KR20030022858A - Unipolarity powder coating systems including improved tribocharging and corona guns - Google Patents

Abstract

A number of new cathodic friction filling materials for use as powder contact surfaces in friction filling and corona powder spray guns, gun elements and powder delivery system elements are described. The present invention provides a short barrel friction filled powder spray gun having interchangeable powder contact inserts and nozzles with turbulent guided air jets. The present invention further provides new friction filling and corona gun designs. Improved powder coating systems are manufacturable, where negative friction filled guns can be used with negative corona guns, for example, to coat other portions of the same workpiece in a powder coating system. In addition, an inside-out configuration is provided in which pressurized air directs the powder coating material outward toward the fill surface. Further configurations provide air jet induced friction filling and conventional friction filling portions combined in a single gun.

Description

Unipolarity powder coating systems including improved tribocharging and corona guns}

There are two basic types of powder spray guns commonly used in the electrostatic powder spray coating of articles. The most common type of spray gun is the corona type, which has a high voltage charge electrode that manufactures the corona to fill the powder. Typically, corona guns are designed to fill the powder with a cathode. One major drawback of corona guns is that they do not coat well the inner edges of the parts due to the Faraday caging effect or strong electrostatic field generated by the corona electrode. A second disadvantage of corona guns is that back ionization can occur due to the formation of free ions in which the orange peel surface or pinholing of the portion to be coated occurs. Other disadvantages of this type of guns include system elements such as nozzles, powder delivery system elements such as pumps, as well as diffusers, hoppers, and other parts in contact with the powder delivery system, such as polyethylene or polytetrafluoroethylene (PTFE). It is made of the same conventional material. The materials have the advantage of low impact fusion, but have the disadvantage of filling the powder positively, which can damage the negative corona filling process since the final or maximum filling of the powder is reduced. In addition, higher voltages are often needed to neutralize the positive charge of the system. In addition, this anodic friction filling can break powder transport elements such as hoses connecting the pump to the spray gun.

A second type of gun commonly used is a friction filling gun in which powder is filled by frictional contact with the inner surface of the gun. One advantage of triboelectric guns is that the gun does not generate as strong an electric field as the corona gun does, so it can easily penetrate the edges of the parts where the powder is coated.

The present invention relates to a powder coating system using corona and friction filled powder spray guns to apply an electrostatic charge to powder for deposition on a substrate.

1 is a cross-sectional view of a friction filling gun incorporating new materials of the present invention.

2 is a cross-sectional view of a novel short barrel friction filling gun of the present invention.

3A-3D show a portion of the insert of the gun of FIG. 2 in which airjets are arranged in several opposing configurations.

4A is a cross-sectional view of the insert of the short barrel friction filling gun of FIG. 2, viewed from the spot, with the air jets not vertically offset from each other;

4B-4E are cross-sectional views of the insert of the short barrel friction filling gun of FIG. 2, viewed from the spot, where the air jets are vertically offset from each other by a vertical distance (H).

5A and 5B show cross-sections of the inserts of the short barrel friction filling gun of FIG. 2, respectively, as seen from the spot, with the first set of air jets shown in FIG. 5A being the second set of downstream air shown in FIG. 5B. Not rotationally offset from the jets.

5e to 5f show cross-sectional views of the insert of the short barrel friction filling gun of FIG. 2, respectively, as seen from the blemish, wherein the first set of air jets shown in FIGS. 5c and 5e are shown in FIGS. 5d and 5f. A rotationally offset from a second set of downstream airjets.

5G-5H show cross-sectional views of the insert of the short barrel friction filling gun of FIG. 2, respectively, as seen from the blemish, with the first set of air jets shown in FIG. 5G being the single downstream air jets shown in FIG. 5H. Not rotationally offset from the drawing.

6 is a cross-sectional view of a corona gun incorporating the new material of the present invention.

7 is a cross sectional view of a flat spray nozzle incorporating the new material and one or more air jets of the present invention.

8 is a cross-sectional view of a powder pump of a powder coating system incorporating new materials of the present invention.

9 is a schematic perspective view of a powder coating system comprising a corona and friction filling gun filling powder with the same polarity.

10 is a cross-sectional view of another embodiment of a friction filling gun of the present invention incorporating air jets.

10A is a cross-sectional view along the direction of 10A-10A of the gun shown in FIG.

11 is a cross-sectional view of another embodiment of a friction filling gun of the present invention incorporating air jets arranged in a spiral pattern.

11A is a cross-sectional view along the direction of 11A-11A of the gun shown in FIG. 10.

12 is a cross-sectional view of another embodiment of a friction filling gun using air jets.

FIG. 13 is a cross sectional view of a modified version of the gun of FIG. 12 with a portion of the air jets and a post fill of friction charging; FIG.

FIG. 14 is another cross-sectional view of a modified version of the gun of FIG. 12, with the precharge section having air jets along the friction charge section.

15 and 16 are cross-sectional views of two embodiments of an inside-out gun in accordance with the present invention.

FIG. 17 illustrates an embodiment of an airjet inductive charge gun in a conventional manual spray gun configuration.

18A-18D illustrate another embodiment of the gun style of FIG. 17 using different extension lengths.

FIG. 19 shows an inside-out gun of the manual gun configuration. FIG.

20 illustrates a spray gun incorporating an inside-out configuration with an outside-in configuration.

21 to 24 illustrate another embodiment of the present invention.

The present invention provides new electrostatic powder coating guns and system components in which the powder is precharged with the same polarity as the charge applied by the powder spray gun to increase and improve the applied charge and transfer efficiency.

An apparatus for spraying a powder coating material according to one aspect of the present invention is described. The apparatus has a powder flow path, wherein the powder flow path has a filling surface for triboelectrically filling the powder coating material in contact with the filling surface, the filling surface comprising a polyamide resin mixture, a fiber reinforced poly Negative electrode friction filling material selected from amides, aminoplastic resins and acetal polymers.

According to another aspect of the present invention, an apparatus for spraying a powder coating material has a powder flow path, wherein the powder flow path has a filling surface for filling the powder coating material with triboelectricity in contact with the filling surface. And at least one air passage formed through the filling surface, wherein the air passage is in fluid communication with a source of compressed air.

An apparatus for spraying a powder coating material according to another aspect of the present invention is described. The apparatus has a powder flow path through which the powder coating material flows, the powder flow path having a first filling surface for triboelectrically charging the powder coating material in contact with the first filling surface, The first filling surface contains a friction filling material having a first filling polarity, the apparatus further comprising an element through which the powder coating material flows, the element comprising a friction filling material having the first filling polarity. It is provided with a 2nd charging surface comprised.

A system for applying powder coating materials to articles according to another aspect of the present invention is described. The system includes a powder supply device for supplying a powder coating material and a device for spraying the powder coating material received from the supply device, the spray device comprising an electrode for filling the powder coating material with a first charging polarity. And the supply device includes an element having a charging surface for triboelectrically charging a powder coating material in contact with the charging surface, the charging surface containing a friction filling material having the first charging polarity. .

A system for applying powder coating materials to articles according to another aspect of the present invention is described. The system includes at least one corona-filled spray device and at least one friction-filled spray device, the corona-filled spray device having an electrode for filling the powder coating material with a first charge polarity, the friction-filled spray device The apparatus has a powder flow path, the powder flow path having a filling surface for triboelectrically filling the powder coating material in contact with the filling surface, wherein the powder coating material is the filling surface of the powder filling spray apparatus. Is charged to the first polarity.

A friction filled powder spray device according to another aspect of the present invention is described. The apparatus includes a body having an inner hole, a wear tube located within the inner hole, an open passage provided between the inner hole and the wear tube, and at least one air jet passage provided through the wear tube. The air jet passage provides fluid communication between the open passage and the interior of the wear tube. The wear tube has a filling surface for filling triboelectrically charged powder coating material in contact with the filling surface. The open passage is in fluid communication with a source of compressed air whereby compressed air flows from the open passage through the air jet passage into the wear tube to affect powder coating material through the wear tube. .

A system for applying powder coating materials to articles according to another aspect of the present invention is described. The system includes a powder supply device for supplying a powder coating material and a device for spraying the powder coating material received from the supply device. The supply device includes an element having a charging surface for triboelectrically charging the powder coating material in contact with the charging surface. The urea-filled side contains a negative electrode friction filling material selected from polyamide resin mixtures, fiber reinforced polyamides, aminoplastic resins and acetal polymers.

A triboelectric powder coating gun having an element comprising a triboelectric charging surface according to another aspect of the invention is described, wherein the element can be assembled into the gun in at least two different position orientations. Still another aspect of the present invention provides a triboelectric powder coating gun having a triboelectric charging surface and an air jet impinging the charging surface, the gun further comprising a ground member disposed upstream of the charging surface. Include.

The following detailed description of the preferred and other embodiments is divided into the following sections. Section (I) describes in detail a new friction filling gun which fills a negative electrode with powder by frictional contact with materials of the new use described in more detail below. Section (II) details a new short barrel friction filling gun capable of filling the powder with an anode or a cathode depending on the material selected for frictional contact with the friction filling side of the gun. Sections (III, IV) are corona guns and powders having corona guns and systems including elements that fill the powders with the same polarity as the corona guns by friction contacting the powders with the frictionally charged surfaces consisting of the desired positive or negative friction filling materials. Relates to a supply system. Section V describes in detail a powder coating system comprising corona and friction filling guns that fill the powder with the same polarity so that the friction filling gun can be used in conjunction with a corona gun to coat the same workpiece. Finally, section VI details another friction filling gun embodiment using air jets.

I. Negative friction filling gun made of unique materials

A. Original Negative Charge Friction Materials

Part of the invention has been found to be described as "original negatively charged friction material." These materials are useful as powder contacts to the negatively charged powder coating material by frictional contact with the powder contacts of the powder spray gun. The term "negative charging tribomaterials" refers to materials that impart a negative charge to a powder, such as powdered paint, when frictionally colliding with the surface of the negatively charged friction materials.

As described in more detail in this application, the original negative charge friction materials are described in more detail in section (IV), powder delivery system elements and spray gun elements such as diffusers, powder tubes, feed hoppers and pumps. In addition, it can be used as the inner surface of the friction filling or corona powder spray gun. Although inventive negatively charged friction materials are generally known, they are not already known to be useful in spray guns for filling powder coating materials.

