US1968992A - Apparatus for coating surfaces - Google Patents

Description

Aug 7 1934- H.-G. coNKLlNG 1,968,992

APPARATUS FOR COATING SURFACES Filed DeC. 2 8. 1932 SPRAY IHmm INVENTOR:

HILEN G. CONKLING j BY ATTORNEY Patented Aug. 7, 1934 UNITED STATES PATENT OFFICE- msaarosroa 'cosmo sonnen-s nnen o. eenmalig.l Los' anni, ome applicaties December 2s, 193e, serial No. 649,41

1 calm. (ci. :i1-44) llt) amolten mixture adapted tor covering surfaces,

from the place of melting to that oi! application;` to maintain the temperature continuously within` the limits between that of free nuidity and that of ignition of any combustible element in the '1I mixture, hereiny termed the critical temperature;

to provide means and apparatus'tor applyingthe materials over the surface of an object to-be coated, to provide such coating means as will enable 'application-of the coating at a rapid rate `901 with but little labor-and at low cost per unito! area coated; to provide certain special 'devices adapted to coordinate in their operation for the purposes to be described and which areIespecially adapted for movement, control and'ap l5 plication oi' molten duid; to provide means substantially complete for control oi' the molten mixture and the thickness -oi the coating so that coatings of practically any desired thickness orthinness may be had from 0.02 inch upward; $v to provide control which will so maintainv the temperature' of the mixture and so apply it that it will-be well and reliably anchored to the surface thus coated, to provide a spray coating means which can be operated without respecial skill or` 85 any considerable experience but *may be `op erated by so-called ordinary labor; to provide a mixture and meansfor applying same to form a coating which will add to the life and endurance oi' many articles, devices `and substances-so protected, as concrete in saltwater, earth-embedded wooden objects and the like,.and to provide apparatus for accomplishment ot the several easary steps which is easilypoxtable.` y Other objects will appear as this description 45, proceeds..

' with the above and cojeetsfinview,

invention consists `in the new and useful jprovision, formation, constructions. combination and l sommelier-hereinafter disclosed, shown in .the

'drawing and finally pointed out in theclaim. u 4 'mthshrawirlsrrV y f y1i1;.1 is"an elevation oi' a meltingpot withv a heatsource thereunder.

spray headfsome'parts Ii'ig. 1 is a cross-section otfthespray head on `form of'spray head drawn to a'smaller scale.'

` the addition .oi' some characteroiiiux the purinterrelatiqn of parts, members, steps `and tea Fig. 2 is an elevation, partly diagrammatiabt f acompression tankwith the several elements for controlling the system and applying the' molten material. j

V Fig. 3 is a cross-section oi' conducting me'ans'il"v for conveying the molten material and hot `com-- Apressed air to point of application of thematei-iai, taken on line 3-3 otllig. 2.

Fig. 4 shows in detail, andl partlykin section.

a form of valve interiorfofthe compression tank' B and employed i'or controllin'giadmissiont molten material therefrom to the' conveyor pipe and for blowing the pipesclear.- This 'and ^'Figs. 5,

6 and 'I are drawn to an:enlarge'd'scale. Fig. 5 shows la. longitudinal section a. .pre- 101 ierred -form or Joint for attachingitheconveyor pipe ,to the compressiontank.

Fig. 6 shows a longitudinal cross-section nl4 a being broken `avvayior clearness. 15-

section line 7-7on Fig. yil, al portion being broken away.

Fis..8 is a front end view otfanfalternative FIB. 9 is a longitudinalsection .of same Spray head taken on section iine-9--9iot.1'ig.` 8 Vdrawn .to same scale.

' Figulis a fragmentary longitudinal section oi' same spray.,.h'ead on section line '10-10 in- Fig. 8r and drawn'to same so ale.

`'lhe mixture. which is preferable for lthe pur" poses describedl is composed almost entirely of sulphur 'and silica in proper' proportions with 90 posewhereoi is to -help hold the molten mixturel homogeneous. Such a substance is napthaline o! which a small amount such as, for instance, nve percent is added tothe sulphur and silica. It the" ingredients comprise about 50 per. cent 95 sulphur, 45 per cent silica and 5 per cent napth-x aline this forms one serviceable and satisfactory mixture or the 'general type applicable to-the purposes ci this invention; though, of course, other substances 'may `be added'and the pro- 100. portions may be varied aszoccasionmay require.

The `silica. is in the' form f extremely 'finely ldividedvsand, in practice it is "wind-blown" and;

thus the very'nefparticles of sandwhich are c nearly pure-silicaare obtained. The ingredillo ents'are preferably dry mixed-prior to melting."

