Patent Application
20080217801
The present invention provides for typically portable, small benchtop apparatus that can be utilized to cure bound aggregates of varying shapes, foundry aggregate forms, non-foundry “films”, non-foundry aggregates, semisolids, fibers, mats, wood panels, construction aggregates, petrochemical-based composites, films, and/or other specialized industrial applications that require a chamber for gassing with a catalyst or similar material through a structure, composite, shape, fiber, film or bound aggregate.
Cold box binders for foundry forms (cores and molds) are cured by passing a reactive gas through resin-coated aggregate. The resin cures within seconds of contact with the gas to produce a hardened core or mold. The equipment to perform these tasks must be able to contain the reactive gas as these gases are typically noxious, and control the amount of the gas going into the resinous sand. In the field, the machines performing these operations are called “core blowers” as the resinous sand is blown by gas pressure into the molds for the aggregate forms, followed by a gassing cycle to cure the aggregate mix, then by purging with air, nitrogen, or another inert gas to remove the noxious catalyst gas from the cured aggregate mix.
When testing for effectiveness, a smaller version of these core blowers is typically utilized. Though smaller, this test equipment is still bulky and rather expensive, utilizing specialized parts manufactured by a select few companies. The size and expense puts this type of equipment out of reach of smaller labs attempting to compete in this technical business area. A small, less expensive unit is needed to allow smaller companies to test cold box aggregate binders.
In addition to the evaluation of non-foundry films, composites, aggregates or similar structures, a re-design of an existing foundry style cold box gassing unit was necessary to allow for the testing of similar or new chemistries that could utilize a gas cure mechanism.
The present invention provides for compact device that can be utilized to cure composite materials in various conformations by exposing the uncured composite to catalytic gas vapors. Large scale equipment is used in the foundry industry, for example, to cure curing aggregate forms into cores and molds for the purposes of making cast metal forms. In the case of foundry equipment, the aggregate is mixed with a curing binder, then “blown” by gas pressure into molds the mixed resinous aggregate then has the catalytic gas passed through it, which causes rapid curing. This process is referred to as the “cold box” process. Laboratories have smaller units for testing the binders that bond these forms. These units are large and bulky and cost prohibitive. These units typically require the installation of additional specialized auxiliary equipment for the control of application conditions that adds further to the bulk and cost.
There are four drivers for this invention; the need for cold box test equipment that is compact and affordable, the need for gas-curing test equipment for a wide variety of composite curing, aggregate curing or semi-porous liquids, fluids or films based upon gas or phase-cured technology, the need for a low-cost, low maintenance, easily adaptable apparatus that is easy to use and can be quickly learned and the need for an apparatus that uses a modular construction based on commonly purchased parts.
This document describes a small, accurate, portable, modular, low cost, low maintenance gas-curing unit that is easily constructed out of mostly pre-manufactured modular equipment currently on the market, used in a standard sized laboratory hood, lightweight, portable, low cost and can very accurately dispense a controlled amount of a variety of catalytic gases into an uncured composite matrix such as the resinous aggregate used in cold-box foundry binders. This invention also solves several issues with existing equipment, including size, mobility, and the ability to deliver from 0.5 cc/minute up to over 1,000 cc/minute very accurately and repeatably.
The Invention consists of several distinct “sections” that when combined together, form a fully functional gassing unit capable of turning low-range flash point fluids, or existing gasses into a vaporized or atomized state that is then transferred through a series of heat-traced lines to a core box, gassing unit or gassing booth that may or not contain specific cavity shapes for holding aggregate, fluid or semi-porous materials, or hold permeable films for curing via this equipment.
The invention is a small, accurate, portable, modular, low cost, low maintenance gas-curing unit that is easily constructed out of mostly pre-manufactured modular equipment currently on the market, used in a standard sized laboratory hood. Its lightweight, portable, low cost, low maintenance and other features make it ideal for small laboratories or for transport to various sites.
The majority of components can be purchased through well known and established suppliers of flow meters, electrical components, timers, tanks and associated mechanical and electrical equipment. These suppliers included; W.W. Grainger, McMaster-Carr and Freeman Manufacturing.
Heat-traced lines and controllers were purchased through TempCo Electric Heater Corporation, 607 N. Central Avenue, Wood Dale, Ill. 60191 (www.tempco.com).
Several items are fabricated to make the unit more efficient. The expansion chamber was fabricated specifically to fit the chosen fluid body, fluid cap and gas cap arrangement. Typically, an adapter can be purchased to attach the fluid cap to another pipe fitting or opening.
