EP0365225A2 - Powder or solid particulate material spray gun - Google Patents
Powder or solid particulate material spray gun Download PDFInfo
- Publication number
- EP0365225A2 EP0365225A2 EP89310506A EP89310506A EP0365225A2 EP 0365225 A2 EP0365225 A2 EP 0365225A2 EP 89310506 A EP89310506 A EP 89310506A EP 89310506 A EP89310506 A EP 89310506A EP 0365225 A2 EP0365225 A2 EP 0365225A2
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- EP
- European Patent Office
- Prior art keywords
- amplifier
- particulate material
- solid particulate
- nozzle
- spray gun
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
- B05B7/1481—Spray pistols or apparatus for discharging particulate material
- B05B7/1486—Spray pistols or apparatus for discharging particulate material for spraying particulate material in dry state
Definitions
- This invention relates to the spraying of solid particulate materials, and more particularly, to improved apparatus for spraying solid particulate materials.
- This invention is an improvement upon the apparatus disclosed in U.S. Patent No. 4,600,603 entitled “Powder Spray Apparatus and Powder Spray Method” and in U.S. Application Serial No. 097,946 entitled “Powder Spray Gun", both of which are assigned to the assignee of this application.
- the powder spray apparatus disclosed in the above identified patent comprises two series aligned air flow amplifiers, both of which are mounted upon supporting bodies. These bodies are in turn mounted in an adjustable manner upon a supporting rod.
- One of the air flow amplifiers is connected to a source of air-entrained powder, whilst the other, downstream from the first amplifier, is connected to a powder discharge nozzle.
- the spacing of the bodies, and thus the spacing between the air flow amplifiers, is adjustable so as to obtain optimal spray patterns and powder velocities from the apparatus in accordance with the needs or requirements for a particular powder spray application.
- the adjustability of the powder spray gun of the above identified patent is sacrificed in the powder spray gun of the above identified pending application in order to achieve a spray gun which is easier to assemble and disassemble, as for example, for cleaning of the apparatus, and easier to obtain repeatable flow patterns and velocities after disassembly and reassembly of the gun.
- the powder spray gun disclosed in this pending application comprises a housing having a generally tubular sidewall and an axial bore, which extends through the housing and is intersected by at least one ambient air flow passage extending through the sidewall of the housing.
- a first or so-called “pattern air flow” amplifier is mounted in one end of the housing on one side of the ambient air flow passage, and a second so-called “suspension air flow” amplifier is mounted in the opposite end of the tubular housing on an opposite side of the ambient air flow passage from the first air flow amplifier.
- Both amplifiers include means for directing a stream of compressed air into a powder flow passage of the amplifier so as to draw ambient air through the ambient air flow passage of the housing into the powder discharge opening of the powder flow passage of the first amplifier and into the powder inlet opening of the flow passage of the second amplifier.
- powder spray guns employ flat fan spray nozzles or other restricted orifice discharge nozzles on the discharge end of the guns in order to achieve a desired spray patter.
- spray guns of the type described in the above identified patent or pending application utilize such restricted orifice nozzles in the discharge end of the gun, through, the back pressure created by the restricted orifice of the nozzle causes powder to puff out of the ambient air flow passage between the two amplifiers of the gun.
- powder puffing from the ambient air flow passage of the gun is wasteful of powder, but more importantly, that powder enters and undesirably contaminates the atmosphere surrounding the gun.
- This invention aims to provide a dual air amplifier powder spray gun which is not subject to the puffing or emission of powder from the ambient air flow passage between the amplifiers of the gun when the gun is used to spray powder from a restricted orifice discharge nozzle.
- a solid particulate material spray gun in accordance with one aspect of the invention comprises a tubular housing, the bore of which is intersected by at least one ambient air flow passage extending through the sidewall of the housing, a first air flow amplifier mounted within the tubular housing on one side of the ambient air flow passage, the first amplifier having a solid particulate material flow passage extending axially therethrough and means for directing a stream of compressed air into the flow passage of the first amplifier, a second air flow amplifier mounted within the tubular housing on an opposite side of the ambient air flow passage from the first amplifier, the second amplifier having a solid particulate material flow passage extending axially therethrough and means for directing a stream of compressed air into the solid particulate material flow passage of the second amplifier, a discharge nozzle in fluid communication with the second amplifier, the nozzle having a restricted discharge orifice and means for preventing the egress of solid particulate material from the ambient air flow passage of the housing caused by back pressure generated from the restricted discharge orifice of the discharge nozzle.
- a filter of porous material may be placed around the ambient air flow passage of the gun so as to prevent the egress of powder through the passage while still permitting the free flow of air at ambient pressure through the porous filter.
- Polyfoam material or sintered metal may be used to form the filter, which, may be located on the exterior or interior of the housing and cover the ambient air passages.
- a solid sleeve may be placed between the two air amplifiers of the gun so as to completely block the egress of powder through the air passages as well as the ingress or egress of ambient air.
- a solid particulate material spray gun having a discharge nozzle, the nozzle having a restricted discharge orifice, includes means for reducing the back pressure generated when air-entrained solid particulate material is sprayed from the restricted orifice of the nozzle.
- This means suitably comprises one or more vent holes provided in the nozzle adjacent to the restricted discharge orifice of the nozzle.
- the back pressure reducing means may be incorporated into any spray gun having a restricted discharge orifice and may be used with or without the egress prevention means of the first aspect of the invention.
- FIG. 1-5 there is illustrated a powder spray gun 10 utilized in the practice of this invention.
- This gun 10 comprises a generally cylindrical, tubular housing 12 within which there are located a pair of air flow amplifiers 14 and 16.
- the housing 12 and amplifiers 14 and 16 are so constructed that the amplifiers may be simply slipped into the housing and retained therein by top and bottom mounting caps 18 and 20, respectively.
- Each air flow amplifier 14 and 16 comprises a two-piece assembly, a body 14a, 16a and a nozzle 14b, 16b.
- the lower air flow amplifier 16 the so-called "pattern” amplifier
- the other amplifier 14 the so-called "suspension” amplifier
- a lock-nut 30 is optionally threaded onto the nozzle assembly so as to lock the two-piece air flow amplifier 14 in an assembled relationship.
- Both the top and bottom caps 18 and 20 are assembled onto the housing by bayonet-type pin 32 and slot 34 connectors 33.
- these connectors each comprise a pair of generally L-shaped slots 34 machined into the peripheral surface of the caps 18, 20 and adapted to receive pins 32 fixedly mounted in the housing 12.
- These pin and slot connectors 33 enable the caps to be very quickly assembled onto the housing or very quickly disassembled therefrom.
- the complete gun including the housing 12, two two-piece air amplifiers 14 and 16, and the top and bottom caps 18 and 20 comprises only a seven-piece assembly if both amplifiers are assembled by bayonet-type pin and slot connectors or eight pieces if the lock nut 30 is included in a threaded type amplifier.
- this seven (or eight) piece assembly may very quickly be assembled and disassembled so as to facilitate cleaning of the gun.