Original negative charge friction materials are selected from polyamide mixtures, fiber reinforced polyamide resins, aminoplastic resins, acetal polymers or mixtures thereof and are described in more detail below. These materials not only fill negatively well, but also do not experience as severe impact melting problems as the negative friction filling materials used in the past, such as nylon.

1. Polyamide Mixture

The polyamide mixture contains a mixture of a polyamide polymer and a second polymer selected from the group consisting of polyethylene, polypropylene, halogenated hydrocarbon resins and mixtures thereof. The polyamide polymer is preferably provided in the polyamide mixture of 50% to 96% by weight, more preferably 70% to 90% by weight. The second polymer is preferably about 4 wt% to about 50 wt%, more preferably about 10 wt% to about 30 wt%, most preferably about 15 wt% to about 25 wt% polyamide Provided in the mixture.

Halogenated hydrocarbon resins preferably include, for example, pletetrafluoroethylene (known as PTFE); Copolymers of tetrafluoroethylene and hexafluoroethylene (known as FEP); Fluorinated hydrocarbon resins such as copolymers of tetrafluoroethylene and perfluorinated vinyl ethers (known as PFAs). Suitable fluororesins are trademarks of DuPont It can be purchased commercially.

The polyamide polymer of the polyamide mixture is preferably nylon. Good grades of nylon are nylon 6/6, nylon 6/12, nylon 4/6 and nylon 11. Suitable polyamide mixtures are 80% nylon 6/6 and 20% polytetrafluoroethylene, commercially available under the trademark RL 4040 from LNP Engineering Plastics, Division of ICI Advanced Materials Exton Pennsylvania. Suitable mixtures are about 95% nylon 6/6 and about 5% polytetrafluoroethylene, commercially available under the trademark RL 4010 from Division of ICI Advanced Materials, LNP Engineering Plastics, Exton, Pennsylvania, USA to be.

View 1

Separate discs of 20% polytetrafluoroethylene and 80% nylon 6/6, polyamide / halogenated hydrocarbon resin mixtures were prepared. For comparison, coupons of conventional materials, nylon and Teflon, were prepared.

The relative transfer efficiency was determined by spraying the powder at an air flow rate of 4 cubic feet per minute onto the disc at an angle of 45 degrees in a flat spray nozzle having a slot of 11.43 mm x 1.65 mm. The powder collided with the surface of the disk of friction filling material and was diffracted from the disk to a grounded metal target. The powder exiting the nozzle has a measurement initial charge of zero. Thus, all powder charges are due to collision with the friction material. The amount of powder attached to the target is defined as the relative transfer efficiency compared to the total powder sprayed. Typically 50 grams of polyester epoxy powder from Ferro Corporation was the powder used for the test. The relative transfer efficiency test is done with a single impact from the coupon, the values of which tend to be lower than the various contacts using the friction filling gun.

The powder used for the evaluation was a polyester epoxy powder indicated by 153W-121 of Ferro Corporation. The results are shown in Table 1 below.

View 2

Individual discs of 5% PTFE, 95% nylon 6/6, and polyamide mixtures were prepared and the transfer efficiency was evaluated as shown in Example 1. The results are shown in Table 1 below.

The advantage of using polyamide mixtures in powder spray guns is to increase powder filling due to increased discharge of friction filled gun surfaces. The increased surface discharge is due to the incompatible polymer provided for the leakage paths that do not appear in the homogeneous polymer. Another advantage of using these polyamide mixtures is that when the polyamide mixtures are filled with PTFE or polyethylene, the moisture absorption of the nylons is reduced.

2. Fiber Reinforced Polyamide Resin

Fiber reinforced polyamide resins include polyamide polymers filled with polyaramid fibers. Preferably, there is about 50% to about 99%, more preferably about 85% to about 95% polyamide polymer. Preferably, about 1% to about 50%, more preferably, about 5% to about 15% of the polyaramid fibers are in the polyamide polymer.

The polyamide polymer of the fiber reinforced polyamide resin is preferably a commercially available polyamide polymer. Suitable polyamides are, for example, nylon.

Polyaramid fibers are a long series of synthetic aromatic polyamides in which at least 85% of amide bonds are attached directly to two directional rings. Suitable polyaramid fiber is a trademark of DuPont Commercially available poly (p-phenylene terephthalamide). Polyaramid fibers, poly (m-phenylene, terephthalamide), commercially available under the DuPont trademark Nomex, are less preferred. Examples of other polyaramid fibers are polymers comprising a polymerization unit of p-aminobenziridide and terephthaloyl chloride; Suitable such polymers are commercially available from Monsanto under the trademark PABH-TX-500.

Suitable fiber reinforced polyamide resins are 10% of 90% nylon 6,6 commercially available under the trademark Lubricon RA of Division of ICI Advanced Materials, LNP Engineering Plastics, Exton, Pennsylvania, USA to be.

View 3

Individual discs of fiber reinforced polyamide resin were prepared. For comparison, conventional coupons, nonfiber receptive nylon and teflon were also prepared. Relative transmission efficiency was determined as in Example 1. The results are shown in Table 1 below.

TABLE 1

surprisingly, Tow fiber adds a positively charged powder to the powder in a comparative example, and the fiber is added to the nylon to negatively charge at increased relative transfer efficiency.

3. Aminoplastic Resins

Aminoplastic resins consist of polymerized units of amine monomers and aldehyde monomers. Preferred aminoplastic resins are aniline formaldehyde resins, urea formaldehyde resins and melamine formaldehyde resins. Optionally, the aminoplastic resins further comprise cellulose such as alpha-cellulose and pigments.

Suitable molding grade melamine formaldehyde resins filled with alpha cellulose are commercially available under the trademark Perstorp 752026 white melamine or Perstorp 775270 red melamine available from Perstop Compound Inc., Florence, Massachusetts. Another suitable melamine resin is a melamine phenol-formaldehyde copolymer commercially available under the trademark Plenco 00732 from the Plenco Plastics Engineering Company, Sheboygan, Wisconsin.

Another suitable melamine resin is Perstorp 752-046 melamine formaldehyde polymer available from Perstop Compound Inc., Florence, Massachusetts.

Example 4

Separate discs of white melamine formaldehyde resin, Perstorp 752026, filled with alpha cellulose were prepared. For comparison, discs of conventional nylon 6/6 were also prepared. Relative transmission efficiency was determined as in Example 1. The results are shown in Table 2 below.

Example 5

Separate discs of red peppercorn melamine formaldehyde resin, Perstorp 775270, filled with alpha cellulose were prepared. For comparison, discs of conventional nylon were also prepared. Relative transmission efficiency was determined as in Example 1. The results are shown in Table 2 below.

Example 6

Individual discs of melamine phenol-formaldehyde resin, Plenco 00732, were prepared. For comparison, discs of conventional nylon were also prepared. Relative transmission efficiency was determined as in Example 1. The results are shown in Table 2 below.

Example 7

Separate discs of white melamine phenol-formaldehyde resin, Perstorp 752-046, were prepared. For comparison, discs of conventional nylon were also prepared. Relative transmission efficiency was determined as in Example 1. The results are shown in Table 2 below.

Table 2. Relative Transfer Efficiency of FERRO 153W-121 in Contact with Amino Resin Coupons

Example 8 to 10

As shown in FIG. 2 and described in section (II), a short barrel friction filling gun is produced, in which the inner surface of the gun, in particular the inner surface of the powder conduit insert and the flat spray nozzle, are a stopstop compound of the USA, Massachusetts, Florence. Red peppercorn melamine formaldehyde, designated Perstorp 775270, is prepared from Inc .. The gun used for the test had two pairs of air jets and two electrodes. The airjets were offset by one jet diameter from the centerline perpendicular to the longitudinal axis and the second set of airjets rotated 5 degrees relative to the longitudinal axis from the first set of airjets. The angle of the air jets was 90 degrees.

Relative transfer efficiency was determined by spraying a set of powder at the target and moving perpendicular to the spray gun at a speed of 10 feet per minute. The powder of the spray gun was an epoxy polyester powder labeled 153W-121 from Ferro Corporation. The results are shown in Table 3 below.

TABLE 3

4. Acetal Resins

Acetal resins are polyoxymethylene engineering thermoplastic polymers. Acetal resins are homopolymers or copolymers. Acetal resins optionally bind with polytetrafluoroethylene, polytetrafluoroethylene fibers and polyethylene or other polymers or additives. Suitable acetal homopolymers are E.I. Wilmington, Delaware. DuPont de Nemours & Co. Trademarks Can be purchased commercially. Suitable examples are acetal homopolymer resins composed of 20% Teflon PTFE fibers and are commercially available under the trademark Delrin AF. One advantage of this material is that the electric shock from the storage capacitance applied to the worker handling the gun is smaller than the other materials tested.

Suitable modified copolymers are available from BASF Corporation, Parsippany, NJ, USA Acetal copolymer modified with very high molecular weight polyethylene (UHMWPE) commercially available as N2380X. Other suitable acetal copolymers are trademarks of Zust Celanese Corporation, Chatham, NJ.Can be purchased commercially.

Example 11

As shown in FIG. 2 and described in section (II), a short barrel friction filling gun was produced in which the inner surface of the gun, in particular the inner surface of the insert, was made from the acetal polymer of Delrin 150 from DuPont.

The powder of the spray gun is an epoxy polyester powder indicated as 153W-121 from Ferro Corporation or a polyester / urethane powder indicated as 153W-281 from Ferro Corporation. The transmission efficiency was determined as in Examples 8-10. The results are described below.

The transfer efficiency is about 62% for both powders as shown in Table 4 below with a flow rate of 2.5 g / s.

TABLE 4

One advantage of the acetal resins is that they can be injection molded, thus producing low cost powder spray guns. Delrin acetal resins for relative transfer efficiency do not contain nitrogen atoms typically found in negatively charged materials such as nylon and melamine, resulting in surprising and unexpected results. It has been found that providing PTFE fibers to Delrin acetal resins, such as Delrin AF acetal resins, results in increased transfer efficiency for Delrin acetal resins.

