Material dispensing system with gas removal

A material dispensing system can comprise a first and second supply container housing a first and second material, respectively, comprising a first and second fluid, respectively; a first and second metering cylinder fluidly connected to the first and second supply container, respectively, the second metering cylinder configured to move from a first to a second stroke position in unison with the first metering cylinder; a dispensing head configured to receive a first and second liquid of the first and second fluids, respectively; a first recycling valve positioned between the first metering cylinder and the dispensing head; and a second recycling valve positioned between the second metering cylinder and the dispensing head, the first and second recirculating valves configured to draw a portion of the first and second fluids back into the first and second supply containers, respectively, in an open position.

TECHNICAL FIELD

Field of Use

This disclosure relates to systems for dispensing fluids in a manufacturing environment. More specifically, this disclosure relates to systems for accurately dispensing multi-component potting materials or casting resins.

Related Art

A material dispensing system can be used in the manufacturing and sealing of electrical components, the fabrication of lightweight resin-impregnated composite structures, and in other components and processes. It can be advantageous to mix different materials immediately before using the different materials to achieve desirable properties in a dispensed mixture. Some materials must be mixed at precise ratios in order to form the desired properties in the dispensed mixture.

SUMMARY

In one aspect, disclosed is a material dispensing system comprising a first supply container housing a first material, the first material comprising a first fluid; a second supply container housing a second material, the second material comprising a second fluid; a first metering cylinder fluidly connected to the first supply container; a second metering cylinder fluidly connected to the second supply container, the second metering cylinder connected to the first metering cylinder, the second metering cylinder configured to move from a first stroke position to a second stroke position in unison with the first metering cylinder; a dispensing head configured to receive a first liquid of the first fluid and a second liquid of the second fluid; a first recycling valve positioned between the first metering cylinder and the dispensing head, the first recycling valve configured to draw a portion of the first fluid back into the first supply container in an open position of the first recycling valve; and a second recycling valve positioned between the second metering cylinder and the dispensing head, the second recycling valve configured to draw a portion of the second fluid back into the second supply container in an open position of the second recycling valve.

In a further aspect, disclosed is a method of dispensing a mixture of two fluids, the method comprising drawing a first fluid from a first supply source, the first fluid comprising a first liquid; drawing a second fluid from a second supply source, the second fluid comprising a second liquid; moving a first metering cylinder and a second metering cylinder in unison from a first stroke position to a second stroke position, the first metering cylinder fluidly connected to the first supply source and the second metering cylinder fluidly connected to the second supply source; simultaneously dispensing each of the first fluid and the second fluid from a dispensing head fluidly connected to the first metering cylinder with a first fluid dispensing connection and to the second metering cylinder with a second fluid dispensing connection; automatically closing the dispensing head to stop dispensing of each of the first fluid and the second fluid based on a position of each of the first metering cylinder and the second metering cylinder; drawing a portion of the first fluid back into the first supply source; and drawing a portion of the second fluid back into the second supply source.

In yet a further aspect, disclosed is a method of dispensing a material, the method comprising: drawing the material from a supply source, the material comprising a liquid; moving a metering cylinder from a first stroke position to a second stroke position, the metering cylinder fluidly connected to the supply source; dispensing the fluid from a dispensing head fluidly connected to the metering cylinder; automatically closing the dispensing head to stop dispensing of the fluid based on a position of the metering cylinder; and drawing a portion of the material back into the supply source.

DETAILED DESCRIPTION

The following description is provided as an enabling teaching of the present devices, systems, and/or methods in their best, currently known aspect. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects described herein, while still obtaining the beneficial results of the present disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present disclosure are possible and can even be desirable in certain circumstances and are a part of the present disclosure. Thus, the following description is provided as illustrative of the principles of the present disclosure and not in limitation thereof.

As used throughout, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a quantity of one of a particular element can comprise two or more such elements unless the context indicates otherwise. In addition, any of the elements described herein can be a first such element, a second such element, and so forth (e.g., a first widget and a second widget, even if only a “widget” is referenced).

The word “or” as used herein means any one member of a particular list and also comprises any combination of members of that list.

As disclosed herein, any “connection” can include a mechanical connection.

To simplify the description of various elements disclosed herein, the conventions of “left,” “right,” “front,” “rear,” “top,” “bottom,” “upper,” “lower,” “inside,” “outside,” “inboard,” “outboard,” “horizontal,” and/or “vertical” may be referenced. Unless stated otherwise, “front” describes that end of the system nearest to and occupied by a user of the system standing in front of and facing the dispensing head during its intended use; “rear” is that end of the system that is opposite or distal the front; “left” is that which is to the left of or facing left from the same user while in the same position and orientation; and “right” is that which is to the right of or facing right from that same person while in the same position and orientation. “Horizontal” or “horizontal orientation” describes that which is in a plane extending from left to right and aligned with the horizon. “Vertical” or “vertical orientation” describes that which is in a plane that is angled at 90 degrees to the horizontal.

In one aspect, a multi-component material dispensing system and associated methods, systems, devices, and various apparatuses are disclosed herein. In one aspect, the multi-component material dispensing system can comprise recycling valves.

As shown inFIG. 1, a material dispensing system100can comprise a first supply or supply source, which can comprise a first supply container111, and a second supply or supply source, which can comprise a second supply container121. The first supply container111and the second supply container121can be configured to store and incrementally supply a first material81(shown inFIG. 11) and a second material82(shown inFIG. 11), respectively. The first material81and the second material82can comprise a first fluid and a second fluid, respectfully, such that each of the first material81and the second material82can flow through the system100towards a dispensing head133, which can comprise a dispensing valve. The first material81and the second material82—and therefore also the first fluid and the second fluid—can comprise a first liquid and a second liquid, respectfully.

As a fluid, each of the first material81and the second material82can comprise both liquid and gaseous portions. Such liquid and gaseous portions need not be different phases of the same substance. For example and without limitation, in some aspects, the liquid portions of the first material81and the second material82can be an epoxy resin and an epoxy hardener, respectively, while the gaseous portions of the first material81and the second material82can be or can at least comprise a gas such as nitrogen. In other aspects, a two-component mixture83(shown inFIG. 11)—and, in other aspects, the multi-component mixture—dispensed by the system can comprise any other desired mixture including, for example and without limitation, an adhesive, a urethane material, a silicone material, or a polysulfide, and the mixture can be blended with “fillers” such as, for example and without limitation, plastic, aggregate, or sand. In other aspects, the gaseous portions of the first material81and the second material82can comprise air or any other gas. In other aspects, small amounts of moisture can be trapped in either the first material81or the second material82. Any such moisture can subsequently be “boiled off” during, for example and without limitation, vacuum degassing of the material as described below. In some aspects, portions of the system100used for distributing and metering the second material82can be removed or isolated and the system100can be used to dispense and degas a single material such as the material81.

The system100can comprise a drier112, which can be attached and fluidly connected to the first supply container111. Likewise, the system100can comprise a drier122, which can be attached and fluidly connected to the second supply container121. In some aspects, either of the driers112,122can be a desiccant air vent drier. Each of the driers112,122can facilitate the removal of moisture from the first supply container111and the second supply container121, respectively, by drawing moisture into itself to be absorbed into a moisture-wicking desiccant material. In other aspects, another type of drier or drying agent can be used.