- This assembly is also very compact and, as explained more fully hereinafter, requires no adjustment of the amplifiers or of any other component of the gun once it has been assembled.
- the housing 12 of the gun is configured as a cylindrical sleeve.
- This sleeve has three large apertures 40 machined from the sidewall thereof.
- the upper section 42a of the sidewall 42 is separated from the lower section 42b by three equidistantly spaced, vertically extending posts 42c (see Figure 4).
- a flange 44 which extends inwardly from the sidewall of the housing. This flange has an axial bore 46 formed therein, which bore receives the lower end of the suspension amplifier 14. Located immediately above the flange 44 there is a threaded port 48, which port receives a conventional threaded air fitting 47. The fitting is, in the use of the gun 10, connected to a source of compressed air (not shown).
- This flange Located immediately below the posts 42c there is another internal flange which extends into the interior of the housing from the sidewall 42. This flange also has an axial bore 52 for the reception of the pattern amplifier 16.
- a threaded port 49 similar to port 48, is located immediately below the flange 50 of the housing. This port extends through the sidewall 42 and receives a conventional compressed air fitting 53 through which compressed air is supplied to the gun 10.
- pins 32 of the bayonet-type pin and slot connectors 33 Extending inwardly into the interior of the tubular housing 12 adjacent the top and bottom ends thereof, there are a pair of pins 32 of the bayonet-type pin and slot connectors 33. These pins 32 are preferably press fitted into holes 32a machined into the side walls 42 of the housing. As mentioned hereinabove, these pins are adapted to be received within slots 34 machined into the top and bottom caps 18 and 20, respectively, so as to enable those caps to be removably secured to the housing.
- the suspension amplifier 14 comprises a body 14a and a nozzle 14b.
- the two pieces, the nozzle 14a and body 14b, are both generally tubular in configuration and are retained in an assembled relationship with the nozzle contained internally of the body by the threaded connection 28.
- This connection comprises external threads 28a on the periphery of the nozzle 24b and internal threads 28b on the interior of the body 14a.
- the body 14a has an axial bore 66 extending therethrough. This bore is of larger diameter at the upper end and smaller diameter at the lower end. Between the two different diameter sections there is a shoulder 68. Additionally, there is an annular channel 70 around the interior of the bore 66 adjacent to the intersection of the threaded and unthreaded sections of the upper large diameter portion of the bore. Between the annular channel 70 and the shoulder 68 there is a radial hole 72 through which compressed air may pass from the exterior to the interior of the body 14a.
- the lower end of the body 14a is slidably received within the bore 46 of the housing 12.
- An O-ring 74 located within an annular groove in the periphery of the body forms a seal between the body 14a and the bore 46.
- the bore 66 tapers inwardly and downwardly. This taper functions to focus air-entrained powder passing through the amplifier 14 into the open upper end of the lower pattern air flow amplifier 16.
- the nozzle 14b of the suspension amplifier 14 is provided with a peripheral flange 80 upon which the threads 28a are formed. Below this flange 80 there is a section of reduced diameter 81 separated from the threaded section 80 by a shoulder 82. The reduced diameter section 81 terminates in an outwardly flared lower end 84 of the nozzle which abuts the shoulder 68 of the body 14a.
- the shoulder 68 of the body forms a seat for the lower flared end 84 of the nozzle 14b.
- recesses 88 machined from the shoulder 68.
- the shoulder comprises three raised sections or ribs 90 against which the lower end 84 of the nozzle 14b abuts, with the recesses 88 being located between the ribs.
- it preferably has flats 91 formed or machined on the upper end of the nozzle 14b.
- the lower or pattern amplifier 16 comprises the nozzle 16a and body 16b. Both the body 16a and nozzle 16b are generally cylindrical in configuration.
- the nozzle of the amplifier 16 is secured to the body by a bayonet-style pin and slot connection 25 substantially identical to the pin and slot connectors 33 ( Figure 3) which connect the top and bottom caps to the housing.
- This connection 25 comprises a pin 24 which is received within a generally L-shaped slot 26 of the nozzle so as to secure the two pieces in an assembled relation.
- An O-ring 122 contained within an annular groove of the nozzle seals the periphery of the nozzle relative to the interior bore 124 of the body 16a.
- the body 16a has a smaller diameter upper end section 128 which is received within the bore 52 of the housing 12.
- the exterior surface of this section of the body is sealed relative to the bore 52 by an O-ring mounted within an annular groove in the surface of the upper end section 128 of the body.
- the lower larger diameter section 132 of the body is received within the bore of the housing, but is spaced from the interior surface thereof so as to define an annular channel 134 therebetween.
- This channel 134 functions as an air flow passage, as explained more fully hereinafter, for the flow of compressed air to the air flow amplifier 16.
- the annular channel 134 communicates with an interior channel 136 on the inside of the body by means of a hole 138 in the sidewall of the housing.
- the nozzle 16b is also tubular in configuration and has an axial bore 147 extending therethrough. At its upper end, the sidewall of the nozzle is flared outwardly, as indicated at 150. The upper end of this flared end wall rests against the shoulder 146 of the body. In order for air to flow from the annular channel 136 around the flared end 150 of the nozzle, as indicated by the arrow 162, there are recesses 164 machined from the surface of the shoulder 146. These recesses are identical in configuration to the recesses 88 in the shoulder 68 of the upper suspension amplifier 14. These recesses define ridges 166 therebetween against which the upper end of the nozzle abuts. Consequently, compressed air is free to flow from the channel 136 through the recesses 164 machined from the shoulder 146 and into the interior of the nozzle.
- the pattern amplifier 16 preferably has flats 148 machined or formed on the lower end of the nozzle 16b to facilitate assembly or disassembly of the nozzle by engagement of the flats with a wrench.
- the top cap 18 functions to retain the suspension amplifier 14 assembled within the housing 12.
- the generally tubular-shaped top cap has an axial bore 100 extending therethrough.
- This bore has a small diameter upper end section 102, a larger diameter intermediate section 104, and a large diameter lower end section 106.
- the small diameter upper end section 102 of the cap is adapted to be placed in fluid communication with a source of air-entrained powder.
- the intermediate diameter section 104 fits over the upper end of the nozzle 14b of the amplifier 14 and is sealed relative thereto by an O-ring seal 108 located within an annular channel in the periphery of the nozzle.
- the large diameter section 106 of the bore of the cap is received over the upper end of the body 14a of the amplifier 14.
- the lower end of the top cap 18 has a pair of generally L-shaped bayonet slots 34 (See Fig. 3), which receive the pins 32 in the upper end of the housing 12.
- the pin 32 slides in the slot 34 and functions to clamp the top cap to the top end of the housing.
- the lower or pattern amplifier 16 is retained within the housing 12 by the bottom cap 20.
- This cap is also tubular in configuration and has an axial bore 112 extending therethrough.
- the lower small diameter end section of this bore is adapted to be placed in fluid communication with a powder spray nozzle (not shown).
- the upper large diameter end section of this bore 112 is received over the lower end of the amplifier nozzle 16b and is sealed relative thereto by the O-ring 114.