The invention can be broken down into several distinct segments for ease of construction, transport, maintenance, troubleshooting and incorporation into specific laboratory or other modes.
Segment 1—Pressure Tank containment system; contains the chemical fluids that are to be vaporized or atomized. The pressure valve, dip tube, and pressure regulator are part of this section.
Segment 2—Control Panel; contains the timers, start/stop buttons, switches, totalizers, indicators or other electrical connections, except those associated with the external heaters for the lines and expansion chamber.
Segment 3—Heating Element and transfer lines; allows material movement from the containment structure and carrier materials through the meters, valves and nozzle assembly to the gassing structure or booth. This includes the heated lines, expansion chamber band heater, heater controllers, 2 and 3-way valves, pipe fittings and connectors.
Segment 4—Flow Meter assembly; which includes an in-line 10-micron filter, piston-style flow meter and calibrated transmitter. These components are combined as a set by the manufacturer to the specific requirements of the materials being atomizer or vaporized including the indicator/totalizer.
Segment 5—Spray Head Nozzle Assembly; includes the fluid body, fluid cap, gas cap, 1-way valve and expansion chamber.
Segment 5—Solenoids; includes the liquid materials solenoid, gas solenoid and carrier gas solenoid.
Segment 7—Gassing Unit; containing the gassing manifold, match plate, core box, booth, and associated wall adapters, fittings, vents, seals and enclosures.
Segment 8—Gas/Air Source; includes the carrier gas, purge gas, air/gas desiccators, pressure regulators, valves and associated equipment and fittings.
Referring now to
Gas flow 121 is controlled by a shutoff valve 123. Gas flows via line 124 to a desiccant gas dryer 125, then to line 127 to gas solenoid 129. Gas then flows to T-divider 131. It is noted that the gas line at T-divider 131 is typically placed to the valve 135 or to the manifold 185 at inlet 185B. Lines 133 or 137 for gas flow are placed as needed to valve 135 or inlet 185B. Gas then flows to pipe tee 113 where it may mix with inert gas from line 111 and flow to the expansion chamber 181 via line 137 and fluid body 175.
Amine is stored in a pressure tank 145 typically having a pressure safety valve 147, a pressure regulator 143 where pressurized dry gas 141 can enter the tank 145. A dip tube 151 provides for amine flow to a shutoff valve 152, then via line 153 to a pipe tee 155. One branch flows via a gas line to a filter 157 for liquid amine. The filter 157 typically is a 10 micron filter. From the filter the amine flows to the flow meter 161 that is attached to transmitter 162, then to another pipe tee 165 and then to liquid amine solenoid 171. From the liquid amine solenoid 171 liquid amine flows to the expansion chamber 181 via line 173 and fluid body 175. A “bypass” route or method (as referred to later below) for amine from pipe tee 155 is to flow past shutoff valve 167 via line 168 to pipe tee 165 and then to the liquid amine solenoid before flowing to the fluid body of the expansion chamber 181 via line 173.
Once the liquid amine has been gasified and mixed with inert gas/air as desired the amine gas (vapor) flows out of the expansion chamber outlet 182 to a heat traced transfer line 183 (for the amine gas) and then to the inlet 185A of the gassing chamber 184. Gassing chamber 184 consists of gassing manifold 185 having two inlets 185A and 185B, a match plate 186 for interfacing with curing box 187. Curing box 187 has one or more outlets 189 for gas that is vented or captured as in a hood or other device not shown.
Control panel 191 shows the locations of the on/off power switch 192, remote stop switch 193, remote start switch 194, toggle switch 195 that has an up indicator timer mode and a down amine gas timer mode. Amine gas timer 196, gas purge timer 197 and indicator/totalizer 198 are provided on this panel. Electrical connections between these units on the control panel are given in detail in
Referring now to
Referring now to
Referring now to
Table 1 lists the parts used for the atomizing segment. These parts are manufactured by Spraying Systems Company, P.O. Box 7900, Wheaton, Ill. 60189-7900.
Table 2 lists the parts used for the flow meter, transmitter, filter and indicator/totalizer available from Max Machinery Inc., 1420 Healdsburg Avenue, Healdsburg, Calif. 95448, web address www.maxmachinery.com.
