Patent Application
20160003541
The present invention relates generally to heating and drying technologies and, in particular, to heating and drying with the assistance of ultrasound.
It has been observed that the majority of energy intensive processes are driven by the rates of the heat and mass transfer. Specific details of a particular application, such as the chemistry involved in drying a material or applying a coating to a substrate (e.g., a factor in label printing, sheet-fed and continuous printing, converting, packaging, and mass mailing), the temperature and specific properties of both the substrate and the coating including the thickness of both the substrate and coating, the method of application, the residence time for a particular coating to dry, the ambient conditions, and the resulting water or solvent evaporation rates are factors in the outcome of any drying and/or heating process. These factors often dictate the nature and size of the drying equipment.
The properties of the boundary layer formed next to the surface along which a fluid moves dictate the heat transfer rate at the surface and therefore the drying rate for the aforementioned application of coating a substrate and for the more general application of drying materials without a coating. As a consequence of the effect of the boundary layer on the heat transfer rate, it can be argued—as Incropera/DeWitt do in their textbook “Fundamentals of Heat and Mass Transfer”—that heat transfer rates are higher for turbulent flow at a surface than for laminar flow at that surface. In modern heating and drying practice, there are several methods to disrupt the boundary layer in order to produce more turbulent flow and therefore more heat transfer.
One method of disrupting the boundary layer, in order to increase the heat transfer rate or for any other purpose, and therefore the drying rate of a wet surface, is to focus acoustic sound waves or oscillations—ultrasonic waves or oscillations, for example—and optionally heated air at the surface of the material or coating being dried as shown in U.S. Patent Publication No. 2010-0199510, published Dec. 12, 2010, which is hereby incorporated by reference in its entirety.
In some applications where acoustic sound waves—ultrasonic waves, for example—or heat, radiant or otherwise, or forced air or a combination of these elements are directed towards the coating to be dried and at the same time facing the coating itself, especially in applications where the coating is relatively thick, the surface can be damaged either before or after the drying process or can be otherwise undesirably impacted by this process. The surface of the coating and/or substrate can develop cracks or form a surface skin, which then impedes the exit of moisture or solvent deeper in the coating, and this could affect the performance of the coating or substrate or the material as a whole. In some cases, the process itself will be slowed considerably in order to avoid even some of the undesirable effects. When drying a coating on a solid substrate using an air stream as stated above, however, the air is nonetheless typically directed towards the wet surface to be dried.
Disclosed is an acoustic head for indirectly drying a material, the acoustic head including at least one ultrasonic transducer facing the material, the material having a first side, and a second side, the second side opposite the first side, the second side defining a surface to be dried, the ultrasonic transducer positioned facing the first side; and an air delivery unit positioned facing the first side of the material.
Also disclosed is a system for indirectly drying a material, the system including a material, the material having a substrate, a coating to be dried, a first side, and a second side, the second side opposite the first side, the coating to be dried at least partially covering the second side; an acoustic head, the acoustic head including at least one ultrasonic transducer facing the first side of the material; and an air delivery unit, the air delivery unit also positioned facing the first side of the material.
Also disclosed is a method of indirectly drying a material, the method including applying a coating to be dried to a substrate to form a material, the material having a first side, and a second side, the second side opposite the first side, the coating to be dried at least partially covering the second side, an acoustic head and an air delivery unit positioned facing the first side of the material; moving the material in a transverse direction relative to an acoustic head and air delivery unit, the acoustic head including at least one ultrasonic transducer, the ultrasonic transducer positioned facing the first side of the material, the air delivery unit also positioned facing the first side of the material; and drying the material using acoustic waves generated by the at least one ultrasonic transducer.
Various implementations described in the present disclosure may include additional systems, methods, features, and advantages, which may not necessarily be expressly disclosed herein but will be apparent to one of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within the present disclosure and protected by the accompanying claims.
The features and components of the following figures are illustrated to emphasize the general principles of the present disclosure. Corresponding features and components throughout the figures may be designated by matching reference characters for the sake of consistency and clarity.
Disclosed is an acoustic drying system and associated methods, systems, devices, and various apparatus. It would be understood by one of skill in the art that the disclosed system is described in but a few exemplary embodiments among many. No particular terminology or description should be considered limiting on the disclosure or the scope of any claims issuing therefrom.
