US2238575A

US2238575A - Apparatus for coating articles such as wires with liquid coating compositions

Info

Publication number: US2238575A
Application number: US266384A
Authority: US
Inventors: Alexay Adalbert
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1939-04-06
Filing date: 1939-04-06
Publication date: 1941-04-15
Anticipated expiration: 1958-04-15
Also published as: BE471852A; GB530217A

Description

April 15, 1941. A. ALEXAY 2,238,575 APPARATUS FOR COATING ARTICLES SUCH AS WIRES WITH LIQUID COATING COMPOSITIONS Filed April 6, 1939 2 Sheets-Sheet 1 F1 1. T'O TAKEUP REE is Attorney.

April 15, 1941.

APPARATUS FOR- COATIN G ARTICLES SUCH A3 WIRES WITH LIQUID COATING COMPOSITIONS Filed April 6, 1939 A ALEXAY 2,238,575

2 Shets-Sheet 2 1h ventor:

Adalbert Alexay,

His Attorney.

Patented Apr. 15, 1941 UNITED STATES P TENT- OFFICE- APPARATUS FOR COATING ARTICLES SUCH AS WIRES LIQUID COATING COM- POSITIONS Adalbert Alexay, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application April 6,1939, Serial No. zeessi (c1. ill- 32) 13 Gialms.

This invention relates to apparatus for coating elongated articles such as wires and the like with liquid coating compositions, for example enamels, varnishes, lacquers, etc., and more particularly is an improvement upon the wire-coating apparatus disclosed and claimed in the copending application of Edward J. Flynn, Serial No 153,612, filed July 14, 1937, and assigned to by reference to the following more detailed (18- scription when considered in connection with the accompanying drawings, wherein- Fig. l is a view showing somewhat schematically coating apparatus embodying the invention;

Fig. 2 is a perspective view, partly in section, of a portion 0! the apparatus for applying and forming the coating upon the wire or other a1:- ticle to be coated;

Fig. 3 is an enlarged perspective view of one form of die embodying the invention;

Fig. 4 is a view similar to Fig. 3 of another form of die embodying the invention; and

Fig. 5 is an enlarged fragmentary view taken along the line 5-5 of Fig. 4 and shows a preferred construction of the orifice of the die. An enlarged fragmentary view of a wire being coat ed with liquid coating material is shown as pass ing upward through this orifice.

In the manufacture of electrically insulated metallic wires wherein the insulation is of the so-called organic enamel type, the wire usual ly is passed continuously through a bath of enamel, varnish or similar coating material, for example an oleo-resinous varnish. On leaving the bath the coated wire is treated; for instance bypassing it in a, vertical upward direction through a heated oven, to evaporate the solvent and to harden the coating. Appropriate temperature and atmospheric conditions are maintained in the oven so as to produce on the wire a hardened film having the desired characteristics. With ordinary wire-coating operations,

it is necessary to coat the wire a. number of times, usually from four to eight times, in order to obtain an insulating layer of the desired thickness. The method is time-consuming, thus lowering the production capacity of the apparatus, due to the numerous coats required. Also, solvent losses are high, since a high ratio of solvent to resin is necessary to produce an enamel or varnish of suitable viscosity for application to the wire; Further, some difilculty is encountered in controlling the thickness of. the individual coats, and thus the total thickness, due to such inrluencingvariabls as, for example, the rate of travel of the wire through the bath, and the viscosity and surface tension of the liquid coating composition. Moreover, the application by conventional methodsof a high viscosity varnish, such for instance as a solution comprising 15 to 20 per cent by weight of a polyvinyl formal resin in a suitable tice.

A method and apparatus for obviating the above described difliculties encountered in the use of conventional wire-coating apparatus are disclosed and claimed in the aforementioned c0- pending Flynn application. In accordance with the Flynn invention a wire-coating device, which is described in the Flynn application as a freely movable, self-centering die, is used as an essential element of wire-coating apparatus, thus permitting the application to wires of highviscosity coating compositions that previously could not be applied successfully to wires.

The present invention is an improvement upon the Flynn invention. More particularly, my invention provides improved means for coating wire or the like with liquid coating compositions, especially with high viscosity varnishes or enamels. By practicing my invention, the wire may be uniformly coated, the thickness of the individual coats and thus the total thickness definitely may be controlled, the number of coats required to attain a desired thickness may be lessened, the coatings may be applied at a high rate of wire travel, and solvent losses may be decreased.

