MXPA06003799A - Apparatus for themal spray coating - Google Patents

Abstract

A system for thermal spray coating of a particulate material onto a substrate includes a spray gun apparatus having dual vortex chambers for the mixing of fuel gas and oxygen. The apparatus provides a jet flame resulting from a compression wave formed by compressed air. Dual venturis control the flow of fluidized coating material particles to provide smooth and controlled delivery of coating material to the spray gun.

Description

BACKGROUND OF THE INVENTION The present invention is directed to an apparatus for thermal spray coating, and particularly to a thermal spray coating gun for applying a coating material containing polymer to a substrate. BACKGROUND OF THE ART The term "thermal spraying" refers to a process in which a coating feed material is heated and impelled as droplets or individual particles on the surface of a substrate. The coating material is heated by the applicator (e.g., a thermal spray gun) using a combustible gas or electric arc and converted into molten or plastic droplets or particles which are propelled out of the heat gun by gas compressed. When the particles of the coating material strike the substrate, they flatten and form thin platelets ("lamellae") that adhere to the surface of the substrate. The lamellae are cooled and formed into a layer of applied coating material having a laminar structure. Several types of thermal spray guns are known. For example, U.S. Patent No. 5,285,967 to Weidman discloses a high velocity oxygen fuel thermal spray gun ("HVOF") for spraying a molten powder composition of, for example, thermoplastic compounds, thermoplastic / metallic compounds, or thermoplastic / ceramic composites on a substrate to form a coating on them. The gun includes a HVOF flame generator to provide a stream of HVOF gas to a cooled fluid nozzle. A portion of the gas stream is divided to preheat the powder, with the preheated powder being injected into the main gas stream at a downstream location within the nozzle. Sources of forced air and vacuum are provided in a reinforcing ring circumscribing the nozzle for cooling the molten powder in flight prior to deposition on the substrate. Thermal spray guns typically use mixtures of oxygen-fuel gas, air-fuel gas, air-fuel liquid, oxygen-liquid fuel or electric arc and plasma as a heating medium to melt and propel the individual droplets to a prepared substrate. Thermal spray devices fall within the general classification of equipment: (1) combustion by cable, (2) combustion of dust, (3) double-wire electric arc, (4) plasma-dust, (5) oxygen-gas high-speed fuel-powder, (6) oxygen-liquid fuel-high-speed wire, (7) air-fuel liquid-high-speed powder, (8) oxygen-fuel liquid-high-speed powder, (9) powder of detonation gun, and (10) water cannon plasma. In general thermal spray devices are wire combustion, dust combustion, plasma and electric arc. In the wire combustion process, a combustion heat source is initiated and the wire or rod-shaped feedstock is driven into the heat medium where a stream of compressed air concentrates the heat source around the axially fed feed so it is atomized in molten form and driven to the substrate for deposition of the coating. Attempts have been made to spray polymeric materials in the form of wire using existing wire combustion technology, however, it has not been successful if the air compression wave required to atomize the polymer wire is oriented to strike the flame high. temperature directly on the feed material thus consuming the resulting atomized droplets. The high temperature associated with this device can cause the coating to crack. The existing wire combustion technology uses a siphon plug to mix the oxygen and fuel gas before combustion. This is a complicated and expensive component for the machine. In the powder combustion process, a combustion heat source is initiated and the feedstock is introduced axially or tangentially in powder form to the propagated flame. The feeding material is supplied by means of a hopper mounted on a gun or powder feeder. The powder combustion process has been used to apply polymer materials; however, the temperature of the flame consumes 50 percent or more of the feed material. Additionally, the relatively high temperature can burn the subsequent applied coating and / or cause the coating to crack. The existing dust combustion technology uses a siphon plug to mix oxygen and combustion gas before combustion. This is a complicated and expensive component for the machine. The combustion powder equipment does not provide the generation of an aligned and oriented compression wave nor does it provide air from the cooling mixture in the body of the nozzle so that the temperature of the flame may decrease. In the process of the electric ARCOE two wires of the material of feeding of similar or dissimilar material with opposite polarity are fed to the spray device where they are directed to impinge one on the other and therefore strike an arc that produces a rapid melting of the food materials. A stream of concentrated compressed air atomizes the molten material and propels it to a substrate. The source of generation for the electric arc is a MIG welding rectifier where the positive charge is applied to a wire of feedstock and the negative or base is applied to the other wire of feedstock. The electric arc requires material in the form of wire that must be electrically conductive and therefore not suitable as a means of spraying plastic materials. In the plasma powder system, a heat source is generated by passing an inert gas between the space formed by an electrode and a nozzle that are in an electric potential. A low-amperage, high-voltage, high-frequency arc is struck which unites the space between the electrode and the nozzle. This small amperage arc partially ionizes the inert gas and generates a conductive path for the high amperage potential, low voltage complete a circuit. The inert gas is therefore completely dissociated and expands and exits through the orifice of the nozzle at high speed. During the recombination of the dissociated gas, heat is generated which is used to melt the powder of the feed material injected into the plasma flame tangentially. The flame velocity drives the powder of the feed material onto the substrate. The plasma gun has been used to spray high temperature polyester with a constituent component of aluminum but the intent is to burn some of the polymeric material. The cost of operating the equipment also limits it as a device for economic application on the site of powder coating materials. In the detonation gun system, a heat source is propagated by a series of controlled explosions. An oxygen-fuel gas mixture is injected into a chamber by means similar to the valve in an internal combustion engine. However, the chamber is open at one end and there is no piston or plunger. The oxygen-fuel gas mixture is ignited by a spark plug that coordinates with the valve train. The fuel and the ignition cycle is repeated multiple times per second and the resulting detonation wave melts and drives the feedstock to a substrate. The feed material is supplied in powder