DE60106617T2 - UNIPOLAR POWDER COATING SYSTEMS WITH IMPROVED FRICTION CHARGING AND CORONAPISTOLS - Google Patents

Description

field of use the invention

These The invention relates to powder coating systems, corona and triboelectric use charging powder spray guns to order powder to electrostatically charge on a substrate.

background the invention

It There are two basic types of powder spray guns commonly used for electrostatic powder spray coating of products used become. The most common Type of spray gun is the corona type, which is a high voltage charging electrode which generates a corona to charge the powder. typically, Corona guns are designed to make the powder negative charge. A major disadvantage of coronary guns is that they due to the strong electrostatic field generated by the corona electrode or Faraday cage effect Do not coat the inside corners of the parts well. A second disadvantage of corona pistols is that as a result of education free Ions a reionization can occur on the part to be coated to gas pores or an orange peel surface leads to the part to be coated. Another disadvantage of this type of pistols is that the system components, such as the nozzle and the diffuser, as well as the powder delivery system components, such as the pump, the reservoir and other parts in contact with the powder delivery system usually made of materials such as polyethylene or polytetrafluoroethylene (PTFE) are made. While These materials have the advantage of low impact fusion have the disadvantage of positive charging of the powder, which may affect the negative coronal charge process because of the final or maximum charge of the powder is reduced. Furthermore is often a greater tension required to counteract the positive charge of the system. Furthermore This positive triboelectric charging can cause the failure of the powder delivery components cause, like the hose, the pump with the spray gun combines.

One second type of pistol, which is also commonly used, is one triboelectrically charging gun, in which the powder by friction contact with the inner surfaces the gun is charged. An advantage of triboelectric guns is that the powder easily in corners of to be coated Parts can penetrate, because the gun no strong electric Field generated like a corona discharge pistol.

Summary of the present invention

The Invention Provides New Electrostatic Powder Coating Guns and system components available, in which powder is charged in advance to the same polarity as one Charging by the powder spray gun, the charging and the transfer efficiency to increase and to improve. There will also be new powder coating processes described.

The EP-A-0 627 265 discloses a spray gun for electrostatic Paint application using friction charging, comprising a Gun body, which at one end has a paint inlet around the other end a paint outlet owns, as well as a charging section, which at least one not conductive resin tube and a precharging portion, the provided between the paint inlet and the charging section is, and a non-conductive Contains resin ring, wherein the precharge section further comprises a flow element in which a number of holes is formed, which extend outwards and forwards to that fed through the paint inlet Color powder in a turbulent and finely distributed flow on the inner wall surface to direct the non-conductive ring.

According to one Aspect of the invention is an apparatus for powder spray coating material provided a powder flow path has, wherein the powder flow path a charging area for triboelectric charging of the powder coating material that comes in contact with the charging surface, characterized that the device comprises a Luftströ flow path, the like the charging area extends and is spaced therefrom, wherein the air flow path is bounded by a wall, one or more through the wall through trained air channels owns, with the air channels in fluid communication stand with a compressed air source.

The charging surface may comprise a negative triboelectrically charging material, that of polyamide resin blends, fiber-reinforced polyamides, aminoplast resins and acetal polymers is.

In one embodiment, the powder flow path has a first charging surface for triboelek wherein the first charging surface comprises a tribocharging material having a first charging polarity, the device further comprising a component through which powder coating material also flows, the component having a second charging surface which also has a tribocharging material with the first charging polarity.

In a further embodiment the device has an electrode for charging the powder coating material on a first charge polarity and the charging area comprises a triboelectrically charging material, which is the first charging polarity has.

The Device can be a body comprising an inner bore, a disposed in the inner bore Abriebrohr and one between the inner bore and the Abriebrohr provided open channel, wherein at least through the attrition tube an air jet channel is provided. The air jet channel provides a flow connection between the open channel and the interior of the Abriebrohres Available. The Abriebrohr has the charging surface for triboelectric charging of the powder coating material coming into contact with the charging surface. The open channel is in fluid communication with a compressed air source, with compressed air from the open channel through the air jet channel flows into the interior of the Abriebrohres to the To influence the flow of the powder coating material through the Abriebrohr.

These and other aspects of the invention will become apparent below to the attached drawings in detail described.

figure description

1 Figure 11 is a sectional view of a tribocharging gun incorporating the novel unconventional materials of the invention;

2 Fig. 10 is a sectional view of a novel short-stroke tribocharging gun of the present invention;

3A to 3D show part of the use of the pistol 2 in which the air nozzles are arranged in different opposing configurations;

4A shows a sectional view of the insert of the short-stroke tribocharging gun 2 seen from the back to the front, where the air nozzles are not vertically offset from each other;

4B to 4E show sectional views of the use of the short-stroke triboelectrically charging gun 2 seen from the rear to the front, in which the air nozzles at a vertical distance H are vertically offset from each other;

5A and 5B each show a sectional view of the insert of the short-stroke tribocharging gun 2 seen from the back to the front, where a first set of air jets, as in 5A not shown by a second set of downstream air jets as shown in FIG 5B shown are circumferentially offset;

5E to 5F each show a sectional view of the insert of the short-stroke tribocharging gun 2 Seen from behind to the front, where a first set of air jets, as in the 5C and 5E shown alternately from a second set of downstream air nozzles, as in FIGS 5D respectively. 5F shown is offset;

5G and 5H each show a sectional view of the insert of the short-stroke tribocharging gun 2 seen from the back to the front, where a first set of air jets, as in 5G shown by a single downstream air nozzle, as in 5H shown, not offset alternately;

6 shows a sectional view of a corona gun incorporating the new unconventional materials of the invention;

7 Figure 10 is a sectional view of a flat spray nozzle incorporating the new unconventional materials and one or more air jets of the invention;

8th Figure 11 is a sectional view of a powder pump of a powder coating system incorporating the novel unconventional materials of the invention.

9 shows a perspective schematic view of a powder coating system comprising a corona and triboelectrically charging gun with charging of the powder to the same polarity;

10 Fig. 10 is a sectional view of an alternative embodiment of a tribocharging gun according to the invention containing air nozzles;

10A is a sectional view of the in 10 shown gun in the direction of 10A-10A;

11 Fig. 12 is a sectional view of yet another alternative embodiment of a tribocharging gun according to the invention containing air nozzles arranged in a spiral pattern;

11A is a sectional view of the in 11 shown gun in the direction of 11A-11A;

12 Fig. 10 is a sectional view of another embodiment of a tribocharging gun using air nozzles;

13 is a sectional view of a modified version of the pistol in 12 having a section with air nozzles and a triboelectric recharge section;

14 is another sectional view of a modified version of the pistol in 12 having a precharge section with air nozzles followed by a tribocharging section;

15 and 16 are sectional views of two embodiments of an inside-out gun according to the invention;

17 shows an embodiment of an air jet induced gun in a conventional manual spray gun configuration;

18A - 18D show additional embodiments of the gun type 17 using different extension lengths;

19 shows an inside-out pistol in a manual pistol configuration;

20 shows a spray gun containing an inside-out configuration with an outside-in configuration;

21 - 24 show a further embodiment of the invention.

Full Description of preferred and alternative embodiments

The subsequent detailed Description of preferred and alternative embodiments is divided into the following sections. Section I gives one detailed description of a new triboelectrically charging Pistol containing a powder by friction contact with new use charging conventional materials, as detailed below is described. Section II gives a detailed description a new short-lived, triboelectrically charging gun, which depends on the frictional contact with The materials selected for the triboelectrically charging surfaces of the gun Powder can charge to a positive or negative polarity. The sections III and IV relate to a corona gun or a powder feed system, the corona gun and the system comprising components which the powder by frictional contact of the powder with triboelectric charging surfaces, which from the desired formed positive or negative triboelectrically charging material become the same polarity how to charge the corona pistol. Section V gives a detailed Description of a powder coating system, the corona and triboelectric includes charging pistols that charge the powder to the same polarity so that the triboelectrically charging gun in conjunction with The corona gun can be used to coat the same workpiece. Section VI finally gives a detailed description of an alternative embodiment the triboelectric charging gun that uses air nozzles.

I. From unconventional Materials constructed, negative triboelectrically charging gun

A. Unconventional, negative Charging triboelectric materials

One Part of this invention is the discovery of what follows herein as "unconventional, negatively charging triboelectric materials. "These materials are considered as powder contact surfaces for negative Charging powder coating material by frictional contact with the powder contact surfaces a powder spray gun suitable. The term "negatively charging triboelectric Materials "means Materials that contribute to the powder, such as powder paints Frictional contact with the surface Negative triboelectrically charging materials have a negative Lends load.

As in this application in more detail could be described the unconventional, negatively charged triboelectric materials as interior surfaces of triboelectrically charging or corona powder spray guns used as spray gun components and powder delivery system components, such as the diffuser, the powder tube, the feed container and the pump, as more detailed described in section IV. Although the unconventional, negative Charging triboelectric materials are basically known, they are so far for Use in spray guns for triboelectric charging of Powder coating materials not known.

The unconventional negative-charging triboelectric materials are from the group of polyamide blends, fiber-reinforced polyamide resins, Aminoplast resins, acetal polymers or a mixture thereof and selected are more detailed below described. These materials not only charge well, but also are not as much subject to impact fusion problems like negative triboelectrically charging materials used in the past used, such as nylon.

1. The polyamide mixture

The Polyamide blend consists of a blend of a polyamide polymer and a second polymer selected from the group consisting of: polyethylene, Polypropylene, halogenated hydrocarbon resins and mixtures selected from it is. The polyamide polymer is preferably in a ratio of 50 to 96% by weight, and especially between 70 and 90% by weight in the polyamide mixture. The second polymer is preferably from approximately 4 to about 50% by weight, more preferably about 10 to about 30% by weight, and most preferably from about 15 to approximately 25% by weight is present in the polyamide mixture.

