Plural component mixing and dispensing apparatus

In an air-operated plural component dispensing hand gun, including a sliding mixing and dispensing element that forms, with a pair of component inlet blocks, the valves controlling the mixing and dispensing of the plural component materials, the mixing and dispensing element includes a rearward part and a forward part which together form a mixing chamber, with admission passages for the plural components to be mixed in the rearward part and a dispensing orifice for mixed plural component material in the forward part, said mixing chamber having an enlarged portion in the rearward part.

FIELD OF THE INVENTION

The present invention relates to 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, catalyzed polyesters, catalyzed epoxies and other chemical compositions that react rapidly upon mixing of the components thereof.

BACKGROUND OF THE INVENTION

Polyurethane foam systems, for example, usually include component A, an isocyanate, and component B, a preformulated 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.

U.S. Pat. No. 3,799,403, issued to Richard O. Probst et al. discloses an apparatus for mixing and dispensing plural component materials, such as urethane foam materials. The Probst et al. patent discloses a hand gun which includes a mixing and dispensing element that is movable with respect to the housing of the device between a rearward position, at which the components of the plural component material are introduced into a mixing chamber in the mixing and dispensing element, appropriately mixed and then dispensed, and a forward position, at which the introduction of components into the mixing chamber is terminated, and air is introduced into the mixing chamber to substantially purge residue material from the mixing chamber and its cooperatively associated orifice.

In the gun disclosed by the Probst et al. patent, the movable mixing and dispensing element forms, in combination with a pair of connection blocks carried by the gun housing, the valves that control the mixing and dispensing of the plural component material. The connection blocks are connectible with the separate pressurized sources of the components of the plural component material and include outlet openings and carry plastic seal members around the outlet openings that interface with and seal against the sides of the mixing and dispensing orifice. The movable mixing and dispensing element includes an internal mixing chamber between its sides, a pair of admission openings, one between each side of the mixing and dispensing element and its internal mixing chamber, and a forward-most dispensing orifice connected with the mixing chamber. When the mixing and dispensing orifice is in its rearward position, the admission openings on each of its sides are aligned with the outlet openings of the connection blocks so the components of the plural component material can flow from their separate pressurized sources into the mixing chamber, where they are mixed and urged out of the dispensing orifice. When the mixing and dispensing element is in its forward position, the outlet openings of the connection blocks are blocked by the sides of the mixing and dispensing element, terminating the dispensation of mixed plural component materials. In the rearward position, the seals carried by the connection blocks confine the flows of the plural components to between the connection block-outlet openings and the admission openings of the mixing and dispensing element, and in the forward position, the seals prevent the plural components from flowing into the interface between the mixing and dispensing element and the connection blocks.

The housing of the device disclosed by the Probst et al. patent includes an air-operated piston/cylinder that is connected to the mixing and dispensing element to move it between its forward and rearward positions. A trigger on the handle of the hand gun controls the application of compressed air, through a four-way valve, to the portions of the cylinder on each side of a piston to move it forwardly and rearwardly within the cylinder, thus moving the mixing and dispensing element between its rearward mixing and dispensing position and its forward position at which the flow of plural component material is terminated and the mixing chamber is purged.

Plural component guns like those disclosed in the Probst et al. patent have been sold for almost 30 years by Glas-Craft, Inc., with the registered trademark PROBLER®.

More recently, such guns have incorporated an improved air actuator for controlling the flow of plural component material from the gun, as disclosed in U.S. Pat. No. 6,796,461 issued to Steven Sinders. In the improved air actuator, two serially connected pistons operating along a common axis within two separate cylinder portions of the housing drive the mixing and dispensing element back and forth along the common axis by the application of compressed air to the two separate cylinder portions of the housing.

Nevertheless, in such guns, it has been difficult to obtain consistently effective mixing of the plural component materials and wide and uniform spray patterns of the mixed plural component materials with the mixing and dispensing element of the apparatus.

BRIEF SUMMARY OF THE INVENTION

The invention provides a plural component apparatus in which plural component materials can be consistently and effectively mixed and dispensed in a consistently wide and uniform spray pattern by a mixing and dispensing element that may be more reliably and consistently manufactured and that effectively mixes the plural components of the material and uniformly dispenses the mixed plural component material in a wide, uniform and usable spray pattern.