With further reference to the drawings there is shown by way of illustration in Fig. l a somewhat schematic arrangement of coating apparatus embodying the invention. As shown in this figure an elongated article to be, coated, specifically a wire his drawn from a pay-cit reel (not shown) over a guide sheave 2 through a split enameling trough or container 3, the construction of which is shown more clearly in Fig. 2.. In operation,

solvent, is diflicult in pracwire is treated to harden the coating thereon. In

the case of an enamel-coated wire this may be done, for example, by passing the coated wire through a drying or baking oven 1. Any suitable design of baking oven may be employed, and

the oven may be heated with gaseous combustion products, electric heating units or by any other suitable means. The wire with its heat-hardened insulating coating thereon is passed over a pulley 8 to a take-up reel (not shown).

Any suitable means may be employed to feed the liquid coating material 4 to the trough 3.

removable cover 23 which is made in two sections as shown, suitable openings 24 being provided for passage of the coated wire. The openings 24 preferably are so made as to reduce to a minimum the escape of volatile material from the coating composition and yet large enough that the wire, with any swaying movement during normal operation, will not contact the rims defining the openings. With such a cover the possibility of contamination of the coating material is'minimized and there is less oxidation of ,the varnish or other oxidizable coating mate- A simple means that has been found to be especially effective is shown in Fig. 1. As there shown a supply reservoir comprises a receptacle III, which is filled with the liquid coating material and is suitably retained in an inverted position over the pan II. The pan ll connects with the trough 3, by means of a conduit l2, so that as the coating material in the trough-3 is consumed, the liquid level in the trough will be maintained by a now of material from the receptacle Hi. This feed method lessens the possibility of contamination of the coating material. It reduces to a minimum the period of time the coating material is exposed to the air before application to the wire. Hence, the method is particularly advantageous for use in the application of varnishes or other coating materials that change in properties, due to oxidation or for other reasons,

upon prolonged exposure to the air.

The trough 3 may take any suitable form, so

long as the die '5 is in operative relationship with it. One form of trough that may be used in carrying the present invention into efiect is shown by way of illustration in Fig. 2. As shown in this-figure, the trough 3 comprises a container adapted" to receive a supply of coating material and having in its bottom wall an opening adapted topermit the passage of a wire therethrough and, in addition, means for sealing this opening to prevent the leakage of coating material during operation of the apparatus.

More particularly, the trough shown in Fig. 2 comprises two separable sections which are held together by suitable means, as by springs,

clamps, etc. (not shown). The opening l3 between the'sections is sealed by suitable packing material N which may be formed, for instance of a flexible tubing l5, e. g., a rubber tubing, covered with a layer l6 of soft, non-shredding material such as chamois, Seal supports H, which may be for example metallic rods, may be used to facilitate retention of the packing material H in place. At the bottom of the trough conveniently may be placed a pad l8 of compressible, absorbent material such as felted wool to absorb any small amount of coating material that may leak at any time from the split trough due to an imperfect seal. The pad I8 is held in place by suitable means, as for example by the fastener l8 and the pad holder 20, which latter is fastened in position by the bolt 2|. A washer 22 is interposed between the head of the bolt and the pad holder.

The trough 3 advantageously is fitted with a rial that is employed than otherwise would take place. Further, the cover reduces to a minimum the solvent vapors, from the varnish, that can escape into the room, and in this way lessens the fire hazard and the health hazard to the operator.

The die support 6 conveniently is a hairpinshaped member upon which the die rests in a loosely fitting position as will be described more fully below. This die support is suitably held in the desired position, for instance by meansof the screw 25 to the upper wall 26 of the trough 3.

The screw 25 loosely engages the bend 21 of the die support, so that in operation the support will be free to move in a horizontal plane with any swaying movement of the wire as it is being coated.

It is sometimes desirable to exchange dies during the coating operation without stopping the movement of the wire. This may be done by suit ably positioning, for instance as shown in Fig. 2, auxiliary die holders above the cover 23, the numerals 6', 25' and 21' designating parts corresponding with those represented by the

numerals

6, 25 and 21. To make the exchange a die is placed on the die holder 6', the die on the holder 6 is removed and replaced by another,

after which the die on the dieholder 6' is removed. In this way dies may be exchanged, when necessary, without in any way interrupting the coating operation.

