US3318281A - Spray apparatus employing masking means - Google Patents

Description

May 9, 1967 A. E. PLEGAT SPRAY APPARATUS EMPLOYING MASKING MEANS 2 Sheets-Sheet 1 Filed March 4, 1963 May 9, 1967 A. E. PLEGAT 3,318,281

SPRAY APPARATUS EMPLOYING MASKING MEANS Filed March 4, 1963 2 Sheets-Sheet 2 United States Patent 3,318,281 SPRAY APPARATUS EMPLGYING MASKING MEANS Alain Edouard Plegat, Asnieres, Seine, France, assiguor to Societe Anonyme des Usines Chausson, Asnieres, Seine, France, a company of France Filed Mar. 4, 1963, Ser. No. 262,486 Claims priority, application France, Mar. 6, 1962, 890,195, Patent 1,324,354 14 Claims. ((11. 118-2) A well-known process for depositing a coat of material on various parts consists of utilizing a metallizing gun comprising at least one nozzle, through which a compressed gas is conveyed for atomizing and carrying the coating material previously brought to melting point. The jet emitted by the nozzle of the metallizing gun is directed to the part to 'be coated, then this gun and part are moved in relation to each other, so that said jet sweeps across that part.

A major disadvantage of this process lies in the fact that the thickness of the layer of material deposited is not even and this for several reasons; on the one hand, the density of the material carried by the compressed gas is variable in a non-linear decreasing manner from the centre of the jet towards the periphery, and on the other, the projecting area :being circular, the surface of the part covered at each moment is greater opposite the central zone of the jet than opposite the peripheric zones, because the length of the elementary surfaces, coming from the fictitious breaking up of the projecting area parallel to the sweeping direction, is equal to the corresponding span parallel to this direction, the spans being obviously variable.

During the sweeping movement, the time passed of each point of the part under the jet is proportional to the length of the corresponding elementary surface of the projecting area. Now, the aggregate quantity of material deposited at each of these points is equal to the product of the passage time by the mean density, brought to the time unit, of the material conveyed by the jet towards the corresponding elementary surface, so that this quantity of material deposited at each point is proportional, at about the sweeping speed, to the two following magnitudes: the length of the elementary projecting surfaces and the local mean density of the jet, magnitudes which are both decreasing non-linearly from the centre towards the periphery.

It results from this that the thickness, in the cross direction, of the coat of material finally deposited is maximum in the middle zone and minimum in the marginal zone and that this coat is confined by a curved surface.

It is a drawback, more particularly in the case where the material deposited is a soft solder alloy, melting at low temperature, intended to cover the collectors of radiators or aerotherms, in order subsequently to solder, by melting the coat deposited in a suitable oven, on the ends of tubes of nests mounted on these collectors.

The present invention has the object, essentially, of obviating this disadvantage, by creating a process for depositing a uniform coat of fusible material on various parts, according to which a part to be treated is moved at a constant speed under a jet of conveyed fusible material, in the form of atomized material, by a gas under pressure, the jet being directed perpendicularly to the part, then being intercepted in part of its peripheric zone, so that the marginal trickles of said jet bordering the nonintercepted part, confine, on the plane of the part, an extended projection area, appreciably rectangular, placed symmetrically in relation to the axis of this jet and parallel to the direction of the movement of this part.

The invention comprises, for operating the process, a metallizing gun directed perpendicularly to a conveyor holding and carrying along the parts for treatment, then a screen inserted between the gun and the parts for intercepting part of the jet of atomized fusible material emitted by said gun, the screen confining a middle opening extended lengthwise whose two opposite edges are equidistant from the axis of this jet and parallel to the direction in which the conveyor moves.

The invention also includes the application of the process in a machine for depositing an even coat of tin brazing on at least one part of radiator collectors, characterized in that it comprises a conveyor supporting the collectors and conveying them through a chamber in which a projection device is placed whose metallizing gun is supplied by a measured wire of tin brazing coming from a reel subject to a device for winding off, straightening and regularizing the tension of this strip, this device whose control is subject to a detector of the maximum and minimum quantity of wire stored in an intermediate magazine and by a delay-action detector for the collectors passing through the projection chamber, this latter communicating, through a screen of recycled water, with a suction cabin tending to create a depression there, then two blower sleeves being placed upstream, for drying the collectors previously polished, and downstream, for cooling the collectors after metallization.

Other various characteristics of the invention will moreover be revealed by the detailed description which follows and the drawing which is attached by way of nonrestrictive example.