The halohydrocarbon resin is preferably a fluorinated hydrocarbon resin, such as polytetrafluoroethylene (also known as PTFE); a copolymer of tetrafluoroethylene and hexafluoropropylene (also known as FEP); and a copolymer of tetrafluoroethylene and perfluorinated vinyl ether (also known as PFA). Suitable fluorinated resins are commercially available under the trade name TEFLON ^® from DuPont.

The Polyamide polymer in the polyamide blend is preferably a nylon. Preferred grades of nylon are nylon 6/6, nylon 6/12, nylon 4/6 and nylon 11. A suitable polyamide blend is 20% Polytetrafluoroethylene and 80% nylon 6/6, under the trade name Lubricon RL 4040 from LNP Engineering Plastics, Division of ICI Advanced Materials, Exton, Pennsylvania, is commercially available. A suitable Mixture is about 5% polytetrafluoroethylene and about 95% nylon 6/6, which are listed under the trade name Lubricon RL 4010 from LNP Engineering Plastics, Division of ICI Advanced Materials, Exton, Pennsylvania, commercial available is.

example 1

It were individual discs of a polyamide / halohydrocarbon resin mixture made of 20% polytetrafluoroethylene and 80% nylon 6/6. To the Comparison were specimens made of conventional material, this means Nylon and Teflon, made.

By spraying of a powder paint from a flat spray nozzle having a slit of 0.45 inches by 0.65 inches (1.143 cm times 0.165 cm) with an air flow rate of 4 cubic feet per minute (1887.8 cm ³ / second) on a disc in a 45 ° angle, the relative transfer efficiency was determined. The powder hit the disk of triboelectrically charging material and was deflected from the disk to a grounded metal target. The powder leaving the nozzle had a measured initial temperature zero. Thus, the total powder charge was due to the impact on the triboelectric material. The amount of powder remaining adhered to the target object in comparison with the total sprayed powder is defined as a relative transfer efficiency. Normally, 50 grams of polyester epoxyd powder from Ferro Corporation was the powder used for the experiments. Since this attempt at relative transfer efficiency was made by a single rebound from a specimen, the values will likely be lower than with multiple contacts using a tribocharging gun.

The for the Evaluation powder used was a polyester epoxy powder with the Designation 153W-121 from Ferro Corporation. The results are shown in Table I below.

Example 2

Separate Discs of a polyamide blend of 5% PTFE and 95% Nylon 6/6 were prepared and the transfer efficiency evaluated as in Example 1. The results are below in Table I shown.

Of the Advantage of using the polyamide blends in powder spray guns is that they charge the powder as a result of increased discharge increase the triboelectrically charged pistol areas. The larger surface discharge is on the incompatible Attributed to polymers a creepage distance available which is not present in the homogeneous polymer. Another Advantage of using these polyamide blends is that it has a reduced moisture absorption of the nylon takes place when it filled with PTFE or polyethylene is.

2. The fiber reinforced polyamide resin

The fiber reinforced Polyamide resin consists of a polymer filled with polyaramid fibers. Preferably the polyamide polymer approximately 50% to 99%, more preferably about 85% to about 95%. Preferably the polyaramid fiber in the polyamide polymer is about 1% to about 50%, and more preferably about 5% to about 15%.

The Polyamide polymer in the fiber-reinforced polyamide resin is preferable commercially available Polyamide polymer. Suitable polyamides are, for example, nylons.

The polyaramid fibers are long-chain synthetic aromatic polyamides in which at least 85% of the amide compounds are directly linked to two aromatic rings. A suitable polyaramid is poly (p-phenylene terephthalamide) which is commercially available under the trade name KEVLAR ^® from DuPont. The polyaramid fiber, poly (m-phenylene terephthalamide), which is commercially available under the tradename Nomex from DuPont, is less preferred. Examples of other polyaramid fibers are a polymer having polymer units of P-aminobenzydrazide and terephthaloyl chloride; a suitable such polymer is commercially available under the tradename PABH-T X-500 from Monsanto.

A suitable fiber-reinforced polyamide resin consists of 10% KEVLAR ^® and 90% nylon 6,6, which is under the trade name LUBRICON RA LNP Engineering Plastics, Division of ICI Advanced Materials of Exton, Pennsylvania.

Example 3

Separate Slices of fiber reinforced Polyamide resin was prepared. For comparison were also specimens from conventional, no fibers containing nylon and Teflon made. The relative transfer efficiency was determined as in Example 1. The results are in the table below I shown.

Table I

Despite the fact that the KEVLAR ^® fiber -Tow charges the powder in the comparative example, positive, surprisingly, the addition of such a fiber to the negatively charging nylon to an increased relative transfer efficiency.

3. The aminoplast resins

The Aminoplast resins include polymerized units of an amine monomer and an aldehyde monomer. Preferred aminoplast resins are aniline-formaldehyde resins, Urea-formaldehyde resins and melamine-formaldehyde resins. The aminoplast resins optionally further comprise cellulose such as alpha cellulose and pigments.

With Alpha cellulose filled Melamine-formaldehyde resins with suitable impression quality are under the trade name Perstorp 752026 white melamine or Perstorp 775270 Red melamine from Perstorp Compounds, Inc., Florence, Massachusetts, commercially available. Another suitable melamine resin is a melamine-phenol-formaldehyde copolymer, under the trade name Plenco 00732 from Plenco Plastics Engineering Company in Sheboygan, Wisconsin, is commercially available.

One another suitable melamine resin is a melamine-formaldehyde polymer, Perstorp 752-046, supplied by Perstorp Compounds, Inc. of Florence, Massachusetts, available is.

Example 4

It were individual slices of the white melamine formaldehyde resin Perstorp 752026 filled with alpha cellulose procured. For comparison were also discs made of conventional Nylon 6/6 made. The relative transfer efficiency became as determined in Example 1. The results are in the following Table II.

Example 5

It were single slices of the red peppercorn melamine formaldehyde resin Perstorp 775270 filled with alpha cellulose procured. For comparison were also discs made of conventional Nylon made. The relative transfer efficiency was determined as in Example 1. The results are in the following Table II.

Example 6

It were individual slices of the melamine-phenol-formaldehyde resin Plenco Procured 00732. For comparison, also discs made of conventional Nylon made. The relative transfer efficiency was determined as in Example 1. The results are in the following Table II.

Example 7

It were individual slices of the white melamine formaldehyde resin Perstorp Procured 752-046. For comparison, also discs made of conventional Nylon made. The relative transfer efficiency was determined as in Example 1. The results are in table II shown.

Table II Relative transfer efficiency of Ferro 153W-121 on contact with amino resin specimens

Examples 8 to 10

It was a short-barreled triboelectric gun, as described in Section II herein and in 2 with the inner surfaces of the gun, particularly the inner surfaces of the powder tube insert and the flat spray nozzle, made of red peppercorn melamine formaldehyde, designated as Perstorp 775270 by Perstorp Compounds Inc., Florence, Massachusetts. The gun used in the experiment had two pairs of air nozzles and two electrodes. The air nozzles were offset from the centerline perpendicular to the longitudinal axis by one nozzle diameter and the second set of air nozzles rotated 5 degrees about the longitudinal axis with respect to the first set of air nozzles. The angle of the air jets was 90 degrees.

Of the relative transmission efficiency was sprayed onto a target object by spraying a fixed amount of powder determined that is perpendicular to the spray gun at a speed of 10 feet per Minute (3,048 m / min) moves. The powder in the spray gun was an epoxy polyester powder from Ferro called 153W-121 Corporation. The results are shown below.

Table III

4. acetal resins

The acetal resin is a technical thermoplastic polymer of polyoxymethylene. The acetal resin is a homopolymer or a copolymer. The acetal resin is optionally combined with polytetrafluoroethylene, polytetrafluoroethylene fibers and polyethylene or other polymers or additives. Suitable acetal are available under the trademark Delrin ^® from EI DuPont de Nemours & Co., Wilmington, Delaware, commercially. A suitable example is an acetal homopolymer resin with 20% Teflon PTFE fibers and is commercially available under the trade name Delrin AF. An advantage of this material is that electrical shock to operators using this gun is less likely due to stored capacity than other materials tested.

A suitable modified copolymer resin is an acetal copolymer, which is modified with a polyethylene with ultra high molecular weight polyethylene (UHMWPE), which is commercially available under the trade name Ultraform ^® N2380X from BASF Corp., Parsippany, New Jersey. Another suitable acetal is under the tradename Celcon ^® from Hoechst Celanese Corp. in Chatam, New Jersey, commercially available.

Example 11

It was a short-barreled tribocharging gun, as described in Section II below and in 2 with the inner surfaces of the gun, particularly the inner surfaces of the insert, made of Delrin 150 acetal polymer from DuPont.

The Powder in the spray gun was an epoxide polyester powder designated as 153W-121 Ferro Corporation, or a polyester referred to as 153W-281 / Urethane powder from Ferro Corporation. The transfer efficiency became as determined in Examples 8 to 10. The results are shown below.

The transfer efficiency results amount at a flow rate of approximately 2.5 g / s 62% for both powders as shown in Table IV below.

Table IV

An advantage of these acetal resins is that they can be injection molded, making it possible to produce a low-cost powder spray gun. The results of the relative transfer efficiency for the delrin acetal resin were surprising and unexpected because the delrin resin does not contain any nitrogen atoms normally found in negatively charging materials such as nylon and melamines. It was also discovered that the presence of PTFE fibers in the Delrin acetal resin, such as the Delrin AF acetal resin, resulted in an increase in the transfer efficiency over the Delrin acetal resin.

B. Negative triboelectric charging pistol with unconventional materials

Referring to 1 There is a triboelectrically charging powder spray gun 10 for use in the method and apparatus of the present invention. The gun 10 includes a gun body 12 with a central opening extending therethrough. The gun 10 may be carried by a suitable gun attachment assembly known to those skilled in the art. The gun 10 includes a powder feed section 20 , a triboelectrically charging section 30 and a spray head section 40 at an outlet end of the gun.