A partial list of potential uses of the disclosed technology includes but is not limited to printing, residential and commercial cooking appliances, food processing equipment, textiles, carpets, converting industries, fabric dyeing, and so on. In particular, the disclosed system(s) and method(s) can be configured for flexographic and gravure printing of wallpaper, gift-wrap paper, corrugated containers, folding cartons, paper sacks, plastic bags, milk and beverage cartons, candy and food wrappers, disposable cups, labels, adhesives, envelopes, newspapers, magazines, greeting cards, and advertising pieces. Further potential uses of the disclosed technology are paper-making and the painting of motorized vehicles and their components. The disclosed can be adapted for these and many other batch and continuous heating and drying processes.
The adhesives for which various embodiments of the presently disclosed structure and methods would apply include various types of pressure-sensitive adhesives such as those adhesives used as or used as part of sticky tape, duct tape, adhesive fasteners, removable adhesive fasteners such as those used in sticky notes, adhesive wound care device adhesives such as used in BAND-AID bandaging products, adhesives used to hold absorbent pads to garments, self adhesive sheets used to hold solid objects, and cold seal adhesives for food packaging and mailing enclosures.
Also applicable to the presently disclosed structure and methods are various types of coatings and lacquers for films, various foils, and various metal and glass or ceramic sheets, including those having either decorative or functional coatings. In various embodiments, these coatings will be reflective, thermal insulating, electrical insulating, radio frequency absorbing, or mechanical shock absorbing, or these coatings may share several of these characteristics in combination. In various embodiments, the presently-disclosed structure and methods will also cover laminating materials for bonding sheets of various materials together to form composites, such as those used materials or composites used in glass windshields, in aerospace components such as wings, and in other applications such as the aforementioned painting of motorized vehicles and their components. In addition, in various embodiments, a water-based ultraviolet (UV) curable coating is typically dried prior to curing using UV light.
Use of the disclosed structure and methods can also be applied to drying films cast from polymer solutions. In such an application, a polymer solution is poured into a metal tray or onto a carrier sheet, and the solvent is evaporated to produce a dry film. Examples of such polymer-solvent systems include those in the following list:
Use of the disclosed structure and methods can also be applied to polymer dispersions and cast films. A polymer dispersion is a film-forming polymer, and such a polymer is often converted to a film by a process of evaporation from a continuous liquid. For example, natural rubber latex, poly(vinyl acetate), or poly(urethane) dispersed in water may be dried to leave a film. As either water or the continuous liquid medium are removed through evaporation, the spheres of polymer coalesce to form a film. A plasticizer may be added to further facilitate coalescence of the polymer spheres from the polymer dispersion into a cohesive film. During the film casting process, the solvent (or continuous phase if the polymer is in the form of a dispersion) is evaporated by indirect application of the acoustic air to leave a polymer film. The acoustic energy is conducted through the carrier medium to enhance thermal and mass transfer at the interface between the coating and the surrounding gaseous medium, which is often air.
Examples of such films cast from solutions or dispersions may include edible films, including drug delivery devices, such as TRIAMINIC THIN STRIPS medicine strips, previously available from Novartis, New Jersey, and GAS-X THIN STRIPS medicine strips, currently available from Novartis, New Jersey. Other examples of cast films include water-soluble plastic bags and water-soluble packages containing detergents, dyes, or surfactants or a combination of these elements for use with the operation of dishwashers, clothes washing machines, and dying machines.
Because a wide range of products and processes beyond the specific processes, products, systems, or examples provided herein could be made possible or improved by that which is presently disclosed, none of the processes, products, systems, or examples described herein should be considered as limiting the disclosure.