,'When'properly mixed they are placed'withinjan `appropriate'container and heat lapplied so that the sulphur is melted and the tine silica -par-- vtioles are thoroughly mixed and in suspensionl v in the molten sulphur. Obviously, the temperature must be suiliciently high to melt the sulphur yet below the ignition point of this material. Otherwise the sulphur simply burns and the usefulness of the remaining parts -of the mixture destroyed.

The preferred melting temperature is around 240 F. which is subject to considerable variation, provided the temperature of the mixture is never raised so high as 330 F. With the napthaline, or other substances having similar eiect, the consistency of the mixture is uniform throughout and maintained so throughout the procedure. It has been found that this mixture can be applied while hot by spraying or otherwise in coatings as thin as 0.02 inch thick and will cool and harden as an impermeable coating which is hard, smooth and resistant to shock or impact, being well anchored in the surface of the object covered, provided the latter be reasonably dry and have some slight degree of porosity. The mixture will adhere to materials such as glass and metal but under pounding or impact the thin layer will crack loose and fall away. It, however, is sufficiently adherent to polished surfaces to oer considerable resistance to its removal.

In transmitting the molten material to the surfaces to be covered its temperature must, of course, be maintained well above the melting point. The critical temperature therefore lies between 225 and 300 deg.. F.

'I'he preferred method of application to form a surface is by spraying somewhat in the manner that ordinary spraying is done but, of course, with certain requisite additions for temperature maintenance. The means hereinafter described refer to transmitting the molten material through 'an appropriate conduit and spraying same on the surface to be coated.

The melting arrangement shown in Fig. 1 is that of an ordinary melting pot A with a heat source B which, in this case, is indicated as a gas burner. It is obvious, of course, that electrical resistance, superheated steam, or any other means which will accomplish the object, is equally applicable for melting. In Fig. 2 is shown the general arrangement of the entire -equipment which includes an air compressor of any suitable type delivering -air to the heater E therefor through pipe 10 with controlling valve 11 between the compressor and the heater. Pipe 12' receives the hot compressed air and' conveys it to junction point 14 wherefrom three branches P, 20 and 18 carry the hot air on to different points for the special use wherefor it is required at each point. Compression tank C is provided with a hand hole, or similar opening, 29 through which the molten material is passed into tank C. Means are provided to maintain the required temperature in the compression tank, -such as electrical resistance wires 22, which are placed external of the wall 42 of the tank C as indicated. R shows the material within the tank when it is at its uppermost level. When thev tank is sufciently filled opening 29 is closed, and valve G, adjacent the bottom of the tank, is opened by means of control link 30 which opens the tank to pipe 24 which latte;` joins at connection F with pipe L, as indicated in Fig. 5. By opening valve 15 hot compressed air' is admitted to the compression tank which drives the molten material out through pipe 24 and carries it to the spray head by the thereto connected pipe L. Hot air pipe l?.

extends from junction 14 to the end of pipe L nearest the tank C and is preferably extended along with pipe L until the spray head is reached and a common heat insulating covering J surrounding them both, as shown, in Fig. 3. Pipe L and the contents flowing therein are maintained at the proper temperature by any preferred means. In the instant case an electrical resistance heating coil Q is employed. Valve G, whereby molten material is admitted to outgoing pipe 24 from the tank C, is shown in detail in Fig. 4. As indicated, it comprises a frustro-conical inner end for pipe 24 adapted to accommodate a' similarly shaped end on pipe 37. Obviously, when the two mating conical ends are pressed together there is no connection between pipe 24 and the interior of the compression tank, but pipes 20, 37, 24 and L form one continuous conduit. On withdrawing the conical end 39 of pipe 37 from the tapered end 33 of pipe 24 there is obviously a clear annular passage from the interior of tank C to pipe'24. The means of operating this valve G are obvious, comprising a bell crank pivoted at 32, the arm 31 whereof is connected with control link 30 and the other. 100 arm 35 being pivotally attached to the conical end 39 of pipe 37 at pivot 36. In order to carry an electrical heat coil over the entire length of pipe 24, including its tapered end 33, pipe 24 itself is not fastened into the wall 42. A short pipe 41, having a greater diameter than that of pipe 24 plus heat element Q with its insulation, is fastened tightly into the wall 42 and interior of the tank C, an annular header 40 is welded to the inner ends of both pipes'41 and 24 as shown.