The system100can comprise a first transfer pump113, which can be attached and fluidly connected to the first supply container111. Likewise, the system100can comprise a second transfer pump123, which can be attached and fluidly connected to the second supply container121. In some aspects, either of the first transfer pump113or the second transfer pump123can be a liquid pneumatic pump. In other aspects, either of the first transfer pump113or the second transfer pump123can be another type of pump.

The system100can comprise a first preparation tank114and a second preparation tank124. The first preparation tank114and the second preparation tank124can be fluidly connected to the first supply container111and the second supply container121, respectively. Passage of the first material81and the second material82from the first supply container121to the first preparation tank114and from the second supply container121to the second preparation tank124, respectively, can be regulated with a first loading valve2131(shown inFIG. 2) and a second loading valve2231(also shown inFIG. 2), respectively.

The system100can comprise a first agitator115, which can be secured to the first preparation tank114, and a second agitator125, which can be secured to the second preparation tank124. In some aspects, either of the first agitator115and the second agitator125can be a mixing agitator. In other aspects, either of the first agitator115and the second agitator125can be another type of agitator. Each of the first agitator115and the second agitator125can facilitate even mixing of the first material81inside the first preparation tank114and the second material82inside the second preparation tank124, respectively.

The system100can comprise a first delivery pump116, which can be fluidly connected to the first preparation tank114, and a second delivery pump126, which can be fluidly connected to the second preparation tank124. In some aspects, either of the first delivery pump116and the second delivery pump126can be a diaphragm pump. In other aspects, either of the first delivery pump116and the second delivery pump126can be another kind of pump. As shown, the first delivery pump116can be a diaphragm pump and the second delivery pump126can be a reciprocating pneumatic motor fluid pump such as, for example and without limitation, either of those described in U.S. Pat. Nos. 5,586,480 and 5,647,737.

The system100can comprise a first delivery pipe117, which can be fluidly connected to the first delivery pump116, and a second delivery pipe127, which can be fluidly connected to the second delivery pump126. The first delivery pipe117and the second delivery pipe127can transport the first material81and the second material82, respectively, to the metering cylinder assembly400, to which each of the first delivery pipe117and the second delivery pipe127can be fluidly connected.

As shown, the metering cylinder assembly400can comprise a first metering cylinder141, which can be fluidly connected to the first supply container111, and a second metering cylinder142, which can be fluidly connected to the second supply container121. The second metering cylinder142can be connected to the first metering cylinder141. The metering cylinder assembly400can comprise a shuttle-valve assembly150, which can operate—simultaneously as desired—various valves of the metering cylinder assembly400to transport the first material81and the second material81as desired, as will be described below. A control system160can be operatively connected to and in electrical or electronic communication with and control components of the system100such as, for example and without limitation, the pumps113,123,116,126and the dispensing head133and can receive inputs from components of the system such as, for example and without limitation, an encoder161or other component functioning as a position sensor or a foot pedal (not shown), which can cause the control system160to open or close the dispensing head133to start or stop dispensing the mixture83(shown inFIG. 11) of the materials81,82. The control system160can effectively control the operation of various other aspects of the system100including components such as, for example and without limitation, a first recycling valve171and a second recycling valve172. As an input to a controller such as the control system160, the encoder161, which be a linear position encoder, can signal movement or a position of a rod410(shown inFIG. 4) of the metering cylinder assembly400and thereby signal a stroke position of each of the first metering cylinder141and the second metering cylinder142.

The system100can comprise a first return pipe119and a second return pipe129. The first return pipe119can fluidly connect the metering cylinder assembly400to the first preparation tank114via a first exit tee118, and the second return pipe129can fluidly connect the metering cylinder assembly400to the second preparation tank124via a second exit tee128. The first recycling valve171can regulate flow of the first material81from the metering cylinder assembly400to the first preparation tank114, and the second recycling valve172can regulate flow of the second material82from the metering cylinder assembly400to the second preparation tank124. As shown inFIG. 1, each of the recycling valve171and the recycling valve172can be maintained in a closed position in which movement of the first material81into the first return pipe119and movement of the second material82into the second return pipe129, respectively, is blocked. As shown, each portion of the first material81and the second material82that is recycled can be returned to the respective preparation tanks114,124proximate to a topmost level of the respective material81,82inside the respective preparation tanks114,124, a level or position within the preparation tank114,124which can be the farthest away from the bottom outlet of the preparation tank114,124through which the material81,82can be fed into the delivery pump116,126. Any material81,82that is recycled can be separated into liquid and gaseous portions as it is dispersed or vented back onto the top of the material81,82in the preparation tank114,124before being subsequently dispensed.

The dispensing head133can comprise the dispensing valve and a dispensing nozzle130, which can be a dispensing mixing nozzle. A first feeder pipe131and a second feeder pipe132can transport the first material81and the second material82, respectively, from the metering cylinder assembly400to the dispensing head133via the first exit tee118and the second exit tee128, respectively.

As shown inFIG. 2, a first loading pipe2132can fluidly connect the first supply container111to the first preparation tank114and thereby transport the first material81between the first supply container111and the first preparation tank114, the flow of which can again be regulated by the first loading valve2131. Likewise, a second loading pipe2232can fluidly connect the second supply container121to the second preparation tank124and thereby transport the second material82between the second supply container121and the second preparation tank124, the flow of which can again be regulated by the second loading valve2231.

The first preparation tank114can comprise a first top end2150, a first inspection port2151, a drier2152, a first drier valve2153, a first extraction valve2154, and a first blanket valve2155. Similarly, the second preparation tank124can comprise a second top end2250, a second inspection port2251, a drier2252, a second drier valve2253, a second extraction valve2254, and a second blanket valve2255.

The first inspection port2151and the second inspection port2251can be mounted in or secured to the first top end2150and the second top end2250, respectively. Either of the first inspection port2151and the second inspection port2251can comprise a glass or other transparent material to facilitate viewing of the first material81and the second material82inside the first preparation tank114and the second preparation tank124, respectively.

The first drier2152and the second drier2252can be fluidly connected to the first preparation tank114and the second preparation tank124, respectively, and the respective drier valves2153,2253can regulate flow of fluid and/or moisture between each respective drier2152,2252and the respective preparation tanks114,124. Each of the driers2152,2252can facilitate the removal of moisture from the first preparation tank114and the second preparation tank124, respectively, by drawing moisture into itself to be absorbed into a moisture-wicking desiccant material. In other aspects, another type of drier can be used.

Either of the first extraction valve2154and the second extraction valve2254can be a liquid tank vacuum degassing extraction valve and can facilitate the removal of gas from the first preparation tank114and the second preparation tank124, respectively. In other aspects, either of the first extraction valve2154and the second extraction valve2254can have a different use.

Either of the first blanket valve2155and the second blanket valve2255can be an inert gas blanket valve and can facilitate the introduction of an inert gas such as nitrogen into a top of the first preparation tank114and the second preparation tank124, respectively, including when the respective material81,82is pulled from the respective preparation tank114,124, thereby increase the amount of free volume inside the respective preparation tank114,124with which the inert gas can be introduced.

