Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
  • B05D3/0254—After-treatment
  • B05D3/0263—After-treatment with IR heaters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B15/00—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form
  • F26B15/10—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions
  • F26B15/12—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined
  • F26B15/122—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined the objects or batches of material being carried by transversely moving rollers or rods which may rotate
  • F26B15/128—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined the objects or batches of material being carried by transversely moving rollers or rods which may rotate the rods being attached at one end to an endless conveying means, the other end being free to receive hollow articles, e.g. cans
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/26—Making hollow objects characterised by the use of the objects cans or tins; Closing same in a permanent manner
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B15/00—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form
  • F26B15/10—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions
  • F26B15/12—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined
  • F26B15/18—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined the objects or batches of materials being carried by endless belts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B3/00—Drying solid materials or objects by processes involving the application of heat
  • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
  • F26B3/04—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour circulating over or surrounding the materials or objects to be dried
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B3/00—Drying solid materials or objects by processes involving the application of heat
  • F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
  • F26B3/30—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun from infrared-emitting elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2202/00—Metallic substrate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/22—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes
  • B05D7/227—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes of containers, cans or the like

Definitions

• D&R draw-redraw process
• D&l draw and iron process
• DWI draw-wall iron process
• the second step in the D&l process involves successively ’’ironing” the walls of the cup until they are at the correct and desired thickness and dimension.
• a substantial amount of engineering and experimentation has gone into the process and into the final developed shape at both the bottom and ultimately, in a later process, the neck of the can.
• the exact shape geometry is critically important so the finished can is able to sustain the pressure that will be exerted by the gases from the liquid food or beverage with which the can will be filled.
• This structural shaping is intended to hold the pressure along the sidewalls but ultimately has to prevent the dome shaped bottom from actually failing with what is referred to as bottom reversal failure.
• FIG. 6 an example process 600 for forming cans using D&l is illustrated. As shown, cans are formed using an uncoiler (602), lubricator (604), cupper (606), bodymaker (608) and trimmer (610). Those of skill in the art will appreciate the form and function of these elements in the typical D&l process.
• the cans are in a straight-walled, un-necked can shape, they are washed using a washer (612) and dried using, for example, a gas dryer oven (614) at approximately 400°F before being put through a coating process, including an interior coating process.
• the coating process is initiated by optionally applying a base coat of ink to the exterior of the cans using a basecoater (616) and then drying any applied basecoat using an optional basecoater oven (618) operated at approximately 400°F.
• a basecoater 618
• the cans are run through a decorator (620) to apply the ink pattern to the outside surfaces of the cans and a bottom coater (622) to apply a layer of protective coating to the bottoms of the cans.
• the cans are next sent to a deco oven (624) (also operated at approximately 400°F) to dry the applied exterior coatings.
• an internal coating process is initiated to coat the inside surfaces of the cans.
• the internal coating process generally involves a single file line of cans going through an internal coater (626), either an indexing starwheel or a continuous running starwheel, in which spray guns are actuated which coat the inside of the can.
• the spray guns are highly developed to direct a very fine mist of wet coating into the can such that all surfaces are covered.
• the can rotates under the spray gun during the operation to provide even coverage around the 360 degree inside perimeter of the can.
• the goal is for the can to rotate two to five revolutions while the interior is being sprayed.
• the coating looks like thin white paint adhering to the surfaces of the entire inside of the can.
• the cans are spun at high speed during the process to use centripetal force to even out the coating. It is important that the spray coating goes on at the right thickness so that it provides adequate coverage of the aluminum or steel can stock. It can be neither too thin nor too thick to perform properly. If it is too thick, it can cause runs and thick areas which may not cure properly and will waste coating. Immediately after the spray coating process, the cans must be thermally cured, in an inside bake oven known as an IBO (628).
• the single file line of cans coming out of the spray coater is routed to mass conveying.
• the mass conveyor material handling groups the cans as close together as they can be nested several dozen wide across a wide conveyor which can range from 30 - 80” wide.
• the conveyor belting on which the cans are transported through the IBO (628) is designed to handle the repetitive rigors of high temperature so that the belting material can safely pass through the oven to convey the cans through the curing oven.
• the trip through the curing oven will typically take from two to four minutes.
• the oven will typically have multiple heat sections that the cans pass through progressively.
• a typical IBO oven configuration would introduce the cans to the first section of oven which would subject the cans to 200 - 270° Fahrenheit for about 60 seconds as a pre-heat. Section or zone two would raise the temperature to 270 - 400° for another roughly 60 seconds. The final section or zone 3 would typically hold the temperature at 380 - 450° Fahrenheit for approximately a final 60 second cure. The cans spend a total of about 180 seconds in the oven, which timing may vary some, but this represents the traditional circumstance. [0008] As the mass conveyed cans exit the IBO, the epoxy coating on the inside should look virtually clear if properly cured. Clarity is an indicator but does not guarantee that the coating is fully cured. It must be tested in a lab to be certain.
• the concept with an IBO is to gradually bring the temperature of the mass conveyed cans up to the full curing temperature and then ascertain that it has been held at 380 - 450° Fahrenheit for at least a minimum number of seconds. This is the time necessary for the epoxy coating to start the binding or linking process which is required for proper, full curing. That linking process, once initiated by this “time at temperature”, will continue until fully cured if it has actually been held above the 375° temperature for the designated time. As was mentioned, “clear” compound does not mean that it is properly cured. It will turn clear, even if the correct linking temperature has never been initiated if a slightly lower temperature at time was provided.
• the cans exit the I BO (628) they are sent to a waxer (630) for further processing.
• a necker (632) and flanger (634) are utilized to complete the can forming process, as those of skill in the art will appreciate.
• a light tester (636) may also be used.
• the formed cans are sent to a palletizer (638).
• This process is used worldwide and is widely accepted as the standard for safe food and beverage packaging in two-piece cans. The same or very similar process is often used on other types of cans as well.
• cans have to be manufactured so they are actually stronger than the end specification. They lose about 8-10% of the bottom reversal strength that they are required to have for proper performance as a result of the IBO oven trip. They must maintain 92 to 95 PSI of pressure containment strength before “bottom reversal” for carbonated soft drinks, and 105 to 110 PSI for beer.
• This high-speed softening, de-strengthening or annealing has the effect of reducing the tensile and yield strengths of the aluminum alloy so that the aluminum has to be thicker in order to have the required strength compared to a non-annealed can.
• the gas dryer oven (e.g. 614 in Figure 6) which dries the cans after the washer, is configured as a very wide mass conveyor with the cans open end down so they can drain.
• the width of the conveyor can vary depending on the throughput of the plant, but is often from 20 to 40 standard 12-ounce cans wide.
• the drying oven often has a set point of between 400 and 420 degrees Fahrenheit and typically maintains a temperature from 25 to 50 degrees cooler than the actual set point.
• the time to travel through the oven is typically from 1 .5 to 2.0 minutes at a conveyor belt speed which is typically between 15 and 25 feet per minute.
• the washing process consists of multiple stages which usually is six stages. After a can comes out of the body maker, it is covered in the drawing fluid/cooling compound which is used to improve the processing. This must be washed off and cleaned before it can be further processed into a finished can. After the can exits the body maker, it usually slides down a set of trackwork on to some kind of conveyance means whereby it is merged together with many other cans to form a wide and contiguous flow of cans which merge on to the mass conveyor. The cans are at this point upside down so that the water will readily run out of them by gravity. As a mass group, the cans slowly proceed through the washer and get sprayed in two successive steps with (usually) hydrofluoric acid.
• the pin chain oven or deco oven as it is sometimes called (e.g. 624 in Figure 6), is arranged to receive the can at the exit of the decorator. Its whole purpose is to transport the can through a drying oven without allowing the exterior surfaces of the freshly decorated can to touch anything. Any slightest touch will smear the ink that is still wet.
• a pin chain conveyor At its heart, it is a link belt or motorcycle chain style “belt” which is configured to zig and zag around a series of sprockets to take it through a serpentine or zig-zag path through the oven.
• the purpose for the serpentine path is to dramatically increase the dwell time that the can spends in the oven so that it has sufficient time to dry the ink.
• Each can rides on a pin which is somewhat longer than the inside depth of the can.
• Each pin is effectively an extension of the hinge pin that engages with the sprocket from each link.
• the spacing varies but they are generally arranged so that the cans are approximately spaced with one can diameter between each of the cans.
• the belt travels at a high rate of speed so that it can keep up with the output of the decorator which may be as high 2800 cans per minute.
• the serpentine weave of the belts of the pin chain conveyor create a plane through the oven. That plane is tilted back so that gravity helps hold the cans in place during their travel through the oven.
• the oven is gas-fired and creates a high acoustic noise level because of the blowers that blow super-heated air at the cans such that it functions like a convection oven.
• the heat set point is often in the range of 450 degrees but due to the openness of certain sections of the oven and the high air volume throughput, the actual maintained temperature is 60 to 90 degrees cooler than the set point.
• the pin chain oven heats the plant substantially as well. Again, the specification will vary from plant to plant, but a can may typically spend between 15 and 25 seconds in the pin chain oven.
• All three of these large ovens are inefficient in that they heat much more than just the cans that they intend to heat. They burn large amounts of natural gas or hydrocarbon-based fuels which basically heats the air which then secondarily heats the cans and coatings/water. This two-step heating process is a big contributor to the slow and inefficient heating of the cans. They are also large electrical energy consumers with many high horsepower motors running not only the conveyors themselves, but many blowers for purposes of directing and concentrating the heat as well as for scrubbing the exhaust air and facilitating appropriate exhaust. The composite of the three ovens also creates a very high heat plant situation which creates an uncomfortable working environment and can dramatically increase the HVAC costs, depending on where the plant is located. For plants which are located in an area of the world where it is desirable or required to air-condition it, this extra heat load is a huge energy consumer and large contribution to the carbon footprint.
• the gas drying oven pursuant to the inside washing, because it subjects the can to such high temperatures for 1.5 to 2.0 minutes, also contributes to the annealing or de-strengthening process in a similar way, but to a slightly less extent than the IBO oven. Similarly, this means that the can must be made out of more aluminum to have the same strength that a non-weakened can would normally have. So the drying oven not only uses very large amounts of hydrocarbon fuel and electrical energy along with high maintenance costs, it also weakens the can and reduces its ultimate strength and performance.
• the pin chain oven creates similar problems but causes slightly less weakening as a result of the shorter exposure time. Although the can spends from 15 to 20 seconds generally in the pin chain oven, it usually has the highest set point temperature of 430 to 460 degrees Fahrenheit. Since the annealing effect is a combination of time and temperature, the pin chain oven contributes further to the weakening and annealing effect.
• the pin chain itself has many moving parts which need to be lubricated. In an exuberance to try to maintain adequate lubrication, the pin chain is usually over lubricated which then causes ongoing housekeeping and contamination problems. The pins themselves often have a tendency to get bent and cause their own loading, unloading, and crash issues. Again, the high maintenance costs, the high hydrocarbon fuel costs, and the inhibited can performance all are problems that the can manufacturing plant would like to reduce or eliminate.
• a system for use in can manufacturing wherein cans are washed, decorated and/or a coating has been sprayed onto an inside surface of cans comprises a first station including a first array of semiconductor-based narrowband irradiation devices positioned to irradiate and dry the cans through a mesh or open-spaced belt of a mass conveyor or to individually irradiate and dry individual cans through selective elements of a serial conveyor, wherein the first station is configured to dry the cans in less than 60 seconds, a second station including a second array of semiconductor-based narrowband irradiation devices positioned to irradiate and cure ink applied to outsides of cans being transported on aconveyor, wherein the second station is configured to cure the ink in less than 20 seconds and a third station including a third array of semiconductor-based narrowband irradiation devices positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned
• the first station is configured to dry the cans in less than 50 seconds, 40 seconds, 30 seconds or 20 seconds.
• the second station is configured to cure the ink in less than one of 15 seconds, 10 seconds or 5 seconds.
• At least one of the third station is configured to heat the cans to the critical linking or cross-linking temperature in the coating in less than one of 10 seconds, 5 seconds or 2 seconds, and the coating is optimized for narrowband curing.
• a method for use in can manufacturing wherein cans are washed, decorated and/or a coating has been sprayed onto an inside surface of cans comprises with a first array of semiconductor- based narrowband irradiation devices at a first station, irradiating and drying the cans through a mesh or open-spaced belt of a mass conveyor or individually irradiating and drying individual cans through selective elements of on a serial, single-file conveyor, with a second array of semiconductor-based narrowband irradiation devices at a second station positioned after an ink decorator, then irradiating and curing ink applied to outsides of cans which are being transported on a conveyor and with a third array of semiconductor-based narrowband irradiation devices at a third station, individually and electrically heating inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production
• the curing of the ink occurs in less than one of 15 seconds, 10 seconds or 5 seconds.
• the inside coating reaches the critical linking or cross-linking temperature is reached in less than one of 10 seconds, 5 seconds or 2 seconds.
• a system for use in can manufacturing wherein cans are washed, decorated and/or a coating has been sprayed onto an inside surface of cans comprises a first station including a first array of semiconductor-based narrowband irradiation devices positioned to irradiate and dry the cans through a mesh or open-spaced belt of a mass conveyor, the first array being positioned to face the inside of the cans and within a housing, the housing having a protective window positioned and sealed to prevent moisture from entering the array housing, the protective window being optically transparent at an applied wavelength, the first array also being provided with at least one of reflective baffles to guide irradiation towards the cans or optical elements to selectively spread or narrow beams of the irradiation, the system being configured such that the irradiation does not exit the system.
• the protective window is at least one of mounted at an angle to promote water runoff toward a trough or gutter positioned near an edge of the protective window or provided with an anti-reflective coating that is functional at applied narrow wavelength bands.
• the system further comprises at least one of fans or blowers to provide higher speed air flow at the mouths of the cans to remove water vapor more efficiently.
