Powder coating booth containment structure

Abstract

A powder coating booth containment structure including first and second canopy halves, each of which is a substantially nonconductive, seamless, structural composite to substantially reduce oversprayed powder particle adhesion to the booth inner surfaces. The composite canopy halves, when assembled into a spray booth additionally including either a floor or a utility base and one or a pair of end units in the form of aperture bulkheads, vestibules, or a combination of both, are structurally sufficiently strong that no external support frame is required. The composite canopy halves can each include sidewall and ceiling portions, in an embodiment, that can be connected to a floor. In another embodiment, the canopy halves each additionally include a floor portion such that they may be connected together at a floor edge and placed atop a utility base. They may be connected to the utility base. In another embodiment, the canopy halves may each further include an integral end or ends, comprising aperture bulkhead or vestibule-type end portions. Methods of assembling these embodiments are also provided that require less time than for known powder coating spray booth assembly.

Description

FIELD OF THE INVENTION [0001] The present invention relates to powder coating spray booths used for containing powder particles that do not adhere to articles intended to be coated. More specifically, the invention relates to a substantially non-conductive spray booth comprising a pair of self-supporting, one-piece, composite, seamless canopy booth halves. BACKGROUND OF THE INVENTION [0002] Powder spray booths for electrostatic powder coating operations are well known and are used for environmental purposes to contain oversprayed powder coating material that does not adhere to the target article. In addition, the booth facilitates collection of the oversprayed powder material which is often recycled back into the application system. In an electrostatic powder coating operation, the powder particles are charged, such as by one or more high voltage charging electrodes on an electrostatic powder spray application device, such as a spray gun, and the parts are grounded. The difference i...

AI Technical Summary

Benefits of technology

[0012] The invention herein provides for an improved powder coating spray booth. In one embodiment, which is well-suited for retrofitting existing powder coating spray booths, the invention herein comprises a pair of opposed canopy halves that each have a sidewall and a ceiling portion that can be connected to each other through a radius. This radius serves to reduce color change times and functions as a torsional support element for the wall and ceiling surfaces. Each canopy half is a seamless, composite, unitary structure that can connect with an existing booth floor and with the existing booth vestibule and / or aperture end or ends, and can be separated at the top providing for a narrow overhead conveyor slot opening typical in electrostatic powder coating spray booths. The canopy halves are each self-supporting, which means they can be assembled together with an existing floor and vestibule end or ends and no external frame is required to support the powder coating spray booth of the present invention. By removing the external frame typical of all known powder coating spray booths and constructing the inventive booth canopies from nonconductive materials, the improved booth can be assembled much quicker and is more nonconductive to oversprayed electrostatic powder particles. Thus, less oversprayed particle coating material adheres to the ceiling and walls of the inventive booth. Of course, it can be appreciated by those skilled in the art that this improved embodiment of the invention can also work equally well with a new floor or vestibule end.

[0013] The canopy halves of the present invention are made from a number of non-conductive materials that are loaded onto a set-up tool having a smooth surface that has been prepared with a release agent. All the materials can be non-metallic. Typical non-conductive layers can include a first, optional, sprayed on layer of gel-coat, which is an unreinforced resin layer that is allowed to set or cure. This first layer of the booth canopy halves serves as the booth interior surface. It may be pigmented, such as with white pigment, for aesthetics and functional reasons, such as to give a clean smooth appearance and to help the worker identify the location of oversprayed powder coating material within the spray booth during booth cleaning for a color change. The specific resin material chosen is non-conductive, ultraviolet light stable and impervious to moisture adsorption, even over time. This layer can be followed by an optional layer of chopped strand mat which is a random orientation glass fiber product. Also included are three necessary layers including a core having a suitable thickness to give the canopy halves structural rigidity and a first and a second layer of knitted glass fabric sandwiching the core for strength. One or more handling tabs can be placed within the lay-up of the composite canopy halves, such as at perimeter edges or at the outer radius between the ceiling and wall portions, to assist with handling the composite canopy halves during lifting the newly formed canopy half from the tool, secondary operations in finishing the canopy half, storage, transportation and booth assembly at a production site. These handling tabs can be simple nonconductive lugs, such as of similar composite construction and already cured before placement in the lay-up.