B. Negative Friction Filling Gun with Original Materials

1 is a friction filled powder spray gun 10 for use with the apparatus and method of the present invention. This gun 10 includes a gun body 12 having a through center opening. Gun 10 may be supported by a suitable gun installation assembly known to those skilled in the art. The gun 10 includes a powder supply 20, a friction filling 30, and a sprayhead portion 40 at the outlet end of the gun.

The friction filling section 30 of the gun includes an inner core 34 disposed in the outer cylinder 32, in which the surfaces 34a and 32a provide an annular filling path for the powder flowing through the filling path of the gun. Cooperate to provide. As shown in FIG. 1, the surfaces 34a and 32a comprise wave surfaces or corrugated surfaces, so that the annular gap provides a twisted path for the powder, thereby allowing the powder 34 to be charged. ) And powder contact.

In a preferred embodiment of the invention, some or all of the powder contact surfaces of the gun are polyamide mixtures, fiber reinforced polyamide resins, acetal polymers, acetal polymer homopolymers, preferably PTFE fibers (hereinafter collectively described as acetyl polymers). ) And a material selected from the group consisting of copolymers, aminoplastic resins or mixtures thereof. These are the original negative charge friction materials of the present invention that have been found to be well charged. Thus, the powder contact surface may be coated with the material described above, or each element having the powder contact surface may be composed in whole or in part from the materials described above. Thus, as shown in FIG. 1, the powder contact surfaces, the inner core 34 and the nozzle 40 of the outer cylinder 32 may be a polyamide mixture, a fiber reinforced polyamide resin, an acetal polymer, an aminoplastic resin or mixtures thereof. It may contain. In addition, the powder contact surfaces of the inner wear sleeve 38, the outer wear sleeve 40, the inner wear sleeve 41, the inlet dispenser 36, the outlet dispenser 37 and the outlet wear sleeve 42 are made of polyamide mixture, fibers It can be made entirely or coated with a material selected from the group consisting of reinforced polyamide resins, acetal polymers, aminoplastic resins or mixtures thereof. Other powder contact surfaces not described herein may also contain the materials described above.

Ground electrodes 43, discharge rings or other means known to those skilled in the art can be utilized to discharge the powder contact surfaces of the outer cylinder and inner core in the manufacture of electric charge. The ground electrode or discharge ring may be placed at any location known to those skilled in the art.

As shown in FIG. 1, powder and conveying air are provided to a powder supply 20. The powder enters the filling section of the gun from the supply section 20 and moves into an annular filling path located between the inner core 34 and the outer cylinder 32. Since the air with powder repeatedly contacts the powder contact surfaces 32a and 34a of the outer cylinder 32 and the inner core 34, the powder is negatively charged. As a result, the frictionally charged powder is discharged into the sprayhead portion 40 of the gun. In the original cathodic filling, friction materials are used and the powder is filled with the cathode, but the gun does not undergo impact dissolution of the powder which is not acceptable on the filling side.

II. Spray gun with short barrel friction filled powder consisting of new bipolar or negative friction filled materials

As shown in FIG. 2, the short barrel friction filling gun 200 of the present invention provides a novel powder spray gun of relatively simple construction and small size to fill powder by a friction filling process. The present invention has the advantage of removable insert 220, which can be easily changed for quick color change of the powder. One important advantage over short barrel triboguns is that they do not have the disadvantages of strong electric field or bag ionization problems present in corona guns. The gun, described in more detail below, can fill the powder with an anode or a cathode. In general, the triboelectric powder filling gun, denoted by the symbol "200", has an overall length in the range of about 25.4 mm to 254 mm from the powder inlet to the nozzle tip, more preferably prior art friction, typically between 355.6 mm and 914.4 mm in length. It has a total length in the range of 25.4 mm to 152.4 mm substantially smaller than the total length of the filling gun.

The main elements of the gun are the body 210, the powder conduit insert 220 installed on the body 210 and the nozzle 230 attached to or installed in the body 210. Insert 220 and nozzle 230 together form a barrel of the gun. Body 210 may be made of any structurally suitable material. Body 210 has an input end 212 with an opening suitable for receiving insert 220 and an output end 214 suitable for receiving or connecting to nozzle 230. For manual use, a handle or pistol grip (not shown) may be formed or attached as an integral part of the body 210.

The powder conduit insert 220 is preferably a cylindrical tube with an inner powder passageway 222. The inner diameter of the powder passageway 222 may preferably be in the range of about 6.4 mm to about 38.1 mm, most preferably 12.7 mm.

The insert 220 is preferably removable or releasably connected to the body in a conventional manner. For the negative gun, the insert 220 is made of a material selected from polyamide, preferably a nylon 6/6, polyamide mixture, fiber reinforced polyamide resin, acetal polymer, aminoplastic resin or mixtures thereof or It is desirable to have an inner surface 222 coated with these materials. For bipolar filling guns, insert 220 may be formed of a fluoropolymer, in particular a material such as polytetrafluoroethylene or mixtures thereof, or an inner surface coated entirely with or coated with friction materials. It can be provided. Therefore, depending on the type of friction filling material selected, when contacted with the inner powder contact surface of the insert 220, a cathode charge or an anode charge is imparted to the powder particles.

The spray gun 200 may further include one or more air jets 240 provided in the inner passages 222, 234 of the gun. The air jet 240 is positioned within the insert 220 or nozzle 230 to act to create turbulence when the frictional contact of the powder with the wall 222 or nozzle 230 of the insert 220 increases. Air or other fluid (described below as air) may be used to direct the air jet 240 through an air passage 250 formed in the body 210, which guides the chamber 252 to an insert 220 or nozzle (not shown). Is supplied. One or more air jets 240 are guided from chamber 252 to powder passages 222 and 234 of insert 220 or nozzle 230 (not shown).

Air jet 240 may include any orifice shape, such as round, rectangular, square or oval. The cross-sectional area of each air jet may be in the range of about 0.025 mm ² to about 0.76 mm ² (diameter corresponding to a round hole size of about 0.76 mm to about 5.08 mm). More preferably, each airjet cross sectional area may range from about 0.76 to about 0.127 mm ² (corresponding to a round hole size diameter of about 1.52 to about 2.032 mm). Most preferably, the airjet cross sectional area may be about 0.097 mm ² , corresponding to a round hole size diameter of about 1.78 mm.

As shown in FIG. 2, the airjets 240 are in the interior passage 222 in the range of about 0 degrees to about 90 degrees, preferably in the range of about 45 degrees to about 90 degrees, more preferably, about 60 degrees. An angle Θ is formed with respect to the insert or nozzle side wall or longitudinal axis.

Air jets may be arranged in one or more groups of air jets having the same diameter or different diameters. One group may be two or more airjets that may be arranged in opposing or non-opposing configurations. 3A-3D show another configuration of the arrangement of the upper and lower airjets 240 of the insert 220. 3A shows the upper and lower air jets 240 where the air flow from the jets intersects on the longitudinal axis (or center line CL). Both upper and lower airjets form an angle of 45 degrees with the insert sidewall 222. FIG. 3B is substantially the same configuration as FIG. 3A except that the center of the upper air jet is offset longitudinally from the center of the lower air jet so that air flow from the air jets crosses at a point offset from the longitudinal axis. 3C shows that it may have another airjet angle that results in a flow of airjets intersecting at points offset from the longitudinal axis. 3D shows that the upper and lower airjets may have different angles that are offset in the longitudinal axis and generate a flow of jets intersecting at the longitudinal axis.

If two or more air jets are used, one air jet may be offset by a distance H perpendicular to the longitudinal axis, as shown in FIGS. 4B-4E with respect to the other air jet. Thus, in FIGS. 4B-4E, the air jets are vertically offset from each other by varying the vertical distance H with respect to the longitudinal axis. The distance H can vary from zero (not offset) to the diameter of the insert shown in FIG. 4E, as shown in FIG. 4A.

As shown in FIGS. 5A-5H, if using more than one group of air jets, a group of air jets are angled clockwise or counterclockwise around the longitudinal axis for the first group of air jets. Can be rotated. It is preferred that the air jets of the lower group rotate at an angle clockwise or counterclockwise in the range of about 0 degrees to about 90 degrees relative to the first group. 5A, 5C, 5E and 5G respectively show the first or upper group of air jets located within the insert 220 of FIG. 5B, 5D, 5F and 5H show 0 degrees, 45 degrees, 90 degrees and 0 degrees counterclockwise for the corresponding first set of air jets of FIGS. 5A, 5C, 5E and 5G. The rotating second or lower group of air jets are respectively shown. 5H shows that the second group of air jets need only one air jet.

The total air flowing to the four air jet orifices 240 of FIG. 2 may range from about 0.3 cubic feet per minute to about 6.5 cubic feet / minute. If two pairs of air jets are used, the overall air flow rate of the air jets is preferably 4.2 CFM. Air jet orifices 240 typically have a speed in the range of about 100 to about 1000 feet / second, more preferably in the range of about 400 to about 800 feet / second and most preferably in the range of about 655 feet / second. . These variables can be accumulated appropriately for tubes of different diameters.

One or more electrodes 260 known to those skilled in the art, wherein the internal charge gun 200 serves to discharge the frictional charge surfaces 222, 234 due to the generation of charge as a result of frictional contact with the powder. Or other means. For example, the electrode can be a conductive pin, a compressed solid metal ring, an air washed porous ring, or a metal strip located along the longitudinal axis in the filling tube. At least one electrode is preferably electrically grounded. However, electrode 260 may be charged to a positive or negative electric potential, preferably in the range of about 0 to about 10 kilovolts (Kv), as shown in FIG. 2. The electrode 260 may be disposed inside the insert 220 or the nozzle 230, but the electrode is preferably disposed on top of the air jets. One or more electrodes 260 may be air washed. That is, air flow is provided from the chamber 250 through the passages 262 and 264 to blow off and blow away the powder of the electrode 260.