form from a powder feeder device. The detonation gun is large and requires a dedicated room. It can not be used on the site. It is used to apply dense and hard coatings and is not suitable for polymeric materials. The high speed is inadequate to apply polymeric materials in which the pressures required for the fuel and the gases of the oxidizing medium ensure a large flame and high temperature. Also, the very high speed is negative for the plastic droplets. The temperature of the flame can degrade and crack the applied coating. In addition, the high operating cost of the equipment prevents it from becoming a viable means of applying low-cost polymeric materials. Powder feeders come in a variety of constructions; But, the basic function is to transport the material in powder form. These constructions are fluidized bed with venturi supply, mechanical screw with venturi supply, gravity feed with venturi supply, metric flywheel with venturi supply. Powder feeders are required to supply the powder feed materials, to various equipment, from a material source that is separated from said equipment. The equipment can be a thermal spray device, electrostatic powder paint gun, extrusion screw and injection molding equipment. In all cases, a feeder that provides precisely measured and non-pulsed material is essential. This is particularly true for the powder dust combustion equipment by thermal spray and electrostatic spray guns. The current fluidized bed ventura powder feeder technology is insufficient for use in thermal spray devices and electrostatic powder paint guns. In both electrostatic and thermal spray equipment the pressure, velocity and fluid required at the nozzle to supply the feed material to the substrate is different than the pressure, velocity and flow required to generate a vacuum and the measured feed material (velocity of Dew) . The equipment currently used uses the same pressure, velocity and flow source for both supply and quantification functions. This is a compromise of two separate functions. The mechanical screw / ventura and the ventura of the quantization handwheel separate the functions but are subject to union, wear and pulsation of an unequal feed towards the flywheel or screw. The powder coating equipment supplies polymer / powder paint materials to a substrate via an electrostatic spray gun. This gun applies an electric charge to the feed material that is at a different load to the substrate to be coated. The coated part is placed in an oven so that the electrically bonded polymeric materials melt and cure. In a second embodiment of this technology, the substrate to be coated is placed in an oven and heated above the melting point of the polymeric material to be applied. The heated part is then immersed in a fluidized bed of the polymeric feed powder so that the material in contact with the melts of the heated part is deposited on the substrate. Both modalities have limitations in their use. They require a high energy cost to operate the oven. They can not be used on the site as they are fixed factory installations. The parts that can be coated are limited by the size of the available oven. In the case of electrostatic equipment, certain combinations of conductive metals and / or polymers can be avoided as they can affect the charge. As previously established, the existing thermal spray technology has been used in an attempt to apply thermally sprayed polymeric materials in powder form with very limited success. Additionally, equipment has been produced that is dedicated to the application of powdered polymeric materials. The sources of heat for these devices are oxygen-fuel gas or propane-air. These work as typical thermal spray dust combustion guns. However, they are aimed at the polymer material temperature requirements somewhat better than the high temperature thermal spray combustion powder designed for metallic or ceramic materials. There are limitations to the effectiveness of these devices. They are not directed to the requirements of separate function of particle velocity and flow in the heat medium and the pressure and flow required to supply a measured dew rate consistent with the thermal output of the gun. These either provide the correct spray speed for the material used and the thermal output or provide a correct speed and flow to effect an appropriate drying time or compromise both. further, all the above embodiments of this apparatus use a gas mixing device siphon plug. In the case of the propane-air heat source, the function of the stoichiometry of the flame is not separated from the air used to provide the correct speed and flow of the feedstocks. Additional air is introduced to the flame to propel the particle, the temperature of the flame rises as the proper mixture of propane and oxygen is achieved. In all known prior embodiments of the apparatus, the temperature of the flame is too high because it is not directed to the requirement of cooling the flame before it comes into contact with the polymeric feedstocks. This high temperature results in the combustion of polymeric feedstocks or acts as an additional fuel source when contacted with the flame. It is indicated by the bright orange flame generated when they are introduced - the polymeric materials in the heat medium. This combustion of the feedstocks results in reduced deposition rates below 50%. In addition, it avoids the use of electrostatic grade materials (the range of 5 to 160 microns) that provide a more homogeneous and smooth coating. This limits the equipment generally to fluidized bed materials that are in the range of 80 to 200 microns and provide coarser or thicker coatings. Since the temperature of the existing apparatus is too high, it is not intended to meet the needs for a compression wave that efficiently transfers a reduced temperature heat source to the feed of the polymeric material. The foregoing modalities are based on preheating the substrate to 204.44 ° C (400 ° F) prior to application of the polymeric feedstock to achieve a viable deposited coating. All the technology so far has failed to solve the problem of the importance of aligning the cooling air or the compression jets with the jets of the gas from the nozzle. Finally, the prior known apparatuses are limited in the range of and the control of the dew parameters. Although several apparatuses are known, there is still an apparent need for an improved apparatus. The improvement includes: better control of the heat source medium, improved supply of material for the separation of functions from the velocity and flow of the material in the heat source and the material measurement function (dew velocity), to the elimination of a mixing device with siphon plug, the ability to cool the temperature of the flame before coming into contact with the polymeric feed material, the generation of a compression wave for the efficient transfer of a reduced temperature heat source to the polymeric feed materials, the need to align the air of the cooling mixture with the nozzle flame jets, the need for alignment of the compression wave jets with the jet jets of the nozzle, the ability to spray materials of electrostatic grade of lower micras (5 