The triboelectrically charging section 30 The gun includes an inner core 34 that is inside an outer cylinder 32 is arranged, in which the surfaces 34a . 32a cooperate to provide an annular charging path for the powder flowing through the loading path of the gun. As in 1 shown can be the surfaces 34a . 32a optionally have a wavy or uneven surface, such that the annular gap provides a tortuous path for the powder, whereby the powder contact with the surfaces 34a . 32a is improved, so that the powder is charged.

In the preferred embodiment of the invention, some or all of the powder contact surfaces of the gun are made of a material selected from the group consisting of: a polyamide blend, a fiber reinforced polyamide resin, an acetal polymer, an acetal polymer homopolymer, a copolymer, preferably filled with PTFE fibers ( hereinafter collectively referred to as acetyl polymer), an aminoplast resin or mixtures thereof. These are the unconventional, negative-charging, triboelectric materials of this invention that were identified as being well-charged. Thus, the powder contact surface may be coated with the aforementioned material, or the corresponding component having the powder contact surface may be wholly or partly made of the aforementioned materials. As in 1 is shown, thus the powder contact surfaces of the outer cylinder 32 , the inner core 34 and the nozzle 40 of a material selected from the group consisting of a polyamide blend, a fiber reinforced polyamide resin, acetal polymer, aminoplast resin, or mixtures thereof. In addition to the powder contact surfaces of the inner abrasion sleeve 38 , the outer abrasion sleeve 40 , the inlet wear sleeve 41 , the inlet manifold 36 , the outlet distributor 37 and the exhaust wear sleeve 42 coated with a material or consisting entirely of the material selected from the group comprising a polyamide blend, a fiber reinforced polyamide resin, acetal polymer, aminoplast resin or a mixture thereof. Other powder contact surfaces not specifically referred to herein may include the above-mentioned materials.

A grounded electrode 43 A discharge ring or other means known to those skilled in the art (not shown) may be used to dissipate the charge of the powder contact surfaces of the inner core and the outer cylinder. The grounded electrode or discharge ring may be in any position known to those skilled in the art.

As in 1 is shown, powder and the conveying air to the powder supply section 20 guided. Powder emerges from the feed section 20 in the charging section of the gun and is guided in the annular charging path, which between the inner core 34 and the outer cylinder 32 is arranged. When the air entrained powder is the powder contact surfaces 32a . 34a of the outer cylinder 32 and the inner core 34 repeatedly contacted, the powder is charged triboelectrically to a negative polarity. Finally, the triboelectrically charged powder is placed in a spray head section 40 the pistol discharged. By using unconventional, negatively charged, triboelectric materials, the powder is negatively charged, but with the gun, there is no unacceptable impact fusion of the powder to the charging surface.

II. Short-term, triboelectric Charging powder spray gun, made of new, negative triboelectric is made of charging materials

As in 2 1 shows a first embodiment of the short-running tribocharging gun according to the invention 200 a new powder spray gun of relatively simple construction and small size, which charges powder through the triboelectric charging process. The invention has the Advantage of a replaceable insert 220 which can be easily exchanged for quick color change of the powder. An important advantage of the short-barreled triboelectric gun is that it does not have the disadvantages of high electric fields or reionization problems that occur with corona guns. The gun described in more detail below can charge a powder positively or negatively. The triboelectric powder charge pistol, which generally with 200 from the powder inlet to the nozzle tip has an overall length in the range of about one to ten inches (2.54 to 25.4 cm), and more preferably in the range of one to six inches (2.54 to 15.24 cm) is substantially less than the total length of known tribo-charging guns, which usually range in length from 14 to 36 inches.

The main components of the gun are a body 210 , a powder tube insert 220 in the body 210 built-in, and a nozzle 230 also in the body 210 installed or otherwise attached to this. The use 220 and the nozzle 230 together make up the barrel of the gun. The body 210 can be made of any structurally suitable material. The body 210 has an inlet end 212 with an opening that is adapted to use 220 and an outlet end 214 that is adapted to the nozzle 230 receives or connects to this. For manual use can be on the body 210 a handle or pistol grip (not shown) attached or as an integral part of the body 210 be educated.

The powder tube insert 220 is preferably a cylindrical tube with an internal powder channel 222 , The inner diameter of the powder channel 222 may preferably range from about 0.25 inches to about 1.5 inches (0.635 to 3.81 cm), and is preferably 0.5 "(1.27 cm).

It is preferred that the use 220 is exchangeable or releasably connected to the body by conventional methods. For a negative polarity gun, it is preferred that the insert 220 made entirely of the materials or an inner surface coated with the materials 222 which are selected from the group of polyamides, preferably nylon 6/6, a polyamide blend, a fiber reinforced polyamide resin, acetal polymer, aminoplast resin or mixtures. For a positively charging pistol can use 220 completely made of a triboelectrically charging material or coated with a triboelectrically charging material inner surface 222 such as, but not limited to, fluoropolymers, especially polytetrafluoroethylene, or mixtures thereof. Thus, depending on the nature of the selected triboelectrically charging material, the powder particles will be in contact with the inner powder contact surfaces of the insert 220 charged negatively or positively.

The spray gun 200 may also include one or more air jets 240 have in the inner channel 222 . 234 the gun are provided. The air nozzles 240 can within the insert 220 or the nozzle 230 be arranged and are effective for generating turbulence, resulting in an increase of the frictional contact of the powder with the walls 222 of the insert 220 or the nozzle 230 leads. Air or other fluids (hereinafter air) will be the air jets 240 about one in the body 210 trained air duct 250 fed to a chamber 252 to the use 220 or the nozzle around (not shown) leads. One or more air jets 240 lead from the chamber 252 to the powder channel 222 . 234 in use 220 or in the nozzle 230 (Not shown).

The air nozzles 240 can have any opening shape, such as a round, rectangular, square or oval. Each air jet cross-sectional area may be between about 0.001 to 0.03 square inches (0.0065 to 0.194 cm ² ), which corresponds to a round orifice size of about 0.03 to about 2 inches (0.076 to 0.508 cm) in diameter. More preferably, each air nozzle cross-sectional area may range from about 0.003 to about 0.005 squares (0.0194 to 0.0323 cm ² ) (corresponding to a round hole diameter of about 0.06 to about 0.08 inches (0.152 to 0.203 cm)). Most preferably, the air jet cross-sectional area may be about 0.0038 square inches (0.0245 cm ² ), which corresponds to a round orifice diameter of about 0.07 inches (0.178 cm).

As in 2 shown, define the air nozzles 240 with respect to the longitudinal axis or an insert or nozzle sidewall of the inner channel 222 an angle θ in the range of about 0 to about 90 degrees, and more preferably in the range of about 45 to about 90 degrees, and most preferably about 60 degrees.

The air nozzles may be arranged in one or more groups of air nozzles of the same or different diameters. One group may consist of two or more air nozzles, which may be arranged either in an opposed or non-opposed arrangement. The 3A - 3D show alternative configurations of the arrangements of upper and lower air nozzles 240 of the insert 220 , 3A shows an upper and lower air nozzle 240 in which the air flow from the nozzles intersects on the longitudinal axis (or center line CL). Both the upper and lower air nozzles form with the insert sidewall 222 an angle of 45 degrees. 3B is almost the same configuration as 3A except that the center of the upper air nozzle is offset longitudinally from the center of the lower air nozzle, resulting in air flow from the air nozzles intersecting at a point offset from the longitudinal axis. 3C shows that the air nozzles may have different air nozzle angles, resulting in a flow from the air nozzles intersecting at a point offset from the longitudinal axis. 3D shows that the upper and lower air nozzles may be offset longitudinally and may have different angles, yet still result in flow out of the nozzles intersecting the longitudinal axis.

When two or more air nozzles are used, one air nozzle may be offset from the other air nozzle by a distance H perpendicular to the longitudinal axis, as shown in FIGS 4B - 4E is shown. Thus, the air nozzles in the 4B - 4E by vertically varying the vertical (or vertical) distances H with respect to the longitudinal axis. The distance H can be from 0 (no offset) as in 4A shown up to a diameter of the insert as in 4E vary.

As in the 5A to 5H As shown, when two or more sets of air nozzles are used, a group of the air nozzles may be rotated at an angle about the longitudinal axis with respect to the first group of air nozzles in a clockwise or counterclockwise direction. It is preferred that the downstream group of air nozzles is rotated at an angle ranging from about 0 to about 90 degrees with respect to the first group either clockwise or counterclockwise. The 5A . 5C . 5E and 5G Each represents a first or upstream group of air nozzles in use 220 of the 2 are arranged. The 5B . 5D . 5F and 5H represent a second or downstream group of air jets which, with respect to the corresponding first set of air jets, of the 5A . 5C . 5E respectively. 5G counterclockwise by 0, 45, 90 and 0 degrees are rotated. 5H also shows that the second group of air nozzles can only comprise one air nozzle.

The total air flow to the four air vents 240 in 2 can range from about 0.3 cubic feet per minute (CFM) (141.5 cm ³ / second) to about 6.5 cubic feet / minute (3067.7 cm ³ / second). When two pairs of air nozzles are used, the total air flow rate to the air nozzles is preferably 4.2 CFM (1982.2 cm ³ / second). The air nozzle openings 240 typically have an air velocity in the range of about 100 to about 1000 feet / second (0.51 to 5.08 m / s), and most preferably in the range of about 400 to about 800 feet / second (2.03 to 4.06 m / s), and most preferably about 655 feet / second (3.33 m / s). These variables can be suitably dimensioned for pipes with different diameters.