- Another O-ring 116 mounted in an annular groove in the periphery of the bottom cap 20 seals the exterior of the bottom cap relative to the interior of the housing 12.
- This lower O-ring seal 116 cooperates with the pin and slot connector 33 to retain the bottom cap in an assembled relation on the housing with the bottom amplifier 16 contained interiorly thereof.
- the powder spray gun 10 is assembled by first assembling the suspension amplifier 14. This is accomplished by threading the nozzle 14b of the amplifier 14 into the body 14a until the end surface of the flared end 84 of the nozzle engages the top surface of the ridges 90 on the shoulder 68. With the nozzle and body so assembled, the locknut 30 is threaded onto the upper end of the nozzle until the bottom surface of the locknut engages the top surface of the body 14a. An O-ring 35 contained within an annular groove of the nozzle then forms an air seal between the nozzle 14b and body 14a. With the top cap 18 removed from the housing 12, the assembled suspension nozzle 14 is then dropped into the housing.
- the lower end, or so-called "nozzle” end of the body then slides through the axial bore 46 of the housing until a shoulder-defined between the lower end of the body 14a and the upper end contacts the top surface of the flange 44.
- the O-ring 74 then forms an air seal between the body 14a and the flange 44 of the housing.
- the top cap 18 of the gun is then placed over the top of the housing and over the top of the amplifier 14.
- the bayonet slots 34 of the top cap then slip over the pins 32 such that when the top cap is then rotated, the top cap clamps the amplifier 14 on the interior of the housing.
- the O-ring seal 110 then cooperates with the bayonet pin and slot connector 33 so as to fixedly secure the top cap to the top of the housing.
- the O-ring seal 108 then forms a seal between the nozzle of the amplifier and the bore of the top cap.
- the lower or pattern amplifier 16 is next assembled by placing the nozzle 16b within the body 16a.
- the nozzle and body are then secured together by locating the pin 24 within the slot 26 of the nozzle and rotating the nozzle relative to the body.
- This bayonet slot connection 25 then secures the nozzle within the body with the O-ring seal 122 then forming a seal between the nozzle and body.
- the upper end of the nozzle 166 rests against the bottom surface of the ridges or ribs 166 of the shoulder 146.
- the pattern amplifier 16 is then inserted into the housing 12 with the upper end of the body 16a of the amplifier received within the bore 52 of the housing.
- the O-ring seal 130 then forms an air seal between the bore 52 of the housing and the upper end of the body 16a.
- the amplifier 16 is then secured within the housing by placement of the bottom cap 20 over the lower end of the nozzle of the amplifier 16.
- the slots 34 of the bottom cap 20 are then inserted over the pins 32 and the bottom cap rotated so as to secure the bottom cap to the lower end of the housing with the O-ring seal 116 compressed therebetween.
- the O-ring 114 then forms a seal between the exterior of the amplifier and the interior bore of the bottom cap.
- the powder spray gun 10 of this application differs from the powder spray gun of the above-identified application in that it includes means for preventing the egress of solid particulate powder through the ambient air flow passages of the gun.
- a filter 190 surrounds the ambient air flow passages 40 and is of a porosity which will prevent the egress of powder from the passages 40 while still permitting the free flow of air at ambient air pressure.
- a powder spray nozzle 200 is secured over the bottom tubular end section 112 of the bottom cap.
- the nozzle is preferably secured to the lower end of the bottom cap by O-rings 180, 181 mounted in annular grooves in the peripheral surface of the bottom cap.
- a plurality of equidistantly spaced, radial vent holes or ports 210 are provided in the sidewall of the nozzle 200. These vent holes extend between the exterior of the nozzle and the internal passage 208. The function of the nozzle vent holes 210 is to relieve back pressure created by the restricted orifice 202 of the nozzle 200, which back pressure, in the absence of the vent holes 210 and the filter 190, tends to push powder out the ambient air flow passages 40 of the housing 12.
- compressed air is supplied to the air fittings 47, 53 mounted in each of the threaded bores 48 and 49 of the housing 12.
- Compressed air supplied to the fitting 47 passes through an annular channel contained interiorly of the housing 12, through the bore 72, into the channel 70 located internally of the amplifier 14. From this channel, the compressed air passes through the recesses 88 defined between the bottom surface of the end of the nozzle and the top surface of the shoulder of the nozzle body.
- This compressed air then, is directed in a generally upward direction when it emerges from the recesses 88. Because it is so directed, it creates a vacuum in the lower end of the nozzle body 14a which tends to draw ambient air from the exterior of the housing, through the apertures 40, into the interior of the housing and into the lower end of the amplifier 14.
- Compressed air at a pressure usually substantially greater than that supplied to the fitting 47 and threaded port 48, is also supplied to the fitting 53 and port 49.
- This compressed air passes through the annular channel 134 defined between the interior of the housing and the exterior of the amplifier body 16a, through the aperture 138 in the amplifier body, and into the annular channel 136. From this channel 136 the air passes upwardly around the upper flared end of the nozzle through the recesses 164 and downwardly into the axial centre bore of the nozzle.
- This high pressure air draws ambient air through the passage 40 of the housing downwardly into the open upper end of the amplifier 16.
- the air-entrained powder flows downwardly through the suspension amplifier 14.
- the air-entrained powder is subjected to turbulence created by the upwardly directed compressed airstream flowing through the recesses 88 of the amplifier.
- This air-entrained powder passes through the suspension amplifier and is focused and directed by the lower discharge nozzle end 69 of the amplifier body 14a of the suspension amplifier into the open upper end of the lower pattern amplifier 16.
- the velocity of the powder is increased by the high velocity, downwardly directed airstream emitted through the recesses 164 of the pattern amplifier.
- This high velocity airstream causes a vacuum at the inlet to the pattern amplifier 16 which pulls air into the amplifier from the surroundings through the passages 40 of the housing. Simultaneously, the high velocity air flow through the lower pattern amplifier draws air-entrained powder from the upper suspension amplifier 14. In the course of passage through the pattern amplifier, the velocity of the powder is markedly increased. The high velocity powder is then caused to flow from the gun through the nozzle 200 via the discharge passage 112 in the bottom cap 20.
- the filter 190 is provided.
- This filter is preferably a sintered bronze filter in the form of a sleeve which surrounds the housing and covers the passages 40 so as to prevent the egress of powder from the housing through the passages 40, which would otherwise occur because of this back pressure.
- the porosity of the filter 190 is selected so that it will prevent the egress of air-entrained powder but will still permit the free flow of air at ambient pressure through the filter.
- the filter 192 comprises an annular filter made from polyfoam material, which filter fits over the lower end 69 of the nozzle body 14a and extends between that lower end of the nozzle body and the posts 42c.
- the polyfoam filter is made from a polyester foam material having 35 pores per linear inch.
- the powder spray gun of Figure 6 is identical to the powder spray guns of Figures 1-5.
- a polyfoam filter may be located on the exterior of the gun, as illustrated in Figure 1. In that event, the polyfoam filter would be substituted for the sintered metal filter 190 of Figure 1.