Although other prior art nozzles may also work with the present invention, a flat spray nozzle 230 is shown in FIG. 2 in combination with the present invention. The nozzle 230 generally has a slot 232 that produces a flat spray pattern and an inner passage 234 in fluid communication with the inner passage 222 of the insert 220. It is preferred that the nozzle 230 is removable or releasably connected to the gun body 210 by any conventional method. Since the nozzle has a large powder contact area for the negative friction filling gun, the nozzle 230 may be made of polyamide, in particular nylon 6/6, polyamide mixtures, fiber reinforced polyamide resins, acetal polymers, aminoplastic resins or mixtures thereof. It is preferred to have an inner surface 234 coated with the same friction filling material or to be made entirely of such a friction filling material. For a positive friction filling gun, it is preferred that the nozzle 230 has an inner surface 234 coated with a fluoropolymer, in particular a friction filling material such as PTFE, or is made entirely from the friction filling material. Therefore, depending on the type of friction filling material selected, negative or positive charges are transferred to the powder particles when they contact the inner surface 234 of the nozzle 230. Thus, the nozzle 230 acts with the insert 220 to frictionally charge the powder particles to the desired polarity when the powder particles contact the inner surface of the gun 200.

Although not shown, insert 220 and nozzle 230 may be formed of an integrated single member unit releasably connected to body 210 (not shown). Alternatively, the insert 220 and the nozzle 230 are releasably connected together and then releasably connected to the body. Thus, a particular advantage of the short internal filling gun 200 of the present invention is the insert 220 and the nozzle 230 of a simple configuration, which simple elements are made of any of the above-mentioned friction filling materials or Coated and easily interchangeable with gun body 210. An array of inserts 220 and nozzles 230 made or coated with other friction filling materials may be provided for use with a single gun body. Suitable inserts and nozzles may be selected depending on the type of powder to be sprayed and the type of polarity applied to the powder. Since powders are filled differently depending on their chemical composition, material specific inserts can be used for specific powder chemistries. For example, since epoxy tends to be charged with a positive charge, PTFE may be ideal for such powders. Polyester, on the other hand, tends to be negatively charged, so it is better filled by the use of nylon inserts.

The following examples present several configurations that alter the placement of air jets, the type and location of the electrodes, and the use of friction filling materials. However, the invention is not limited to the above examples, and many other combinations and configurations are possible.

Example 12

In one example of the invention, the friction filling gun 200 with insert 220 is made of nylon 6/6 material. Insert 220 has two pairs of aligned, opposing air jets, each air jet angled with the insert sidewall at an angle Θ of 60 degrees and a speed of about 655 feet / sec and a total air flow rate of 4.2 cubic feet / minute. The centerline of the first pair of air jets is spaced 15.88 mm in the longitudinal direction from the centerline of the second pair of air jets. The grounded electrode was flush with the inner surface of the powder flow passage and offset 60 degrees from the air jets. The gun was measured to be 146.05 mm long from the powder inlet to the tip of the flat spray nozzle. The powder flow rate was 20 lbs / hr using Ferro 153W-108 polyester urethane powder. The transmission efficiency of this configuration was 78.0%.

Example 13

In another example of the invention using a gun of the same configuration as described in Example 12, the electrode was charged to -8 KV. Transmission efficiency was measured at 84%.

Example 14

In another example of the invention, a short barrel friction filling gun is made of Delrin 100 AF material. The total combined length of insert and nozzle is 85.73 mm. A 4 mm Delrin 100 AFdml flat spray nozzle was used. As shown in FIG. 2, the insert inlet diameter was 9.53 mm for a length of 28.58 mm and an open insert diameter of 12.7 mm following 45 degrees for the remaining tube length of 56.26 mm. Two pairs of opposing air jets were used, each having a diameter of 1.78 mm and an angle Θ of 60 degrees. The downstream set of air jets rotated 5 degrees around the longitudinal axis for the first pair of air jets. All air jets were offset from the longitudinal axis by a vertical distance of 0.89 mm. Each air jet has a speed of 655 ft / sec and a flow rate of 1 standard cubic feet per minute. A single grounded sharp tip electrode is located upstream from the air jets, as shown in FIG. The electrode was rotated at an angle of 60 degrees around the longitudinal axis for the first set of air jets. The transmission efficiency of this configuration was 70% using Ferro 153W-121 at 20 lbs / hour.

In summary, the short barrel friction filling gun described above provides a new lightweight spray gun that can be easily maneuvered in dense space due to its short length and small diameter gun. Conventional friction filling guns are typically 355.6 mm to 914.4 mm in length, and short friction filling guns provide a gun of about 152.4 mm. The gun is used as a manual or low cost automatic gun on its own. The straight flow powder path allows for easy cleaning as well as removable inserts that can be easily replaced by inexpensive inserts for rapid color change. The new material used to make the gun is an injection molded material, which can greatly reduce processing costs. Accordingly, the present invention provides a short barrel friction filling gun capable of accepting powder flow rates up to 30 lbs / hour and allowing reasonable transfer efficiency.

The present invention further provides a short barrel cathodic friction filling gun that may be used in combination with a negative corona gun or as a single unit, as described in more detail below. Short barrel cathodic friction filling guns offer all the advantages described above, as well as thermoplastic powders such as PVC and PTFE powders, as well as superior applicability filling polyesters such as TGIC polyesters, epoxy / polyester hybrid powders, and polyester urethanes. It further provides the benefits of powder.

III. Unipolar Corona Gun with Friction Filling Element

In FIG. 6, a monopolar corona spray gun 300 is provided for spraying a flowable powder filled with bipolar or cathodic. The term "unipolar" refers to a powder spray gun or powder supply system that selects the elements to fill the powder coating material with unipolarity. An example may be a corona gun having a negative powder supply comprising a friction filling element such as a spray nozzle to negatively fill the powder. Gun 300 includes a rear barrel 328 that can be secured to the installation block. The rear barrel 328 has a corner hole 333 and an inner hole 332 for connecting to the powder feed tube 324. The powder feed tube 324 acts to introduce the flowing powder into the through hole 332 of the rear barrel member 328 through the corner hole 333. The front end of the rear barrel member 328 is connected to the front barrel member 338 which further comprises a through hole 346, which passes powder from the powder supply tube 334 to the gun 300. It is axially aligned with the hole 332 to form a powder flow passage 350 for conveying towards the front end. The flat spray nozzle 394 is located at the front end of the front barrel member 380.

The barrel liner 352 extends axially in the powder passage 350 provided at the end of the rear barrel member 328. The barrel liner 352 houses and supports the high pressure electrostatic cable assembly 359. Electrode 362 is installed at the front end of cable assembly 352 and extends through hole 396 of nozzle tip 390 and extends forward of spray nozzle 394 between rectangular slots 398. An electrode 362 extending forward of the spray nozzle 380 creates a strong electrostatic field between the electrode and the object being coated. The electrode can be charged either positive or negative, depending on the desired dry polarity. The electrode is preferably charged to the desired polarity in the range of about 60 to about 100 kv.

The powder contact surface of the corona gun 300 is a passage 372 through the barrel liner 352, the powder passage 350, the powder feed tube 334, and the nozzle 380. For a bipolar corona gun that bipolarly charges the powder, the one or more contact surfaces 334, 350, 352 or 372 include, for example, materials that tribologically charge the powder. These materials are selected from the group consisting of polyethylene, fluoropolymers or mixtures thereof. The fluoropolymer preferably contains polytetrafluoroethylene. For the negative corona gun to negatively charge the powder, the one or more powder contact surfaces 334, 350, 352 or 372 are selected, for example, from a material that negatively frictionally charges the powder. These surfaces contain a material selected from the group consisting of polyamides, polyamide mixtures, fiber reinforced polyamide resins, acetal polymers, aminoplastic resins or mixtures thereof, as described in detail in section (I).

Thus, the monopolar corona gun of the present invention utilizes a friction filling method to fill the powder as well as corona filling. Since the frictional charge generated is the same polarity, it increases the charge in the powder generated at the corona charging electrode. Since the powder contact surface is added to the charge of the powder produced by the corona electrode, less electrode voltage is required than is necessary to generate the same amount of charge as in the prior art. Thus, for the negative gun, reduced white ionization occurs because of the low voltage. These results improve the surface finish. This reduction in electrode voltage reduces the Faraday cage effect. Also, a small power supply can be used to produce the same voltage.

In another embodiment of the present invention, the corona gun 300 may further include an improved friction filling nozzle 400, as shown in FIG. The friction filling nozzle 400 may be used with other prior art corona or friction filling guns and is not limited to the corona gun 300 as described above. The friction filling nozzle 400 provides a large inner surface area that can be used for friction filling powder. The powder may be filled either positively or negatively as desired, depending on the friction filling material selected, as described in more detail below.

The nozzle, generally indicated by reference numeral "400," has an internal flow passage 412 and a powder inlet end 410 in fluid communication with an internal passage of a prior art corona gun or triboelectric gun (not shown). The inlet end 410 is preferably cylindrical in shape with a transition surface 414 guided to the nozzle slot 420. The nozzle 400 generally has a slot 420 shaped to produce a flat spray pattern. The depth and width of the nozzle slot 420 can be sized as needed for a particular application.

Since the nozzle surfaces 412 and 414 are in contact with the powder, it is preferable that the nozzle 400 has an inner surface coated with a friction filling material or is made entirely of a friction filling material. For a bipolar corona gun, the nozzle preferably has an internal powder contact surface made of or coated with a material selected from the group consisting of fluoropolymers, in particular PTFE. For use with the negative gun, the nozzle 400 is selected from the group consisting of polyamides, in particular nylon 6/6, polyamide mixtures, fiber reinforced polyamide resins, acetal polymers, aminoplastic resins or mixtures thereof. It is better to have the inner surfaces 412 and 414 coated with or to be made entirely of a material selected from the group above. Therefore, depending on the type of friction filling material selected, negative or positive charges are transferred to the powder particles when in contact with the inner surfaces 412 and 414 of the nozzle 400. Thus, the nozzle 400 can act in conjunction with the corona charging electrode of prior art spray guns to fill the powder with the same polarity as the corona electrode.