As suggested previously and explained in further detail below, the formation of skin on a coating or material to be dried is often particularly problematic. Not only can it lead to the formation of microscopic or macroscopic surface cracks, but a surface-skinned coating is often very difficult to dry. Without a surface skin, solvent or water molecules can more easily diffuse up through the liquid bulk of the coating to the surface and then leave into the surrounding air. Once a skin forms on the surface of the coating, in various embodiments the water or solvent molecules now must diffuse through the solid skin before these molecules can leave the coating. This process of diffusion through a coating skin is a much slower process than the process of diffusion through a liquid coating, and it is common for some residual solvent or moisture to remain in the lower layers of the coating when a skin forms on the surface of a coating before drying of that coating is complete. This residual moisture or solvent has the potential to deleteriously affect the properties of the coating. For instance, residual moisture or solvent trapped beneath a surface skinned layer has the potential to form a blister, a bubble, or a crack during the remaining drying process. If the film is later warmed, blisters, bubbles, or cracks have the potential to develop. Trapped residual moisture or solvent has the potential to lead to corrosion if the coating is on a metal surface. The residual solvent or water may cause the coating to have an odor.
Applying heat to the side of a substrate opposite to the side that was coated can also lead to bubble or blister formation as well as the formation of a solid skin, sometimes referred to as “skinning”. Applying or directing non-acoustic energized air to the side of a substrate opposite to the side that is coated often has little or no effect on accelerating the drying of the coating, as the forced air is unable to interact with the coating on the other side of the substrate.
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Material delivery unit 150 includes conveyor side frames 200a,b (200b not shown), a set of two lower side frames 210a,b (210b not shown), a set of four leg frames 235a,b,c,d (235c,d not shown), a set of four caster assemblies 240a,b,c,d (240c,d not shown), one positioned at the lower distal end of each leg frame. Also disclosed are a conveyor frame 200, a drive and control module 155, and a conveyor belt 160. Conveyor side frame 200a includes an upper end 201a, a lower end 202a, a first distal end 203a and a second distal end 204a. Conveyor side frame 200b (not shown) includes an upper end 201b, a lower end 202b, the first distal end 203b and the second distal end 204b.
Drive and control module 155 includes a drive module frame 156, a controller 157, a motor 190, and a drive train 165. Drive train 165, located proximate the first distal end 203a of conveyor side frame 200a, includes a drive pulley 166, a drive belt 180, a driven pulley 168, and a conveyor pulley 170. Drive train 165 also includes a drive pulley axle (not shown) and driven pulley axle (not shown). Drive pulley 166 is connected to, supported by, and rotating about the drive pulley axle. Driven pulley 168 and conveyor pulley 170 are connected to, supported by, and rotating about the driven pulley axle. Drive pulley 166, driven pulley 168, and conveyor pulley 170 can be grooved or smooth or contain teeth like a gear to interface with drive belt 180. The pulleys can be made out metal, plastic, or any other material having the required properties. Drive belt 180 can be a belt, a chain, or any other flexible linkage made out rubber, metal, plastic, or any other material having the required properties. The selection of motor 190 and the diameter of each pulley is made based on the desired conveyor speed of a conveyor belt 160. The conveyor speed at which various drying operations were performed was in the range of five feet per minute to 250 feet per minute, but other speeds are used in various embodiments. In order to cause movement of conveyor belt 160 past acoustic head 120, conveyor belt 160 is driven by conveyor pulley 170 and passes around a tension pulley 230, the horizontal location of which, relative to conveyor pulley 170, is adjustable by a pulley adjustment mechanism 231.
Conveyor belt 160 passes around not only conveyor pulley 170 and tension pulley 230 but also around auxiliary pulleys 232, 233, and 234. Auxiliary pulleys 232, 233, and 234 help maintain the position and tautness of conveyor belt 160. In various embodiments, material delivery unit 150 includes a conveyor system 159 and conveyor system 159 includes a conveyor belt 160 which transports the material 1300 past the acoustic head 120 to facilitate drying, although in various embodiments the acoustic head 120 will be made to move past a stationary material 1300 that is to be dried, or both the material 1300 and acoustic head 120 will be made to move during some or all of the drying process. In various other embodiments, conveyor system 159 will not include conveyor belt 160 and the presence of conveyor belt 160 should not be considered limiting. In various embodiments, conveyor system 159 will not require a conveyor belt 160 to transport or convey material 1300 past the acoustic head 120.