to 160 microns) for an improved homogeneity and smoothness of the coating, the ability to apply polymer coatings with little or no need for preheating the substrate, the ability to apply polymeric materials without consuming the same as a fuel source, the ability to achieve close to 100% efficiency of the polymeric coating tank, the ability to of non-destruction or degradation of the polymer coatings applied by the thermal spray device as the coating is being applied, and the ability to have a larger range and control of the spray parameters. BRIEF DESCRIPTION OF THE INVENTION The present invention is directed to a new apparatus for the thermal application of coatings of powder and plastic paint., and particularly to a portable thermal coating gun for applying polymeric coating materials to a substrate. The material is in the form of powder or wire or wire and encompasses all known thermosetting and thermoplastic polymeric powder paint materials, ie epoxies, urethanes, nylons, polyesters, polyethylene, polypropylene, polyethers, acrylics, vinyls, PVCs, polymers of fluorocarbons, silicones, numerous and hybrid combinations of the included materials. In general, all materials in the form of a powder between 5 microns and 500 microns are useful in the device described. Also all the materials that are or can be stretched in wires or threads are useful in the described device. The materials in the form of powder or wire may include other organic or polymeric materials or non-organic minerals or metallic materials such as ceramics, silica, graphite, coal and all metals in the form of powder. The metallic materials can take the form of copper, brass, bronze, 'tungsten and chromium carbides, stainless steels, aluminum, zinc, zinc / aluminum, iron and all the metal components and compounds available for the general thermal spray industry. Biocides, anti-fouling agents and lubricating materials can also be included in the plastic polymer matrix. BRIEF DESCRIPTION OF THE DRAWINGS Several modalities are described below with reference to the drawings in which: Figures 1 and 2 are diagrammatic illustrations of the system of the invention; Figure 3 is a diagrammatic illustration of the powder feed system employing the dual ventura; Figure 4 is a sectional view illustrating the spray gun apparatus of the invention; Figure 5 is a sectional view illustrating the body of the gun; Figure 6 is a side elevational view illustrating the body of the gun; Figure 7 is a sectional plan view illustrating the fuel and oxygen channels of the gun body; Figure 8 is a sectional plan view illustrating the air channel of the gun body; Figures 9A, 9B and 9C are 'respectively, an end view, side view and view of the side section of the nozzle; Figure 10 is a side sectional view of the diffuser ring; Figure 11 is a diagrammatic end view of the spray gun apparatus; Figures 12A and 12B are respectively an end view and a side view illustrating the cover of the air distributor; and Figure 13 is a side sectional view illustrating the body of the air cap. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention employs a vortex fuel-oxygen mixer and other innovations to provide a portable flame thermal spray gun with up to 100% efficiency in the deposition of coating material. It is simple and convenient to use in on-site locations and gives the user great flexibility in the application, for example, of soft surface coatings, solids, or surface coatings. rough, porous, for any particular polymeric coating material of any desired thickness. The thermally applied polymer and powder paint spray system consists of a spray gun with unique modes that include a new and unique powder feeder and regulated and controlled supply of air, oxygen and propane. The polymeric material to be applied is placed in the powder feeder, so the feed rate or rate of the material is controlled by a feed-speed vent and it is directed into the feeder to a venturi that supplies material. The feed material to be applied is directed to the spray gun where it is melted and driven to a substrate for application. The control of the powder feeder is determined by the regulated pressure and the air flow to a fluidized chamber, the velocity venturi of the material feed and a venturi of material supply. The gun is controlled by the speed of the material supplied from the power feeder and by the speed and flow of supply independent of the speed or proportion of the material. In addition, the gun is provided with a regulated supply of pressure and flow of oxygen and propane. to be used as a source of combustion heat. A regulated supply of pressure and air flow is directed to unique jets in the nozzle of the gun, which serve to provide a curtain between the polymers of the low-temperature melt feed material and the combustion flame and also to cool the flame of combustion. The same air is directed to the compression jets that align with the jets of air from the nozzle so that the cooled combustion flame are incidents are the feedstock. These jets form a compression wave. The compression wave produced in this process allows the rapid transfer of the heat medium to the thermoplastic polymer material to be melted. This compression wave is analogous to the pressure cooker. However, it is an open system instead of closed. The compression wave is focused around an axis formed by the wire or polymer powder and has a forward moment moving away from the camera. This system allows the fast fusion of the materials of feeding without burning or degrading the delicate materials. The apparatus includes a double vortex that propagates by the injection of oxygen and propane at the same point, but in the opposite direction, whereby oxygen and propane are premixed, and the oxygen-rich vertex moves in a direction opposite to the hands of the clock inside the chamber of the first stage formed by the body of the Diffuser ring and the body of the gun. The double vertex moves in the opposite direction 180 degrees from the injection point and enters the opposite ports. After entering these ports, the oxygen-rich vertex and the propane-rich vertex are directed to intersect and complete the mixing of the combustion gases in the chamber of the second stage that is formed by the diffuser body and the nozzle stem. The combustion combustion gases then pass through the annular space formed by the nozzle stem and the diffuser so they enter a chamber formed by the rear part of the nozzle body, the surface of the diffuser, the stem of the nozzle and the body of the gun. The gas then exits the nozzle via the gas discharge ports of the nozzle so that a combustion flame is propagated. This method of gas mixing is new, novel and unique. It is simple, easy to manufacture, and eliminates the siphon plug assembly found in other thermal combustion spray devices. As there is double chamber and double vortex, this mitigates the recoil fire as it is difficult for the sustained combustion to occur in a vortex and especially where the gases pass through the ports from the first chamber to the second chamber as the velocity increases so that the delivery speed is greater than the burning speed. So this method is inherently safe.