• the system further comprises a second station having a second array of semiconductor-based narrowband irradiation devices positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds to prevent de-tempering or annealing from occurring in the can.
• a system for use in can manufacturing wherein cans are washed, decorated and/or a coating has been sprayed onto an inside surface of cans comprises a first station including a first array of semiconductor-based narrowband irradiation devices positioned to irradiate and cure ink applied to outer surfaces of cans being transported on a pin chain, the first array being positioned along the pin chain to irradiate an outer surface of an oncoming can at a first angle, a second station including a second array of semiconductor-based narrowband irradiation devices positioned to irradiate and cure ink applied to the outer surfaces of the cans being transported on the pin chain, the second array being positioned along the pin chain to irradiate the outer surface of the oncoming can at a second angle, different from the first angle and corner cube reflector material strategically positioned relative to each station substantially orthogonal to a tangent of the outer surfaces of the cans and between arrays such that ir
• the system further comprises a third station having a third array of semiconductor-based narrowband irradiation devices positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds to prevent de-tempering or annealing from occurring in the can.
• the system further comprises a plurality of additional stations including arrays of semiconductor- based irradiation devices to irradiate and cure ink applied to the outer surfaces of cans, each array being positioned at a strategic angle so the combination of the plurality of stations will irradiate the ink around the entire outer surface of each can.
• the system further comprises a ventilation system to carry vapor, including at least volatile organic compounds, from the first and second station to a thermal or catalytic destruction unit, wherein the ventilation system maintains the vapor at a minimum threshold temperature.
• the system further comprises a drying station including at least one array of semiconductor-based narrowband irradiation devices positioned to irradiate and dry the cans through a mesh or open-spaced belt of a mass conveyor or to individually irradiate and dry individual cans through selective elements of a serial conveyor, wherein the drying station is configured to dry the cans in less than 20 seconds.
• a system for use in a can manufacturing inside coating and curing process wherein coating has been sprayed onto an inside surface of a can comprises a can handling system configured to serially move production cans into at least one curing zone, arrays of semiconductor- based narrowband irradiation devices positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds to prevent de tempering or annealing from occurring in the can and a ventilation system to carry vapor, including at least volatile organic compounds, to a thermal or catalytic destruction unit, wherein the ventilation system maintains the vapor at a minimum threshold temperature.
• a system for use in a can manufacturing inside coating and curing process wherein coating has been sprayed onto an inside surface of a can comprises a can handling system configured to serially move production cans into at least one curing zone, broadband infrared sources positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned to direct irradiation toward upper sidewalls of the inside surface of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds to prevent weakening, de-tempering, or annealing from occurring in the can body, a ventilation system to carry vapor, including at least volatile organic compounds, to a thermal or catalytic destruction unit, wherein the ventilation system maintains the vapor and outgassed compounds in the vapor at a minimum threshold temperature.
• a system for use in can manufacturing wherein cans are washed, decorated and/or a coating has been sprayed onto an inside surface of cans comprises a first station including a plurality of arrays of semiconductor-based narrowband irradiation devices positioned to irradiate and cure ink applied to outsides of cans being transported on a pin chain conveyor, wherein the arrays of the first station are configured to cure the ink in less than 20 seconds and a second station including a second configuration of arrays of semiconductor-based narrowband irradiation devices positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds to prevent de-tempering or annealing from occurring in the can.
• a system for use in can manufacturing wherein cans are washed, decorated and/or a coating has been sprayed onto an inside surface of cans comprises at least one of a first array of semiconductor-based narrowband irradiation devices positioned to irradiate and dry the cans through a mesh or open-spaced belt of a mass conveyor or to individually irradiate and dry individual cans through selective elements of the serial conveyor, a second array of semiconductor-based narrowband irradiation devices positioned to irradiate and cure ink applied to outsides of cans being transported on a pin chain and a third array of semiconductor-based narrowband irradiation devices positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than
• a method for use in can manufacturing wherein cans are washed, decorated and/or a coating has been sprayed onto an inside surface of cans comprises at least one of with a first array of semiconductor-based narrowband irradiation devices, irradiating and drying the cans through a mesh or open-spaced belt of a mass conveyor or to individually irradiate and dry individual cans through selective elements of on the serial conveyor, with a second array of semiconductor-based narrowband irradiation devices, irradiating and curing ink applied to outsides of cans being transported on a pin chain and with a third array of semiconductor-based narrowband irradiation devices, individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds
• a method for use in a can manufacturing inside coating and curing process wherein coating has been sprayed onto an inside surface of a can comprises generally transporting the cans toward at least one curing station and individually and electrically heating the cans using narrowband radiant infrared energy and optical elements positioned outside of the cans in the at least one curing station such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to start a curing linking process in the coating, in less than 20 seconds to prevent de-tempering or annealing from occurring in the can.
• each can is formed from manufacturing tooling reconfigured to reduce a diameter of a cut edge of a blank from which a starting cup for the can is drawn whereby a thickness of coil stock aluminum is substantially the same as before tooling reconfiguration but such that the coil stock is narrower, thus reducing the weight of aluminum required to manufacture each can by greater than 3%.
• each can is formed using a can design and tooling that is modified to manufacture the can out of thinner coil stock material to reduce the aluminum from which the can is manufactured, whereby the heating to accomplish the linking curing process in less than 20 seconds eliminates a reduction in strength of the can such that the can will have similar sidewall axial strength, bottom reversal strength, and overall strength as compared to a thicker can cured for a longer time, which longer time weakened the metal.
• the electric curing of the coating is implemented by a narrowband, semi-conductor based radiant heating system.
• a semiconductor-based system producing the narrowband radiant energy may be turned on or off within microseconds and can heat the coating and/or the can to curing temperature in less than 10 seconds.
• a conveyer transports the cans during the curing process and utilizes continuous rotary motion whereby the at least one irradiation curing station is in continuous rotary motion synchronous with the cans being cured thereby and at least one of electrical power, cooling liquid, and control signals are connected to the at least one curing station through a rotary union.
• At least one of DC power supply, cooling heat exchanger, cooling chiller, cooling recirculation pump, and control system which serve the at least one curing station are moving in a rotary motion and synchronously with the cans, providing for a continuous rotary motion curing system wherein the continuous motion of the system helps in the cooling function.
• a conveyer transports the cans during the curing process and utilizes an indexing rotary motion whereby multiple irradiation curing stations are located around the periphery of, but not on, a turret such that a group of cans is serially loaded into a selected number of empty stations around the turret while the turret is rotationally indexing so that the cans are each under their respective narrowband curing stations, the curing stations are actuated to cure the cans and then the turret is again rotationally indexed, which takes the cured cans out while a new set of cans is indexed into their positions under the curing stations for curing and the process continues to repeat.
• cans are individually cured in less than 5 seconds.
• narrowband semiconductor devices emit the narrowband radiant infrared energy at a wavelength matched to an absorption characteristic of the coating on the inside surface of each successive can.
• a wavelength of the narrowband radiant infrared energy used to heat is in a range of one of 800 nm to 1200 nm, 1400 nm to 1600 nm, and 1850 nm to 2000 nm.
• the narrowband infrared radiant energy used to heat is produced using at least one of semiconductor- based irradiation devices, light emitting diodes (LEDs) and laser diodes.
• LEDs light emitting diodes
• the semiconductor devices that produce the irradiation are configured in multi-device arrays which combine the optical output power of more than 10 individual semiconductor devices to produce a total optical output power of more than 100 watts.
• the semiconductor devices are laser diodes and such that the full width / half max output bandwidth is narrower than 20 nanometers.
• the semiconductor devices are surface emitting laser diodes whose full width / half max output bandwidth is narrower than 2 nanometers.
• the energy sources are comprised of arrays of surface emitting laser diodes producing their photonic energy output between 825 to 1075 nanometers.
• material/can handling facilitates individual curing of one lane of cans at production speeds in excess of 300 cans per minute.
• multiple parallel curing stations are arranged to individually cure at a total throughput speed in excess of 1 ,800 cans per minute while running all lanes except one, that lane being available for any maintenance that may be required or to provide additional production if needed so that a higher level of overall up-time may be achieved.
• the method eliminates hydrocarbon-based fuel use and more than 3% of aluminum is saved in a can manufacturing process as a result of higher speed, under 20 second curing which eliminates annealing and weakening of aluminum of a can body.
• the method facilitates reformulation of the coating to eliminate BPA or other undesirable components in the coating formulation.
• equipment configurations of the curing method can be started and stopped easily without deleterious effect on the cans or the production process.
• implementation provides the ability to instantaneously and while in motion respond to modulation of the method as a result of sensory gained information from an inspection system.
• a system for use in a can manufacturing inside coating and curing process wherein coating has been sprayed onto an inside surface of a can comprises a can handling system configured to serially move production cans into at least one curing zone, arrays of semiconductor- based narrowband irradiation devices positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned outside the open end of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in less than 20 seconds to prevent de-tempering or annealing from occurring in the can.
• the arrays of semiconductor-based narrowband irradiation devices and the optical elements are positioned just outside a top plane of a cut edge of the cans and aim over 90% of narrowband infrared photonic energy produced by the semiconductor-based narrowband irradiation devices into an interior of a can being cured with the majority of energy being focused on the upper half of the sidewall so that the internal reflections expose the lower portions of the can.
• the optical elements comprise at least one micro-lens array aligned with respective devices of the arrays of semiconductor-based narrowband irradiation devices to form columnated energy, a condenser lens configured to focus the columnated energy toward and through a pinhole or aperture element and into an interior of a can being cured, and the pinhole or aperture providing an opening through the vortex of a reflective engineered shaped surface which functions to redirect narrowband energy which otherwise would have escaped from the can, back into the can.
• the reflective conical surface is equipped with ventilation slots or openings to facilitate vapor removal from a curing can.
• the reflective engineered surface is roughly conical and is made of one of copper, aluminum, gold plated metal, silver plated material, and highly reflective nano-structure.
• the optical elements and the arrays of semiconductor-based narrowband irradiation devices are mounted in a housing configured to prevent stray infrared energy from escaping from the housing, except through the pinhole or aperture element and is configured with a recirculating water cooling arrangement to keep the arrays and optical elements at an acceptable operating temperature in the production curing environment.
• the arrays of semiconductor-based narrowband irradiation devices includes at least one array of laser diodes which are positioned outside the can and the corresponding optical elements are articulated into the inside of each can during at least a portion of the curing.
• the optical elements comprise an objective lens configured to receive energy from the arrays of semiconductor-based narrowband irradiation devices via an optics and mirror assembly and the system further comprises insertion and withdrawal mechanisms to translate the optical elements into the cans through reflection containment plates configured to be positioned above each can so that the optical transfer of energy is aligned when the insertion mechanism positions a portion of the optical assembly inside the can so the irradiation can be activated when the optical train is positioned properly inside the container to effect the curing.
• a system for use in can or container manufacturing for curing a coating which has been sprayed onto the inside walls of said containers comprises an ingoing trackwork or conveyor configured to organize or facilitate movement of individual containers into single-file order toward a second conveyor, the second conveyor being configured as a rotary turret to move the individual containers into and away from at least one curing station, the at least one curing station comprising an optical configuration wherein photonic energy from at least one array of surface emitting laser diodes passes through columnating optics and then is focused by at least one condensing lens element through a pinhole or aperture where beyond the photonic energy diverges to irradiate inside sidewalls of a coated container, such pinhole or aperture being located at the vertex of a reflective cone such reflective cone functioning to reflect photonic energy back into the container to effect further curing work, wherein the coating is cured in less than 20 seconds, thus being fast enough to prevent weakening or annealing from taking place in aluminum comprising the container
• the subsequent manufacturing operations include an inspection station located on the third conveyor, the function of which inspection station is at least to verify veracity of the coating and curing by way of imaging inside each container and searching for bare metal areas, and to the extent that an imaged quality level of the cured coating is not sufficient, rejecting the container with a faulty coating at a rejection station which is configured into the third conveyor after the inspection station and then sending signals to at least one of a coating system control system and a curing control system to correct the respective process.
• a system for use in can or open top container manufacturing for curing a coating which has been sprayed onto the inside surface of said container comprises an ingoing trackwork or conveyor configured to move single-filed individual containers toward a second conveyor, the second conveyor being configured to use a rotary motion table to move said containers into and away from at least once curing stations, the at least one curing stations incorporating one of an engineered reflector which will serve to re-direct the photonic energy from the arrays through the open top of the container and directly onto the sprayed coating on the inside surfaces of the container to effect curing process, wherein the coating is cured in less than 20 seconds, thus being fast enough to prevent weakening or annealing from taking place in aluminum comprising the container, the second conveyor configured to rotate to provide for exit for already cured containers to a third conveyor while new, uncured cans are serially loaded into the vacated positions, the third conveyor configured to receive the already cured containers an exit and convey them along toward next container manufacturing operations.
• the second conveyor is a rotating configuration which has multiple curing stations located around a periphery, each of which can be functioning simultaneously to cure the inside of a container with infrared energy produced by at least one laser diode array.
• the multiple curing stations comprises more than 8 curing stations.
• the second conveyor is a rotating configuration which has multiple curing stations which are rotated in synchrony with the containers so curing can continue without starting or stopping rotation of a table and wherein at least one of the electrical power, cooling, and control signals are connected to the curing stations through at least one rotary union.
• the ingoing trackwork or conveyor is configured to use gravity to advance the containers which are single-filed and pressure of gravity to feed each individual can into the second conveyor.
• a system for use in a can manufacturing inside coating and curing process wherein coating has been sprayed onto an inside surface of a can comprises a can handling system configured to serially move production cans into at least one curing zone, and broadband infrared sources positioned to individually and electrically heat inside surfaces of each can moved into a curing zone using optical elements positioned to direct irradiation toward upper sidewalls of the inside surface of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds to prevent de tempering or annealing from occurring in the can, and a control system configured to use sensor information to modulate output of the broadband infrared sources to maintain consistent curing temperature and results.