The nozzle 400 may preferably include one or more air jet orifices 430 disposed to be in fluid communication with the internal passageway 412 of the nozzle. For example, air or other fluid is provided to the air jet orifice 430 by a chamber 440 connected to an external fluid source (not shown) through the port 450. The air jet orifice 430 is preferably sized and structured to provide air at a speed in the range of about 100 to about 1,000 feet / second, more preferably in the range of about 400 to about 800 feet / second. It is also preferred that the air jet orifice 430 includes an angle a with respect to the longitudinal axis of the insert internal passageway, in the range of about 0 to about 90 degrees, more preferably, about 45 degrees to about 90 degrees. . The angle of the air jet orifice 430 is preferably set to provide turbulence so that the air jets increase frictional contact with the filling surface. The impact angle β of the air jets at the front side 414 is preferably in the range of about 45 degrees to about 90 degrees, more preferably about 60 degrees.

The nozzle 400 may further include one or more electrodes 460 or other means known to those skilled in the art to discharge the inner surface 412. At least one electrode is preferably grounded. Alternatively, the one or more electrodes can have a positive or negative charge in the range of about 0 to about 100 KV, more preferably in the range of about 0 to about 10 KV. The high voltage electrode (s) is charged positively if a negatively charged material is used, and if the positively charged material is used at the surface of the nozzle, the electrodes are negatively charged. As shown in FIG. 7, the electrode may be disposed in the electrode holder 490. The electrode holder 490 has an outer surface 492 made of the material described for the inner passage 412 of the nozzle described above. However, it is important to note that it is possible with other electrode types such as ground rings, blunt or sharp tipped conductive pins. If conductive pins are used, they may be disposed perpendicular to the fluid passages of the nozzle 400. The electrode is disposed upstream of about 50.8 mm of the air jet impinging the wall.

In a preferred embodiment of the nozzle, the electrode is disposed and grounded upstream of two pairs of aligned opposing air jets laterally spaced by one diameter. Air jets are formed at an angle of 60 degrees with respect to the longitudinal axis.

Ⅳ. Friction Filling Elements in Powder Delivery Systems

The present invention further provides a friction filled powder contact surface to the various elements through a powder delivery system that can be used to frictionally fill the powder with the same polarity as the corona powder feed. Friction charging in various areas along the delivery system increases the charge in the powder as it passes through each frictional charging area. This gives the corona gun the benefit of increasing transmission efficiency. This principle can be used with the friction filling gun system. The frictional filling regions of the powder supply system frictionally powder the powder to the same polarity used in the triboguns of the system.

As shown in FIG. 9, a conventional powder spray system includes a spray gun 510 connected to the hopper 520 by a powder supply hose 540 and installed on top of the hopper via a powder pump 530. Spray gun 510 is, for example, a powder spray gun of the cathodic filled corona type, but may alternatively be a bipolar filled corona gun or a cathodic or bipolar friction filled powder spray gun.

Wire 544 is connected to gun 510 in control system 550 that regulates the air pressure of pump 530 and the voltage of the corona electrode of gun 510. Within the powder hopper 520, a diffuser plate 521 is configured to extend with respect to the cross sectional area in the hopper and is formed of a porous material through which air passes to fluidize the powder. Since the hopper sidewall 522 and the diffusion plate 521 have a large contact area of powder, the present invention is directed to polyamide, in particular nylon 6/6, polyamide mixtures, fiber reinforced polyamide resins, acetal polymers, aminoplastic resins or the like. And forming the diffusion plate 521 and the sidewalls 522 with a negative friction prefill material selected from the group consisting of the mixture. Thus, contacting the powder with the sidewalls in the diffusion plate 521 and the hopper 520 precharges the powder to the cathode before being transported to the negative corona gun 510.

The pump 530 shown in cross section in FIG. 8 includes a body 531 having a powder inlet tube 532 guided to a cavity 533, the cavity 355 having a venturi throat 535. It is crossed by a venturi nozzle 534 or an ejector. The venturi body 535 is held at the pump body 531 by a neck holder 536 extending from the pump body to provide an attachment mechanism 537 for the hose. Within the attachment mechanism 537 is a wear sleeve 538 described by a wear tube downstream of the pump neck. The wear sleeve prevents impact fusion on the inner wall of the neck holder. Atomizing air inlet 539 intersects neck holder 536 to provide an air flow that engages the powder air mixture from the Venturi neck.

This area in the powder delivery system is in a suitable position for the use of one of the prefilled materials described above. Accordingly, the venturi neck 535, wear sleeve 538, pump suction tube 532 and powder hose (not shown) are negatively charged to precharge the powder with triboelectricity, as described in more detail above. It is preferred to be made of or coated with a material selected from the group consisting of polyamides, polyamide mixtures, fiber reinforced polyamide resins, acetal polymers, aminoplastic resins or mixtures thereof. In addition, the venturi neck 535 and neck holder 536 preferably extend beyond the edge of the pump body by, for example, 25.4 mm to 127 mm. Optimally, this extension length is provided for the cathodic friction filling of substantially another powder in this region of the powder delivery system.

As described in the section above, the prefilled powder in the powder delivery system in the hopper and / or the pump flows through the hose to reach the gun with the desired negative charge. This precharge increases the other negative charge applied to the gun by the corona electrode.

Ⅴ. Monopolar powder coating system with corona and friction filling guns

As shown in FIG. 9, the corona gun 510 is shown for use with the friction filled powder spray gun 10 of the present invention described above. The corona gun 510 and the friction filling gun 10 have the same polarity. Due to this unique combination, the friction filling gun 10 can be used, for example, as a touch up gun penetrating the corners or to reach parts where the corona gun 510 does not effectively coat. it's difficult. Said exemplary combination of negative corona gun 510 and negative friction filling gun 10 preferably comprises powder as described above. The common powder delivery system 520 is precharged with a negative electrode. Alternatively, the friction filling gun may comprise a short barrel gun 200 (not shown) described in more detail above. The new combination of one or more negative electrode corona guns and one or more negative electrode friction guns, optimally a delivery system of negative prefilled powders used to coat other parts of the same workpiece, is an important embodiment of the present invention.

Ⅵ. Friction Filling Gun with Air Jets

As shown in FIG. 10, the new friction filling gun 600 includes a powder supply section 610, a powder filling section 620, and a spray nozzle 630 located at the outlet of the gun. The powder filled section 620 of the friction filling gun 600 further includes a cylindrical body 622 having an inner hole 623 for receiving the internal elements of the gun. The powder tube connector 612 with the inner hole 626a is received in the hole 623 of the body 622. The first end 616 of the connector 612 is connected to a powder supply tube (not shown) for supplying the flow powder to the powder flow passages 626a, b, c of the gun 600. The second end 618 of the powder tube connector 612 is connected to an inlet air entry 640. Inlet air inlet 640 has an internal passageway 626b and one or more corner holes or air jets 642 that are compressed air to induce turbulence and increase the velocity of the flow powder entering the gun. Is connected to an air manifold 628 located in the body 622 for the purpose of supplying it to the air jet 642. An outer wear tube 650 having an inner passage that is part of the powder flow passage 626 of the gun is connected to the inlet air inlet 640. Outer wear tube 650 further includes one or more air jets 652. Compressed air is supplied to the air jet 652 through a passage 654 in fluid communication with the air manifold 628. Gun 600 may further include optional internal wear surfaces 660 that form an annular powder flow path. As shown in the cross section of FIG. 10A, the plurality of air jets 652 are arranged in opposing configurations at one or more longitudinal stations. Preferably, the air jets 652 preferably include an angle γ (measured counterclockwise from the longitudinal axis) in the range of about 90 degrees to about 135 degrees. The air jet velocity is preferably large enough to cause the powder to flow through the passages in contact with the wall opposite the air jet and to induce turbulence in order to increase the frictional filling of the powder. The speed of the air jet is preferably in the range of about 100 to about 1000 feet / second and more preferably in the range of about 400 to about 800 feet / second.

In order to provide frictional filling of the powder, the powder contact surfaces of the gun, such as the inner surfaces of the powder flow passages 626a-c, the outer surface of the nozzle 630 and the inner filling tube 660 are coated or constructed with a friction filling material. For the bipolar friction filling gun, the powder contact surfaces are preferably selected from the group consisting of fluoropolymers, in particular PTFE. For the cathodic friction filling gun, the powder contact surfaces are preferably selected from the group consisting of nylon, in particular nylon 6/6, polyamide mixtures, fiber reinforced polyamide resins, acetal polymers, aminoplastic resins or mixtures thereof.

As shown in FIG. 11, in another embodiment of the present invention, the friction filling gun is the same as described above except for the following differences. The first difference is that the inner fill tube 660 is not used. The second difference is that the air jets 652 of the friction filling gun 600 located in the outer wear tube 650 are arranged in a spiral pattern with respect to the longitudinal axis, as shown in FIGS. 11 and 11A. Optionally, the air jets 652a located at the top of the tube 650 may have a different angular orientation than the air jets 652b (not shown) located at the bottom of the tube 650. When configured in this manner, the air jets 652a and 652b are designed to impinge the flow powder against the opposing wall in a rattle or corrugated manner, in order to increase the frictional filling of the powder. The configuration is preferred in which three to four sets of holes are arranged, each set including two or more holes. This helical configuration acts to induce and swirl the flow powder in a spiral manner such that relatively heavy powder is induced or elongated to impinge the wall with the passage wall through centrifugal force.

An advantage of this embodiment is that instead of forming a mechanical waveform on the filling surface, as shown in the gun of FIG. 1, in order to cause each powder particle to strike the filling surface several times and thereby increase the charge of the powder, an air jet 652 are easy to manufacture, while the powder particles run multiple times to increase the triboelectrically induced charge on the powder for turbulent route through the flow passages 626a, b, c. It is called a straight cylinder.

FIG. 12 shows another embodiment of the short barrel friction filling gun 200 of FIG. 2. In the embodiment of FIG. 12, the modified gun 200 ′ includes a gun body 210 ′ that holds the powder conduit insert 800 somewhat different from the insert 220 of FIG. 2. Insert 800 includes a powder feed inlet 802 and an optional diffuse air inlet 804. Diffused air can be used as needed to increase the speed of the powder through the modified gun 200 '. This increased speed can be used to increase the friction filling effect in the powder, aid in the diffusion of the powder, and affect the spray pattern. Diffusion air, however, is not necessary in every situation and depends on several factors, which are not only how much further diffusion of the powder is needed through the gun, but also the powder feed elements (see FIG. 9 and the present application). Related description) and the velocity and pressure of the powder inlet gun 200 ′ from the powder supply hose 540. In many cases where air jets are incorporated into a friction-filled gun, the pressure drop generated by the air flowing through the air jets may be sufficient to eliminate the use of diffused air. This is a special case where the air jets are angled forward to direct critical air flow axially forward through the gun, thereby inducing an inhalation effect at the powder inlet end of the gun. Reducing the use of total air in a spray gun is generally beneficial because it can reduce the operating costs associated with workplace air, impact fusion and wear. Reducing impact fusion aids rapid color change and cleaning operations.