The apparatus includes alignment pins that allow precise orientation of the compression jets with the jets of the flame and the air jets of the cooling nozzle. In one embodiment the compression jets in the body of the air cap are aligned along the lines of the radius of the air cap body with the cooling jets of the flame in the nozzle and along the lines of the air cap. radio there. This allows the combustion gases to impinge and compress on the feed material. In another embodiment of the apparatus the compression jets are aligned along the shape of the spokes by the jets of the flame in the nozzle and the compression jets in the cap of the air distributor. This mode allows high temperature hot gases to impinge on the feedstock, but in all other forms it is similar in operation and function as that described immediately above. The orientation of the compression jets in the cap of the air distributor with respect to the jet jets of the nozzle or the air jets of the cooling nozzle are incrusted by means of an alignment pin which is embedded in the body of the nozzle. gun and passes through the diffuser and into the body of the nozzle so that the nozzle is fixed in place with its cooling jets and the flame jets oriented and fixed with respect to the body of the gun. There is a second alignment pin on the gun body that allows alignment of the air distributor cap. The air distributor cap preferably has two aligned holes that allow the orientation of the compression jets to be aligned with either. cooling air jets in the nozzle or the jets of the flame in the nozzle. The thermal spray device incorporating this alignment feature is not known. This is unique and new and new. It is very important to ensure that the parameter group does not change with the arbitrary alignment of the gun components. In addition, there is no known thermal powder combustion powder apparatus that uses compression wave jets to effect a rapid transfer of heat to the powder feed material. The apparatus of the present invention not only compresses the hot flame gases but also provides cooling air jets which act as a curtain between the hot flame and the low melting point polymeric coating material. The device includes new, unique and innovative air jets from the flame cooling nozzle. These jets are in the middle of the nozzle between the subsequent flame jets and are concentrically closer than the flame jets to the orifice or discharge port for feeding the material. This arrangement provides an air curtain between the flame jets and the coating material such that the coating material does not come into direct contact with the high temperature combustion gases of the flame jets. This mode allows the hot gases of the flame jets to be cooled before contact with the material feed. There is no known thermal spray device that incorporates this feature. The independent control of the oxygen-containing stream used for the oxidation of the fuel gas and the air stream used for the nozzle • cooling avoids the disadvantage of having a single source of single air stream used for both oxidation and cooling of the material This is, if the same air stream is used both for the oxidation of the fuel gas and for the cooling of the material, increasing the air flow sufficiently for cooling-it can result in a stoichiometric excess of air that extinguishes the flame. of combustible gas. On the other hand, maintaining the air flow • within the flammability limit of the air / fuel ratio can result in insufficient cooling of the coating material. This in turn, or can result in overheating and carbonization of the low melting point polymers, thus avoiding their use as coating materials. The apparatus and system of this invention avoid this problem. The apparatus provides independent control of the speed and flow of the feed material in the heat source at the front of the gun by means of the port or discharge port of the nozzle material. This independent supply is essential for all thermal dust spray devices but particularly for low melting point polymer fuel feed materials. The polymeric feedstocks are combustible in the form of powder. They can act as an additional source of fuel when they come into contact with the flame. For at least this reason at a minimum supply speed must be greater than the rate of combustion of the feed material for the desired feed rate. However, the drying time of the coating material in the heating zone must be sufficient for the transfer of the heat medium to the feed material so that all the particles are properly melted. No existing thermal spray apparatus is known to provide the independence of this essential function. All existing powder combustion thermal spray devices use the same speed and flow to set a spray speed and supply it to the front of the spray gun to the heat medium. The required spray speed and the required speed and drying time are two mismatched functions that must be separated. One mode provides for this by means of a special new powder feeder, unique and novel. The apparatus includes a new, novel and novel powder feeder as discussed above. This fluidized bed powder feeder allows separation of the functions of the feed rate of the material and the speed of the material and the flow to the heat medium. This is done by a unique combination of two venturi generators as opposed to one. The first is a material feed speed venturi that is adjusted to control the speed at which the feed material is delivered to the second ventura in an open coupling. The open coupling allows the second venturi to extract a vacuum and provide a flow of a desired velocity and independent flow from the first ventura. When the material flow is not carried by the second venturi it works continuously. The continuous speed and flow are coupled for the supply and drying time required at the front of the gun for the feed material to