Patent Application
20180104854
The present application relates generally to fluid dispensing, and in particular, apparatus for mixing and dispensing materials, including, for example, an air-operable gun for mixing and dispensing thermoplastic and thermosetting plural component materials, such as urethane foams and coatings, polyurea, catalyzed polyesters, catalyzed epoxies and other chemical compositions that react rapidly upon mixing of the components thereof.
Polyurethane foam systems, for example, usually include component A, an isocyanate, and component B, a pre-formulated compound comprising a polyether resin, a catalyst, a surfactant and a blowing agent. Each component of the plural material is, by itself, generally stable, that is, each component does not cure or cross-link for several months or more, provided it is properly stored. However, mixing of component A and component B in proper concentrations initiates a chemical reaction that causes the components to begin to polymerize and generate heat which volatilizes the blowing agent and causes the polyurethane to foam, cure and cross-link. In one polyurethane system, water is used to combine with isocyanate to provide a carbon dioxide blowing agent; and in another polyurethane system, a fluorocarbon or Freon, which boils at about room temperature, provides the blowing agent. In this system, the blowing agent is trapped in the resin and acts in cooperation with the other constituents of the system to foam the polyurethane. Other systems may be such that the blowing agent is used to provide a cellular structure.
Usually cross-linking and curing of a plural component material is substantially completed in a matter of seconds. It is therefore desirable to mix the components in the dispensing device as close as is possible to the orifice from which the mix is ejected, that is, mixing of the several components of the compound should take place substantially contemporaneously with dispensing. Mixing the components of the plural component material with the dispensing device requires the apparatus operator to purge the residue of the mixed components from a mixing chamber and the orifice of the dispensing device so that the residue components do not chemically react and clog the chamber and the orifice, or in any other way prevent or inhibit dispensing of the plural component material.
Previously, the mixing and dispensing element—such as illustrated in FIGS. 1 & 2 from U.S. Pat. No. 7,527,172B2, which is incorporated by reference in its entirety—dispensed plural component materials in a consistently wide and uniform spray pattern (e.g., round pattern). This was done to effectively mix the plural components of the material and uniformly dispense the mixed plural component material in a wide, uniform and usable spray pattern. This round spray pattern of mixing for handheld and robotic spraying of ultra-fast and high-fasting two component materials was preferred due to its ability to stay cleaner in the exiting orifice and the surrounding exit surfaces. An off-ratio mixture of the plural components as a result of insufficient mixing and/or dispensing resulted in a mixed plural component lacking optimized properties, such as foam expansion, adhesion, etc. Further, off-ratio mixing of plural components may result in a mixed plural component that is dangerous to humans during dispensing.
Atomizing air streams are used for low pressure single stream materials that are easily manipulated. In high volume spraying applications, the velocity of the material exiting the orifice is so great that two impinging air streams don't have enough energy to flatten the spray pattern without massive volume of gas and/or extremely high pressures. Previously, a flat spray pattern with two component fast setting materials is generated using a mechanical structure to directly shape the spray pattern and then refine the pattern with air. This is done with a cats-eye type spray tip, but the problem with a cats-eye spray tip is that, when using ultra-fast setting two component materials, the trailing edges of the pattern results in poor material dispersion along the edge (e.g., the outside edges of the material are not clean due to such things as clumping, poor atomization, etc.). The mechanical solution requires the restrictive orifice of the stream to fully develop the spray pattern. However, this leads to the exiting orifice becoming clogged with the ultra-fast setting two component material.
For these aforementioned reasons, improvements to the mixing and dispensing element are desired.
According to at least one embodiment, a mixing and dispensing element generates a hydrostatically shaped pattern. The pattern is softened and/or widened with a minimal amount of impinging air stream(s), thus using less energy than traditional air atomizing guns. The softening and widening of the pattern also decreases the material thickness on the substrate by elongating the pattern along the impinging plane. The elongation of the spray pattern has the advantages of consistency of the thickness over length when compared to round and is sometime the preferred type of application.
According to at least one embodiment, a mixing and dispensing element generates a flat spray pattern without the use of a mechanical shearing spray tip.
According to another embodiment, a mixing and dispensing element includes a reciprocating mixing chamber that has communications with the ultra-fast setting two-component material and a purging source of high pressure gas, typically compressed air.
According to another embodiment, a mixing and dispensing element includes mixing chamber inlet ports that are in communication with a metered source of pressurized two-component material. The two materials may be introduced into a single exit orifice through two orifices that are perpendicular to the exit orifice.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
As indicated by
Compressed air delivered to the plural component mixing and dispensing assembly 10 through the air inlet 50 is put into a plurality of uses in the plural component mixing and dispensing assembly 10. When the valve 51 is in the “on” position, compressed air applied to the inlet end of the air inlet 50 is present at a first opening downstream of the on/off valve 51, and can flow through air passageways formed respectively in the connection portion 14 and actuator portion 15 of the housing 11.