The inner end 800a of the powder conduit insert 800 slidably receives the first end of the fill tube 806. Filling tube 806 is preferably made from any of the various materials described herein to apply the positive or negative charge to the powder as desired for a particular application. Filling tube inlet 806a may include an optional inner diameter reducer or neck down 808 that increase the powder velocity (without the need to increase diffusion air volume or pressure). And re-center the powder in the center volume of the fill tube 806 before the powder enters the main portion of the fill tube.

The solid or hollow shaft 810 is disposed in the filling tube 806 longitudinally and preferably coaxially. This shaft 810 is preferably cylindrical but not required to facilitate the discharge of the shaft 810. Optional taper to conical end 810a. The charge tube 806 includes a metal discharge or ground ring 812 connected to the ground discharge pin 814. The fin 814 allows the filling tube 806 and the shaft 810 to self-discharge during the spray operation when charge is generated on the finish charge surface. Hole 816 provides to receive a wire or ground pin in contact with ground ring 812.

Body 210 ′ includes inlet port 250 ′ in the same manner as port 250 of the embodiment of FIG. 2 herein. The port 250 ′ opens into the annulus 817. The annulus 817 is in fluid communication with and surrounds the annulus 818, where the annulus 818 is generally an inner surface of the filling tube 806 and an outer circle of the shaft 810. It is limited to the space between the main surfaces. The annular portion 818 preferably forms a fairly small gap between the filling tube 806 and the shaft 810. A series of air jets 240 ′ are provided through the wall of the filling tube 806 in a manner similar to the embodiment of FIG. 2 herein, with compressed air flowing from the outer annulus 817 to the inner annulus 818. . The exact location, number, angle, and orientation of the jets 240 'may be determined based on several factors, as described above herein. According to one aspect of the invention, for example, compared to the diameter of the tubular insert 220 of FIG. 2, the small annular portion 818 is pressed towards the shaft 810 by air from the jet 240 ′. It greatly reduces the travel distance for the powder particles to be made. Thus, less air is required to run the powder to hit the frictional filling surface of the shaft 810 at a speed comparable to the embodiment of FIG. 2. This not only reduces the need for air, but also reduces blow melting effects. In addition, the use of the shaft 810 not only increases the internal surface area of the filling tube 806, but also the surface area of the shaft 810, thereby increasing the overall surface area of the friction filling material to which the powder particles are exposed. The air jet 240 'is offset, or forward or radially [deformed of the gun 200' deformed as shown in FIG. 12, to increase spin air movement around the shaft 810, as described herein above. An angle can be formed with respect to the longitudinal axis. Narrow annular portion 818 is a conventional friction filling effect in powder when the prior art friction filling gun passes through the gun 200 ', where the powder is deformed in an analog manner using a twisted or corrugated path through which the powder passes. Allow. Although the exact size chosen depends on the overall performance characteristics and the requirements of each gun design, through view, the annular portion 818 may vary by about 0.51 mm to about 12.7 mm.

The shaft 810 is disposed and fixed to the filling tube 806 by some conventional mechanism, such as, for example, a centering pin (not shown). In addition, in the embodiment of FIG. 12, the insert 800, the filling tube 806, and the nozzle 820 form a gun barrel and the positive charge of the powder particles, such as the shaft 810, is made of the friction filling materials. Or may be made of the various materials described herein above to produce negative charges. The embodiment of FIG. 12 uses a conventional flat spray nozzle 820 with a slot 821, but any suitable nozzle design may be used.

In FIG. 13 another embodiment of the FIG. 12 version is shown. Similar parts are provided for similar parts and the description is not repeated. In the embodiment of FIG. 13, the filling tube 822 and the shaft 824 have a corresponding configuration of the nozzle body 826 to define a parallel corrugated path 828 of frictional charging downstream of the annular portion 818. The front end is modified to cooperate. The corrugated path 828 is realized in the form of a watch type with a reduced diameter in the nozzle body cavity 820. The shaft 824 is formed in a corresponding geometry, and the front end of the fill tube 822 simply contacts the rear end of the nozzle body 826 to form a smooth continuous contour. The spider 830 is centered and supported by the nozzle body 826 cavity by a plurality of radial legs 832. The spider 830 may be assembled with the shaft 824 or assembled with the shaft 824, if necessary by the pin insert 834, at the front end of which the spider 830 may displace the conventional conical nozzle 836. It can be used to support it. Spider 830 is made from any suitable friction filled material described herein. In this embodiment, the gun 200 "is a post-filling function of frictional charging generated by the parallel corrugated path 828, as well as the filling tube 822 and shaft 824 and both air jets that initially charge the powder. It works in conjunction with 240 '. Although in the embodiment of Figure 13, the friction filling section 828 is shown in a parallel waveform pattern, this illustration is intended to be illustrative in nature and should not be construed in a limiting sense. The person skilled in the art can realize that the friction filling section uses any number of known friction filling devices.

FIG. 14 shows another modification of the modified gun 200 ′ of FIG. 12. In this version, the shaft 810 is compared with the shaft 810 of FIG. 12. Installed in some axial forward position. This has the effect of placing the conical rear tip 810a of the shaft 810 further adjacent to the ground pin 814. This greatly increases the ease with which the shaft 810 can be discharged during the spray operation.

FIG. 14 further includes the concept of incorporating the original air jet assist or inductive friction charging function with additional friction charging to the gun 200 '. In comparison with the example of FIG. 13, note that in FIG. 14, air jets 240 ′ are disposed at the rear of the shaft 810. This is first guided by the friction filling function, and subsequently arranges the air jet with the friction filling function of the annular portion 818. Air jets apply sufficient energy to the powder particles to strike the filling tube and shaft surfaces to cause the powder to charge. The air flow generated by the air jet can be used if twisted, corrugated or other conventional friction filling techniques and configurations are required, but without the need for such a friction filling path, it is possible to allow friction filling effects through the annular portion 818. Enough.

15, another embodiment is shown. The basic concept shown in the figures is described herein as an "inside-out" gun because the direction of flow of the air jets is reversed, compared to the embodiment described above. Thus, the prior art embodiments of the present disclosure may be described as "outside-in" guns for convenience. In the embodiment of FIG. 15, the gun 840 includes a gun body 842 having a rear end 842a and a front end 842b. The rear end 842a includes a counterbore that slidably receives and holds the powder conduit insert 844. Powder insert 844 supports powder tube connection nipple 846 and air inlet connector 848. Insert 844 receives and supports the first end of filling tube 850 made of the appropriate friction filling material described herein above. Fill tube 850 extends through nozzle body 842 to nozzle assembly 852. The special design of the nozzle assembly 852 can be selected as needed for a particular spray pattern. In the example of FIG. 15, the nozzle assembly 852 includes a nozzle body 852a that holds a spider 852b that supports a conventional conical nozzle 852c at one end. The spider 852b may include another suitable member, such as a pin, or radial legs 852d to support the spider 852b in the nozzle body 852a.

Insert 844 receives and supports the first or inlet end of air tube 854, which is realized in the form of a hollow shaft in this example. Air tube 854 includes one or more air jets 856 formed at appropriate angles and orientations, as described above with respect to other embodiments herein. In the example of FIG. 15, the air jets 856 generate air flow towards the front of the gun 840, but are angled radially to direct the powder towards the inner surface 858 of the fill tube 850. do. Inlet end 854a of air tube 854 is in fluid communication with air inlet coupling 848. Thus, pressurized air supplied to the air inlet 848 via an air hose (not shown) enters the air tube 854 and exits through the various air jets 856. The air tube 854 is generally extended in common with the fill tube 850 and the front end 854b of the air tube 854 is closed and supported by the spider 852a.

For example, when compared to the embodiments of FIGS. 2,7,3a to 3d, 4a to 4h and 11, the concept of the inside out gun is characterized by the fact that powder particles may The effect of pressurized air is to have a near short travel distance from the air jet 856. This reduces the amount of air to get the proper blow rate or reduces the amount of low energy in the particles moving under the gun so as to carry out the proper filling of the powder. The air tube 854 may be made of a friction filling material to further increase the friction filling effect of the design. Another advantage of Inside Out Design is that the gun is simpler to manufacture when using fewer parts.

FIG. 16 shows a variant of the inside out gun of FIG. 15. In FIG. 16, the gun 840 ′ has a central gun body 860 that acts as a fill tube. Powder insert 844 ′ is attached at the inlet end of the body and nozzle assembly 852 ′ is attached at the opposite end of gun body 860. The nozzle assembly 852 ′ may be similar to that shown in FIG. 15 or in some other suitable design.

In FIGS. 15 and 16, ground pin 862 extends through gun body 842/860 to discharge gun internal elements and frictional filling surfaces. Pin 862 is shown in FIG. 16 along with the pins omitted from FIG. 15 to illustrate pin holes 862.

17 illustrates an embodiment of the invention in a manually operated gun configuration. The above embodiments of the present application are shown as automatic gun configurations are installed on the gun support and gun mover, although the main elements of the embodiments can be incorporated into a manual gun handle, as shown in FIGS. 17 and 18. do.

In FIG. 17, the gun 870 includes a handle 872 with a trigger 874 or other control means for controlling the flow of powder through the gun 870. Gun body 876 supports powder supply hose connector 878 to which a powder supply hose (not shown) can be connected. The powder flows through a powder extension tube 880, which may be made of a friction filling material. Extension tube 880 is supported within gun body extension 882 that supports nozzle assembly 883 at the opposite end. Extension tube 880 is generally installed concentrically within extension 882 and gun body 876 to provide annular portion 884. The annular portion 884 receives pressurized air through an air mechanism 886 connected to an air line 886a extending through the handle 872. Diffusion air passage 888 is formed through the wall of powder extension tube 880. The passage 888 is sized to achieve the desired balance between air moving from the annulus 884 to the fill 890 of the gun 870 and diffused air entering the powder extension tube 880.