As shown in Fig. 3 the die is a unitary structure formed preferably from a single sheet of flexible metal which is stamped by suitable means to provide the necessary openings and extension members. This die may be formed by deforming the sheet metal to provide a bottomsurface, and shaping the metal to provide the side walls which terminate at the top thereof in the gable structure. More particularly, the spaced apart side walls 28 extend upwardly and are bent inwardly until they meet at an apex 29 to form a closely fitting, sectionally divided gable 30- The angle on (Figs. 3 and 4) may be varied as desired or as conditions may require. In general, this angle will be within the range of 10 to Especially good results have been obtained with an angle a of 30.

The gable 30 has at its apex an orificeor aperture 3|, which is larger in diameter than that of a wire or the like to be received therein and is located substantially equidistant from the opposite marginal edges defining the gable. The diameter of the orifice 3! that is necessary for applying a desired thickness of coating to wire (or other article to be coated) of a particular diameter with a particular coating material is determined empirically. Its diameter depends not only upon the diameter of the wire to be received therein, but also, for example, upon the required thickness of insulation,'the total number of coats to be supplied, the viscosity and other characteristics of theenamel or coating material employed, and other influencing varifor reasons hereafter given.

' bottom wall.

ables. The orifice 3|. preferably is rounded atits lower edge, as shown by way By forming the die of a resilient material which is unaffected by the liquid coating composition,

as for example of sheet spring steel, sheet phosphor bronze, or similar hard, wear-resistant flexible metal, the bottom wall joining the sidewalls of the die can be deformed to assure closely fitting re-engagement of the sections forming the gable when these sections temporarily are separated. Close fltting of the sections of the gable during normal conditions of use of the die .is further assured by carefully grinding the contacting surfaces to a smooth finish so that a sharp, continuous edge (designated in Fig. 3 as of example in Fig.5,

ing. flanges: 39 adapted to cooperate with the flanges 33 in retaining the die during service use in a loosely fltting position on the die supthe apex 23) is formed. The specific purpose of this sharp apex is to repel, on hydraulic principles, the viscous coating material. Such coating material, if a flat surface were used, would tend to accumulate on the top of the die and around the orifice, thus disturbing the even deposition of coating material on the moving wire.

The bottom wall may be deformed, for example as shown in Fig. 3. In the specific construction there shown by way of fllustration, the lower part of each of the side walls 28 is bent inwardlyand upwardly to form extensions 32 which, are

. spaced apart from the side walls 23. These extensions are bent inwardly and meet to form a of a slot 34, whereby the die andthe wire to be coated may be 1 brought into operative relationship merely by separating the sections forming the gable and bringing the side of the wire through the opening formed by the separated sections and, also, through the slot 34. In forming the slot 34 the bottom section 33 is slotted partway in a direction parallel with the marginal edges of the side walls, the longitudinal center of this slot being aligned with theapex 29 of the gable 30. Advantageously the slot'3l may -take the shape shown in Fig. 3 where its inner end 35 takes the form of a larger opening than is provided by the slot itself; or the inner end of the slot may be merely rounded as shown in the die of Fig. 4.

The segments 36 unite the side walls 28 to the extensions 32. ments is provided with a suitable opening in the central portion thereof. This aids in increasing the spring effect afforded by deformation of the rapid drainage of liquid coating material (including any foreign bodies which. accidentally may be present therein) from the inner portion of the die during use. The side walls and extensions adjacent these openings may be cut away as shown to increase the area of each opening, the rims 31 defining the openings resulting from such construction.

The dies of my invention preferably have means integral with the walls of the die for retaining the d e on a die support. For example. the side walls may be provided with inwardly projecting, suitably spaced apart, facing flanges. In the die of Fig. 3 the upper opposite end portions of each of the side walls 23 are bent inwardly to form spaced' apart, facing flanges 33. Each of the .side walls also is deformed in its central region to provide inwardly projecting fac- Preferably each of these seg- Such openings also facilitate the port 3 (Fig. 2). The openings in the side walls are deflned by the rims 40. These openings, like theopenings in the segments 36, further aid .in the rapid drainage of coating material from the inner portion of the die during service use.