The internally charging pistol 200 is further with one or more electrodes 260 or other means known to those skilled in the art for discharging the tribocharging surfaces 222 . 234 due to the charge due to frictional contact with the powder. For example, the electrode may be a conductive pin, a pressed, solid metal ring, an air-cleaned porous ring, or a metal strip disposed along the charging tube along the longitudinal axis. The one or more electrodes are preferably electrically grounded. The electrode 260 However, it can also be charged to either a positive or a negative electrical potential, as in 2 is shown, preferably in the range of about 0 to about 10 kilovolts (KV). The electrode 260 can be inside the insert 220 or the nozzle 230 However, it is preferred that the electrode is arranged upstream of the air nozzles. The one or more electrodes 260 can be air-cleaned, ie from the chamber 250 through the channels 262 and 264 An air flow is provided to powder from the electrode 260 blow away.

In 2 is in the context of the invention, a flat spray nozzle 230 although other known nozzles would also work for the invention. The nozzle 230 has a slot 232 which generates a substantially flat spray pattern, and an inner channel 234 that with the inner channel 222 of the insert 220 is in flow communication. It is preferred that the nozzle 230 removable or detachable with the gun body by any conventional method 210 connected is. In addition, because the nozzle is an area of greater powder contact, it is preferred for a negative triboelectrically charging gun that the nozzle 230 entirely of a triboelectrically charging material such as polyamide, especially nylon 6/6, a polyamide blend, fiber reinforced polyamide resin, acetal polymer, aminoplast resin or Mi. made of it, or an inner surface coated with such a material 234 has. For a positive triboelectrically charging gun, it is also preferred that the nozzle 230 is made entirely of a triboelectrically charging material such as fluoropolymers, in particular PTFE, or an inner surface coated with this material 234 has. Thus, it depends on the nature of the selected triboelectrically charging material, whether in contact with the inner surface 234 the nozzle 230 a negative or positive charge is transferred to the powder particles. Thus, the nozzle works 230 with the inlet 220 together to triboelectrically charge the powder particles to the desired polarity as they enter the inner surface of the gun 200 touch.

Although not shown, the use can 220 and the nozzle 230 be formed as an integral one-piece unit, the detachable on the body 210 is attached (not shown). Alternatively, the use can 220 and the nozzle 230 releasably connected to each other and then releasably secured to the body. Thus, there is a particular advantage of the short, internally charging pistol 200 the invention in the simple construction of the insert 220 and the nozzle 230 so that these components can be made of or coated with any of the described triboelectrically charging materials and in a simple manner with the gun body 210 can be exchanged. For use with a single gun body can be a series of inserts 220 and nozzles 230 can be provided, which are made of different triboelectrically charging materials or coated with these. A suitable insert and nozzle may then be selected according to the type of powder to be sprayed and in accordance with the type of polarity to which the powder is to be charged. Since powders charge differently depending on their chemistry, a material-specific use for a particular powder chemistry can be used. For example, epoxy resins tend to positively charge, so PTFE use would be ideal for this powder. On the other hand, polyesters tend to charge negatively and therefore it would be better to charge them using a nylon insert.

The The following examples show several gun configurations varying arrangement of air nozzles, Type and position of electrodes and use of triboelectric charging materials. However, the invention is not limited to these Examples limited, because many other combinations and configurations are possible.

Example 12

In one example of the invention, a tribocharging gun was used 200 with an insert 220 made of nylon 6/6 material. The insert had two pairs of aligned opposed air nozzles with each air nozzle angled in the insert sidewall at an angle θ of 60 degrees and a speed of about 655 Feet / Second (3.33 m / s) and a total air flow rate of 4.2 cubicfoot / minute (1982.2 cm ³ / s). The centerline of the first pair of air jets is spaced from the centerline of the second pair of air jets longitudinally by 0.625 "(1.588 cm) A grounded electrode was mounted flush with the inside surface of the powder flow channel and was offset by the air jets at an angle of 60 degrees The gun was 5.75 inches (14.61 cm) long, measured from the powder inlet to the tip of a flat spray nozzle The powder flow rate was 20 lbs / hr (9.07 kg / hr) using Ferro 153W-108 polyester urethane powder for this configuration was 78.0%.

Example 13

In another example of the invention for the same pistol configuration as was used in Example 12, the Electrode at -8 KV charged. The transfer efficiency became measured at 84%.

Example 14

In another example of the invention, the short-acting tribocharging gun was fabricated from Delrin 100 AF material. The combined total length of the insert and die was 3.375 inches (8.573 cm). A 4 mm Delrin 100AF flat spray nozzle was used. As in 2 The insert inlet diameter was 0.375 inches (0.953 cm) at a length of 1.25 inches (3.175 cm), followed by a 45 degree step that measured the insert diameter for the remaining length of 2.125 inches (5.40 cm). opens to 0.5 inches (1.27 cm). Two pairs of opposing air nozzles were used, each air nozzle having a diameter of 0.07 inches (0.178 cm) and an angle θ of 60 degrees. The downstream set of air jets was about 5 degrees with respect to the first pair of air jets Rotated longitudinal axis. All air jets were offset by 0.035 inches (0.089 cm) at a perpendicular distance from the longitudinal axis. Each air nozzle had an air flow rate of approximately one standard cubic feet per minute (471.95 m ³ / s) and a speed of 655 ft / sec (3.33 m / s). A single grounded electrode with a sharp tip was placed upstream of the air nozzles as shown in FIG 2 is shown. The electrode was rotated about the longitudinal axis with respect to the first set of air jets at an angle of 60 degrees. The transfer efficiency for this configuration was 70% using Ferro 153W-121 at 20 lbs / hr (9.07 kg / hr).

Summarized represents the short-circuited, triboelectrically charging Pistol ready a new light spray gun due to the shortly Length and the smaller diameter of the gun in narrow spaces easily maneuvered can be. conventional Tribocharging guns are usually 14-36 inches (35.56 - 91.44 cm) long while the short triboelectrically charging pistol has a pistol with one length of approximately 6 inches (15.24 cm). The gun is suitable as manual Pistol or for use as a cheap automatic pistol. The straight powder flow path allows both easy cleaning and a replaceable Use that for Quick color change easily replaced by a cheap use can be. The new materials used to make the pistol are used, are injection moldable, which is why the production costs be significantly reduced. Thus, the invention provides a triboelectric Charging gun with short barrel ready, which has a powder flow rate from up to about 30 lbs / hr (13.61 kg / hr) and provide acceptable transmission efficiency can.

The Invention also provides a short-circuit, triboelectric negative charging pistol ready alone or in conjunction with one negative corona gun can be used as below is described in detail. While it has all the advantages described above, has the triboelectric Negative charging pistol with short barrel also has the advantage of polyester powder, such as TGIC polyester, epoxy / polyester hybrid powder and polyester urethanes, as well as thermoplastic powders such as PVC and PTFE powder, excellent to apply and charge.

III. Unipolar corona pistol with triboelectrically charging components

Referring to 6 is a unipolar corona spray gun 300 for spraying liquefied powder which has been charged to either positive or negative polarity. The term "unipolar" refers to a powder spray gun or powder delivery system wherein the components are selected to charge the powder coating material to a single polarity, for example, a corona gun having a negative polarity electric power supply comprising triboelectrically charging components for example, the spray nozzle, which also negatively charges the powder 300 includes a rear barrel 328 which can be attached to a mounting block. The back run 328 has an internal bore 332 and an angular hole 333 for connection to a powder feed tube 334 , The powder feed tube 334 Used to introduce liquefied powder through the angled hole 333 into the through hole 332 the rear running element 328 , The front end of the rear runner 328 is with a front running element 338 connected, which also has a through hole 346 that with the bore 332 axially aligned to a powder flow path 350 for transporting the powder from the powder feed tube 334 to the front end of the pistol 300 to build. At the front end of the front running element 380 is a flat spray nozzle 394 arranged.

In the powder path 350 extends axially a running insert 352 , which is inside the end of the rear running element 328 is attached. The running insert 352 takes a high voltage electrostatic cable assembly 358 up and holding this. At the front end of the cable assembly 352 is an electrode 362 attached and extends through a hole 396 the nozzle tip 390 and extends from the spray nozzle 394 between the rectangular slot 398 Forward. The electrode 362 extending from the spray nozzle 380 extends forward, creating a strong electrostatic field between it and the object to be coated. The electrode may be positively or negatively charged depending on the desired gun polarity. It is preferred that the electrode be charged in the range of about 60 to about 100 KV to the desired polarity.

The powder contact surfaces of the corona gun 300 are the running insert 352 , the powder path 350 , the powder feed tube 334 and the passage 372 through the nozzle 380 , For a corona gun of positive polarity, which positively charges the powder, there are one or more powder contact surfaces 334 . 350 . 352 or 372 For example, from materials that positively triboelectrically charge the powder. These materials are selected from the group consisting of: polyethylene, fluoropolymer or mixtures thereof. It is preferred the fluoropolymer contains polytetrafluoroethylene. For a negative polarity corona gun, which negatively charges the powder, one or more of the powder contact surfaces become 334 . 350 . 352 or 372 for example, the corona pistol 300 selected so that they are made of a material that charges the powder triboelectrically negatively. These surfaces are made of a material selected from the group consisting of: a polyamide, a polyamide blend, a fiber reinforced polyamide resin, an acetal polymer, an aminoplast resin, or mixtures thereof, as described in detail in Section I.

Consequently uses the unipolar corona gun of the present invention the triboelectric charging for charging the powder as well Corona charging. The occurring triboelectric charge has the same polarity like the powder charge resulting from the corona charge electrode and increased she therefore. Because the powder contact surfaces to from the corona electrode Generated charge of the powder, less electrode voltage needed to produce the same amount of charge as with known pistols. Thus, with a negative polarity gun, a reduced one occurs back ionization because the voltage is lower. This leads to an improved surface finish. This reduction in electrode voltage also reduces the Faraday cage effect. Furthermore a smaller power connector can be used to the same To create tension.