The fill 890 of the above example is in the form of an outside-in gun and includes a fill tube 892 inserted into the front end of the powder extension tube 880 at one end. The front end of the fill tube 892 is assembled into a nozzle assembly 883. Fill tube 892 is supported by legs 894 or ribs that include air from annular portion 884 or allow this air to pass through a series of air jets 896. The air inlet and fill tube 892 directs the powder particles to strike the frictional filling surface 892a of the fill tube 892, as in the previously described embodiment. It can also be envisaged that the extension tube 880 and nozzle assembly 882 can be made of a suitable friction filling material to increase the filling effect of the gun 870. Using the internal diffused air passage 888 requires only a single air supply of the gun 870 to both the air to the jet 896 and the diffused air, so that the second air port on the side of the gun of the portion 890 Eliminate the need for Although not shown in FIG. 17, a shaft similar to the concept for shaft 810 of FIG. 15 may be used in the gun configuration of FIG. 17.

The embodiment of FIG. 17 has a ground pin 893 connected to an extension 882 that is electrically conductive. The extension 882 is alternately connected to a ground screw 885 that is electrically grounded by a ground wire 887. Positioning the ground pin 893 upstream of or immediately after the position at which the friction-filling air assist jets 896 first strike the filling surface is a surface created at the friction-filling surface due to the frictional charging of the powder at that position. The charge can be easily discharged by the ground pin 893 in order to promote frictional charging of the powder. If the ground pin is placed upstream too far from the air jet impact point, the surface charge produced at the surface is not discharged by the ground pin. If a ground pin is placed in front of or downstream of the location where the friction-charged air jets impact the charging surface, the powder is charged by the collision and the surface is discharged by the ground pin as the powder flows downstream of the ground pin. .

In conventional friction filling guns, extending the length of the gun barrel downstream of the friction filling portion tends to cause a loss of charge before the powder is injected through the nozzle. 18A-18D, for other gun lengths, another configuration is shown in which the air jet induced friction filling gun 890 is held closer to the nozzle, thereby minimizing charge loss. In all of the above embodiments, the grounding pin or other grounding member (not shown) is preferably disposed at a position immediately after the place where the friction-filled air assisted manufacture first strikes the charging surface, as in the embodiment of FIG.

In FIG. 19, a spray gun is shown that incorporates the concept of an inside-out gun in a manual spray gun configuration. Gun 900 includes gun body 902 with a handle 904. Handle 904 may include a conventional trigger mechanism 906 for controlling gun flow flowing into gun 900. Body 902 supports fill tube 908 within body extension 910. Fill tube 908 is made of a suitable friction filling material, as described above. At the rear end of the gun body 902, the powder hose connector 914 and the air mechanism 916 (in FIG. 19, air and powder supply lines are omitted for clarity in a manner similar to the embodiment of FIGS. 15 and 16). Attached is a powder inlet cap assembly 912 that includes. Air inlet 916 is in fluid communication with air tube 918 extending longitudinally through gun 900 from inlet head 912 to nozzle assembly 920. In this embodiment, the nozzle assembly includes a flat spray nozzle 922 installed with a spider 924 that is similar in design to the spider 852b of FIG. 15 herein. Spider 924 supports the front end of air tube 918. The air tube extends generally concentrically through the gun 900, providing an annulus 926 between the inner surface 908a of the fill tube 908 and the outer surface of the air tube 918. In the portion 928 of the gun 900, a plurality of air jets 930 are provided through the wall of the air tube 918 which is directed towards the front end of the gun near the nozzle. The number, location, orientation, and angle of the various air jets 930 may be selected for a particular gun design, as described above. The air jets 930 are not all required at the front end of the gun 900, but may be further directed towards the gun handle.

The powder enters the gun 900 through the coupling 914 and passes through the annulus 926. Before the powder reaches the portion 928 of the gun 900, an annular portion 926 of appropriate size may be used to prefill the powder. Pressurized air flows into the annulus 926 inside the air tube 918 to effect powder particles striking the friction filled surface of the fill tube 908. The air tube 918 may be constructed of a friction filling material to increase the filling effect in the powder. Although the gun 900 is shown with a filling tube 918 disposed within the gun extension 910, the two members can be a single tube, as desired, in the embodiment of FIG. 16 herein.

As in the above embodiment, the ground pin 931 is disposed at a position immediately after the place where the frictionally charged air assist jet 930 strikes the charging surface for the first time. Ground pin 931 is connected to an extension 910 that is electrically conductive. Extension 910 is grounded to ground wire 935 through ground screw 933.

Another advantage of the in-out gun configurations shown herein is that if impact fusion occurs along a portion of the fill tube face, the air jets 930 are grown toward “clean” friction filled surface areas without impact fusion. Straight motion to simply rotate the air tube 918 through an angle sufficient to direct it. This improves the filling efficiency with which the clean filling surface is exposed to the striking powder particles and the gun is used. Alternatively, the relative axial position between the air jet 930 and the frictional filling surface may be adjusted to expose the clean filling surface to the powder or both relative charging and rotating positions may be varied.

20 illustrates another configuration of the present invention that combines a single gun outside-in configuration with an inside-out configuration. In this embodiment, the gun 940 includes a gun body 942 that supports the powder inlet cap at one end and the nozzle assembly 946 at the opposite end. The nozzle assembly 946 is shown as a conical nozzle type that sleeps the nozzle 948 supported by the spider 950 in a manner similar to other embodiments described herein.

Inlet assembly 944 includes powder hose mechanism 952 and air mechanism 954. The air mechanism 954 is in fluid communication with an air tube 956 extending through the gun to the nozzle assembly and supported at the front end by the spider 950. Filling tube 958 is supported inside gun body 942 and concentrically surrounds air tube 956 to form a second or outer annular portion 960 therebetween. The air tube 956 includes a plurality of inside-out air jets 957 that allow air to pass through the annulus 960 inside the air tube. Filling tube 958 is sized to have a diameter smaller than the diameter of gun body 942, thereby providing an air passage or second outer annular portion 962. Fill tube 958 is provided with a plurality of air jets 964 such that fill tube 958 acts as an outside-in air tube. Pressurized air flows from the second or outer annular portion 962 into the first or inner annular portion 960 through the filling tube air jet 964. Powder from the inlet 952 flows into the inner annulus 960 and is accompanied by the air flow generated by the air jets 957,964. Two sets of air jets, one outside-in and the other inside-out, perform to increase the turbulence of the powder and impinge on both fill tube surface 958a and air tube outer surface 956a. Ground pin 966 is provided, as described above.

Pressurized air enters the gun through air appliance 954 and flows through air tube 956. In addition, an air passage 968 is provided that directs a portion of the air to the outer annular portion 962. In this way, only a single air input is needed for the gun. If necessary, some or air may be directed into the inner annulus 960 to act as diffused air, but this may be necessary because the volume of moving air from all air jets in most cases properly diffuses the powder. not. Gun 940 may include an additional powder flow length prior to the filling operation to incorporate the tribocharge precharge or subsequent charge effects.

21-24 illustrate another embodiment of the present invention. In this embodiment, the electrically conductive extension 972 supports the nozzle 974 with the slot 976. The filling sleeve 978 is installed between the nozzle 974 and the filling sleeve holder 980. Powder feed tube 982 is inserted into fill sleeve holder 980 and connected to powder feed horn 984. Ground pin 986 is connected to extension 972. Extension 972 is connected to ground wire 990 through ground screw 988. The filling sleeve holder 980 includes an air jet 981 or gun that improves the friction filling function. The jet 981 impinges on the inner surface 979 of the filling sleeve 978 constructed from the friction filling material described above. The ground pin 986 is located immediately after the place where the frictionally charged air assist jet 981 hits the charging surface 979.

22 and 23 show the filling sleeve holder 980 in more detail. As shown in FIG. 23, air jets 981 are disposed at 90 degree intervals around the circumference of the filling sleeve holder 980. A passage 992 to ground pin 986 is shown in FIG. 23 as being placed between two air jets 981.

24 shows a view of a filling sleeve 978 assembled to a filling sleeve holder 980. Positioning pin 996 is frictionally received within holder 980. When the filling sleeve 978 is assembled to the holder 980, the positioning pin 996 is received in a slot 994 formed in the outer surface of the sleeve 978. This allows the sleeve 978 to take a special positional orientation (hereinafter first orientation) in the holder 980. In the first orientation, any portion of the inner surface of the sleeve 978 is hit by the air jet 981 and worn out by frictional filling of the powder. In order to be able to expose other portions of the inner surface 979 to the air jet 981, a plurality of slots are formed outside of the sleeve 978. In order to reorient the sleeve of the holder 980 to another position orientation, the sleeve 978 is pulled out of the holder 980 and rotated to align with the pin 996 another slot formed outside the sleeve 978 and the sleeve 978 is then pushed back into holder 980. Here, a new part of the filling surface 979 is hit by the air jet 981 used for frictional or triboelectric, filling of the powder without the need to replace the filling sleeve 978. In addition, the sleeve 978 is symmetric such that the orientation in the holder 90 can be reversed with the opposite end of the sleeve 978 inserted into the holder 980. Before the sleeve 978 needs to be replaced, it can take this double the number of other oriented sleeves in the holder 980 to allow a large, flat portion of the surface to be used.

As a result, one of the advantages of this embodiment is that one or more elements of the gun used as a friction filling surface assembled into the gun in one or more orientations, so that more surfaces can be used to frictionally charge the powder before replacing the element with a new one. There is a new concept in triboelectric guns that are designed. This allows for greater savings for the consumer by making more use of the element before replacing it.

The triboelectric charging assembly is formed of two members, a charging sleeve and a charging sleeve holder, to provide additional cost savings to the consumer. By configuring the element in a two member assembly, only the filling sleeve holder, which is more complicated to contain and manufacture air jets, does not need to be replaced. Thus, the filling sleeve 978 is a simpler part to replace and manufacture than the filling sleeve as shown in FIG. 17 that includes air jets as well as the filling surface.