In operation, the die usually is arranged on the die support so that theprongs of the support fit between flanges, 33 and 33, upward movement of the support being limited by the flanges 33. In certain cases, however, the prongs of the support may be fltted beneath the flanges 39, the edges of the bottom section 33 that are parallel with the side walls then serving to limit upward movement of the die duringuse. In all .cases the prongs of the die support are of such diameter. and the support is of such overall width,

movement since, as previously has been menj -tioned, the screw 25 engages only loosely the bend 21 (Fig. 2) of the die support. This freedom of movement of the die in both vertical and horizontal planes aids in centering the die upon the wire during the coating operation.

With further reference to Fig. 2,, it will be noted that asthe wire I passes through the liquid coating material 4 it picks up and carries with it, as indicated at H, a. volume of liquid which is many times the diameter of the wire. This column of liquid is raised upwardly with the wire until it reaches the die 5. The upward force of the liquid, aided by the upward movement of the wire, causes the die to be raised to a. limited extent, the position of theflanges on the die and the diameter of the prongs of the die support controlling the extent of such upward move- Lment. The wire continues upwardly through the orifice 3i and inso doing the applied coating is reduced to a uniform thickness. The excess coating material drains from all open portions of the die, particularly from the ends as indicated by the arrows leading therefrom. As at all times during coating there is a substantial volume of liquid within the inner portion of the die, and also at the sides, ends and bottom of the die, the die actually'fioats most of the timeduring coating upon a mass of coating material. To secure this effect, the weight of the die must not be excessive, the weight depending to a large extent upon the particular coating material employed. A die weighing, for example, approximately 2 grams has been found to be satisfactory in applying to wires an enamel having a viscosity approximating that oi molasses or honey at average room'temperatures.

The particular die construction also is important in effecting optimum self-centering of the die upon the wire, the shape of the upper portion and of the orifice being especially'important from this standpoint. By constructing the die so that'the upper portion is gable-shaped there is obtained during the coating operation a hydraulic effect that aids partly in centering the die with respect to the wire, Also. by this construction, wherein the inclined sections of the gable are held closely together under pressure, there is little possibility of leakage at the apex 29 during normal operation, and hence none of the difllculties which otherwise may result from an accumulation of globules or masses of coating material on the. upper outer surface of the die. The tension under which the sections of the gable are held together is such that they can separate during use to permit passage of enlarged parts (for-example, brazed .portions) of the wire to pass through the orifice ll. During the brief interval when the sections thus are separated there is no appreciable leakage of coating material through the resulting opening. This is due mainly to the two individual sharp knife edges of the gable, which edges, when they meet, form the apex 29 and which, when they are separated, repel the liquid by reason of the inherent characteristic of all liquids to draw away from sharp edges and to form globules due to surface tension and molecular attraction; Furthermore, by reason of the tension under which the sections of the gable are held together during normal operation, instant re-engagement of the sections takes place as soon as the enlarged portion of the wire has passed through the orifice at relatively high speed.

The shape of the orifice is of particular importance in effecting a substantially uniform self-centering of the die upon the wire. I have discovered that in order to obtain an optimum self-centering effect the lower-edge of the orifice should be rounded to provide a. flow nozzle flaring inwardly. Fig. 5 clearlyillustrates this construction, the arrows indicating the flow of liquid beneath the gable 30. As there shown, the walls defining the split orifice consist of a straight portion 42 and a curved or rounded portion 43. While the ratio between the straight and curved portions of thorifice walls may be varied considerably, ordinarily the straight portion is approximately one-third to one-half the thickness of the gable sections, the remainder being rounded. This orifice construction provides a hydraulic self-centering of the die upon the wire not otherwise obtainable and thus assures a more uniform thickness of coating.

It will be understood, of course, thatin coating applications where uniformity of coating thickness is of lesser importance, orifices of other design may be employed without departing from the scope of my invention. In such cases the die orifice may be, for'example, straight-walled, or funnel-shaped, or any other suitable shape, as desired or as conditions may require to conform with the said inherent characteristics of the viscous materials in question.

The die shown in Fig. 4 embodies the same essential constructional features shown in the die of Fig. 3, but differs mainly therefrom in that the die is provided with only a single set of inwardly projecting, spaced apart, facing flanges. These flanges, which are designated by the numeral H, are formed by deforming the side walls of the die in the regions 45 as shown. The central non-deformed portions of the side walls extend upwardly to the edges 46, thence being bent inwardly until they meet at an apex to form a sectionally divided gable similar to that of the die shown in Fig. 3. The die of Fig. 4 further differs from the die of Fig. 3 in that the side walls are not provided with openings such as de-' fined by the rims 40 (Fig. 3) or with flanges such as designated by the numeral 39 (Fig. 3). The die shown in Fig. 4 is especially adapted for use in coating wires, etc., of relatively large diam eter, for example wires having a diameter of 0.10 inch to 0.15 inch, or larger.

economical manner.