In various embodiments, a separation distance D between the acoustic head 120 and the conveyor belt 160 (shown in
In the embodiment of
In various embodiments, the material 1300 to be dried includes a first side 1310 and a second side 1320, and at least two different components—a substrate 1305 (shown in
In various embodiments, substrate 1305 of material 1300 will include any one or more of a number of materials to which a coating can physically be applied. In various embodiments, material 1300 will only include substrate 1305 and will not include a coating 1330 but will nevertheless require drying on one or both sides. The group of materials from which substrate 1305 can be made includes but is not limited to sheet metal, foil, polyethylene terephthalate (PET), polypropylene (PP), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), and polyvinyl butyral (PVB). In various embodiments, the material used will be described as a film. In various other embodiments, the material will not be described as a film. In various embodiments, the substrate 1305 will have a thickness in the range of 10 microns to 2,000 microns (0.010 mm to 2 mm), but in various embodiments the thickness will not be in the range of 10 microns to 2,000 microns and the disclosure of a substrate 1305 having a thickness of 10 microns to 2,000 microns should not be considered limiting on the present disclosure.
In various other embodiments, a coating will also be on the first side 1310 of the material. In other words, it may be beneficial to dry one coating on the second side 1320 and another coating on the first side 1310, and either coating or both coatings could be dried using equipment facing the side facing opposite that side being dried. This drying of both sides could be made to take place at the same time and the same place on the material linearly, or it could be made to take place at different times or at different locations on the same material delivery system.
In various other embodiments, the coating may be absent from both sides and the material without coating, which could be a composition of two or more different materials, is therefore exposed on both the first side 1310 and the second side 1320, at least at the point in time when drying is to take place. In these instances, it is only the substrate 1305 that requires drying. In various embodiments, the material will be made wet on only one side—during a cleaning process, for example—and benefit from a subsequent drying operation. Because of the properties of that particular material or composite of materials in various embodiments, it will not be wet throughout the material. In various embodiments, it will either have a skin on the first side that partially or completely interferes with drying or that makes it less desirable to dry with equipment facing the first side of the material. In various embodiments, the material will be a composite of heterogeneous materials without any coatings that will nonetheless benefit from indirect drying by one or more of the processes disclosed herein. While not to be considered limiting, various embodiments of this disclosure include the cleaning or dying of carpet or fabric. In the case of a material that has been cleaned, it is desirable in some embodiments to remove moisture on the second side of the material using equipment facing the first side. In the case of material that has been treated with a chemical and not a coating, it will be beneficial in some embodiments to remove traces of the chemical or reduce the amount of chemical in the material but using equipment facing the first side of the material that will remove this chemical partially or completely from the second side of the material. This chemical will be water-based in various embodiments and not water-based in various other embodiments. In various embodiments, the chemical will change the properties of the base material (during a chemical dying process, for example) but will be made to leave the material during the subsequent drying process. In various other embodiments, the chemical will not change the properties of the base material (during a cleaning process, for example) but will nonetheless provide some benefit to the process—the removal of dirt in this example.
In various embodiments, the thickness of the coating 1330 will be at least 5 microns (0.005 mm) but in various embodiments the thickness will not be at least 5 microns and the disclosure of a coating 1330 having a thickness of at least 5 microns should not be considered limiting on the present disclosure. In various embodiments, the thickness of the coating 1330 will be in the range of 10 microns to 4,000 microns (0.010 mm to 4 mm), but in various embodiments the thickness will not be in the range of 10 microns to 4,000 microns and the disclosure of a coating 1330 having a thickness of 10 microns to 4,000 microns should not be considered limiting on the present disclosure.
During operation of acoustic drying system 100, material 1300 is placed on conveyor belt 160 inside a holder 1100 (shown in
In various embodiments, it is beneficial to keep material 1300 in tension because a material 1300 in tension, especially a thinner material, will respond to the acoustic waves 250—ultrasonic waves, for example—differently than a material 1300 that is not in tension. A material 1300 in tension will tend to move itself as a result of the acoustic waves 250—ultrasonic waves, for example. As will be explained below, the degree of movement of the material 1300 and the degree of disruption of the boundary layer at the surface of the material 1300 will depend on a number of factors including the unsupported length of the material, the stretching or tensile force on the material 1300, and the mass per unit length of the material 1300. Specifically, the system is specifically designed in the current embodiment with idler rollers placed a certain distance apart to control the area of the section of film being dried acoustically, the surface tension of the film (S) being controlled by the tension between an unwind roller and a re-wind roller, and the mass density per unit area of the film (σ) being constant for a particular film.