• FIGURE 1 shows an exemplary can to be cured using the presently described embodiments
• FIGURE 2 shows a system according to the presently described embodiments
• FIGURE 3 shows another system according to the presently described embodiments
• FIGURE 4 shows another system according to the presently described embodiments
• FIGURE 5 shows another system according to the presently described embodiments
• FIGURE 6 shows a flow diagram illustrating an exemplary prior method for forming cans
• FIGURE 7 shows another system according to the presently described embodiments
• FIGURE 8 shows another system according to the presently described embodiments
• FIGURE 9 shows another system according to the presently described embodiments.
• FIGURE 10 shows another system according to the presently described embodiments
• FIGURE 11 shows another system according to the presently described embodiments
• FIGURE 12 shows another system according to the presently described embodiments
• FIGURE 13 shows another view of the system of Figure 12 according to the presently described embodiments.
• FIGURE 14 shows another system according to the presently described embodiments.
• the presently described embodiments teach a completely new concept for applying heat to cans including for 1 ) curing the coating on the inside of food, beverage, and other types of cans, 2) drying cans after washing and 3) curing ink or coatings on the outside of cans.
• many of the implementations are suited to replace all or selected ones of the conventional ovens used in can manufacturing including, the gas dryer oven, the deco oven, and/or the inside bake ovens (IBOs) (and/or, in some cases, the basecoater oven) described above in connection with the known techniques to form cans. That is, all or selected functions described herein in connection with the above identified curing the inside coating, drying the cans, or curing ink or coatings on the outside of cans, or various combinations of these functions, may be implemented.
• the curing and drying times are decreased advantageously.
• applying the presently described embodiments to curing the inside of can coatings at a curing station may result in heating the cans to reach a critical temperature to produce a linking (or cross-linking) curing process in the coating in, for example, less than 20 seconds (or, as further examples, less than 10 seconds, or 5 seconds or 2 seconds).
• applying the presently described embodiments to curing of ink or coatings on the outsides of cans at a curing station may result in curing the ink or coating on each can in, for example, less than 20 seconds (or, as further examples, less than 15 seconds, or 10 seconds or 5 seconds).
• applying the presently described embodiments to drying cans, e.g. each can serially or each can or a group of cans among a mass of cans, at a drying station may result in drying the can(s) in, for example, less than 20 seconds. Performing each of these drying and/or curing functions in less than 20 seconds prevents de tempering, annealing or weakening from occurring in the can(s).
• the drying (after washing) function may be implemented to consume 60 seconds or less (or, as further examples, less than 50 seconds, 40 seconds, 30 seconds, or 20 seconds), wherein de-tempering, annealing or weakening of cans may still be prevented.
• one preferred implementation contemplates using, at an inside of can curing station(s), narrowband, semi-conductor produced infrared energy which is focused into the inside of the can to affect a very high-speed curing result. It contemplates using focused high powered, radiant energy that will directly impact the coating and the side walls of the inside of the can to rapidly transmit energy to both the coating material and the walls of the can which will then both reflect and re-radiate back into the coating material. This high powered radiant, narrowband energy will be introduced directly into each individual can and will bounce around at the speed of light inside the can until virtually all of its energy is absorbed into the coating and the aluminum substrate.
• a narrowband source is a preferred and likely most ideal solution.
• Broadband sources such as quartz lamps could be used but many of the advantages are not achieved and the implementation is not as beneficial. It is, however, possible to implement and practice the presently described embodiments with broadband sources.
• quartz lamps, high intensity discharge, or arc lamps could be utilized. They tend to have wavelength output bands that are a short enough wavelength range to be focused with normal glass optics.
• the various broadband sources would almost assuredly have to be on continuously because they cannot be switched off and on at the kinds of rates necessary for this application. While it can be done, it would also be expensive to equip such a system with the switching electronics to, for example, handle the 2,000 to 3,000 Watt quartz bulbs which would be needed for each curing station. Much care would need to be taken to ensure that the cans are heated to the temperature that is needed to accomplish the linking curing action but not so hot that it anneals the can’s aluminum body. Close monitoring of the can temperatures and the ability in the electronic controls to modulate the broadband device outputs would be extremely desirable.
• One of the fundamental advantages of this the presently described embodiments is to eliminate the weakening effect on the aluminum in order to facilitate using less weight of aluminum to manufacture a can of equal strength to the ones resulting from the conventional process that is almost universally used currently in the world can industry.
• One additional consideration with broadband sources is that they have an inherently shorter service life than the semi-conductor devices that are being used for narrowband sources. The life is shorter, for example, for a quartz lamp but it also continues to have less photonic output as it wears itself out.
• the electronics must be capable of modulating the power up to continuously account for the reduced output. Monitoring sensors can be employed just as they can with narrowband devices to provide feedback as to the can temperature and therefore the completeness of the curing.
• narrowband sources that could be implemented (e.g. in all embodiments described herein, for example, all embodiments described in connection with Figures 1-14) including high-powered lasers, various semiconductor-based irradiation devices, laser diodes, edge emitter laser diodes, VCSEL laser diodes, surface emitting laser diodes including SE-DFB laser diodes, laser arrays, and even light emitting diodes (LEDs) such as high-powered LED arrays. Multiple device arrays (e.g. more than 10 devices per array) could be used to produce output power (e.g. more than 100 watts).
• LEDs light emitting diodes
• Narrowband energy also facilitates better optical precision because the wavelengths are similar enough to focus nearly identically, which is not the case with broadband radiant sources.
• coatings on optics such as anti- reflective coating, can be optimized to be very efficient at the specific wavelength or narrow range of wavelengths being employed.
• laser diode arrays can be digitally switched, instantly on and instantly off, they will facilitate a nice variety of possible implementations of the presently described embodiments. They also can be configured so that they can be optically handled in a number of convenient ways to facilitate getting the right energy directed into the can to the exact areas where it is needed for effective implementation of the high speed curing.
• the present disclosure will teach a number of optical implementations and a number of can handling mechanical implementations which are possible examples, depending on the exact application and preferences of the implementer of the presently described embodiments.
• annealing of the can will be prevented. Shorter curing times (e.g. less than 10 seconds, less than 5 seconds, or less than 1 second) likewise result in an avoidance of annealing. If the annealing effect can be prevented, it will prevent the need to over strengthen the can to maintain enough remaining strength after the curing process. This can be a huge advantage to the can manufacturer because approximately 70% of the bill of materials and manufacturing cost of the average can is the cost of the aluminum material that is used to make the can.
• a narrower press bed also means greater machine rigidity and lower moving mass which results in longer press life and longer tool life.
• the cupper tooling which makes a smaller diameter cup will be cheaper initially and replacement tooling components will also be cheaper because there are smaller diameters involved and there is less tool steel involved.
• Another advantage is that the presently described embodiments use, for example, a digital, narrowband curing system which facilitates changing and precisely tuning the curing parameters to improve or optimize levels and the overall curing process.
• this tuning can be done dynamically to correspond perfectly to any chosen production speed and for improved or optimum energy savings.
• a closed loop process can also be developed which will verify the veracity of the curing and correct any under-curing or over-curing that may be occurring.
• the amount of curing energy can be optimized. This can be used to save further energy by not injecting more joules of energy into the can that would truly be needed for a proper cure.
• a further advantage is that the presently described embodiments facilitate, in some embodiments, putting an additive in the coating which will absorb more readily and more optimally at the chosen wavelength, thus paving the way for an even lower energy cure and potentially a higher throughput speed.
• the presently described embodiments have a further advantage of facilitating tremendous energy savings.
• Yet a further advantage is the elimination or near elimination of any hydrocarbons or fossil fuels in the curing process.
• a narrowband, high-speed inside of can curing technique described in connection with the presently described embodiments can be practiced in a number of different ways.
• the varying ways of practicing the presently described exemplary embodiments are primarily concerning two general areas. The first is how to arrange the system such that the cans are introduced to and taken away from the narrowband irradiation source, and the second is how the narrowband irradiation is generated and directed specifically into the areas where it is needed on the inside of the can.
• a two-piece beverage can with inside coating that will be cured typically comprises sections described hereafter as they are commonly known in the industry and as shown in Figure 1 . Although other shapes and configurations can be cured, such as cans with tapered walls, most two-piece cans are still of the configuration that will be detailed here for the education on practicing the presently described embodiments.
• a can (22) comprises a straight vertical wall (23) that extends from the moat (26) and heel area (25) to the top of the can.
• the very top of the un-necked, straight-walled can (22) is typically referred to as the trimmed edge or trim edge (21 ).
• the inside coating and subsequent curing operations typically occur on the straight-walled, un-necked can (22). It is necked and flanged in a later operation in the area near the trim edge in a necker/flanger machine operation.
• These various sections of the can (22) have been engineered and thoroughly tested to hold up under the pressure that is required for soft drink or beer containers, which pressure ranges generally in the range of from 90 to 110 PSI.
• the base metal (28) out of which the entire body of the can (22) is manufactured, is most typically manufactured from an aluminum alloy #3,004.
• This alloy has been chosen and standardized upon by most of the industry for its combination of strength, formability, and resilience for the can making process and application. To be sure, this alloy is more expensive than a straight aluminum material and anything that can be done to facilitate manufacturing a fully capable can from a lower alloy material will save money for the manufacturer.
• the exterior surface of the can (22) is typically coated or printed with layer(s) (29) of coatings or ink, as shown.
• the entire inside surface of the can (22) with current industry practices is coated with a layer, such as layer (27), of epoxy-based material which is baked on to properly cure it.
• the industry specifications for a properly cured coating are well known in practice within the industry and are part of the manufacturer’s specifications. It is, of course, completely unacceptable to have any areas on the inside of the can which have not been coated completely or properly cured.
• the can manufacturing industry is constantly concerned about making sure that the coating is all correctly cured and that there are no voided areas where uncured epoxy exists in the finished product. Coatings other than epoxy have been experimented with but have not been rolled out widely. If the other types of coating or partial coatings need heat or thermal curing, the presently described embodiments will be quite workable for those as well. The same is true for newer coatings which reduce or eliminate the BPA in the coatings which are thermally cured.
• the first challenge that is encountered by one practicing the presently described embodiments is how to generate the powerful narrowband irradiation.
• the designer’s first impulse is to try to configure something that can be inserted into the can which will irradiate in a multi directional, if not with a 360° pattern. While this is possible, most of the technology which is available to generate high powered, narrowband energy is considerably larger than that which can be inserted into the can through the un-necked top of a beverage can. It is certainly possible, as technology shrinks and narrowband energy devices produce more power, more efficiently and in a smaller package, that this will become more practical.
• a problem with an “inserted into the can” technique is that it involves many more moving parts and mechanisms.
• the insertion/retraction motion would have to occur between 200 - 400 strokes or insertions per minute, and that speed is likely to increase in the future.
• This assumes that the entire production flow through a can manufacturing line is divided into six to eight curing lanes, each running at the 200 to 400 cans per minute throughput rate.
• a typical production speed may be approximately 300 cans per minute or more.
• the concept of inserting and withdrawing an irradiation source from the can is a viable implementation technique, but will require more mechanism in order to insert and withdraw the irradiation sourcing arrangement at this rapid rate.
• the portion that can be inserted and withdrawn can be just the optics or some form of light guide to direct the narrowband irradiation which is produced outside the can into the proper locations on the inside of the can.
• This can take the form of the fiber optic light guide which is configured to gather the energy from one or more narrowband source or sources and deliver it into the can.
• the fiber optic light guide could be coupled to it in a location that would locate it safely away from the rigors, vibration, and contaminants of the actual curing station. It would be necessary to design the correct lensing or diffusing at the exit end of the fiber optic light guide to produce the output pattern that will adequately irradiate the coating on the inside of the can.
• the light guide could also take the form of a lensing configuration (see Figure 3) which is arranged to gather the narrowband energy near the sources (32) and then project it through a final objective lens configuration (38) and a mirror assembly (34) which is at the exact right focal length when the articulation mechanism (33) has it completely inserted into its irradiation position inside the can (22).
• the photonic energy (30) would be directed down a tube (35) to the output of the objective lens (38) inside the can (22) in combination, possibly with additional diffusers (37), could then directly irradiate the coating (27) on the inside of the can.
• Many different permutations of the lensing and the light guide type approach can be configured by one skilled in the art of high energy lensing and optical designs.
• the vertical insertion and withdrawal mechanism (33) would ideally have a containment reflection plate arrangement (36) to keep the photonic energy in the can by reflecting energy back into the can. It would also keep the arrangement safer by making sure the irradiation is all delivered into the can’s interior. All of the components and mechanisms would have to be designed such that they could handle the rigors of being moved at high speeds into and withdrawn from the can to meet the requirements of high-production manufacturing. This methodology may prove to be an excellent way of irradiating the inside of the can with an even irradiation pattern, but will require much in terms of articulating mechanism and engineering and, therefore, more cost to implement. It has the distinct advantage of providing a very direct way of projecting the narrowband irradiation to the coated surfaces for excellent results.
• an optical system may be incorporated into and/or used in conjunction with the irradiation system.
• a well-designed optical irradiation system in at least some embodiments, will be able to focus a relatively high percentage, for example, over 95% or over 90%, of the optical energy that emerges from the optical configuration directly and evenly into the interior of the can for curing purposes. Since the aluminum is highly reflective at these infrared wavelengths and since the can is cylindrical, much internal reflection is reliably predicted.
• the plane of the bottom of the narrowband irradiation assembly is located, for example, about .030” to .045” away from the top trimmed edge of the can (21), it is close enough to not have excessive energy losses through the gap, but it is close enough that sufficiently good transfer of energy will occur at the necessary angles to efficiently cure the coating by bouncing the energy around the inside of the can. It needs to be close enough that the cone or conical surface (64) is able to interface with the can’s interior geometry to return most of the energy that is reflected out the open top of the can, back into the can.