FIG. 1 is a diagrammatical perspective showing the process of the invention.

FIG. 2 is a cross section of a device operating the process.

FIG. 3 is a lateral elevation of a machine applying the device of the process of the invention.

In FIG. 1, 1 denotes the projection nozzleof a metallizing gun whose type is chosen in function of the rough shape of the material supplying this gun. By way of nonrestrictive example, this material consists of tin brazing, for the application shown in FIG. 3 relates to a machine for depositing an even layer of solder on radiator collectors. The tin brazing can be utilized in the form of calibrated wire or metal powder or else sticks, flat pieces, or eventually in liquid form, for respectively supplying a wire, powder or crucible gun.

In any case, the deposited material or tin brazing is liquified upstream from the nozzle 1, then atomized in the latter by a compressed gas, most frequently air, which comes out in the form of a cone-shaped jet 2 conveying said atomized depositing material. The jet 2 is directed perpendicular to the part 3 which is moved at a constant speed in the direction of the arrow F.

The projection area of the jet 2 on the plane of the part 3 is circular in shape 4 fictitiously split up into parallel elementary surfaces. These elementry surfaces, being proportional to the corresponding span of the circle 4, decrease from the middle zone towards the peripheric zone.

5 denotes a curve showing the variation of the density of material directed at the level of this circle. This curve shows that the density is maximum at the centre and decreases towards the periphery where it is minimum. Thus, it is advantageous to limit the projection area to a middle zone 6 in which, as can be seen from the diagram, the elementary surfaces are appreciably equal and the density appreciably constant transversely. It is also advantageous that this zone 6 be parallel to the direction F or the movement of the part 3. This means that the thickness of the deposited material directed at each momerit on this zone 6 is appreciably constant transversally, and slightly variable longitudinally; then, that the aggregate thickness of the deposited material directed over the whole of the part, while the latter is moved, is appreciably constant transversally and rigorously constant longitudinally owing to the sweep-ing speed thus created which is itself constant, the thickness at each point of a longitudinal section of this part then becoming proportional to the integral of instantaneous thicknesses, taken along the corresponding section of said zone 6.

For the purpose of cutting down the projection area, a screen confining a middle opening is placed across the jet 2 between the part 3 and the nozzle 1 of the gun. Two opposite edges of the middle opening are placed parallel to the movement direction of the part 3. These edges are separated to an extent that the marginal trickles 7, 8 ofvthe jet 2,tangent to said edges, encounter the part 3 according to the parallel limits of the zone 6.

The preceding description illustrates the process according to the invention, according ot which a part of the marginal zone of the jetis intercepted, so that the remaining part of -.this jet encounters the part, according to an extended projection area placed symmetrically in relation to the axis of said jet and parallel to the moving direction .of said part.

FIG. 2 shows, in cooperation with FIG. 1, a form of embodiment of means for operating the process. The screen intercepting part of the jet 2 is formed by two rollers 9, placed parallel to the moving direction of the part 3, and tangently to the marginal trickles 7, 8 of the jet. These rollers are cooled by means of fluid, water,

7 for example. To this end, each roller 9 or 10 is made of a' tube confining a cavity 11 which communicates with axial ducts 12 and axial ducts 13 drilled in the ferrules 14 r or 15 and the journals 16 or 17 closing the tube.

The cooling water, put into circulation by a pump, is inlet by-one of the ducts 13 and one of the channels 12 and circulates in the corresponding. roller towards the other duct and the other channel.

The journals 16, 17 are housed in bearings supported by two independent carriages which are guided in the slides of a fixed frame and subject to a control mechanism tending to move them in opposite directions for regulating the distance between the rollers. The latter are rotatively driven, in the direction of the arrows F and F by motor-reducing gear sets, in order to reject and evacuate the depositingmaterial deposited by the jet 2 outside of the trickles 7, 8, towards the incurved ramps that descend 18, 19. The rollers have the purpose, not only of limiting the projection area of the jet, but also to prevent solder from being projected on to the conveyor of the parts, described in that which follows, and to recover the non-deposited solder, on these parts in a practical form.