In various embodiments of the indirect drying process, a tensile force is applied to the material 1300 in order to maintain the material 1300 in the aforementioned state of tension during the drying step. This can be especially beneficial when the drying equipment is positioned facing the side opposite the side of the material 1300 being dried. In some embodiments due to the thickness of the substrate or material 1300 or simply for simplicity, tension will be expressed as pounds of force per linear inch of web width, the tension being applied until the coating reaches a desired moisture content level. This desired moisture content level will vary depending on the application and will determine when the drying process is complete. The tension will in various embodiments be maintained in the range of 0.5 pounds per linear inch of web width to 4 pounds per linear inch of web width in order to effectively dry the coating 1330 or the material 1300 without the coating, though different amounts of tension are present in various other embodiments.
The relationship between the acoustic waves—including ultrasonic waves—and the material response can be represented by the following “dispersion relation”:
Where omega ω is the time period of one fundamental oscillation (inversely proportional to the fundamental frequency), and kx and ky are constants that relate to the length of the film section and the width of the film section.
This equation is analogous to Mersenne's laws which state that the fundamental frequency of a length of string is as follows:
While not limited by theory, this disclosure includes tuning the film or material 1300 to resonate with the acoustic field, either at the fundamental frequency, or at a higher harmonic of the fundamental frequency. This will have the effect of disturbing the boundary layer at the surface by a greater degree and increasing the heat transfer rate and therefore also the drying rate.
Where a material 1300 includes both the substrate 1305 and wet coating 1330, the material 1300 is positioned so that the first side 1310 is facing the acoustic head 120 and the second side 1320 with coating 1330 is facing away from the acoustic head 120.
The next step involves moving the material 1300 in a transverse direction relative to the acoustic head 120 and an air delivery unit 265 (shown in
The final step involves drying the material 1300 using a combination of acoustic waves 250 (shown in
In various embodiments of the system of
In various embodiments, a butt-roll of Skyrol® SH-76, 300 gauge, 0.050 mm (50 micron) thick polyethylene terephthalate (PET) film (available from SKC Inc., Covington Ga.) is cut into approximately 8 inches wide by 12 inches long, and fastened to a flat coating pad surface. Meyer rods are used to make draw-down coatings. Coated pieces of substrate are placed in a hinged holder 1100 and secured to the holder 1100 using 2-inch wide masking tape of the variety commonly available from painting supply and home improvement stores. The film is then stretched taught during the securing process so that it is tensioned into a substantially flat surface.
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Inputs to control panel 260 are pressure readings 285 at the outlet of the blower fan 275 and air temperature readings 290 at heater 280. Based on the material 1300 and/or coating 1330 being dried, the air pressure, air temperature 292, and the strength of acoustic waves 250 at the surface of the material 1300, or other characteristics of the system can be controlled at control panel 260. Blower motor 270, blower fan 275, heater 280, an inlet duct 266, and the delivery air inlet 130 of acoustic head 120 make up air delivery unit 265.
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In various embodiments, the ultrasonic transducer 1000 has more or fewer grooves 1044, deeper or shallower grooves 1044, different shaped grooves 1044, grooves 1044 that do not extend the entire length of the walls 1036, a greater spacing between the grooves 1044 on the same wall 1036, or a greater spacing between the walls 1036. In other various embodiments, the ultrasonic transducer 1000 has a U-shaped air passage 1040 that induces the acoustic waves 250. And in still other various embodiments, the ultrasonic transducer 1000 is provided by another design of pneumatic transducer and/or by an electric-operated ultrasonic transducer.