• the conical surface could be formed of a variety of different materials including copper, aluminum, gold plated metal, silver plated metal and/or highly reflective nano-structure material.
• a reflection cone (64), or whatever geometry is chosen should in most embodiments also provide, most optimally, for ventilation of the water vapor out of the can by positioning louvers accordingly.
• the louvers (74) must be shaped so they are reflectors facing the interior of the can but with spaces between the louvers to provide for vacuum air flow through vacuum port or vent tubes 75.
• the well designed airflow system should actually be both pushing air into the can as well as pulling vapor-laden air out of the can through the louvers (74) or venting holes in the reflection cone.
• a 90° included angle (69) is designed into the interior geometry of the cone (64), it will serve as an excellent multi-angle reflector to reflect or return the narrowband energy back into the can for further curing.
• the energy may, depending on the wavelength chosen, bounce around the inside of the can hundreds or even thousands of times until all of the energy has been absorbed into the coating (27) or the substrate aluminum (28).
• a primary purpose of the optical arrangement shown in Figure 2 is to inject photonic energy into the inside of the can (22) as shown.
• narrowband photonic radiant energy is generated in arrays (51) at the top of the diagram in Figure 2.
• the array or arrays (51 ) can have any number of laser diodes connect to an appropriate electric power supply.
• the designer of an array can use a combination of series and/or parallel connections of the laser diode devices to attain his desired current and voltage input preference to suit the system that he is designing. This will determine the current capacity and voltage required from the power supply. Choosing the right combination will allow optimization of the power supply specifications.
• the laser diodes can be of an edge emitter design or a surface emitting type of design.
• the surface emitting design has substantial robustness advantages because the effective aperture is much larger and therefore less susceptible to damage from contaminants.
• the traditional edge emitters are most often coupled to fiber optic light guides to provide for a better way of getting the narrowband energy to the optical train without exposing their rather fragile apertures to the difficult environment and contaminants that might cause catastrophic aperture failure.
• the additional cost and assembly complications related to the fiber optic coupling to the devices makes the traditional edge emitting laser diodes a viable solution for practicing the presently described embodiments but less desirable and much more costly than other solutions.
• surface emitting types of laser diodes often do not need to be fiber coupled. They can usually be configured to directly irradiate into an optical configuration which will guide the narrowband output into the can directly.
• the housing is configured to prevent stray infrared energy from escaping the housing, except through a pinhole element or a suitably sized aperture element (described below), although a variety of configurations of the housing could be implemented.
• the output of the laser diodes will either be diverging in two directions - a fast axis and a slow axis, or diverging in a single direction.
• the output is columnated in one direction, and has a slow divergence in the other.
• the slow axis would be considered the columnated direction and the fast axis would typically be diverging at 7-10°.
• a VCSEL is used as the narrowband, photonic energy generating device, it has a conical output pattern. Regardless of which type of laser diode is chosen, they must be packaged and configured in multiple device arrays so their total output power is sufficient.
• SE-DFB’s, VCEL’s, and any other surface emitting devices they can be packaged onto cooled circuit boards in an X by Y or some other pattern, but such that the energy is largely directed orthogonally to the mounting circuit board.
• arrays can certainly be of varying sizes to execute the presently described embodiments.
• arrays may be built and used for inside can curing which range in total output from 250 watts to over 500 watts.
• a 500 watt array could be comprised of 50 surface emitting laser diodes, each of which can produce 10 watts of optical narrowband near-infrared power. This may not be enough optical power to perform the inside coating curing in a specified time, so multiples of same array may be the designer’s best configuration.
• One assay showed that a single 300 watt laser diode array was able to properly cure an extra-thick layer of inside coating in under 10-15 seconds without careful attention paid to an optimized optical arrangement.
• optical configuration such as the example shown in Figure 2
• An example of a proper optical configuration could distribute the photonic energy exactly where it is needed for improved uniformity and a much faster cure.
• This optical configuration will ensure that less photonic energy is wasted and will effect a much faster curing time.
• the optical configuration in at least some embodiments, could be designed or tuned to deposit desired amounts of energy in desired locations on the inside of the can.
• an optical configuration could be implemented that deposits more energy at the top of the inside sidewall surface of the can and smooths out the decrease in energy down the sidewall of the can.
• Various optical elements for example, refractive, reflective, non linear, aspheric or other elements) could be used to accomplish these objectives and others to suit the needs of a particular configuration.
• optics or a microlens array (52) could be selected so that it creates columnated energy (54) directed in parallel with the central optical axis of the system.
• the output energy (57) will converge toward a focal point that is in the pinhole (65), then the light energy will cross in the pinhole (65) and become diverging rays (58) as it then is headed toward the coating on the inside of the can (22).
• the photonic energy will continue to process through the coating (27) and bounce off the walls (28) and back through the coating (27), as shown for example at (59), until it has imparted all of its energy to the coating and the can wall. Some of those bounces will also impact the reflection cone surface (64) and will then bounce back into the can and continue the process.
• the cone surface (64) should either be fabricated from or be coated with a highly reflective material. It may be copper, silver coated, gold coated or other such that it is as highly reflective of the particular wavelength of infrared that is being utilized as possible.
• the pinhole (65) & (71 ) is in a plate (62) which is designed to be replaceable to provide for easy maintenance to maintain a clean sharp pinhole area.
• the pinhole size (which could be, as but one example, 3mm) and sidewall shape should be the smallest that the optical configuration can accommodate such that virtually all the focused photonic energy passes through the hole without depositing energy on the pinhole plate (62), but not an unnecessarily large opening in the plate (62) and the cone (64). It should be appreciated, however, that a suitably sized aperture may be used as or in place of the pinhole (65).
• a pinhole such as pinhole (65) may well be implemented for systems according to the presently described embodiments that require more precise focusing of the irradiation into the inside of the can.
• any suitably sized aperture for example, apertures that have a diameter smaller than the opening of the top of the can, could be implemented to achieve desired results.
• such an aperture as but one example, could be smaller than 2 inches, or another dimension dependent on the size of the can.
• the reflection structure (64) which can be formed in whatever geometrical shape that serves the best to reflect energy back into the can, is also made so that it can be replaced for easy renewing and to provide a clean reflective surface. It can be quickly and easily replaced periodically when necessary, and should be designed such that it can be done with minimal tools.
• the angle of the reflective cone insert (64) should be carefully modeled so that reflects the maximum amount of energy back into the can, given the particular shape of the can’s geometry.
• the housing (55) should be made out of a material which can handle the scattered reflections of the infrared radiation that it will be containing. It preferably should be designed with cooling holes (61 ) throughout it so that water or a coolant can be circulated through the housing to keep it cool at all times.
• the laser diode arrays (51 ) should have some form of cooling as well. They can be cooled by a refrigerant circulation system through the actual arrays or it could be deionized water. In a most desired implementation, it could be plain water circulation through the arrays. If the devices are highly efficient, as may be the case in the future, gas or liquid coolant may not be needed and air cooling with heat sinks and fans may be adequate to keep the devices in a comfortable operating temperature range.
• the housing (55) may also have cooling facilities so that any of the components that are mounted there, including the optics and the laser diode arrays, are not seeing too much heat.
• the cooling for the housing (66) can either be a recirculating water jacket or could be a forced air-cooling arrangement.
• bottom surface (67) is, in at least one form, configured to control reflections of any escaping energy from the inside of the can (22).
• the surface (67) is provided with grooves, e.g. deep grooves, to provide such control over any escaping energy.
• the flush mating surfaces before and after the housing (55) should be engineered and assembled so that the incoming surface (73) is at the same level as the farthest reach of the bottom surface (67) of the housing (55).
• the outgoing surface (72) must also be at the same level or slightly higher than the farthest reach of the bottom surface (67) of the housing (55) so that a bump is not encountered by the trim edge surface of the top of the can (22).
• a broadband infrared irradiation source such as quartz lamps or high energy discharge lamps and the like. They are, however, more difficult to precisely focus the energy. They are not as energy efficient at producing the most efficient wavelengths to match the coating for best and fastest curing. They will inherently run much hotter because of the way they fundamentally produce their output energy. This will require much additional engineering to keep everything cool and to not completely overheat the cans. If the cans are overheated, they can be annealed or de-tempered even if it is for a brief period of time duration.
• broadband infrared sources will have less control over the heat imparted to the cans and there will be a requirement to modulate their output as a function of the throughput speed. But, while they cannot be turned on and off quickly and in a precise way like the semiconductor-based irradiation, this can be modulated with careful engineering.
• broadband electrical infrared components such as quartz lamps, high intensity discharge lamps, or arc lamps could be utilized. Again, instead of focusing the thermal photonic energy with refractive optics, one can use reflective optical configurations.
• a suitably engineered reflector arrangement a generally conically shaped reflector or an ellipsoidal, circularly symmetrical mirror can be used to focus the infrared energy on the inside of the upper sidewall of the can or container. That is the optimum area to have the energy hit the inside of the can because from there the internal reflections will distribute it from that preferred starting area.
• the configuration shown in Figure 3 (and also the configuration shown in Figure 2) could be suitably modified to implement a broadband embodiment wherein the radiation source is implemented with a broadband source and the optical elements are implemented using reflective, as opposed to refractive, elements and arranged to aim or direct the radiation at the upper sidewalls of the inner surface of the can.
• the system 200 for use in a can manufacturing inside coating and curing process wherein coating has been sprayed onto an inside surface of a can, includes comprises a can handling system 205 (not shown in detail) configured to serially move production cans into at least one curing zone.
• the system 200 includes broadband infrared sources, such as broadband infrared source 230 including quartz lamp 220, positioned to individually and electrically heat inside surfaces of each can 22 (shown in cross-section) moved into a curing zone using optical elements 240 positioned to direct irradiation (representatively shown at 260, for example) toward upper sidewalls of the inside surface of the can such that the coating on the inside surface of each successive can in a series of production cans is brought to a critical temperature to produce a linking curing process in the coating, in less than 20 seconds to prevent de tempering or annealing from occurring in the can.
• broadband infrared sources such as broadband infrared source 230 including quartz lamp 220
• the system is also provided with a control system 210 (connected using a link 250 - which could take a variety of forms and is only representatively shown) configured to use sensor information (not shown) to modulate output of the broadband infrared sources to maintain consistent curing temperature and results.
• a control system 210 configured to use sensor information (not shown) to modulate output of the broadband infrared sources to maintain consistent curing temperature and results.
• the optical elements may take the form, as describe by example above, of a suitably engineered reflector arrangement, a generally conically shaped reflector or an ellipsoidal, circularly symmetrical mirror used to focus the infrared energy on the inside of the upper sidewall of the can or container 22.
• such optical elements would be of a size at least slightly smaller than a diameter of the container or opening of the container, such as container 22, to allow for a suitable transmission of energy into the can and appropriate maintenance of that energy in the can for curing purposes.
• the precise digital control and precision energy control favors the semiconductor solution.
• the semiconductor-based irradiation configuration should have a much longer life and much more consistent output during that useful life. While broadband sources may have a useful life of several thousand hours, their output will drop continually during that time, so it must be modulated carefully to ensure a consistent curing result. They will not all wear at the same rate, so it will be an engineering challenge as well as a chronic maintenance problem to make sure that the irradiant output of each lamp is adequate to ensure proper curing.
• Figures 4 and 5 the implementations of the presently described embodiments also should, in most forms, address preferred configurations for the mechanical can handling. These configurations can come in at least four different forms. Also, it should be appreciated that descriptions of Figures 4 and 5 include references to examples of narrowband sources of irradiation; however, broadband infrared sources and corresponding systems could also be employed in these embodiments with suitable modifications, where necessary.
• cans are individually and electrically heated using, for example, narrowband semiconductor-produced radiant infrared energy (produced by, for example, arrays of semiconductor-based narrowband irradiation devices) and optical elements positioned outside of the cans in the at least one curing station such that the coating on the inside surface of each successive can in a series of single-filed production cans is brought to a critical temperature to accomplish a linking curing process in the coating in less than 20 seconds to prevent de-tempering or annealing from occurring in the can.
• narrowband semiconductor-produced radiant infrared energy produced by, for example, arrays of semiconductor-based narrowband irradiation devices
• optical elements positioned outside of the cans in the at least one curing station such that the coating on the inside surface of each successive can in a series of single-filed production cans is brought to a critical temperature to accomplish a linking curing process in the coating in less than 20 seconds to prevent de-tempering or annealing from occurring in the can.
• example embodiments include an ingoing trackwork or conveyor configured to organize or facilitate movement of individual containers into single-file order toward a second conveyor, the second conveyor being configured as a rotary turret to move the individual containers into and away from at least one curing station, the at least one curing station comprising an optical configuration wherein photonic energy from at least one array of surface emitting laser diodes passes through columnating optics and then is focused by at least one condensing lens element through a pinhole or aperture where beyond the photonic energy diverges to irradiate inside sidewalls of a coated container, such pinhole or aperture being located at the vertex of a reflective cone, such reflective cone functioning to reflect photonic energy back into the container to effect further curing work, wherein the coating is cured in less than 20 seconds
• example embodiments include an ingoing trackwork or conveyor configured to organize or facilitate movement of individual containers into single-file order toward a second conveyor, the second conveyor being configured as a rotary turret to move the individual containers into and away from at least one curing station, the at least one curing station comprising an optical configuration wherein photonic energy from at least one array of surface emitting laser diodes passes through columnating optics and then is focused by at least one condensing lens element through a pinhole or aperture where beyond the photonic energy diverges to irradiate inside sidewalls of a coated container, such pinhole or aperture being located at the vertex of a reflective cone, such reflective cone functioning to reflect photonic energy back into the container to effect further curing work, wherein the coating is cured in less than 20 seconds, thus being fast enough to prevent weakening or annealing from taking place in aluminum comprising the container, and the second conveyor delivering the containers and being guided off to a third conveyor configured to bring the container out and away from the second conveyor so empty pockets are available to load
• one example configuration which will be outlined in connection with Figure 5 is a configuration involving continuous rotary motion.