In an alternative embodiment of the invention, the corona gun 300 also an improved triboelectrically charging nozzle 400 included as it is in 7 is shown. The triboelectrically charging nozzle 400 Can be used with other known corona or tribocharging guns and is not on the corona gun described above 300 limited. The triboelectrically charging nozzle 400 provides a large internal surface area that can be used to charge the powder triboelectrically. The powder may be positively or negatively charged as desired, depending on the selected triboelectric material, as described in detail below.

The generally as 400 shown nozzle, has a powder inlet end 410 and an inner flow channel 412 which is in fluid communication with the internal passage of a known corona gun or triboelectric gun (not shown). The inlet end 410 may be threaded or otherwise designed so that it is releasably connected to the body of the prior art spray gun. The inner channel 412 is preferably cylindrical with a transition surface 414 leading to the nozzle slot 420 leads. The nozzle 400 has a slot 420 formed to produce a substantially flat spray pattern. The depth and width of the nozzle slot 420 can be dimensioned as required by the particular application.

Because the nozzle surfaces 412 . 414 are in contact with the powder, it is preferred that the nozzle 400 is completely made with a triboelectrically charging material or has a coated with this inner surface. For a positive polarity corona gun, it is preferred that the nozzle be made of or have coated with a material having internal powder contact surfaces selected from the group consisting of: fluoropolymers, especially PTFE. For use with a negative polarity gun, it is more preferable that the nozzle 400 made entirely of materials or coated with this interior surfaces 412 . 414 which is selected from the group consisting of: a polyamide, especially nylon 6/6, a polyamide blend, a fiber reinforced polyamide resin, an acetal polymer, an aminoplast resin, or mixtures thereof. Thus, the powder particles become in contact with the inner surfaces 412 . 414 the nozzle 400 charged negatively or positively depending on the selected type of triboelectrically charging material. Thus, the nozzle can 400 work together with the corona charging electrode of the prior art spray guns to charge the powder with the same polarity as the corona electrode.

The nozzle 400 may preferably have one or more air vents 430 include, for fluid communication with the inner channel 412 the nozzle are arranged. Air or other fluid is added to the air vents 430 for example through a chamber 440 made available through an opening 450 is connected to an external fluid source (not shown). It is preferred that the air vents 430 are sized and configured to have an air velocity in the range of 100 to about 1000 feet / second (30.48 to 304.8 m / s), and preferably in the range of about 400 to about 800 feet / second (121.9 to 243.8 m / s) is made available. It is further preferred that the airflow opening (s) 430 with respect to the longitudinal axis of the inner channel of the insert at an angle in the range of about 0 to about 90 degrees, and preferably in the range from about 45 to about 90 degrees. It is preferred that the angle of the air nozzle openings 430 such is that the air jets intersect, so that turbulence is provided, which leads to a larger frictional contact with the Charging surface leads. It is preferable that the impact angle β of the air jets on the interface 414 should be in the range of about 45 to about 90 degrees and more preferably about 60 degrees.

The nozzle 400 can additionally have one or more electrodes 460 or other means known to those skilled in the art for charging the interior surface 412 dissipate. The one or more electrodes are preferably grounded. Alternatively, the one or more electrodes may have a positive or negative charge in the range of about 0 to about 100 KV, and more preferably in the range of about 0 to about 10 KV. The high voltage electrode (s) become positively charged when using an electronegative charging material, and the electrodes are negatively charged when an electropositive charging material is used on the inner surface of the nozzle. As in 7 As shown, the electrode may be in an electrode holder 490 be arranged. The electrode holder 490 has an outer surface 492 , which is made of materials above for the inner channel 412 the nozzle were described. However, it is important to note that other electrode configurations are possible, such as a grounded ring or a conductive pin with a blunt or sharp tip. If a conductive pin is used, it can be at right angles to the flow channel anywhere in the nozzle 400 be arranged. The electrodes are located upstream within about 2 inches (5.08 cm) of the air jet impingement on the wall.

In a preferred embodiment of the nozzle 400 For example, the electrode is grounded and disposed upstream of two pairs of aligned, opposed air nozzles that are laterally spaced by a diameter. The air jets are angled 60 degrees with respect to the longitudinal axis.

IV. Triboelectrically charging Components of the powder delivery system

The The invention further provides tribocharging powder contacting surfaces various components throughout the powder delivery system are available for triboelectric charging of the powder to the same polarity as the Korona powder feed can be used. The triboelectric charging in several areas along the supply system elevated the powder charge gradually, if it is the triboelectric Charging area goes through. This benefits Koronapistolensystemen with higher transmission efficiency. This idea can also be applied to triboelectrically charging pistol systems be used. The triboelectrically charging regions of the powder delivery system Charge the powder triboelectrically to the same polarity as it is used in the triboelectric guns of the system.

As in 9 shown includes a typical powder spray system 500 a spray gun 510 passing through a powder feed tube 540 via a powder pump attached to the top of the container 530 with a container 520 connected is. The spray gun 510 is, for example, a corona type negative charge powder spray gun, but may alternatively be a positively charging corona gun or a negative or positive triboelectrically charging powder spray gun.

From the tax system 550 that the air pressure to the pump 530 and the voltage of the corona electrode in the gun 510 is an electrical line 544 to the gun 510 connected. In the powder container 520 is an atomizer plate 521 designed to extend over a cross-sectional area in the container, and is formed of a porous material through which air flows to fluidize the powder. Because the container sidewalls 522 and the atomizer plate 521 contact areas of the powder, the invention includes the structure of the plate 521 and sidewalls 522 of the negative triboelectrically preloading materials selected from the group consisting of polyamides, especially nylon 6/6, a polyamide blend, fiber reinforced polyamide resin, acetal polymer, aminoplast resin, or mixtures thereof. Thus, the powder becomes due to the contact of the powder with the atomizer plate 521 and the side walls in the container 520 previously charged before going to the negative coronary pistol 510 is transported.

The average in 8th shown pump 530 includes a body 531 with a powder inlet tube 532 that leads to a cavity 533 that leads from an ejector or a Venturi nozzle 534 and a venturi nozzle neck 535 is cut. The Venturi nozzle neck 535 is through a nozzle neck holder 536 in the pump body 531 held, which extends from the pump body to a mounting connector 537 to provide for a hose. In the mounting fitting 537 is an abrasion sleeve 538 , also referred to as Abriebrohr, arranged downstream of the pump nozzle neck. The wear sleeve prevents the impact fusion joint on the inside wall of the nozzle neck holder. An atomizing air inlet 539 cuts with the nozzle neck holder 536 to provide a flow of air that connects to the powder-air mixture from the venturi neck.

This area in the powder delivery system is thus a suitable location for the application of one of the described preloading materials. Thus, it is desired that the Venturi neck 535 , the abrasion sleeve 538 , the pump suction tube 532 and the powder hose (not shown) is coated or made from the materials selected from the group consisting of a polyamide, a polyamide blend, fiber reinforced polyamide resin, acetal polymer, aminoplast resin, or mixtures thereof, as described in detail above pre-charge the powder triboelectrically with a negative polarity. It is also preferred that the length of the Venturihalses 535 and the nozzle neck holder 536 for example, be extended one to five inches (2.54 to 12.7 cm) beyond the edge of the pump body out. Optimally, this extension provides for substantial additional negative triboelectric charging of the powder in this area of the powder delivery system.

in the Powder feeding system in the container and / or the pump pre-charged powder, as in this section described, flows through the hose, making it the gun with a predetermined reached negative charge. This pre-charge improves the extra negative, applied to the gun by the corona electrode Charge.

V. Unipolar powder coating system including Corona and triboelectrically charging pistols

As in 9 shown is a corona pistol 510 together in use with a triboelectrically charging powder spray gun according to the invention 10 shown in detail above. The corona pistol 510 and the triboelectrically charging pistol 10 have the same polarity. The unique combination allows the use of the tribo-charging gun 10 as a repair gun, for example, to penetrate into the corners or hard to reach parts, the Koronapistole 510 not effectively coated. This exemplary combination of a negative corona pistol 510 and a negative triboelectrically charging gun 10 is preferably to a common powder feed system 520 connected, which precharges the powder negative as described above. Alternatively, the tribo-charging gun can be the short-barreled gun 200 (not shown), which is described in more detail above. This new combination of one or more negative corona guns with one or more negative triboelectrically charging guns, optimally with a pre-charged negative powder feed system used to coat different parts of the same workpiece, is an important embodiment of this invention.

VI. Triboelectrically charging Pistol with air nozzles

As in 10 shown is a new triboelectrically charging pistol 600 provided, which has a powder feed section 610 , a powder charging section 620 and a spray nozzle 630 includes, which is arranged at the outlet of the gun. The powder charging section 620 the triboelectrically charging pistol 600 also includes a cylindrical body 622 , which is an internal bore 623 for picking up the internal components of the gun. A first end 616 of the connector 612 is provided with a powder supply pipe (not shown) for supplying fluidized powder to the powder flow path 626a, b, c the gun 600 connected. The second end 618 of the powder tube connector 612 is with an intake air inlet 640 connected. The intake air inlet 640 has an interior channel 626b and one or more angular openings or air jets 642 that with one in the body 622 arranged air distributor 628 for supplying compressed air to the air nozzles 642 connected to increase the speed and turbulence of the entering into the gun fluidized powder to produce. With the intake air inlet 640 is an outer abrasion tube 650 connected, which has an inner channel, the part of the powder flow path 626 the gun is. The outer abrasion tube 650 also includes one or more air jets 652 , The air nozzles 652 is over a channel 654 which is in fluid communication with the air manifold 628 stands, compressed air provided. The gun 600 Can also with an optional inner abrasion surface 660 be provided, which forms an annular powder flow path. As in a sectional view in 10A shown are several air nozzles 652 arranged in opposing arrangement at one or more locations in the longitudinal direction. Preferably, the air nozzles 652 an angle γ (measured counterclockwise from the longitudinal axis) preferably in the range of about 90 to about 135 degrees. The air jet velocity is preferably high enough to create turbulence and to cause the powder flowing through the channel to contact the wall opposite the air nozzle to increase the triboelectric charge of the powder. It is preferred that the air jet velocity be in the range of about 100 to about 1000 feet / second (30.48 to 304.8 m / s), and more preferably in the range of about 400 to about 800 feet / second (121.9 up to 243.8 m / s).