Referring now to
Referring now to
Referring now to
The bottom portion, consisted on a standard 12-cavity aluminum dog bone gang box manufactured by Piteo Manufacturing Company, 5900 Highway 321 North, Lenoir City, Tenn. 37771, that was further modified by a local machine shop to include a perform 20 Durometer seal, commonly known as Dike-O-Seal, around the perimeter and a set of standard size 3 male and female locator pins 184B. These locator pins 184B were set at opposite corners with a height sufficient to pass through the thickness of the match plate into the bottom portion of the top gassing manifold. Holes were drilled and three 50 mesh, Type K, ⅜″ diameter screened vents were placed at the bottom of each dog bone cavity.
Essentially, to cure a laboratory cold-box aggregate test specimen used within the foundry industry, it is necessary to place an aggregate mix, containing a selected type of sand coated with a small amount of gas-curable resin into a standard shape. In this case, the shape happens to be known within the foundry industry as a standard AFS (American Foundry Society) “dog bone” of known proportions, see
The resin used in one of these processes was a phenolic-urethane resin that is catalyzed to a hardened shape within a few seconds by using an amine gas or vapor. The amine gas or vapor acts as a true catalyst. It is passed in the vapor phase through the sand mix, hardening the sand mix. The amine then exits the forms used for making the shapes by means of vents, typically located opposite the injection area. In this case, the amine enters the aggregate sand mix from the gassing manifold, through the match plate to the aggregate sand mix. It then passes through the specific mixed sand shape, maintained by particular patterns in the bottom half on the mold or box then through an exiting vent to the atmosphere, chemical hood, or other arrangement for collection elsewhere. Within the foundry environment, the amine is typically guided by means of vents through a series of collection tubes to a chemical scrubber.
In order to inject or administer the vaporized amine through the aggregate mix, the amine must be atomized and/or vaporized at some point prior to it passing through the aggregate mix. This is accomplished by pressurizing the liquid amine (flash point=14.4° C.) in a containment vessel. The containment vessel used was a 3.79 liter stainless steel pressure tank. The pressurized liquid amine is forced through a series of lines to a liquid amine solenoid. The liquid amine solenoid is opened and closed by means of an amine gas timer located on the control panel.
As the liquid amine is allowed to pass through the liquid amine solenoid, it flows to a spray head assembly, which is attached directly to an expansion chamber. The expansion chamber is typically heated and in this case was heated to be between about 37.8° C. and about 148.9° C.
There are two distinctly different methods that were used with present invention to move the liquid amine to the spray head assembly. One is strictly by means of the pressure differential in the liquid amine tank forcing the liquid amine to the liquid amine solenoid, where it is allocated to the spray head assembly by the amine gas timer. The difference in pressure, the line diameter and time of allocation used determines the amount of amine that will eventually be passed through the mixed aggregate.
The second and preferred method is by using minimal backpressure within the liquid amine tank to keep the liquid amine flowing through the transfer lines to the flow meter, where the liquid amine is moved with a high degree of precision to the liquid amine solenoid. The flow meter, liquid amine solenoid and nitrogen carrier gas solenoid are controlled by the indicator/totalizer located on front of the control panel. This preferred method shows an extremely high degree of accuracy that will allow the liquid amine to be metered anywhere from about 1.0 ml/minute to more than about 94.6 liter/minute depending on the flow meter, transmitter and indicator chosen. This method saves the end user amine or other catalytic material and greatly improves accuracy of a laboratory experiment.
In both cases, once the liquid amine flows past the spray head assembly, where it is first atomized, the atomized particles pass into the expansion chamber where the atomized particles are then vaporized by the external band heater wrapped around the chamber. The chamber acts as a collection point from which the vapors can be moved onwards.
Also, in both cases, as the liquid amine solenoid opens to allow the liquid amine to flow through the spray head assembly, the nitrogen gas (or other inert carrier gas) enters at the same time. The nitrogen gas solenoid is electrically connected to the same contacts as the liquid amine solenoid so both open and close together.
As the liquid amine passes through the spray head assembly, the nitrogen is also passing through the spray head assembly. This causes the atomization of the liquid amine at the ejection point at the tip of the spray head assembly. In effect, it is the same principle as is used to spray paints, varnishes and other coatings. Small droplets are formed.
The small droplets are useful as a means to vaporize the amine catalyst. The vapor phase allows the amines or other materials to pass more efficiently through the aggregates or other materials being cured. It also allows for much less catalyst to be required.
The nitrogen carrier gas is furnished by means of a typical nitrogen cylinder with a regulator and valve assembly or other means such as an “in house” line system. The gas as it exits the cylinder enters a heated transfer line to “pre-warm” the gas before it enters the spray head assembly. By using heated nitrogen, it assures an easier vaporizing of the amine and assists in maintaining it in a vapor phase.