- a polyfoam filter on the interior of the gun as illustrated in Figure 6 is to substitute a sintered metal filter on the interior of the gun for the polyfoam filter 192 illustrated in Figure 6.
- FIG. 7 With reference now to Figure 7, there is illustrated a second embodiment of the invention of this application.
- This embodiment incorporates a spray gun 10′ substantially identical to the spray gun 10 of the modification illustrated in Figures 1-5. Accordingly, identical numerals have been used to designate those elements of the embodiment of Figure 6 which are identical to the same elements in the embodiment of Figures 1-5.
- the embodiment of Figure 7 differs from the embodiment of Figures 1-5 only in that a solid sleeve 191 is provided internally of the gun to block the ambient air flow passages 40 of the housing. Consequently, there is no need for a filter 190 surrounding those passages.
- the sleeve 191 has an internal bore 212 sized to fit over the lower end or discharge end 69 of the body 14a of the powder amplifier 14. This sleeve is secured to the lower end 69 of the body 14a by a conventional O-ring seal 214 contained within an annular groove of the body 14a.
- This same sleeve 191 has an external diameter which fits within the interior bore 124 of the pattern amplifier body 16a.
- the sleeve 191 is sealed relative to the internal bore 124 by a conventional O-ring seal 216 received within an annular groove of the body 16a of the suspension amplifier 16.
- the powder spray gun 10′ of Figure 7 is identical to the powder spray gun 10 of Figure 1.
- the operation of the powder spray gun of the modification of Figure 7 is quite different, however, from the operation of the powder spray gun of Figures 1-6.
- the solid sleeve 191 there is a pneumatic isolation between the pattern and suspension air amplifiers 16 and 14 provided by the air gap between the two.
- these amplifiers are fluidly locked together so that the pattern amplifier 16 becomes a secondary pump which pulls powder out of the hopper.
- a filter such as the filters 190 and 192, increases the consistency of the flow rate of the gun by reducing the effect of the ambient environment on powder flowing through the gap between the suspension and pattern amplifiers. It is believed that the filter provides for less turbulent air flow into the gap for mixture with the air-entrained powder.
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Abstract
A powder spray gun comprises a tubular housing (12) having ambient air flow passages (40) located in the sidewall thereof medially of the opposite ends. A pair of air flow amplifiers (14,16) are mounted in the housing (12) on opposite sides of the ambient air flow passages and are so oriented that compressed air supplied to the upstream one of these amplifiers, the so-called suspension amplifier (14), is operable to draw ambient air into the outlet end of the suspension amplifier, and compressed air supplied to the downstream amplifier, the so-called pattern amplifier (16), is operable to draw ambient air into the inlet end of the pattern amplifier. The spray gun (10) includes means (190) for preventing the egress of powder through the ambient air flow passages of the housing caused by back pressure generated by a restricted discharge orifice of a powder discharge nozzle of the gun.
Description
- This invention relates to the spraying of solid particulate materials, and more particularly, to improved apparatus for spraying solid particulate materials. This invention is an improvement upon the apparatus disclosed in U.S. Patent No. 4,600,603 entitled "Powder Spray Apparatus and Powder Spray Method" and in U.S. Application Serial No. 097,946 entitled "Powder Spray Gun", both of which are assigned to the assignee of this application.
- In the above identified patent, there is disclosed a powder spray gun which is characterised by sharp start-up and sharp cutoff of powder flow from the gun. The gun disclosed in that patent is also characterised by a relatively high velocity powder flow from the gun and an even distribution of powder throughout the pattern emitted from the gun. These are all characteristics which are highly desirable for many applications of powder spray equipment.
- The powder spray apparatus disclosed in the above identified patent comprises two series aligned air flow amplifiers, both of which are mounted upon supporting bodies. These bodies are in turn mounted in an adjustable manner upon a supporting rod. One of the air flow amplifiers is connected to a source of air-entrained powder, whilst the other, downstream from the first amplifier, is connected to a powder discharge nozzle. The spacing of the bodies, and thus the spacing between the air flow amplifiers, is adjustable so as to obtain optimal spray patterns and powder velocities from the apparatus in accordance with the needs or requirements for a particular powder spray application.
- The adjustability of the powder spray gun of the above identified patent is sacrificed in the powder spray gun of the above identified pending application in order to achieve a spray gun which is easier to assemble and disassemble, as for example, for cleaning of the apparatus, and easier to obtain repeatable flow patterns and velocities after disassembly and reassembly of the gun.
- The powder spray gun disclosed in this pending application comprises a housing having a generally tubular sidewall and an axial bore, which extends through the housing and is intersected by at least one ambient air flow passage extending through the sidewall of the housing. A first or so-called "pattern air flow" amplifier is mounted in one end of the housing on one side of the ambient air flow passage, and a second so-called "suspension air flow" amplifier is mounted in the opposite end of the tubular housing on an opposite side of the ambient air flow passage from the first air flow amplifier. Both amplifiers include means for directing a stream of compressed air into a powder flow passage of the amplifier so as to draw ambient air through the ambient air flow passage of the housing into the powder discharge opening of the powder flow passage of the first amplifier and into the powder inlet opening of the flow passage of the second amplifier.
- Quite commonly, powder spray guns employ flat fan spray nozzles or other restricted orifice discharge nozzles on the discharge end of the guns in order to achieve a desired spray patter. When spray guns of the type described in the above identified patent or pending application utilize such restricted orifice nozzles in the discharge end of the gun, through, the back pressure created by the restricted orifice of the nozzle causes powder to puff out of the ambient air flow passage between the two amplifiers of the gun. Such powder puffing from the ambient air flow passage of the gun is wasteful of powder, but more importantly, that powder enters and undesirably contaminates the atmosphere surrounding the gun.
- This invention aims to provide a dual air amplifier powder spray gun which is not subject to the puffing or emission of powder from the ambient air flow passage between the amplifiers of the gun when the gun is used to spray powder from a restricted orifice discharge nozzle.
- A solid particulate material spray gun in accordance with one aspect of the invention comprises a tubular housing, the bore of which is intersected by at least one ambient air flow passage extending through the sidewall of the housing, a first air flow amplifier mounted within the tubular housing on one side of the ambient air flow passage, the first amplifier having a solid particulate material flow passage extending axially therethrough and means for directing a stream of compressed air into the flow passage of the first amplifier, a second air flow amplifier mounted within the tubular housing on an opposite side of the ambient air flow passage from the first amplifier, the second amplifier having a solid particulate material flow passage extending axially therethrough and means for directing a stream of compressed air into the solid particulate material flow passage of the second amplifier, a discharge nozzle in fluid communication with the second amplifier, the nozzle having a restricted discharge orifice and means for preventing the egress of solid particulate material from the ambient air flow passage of the housing caused by back pressure generated from the restricted discharge orifice of the discharge nozzle.
- A filter of porous material may be placed around the ambient air flow passage of the gun so as to prevent the egress of powder through the passage while still permitting the free flow of air at ambient pressure through the porous filter. Polyfoam material or sintered metal may be used to form the filter, which, may be located on the exterior or interior of the housing and cover the ambient air passages.