The first preparation tank114and the second preparation tank124, respectively, can comprise a low level sensor2143,2243, respectively, and a high level sensor2144,2244, respectively. Each of the low level sensors2143,2243and the high level sensors2144,2244can facilitate monitoring of the level of the respective material81,82inside the respective preparation tank114,124and, as needed, refilling of the first preparation tank114and the second preparation tank124from the first supply container111and the second supply container121by operation of the first transfer pump113and the second transfer pump123, respectively.

The first preparation tank114and the second preparation tank124, respectively, can comprise a first bottom transfer pipe2141and a second bottom transfer pipe2241, respectively. The first preparation tank114and the second preparation tank124, respectively, can comprise a first bottom transfer valve2142and a second bottom transfer valve2242. The first bottom transfer valve2142and the second bottom transfer valve2242can regulate flow of the respective material81,82through the first bottom transfer pipe2141and the second bottom transfer pipe2241from the first preparation tank114and the second preparation tank124, respectively, to the first delivery pump116and the second delivery pump126, respectively. At either of the first delivery pump116and the second delivery pump126, respectively, a first pressure regulator2161and a second pressure regulator2261, respectively, can facilitate maintenance of a desired pressure on either side of the respective delivery pump116,126. As shown, the first pressure regulator2161and the second pressure regulator2261, respectively, can facilitate maintenance of a desired pressure on the side of the respective delivery pump116,126nearest the dispensing nozzle130to help ensure a desired supply of the respective material81,82to the metering cylinder assembly400and ultimately the dispensing nozzle130.

As shown inFIG. 2, each of the recycling valve171and the recycling valve172can be maintained in an open position in which movement of the first material81into the first return pipe119and movement of the second material82into the second return pipe129, respectively, is allowed.

As shown inFIG. 3, the system100can further comprise a recycling controller363. In some aspects, as shown, the recycling controller363can be physically and electronically separate from the control system160. In such aspects, the recycling controller363can operate completely independent from the control system160. In other aspects, the recycling controller363—or at least the features and functions of the recycling controller363—can be tied or incorporated into the control system160.

The shuttle-valve assembly150of the metering cylinder assembly400can comprise a sensor mount360. Each of a first shuttle cylinder position sensor361, which can be a right shuttle cylinder position sensor, and a second shuttle cylinder position sensor362(shown inFIG. 4), which can be a left shuttle cylinder position sensor, can be mounted on the shuttle cylinder sensor mount360. Each of the first shuttle cylinder position sensor361and the second shuttle cylinder position sensor362can sense when shuttle cylinders151,152(152shown inFIG. 4) of the shuttle-valve assembly150have reached a desirable cylinder travel position, which can be proximate to an end-of-travel position at either end of either of the shuttle cylinders151,152. In some aspects, sensing of the positions of the shuttle cylinders151,152by the shuttle cylinder position sensors361,362can serve as a proxy for sensing of the position of the metering cylinders141,142by a separate sensor. The shuttle cylinder position sensors361,362, for example, can even replace the function of the metering cylinder position sensors365,366described below.

The system100can further comprise a mounting bed310, to which the metering cylinder assembly400can be secured. The system100can comprise the metering cylinder position sensors365,366, which can be secured to the mounting bed310. In some aspects, the system100can comprise a single metering cylinder position sensor365,366. In other aspects, the system100can comprise a pair of metering cylinder position sensors365,366. In other aspects, the system100can comprise more than two metering cylinder position sensors365,366. In any case, a position sensor such as the metering cylinder position sensor365,366can sense the position of the rod410of the metering cylinder assembly400. In some aspects, a position flag364can be secured to or mounted around the rod410, in which case the position flag364can be a portion of the rod410whose movement is sensed by either or both of the metering cylinder position sensors365,366. The position flag364, the metering cylinder position sensor365, and the metering cylinder position sensor366can be positioned relative to one another such that the first metering cylinder position sensor365and the second metering cylinder position sensor366can effectively sense “near” end of travel of the rod410, which can be the point at which the rod410nears the end of travel and, as will be described, gas that can be trapped inside the first material81and the second material82can be introduced into the respective first transfer pipes411,412or the second transfer pipes412,422.

As shown inFIG. 4, the metering cylinder assembly400can comprise the first exit tee118and the second exit tee128, to which the first recycling valve171and the second recycling valve172, respectively, can be fluidly connected. The first metering cylinder141can comprise a first end4411and a second end4412. Likewise, the second metering cylinder142can comprise a first end4421and a second end4422. Any of the first end4411,4421and the second end4412,4422can comprise an end stop or an end cap.

The metering cylinder assembly400can comprise a first transfer pipe411fluidly connecting the first end4411of the first metering cylinder141to a lower valve521(shown inFIG. 5); and the metering cylinder assembly400can comprise a second transfer pipe412fluidly connecting the second end4412of the first metering cylinder141to an upper valve520. The metering cylinder assembly400can comprise a first transfer pipe421fluidly connecting the first end4421of the second metering cylinder142to an upper valve530; and the metering cylinder assembly400can comprise a second transfer pipe422fluidly connecting the second end4422of the second metering cylinder142to a lower valve531(shown inFIG. 5). Each of the transfer pipes411,412and the transfer pipes412,422can be used for both inflow and outflow of the respective materials81,82, depending on whether the rod410of the metering cylinder assembly is moving in a first axial direction or a second axial direction opposite the first axial direction.

As shown, the side of the metering cylinder assembly400handling the first material81can comprise a first inlet port417, which can receive the first delivery pipe117, and a first return port419, which can receive the first return pipe119. Likewise, the side of the metering cylinder assembly400handling the second material82can comprise a second inlet port427, which can receive the second delivery pipe127, and a second return port429, which can receive the second return pipe129. As described above, the delivery pipes117,127can be used to transport the materials81,82from the preparation tanks114,124, respectively.

The metering cylinder position sensors365,366, shown inFIG. 4without the mounting brackets for clarity, can be oriented facing the rod410and substantially perpendicular to the rod410. The position flag364can be secured to the rod410with a fastener3640, which can be, for example and without limitation, a set screw or a pin. As shown, the shuttle cylinder position sensors361,362can sense the position of a portion of the shuttle-valve assembly150such as a first bar451on a first end of a moving portion of the shuttle-valve assembly150and a second bar452(shown inFIG. 2) on a second end of a moving portion of the shuttle-valve assembly150. Again, the sensor mount360can be used to support and maintain the position of the shuttle cylinder position sensors361,362.

As shown inFIG. 5, which shows portions of the shuttle-valve assembly150(e.g., the sensor mount360and the shuttle cylinder position sensors361,362) as well as the first transfer pipes411,421and the second transfer pipes412,422removed for clarity, the shuttle-valve assembly150can comprise an actuator rack550defining teeth551. In some aspects, as shown, each of the actuator rack550, the shuttle cylinders151,152, and the metering cylinders141,142can be oriented along and be configured to move along an X-axis direction as shown. In other aspects, movement can be along an Y-axis direction or a Z-axis direction or at an angle to any of the X-axis direction, the Y-axis direction, and the Z-axis direction.

Again, the metering cylinder assembly400can comprise the first inlet port417, the second inlet port427, the first return port419, and the second return port429. The first inlet port417can be defined in a first inlet tee517, while the second inlet port427can be defined in a second inlet tee527. A transfer pipe518can fluidly connect the first inlet tee517to the lower valve521, and a transfer pipe528can fluidly connect the second inlet tee527to the lower valve531. Similarly, a transfer pipe519can fluidly connect the first inlet tee517to the upper valve520, and a transfer pipe529can fluidly connect the second inlet tee527to the upper valve530.