In the invention, the mixing and dispensing element is provided with a mixing chamber having a rearward portion into which the plural components are admitted that is larger than the dispensing orifice at its forward end, and the mixing and dispensing element preferably includes a forward part with the dispensing orifice and a rearward part, with the mixing chamber extending through the forward and rearward parts of the mixing and dispensing element and with the larger rearward portion of the mixing chamber in the rearward part of the mixing and dispensing element.

This invention provides an apparatus for mixing the plural components of a plural component material and for dispensing the mixed plural component material that includes: a housing including a connection portion at its forward end; a mixing and dispensing element having a rearward part with opposed planar side portions, a forward part with a dispensing orifice, and a mixing chamber formed within the forward and rearward parts leading to the dispensing orifice, the rearward part of the mixing and dispensing element including a pair of passages for admission of the plural components into the mixing chamber, with one admission passage extending from one of the opposed planar sides and the other admission passage extending from the other of the opposed planar sides and with the rearward portion of mixing chamber in the rearward part of the mixing and dispensing element having a greater diameter than the diameters of the admission passages, said mixing and dispensing element being slidably carried by the connection portion of the housing and combining with the connection portion of the housing to form valves controlling the flow of the plural components through the admission passages, the mixing chamber and dispensing orifice; and an actuator for sliding the mixing and dispensing element between a first position blocking flow of the plural components into the mixing chamber and a second position allowing the plural components to flow into the mixing chamber for mixing and dispensation from the dispensing orifice.

The drawings and more detailed description of the preferred embodiment that follow comprises one example of the invention. Other embodiments of the invention will be apparent to those skilled in the art from the drawings and more detailed description that follows.

DETAILED DESCRIPTION OF THE CURRENTLY BEST KNOWN MODE OF THE INVENTION

FIGS. 1-12exemplify one preferred plural component dispensing hand gun10of the invention. As indicated byFIG. 1, the plural component dispensing hand gun10includes a housing11, a handle12extending from the housing at an angle, and a trigger13pivotally carried by the handle12. The hand gun10may be conveniently provided with a trigger guard13a.The housing11includes a connection portion14at its forward end and an actuator portion15at its rearward end. The words “forward” and “forwardly” in this description refer to the direction in which mixed plural component material is dispensed, and the terms “rearward” and “rearwardly” refer to the direction toward the back of the gun, which is illustrated inFIG. 2.

The connection portion of the housing14carries a pair of connection blocks16and17(seeFIG. 2). The connection blocks16and17provide connections for hoses that lead from the apparatus10to pressurized sources of each of the components of the plural component material. For example, connection block16carries a hose connection16afor a flexible hose leading to a source of component A of a plural component material, and connection block17carries a hose connection17afor a flexible hose leading to a source of component B of the plural component material. The connection blocks16and17can also carry valves17band16b(not shown) to block the flow of the plural components to the outlets18,19(FIG. 12) of the connection blocks. The connection blocks16and17thus provide the inlets for each of the components of the plural component material to the hand gun10, and are also sometimes referred to in this description as inlet blocks16and17.

In the hand gun10, the hose connections16aand17aproject upwardly and rearwardly from the connection blocks16and17so the hoses supplying the plural components from their respective separate sources of supply will be conveniently carried by the hand gun10over the handle12. The hand gun10is likewise connected with a source of compressed air by an air inlet means50of the invention, described in greater detail below. As illustrated byFIGS. 1 and 2, the air inlet means50also projects upwardly and rearwardly from the connection portion14of the housing so that an air hose connected thereto will be conveniently carried over the handle12of the gun. The air inlet means50can include a sliding on/off valve51so that the hand gun operator can remove air pressure from the gun when it is not in operation. With valve51turned off, the gun10cannot be operated. The on/off valve can also be used to control the flow of compressed air used to purge the mixing chamber23when the gun is in the non-dispensing position.

As best illustrated inFIG. 1, the connection portion14of the housing slidably carries a mixing and dispensing element20, and the actuator portion15of the housing11carries air actuator30to move the mixing and dispensing element20forwardly and rearwardly within the connection portion14of the housing.

FIGS. 3-11illustrate a preferred mixing and dispensing element20of the invention. As illustrated byFIGS. 3,9,11and12, the mixing and dispensing element20is formed with a pair of planar sides21and22, an internal mixing chamber23located between the planar sides21and22, and a pair of admission passages24and25, with admission passage24extending between planar sidewall21and the mixing chamber23, and with admission passage25extending between planar sidewall22and the mixing chamber23.