In various embodiments, the ultrasonic transducer 1000 is operable to produce fixed frequency acoustic waves 250 in the ultrasonic sound pressure range of about 120 dB to about 190 dB at the interface surface of the material 1300 being treated, though other decibel ranges may be present in various embodiments. In various embodiments, the ultrasonic transducer 1000 is designed for producing acoustic waves 250 in the sound pressure range of about 130 dB to about 185 dB at the interface surface of the material 1300 being treated, more preferably about 160 dB to about 185 dB, and in other various embodiments about 170 dB to about 180 dB. These are the decibel levels at the interface surface of the material 1300, not necessarily the output decibel level range of the ultrasonic transducer 1000. In typical commercial embodiments, the ultrasonic transducer 1000 is selected to generate up to about 170 to about 190 dBs, though higher or lower dB transducers could be used.
Sound intensity (including the intensity of ultrasound) dissipates with the second power to the distance, so the closer the ultrasonic transducer 1000 is positioned to the material 1300, the lower in the dB range the dB level generated by the transducer can be. Many applications, by the nature of the process, require a transducer-to-material separation distance D of from about 4 mm to about 100 mm as stated previously, though other separation distances D are present in various embodiments. The larger the separation distance D, the higher the dB level that generally should be generated by the ultrasonic transducer in order to obtain the needed dB level at the interface surface of the material 1300. In addition, dB levels above the high end of the dB range could be used in some applications, but generally the larger transducers that would be needed are not as cost-effective and the sound level would be so high that humans could not safely or at least comfortably be present in the work area.
As shown in
In order for the ultrasonic transducer 1000 to be spaced from the material 1300 in this way, the acoustic head 120 can be provided with a register surface 161 for fixing the separation distance D. In various embodiments, the register surface 161 can be provided by a flat sheet and the material 1300 can be conveyed across it on a conveyor belt 160 driven by drive rollers before and after the sheet. In various other embodiments, the register surface 161 can be provided by one or more rollers that support material 1300 directly, by a conveyor belt 160 supporting the material 1300, or by another surface known to those skilled in the art. In any event, the register surface 161 is spaced the separation distance D from the ultrasonic transducer 1000 (or positioned slightly more than the separation distance D from the ultrasonic transducer to account for the thickness of the material 1300 and the conveyor belt 160). Embodiments without a register surface 161 are often used when the material 1300 is web-based, otherwise self-supporting, or tensioned by conventional tensioning mechanisms. In various embodiments, the material 1300 will be stretched across a register surface 161 in the same way that the material 1300 inside holder 1100 holds the material 1300 in tension. In various other embodiments, the tensioning mechanism will include idler pulleys which maintain tension in a material 1300′ (shown in
As stated previously, the acoustic head 120 can be provided with the aforementioned support and positioning mechanism 220 for maintaining or adjusting the separation distance D between the ultrasonic transducer 1000 and the material 1300. The support and positioning mechanism 220 may be provided by conventional devices including but not limited to rack and pinion gearing, screw gearing, or mechanical fasteners. The support and positioning mechanism 220 may be designed to move the air delivery enclosure 420, air return enclosure 410, and one or more ultrasonic transducers 1000 of acoustic head 120 closer to or further away from material 1300 by moving the acoustic head 120 or by moving the material 1300 or by moving both the acoustic head 120 and the material 1300.
In order to consistently produce the precise decibel levels at the interface surface of the material 1300, a method of manufacturing and/or installing the acoustic head 120 is provided. The method includes calibrating the acoustic head 120 for the desired decibel levels. First, the separation distance D is calculated based on the frequency of the selected ultrasonic transducer 1000. For example, an ultrasonic transducer 1000 with an operating frequency of 33,000 Hz has a wavelength of about 0.33 inches at a fixed temperature, so acceptable separation distances D include (0.33)(¾) equals 0.25 inches and (0.33)(5/4) equals 0.41 inches, based on the formula D equals (λ)(n/4). Similarly, an ultrasonic transducer 1000 with an operating frequency of 33 kHz has a wavelength of about 0.41 inches, so acceptable separation distances D include (0.41)(¾) equals 0.31 inches and (0.41)(5/4) equals 0.51 inches.