• the narrowband irradiation sources and, possibly, controllers
• optics e.g. heat exchanges, chillers, and/or recirculation pumps
• power supplies e.g. DC power supply
• a rotary union would be designed into the system to provide for the delivery of whatever electrical power, control signals, compressed air, vacuum, and/or cooling that is needed on the continuously rotating turntable or turret.
• the narrowband irradiation arrays or sources can continuously irradiate the inside of the can through their optical configurations for the time period necessary to impart enough joules of energy to do the full curing.
• the entire irradiation system would rotate right along with the cans in synchronous motion.
• the irradiant energy would turn on when the can rotates through the starting irradiation station and then would turn off prior to the can exiting the starwheel.
• the particular narrowband irradiation system is capable of producing 500 joules, and for correct curing a particular can requires 850 joules, then the irradiation must be turned on during 1 .7 second portion of the arc of the starwheel.
• the start time and duration of on-time can be fixed or more ideally, a programmable parameter.
• the intensity or pulse width modulated on-time (duty cycle) should be programmable in at least some forms.
• the user interface can be configured to meet the needs of the end customer. It can be as simple as screen entries on the display of a programmable controller or as complex as a PC-driven user interface with user friendly graphics showing on/off timing, duration, and intensity. It could also facilitate the programmability or the graphical setting of the intensity curve as a function of time or turntable position.
• the system’s controller could also communicate with portable devices, whether tablets, smart phones, smart watches, or other to make it very convenient to monitor the settings, speed and functioning of the curing systems.
• the starwheel’s diameter and RPM must be configured so that an adequate period of dwell is provided for the irradiation to execute proper curing. This configuration of the presently described embodiments will be described in greater detail below.
• a downstream inspection system could inspect the outgoing cans (89) to make sure that the coating has covered the entire inside of the can and to make sure that it is fully and properly cured.
• This inspection system could utilize either a visible light grey scale or color camera or it could use an infrared camera on the way out of the curing system, or it could use both types. The inspection system could ultimately try to determine if there was any bare, uncoated metal or uncured coating.
• the inspection system (97) could close the loop and gradually turn up the joules of energy that are being applied to the various cans from the respective stations to make sure that they are correctly cured.
• the system would be able to correlate that it would know which can was cured by which curing system (91 ). To the extent that the cans from an individual curing station were under-cured, the system would be able to correct and increase the curing energy from any particular curing station.
• a similar process correction by way of closing the loop from an inspection station back to the specific curing station could be accomplished on any of the configurations in which the presently described embodiments could be practiced.
• the system in Figure 5 would function as follows.
• the sprayed but uncured cans (82) would arrive by way of a conveyor, trackwork or similar mechanism or system configured to organize or facilitate movement of individual containers into single-file order toward, for example, another conveyor or device.
• a conveyor could be in any form of conveyor including a vacuum conveyor or it could mean trackwork to simply guide the cans while air or gravity pushes them along.
• What is shown schematically is a vacuum belted type conveyor (80) which also has guiding trackwork (81 ) along both sides of the row of cans. The row of cans (82) is pushed along such that a slight pressure is exerted on the hold out plate (87) as the next can for loading sits on the dead plate (96).
• the can continues to press against the holdout plate (87) until the next empty pocket (86) arrives and the can is able to be pushed into the pocket.
• the can can be assisted by vacuum which is pulled from the back section of the nest hold out plate (87), the portion which is closest to the center of the turntable.
• the shape of the holdout / nest plate must be carefully derived so that the can slips in smoothly when the pocket has opened-up and is available and so that it does not dent or deform the can. It must also create a consistent location for the can and hold it securely and in a consistent position during the time that it is being cured.
• the turntable (84) As the turntable (84) continues to rotate, it will transport the can in the nest position (86) and once it has cleared the loading station, a signal will be given to turn on the irradiation energy.
• the control system will turn on the energy at a rate which the irradiation devices can handle without a deleterious effect but not so slowly that time is wasted which could be viably used for curing.
• the arrays of irradiation devices (85) are actuated, they are powered by the control system and power supply (95) which correspond to each irradiation station.
• the can should be situated centrally under the irradiation optics (91 ) the entire time that they are rotated by the turntable.
• the optics (91 ), the arrays (85), and the power supplies and control system (95) are rotated with the turntable (84) and maintain their relative position to one another during the entire rotation process.
• An encoder (93) is continually feeding back the rotary position and speed information to the central control system (99) by way of cabling (98).
• the central control system (99) is feeding back the relevant information that each station needs to have to the local control (95) that it needs in order to properly actuate each of the irradiation stations (91 ) with their appropriate timing and power levels.
• Each of the control systems (95) will monitor the cooling for each of their respective stations and will feed that back by way of the interconnect (98) to the central control (99) in order to facilitate full supervisory control over all stations.
• the cured cans (89) As the cured cans (89) approach the unloading station, they will gradually come into contact with the stripper arm (90) which will gradually and gently push them out of the station on to the already moving vacuum conveyor belt (88). The cured cans (89) will continue to proceed down the vacuum conveyor (88) and will pass under the inspection station (97) on their path out of the curing system.
• a trackwork system which takes advantage of gravity or high volume, low pressure air to move them along to exit the curing system.
• Another viable configuration for the presently described embodiments are somewhat similar in that it employs continuous rotary or linear motion, but it uses fixed position irradiation systems that strobe to impart the energy when the can is passing by the correct location.
• This configuration would require a very powerful and very short pulse of irradiation energy which must be timed correctly.
• the duration of such a high-speed strobe pulse would vary with the exact implementation details and throughput speeds of the material handling but would most likely require a pulse of less than 500 milliseconds, but could be as short as 300 microseconds, for some higher speed applications. It is possible to over pulse arrays of narrowband infrared semiconductors to get very high outputs for very short periods of time.
• the concept here is that if perhaps the normal electrical supply current rating on an array is x, that for a very short duration of time perhaps 10, 15, or 20x is possible to get a much higher peak output. If, for example if 1700 joules is required for correct irradiation, the group of irradiation arrays can normally put out 1700 joules in 1.7 seconds with a current input of 15 amps, could be strobed at ten times their normal current, which in this case would be 150 amps, to produce the 1700 joules in 170 milliseconds.
• the strobed and over-pulsed configuration can be executed in either a rotary motion configured system or in a continuous linear motion configured system. Either arrangement will facilitate allowing the cans to pass single file under a strobed narrowband irradiation array for the curing exposure.
• the implementer of the presently described embodiments will be constantly debating the relative merits of material handling throughput speed versus the power and configuration of the irradiation system.
• a more powerful irradiation system will ostensibly irradiate in a shorter period of time directly proportionate to the power it incorporates.
• a 2,000- watt array will irradiate roughly twice as fast as a 1 ,000 watt array, but more material handling equipment that runs at a slower speed will be required for the 1 ,000 watt array because the system must be designed with more serial or parallel mechanism to attain a particular throughput speed.
• a material handling system can process twice as many cans in a given period of time if it runs at the doubled speed.
• a material handling system can process twice as many cans in a given period of time if it runs at the doubled speed.
• the power output in the narrowband irradiation arrays and larger power supplies and so on In order to cure at the doubled speed, one needs roughly twice the power output in the narrowband irradiation arrays and larger power supplies and so on.
• Higher powered irradiation systems generally require that much more cooling and everything in the system, including the optical train, must be capable of handling the much higher power levels.
• high speed material handling equipment brings its own challenges. Since the kinetic energy in a moving item increases by the square of its velocity, a material handling system that runs at twice the speed must deal with four times the inertial or kinetic energy throughout the system including in the cans that are being handled.
• a typical can line divides the production flow into seven lanes currently to do the inside of can coating. One of those lanes is assumed to be available for maintenance at any time while the other six run continuous production. According to the presently described embodiments, each curing lane could, for example, cure individual cans at production speeds of 300 cans per minute (which translates to 1800 cans per minute for six lanes). The full output of those six active lanes is then brought back together into mass conveying before it passes through the IBO.
• the lanes would proceed on through the corresponding curing lanes while still separated.
• independent lanes they may be started and stopped independently. They maintain the independence for control, servicing, and speed optimization.
• This configuration of independent curing lanes allows for any lane to be started or stopped for any reason without shutting down plant or whole line production. It facilitates both scheduled maintenance while production is maintained as well as spontaneous maintenance or jam clearing without shutting down production. If any electronic troubleshooting or component replacement is needed, it can be done seamlessly while normal production proceeds.
• the separate lanes of curing could then be merged into one high speed, single file lane again for the trip through the next production step, which typically is the necker flanger.
• FIG. 1 Another arrangement that could be implemented according to the presently described embodiments incorporates high speed, indexed rotary motion.
• This configuration will involve a turntable or starwheel arrangement which incorporates a rotary index configuration which will move a specified arc of movement repetitively.
• the indexing technology can be one of a number of mechanical or electromechanical considerations.
• the periodic indexing can be one of a number of technologies including electric servo, cam, ratcheting or clutch mechanical, pneumatic, or any number of other indexing mechanisms. Although they are employed in a unique way here, all of these mechanical mechanisms are well detailed in the literature and the patent database and will not be explained in detail here. Commercially available products can fill this need very well for the basic mechanism but then they must be tooled very specifically and accordingly to handle cans through the high-speed irradiation curing stations.
• the properly indexed starwheel or turntable facilitates moving the can under the irradiation source and will provide a dwell during which the irradiation source can be turned on and then ultimately turned off prior to indexing the can out from under the narrowband irradiation source and bringing a new can in to position to allow irradiation for it.
• This repetitive indexing cycle has the advantage of providing whatever length of dwell duration is required for the application. It must provide whatever number of joules of energy are required for a proper curing, but the speed and throughput will demand that certain radiant power be matched with the right speed of indexer to meet the overall production demands for the system.
• the indexing arrangement can provide for moving single cans into and away from the narrowband irradiation source. Alternatively, with each index it could move multiple cans into position under multiple irradiation sources. It is, therefore, possible to design the system so that it is optimized by having the perfect number of irradiation sources to deal with the curing duties while the indexing turntable can be run at a speed which is within the range of high reliability for its mechanisms.
• the coating may be a viable configuration, however, if it is necessary to keep the coating at the elevated temperature for a more extended duration to suit a particular kind of coating. It will also facilitate multiple repeated irradiations if a longer period of irradiation is required than can be facilitated by the mechanism otherwise. This could also facilitate a higher throughput speed if configured carefully. In some cases the longer effective duration time may be required to drive off the water or for other curing reasons.
• any of the rotary motion configurations of the presently described embodiments can utilize gravity to assist the movement of the cans through their various respective track work.
• the cans can be basically touch one another as they move through the track work either on the path to or from the narrowband, high speed radiant curing stations.
• a steep incline or vertical track work full of cans is very helpful.
• the track work (81) whether backed by a vacuum conveyor (80) or not, can be configured so that it is either vertical or at a steep angle so that the cans (82) push each other along.
• the gentle push of gravity which force can be increased or decreased by increasing the vertically or the stack length before the transport nest (86) with the help of the peel-off guide (87) gently guides the next can into the transport nest (86).
• FIG. 4 Another way of implementing the presently described embodiments is by way of a linear escapement configuration as shown, for example, in Figure 4.
• Programmable escapement pushers are arranged along the input conveyor which are configured to provide properly timed push off into the escapement tracks between the two conveyors.
• the narrowband irradiation system is provided above the work station on each escapement track at an escapement work station so that when the can is pushed off and made to dwell in the work station, the irradiation can proceed as long as necessary for proper curing.
• the can is pushed out of the work station and to the exit conveyor with proper timing so that it fits into a gap between other cans that are already in process on the high-speed exit conveyor.
• This type of arrangement allows a lot of parallelism for long dwell times but with high programmability. It can typically be implemented at a lower cost point and may provide for higher flexibility and more modularity than most of the other configurations. It does, however, require more sensing, more programming, and more articulation of the cans.
• the linear escapement configuration in Figure 4 will be explained in greater detail here.
• the linear escapement configuration would work as follows. Referring to Figure 4, the incoming conveyor (111) brings a row of single file upright cans. The open top is facing away from the vacuum conveyor on which it is transported. The input speed of the conveyor (111 ) will depend on the throughput speed and handling speed of the entire balance of the system. The actual speed and belt position is constantly being monitored by an encoder (109) which is directly linked to the drive of the conveyor (118) and (119). The encoder is connected to the computer, the control system, or the programmable controller which constantly logs the position of the belt and by way of the input from a photo cell (100) is monitoring the position of every can that enters the material handling system.
• the control system determines which irradiation station is going to be available for the can to enter. Seven fully independent irradiation curing stations (106) are shown in Figure 4. If the programmable controller determines that it will send the can to station three, it will alert the station three diverter (114) to extend its fingers with very precise timing to provide the necessary vectoral force to angle the can off into the irradiation station number three. There will be a pushing sliding motion created by the combination of the kinetic action provided by the moving belt as the can comes against the fingers of the diverter (114) as it approaches station three.
• the can As the can is pushed off onto the station three sidetrack conveyor, it will first slide over a dead plate (113) before it is picked up by a station diverter conveyor (105).
• the diverter conveyor will continue to transport the non-cured can into its respective curing station (106) until the center point (110) is over the center point of the uncured can under the curing station (106).
• the diverter (105) will continue to transfer the can into the curing station (106) until the photo cell (120) verifies its arrival. At that instant, the diverter conveyor (105) will stop moving the conveyor and the irradiation station (106) will be activated and will irradiate the inside of the can.
• the electro-optical system may be very similar to the one shown in Figure 2.
• the narrowband curing system (106) When the on time indicates that the correct number of joules of energy have been imparted to the inside of the can, the narrowband curing system (106) will be turned off and the control system will know that the now cured can is ready for its exit.