To provide triboelectric charging of the powder, the powder contact surfaces of the gun are such as the inner surface of the powder flow channel 626a - c , the nozzle 630 and the outer surface of the inner charging tube 660 made of or coated with a triboelectrically charging material. For a positive tribocharging gun, the powder contact surfaces are preferably selected from the group consisting of: fluoropolymers, especially PTFE. For a negative tribocharging gun, the powder contact surfaces are preferably selected from the group consisting of: nylon, especially nylon 6/6, a fiber reinforced polyamide resin, an acetal polymer, an aminoplast resin, or mixtures thereof.

In yet another embodiment of the invention, as in 11 is shown, the tribocharging gun is the same as that described above except for the following differences. First, no inner charging tube 660 used. Second, are the air jets 652 the triboelectrically charging pistol 600 in the outer abrasion tube 650 are arranged in a spiral pattern arranged around the longitudinal axis, as in the 11 and 11A is shown. The at the upper part of the pipe 650 arranged air nozzles 652a can optionally have a different angular orientation than that at the bottom of the tube 650 (not shown) arranged air nozzles 652b to have. The air nozzles 652a . 652b are constructed in this arrangement so that the fluidized powder impinges on the opposite wall in a staggered or wavy shape to increase the triboelectric charging of the powder. It is preferred that in the arrangement 3 - 4 sets of openings are arranged, each set comprising two or more openings. This helical arrangement serves to generate turbulence and turbulence of the fluidized powder in a spiral shape so that the relatively heavier powder is rapidly rotated or caused to strike the wall via centrifugal forces in contact with the channel wall.

An advantage of this embodiment is to cause the multiple impact of each powder particle on the charging surface and thereby increase the powder charge, instead of forming mechanical waves on the charging surface, as is the case for the pistol 1 is shown, in which the charging surface is a straight cylinder, which is easy to manufacture, while the air nozzles 652 cause the powder particles to make a turbulent path through the flow channel 626 a, b, c take several hits on the surface to increase the triboelectrically generated charge of the powder.

With reference to 12 is another embodiment of the short-barreled tribocharging gun 200 of the 2 shown. In the embodiment of the 12 includes the modified pistol 200 ' a gun body 210 ' holding a powder pipe insert 800 picks up something of the use 220 in 2 different. The use 800 includes a powder feed inlet 802 and an optional atomizing air inlet 804 , Atomizing air can be used as needed to control the powder speed through the pipet 200 ' to increase. The increased speed increases the triboelectric charging effect on the powder and helps to spray the powder and can also be used to influence the spray pattern. However, atomizing air is not required in all situations and depends on various factors, in particular the speed and pressure of the powder feed tube 540 and associated powder feed components (see 9 and the related explanation) in the gun 200 ' counting powders, as well as how much additional spraying of the powder through the gun is required, if any. In many cases, where the air nozzles are integrated into a tribo-charging gun, the pressure drop created by the air flow through the air nozzles may be sufficient to avoid the use of atomizing air. This is particularly the case when the air nozzles are angled forwards to direct a substantial axial airflow forwardly through the gun, creating a suction effect at the powder inlet end of the gun. Reducing the total air consumption in a spray gun is usually advantageous because it reduces operating costs associated with operating air, impact fusion, and wear. Reducing the impact fusion compound helps accelerate color change and cleaning operations.

The inner end 800a of the powder tube insert 800 takes a first end of a charging tube 806 slidable on. The charging tube 806 is preferably made of any of the various materials described herein to positively or negatively charge the powder as desired for a particular application. The charging tube inlet 806a can be an optional inner diameter reduction or narrowing 808 which serves to increase the powder velocity (without increasing the diffuser air volume or pressure) and also to increase the powder in the middle volume of the charge tube 806 center again before the powder enters the main section of the charging tube.

Inside the boot tube 806 is a solid or hollow shaft 810 arranged longitudinally and preferably coaxially. This shaft 810 is preferably cylindrical and includes an optional taper to a conical end 810a to unload the shaft 810 to facilitate. The boot pipe 806 includes a metallic discharge or ground ring 812 that with a grounded discharge pin 814 connected is. The pencil 814 allows the self-discharge of the charging tube 806 and the shaft 810 During an injection process, when the triboelectrically charging surfaces charge. To accept a grounded pin or wire (not shown) that supports the grounding ring 812 contacted, is a hole 816 intended.

The body 210 ' includes an air inlet opening 250 ' in almost the same way as the opening 250 in the embodiment of the 2 , This opening 250 ' opens into an annular chamber 817 , The annular chamber 817 is in flow communication with another annular chamber 818 , which is generally defined by the space between the outer circumference of the shaft 810 and the inner surface of the charging tube 806 is limited, and surrounds it. The annular chamber 818 preferably forms a relatively narrow gap between the charging tube 806 and the shaft 810 , Through the wall of the charging tube 806 is a series of air jets 240 ' in a similar manner as the embodiment of the 2 provided, and compressed air flows from the outer annular chamber 817 to the inner ring chamber 818 through there. The exact location, number, angle and orientation of the nozzles 240 ' can be determined based on various factors described above. According to one aspect of the invention, the smaller annular chamber reduces 818 , in comparison, for example, with the diameter of the tube insert 220 in 2 , the movement distance of the powder particles considerably, from the air from the air nozzles 240 ' to the shaft 810 be pressed. Thus, less air is needed to impinge the powder on the triboelectrically charging surface of the shaft 810 at a comparable speed as in the embodiment of 2 to effect. This not only reduces the air requirement but also reduces impact fusion joint effects. In addition, the use of the shaft increases 810 the total surface area of the triboelectrically charging material to which the powder particles are exposed, considerably, because the powder on both the surface area of the shaft 810 as well as the inner surface area of the charging tube 806 incident. The air nozzles 240 ' can like in 12 forward and radially angled (with respect to the longitudinal axis of the gun 200 ' ), or they can be offset to a fast rotating air movement around the shaft 810 around as described above. The narrower annular chamber 818 also allows conventional triboelectric charging effects on the powder when passing through the gun 200 ' flows in an almost analogous manner as the application of a tortuous or undulating path for the passage of the powder in a known triboelectrically charging gun. The annular chamber 818 For example, it may vary from about 0.02 inches (about 0.51 mm) to about 0.5 inches (about 1.27 cm), although the exact dimensions chosen depend on the overall performance characteristics and requirements of each gun design.

The shaft 810 gets in the charging tube 806 positioned and held by any suitable device, such as centering pins (not shown). Furthermore, in the embodiment of the 12 the use 800 , the charging tube 806 and the nozzle 820 form the gun barrel and all of the various materials described herein to produce a positive or negative charge of the powder particles as desired when the stem 810 is made of such triboelectrically charging materials. In the embodiment of the 12 becomes a conventional flat spray nozzle 820 with a slot 821 however, any suitable nozzle design may be used.

With reference to 13 is an alternative embodiment of the variant 12 shown. Like parts are denoted by the same reference numerals and their description will not be repeated. In the embodiment of the 13 became the charging pipe 822 and the shaft 824 modified at their front ends, giving them a corresponding design of the nozzle body 826 cooperate to form a triboelectrically charging parallel wave path 828 to define the downstream of the annular chamber 818 lies. The wave path 828 is in the form of a hourglass-like reduced diameter in the nozzle body cavity 820 realized. The shaft 824 is formed with a corresponding geometric shape, and the front end of the charging tube 822 simply hits the back of the nozzle body 826 so that a smooth continuous profile is formed. In the cavity of the nozzle body 826 becomes a star of several radial legs 832 centered and held. If necessary, the star can 830 through a pencil insert 834 with the shaft 824 be connected or assembled, and at its front end may be the star 830 used to be a conventional conical nozzle 836 to keep. The star 830 is preferably made of a suitable triboelectrically charging material, such as those described above. In this embodiment, the gun works 200 ' then with both the air jets 240 ' , the charging tube 822 and the shaft 824 , which charge the powder at the beginning, as well as a triboelektrisch nachladenden function, by the Parallelwellenweg 828 is produced. Although in the embodiment of the 13 the triboelectrically charging section 828 is shown as a parallel wave pattern, this representation is intended to be exemplary only and not in a limiting sense understood who the. Those skilled in the art will readily appreciate that the tribocharging section can be realized using a variety of known triboelectrically-charging arrangements.

14 shows another modification of the pistol 200 ' in 12 , In this version is the shaft 810 in a slightly axially forward position compared to the shaft 810 in 12 built-in. This causes the positioning of the conical rear tip 810a of the shaft 810 closer to the ground pin 814 , This significantly increases the ease with which the shaft 810 can be discharged during an injection process.

14 Further, the concept includes both an initial, air jet assisted or induced triboelectrically charging function and an additional tribocharging function into the gun 200 ' to integrate. Note in 14 in comparison with the example of 13 that the air nozzles 240 ' behind the shaft 810 are arranged. This places the air-jet induced triboelectrically-charging function first, followed by a subsequent triboelectrically-charging function in the annulus 818 , The air jets transfer sufficient energy to the powder particles to impact the charge tube and shaft surfaces to charge the powder. The airflow generated by the air nozzles is sufficient to pass over the annular chamber 818 downstream of allowing a triboelectric charging effect without requiring a tortuous, wavy, or other conventional tribocharging path, although such triboelectrically charging methods and configurations may be used as needed.