The metering cylinder assembly400can comprise a first outlet tee524and a second outlet tee534. A transfer pipe522can fluidly connect the first outlet tee524to the upper valve520, and a transfer pipe532can fluidly connect the second outlet tee534to the upper valve530. A transfer pipe523can fluidly connect the first outlet tee524to the lower valve521, and a transfer pipe533can fluidly connect the second outlet tee534to the lower valve531. A transfer pipe525can fluidly connect the first outlet tee524to the first exit tee118, and a transfer pipe (not shown) can fluidly connect the second outlet tee534to the second exit tee128.

The first metering cylinder141can define a first transfer port5411at the first end4411and a second transfer port5412at the second end4412, which can be sized and otherwise configured to receive the first transfer pipe411(shown inFIG. 4) and the second transfer pipe412(shown inFIG. 4), respectively. Likewise, the second metering cylinder142can define a first transfer port5421at the first end4421and a second transfer port5422at the second end4422, which can be sized and otherwise configured to receive the first transfer pipe421(shown inFIG. 4) and the second transfer pipe422(shown inFIG. 4), respectively.

As shown inFIG. 6, each of the upper valves520,530and the lower valves521,531can comprise a pinion gear defining teeth matching the teeth551of the actuator rack550. More specifically, the upper valve530can comprise a pinion gear552, the upper valve520can comprise a pinion gear553, the lower valve531can comprise a pinion gear554, and the lower valve521can comprise a pinion gear555.

The metering cylinder assembly400can comprise a position flag601, which can be positioned between the first metering cylinder141and the second metering cylinder142and be secured to or mounted around the rod410. A first position sensor602and a second position sensor603, which can be offset in an axial direction of the rod410from the first position sensor602, can sense the presence of the position flag601and thereby sense and track movement of the rod410. Either or both of the first position sensor602and the second position sensor603can be mounted to a sensor mount604with a fastener, which can comprise a clamp or a bracket. The position flag601, the first position sensor602, and the second position sensor603can be positioned relative to one another such that the first position sensor602and the second position sensor603can effectively sense the absolute end of travel of the rod410, which can be the point at which the rod410stops and reverses direction.

The first metering cylinder141can comprise a first bleeder valve6411and a second bleeder valve6412. Likewise, the second metering cylinder142can comprise a first bleeder valve6421and a second bleeder valve6422. Either or both of the first bleeder valves6411,6421or the second bleeder valves6412,6422can facilitate manual removal of gas trapped inside the first ends4411,4421or the second ends4412,4422of the respective metering cylinders141,142.

As shown inFIG. 7A, which shows a top view of the metering cylinder assembly400, the first metering cylinder141can comprise a first piston741, and the second metering cylinder142can comprise a second piston742.

As shown inFIG. 7B, which shows a cross-section of the metering cylinder assembly400, as will be described in more detail with respect toFIG. 13, a fluid such as the material81,82inside the respective metering cylinder141,142can have both a liquid portion and a gas portion.

On a first side of an interior cavity7430of the first metering cylinder141positioned between the first piston741of the first metering cylinder141and the first end4411, a lighter portion7431of the first material81(shown inFIG. 12) can comprise rising entrapped gas, while a heavier portion7432of the first material81can comprise a settling liquid. On a second side of the first piston741of the first metering cylinder141opposite from the first side and proximate to the second end4412, a lighter portion7433of the first material81can comprise rising entrapped gas, while a heavier portion7434of the first material81can comprise a settling liquid.

Likewise, on a first side of an interior cavity7440of the second metering cylinder142positioned between the second piston742of the second metering cylinder142and the first end4421, a lighter portion7441of the second material82(shown inFIG. 12) can comprise rising entrapped gas, while a heavier portion7442of the second material81can comprise a settling liquid. On a second side of the second piston742of the second metering cylinder142opposite from the first side and proximate to the second end4422, a lighter portion7443of the second material82can also comprise rising entrapped gas, while a heavier portion7444of the second material82can also comprise a settling liquid.

The first end4411of the first metering cylinder141can define a gas exit cavity7411fluidly connecting the first end of the interior cavity7430of the first metering cylinder141and the first bleeder valve6411, and the second end4412of the first metering cylinder141can define a gas exit cavity7412fluidly connecting the second end of the interior cavity7430of the first metering cylinder141and the second bleeder valve6412.

Likewise, the first end4421of the second metering cylinder142can define a gas exit cavity7421fluidly connecting the first end of the interior cavity7440of the second metering cylinder142and the first bleeder valve6421, and the second end4422of the second metering cylinder142can define a gas exit cavity7422fluidly connecting the second end of the interior cavity7440of the second metering cylinder142and the second bleeder valve6422.

A first cylinder axis701defined by the first metering cylinder141can be aligned with a second cylinder axis702defined by the second metering cylinder142.

In some aspects, as described above, either of the recycling valves171,172can be an electronic valve that is electronically operated. In other aspects, as shown inFIG. 8, either of the recycling valves171,172can be replaced with a manually operated valve such as, for example and without limitation, a manual shut-off valve1011,1021in the respective return pipe119,129. Each of the manual shut-off valves1011,1021can be a recirculation valve. Either of the manual shut-off valves1011,1021can be any valve able to manually regulate flow of the respective material81,82into the return pipe119,129such as, for example and without limitation, a 90-degree ball valve with a lever. As shown, each of the manual shut-off valves1011,1021can be in a closed position, blocking such flow into and through the respective return pipe119,129. In some aspects, opening the manual shut-off valves1011,1021can facilitate start temperature equalization of the system100and a general homogenization of the materials81,82but is not intended to remove entrapped gas.

As shown inFIG. 9, the metering cylinders141,142(142shown inFIG. 8) and the metering cylinder position sensors365,366can be secured to the mounting bed310of the system100. More specifically, the mounting bed310can comprise rails312and channels313with respect to which the metering cylinders141,142and the metering cylinder position sensors365,366can be gauged or positioned and secured. The metering cylinder position sensors365,366can be secured to brackets911,912with a respective fastener. The brackets911,912can be secured to the mounting bed310with positioning blocks921,922and positioning blocks931,932, respectively. The positioning blocks921,922and the positioning blocks931,932can be secured to the mounting bed310with respective fasteners9219,9229,9319,9329. By adjustment (e.g., loosening and readjustment) of fasteners such as, for example and without limitation, the fasteners9219,9229,9319,9329, the metering cylinder position sensors365,366can be moved to and secured in any desired position in the X-axis, the Y-axis, or the Z-axis directions as shown relative to the rod410and the position flag364of the metering cylinder assembly400.

Each of the metering cylinder position sensors365,366can comprise a proximity sensor comprising, for example and without limitation, an electromagnetic coil for sensing the presence of a metal object such as the position flag364. Each of the metering cylinder position sensors365,366can be an inductive sensor in that the presence of the metal object being sensed need not touch the metering cylinder position sensor365,366but simply be close enough to the metering cylinder position sensor365,366to induce movement of a switch located inside the metering cylinder position sensor365,366.