Two scrapper, elements 20, 21 are also provided, associated with the'two rollers 9, 10. Each scraping element 20 or 21 comprises a rule 22 guided in a support 23 integral with the corresponding carriage. Guiding is effected in an ascending plane encountering the spindle of the roller 9 or 10, so that the rule 22 is moved, being subjected to the action of an elastic component 24 which bears on the support. 23, rigorously parallel itself to said roller-spindle. Each rule 22 has a two-lipped projection 25, 26, whosecylindricalterminal surfaces, incurved at the same radius as the curvature of the corresponding roller, are applied against the latter by the elastic component 24. It isessential that the edges 27, 28 of the lips 25, 26 of each scraper element 20 or 21 should be sharp and perfectly parallel to the roller 9 or ;10 so that the scraping of the deposit material deposited on this roller takes place in good conditions.

' Each roller can be advantageously provided with a facing to which the deposit material runs no risk of adhering, and whichopposes wear that might start up during scraping. The facing can be made of a hard electrolytic rectified chromium, or by a nickel-chromium-boron alloy, projected, remelted, rectified and polished, or else by a ceramic material or else by synthetic material. The scraping elements 20, 21 associated with the roller can be made of steel or other suitable material such as synthetic resin incorporating as filler a fine abrasive.

Moreover, the lips 25, 26 of each ruler 22 confine a housing for an eventual lubricating wick 29 whose nature and shape are adapted to the facing of the rollers.

Furthermore, a metallizing gun is provided suitable to the rough shape of the deposit material used. This gun is supported by a slide guided in the fixed frame and adjustable for height. The projection nozzle 1 of the gun is placed in the middle plane 30 symmetrically to which the rollers 9, 10 are placed.

Lastly, a conveyor 31 is provided driven at a constant and adjustable speed, supporting, below the rollers 9, 10, the parts to be covered with a coat of deposited material. These parts are formed, in the example shown, by radiator collectors 32.

The disposition of coating material is controlled by adjusting the distance of the nozzle 1 from the parts 32, by the vertical displacement of the slide holding the gun, and by regulating the distance apart of said rollers 9, 10, while acting on the control mechanism of the carriages.

The width of the zone 6 is controlled, so that it is equal to that necessary for producing a correct soldering of the ends of the tubes of a nest on each collector carried along, and also the evenness of the thickness of the deposited material is also controlled. Moreover, by regulating the speed of the conveyor 31, the aggregate thickness of the deposited material is controlled.

A machine putting into application the device for operating the process according to the invention, is shown in FIG. 3. This machine comprises at least one conveyor 31, for the continuous transport of collectors 32. The conveyor may be advantageously made of two endless steel bands and wound on two end drums 33, 34, then guided on slideways 35 and in a return corridor 36. The drums 33, 34 the runways 35 and the corridor 36 are supported by a frame 37 of welded metal sections.

One of the drums 33 or 34 is self-driven, and to this end, driven by a motor variable-speed set which enables the passage speed of the collectors 32 to be regulated, more particularly under a metallized gun 38. The steel bands forming the conveyor 31 have struts,at regular in- The metallizing gun 38 cooperates with the rollers 9, r

10 for intercepting the jet 2 and with the ramps 18, 19 extending the scraping elements, not shown in the drawing. The gun, the rollers, the scraping elements and ramps form the device of the invention which is placed underneath a tank 39 for recovering the deposit material projected into the marginal zone and not utilized. This device is housed in a projection chamber 40 traversed by the conveyor.

In the example shown, the metallizing gun 38 is supplied with the tin brazing in the form of a calibrated wire 41 coming from a reel 42 rotatively driven by a variable speed gear set. The wire 41 is wound on return pulleys 43 and has, between the latter,.a loop .44 partly surrounding a free cylinder 45. The latter forms a tension regulator for the wire, and the loop 44 that it produces forms an intermediate storage magazine. The cylinder 45 cooperates with two abutments 46, 47 which 7 limit its stroke at low and high points, while acting on ing of the supply circuit of a self-driven mechanism, provided in the metallizing gun 38 for the constant speed of the brazing wire. The time constant of the relay is chosen in function of the maximum deviation tolerated between two contiguous collectors 32: it must, actually, be equal to the time taken by the collectors to cover a distance corresponding to this deviation. This results that the supply circuit of the mechanism driving the wire, provided in the metallizing gun 38, is closed by the relay, as long as the collectors 32 conveyed by the conveyor 31 are regularly spaced apart, but when a considerable gap exists, for example, if a collector misses or if the collectors are offset, the relay opens this supply circuit with a delay corresponding to its time constant, for it is no longer supplied by the cell seeing that the ray reflected does not reach the latter, then this relay instantaneously closes as soon as the following collector appears.