- Alternatively, a solid sleeve may be placed between the two air amplifiers of the gun so as to completely block the egress of powder through the air passages as well as the ingress or egress of ambient air.
- In accordance with another aspect of the invention a solid particulate material spray gun having a discharge nozzle, the nozzle having a restricted discharge orifice, includes means for reducing the back pressure generated when air-entrained solid particulate material is sprayed from the restricted orifice of the nozzle. This means suitably comprises one or more vent holes provided in the nozzle adjacent to the restricted discharge orifice of the nozzle. The back pressure reducing means may be incorporated into any spray gun having a restricted discharge orifice and may be used with or without the egress prevention means of the first aspect of the invention.
- The invention will now be described further by way of example with reference to the accompanying drawings in which:
- Figure 1 is a cross-sectional view of a powder spray gun incorporating the invention.
- Figure 2 is a cross-sectional view taken on lines 2-2 of Figure 1.
- Figure 3 is a cross-sectional view taken on line 3-3 of Figure 1.
- Figure 4 is a cross-sectional view taken on line 4-4 of Figure 1.
- Figure 5 is a cross-sectional view taken on line 5-5 of Figure 1.
- Figure 6 is a cross-sectional view of a portion of the powder spray gun of Figure 1 but employing a modified filter in the gun.
- Figure 7 is a cross-sectional view of a second modification of a powder spray gun incorporating the invention.
- With reference first to Figures 1-5, there is illustrated a
powder spray gun 10 utilized in the practice of this invention. Thisgun 10 comprises a generally cylindrical,tubular housing 12 within which there are located a pair ofair flow amplifiers housing 12 andamplifiers bottom mounting caps - Each
air flow amplifier body 14a, 16a and a nozzle 14b, 16b. In the illustrated embodiment, the lowerair flow amplifier 16, the so-called "pattern" amplifier, is assembled by a bayonet-type pin 24 andslot 26connector 25. Theother amplifier 14, the so-called "suspension" amplifier, may be assembled by a bayonet-type pin and slot connection, but in the illustrated embodiment, it is assembled by means of a threadedconnection 28 between the two-pieces 14a, 14b of theamplifier 14. In the case of theupper amplifier 14, which is assembled by means of a threadedconnector 28, a lock-nut 30 is optionally threaded onto the nozzle assembly so as to lock the two-pieceair flow amplifier 14 in an assembled relationship. - Both the top and
bottom caps type pin 32 andslot 34connectors 33. With reference particularly to Figure 3, it will be seen that these connectors each comprise a pair of generally L-shaped slots 34 machined into the peripheral surface of thecaps pins 32 fixedly mounted in thehousing 12. These pin andslot connectors 33 enable the caps to be very quickly assembled onto the housing or very quickly disassembled therefrom. - That the complete gun, including the
housing 12, two two-piece air amplifiers bottom caps lock nut 30 is included in a threaded type amplifier. As is explained more fully hereinafter, this seven (or eight) piece assembly may very quickly be assembled and disassembled so as to facilitate cleaning of the gun. This assembly is also very compact and, as explained more fully hereinafter, requires no adjustment of the amplifiers or of any other component of the gun once it has been assembled. - The
housing 12 of the gun is configured as a cylindrical sleeve. This sleeve has threelarge apertures 40 machined from the sidewall thereof. As a consequence of these apertures, the upper section 42a of thesidewall 42 is separated from thelower section 42b by three equidistantly spaced, vertically extendingposts 42c (see Figure 4). - Located immediately above the
posts 42c of thehousing sidewall 42 there is aflange 44 which extends inwardly from the sidewall of the housing. This flange has anaxial bore 46 formed therein, which bore receives the lower end of thesuspension amplifier 14. Located immediately above theflange 44 there is a threadedport 48, which port receives a conventional threadedair fitting 47. The fitting is, in the use of thegun 10, connected to a source of compressed air (not shown). - Located immediately below the
posts 42c there is another internal flange which extends into the interior of the housing from thesidewall 42. This flange also has anaxial bore 52 for the reception of thepattern amplifier 16. - A threaded port 49, similar to
port 48, is located immediately below theflange 50 of the housing. This port extends through thesidewall 42 and receives a conventional compressed air fitting 53 through which compressed air is supplied to thegun 10. - Extending inwardly into the interior of the
tubular housing 12 adjacent the top and bottom ends thereof, there are a pair ofpins 32 of the bayonet-type pin andslot connectors 33. Thesepins 32 are preferably press fitted intoholes 32a machined into theside walls 42 of the housing. As mentioned hereinabove, these pins are adapted to be received withinslots 34 machined into the top andbottom caps - The
suspension amplifier 14 comprises abody 14a and a nozzle 14b. The two pieces, thenozzle 14a and body 14b, are both generally tubular in configuration and are retained in an assembled relationship with the nozzle contained internally of the body by the threadedconnection 28. This connection comprisesexternal threads 28a on the periphery of the nozzle 24b andinternal threads 28b on the interior of thebody 14a. - The
body 14a has anaxial bore 66 extending therethrough. This bore is of larger diameter at the upper end and smaller diameter at the lower end. Between the two different diameter sections there is ashoulder 68. Additionally, there is an annular channel 70 around the interior of thebore 66 adjacent to the intersection of the threaded and unthreaded sections of the upper large diameter portion of the bore. Between the annular channel 70 and theshoulder 68 there is aradial hole 72 through which compressed air may pass from the exterior to the interior of thebody 14a. - The lower end of the
body 14a is slidably received within thebore 46 of thehousing 12. An O-ring 74 located within an annular groove in the periphery of the body forms a seal between thebody 14a and thebore 46. - From the
shoulder 68 in the body to the lower end, thebore 66 tapers inwardly and downwardly. This taper functions to focus air-entrained powder passing through theamplifier 14 into the open upper end of the lower patternair flow amplifier 16. - The nozzle 14b of the
suspension amplifier 14 is provided with aperipheral flange 80 upon which thethreads 28a are formed. Below thisflange 80 there is a section of reduceddiameter 81 separated from the threadedsection 80 by ashoulder 82. The reduceddiameter section 81 terminates in an outwardly flared lower end 84 of the nozzle which abuts theshoulder 68 of thebody 14a. - As may be seen most clearly in Figure 1 and 2, the
shoulder 68 of the body forms a seat for the lower flared end 84 of the nozzle 14b. To facilitate air flow, as indicated by thearrow 86, over this seat, there arerecesses 88 machined from theshoulder 68. As a result of these recesses being machined or formed inshoulder 68, the shoulder comprises three raised sections orribs 90 against which the lower end 84 of the nozzle 14b abuts, with therecesses 88 being located between the ribs. To facilitate assembly and disassembly of the suspension amplifier, it preferably hasflats 91 formed or machined on the upper end of the nozzle 14b. - The lower or