As shown inFIG. 10, the recycling valves171,172can be electronically controlled. The recycling valves171,172can also be pneumatically powered. Each of the recycling valves171,172can be a ball valve such as, for example and without limitation, the ball valve Model DM340available with either electric or pneumatic actuators from DuraValve, Inc. of Elk Grove, Ill. For example and without limitation, a control wire1711,1712, which can be connected to the respective recycling valves171,172as shown, can be in electrical or electronic communication with the control system160or the recycling controller363to receive operations from and optionally provide feedback to the control system160or the recycling controller363. In addition, the control wires1711,1712can provide electrical power to the respective recycling valves171,172. A pneumatic line1721,1722, which can be connected to the respective recycling valves171,172as shown, can be in fluid communication with a source of pressured air to facilitate actuation of the respective recycling valves171,172. As shown, the recycling valves171,172can be installed in-line in the return pipes119,129. To facilitate back-up manual regulation of flow of the materials81,82into and through the return pipes119,129, the system100can further comprise the manual shut-off valves1011,1021in the return pipes119,129. Either or each of the manual shut-off valves1011,1021can be, for example and without limitation, a ball valve with a lever as shown.

The weight of any or all of the recycling valves171,172, the return pipes119,129, and the manual shut-off valves1011,1021can be supported by a support1050, which can comprise support members1051,1052,1053. Horizontal support members1051,1052can support such weight and can be themselves mechanically secured to a vertical support member1053. As shown, each of the support members1051,1052,1053can be a rail or a bar and can be joined to each other with brackets or fasteners or both. In some aspects, the weight and rigidity of the recycling valves171,172, the return pipes119,129, and the manual shut-off valves1011,1021and the connections therebetween can maintain the position of each component relative to the support1050. In other aspects, additional fasteners can be used to secure the recycling valves171,172to the support1050.

As shown inFIG. 11, a schematic view of the system100in the dispensing condition, the second metering cylinder142, which can be connected to the first metering cylinder141as shown, can by such connection be configured to move from a first stroke position A—which can be measured to a centerline of the position flag601—to a second stroke position B (shown inFIG. 12) in unison with the first metering cylinder141. As such movement occurs, both the first material81and the second material82are effectively—and simultaneously—pushed through the system100and ultimately to and through the dispensing head133. At the same time, the delivery pumps116,126can resupply the material81,82to the opposite side of the respective metering cylinders141,142. As shown, the recycling valves171,172are in a closed position and the dispensing head133is in an open position. As the first material81and the second material82flow through the dispensing head133, the first material81and the second material82can be progressively and thoroughly blended inside a static mixing portion of the dispensing nozzle130and exit as the mixture83, which can be a homogenous mixture such as the potting material or casting resin previously described.

As shown inFIG. 12, a schematic view of the system100in the recycling condition, the recycling valves171,172are in an open position and the dispensing head133is in a closed position. As the first material81and the second material82flow towards the closed dispensing head133, the presence of the first material81and the second material82filling the respective feeder pipes131,132causes the first material81and the second material82now flowing from the respective metering cylinders141,142to be diverted through the now open recycling valves171,172, through the return pipes119,129, and back into the respective preparation tanks without disturbing the first material81and the second material82filing the respective feeder pipes131,132.

As shown inFIG. 13, the representative metering cylinder141(representative of both the first metering cylinder141and the second metering cylinder142) is shown in schematic form. The piston741can move in the X-axis direction proximate to the second stroke position B (shown inFIG. 12). As the piston741moves from the first end4411to the second end4412of the first metering cylinder141, the liquid in the first material81can settle towards the bottom of the interior cavity7430and gas present in the first material81can rise towards the top of the interior cavity7430. In effect, the lighter portion7431of the first material81can comprise rising entrapped gas, while the heavier portion7432of the first material81can comprise the settling liquid. Likewise, on the opposite or second side of the first piston741, the lighter portion7433of the first material81can comprise rising entrapped gas, while the heavier portion7434of the first material81can comprise the settling liquid. As the liquid portion of the first material81settles and the gas portion or gas pocket of the first material81rises on each side of the piston741, a gas portion7451can form on the first side of the piston741and a gas portion7452can form on the second side of the piston741. The gas portion7451can occupy a space having a height1311measured in cross-section, which as shown can be representative of the relative volume of the entrapped gas bubbles in the fluid, or vertically from an uppermost portion of the interior cavity7430of the metering cylinder141to the top of the liquid portion of the first material81on the first side of the piston741, while the gas portion7452can occupy a space having a height1312measured in cross-section, which likewise as shown can be representative of the relative volume of the entrapped gas bubbles in the fluid, or vertically from an uppermost portion of the interior cavity7430to the top of the liquid portion of the first material81on the second side of the piston741.

As described above, the representative first material81, which can consist of a mixture of the lighter portion7431and the heavier portion7432, can be delivered in a pressurized state into the interior cavity7430via the first transfer port5411on the first side of the first piston741via the first delivery pump116. In certain conditions, such as, for example and without limitation, when the second delivery pump126is operating simultaneously, the first recycling valve171is opened, and the second recycling valve172is simultaneously opened, a pressure drop can be created in the interior cavity7430on the second side of the first piston741. Such a pressure drop can create a lower differential pressure inside the material81located on the second side of the piston741, which can cause the immediate expansion of the gas portion7452of the first material81(which can consist of a mixture of its lighter portion7433and heavier portion7434). As will be described below, the material81can be discharged through the operatively opened second transfer port5412and the lighter portion7433sent back to the preparation tank114for recycling.

As the piston741pushes the liquid portion of the first material81out of the first metering cylinder141through the second transfer port5412, the height1312can increase due to the gas portion7452being a greater and greater percentage of the increasingly smaller volume of the interior cavity7430on the second side of the piston741. Eventually, the gas portion can begin to be pushed out of the first metering cylinder141through the second transfer port5412, thereby introducing gas into the otherwise homogeneous liquid material81present in the transfer pipe412(shown inFIG. 12).

When the dispensing valve of the dispensing head133is kept open in such conditions, such trapped gas can travel as part of the first material81through the feeder pipe131to the dispensing head and be dispensed through the dispensing nozzle130. Simultaneously, because of a similar process occurring in and as a result of movement of the piston742in the second metering cylinder142, trapped gas can theoretically also travel as part of the second material82through the dispensing pipe132to the dispensing head and be dispensed through the dispensing nozzle130after mixing with the first material81. It is theoretically possible but unlikely that the first material81and the second material82would be identically “contaminated” with trapped gas and still mix in the proper ratio to produce the mixture83having not only desirable properties but the intended properties. The existence of all of the following conditions, for example, could cause such a result: the liquid portion of the first material81and the liquid portion of the second material82having identical properties, including especially viscosity or resistance to flow; the first material81and the second material82having an identical percentage of trapped gas; identical distribution of any trapped gas throughout each of the first material81and the second material82throughout transport of the materials81,82through the system100; and simultaneous operation (i.e., simultaneous cycling ON and OFF) of the delivery pumps116,126.