be sprayed. This speed and continuous flow ensures that the material feeding hose does not collect the powder feeding the material in the hose curves, which causes back pressure and vibration. When the material is removed, the venturi siphons the powder from the hopper of the powder feeder and injects the desired velocity into the vacuum port of the second venturi. The flow and velocity of the first venturi is always lower than that of the second. There is no back pressure on the material feed hose. There is no vibration and a stream of "non-pulsating material is supplied very accurately into the heat medium." All other existing fluidized bed venturi powder feeders rest in a venturi to supply a measured velocity of feed material to a liquid-containing device. thermal spray, electrostatic powder spray gun, injection model machines, extrusion machines or material processing supply As such, the speed and flow of the transport medium or gas is determined by the speed at which you want the material to be delivered to a particular device The unique venturi concept is plagued by pulsation, vibration, jam and non-uniform speed of supply of the desired material. The reason for this is that the material is siphoned and injected into the supply hose of the material the presence of the material and the accumulation of the same creates a retro-pressure that inhibits the flow of air in the venturi and decreases the vacuum. The material in the hose must flow outward from a decreasing flow before the vacuum is restored and the new material is supplied. This cycle repeats itself and the flow of material always varies from too much to too little or none at all. While the features described above are new, unique and novel in and of them, the synergistic relationship of all of them working together provides a device that is truly capable of efficiently applying powdered and polymeric paint feed materials, with close to 100% Efficiency in the tank, without degrading the feed material, the applied coating or the substrate. Referring now to Figure 1, a coating application system 10 is shown to apply a coating material using a thermal spray gun of the present invention. The coating application system 10 includes a portable thermal spray gun 100, to which is connected a supply of compressed air stream A, the fuel gas F such as methane, ethane, propane, butane, acetylene, etc., a supply of oxygen 0, and a supply of material Cm, of coating. The spray gun 100 preferably includes a handle holder 110 to facilitate manual use thereof. As used herein, the term "oxygen" includes both pure oxygen and gas mixtures containing oxygen, which have an oxygen content at least as high as that of air. The coating material is in the form of a. powder having a particle size of preferably from about 5 to about 500 microns. When the system is in operation, the powder of the coating material is fluidized by a stream of air, and both the air and the particles of coating material are supplied to the thermal spray gun 100, to apply a coating 12 to the surface of a substrate 14. The coating material can be any thermoplastic polymeric material that can be melted without significant degradation. Such thermopolymers include, but are not limited to, polyethylene (low and high density), polypropylene (low and high density), polyurethane (low and high density), nylon (for example, nylon 6, nylon 11), copolymers nylon, EVA, EEA, ABS, PVC, PEEK, PVDF, PTFE (for example, Teflon®) and other polymers of fluorocarbon, polycarbonate, pyrilates, polyethers, polyesters, epoxy resins, silicones and chemical and / or physical combinations thereof . Additional components in the coating material may include metals (eg, zinc, aluminum, zinc-aluminum alloy, alloy of ferrous metals, copper and copper alloys, etc.) as a separate powder or clay powder, ceramics, coal, graphite, or functional components such as dyes, electrically conductive materials (for example, for electromagnetic shield), fluorescent or phosphorescent materials, anti-fouling agents, reflective materials, radar absorbing materials, UV protectors, anti-microbials and similar. The substrate 14 to which the coating material is applied may be porous or non-porous metal (e.g., steel, aluminum), wood, cork, glass, ceramic, solid or foamed polymeric material, paper-containing material, asphalt material, plaster , cement, concrete, stone or other materials capable of receiving a coating. Several applications for thermal spray coating include spraying or bridge coating, ships, aircraft, land transport vehicles, buildings, highway or other printed signs, road markings, various structures in marine environments such as springs or piers, and any other operation in which the spray application of a polymer-containing coating material is suitable.

All supply inputs for A, F, 0 and CM have means to individually regulate the flow rates and / or pressure to allow the operator to. Thermal spray gun make adjustments. The variation of the flow velocities and / or individual variations of the flight distance of the coating material between the thermal spray gun leaves and the surface of the substrate to be coated may produce smooth surface coatings or rough surface coatings or a variety of different different physical coatings as desired. Referring now to Figures 2 and 3, the coating application system includes a dual venturi system for controlling the coating material feed from the CM coating material supply or the thermal spray gun 100. More particularly, the air derived from an AC source of compressed air is divided into individually controlled streams A, B, C and D. The stream A, as stated above, is connected directly to the thermal spray gun 100. The stream B is the fluidized bed air supply. Current C is the air supply of regulated material feed rate. The stream D is the air supply of regulated material supply.