In the preferred mixing and dispensing element20of the invention, the mixing chamber20is formed with a cylindrical sidewall, for example, by a drilling operation, and the admission passages24and25are also preferably formed with cylindrical sidewalls, preferably by a drilling operation. It is important in the achievement of effective mixing and dispensation of the plural components of the material that the cylindrical sidewalls of the admission passages24and25are tangent to the cylindrical sidewall of the mixing chamber23where they intersect. To reliably achieve the desired tangency of the cylindrical sidewalls of the admission passages24and25and the mixing chamber23, the diameter of the cylindrical sidewall of the mixing chamber23, where it is intersected by the admission passages24,25, should be about 1.6 times or more the diameter of the admission passage24and25. With the diameter of the cylindrical mixing chamber23about 1.6 times the diameters of the admission passages24and25, the drill used to form the mixing chamber provides the mixing chamber with a central axis23athat remains more concentric with its intended central axis and provides effective offsets29(seeFIG. 11) between the central axes24a,25aof the admission passages24,25and the central axis23aof the mixing chamber23. With the cylindrical sidewalls of admission passages24and25tangent to the cylindrical sidewall of the mixing chamber23, each of the plural component materials flowing through the admission passages24and25flows smoothly from the admission passages24and25into the mixing chamber23with minimal turbulence, and the plural component materials are effectively mixed by the swirling action imposed on the flows by the cylindrical sidewall of the mixing chamber and the offsets29of the admission passages24and25, about 0.011 to about 0.013 inches. In the preferred mixing and dispensing element20, the diameters of admission passages24and25are preferably equal, and the cross-sectional area of the dispensing orifice26is preferably equal to the sum of the cross-sectional areas of the admission passages24and25. For example, in one preferred apparatus of the invention, the diameter of the admission passages24,25is about 0.043 inches, the diameter of the mixing chamber23, where the admission passages24,25intersect the mixing chamber, is about 0.069 inches, the diameter of the dispensing orifice26is preferably about 0.060 inches, and the offset29is about 0.011 inches.

As illustrated, for example, inFIGS. 3 and 4, a preferred mixing and dispensing element20comprises a forward element20aand a rearward element20b.The forward part20aof the mixing and dispensing element20is illustrated inFIGS. 5-7, and the rearward part20bof the mixing and dispensing element is illustrated inFIGS. 8-11. The admission passages24and25are formed in the rearward part20bof the mixing and dispensing element20, and the mixing chamber23extends from the admission passages24,25forwardly through both the rearward part20band the forward part20a,with the portion of the mixing chamber23that lies within the rearward part20bhaving a preferable diameter about 1.6 times, or more, the diameter of the admission passages24,25. The diameter of the mixing chamber that lies within the forward part20aof the mixing and dispensing element has the same diameter as the dispensing orifice26, as shown inFIG. 7, which is preferably about 1.4 times the diameter of the admission openings24,25. Thus, in the preferred mixing and dispensing element20, the preferred two-part construction results in a discontinuity23bin the mixing chamber23(seeFIG. 4), which creates turbulence that assists mixing the plural components together without adversely affecting the desired uniformity of the spray pattern formed as the mixed plural component material is dispensed from the dispensing orifice26. The manufacturing of the mixing and dispensing element20is made substantially more reliable and consistent with its preferred two-part construction because the portion of the mixing chamber23in the rearward part20bof the mixing and dispensing element is substantially shorter, further avoiding the departure of the central axis23aof the mixing chamber23from concentricity with its intended position and permitting tangency of the sidewalls of the mixing chamber23and admission passage24,25.

As illustrated byFIG. 12, the connection or inlet blocks16or17include outlet openings18and19, respectively, that are at the terminal ends of liquid passageways extending through the connection or inlet blocks16or17, respectively, from their respective hose connections16aand17a.A pair of seal elements27,28is carried by the connection blocks16and17around their outlet openings18and19, respectively, to seal the interfaces between the planar sides21and22of the mixing and dispensing element20and the adjoining side surfaces of the connection/inlet blocks16and17.