• the control system which will have been tracking the position of all cans in the system, will know how long it will take for the diversion conveyor to transport the can out to the exit conveyor (108).
• the timing is right and a gap between the cans (107) as is shown in Figure 4, it will prepare to re activate the diverter conveyor to transport the cured can into the proper gap between cans that are traveling down the exit conveyor (108).
• the diverter conveyors (105) can be equipped with perforated belts through which a vacuum is pulled so that the cans adhere tightly and so they can be accelerated quickly.
• the exit conveyor (108) also can be equipped with vacuum holes (104) through which a vacuum can be pulled to hold the cans down tightly on the belt for good acceleration and control.
• the entrance conveyor (111 ) will be driven by motor (119) and gear drive (118) and the exit conveyor (108) will be similarly driven by the motor (101 ) and gear drive (102) and both of those can be variable speed motors which can be adjusted by the control system for the smoothest can mesh according to the production speeds that are being supported.
• the diverters (114) must be designed so that the fingers are fast enough to divert the cans but they must do it smoothly so that the cans are not tipped over or deformed. But the fingers also must retract fast enough to get out of the way before the oncoming next can comes along.
• the control system must know the reaction time to extend fingers and to retract fingers and must be able to coordinate the timing of all the can transportation, diverting, and then exiting the system on conveyor (108).
• controllers or control systems may take a variety of forms, depending on the specific implementations, but will, in at least one form, be implemented with suitable hardware configurations and/or software routines to realize the form and function of the presently described embodiments.
• controllers or control systems in at least one form, include at least one processor and at least one memory having stored thereon code or instructions that, when executed, cause the processors or other components of the system(s) to act or function in a particular manner.
• the memories may take a variety of forms including non-transitory, computer-readable media or devices such as read-only memory (ROM), random access memory (RAM), or other memory structures.
• controllers or control systems may be, for example, stand alone systems, distributed systems or incorporated in another or a more comprehensive system.
• the different form factors through which the presently described embodiments can be executed which are detailed above are primarily to facilitate the direct narrowband irradiation portions of the curing. Depending on various factors, it may be necessary to augment the above configurations for complete curing.
• One form of augmentation may involve having a pre-warming section through which the cans pass immediately prior to the narrowband irradiation section. This can facilitate pre-warming the can so that less joules of energy are required from the narrowband irradiation section.
• Another form of augmentation may involve a post-blowing section after the narrowband irradiation. Since a great portion of the wet coating is liquid water, it is necessary to drive off the moisture at some point in the curing process.
• the pre-warming section can either be warm air or it could be radiant and be equipped with for example, quartz lamp banks to provide a gentle radiant preheating.
• the augmentation sections can vary widely and will depend on the exact circumstances, plant configuration, and geographical climate into which a system is to be installed. One skilled in the art will understand that not only can the narrowband curing system be configured in many different ways beyond the specific examples which are taught here, but the augmentation, both before and after it, can take many forms as well.
• Convection heating is generally an inefficient heat transfer process. It is a multi-stage process and inherently has lossiness between each stage.
• the air must be heated initially and then the air must be in contact with a can to transfer its heat into the can and its coating.
• a similar amount of hot air hits the outside of the can as that which hits the inside of the can.
• the hot air that hits the inside of the can hits the coating first before it conductively soaks through to heat the metal.
• the hot air which hits the outside of the can must heat the metal and then the metal must heat the coating. In a perfect world, it is much more desirable to just heat the coating to its cross- linking, curing temperature.
• the coating is in intimate contact with the aluminum substrate that comprises the body of the can and because it is very thin, it will transmit the heat directly into the metal substrate. Because of this method of heating, the metal substrate is heated as much as the coating. Also, the hot air in the oven is not completely uniform. Hot spots inherently exist in the oven and the air movement varies from place to place, so it will have a tendency to overheat some cans and under-heat others. The cure for this tendency is to use more oven heat than is truly optimal to prevent uncured cans.
• the 3004 alloy aluminum which is also known as UNS A93004 has the following chemical composition in addition to the base aluminum. It has silicone at 0.3% max, iron at 0.7 maximum percentage, copper at 0.25 max, manganese at between 1 % and 1 .5%, magnesium between 0.8 and 1 .3%, zinc at 0.25% max and then other elements which are less than or equal to .05% each up to 0.15% total.
• Standard tempers available include 0 (annealed), H32, H34, H36, and H38. The H indicates strain hardened and there is an H3X which is strain hardened and stabilized.
• the specific temper typically used for aluminum beverage cans is an H19 number which is less strain hardened than H32 but is harder than the annealed condition.
• the H19 temper seems ideal to handle the significant cold working that occurs during the D&l (Drawn & Ironed) process.
• the specifications regarding tensile strength vary from 26 KPSI to 41 KPSI.
• the yield strength varies from 10 KPSI at the 0 temper or annealed product up to 36 KPSI for an H38 temper.
• the reduction of the can’s strength by eight to ten percent is truly a reduction in the buckle strength or bottom reversal strength that a can is able to sustain under pressure.
• the buckle strength is not directly correlated to yield or tensile strength because the exact geometry and the thickness of the can’s shape are significant factors in the strength of the can. But, since these are as identical as can be measured both before and after curing, it clearly is the change in tensile strength and yield strength which are responsible for the loss of buckle or bottom reversal strength. This annealing/de-tempering effect is clearly a factor that has to be dealt with accordingly in the can manufacturing industry.
• the presently described embodiments can virtually eliminate this annealing/de-tempering effect that occurs in the IBO.
• the presently described embodiments eliminate the IBO and substitutes a high speed, narrowband infrared radiant curing technology in its place.
• the cans are single filed, and irradiation is directed individually into each can. They are cured one at a time serially instead of in mass as a group. Due to the controllability and relative efficiency of the narrowband irradiant heating, the coating can be brought up to the full curing and cross-linking temperature in only a few seconds. Since the can spends so little time at the elevated temperature, the weakening effect does not have time to occur.
• the details and techniques for implementing this high speed, radiant curing technology are taught in more detail throughout this document.
• a penetration depth can be calculated for the spray coating sample.
• a low penetration is actually advantageous as it corresponds to faster absorption of the IR radiation.
• the infrared light will be slightly absorbed on its first pass through the spray coating, but will then reflect off of the aluminum substrate under the coating and then pass back through the coating as it starts the process of reflecting around the inside of the can. It will contact spray coating and aluminum walls with each reflection pass. Even the small amount of energy absorbed by the aluminum during the slightly imperfect reflections will benefit the curing process as it will result in heat energy on the aluminum surface holding the spray compound, thus heating the compound further. Also, it should be appreciated that if the aluminum heats up sufficiently, the external decoration on the can may also be cured. This might be desirable for some implementations so the system could be designed, configured or tuned to accommodate such heating and curing objectives.
• each reflection inside the can will result in 0.00508 mm of travel through the spray coating because of the double coating pass with each reflection.
• 774 passes through the body of the can will be required before 3.93 mm of spray coating have been interacted with.
• the results of a timing calculation for both the thinnest and thickest coating thickness are: 0.17 nanoseconds for 0.1 mil thickness, and 0.03 nanoseconds for 0.5 mil thickness. As the results show, it will actually require significantly more time to emit the energy from the laser diode than it will for it to be absorbed by the coating.
• the current traditional method for can coating curing utilizes a large oven with a mass conveyor. Three successive sections heat the cans. The oven is fed by natural gas in which the temperature in the final section is maintained between 375 to 450 degrees F. The cans are passed through this hottest section of the oven for curing times on the order of one (1) minute through the use of a mass conveyor belt. Because of the high cost associated with initial oven heat-up procedures, these ovens are left on as much as possible, which is wasteful both during line down time or during a jam which can back up prior to or in the oven.
• TABLE 1 shows the cost buildup, based on reasonable assumptions and current natural gas costs in the United States. As TABLE 1 shows, a rather substantial amount of heat must be continuously supplied in order to keep the oven interior at a consistently high temperature. The cost of natural gas is also a key component of the total yearly cost of operation.
• the oven will actually remain at temperature 95% of the available time during the year.
• the narrowband radiant heating elements are designed to be pulsed and would therefore only use electrical power when a can is present and actually being cured. Not only does this allow for greater efficiency during operation, but when the line is down for maintenance or a line jam, the diodes are not in operation. The result is a diode array uptime on par with the actual line uptime.
• cans have weighed approximately .34 to .39 ounces but it will be appreciated that can weight/mass may vary as a function of, for example, exact geometry and material thickness. Also, can manufacturers periodically redesign cans, can tooling and manufacturing processes to vary weight/mass (e.g. make cans weigh less). Further, some cans, e.g. specialty cans, might even be designed to have increased weight/mass. Skillful implementation may yield as much as 9 to 14 percent savings in aluminum used. However, any reduction in amount of aluminum, such as reducing the weight of aluminum by 3%, 5%, 8% or greater, would be beneficial. Since roughly 70% of the cost of a beverage can is the cost of the aluminum material, that represents a huge savings to the can manufacturer or the can user. It also is an environmental gain in other ways since less aluminum needs to be mined, refined, manufactured, and transported.
• the elimination of the weakening effect through the oven will be beneficial in one of three ways or a combination of ways.
• the can could be made with the current aluminum and tooling, but would simply be substantially stronger than the current can because of the elimination of the weakening of the aluminum.
• less aluminum is required to manufacture the can.
• the third possibility is that a cheaper, lower alloyed, or lower tempered aluminum may be used in place of the current higher priced aluminum product. It can be a combination of these, depending on how the manufacturer chooses to implement the presently described embodiments of this technology.
• a more novel way of implementing the presently described embodiments would be to reduce the cut edge diameter of the blank and thus the diameter of the resulting cup.
• the starting cup for a typical 12-ounce two-piece can is 5.100” diameter. This technique would reduce the weight by proportionally reducing the cup size but keep the same coil sheet thickness and thus the same rolling premium.
• the first step in the D&l process is to deep draw a “starting cup”. Again, this would mean that the aluminum coil would have less width but the same thickness as it currently does, so it should fall into industry standard pricing and simply be slit to a narrower width.
• the can body end product will end up at the desired thinner specification in the finished can, but without a premium paid for rolling the aluminum to a thinner gauge specification.
• the tooling components will be smaller in diameter and will therefore require less tool steel and less machining, so they should be comparatively cheaper than the current larger versions.
• the modification to the cupper press tooling will be required in order to make the smaller diameter cup, the payback for making that change can be quite substantial.
• the balance of the cupper press, feeding equipment and overall system should be reconfigurable to use the new tooling or tooling modification.
• the reason the billiard ball eventually slows down and stops is because it has lost all of its energy to the bumpers and a smaller amount to rolling friction.
• Broadband sources because of their inherent properties, may not facilitate the super-fast cure and thus may still induce some or all of the annealing effect by rapidly overheating the can.
• narrowband irradiation and to semiconductor-based production of the narrowband energy.
• the coating can be designed and optimized for the exact narrow wavelength band that is being employed. It does not need to be the less optimal, broadband anti-reflective coating.
• the optics and optical coatings such as cold mirror coatings, can be more easily designed for a narrow specific wavelength range. Lenses focus at different distances for different wavelengths, so more precision can be an advantage when designing the optical train for a narrowband system.
• narrowband can be interpreted differently but we are referring to the production of optical or photonic energy whose full width, half max bandwidth is typically less than 100 nanometers. If the source of the narrowband energy is a solid state or a semi-conductor source, this will normally be the case unless a broadband fluorescence is added to the device configuration.
• the raw output from LED’s is generally narrowband inherently within that range but laser diodes are narrower, for example, less than 20 nanometers (nm), usually less than ⁇ 10 nanometers (full width/half max) or even as narrow as ⁇ 1 nm (full width/half max) for certain types.
• VCELS and SE- DFB devices for example, are usually less than ⁇ 2 nm (full width/half max) in bandwidth. The exact bandwidth is not as important as the central wavelength of the output.
• the wavelength can determine how quickly the energy is absorbed by the coating itself.
• the transmissivity of the coating can be measured at varying wavelengths and a wavelength that achieves the best absorption results can be chosen.
• the narrowband infrared energy used for curing (which, as detailed above, could be as narrow as ⁇ 1 nm (full width/half max), depending on the implementation), will match at least one absorption characteristic of the coating.
• the narrowband wavelength may fall in the range of 800-1200 nm, for example, at approximately 972 nm.
• 972 nm represents a deep penetration wavelength for a water- based epoxy coating, as discussed herein.
• Substantially faster absorption by the coating is possible in a range of 1400 nm to 1600 nm, for example, at about 1 ,454 nm or 1456 nm, but the wall plug efficiency is not as high, so the tradeoff is a decision that the system designer must make. Similar wall plug efficiency challenges exist in the range of 1850 nm to 2000 nm, for example, at 1935 nm.
• the narrowband irradiation aspects of the systems should have very strict attention paid to the safety aspects of the systems.
• the powerful infrared energy that is so effective at rapidly curing the coating is very dangerous to the naked eye. It’s invisible and is powerful enough to quickly blind a person or animal before he or she can blink. Even sunglasses, or welding glasses, because they have weak filters and may filter the wrong wavelengths, are not adequate to stop the powerful photonic energy from damaging the eye.
• Some of the longer infrared wavelengths that could be used for the reduction to practice are not able to penetrate to the retina of the eye, but can still damage the cornea, sclera, iris and/or lens of the eye.
• narrowband infrared energy of this curing system it is also possible to incorporate using the narrowband infrared energy of this curing system to further optimize the coating that is used.
• the manufacturer of the coating could employ IR actuated chemical reaction actuators or accelerators that are appropriate for the inside can coating purposes.
• functional dyes are available which can absorb in specific narrowband infrared wavelength bands. Such dyes are made, for example, by Yamada Chemical Co.