The supply of coating material CM includes a hopper 20 in which a bed of particles 23 of coating material is contained and supported on a porous fluidized bed support plate 22. The compressed air of the fluidized bed air supply stream B is directed through the air supply line 24 of the fluidized bed to a plenum chamber through, under the support plate 22. The compressed air rises through the support plate 22 and fluidizes the particle bed 23. The compressed air of the stream C is directed through the conduit 25 to a first vent 26, and through the axial channel 27 of the ventura. The particles of the fluidized coating material are withdrawn into the channel 27 via the inlet 29 and are directed towards the second ventura 30. The port or port 21 serves to equalize the pressure between the inside and outside of the hopper 20. The inlet 28 serves as a siphon port of the material and / or the air siphon port. The compressed air of the stream D of 1 supply air of the material is directed towards the air injection nozzle 31 of the second venturi 30. The particles of coating material are discharged from the first venturi or the extracted air through the port u orifice 28 of the siphon are directed towards the axial channel 32 of the second venturi and are conveyed to the thermal spray gun 100, for example, through a flexible tubular conduit, tube or other suitable means. The use of the first and second controlled venturis provides superior control of the coating process. In addition, the dual venturi system overcomes the problem associated with single venturi systems, ie slow speed, material replenishment and undesirable pulsating operation as opposed to the smooth flow of material. it should be noted that the dual ventura system (figures 2 and 3) for the supply of material described above can be used for the supply of material to any assortment apparatus or for any purpose where a controlled supply of powdered material is needed fluidized In addition, although the system is described here with compressed air as the driving fluid, any gas can be used (eg, nitrogen, inert gases such as helium or argon, oxygen, carbon dioxide, etc.) in the dual venturi system described above depending on what is appropriate for any desired purpose. Referring now to Figures 4 to 8, the gun body 120 is an elongate member, preferably made from aluminum alloy or any other suitable metal. The axial channel 122 is adapted to receive and direct a fluid stream of the compressed air and the coating particles distally towards the discharge end portion of the air gun 100. The oxygen stream is transmitted longitudinally and distally through the oxygen supply channel 121, and then through the oxygen supply channel 125 which is angled towards the outlet 136 at the angle a with respect to the X axis of the gun body. The fuel gas F is transmitted longitudinally through the fuel gas supply channel 124 (Fig. 7) and then through the fuel gas supply channel 127 which is angled to the common fuel oxygen-gas outlet 136, preferably also at an angle o / in relation to the X axis of the gun body. The angle α preferably ranges from about 30 ° to about 80 °, more preferably from about 40 ° - to about 50 °, although angles outside these ranges may be used when considered appropriate. Due to the angled orientation of the oxygen supply channel 125 and the fuel gas supply channel 127, a dual apex is formed in the vortex gas mixing chamber 115 (Fig. 4) described below. Oxygen flows in a circular direction and the fuel gas flows in the opposite direction to provide vortex mixing of oxygen and fuel gas. The compressed air is transmitted longitudinally and distally through the air supply channel 123 and then through the air supply channel 126, which subsequently bifurcates to the inclined passages 126A and 12b (Fig. 8) ending in the surface 137 distal of the gun body. The distal end of the body 120 of the gun includes a nozzle seat 128, which is a recess configured and sized to receive the proximal portion of the nozzle 150. The diffuser seat 133 is a recess configured and sized to receive the diffuser ring 140. The opening 131 is configured and sized to receive the alignment pin 111, which maintains a stationary position of the diffuser ring 140 and the nozzle 150 'when these components are mounted in their respective seats 133 and 128. The threaded portion 135 is adapted for threaded connection of a body 190 of the air cap. The distal end portion of the gun body 120 also includes a mounting surface 134 that extends generally cylindrically distally to mount the cover 170 of the air distributor. Referring now to Figures 9A, 9B and 9C, the nozzle 150 comprises a generally cylindrical body having a proximal stem portion 151a and a distal flange portion 151b. The portion 151a of the rod is adapted to be received in the nozzle seat 128 of the gun body. The O-rings 159a, 159b, sit on the corresponding circumferential recesses 151e and extend circumferentially around the circumferential periphery 151c of the nozzle 150 to provide a gas seal and secure the seat. The O-ring 159c is positioned around the proximal end portion of the rod 151a. The nozzle 150closes an axial passage 152 through which the fluidized coating material and the carrier gas move. The passageway 152 includes a portion 152a having a constant diameter and a distal portion 152b that widens outwardly. The flange portion 151b includes a plurality of passages 155 oriented in a longitudinal direction (i.e., parallel to the axis) of the nozzle for passage through the fuel gas and oxygen. The passages 155 include proximal portions 155a having a section - transverse of relatively wider diameter and the distal portions 155b having a relatively narrower cross section. The passages 154 of the flange portion 151b are angled so as to have a radial portion 154a and a longitudinally extending portion 154b. The passages 154 admit air in the opening in the circumferential periphery 151c of the flange portion 151b and the discharge air in the distal end surface 151d of the nozzle.

