouid tend toprevent bringing the layer of congealed -material sufilcientlyclose'to the surface of the In my coating method a discharge bore of some v appreciable length is advisable for these reasons:

there would be less region of frictional lag of the melted film, with a result that the head of liquid material could not be so well balanced .by the frictional lag, and hence the iiuctuation in the liquid head by the addition of the materiallto the reservoir from timeV totime would too readily vary the outow of melted material from the discharge bore; and, as the process of building up the layer of congealed material could not be carried forward to any appreciable extent within the length of a short bore, it would be 4diilicult if not impossible so to control the thickness of the layer of congealed material that by the time it got to the short bore itw'ould leave an intervening space of the proper thickness f or the film of melted material-if l.this space were insufficient there would be a damming up at the entrance end of the short bore which would block the flow of melted material, and if the space were too great, the layer of melted material emerging from the short discharge bore'would be too thick to be congealed before it had flowed to the underside of the wire to -form a coating of eccentric cross section and perhaps also to permity some of the liquid materialto drop off the Wire.

When the wire is to be coated with not merely one primary color, but a combination of colors arranged as superposed coatings, an additional4 color coat is placed on the wire. Referring again to Fig/8, I have shown a secondary coating 54 of red, for example', placed over the primary coat- 4ing 54 of yellow, for example.' The secondary coating may be applied in the same way'as was the primary coating.

In Fig. 9 I have shown an alternative form of two color wire where the secondary color is applied as a streak orplurality of streaks 54 instead of a complete secondary coating. ,This has ,the advantage of readily identifying the wire Without removal of any coating.

In Fig. 10 I have shown a modication of thev portions of the wire. 'I'husthe coating material' is applied as a pair of streaks 54" -only to those regions of the wire which are not thus massed out by the member 60. It' the arcuate regions of the discharge bore 2Gb in line with the unmassed region be arranged on a diameter substantially that of the incoming the streaks 54" will v be imbedded or compressed ,into the wireA assembly for the same reason, as previously described,

out enlarging the diameter of the wire.

that thecompression die applies a coating with- While I have described and illustrated this' specific method, apparatus and article, I contemplate that many changes maybe made therein vwithout departing from the scope or spirit o! myinventiom` I claim:

1. A coating apparatus comprising a heating reservoir for meltedvcoating material, an applicator casing, a chamber therein, means for conducting melted coating materialfrom the reservoir to the chamber, aligned anterior and posteror bores in the casing and. disposed in a downward oblique position, the chamber being disposed between the bores, means for heating the casing to maintain the coating material in the chamber in melted state and for maintaining the surface of the posterior bore at a higher temperature than the melting point of the coatving material, the posteriorl bore being of approximately4 the diameter of tn'e desired coated article and a tank of tempering liquid disposed at a lower elevation than the bore's and at such position that the surface of the liquid is obliquelyv intercepted by an extension of thevaxis of the aligned bores, means for feeding to the anterior bore the strand-like article to be coated and ymeans for pulling the-wire` through the applicator and the tempering liquid, the applicator being constructed and arranged to keep the wire out of contact with any solid in passing from the discharge bore into the liquid.

l 2. In awire coating apparatus the combination of a receptacle for melted coating material, means for guiding a wire therethrough including a discharge bore leading from the receptacle of approximately the diameter of the desired coated wire and ymeans for maintaining the surface i of the discharge bore ata `higher temperature than the melting poin't of the coating material throughout its length whereby the wire will emerge therefrom enveloped in a lm of melted material.

3. YA wire coating apparatus comprising a metallic body having a hole therethrough, the body being split along the hole, a cylindrical anterior die member disposed'in the one end of the hole Y and making a uid tight seal therewith, a posterior die member disposed within. the other end of the hole and making a vfluid tight seal therewith, .the adjacent ends ofthe die members being spaced apart leaving a chamber, aligned Wire receiving bores through the anterior and posterior die members, the posterior bore being of approximately the same diameter as desired of .the coated wire, conduit meansfor supplying melted coating material to the chamber and the boreof the posterior die, and means for maintaining the walls ofthe chamber and the sur- Yof the water, the receptacle having a discharge b'ore of approximately the diameter ofthe desired coated wire with the axis ofthe bore aligned with' the center line of the/reach of .wire as determined by the sheaves, and means for main- -taining'the surface of the discharge bore at a temperature above' the melting point of the coat- ,ing material whereby the wire emerges from the 10 ing a discharge die, a heating device applying heat to the chamber body to maintain the material thereon above a melting temperature. and another heating device applying heat to the die body, the second heating device being at a shorter thermal conduction distance from the discharge bore than is the first heating device and being constructed and arranged to maintain the discharge bore at a temperature higher than the melting point of the material.

ALBERT T. CANDY, Jn.

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