In a typical use of the system100, however, the characteristics of the first material81, the second material82, and the system100itself are not so aligned. First, as noted above the first material81and the second material82do not typically have identical properties, including in the area of viscosity. Again, the system100can be used to dispense a potting material into an assembly such as, for example and without limitation, an assembled electrical or electronics component such as a relay, a motor, or a water meter antenna or register assembly, in order to stabilize and protect by encapsulation or lamination the component against liquid intrusion that might adversely affect the operation of the component or shorten its life. For example, such a mixture83can be an epoxy (as more broadly characterized) or a polyurethane (as more narrowly characterized) potting material or casting resin formed by a mixture of a polyol resin and an isocyanate “hardener” material. In order to create the mixture83having the desired properties from the first material81and the second material82, the two materials can in some instances have very different properties. The inherent differences between the materials81,82and the limitations of the systems in which they are typically dispensed, however, can make it challenging to consistently and reliably mix and dispense the materials81,82at the required ratio.

In other aspects, in addition to the use of potting materials in an assembled electrical component, potting materials can be used in a wide variety of other products and industries. For example an without limitation, epoxy and other casting resins including the mixture83described herein can be used to fabricate composite material structures such as is common in the manufacture of wings and many other structural components of aircraft, wind turbine blades, helmets, boats, racing chasses—such as used in FORMULA ONE class racing. In some aspects, as described above, the casting resin resulting from the mixture83can simply cover or surround the material. In other aspects, such as when using the casting resin to build an aircraft wing, a fibrous material such as, for example and without limitation, carbon fiber or fiberglass can be impregnated with the casting resin and built in layers. In other aspects, mixtures of the materials81,82(and mixtures comprising more than the two materials81,82) dispensed using any of the structures or methods described herein can be used in the manufacture of other products such as, for example and without limitation, pharmaceuticals, food products, nutritional aids, and munitions.

In some aspects, in a typical dispensing system, the target mixture83can be a 50/50 or 1:1 ratio mixture of the materials81,82. This same typical dispensing system100operated without any of the improvements described herein, however, can regularly dispense an “off-ratio” mixture83in every cycle of operation or every stroke of the respective piston741,742—typically beginning near an end of a direction stroke of each metering cylinder assembly400. One effect of the mixture83being “off-ratio” is that the mixture83cannot properly and fully cure and can fail to provide the protection that the component requires. Because of the way in which the mixture83fills, surrounds, coats, and permanently adheres to the components of an assembly, an off-ratio mixture83, not having the require properties, can effectively result in any component manufactured with it being utterly unusable and subsequently scrapped at an unacceptably high cost to a manufacturer. If a product that has been assembled with an off-ratio potting material is not identified as such before reaching a customer or end user, other negative consequences can result. In the case of a structural component fabricated with a casting resin such as the mixture83, an off-ratio mixture83can result in failure of the component including, but not limited to, delamination or buckling of individual layers or the entire assembled part.

As an example of the challenges of dispensing the mixture83, a viscosity of the first liquid81can be substantially different than a viscosity of the second liquid82. For example and without limitation, the first material81, which can be the polyol resin material, can have a viscosity of 3,200 centipoise (cps) at 25° C.; in contrast, the second material82, which can be the isocyanate material, can have a viscosity of only 130 cps under the same conditions. Therefore, the polyol resin or “Part A” material can have a viscosity that is nearly 25 times the viscosity of the isocyanate or “Part B” material, even though the density of the polyol resin, which can measure 7.7 lbs./gallon (0.92 g/cm3), can actually be less than that of the isocyanate, which can measure 8.3 lbs./gallon (0.99 g/cm3), and the specific gravity, at 0.91, can be less than that of the isocyanate, at 1.00). In some aspects, therefore, the viscosity of the first liquid81can be between 24 and 25 times the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be at least 20 times the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be at least 15 times the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be at least 10 times the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be at least five times the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be at least two times the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be the same as the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be less than the viscosity of the second liquid82. In other aspects, the viscosity of the first liquid81can be more than 25 times the viscosity of the second liquid82. In any case, when a material such as the material81,82has a higher viscosity, there can be an increased risk of creating a vacuum when pumping the material because the material can be effectively drawn from one part of the system (for example, the preparation tank114) faster than it can readily flow because of its relatively high viscosity. Such a vacuum within the system100can cause any entrapped gasses to separate from the liquid portion of the material, created a gas pocket, which as described herein can result in an off-ratio mixture83because a portion of the material81,82, which should be a liquid, is displaced in part by a gas—and gas that can occupy more volume than any corresponding liquid.

As another example of the challenges of dispensing the mixture83, the first material81and the second material82can comprise trapped gas of different percentages. For example only, various batches of either of the first material81and the second material82manufactured at different times can for various reasons be manufactured or stored under varying conditions and yet each batch still remain within recommended tolerances for that particular material81,82. In addition, either of the materials81,82can be purchased from one supplier at one point in time and then from another supplier at another point in time, in which case the different suppliers can produce materials81,82having the substantially similar if not identical chemical properties. Yet material purchased from the one supplier can have more or less trapped gas than material purchased from the other supplier. In fact, the first material81can have a materially significant percentage of trapped gas and the second material can have none at all, and vice versa. There can be economic or other reasons for this. In any case, any gas trapped inside either the first material81or the second material82can, moreover, be distributed unevenly throughout each of the first material81and the second material82, respectively, such that pockets of trapped gas can be present inside the materials81,82, which can otherwise be homogenous liquids comprising only the Part A and Part B components themselves.

As yet another example of, while not necessarily the only other reason for, the challenges of dispensing the mixture83, the delivery pumps116,126do not typically operate simultaneously (i.e., simultaneously cycling ON and OFF) during operation of the typical system100—including in the system100described herein. As described below, a cycle timing of the first pump can be not synchronized with a cycle timing of the second pump. A cycle timing of two pumps are not synchronized, non-synchronous, or asynchronous, when the ON and OFF cycles of the pumps begin at different times during their operation. For example, the first delivery pump116can have a 4:1 pressure ratio, and the second delivery pump126can have a 1:1 pressure ratio. Using pumps with different pump pressure ratios can be helpful when pumping materials81,82having different viscosities. For example, a higher ratio pump can in some cases pump through the system100a higher viscosity material such as the first material81more effectively, while a lower ratio pump can suffice for pumping of the second material82. Even with identical type pumps, even slightly non-synchronous operation of the pump cycles from the start of operation or over time due to wear or other factors can cause the first material81to flow at a point in time when the second material82is stationary, and vice versa. With the delivery pumps116,126being different pump types, however, non-synchronous operation can have a greater effect. Not only can the pump ON and OFF cycles be offset from one another from the start of operation of the system100, but due to the difference in operation (including the number of cycles per given time period, for example), there can be multiple times (e.g., 5, 10, 20, or even more times) within a single stroke of the metering cylinder400in which the first material81is flowing or pulsing (flowing at a greater rate) at a time that the second material82is stationary or flowing at a lesser rate, and vice versa.

Each time that either the first metering cylinder141or the second metering cylinder142is moving and yet the first material81or the second material82, respectively, is stationary, gas in the form of bubbles inside the first material81and the second material82can be formed. Without removal of the gas that can be trapped in the materials81,82as drawn from the respective preparation tanks114,124or as can develop in the materials81,82during pumping of the materials81,82through the system100, the aforementioned off-ratio mixture83can result. While the bleeder valves6411,6412,6421,6422can facilitate manual removal of gas from the metering cylinders141,142, manual removal of trapped gas from the materials81,82through the bleeder valves6411,6412,6421,6422not only can require worker skill and time (and inevitably introduce the possibility of human error into the process), but productivity of the overall process (for example, as measured by a total number of the assemblies being filled with the potting material) can be impacted, which can result in even greater costs.

