US2317173A - Apparatus for melting powdered materials - Google Patents

Description

April 20, 1943. P. A. BLEAKLEY 2,317,173 I APPARATUS FbR MELTING POWDERED MATERIALS Filed Feb. 1, 1940 2 Sheets-Sheet l INVENTOR fgrjwmz mmy Patented ApnZO, 1943 UNITED STATES PATENT OFFICE.

2,317,173 APPARATUS FOR mums POWDERED MATERIALS Purling- A. Bleaklcy, Toledo, Ohio, assignor to The Bleakley Corporation, Toledo, Ohio, a corporation of Delaware Application February 1, 1940, Serial No. 316,725 I 4 Claims. (Cl. 91-122) This invention relates to devices for applying coatings to articles and relates particularly to devices for applying high-melting point nonmetallic coatings to metallic and non-metallic articles.

Usually in applying vitreous coatings to various types of articles, it is necessary to exercise extreme care in order to avoid checking or failure of the coating material to bond to the material, and moreover, it is difficult and expensive to obtain a smooth, uniform coating of the nummetallic material on the article.

The present invention has as an object the provision of devices by means of which it is possible to rapidly apply non-metallic materials in a molten form to articles to produce smooth, uniform coatings and finishes.

Another object of the inventionis to provide apparatus for applying initially powdered or granular high-melting point materials to articles in the form of a molten spray in order to obtain a uniform and even distribution of the material over the article.

Other objects'of the invention will become apparent from the disclosure of typical embodiments of the invention hereinafter.

The devices utilized in converting the granular non-metallic material into a molten spray are generally of the type disclosed in the Bleakley Patent No. 2,092,150, that is, they may consist of spray guns which have a nozzle in which the material is reduced to a molten condition and projected therefrom by a gaseous blast in an enveloping sheath of gas. The gas preferably is of non-oxidizing nature so as to prevent oxidation of the surface of the article being treated and of the material being sprayed.

Various types of material can be sprayed with guns of this type, for example, silica, glass, enamels, feldspar, silicates of various types, for example, aluminum silicates such as nepheline syenite. These materials, either alone or in conjunction withsuitable fluxes such as for example, lime or fiuorspar, which are used for controlling the melting point of the material, are

fed into the innermost nozzle of the gun by an the nozzle.

air or gas blast and conducted into a melting chamber wherein a flame produced by the combustion of a fuel gas in the air blast reduces the' material to a molten condition. The size of the melting chamber in the gun is critical, for the reason that it must provide a zone of high temperature of suflicient length to melt the granular material, but not so long that it will be. burned The molten material under the gas pressures used is sprayed in the form of a finely divided shower under high pressure against the surface to be coated. The surface preferably is preheated to atemperature only slightly below the temperature of the molten material. The molten material will bond to, this surface and when cooled gradually therewith, as by means of closely controlled heating elements and an oven of lower temperature, will solidify and contract with the surface being coated so that checking and cracking are almost entirely avoided.

For a better understanding of the present invention, reference may be had to the accompanying drawings in which:

Fig. 1 is a perspective view of a typical form of device for coating sheets with sprays of molten non-metallic material;

Fig. 2 is a view in side elevation and partly in section of a typical form of spray gun embodying the invention;

Fig. 3 is an end view, partly broken away, of

the device disclosed in Fig. 2; and

Fig. 4 is a perspective view of a spray nozzle having devices attached thereto for spreading the spray into a narrow fan in order to coat relatively wide areas of an article.

As shown in Fig. 1, a typical embodiment of the invention may consist of a spraying gun Ill .into which may be introduced finely divided 'vitreous or non-metallic material, for example,

silica, feldspar, enamel and aluminum silicates, such as, nepheline syenite. The material is melted and projected in the form of a spray upon a sheet of material H, such as for example, sheet steel. The spray gun I0 preferably is mounted in a carriage l2 which is slidably mounted on the rails l3 on a base'member l4 so thatthe gun may be adjusted toward and from the sheet H to vary the area covered by the spray and the temperature at which the molten material strikes the sheet. The gun Ill may be pivotally supported in the carriage I2 so as to permit its adjustment to vary the direction of impingement, of the spray upon the sheet.