The frame 37 supports an air blower sheath 48 traversed by the conveyor 31. In this sheath, there is a blowing nozzle 49 branched on to a duct 50 connected to a discharge piping of a centrifugal fan 51. The nozzle 49 has four outlets suitable spaced apart, placed below the collectors 32 carried by the conveyor, and so that these collectors under the influence of the air pressure are not displaced from their bars, a fixed slide rule 52 is provided to hold them in place. The air emitted by the nozzle 49 is intended to dry the collectors before metallizing, for the latter are wet, having been previously glossed or polished.

The blower sheath 48 communicates, by a wide aperture, with the projection chamber 40, and by a baffie opening, with a suction cabin 53. The latter is connected to the atmosphere by a chimney 54 eventually provided with a forced suction device. Also, the suction cabin 53 is associated with water distribution ramps, not shown. The latter are intended to form, before the battle is opened, a water screen through which the air loaded with impurities is sucked. The water is conveyed to the ramps by piping 55 branched on to the outlet of a motor pump set 56. The pump draws, through filtering elements, the water contained in a recovery tank 57, so that the water screen is of the recirculation type.

By the means previously described, there is a tendency to create in the projection chamber 40, a depression for sucking up the air of this chamber containing smoke and harmful metal dusts (lead), removing the latter through the water screen and giving off the purified air into the atmosphere by the chimney 54.

The centrifugal fan 51 also supplies blown air to a duct 58 extended by a two-outlet nozzle 59, placed above the conveyor 31 and downstream from the metallizing gun 38. Likewise, the nozzle 49 is associated with a maintenance slide-rule 52, the nozzle cooperating with a slide-rule 60. The air blown through said nozzle 59 is intended to ensure the cooling of the collectors after metallization.

Near to the drum 34 and at a lower level, there is a discharge bin 61, into which the metallized collectors fall by themselves, seeing that they are not attached to their supporting bars. Also, the drum 34 is associated with a device 62 enabling said bars of the conveyor to be cleaned, by eliminating the crust of material projected on to the latter when it is too thick. The cleaning device comprises a feeler, formed, for example, of a two-armed balanced scale, one of the arms bearing against the bars progressively as they pass along for feeling them and of which the other is placed opposite a contact-maker controlling the supply of an electro-magnet. This latter actuates, when the thickness of the crust exceeds a predetermined limit, a slider carrying a cutting tool, the cutting edge of the tool tangenting the bars and removing this crust.

The invention is not restricted to the forms of embodiment shown and described in detail, for various modifica- 6 tions can be applied to it without going outside of its scope.

I claim:

1. A device for the uniform spray deposition of fusible material on a longitudinally moving article comprising: a spray gun for projecting a jet of fusible material, in atomized form perpendicularly to the article to be coated; and

means to both control the transverse extent of deposition on said article and recover excess fusible material deposited beyond said desired transverse extent,

said means comprising a pair of generally cylindrical rollers disposed between said spray gun and said article with their axes generally parallel to the longitudinal movement of said article and at each transverse edge of the coating produced equidistant from the axis of the jet to define the transverse extent of fusible material deposition on said article by intercepting a portion of the peripherical zone of the fusible material jet, means to rotate said rollers in opposite directions to move the surfaces thereof upwardly and outwardly from the axis of said jet, and means to scrape each of said rollers to remove solidified fusible material therefrom.

2. A device in accordance with claim 1 wherein the atomized jet is projected from said gun by gas under pressure.

3. A device in accordance with claim 1 wherein said rollers are continuously cooled rollers.

4. A device in accordance with claim 1 wherein said scraping means comprises, for each roller, a scraping element and a downwardly incurved ramp integral with said scraping element, each said scraping means being springbiased against its said roller.

5. A device in accordance with claim 1 further comprising means to continuously convey articles to be coated past said spray gun.

6. A device according to claim 1, characterized in that said spray gun is carried by a slide moving vertically and subject to the action of a control component intended to regulate the distance of the gun from the conveyor.

7. A device in accordance with claim 4 wherein each D said scraping element is U-shaped comprising a body portion and two lips which engage the surface of said roller.

8. A device according to claim 7, characterized in that the scraping element of each roller is provided with a lubricating wick placed in a housing confined by the lips of this scraping element and roller.

9. A device according to claim 7, characterized in that each roller .is provided with a hard surface opposing the adherence of the material projected and wear, and the scraping element associated with each said roller is made of an abrasive containing material, the lips of said element having sharp edges, to improve the scraping effect.