21-24, note that all embodiments of air jets 981 are in a single vertical plane. This has many advantages. The filling sleeve can be shorter than the filling sleeve in which the set of air jets is provided along the length of the filling sleeve. In addition, some air introduced at the rear of the gun supplies all the air jets evenly, which makes the powder more evenly filled. In addition, all powder striking areas in the sleeve are adjacent to the ground pin. Also, since there is no pressure drop between the first set of air jets and the second set of air jets, low pressure can be used for single plane air jets, which reduces the energy requirement.

According to another aspect of the present invention, various combinations of air jet assisted friction filling and friction filling techniques can be implemented in the spray gun. These include air jet assisted friction charging followed by frictional charging; Frictional charging followed by air jet assisted frictional charging; Inside-out air jet assisted friction charging followed by frictional charging; frictional charge followed by inner-out air jet assisted frictional charging; Inside-out air jet assisted friction filling followed by outside-in air jet assisted friction filling; And inside-out air jet assisted friction charges in combination with outside-in air jet assisted friction charges. Combinations of various friction filling materials can be used in the gun, including the necessary positive and negative charge materials. An important advantage of the air jet assisted friction filling gun is its short length design makes it suitable for coating the interior of pipes and other enclosed surfaces. The short gun length allows the gun to move through a pipe with multiple angle bends that is difficult for large length prior art spray guns.

Although the present invention has been described with reference to the preferred embodiments, those skilled in the art will understand that various modifications and equivalents may be made within the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the principles of the invention within its core scope.

Accordingly, the invention is not limited to the specific embodiments disclosed in the best mode devised for carrying out the invention, but the invention includes all embodiments within the scope of the appended claims.

Claims (47)

An apparatus for spraying a powder coating material having a powder flow path, the apparatus comprising: The powder flow path has a filling surface for triboelectrically charging the powder coating material in contact with the filling surface, the filling surface being selected from polyamide resin mixtures, fiber reinforced polyamides, aminoplastic resins and acetal polymers. A device composed of a negative friction filling material. 2. The apparatus of claim 1, further comprising one or more air passages formed through the filling surface, the air passages in fluid communication with a compressed air source. 2. The apparatus of claim 1, further comprising an electrical conductor provided adjacent said charging surface, said electrical conductor being connected to either an electrical ground or a source of electrical potential. 4. The apparatus of claim 3, further comprising one or more air passages formed through the filling surface, the air passages in fluid communication with a source of compressed air. An apparatus for spraying a powder coating material having a powder flow path, the apparatus comprising: The powder flow path has a filling surface for triboelectrically charging the powder coating material in contact with the filling surface, and further comprises one or more air passages formed through the filling surface, the air passages of the compressed air Device in fluid communication with a source. 6. The apparatus of claim 5, wherein the filling surface is comprised of a negative friction filling material selected from polyamide resin mixtures, fiber reinforced polyamides, aminoplastic resins, and acetal polymers. 6. The apparatus of claim 5, further comprising an electrical conductor provided adjacent said charging surface, said electrical conductor being connected to either an electrical ground or a source of electrical potential. An apparatus for spraying a powder coating material having a powder flow path through which the powder coating material flows; The powder flow path has a first charging surface for triboelectrically charging the powder coating material in contact with the first charging surface, the first charging surface containing a friction filling material having a first charging polarity, The apparatus further comprises a component through which the powder coating material flows, the component having a second filling surface configured as a friction filling material having the first charging polarity. 9. The apparatus of claim 8, wherein the element is a spray nozzle. 10. The apparatus of claim 9, wherein the spray nozzle comprises an air passage in fluid communication with a source of compressed air. 9. The apparatus of claim 8, wherein the first charge polarity is negative charge polarity. 12. The apparatus of claim 11, wherein the first fill surface is comprised of a negative electrode friction filling material selected from polyamide resin mixtures, fiber reinforced polyamide resins, aminoplastic resins and acetal polymers. A system for applying powder coating materials to articles, The system includes a powder supply device for supplying a powder coating material and a device for spraying the powder coating material received from the supply device, the spray device comprising an electrode for filling the powder coating material with a first charging polarity. And the supply device comprises an element having a charging surface for triboelectrically charging the powder coating material in contact with the charging surface, wherein the charging surface is constituted by a friction filling material having the first charging polarity. system. The system of claim 13, wherein the element comprises at least one flow plate, a hopper wall, a suction tube for the pump, and an element of the pump or hose. 14. The system of claim 13, wherein said filler side is comprised of a negative electrode filler material selected from polyamide resin mixtures, fiber reinforced polyamide resins, aminoplastic resins, and acetal polyamides. The system of claim 13, wherein the spray device comprises a filling surface for filling the powder coating material to the first filling polarity. 17. The system of claim 16, wherein the filler surface is comprised of a negative friction filling material selected from polyamide resin mixtures, fiber reinforced polyamide resins, aminoplastic resins and acetal polymers. A system for applying powder coating materials to articles, The system includes at least one corona-filled spray device and at least one friction-filled spray device, the corona-filled spray device having an electrode for filling the powder coating material with a first charge polarity, the friction-filled spray device The apparatus has a powder flow path, the powder flow path having a filling surface for triboelectrically filling the powder coating material in contact with the filling surface, wherein the powder coating material is the filling surface of the powder filling spray apparatus. The system is charged to said first polarity. 19. The system of claim 18, wherein the first charge polarity is negative polarity. 20. The system of claim 19, wherein said fill surface is comprised of a negative friction filling material selected from polyamide resin mixtures, fiber reinforced polyamides, aminoplastic resins, and acetal polymers. 21. The system of claim 20, wherein the system further comprises a powder supply device for supplying powder coating material to at least one of the corona filled spray device and the friction filled spray device, wherein the supply device is in contact with the filling surface. An element having a filling surface for triboelectrically charging a powder coating material, said element filling surface consisting of a friction filling material having said first charging polarity. 22. The system of claim 21, wherein the urea fill surface is comprised of a negative friction fill material selected from polyamide resin mixtures, fiber reinforced polyamides, aminoplastic resins, and acetal polymers. 22. The system of claim 21, wherein the powder supply device supplies powder coating material to at least one corona filled spray device and at least one friction filled spray device. 19. The system of claim 18, wherein the corona filled spray device is used to coat a first portion of the article and the friction fill spray device is used to coat a second portion of the article. The system of claim 24, wherein the second portion of the article is a recessed portion of the article. 25. The system of claim 24, wherein the corona filled spray device first applies a powder coating material to the first portion of the article and thereafter the friction filled spray device applies the powder coating material to the second portion of the article. A friction-filled powder spray comprising a body having an inner hole, a wear tube located within the inner hole, an open passage provided between the inner hole and the wear tube, and at least one air jet passage provided through the wear tube. In the apparatus, The air jet passage provides fluid communication between the open passage and the interior of the wear tube, the wear tube having a charge surface for triboelectrically charging powder coating material in contact with the charge surface, the open passage Is in fluid communication with the source of compressed air, whereby the friction filled powder flowing from the open passage through the air jet passage into the wear tube to effect compressed air through the wear tube through the wear tube. Spray device. 28. The friction filled powder spray of claim 27 further comprising an inner wear surface located within said wear tube, said inner wear surface having a filling surface for triboelectrically charging powder coating material in contact with said filling surface. Device. 28. The apparatus of claim 27, wherein the filler surface is comprised of a negative friction filler material selected from polyamide resin mixtures, fiber reinforced polyamides, aminoplastic resins and acetal polymers. A system for applying powder coating materials to articles, The system includes a powder supply device for supplying a powder coating material and a device for spraying the powder coating material received from the supply device, the supply device for triboelectrically charging the powder coating material in contact with the filling surface. And an element having a filling surface, said urea filling surface consisting of a negative friction filling material selected from polyamide resin mixtures, fiber reinforced polyamides, aminoplastic resins and acetal polymers. An apparatus for spraying a powder coating material having a powder flow path, the apparatus comprising: The powder flow path has a filling surface for triboelectrically charging the powder coating material in contact with the filling surface, and further comprises one or more air passages formed through the filling surface, the air passages of the compressed air An apparatus disposed in the powder flow path such that it is in fluid communication with the source and the friction filling insert shortens the powder travel distance to strike the filling surface. 32. The apparatus of claim 31 wherein the powder flow path is generally cylindrical and the insert is also cylindrical and has a smaller diameter than the powder flow path. 33. The apparatus of claim 32, wherein the insert and the powder flow path form an annular portion and the powder passing through the annular portion is friction filled. 34. The apparatus of claim 33, wherein the air passage is upstream of the annular portion. 34. The apparatus of claim 33, wherein the air passage opens to the annular portion. An apparatus for spraying a powder coating material having a powder flow path, the apparatus comprising: The powder flow path having a filling surface for filling the powder coating material with triboelectricity in contact with the filling surface, further comprising an air flow path spaced apart from the filling surface and extending in common within the filling surface; An air flow path is defined by a wall having one or more air passages formed through the walls, the air passages in fluid communication with a source of compressed air. 37. The apparatus of claim 36, wherein the air flow path is defined by a tubular wall disposed concentrically in a large tube forming the fill surface. 37. The apparatus of claim 36, comprising a body forming part of a spray gun, wherein the filling surface is partially formed by the gun body. 37. The apparatus of claim 36, wherein the air flow path wall includes an outer surface that is triboelectrically charged with powder coating material striking the outer surface. 37. The apparatus of claim 36, comprising an external air passage formed through the filling surface. A triboelectric powder coating gun having an element comprising a triboelectric charging surface, Said element may be assembled into said gun in at least two different position orientations. 42. The gun of claim 41 wherein the element is rotated from a first position to a second position when assembled into the gun. 42. The gun of claim 41 wherein when assembled into the gun the direction of the element has been reversed from the first position to the second position. A triboelectric powder coating gun having an element comprising a triboelectric charging surface, Said element being connected to a holder to form an assembly of two members, said two member assemblies being assembled into said gun. 45. The gun of claim 44, wherein the holder comprises one or more air jet passages. 45. The method of claim 44, wherein the holder comprises one or more electrical ground members. A triboelectric powder coating gun having a triboelectric charging surface and an air jet impinging upon the charging surface, And a grounding member disposed upstream of said charging surface.