molten material will adhere. tightly. A plurality J of sheets may be detachably supported by means of clips l5 upon a conveyor of any desired type,.

such as for example, a pair of chains l6 and I1 form material, by means of a series of heating elements 24 which-are located adjacent the upper and lower ends of the vertical conveyor and between the passes of the chains l6 and H. The

Patent No. 2,092,150, a concentric nozzle 46 is.

provided through which an annular stream of fuel gas is delivered for combustion in the air stream which delivers the 'iinely dlvidedmaterial to be melted and sprayed. Another concentric nozzle 41 is provided through which additional or secondary combustion supporting gas may be delivered. The nozzle 41 is provided with an extension 43 which forms a melting chamber and controls to a large degree the temperature conditions therein. The length of the extension 43 must be such that it will be maintained at substantially a cherry-red heat without being softened so that it loses its shape during operation.

upper series of heating elements 24 prevent too rapid cooling of the sheets with consequent checking or cracking of the coating. Any desired type of heating element may be used, for example, gas burners or electric heating coils, the latter being preferred because their temperature may be closely controlled.

A typical form of spray gun I0 is shown in Figs. 2 and 3. This gun is constructed to provide for uniform feed of the powdered material to the spray nozzle and to maintain in the nozzle the proper temperatures and conditions for melting the powdered material.

The device consists of a base member 26 which is provided with a series of control valves (not shown), which have the operating handles 21 for controlling the velocity and pressure of the fuel gas and air to the various passages in the spray gun nozzle. Detachably supported on the base 25 by means of an L-shaped bracket 23 is a hopper 29 for receiving the powdered or granular material. The outlet end 33 of the hopper 29 is disposed within an agitator funnel 3| which is supported by means of pivot pins 32" in apair of similar L-shaped brackets 33 mounted on the base member 25. Interposed between the upper edges of the funnel 3| and outlet spout of the hopper movement of the funnel 3| relatively to the hopper, while preventing escape of the granular material therefrom. The funnel 3| is oscillated about the pivot pins 32 by means or a pitman 33 is a resilient gasket 34 which permits 35 and a crank 36 which are driven by means ofa pneumatic motor 31 on'the base 28. Upon operation of the motor 33, the funnel 3| is escillated, thereby feeding the material downwardly at a uniform rate through the outlet 33 of the agitator into an aspirator by means of which the material is fed to the spray nozzle. The aspirator consists of a split housing 33 having a generally L-shaped passage or chamber 40 and an air inlet nozzle 4| of. reduced diameter which is disposed substantially centrally thereof. A resilient gasket 4|a is interposed between the lower end of the funnel 3| and the housing 33. The air inlet nozzle 4| is detachably connected to the housing 39 by means of an L-shaped ring bolt 42 having a shank which passes between the elements of the housing 39 beneath the passage 44. The housing is connected to a tube vided'at it's gm hand end with an enlarged or Similarly to the gun disclosed in the Bleakley "and material inlet name; :The i M u H I u a g "which e'xte'nds longitudinally ofthddevice and is pro- 1 Itcwill be understood that whe'n tjls desired diameter-throughout so that the steady flow '5 0f the granular material i is not i impeded; thus avoiding clogging of the bore 45. eve'rrunder conditionsof continuoususer;

1 astr y it will be burned oif by the flame. The nozzle may be cooled somewhat by means of radiating fins 49 adjacent the end thereof and by the pas-. sage of additional air or a mixture of air and hydrogen or non-oxidizing gas through the annular passageway 50 defined by the nozzle 48 and a concentric outer nozzle 5|, which projects beyond the end of the nozzle extension 43.

In operation the finely divided vitreous or non metallic material is fed into the hopper 29 and falls into the agitator: 3| where the oscillation of the latter causes it to be fed at a continuous rate into the chamber 39 of the aspirator. The blast of air through the nozzle 4| withdraws the material from the chamber and blows it alon the tube 43 out of the nozzle 44. The-fuel gas which is blown through the nozzle 46 is ignited through the passageway 50, it is possible to form a non-oxidizing gas'sheath aboutthe sprayed molten material so that oxidation of the molten material or the surface being sprayed is largely avoided.