The combination of warm nitrogen and vaporized amine, now in the expansion chamber, passes through a heated amine gas line directly to the gassing manifold. Once again, the use of a heated amine gas line ensures that there will not be any reformation of liquid amine prior to it entering the gassing manifold.
The gassing manifold and associated match plate, bottom plate or other forms used to hold the shapes being gassed could also be heated in a similar fashion to further ensure no amine or other catalyst “drops out” to a liquid phase before catalysis of the materials takes place.
The amine or other catalyst passed through the aggregate, shape, or materials to be catalyzed, then out the bottom of the gassing unit through a series of vents to a collection point or it can be vented to the atmosphere.
Any laboratory or field aggregate, film, semi-permeable material, cellular structure, woven fiber, coating or similar material requiring a technique to vapor or atomize the catalyst for solidification of that material can be evaluated or produced, as in production, using this apparatus. The size of the gassing chamber, manifold, core box, bottom box or enclosure can be resized as needed to hold the shapes for catalyzing.
The gassing apparatus itself can be modified to include two or more solenoids, timers, flow meters or similar parts to incorporate multiple carrier gasses or multiple amines or multiple catalysts. This includes the addition on multiple heated lines and other plumbing.
The examples herein are exemplary of some aspects of the invention and are not intended to limit the scope of the invention in any way.
An initial design of the gassing apparatus centered on producing a typical laboratory test core specimen used within the foundry industry.
A series of sand mixes were made using industry standard readily available phenolic-urethane cold-box binders and Wedron 540 silica sand. The amine chosen for this example was triethylamine (TEA), a typical foundry catalyst used worldwide for curing various cores and molds for high production operations.
The resin was mixed using a 55:45 of Part I (phenol-formaldehyde resin) to Part II (isocyanate and solvents) and mixed on the sand at 1.25% based on the weight of the resin.
The sand mix was hand packed into standard American Foundry Society (AFS) dog bone forms located in the bottom portion of the gassing unit. The match plate was then placed on top of the core box (bottom portion), and then the gassing manifold was placed on top of the match plate.
All three sections were clamped together and placed in the laboratory hood. The amine gas line was attached to the gassing manifold after the gassing apparatus lines and timers were set for the specific evaluation.
Table 3 shows the initial settings for line temperature and pressure during the test phase.
Several sets of 12 dog bones were completely cured using these variables. Test specimens showed 100% cure with initial tensile strengths of above 180 psi using a Thwing Albert QC-3A Tensile Tester set at 2 inches/minute crossbar speed and 0.2 inches/minute crossbar speed once contact with the test specimens was made. The load cell used was a standard 1,000 psi load cell from the same manufacturer.
After the cure cycle, minimal amine odor was noted on the samples. No puddling or liquid amine was noted at any location.
Several mixtures of sand and phenolic-urethane resin were made and evaluated with various settings of time and pressures using the “bypass” method, or not using the flow meter. Results of amine volume were calculated with the liquid amine pressure tank set from 2 to 12 psig back pressure and with the amine gas timer set from 2 to 10 seconds. From the data, calculations were made and a chart developed as shown in Table 4.
The chart developed can be used to preset the gassing apparatus for curing various aggregates or other materials based on the amounts of amine needed. A simplified view of this chart is shown in Table 5.
The “flow meter” method consists of shutting off the “bypass” lines for the liquid amine and allowing the liquid amine to continue through the flow meter to the liquid amine solenoid as previously outlined. With this method, the amine gas timer is not used. All variables for the liquid amine are set using the indicator/totalizer on front of the control panel.
Using this method ensure an exact amount of amine goes to the spray head assembly during a predetermined time and using specific instructions for volumes per second or per minute based on ambient conditions. This method allows the operator to set the time intervals and amounts per selected time to the aggregate or items to be catalyzed.
The flow meter, transmitter and indicator/totalizer work together and are based on electrical current, liquid densities and pulses per second from the flow meter and transmitter. A few of these variables are shown in Table 6.
Parts and materials for the typical fabrication illustrated herein are shown in Table 7 and were purchased through well established suppliers to ensure reliability, part exchange and replacement if needed.
While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all of the possible equivalent forms or ramifications of the invention. It is to be understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit of the scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 60/848,160, filed Sep. 29, 2006. The entire content of the provisional application is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 60848160 | Sep 2006 | US |