The recess 153 is adapted to receive the alignment pin 111. The unique configuration of the nozzle 150 allows sufficient control of the flow of the flame, air and coating material to allow an air curtain to protect the particles of the coating material from degradation by excess heat. Instead, sufficient heat is provided to melt the particles that are then projected onto the surface of the substrate. Referring now to Figures 9a and 9B, it can be seen that the distal outlets for the passages 155 and 154 are generally arranged around the distal end surface 15Id of the nozzle in the respective concentric circular arrays in an alternating or staged pattern. However, the outlets for the air passages 154 are concentrically closer to the passageway 152 of the facing material by a distance D, thus providing an air curtain interposed between the high-temperature combustion gases of the oxygen flame. fuel gas and the flow of the coating material. Thus, the coating material is heated sufficiently to cause fusion but does not burn, or degrade by the combustion flame jets. The distance D may be any suitable distance for the purposes described herein and may typically vary from about 0.1 to about 5.0 mm, although distances outside this range may be employed where appropriate. Referring now to Figure 10, the diffuser 140 includes a ring-shaped body 141 having an axial opening 142 through which portion 151a of the nozzle stem is disposed. The circumferential wall 141a and the annular wall 141b of proximal surface together at least partially define a vortex gas mixing chamber 115 for the mixing of the fuel gas and oxygen. The alignment opening 144 is adapted to receive the alignment pin 111 which is longitudinally disposed therethrough and then in the recess 153 of the nozzle as discussed above. The lateral opening 143 admits the mixing of fuel and oxygen from the vortex gas mixing chamber 115 into a mixing chamber 116 of the second vortex (Fig. 4) at least partially defined by the annular surface 146 of the ring's distal cover diffuser (Fig. 10) and the cover surface 156 of the flange portion 151b of the nozzle (Figs 9B and 9C). As mentioned above, the dual purpose vortex mixing by the apparatus of the invention avoids flame return and provides stable operation of the gun as well as other benefits. Referring now to Figure 11, the diagrammatic end view illustrates the flow from the oxygen supply channel 121 and the fuel gas supply channel 124 leaving the common outlet 136 and flowing through the mixing chamber 115 of the gas from the first vortex, then through the side openings 143 in the diffuser 140, and into the gas mixing chamber 116 of the second vortex, from which it enters and flows through the fuel and oxygen passages 155 of the nozzle 150. Referring now to Figures 12A and 12B, the cap 170 of the air distributor includes a ring-shaped body 171 and an axial passage 172. The alignment pin 112 (Fig. 4) is received in the recess. 173 of the cover 170 of the air distributor (Fig. 12B) to align and secure the cap of the air distributor to the body 120 of the gun. The air distributor cap includes a plurality of radial ports 174 for conducting air from a first annular air flow chamber 117 (Figs., 11) to a second air flow chamber 118 (Fig. 4) from which air is conducted to and through openings 154 in the nozzle. Air enters the first air flow chamber 117 through the air supply channels 126a, 26b (Fig. eleven) . The air jet holes 175 are angled inward and provide a compression wave as the compressed air passes through and is injected into the flame. Referring to Figure 13, the body 190 of the air cap includes a ring-shaped member 191 generally having an axial passage 192. The interior surface 193 of the body includes a threaded portion 195 for the threaded engagement with the threaded portion 135 of the gun body (Figs 6, 7). The first annular air flow chamber 117 is at least partially defined by the inner surface 193 of the air cap body and the outer surface 176 of the air distributor cap 170 (Fig. 12B). In operation, the coating material is passed through the flame of the oxygen-fuel gas at the discharge end of the spray gun where it melts into droplets. The flame is a jet flame formed by the compression wave provided by the compressed air directed at an angle inward towards the axis of the apparatus. The air streams discharged through the nozzle provide a thermal "mattress" to prevent the particles of the coating material from degrading due to overheating. The control, separated from the fuel supply F, the oxygen supply 0, the compressed air A, and the first and second ventures 26 and 30 for the CM supply of coating material, allows the user to have superior control of the spraying process . A wide variety of coating materials can be used with excellent coating efficiency and quality. While the foregoing description contains specific issues, these specific issues should not be considered as limitations of the invention, but only as exemplifications of the preferred embodiments thereof. Those skilled in the art will be able to suggest many other modalities within the scope and spirit of the invention as defined by the appended claims.

Claims (26)

1. CLAIMS 1. A thermal spray coating system, characterized in that it comprises: a) a spray gun applicator providing means for projecting the coating material through a reduced temperature zone of a flame region and onto a substrate, the spray gun applicator includes: a gun body having an axial conduit for the passage therethrough of the coating material, said gun body includes a fuel gas supply conduit, an oxygen supply conduit, and a compressed air conduit, and a mounting mounted on a distal end portion of the gun body that includes a nozzle having a plurality of first channels for distally ejecting streams of oxygen-fuel gas mixtures into the flame region to provide high temperature combustion gases and having a plurality of second channels for distally ejecting them. compressed air entities towards the flame region to provide the reduced temperature zone, the assembly further includes a cover of the air distributor having a plurality of ports or orifices for discharging the compressed air distally in an inwardly angled direction, towards the axis of the gun body and towards the flame region to provide a compression wave to rapidly melt the coating material; and b) means for supplying coating material to the spray gun applicator.
2. 2. The thermal spray coating system according to claim 1, characterized in that the assembly further includes a first annular chamber for the vortex mixing of the fuel gas and oxygen, and a second annular chamber for the vortex mixing of the gas fuel and the oxygen that flows from the first annular chamber.
3. 3. The thermal spray coating system according to claim 1, characterized in that the nozzle has an axial passage for the passage therethrough of the coating material, a proximal rod portion and a distal flange portion, said portion The flange includes the plurality of first and second channels in alternating arrangement, the first channels extend longitudinally through the flange portion and the second channels respectively have radially oriented portions with inlet openings arranged around a circumferential periphery of the portion of the flange portion. flange and longitudinally oriented portions.
4. 4. The thermal spray coating system according to claim 3, characterized in that the first channels have respective distal outlets disposed in an array generally circular to a distal end surface of the nozzle, and the longitudinally oriented portions of the second channels terminate in respective distal outputs arranged in a generally circular array on the distal end surface of the nozzle, the circular arrangement of the outputs of the second channels are concentric and smaller than the circular arrangement of the distal outputs of the first channels.