To coat wider areas of the sheet, it may be desirable in some instances to provide means for spreading the spray into a narrow fan-like shape. In Fig. 4 is disclosed a construction for so spreading the spray. Mounted on the outer nozzle 5| is a ring-header 52 having outlet pipes 53 and 54 of generally similar shape which extend longitudinally of the nozzle 5| and terminate in nozzles 55 of flattened formation having narrow slit-like outlets which are directed substantially transversely of and disposed'adjacent to the outlet of the nozzle 5|; When, for example, natural ga is directed by means of these nozzles 55 against opposite sides of the spray, they tend to flatten it and spread it into the fan-like shape. Moreover, the streams of the natural gas will tend to deoxidizethe gas sheath and ,Qthus}, will provide Qadditional, protection against oxidation or nie molten. materiall a comparativelywide 'rnore'fthan hree,

be covfouror more depending upon tfi i ered. Moreover. while the device as been-unus- 'trated as utilizing a horizontally disposed spray gun, the spray-gun or sprayirguns maybe 11 posed vertically to spray the molten material downwardly upon articles or sheets carried by a horizontal conveyor over suitable heating elements and through a suitable oven. The only change required to convert the form of device illustrated into a vertically disposed gun is to arrange the agitator at the end of the device rather than in its side, this being readily accom- 4 plished Without material change in the shape,

proportions or construction of the gun.

From the foregoing description it will be apparent that I have provided a simple and effective device for converting granular or powdered high-melting point material into a molten spray and applying it as a surface coating to various types of articles. Moreover, I have provided a simple and effective device for applying such diflicultly applicable substances as enamels, porcelain, glass and various types of highmelting silicates to the surface of articles without substantial loss due to checking or cracking of the coating ,material.

It will be understood that the devices disclosed herein are susceptible to modification and that they should be considered as illustrative, only, and not as limiting the scope of the following claims.

I claim:

1. In a device for melting and spraying finely divided non-metallic substances the combination of a base member; a carriage supporting said base member for pivotal movement; a gun for melting and spraying pulverulent material mounted on said base' member, said gun comprising a nozzle having a passageway for said granular material, a second nozzle substantially concentric with said passageway ion delivering fuel gas, and a third nozzle concentric with said second nozzle for delivering additional combustion supporting gas having a portion projecting beyond the end of the first mentioned nozzle and forming a combustion chamber for the fuel gas in which said material is'melted, means supported on said base member for receiving said granular material, and an aspirator for withdrawing 'said material from said receiving means and blowing the. material through said passageway.

2. In a device for melting and spraying a finely divided substance the combination of a base member, a hopper mounted on said base member, an aspirator, an agitator communicating with said hopper-for delivering said substance to said aspirator, and a spray gun on said base member comprising a nozzle communicating with said aspirator, additional nozzles for supplying fuel gas and combustion-supporting gas to produce a flame and melt said substance, and means forming a chamber in which said substance is melted. I

3. In a device for melting and spraying a finely divided substancev the combination of a base member; a melting and spraying gun on said base member comprising a nozzle having a central passageway and a plurality of additional annular passageways for fuel and combustionsupporting gas, means forming a-substance-receiving chamber in which said fuel gas is burned, a housing having a chamber communicating with said central passageway, and a small nozzle insaid central passageway to direct gas therethrough and withdraw said substance from said chamber; a funnel-like member supported on said base member communicating with said chamber; means on said base member for vibrating said member and a hopper on said base member communicating with said member for delivering said substance to said member.

4. In a device for melting and spraying a finely-divided substance the combination of a base member, a hopper mounted on said base member, a pivotally supported funnel beneath said hopper, means for oscillating said funnel,

a spray gun on said base member having a nozzle, a housing on said base member forming a chamber communicating with said nozzle, means for delivering a blast of gas through said nozzle to draw said substance from said chamher and blow it through said nozzle, and means for directing fuel gas around said nozzle for combustion to melt the substance blown through said nozzle.

'PURLING A. BLEAKLEY.

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