When the air actuator30moves the mixing and dispensing element20rearwardly, it comes to rest in a dispensing position in which the admission openings24,25of the mixing and dispensing element20are aligned with the outlets18,19of the connection blocks16,17, illustrated byFIG. 12, and the pressurized sources of the components of the plural component material can urge the components of the plural component material, which are connected to the hose connections16aand17a,through the admission openings24and25into the mixing chamber23for mixing and dispensation from the dispensing orifice26of the mixing and dispensing element20. When the air actuator30moves the mixing and dispensing element20forwardly within the connection portion14of the housing11, the admission openings24,25of the mixing and dispensing element20are moved out of alignment with the outlet openings18,19of the connection blocks16,17, and the planar sides21,22of the mixing and dispensing element20block the outlet openings18,19, which are sealed shut by the planar sides21,22of the mixing and dispensing element20and the seal elements27,28. Thus, the mixing and dispensing element20not only provides a means for mixing and dispensing plural component materials, it also provides a valve means for controlling their flow from the hand gun10.

Compressed air delivered to the gun through the air inlet means50is put into a plurality of uses in the gun10. When the valve51is in the “on” position, compressed air applied to the inlet end52of the air inlet means50is present at a first opening53downstream of the on/off valve51, and can flow through air passageways61and62formed respectively in the connection portion14and actuator portion15of the housing11for connection with air passageways in the handle12, and for control by a three-way valve70, which is operated by the trigger13pivotally connected with the handle. When the trigger13is in the unpulled position, the chambers of the three-way valve70connect compressed air from passageway62to the air actuator30to force the mixing and dispensing element20forwardly to the non-dispensing position illustrated inFIG. 1, and when the trigger is pulled rearwardly by an apparatus operator, the chambers of the three-way valve apply compressed air to the air actuator30to move the mixing and dispensing element20to its rearward dispensing position illustrated inFIG. 12. The passageways leading from the three-way valve through the handle12and the actuator portion15of the housing to the air actuator30are not shown but will be apparent to those skilled in the art from the description of the air actuator.

The use of metal seal elements27,28, preferably hardened stainless steel, greatly reduces the wear on the seal elements, the possibility of a seal failure, and substantially increases the time between replacement of the seal elements, reducing the maintenance costs of the hand gun10. Unfortunately, the use of metal seal elements27,28substantially increases the force needed to slide the mixing and dispensing element20between its dispensing and non-dispensing positions. The use of metal seals almost doubles the force needed to slide the mixing and dispensing element20between its dispensing and non-dispensing positions in operation of the hand gun, and would, unfortunately require the actuator portion of the housing to almost double in size in order for the pressure of compressed air that is usually available in a manufacturing operation to develop sufficient force to reliably move the mixing and dispensing element20between its dispensing and non-dispensing positions. Such an increase in size and the accompanying increase in weight would undesirably reduce the maneuverability of the hand gun and result in increased fatigue of hand gun operators.

As illustrated byFIG. 1, the hand gun10of the invention does not include an actuator portion of the housing having increased size and weight, because the air actuator comprises to serially connected pistons31,32operating along a common axis within two separate cylinder portions33,34of the housing11. The serially connected pistons31,32are connected to the mixing and dispensing element20by a rod35, extending forwardly through the actuator portion15of the housing with which it is sealed. In the operation of the hand gun10, the two serially connected pistons31,32are driven in the same direction along a common axis by the application of compressed air to the two separate cylinder portions33,34, as a result of the operation of trigger13and three-way valve70. When the trigger13is in the unpulled position, the three-way valve70applies compressed air within the two separate cylinder portions33,34rearwardly of the pistons31,32, moving the mixing and dispensing element20to its non-dispensing position illustrated inFIG. 1. When the trigger13is pulled, it moves the three-way valve70to a position in which compressed air is applied to the two separate cylinder portions33,34forwardly of the pistons31,32to move the pistons31,32rearwardly within their separate cylinder portions33,34, and to move the mixing and dispensing element20rearwardly to its dispensing position, as illustrated inFIG. 12. Thus, the force generated by the air actuator and applied to the mixing and dispensing element20can be substantially doubled by the forces exerted on the two serially connected pistons by the compressed air, thus obviating the need to increase the size and weight of the hand gun10to overcome the substantial friction imposed on the gun by the metal seals27,28.