5. 5. The thermal spray coating system according to claim 1, characterized in that the means for supplying the coating material comprises: a fluidized bed of particles of coating material; first venturi means for conveying a stream of the coating material particles in compressed air from the fluidized bed; second venturi means for receiving the stream of the particles of the coating material from the first venturi means and conveying the stream of the coating material particles to the applicator of the spray gun, wherein each of the first and second means it is independently controlled by the respective individual streams of compressed air.
6. 6. The thermal spray coating system according to claim 5, characterized in that the coating material comprises a thermoplastic or thermosetting polymeric polymer material. The thermal spray coating system according to claim 1, characterized in that the polymeric material is selected from the group consisting of epoxy resins, polyurethanes, nylons, polyesters, polycarbonates, polyethylene, polypropylene, acrylic polymers, PVC resins, polymers of fluorocarbons, EVA, PEEK, PVDF, silicones and chemical and physical combinations thereof. 8. The thermal spray coating system according to claim 5, characterized in that the coating material includes zinc, aluminum, zinc-aluminum alloy, alloys of ferrous metals, copper, copper alloys or ceramics. 9. The thermal spray coating system according to claim 5, characterized in that the coating material includes colorants, electrically conductive materials, fluorescent materials, phosphorescent materials, anti-fouling agents, reflective materials, radar absorbing materials or UV protectors. . 10. The thermal spray coating system according to claim 5, characterized in that the coating materials have a particle size range from about 5 microns to about 500 microns. 11. The thermal spray coating system according to claim 1, characterized in that the coating material is in the form of a wire. 12. The thermal spray coating system according to claim 1, characterized in that the applicator of the spray gun is portable and includes a grip handle. 13. An applicator of a thermal spray gun according to claim, characterized in that: a gun body having an axial conduit for the passage therethrough of the coating material, said gun body includes a supply conduit for fuel gas, an oxygen supply conduit, and a compressed air conduit, and a mounting mounted on a distal end portion of the gun body that includes a nozzle having a plurality of first channels for distally ejecting mixtures streams oxygen-gas fuel towards the region of the flame to provide high temperature combustion gases and having a plurality of second channels for distally ejecting the compressed air streams towards the flame region to provide a reduced temperature zone , the assembly also includes a first ring chamber for the vortex mixing of fuel gas and oxygen no, and a second annular chamber for the vortex mixing of the fuel gas and the oxygen flowing from the first annular chamber. 14. The applicator of the thermal spray gun according to claim 13, characterized in that the assembly further includes an air distributor cap having a plurality of ports or orifices for discharging compressed air distally in an inwardly angled direction, toward the shaft of the gun body and towards the region of the flame to provide a compression wave. 15. A method for coating a substrate with a coating material, the method characterized in that it comprises: a) providing a flame region of the hot combustion gases; b) ejecting the compressed air in the region of the flame to provide a zone of reduced temperature; c) directing the compressed air at an angle towards the region of the flame to provide a compression wave; d) project coating material through the reduced temperature zone and onto the substrate. 16. The method of forming with claim 15, characterized in that the substrate is metal, wood, cork, glass, ceramic, polymeric material, paper-containing material or asphalt material. 1
7. 7. The shaping method according to claim 15, characterized in that the coating material contains polymeric resin. 1
8. 8. The shaping method according to claim 17, characterized in that the coating material is a particulate material having a particle size from about 5 microns to about 500 microns. 1
9. 9. The shaping method of claim 16, characterized in that the step of providing a flame region comprises burning the oxygen-fuel gas mixture directed as a ring of streams towards the flame region. 20. The shaping method according to claim 19, characterized in that the step of ejecting the compressed air to the flame region to provide the reduced temperature zone comprises ejecting a ring of compressed air streams concentric to the ring of the oxygen streams. -gas fuel, but interposed between the combustion gases and the coating material. 21. An apparatus for supplying powder material, characterized in that it comprises: a fluidized bed of particles of powder material contained within a housing; a first venturi for conveying a stream of the particles of powder material in compressed gas from the fluidized bed; a second venturi for receiving the stream of the particles of the powder material from the first venturi and ejecting the stream of powdered material particles, wherein each of the first and second venturis is independently controlled by a respective individual stream of compressed gas . 22. The apparatus according to claim 21, characterized in that the powder material comprises a thermoplastic or thermosetting polymeric material. 23. The apparatus according to claim 22, characterized in that the polymeric material is selected from the group consisting of epoxy resins, polyurethanes, nylons, polyesters, polycarbonates, polyethers, polyethylene, polypropylene, acrylic polymers, PVC resins, fluorocarbon polymers, EVE,. EAA, ABS, PEEK, PVDF, silicones and chemical and physical combinations thereof. 24. The apparatus according to claim 21, characterized in that the coating material includes zinc, aluminum, zinc-aluminum alloy, alloys of ferrous metals, copper, copper alloys or ceramics, carbon or graphite. 25. The apparatus according to claim 21, characterized in that the powder material includes colorants, electrically conductive materials, fluorescent materials, phosphorescent materials, anti-soiling agents, reflective materials, radar absorbing materials, anti-microbial or UV protective. 26. The apparatus according to claim 21, characterized in that the particles of powder material have a particle size range from about 5 microns to about 500 microns.