With reference to 15 Next, another gun embodiment will be illustrated. The basic concept illustrated in this drawing is referred to herein as an "inside-out" gun because, compared to the embodiments described above, the flow direction of the air nozzles is reversed. Thus, for the sake of simplicity, the above embodiments may be referred to as "outside-in" gun configurations. In the embodiment of the 15 includes the pistol 840 then a gun body 842 , the back end 842a and a front end 842b has. The back end 842a includes a cylinder counter, which is a powder tube insert 844 slidably receives and holds. The powder insert 844 carries a powder pipe connecting piece 846 and an air inlet connector 848 , The use 844 takes a first end of a charging tube 850 and carries this, which is made of a suitable triboelectrically charging material, as described above. The charging tube 850 extends through the gun body 842 to a nozzle assembly 852 , The special construction of the nozzle arrangement 852 can be selected according to the requirements of a particular spray pattern. In the example of 15 includes the nozzle assembly 852 a nozzle body 852 who is a star 852b holds, which at one end a conventional conical nozzle 852c wearing. The star 852b can have radial legs 852d or other suitable elements, such as pins, embrace the star 852b in the nozzle body 852 to keep.

The use 844 takes a first or inlet end of an air tube 854 , which is realized in this example in the form of a hollow shaft, and holds this. The air tube 854 includes one or more air jets 856 formed at suitable angles and orientations as described above with respect to the other embodiments. In the example of 15 generate air nozzles 856 one forward to the front of the gun 840 directed airflow, but radially angled to powder on the inner surface 858 of the charging pipe 850 to steer. The inlet end 854a of the air tube 854 is in fluid communication with the air inlet fitting 848 , Therefore, compressed air enters the air inlet via an air hose (not shown) 848 is guided into the air tube 854 and enters through the various air nozzles 856 out. The air tube 854 extends substantially coaxially with the Aufla training tube 850 and a front end 854b of the air tube 854 is from the star 852 closed and kept.

For example, in comparison with the embodiments of 2 . 7 . 3A - 3D . 4A - 4 Dog 11 The concept of the inside-out gun is that the powder particles have a much shorter travel distance under the influence of the compressed air from the air nozzles 856 have, before the particles on the triboelectrically charging surface of the charging tube 850 to meet. This reduces the amount of air to achieve a sufficient impact velocity to cause sufficient charging of the powder and also reduces the amount of energy lost from the particles moving through the gun. The air tube 854 may be made of a triboelectrically charging material to further increase the triboelectrically charging effect of the construction. Another advantage of this inside-out design is that the gun is easier to manufacture because it requires fewer parts.

16 shows a modification of the inside-out pistol of 15 , In 16 has the gun 840 ' a central gun body 860 which also acts as a charging tube. The powder insert 844 ' is at an inlet attached end of the body, and a nozzle assembly 852 ' is at an opposite end of the gun body 860 attached. The nozzle arrangement 852 ' can be similar to the one in 15 shown or another suitable construction.

As well in 15 as well as 16 extends a grounding pin 862 through the gun body 842 / 860 to discharge the triboelectrically charged surfaces and components within the guns. The pencil 862 is in 16 shown, with the pin in 15 was omitted to the pin hole 862a to show.

17 shows an embodiment of the invention with a manually operated pistol configuration. Previous embodiments herein are illustrated as automatic gun configurations attached to, for example, gun retainers and gun mover mechanisms, although the major elements of those embodiments may be incorporated into a manual pistol grip, as exemplified in FIGS 17 and 18 is executed.

In 17 then includes the pistol 870 a grip section 872 that's a trigger 874 or other control means for controlling the flow of powder through the gun 870 has. A gun body 876 holds a powder feed hose connector 878 to which a powder feed hose (not shown) can be connected. The powder flows through a powder extension tube 880 which may be made of a triboelectrically charging material. The extension tube 880 gets in a gun body extension 882 held, which at one opposite end a nozzle arrangement 883 holds. The extension tube 880 is essentially concentric in the gun body 876 and the extension 882 held, leaving an annular chamber 884 is provided. This ring chamber 884 takes through an air tube connector 886 that goes up one by one through the handle 872 extending air line 886a connected, compressed air on. A diffuser air duct 888 is through the wall of the powder extension tube 880 educated. The channel 888 is dimensioned so that a desired balance between in the powder extension tube 880 entering diffuser air and through the annular chamber 884 down to the charging section 890 the gun 870 flowing air is effected.

The charging section 890 has in this example the shape of an outside-in gun and includes a charging tube 892 at one end into the front end of the powder extension tube 880 is used. The front end of the charging tube 892 is at the nozzle assembly 883 attached. The charging tube 892 gets from ribs or legs 894 kept the air from the annular chamber 884 contain or allow the air through a series of air jets 896 flows. The into the charging tube 892 Incoming air carries the powder particles, placing them on the triboelectrically charging surface 892a of the charging pipe 892 bounces, as described in the preceding embodiments. It is thought that the extension tube 880 and the nozzle assembly 882 can also be made of suitable triboelectrically charging materials to the charging effect of the gun 870 to improve. The use of the internal diffuser air duct 888 requires only a single air supply to the gun 870 for both diffuser air and air for the nozzles 896 so no need for a second air vent on the side of the gun on the section 890 consists. Although in 17 not shown, a shaft similar to the concept of the shaft 810 in 15 in the pistol configuration of the 17 be used.

The embodiment of 17 has a grounding pin 893 that with the extension 882 is connected, which is electrically conductive. The extension 882 is in turn with a grounded screw 885 connected via a grounded wire 887 is electrically grounded. The arrangement of the grounding pin 893 at a location directly behind or upstream of the location, at the triboelectrically-charging air assist nozzles 896 At first, it is preferred to impinge on the charging surface because at this point the surface charge which builds up due to the tribocharging of the powder on the triboelectrically charging surface simply passes over the grounding pin 893 can be discharged to assist the triboelectric charging of the powder. If the ground pin is located too far upstream from the point of air blast impact, surface buildup on the surface will not be dissipated from the ground pin. When the grounding pin is placed in front of or downstream of where the tribocharging air jets impinge on the charging surface, the powder charged by impingement on that surface is discharged by the grounding pin as the powder flows downstream over the grounding pin.

In a typical triboelectrically charging gun, extending the length of the gun barrel downstream of the tribocharging section tends to cause a loss of charge before the powder is expelled through the nozzle. In the 18A - D we show an alternative arrangement in which for different gun lengths the air jet induced triboelectrically charging section 890 held closer to the nozzle, so that the charge loss is minimized. In all of these embodiments, it is preferred that the grounding pin or other grounding element (not shown) be located at a location just beyond the point where the triboelectrically charged air assisted beams impinge on the charging surface first, as in the embodiment of FIGS 17 is done.

With reference to 19 Next, a spray gun incorporating the concept of an inside-out gun in a hand-held, manual spray gun configuration is illustrated. The gun 900 includes a Pisto lenkörper 902 that a grip 904 has. The handle 904 can be a conventional trigger mechanism 906 to control the flow of powder into the gun 900 include. The body 902 holds a charging tube 908 in a body extension 910 , The charging tube 908 is of a suitable triboelectrically charging material, as described above. At a rear end of the gun body 902 is a powder inlet cap assembly 912 attached in a manner similar to the embodiments of the 15 and 16 a powder hose connector 914 and an air tube connector 916 includes (the air and powder supply lines are in for clarity 19 ) Omitted. The air intake 916 is in flow communication with an air tube 918 extending longitudinally from the inlet head 912 through the gun 900 to a nozzle assembly 920 extends. In this embodiment, the nozzle assembly comprises a flat spray nozzle 922 in which a star 924 is built in, which has a similar construction as the star 852b of the 15 may have. The star 924 Holds the front end of the air tube 918 , The air tube extends substantially concentrically through the gun 900 , so that between the outer surface of the air tube 918 and the inner surface 908a of the charging pipe 908 an annular chamber 926 is provided. In a section 928 the gun 900 be through the wall of the air tube 918 a series of air jets 930 provided, which are directed to the front end of the gun near the nozzle. The number, location, orientation and angle of the various air nozzles 930 can be selected for a particular gun design as previously explained. The air nozzles 930 Not all need to be at the front end of the gun either 900 but may also be located more towards the pistol grip.

Powder passes through the fitting 914 in the gun 900 and flows in the annular chamber 926 along. A suitable dimensioning of the annular chamber 926 can be used to provide a triboelectric pre-charge of the powder before passing the section 928 the gun 900 reached. Compressed air flows from the inside of the air tube 918 out to the annular chamber 926 , whereby the impact of the powder particles on the tribocharging surface of the charging tube 908 is effected. The air tube 918 can also be constructed of triboelectrically charging material to increase the charging effect on the powder. Although the gun 9O0 is shown as a delay in the pistol Verlän 910 arranged charging tube 918 If necessary, these two elements can, as in the embodiment of the 16 to be a single pipe.

As in the previous embodiments, there is a ground pin 931 located at a location just behind the spot, at the triboelectrically charging, air assisted beams 930 first hit the charging surface. The grounding pin 931 is with the extension 910 connected, which is electrically conductive. The extension 910 is through a grounded screw 933 on a grounded wire 935 grounded.

Another advantage of the inside-out gun configurations illustrated herein is that if an impact fusion joint were to occur along portions of the charge tube surface, the air tube is a simple process 918 easy to turn at an angle sufficient to the air nozzles 930 to realign to "clean" triboelectrically charged surface areas where there is no impact fusion bond. This exposes the impacting powder particles to a clean charging surface and improves charging efficiency when using the gun. Alternatively, the relative axial position could be between the air nozzles 930 and the triboelectrically charging surfaces are adjusted so that a clean charging surface is exposed to the powder, or both the relative axial and rotational positions could be changed.

20 Figure 4 shows another embodiment of the invention combining the inside-out configuration with an outside-in configuration in a single gun. In this embodiment, the pistol includes 940 a gun body 942 , which at one end has a powder inlet cap arrangement 944 and a nozzle assembly at an opposite end 946 wearing. The nozzle arrangement 946 is shown as a conical nozzle, with a nozzle 948 from a star 950 in a similar manner as other embodiments described herein.