Plural component mixing and dispensing assembly 10 includes shaping air assembly 400. Shaping air assembly 400 includes and air inlet 410 and a nozzle air manifold 420, which includes internal air passageways to impinging air outlet(s) 402 and/or adjustable air outlet(s) 404. Thus, nozzle air manifold 420 allows outlet(s) 402 and/or 404 to be positioned in any 360 degree array around dispensing nozzle 26. Air assembly 400 provides the impinging air stream(s) and/or adjustable air stream(s) necessary to shape the plural component material exiting at nozzle 26.
The plural component mixing and dispensing assembly uses a reciprocating mixing chamber 20 that has communications with the ultra-fast setting two-component material and a purging source of high pressure gas, typically compressed air. When in the dispensing position, the mixing chamber inlet ports are in communications with a metered source of pressurized two-component material. These two materials are introduced into a single exit orifice through two orifices that are perpendicular to the exit orifice. The two orifices that communicate the two component materials are typically the same size, but can vary slightly and represent a restriction that can be used to control flow. The area of the cross section of assembly passages 24 and 25 are substantially equal to the area of the mixing chamber (exit port) 23 (i.e., Area of 24+Area of 25=Area of 23, or within 30%, as a percentage of area). Assembly passages 24 and 25 are machined to be tangent with the center plane of the chamber 23 (exit orifice). Since chamber 23 is slightly larger then each of cross sections of assembly passages 24 and 25, an offset in assembly passages 24 and 25 results when machined perpendicular to chamber 23. The plural component materials are introduced at high pressures into the reciprocating mixing chamber, and the collision in chamber 23 creates turbulences that assist in the atomization of the mixture exiting the dispensing nozzle 26. The hydrostatically generated pattern from this mixing is considered to be a round spray pattern. When the two orifices are in communication with the purging source, the materials from 24 and 25 are purged from the mixing chamber with the high pressure gas.
Shaping air assembly 400 turns the hydrostatically generated two component spray pattern into a flat spray pattern. The invention utilizes the purge air 602 to surround the exiting material when dispensing, but (in most embodiments) the purge air 602 shuts off during the purging phase. The surrounding air 604 may soften the round spray pattern, but is predominately used to prevent the formation of eddies that are generated from the two impinging air streams. In many embodiments, the impinging air port(s) 402, providing impinging air stream(s) are located on a 105 degree angle from axis 23a. In alternative embodiments, the degree angle range from 75 degrees to 135 degrees from axis 23a. In the illustrated embodiment, two impinging air streams are provided. In most embodiments, the horizontal plane of the exiting stream impinges roughly 0.240″ from the exiting nozzle. In most embodiments, the impinging air port(s) are adjustable and move with the horizontal plane of the exiting material stream. This adjustability allows for the impinging air streams to move from either side of the vertical exiting material stream plane. Since this round spray pattern is hydrostatically generated, variation in the centerline of the material stream has been noticed and moveable, impinging air streams allow for this variation. Without being bound by theory, it believed that chamber 23 needs to be highly polished with no tool marks or drilling rotational mark on the inside surface. In some embodiments, additional adjustable shaping air port(s) 404 are provided air stream(s) to further shape and/or improve the dispersion qualities of the dispensed plural component material.
Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present invention, disclosure, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
In some embodiments, some component(s) or step(s) may be omitted for optimizing design, function, economy, or any combination thereof, and therefore, the omission of any such component(s) or step(s) shall be a negative limitation, if so claimed.
To the extent that any definitions, limitations, descriptions, preferred features, or preferred configurations provided in the instant Specification conflict with any part of U.S. Pat. No. 7,527,172B2 (which has been incorporated by reference in its entirety) the definitions, limitations, descriptions, preferred features, and preferred configurations in the instant Specification control.
The present disclosure is made using various embodiments to highlight various inventive aspects. Modifications can be made to the embodiments presented herein without departing from the scope of the invention. As such, the scope of the invention is not limited to the embodiments disclosed herein.
This application claims priority to U.S. Provisional Application No. 62/409,686 filed Oct. 18, 2016, entitled “FLAT FAN SPRAYING APPARATUS FOR THE DISPENSING OF ULTRA-HIGH FAST SET TWO COMPONENT MATERIALS”, the disclosure of which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62409686 | Oct 2016 | US |