pattern amplifier 16 comprises the nozzle 16a and body 16b. Both the body 16a and nozzle 16b are generally cylindrical in configuration. The nozzle of theamplifier 16 is secured to the body by a bayonet-style pin andslot connection 25 substantially identical to the pin and slot connectors 33 (Figure 3) which connect the top and bottom caps to the housing. Thisconnection 25 comprises apin 24 which is received within a generally L-shapedslot 26 of the nozzle so as to secure the two pieces in an assembled relation. An O-ring 122 contained within an annular groove of the nozzle seals the periphery of the nozzle relative to the interior bore 124 of the body 16a. - The body 16a has a smaller diameter
upper end section 128 which is received within thebore 52 of thehousing 12. The exterior surface of this section of the body is sealed relative to thebore 52 by an O-ring mounted within an annular groove in the surface of theupper end section 128 of the body. The lowerlarger diameter section 132 of the body is received within the bore of the housing, but is spaced from the interior surface thereof so as to define anannular channel 134 therebetween. Thischannel 134 functions as an air flow passage, as explained more fully hereinafter, for the flow of compressed air to theair flow amplifier 16. Theannular channel 134 communicates with aninterior channel 136 on the inside of the body by means of ahole 138 in the sidewall of the housing. - Between the large diameter
lower end section 140 of thebore 124 and the smaller diameterupper end section 144 of that bore there is ashoulder 146. The upper end of the nozzle 16b rests against this shoulder. - The nozzle 16b is also tubular in configuration and has an
axial bore 147 extending therethrough. At its upper end, the sidewall of the nozzle is flared outwardly, as indicated at 150. The upper end of this flared end wall rests against theshoulder 146 of the body. In order for air to flow from theannular channel 136 around the flaredend 150 of the nozzle, as indicated by thearrow 162, there arerecesses 164 machined from the surface of theshoulder 146. These recesses are identical in configuration to therecesses 88 in theshoulder 68 of theupper suspension amplifier 14. These recesses defineridges 166 therebetween against which the upper end of the nozzle abuts. Consequently, compressed air is free to flow from thechannel 136 through therecesses 164 machined from theshoulder 146 and into the interior of the nozzle. - As in the case of the suspension amplifier, the
pattern amplifier 16 preferably hasflats 148 machined or formed on the lower end of the nozzle 16b to facilitate assembly or disassembly of the nozzle by engagement of the flats with a wrench. - The
top cap 18 functions to retain thesuspension amplifier 14 assembled within thehousing 12. To that end, the generally tubular-shaped top cap has anaxial bore 100 extending therethrough. This bore has a small diameterupper end section 102, a larger diameterintermediate section 104, and a large diameterlower end section 106. The small diameterupper end section 102 of the cap is adapted to be placed in fluid communication with a source of air-entrained powder. Theintermediate diameter section 104 fits over the upper end of the nozzle 14b of theamplifier 14 and is sealed relative thereto by an O-ring seal 108 located within an annular channel in the periphery of the nozzle. Thelarge diameter section 106 of the bore of the cap is received over the upper end of thebody 14a of theamplifier 14. The lower end of thetop cap 18 has a pair of generally L-shaped bayonet slots 34 (See Fig. 3), which receive thepins 32 in the upper end of thehousing 12. When the top cap is mounted onto the top of the housing and rotated relative thereto, thepin 32 slides in theslot 34 and functions to clamp the top cap to the top end of the housing. - The lower or
pattern amplifier 16 is retained within thehousing 12 by thebottom cap 20. This cap is also tubular in configuration and has anaxial bore 112 extending therethrough. The lower small diameter end section of this bore is adapted to be placed in fluid communication with a powder spray nozzle (not shown). The upper large diameter end section of thisbore 112 is received over the lower end of the amplifier nozzle 16b and is sealed relative thereto by the O-ring 114. Another O-ring 116 mounted in an annular groove in the periphery of thebottom cap 20 seals the exterior of the bottom cap relative to the interior of thehousing 12. This lower O-ring seal 116 cooperates with the pin andslot connector 33 to retain the bottom cap in an assembled relation on the housing with thebottom amplifier 16 contained interiorly thereof. - The
powder spray gun 10 is assembled by first assembling thesuspension amplifier 14. This is accomplished by threading the nozzle 14b of theamplifier 14 into thebody 14a until the end surface of the flared end 84 of the nozzle engages the top surface of theridges 90 on theshoulder 68. With the nozzle and body so assembled, thelocknut 30 is threaded onto the upper end of the nozzle until the bottom surface of the locknut engages the top surface of thebody 14a. An O-ring 35 contained within an annular groove of the nozzle then forms an air seal between the nozzle 14b andbody 14a. With thetop cap 18 removed from thehousing 12, the assembledsuspension nozzle 14 is then dropped into the housing. The lower end, or so-called "nozzle" end of the body, then slides through theaxial bore 46 of the housing until a shoulder-defined between the lower end of thebody 14a and the upper end contacts the top surface of theflange 44. The O-ring 74 then forms an air seal between thebody 14a and theflange 44 of the housing. Thetop cap 18 of the gun is then placed over the top of the housing and over the top of theamplifier 14. Thebayonet slots 34 of the top cap then slip over thepins 32 such that when the top cap is then rotated, the top cap clamps theamplifier 14 on the interior of the housing. The O-ring seal 110 then cooperates with the bayonet pin andslot connector 33 so as to fixedly secure the top cap to the top of the housing. The O-ring seal 108 then forms a seal between the nozzle of the amplifier and the bore of the top cap. - The lower or
pattern amplifier 16 is next assembled by placing the nozzle 16b within the body 16a. The nozzle and body are then secured together by locating thepin 24 within theslot 26 of the nozzle and rotating the nozzle relative to the body. Thisbayonet slot connection 25 then secures the nozzle within the body with the O-ring seal 122 then forming a seal between the nozzle and body. When the nozzle and body are secured together by the pin and bayonet slot connection, the upper end of thenozzle 166 rests against the bottom surface of the ridges orribs 166 of theshoulder 146. - The
pattern amplifier 16 is then inserted into thehousing 12 with the upper end of the body 16a of the amplifier received within thebore 52 of the housing. The O-ring seal 130 then forms an air seal between thebore 52 of the housing and the upper end of the body 16a. Theamplifier 16 is then secured within the housing by placement of thebottom cap 20 over the lower end of the nozzle of theamplifier 16. Theslots 34 of thebottom cap 20 are then inserted over thepins 32 and the bottom cap rotated so as to secure the bottom cap to the lower end of the housing with the O-ring seal 116 compressed therebetween. The O-ring 114 then forms a seal between the exterior of the amplifier and the interior bore of the bottom cap. - The power spray gun described hereinabove is identical to the spray gun described in the above identified U.S. Application Serial No. 097,946 and per se, forms no part of the invention of this application.