When it is desirable or necessary to blow the supply pipe system L and 24 with a. spray header clear, cone 39 is moved by rod 30 and the bell crank to fit tightly with the beveled end 33 of pipe 24 and hot air under pressure is admitted to pipe 37 by opening valve 16. Obviously, pipe 37 is. flexible and joins with pipe 20 just inside the tank C at 38. By this arrangement the entire system is blown clear by compressed air.

The joint shown in Fig. 5 is a special one and intended as a union having a special form to prevent leakage. Sleeve 25 is threaded at one end to screw onto the end of pipe 24, the threads 125 of pipe and sleeve being at 27 as shown. Pipe L, over which sleeve 25 passes, has an annular ange 26 on its end adjoining pipe 24 which flange is sloped so that its surface cooperating with sleeve 25 forms an angle with the axis of the joint. The cooperating flange of the sleeve 25 mates with this flange 26 and the two ends of the adjoining pipes are surfaced for an exact t. Obviously, when sleeve 25 is screwed tightly onto pipe 24 the abutting ends of the pipes, at the transverse line'28, are'drawn tightly together, and the sloping flanges 26 of pipe L and of sleeve 25 likewise make a conical joint which is in series with the first named joint. This provides a joint which is not only normally tight but in the event oi' any slight distortion can be ground tight by rotation of the angular surface of flange 26 against that of the sleeve until an exact ilt is obtained.

The spray head shown in Fig. 6 is attached on the end of pipe L by a conical joint as shown and which is substantially obvious from the drawing. The usual form of union made by the flange 54 on the end of pipeL which pipe and which flange are surrounded by a sleeve 51 hav- 150 ing fiange52 mating with ange 54,` is used, the only change being in the mating end of the conduit attached by sleeve 51. This conduit member 54 has a much smaller bore than the pipe L so that the diameter of the sleeve 51 at the -threaded portion 53 is greater than needi ed for the smaller tube 65. The end of tube 65 is beveled inside to provide an easy path for the liquid and to avoid, as much as possible, obstructing corners and flanges. The outer portion of the end 54is tapered oppositely to the inner taper and this conically formed outer surface enters the end of pipe L a short distance as indicated. By drawing the parts tightly together by sleeve 51 it is obvious that linear contact is made by the inner end of pipe L with the conical` outer surface of member 54. One o! these is of steel. the other a softer material so that the sharp inner edge of pipe L will cut into the end 01,54 thereby producing a tight joint. Member 54,isextended radially as at 63 and this extended portion is welded, or otherwise attached, to the inside of the walls of the hot air jacket to form an integral chamber.

'The reduced conduit 65 continues on with its axis coincident with that of L and with the Walls 60 and 61 of the hot air jacket surrounding this conduit, finally terminating at the end` M which extends past the end wall 62 of the hot air jacket, passing through a hole 46 in end 62 which has a greater diameter than that of pipe M thereby providing an annular open--- ing surrounding pipe M. 'The general arrangement of the spray head is to pass hot air under pressure from supply pipe P into a jacket surrounding the end portion o! the conduit and after the air has passed through the air. jacket and along its length it passes out therefrom by two opposite conduits which are formed and positioned to spray the molten mixture. In Fig. 6 it is -seen that pipe P enters the jacket through opening in one side thereof and adjacent its outermost end, the air supplied thereto being both hot and runder considerable pressure. Some o1 the air blows directly out through annular hole 46 while much of it turns in its path and traverses the air jacket axially back to the end adjacentthe joint with pipe L, at which end are located two openings K-'-1, K--Z connected with pipes S--1, and S-2 which are diametrically at opposite sides and exterior o1' the air jacket. These pipes extend to the end of the air jacket then bend radially outwardly, and, after a short length so directed, bend inwardly terminating in oppositely positioned ends whichI are cut diagonally to the axis of the pipe so that the surface of the ends. lies in a plane substantially parallel with the axis o! the spray head. Outside of conduit M is shown an electrical heat coil q, the inner wall of the hot air jacket surrounding this electrical heating arrangement. Over the entirety is placed some appropriate heat 'insulating substance Iorming layer J.

