This invention relates to liquid dispensing apparatus and methods, and more particularly to airless liquid dispensing nozzles and methods.
Liquid dispensing systems include methods and apparatus using compressed air to atomize and shape a spray pattern for application to a substrate, and airless liquid dispensing systems in which liquid is forced through a nozzle, frequently at high fluid pressures, in an expanding fan-like sheet for atomization and application to a substrate, and also airless liquid dispensing systems in which liquid streams are directed from a nozzle for impingement and the formation of an expanding fan-like sheet in air.
Compressed air spraying and dispensing systems, while providing flexibility in operation and variability in the shape and angle of a spray pattern through the adjustment of compressed air jets from a plurality of orifices in the dispensing nozzle, suffers a serious disadvantage because of liquid spray particles and vapors which are blown away from the substrate and into the operating environment, frequently in violation of regulations for safe operation and protection of the environment.
Airless liquid dispensing systems suffer from a lack of flexibility during their operation. Airless liquid dispensing nozzles are designed to dispense liquid in a substantially constant and pre-selected angle of dispersion. Thus, if during operation it becomes desirable to change the width of liquid being dispensed from an airless operating system, it has been necessary to stop operation of the system, remove the nozzle being used, and replace it with a nozzle providing a more desirable angle of dispersion. This is inconvenient and time consuming, frequently requiring cleaning of the dispensing apparatus and nozzle.
The ability to vary the width of liquid being dispensed and applied to a substrate while continuing dispensing is of particular value in the application of plural component materials, such as polyesters in gel-coat, spray-up, and wet-out operations. In many such operations, the substrates and molds to which plural component materials, such as polyesters are being applied, present varied and complex shapes, frequently with channels and corners. The ability to apply, for example, polyester materials, in narrow widths to channels and corners, and in wide widths to larger, planar areas of a mold can assist the equipment operator in obtaining quick, complete and uniform coverage of the substrate or mold, and effective wet-out of reinforcing glass fibers or mat.
The invention provides an airless dispensing system in which liquids may be dispensed with variable included angles from substantially 0xc2x0 to as much as 50xc2x0-60xc2x0, by a simple adjustment made by a dispenser operator without ceasing operation or disassembling the dispenser apparatus.
In the invention, a variable angle liquid dispenser comprises a nozzle having a forward face with a dispensing orifice, a first passageway in the nozzle having a central axis intersecting the dispensing orifice, a plurality of angled second passageways in the nozzle, each angled second passageway having a central axis intersecting the dispensing orifice and the central axis of the first passageway, and a variable flow means adjustable to vary the flows of liquid entering the first passageway and the plurality of angled second passageways and to thereby vary the included angle of the liquid dispensed from the dispensing orifice.
Variable angle liquid dispensers of the invention can comprise two major elements, a nozzle body forming the forward face, the dispensing orifice, the first passageway and the plurality of intersecting angled second passageways, and variable flow means comprising a body forming an input passageway and carrying a variable flow splitter between the input passageway and the passageways of the nozzle body. In one preferred embodiment, the variable flow means comprises an assembly including a flow divider body forming an input passageway leading to the first passageway and the plurality of angled second passageways of the nozzle, and a valve member movably carried by the body to provide a variable flow division between the first passageways and plurality of angled second passageways of the nozzle. A preferred flow divider body can have a forward portion that is adapted for sealed engagement with the nozzle body, can provide a seal between the first passageway and the plurality of angled second passageways, and can provide a first feed passageway between the input passageway and the first passageway of the nozzle body, and a second feed passageway with an entrance opening between the input passageway and the angled second passageways of the nozzle body. The valve member can be threadably and rotatably carried by the flow splitter body and can be moved variably with respect to the entrance opening of the second feed passageway to provide a variable flow division between the first feed passageway and the second feed passageway, thereby varying the portions of the liquid flowing in the input passageway that flow through the first passageway and angled second passageways of the nozzle.
One preferred nozzle body of the invention includes a plurality of passageways converging adjacent the dispensing orifice. A first passageway lies on the central axis of the nozzle body and two angled second passageways have their central axes lying outboard in the same plane as the central axis of the first passageway, and converging with an included angle of from about 25xc2x0 to about 50xc2x0 between them. The first passageway has a diameter about 25% to about 75%, preferably about 70% of the diameters of the angled second passageways and a central axis bisects the central axes of the two outboard passageways.
In one preferred method of the invention, flows of the two components of a plural component material, such as a polyester resin and a catalyst therefor, are directed, under pressure, from their sources for mixing and dispensing from a nozzle having a plurality of passageways, at least two of the nozzle passageways being angled, with their central axes converging at an included angle, for example, from about 25xc2x0 to about 50xc2x0, and with a central nozzle passageway bisecting the converging central axes of the two angled outboard passageways. The flow rates of the two components are controlled to provide desired flow rates for proper mixing, for example, a catalyst flow rate about 0.5% to about 10% of the flow rate of a polyester resin, and the two liquid components catalyst are mixed, while flowing, and the flowing mixed liquid components are directed to the plurality of passageways of the nozzle and are dispensed from the nozzle as combined and mixing streams, forming an expanding, substantially planar stream of further mixed two-component material for application to a substrate. The flow of mixed two-component material is variably divided between the at least two angled outboard passageways and the central passageway, and the included angle of liquid dispensed from the dispensing nozzle is varied from substantially 0xc2x0 to about 50xc2x0, varying the width of mixed plural component material applied to the substrate.
Other features and advantages of the invention will be apparent from the attached drawings and more detailed description of the currently known best mode of the invention, which follows.