Again, in some aspects, the target mixture83can be a 50/50 or 1:1 ratio mixture of the materials81,82. It can in some cases be acceptable for the first material81to be greater in volume or less in volume than the volume of the second material by 5%, but beyond this range the mixture can become unusable. By operating the electronically controlled recycling valves171,172disclosed herein, a user can be guaranteed that 100% of the mixture83is within the required range by removing the gas trapped in the lines and more specifically in the metering cylinders141,142, even if some variance in the ratio from an exact50/50ratio is not possible for some of the reasons stated above. As will be described in more detail below, during the time that trapped gas is likely to introduced into the portion of the system100proximate to the dispensing head133, the control system160or the recycling controller363can be set to automatically close or “lock” the dispensing head133and simultaneously open the recycling valves171,172in order to draw the respective material81,82—with or without the trapped gas—back into the respective preparation tanks114,124. No matter the cost of the materials81,82but especially if the cost is not insignificant, such redirection of the materials81,82effectively means that no material is wasted; rather it is reused during subsequent operation of the system100. In other aspects, as will be described below, other mixture ratios and ratio tolerances can be accommodated.

Because of this reuse of the material81,82, the trigger point for recirculation to begin—by closing the dispensing head133and opening the recycling valves171,172—can be made far enough away from the end of the stroke of the metering cylinder assembly400that the risk of gas remaining trapped in the materials81,82as the materials81,82flow through the dispensing head133is at an acceptable level. In some aspects, the recycling valves171,172can open at a position equal to 92% of the cylinder stroke position, though the position can be above or below 92% in other aspects depending on, for example and without limitation, the properties of the materials81,82.

In a typical system without any of the improvements described herein, an off-ratio mixture83can be manually captured in containers at the end of each stroke and then discarded. This discarded material can amount to as much as 8-10% or more of the material initially in the supply containers111,121. When the dispensing head133is closed and the manual shut-off valves1011,1021are open, however, any gas trapped in the material81together with the material81in which that gas is trapped can in some cases be diverted through the manual shut-off valves1011,1021, through the return pipes119,129, and back into preparation tanks114,124, respectively. As is noted elsewhere, however, this apparent removal of trapped gas from the materials81,82may be quickly reintroduced into the materials81,82and is neither automatic nor guaranteed to be effective. Due to the presence of trapped gas, the material81that is actually mixed with the material82being simultaneously pushed through the system100can actually be less than required to ensure a 50/50 mixture of the two materials81,82.

When the piston741changes direction and pushes the liquid portion of the first material81out of the first metering cylinder141through the second transfer port5412, the height1312can increase due to the gas portion7452being a greater and greater percentage of the increasingly smaller value on the second side of the piston741. Eventually, the gas portion can begin to be pushed out of the first metering cylinder141through the second transfer port5412, therefore introducing gas into the otherwise homogeneous liquid material81present in the transfer pipe412(shown inFIG. 12).

As shown inFIG. 14, an overall process1400for dispensing the mixture83of the materials81,82can comprise any one or more of the following steps. As shown inFIG. 14, each of the materials81,82can be a fluid. The dispensing process1400can comprise moving the first metering cylinder141and the second metering cylinder142in unison throughout from a first stroke position such as the first stroke position A to a second stroke position such as the second stroke position B, or vice versa. A step1410can comprise supplying and activating power to the system100. A step1420can comprise initiating a dispensing process, which can be by one-time or continuing operator input, the latter by a component such as, for example and without limitation, the aforementioned foot switch or any other switch. Respective steps1430A,B can comprise drawing a first material81from a first supply source such as, for example and without limitation, the first supply container111and drawing the second material82from a second supply source such as, for example and without limitation, the second supply container121. Respective steps1440A,B can comprise pumping the first material81from the first supply source to the first metering cylinder141and pumping the second material82from the second supply source to the second metering cylinder142. Respective steps1450A,B can comprise filling the first metering cylinder141with the first material81and filing the second metering cylinder142with the second material82. Respective steps1460A,B can comprise pushing the first material81from the first metering cylinder141towards the dispensing head133and pushing the second material82from the second metering cylinder142towards the dispensing head133. A step1470can comprise mixing the first material81and the second material82at the dispensing head133or after passing through the dispensing head and entering the dispensing nozzle130. A step1480can comprise simultaneously dispensing each of the first material81and the second material82from the dispensing head133through the dispensing nozzle130. More specifically, dispensing each of the first material81and the second material82from the dispensing head133can comprise dispensing a polyurethane epoxy material from a dispensing nozzle130.

At this stage, however, the mixture83can be a liquid only, i.e., without any significant portion of trapped gas. More specifically, where the materials81,82separately have a 5% mixture tolerance upon receipt from a supplier and initial incorporation into the system, the system described herein can reduce the percentage of trapped gas in the mixture83to less than one percent—in contrast to such a percentage being nine percent or more with a system not comprising the improvements described herein. A step1490can comprise determining whether a position flag such as, for example and without limitation, the position flag364of the metering cylinder assembly400has reached a position sensor such as, for example and without limitation, the position sensor366. A purging process1500can comprise purging gas from the materials81,82flowing through the system100before such gas is effectively dispensed with the materials81,82.

As shown inFIG. 15, the purging process1500can comprise any one or more of the following steps. As an initial matter, gas or gas pockets can be introduced into the first material81or the second material82at any one or more of a number of different steps: before being transferred to the respective supply container111,121, in the process of being pumped into the respective preparation tank114,124by the respective transfer pumps113,123, in the process of being agitated inside the respective preparation tank114,124by, for example and without limitation, the respective agitators115,125, after this point but before being drawn from the respective preparation tank114,124, in the process of being pumped into the delivery pipes117,127by the respective delivery pumps116,126, in the process of being transferred to the respective metering cylinders141,142, and in the process of being transferred from the respective metering cylinders141,142. When either of the first material81or the second material82is a volatile organize compound (VOC), such as, for example and without limitation, polyol, an otherwise liquid material can spontaneously form gas vapors in a process sometimes referred to as outgassing. As with the overall process1400, the purging process1500can comprise moving the first metering cylinder141and the second metering cylinder142in unison throughout from a first stroke position such as the first stroke position A to a second stroke position such as the second stroke position B, or vice versa.

A step1510can comprise closing or locking a dispensing valve of the dispensing head133to stop dispensing of each of the first material81and the second material82. Closing the dispensing head133can comprise closing or locking out the dispensing head133when each of the first metering cylinder141and the second metering cylinder142is proximate to the second stroke position B. Locking out the dispensing head133to stop dispensing of each of the first material81and the second material82can occur without manual intervention by a user of the system100. Respective steps1520A,B can comprise opening a first recycling valve171, which can be positioned in a fluid line between the first metering cylinder141and the dispensing head133, and opening a second recycling valve172, which can be positioned in a fluid line between the second metering cylinder and the dispensing head133. Respective steps1530A,B can comprise drawing a portion of the first material81back into the first supply source and drawing a portion of the second material82back into the second supply source. A step1540can comprise stopping and reversing movement of the first metering cylinder141and the second metering cylinder142. Respective steps1550A,B can comprise starting to push the first material81from an opposite side of the first metering cylinder141and starting to push the second material82from an opposite side of the second metering cylinder142.