• the narrowband IR irradiation can be used by chemical coating manufacturers in creative ways to improve their coatings, reduce or eliminate the BPA based coatings, or improve the performance in various ways. Some of the reflections inside the can would inherently direct energy out through the open top of the can.
• a properly designed system will place reflective surfaces appropriately to, at least partially, direct any exiting energy back into the can to perform further curing until it is spent.
• the most reflective surfaces give up a few percent of the impacting energy into the reflective material. They are often called Fresnel reflections. Also, some of the energy may be scattered or reflected incorrectly and may never get back into the can.
• a properly designed reflective shape or cone (64) can provide for better placement of the returned energy so that more of it will be absorbed in the additional passes through the coating and reflections off the base material.
• both the drying oven for example, a drying station
• the pin chain oven for example, an outer can surface curing station
• both the drying oven for example, a drying station
• the pin chain oven for example, an outer can surface curing station
• both the drying oven can be accomplished with major advantages by likewise using precisely directed and controlled narrowband heating technology.
• each of these stations performing their drying or curing functions in less than 20 seconds, de-tempering, annealing or weakening are prevented from occurring in the can(s).
• the respective ovens would be designed and configured very differently but they would have in common that they use narrowband infrared radiant technology. Because the narrowband infrared technology uses electricity to provide the fundamental energy to ultimately create the infrared energy, it can completely eliminate hydrocarbon use in the ovens. If the entire plant does so with the three main “heat Process” functions of drying, ink curing, and inside coating curing, the entire plant can be without any hydrocarbon fuel-based heat or oven processes.
• the drying oven comes just after the washing process in the sequence of can production as shown in Figure 6 and would still take the form of a mass conveying system. It would employ an open mesh conveyor belt or an open hinged slat arrangement so that radiant infrared energy can be projected from below and up into the cans through their open end, which is facing down. Ideally, the largest possible mesh cross section, providing for maximum open space through which the infrared energy can pass, would create the most efficient design.
• the width and the speed of the mass conveyor will be sized according to the plant speed and throughput desires. They typically are from 20 to 40 can diameters wide, but can vary beyond that. But it could easily be configured whatever width is desirable and optimal for the can manufacturing plant’s throughput and production speed requirements.
• the narrowband radiant infrared energy is aimed or projected up through the mesh or perforate belt into the open top of the inverted can.
• the energy begins bouncing around the inside of the can and imparts energy to the can with each bounce. If the photonic energy encounters water on its way to the interior walls of the can, it will pass through the water thus imparting another quanta of energy which will depend on the thickness of the encountered water. This interplay continues until enough photonic energy has been absorbed by the combination of the water and the aluminum to heat the water to an evaporation temperature. Increased evaporation occurs at quite modest temperatures but is accelerated at higher and higher temperatures.
• the air movement can be provided by fans and blowers configured to introduce fresh, drier air into the cans to allow the heavier vapor-laden air to come out and be ducted away.
• the aluminum however, has an absorption at around 1000 nanometers that is greater than at longer wavelengths, so there may be an optimization tradeoff to be considered. Therefor it is necessary for the application engineer to determine if the extra absorptivity is worth the reduced power and reduced wall plug efficiency that is typical of the longer wavelength devices.
• the pin chain oven or outer can surface curing station, requires a completely different deployment of narrowband technology.
• the pin chain oven s purpose is to cure the ink that has just been printed on to the outside perimeter of the can. The reality is, it does not completely cure the ink in this oven but during its short exposure in the pin chain oven, it cures it sufficiently that it will not rub, smear, or spoil the printing until further curing occurs in the IBO.
• corner cube reflection sheets which can vary in configuration but, as an example, will be configured to have a plurality (e.g. tens, or hundreds or thousands) of suitably sized corner cub reflectors to achieve the desired results depending on the implementation.
• Various applications and use of such sheets and related technologies are fully described in US Patent Application No. 13/102,588, filed May 6, 2011 (and entitled, “Corner-Cube Irradiation Control”), which is incorporated herein by reference in its entirety.
• the sheets must be positioned as orthogonally as possible to the direction from which it is anticipated the reflections will come in order to send the energy back to exactly the point from which it was reflected from the can.
• Figure 9 shows corner cube reflection sheets arrayed around the can but beyond the “no fly zone” through which the cans must travel on the conveyor. Great care must be taken that the cans do not touch anything or the ink will be smeared.
• the concept which must be executed effectively is to maximize the amount of narrowband energy that impacts the can directly and then to harness as much of the reflective energy to return it back to the inked outer surface of the can as possible.
• the laser arrays can be aimed and focused very precisely, it facilitates having a high concentration of energy which will heat the ink and cans very quickly. If the energy is focused on the side wall of the can as it is passing, it will really only be focused properly for a short moment and then it will be aiming between cans and wasted.
• One solution to this is to articulate and track the can as it goes past with a servo or galvanometer controlled mirror such that the energy will continue to be focused in the right location on the can body for a more extended period of time. While this is a viable solution, it requires extra mechanism and sophistication which then could bring maintenance and setup problems.
• Another solution is to turn off the array when the can is not in its area of focus.
• the array would then be turned back on at the desired timing when the next can is coming into its view. If this is done strategically, one can conserve on power supplies by arranging the positioning and therefor the timing so that two or more arrays can share the same power supply. The DC power from the power supply would simply be switched to whichever array needs the power at that timing moment.
• An additional way of augmenting the quick heating to cure the ink would be to inject some or all of the heat into the inside of the can. This has the advantage of not requiring so much reflection management because energy that is injected into the open top of the can bounces around inherently until it is either absorbed or bounces completely out of the can. By locating one or more highly focused arrays so that its energy is focused into the open end of the can and timing a powerful pulse of energy at the time when the can’s opening is perfectly aligned with the focal pattern, it is possible to inject the energy in to provide fast heating.
• the photonic energy cannot be turned on for longer than just a momentary pulse before the can is no longer in the correct position, it will usually be necessary to have a series of arrays that are sequentially injecting more energy as the can proceeds along its path through the high speed, narrowband oven. It is, however, possible to push laser diode arrays to a much higher current input level for the momentary pulse compared to steady state operation.
• There are other ways of injecting high powered, narrowband photonic energy into the open end of the can by designing the material handling means to make the can available either in an indexing way or with continuous tracking similar to the concepts taught for the inside bake oven. The only significant difference is that the can will likely have to be held by a vacuum to keep the ink from bumping or being scuffed/smeared by anything.
• One advantage of using electric or narrowband irradiation throughout the can plant is the complete elimination of hydrocarbon fuels, CO2, nitrous oxides and some other pollutants through the entire process from aluminum coil to finished can.
• Another advantage of eliminating the hydrocarbon fuels, CO2, nitrous oxides and other combustion pollutants is the dramatic improvement in public relations with people who live near the plant which may be producing smelly or noxious pollutants from one of the ovens. Continual maintenance is necessary by sometimes unavailable knowledgeable people to make sure the combustion is clean, properly scrubbed, and the ovens are properly maintained and optimized. Environmental advocates are very much opposed to natural gas or hydrocarbon-fueled ovens in a can plant.
• Another advantage of using electric or narrowband irradiation throughout the can plant is the ability to use renewable fuel sources to power the entire plant such as windmills, hydro-electric power, and solar panel/photo-voltaic cells.
• Another important advantage to implement the quick, narrowband technology for curing and drying is the ability to save a substantial amount of aluminum in the process, which can be from 10 to 14%. Because there are so many differences in the can making tooling, reduction steps, and oven treatments the savings in aluminum is a function of many variables that can be addressed to optimize the savings. A can of the same strength can be manufactured with less aluminum by manufacturing it from thinner coil-stock material. An alternative major advantage is to save a substantial amount of aluminum required to manufacture a can by staying with the same starting coil-stock thickness but changing the tooling to manufacture the same essential can shape, liquid capacity, and specification from a smaller diameter blank which ultimately will allow the can to be formed with selectively thinner sections.
• a further benefit of these advantages is the ability to manufacture a given number of cans from a narrower coil-strip of the same thickness.
• Yet another advantage of implementing narrowband technology for these applications is that it saves raw material resources in multiple ways. It reduces carbon footprint, processing costs, and raw materials all the way through the aluminum manufacturing and can commercialization process. It saves on transportation costs from the aluminum rolling mill to the can manufacturing plant, from the can manufacturing plant to the filling plant, from the filling plant to the distribution warehouse, from the distribution warehouse to the retail store, and from the retail store to the consumers who use the product. It also reduces the tonnage and resources involved in the recycling stream. Because the cans made in this way will be thinner, they will be crushed and briquetted more easily and will be melted with less energy for remanufacturing/recycling.
• the narrowband technology is digital, programmable, and highly controllable, it is not necessary to heat the cans beyond the ideal temperature, thus saving energy and preventing any unnecessary metal weakening or annealing.
• Yet another advantage of implementing any of these ovens with narrowband technology is the ability to close the loop by using infrared sensors, thermocouples, or infrared cameras to ascertain the temperature of the cans and then modulate the narrowband energy delivery to keep the energy usage and temperature optimal.
• the correct width of irradiation energy projection can be used to conserve energy. If, for example, several upstream body makers and trimmers are not being utilized because they are being maintained or for other reasons, a narrower stream of cans can be processed through the oven without wasting the extra width that would be inherent with the conventional, broadband oven.
• the current broadband ovens offer only the choice of all or nothing as to whether they will be turned on or not. This will also be an advantage during reduced or modulated production periods, facilitating the matching of production output to demand or need.
• Another advantage of the technology when used for mass conveying is the facility to measure the temperature of the cans across the width of the conveyor and then close the loop to correct the temperature quickly so as to not over or under heat the cans.
• the temperature can be measured by positioning several non-contact sensors which could be infrared sensors or infrared cameras to verify the temperatures and then send that information to a control system which controls the irradiation arrays to modulate the output or the conveyor speed accordingly.
• the temperature can also be modulated across the width of the conveyor or anywhere across the mass of the conveyor if it is not heating consistently across the conveyor or if convective air currents or something else is cooling some cans more than others.
• a further advantage for the narrowband pin chain oven is the possibility of sharing power supplies between two or more arrays. With good planning, this reduces the number of power supplies required to implement a system, and thus reduces the system cost. If implemented correctly, it could also extend the life of the power supplies by producing less severe thermal cycling of the electronic components.
• a further advantage of maintaining the strength of the aluminum is that it increases bottom reversal strength which then allows greater pressure to be built in the can safely for the same thickness can material.
• Another advantage of maintaining the full strength of the aluminum is that the can could be manufactured out of thinner material and still have the specified strength of a can made the conventional over-built way.
• the advantage accrues from maintaining the full strength of the aluminum that a narrower cut strip coil can be used to produce smaller diameter blanks which then produces a smaller diameter cup from which the balance of the process can proceed. This facilitates making a similar strength can from roughly 10 to 14% less aluminum.
• the advantage accrues that a stronger can may be manufactured with the same exact tooling and aluminum substrate.
• a further advantage of implementing narrowband technology for the pin chain oven would be a dramatic reduction in the ambient heat released into the plant near the oven and a dramatic reduction in the sound pressure level produced by all the moving chain/belt components and the convection blowers.
• a further advantage of this technology is the ability that it gives the implementer of the technology the ability to aim, focus and control the energy very precisely.
• the best type of narrowband devices with which to implement this technology is typically laser diodes because they can produce very high power levels very straightforwardly, especially when configured in massed arrays thereof. Fiber lasers and other narrowband devices can be utilized.
• any type laser device even though infrared devices would typically be chosen, the output photonic or light energy can be shaped with similar modalities to those used for visible light. Therefore, any of refraction, diffraction, reflection, and diffusion components can all be used very effectively by someone implementing the presently described embodiments to assist in getting the energy where it needs to be at the right time and intensity. This is very important to get the overall systemic efficiency and to get the speed of heating that creates so many advantages.
• the narrowband pin chain oven if implemented well, eliminates the need to turn or rotate the can while it is passing in front of the irradiation units. Because of the precision of the aiming and because there is space between the cans, all 360 degrees of the can’s perimeter can be precisely irradiated without rotating the can.
• the narrowband drying oven would be configured to function as a mass conveyor to replace, supplement, or augment the gas dryer oven (614), for example, referenced in the system described in Figure 6.
• Figure 12 shows an overhead view of a mass conveyor. It shows the bottoms of the cans (121 ) because the cans are inverted so that they will drain with the assistance of gravity.
• the belt material (112) is shown moving the mass of cans in a direction (114).
• the belt (112) simply needs to, at some level, be transparent to the wavelength of light or irradiation that is being used by the narrowband irradiation sources.
• mesh fabric that is very open weave, or some sort of chain- mail or chain-link belting material.
• it needs to have a very high percentage of open space on a cross sectional basis in the vertical direction.
• the idea is to be able to pass the maximum amount of light and not cause too much back reflection.
• Thin, strategically shaped and hinged, vertical metal slats which have substantial cross section in the vertical direction and very little cross section in the horizontal direction can work very well because they will provide strength across the width and length of the belt and yet still provide a lot of pass through space in the vertical direction.
• the vertical sidewalls of such hinged conveyor pieces can provide terrific reflections off their vertical sidewalls, which will end up assisting in the heating process as it reaches the cans.
• Whatever material is chosen for the belting material it must be able to handle the heat of the irradiation at a very high duty cycle, and must also be resistant to any remaining dripping hydrofluoric acid or hot water.
• the belting needs to be structurally rigid enough that it doesn’t sag across the width of the belt, causing problems with the can travel and positioning.
• the belting material (112) is supported by the frame (111) along the edges and additional structure (110).
• the additional structure (110) will be configured as is necessary to structurally position and align all of the sections and components of the conveyor and the drive components for correct functionality.
• the section of the belt (112A - Figure 13) which is immediately under and carries the cans should be driven such that it pulls the belt through the work section of the oven rather than pushing it through. It must transport the cans away from the acid and deionized water rinse baths while the return section of belting (112B - Figure 13) will be moving below the top structure and below the irradiation units.