[0015] The cured canopy halves can be lifted off the set-up tool, trimmed and have their access and other operational openings cut. A final exterior layer of gelcoat, again a pigmented or unpigmented unreinforced resin layer can be applied for aesthetics and to further inhibit moisture adsorption over time and during shipping to the production site. Alternatively, an epoxy-based barrier coat can be applied in place of the gelcoat for the same purposes. Either coating layer on the part exterior serves to effectively seal the part from the elements during shipping and fills in any pinholes that may be present on the exterior or trimmed surfaces of the composite canopy half.

[0016] In accordance with another aspect of the invention, each canopy half of the inventive spray booth can be essentially mirror images of each other and produced with the same tooling. As such, they can be shipped to the production site in a nested configuration, minimizing shipping space. In addition, each canopy half can have one or more access and other operational openings which are positioned in the canopy half during construction by measured placement of the core material, essentially removing the core material where an access opening is desired. A flange around the perimeters of the canopy halves can be provided by tapering the core layer to zero thickness and creating a flange from the remaining layers, as described above. These perimeter flanges can be used for connecting the floor and the booth ends, which can be narrowed vestibules that are known to help retain oversprayed powder coating material inside the spray booth. Alternatively, one or both of the vestibule ends can be replaced with aperture bulkheads that establish a part opening in the booth end or ends.

[0021] In another inventive powder coating booth embodiment, a nonconductive, self-supporting, spray booth canopy is provided that includes a pair of composite canopy halves each having a wall and ceiling portion and at least one integral vestibule end half, or aperture bulkhead half. In addition, each canopy half can have an integral floor portion with the assembled canopy halves requiring a suitable utility base section for connecting thereto. The integral floor portions of either half, or both halves may be sloped to facilitate oversprayed powder coating material collection in one or more collection troughs located below the booth floor. Otherwise, a floor is provided to connect with the canopy halves at perimeter wall and vestibule or aperture bulked edges. An overhead conveyor slot opening for passing parts through the booth can be provided. The canopy halves are nonconductive for mininizing the adherence of electrostatically charged oversprayed powder coating material to the booth interior surfaces.

Problems solved by technology

Cleaning a powder coating spray booth can be a labor-intensive effort.

During extended powder coating runs, the amount of oversprayed powder accumulated within the booth can impact color change time.

Seams between booth panels and recessed ledges, such as where access doors or automatic or manual spray application devices may be located, are typically hard to clean areas and tend to hold concentrations of oversprayed powder coating material that could present a contamination risk after a color change.

These seams require much effort and cost to achieve a virtually uninterrupted, seamless surface.

In addition, known powder coating spray booths have numerous features that reduce operational efficiencies.

In booths using panel members connected with each other and supported by an external frame, numerous seams exist throughout the booth interior that entrap oversprayed powder coating material, thereby making the booth harder to clean during a color change or routine booth maintenance.

Even if otherwise angled or curved toward the floor from the typically vertical sidewalls, oversprayed powder coating material still tends to accumulate in these areas, thus making them more difficult to clean, as well.

In addition to the reduced spray booth operating efficiencies due to powder coating material adhesion as a result of electrostatics and booth design, booths constructed with frames and panel members and booths made of thermoformed plastics increase assembly and maintenance times, thus further reducing operational efficiencies.

Installation of booths that require external frames for structural support of any kind increase booth installation time.

Booths having multiple panels forming the walls, ceiling and floors further increase assembly time, and at best result in a semi-rigid enclosure that falls short of a preferred robust containment envelope that is suitable for industrial environments.

Maintenance of thermoformed plastic booths is also a concern and has a negative impact on efficient booth operations.

With thermoformed plastic booth materials, workers and parts can accidentally nick and scratch the booth internal surfaces rather easily.

These surface imperfections and discontinuities are hard to clean areas and act to entrap powder coating material therein.

In addition to increased cleaning times, maintenance of the booth to remove the scratches and nicks are time-intensive at best, and results of repair activities cannot restore a surface to original condition.

Both the ease at which thermoformed plastic booths can be scratched and the time involved in repairing them make thermoformed plastic booths less than ideal as a powder coating booth material.

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