In some aspects, the method can comprise keeping each of the first recycling valve171and the second recycling valve172open until each of the first metering cylinder141and the second meter cylinder142reaches an end of a programmed stroke interval or programmed stroke distance or until a piston741,742of at least a one of the first metering cylinder141and the second metering cylinder142, respectively, changes direction. The method can further comprise keeping each of the first recycling valve171and the second recycling valve172open until an end of a pre-programmed interval for clearing the first fluid dispensing connection and the second fluid dispensing connection of trapped gas, where the first fluid dispensing connection fluidly connects the dispensing head133with the first metering cylinder141and the second fluid dispensing connection fluidly connects the dispensing head133with the second metering cylinder142.

Respective steps1560A,B can further comprise closing the first recycling valve171, which can be positioned in the first fluid dispensing connection, and closing the second recycling valve172, which can be positioned in the second fluid dispensing connection. A step1570can comprise opening the dispensing valve of the dispensing head133to restart dispensing of each of the mixture83.

A method of dispensing a single material such as the material81can comprise drawing the material81from a supply source such as, for example and without limitation, the preparation tank114, moving the metering cylinder141from a first stroke position to a second stroke position, the metering cylinder141fluidly connected to the supply source, dispensing the material81from the dispensing head130fluidly connected to the metering cylinder; automatically closing the dispensing head130to stop dispensing of the material based on a position of the metering cylinder141; and drawing a portion of the material141back into the supply source.

A method of manufacturing a dispensing system100can comprise: assembling a first fluid delivery connection from a first metering cylinder141to a first supply container111, the first supply container111configured to store the first material81; assembling a second fluid delivery connection from a second metering cylinder142to a second supply container121, the second supply container121configured to store the second material82; assembling a first fluid dispensing connection from the first metering cylinder141to the dispensing head133; assembling a second fluid dispensing connection from the second metering cylinder142to the dispensing head133; assembling the first recycling valve171to a portion of the first fluid dispensing connection, the first recycling valve171configured to draw a portion of the first material81back into the first preparation tank114when the first recycling valve171is in the open position; and assembling the second recycling valve172to a portion of the second fluid dispensing connection, the second recycling valve172configured to draw a portion of the second material82back into the second preparation tank124when the second recycling valve172is in the open position.

A method of retrofitting a dispensing system100can comprise splicing in the first recycling valve171to a portion of the first fluid dispensing connection between the first metering cylinder141and the dispensing head133, the first recycling valve171configured to draw a portion of the first material back into the first preparation tank114when the first recycling valve171is in the open position; and splicing in the second recycling valve172to a portion of the second fluid dispensing connection between the second metering cylinder142and the dispensing head133, the second recycling valve configured to draw a portion of the second material back into the second preparation tank124when the second recycling valve172is in the open position.

A method of using the dispensing system100can comprise dispensing the mixture83and determining when gas begins to be expelled by the first metering cylinder141and the second metering cylinder142and optimizing the activation point for the purging process so that it is no earlier than it need be (to avoid unnecessary recirculation of material not containing trapped gas) and no later than it should be (to avoid dispensing of material with trapped gas).

As claimed, a supply container can comprise any of the supply containers111,121, the preparation tanks114,124, and any other source from which the materials81,82can be drawn.

As shown inFIGS. 16 and 17, the system100can comprise not only the manual shut-off valves1011,1021but also the recycling valves171,172and recycling valves173,174. As shown, each of the recycling valves171,172,173,174can be secured directly to one of the metering cylinders141,142. For example and without limitation, a pair of the recycling valves171,173can be coupled to and in fluid communication with the first metering cylinder141. Likewise, a pair of the recycling valves172,174can be coupled to and in fluid communication with the second metering cylinder142.

More specifically with respect to the first metering cylinder141, the recycling valve171can be coupled to and in fluid communication with a tee fitting16431(shown inFIG. 17), which itself can be coupled to and in fluid communication with the first metering cylinder141proximate to the first end4411(shown inFIG. 17) of the first metering cylinder141. Similarly, the recycling valve173can be coupled to and in fluid communication with a tee fitting16432, which itself can be coupled to and in fluid communication with the first metering cylinder141proximate to the second end4412(shown inFIG. 17). More specifically with respect to the second metering cylinder142, the recycling valve172can be coupled to and in fluid communication with a tee fitting16441, which itself can be coupled to and in fluid communication with the second metering cylinder142proximate to the first end4421(shown inFIG. 17) of the second metering cylinder142. Likewise, the recycling valve173can be coupled to and in fluid communication with a tee fitting16442, which itself can be coupled to and in fluid communication with the second metering cylinder142proximate to the second end4422. As shown, either or both of the first bleeder valves6411,6421and the second bleeder valves6412,6422(shown inFIG. 17) can be coupled to and in fluid communication with one of the tee fittings16431,16432,16441,16442.

Each of the recycling valves171,173can be coupled to and in fluid communication with the first preparation tank114via a tee fitting16439, which can be mounted on or proximate to the first preparation tank114, and return pipes16437,16438respectively joining the recycling valves171,173to the first preparation tank114. Likewise, each of the recycling valves172,174can be coupled to and in fluid communication with the second preparation tank124via a tee fitting16449, which can be mounted on or proximate to the second preparation tank124, and return pipes16447,16448respectively joining the recycling valves172,174to the second preparation tank124.

Placing the separate recycling valves171,172,173,174more directly in fluid communication with the respective gas exit cavities7411,7421,7412,7422by mounting the recycling valves171,172,173,174to the ends4411,4421,4412,4422of the corresponding metering cylinders141,142can facilitate more efficient and effective removal and transfer of entrapped gas (such as, for example and without limitation, the trapped gas found in the material81) from the system to the preparation tanks114,124without introduction of the entrapped gas into the mixture83. More specifically, placing the recycling valves171,172,173,174nearer to the entrapped gas inside the metering cylinders141,142can facilitate greater separation of the entrapped gas from the liquid portion of the respective material81,82by reducing the distance across which the material81,82with entrapped gas needs to be pushed to remove it from the metering cylinders141,142and return it to the preparation tanks, thereby reducing pressure losses inside the affected piping and valves of the system and any resistance to flow resulting therefrom.

In some aspects, the material81can be discharged through the respective gas exit cavities7411,7421,7412,7422and the lighter portion7433(shown inFIG. 13) sent back to the preparation tank114for recycling. More specifically, as the piston741(shown inFIG. 13) pushes the liquid portion of the first material81out of the first metering cylinder141through the second transfer port5412, at a desired stroke position the appropriate recycling valves171,172,173,174can be opened and the dispensing head133closed to allow continued movement of the piston741to push the material81and any entrapped gas back into a supply source such as, for example and without limitation, the preparation tank114for recycling. The material82and any entrapped gas can be similarly recycled.

In some aspects, the target mixture83can be a 1.59:1 ratio mixture of the materials81,82. Furthermore, it can in some cases be acceptable for the first material81to be greater in volume or less in volume than the volume of the second material by only 2.5% (i.e., a more sensitive mixture ratio can be accommodated by the system100with the four recycling valves171,172,173,174).