The inlet arrangement 944 includes a powder hose fitting 952 and an air connection piece 954 , The air connection piece 954 is in flow communication with an air tube 956 extending through the gun to the nozzle assembly 946 extends and at the front end of the star 950 is held. A charging tube 958 is also inside the gun body 942 holds and surrounds the air tube 956 concentric to a second or outer annular chamber 960 to train in between. The air tube 956 includes several inside-out air jets 957 passing the air from the inside of the air tube into the annular chamber 960 allow. The charging tube 958 is dimensioned with a diameter that is smaller than the diameter of the gun body 942 , whereby an air duct or a second outer annular chamber 962 is provided. The charging tube 958 is also with a number of air jets 964 provided so that the charging tube 958 also acts as an outside-in air tube. Compressed air flows from the second or outer ring chamber 962 through the charging tube air nozzles 964 in the first or inner ring chamber 960 , Powder from the inlet 952 flows into the inner ring chamber 960 and then gets in through the air jets 957 and 964 entrained airflow. The two sets of air nozzles, one outside-in and the other inside-out, significantly increase powder turbulence and cause impact on both the charge tube surface 958A as well as the air tube outside surface 956a , A grounding pin 966 is provided as described above.

Compressed air enters through the air connection piece 954 into the gun and flows through the air tube 956 , In addition, there is an air duct 968 provided a portion of the air in the outer annular chamber 962 passes. In this way, only a single air inlet is needed in the gun. If necessary, part of the air can also enter the inner ring chamber 960 however, it is unlikely to be needed as the volume of moving air from all the air jets will in most cases sufficiently atomize the powder. The gun 940 may also include additional powder flow lengths prior to the charging process to integrate a triboelectric precharge or recharge effect.

The 21 - 24 show a further embodiment of the invention. In this embodiment carries an electrically conductive extension 972 a nozzle 974 with a slot 976 , A boot 978 is between the nozzle 974 and a charging sleeve holder 980 built-in. The powder feed tube 982 gets into the charging sleeve holder 980 used and is connected to a powder feed hose 984 connected. A grounding pin 986 is with the extension 972 connected. The extension 972 is over a grounded screw 988 with a grounding wire 990 connected. The boot sleeve holder 980 includes air nozzles 981 which improve the triboelectric charging ability of the gun. The nozzles 981 apply the inner surface 979 the boot 978 which is constructed of a triboelectrically charging material such as that described above. The grounding pin 986 is positioned directly behind the point where the triboelectrically charging, air assisted beams 981 on the charging surface 979 incident.

The 22 and 23 show the charging sleeve holder 980 in greater detail. As in 23 shown are the air nozzles 981 at 90 degree intervals around the circumference of the charge tube holder 980 arranged around. The passage 992 for the grounding pin 986 is in 23 as between two of the air jets 981 shown arranged.

24 shows a view of the with the charging sleeve holder 980 assembled boot. In the holder 980 a dowel pin is frictionally received. When the charging sleeve 978 with the bracket 980 is assembled, the dowel pin 996 in one in the outer surface of the sleeve 978 trained slot 994 added. This allows the sleeve 978 a certain local orientation in the holder 980 assume (hereinafter referred to as a first orientation). In this first orientation becomes a certain part of the inner surface 979 the sleeve 978 from the air nozzles 981 charged and worn by the friction charging of the powder. To different parts of the inner surface 979 the air nozzles 981 to suspend is a number of such slots on the outside of the sleeve 978 educated. To realign the sleeve in the holder 980 in another local orientation, the sleeve would 978 from the holder 980 pulled and turned to another on the outside of the sleeve 978 trained slot with the pin 996 align, and the sleeve 978 then back into the holder 980 be pushed. That way, a new part of the charging area would be 979 from the air nozzles 981 to charge for the friction or triboelectrical charging of the powder without the need to replace the charging sleeve 978 to be used. In addition, the sleeve 978 symmetrical, so that their orientation in the holder 90 can be reversed, with the opposite end of the sleeve 978 in the holder 980 is used. This doubles the number of different orientations that the sleeve has in the holder 980 to provide an even larger portion of the area for the triboelectric charging application before the sleeve 978 must be replaced.

consequently One of the advantages of this embodiment is the application of a new concept of construction of one or more components the pistol in a tribo-charging gun, called as a triboelectrically charging surface is used to enter the Pistol to be installed in more than one orientation, so that more of the surface for triboelectric charging of the powder can be used before the component is replaced by a new component. This saves money to the customer by allowing the customer to still use the component to exploit more before replacing it.

A further cost saving is provided to the customer in that the triboelectrically charging assembly is formed in two parts as a charging sleeve and a charging sleeve holder. By constructing these components as a two-piece arrangement, it is not necessary to replace only the charging sleeve holder which comprises the air nozzles and is more complicated to manufacture. Thus, the charge tube 978 a much easier to manufacture and replace part than a boot, like the one in 17 shown, which includes both the air nozzles and the charging surface.

It should also be noted that in the embodiment of the 21 - 24 all air nozzles 981 lie in a single vertical plane. This leads to a number of advantages. The charging sleeve may be shorter than the charging sleeves with air nozzle sets provided over the length of the charging sleeve. In addition, any air introduced from the rear of the gun will be delivered evenly to all air jets, resulting in more even charging of the powder. Furthermore, all powder impingement areas in the sleeve are near the grounding pin. In addition, lower pressure can be used for air nozzles in a single plane, which reduces energy requirements because there is no pressure drop between the first set of air nozzles and the second set of air nozzles.

According to one another aspect of the invention then different combinations of air jet assisted triboelectric Charging and triboelectric charging techniques into a spray gun to get integrated. These include but are not necessarily limited to: air jet assisted triboelectric charging followed by triboelectric charging; triboelectric charging followed by air jet assisted triboelectric Charge; an inside-out air-assisted triboelectric charging followed by triboelectric charging; triboelectric charging followed by an inside-out air-jet assisted triboelectric Charge; Inside-out air-assisted triboelectric charging followed by an outside-on-air assisted triboelectric Charge; and inside-out air-jet assisted triboelectric Charging combined with outside-in-the-air assisted triboelectric charging. It can as required also various triboelectrically charging material combinations used in a pistol, including positively and negatively boosting Materials. A significant advantage of the air jet assisted triboelectric charging pistols is that their short length makes them for coating the insides of pipes and other enclosed surfaces makes it suitable. The short gun length allows the pistol to move through a pipe, even if there are bends of different angles has that for prior art spray guns of considerable length are difficult.

Even though the invention with reference to a preferred embodiment should be understood by those skilled in the art, that different changes can be made and equivalents can replace their elements. additionally can many modifications done be to teach a particular situation or material to the lessons to adapt the invention. Therefore, it is intended that the invention not on the specific embodiment is limited, as the best way to execution This invention is disclosed, but that the invention all within the scope of the attached claims falling embodiments includes.

Claims (7)

Contraption ( 200 . 400 . 600 . 200 ' . 200 ' . 840 . 840 ' . 870 . 900 . 940 . 970 ) for spraying powder coating material having a powder flow path, the powder flow path having a charging surface (US Pat. 412 . 414 . 858 . 892a . 908a . 979 ) for triboelectrically charging the powder coating material in contact with the charging surface ( 412 . 414 . 858 . 892a . 908a . 979 ), characterized in that the device further comprises an air flow path which, like the charging surface ( 412 . 414 . 858 . 892a . 908a . 979 ) and spaced therefrom, wherein the air flow path through a wall ( 222 . 650 . 806 . 822 . 854 . 892 . 918 . 956 . 958 . 980 ), one or more, through the wall ( 222 . 650 . 806 . 822 . 854 . 892 . 918 . 956 . 958 . 980 ) formed through air channels ( 240 . 430 . 652 . 240 ' . 856 . 896 . 930 . 957 . 964 . 981 ), wherein the air channels ( 240 . 430 . 652 . 240 ' . 856 . 896 . 930 . 957 . 964 . 981 ) are in fluid communication with a compressed air source. Contraption ( 200 . 400 . 600 . 200 ' . 200 ' . 840 . 840 ' . 870 . 900 . 940 . 970 ) according to claim 1, wherein the air flow path through a tubular wall ( 854 . 918 . 956 ) which is concentric in a larger tube ( 850 . 908 . 958 ), which is the charging surface ( 412 . 414 . 858 . 892a . 908a . 979 ). Contraption ( 200 . 400 . 600 . 200 ' . 200 ' . 840 . 840 ' . 870 . 900 . 940 ,, 970) according to claim 2, comprising by the charging surface ( 412 . 414 . 858 . 892a . 908a . 979 ) formed outside air passages ( 964 ). Contraption ( 200 . 400 . 600 . 200 ' . 200 ' . 840 . 840 ' . 870 . 900 . 940 . 970 ) according to claim 1, wherein the air flow path wall ( 222 . 650 . 806 . 822 . 892 . 958 . 980 ) includes an outer surface that triboelectrically charges the powder coating material impinging on the outer surface. Spray device according to one of the preceding claims, in which the charging surface ( 412 . 414 . 858 . 892a . 908a . 979 ) comprises a negative triboelectrically charging material selected from the group consisting of polyamide resin blends, fiber reinforced polyamides, aminoplast resins and acetal polymers. Spray device according to one of the preceding claims, also comprising one next to the charging surface ( 412 . 414 . 858 . 892a . 908a . 979 ) provided electrical conductor, wherein the electrical conductor is connected either electrically to ground or to a source of electrical potential. Contraption ( 200 . 400 . 600 . 200 ' . 200 ' . 840 . 840 ' . 870 . 900 . 940 . 970 ) according to one of the preceding claims, comprising a body ( 860 . 908 ), which forms part of a spray gun, wherein the charging surface ( 412 . 414 . 858 . 892a . 908a . 979 ) is partially formed by the gun body.