Then the ultrasonic transducer 1000 is positioned at the calculated separation distance D from the first side 1310 of material 1300 (or from the conveyor belt 160 that will carry the material 1300, or from the register surface 161). Next, a sound input device (e.g., a microphone, not shown) is placed at the material 1300 (or at the conveyor belt 160 that will carry the material 1300, or at the register surface 161, or at the separation distance D from the ultrasonic transducer 1000). The sound input device is connected to a signal conditioner (not shown). The sound input device and the signal conditioner are used to measure the air pressure wave (i.e., the acoustic waves 250) in psig and convert that to decibels (dB). For one example among others, at a temperature of 120° F. and a flow rate of 35 ft/sec, a sound wave measured at 5 psig converts to 185 dB. Suitable microphones and signal conditioners are commercially available from Endevco Corporation (San Juan Capistrano, Calif.) and from Bruel & Kjer (Switzerland).
Once this baseline decibel level has been determined, the acoustic head 120 can be adjusted for maximum effectiveness. For one example among others, the support and positioning mechanism 220 can be adjusted to alter the preset separation distance D to see if the decibel level increases or decreases at the altered separation distance D. If it decreases, then the preset separation distance D was accurate to produce the maximum amplitude A, and this separation distance is used. But if it increases, then the altered separation distance D is used as the new baseline and the separation distance D is adjusted again. This fine-tuning process is repeated until the maximum amplitude A within the design range is found. The adjustment of separation distance D by support and positioning mechanism 220 can be made by direct manipulation of support and positioning mechanism 220 or it can be made by automatic electronic control based on one or more various inputs including but not limited to the conveyer speed, the type of coating system, the coating rod diameter in the case of a rod coating system, substrate specification, substrate thickness, coating specification, coating thickness, acoustic wave strength, air pressure, air speed, and air temperature.
In addition, because the depicted embodiment includes a pneumatic-type ultrasonic transducer 1000, it is operable to produce the desired decibel levels by adjusting the flow-rate of the inlet airflow 1350. So if the baseline decibel level is not in the desired range, then the inlet airflow 1350 rate can be adjusted (e.g., by increasing the speed of the fan or blower) until the decibel level of airflow 1355 is in the desired range. The same procedure can be applied to electrically-powered ultrasonic transducers. Similar adjustments can be made with a signal amplifier, when electrically-based ultrasonic transducers are used.
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These steps will vary slightly or may not be present in various embodiments depending on the equipment being used and depending on the application. There may be additional steps added to the process. For other coating methods, the steps taken may be completely different. In addition to the roll-to-roll coating processes listed above, other coating processes will be used in various embodiments including but not limited to vapor deposition, conversion coating, plating, spraying, and roll-to-roll coating methods other than those already mentioned.
What is sometimes important in the selection of a coating method and coating thickness is the selection of a coating method that will apply the desired coating thickness in such a way that it will meet the aesthetic and functional requirements of that coating 1330. Aesthetic requirements may dictate that one or more colors, one or more patterns, text or any number of finishes—including but not limited to those finishes described as gloss, satin, or matte—be applied consistently to the substrate 1305 across large numbers of product and across multiple production runs spread out over time. Functional requirements may dictate that the coating 1330 or a material 1300 without the coating 1330 that is nonetheless being dried be able to consistently exhibit certain adhesion, wetability, corrosion resistance, wear resistance, electrical conductivity, electrical insulation, or other physical properties after the coating has dried sufficiently.
In various embodiments, material 1300′ is transported and kept taught across idler rollers 1250a-f. Between idler rollers 1250b-f, a series of four acoustic heads 120′ successively dry the material 1300′, now with coating 1330′, until the point at which material 1300′ is caused to join a release paper 1225 from a release paper roll 1220. Rewinding roll 1230 pulls lengths of material 1300′ from unwinding roll 1210 and release paper roll 1220 through rolls 1260a-c. In various embodiments, the release paper 1225 is omitted or may be made out of some material other than release paper 1225 that will achieve a similar purpose or have a similar structure as release paper 1225. Idler roller 1250g helps provide tension on release paper 1225 before release paper 1225 is combined with material 1300′.
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One should note that conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more particular embodiments or that one or more particular embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.
It should be emphasized that the above-described embodiments are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Any process descriptions or blocks in flow diagrams should be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process, and alternate implementations are included in which functions may not be included or executed at all, may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the present disclosure. Further, the scope of the present disclosure is intended to cover any and all combinations and sub-combinations of all elements, features, and aspects discussed above. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure.