- The
powder spray gun 10 of this application differs from the powder spray gun of the above-identified application in that it includes means for preventing the egress of solid particulate powder through the ambient air flow passages of the gun. In one embodiment, shown in Figure 1, afilter 190 surrounds the ambientair flow passages 40 and is of a porosity which will prevent the egress of powder from thepassages 40 while still permitting the free flow of air at ambient air pressure. - A
powder spray nozzle 200 is secured over the bottomtubular end section 112 of the bottom cap. The nozzle is preferably secured to the lower end of the bottom cap by O-rings - A plurality of equidistantly spaced, radial vent holes or
ports 210 are provided in the sidewall of thenozzle 200. These vent holes extend between the exterior of the nozzle and theinternal passage 208. The function of the nozzle vent holes 210 is to relieve back pressure created by the restrictedorifice 202 of thenozzle 200, which back pressure, in the absence of the vent holes 210 and thefilter 190, tends to push powder out the ambientair flow passages 40 of thehousing 12. - In the use of the
spray gun 10, compressed air is supplied to theair fittings housing 12. Compressed air supplied to the fitting 47 passes through an annular channel contained interiorly of thehousing 12, through thebore 72, into the channel 70 located internally of theamplifier 14. From this channel, the compressed air passes through therecesses 88 defined between the bottom surface of the end of the nozzle and the top surface of the shoulder of the nozzle body. This compressed air, then, is directed in a generally upward direction when it emerges from therecesses 88. Because it is so directed, it creates a vacuum in the lower end of thenozzle body 14a which tends to draw ambient air from the exterior of the housing, through theapertures 40, into the interior of the housing and into the lower end of theamplifier 14. - Compressed air, at a pressure usually substantially greater than that supplied to the fitting 47 and threaded
port 48, is also supplied to the fitting 53 and port 49. This compressed air passes through theannular channel 134 defined between the interior of the housing and the exterior of the amplifier body 16a, through theaperture 138 in the amplifier body, and into theannular channel 136. From thischannel 136 the air passes upwardly around the upper flared end of the nozzle through therecesses 164 and downwardly into the axial centre bore of the nozzle. This high pressure air draws ambient air through thepassage 40 of the housing downwardly into the open upper end of theamplifier 16. - While compressed air is supplied to the threaded
air inlet ports 48 and 49, air-entrained powder is supplied to theinlet port 182 of thetop cap 18. The air-entrained powder flows downwardly through thesuspension amplifier 14. Within this suspension amplifier, the air-entrained powder is subjected to turbulence created by the upwardly directed compressed airstream flowing through therecesses 88 of the amplifier. This air-entrained powder passes through the suspension amplifier and is focused and directed by the lower discharge nozzle end 69 of theamplifier body 14a of the suspension amplifier into the open upper end of thelower pattern amplifier 16. In the course of passage through the pattern amplifier, the velocity of the powder is increased by the high velocity, downwardly directed airstream emitted through therecesses 164 of the pattern amplifier. This high velocity airstream causes a vacuum at the inlet to thepattern amplifier 16 which pulls air into the amplifier from the surroundings through thepassages 40 of the housing. Simultaneously, the high velocity air flow through the lower pattern amplifier draws air-entrained powder from theupper suspension amplifier 14. In the course of passage through the pattern amplifier, the velocity of the powder is markedly increased. The high velocity powder is then caused to flow from the gun through thenozzle 200 via thedischarge passage 112 in thebottom cap 20. - When the flow of air-entrained powder to the
inlet port 182 is terminated, air flow to the suspension amplifier via the highpressure inlet port 48 is maintained. By maintaining air flow to the upper suspension amplifier, any powder contained in the lines above the discharge end of the suspension amplifier is either maintained in the lines or purged from the lines back into the powder source or supply. As a result, powder flow does not continue to trickle from the gun or to blow out of the ambientair flow passages 40 of the gun. Instead, powder flow is sharply cut off when powder flow to theinlet 182 of the gun is terminated. When powder flow is again initiated to theinlet port 182 of the gun, powder flow is sharply initiated as a consequence of the air flow being maintained to both the suspension amplifier and thepattern amplifier 16. - It has been found that when the
gun 10 is utilized to spray powder from a nozzle having a restricted discharge orifice, such as theorifice 202 ofnozzle 200, there is a back pressure created in thepowder flow passage 112 of the gun. This back pressure tends to force powder to puff and flow from the ambientair flow passages 40 of the housing. To alleviate that problem and to prevent powder from flowing out of thepassages 40 of the housing, thefilter 190 is provided. This filter is preferably a sintered bronze filter in the form of a sleeve which surrounds the housing and covers thepassages 40 so as to prevent the egress of powder from the housing through thepassages 40, which would otherwise occur because of this back pressure. The porosity of thefilter 190 is selected so that it will prevent the egress of air-entrained powder but will still permit the free flow of air at ambient pressure through the filter. - With reference now to Figure 6, there is illustrated a central portion of the powder spray gun of Figure 1, but with a modified
filter 192 replacing the sintered metal filter of the gun of Figure 1. Thefilter 192 comprises an annular filter made from polyfoam material, which filter fits over thelower end 69 of thenozzle body 14a and extends between that lower end of the nozzle body and theposts 42c. In the preferred embodiment, the polyfoam filter is made from a polyester foam material having 35 pores per linear inch. Except for the difference in filter materials and filter configuration, the powder spray gun of Figure 6 is identical to the powder spray guns of Figures 1-5. - As an alternative to the use of the
polyfoam filter 192 on the interior of the gun, as illustrated in Figure 6, a polyfoam filter may be located on the exterior of the gun, as illustrated in Figure 1. In that event, the polyfoam filter would be substituted for thesintered metal filter 190 of Figure 1. Yet another alternative to the use of a polyfoam filter on the interior of the gun, as illustrated in Figure 6, is to substitute a sintered metal filter on the interior of the gun for thepolyfoam filter 192 illustrated in Figure 6. - With reference now to Figure 7, there is illustrated a second embodiment of the invention of this application. This embodiment incorporates a
spray gun 10′ substantially identical to thespray gun 10 of the modification illustrated in Figures 1-5. Accordingly, identical numerals have been used to designate those elements of the embodiment of Figure 6 which are identical to the same elements in the embodiment of Figures 1-5. - The embodiment of Figure 7 differs from the embodiment of Figures 1-5 only in that a
solid sleeve 191 is provided internally of the gun to block the ambientair flow passages 40 of the housing. Consequently, there is no need for afilter 190 surrounding those passages. In accordance with this embodiment, thesleeve 191 has aninternal bore 212 sized to fit over the lower end or dischargeend 69 of thebody 14a of thepowder amplifier 14. This sleeve is secured to thelower end 69 of thebody 14a by a conventional O-ring seal 214 contained within an annular groove of thebody 14a. Thissame sleeve 191 has an external diameter which fits within the interior bore 124 of the pattern amplifier body 16a. Thesleeve 191 is sealed relative to theinternal bore 124 by a conventional O-ring seal 216 received within an annular groove of the body 16a of thesuspension amplifier 16. - Except for the provision of the
solid sleeve 191 mounted internally of the gun and the absence of thefilter 190, thepowder spray gun 10′ of Figure 7 is identical to thepowder spray gun 10 of Figure 1. The operation of the powder spray gun of the modification of Figure 7 is quite different, however, from the operation of the powder spray gun of Figures 1-6. Without thesolid sleeve 191 there is a pneumatic isolation between the pattern andsuspension air amplifiers solid sleeve 191, these amplifiers are fluidly locked together so that thepattern amplifier 16 becomes a secondary pump which pulls powder out of the hopper. With thesolid sleeve 191 in place, an increase in the air pressure to the pattern amplifier increases the flow of powder through the gun until the air pressure becomes excessive and causes a decrease in powder flow due to a back pressure condition caused by the excessive air pressure and the flow limitations of the gun. Without the solid sleeve in place, the amount of powder flowing through the gun does not increase when the air pressure of the pattern air amplifier is increased. - It is also worth noting that the use of a filter, such as the
filters
Claims (10)
1. A solid particulate material spray gun comprising a tubular housing, the bore of which is intersected by at least one ambient air flow passage extending through the sidewall of the housing, a first air flow amplifier mounted within the tubular housing on one side of the ambient air flow passage, the first amplifier having a solid particulate material flow passage extending axially therethrough, and means for directing a stream of compressed air into the flow passage of the first amplifier, a second air flow amplifier mounted within the tubular housing on an opposite side of the ambient air flow passage from the first amplifier, the second amplifier having a solid particulate material flow passage extending axially therethrough and means for directing a stream of compressed air into the solid particulate material flow passage of the second amplifier, a discharge nozzle in fluid communication with the second amplifier, the nozzle having a restricted discharge orifice, characterised in that means (190, 191, 192) are provided for preventing the egress of solid particulate material from the ambient air flow passage (40) of the housing (12) caused by back pressure generated from the restricted discharge orifice (202) of the discharge nozzle (200).