In the preferred embodiment of the hand gun10, illustrated in the figures, and particularly inFIG. 1, the actuator portion15is provided with a cylinder-forming wall40that has a smaller diameter forward portion, and a larger diameter rearward portion. A dual piston element39is slidably carried within the cylinder-forming walls, and extends forwardly through rod35for connection with the mixing and dispensing element20. The dual piston element39comprises an assembly including a forward piston32and a rearward piston31, which may be slidably sealed with the smaller diameter forward portion, and the larger diameter rearward portion, respectively, of the cylinder-forming wall40, and a cylinder-dividing element36is slidably carried by a connecting rod37extending between the forward and rearward pistons32and31. With the dual piston element39in place within the large and smaller cylinder-forming walls, the cylinder-dividing element36is sealed with the larger diameter portion of the cylinder-forming wall, and is seated and held stationary at the wall formed by the transition between the smaller diameter portion and larger diameter portion of the cylinder-forming wall40. As a result, the actuator portion15and the cavity formed by the cylinder-forming wall40is divided into the first cylinder portion34with the forward piston32being drivable therein, and a second cylinder portion33with the rearward piston31being drivable therein, and the driving forces generated on the pistons31,32by the compressed air are added in sliding the mixing and dispensing element20between its forward and rearward positions. For example, in a preferred hand gun of the invention, the smaller diameter cylinder has a diameter of 1⅜ inches, and a larger diameter cylinder has a diameter of 1½ inches, providing a combined area upon which compressed air acts equal to almost 3¼ square inches, permitting factory air to exert several hundred pounds of force to move the mixing and dispensing element20between its dispensing and non-dispensing positions.

As noted earlier, compressed air admitted to the inlet end of52of the air inlet means50is put to a plurality of uses in the gun. In addition to operation of the two serially connected pistons31,32, as a result of operation of the trigger13and the three-way valve70, compressed air is also directed from the air inlet means50through passageways including passageway63, formed in the connection portion14of the housing11, to an air chamber64(shown inFIG. 12) formed by a cylindrical cavity portion65within the actuator portion14of the housing11in communication with the sides21,22of the mixing and dispensing element20, which has a square cross-section in the preferred embodiment. When the mixing and dispensing element20is in its forward non-dispensing position, the admission openings24,25of the mixing and dispensing element20are moved from within seal elements27,28and are located within the air chamber64so that compressed air applied to the air chamber64will be forced through the admission openings24,25, the mixing chamber23, and the dispensing orifice26, expelling residue of the plural component material therefrom so it does not cure and prevent or inhibit further operation of the gun10. The flow of purging air through passageway63, the air chamber64formed in connection portion14of the housing, the admission openings24,25and the mixing chamber23and dispensing orifice26may be controlled by adjustment of the on/off valve51, or other valve between the end of the air inlet means50and passageway63.

As shown inFIG. 1, the air inlet means50is threadedly connected to an air inlet passage54, formed in the connection portion14of the housing11. The air inlet54and the connection portion14of the housing carry a ball check valve formed by a ball55and a spring56that urges the ball55into a sealing position against the end of the air inlet means50if compressed air is not present at the first opening53of the air inlet means50. The ball check valve formed by ball55, spring56and the end of the air inlet means50is in the closed position when compressed air is not present at the first orifice53, and thus prevents plural component material from flowing backwardly through the passageway63into the passageways61,62and into the three-way valve70and air actuator30in the event the seals27,28between the mixing and dispensing element20and the connection blocks16and17fail, or in the event the connection blocks16and17are not properly seated or have become defective.

As known in the art, the components of the gun10are fabricated from any suitable wear-resistant material that is chemically inert with respect to the components of plural component materials being dispensed. Suitable materials include aluminum, aluminum alloys, steel, and strong, durable plastics, such as acetyl resin, glass-filled epoxy, glass-filled nylon and the like, the preferable materials being light-weight metals, such as aluminum.

Thus, preferred embodiments of the gun10can include air inlet means50for connecting a source of compressed air with compressed air inlet54that is formed in the connection portion14of the housing11, and the compressed air inlet means can comprise a manually operated off/on valve51between the source of compressed air and the compressed air inlet54, a first opening53in communication with air passageways61,62leading to a three-way valve70and an air actuator30, and a second opening63in communication with an air chamber formed in the connection portion14of the housing for the passage of compressed air to expel mixed plural component material residue from the mixing chamber23of the mixing and dispensing element20. In the air inlet means50, a ball check valve is provided between the first and second openings53,63, which is opened in the presence of compressed air at the first opening53, and closed in the absence of compressed air at the first opening53, thereby preventing plural component air from flowing back into the first opening53and the air passageways61,62leading to the three-way valve70and the air operated actuators30.

The foregoing detailed description and the drawings should be regarded as illustrative rather than limiting, and it should be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.