The dies of this invention are economical to construct and have along service life. Their use.

makes possible the production of uniformly coated articles such as wires and the like in arapid,

The thickness of the individually applied coats and thus the total thickness definitely can be controlled. The number of coats required to attain a desired thickness is lessened, as compared with conventional wirecoating-apparatus and methods. Also, high viscosity enamels, varnishes, etc., can be applied without dlfilculty to wires at a high rate of wire travel and without detracting from the uniformity of the thickness of coating of the finished article.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A die for applying a uniform film of coating material on a wire comprising a member'having spaced apart side walls terminating at their upper ends in a gable structure, said gable structure having an orifice in its apex to receive the wire being coated, said orifice being of sufiicient size to admit the wire therethrough and shaped to coat the wire with a uniform film of the coating material, and a bottom wall joining said side walls, said bottom wall having an opening arranged to permit vertical movement of a wire therethrough and through the orifice in the apex of the said gable structure. I

2. A die comprising a member having spaced apart side walls terminating at their upper ends in a gable structure having an orifice in its apex. said orifice being rounded at its lower edge and being of suflicient size to admit a wire or the like therethrough, and a bottom wall joining said side walls, said bottom wall having an opening aligned with the orifice in the apex of the said gable structure.

3. A die for coating a continuous length of a moving article such as wire and the like with a film of liquid coating composition, said die comprising a member having spaced apart side walls extending upwardly and being bent inwardly until they meet at an apex to form a sectionally divided gable, said gable having an orifice in its apex of sufficient size to receive the article being coated, said orifice being rounded at its lower edge and being located substantially equidistant from the opposite marginal edges defining said gable, and a bottom wall joining said side walls, said bottom wall having an opening aligned with the orifice in the apex of the said gable.

4. A die having spaced apart side walls extending upwardly and being bent inwardly until they meet at an apex to form a. sectionally divided gable, said gable having at its apex an orifice larger in diameter than that of a wire for the like to be received therein, said orifice being located substantially equidistant from the opposite marginal edges defining said gable, and

a bottom wall joining said side walls; said bottom wall having an opening arranged to permit vertical movement of a wire or the like therethrough and through the orifice in the said gable.

5. A die having spaced apart side walls extending upwardly and being bent inwardly until they meet at an apex to form a gable divided into two equal, closely fitting, yieldably separable sections, said gable having at its apex an orifice larger in diameter than that of a wire or the like to be received therein, said orifice being located substantially equidistant from the opposite marginal edges defining said gable, and a bottom wall joining said'sid'e walls-said bottom wall having an opening arranged to permit ver-.- tical movement of a wire or the like therethrough and through the orifice in the said gable, and means integral with the walls of the die for retaining the die on a die support.

6.'A die for use in coating wires or the like with liquid coating material, said die being formed of resilient material and having spaced apart side walls extending upwardly and being bent inwardly until they meet at an apex to form a gable divided into two equal, closely fitting, yieldably separable sections, said gable having at its apex an orifice larger in diameter than that of a wire or the like to be received therein, said orifice being located substantially equi-distant from the opposite marginal edges defining said gable, the said side walls having inwardly projecting, suitably spaced apart, facing flanges for retaining the die on a die support, and a bottom wall joining said side walls, the said bottom wall being provided with an opening arranged to permit vertical movement of a wire or the like therethrough and through the orifice in the said gable and being so deformed as to assure reengagement of the sections of the gable when said sections temporarily are separated.

'7. A die formed from a single piece of resilient material, said die having spaced apart side walls, the upper opposite end .portions of eachof said side walls being bent inwardly to form facing flanges suitably spaced apart and the middle portions of said side walls extending upwardly and being bent inwardly until they meet at ant apex to form a gable divided into two equal, closely fitting, yieldably separable sections, said gable having at its apex an orifice larger in diameter than that of a wire or the like to be received therein, said orifice being located substantially equidistant from the opposite marginal edges defining said gable, the lower part of each of said side walls being bent inwardly and up thereof aligned with the orifice in the said gable.