10. A device according to claim 7, characterized in that each roller, and the scraping element and curved ramp associated with them, are supported by a carriage, the two carriages corresponding to the two rollers being movable in opposition and subject to the action of a control mechanism intended to regulate the distance between said rollers symmetrically in relation to the projection axis of the metallizing gun.

11. A device according to claim 5, wherein said conveyor means supporting the articles to be treated passes through a chamber in which said spray gun is placed and further comprising a self-driven mechanism for driving at a constant speed a calibrated tin brazing wire coming from a reel subjected to a running-off device and passed to said spray gun, which mechanism straightens and regularizes the tension of said wire, a detector of the maximum and minimum quantity of wire stored in an intermediate magazine, a delay-action detector for the parts to be treated passing into the projection chamber for controlling the continuity of wire feed to spray gun, suction cabin for creating a depression in said spray gun chamber,

and blower sheaths upstream for drying the articles prior to coating and downstream for cooling the articles after coating.

12. A device according to claim 11, further comprising means about which the wire coming from the reel is wound, before penetrating into the rnetallizing gun, comprising at least two pulleys between which the wire forms a loop surrounding a free cylinder which forms said tension regulator for the wire and which cooperates with two detection contact-makers for the 'top and bottom stroke ends, these contact-makers controlling the electric supply of a variable speed-gear group driving the reel. 13. A device according to claim 11, wherein said delay-action detector comprises a photo-electric" cell, receiving light rays coming from a source and reflected by the articles for treatment carried by the conveyor, supplies a delay-action relay controlling the closing of the supply a circuit of the self-driven mechanism provided in the spray gun for driving the brazing wire, the time constant of this relay being equal to the time taken by the articles for covering a distance corresponding to the maximum deviation tolerated between two successive parts.

'8 14. A' device according to claim 5, wherein said conveyor is made of two endless steel strips wound on two end drums of which one at least is driven by a motor speed-gear change set, these strips being also guided on slideways and in a return corridor, then being strutted by small bars for supporting the articles.

References Cited by the Examiner UNITED STATES PATENTS 2,035,677 3/1936 Steinke.

2,252,204 8/ 1941 Reilly.

2,676,841 4/1954 Pohle 118-301 2,733,172 1/1956 Brennab 117-1053 X 2,914,788 12/1959 Smith et a1. 15-25651 3,048,146 8/1962 Coppola 118-301 3,073,528 1/1963 Wilson et a1. 118-2 X 3,084,663 4/1963 Warner.

3,102,046 8/1963 Bushley 118-301 X ALFRED L. LEAVITT, Primary Examiner.

A. GOLIAN, Assistant Examiner.

Claims (1)

1. A DEVICE FOR THE UNIFORM SPRAY DEPOSITION OF FUSIBLE MATERIAL ON A LONGITUDINALLY MOVING ARTICLE COMPRISING: A SPRAY GUN FOR PROJECTING A JET OF FUSIBLE MATERIAL, IN ATOMIZED FORM PERPENDICULARLY TO THE ARTICLE TO BE COATED; AND MEANS TO BOTH CONTROL THE TRANSVERSE EXTENT OF DEPOSITION ON SAID ARTICLE AND RECOVER EXCESS FUSIBLE MATERIAL DEPOSITED BEYOND SAID DESIRED TRANSVERSE EXTENT, SAID MEANS COMPRISING A PAIR OF GENERALLY CYLINDRICAL ROLLERS DISPOSED BETWEEN SAID SPRAY GUN AND SAID ARTICLE WITH THEIR AXES GENERALLY PARALLEL TO THE LONGITUDINAL MOVEMENT OF SAID ARTICLE AND AT EACH TRANSVERSE EDGE OF THE COATING PRODUCED EQIDISTANT FROM THE AXIS OF THE JET TO DEFINE THE TRANSVERSE EXTENT OF FUSIBLE MATERIAL DEPOSITION ON SAID ARTICLE BY INTERCEPTING A PORTION OF THE PERIPHERICAL ZONE OF THE FUSIBLE MATERIAL JET, MEANS TO ROTATE SAID ROLLERS IN OPPOSITE DIRECTIONS TO MOVE THE SURFACES THEREOF UPWARDLY AND OUTWARDLY FROM THE AXIS OF SAID JET, AND MEANS TO SCRAPE EACH OF SAID ROLLERS TO REMOVE SOLIDIFIED FUSIBLE MATERIAL THEREFROM.

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