• a railing structure of some sort (113) which simply functions to keep the cans corralled and moving together in a pack so as to not separate or slide off the conveyor.
• the implementer of the presently described embodiments should always be aware of laying out the configuration of any of the narrowband irradiation so that it cannot find bounce paths out of the oven and into eyes in any way.
• Baffles and shrouds or turning corners under or within the shrouds can usually be used effectively to make sure that the energy has made enough bounces to reduce its concentration or weaken its intensity to a safe level before it can exit the conveyor’s covering. No matter what, the energy must be sufficiently absorbed or diffused to safe levels before it can find a path to leave the oven.
• signage must be properly positioned to warn people or operators of the inherent dangers that must be avoided with powerful IR radiant-energy based systems.
• control system may function to monitor (through, for example, suitable sensors) whether personnel enter an area of concern or whether undesired energy is not contained.
• Figure 13 is a cross sectional view of the conveyor along its length. It shows the cans (121 ) riding on the belt (112A) with the closed, dome end of the cans up.
• the irradiation arrays are positioned in irradiation housings (130), the number of which is dependent upon how much total and local irradiation power is required for the particular application and speed. It should be well known and understood by the implementer of the presently described embodiments what the irradiation power density is from the arrays that are employed.
• One type of standard narrowband laser array that is available, can put out somewhat in excess of 300 watts of radiant photonic energy. Positioning such arrays edge to edge with one another along the length of housings like 130, allows for a continuous irradiation output across the width of the belt (112).
• the output pattern must be well understood so the arrays or individual devices can be positioned to provide for a relatively homogeneous energy field at the location of the target cans. With great engineering care, enough of these arrayed banks in housings like (130) can be positioned along the length of the conveyor (111 ) to provide sufficient irradiation power with excellent consistency of power density for nearly any drying application.
• the face of the arrays (141) are facing up through the mesh belt and into the open ends of the still straight-walled cans (121 ).
• the irradiation (151 ) can be roughly reflectively guided by the baffle reflectors (132) so that the energy goes toward the target. It is possible to use lenses, micro-lens arrays, or diffusers as may be chosen, to spread or narrow the beams accordingly to provide for the best energy entrance into the cans. Since some liquid water will probably still be dripping out of the cans, especially in the early part of the drying operation, optically transparent windows (133) can be placed to protect the arrays from direct dripping water.
• the windows are, in at least one form, optically transparent or transmissive at least at wavelength(s) and/or wavelength range(s) applied in the drying process.
• the protective windows (133) are best mounted at a slight angle to promote water runoff like a roof.
• the protective windows (133) should be properly sealed where they meet with the reflective structures (132) so that it does not allow water or liquid moisture to enter the enclosed chamber.
• the protective windows may also be provided with an anti-reflective coating that is functional at applied wavelengths or wavelength bands. Gravity will carry liquid water down the slope of 133 into drainage troughs or gutters (134) which can be suitably positioned on or near the edge of the protective window to carry off any liquid water. In any event, it is wise to arrange the system so the arrays are protected and not vulnerable and are not subject to water nor any other random contaminants that may tend to fall off the belt or from inside the cans.
• the fundamental narrowband devices are most typically laser diodes. They are generally assembled in to arrays of from dozens to hundreds of devices (141 ). Their efficiency can vary substantially and are typically some place between 20% and 65% “wall plug efficiency”, depending on many factors. The wavelength chosen for implementation is the biggest driver of the efficiency but the style of device chosen is also a determinant.
• One of the best devices for their combination of efficiency, and overall robustness are surface emitting devices. Specifically, SE-DFB devices have proven to be robust performers but can be run in series to facilitate ideal drive voltages for great cost efficiency and practicality.
• Lamellar air flow can be used immediately under the belt (112A) to continually change the airspace between the irradiation array protective glass (133) and the bottom of the belt (112A). In at least one form, higher speed air flow may be provided at the mouths of the cans to remove water vapor more efficiently.
• the implementer of the presently described embodiments will have to be careful to provide enough airflow to augment the irradiation for effective drying but not so much flow or air pressure that it tends to lift the cans (121 ) off of the belt (112A).
• the system may well have additional blowers to blow-off or help dry water that may collect in the domes of the cans (which are upside down).
• the blowers may function before or during the drying process.
• FIG 10 it should also be appreciated that, although a pin chain conveyor is shown in this example embodiment, other types of conveyors such as, e.g., vacuum or belt conveyors may also be implemented.
• the pin chain conveyor is depicted in Figure 10 with an enlarged link belt (162A), which is shown for conceptual clarity.
• An array of sprockets is positioned in a single plane but such that the link belt is zig zagged through the oven with 8 to 15 feet straight sections between each sprocket.
• the purpose for the zig zag or serpentine weave is to extend the time that the just-inked cans spend in the oven.
• the plane of the serpentine weave of link-belt is tilted back somewhat so that gravity will help the cans stay on the pins during their high-speed ride. Since the ink is wet, it is crucial that nothing can touch the outer cylindrical perimeter of the can because it will smear the wet ink.
• the pins (161 ) which form a long extension of the hinge pin, every so many joints of the belt, are by design somewhat longer than the can’s depth. In this fashion, the cans are held away from each other and away from the link belt and with space between them so that they can dry effectively in the oven.
• Figure 10 shows how the cans are supported by the pins during their transport through the pin- chain oven.
• the cans have some degrees of freedom.
• can 122A is merely perfectly centered relative to the pin (161 ) on which it rides.
• A can may sometimes find itself in that position because of jostling, gravity, or centripetal force created when the belt zings around one of the sprockets. But more typically they settle into a position like 122B when the current weave of the conveyor is against gravity in the direction (164), but the same can may jostle and reposition in to, for example, the position like 122C.
• the cans move around slightly on their pins, they are held away from one another so they will not smear the ink.
• the presently described embodiments can be implemented with the pin-chain configuration similar or even identical to what it is currently.
• Figure 9 shows a curing or irradiation station and a view along the long axis of a pin (161 ) similar to the view of the multi-link conveyor (162B).
• Figure 9 shows a can (122) which is moving past the array assembly housing (143) such that it can irradiate it with nearly orthogonal arrays on the portion of the can that most nearly faces or is orthogonal to the array (143).
• a portion of the irradiation may also be aimed or directed to cure bottom coating that may have been applied by a bottom coater in the system (see, e.g., Figure 6).
• a bottom coater in the system
• an encoder would track the progress of the conveyor (162) such that the control system can turn on the DC electrical to array (142) to send powerful narrowband irradiation toward the perimeter of the can that is nearest the array.
• the ink is very thin so the energy will penetrate through the ink while some of the energy is being absorbed immediately and directly into the ink, much of the photonic energy will travel on through and impact the aluminum can body (122) which is the substrate under the ink.
• the aluminum can body Upon impacting the aluminum can body, it will deposit some of the photonic energy into the aluminum and then most of the energy will reflect back. For a normal reflection off a simple flat reflective surface, the angle of incidence equals the angle of reflection. For each micro location, this is true but the collection of photons has a beam width. So, given that it is hitting a curved surface, the energy will reflect back in an imperfect curved spray. The engineering challenge is to not waste the reflected energy and to arrange mirrors or some sort of reflection devices to return it back to the can.
• corner cube reflection sheet (171 ) it will function to reflect the ray 155 straight back to very close to where it originated on the can body surface after the first reflection. That is, the corner cube reflector material or sheet(s) are strategically positioned such that irradiation reflected from the outer surface of the cans subsequently reflects off the corner cube reflector material back to substantially a location on the outer surface of the cans proximate to where the irradiation originally reflected. [00213] This process can then continue over and over until the energy is exhausted.
• Figure 11 is an overhead view of multiple curing or irradiation stations that are aiming at the can along its path.
• irradiation (152) being projected at the can at different angles so that ultimately after multiple irradiation stations, all surfaces of the can have been hit by direct photonic radiant energy.
• the irradiation housings (143) are placed along the conveyor at various angles to facilitate the direct radiant energy impacting the right locations on the cans (122).
• the implementer of the presently described embodiments can spread the arrays out so that more space is allowed around each array for the corner cube reflection sheet (171 ) or they can be placed closer together to reduce the temperature losses which will actually occur between the radiant energy doses at the different stations.
• corner cube reflector material or sheets of corner cube reflector arrays may be strategically positioned relative to each curing or irradiation station to be substantially orthogonal to a tangent of the outer surfaces of the cans and between the arrays.
• the plurality of irradiation stations are, in at least some forms, configured such that the arrays are positioned at different angles designed to cure ink or coatings around the entire surface or entire periphery or circumference of each can.
• Figure 14 shows a pin chain conveyor that is brought gradually closer to a vacuum flat belt conveyor (183) which has an angle (186) between the plane of the top of the cans on the pin chain conveyor compared to the plane of the surface of the vacuum belt (182).
• the vacuum plenum (185) will draw air through the vacuum holes in the vacuum belt (182) in order to pull the bottom plane (the plane on which and opened can would rest on a table) of the can firmly against the vacuum conveyor belt.
• the system is provided with heating systems/subsystems and suitable destruction systems/subsystems to address undesired Volatile Organic Compound (VOC) emission during the curing process.
• VOC Volatile Organic Compound
• undesired VOCs may be generated and emitted during the curing process of the inside of can coatings and also during the curing process of the ink on the outer surface of containers.
• a heating system/subsystem is provided to a venting configuration for the curing process to maintain a threshold temperature of the VOCs to prevent disadvantageous collection of the VOCs, for example, plating of the VOCs in an undesired manner and/or location, until such time as the VOCs reach a destruction system/subsystem, such as a catalytic destruction system including, for example, a catalytic oxidation system and/or a thermal destruction system including, for example, thermal incinerators, oxidizers or afterburners, to destroy or burn-up the undesired VOCs and other outgasing from the curing.
• a catalytic destruction system including, for example, a catalytic oxidation system and/or a thermal destruction system including, for example, thermal incinerators, oxidizers or afterburners, to destroy or burn-up the undesired VOCs and other outgasing from the curing.
• the threshold temperature is at least approximately 290 degrees Fahrenheit inasmuch as the VOCs generated during the inside of can curing process contemplated herein typically condense at temperatures below such a threshold.
• the threshold temperature will vary depending on the application and the types of VOCs actually generated and sought to be conveyed away or removed from the area, and in most cases destroyed.
• the inks applied to the outside of cans may have different VOCs or vaporous products generated during curing.
• suitable heating systems or subsystems such as heating coils
• suitable heating systems or subsystems are provided to heat the vent tubes in, for example, Figure 7, to maintain sufficient temperature of the VOC until transported to the catalytic converter station.
• the vacuum ports or vent tubes 75 in at least some embodiments, may be provided with a heating arrangement, such as heating coils 310, to maintain a minimum threshold temperature in the vacuum port while the vapors, including VOCs and other generated compounds, are drawn away from the curing process.
• the vent tubes 75 may take any of a variety of configurations to achieve the objective of drawing the unwanted vapors away from curing process.
• vent tubes 75 are shown as including, in at least some embodiments, a heating arrangement such as a heating coil 310; however, the heating coils 310 and their implementation in conjunction with the vent tubes 75 could also take a variety of forms.
• the heating coils 310 could be positioned within the passageway of the vent tube or positioned on the outside of (e.g. wrapped around) the vent tubes.
• the vent tubes could be configured with multiple layers with the heating coils positioned between layers, as shown as an example in Figure 7 (cross-section A-A). Insulated outer layers could be provided to reduce the lost heat and reduce the cost of keeping the inner walls of the tube at or above the minimum threshold temperature. Still further, other suitable heating mechanisms could be implemented to supplement or replace the heating coils.
• the vapors emitted during the curing process are then transported through the vent tubes 75 to a catalytic destruction system or unit or thermal destruction system or unit 350 to be broken down, expelled or eliminated.
• This architecture is only shown in Figure 7 representatively; however, a network or system of vent tubes 75 extending from the curing station may be implemented in any of a variety of suitable manners that will be apparent to those skilled in the art upon reading this disclosure.
• the thermal or catalytic destruction unit 350 could take a variety of forms.
• the destruction unit may take the form of, for example, a catalytic destruction system such as, for example, a catalytic oxidation system.
• the destruction unit may also take the form of, for example, a thermal destruction system such as a thermal incinerator, oxidizer or afterburner.
• a ventilation unit 320 could be positioned to carry vapors including VOCs and other generated compounds to a thermal or catalytic destruction unit 350.
• the ventilation unit 320 may take a variety of forms and may be positioned in a variety of different locations (e.g. near the top of the container 22) to implement its functionality.
• suitable vent tubes 375 including vent tubes with a heating mechanism such as heating coils may also be implemented to carry the vapors from the ventilation unit 320 to the destruction unit 350.
• vent tubes 375 are directly connected to the element 240 (in place of or as a supplement to the ventilation unit 320), similar to the vent tubes 75 of Figure 7. As with the vent tubes and destruction unit of Figure 7, these components may take a variety of forms, including those described above and others.
• a suitable ventilation system such as representatively illustrated ventilation unit 330 could be provided to carry away and eliminate unwanted VOCs.
• ventilation tubes or ports 375 such as vent tubes 75 of Figure 7
• suitable heating features such as heating coils 310) could be implemented to carry vapor, including VOCs and other generated compounds, away from the curing oven to a catalytic or thermal destruction system or unit 350 for processing and/or elimination.
• the ventilation units 330 could be positioned outside, above or alongside the curing stations of Figure 9 or 11 .
• the ventilation units 330 may also be positioned within the reflector arrays or between the reflector arrays as may be appropriate.
• the vent tubes could be positioned in a variety of locations (with or without the ventilation units 330) to receive and convey the vapors to the destruction unit 350.

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• 2021
  • 2021-06-10 KR KR1020237000781A patent/KR20230033704A/ko active Search and Examination
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