8. A die formed from a single piece of resilient metal, said die having spaced apart side walls, the upper opposite end portions of each of said side walls being bent inwardly to form facing flanges suitably spaced apart and the middle portions of said side walls extending upwardly and being bent inwardly until they meet at anapex to form a gable divided into two equal, closely fitting, yieldably separable sections, said gable having at its apex an orifice larger in diameter than that of a wire or the like to be received therein, said orifice being roundedfat its lower edge and being located substantially equidistant from the opposite marginal edges defining said gable, the said side walls being deformed in their central regions to provide inwardly projecting, suitably spaced apart facing flanges adapted to co-operate with the first-mentioned flanges in retaining the die during service use in a loosely fitting position on a die support, the lower part of each of said side walls being bent inwardly v an opening in the central portion thereof the side walls and extensions adjacent said openings being cut away to increase the area of each opening, the said extensions being bent inwardly and meeting to form a bottom section which is slotted part way in a direction parallel with the marginal edges of the side walls, the slot formed thereby being rounded at its inner part with the center thereof aligned with the orifice inthe said gable and the longitudinal center of the said slot being aligned with the apex of the gable.

9. Apparatus especially adapted for coating wire with liquid coating material comprising means for moving a wire to be coated, a container adapted to receive a supply of said coating material and having an opening in its bottom wall adapted to permit the passage of the wire therethrough, means for sealing said opening to prevent leakage of coating material, means i for automatically maintaining the level of said coating material in said container, a die in operative relationship with said container that is capable of being fitted on-and removed from the moving wire during coating, said die comprising a member having spaced apart side walls terminating at their upper ends in a-gable structure which is provided at its apex with an orifice adapted to receive the moving wire, the lower edge of the orifice being rounded to facilitate self-centering of the die upon the said wire during coating, a bottom wall joining the side walls of the die, said bottom wall having an opening aligned with the orifice in the apex of the said gable structure, a support for said die, and means for treating the coated wire to harden the coating thereon.

10. A die formed of resilient material and comprising a member provided with spaced apart side walls terminating at their upper ends in a gable structure having an orifice in its apexof sufficient size to admit a wire or the like therethrough, a bottom wall joining said side walls, said bottom wall having an opening arranged to permit vertical movement of a wire or the like therethrough and through the orifice in the apex of the said gablestruoture, and means integral with the walls of the die for retaining the die on a die support.

11. A die formed of resilient metal and comprising a member provided with spaced apart side walls extending upwardly and being bent inwardly until they meet at an apex to form a gable divided into two equal, closely fitting, yieldably separable sections, said gable having at its apex an orifice which is rounded at its lower edge and which is of sufiicient size to admit a wire or the like therethrough, a bottom wall joining said side walls, said bottom wall having an opening arranged to permit vertical movement of a wire or the like therethrough and through the orifice in the apex of the said gable, and means integral with the walls of the die for retaining the die on a die support.

12. A die formed of resilient metal and comprising a member provided with spaced apart side walls extending upwardly and being bent inwardly until they meet at an apex to form a gable divided into two equal, closely fitting, yieldably separable sections, said gable having at its apex an orifice which is rounded at its lower edge, said orifice being located substantially equidistant irom the opposite margin-a1 edges defining said gable and being of sufiicient size to admit a wire or. the like ltherethrough, the said side walls having inwardly projecting, suitably spaced apart, facing flanges for retaining the die on a die support, and a bottom wall joining said side walls, said bottom wall having an opening arranged to permit vertical movement of a'wire or the like therethrough and through the orifice in the apex of the said sable. I

'13. Apparatus especially adapted 'for coating wire with liquid coating material comprising means for moving a wire to be coated, a container adapted to receive a supply of saidcoating material, a die in operative relationship with said container, said die being adapted to be fitted on and removed from the moving wire during coating and comprising a member provided with spaced apart side walls terminating at their upper ends in a gable structure, said gable structure having an orifice in its apex of suflicient size to admit the wire therethrough and shaped to coat the wire with a uniform flim'ot the coating material, a bottom wall joining the side walls of the said die, said bottom wall having an opening arranged to permit vertical movement of a wire therethrough and through the orifice in the apex of the said gable structure, means integral with the walls of the die for retaining the die on a die support, a support for said die, and means tor treating the coated wire to harden the coatins thereon.

.ADALBERT ALEXAY.