2. A solid particulate material spray gun as claimed in Claim 1 characterised in that the solid particulate material egress prevention means comprises a porous filter (190,192).
3. A solid particulate material spray gun as claimed in claim 2 characterised in that the filter (190, 192) is sized so as to prevent the egress of solid particulate material sprayed from the gun but operable to permit the free flow therethrough of air at ambient
4. A solid particulate material spray gun as claimed in any of claims 1, 2 or 3 characterised in that the egress prevention means comprises a porous filter surrounding the ambient air flow passage (40).
5. A solid particulate material spray gun as claimed in claim 1 characterised in that the solid particulate material egress prevention means comprises a solid sleeve (191).
6. A solid particulate material spray gun as claimed in claim 5 characterised in that the solid sleeve (191) is contained internally of the housing (12), between the two air amplifiers (14, 16).
7. A solid particulate material spray gun as claimed in any preceding claim characterised in that the solid particulate material egress prevention means include at least one vent hole (210) located adjacent to the restricted discharge orifice (202) of the discharge nozzle (200).
8. A solid particulate material spray gun as claimed in claim 7 characterised in that a plurality of vent holes (210) are located adjacent to the restricted discharge orifice of said discharge nozzle.
9. A solid particulate material spray gun as claimed in claim 8 characterised in that the plurality of vent holes (210) are located within the discharge nozzle (200).
10. A spray gun for spraying air-entrained solid particulate material having a discharge nozzle mounted upon the discharge end of the spray gun, the nozzle having a restricted discharge orifice, characterised in that means are provided for reducing the back pressure generated when air-entrained solid particulate material is sprayed from the restricted discharge orifice of the nozzle, the back pressure reducing means comprising at least one vent hole (210) in the nozzle (200) located adjacent to the discharge orifice (202).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US26081188A | 1988-10-20 | 1988-10-20 | |
US260811 | 1988-10-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0365225A2 true EP0365225A2 (en) | 1990-04-25 |
EP0365225A3 EP0365225A3 (en) | 1990-11-14 |
Family
ID=22990717
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890310506 Withdrawn EP0365225A3 (en) | 1988-10-20 | 1989-10-13 | Powder or solid particulate material spray gun |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0365225A3 (en) |
JP (1) | JPH02164471A (en) |
AU (1) | AU4141889A (en) |
BR (1) | BR8905309A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0599498A1 (en) * | 1992-11-23 | 1994-06-01 | Nordson Corporation | Powder spray nozzle |
EP0718043A1 (en) * | 1994-12-24 | 1996-06-26 | ITW Gema AG | Powder coating installation |
EP2144704B1 (en) * | 2007-05-09 | 2015-11-04 | Nordson Corporation | Nozzle with internal filter |
US11534777B2 (en) | 2016-03-21 | 2022-12-27 | Exel Industries | Coating sprayer, method for assembling and disassembling |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4873937A (en) * | 1988-01-28 | 1989-10-17 | Nordson Corporation | Method and apparatus for spraying powder into a continuous tow |
GB8919767D0 (en) * | 1989-09-01 | 1989-10-18 | Univ Manchester | A device for producing a particulate dispersion |
EP3551338B1 (en) * | 2016-12-06 | 2022-11-09 | 3M Innovative Properties Company | Spray gun air cap with retention means |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0125153A2 (en) * | 1983-03-14 | 1984-11-14 | Saint Gobain Vitrage International | Method and apparatus for evenly applying a powder coating to a substrate, and substrate thus coated |
US4600603A (en) * | 1984-06-21 | 1986-07-15 | Nordson Corporation | Powder spray apparatus and powder spray method |
WO1989002317A1 (en) * | 1987-09-17 | 1989-03-23 | Nordson Corporation | Powder spray gun |
-
1989
- 1989-09-13 AU AU41418/89A patent/AU4141889A/en not_active Abandoned
- 1989-10-13 EP EP19890310506 patent/EP0365225A3/en not_active Withdrawn
- 1989-10-18 BR BR8905309A patent/BR8905309A/en unknown
- 1989-10-19 JP JP27049389A patent/JPH02164471A/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0125153A2 (en) * | 1983-03-14 | 1984-11-14 | Saint Gobain Vitrage International | Method and apparatus for evenly applying a powder coating to a substrate, and substrate thus coated |
US4600603A (en) * | 1984-06-21 | 1986-07-15 | Nordson Corporation | Powder spray apparatus and powder spray method |
WO1989002317A1 (en) * | 1987-09-17 | 1989-03-23 | Nordson Corporation | Powder spray gun |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0599498A1 (en) * | 1992-11-23 | 1994-06-01 | Nordson Corporation | Powder spray nozzle |
US5368237A (en) * | 1992-11-23 | 1994-11-29 | Nordson Corporation | Power coating guns with improved spray nozzles and improved method of power coating |
EP0718043A1 (en) * | 1994-12-24 | 1996-06-26 | ITW Gema AG | Powder coating installation |
US5704957A (en) * | 1994-12-24 | 1998-01-06 | Gema Volstatic Ag | Powder coating system |
EP2144704B1 (en) * | 2007-05-09 | 2015-11-04 | Nordson Corporation | Nozzle with internal filter |
EP2279797B1 (en) | 2007-05-09 | 2016-01-13 | Nordson Corporation | Nozzle with internal filter |
US11534777B2 (en) | 2016-03-21 | 2022-12-27 | Exel Industries | Coating sprayer, method for assembling and disassembling |
Also Published As
Publication number | Publication date |
---|---|
AU4141889A (en) | 1990-04-26 |
BR8905309A (en) | 1990-05-22 |
JPH02164471A (en) | 1990-06-25 |
EP0365225A3 (en) | 1990-11-14 |
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