The operation of this spray `head is as follows:

Molten liquid is supplied under pressure'l through pipe L to iinal spray conduit M, being continuously heated by electrical resistance coils.`

The pressure on the liquid is sumcient to eject itv from the end M of the conduit with considerable velocity. Hot air supply pipe conveys4 air under pressure into the hot air jacket and the outgoing stream of molten material from the end of M almost immediately receives an annular blast of high pressurcni high velocity hot air. This tends to mingle with the material and thereby increase the total volume so that the diameter of the spray continuously increases taking substantially a frustro-conical form until the stream reaches the ends S--1, S--2 of the 8l oppositely positioned blast pipes. Air, under high pressure, inthe hot air jacket passes through these pipes and strikes the conicallyformed iet, blowing it fiat. As it iiattens more and more it spreads, fanwise, to a wider and wider dimension perpendicular to the plane or the drawing and much as indicated in the Ianshaped spray in Fig. 9. To apply the coating this spray head is moved back and forth over the surface to be coated being held at an appropriate distance therefrom and moved at a rate of speed to correspond with the thickness of coating desired. It has been found that the rate at which coating can be applied is directly inversely proportional to the thickness of the coating. For a thickness of 0.032 the ordinary rate of coating is about one square foot per second, while for a coating of three times this thickness the time required for the same area `is three seconds. During this procedure that portion of the molten substance being sprayed is subjected toheat near the end of its travel from two different sources, namely, an electricall heat coil and hot air. Obviously, either could be used alone but it has been found that hot air alonefis'more diilicult to control exactly while electrical lheat alone adds somewhat to the cost of operation, but by combining them and using most of the heat from air having its temperature raised by ordinary combustion and just enough electrical heat therewith to .enable exact control the best operating and economical arrangement is produced.

An alternative form of spray head which is useful under certain conditions is that depicted in Figs. 8, 9 and 10. As indicated in Fig. 9 this spray head is attached to pipe L in identically the same 'manner that end 54 of tube 65 is attached to that pipe, the same encircling sleeve 51 being employed and the same character of 120 conical joint as before described being also used. The spray nozzle simply comprises l'the short central tubular conduit 65 which terminates in a flattened discharge opening whereof the narrow'sides make outwardly diverging angles with 135 the axis of the device. Transverse slit 66 through which the material is ejected is narrowed at its outer end by lips 67 which are parallel with and converging toward each other thereby making the discharge slit narrower 13g than that portion of the slit 66 leading from the circular tube 65 and spreading fanwise outwardly. The other parts are similar to those parts of the union connection shown in Fig. 6 and are similarly numbered. 135

As indicated in Figs.'9 and 10 the outer end of this head is rounded so that it is approximately the segment or a sphere which form is described in order that the distance of the point of emergence of the material from the discharge '149 slit to the surface being covered will be substan tially the same regardless of the position in which the spray head is held. The air pressure in the compression tank mustl be sulcient to move the material through the conduit L and '45 to spray it as indicated, so that the pressure in the compression tank must be adjusted to each of the spray heads when one is substituted for another.

All of these parts and4 members may be of 15g small size and independent of the area of the surfaces to be coated, and the entirety can be mounted on a light vehicle and moved about as may be desired. l

Such arrangement is economical and convenient in many classes oi work such as coating the interior of large sewer pipe lines. to protect them from being eaten away by chemical action of the substances moved therethrough and for coating many fixed objects to which the spray head mustbe brought as they cannot be moved.

Other conditions make portability of a complete system desirable which is provided by the arrangement herein described.

Figs. 1 and 2 show all the parts and elements required. It is obvious that no part of the system need be large for any area of coating to be applied, because, the time required to discharge one cubic foot, based on the rate 1 sec. per square foot 0.031 thick, is about 380 seconds, exceding 6 hours. Hence ii* the vessels could contain one cubic foot only, this would be an ample size, because within the 6 hours required to discharge 'this batch there would be ample time to melt and prepare a second batch before the nrst is exhausted. Hence the entirety may be small, light, and easily transportable.

Having described my invention in connection with illustrative embodiments, forms, proportions, and arrangement of parts, it will be understood that may variants thereof are possible to those skilled in the art, and my invention, in its broader. aspects, is not limited to the speciiic construction herein described and shown, as changes in the sizes, proportions, configurations, arrangements, assemblage, interaction, juxta position and mechanical relations, as well as additions, omissions, substitutions, combinations and alterations of forms, parts, members and features, may be made without departing :from the broad spirit of this invention.

Having thusdisclosed my invention, I claim and desire to secure by Letters Patent:

In an apparatus i'or applying a coating of a iiuid composition to a surface, the combination of a gas tight container for said composition, means tor heating said container, a source ot compressed heated air, means for admitting same to said container, a discharge pipe from the container, spray means at the end of said discharge pipe, and a valve which in one position connects said pipe with the interior oi' the container and in another position closes com? munication between said pipe and container and connects the pipe with the said source ot compressed heated air.

HILEN G. CONKLING.

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